• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    The pressure sensitive adhesive article includes a substrate having a layer of pressure sensitive adhesive formed thereon. The pressure sensitive adhesive includes an elastomer having an elastomer component that is partially oriented and partially crystallized. Also described are methods of making such adhesive articles.
    公开号:KR20000064434A
    申请号:KR1019980704568
    申请日:1996-11-08
    公开日:2000-11-06
    发明作者:제이. 야루소 데이비드；디. 하이드 패트릭
    申请人:스프레이그 로버트 월터；미네소타 마이닝 앤드 매뉴팩춰링 캄파니；
    IPC主号:
    专利说明:

    Pressure sensitive adhesive article based on partially oriented and partially crystallized elastomer
    Typically pressure sensitive adhesives ("PSAs") are provided in the form of an adhesive adhesive coating applied onto a backing (such as a polymer film, metal foil, paper, cloth, tape or sheet made of release liner, etc.). . Such adhesives are useful for adhesive bonding together by lightly pressing the two sides with a finger to form a relatively weak bond, usually the bond can be easily broken by peeling off the adhesive coated tape or sheet from the surface to which it is bonded. It is desirable for the adhesive coated tape or sheet to be able to be removed without damaging the surface and leaving no residual adhesive behind. PSA articles currently in wide use are masking tapes of the Scotch ™ brand manufactured by 3M Corporation, which began using rubber-based PSAs for such articles in the late 1920s.
    A solvent free hot melting process for the preparation of PSAs from viscous nonthermoplastic elastomers, such as natural rubber, polyisobutylene and other hydrocarbon elastomers, was issued on May 26, 1994. PCT International Patent Application WO 94/11175 (of the assignee herein). The process involves a continuous compounding device with alternating conveying zones and process zones where the elastomer is crushed to mix the elastomer, tackifier and adjuvant to form an adhesive. Use The molten adhesive may be pumped onto the support directly in a thin film form via a coating die, which preferably consists of a movable web passing around a heated coating roll.
    Japanese Patent Publication No. 7 (1995) 18227, published January 20, 1995, discloses an anisotropic adhesive material having an adhesive layer formed on at least one side of a base having anisotropic flexibility and a corrugated or cordlike structure. adhesive material).
    United States Patent No. 5,156,911 issued October 20, 1992, describes a surface-activated, temperature sensitive adhesive assembly. In one embodiment, the adhesive, which is substantially non-viscosity below room temperature, has viscous viscous at the skin temperature, but returns to a substantially non-viscous state upon cooling (by adding ice, cold pack, etc.). Regardless of the embodiment, the adhesive comprises a crystallizable polymer that can be crosslinked. A similar material is described on page 39-41 of "Temperature Switchable Pressure Sensitive Adhesive" issued by Adhesive Age in September 1993 by R. Clarke et al.
    Adhesives having anisotropic peeling behavior (i.e., adhesiveness when peeled off in different directions) are desired. Such adhesives will be useful in many applications, such as graphics tapes and other uses described in more detail below. Substantial flexibility can be exercised in the selection of the base if an adhesive article having such properties can be provided independent of the base. It would also be desirable if known adhesive compositions could be prepared in a manner that provides such properties. In addition, a heat activatable tack adhesive is desired, which would be useful in situations where it would be advantageous to have a low initial viscosity, especially if known adhesive compositions can be prepared in a manner that provides such properties. Because it is.
    The present invention relates to pressure sensitive adhesive articles consisting of a substrate or backing coated with a pressure sensitive adhesive, a hot melt process for producing such adhesive coated supports and the use of such articles. More specifically, the present invention relates to articles comprising pressure sensitive adhesives of partially oriented and partially crystallized elastomeric components, in particular preferred embodiments the elastomeric components impart anisotropic peel behavior to the adhesives. do.
    The invention is more fully described with reference to the following non-limiting drawings.
    1 illustrates one embodiment of a continuous blending and coating line of equipment or apparatus that can be used to perform the solvent-free hot melting process described above for producing a PSA article according to the present invention.
    FIG. 2 shows one embodiment of the extruder screw design or blending apparatus shown in FIG. 1. FIG.
    3 is a cross-sectional view of an elevation of one embodiment of a PSA article according to the present invention in tape or sheet form.
    4 and 5 are schematic isometric views of one embodiment of a PSA article according to the present invention used as a tape or sheet for graphic art for transferring text from one substrate to another.
    6 and 7 are schematic cross-sectional views of the elevation of FIGS. 4 and 5.
    8-11 are schematic plan views of a PSA article in accordance with the present invention, wherein FIGS. 9-11 show patterns of spatially variable regions with different reduced pressure viscosity.
    In one aspect, the present invention provides a pressure sensitive adhesive article comprising a substrate and a pressure sensitive adhesive layer on the substrate. Pressure sensitive adhesives comprise partially oriented and partially crystallized elastomers. Molecular repeat units that are repeated in the elastomer preferably exhibit some oriented orientation and some degree of crystallinity. "Some oriented" means that the elastomer is sufficiently oriented so that the orientation can be revealed by optical birerefringence, infrared dichroism or X-ray diffraction. "Some crystallized" means that the elastomer has sufficient crystallinity to be detected by differential scanning calorimetry or X-ray diffraction.
    Different orientations and extents or ranges of crystallization in the elastomer can have a beneficial effect on the properties of the PSA. For example, in one embodiment of the present invention, the orientation and crystallinity of the elastomer are sufficient to impart anisotropic peeling force to the PSA article (eg, substrate or support coated with PSAs). Anisotropic peel force is a unique property because the force required to peel a PSA article from the bonded surface depends on the axis on which it is measured. That is, PSA articles exhibit different adhesion when peeled off the surface in different directions. The orientation and crystallization degree of the elastomer causes (1) the peel force measured in the direction parallel to the preferred orientation, to be actually smaller than that observed for PSAs of the same formulation in which the elastomer is in an unoriented state, 2) may be sufficient to ensure that the peel force measured in the direction perpendicular to the preferred orientation is actually greater than that measured in the parallel direction. In general, the peel force in the parallel direction will be 90%, preferably less than 50%, most preferably less than 10% of the higher peel force (ie peel force in the vertical direction).
    When making a PSA article by extrusion of an adhesive, the preferred orientation of the elastomer will be generally the "machine direction" (or "MD") parallel to the extrusion coating line. The direction perpendicular to the extrusion coating line generally refers to the "cross direction" (or "CD"). For example, in the case of PSA coated tapes prepared by extruding hot melt tackified natural rubber PSA onto a continuous moving web support, the peel force of the tape is such that the tape peels off from its adhered surface in the extrusion coating line. It depends substantially on whether it is parallel to the machine direction (machine direction) or cross direction (i.e., perpendicular or transverse to the extrusion coating line).
    In general, the ratio of the peel force in the machine direction to the peel force in the cross direction is less than 1 and more preferably about 0.9 to 0.002. However, when the anisotropic PSA is heated to a temperature above the melting point of the oriented crystalline region of the elastomer, the PSA is essentially or substantially irreversible in an isotropic state, where the ratio of MD peel force to CD peel force is essentially one. Is converted.
    According to the inherent anisotropic peel force properties, the PSA articles (such as PSA coated tapes or sheets) of the present invention are used for graphic art applications (premask tape, prespace tape, graphic art film, die cut). (diecut) or dry transfer lettering (such as the graphic arts article described above in chapter 32) by Satas). In addition, the anisotropic PSA articles according to the invention can be used as base fastening tapes, wall decorative films or other constructs requiring differential peels.
    As the orientation and crystallinity in the elastomer increase, the orientation and crystallinity are relatively low (and include the same formulation, both in the machine and cross direction), and the PSA viscosity and peel resistance are much lower than the resistance of the PSA where the elastomer is not oriented and not crystallized. Is enough to give. However, when such low viscosity examples of PSA are heated above the melting point of the oriented crystallized elastomer, the elastomer crystals melt, the orientation is relaxed, and the adhesion properties (viscosity and peel resistance) are the same in conventional PSAs of the same formulation. It is converted irreversibly to typical higher viscosity and peel resistance. If the degree of orientation and crystallinity is sufficient to form relatively low viscosity and low peel force in both the machine and cross directions, these two adhesive properties will increase upon heating and will be essentially or substantially the same in both the machine and cross directions. . That is, the PSA layer will be isotropic.
    In yet another embodiment, the PSA article according to the present invention comprising an initial low viscosity adhesive layer is selectively heated to control the adhesion of the article to provide high and low viscosity spatially varying patterns of regions.
    The present invention also relates to various processes, such as adding a PSA article to a bonding surface to bond one or more substrates or objects together. According to another aspect of the present invention, there is provided a method of transferring one or more objects from one location to another by applying PSA to the surface of such objects and a process of transferring the obtained combined article to another location.
    In another aspect according to the invention, the PSA article is produced by a solvent-free hot melting process which can use the blending apparatus, pumps, dies and coating rolls and the like described in published PCT application WO 94/11175, the The process is described herein by reference.
    In one aspect, the process for producing a PSA according to the present invention comprises (a) an unmodified elastomer, usually solid, capable of uncured orientation and stress strain induced crystallization of uncured natural rubber or polyisobutylene, etc. Crushing or milling; (b) optionally mixing such elastomers with a viscosity inducing additive; (c) heating the crushed elastomer or elastomer / viscosifier mixture above room temperature (> 23 ° C.) to form a hot viscous material; (d) shearing, elongating, stretching or elongating the hot material such that deformation and stress are induced inside the hot material to partially align the elastomer molecules; And (e) cooling the resulting hot oriented composition at a temperature below the melting point of the oriented elastomer and at a cooling rate fast enough to partially crystallize in the elastomer in the oriented state.
    The hot viscous material may be stretched or extended, for example by extruding through a slot in an extrusion die. The film_extrudate can be coated or deposited on a support such as a biaxially oriented polyester film or release surface and then cooled to provide a PSA article according to the invention, such as a PSA tape or sheet. Cooling can be effected, for example, by depositing the PSA extrudate on a web (base) carried by a coating roll with cooled water circulating through it. Optionally, the hot, viscous elastomer-containing material and thermoplastic precursor of the backing may be coextruded as a laminate. PSA extrudates or coextruded laminates coated on the backing may be stretched and cooled to induce partial orientation and crystallization.
    The manufacturing process can affect the range of orientations and thus the properties of the PSA. For example, when the cooling rate is relatively slow, the cooled PSA may have high viscosity and isotropic peel force. As the cooling rate increases, the PSA will become less viscous and the peel force will be more anisotropic. At relatively high cooling rates, cooled PSAs can have significantly low reduced pressure viscosity and low or significantly fine peel force. The desired cooling rate (to form the desired orientation, crystallization and thus the desired degree of anisotropy, viscosity and peel force) will vary and the specific adhesive component used and the amount thereof, the temperature of the adhesive formed, the thickness of the PSA coating And the specific equipment and operating conditions used to make the PSA article (such as line speed) and the use or application of the article.
    In order for the PSA article to have the desired heat or solvent resistance for a particular application, the PSA may be cured or crosslinked. Crosslinked PSAs are particularly useful where, for example, the PSA article is a masking tape used for paint spraying operations and must undergo a paint stoving process. However, crosslinking processes involving heating are detrimental to maintaining orientation and crystallinity in the PSA.
    Referring first to FIG. 1 of the drawings, reference numeral 20 denotes a device or device that may be a single unit or a series of interconnected units for continuously compounding and processing the elastomeric components of the PSA used in the present invention. The apparatus 20 may be a twin screw extruder, such as a WernerPfleiderer ™ twinscrew extruder, ZSK30 or ZSK60 model. The device 20 has a continuous crossing and interconnecting section or section for transport. A plurality of metering hoppers 21, 22, 23 connected to the corresponding plurality of inlet openings is provided to convey the PSA component to the apparatus 20 at a controlled speed. A KTron ™ automatic lossinweight feeder or liquid addition device, such as a heated pail unloader or liquid metering pump, can be used to achieve this rate. An outlet 24 may be provided downstream or at the discharge end of the device 20 to discharge volatiles from the device 20. A melt pump 26, such as a ZenithNichols ™ gear pump, is provided at the discharge end of the device 20 to carry the hot melt of the synthesized PSA (ie, melted and blended PSA) at a controlled rate from the device 20. A filter 27 is disposed downstream of the pump 26 to filter out the metered hot melt to separate impurities. The filter 27 may optionally be disposed upstream of the pump 26.
    The molten PSA is formed by extruding from an opening or slot in a direct contact coating die 32, such as a flexible blade coater with a silicone rubber wiping blade attached to the top side of the die slot. do. The die may also be a rotating rod contact die. The die deposits, coats, smears or cleans the molten PSA extrudate, which is a continuous coating or film, to one surface of the movable web 34 to a desired thickness of, for example, 20­75 μm. However, the PSA need not be a continuous coating on the web. It may also be provided as a coating or film discontinuous in the longitudinal direction or in the cross direction. Web 34 provides a backing for PSA articles, and may be any desired, including biaxially oriented polyester or polypropylene, vinyl, cloth, paper, metal foil, and the like, commonly used as backing for pressure sensitive adhesive tapes. It can be made of a material. In addition, the web may be a release surface, such as a release liner.
    As the elastomeric component of the PSA melt flows out of the die 32 and is cleaned on the web 34, the formation and stress deformation of the elastomeric component of the PSA melt occurs. The web 34 passes over the guide roll 30 and is reciprocated to the orifice of the die 32 by a cooled coating roll or drum 35. The die 32 and coating roll 35 may be positioned relatively so that the PSA extrudate is deposited on the surface of the roll as shown. The roll 35 may be a chrome plated steel coating roll (particularly useful for flexible blade coaters) or a rubberized coating roll (particularly useful for rotating rod contact dies). Inside the roll 35 a temperature controlled cooling medium (such as circulating water) can be supplied to quickly cool or quench the molten PSA extrudate and orient and crystallize the elastomeric components to the desired degree. The molten PSA extrudate is cooled by transferring heat from the extrudate to the base cooled by the roll 35. If the roll 35 is rubber-coated, an additional chilled roll 36 may optionally be used to cool the surface of the roll 35 to essentially rapidly cool the PSA extrudate. Alternatively or additionally, a spray device 37 mounted or disposed over the coating die 32 allows cooling media, such as a membrane of misty water or cooled nitrogen gas, to the surface as the PSA extrudate exits the die. It can be sprayed to cool. An additional option is to precool the web 34 and coat the PSA onto a cooled web (acting as a heat sink). Another alternative is to cool the PSA coated web 38.
    The PSA coated web 38 may be wound and split or otherwise cut into the desired size or shape. As shown in FIG. 1, the web 38 may first be transported to a crosslinking station 39 where the PSA layer on the web is exposed to radiation at the radiation source 41. The radiation source 41 may be an electron beam (ie Electrocurtain ™ unit) or ultraviolet radiation. Spinning crosslinks the elastomeric component of the PSA and forms a crosslinked PSA coated web 42, which can be wound and cut to a desired size. In addition, release coatings and / or low adhesion backsizes such as those conventionally used in PSA tapes may be applied to the web before or after the molten PSA extrudate is deposited on the web. Other details of the illustrated mixing and coating equipment will be omitted for simplicity, such details are described in PCT application WO 94/11175.
    When coating on a relatively thin backing (such as about 25 μm thick), only the temperature of the coating roll can be controlled to achieve an effective quenching rate that forms the PSA elastomer component in the desired oriented and crystallized state. However, if the support is thicker, it may be necessary to employ additional cooling means, such as to quench the support prior to coating the PSA injection, or to add coolant or gaseous refrigerant to the surface of the extrudate. However, other means can be used. It is important that the cooling rate is sufficiently fast that crystallization occurs in the elastomer before the orientation induced by the forming and / or coating operation is relaxed.
    FIG. 2 shows a design of a screw extruder that can be used with the blending apparatus 20 of FIG. 1. In addition, hoppers 21, 22, 23 are provided for dispensing the respective elastomers, tackifying resins and antioxidant components of the PSA through the inlet opening to each of the different extruder sections 1, 5, 7. Shown. The elastomer is kneaded or crushed in section 2, conveyed and further crushed in section 3, mixed with tackifying resins and / or other adjuvants in section 5, and mixed with antioxidants in section 7. do. Further mixing and breaking up takes place in sections 6, 8. The extruder screw is suitably stirred or rotated to carry the PSA component from one section to the next, in the direction indicated by the arrows in the upstream and downstream zones 1x9. The extruder screw also kneads and breaks up the elastomer.
    The elastomer may be supplied as a warm mass to the device 20 from an external processing device. Optionally, the elastomer is transported in pelletized or bottom form and coated or powdered with powdered talc or other conventional parting agents so that the elastomer is stuck to the screw or inner wall of the extruder. prevent sticking. If aerobic processing is desired, oxygen-containing gases, such as compressed air, are injected into the extruder (e.g. at a pressure of 5100 psig (pound per square inch gauge) at a pressure of 30700 kPa), for example in section 3, to determine the molecular weight of the elastomer. It assists controlled reduction and facilitates the formation of PSAs. During processing of the PSA and its components in the extruder, a number of extruder sections are heated, for example to 160 ° C., optionally other auxiliaries may be added to the extruder and mixed with the elastomer and the tackifying resin.
    FIG. 3 shows a cross section of a PSA article 43 according to the invention cut from the web 38 or 42 of FIG. 1. The article 43 has a PSA coating 44 derived from a hot PSA extruder and a web or support 46, such as polyester or polypropylene, biaxially oriented.
    As noted above, in one embodiment of a PSA article according to the present invention, the degree of orientation and crystallization of the PSA elastomer is sufficient to impart anisotropic peel force to the article. Articles with anisotropic peel force can be used as graphics tapes useful for graphic art work (including premasks and freespace tapes). Die-cut graphics, for example, often take the form of such vinyl decals. Typically, the transfer print is formed by cutting from a sheet of colored, adhesive coated vinyl film, laminated to a release liner. After scraping off the waste or waste, the graphics tape is applied to the top of the die cut transfer print and lifted from the release liner while maintaining the transfer print registration. The transfer print is then transferred to the desired target substrate and the graphics tape is peeled off. Such graphics tapes require sufficient viscosity to reliably lift all components of the graphics (e.g. transfer prints in this example) from the release liner, but still must be easily peeled off after transferring the graphics to the target substrate and any graphics can be It should not be separated from. This harmony is often difficult to implement. When the PSA tape according to the present invention is used as a graphics tape, the tape can be removed by pulling in the high adhesion direction to remove the graphic from the liner, applying the graphic to the target substrate, and pulling in the low adhesion direction. Other graphics tapes do not contain die cut components, but still have the advantage that the graphics tapes have a very easy separation direction, since graphics can be very wide and difficult to peel off with conventional adhesives. If a conventional adhesive is formulated to have a small separation force, the ability to retain on the graphic is compromised. The anisotropic PSA tapes of the present invention may have a high holding capacity but still have a small separation force.
    An embodiment of a graphics article according to the present invention is shown in Figure 4-7. Embodiments include a tape or sheet (also in cross section shown in FIG. 3), denoted by reference numeral 43, comprising a PSA coating 44 with anisotropic peel force on the backing 46. In FIG. 4, the graphics article 43 is shown positioned on top of the release liner 51 which serves as the substrate for the PSA coated die cut letters 52 in the form of “E”. The bottom of the graphics article 43 is formed by the exposed surface of the PSA coating 44. After placing the article on the release liner 51, the tape is peeled off or lifted in the direction shown in Figure 4 by the vertical arrow (i.e., the high adhesion or cross direction indicated by the horizontal arrow indicated by "CD"). The die cut characters 52 are separated from the substrate because they are adhered to the PSA coating 44. This use of the graphics article 43 is further illustrated in FIG. 6, in which the PSA coated die cutting with the support 53 coated on the release liner 51 with the conventional isotropic PSA 54 respectively. Arrays of printed characters 52a, 52b, 52c, 52d, 52e, 52f are detachably attached in a desired pattern. 5 and 7 illustrate how die cut characters 52a, etc., affixed on the anisotropic graphics article 43 of FIGS. 4 and 6 can be detached from the article 43 and transferred to the destination substrate 56, respectively. It is shown. The textual attached graphic article is placed on the target substrate and the graphic article is peeled off the substrate in the direction shown in FIG. 5 by the vertical arrow (machine direction shown by the arrow indicated by "MD"). Thus, the letter 52, i.e., "E", is transferred to the destination substrate 56 as shown in FIG. 5, and the string 52a, etc., in the desired pattern on the destination substrate 56, as shown in FIG. Is transferred.
    Another application in which the anisotropic peeling behavior according to the invention can be used relates to the production of diaper fastening tapes. Due to the low peel force of the tape in the machine direction, the tape of a large stock roll can be unwound and converted without the aid of a release material. In the process of converting the stock rolls into individual tapes, the tapes can be cut so that the cross direction of the stock rolls in the high adhesion direction becomes the peeling direction on the completed base article.
    Yet another application of PSA articles relates to wall decor films. Anisotropic PSAs in such a way that the high adhesion direction is located vertically or downwards to the wall to prevent the fall due to gravity, while the low adhesion direction is horizontal to provide an easy separation direction without any damage to the wall. The article can form a graphic wall decoration.
    Another use of the PSA article according to the invention relates to a masking application using a maskant sheet or a drape adhesively fixed to a substrate to mask a large area of the substrate. . Mascot sheets or drapes are used in automotive painting or refinishing, and in commercial and residential wall painting, on areas where paper or plastic film is masked by taped to the body part or wall. Prevents overspraying of coatings overlaid. If the mascot sheet is relatively long and heavy, a constant peel force will be induced in the direction of the drape and the tape will peel off the substrate. The adhesive may be formulated to withstand greater stress induced by the weight of the drape, but the tape may then be difficult to remove completely from the substrate after the painting operation is complete. Anisotropic PSA tapes according to the present invention which exhibit low peel force in the machine direction and high peel force in the cross direction are useful for such masking applications. The tape can be made to have a high peel resistance or holding ability in the cross direction to withstand the peel stress induced by the weight of the drape, but only very low peel or in the longitudinal direction to tear off the tape without damaging the substrate. Has separation force. Heating the PSA tape can adversely affect its anisotropic properties, so passing the tape through a paint baking oven is not desirable.
    Another use for anisotropic PSA articles according to the present invention is adhesively bonded wall hooks or wall hangers, for example for picture frames. Such articles will have an anisotropic PSA layer that will have a high adhesion direction down the wall to prevent adhesion failure due to gravity or the weight of the frame. The wall hanger is pulled off the wall in the horizontal direction (low adhesion of the PSA layer), if desired, and then when the hanger is in a new desired position, the hanger is heated by, for example, a hot air gun or a dryer. By fixing in place, the position can be easily changed.
    Another embodiment according to the invention is a PSA article comprising a PSA layer of partially oriented and partially crystallized elastomer, wherein the degree of orientation and crystallinity of the elastomer is relatively low in both directions (and the elastomer in the adhesive layer is not oriented without crystallization). Is sufficient to impart viscous and peel resistance, which is much lower than the viscosity and peel resistance of articles of the same formulation that are not.
    One application of the aforementioned low viscosity PSA article according to the present invention is a pressure sensitive tape that does not require a low adhesive backsize (LAB) on the back side of an adhesive coated tape support. Such tapes are useful, for example, if desired to print directly on the back side of the tape. The process of printing on a number of commercially available tapes includes removing some or all of the LAB coating, printing on the back side of the tape using a standard flexographic method, and printing the LAB on the printing side. It usually involves a multistage process of the steps which are added again above. Since the PSA tapes of the present invention can be made to have a very low viscosity, LABs can be removed and indicia can be printed directly on the tape backing. The low-viscosity roll can then be rolled up again or LAB applied to the printed support and the heated tape to provide a printed tape having standard viscosity and peelability. Similarly, low viscosity PSA tapes according to the present invention can be used to produce linerless labels that can be printed in a low viscosity state and then heated immediately prior to use to restore viscosity and peel resistance. A low viscosity tape or label stock, for example, is transferred to a station that (1) prints the desired label on the backing with any conventional printing technique, and (2) is heated to increase the viscosity of the adhesive. It can run through a roller or wire, (3) cut into labels of the desired length, and (4) can be attached directly to the substrate. If printing is carried out by thermal printing during this process and the controlled production article is desired to be stored before use, the temperature required for printing may be used to melt the crystallized regions of the elastomeric components of the PSA and to relieve the orientation in the adhesive. It must be smaller than necessary.
    Another application of the low viscosity PSA according to the invention relates to the production of PSA tapes in which the surface viscosity of the tape is adhered to each other, although the surface viscosity is so low that the surface of the adhesive layer does not adhere to most other surfaces. Surprisingly, the low viscosity adhesive surface according to this embodiment of the present invention is actively adhered to itself or other similar low viscosity adhesive surface, although the adhesive surface is not viscous to contact. Such tapes are useful in a variety of fastening and closure applications, such as, for example, diaper closures, suture strips on envelopes and bags, garment fasteners, and other applications in which hook and loop fasteners are commonly used.
    Another application of the low viscosity PSA according to the present invention is that the bundling tape initially has a low viscosity so that it can detect a number of elements together with an adhesive tape but can slide slightly during bundling, after which the holding performance is increased when the bundle is heated. It is about a bundle operation which increases and does not slip. Such tapes are useful for wrapping cables, filaments, reinforcing fibers and other elongated members.
    In addition, PSA articles comprising low viscosity oriented adhesives may deform the PSA layer by zone heating techniques and impart high or high viscosity to the PSA layer of viscous and non-viscous regions that may be spatially varied. It can be treated to impart different adhesion properties to different areas, such as regular, random or patterned areas with low viscosity. This variant (shown below in FIG. 911 and described below) places a mask, such as a pure polyethylene terephthala art film, on the exposed adhesive surface of a PSA article according to the invention having a low anisotropic peel force in the machine direction. And by directing ultraviolet (IR) radiation toward such located exposure surfaces. The mask has a blackened portion that absorbs IR radiation and is laser printed in a predetermined arrangement or pattern, and passes or reflects IR radiation through the unblackened portion. The temperature of that portion of the PSA layer, which is located underneath the blackened area of the mask, is raised, for example, to 50 to 150 ° C. In this way, the oriented and crystallized PSA elastomer is thermally relaxed, thus increasing the viscosity of such heated portion in the PSA layer. The unwind noise of the PSA tape can be changed by varying the viscosity of the adhesive with space. In addition, PSA tapes comprising such patterned adhesives can be used for safety and tamper-evident applications where peeling off the tape can leave the adhesive of the selected pattern on the surface.
    In addition, the viscosity of the PSA layer can be selectively heated to increase viscosity, instead of patterning the adhesive or selectively de-visking the adhesive area with varnish or cover film. For example, a "pouch tape" used to form a pocket for holding invoices or other papers on a shipping carton is currently coated with adhesive on the entire surface of the backing, and then all but the periphery of the pouch. It is produced by coating the central portion with a varnish to weaken the adhesive in position. The document can then be placed at the center so as not to contact the active adhesive at the periphery, and then the pouch is pressure-sealed with exposed viscous adhesive at the edge of the pouch.
    Optionally, the pouch can be made from a low viscosity PSA tape according to the present invention. Place the paper directly on the low viscosity adhesive side of the tape and place it on the shipping carton as desired. The periphery of the pouch can then be heated, for example, with a heated iron that defines and heats only the periphery edges.
    Similarly, the low viscosity PSA articles of the present invention can be used instead of patterning an adhesive, and the patterned coating often requires an adhesive to be applied. For example, it is desirable that the adhesive is present only at the outer edge of the cover tape such that the adhesive only contacts the side rails of the carrier tape and does not contact the components held in the pocket of the carrier tape by the cover tape. Used for cover tapes for component carrier tapes. EXAMPLES It is difficult to achieve the precise match of the required adhesives, often a blocker film is used below the center of the adhesive coated cover tape to ensure that the adhesive side of the adhesive is held in the pocket of the carrier tape by the cover tape. Avoid contact with electrical components. Alternatively, the low viscosity PSA according to the present invention can be used on the entire surface of the cover tape, but can only be activated at the edge by heating and sealing the cover tape to the side rails of the carrier tape. Similarly, low viscosity PSAs according to the present invention can be used in applications where an adhesive patterned coating is required by only heat activating only the area of the adhesive for which sealing is desired.
    Any natural rubber previously used or intended to be used as an elastomeric component of PSAs based on natural rubber can be used in the preparation of PSAs used in the practice of the present invention. Uncured natural rubber is an amorphous material that is chemically unsaturated, unstressed or unstretched, and upon stretching, its molecules are stress strain-induced (at least in part) to be oriented and crystallized. Natural rubber hydrocarbons are essentially 1,4 'polyisoprene with a 100% geometric (cis) structure and have a small intrinsic viscosity (thus preferably combined with viscous resins for PSA use). Commercial natural rubber articles that can be used to make PSAs according to the present invention include ribbed smoked sheets and pale crepe, technically detailed rubbers such as SIR or SMR, and CV60 variants (1988). Visual graded rubbers known as controlled viscosity grades, such as KirkOthmer Encyclopedia of Polymer Sci. And Eng., Published by John Wiley E. Sons, Inc., incorporated herein by reference. to be.
    In addition, polyisobutylene useful as the non-thermoplastic elastomer component of PSAs according to the present invention is not easily crystallized in an unoriented state, but is similar in that it is crystallized by inducing orientation and stress deformation upon stretching. This elastomer only has a thermally unsaturated state. Polyisobutylene has inherent viscosity at low molecular weight, although often combined with viscous resins to achieve stable PSA properties. Commercially useful polyisobutylene articles that can be used in the present invention include high molecular weight, usually solid, articles such as Vistanex ™ MM L80. Low molecular weight polyisobutylene, such as Vistanex ™ LMMS, can be used to impart viscosity with high molecular weight modifications (see Vistanex® in the Supplies Report issued by Exxon Chem., Inc., incorporated herein by reference). Trademark) see detailed description of polyisobutylene).
    Viscosity resins useful as components of PSAs according to the present invention include resins which are usually liquid or solid, which are known to impart viscosity to PSAs based on natural rubber and polyisobutylene. Such resins preferably have a relatively lower molecular weight than the elastomer component and a higher glass transition temperature than the elastomer component. The main types of viscous resins useful herein include the following known wood rosin and derivatives thereof; Petroleum based resins; And terpenes. The amount of viscous resin used will be sufficient to impart the desired viscosity to the PSA, and the amount will generally be 10 to 400 parts by weight, preferably 20 to 150 parts by weight per 100 parts by weight of the elastomer. Particularly useful commercially available viscous resins for viscous natural rubber are Piccolyte ™ S115 terpenes and Escorez ™ 1310. A particularly useful commercially petroleum-based resin useful for the viscosity of polyisobutylene-based PSAs is the Escorez ™ 1310 viscosity agent.
    In addition, antioxidants such as Irganox 1010 tetrakis [methylene 3 (3 ', 5'etherbutyl4'hydroxyphenyl) propionat] methane, such as plasticizer oils of white mineral oil, Other auxiliaries commercially used in rubber-based PSAs, such as elastomeric oligomers, waxes, and inorganic fillers of, for example, talc, zinc oxide, titanium dioxide, aluminum oxide and silica, may be included in the PSAs of the present invention (such adjuvants). See chapter 2 of Satas, above, for a detailed description). Typically, the amount of antioxidant used will be up to 5 parts (per 100 parts by weight of elastomer based on weight), the amount of plasticizer will be 50 parts, preferably up to 20 parts, and the amount of filler will be up to 50 parts. .
    Materials that can be used as a backing or substrate for PSA articles according to the present invention include PSA articles based on rubber, including polymeric films such as flexible polypropylene and polyester films, metal foils, papers, ceramic films, and equivalents. Included above are used. Such support also includes a plurality of fibers in a woven or nonwoven mat-like structure. The other side of the base may be coated with a release coating or a low adhesive backsize and the PSA layer may be applied with a release liner. The backing and release coatings or liners are detailed above on pages 208 및 211 and 585­600 of Satas, which are incorporated herein by reference.
    Yes
    Although the invention is illustrated in the following examples, the particular materials, types and amounts of materials, and the equipment and process conditions described in the examples do not improperly limit the invention. In preparing PSA articles according to these examples, the equipment shown in FIG. 1 was used. In these examples, the orientation and crystallization of the elastomeric PSA component was measured at room temperature in combination of the techniques. After processing in the crushing section of the applicator, the molecular weight of the natural rubber was measured in terms of intrinsic viscosity (IV). In addition, the adhesive force and peeling force of the PSA article were measured. The technique or method of these measurements is as follows.
    Optical birefringence measurements of the PSA showed evidence of orientation in which the PSA had a different index of refraction for light polarized parallel to the machine direction compared to light polarized perpendicular to the machine direction.
    The crystallinity of the elastomer in the PSA was detected by X-ray diffraction analysis. The degree of crystallinity was assessed by differential scanning calorimetry analysis, which was determined to be low in these samples, ie on the order of some weight percent of the elastomer.
    PSA orientation was measured directly using a sample of PSA coated on the release surface of the film pretreated with the silicone release coating. Transfer multiple layers of adhesive from the release film to a clean glass slide (large quality required for the microscope but larger) from the release film by applying the glass slide to the adhesive side, cutting the adhesive around the edge of the slide with a razor blade, and lifting the slide. It was. This process was repeated as many times as necessary to obtain the desired number of adhesive layers, each time maintaining the relative orientation of the slide and coated adhesive. The slide was mounted on the sample holder of the optical bench.
    As indicated by the black line appearing in the center of the crosshair of the compensator eyepiece, the birefringence of the PSA sample was measured by adjusting the Babinet compensator so that the birefringence of the compensator is the same as the birefringence of the sample. J.L. was published in 1987 by John Wiely & Sons. The birefringence of the sample was measured by the calibrator setting, the wavelength of light (546 nm) and the sample thickness according to standard methods such as those described in White et al., Page 10, 605 of Encyclopedia of Polymer Science. The definition of birefringence is the difference in the refractive index of a sample for light polarized in two mutually perpendicular directions. In this patent specification, the complementary refraction value is the refractive index difference for light that is polarized parallel and perpendicular to the direction of the desired orientation.
    Fourier transform attenuated total reflectance (FT ATRIR) dichroism measurements were performed on some PSA articles according to the present invention to measure molecular orientation within the coating plane. The method is described more fully in J. Applied Spectroscopy 42 (7), 12581265 (1988) by F. Mirabella and in 22, 12831304 (1984) of J. Polymer Science, Polymer Physics. The Nicollet 10DX Fourier Transform Infrared Spectrometer used was mounted with an ATR accessory and a germanium (Ge) single diamond polarizer (Harrick, PSDJ1R). A Ge internal reflective element cut for 45 ° incidence was placed 22 ° from the normal to the beam between the polarizing element and the detector. The thickness of the crystal was measured 50 mm x 20 mm x 3 mm. The actual angle of incidence for the Ge crystal was calculated to be 39 ° due to refraction, which corresponds to a depth of penetration of about 1 micron when infrared energy was transmitted into the pressure sensitive adhesive coating. Absorption at 1130 cm −1 is sensitive to orientation in the sample, such that the IR beam is polarized along the machine (or beam) direction compared to when the beam is polarized along the transverse direction to the sample with anisotropic peel adhesion and molecular orientation. It was found that the absorption strength was higher. The incident IR beam was polarized parallel to the plane of the adhesive coating. Machine direction spectra were obtained when a PSA sample was subjected to an electric field vector of radiation parallel to the machine direction. Conversely, the cross web direction spectrum was obtained when the sample was subjected to an electric field vector parallel to the cross web direction. The intensity of the 1130 cm -1 band was measured as the peak height minus the baseline signal. This intensity is normalized by dividing it by an absorption intensity of 1095 cm -1 (also subtracted from the baseline signal), which is independent of orientation and can therefore exclude factors of sample contact surface artifacts for the MD and CD spectra. (normalization). In each spectrum, 50 injections for both background and sample were averaged. In each sample, the relative absorption of the 1130 cm -1 band for both the machine and cross web directions was measured. "IR anisotropy" is defined as the ratio of the normalized absorbance of the 1130 cm -1 band to the IR radiation polarized in the machine direction relative to the absorbance for the IR radiation polarized in the cross direction.
    Resistance to peeling of PSA tape under constant load was measured by a test referred to as adhesion at constant angle and stress (ACAS), a variation of PSTC 14 (Glenview, Illinois, Pressure-Resistant Tape Association). The static load peel resistance of the tape was tested in the following manner. A strip of 0.75 inch (1.9 cm) wide tape was cut with a laser cutter and applied to a polished stainless steel panel. In some tests, quartz substrates were used instead of stainless steel. Panels were cleaned between uses by wiping with Kimwipe ™ sheets each time, then washing with heptane three times with diacetone alcohol. The tape was laid on the panel with a 4.5 lb (2 kg) rubber coated 4 inch (10 cm) diameter roller that passed twice at approximately 12 inches / minute (30.5 cm / min). The wire hook was attached to one end of the tape strip. The tape was attached horizontally on the bottom surface of the panel. A 200 g weight was hung on the hook and the peel rate was determined by measuring the time to strip the 3 inch (7.6 cm) long panel. Peel resistance was calculated as the reverse peel rate in minutes / inch. The measurement was repeated and the peel resistance value was averaged. The results of using this test method are referred to herein as ACAS1. Optionally, the above test was performed using a quartz plate as substrate instead of stainless steel, and the optional test results are referred to herein as ACAS2.
    In addition, the peel strength at a fixed peel rate was measured using an Instron ™ universal test machine. The tape was cut into strips 1 inch (2.54 cm) wide and applied to a flat glass plate. Two passes of 4.5 lb (2 kg) rubber coated rollers were used to strip the holding force measurements described above. Glass plates with attached samples were mounted horizontally in sliding jigs on an Instron machine. The cord attached to the leading edge of the sliding plate was run through the pulley and attached to the crosshead. The tape tab was filled in a grip attached to the force transducer in the movable crosshead. The tape was peeled off by moving the croissant head up at a constant speed of 12 inches / minute (3.5 cm / min). The average peel force during peeling was determined. Peel strength is expressed as the force divided by the width of the tape. The results of this test are referred to herein as PL1.
    Another peel strength test was used for some test procedures. In this further test, a piece of biaxially oriented polypropylene (BOPP) film was applied to a stainless steel test panel with double sided PSA tape. The PSA tape article according to the invention to be tested was thinly sliced to 1 inch (2.54 cm) wide and then applied to a BOPP film and laid as described in the PL1 test described above. The tape was stripped by an Instron machine at a crosshead speed of 12 inches / minute (30.5 cm / min) at 180 ° peel angle. The average peel force was measured and calculated as the peel force divided by the tape width. The results of this test are referred to herein as PL2.
    A PSA tape according to the present invention was applied to the glass substrate 1 inch (2.54 cm) wide, rolled and peeled off at a peel angle of 180 ° and a peel rate of 90 inches / minute (228.6 cm / min) to form a third type of peel test. Was run. The results of the test are referred to herein as PL3. The same test method was run at a peel rate of 12 inches / minute (30.48 cm / min) and the results are referred to herein as PL4.
    Viscosity was measured by the rolling ball test method described in PSTC 6. A strip of adhesive tape was mounted on the base of the inclined plane with the adhesive side up. The stainless steel ball was released from the top of the inclined plane and the distance traveled on the adhesive surface was measured before the ball stopped. The result is the average of two measurements. The results of this test are referred to herein as RBT.
    The molecular weight of natural rubber after processing in the crushing zone of the extruder is often specified using intrinsic viscosity (IV) measurements. This technique is well known in the polymer sciences. The sample rubber was separated from the viscous agent supply port where the supply of the viscous agent was stopped. This sample insoluble in toluene was diluted to a concentration of 0.15 g / dl ± 0.02 g / dl. The diluted solution was centrifuged to separate insoluble components. 10 ml portions of the solution were transferred to a Cannon­Fenske glass capillary viscometer. The viscometer and solution were homogenized for 5 minutes in a water bath maintained at 25 ° C. The solution was then applied to the marked mark in the viscometer using a compression bulb and allowed to flow through the capillary of the viscometer. The time the solution flowed was measured with a stopwatch. This process was repeated for samples of pure solvent in the same viscometer. Precise polymer concentration was measured by transferring 20 ml of the solution into an aluminum drying dish previously weighed with a pipette. The solution was placed in an oven at 100 ° C. for 2 hours. The remaining polymer weight was then determined. All weights were determined using analytical balance with 0.1 mg resolution. IV (inherent viscosity) was calculated by the following relationship.
    IV = ln {(t solution / t solvent ) / c}
    In the above equation, t solution is the outflow time for the polymer solution,
    t solvent is the outflow time for the solvent,
    c is the polymer concentration (g / dl),
    ln is the natural logarithm.
    Example 1­4 and Comparative Example A
    All these examples were made with a single adhesive formulation and fixed extruder conditions. The formulation consists of the following ingredients.
    ingredientParts by weight Natural rubber (smoked sheet with ribs)100 Piccolyte TM S-115 viscosity imparting agent65 Irgnox TM 1010 AntioxidantOne
    The natural rubber supplied by the Goodyear Chemical Plantation Division was ground and transferred to the extruder at a rate of 68.4 g / min. The Piccolyte TM S115 Viscosifier was ground and dry mixed with Ifganox TM 1010 antioxidant at a weight ratio of 65/1 Piccolyte TM S115 / Irganox TM 1010, and the mixture was fed 45.1 g / min to the second feed port in the injection machine downstream of the rubber feed. Was transferred at a speed of. The extruder screw configuration shown in FIG. 2 was used in the rubber fracturing zone with air injection. The screw speed was 475 rpm and the temperature in the fracture zone was 172 ° C. Under these conditions, rubber IV was 2.0 dl / g. The line speed was 60 feet / minute (18.3 m / min) and the adhesive melting point at the die was 100 ° C. As shown in FIG. 1, rubber lip was used in the contact die with a chrome plated steel backup roll.
    The PSA extruder was rapidly cooled with a backup roll having a diameter of 30 cm and a circumference of 94 cm. The inside of the roll was maintained at the temperature of 15-50 degreeC using circulating water in Example 1x4. In Comparative Example A, the backup roll internal temperature was 70 ° C. In the entire example, a biaxially oriented polyethylene terephthalaart film (30 μm thick) was used as a support and coated to a thickness of 40 μm with a PSA extruder. In addition, a second sample was prepared by coating the same PSA extrudate on a support on a 50 μm thick polyester film with a silicone release coating formed on the side to which the adhesive was applied using the same conditions for each example. This second sample was made such that the adhesive could be transferred to a glass slide for a measure of elastomeric orientation by birefringence. The test results of the adhesives and tapes produced in this way are shown in Table 1 below.
    YesCoating roll temperature (℃)Birefringence Δn × 10 3 Rolling ball viscosity, RBT, cmACAS1sec / cm (minutes / inch)ACAS2sec / cm (minutes / inch)PL2N / cm (lb / in)Anisotropic IR MDCDMDCDMDCD One151.46.20.7 (0.03)43 (1.8)0.2 (0.01)66 (2.8)0.11 (0.06)1.05 (0.60)2.3 2301.92.20.7 (0.03)83 (3.5)-*---2.2 3400.322.11.9 (0.08)40 (1.7)1.4 (0.06)54 (2.3)0.12 (0.07)2.50 (1.43)1.8 4500.221.528 (1.2)52 (2.2)----1.1 A700.021.499 (4.2)135 (5.7)118 (5.0)139 (5.9)2.50 (1.43)2.45 (1.40)1.0
    * A dash in Table 1 means that no value is measured.
    Both birefringence and infrared dichroism data in Table 1 mean that the molecules of the elastomer in the PSA according to the invention in Example 14 were oriented significantly, and Example 14 was prepared by cooling the PSA extrudate to 1550 ° C. . The peel resistance data of Table 1 for the PSA article of Example 14 (under the headings ACAS1, ACAS2 and PL2) is a significant amount in the cross direction (CD) relative to the machine direction (MD), with higher anisotropy Correlated with large orientations. In contrast, in making the PSA of Comparative Example A at a higher backup roll temperature, i. Crystallization rarely occurred or occurred. The peel resistance values for the machine and the cross direction for Comparative Example A are not significantly different or almost the same, and the adhesion anisotropy is very low or intrinsically absent. Rolling ball viscosity data shows that the viscosity is actually reduced at high degrees of orientation.
    PSA prepared under the conditions for example 2 was coated onto a release liner and transferred to glass for X-ray diffraction analysis. The result is two diffraction peaks (not present in the spectrum by Comparative Example A), which are in accordance with the data reported in the literature for the crystallized natural rubber. According to the differential scanning calorimetry (DSC) analysis of this adhesive, an endothermic peak appears at 52 ° C by the heat of fusion of the adhesive of 0.2 cal / g. The literature values of the heat of dissolution of the rubber crystals given as 16.1 cal / g crystals calculated that approximately 2% of the elastomers in the PSA of Example 2 were crystals.
    Example 5
    Samples of the PSA article prepared in Example 1 were mounted in the birefringence setup described above. The PSA layer of the article was heated with a heat gun at a temperature of approximately 80 ° C. for 1 minute and the birefringence dropped below 0.01 × 10 −3 . The sample was substantially more viscous to contact after heat treatment than before heating, showing that heating to a temperature above the melting point of the elastomer's oriented crystallization can remove the oriented crystalline phase of the elastomer of the PSA.
    Example 6
    A portion of the PSA tape of Example 2 was added to the release liner and aged for 5 minutes at 65 ° C. in an oven. Another portion of the same tape was added to the same release liner and stored at room temperature (approximately 20 ° C.). The two parts were then tested for peel resistance by the ACAS1 method. Thereafter, two portions of the tape so treated were tested and the results are shown in Table 2.
    processACAS1, sec / cm (minutes / inch) MDCD Store at room temperature of approximately 23 ° C0.7 (0.03)83 (3.5) Heated at 65 ℃1800 (75) *1800 (75) *
    * Tapes are uniquely split
    The data in Table 2 shows that the oriented crystallized state of the elastomer of the anisotropic PSA according to the present invention can be removed by heat treatment, resulting in increased peel resistance and reduced anisotropic peel properties.
    Example 7 and 8
    For these examples, the extruder screw construction used was the same as shown in FIG. The screw speed was 400 rpm and the air injection port was blocked. In these examples, a controlled viscosity grade natural rubber SMR CV60, available from Goodyear Chemical Plantation Division, was used. Piccolyte ™ S115 viscous resin was transferred to the extruder zones (5, 7), and in Example 7, white mineral oil was added to the outlet in zone (9). Rubber IV under the operating conditions of this experiment was determined to be 3.5 dl / g.
    In Example 7, natural rubber CV60 was pelleted with a Moriyama extrusion pelletizer and acidified with talc. The rubber pellets were transferred to zone 1 of the twin screw extruder at a rate of 68.4 g / min. Polished Piccolyte ™ S115 viscous resin, premixed with Irganox ™ 1010 antioxidant at a ratio of 15/1 Piccolyte ™ / Irganox ™ , was added to zone 5 at a rate of 10.9 g / min. Undiluted Piccolyte ™ S115 was added to zone 7 at a rate of 44.5 g / min. The obtained formulation was as follows.
    ingredientParts by weight Natural Rubber CV-60100 Piccolyte TM S-115 viscosity imparting agent80 Mineral oil20 Irganox TM 1010 AntioxidantOne
    The PSA temperature at the coating die was 100 ° C. The same coating dies and rolls were used as in Example 1-4. The fluid circulated through the backing roll was controlled at 40 ° C. The line speed was 60 feet / minute (18.3 m / min). The adhesive was coated on the same polyester film as used in Example 1 × 4 with a thickness of 50 μm. The properties of the tape are shown in Table 3.
    In Example 8, the feed rate for transferring PiccolyteTM S-115 to Zone 7 was 34.2 g / m and the same conditions as in Example 7 were used except no oil was added to Zone 9.
    ingredientpart Natural Rubber CV-60100 Piccolyte TM S-115 viscosity imparting agent65 Irganox TM 1010 AntioxidantOne
    The line speed was 30 feet / minute (9.1 m / min). The fluid circulated to the backup roll was controlled at 40 ° C. The adhesive was coated by 50 μm on a crepe paper masking tape support approximately 100 μm thick. Tape test results are shown in Table 3.
    YesPL1 (MD), N / cm (lb / in)PL1 (CD), N / cm (lb / in)ACAS1 (MD), sec / cm (min / in)ACAS1 (CD), sec / cm (min / in) 70.5 (0.3)2.8 (1.6)2 (0.1)45 (1.9) 80.9 (0.5)2.1 (1.2)0.7 (0.03)4.2 (0.18)
    The data in Table 3 show that these selective formulations and supports can achieve anisotropic peel properties.
    Example 9­13
    For these examples, the extruder construct shown in FIG. 2 was used with a rotating rod die and a rubber coated back up roll. The air injection port of the extruder was closed and the screw speed was 300 rpm. The rubber surface of the backup roll was cooled by contacting with a chill roll, and the surface of the adhesive was further cooled as shown in FIG. 1 using cooled nitrogen gas and either liquid or water spray. The nitrogen was cooled by feeding liquid nitrogen into the perforated copper branch pipe. The liquid nitrogen partially evaporates in the transfer hose and branch pipes, forming a stream of cooled nitrogen gas as the liquid nitrogen slowly falls to the point of contact between the die and the web. A water spray was formed by feeding water at a metered rate to a set of needles arranged in a line approximately 0.25 inches (0.67 cm) apart. Compressed air was used to propagate two streams of impingement air from the branch, spray water, and deliver the spray directly to the web just downstream of the die so that the air flow meets at the line at the needle end. The adhesive was coated on polyester film supports of various thicknesses to a thickness of 40 μm. The line speed was 30 feet / minute (9.1 m / min). The adhesive temperature at the die was 150 ° C.
    The adhesive formulation for Example 9 is as follows.
    ingredientParts by weight Natural rubber CV­60100 Piccolyte TM S115 Viscosifier65 Irganox TM 1010 AntioxidantOne
    It was added to natural rubber to an extruder zone (1) to 68.4g / min, and the addition of undiluted Piccolyte TM S115 to the 13.7g / min Area (5), 45/1 Piccolyte TM S115 / Irganox TM 1010 mixture consisting of Was added to zone 7 at 31.5 g / min. Cooling water was circulated to the cooling nip roll at a temperature of 15 ° C. No cooled nitrogen gas or water spray was used in this example. The adhesive was coated onto a 100 μm thick biaxially oriented polyethylene terephthala art (PET) film.
    In Example 10, the same conditions as in Example 9 were used except that a liquid nitrogen cooling system was used to rapidly cool the PSA extrudate.
    For Example 11, the same conditions as in Example 9 were used except that the Piccolyte ™ S-115 article was replaced with Escorez ™ 1310 viscous resin and the adhesive was coated on a 50 μm thick PET film.
    In Example 12, the same conditions as in Example 11 were used except that a liquid nitrogen cooling system was used to rapidly cool.
    In Example 13, the same conditions as in Example 11 were used except that a water spray cooling system was used to cool rapidly.
    The tape properties of Example 9x13 are described in Table 4.
    Yes No.PL3 (MD), N / cm (lb / in)PL3 (CD), N / cm (lb / in) 91.42 (0,81)2.05 (1.17) 100.26 (0.15)1.56 (0.89) 112.40 (1.37)3.12 (1.78) 120.19 (0.11)3.59 (2.05) 130.18 (0.10)3.01 (1.72)
    The data in Table 4 shows that only cooling from the backup roll did not provide a high degree of anisotropy in the step of making a PSA tape with a relatively thick base formed on a rubber coated backup roll. However, the desired degree of orientation and anisotropy can be provided by liquid nitrogen or water cooling.
    Example 14
    In Example 14 and Comparative Example B, the extruder and the cooling station setup of Examples 9 13 were used. The fluid circulating through the rubber coated back up roll was controlled at 20 ° C. The cooling roll which cools the surface of a backup roll was cooled with 15 degreeC water. A liquid nitrogen cooling system was used with the second branch tube to cool the web prior to coating. The adhesive formulation was as follows.
    ingredientParts by weightTM Vistanex MM L-80 polyisobutylene62.8 Vistanex TM LMMS Polyisobutylene20.0 Excorez TM 1310 Viscosity Resin33.7 White mineral oil10.0 Irganox TM 1010 Antioxidant0.6
    Vistanex TM MM L-80 polyisobutylene was pelletized in the same manner as the CV60 natural rubber in the above example and transferred to the extruder zone (1). Vistanex TM LMMS polyisobutylene is a low molecular weight article that is a very viscous liquid. This material was heated and pumped into zone 5 of the blending apparatus using a heated fail unloader. Escorez ™ 1310 resin was transferred to zone 7 and mineral oil was metered into zone 9 using a gear pump. The antioxidant was premixed with the viscous resin and transferred with the viscous resin. The adhesive was coated on a 50 μm thick PET base with a thickness of 40 μm. The line speed was 30 feet / minute (9.1 m / min). The tape properties obtained are listed in Table 5.
    Comparative Example B
    The same conditions as in Example 14 were used except that Vistanex ™ MM L80 was replaced with Exxon Butyl 077 rubber in the adhesive formulation. In addition, the tape property of this comparative example is described in Table 5.
    Yes No.PL4 (MD), N / cm (lb / in)PL4 (CD), N / cm (lb / in) 140.18 (0.10)4.89 (2.79) Comparative Example B6.78 (3.87)6.31 (3.60)
    The data in Table 5 show that the polyisobutylene-based adhesive has strong peeling anisotropy, while the MD peeling force is less than 4% of the CD peeling force, but the material based on the butyl rubber formed under the same conditions It wasn't. The CD peel force was in this case slightly lower than the MD peel force at 93% of the MD value. The difference between Example 14 and Comparative Example B is due to the fact that small amounts of isoprene comonomers in Butyl 077 rubber prevent the crystallization of the rubber.
    Example 15
    The tape made according to Example 10 was cut to approximately 6 inches (15.2 cm) in length.
    By masking approximately half of the width of the tape, only a portion of the adhesive is heated such that the crystals are selectively melted and the orientation of the elastomer is relaxed, thus making it possible to selectively change the viscosity of the adhesive. The rolling ball viscous body (RBT) of the tape sample before predetermined masking or selective heating was 68 mm.
    Thereafter, a mask was prepared. More specifically, the pattern was laser printed on paper so that half of the paper was printed black and half remained unprinted. The paper was then conveyed through a Thermofax ™ photocopy machine with an infrared transparent film, while the film absorbed infrared energy from the machine and optionally darkened in dark areas on the paper. In this way, the transparent film mask patterned by semi-darkness and translucent is formed.
    The PSA tape is then patterned transparent (including an elastomer with some oriented and partially crystallized component) such that half of the longitudinal tape overlaps the dark patterned transparent area and the half overlaps the clean patternless area. It was applied to a film mask. To further protect the unmasked area of the PSA tape from the infrared absorption effect, a white tape that does not significantly absorb infrared energy is placed over the clear patternless area of the transparent film mask and within the overlapping area of the clear patternless area of the transparent film mask. It was laminated to the back side of the PSA tape. The laminate was transferred back through the Thermofax ™ machine, a machine in the apparatus of reference number 6, to cause the adhesive in the area overlapped with the dark pattern on the transparent film to be locally heated.
    The rolling ball viscous body (RBT) of each side of the tape was measured to find that the unmasked side was 38 mm and the masked heated side of the tape was 11 mm. From these data, the heating and the accompanying melting of the oriented crystalline component of the elastomer appears to occur even in the patternless area by generalized heating inside the Themofax ™ machine.
    Example 16
    By masking a second 6 inch (15.2 cm) tape sample prepared according to Example 10, it was heated in a spatially changing pattern so that high and low viscosities could be alternately patterned. The rolling ball viscous body (RBT) of the tape sample before any masking or optional heating was measured to be 68 mm. The pattern shown in FIG. 10 was formed using a computer drafting program and printed on paper with a laser printer. The paper was then transferred through a Thermofax ™ photocopy machine along with the infrared transparent film described in Example 15 to form a patterned transparent film mask with alternating dark and transparent lines shown in FIG. 10. Thereafter, a PSA tape (comprising an elastomer with some oriented and partially crystallized components) was applied to the patterned transparent film mask so that the mask lines were perpendicular to the length direction of the tape. The laminate was transferred back through the Themofax ™ machine in the apparatus of reference number 4, causing the adhesive in the area overlapped with the dark lines on the transparent film to be locally heated. The rolling ball viscosity (RBT) of the optionally heated tape sample was measured at 10 mm and the viscosity was measured (vertically) to intersect the alternatingly heated and unheated areas of the elastomer.
    Example 17­20
    PSA tapes were prepared using the same extruder screw construction, coating rolls, and die apparatus used in Example 1-4. The rubber used was an SMR CV60 natural rubber, the PSA formulation of Example 17x20 is as follows.
    ingredientParts by weight caoutchouc100 Piccolyte TM S-11550 Irganox TM 1010One
    The coating roll temperature was controlled at 30 ° C. and the tape formed had relatively low viscosity and high peeling anisotropy.
    The PSA tape of Example 17x20 was exposed to heat in a spatially varying pattern to selectively melt the crystallized body and relax the orientation of the elastomer. By changing the shape of the heating pattern, it was possible to change the loosening property of the tape. In order to perform the heating, the desired pattern was formed as described in Example 16 except that the patterns shown in Fig. 9-11 and Table 6 below were used. FIG. 9 shows a tape sample made of a mascot with alternating dark and transparent regions lined parallel to the machine direction of the tape, and FIG. 10 shows a mascot with alternating dark and transparent regions lined perpendicular to the machine direction of the tape. The tape sample produced is shown. 8 shows a control sample that corresponds to a relatively low viscosity tape sample without a pattern that is not selectively heated to change the unwinding properties.
    The tape was peeled off at a rate of 100 inches / minute (254 cm / min) to characterize the noise level of the tape during unwinding. The properties are shown in Table 6.
    Yes No.patternNoise characteristics 178Low peel adhesion, friction sound 189Smooth peeling, quiet 1910Sudden peeling, friction 2011Smooth peeling, quiet
    From these data, it is clear that the peeling properties and the annealing noise levels can be changed by spatially changing the viscosity of the adhesive.
    Example 21
    Anisotropic PSA tapes were prepared under the same conditions as in Example 10 except that PSA was coated on a 50 μm thick polyester film. The adhesiveness of the PSA tape measured by the PL3 method was found to be 0.15 N / cm when peeled off in the machine direction and 4.40 N / cm in the cross direction. A sheet of this tape was used as the application tape to transfer die cut letters from a silicone release liner similar to that shown in FIG. 4-7. Approximately 1.2 cm high characters were die cut from the vinyl graphic Controltac® film and the waste vinyl material was separated from the spaces between the characters. The tape was applied to the surface of the die crust on the release liner and rubbed. Thereafter, the coating tape was peeled off in the cross direction (high adhesion direction). The high adhesion exhibited in this direction by the application tape ensures that all letters are lifted off the release liner and held firmly to the application tape. Thereafter, the application tape and the die cutting characters attached to the tape were applied to the target substrate and rubbed. Thereafter, the coating tape was peeled off in the machine direction (low adhesion direction) and separated. Due to the low peeling force of the tape when peeled in this direction, it was assured that all the letters remained bound to the target substrate and the coating tape was easily separated.
    It will be apparent to those skilled in the art that various modifications and variations according to the present invention do not depart from the scope and spirit of the present invention.
    权利要求:
    Claims (15)
    [1" claim-type="Currently amended] A pressure sensitive adhesive article comprising a substrate and a pressure sensitive adhesive layer on the substrate,
    And the pressure sensitive adhesive comprises an partially oriented and partially crystallized elastomer.
    [2" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1, wherein the elastomer comprises natural rubber.
    [3" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1 wherein the elastomer comprises polyisobutylene.
    [4" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1, wherein the interposition is a release liner.
    [5" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1 wherein the adhesive layer has an anisotropic peel force.
    [6" claim-type="Currently amended] 2. The adhesive layer of claim 1 wherein the adhesive layer has low viscosity and low peeling strength, wherein the low viscosity and low peeling force results in higher viscosity and higher peeling off when the elastomer is heated above the melting point of the partially oriented and partially crystallized elastomer. Pressure-sensitive adhesive article, characterized in that the irreversible conversion to the force.
    [7" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1, wherein the pressure sensitive adhesive article is in the form of a tape, wherein the substrate is a backing and the pressure sensitive adhesive layer is coated on the backing.
    [8" claim-type="Currently amended] 8. The pressure sensitive adhesive article according to claim 7, wherein said backing is selected from the group consisting of polyethylene terephthalaart, polypropylene and paper.
    [9" claim-type="Currently amended] The pressure sensitive adhesive article of claim 1 wherein said pressure sensitive adhesive layer is attached to said substrate and said other surface.
    [10" claim-type="Currently amended] The pressure sensitive adhesive article according to claim 9, wherein the other surface is a film for graphic arts.
    [11" claim-type="Currently amended] The pressure sensitive adhesive article of claim 7 wherein the pressure sensitive adhesive layer has a high and low viscosity spatially varying region.
    [12" claim-type="Currently amended] A method for producing a pressure sensitive adhesive article according to claim 4,
    Preparing an elastomer that is a generally solid phase capable of stress strain induced crystallization, crushing the elastomer, optional mixing the crushed elastomer with a viscous inducing additive, heating the crushed elastomer, the crushed and Forming a heated elastomer to induce partial orientation, depositing the formed elastomer on a substrate, and inducing partial formation of crystallization at a temperature below the melting point of the partially oriented elastomer Cooling at a rate that maintains the partial orientation in the elastomer induced by the stress deformation of the step.
    [13" claim-type="Currently amended] 13. The method of claim 12, wherein the substrate is a backing and the forming step is performed by extruding and welding the elastomer onto the backing.
    [14" claim-type="Currently amended] In a method of joining one or more substrates or objects,
    Applying the pressure sensitive adhesive article of claim 1 to the surface of the substrate or object.
    [15" claim-type="Currently amended] A method of transferring one or more objects from one location to another, wherein
    Applying the pressure sensitive adhesive article according to claim 7 to the surface of the object, and transferring the resulting load-bearing article to another location.
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    同族专利:
    公开号 | 公开日
    BR9612027A|1999-06-29|
    JP2000502379A|2000-02-29|
    AU7611896A|1997-07-14|
    US5866249A|1999-02-02|
    EP0868494A1|1998-10-07|
    WO1997022675A1|1997-06-26|
    CA2238617A1|1997-06-26|
    US5858150A|1999-01-12|
    AU709567B2|1999-09-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1995-12-18|Priority to US08/574,246
    1995-12-18|Priority to US8/574246
    1996-11-08|Application filed by 스프레이그 로버트 월터, 미네소타 마이닝 앤드 매뉴팩춰링 캄파니
    1996-11-08|Priority to PCT/US1996/018090
    2000-11-06|Publication of KR20000064434A
    优先权:
    申请号 | 申请日 | 专利标题
    US08/574,246|US5866249A|1995-12-18|1995-12-18|Pressure-sensitive adhesive based on partially oriented and partially crystallized elastomer|
    US8/574246|1995-12-18|
    PCT/US1996/018090|WO1997022675A1|1995-12-18|1996-11-08|Pressure-sensitive adhesive article based on partially oriented and partially crystallized elastomer|
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