• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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    • 专利摘要:
    Procedure for the preparation of cellulose nanofibers. In the process, firstly, a cellulose nanofiber is obtained and characterized, based on an oxidation reaction of a solution of nabr and tempo, to whose dissolution a volume of naclo is added keeping the ph constant at 10, maintaining all the process the dissolution in constant agitation, all this in such a way that the cellulose fibers are added to a matrix of ethylvinylacetate in an autoclave under certain pressure and temperature, and thus obtain a compound based on cellulose nanofibers with ethylvinylacetate. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2600382A1
    申请号:ES201600570
    申请日:2016-07-11
    公开日:2017-02-08
    发明作者:Pere MUTJÉ PUJOL；Marc DELGADO AGUILAR；Joaquín Agustí TARRÉS FARRÉS
    申请人:Fibla Guardia Daniel；Jaume Caravaca Aitor；
    IPC主号:
    专利说明:

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    DESCRIPTION
    Preparation procedure of cellulose nanofibers.
    Object of the invention
    The present invention relates to a process for obtaining a material composed of cellulose nanofibers with ethyl vinyl acetate, and in which process the cellulose nanofibers are prepared first, in aqueous suspension and then mixed with an ethyl vinyl acetate acetate matrix under specific conditions, for achieve results of characterization of cellulose nanofibers and a characterization of the corresponding composite materials obtained.
    Background of the invention
    On the part of the inventor there is no known procedure that allows obtaining an alloy of cellulose nanofibers with ethyl vinyl acetate, under the conditions and steps described in the present application.
    Description of the invention
    The recommended procedure is based on initially preparing cellulose nanofibers at 15 mmoles of sodium hypochlorite per dry gram of fiber as oxidation grade, from a bleached chemical pulp of unrefined eucalyptus so that the oxidation reaction requires a solution of NaBr and TEMPO at constant concentrations of 01 g and 0.016 g respectively per gram of dry fiber to oxidize Once both reagents are perfectly dissolved in the suspension, the fibers to be oxidized should be added at the rate of 1 gr of fiber per 100 g total suspension.
    For the corresponding solution, a volume of NaCIO necessary for the desired oxidation level is added, keeping the pH constant at 10, all in such a way that a degree of oxidation of 15 mmol indicates that 15 mmol of NaCIO must be added per gram of dry fiber in such a way that once the entire volume of NaCIO has been added, the reaction is followed with 0.01 M NaOH to maintain the pH at 10 ending the reaction once the pH has stabilized at 10, so that throughout the entire process of Oxidation will keep the solution in constant agitation for a period of time between 2 and 5 hours.
    As for the oxidation reaction of the cellulose catalyzed by TEMPO, to say that the fiber is destructured by means of a high-performance homogenizer, the procedure consisting in the introduction of the suspension of chemically pretreated fibers washed with water, and the pass through the homogenizer according to the following sequence:
    Three passes to 300 bar three passes to 6 bar and 3 passes to 900 bar so that this gradual increase in the loan is made to avoid clogging of the equipment's cameras.
    Obtained cellulose nanofibers, were characterized according to the methodology described below:
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    I) Content in carboxy groups
    The content of carboxyl groups (-COOH) is determined by conductimetric evaluation resulting in mmols of COOH groups per gram of CNF The exchange of the proton of the carboxyl group for Na + is determined.
    II) Performance
    To calculate the performance of the process in CNF, a 0.2% suspension of CNF is centrifuged for 20 minutes at 4500 rpm, isolating the nanofiber fraction of the non-fibrillated or partially fibrillated fibers that will pass into the sediment. This residue is dried and the yield value is determined.
    III) Cationic demand
    The cationic demand is determined from the amount of cationic polymer necessary to neutralize the surface of the fibers. The reagent (cationic polymer) used is polydiallyldimethylammonium chloride (poly-DADMAC) and to carry out this test the Mutek PCD 04 apparatus is used to detect the particle charge.
    0.04 g of CNF (dry weight) are diluted and dispersed in 1 L of distilled water with mechanical stirring for 10 min at 3000 rpm and the addition of 10 ml of this 25 ml solution of poly-DADMAC chloride is added to 10 ml at known concentration. Proceed according to a normal determination.
    IV) Water retention value (WRV)
    The water retention value (WRV) indicates the amount of water chemically bound to the cellulose and allows to determine the ability of the fibers to absorb water and swell, the determination of the WRV is performed according to TAPPI UM 256.
    V) Transmittance
    Transmittance is determined by a UV-VisShimadzu spectrophotometer. The transmittance value is determined within the range of 400 to 800 nm wavelength of a 0.1% CNF suspension
    VI) Degree of polymerization
    The degree of polymerization corresponds to the value of monomer units that form a polymer chain. The determination of the degree of polymerization on cellulosic fibers is obtained from the intrinsic viscosity (q) of a suspension of fibers in ethylenediamine copper at 25 ° C prepared according to UNE 57-039-92 and determination by capillary viscosimeter.
    The entire preparation process of the CNF was quantified from the point of view of energy consumption using a Circutor CVM-C 10 network analyzer.
    CNF cellulose fibers are added to an EVA ethyl vinyl acetate matrix in an autoclave under pressure and temperature.
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    A 0.2wt% CNF dispersion in water was prepared by stirring in Ultraturrax, in order to ensure correct dispersion and individualization of the CNFs. Next, EVA was added to the aqueous suspension until an EVA / CNF ratio of 20/1 was achieved with the purpose of obtaining composite materials reinforced with 5wt% of CNF. The suspension, totally heterogeneous, was introduced into an autoclave and carried a temperature of 110 ° C to provide steam for the purpose of melting the EVA in the suspension.
    The result was not as expected, the dispersion of the EVA in the aqueous suspension being very limited and thus preventing the dispersion of the CNF in the matrix. However, it could be observed how the EVA reached its melting point and partially dispersed, being impossible Its total dispersion.
    To try to solve this problem, a working temperature was determined in a Brabender double spindle mixer, where readings of the resistance that opposes the material depending on the working temperature are given, being indicative of the temperature at which it is due Process the material.
    Addition of CNF in the EVA matrix and characterization of composite materials
    The CNFs were added in the EVA matrix in the double spindle mixer (with concentric rotation) Brabender. First, the equipment was preheated to the working temperature to subsequently incorporate the EVA matrix. When the equipment torque was constant, the cellulose nanofibers were added in aqueous suspension (1wt% concentration). This concentration made a prolonged mixing time imperative to evaporate all the water present in the CNF suspension. The result was not satisfactory due to two factors.
    • Presence of cavities with air and water in the resulting composite material.
    • Yellowing of the composite material as a result of the long exposure time of the CNFs in the Brabender.
    In order to counteract the effect of the cavities and the yellowish color, the research team decided to increase the concentration of the CNF suspension, thus reducing the amount of water per CNF mass unit. In this sense, prior to its incorporation into the EVA matrix , the CNF suspension was brought to 105 ° C in an oven until it reached a concentration of 5wt%, having reduced the mass of water considerably. The qualitatively resulting composite material had an appearance similar to that of the matrix. So that. The composite material was introduced into a plastics injector to obtain standard bone-shaped specimens (Type II). The resulting specimens were conditioned for 48 hours at a temperature between 22 and 24 ° C and 50% relative humidity to be characterized according to with ASTM D638.
    Likewise, with the resulting composite material, films of the same weight as the EVA film provided for the realization of the project were prepared. The films were obtained by hot pressing according to the following methodology described below:
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    First, a known amount of composite material was placed between two sheets of cellulose acetate and introduced into the hot plate press at 110 ° C without applying pressure to ensure that the EVA melts properly. Then, it is pressed using a force of 100 kN, being progressively increased up to 300kN for 20 minutes. The resulting films were characterized by traction following the same standard used to determine the tensile properties of paper (ISO 1924-2).
    With the purpose of improving the dispersion of the CNFs in the EVA matrix, the research team explored the option of incorporating alkyl cetene dimer (AKD) into the CNF suspension, partially hydrophobicizing the CNFs.
    In short, the results obtained will correspond to the characterization of the composite materials
    The characterization of the CNF obtained for the realization of the present invention is reflected in the following table:
    CNF
    NaCIO (mmol / g)
    Destructuring
    Carboxyl content (small-g / g)
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    Homogenization
    (3p300 / 3p600 / 3p900)
    1278
    Cationic demand (peq-g / g) 1850
    Fibrillation performance> 95
    (%)
    WRV (%) 10.8
    T ransmittance at 600nm 91.3
    Degree of polymerization 324
    Cellulose nanofibers at lower degrees of oxidation lead to similar nanofibrillation yields but with lower transmittances and specific surfaces, which limits their use for the final application that is intended to be achieved. However, paradoxically, lower degrees of oxidation lead to lower water retention capacity, which makes it easier to use at high temperatures to be incorporated into the EVA matrix.
    Regarding the characterization of composite materials. The results of the tensile test corresponding to the specimens obtained by injection are shown in the following table:
     % CNF  otc (MPa) Etc (mm) EtC (%)
     0  3.17 88 47 80.4
     one  3.21 73.18 66.5
     2  4.13 66 12 60.1
     3  4.27 61.03 55.5
     5  4.22 59.02 53.7 _________I
    As noted in the previous table, the effect of AKD is positive in terms of increased physical-mechanical properties. This is due to the greater ease of dispersion of the CNF when the surface hydroxyl groups are partially blocked, since the curing process of the AKD was not carried out until after they had been dispersed in the EVA matrix.
    With regard to transmittances, in all cases 90% was exceeded 700nm, 10 giving rise to seemingly transparent films obtaining lower values in those films reinforced with CNF.
    权利要求:
    Claims (2)
    [1]
    1. Procedure for the preparation of cellulose nanofibers, the process being carried out at 15 mmol of sodium hypochlorite as a degree of oxidation from a chemical paste
    5 bleached unrefined eucalyptus characterized in that for each gram of dry fiber to be oxidized a solution of NaBr and TEMPO is used at constant concentrations of 0.1 g to 0.016 g respectively, maintaining the consistencies at 1%, adding to the solution a volume of NaCIO, maintaining the constant pH at 10 with the particularity that the oxidation reaction is continued with the addition of 0.01 M 10 NaOH to maintain the pH at 10, with a constant stirring of the oxidation process throughout the oxidation process. solution for a period of time between 2 and 5 hours, to achieve cellulose nanofibers in aqueous suspension.
    [2]
    2. Process for preparing cellulose nanofibers according to revindication 1a, 15 characterized in that in the oxidation reaction of cellulose catalyzed by TEMPO
    a fiber de-structuring is established by means of a homogenizer, with an introduction of the fibers in prior suspension, treated chemical and washed in water, with three passes through the homogenizer at 300 bar; three passes to 600 bar and three passes to 900 bar.
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    同族专利:
    公开号 | 公开日
    ES2600382B1|2017-11-15|
    引用文献:
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    法律状态:
    2017-11-15| FG2A| Definitive protection|Ref document number: 2600382 Country of ref document: ES Kind code of ref document: B1 Effective date: 20171115 |
    2018-06-12| FA2A| Application withdrawn|Effective date: 20180606 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES201600570A|ES2600382B1|2016-07-11|2016-07-11|Preparation procedure of cellulose nanofibers|ES201600570A| ES2600382B1|2016-07-11|2016-07-11|Preparation procedure of cellulose nanofibers|
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