JP2010242063A - Cellulose nanofiber compound polyvinyl alcohol-based polymer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a PVA composition, film and fiber having excellent heat resistance or hot water resistance without damaging transparency. <P>SOLUTION: A cellulose nanofiber compound polyvinyl alcohol-based polymer composition is a composite material of a polyvinyl alcohol-based polymer and a cellulose nanofiber having an average fiber diameter of 2-150 nm, and a part of a hydroxy group of the cellulose is oxidized to at least one functional group selected from a group consisting of a carboxyl group and an aldehyde group, and also the content of the cellulose nanofiber having a total amount of the carboxyl group and the aldehyde group of 0.1-2.2 mmol/g to a mass of the cellulose nanofiber is 0.1-10 pts.mass to 100 pts.mass polyvinyl alcohol-based polymer. A film and a fiber using the composition are provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cellulose nanofiber composite polyvinyl alcohol (hereinafter abbreviated as PVA) polymer composition having excellent heat resistance and hot water resistance, a film and a fiber using the same, and industrial materials. It can be used extremely effectively in many applications including applications, electrical and electronic materials, agricultural materials, and optical materials.

  Conventionally, PVA polymers are widely used as film materials and fiber materials as well as pastes and coating agents because they are excellent in adhesion to inorganic materials and mechanical properties. However, since the PVA polymer has a hydroxyl group in the molecular skeleton, it cannot be said to have sufficient hot water resistance. For example, in the case of a fiber made of a PVA polymer, if it is exposed to a wet state for a long time, it will swell. As a result, the mechanical properties are deteriorated and dimensional changes are caused, so that the use is limited even if it is used as a general industrial material. In addition, it is known that the hydrogen bonding ability in the molecular skeleton is weakened at 100 ° C. or higher. Therefore, even in an absolutely dry state, the molecular motion becomes active at the temperature or higher. The mechanical properties, dimensional changes, and the like were reduced, and the usage was limited. As a heat resistant water-resistant technology for PVA polymers, a technology for hydrophobizing or cross-linking PVA polymers using acetalization reaction between an aldehyde compound and a hydroxyl group of PVA polymer has been widely proposed (for example, patents). References 1 to 4). However, in these formulations, a part of the amorphous part region of the PVA polymer is hydrophobized, so that the hot water resistance is improved, but it is not intended to improve the decrease in mechanical properties when exposed to high temperatures. There wasn't. In order to increase the degree of acetalization, it is necessary to set the treatment time longer and separate steps such as an acid treatment bath for heat-resistant water formation by acetalization. Thus, further improvements have been desired in terms of process passability.

  In addition, a film made of a PVA-based polymer forms a polyiodine complex in its molecule and expresses excellent dichroism, so that it is subjected to uniaxial stretching, dyeing with iodine, and treatment with a boron compound. Widely used in polarizing film applications that are members of liquid crystal displays. In the process of manufacturing a polarizing film, high water swellability is required for the purpose of incorporating iodine into the film, while hot water resistance is high for the purpose of increasing the yield in the process. Conflicting performance is required. Conventionally, it is widely known that heat treatment can be carried out by heat treatment, but this method increases the crystallinity of the PVA polymer and is effective in improving hot water resistance, but has water swellability. It had the problem that it will fall remarkably.

  On the other hand, an attempt to improve the hot water resistance and heat resistance of a PVA polymer by combining a PVA polymer and a filler has been reported. The average fiber diameter is 2 to 150 nm, and one of the hydroxyl groups of cellulose. It has been proposed that a cellulose nanofiber oxidized to at least one functional group selected from the group consisting of a carboxyl group and an aldehyde group is combined with a PVA polymer (for example, see Patent Document 5). Cellulose has a hydroxyl group, a carboxyl group, and an aldehyde group in its molecular skeleton, so that it interacts strongly with the PVA polymer and can be expected to have improved hot water resistance and heat resistance. , 10-80% by weight of a binder such as PVA polymer is used for cellulose nanofibers, in other words, 12.5-1000% by weight of cellulose nanofibers is used for binder such as PVA polymer. In the case of blending such a large amount of cellulose nanofibers, it is not only difficult to mold as is apparent from the comparative examples described later, but the dispersibility of the cellulose nanofibers is not good, The mechanical properties are deteriorated, and furthermore, it is impossible to obtain a composition excellent in both hot water resistance and heat resistance.In addition, transparency when formed into a film is lost.

JP 30-7360 PR JP-A-36-24565 Japanese Patent Publication No.29-6145 Public information of Shoko 32-5819 Japanese Laid-Open Patent Publication No. 2008-1728

  The present invention eliminates the disadvantages of the prior art as described above, and without impairing the excellent mechanical performance of the PVA polymer or the transparency when formed into a film, An object of the present invention is to provide a PVA polymer composition, a film and a fiber excellent in properties.

  As a result of intensive studies in order to obtain the above-described PVA polymer, the inventors of the present invention do not require any special process for the PVA polymer, and have a specific average fiber diameter and modified cellulose. It has been found that this can be achieved by combining the nanofiber and the PVA polymer.

  That is, the present invention is a composite of a PVA polymer and a cellulose nanofiber having an average fiber diameter of 2 to 150 nm, and at least one selected from the group consisting of a carboxyl group and an aldehyde group. The content of cellulose nanofibers that are oxidized to two functional groups and the total amount of carboxyl groups and aldehyde groups is 0.1 to 2.2 mmol / g with respect to the mass of the cellulose fibers is 100 masses of PVA polymer. This is achieved by providing a cellulose nanofiber composite PVA polymer composition that is 0.1 to 10 parts by mass relative to parts.

  Further, the above object is more preferable because the cellulose nanofiber is a cellulose fiber which is oxidized by using natural cellulose as a raw material, using an N-oxyl compound as an oxidation catalyst in water, and acting on a cooxidant. To be achieved.

  According to the present invention, a composition excellent in hot water resistance or heat resistance can be obtained without losing the conventional properties of the PVA polymer. For example, by using the composition of the present invention, a transparent A film excellent in hot water resistance can be obtained without impairing the properties and water swellability. Furthermore, by using the composition of the present invention, it is possible to obtain a fiber having high strength and high elastic modulus and excellent heat resistance with little deterioration in physical properties at high temperatures.

  The present invention will be specifically described below. In the present invention, blending a specific amount of the above-mentioned specific cellulose nanofibre into the PVA polymer is extremely important for achieving the object of the present invention. Here, the specific cellulose nanofiber has a number average fiber diameter of 2 to 150 nm, and a part of the hydroxyl group of cellulose is oxidized to at least one functional group selected from the group consisting of a carboxyl group and an aldehyde group. Cellulose nanofiber. When the number average fiber diameter satisfies 2 to 150 nm, excellent transparency, hot water resistance and heat resistance can be imparted.

  Cellulose nanofibers have a number average fiber diameter of 2 to 150 nm, preferably 2 to 100 nm, and more preferably 2 to 10 nm.

  Here, the number average fiber diameter is measured as follows. An aqueous dispersion of fine cellulose having a solid content of 0.05 to 0.1 parts by mass is prepared, and the dispersion is cast on a carbon film-coated grid that has been subjected to a hydrophilic treatment to obtain a sample for TEM observation. Moreover, when the fiber of a big fiber diameter is included, you may observe the SEM image of the surface cast on glass. Observation with an electron microscope image is performed at a magnification of 5000 times, 10000 times, or 50000 times depending on the size of the constituent fibers. At this time, when an axis having an arbitrary vertical and horizontal image width is assumed in the obtained image, a sample and observation conditions (magnification, etc.) are set so that at least 20 fibers intersect the axis at least with respect to the axis. With respect to an observation image satisfying this condition, two random axes are drawn vertically and horizontally per image, and the fiber diameter of the fiber intersecting with the axis is visually read. Thus, images of at least three non-overlapping surface portions are taken with an electron microscope, and the value of the fiber diameter of the fibers intersecting with each of the two axes is read (thus, at least 20 × 2 × 3 = 120 fiber diameters). Information). The number average fiber diameter is calculated from the fiber diameter data thus obtained.

  Furthermore, the cellulose nanofiber has a cellulose I-type crystal structure in which a part of the hydroxyl group of cellulose is oxidized to a carboxyl group or an aldehyde group. This means that the cellulose nanofiber is a fiber obtained by subjecting a naturally-derived cellulose solid raw material having an I-type crystal structure to surface oxidation and refinement. That is, in the process of biosynthesis of natural cellulose, nanofibers called microfibrils are first formed almost without exception, and it is used in principle to build a higher-order solid structure by bunching them. In order to weaken the hydrogen bond between the surfaces, which is the driving force of strong cohesive force between microfibrils, a part thereof is oxidized and converted into an aldehyde group or a carboxyl group.

Here, the cellulose nanofibers have an I-type crystal structure in the diffraction profile obtained by the wide-angle X-ray diffraction image measurement in two theta = 14-17 ° vicinity and 2 theta = 22-23 ° vicinity. It can be identified from having a typical peak at one position. Furthermore, the introduction of an aldehyde group or a carboxyl group into the cellulose of the cellulose nanofibers indicates that the absorption due to the carbonyl group in the total reflection infrared spectroscopic spectrum (ATR) (1608 cm ⁻¹ ) in the sample from which moisture has been completely removed. This can be confirmed by the presence of the vicinity. In particular, in the case of an acid-type carboxyl group (COOH), absorption exists at 1730 cm ⁻¹ in the above measurement.

  Cellulose nanofibers are more stable as finer fiber diameters when the total amount of carboxyl groups and aldehyde groups present in cellulose is larger, and are not only uniformly dispersed in PVA polymers, but also PVA heavy weights. Since the hydrogen bonding ability with the coalescence increases, the combined effect increases. For example, in the case of wood pulp or cotton pulp, the total amount of carboxyl groups and aldehyde groups present in cellulose nanofibers is 0.1 to 2.2 mmol / g, preferably 0.5 to 2 with respect to the mass of cellulose nanofibers. .2 mmol / g, more preferably 0.8 to 2.2 mmol / g, because it is excellent in stability as a nanofiber and has high hydrogen bonding ability with a PVA polymer, which is preferable. In the case of cellulose having a relatively large fiber diameter of microfibrils such as bacterial cellulose and cellulose extracted from sea squirt (average diameter is on the order of several tens of nm), the total amount is 0.1 to 0.8 mmol / g. Preferably, the amount is 0.2 to 0.8 mmol / g because the hydrogen bonding ability with the PVA polymer is increased. Thus, when the total amount satisfies 0.1 to 2.2 mmol / g, the hydrogen bonding ability between the cellulose nanofiber and the PVA polymer is increased, and the affinity between the two is also increased. Hot water resistance and heat resistance are imparted.

  Furthermore, the introduction of a carboxyl group with respect to an aldehyde group, which is a nonionic substituent, creates an electric repulsive force and increases the tendency of microfibrils to break apart without maintaining aggregation. The stability as a nanofiber is increased, and not only is it uniformly dispersed in the PVA polymer, but also the composite effect is enhanced because the hydrogen bonding ability with the PVA polymer is increased. For example, in the case of wood pulp or cotton pulp, the amount of carboxyl groups present in cellulose nanofibers is 0.2 to 2.2 mmol / g, preferably 0.4 to 2.2 mmol / g, based on the mass of cellulose fibers. The bond with the PVA polymer becomes stronger when the amount is preferably 0.6 to 2.2 mmol / g. In the case of cellulose having a relatively large fiber diameter such as bacterial cellulose or cellulose extracted from sea squirt, the amount of carboxyl groups is 0.1 to 0.8 mmol / g, preferably 0.2 to 0. When it is .8 mmol / g, the bond with the PVA polymer is further strengthened.

Here, the amount (mmol / g) of aldehyde groups and carboxyl groups of cellulose relative to the mass of cellulose nanofibers is evaluated by the following method.
60 ml of 0.5-1 part by mass slurry was prepared from a cellulose sample precisely weighed in dry mass, and the pH was adjusted to about 2.5 with 0.1 M hydrochloric acid aqueous solution, and then 0.05 M sodium hydroxide aqueous solution was added dropwise. To measure the electrical conductivity. The measurement is continued until the pH is about 11. The amount of functional group 1 is determined from the amount (V) of sodium hydroxide consumed in the neutralization step of the weak acid whose electrical conductivity changes slowly. The functional group amount 1 indicates the amount of carboxyl groups.
Functional group amount (mmol / g) = V (ml) × 0.05 / mass of cellulose (g)
Next, the cellulose sample is further oxidized at room temperature for 48 hours in a 2% aqueous sodium chlorite solution adjusted to pH 4 to 5 with acetic acid, and the functional group amount 2 is measured again by the above method. The amount of functional groups added by this oxidation (= functional group amount 2 -functional group amount 1) is calculated and used as the aldehyde group amount.

Next, a method for preparing cellulose nanofibers and a dispersion in which cellulose nanofibers are dispersed in a medium according to the present invention will be described.
The dispersion of cellulose nanofiber refers to a dispersion of the above-described cellulose nanofiber in a solvent described later. The dispersion includes, for example, an oxidation reaction step in which natural cellulose is used as a raw material, an N-oxyl compound is used as an oxidation catalyst in water, and the natural cellulose is oxidized by acting a co-oxidant to obtain reactant nanofibers. Can be obtained by three steps: a purification step of obtaining reactant nanofibers impregnated with water and a dispersion step of dispersing the reactant fibers impregnated with water in a solvent. Each step will be described in detail below.

First, in the oxidation reaction step, a dispersion in which natural cellulose is dispersed in water is prepared. Here, natural cellulose means purified cellulose isolated from cellulose biosynthetic systems such as plants, animals, and bacteria-producing gels. More specifically, softwood pulp, hardwood pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as straw pulp and bagasse pulp, bacterial cellulose, cellulose isolated from sea squirts, and seaweed. Examples include cellulose to be released, but are not limited thereto. Natural cellulose is preferably subjected to a treatment for increasing the surface area such as beating, whereby the reaction efficiency can be increased and the productivity can be increased. Furthermore, when natural cellulose is used that has been isolated and purified, and stored in a dry dry state, the microfibril bundles are likely to swell with water. The number average fiber diameter can be reduced, which is preferable.
The dispersion medium of natural cellulose in the reaction is water, and the concentration of natural cellulose in the reaction aqueous solution is arbitrary as long as the reagent can sufficiently diffuse, but usually about 5% with respect to the weight of the reaction aqueous solution. It is as follows.

  Many N-oxyl compounds that can be used as an oxidation catalyst for cellulose have been reported ("Cellulose" Vol. 10, 2003, pages 335 to 341, using "TEMPO derivatives by I. Shibata and A. Isogai"). The article entitled “Catalyzed Oxidation of Cellulose: HPSEC and NMR Analysis of Oxidation Products”), in particular, TEMPO (2,6,6, -tetramethylpiperidine 1-oxyl), 4-acetamido-TEMPO, 4-carboxy-TEMPO. , And 4-phosphonooxy-TEMPO are preferable in the reaction rate at room temperature in water. A catalytic amount is sufficient for the addition of these N-oxyl compounds, preferably 0.1 to 4 mmol / l, more preferably 0.2 to 2 mmol / l.

As the co-oxidant, hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogen acid or a salt thereof, hydrogen peroxide, a perorganic acid, and the like can be used in the present invention. Hypohalites such as sodium hypochlorite and sodium hypobromite. When sodium hypochlorite is used, it is preferable in terms of the reaction rate to advance the reaction in the presence of an alkali metal bromide such as sodium bromide. The addition amount of the alkali metal bromide is about 1 to 40 times mol, preferably about 10 to 20 times mol for the N-oxyl compound.
The pH of the aqueous reaction solution is preferably maintained in the range of about 8-11. The temperature of the aqueous solution is arbitrary at about 4 to 40 ° C., but the reaction can be performed at room temperature, and the temperature is not particularly required to be controlled.

  The amount of carboxyl groups required to obtain cellulose nanofibers varies depending on the natural cellulose species, and the greater the amount of carboxyl groups, the smaller the number average fiber diameter. For example, in the case of wood-based pulp and cotton-based pulp, carboxyl groups are introduced in the range of 0.2 to 2.2 mmol / g, and in cellulose extracted from bacterial cellulose and squirts, 0.1 to 0.8 mmol / g. move on. Therefore, it is preferable to obtain the target amount of carboxyl groups by controlling the degree of oxidation by the addition amount of the co-oxidant and the reaction time and optimizing the oxidation conditions according to the natural cellulose species. In general, the amount of co-oxidant added is preferably in the range of about 0.5 to 8 mmol with respect to 1 g of natural cellulose, and the reaction is completed within about 5 to 120 minutes and at most 240 minutes.

  In the purification process, the reactant nanofibers and compounds other than water contained in the reaction slurry such as unreacted hypochlorous acid and various by-products are removed from the system. Since the nanofibers are not dispersed evenly at the stage, a normal purification method, that is, washing with water and filtration is repeated to obtain a high-purity (99 parts by mass or more) reactant nanofiber and water dispersion. . As the purification method in the purification step, any apparatus can be used as long as it can achieve the above-described object, such as a method using centrifugal dehydration (for example, a continuous decanter). The aqueous dispersion of reactant nanofibers thus obtained is in the range of approximately 10 to 50 parts by mass as the solid content (cellulose) concentration in the squeezed state. In consideration of the dispersion in the nanofiber in the subsequent step, if the solid content concentration is higher than 50 parts by mass, extremely high energy is required for dispersion, which is not preferable.

Furthermore, it can provide as a dispersion | distribution of a cellulose nanofiber by disperse | distributing the reaction material nanofiber (water dispersion) impregnated with the water obtained by the refinement | purification process mentioned above in a solvent, and performing a dispersion process.
Here, the solvent as the dispersion medium is usually preferably water, but in addition to water, alcohols that are soluble in water depending on the purpose (methanol, ethanol, isopropanol, isobutanol, sec-butanol, tert-butanol, methyl) Cellosolve, ethyl cellosolve, ethylene glycol, glycerin, etc.), ethers (ethylene glycol dimethyl ether, 1,4-dioxane, tetrahydrofuran, etc.), ketones (acetone, methyl ethyl ketone), N, N-dimethylformamide, N, N-dimethylacetamide Dimethyl sulfoxide or the like may be used. Moreover, these mixtures can also be used conveniently. Furthermore, when diluting and dispersing the dispersion of the above-mentioned reactant nanofibers with a solvent, the dispersion is gradually added by adding a solvent gradually. May be able to gain a body. Due to operational problems, the dispersion conditions may be selected so that the state after the dispersion step is a viscous dispersion or gel.

Next, various devices can be used as the disperser used in the dispersion step. For example, although depending on the progress of the reaction in the nanofiber (reaction amount to aldehyde group or carboxyl group), the screw mixer, paddle mixer, disperser can be used under suitable conditions. A dispersion of cellulose nanofibers can be sufficiently obtained by a general-purpose disperser as an industrial production machine such as a mold mixer or a turbine mixer.
However, more powerful and defeating devices such as homomixers, high pressure homogenizers, ultra high pressure homogenizers, ultrasonic dispersion processing, beaters, disc refiners, conical refiners, double disc refiners, and grinders under high speed rotation By using, more efficient and advanced downsizing becomes possible. Furthermore, by using these devices, even when the amount of aldehyde group or carboxyl group is relatively small (for example, 0.1 to 0.5 mmol / g as the total amount of aldehyde group or carboxyl group to cellulose). A highly refined dispersion of cellulose nanofibers can be provided.

  In this manner, cellulose nanofibers can be produced by drying a dispersion in which cellulose nanofibers are dispersed in a medium.

  By blending the cellulose nanofibers or cellulose nanofiber dispersion in a specific amount with respect to the PVA polymer in a pure amount, that is, 0.1 to 10 parts by mass of cellulose nanofibers with respect to 100 parts by mass of the PVA polymer. Thus, a composition excellent in transparency, hot water resistance and heat resistance can be obtained. The more preferable amount of cellulose nanofiber is 0.5 parts by mass or more, optimally 1 part by mass or more, and the upper limit is preferably 8 parts by mass or less, and optimally 6 parts by mass or less. .

The PVA polymer used in the present invention is not particularly limited, but PVA having a saponification degree of 70 to 100 mol%, preferably 80 to 99.8 mol%, a polymerization degree of 500 to 8000, preferably 1000 to 4000. System polymers are preferably used. Here, the degree of saponification of the PVA polymer indicates the proportion of units that are actually saponified to vinyl alcohol units among units that can be converted to vinyl alcohol units by saponification, and is measured according to the JIS K6726 test method. Is done. The degree of polymerization (Po) is a value measured according to the JIS K6726 test method, and the intrinsic viscosity [η] (unit) measured in water at 30 ° C. after re-saponifying and purifying the PVA polymer. : Deciliter / g) by the following formula.
Po = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  The PVA polymer can be produced by polymerizing a vinyl ester monomer and saponifying the resulting vinyl ester polymer. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Of these, vinyl acetate is preferred.

  When the vinyl ester monomer is polymerized, other copolymerizable monomers can be copolymerized within a range that does not impair the effects of the invention, if necessary. Examples of the monomer copolymerizable with the vinyl ester monomer include olefins having 2 to 30 carbon atoms such as ethylene, propylene, 1-butene and isobutene; acrylic acid and salts thereof; methyl acrylate and acrylic acid. Acrylics such as ethyl, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc. Acid esters; methacrylic acid and salts thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methacrylic acid 2-ethylhexyl, dodecyl methacrylate Methacrylic acid esters such as octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropyldimethylamine and salts thereof, N-methylolacrylamide and derivatives thereof, etc. Acrylamide derivatives; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropyldimethylamine and salts thereof, N-methylolmethacrylamide and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl Vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl Vinyl ethers such as ether, dodecyl vinyl ether and stearyl vinyl ether; Nitriles such as acrylonitrile and methacrylonitrile; Halogenated vinyls such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; Allyl such as allyl acetate and allyl chloride Compound; Maleic acid and its salt or ester thereof; Itaconic acid and its salt or ester thereof; Vinylsilyl compound such as vinyltrimethoxysilane; Isopropenyl acetate; Dihydroxybutene derivative; Vinylethyl carbonate; 3,4-diacetoxy-1-butene 3,4-diethoxy-1-butene and the like. The copolymerization ratio of these copolymerizable monomers is preferably 15 mol% or less, and more preferably 10 mol% or less. About a lower limit, it is 0.01 mol% or more suitably, and is 0.05 mol% or more more suitably.

  In the composition of the present invention, various additives such as a plasticizer, a surfactant, and a crosslinking agent can be blended according to the purpose and application. Here, the plasticizer is preferably a polyhydric alcohol, and examples thereof include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like. A seed or a mixture of two or more can be used. Among these, ethylene glycol, glycerin and diglycerin are preferable. The content of the plasticizer is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass with respect to the PVA polymer.

  Examples of the surfactant include an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. Examples of the anionic surfactant include carboxylic acid types such as potassium laurate; sulfate ester types such as octyl sulfate; sulfonic acid types such as dodecylbenzenesulfonate and sodium alkylbenzenesulfonate; polyoxyethylene lauryl ether phosphate mono Ethanolamine salt, octyl phosphate potassium salt, lauryl phosphate potassium salt, stearyl phosphate potassium salt, octyl ether phosphate potassium salt, dodecyl phosphate sodium salt, tetradecyl phosphate sodium salt, dioctyl phosphate Ester sodium salt, Trioctyl phosphate sodium salt, Polyoxyethylene aryl phenyl ether phosphate potassium salt, Polyoxyethylene aryl ester Alkenyl ether phosphate amine salts, and the like. Examples of nonionic surfactants include alkyl ether types such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate. An alkylamine type such as polyoxyethylene lauryl amino ether; an alkylamide type such as polyoxyethylene lauric acid amide; a polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; an alkanolamide type such as oleic acid diethanolamide; Examples include allyl phenyl ether type such as oxyalkylene allyl phenyl ether. Examples of the cationic surfactant include amines such as laurylamine hydrochloride; quaternary ammonium salts such as lauryltrimethylammonium chloride; and pyridium salts such as laurylbiridinium chloride. Furthermore, examples of the amphoteric surfactant include N-alkyl-N, N-dimethylammonium betaine. Surfactant can be used 1 type or in combination of 2 or more types. 0.01-7 mass parts is preferable with respect to PVA, and, as for content of surfactant, 0.02-5 mass parts is more preferable.

  The crosslinking agent is not particularly limited as long as it causes a crosslinking reaction with the PVA polymer. For example, boric acid, calcium borate, cobalt borate, zinc borate, aluminum potassium borate, ammonium borate, boric acid. Cadmium, Potassium borate, Copper borate, Lead borate, Nickel borate, Barium borate, Bismuth borate, Magnesium borate, Manganese borate, Lithium borate, Borax, Carnite, Inyoite, Colite Boron compounds such as stone and zyberite; tripotassium citrate and the like. Among these, boron compounds are preferable, and boric acid and borax are more preferable. The content of the crosslinking agent is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to the PVA polymer.

Since the composition of the present invention is particularly useful as a film material and a fiber material, this point will be described in more detail below.
Films include packaging film, optical polarizing film, retardation film, agricultural material film (for vegetable warming, growth, etc.), water-soluble film (water transfer film, agricultural chemical, detergent packaging film, etc. ), An oxygen barrier film, and among these, it is particularly useful as an optical polarizing film.
Although the thickness of a film changes with purposes and uses, it is 5 to 1000 μm, preferably 10 to 800 μm, and more preferably 10 to 500 μm.

  For the film, using a solution containing the composition, a casting film forming method, a solution coating method, a wet film forming method (a method of discharging into a poor solvent), a gel film forming method (a PVA polymer aqueous solution is once cooled) After gelation, the solvent is extracted and removed), a combination thereof, a melt extrusion film forming method in which a composition containing a plasticizer is melted, and the like. Among these, a film obtained by a casting film forming method, a solution coating method, and a melt extrusion film forming method is preferable.

  The film thus obtained can be uniaxially or biaxially stretched before and after the drying step, if necessary. As extending | stretching conditions, the temperature of 20-120 degreeC and the draw ratio of 1.05-5 times are preferable, and 1.1-3 times are more preferable. Furthermore, if necessary, the residual stress can be reduced by heat fixing the film after stretching.

  It is preferable that the moisture content of a film layer is 1-10 mass%, and 1-8 mass% is more preferable.

  The film thus obtained has a light transmittance of 70% or more, preferably 80% or more, and more preferably 90% or more, which impairs the excellent transparency of the conventional PVA film. In addition, as is clear from examples described later, the water swellability is not lowered, although the softening point in hot water is increased and the hot water resistance is improved.

  Next, the fiber referred to in the present invention will be described. Examples of the fibers include PVA fibers using the composition of the present invention, acetalized PVA fibers (such as formalized PVA fibers and butyral PVA fibers). The fineness of the fiber obtained by this invention is not specifically limited, For example, the fiber of the fineness of 0.1-10000 dtex, Preferably 1-1000 dtex can be used widely. What is necessary is just to adjust the fineness of a fiber suitably with a nozzle diameter or a draw ratio.

  Next, the manufacturing method of the PVA type fiber of this invention is demonstrated. In the present invention, by producing a fiber by a method described later using a spinning stock solution in which a PVA polymer and cellulose nanofiber are dissolved in water or an organic solvent, the cellulose nanofiber is dispersed inside the fiber, A fiber excellent in high temperature physical properties can be produced efficiently and inexpensively. Examples of the solvent constituting the spinning dope include polar solvents such as water, dimethyl sulfoxide (hereinafter abbreviated as DMSO), dimethylacetamide, dimethylformamide, N-methylpyrrolidone, polyhydric alcohols such as glycerin and ethylene glycol, and the like. And a mixture of swellable metal salts such as rhodan salts, lithium chloride, calcium chloride, zinc chloride and the like, or a mixture of these solvents, or a mixture of these solvents and water. Among these, water and DMSO are particularly preferable. Most suitable in terms of process passability such as cost and recoverability.

  The polymer concentration in the spinning dope varies depending on the composition, degree of polymerization, and solvent, but is preferably in the range of 8 to 60 parts by mass. The liquid temperature at the time of discharging the spinning dope is preferably in a range in which the spinning dope is not decomposed or colored, and specifically 50 to 200 ° C. is preferable. In addition, as long as the effect of the present invention is not impaired, the spinning dope includes a flame retardant, an antioxidant, an antifreezing agent, a pH adjusting agent, in addition to the PVA polymer and cellulose nanofiber, depending on the purpose. Additives such as a hiding agent, a coloring agent, an oil agent, and a special functional agent may be included. Furthermore, these may be used alone or in combination of two or more.

  Such spinning raw solution may be discharged from a nozzle to perform wet spinning, dry wet spinning, or dry spinning, and may be discharged into a solidified liquid or a gas having a solidifying ability for a PVA polymer. Wet spinning is a method in which a spinning stock solution is discharged directly from a spinning nozzle into a solidification bath, and dry and wet spinning is a method in which a spinning stock solution is temporarily placed in air or inert gas at an arbitrary distance from the spinning nozzle. It is a method of discharging and then introducing into the solidification bath. Dry spinning is a method of discharging a spinning solution into air or an inert gas.

  In the present invention, the solidification bath used in wet spinning or dry wet spinning differs depending on whether the stock solution is an organic solvent or water. In the case of a stock solution using an organic solvent, it is preferably a mixed solution composed of a solidification bath solvent and a stock solution solvent from the viewpoint of fiber strength and the like obtained, and the solidification solvent is not particularly limited, but for example, methanol, ethanol, An organic solvent having a solidifying ability for PVA polymers such as alcohols such as propanol and butanol, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used. Among these, a combination of methanol and DMSO is preferable in terms of low corrosivity and solvent recovery. On the other hand, when the spinning dope is an aqueous solution, an aqueous solution of inorganic salts or caustic soda having a solidifying ability with respect to a PVA polymer such as mirabilite, ammonium sulfate and sodium carbonate can be used as the solidifying solvent constituting the solidifying bath. Further, an aqueous solution to which boric acid or the like is added together with the PVA polymer can be gel-spun in an alkaline solidification bath.

  Next, in order to extract and remove the solvent of the spinning dope from the solidified yarn, it is passed through an extraction bath. It is preferable for improving the mechanical properties. In that case, the wet draw ratio is preferably 2 to 10 times in terms of processability and productivity. As the extraction solvent, a solidified solvent alone or a mixed solution of a stock solvent and a solidified solvent can be used.

  After wet stretching, the film is dried, and in some cases, dry heat stretching and heat treatment are performed. The stretching conditions for this are generally 100 ° C or higher, preferably 150 ° C to 260 ° C, and the total stretching ratio is 3 times or more, preferably 5 to 25 times. Is preferred because it increases the crystallinity and orientation of the fiber and remarkably improves the mechanical properties of the fiber. When the temperature is less than 100 ° C., whitening of the fiber occurs, resulting in a decrease in mechanical properties. On the other hand, if the temperature exceeds 260 ° C., partial melting of the fiber occurs, and in this case, mechanical properties are deteriorated, which is not preferable. The stretch ratio here is the product of the above-described wet stretching in the solidification bath before drying and the stretch ratio after drying. For example, when the wet stretching is 3 times and the subsequent dry heat stretching is 2 times, the total stretching ratio is 6 times.

  The PVA fiber of the present invention can be subjected to acetalization treatment or other crosslinking treatment generally performed for PVA fibers for the purpose of improving hot water resistance, depending on the application or purpose. That is, the fiber can be hydrophobized by treating the PVA fiber in an aqueous solution containing a crosslinking agent such as formaldehyde that reacts with the hydroxyl group of the PVA polymer and blocking the hydroxyl group.

  The fiber made of the PVA polymer composition of the present invention is characterized by excellent elasticity retention at high temperatures. Specifically, the PVA fiber of the present invention has an elastic modulus retention at 100 ° C. with respect to room temperature of 30% or more, preferably 35% or more, and more preferably 40% or more. . When the elastic modulus retention rate is less than 30%, it is not preferable because it is not different from existing PVA fibers and uses are restricted.

  The fibers of the present invention exhibit excellent heat resistance in all fiber forms such as staple fibers, shortcut fibers, filament yarns, spun yarns, strings, ropes, fabrics and the like. Can be used. The cross-sectional shape of the fiber at that time is also not particularly limited, and may be circular, hollow, or an atypical cross section such as a star shape. Especially, since the PVA fiber according to the present invention is excellent in heat resistance and flexibility, it can be advantageously used as a heat resistant fabric. For example, the PVA fiber according to the present invention is 50% by mass or more, preferably By using a fabric containing 80% by mass or more, particularly 90% by mass or more, a PVA fiber product exhibiting high heat resistance can be obtained. At this time, although there is no limitation in particular as a fiber which can be used together, PVA type fiber which does not contain a cellulose nanofiber, polyester type fiber, polyamide type fiber, a cellulose type fiber, etc. can be mentioned.

  The fibers of the present invention are excellent in heat resistance such as elastic modulus retention at high temperatures in addition to mechanical properties and flexibility, and therefore are made into filaments, spun yarns, and further fabrics such as paper, nonwoven fabric, woven fabric, and knitted fabric. It can be suitably used for various applications such as industrial materials, clothing, and medical use. For example, it can be widely used for various filters, heat insulating materials, highly heat-resistant clothing, house wrapping paper, etc. . In particular, since it is excellent in mechanical properties and heat resistance, it can be suitably used as reinforcing fibers such as cement, rubber, and resin.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further in detail, this invention is not limited at all by these Examples. In the following examples, the light transmittance of the film, the softening point temperature (hot water resistance), and the elastic modulus of the fiber are those measured by the following methods.

[Measurement of light transmittance of film]
The light transmittance of the film was measured at 380 to 780 nm using a Hitachi spectrophotometer U-4100.

[Softening point temperature of film (hot water resistance)]
The softening point temperature of the film in hot water was fixed to a metal frame having a circular hole with a diameter of 1 cm using an automatic softening point temperature measuring device manufactured by Elex Chemical, and the center of the hole. A sphere with a diameter of 0.95 cm and a weight of 3.526 g was placed on the surface, and the temperature when the sphere dropped 2.5 cm during the temperature rising process from 30 ° C. to 5 ° C./min was measured with a sensor. .

[Water swelling degree of film]
The degree of water swelling of the film was determined by immersing a 10 cm × 15 cm film in 1 L of 30 ° C. pure water for 30 minutes, removing the surface moisture with a filter paper, and then measuring the film mass W1 measured with a precision balance, It calculated using the following formula from film mass W2 dried for 16 hours with a 105 degreeC hot air dryer.
Swelling degree (%) = (W1 / W2) × 100

[Elastic modulus of fiber]
In accordance with the JIS-1013 test method, a pre-humidified yarn was measured under the conditions of a test length of 20 cm, an initial load of 0.25 g / d and a tensile speed of 50% / min, and an average value of n = 20 was adopted. In addition, the elastic modulus retention at high temperature, which indicates heat resistance, is measured by measuring the elastic modulus (high temperature elastic modulus) at 100 ° C. by attaching an air thermostat to the tensile tester, and the ratio of the high temperature elastic modulus to the room temperature elastic modulus ( %).

[Example 1]
(1) PVA aqueous solution was adjusted so that it might become 12 mass parts of glycerol as a plasticizer with respect to 100 mass parts of PVA polymers with an average degree of polymerization of 2400 and a saponification degree of 99.9 mol% (A).
(2) Next, undried sulfite bleached softwood pulp equivalent to 2 g in dry mass (mainly composed of fibers having a fiber diameter exceeding 1000 nm), 0.025 g of TEMPO (2,6,6, -tetramethylpiperidine) 1-oxyl) and 0.25 g of sodium bromide were dispersed in 150 ml of water, and then 13 parts by mass of an aqueous sodium hypochlorite solution containing 2.5 mmol of sodium hypochlorite per 1 g of pulp. The reaction was started by adding sodium hypochlorite so that. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10.5. When the pH no longer changes, the reaction is considered to be complete, the reaction product is filtered through a glass filter, washed with a sufficient amount of water and filtered five times to impregnate 25 parts by mass of water with a solid content. Reactant fibers were obtained.
(3) Next, water was added to the reactant fiber to form a 2 part by mass slurry, which was then treated with a rotary blade mixer for about 5 minutes. Since the viscosity of the slurry significantly increased with the treatment, water was gradually added and the dispersion treatment with the mixer was continued until the solid content concentration became 0.15 parts by mass. The dispersion of fine cellulose fibers having a cellulose concentration of 0.15 parts by mass thus obtained was subjected to removal of suspended matters by centrifugation and then dried to obtain cellulose nanofiber aggregates. The wide-angle X-ray diffraction image of the obtained cellulose shows that it consists of cellulose nanofibers with cellulose I-type crystal structure, and the presence of carbonyl groups was confirmed from the infrared spectrum pattern of the same cellulose nanofiber aggregates. It was. In addition, the average fiber diameter of the cellulose nanofiber was 4 nm, and the total of the amount of carboxy and the amount of aldehyde was 0.6 mmol / g with respect to the mass of the cellulose nanofiber.
(4) The cellulose nanofiber aggregate was added to water so as to be 3 parts by mass and stirred to obtain a cellulose nanofiber dispersion solution (B). (B) was added to 100 parts by mass of PVA in (A) such that the cellulose nanofibers were 1.0 part by mass, and the mixture was stirred to obtain a film stock solution.
(5) This was dried on a metal roll at 60 ° C. to obtain a PVA film having a thickness of 75 μm. Further, the obtained film was fixed to a frame and heat-treated at 120 ° C. for 10 minutes. Table 1 shows the light transmittance, softening point temperature, and degree of swelling of the obtained film.
(6) Appearance of the resulting film is good, there are no thickness spots or irregularities, light transmittance is 90.8%, softening point temperature is 70.3 ° C., swelling degree is 220%, transparency, It was excellent in hot water resistance.

[Example 2]
(1) A film was obtained in the same manner as in Example 1 except that the composite amount of cellulose nanofibers was 0.2 parts by mass. Table 1 shows the light transmittance, softening point temperature, and degree of swelling of the obtained film.
(2) Appearance of the obtained film was good, there were no thickness spots or irregularities, light transmittance was 90.8%, softening point temperature was 69.0 ° C., swelling degree was 220%, transparency, It was excellent in hot water resistance.

[Example 3]
(1) A film was obtained in the same manner as in Example 1 except that the composite amount of cellulose nanofibers was changed to 3.0 parts by mass. Table 1 shows the light transmittance, softening point temperature, and degree of swelling of the obtained film.
(2) Appearance of the obtained film is good, there is no thickness unevenness or irregularity, light transmittance is 90.7%, softening point temperature is 74.1 ° C., swelling degree is 220%, transparency, It was excellent in hot water resistance.

[Example 4]
(1) The composite amount of cellulose nanofibers was 8.0 parts by mass, and a film stock solution was obtained in the same manner as in Example 1.
(2) This was dried on a PET film at 25 ° C. to obtain a PVA film having a thickness of 75 μm. Further, the obtained film was fixed to a frame and heat-treated at 135 ° C. for 10 minutes. Table 1 shows the light transmittance, softening point temperature, and degree of swelling of the obtained film.
(3) Appearance of the obtained film is good, there is no thickness unevenness or unevenness, light transmittance is 90.6%, softening point temperature is 83.0 ° C., swelling degree is 220%, transparency, It was excellent in hot water resistance.

[Example 5]
(1) PVA having a viscosity average polymerization degree of 1700 and a saponification degree of 99.9 mol% was added to water so as to have a concentration of 20 parts by mass and dissolved in a nitrogen atmosphere at 90 ° C. (A), while the average fiber Add cellulose nanofibers with a diameter of 4 nm and the total amount of carboxy and aldehyde in the cellulose nanofibers to 0.6 mmol / g with respect to the mass of the cellulose nanofibers to 3 parts by mass in water, and stir Thus, a cellulose nanofiber dispersion solution was obtained (B). (B) was added to 100 parts by mass of PVA in (A) so that the cellulose nanofibers would be 1.0 part by mass, and mixed and stirred to obtain a spinning dope.
(2) The obtained spinning solution was subjected to dry and wet spinning in a methanol solution at 5 ° C. through a nozzle having a hole diameter of 0.08 mm and the number of holes of 108.
(3) The obtained solidified yarn was wet-stretched 4 times in methanol, further dried with hot air at 120 ° C. and wound up to obtain a spinning yarn.
(4) The obtained spinning yarn was stretched so that the total draw ratio (wet draw ratio × hot air furnace draw ratio) was 15 times in a hot air drawing furnace at 180 ° C. in the first furnace and 235 ° C. in the second furnace. To obtain a fiber. Table 2 shows the evaluation results of mechanical properties.
(5) Appearance of the obtained fiber was good, there was no yarn unevenness, the single yarn fineness was 6.8 dtex, the elastic modulus at room temperature and 100 ° C. of the fiber was 334 cN / dtex, 150 cN / dtex, and the retention rate was 45%. It was excellent in heat resistance.

[Example 6]
(1) A fiber was obtained by spinning and stretching according to the method described in Example 5, except that the amount of cellulose nanofibers to be mixed was 0.2 parts by mass. Table 2 shows the evaluation results of mechanical properties.
(2) Appearance of the obtained fiber was good, there was no yarn unevenness, the single yarn fineness was 6.5 dtex, the elastic modulus of the fiber at room temperature and 100 ° C. was 340 cN / dtex, 110 cN / dtex, and the retention rate was 32%, respectively. It was excellent in heat resistance.

[Example 7]
(1) A fiber was obtained by spinning and stretching by the method described in Example 5 except that the amount of cellulose nanofibers to be mixed was 8.0 parts by mass. Table 2 shows the evaluation results of mechanical properties.
(2) Appearance of the obtained fiber was good, there was no yarn unevenness, the single yarn fineness was 7.0 dtex, the elastic modulus at room temperature and 100 ° C. of the fiber was 260 cN / dtex and 130 cN / dtex, respectively, and the retention rate was 50%. It was excellent in heat resistance.

[Comparative Example 1]
(1) A film was prepared by the method described in Example 1 except that no nanofiber was contained. Table 1 shows the evaluation results of light transmittance and hot water cutting temperature.
(2) Although the appearance of the obtained film is good and the light transmittance is excellent at 90.8%, the softening point temperature is 68.5 ° C., the swelling degree is 220%, and the hot water resistance is low. there were.

[Comparative Example 2]
(1) A fiber was obtained by spinning and drawing according to the method described in Example 5 except that no nanofiber was contained. The evaluation results of mechanical properties are shown in Table 1.
(2) Appearance of the obtained fiber was good, there was no yarn unevenness, and the elastic modulus at room temperature was as high as 322 cN / dtex, but the elastic modulus at 100 ° C. was as low as 84 cN / dtex.

[Comparative Example 3]
(1) Except that water was added to the sulfite bleached softwood pulp (mainly composed of fibers having a fiber diameter exceeding 1000 nm) used as a raw material in Example 1, and 3 parts by mass of the dispersion was prepared by mixer treatment. The fiber was obtained by spinning and drawing by the method described in 5. The evaluation results of mechanical properties are shown in 2. The cellulose nanofiber used here is not subjected to so-called oxidation treatment, and the total amount of carboxy and aldehyde in the cellulose nanofiber is about 0.01 mmol / g with respect to the mass of the cellulose nanofiber.
(2) Appearance of the obtained fiber was good, there was no yarn unevenness, and the elastic modulus at room temperature was as high as 320 cN / dtex, but the elastic modulus at 100 ° C. was as low as 85 cN / dtex.

[Comparative Example 4]
(1) A fiber was obtained by spinning and stretching according to the method described in Example 5, except that the amount of cellulose nanofibers to be mixed was 15.0 parts by mass. Table 2 shows the evaluation results of mechanical properties.
(2) The obtained fiber had not only a lot of fluff but also a severe fineness spot. The elastic modulus at room temperature and 100 ° C. is 200 cN / dtex, 58 cN. It was dtex and was not excellent in heat resistance.

[Comparative Example 5]
(1) Instead of cellulose nanofibers, synthetic mica (manufactured by Co-op Chemical Co., Ltd .: trade name ME100), which is a nano-layered compound, generally considered to be capable of imparting heat resistance and hot water resistance to a polymer material A fiber was obtained by spinning and drawing by the method described in Example 5 except that 0 part by mass was added. Table 2 shows the evaluation results of mechanical properties.
(2) The obtained fiber was somewhat fuzzy and the room temperature elasticity was as high as 290 cN / dtex, but the elasticity at 100 ° C. was as low as 80 cN / dtex.

  The composition of the present invention is excellent in transparency and heat resistance or hot water, and is particularly useful as a material for films and fibers. Furthermore, it can be applied to paper processing agents, fiber processing agents, fiber glues, paints, coating agents, adhesives, and the like.

Claims (4)

  A composite of a polyvinyl alcohol polymer and a cellulose nanofiber having an average fiber diameter of 2 to 150 nm, wherein at least one functional group selected from the group consisting of a carboxyl group and an aldehyde group is part of the hydroxyl group of cellulose. The content of cellulose nanofibers that are oxidized and the total amount of carboxyl groups and aldehyde groups is 0.1 to 2.2 mmol / g with respect to the mass of the cellulose nanofibers is 100 parts by mass of the polyvinyl alcohol polymer. The cellulose nanofiber composite polyvinyl alcohol-based polymer composition, which is 0.1 to 10 parts by mass with respect to the composition.   A cellulose nanofiber composite polyvinyl alcohol system, wherein the cellulose nanofiber according to claim 1 is a cellulose nanofiber that is oxidized by using natural cellulose as a raw material, using an N-oxyl compound as an oxidation catalyst in water, and acting on a co-oxidant. Polymer composition.   The film which consists of a cellulose nanofiber composite polyvinyl alcohol-type polymer composition of Claim 1 or 2.   The fiber which consists of a cellulose nanofiber composite polyvinyl alcohol-type polymer composition of Claim 1 or 2.