JP2011173993A - Composite composition and composite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite composition that has a negative coefficient of thermal expansion and can easily achieve the production of a composite having a desired coefficient of thermal expansion, for example, a near zero coefficient of thermal expansion, by mixing other compositions and to provide a composite that is produced by molding the composite composition into a predetermined shape and has a desired coefficient of thermal expansion, for example, a near zero coefficient of thermal expansion, and various properties of high strength and a low coefficient of humidity expansion. <P>SOLUTION: The composite composition includes a fibrous filler and a resin material and can produce a composite by molding the composite composition into a predetermined shape. The fibrous filler used in the composite composition is composed of a polysaccharide material. The resin material used in the composite composition is characterized in that it can disperse the fibrous filler so that the average fiber diameter of the fibrous filler is reduced to not more than 100 μm and that the content of hydrogen atom which can form a hydrogen bond is less than 0.01 mol/g. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite composition containing a fibrous filler and a composite.

  In the past, it has been widely practiced to add a filler to a resin material. As such fillers, spherical fillers such as silica fine particles and metal fine particles, and rod-like fillers such as whiskers are known, and by blending the filler, the thermal expansion coefficient of the resin material is reduced, the elastic modulus, Mechanical strength such as bending strength can be increased.

  In recent years, composites using cellulose as a filler have been proposed. This composite contains fine fibers of cellulose. Examples of the cellulose fibers include cellulose microfibrils obtained by mechanically refining cellulose fibrillar substances (for example, patent documents). 1).

  A composite containing such fine cellulose fibers has characteristics such as high mechanical strength and transparency, light weight, and low thermal expansion coefficient. For this reason, application of this feature is expected in various fields such as an optical field, a structural material field, a building material field, a precision machine field, and a semiconductor field.

  For example, glass plates are widely used as display substrates for liquid crystal display elements and organic EL elements, color filter substrates, and solar cell substrates. However, in recent years, plastic materials have been studied as an alternative to glass plates because they are easily broken, cannot be bent, have a large specific gravity, and are not suitable for weight reduction.

  Examples of the resin used for the plastic substrate for display elements include a composition comprising an alicyclic epoxy resin, an alcohol, and a curing catalyst (see, for example, Patent Document 2), an alicyclic epoxy resin, and an acid anhydride partially esterified with an alcohol. A resin composition comprising a physical curing agent and a curing catalyst (see, for example, Patent Document 3), an alicyclic epoxy resin, an acid anhydride curing agent having a carboxylic acid, and a curing catalyst (for example, (See Patent Document 4). However, the linear expansion coefficient of a plastic substrate made of these resin compositions is considerably larger than that of a thin film material such as Si laminated thereon. For this reason, such mismatch of linear expansion coefficients causes thermal stress, distortion, cracks and peeling of the formed layer, and causes the plastic substrate on which the layer is formed to be curved (for example, Non-Patent Document 1). .

JP 2003-201695 A JP-A-6-337408 JP 2001-59015 A JP 2001-59014 A

Monthly Display January 2000 p. 35

  An object of the present invention is to provide a composite composition having a negative thermal expansion coefficient, and a composite formed by molding the composite composition into a predetermined shape. Another object of the present invention is to provide a composite having a desired thermal expansion coefficient, for example, a thermal expansion coefficient close to zero, and various characteristics such as high strength and low humidity expansion coefficient by mixing with other compositions.

Such an object is achieved by the present inventions (1) to (12) below.
(1) A composite composition comprising a fibrous filler and a resin material,
The fibrous filler is composed of a polysaccharide material,
The resin material, the fibrous filler, the average fiber diameter are those dispersible possible so as to be 100μm or less, and the content capable of forming a hydrogen atom hydrogen bonds is less than 0.01 mol / g A composite composition characterized by the above.

  (2) The composite composition according to (1), wherein the polysaccharide material is cellulose or chitin.

  (3) The composite composition according to (2), wherein the fibrous filler composed of cellulose is a cellulose fiber obtained by refining a cellulose raw material by at least one of chemical treatment and mechanical treatment.

  (4) The above-mentioned (2) or (3), wherein the fibrous filler composed of the cellulose is obtained by substituting at least one of an aldehyde group and a carboxyl group in the hydroxyl group in the cellulose molecule contained. A composite composition according to 1.

  (5) The composite according to any one of (1) to (4), wherein the hydrogen atom capable of forming a hydrogen bond is a hydrogen atom covalently bonded to any one of a nitrogen atom, an oxygen atom, and a fluorine atom. Composition.

  (6) The composite composition according to any one of (1) to (5), wherein the resin material is a water-soluble polymer.

  (7) The composite composition according to any one of (1) to (6), wherein the resin material includes N-vinylpyrrolidone as a monomer.

  (8) The composite composition according to any one of (1) to (7), wherein the resin material includes an acrylate ester as a monomer.

  (9) The composite composition according to (8), wherein the resin material is a copolymer of an acrylate and an acrylate.

  (10) The composite composition according to any one of (1) to (9), wherein the resin material includes polyethylene glycol having a molecular weight exceeding 200.

  (11) The composite composition according to any one of (1) to (10), wherein the fibrous filler content is 0.1 to 99.9% by weight.

  (12) A composite formed by molding the composite composition according to any one of (1) to (11) above.

According to the present invention, a composite composition having a negative coefficient of thermal expansion is obtained.
According to the present invention, the composite composition and another composition are mixed and formed into a predetermined shape, and a desired thermal expansion coefficient, for example, a thermal expansion coefficient close to zero, is obtained. And a composite having various properties such as high strength and low humidity expansion coefficient.

  Hereinafter, the composite composition and composite of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<Composite composition>
The composite composition of the present invention includes a fibrous filler and a resin material, and can form a molded body (composite) by molding into a predetermined shape, for example.

When a composite composition containing a fibrous filler is molded into a molded body (composite), the fibrous fillers are intertwined with each other and dispersed in the resin material to enhance the mechanical properties of the molded body. For this reason, the obtained molded body has a high mechanical strength and a low humidity expansion coefficient.
The fibrous filler used in the present invention is composed of a polysaccharide material.

  On the other hand, the resin material used in the present invention can disperse the fibrous filler so that the average fiber diameter is 100 μm or less, and the content of hydrogen atoms capable of forming hydrogen bonds is 0.01 mol. What is characterized by being less than / g is used.

  The composite composition containing such a fibrous filler and a resin material has a negative thermal expansion coefficient. For this reason, the composite which has a desired thermal expansion coefficient, for example, the thermal expansion coefficient close | similar to zero, can be easily implement | achieved by mixing the composite composition of this invention with another composition. In the present specification, the thermal expansion coefficient is also referred to as “thermal expansion coefficient”.

Hereinafter, the fibrous filler and the resin material will be described in detail.
(Fibrous filler)
As described above, the fibrous filler contained in the composite composition of the present invention is composed of a polysaccharide material.

  Examples of the polysaccharide material include cellulose, chitin, chitosan and the like. Since these polysaccharide materials are insoluble in water and relatively easy to disperse in water, fibrous fillers composed of such polysaccharide materials (hereinafter also referred to as “polysaccharide fibers”). By using this, a composite composition having high mechanical properties and a low thermal expansion coefficient can be obtained.

  Among the polysaccharide fibers, examples of the fibers composed of cellulose (cellulose fibers) include natural cellulose fibers and regenerated cellulose fibers.

  Among these, natural cellulose fibers include refined pulp obtained from conifers and broad-leaved trees, cellulose fibers obtained from cotton linters and cotton lint, cellulose fibers obtained from seaweeds such as valonia and rhododendrons, cellulose fibers obtained from sea squirts, and bacterial fibers. Examples include cellulose fibers to be produced. On the other hand, examples of the regenerated cellulose fiber include those obtained by once dissolving the natural cellulose fiber and then regenerating it into a fiber form with the cellulose composition.

  In the present invention, highly crystalline cellulose fibers are preferably used. Since such a cellulose fiber has a particularly small linear expansion coefficient and high mechanical strength, it is suitably used as a fibrous filler. From this viewpoint, natural cellulose fibers are preferable to regenerated cellulose fibers as the cellulose fibers used in the present invention.

  Moreover, although the crystallinity degree of a cellulose fiber is not specifically limited, It is preferable that it is 50 to 95%, and it is more preferable that it is 70 to 90%. Cellulose fibers having such a crystallinity have particularly high mechanical properties of the fibers themselves, and can particularly improve the mechanical properties of the composite.

  On the other hand, among the polysaccharide fibers, chitin fibers are particularly preferably used as fibers other than cellulose fibers. The chitin fiber is produced, for example, by dissolving chitin in an alkaline solution and fiberizing it by the viscose rayon method.

  The average fiber diameter of the polysaccharide fiber is preferably 1-1000 nm, more preferably 2-300 nm, and even more preferably 4-200 nm. When the average fiber diameter of the polysaccharide fiber is within the above range, it is prevented that the fibrous filler becomes a light transmission inhibiting factor in the finally obtained composite. For this reason, a highly transparent composite can be obtained by using a resin material having transparency.

  The cellulose fiber used in the present invention may be such a polysaccharide fiber alone, or may be an aggregate of a plurality of polysaccharide fibers. In the case of an aggregate of polysaccharide fibers, the average fiber diameter of the aggregate is 100 μm or less in the composite composition.

Here, the measurement of the average fiber diameter of polysaccharide fiber can be performed as follows.
First, a dispersion of polysaccharide fibers having a solid content of 0.05 to 0.1% by weight was prepared, and the dispersion was cast on a carbon film-coated grid, and a transmission electron microscope (TEM) observation sample And Moreover, when the polysaccharide fiber of a big fiber diameter is included, you may observe the surface cast on glass with a scanning electron microscope (SEM).

  At the time of microscopic observation, an electron microscope image is acquired at a magnification of 5000 times, 10000 times, or 50000 times according to the fiber diameter of the polysaccharide fiber. At this time, when assuming an axis of arbitrary image width in the obtained image, sample conditions and observation conditions (magnification, etc.) so that 20 or more polysaccharide fibers intersect at least the axis. Set.

  Then, two random axes, vertical and horizontal, per image are drawn with respect to the observation image satisfying this condition, and the fiber diameter of the fiber intersecting with each axis is visually read. It should be noted that at least three observation images are acquired with an electron microscope while shifting the photographing positions so as not to overlap each other on the sample surface, and the fiber diameter is read for each image as described above. Thereby, the fiber diameter information is obtained for at least 20 × 2 × 3 = 120 polysaccharide fibers. Based on the fiber diameter data thus obtained, the average fiber diameter is calculated.

  On the other hand, the average length of the polysaccharide fiber (fibrous filler) is not particularly limited, but is preferably 100 nm or more, and more preferably 200 nm or more. Thereby, the reinforcing effect of the fibrous filler becomes more remarkable, and in the composite, the mechanical strength is further improved and the humidity expansion coefficient is further reduced.

(Fabric filler production method)
Next, a method for producing a fibrous filler will be described. Here, a method for producing a cellulose fiber will be described as an example.

  The cellulose fiber used in the present invention may be obtained by any known method, and its production method is not particularly limited. As an example, a cellulose raw material (natural cellulose or regenerated cellulose) is treated with a medium stirring mill processing device, Those that are mechanically refined by various miniaturization devices such as a vibration mill treatment device, a high-pressure homogenizer treatment device, and an ultra-high pressure homogenizer treatment device are used. As another method, cellulose fibers obtained by an electrospinning method, a steam jet method, an APEX (registered trademark) technique (Polymer Group. Inc) method, or the like can also be used. However, considering energy efficiency and the like, the cellulose raw material is most preferably a cellulose fiber obtained by a method involving chemical treatment shown below.

  The cellulose fiber production method described below is a method for producing a cellulose fiber (nanocellulose fiber) by subjecting a cellulose raw material to chemical treatment and then subjecting it to a mechanical treatment to disperse it in a dispersion medium.

  Specifically, [1] 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 a co-oxidant is allowed to act to oxidize natural cellulose to obtain reactant fibers; 2) a purification step of obtaining a reactant fiber impregnated with water by removing impurities, and [3] a dispersion step of dispersing the reactant fiber impregnated with water in a dispersion medium. Each step will be described in detail below.

[1] Oxidation reaction step First, in the oxidation reaction step, a dispersion in which a cellulose raw material is dispersed in water is prepared. Here, as the cellulose raw material to be used, those subjected to a treatment for increasing the surface area such as beating in advance are preferably used. It is because reaction efficiency can be raised by this and productivity can be raised. Moreover, as a cellulose raw material, it is preferable to use what was stored by Never Dry after isolation and purification. As a result, since the microfibril bundle constituting the cellulose raw material is easily swollen, it is possible to increase the reaction efficiency and reduce the number average fiber diameter after the refining treatment.

  When water is used as the dispersion medium for the cellulose raw material in this step, the cellulose concentration in the dispersion (reaction aqueous solution) is arbitrary as long as the reagent can be sufficiently diffused. 5% by weight or less based on the weight of

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

  Examples of the co-oxidant include hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogenic acid or a salt thereof, hydrogen peroxide, and a perorganic acid. Hypohalite, specifically, sodium hypochlorite and sodium hypobromite are preferably used. 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 preferably about 1 to 40 times mol, more 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 in the range of about 4 to 40 ° C., but the reaction can be performed at room temperature, and the temperature is not particularly required to be controlled.

  A carboxyl group is introduced into the cellulose molecule by the co-oxidant so as to replace the hydroxyl group, but in obtaining the fine cellulose fiber used in the present invention, the amount of carboxyl group required differs depending on the type of cellulose raw material. Accordingly, the amount of the co-oxidant added and the time for which the co-oxidant is allowed to act may be set accordingly. Specifically, the larger the amount of carboxyl groups, the smaller the maximum fiber diameter and the number average fiber diameter of the cellulose fiber finally obtained, so that it may be set in consideration thereof.

  For example, when wood pulp and cotton pulp are used as the cellulose raw material, the required carboxyl group amount is 0.2 to 2.2 mmol / g with respect to the cellulose raw material, and bacterial cellulose (BC) or sea squirt as the cellulose raw material When using the cellulose extracted from the above, the required carboxyl group amount is 0.1 to 0.8 mmol / g. Thus, the optimal amount of carboxyl groups can be introduced into each cellulose raw material by controlling the addition amount of the co-oxidant and the reaction time according to the type of the cellulose raw material.

  In addition, based on the introduction amount of the carboxyl group as described above, the addition amount of the co-oxidant can be derived. As an example, about 0.5 to 8 mmol of the co-oxidant is added to 1 g of the cellulose raw material. The reaction time is preferably about 5 to 120 minutes, and at most 240 minutes.

  In addition, although a carboxyl group is introduce | transduced into a cellulose molecule through this oxidation reaction process, an aldehyde group may be introduce | transduced depending on the progress degree of an oxidation process. Therefore, a part of the hydroxyl group of the cellulose molecule after the end of this oxidation reaction step is substituted with at least one of an aldehyde group and a carboxyl group.

[2] Purification step In the purification step, compounds other than the reaction fiber and water contained in the reaction slurry, specifically, compounds such as unreacted hypochlorous acid and various by-products are removed from the system. It is intended to be removed. At this stage, the reaction fiber is usually not dispersed evenly to the nanofiber unit. Therefore, the high purity (99% by weight or more) should be achieved by repeating the usual purification method, that is, washing with water and filtration. Can do.

  As a purification method in this purification step, any apparatus may be used as long as it is an apparatus (for example, a continuous decander) that can achieve the above-described object, such as a method using centrifugal dehydration. The reactant fibers thus obtained are in the range of approximately 10 to 50% by weight as the solid content (cellulose) concentration in the squeezed state. In consideration of dispersion in the nanofiber unit in the subsequent step, it is not preferable to make the solid content concentration higher than 50% by weight because extremely high energy is required for dispersion.

[3] Dispersion Step In the above-described purification step, a reaction fiber (water dispersion) impregnated with water is obtained. By dispersing this in a solvent and subjecting it to a dispersion treatment, the fine fibers used in the present invention are obtained. Cellulose fibers are obtained in the state of an aqueous dispersion.

  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 and the like. Moreover, these mixtures can also be used conveniently.

  In addition, when diluting and dispersing with the above-described reactant fiber solvent, nanofiber level fiber dispersion is efficiently obtained by performing stepwise dispersion in which the solvent is gradually added and dispersed. be able to. In view of operational problems, after the dispersion step, the dispersion conditions may be selected so that the dispersion is in a viscous state or gel.

  Here, various devices can be used as the disperser used in the dispersion step. For example, depending on the progress of the reaction in the reaction product fiber (the amount of conversion to aldehyde groups and carboxyl groups), a screw-type mixer, paddle mixer, and disper type are suitable under conditions where the reaction proceeds appropriately. A dispersion of fine cellulose fibers can be sufficiently obtained with a general-purpose disperser as an industrial production machine such as a mixer or a turbine mixer.

  Also, use equipment with strong beating ability under high speed rotation such as homomixer, high pressure homogenizer, ultrasonic homogenizer, ultrasonic dispersion treatment, beater, disc type refiner, conical type refiner, double disc type refiner, grinder This allows more efficient and advanced downsizing. Furthermore, by using these apparatuses, 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). Can also provide a highly refined dispersion of fine cellulose fibers.

  Next, a method for recovering fine cellulose fibers from a dispersion in which fine cellulose fibers are dispersed in a dispersion medium will be described.

  Specifically, fine cellulose fibers can be recovered by drying the dispersion of fine cellulose fibers described above.

  Here, for example, when the dispersion medium is water, the drying is performed by freeze-drying. When the dispersion medium is a mixture of water and an organic solvent, drying by a drum dryer or, in some cases, spray drying by a spray dryer. Can be preferably used.

  In addition, in the dispersion of fine cellulose fibers described above, a water-soluble polymer (polyethylene oxide, polyvinyl alcohol, polyacrylamide, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, starch, natural gums, etc.) is used as a binder. Sugars (glucose, fructose, mannose, galactose, trehalose, etc.) may be added. Since these binder components have a very high boiling point and affinity for cellulose, they are dried by a general-purpose drying method such as a drum dryer or a spray dryer by adding these components to the dispersion. Even in such a case, aggregation when dispersed again in the dispersion medium is prevented, and a dispersion of fine cellulose fibers dispersed as nanofibers can be obtained with certainty. In this case, the amount of the binder added to the dispersion is preferably in the range of 10 to 80% by weight with respect to the reactant fiber.

  The recovered fine cellulose fibers are again mixed into the dispersion medium (water, organic solvent or a mixture thereof) and applied with an appropriate dispersion force (for example, using various dispersers used in the dispersion step described above). By performing dispersion), a dispersion of fine cellulose fibers can be obtained.

  In the fine cellulose fiber used in the present invention, a part of the hydroxyl group of cellulose is oxidized to a carboxyl group or an aldehyde group. Moreover, it is preferable that this fine cellulose fiber has a cellulose I type crystal structure. In addition, that a fine cellulose fiber has an I type crystal structure means that it is the fiber which surface-oxidized the natural cellulose solid raw material and refined | miniaturized.

In addition, the fact that the fine cellulose fiber has the I-type crystal structure is that two positions of 2 theta = 14-17 ° and 2 theta = 22-23 ° in the diffraction profile obtained by wide-angle X-ray diffraction image measurement. Can be identified based on having a typical peak. Furthermore, the introduction of an aldehyde group or a carboxyl group into the cellulose of the fine cellulose fiber means that the absorption due to the carbonyl group (1608 cm) in the total reflection infrared spectroscopic spectrum (ATR) of the sample from which moisture has been completely removed. ^-1 vicinity) can be confirmed. In particular, when an acid-type carboxyl group (—COOH) is introduced into cellulose, absorption is present at 1730 cm ⁻¹ in the above measurement.

  For the reasons described above, the fine cellulose fibers can be stably present as finer fiber diameters as the total amount of carboxyl groups and aldehyde groups present in the cellulose is larger. For example, in the case of wood pulp and cotton pulp, the total amount of carboxyl groups and aldehyde groups present in fine cellulose fibers (hereinafter referred to as “total amount”) is 0.2 to When the concentration is 2.2 mmol / g, preferably 0.5 to 2.2 mmol / g, more preferably 0.8 to 2.2 mmol / g, a cellulose fiber excellent in stability as a nanofiber can be obtained. Moreover, when the fiber diameter of microfibrils such as cellulose extracted from BC or sea squirt is relatively thick (average fiber diameter is on the order of several tens of nm), the total amount is 0.1 to 0.8 mmol / g, If it is 0.2-0.8 mmol / g, the cellulose fiber excellent in stability as a nanofiber will be obtained. In addition, when the total amount is smaller than the lower limit, the difference in physical properties from the conventionally known refined cellulose fibers (for example, the dispersion stabilization effect in the dispersion) is reduced and the minute amount is small. Since it becomes difficult to obtain as a fiber of a fiber diameter, it is not preferable.

  Furthermore, the introduction of a carboxyl group with respect to the aldehyde group, which is a nonionic substituent, produces an electrical repulsive force. This increases the tendency of the microfibrils to fall apart without maintaining agglomeration, thereby further increasing the stability of the nanofiber as a dispersion. For example, in the case of wood pulp or cotton pulp, the amount of carboxyl groups present in fine cellulose fibers is 0.2 to 2.2 mmol / g, preferably 0.4 to 2.2 mmol / g, based on the weight of the cellulose fibers. More preferably, when it is 0.6 to 2.2 mmol / g, a cellulose fiber having extremely excellent stability as a nanofiber can be obtained. In the case of cellulose having a relatively large fiber diameter of microfibrils, such as cellulose extracted from BC or sea squirt, the amount of carboxyl groups is 0.1 to 0.8 mmol / g, preferably 0.2 to 0.00. A cellulose fiber excellent in stability as a nanofiber is obtained as it is 8 mmol / g.

  Here, the amount (mmol / g) of aldehyde group and carboxyl group of cellulose relative to the weight of cellulose fiber is evaluated by the following method.

60 ml of a slurry having a concentration of 0.5 to 1% by weight was prepared using a cellulose sample with a precisely weighed dry weight, adjusted to pH 2.5 with a 0.1 M hydrochloric acid aqueous solution, An aqueous sodium solution is dropped to measure the electrical conductivity of the slurry. This measurement is continued until the pH is about 11. The amount of functional groups is calculated from the amount of sodium hydroxide (V) consumed in the neutralization step of the weak acid with a slow change in electrical conductivity using the following formula. The calculated functional group amount is defined as “functional group amount 1”. This 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 is calculated again by the above method. The calculated functional group amount is defined as “functional group amount 2”. Then, the amount of functional groups added by this oxidation (= functional group amount 2−functional group amount 1) is calculated. This amount of functional groups indicates the amount of aldehyde groups.
The cellulose fiber used for this invention is obtained as mentioned above.

(Resin material)
Conventionally, as a resin material used for a composite composition containing a fibrous filler, various curable resin materials, various plastic resin materials, and the like have been used. However, when these resin materials are used, the composite composition has a positive thermal expansion coefficient, and a composite composition having a negative thermal expansion coefficient cannot be realized.

  In response to such a problem, the present inventor has made the resin material used for the composite composition particularly dispersible with respect to the fibrous filler composed of the polysaccharide material and the content of hydrogen atoms capable of forming hydrogen bonds. Pay attention. Then, when these factors satisfy predetermined conditions, it is found that the above problem can be solved, that is, a composite composition having a negative thermal expansion coefficient can be realized, and the present invention is completed. It came.

  That is, as described above, the resin material used in the present invention can disperse the fibrous filler added together with the resin material so that the average fiber diameter is 100 μm or less, and forms hydrogen bonds. The possible hydrogen atom content is less than 0.01 mol / g. By mixing the resin material having such characteristics with a fibrous filler, a composite composition having a negative thermal expansion coefficient can be realized.

  As described above, the composite composition having a negative thermal expansion coefficient can be mixed with the composition having a positive thermal expansion coefficient to cancel the thermal expansion characteristics of the two. As a result, the coefficient of thermal expansion of the mixture and the composite formed by molding the mixture can be made substantially zero. In addition, by changing the mixing ratio of the two, the thermal expansion coefficient of the mixture can be changed as appropriate, and a mixture and a composite having a desired thermal expansion coefficient can be realized.

  For example, when the composite obtained in this manner is bonded to another member, stress concentration on the bonding interface can be suppressed. Specifically, by producing a composite having a thermal expansion coefficient substantially equal to the thermal expansion coefficient of the other member, almost no stress associated with the thermal expansion difference is generated between the two used for bonding. For this reason, even if the external temperature changes, it is possible to reliably prevent problems such as interface peeling caused by stress concentration.

  Further, according to the present invention, a composite having a smaller thermal expansion coefficient than that of an inorganic material such as a glass material can be realized. That is, the composite of the present invention has a thermal expansion coefficient equal to or smaller than that of an inorganic material such as a glass material, and also has excellent characteristics such as light weight, high strength, and low humidity expansion coefficient. It is extremely useful as a substitute for glass members.

  Although it is not clear about the mechanism in which the effect as described above produced by the composite composition of the present invention is manifested, it is presumed as follows.

  First, the composite composition of the present invention includes a fibrous filler containing polysaccharide fibers and a resin material having the characteristics as described above.

  The polysaccharide fiber has a hydrophilic functional group in its molecular structure, and this hydrophilic functional group mainly serves as an interaction between the fibrous fillers and between the fibrous filler and the resin material. It is thought to be a factor that brings about an interaction. On the other hand, the resin material has a positive coefficient of thermal expansion.

  When the composite composition of the present invention is heated, in the temperature range below the glass transition temperature or the melting point of the resin material, the resin thermally expands as the temperature rises. Therefore, the entire composite composition once has a positive linear expansion coefficient. Indicates. At this time, the fibrous filler in the composite composition is pulled by the expansion of the resin due to the interaction with the resin material, and the network formed by the fibrous filler is distorted. Then, when the temperature is continuously raised and the temperature exceeds the glass transition temperature or melting point of the resin material, the viscosity of the resin rapidly decreases, the strain applied to the fibrous filler network is relaxed, and shrinkage occurs. It is considered that the composition exhibits a negative linear expansion coefficient. In addition, at this time, the strength of interaction between the resin material and the fibrous filler differs depending on the content of hydrogen atoms capable of forming hydrogen bonds in the resin material, and thus the resin does not show a negative linear expansion coefficient. It is thought that a difference in resin occurs.

  In addition, if the resin material used in the present invention can disperse the fibrous filler so that the average fiber diameter is 100 μm or less, significant aggregation of the fibrous filler in the composite composition is prevented. It is possible to prevent the interaction as described above from being suppressed due to aggregation. The average fiber diameter of the fibrous filler can be measured in the same manner as the average fiber diameter of the polysaccharide fibers described above.

  Furthermore, in the resin material used in the present invention, if the content of hydrogen atoms capable of forming hydrogen bonds is less than 0.01 mol / g, preferably less than 0.005 mol / g, the hydrophilicity contained in the fibrous filler It is possible to prevent a strong attractive force based on the hydrogen bond between the functional group and the hydrogen atom that can form a hydrogen bond contained in the resin material.

  Due to the above mechanism, the composite composition of the present invention is considered to have a negative coefficient of thermal expansion.

  Note that a hydrogen atom capable of forming a hydrogen bond is a hydrogen atom covalently bonded to any one of a nitrogen atom, an oxygen atom, and a fluorine atom. Since such hydrogen atoms can form strong hydrogen bonds, it is considered that the thermal expansion coefficient of the composite composition is greatly affected. The inventor paid attention to the causal relationship between the content of hydrogen atoms capable of forming hydrogen bonds and the thermal expansion coefficient of the composite composition, and described the content of hydrogen atoms having a negative thermal expansion coefficient. I found it like this.

  Further, as described above, cellulose fibers and chitin fibers are preferably used for the fibrous filler used in the present invention. These fibers have a hydrophilic functional group in the molecular structure, and the above mechanism. As can be seen, the composite composition will certainly have a negative coefficient of thermal expansion.

  Here, examples of the resin material used in the present invention include various curable resins, various plastic resins, various water-soluble resins (water-soluble polymers), and among these, water-soluble resins are preferably used. By using a water-soluble resin as the resin material, the interaction between the fibrous filler and the resin material is further stabilized, and the fibrous filler is stably dispersed. Specifically, the fibrous filler in the composite composition exhibits stable dispersibility to such an extent that the average fiber diameter is 100 μm or less. As a result, the composite composition is more likely to have a negative coefficient of thermal expansion.

  In particular, the resin material used in the present invention is preferably (i) one containing N-vinylpyrrolidone as a monomer, (ii) one containing an acrylate ester as a monomer, and (iii) one containing polyethylene glycol. In particular, such a resin material can ensure a negative thermal expansion coefficient of the composite composition. Although the detailed reason is not clear, the composite composition is formed by the fact that the interaction between the fibrous filler and the resin material is lower than the positive thermal expansion coefficient of the resin material alone in the temperature range of Tg or higher. It is considered that the thermal expansion coefficient is negative. Specifically, the heat resistance of the composite composition of the present invention is that the resin material is particularly highly dispersible with fibrous filler and has a particularly low content of hydrogen atoms capable of forming hydrogen bonds. This is considered to be a factor in the negative expansion coefficient.

  (I) A resin material containing N-vinylpyrrolidone as a monomer is a water-soluble (hydrophilic) resin and a resin material having a relatively high transparency. Specific examples of such a resin material include a homopolymer of N-vinylpyrrolidone (N-vinyl-2-pyrrolidone), or a copolymer of a monomer of N-vinylpyrrolidone and another monomer. .

  The other monomer is not particularly limited as long as it is copolymerizable with N-vinylpyrrolidone. For example, acrylic acid, methacrylic acid, alkyl esters of acrylic acid (methyl acrylate, ethyl acrylate, etc.), methacrylic acid Alkyl esters (methyl methacrylate, ethyl methacrylate, etc.), aminoalkyl esters of acrylic acid (diethylaminoethyl acrylate, etc.), aminoalkyl esters of methacrylic acid, monoesters of acrylic acid and glycol, monoesters of methacrylic acid and glycol (hydroxy Ethyl methacrylate), alkali metal salt of acrylic acid, alkali metal salt of methacrylic acid, ammonium salt of acrylic acid, ammonium salt of methacrylic acid, aminoalkyl ester of acrylic acid Quaternary ammonium derivatives, quaternary ammonium derivatives of aminoalkyl esters of methacrylic acid, quaternary ammonium compounds of diethylaminoethyl acrylate and methyl sulfate, vinyl methyl ether, vinyl ethyl ether, alkali metal salts of vinyl sulfonic acid, vinyl sulfonic acid Ammonium salt, styrene sulfonic acid, styrene sulfonate, allyl sulfonic acid, allyl sulfonate, methallyl sulfonic acid, methallyl sulfonate, vinyl acetate, vinyl stearate, N-vinyl imidazole, N-vinyl acetamide, N-vinylformamide, N-vinylcaprolactam, N-vinylcarbazole, acrylamide, methacrylamide, N-alkylacrylamide, N-methylolacrylamide, N, N-methylene Scan acrylamide, glycol diacrylate, glycol dimethacrylate, divinylbenzene, and glycol diallyl ether and the like, a combination of one or more of them are used.

  In the case of the copolymer, the content of the N-vinylpyrrolidone monomer is preferably 20% by weight or more, and more preferably 30% by weight or more. Thereby, the resin material containing the monomer of N-vinylpyrrolidone can reliably realize a composite composition having a negative thermal expansion coefficient.

  Although the weight average molecular weight of the resin material containing N-vinylpyrrolidone is not particularly limited, it is preferably about 20,000 to 5,000,000, and more preferably about 200,000 to 2,000,000.

  (Ii) A resin material containing an acrylate ester as a monomer is also a water-soluble (hydrophilic) resin and a resin material having a relatively high transparency. Specific examples of such a resin material include a homopolymer of an acrylate ester, or a copolymer of a monomer of an acrylate ester and another monomer.

  Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, palmityl acrylate, A stearyl acrylate etc. are mentioned, What combined these 1 type (s) or 2 or more types is used.

  In addition, the other monomer is not particularly limited as long as it is copolymerizable with an acrylate ester. For example, in addition to (meth) acrylic acid, ammonium (meth) acrylate, (meth) acrylic amide, Various (meth) acrylates such as (meth) acrylic acid metal, vinyl acetate and the like can be mentioned. Of these, ammonium (meth) acrylate is preferably used.

  In the case of the copolymer, the content of the acrylic ester monomer is preferably 80% by weight or more, and more preferably 90% by weight or more. Thereby, the resin material containing the acrylate monomer can reliably realize a composite composition having a negative thermal expansion coefficient.

  Although the weight average molecular weight of the resin material containing an acrylic ester is not particularly limited, it is preferably about 500 to 100,000, and more preferably about 1000 to 70,000.

  (Iii) A resin material containing polyethylene glycol is also a water-soluble (hydrophilic) resin, and is a resin material having relatively high transparency. As such a resin material, polyethylene glycol having a weight average molecular weight of more than 200 is particularly preferably used, those having a weight average molecular weight of 400 or more are more preferably used, and those having a weight average molecular weight of 1000 or more are more preferably used. . With such a weight average molecular weight of polyethylene glycol, a composite composition having a negative thermal expansion coefficient can be reliably realized.

  In place of polyethylene glycol, a copolymer of ethylene glycol and another monomer may be used.

  The other monomer is not particularly limited as long as it is copolymerizable with ethylene glycol, and examples thereof include lactic acid, propylene glycol, butanediol, hexanediol, oxalic acid, terephthalic acid, and the like. What combined 1 type or 2 types or more is used.

  In the case of a copolymer, the content of the ethylene glycol monomer is preferably 50% by weight or more, and more preferably 60% by weight or more.

  In addition, the composite composition of the present invention includes various coupling agents such as silane coupling agents and titanium coupling agents, various antioxidants, various particles such as metal oxide particles and silica particles. Etc. may be included.

  The coefficient of thermal expansion of the resin material used in the present invention is not particularly limited, but is preferably about 50 to 250 ppm / ° C. in the temperature range of the glass transition temperature Tg or more of the resin material, and is 100 to 200 ppm. More preferably, it is about / ° C.

  The glass transition temperature Tg of the resin material used in the present invention is not particularly limited, but is preferably about −30 to 300 ° C., more preferably about 0 to 200 ° C.

(Composition)
In the composite composition including the fibrous filler and the resin material as described above, the weight fraction of the blended amount of the fibrous filler is preferably 0.1 to 99.9%, preferably 0.1 to 75%. More preferably. In addition, a compounding quantity is not specifically limited, It adjusts according to the characteristic required when shape | molding a resin composition. For example, when it is desired to reflect the characteristics of the fibrous filler, the blending amount of the fibrous filler is increased, and when it is desired to reflect the characteristics of the resin material, the blending amount of the resin is increased. Moreover, the absolute value of a negative thermal expansion coefficient can be adjusted by changing suitably content of the fibrous filler in a composite composition.

  In the composite composition of the present invention, a thermoplastic or thermosetting oligomer or polymer can be used in combination as required. In addition, the composition of the present invention may contain a small amount of a filler such as an ultraviolet absorber, a dye / pigment, other inorganic fillers and the like as long as the characteristics are not impaired.

  Such a composite composition of the present invention can be obtained by mixing each component by any method. For example, the resin material and the fibrous filler may be mixed as they are, or may be mixed while being heated as necessary. Moreover, the composition excellent in the dispersibility of a fibrous filler can be obtained by preparing the uniform dispersion liquid of a fibrous filler using a dispersion medium, and using the method of performing a dedispersion medium later. As the dispersion medium to be used, for example, the dispersibility of the fibrous filler can be maintained, and the resin material and / or a solvent capable of dissolving the coupling agent described later can be mixed uniformly. Examples of such a solvent include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, dioxane, acetone, methyl ethyl ketone, methyl cellosolve, tetrahydrofuran, pentaerythritol, dimethyl sulfoxide, dimethylformamide, and the like. Two or more types can be mixed and used. It is also possible to gradually change the polarizability of the original dispersion medium to the polarity of the target dispersion medium and disperse the fibrous filler in a dispersion medium having a different polarity.

  Moreover, the composite composition of the present invention is formed into a composite by being molded into a predetermined shape. This composite is characterized by high mechanical strength, low thermal expansion coefficient and humidity expansion coefficient, as well as high transparency. For this reason, the composite is expected to be applied not only to applications utilizing mechanical properties but also to the optical field.

  Moreover, the composite composition of the present invention has a negative thermal expansion coefficient as described above. Specifically, the thermal expansion coefficient of the composite composition of the present invention is preferably expected to be about −50 to 0 ppm / ° C., more preferably about −30 to −1 ppm / ° C. Is done. Such a composite composition can be mixed with other compositions, for example, to produce a composite having a coefficient of thermal expansion close to zero. Thereby, for example, when bonded to another member, a composite that can reliably prevent problems such as peeling of the bonding interface can be obtained. Furthermore, according to the composite composition of the present invention, there is almost no dimensional change due to heat, and highly reliable optical parts, structural parts, precision machine parts, and the like can be realized.

  Examples of other compositions used for mixing with the composite composition of the present invention include various water-soluble resins, various plastic resins, and various curable resins. The mixing ratio of the two is not particularly limited, and can be arbitrarily mixed so that the linear expansion coefficient of the mixture is −5 to 5 ppm, preferably −3 to 3 ppm.

  The water-soluble resin is not particularly limited as long as it is soluble in water, but is preferably a synthetic polymer such as polyvinyl alcohol, polyethylene oxide and polyacrylamide, polysaccharides such as starches and alginic acids, and the constitution of wood. Examples thereof include natural polymers such as proteins such as hemicellulose, gelatin, glue, casein and the like.

  In addition, the plastic resin is not particularly limited. For example, vinyl chloride resin, vinyl acetate resin, polystyrene, ABS resin, acrylic resin, polyethylene, polyethylene terephthalate, polyethylene naphthalate, polypropylene, fluororesin, polyamide resin, Thermoplastic polyimide resin, polyacetal resin, polycarbonate, polylactic acid, polyglycolic acid, poly-3-hydroxybutyrate, polyhydroxyvalylate, polyethylene adipate, polycaprolactone, polyester such as polypropyllactone, polyether such as polyethylene glycol, Examples thereof include polyamides such as polyglutamic acid and polylysine.

  On the other hand, as curable resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, acrylic resin, oxetane resin, diallyl phthalate resin, polyurethane resin, silicon resin, maleimide resin, thermosetting polyimide resin, etc. Is mentioned.

  Among these, examples of the acrylic resin include resins containing at least one cyclic acrylate or methacrylate, hydroxyethyl acrylate, or the like in addition to alkyl acrylate or alkyl methacrylate such as acrylic acid, methacrylic acid, methyl acrylate, and methyl methacrylate.

  A phenol resin is an organic compound having one or more phenolic hydroxyl groups in the molecule. Examples include novolak and bisphenols, resins having naphthol and naphthol in the molecule, paraxylylene-modified phenol resins, dimethylene ether type resols, methylol type phenols and the like. Further, compounds obtained by further methylolating these resins, lignins or lignin derivatives containing one or more phenolic hydroxyl groups, lignin degradation products, lignin or lignin derivatives, lignin degradation products modified, or these from petroleum resources Resins including those mixed with the manufactured phenolic resin may be mentioned.

  The epoxy resin is an organic compound having at least one epoxy group. For example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated products of these bisphenol type epoxy resins, epoxy resins having a dicyclopentadiene skeleton, triglycidyl isocyanate Epoxy resin having nurate skeleton, epoxy resin having cardo skeleton, epoxy resin having polysiloxane structure, alicyclic polyfunctional epoxy resin, alicyclic epoxy resin having hydrogenated biphenyl skeleton, fat having hydrogenated bisphenol A skeleton Examples thereof include cyclic epoxy resins.

  In addition, when a curable resin is used as the resin material, the curing method of the curable resin is not particularly limited, but in the composition, a crosslinking agent such as an acid anhydride or an aliphatic amine, or a cationic curing catalyst or an anionic system. It is preferable to add a curing accelerator such as a curing catalyst.

  Among these, as the cationic curing catalyst, for example, a substance that releases a substance that initiates cationic polymerization by heating (for example, an onium salt cationic curing catalyst or an aluminum chelate cationic curing catalyst) or an active energy ray is used to initiate cationic polymerization. For releasing a substance to be released (for example, an onium salt-based cationic curing catalyst). Specifically, as an aromatic sulfonium salt, hexafluoroantimonate salts such as SI-60L, SI-80L, SI-100L made by Sanshin Chemical Industry, SP-66, SP-77 made by Asahi Denka Kogyo, etc. Examples of the aluminum chelate include ethyl acetoacetate aluminum diisopropylate and aluminum tris (ethyl acetoacetate). Examples of the boron trifluoride amine complex include boron trifluoride monoethylamine complex and boron trifluoride. Examples include imidazole complexes and boron trifluoride piperidine complexes.

  On the other hand, examples of the anionic curing accelerator include tertiary amines such as 1,8-diaza-bicyclo (5,4,0) undecene-7, triethylenediamine, 2-ethyl-4-methylimidazole and 1-benzyl. Examples include imidazoles such as 2-phenylimidazole, phosphorus compounds such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate, quaternary ammonium salts, organometallic salts, and derivatives thereof, and among these, transparency is excellent. Accordingly, phosphorus compounds and imidazoles such as 1-benzyl-2-phenylimidazole are preferable. These curing accelerators may be used alone or in combination of two or more.

  In addition, the water-soluble resin, the plastic resin, and the curable resin described above can be used individually or in combination of two or more.

<Composite>
The composite composition of the present invention is formed into a composite having a predetermined shape by being molded.

  For example, by forming the composite composition of the present invention into a plate shape, it can be used for solar cell substrates, organic EL substrates, electronic paper substrates, liquid crystal display plastic substrates, color filter substrates, touch panel substrates, etc. Various usable transparent substrates (composites) can be obtained.

  In this case, the thickness of the composite of the present invention is preferably about 10 to 2000 μm, and more preferably about 20 to 200 μm. As a result, the composite of the present invention has both necessary and sufficient mechanical strength and light transmittance as the transparent substrate as described above. Moreover, if the thickness of a composite is in the said range, it is excellent in flatness and can achieve weight reduction of a transparent substrate compared with the conventional glass substrate.

  When the thickness of the composite of the present invention is within the above range, the total light transmittance is preferably 70% or more, more preferably 80% or more, and 88% or more. Further preferred.

  In addition, the composite of the present invention can be used for, for example, an optical element such as an optical lens and an optical sheet, an optical waveguide, an LED sealing material, and the like.

  Moreover, the humidity expansion coefficient of the composite of the present invention is preferably 100 ppm / humidity% or less, more preferably 50 ppm / humidity% or less, and further preferably 30 ppm / humidity% or less. By setting the humidity expansion coefficient within the above range, the dimensional change of the composite of the present invention is sufficiently suppressed even if the composite absorbs moisture during the production process or use. As a result, it is possible to reliably prevent problems such as warpage of the composite accompanying change in dimensions and disconnection of the aluminum wiring formed on the composite.

  Moreover, when applying the composite_body | complex of this invention to an optical element, you may provide the coat layer of resin on both surfaces for smoothness improvement. The resin to be coated preferably has excellent transparency, heat resistance and chemical resistance, and specific examples include polyfunctional acrylates and epoxy resins. The thickness of the coat layer is preferably from 0.1 to 50 μm, more preferably from 0.5 to 30 μm.

  Furthermore, you may provide the gas barrier layer and transparent electrode layer with respect to water vapor | steam or oxygen as needed on the surface of the composite_body | complex of this invention.

  In addition, in order to obtain a sheet-like composite using the composition of the present invention, a general sheet forming method may be used, and the forming method is not particularly limited. As a forming method, for example, a method of rolling the composite composition as it is to form a sheet, or after casting a dispersion medium of fibrous filler, removing the dispersion medium to obtain a sheet of fibrous filler, and then a resin material Or a method of casting a solution containing a resin material, a fibrous filler, and a dispersion medium, and then removing the dispersion medium to obtain a sheet.

  As one of preferred embodiments in such a process, a resin material and a fibrous filler are previously dispersed in a dispersion medium to prepare a dispersion, and then the obtained dispersion is filtered with a filter paper, a membrane filter, a paper mesh, or the like. And the other components such as a dispersion medium are filtered and / or dried to obtain a sheet. In addition, in the said filtration separation drying process, in order to improve work efficiency, you may carry out under pressure reduction and pressurization. Moreover, when forming continuously, the method of forming a thin layer sheet continuously using the paper machine used in the paper industry is also included.

  In the case of producing a sheet by casting, it is preferable that the sheet formed after filtration and / or drying is produced on a substrate from which the sheet is easily peeled off. Examples of such a substrate include those made of metal or resin. Examples of metal base materials include stainless steel base materials, brass base materials, zinc base materials, copper base materials, and iron base materials. Resin base materials include acrylic base materials, fluorine base materials, and polyethylene. Examples thereof include a terephthalate substrate, a vinyl chloride substrate, a polystyrene substrate, and a polyvinylidene chloride substrate.

  The embodiments of the composite composition and composite of the present invention have been described above. However, the present invention is not limited to this, and for example, an arbitrary component may be added to the composite. .

Next, specific examples of the present invention will be described.
[Fabric filler production]
(Production Example 1)
First, it is mainly composed of cellulose fibers having a fiber diameter of more than 1000 nm, dry pulp equivalent to 2 g in dry weight, and 0.025 g of TEMPO (2,2,6,6-tetramethyl-1-piperidine-N -Oxyl) and 0.25 g of sodium bromide were dispersed in 150 ml of water to prepare a dispersion.

  Next, a 13 wt% aqueous sodium hypochlorite solution was added to this dispersion so that the amount of sodium hypochlorite was 2.5 mmol per 1 g of pulp, and the reaction was started. During the reaction, a 0.5 M sodium hydroxide aqueous solution was dropped into the dispersion to keep the pH at 10.5. Thereafter, when no change in pH is observed, the reaction is considered to be complete, neutralized to pH 7 with a 0.5 M aqueous hydrochloric acid solution, the reaction product is filtered through a glass filter, and the filtrate is washed with a sufficient amount of water. And filtration was repeated 6 times. As a result, a reactant fiber having a solid concentration of 2% by weight was obtained.

  Next, water was added to the reaction product fiber to make 0.2% by weight. This reactant fiber dispersion was treated 15 times at a pressure of 20 MPa using a high-pressure homogenizer (manufactured by APV GAULIN LABORATORY, 15MR-8TA type) to obtain a transparent cellulose nanofiber dispersion (fibrous filler dispersion).

  Next, the dispersion was cast on a carbon film-coated grid that had been subjected to a hydrophilic treatment, then negatively stained with 2% uranyl acetate, and observed with a TEM. As a result of observation, the maximum fiber diameter was 10 nm and the number average fiber diameter was 6 nm.

  Further, the aggregate of transparent film-like cellulose fibers obtained by drying was subjected to wide-angle X-ray diffraction analysis to obtain a diffraction image. A wide-angle X-ray diffraction image showed that this membranous cellulose was composed of cellulose fibers having a cellulose I-type crystal structure.

  Moreover, the total reflection type infrared spectroscopic analysis was performed about the same membranous cellulose, and the ATR spectrum was obtained. From the ATR spectrum pattern, the presence of carbonyl groups was confirmed, and the amounts of aldehyde groups and carboxyl groups in the cellulose fibers evaluated by the method described above were 0.31 mmol / g and 1.7 mmol / g. .

(Production Example 2)
A cellulose nanofiber dispersion (fibrous filler dispersion) was obtained in the same manner as in Production Example 1 except that an ultrasonic homogenizer (manufactured by BRANSON, Digital Sonifier S-450) was used instead of the high-pressure homogenizer. The output (power) of the ultrasonic homogenizer was 40%, and the treatment time was 30 seconds.

[Production of complex]
Example 1
The cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% by weight obtained in Production Example 1 and an acrylic ester copolymer (Vaicry 6286, manufactured by Cytec Co., Ltd., glass transition temperature 30 ° C.) are mixed at room temperature. Stir for 30 minutes. The obtained mixed solution was poured into a petri dish that had been subjected to mold release treatment, water was evaporated in an oven at a temperature of 50 ° C, and further dried in a vacuum oven at 120 ° C. A transparent film (composite) was obtained.

  By the way, when a mixed solution of the cellulose nanofiber-dispersed aqueous solution and the copolymer was observed with a polarizing microscope, it was found that the cellulose nanofibers were uniformly dispersed. Moreover, when the average fiber diameter of each fibrous filler was measured, it was recognized that it was 100 micrometers or less.

(Example 2)
Example 1 except that a copolymer of ammonium acrylate and an acrylate ester (manufactured by Toagosei Co., Ltd., Jurimer AT510, glass transition temperature 27.5 ° C.) was used instead of the copolymer. In the same manner, a transparent film (composite) was obtained.

(Example 3)
Example 1 except that a copolymer of ammonium acrylate and an acrylate ester (manufactured by Toagosei Co., Ltd., Jurimer ET325, glass transition temperature 28.0 ° C.) was used instead of the copolymer. In the same manner, a transparent film (composite) was obtained.

Example 4
Example 1 except that a copolymer of ammonium acrylate and an acrylate ester (manufactured by Toagosei Co., Ltd., Jurimer AT613, glass transition temperature 76.0 ° C.) was used instead of the copolymer. In the same manner, a transparent film (composite) was obtained.

(Example 5)
A transparent film (composite) was obtained in the same manner as in Example 1 except that polyvinylpyrrolidone (manufactured by Wako Pure Chemical Industries, polyvinylpyrrolidone, glass transition temperature 160 ° C.) was used instead of the copolymer. Obtained.

(Example 6)
In the same manner as in Example 1 except that polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., polyethylene glycol 20,000, weight average molecular weight 20000, melting point 56 to 63 ° C.) was used instead of the copolymer. A transparent film (composite) was obtained.

(Example 7)
A transparent film in the same manner as in Example 1 except that polyethylene glycol (manufactured by Aldrich, Poly (ethylene glycol), weight average molecular weight 8000, melting point 60 to 63 ° C.) was used instead of the copolymer. (Complex) was obtained.

(Example 8)
A transparent film in the same manner as in Example 1 except that polyethylene glycol (manufactured by Aldrich, Poly (ethylene glycol), weight average molecular weight 1540, melting point 43 to 46 ° C.) was used instead of the copolymer. (Complex) was obtained.

Example 9
A transparent film in the same manner as in Example 1 except that polyethylene glycol (manufactured by Aldrich, Poly (ethylene glycol), weight average molecular weight 400, melting point 4 to 8 ° C.) was used instead of the copolymer. (Complex) was obtained.

(Example 10)
A transparent film (composite) was obtained in the same manner as in Example 1 except that the aqueous solution of cellulose nanofibers having a solid content concentration of 0.2% by weight obtained in Production Example 2 was used.

(Comparative Example 1)
A transparent film (composite) was obtained in the same manner as in Example 1 except that polyethylene glycol (manufactured by Wako Pure Chemical Industries, polyethylene glycol 200, weight average molecular weight 200) was used instead of the copolymer. Obtained.

(Comparative Example 2)
A transparent film (composite) was obtained in the same manner as in Example 1 except that polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., polyacrylic acid 25,000) was used instead of the copolymer. It was.

(Comparative Example 3)
A transparent film (composite) in the same manner as in Example 1 except that ammonium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd., ammonium polyacrylate solution 70 to 110) was used instead of the copolymer. )

(Comparative Example 4)
Example except that sodium polyacrylate (prepared to PH12.4 by adding sodium hydroxide aqueous solution to the polyacrylic acid aqueous solution used in Comparative Example 2) was used instead of the copolymer. In the same manner as in Example 1, a transparent film (composite) was obtained.

(Comparative Example 5)
A transparent film (composite) was obtained in the same manner as in Example 1 except that polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd., polyvinyl alcohol) was used instead of the copolymer.

(Comparative Example 6)
A transparent film (composite) was obtained in the same manner as in Example 1 except that polyethyleneimine (manufactured by MP Biomedical, POLYETHYLEENEIMINE 50% SOLUTION) was used instead of the copolymer.

(Comparative Example 7)
A transparent film (composite) was obtained in the same manner as in Example 1 except that hydroxyethylcellulose (Wako Pure Chemical Industries, Ltd., hydroxyethylcellulose) was used instead of the copolymer.

(Comparative Example 8)
A transparent film (composite) was obtained in the same manner as in Example 1 except that carboxymethyl cellulose ammonium (Wako Pure Chemical Industries, Ltd., carboxymethyl cellulose ammonium) was used instead of the copolymer.

(Comparative Example 9)
A transparent film (composite) was obtained in the same manner as in Example 1 except that sodium carboxymethylcellulose (Wako Pure Chemical Industries, Ltd., carboxymethylcellulose sodium) was used instead of the copolymer.

(Comparative Example 10)
A transparent film was obtained in the same manner as in Example 1 except that the addition of the fibrous filler was omitted and the following was performed.

  An acrylic ester copolymer (Cytech, Viacryl 6286, glass transition temperature 30 ° C.) is poured into a petri dish, moisture is evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. A transparent film was obtained.

(Comparative Example 11)
A transparent film was obtained in the same manner as in Example 1 except that the addition of the resin material was omitted and the procedure was as follows.

  The cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% by weight obtained in Preparation Example 1 is poured into a petri dish, water is evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C., and the thickness is 30 μm. A transparent film was obtained.

(Comparative Example 12)
A transparent film was obtained in the same manner as in Comparative Example 11 except that the cellulose nanofiber-dispersed aqueous solution having a solid content concentration of 0.2% by weight obtained in Production Example 2 was used.

[Evaluation of complex]
About the film obtained by each Example and each comparative example, the thermal expansion coefficient was measured in the following procedures, respectively.

<Measurement procedure of thermal linear expansion coefficient>
Using a TMA / SS120C type thermal stress strain measuring device manufactured by Seiko Denshi Co., Ltd., after changing the temperature within a predetermined temperature range (see Table 1) at a rate of 5 ° C. per minute in a nitrogen atmosphere, once 0 The temperature was lowered to 5 ° C., the temperature was increased again at a rate of 5 ° C. per minute, and the values in the temperature range shown in Table 1 were measured and determined. Then, the load was set to 5 g, and the measurement was performed in the tension mode.

  The results of the above measurements are shown in Tables 1 and 2.

  As is clear from Table 1, in the films obtained in each example, the average fiber diameter of the fibrous filler is 100 μm or less, and the content of hydrogen atoms capable of forming hydrogen bonds in the resin material Is less than 0.01 mol / g, however, these films were found to exhibit a negative value for the coefficient of thermal expansion.

  Although not shown in Table 1, the composite composition obtained in each example and another composition were mixed at a predetermined ratio to form a film (composite). A film having an expansion coefficient of almost zero was obtained. Moreover, when the mixing ratio of the composite composition of the present invention and the other composition was changed, the coefficient of thermal expansion of the resulting film could be changed.

  Furthermore, although not shown in Table 1, the coefficient of thermal expansion of the film could be changed from the results of Example 10 by changing the output of the ultrasonic homogenizer or the processing time. Specifically, by increasing the output of the ultrasonic homogenizer or increasing the treatment time, it was observed that the average fiber diameter of the cellulose nanofibers decreased and the absolute value of the negative thermal expansion coefficient increased.

  On the other hand, as apparent from Table 2, in the films obtained in Comparative Examples 1 to 9, the average fiber diameter of the fibrous filler was more than 100 μm. Moreover, in these films, it was recognized that a thermal linear expansion coefficient shows a positive value.

  Moreover, although the film obtained in Comparative Examples 10-12 was not a composite of a fibrous filler and a resin material, the thermal linear expansion coefficient also showed a positive value.

Claims (12)

A composite composition comprising a fibrous filler and a resin material,
The fibrous filler is composed of a polysaccharide material,
The resin material is capable of dispersing the fibrous filler so that the average fiber diameter is 100 μm or less, and the content of hydrogen atoms capable of forming hydrogen bonds is less than 0.01 mol / g. A composite composition characterized by the above.   The composite composition according to claim 1, wherein the polysaccharide material is cellulose or chitin.   The composite composition according to claim 2, wherein the fibrous filler composed of cellulose is a cellulose fiber obtained by refining a cellulose raw material by at least one of chemical treatment and mechanical treatment.   4. The composite composition according to claim 2, wherein the fibrous filler composed of cellulose is obtained by substituting at least one of an aldehyde group and a carboxyl group for a part of the hydroxyl group in the cellulose molecule contained therein. 5. object.   5. The composite composition according to claim 1, wherein the hydrogen atom capable of forming a hydrogen bond is a hydrogen atom covalently bonded to any one of a nitrogen atom, an oxygen atom, and a fluorine atom.   The composite composition according to any one of claims 1 to 5, wherein the resin material is a water-soluble polymer.   The composite composition according to claim 1, wherein the resin material contains N-vinylpyrrolidone as a monomer.   The composite composition according to claim 1, wherein the resin material contains an acrylate ester as a monomer.   The composite composition according to claim 8, wherein the resin material is a copolymer of an acrylate and an acrylate.   The composite composition according to any one of claims 1 to 9, wherein the resin material contains polyethylene glycol having a molecular weight of more than 200.   The composite composition according to any one of claims 1 to 10, wherein a content of the fibrous filler is 0.1 to 99.9 wt%.   A composite formed by molding the composite composition according to claim 1.