JP5515617B2 - Composite composition and composite - Google Patents

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 coefficient of thermal expansion. For this reason, it is expected that the characteristics will be applied to various fields such as the optical field, the structural material field, and the building material field, particularly as an alternative to the glass material.

  However, a composite containing fine cellulose fibers has a problem of discoloration when heated at a high temperature. When such discoloration occurs, the transparency of the composite is lowered, which hinders application in the optical field in particular. This phenomenon of discoloration has become a major issue in the full-scale practical application of composites because it is inevitable that members are exposed to a high temperature environment in the manufacturing process or use process of products.

JP 2003-201695 A

  An object of the present invention is to provide a composite composition having various characteristics such as a low thermal expansion coefficient, high strength, and a low humidity expansion coefficient and capable of suppressing discoloration at high temperatures, and a composite formed by molding such a composite composition. Is to provide.

Such an object is achieved by the present inventions (1) to (15) below.
(1) A composite composition composed of a fibrous filler and a dispersion medium ,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting treatment is a treatment for introducing at least one of a coupling agent having an acrylic group or a methacrylic group and a hydrolyzate of the coupling agent into the cellulose fiber, and JIS K for the fibrous filler. The weight loss rate at 180 ° C. measured according to the thermogravimetry method specified in 7120 is A, and the cellulose fiber subjected to oxidation treatment is measured according to the same method as the thermogravimetry method. A composite composition characterized in that, when the weight loss rate at 180 ° C. is B, the treatment satisfies the relationship of A <B.

(2) A composite composition composed of a fibrous filler and an acrylic resin-containing resin material,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting treatment is a treatment for introducing at least one of a coupling agent having an acrylic group or a methacrylic group and a hydrolyzate of the coupling agent into the cellulose fiber, and JIS K for the fibrous filler. The weight loss rate at 180 ° C. measured according to the thermogravimetry method specified in 7120 is A, and the cellulose fiber subjected to oxidation treatment is measured according to the same method as the thermogravimetry method. A composite composition characterized in that, when the weight loss rate at 180 ° C. is B, the treatment satisfies the relationship of A <B .
(3) The composite composition according to (1) or (2), wherein the coupling agent is alkoxysilane or alkoxytitanium.

(4) A composite composition composed of a fibrous filler and a dispersion medium ,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting process is a process of introducing at least one of alkoxy titanium and a hydrolyzate of alkoxy titanium into the cellulose fiber, and the thermogravimetric measurement method defined in JIS K 7120 is used for the fibrous filler. The weight loss rate at 180 ° C. measured in accordance with A is defined as A, and the weight loss rate at 180 ° C. measured in accordance with the same method as the thermogravimetric method for cellulose fibers subjected to oxidation treatment is defined as B. A composite composition characterized by being a treatment satisfying a relationship of A <B.
(5) A composite composition composed of a fibrous filler and an acrylic resin-containing resin material,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting process is a process of introducing at least one of alkoxy titanium and a hydrolyzate of alkoxy titanium into the cellulose fiber, and the thermogravimetric measurement method defined in JIS K 7120 is used for the fibrous filler. The weight loss rate at 180 ° C. measured in accordance with A is defined as A, and the weight loss rate at 180 ° C. measured in accordance with the same method as the thermogravimetric method for cellulose fibers subjected to oxidation treatment is defined as B. A composite composition characterized by being a treatment satisfying a relationship of A <B.

(6) The composite composition according to any one of (1) to (5), wherein the weight reduction rate A and the weight reduction rate B satisfy a relationship of A / B ≦ 0.9.
(7) The composite composition according to any one of (1) to (6) , wherein an average fiber diameter of the cellulose fibers is 4 to 1000 nm.

(8) The composite composition according to any one of (1) to (7), wherein the cellulose fiber is obtained by refining a cellulose raw material by at least one of chemical treatment and mechanical treatment.

(9) The above-described (1) to (8), wherein the cellulose fiber subjected to the oxidation treatment is obtained by substituting at least one of an aldehyde group and a carboxyl group in a hydroxyl group in the cellulose molecule contained. The composite composition according to any one of the above.

(10) The cellulose fiber subjected to the oxidation treatment uses natural cellulose as a raw material, uses an N-oxyl compound as an oxidation catalyst, and oxidizes the raw material by allowing a co-oxidant to act on the raw material in water. The composite composition according to any one of (1) to (9) , which is obtained by applying

(11) The composite composition according to (2) or (5) , wherein the fibrous filler content is 0.1 to 99.9% by weight.

(12) A composite formed by molding the composite composition according to (2) or (5 ) above,
A composite having a thickness of 10 to 2000 μm.

(13) The composite according to (12) , wherein the total light transmittance is 50% or more after the heat treatment at 180 ° C. for 2 hours.

(14) The composite according to (12) or (13) , wherein the thermal expansion coefficient at 30 ° C. to 150 ° C. is −30 to 50 ppm / ° C.

(15) The composite according to any one of (12) to (14) , wherein the coefficient of humidity expansion is 100 ppm / humidity% or less.

  According to the present invention, by suppressing thermal decomposition and weight reduction of the fibrous filler at high temperature, discoloration is suppressed, and a composite having excellent characteristics of low thermal expansion coefficient, high strength, and low humidity expansion coefficient is manufactured. A possible composite composition is obtained.

  In addition, according to the present invention, a composite having various characteristics such as low thermal expansion coefficient, high strength, and low humidity expansion coefficient is obtained by molding the composite composition into a predetermined shape and having excellent discoloration resistance. can get.

It is a graph which shows the example of the thermogravimetric (TG) curve measured about a fibrous filler.

  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 contains a fibrous filler and can be produced by molding into a predetermined shape.

  A fibrous filler is comprised with the fiber in which the oxidation process and the thermal decomposition suppression process were performed.

  In this thermal decomposition suppression treatment, the weight reduction rate at 180 ° C. measured in accordance with the thermogravimetry method defined in JIS K 7120 for the fibrous filler is defined as the weight reduction rate A, and the fiber subjected to oxidation treatment is treated. When the weight reduction rate at 180 ° C. measured in accordance with the same method as the thermogravimetry method is defined as the weight reduction rate B, this is a process that satisfies the relationship A <B.

  A composite composition containing a fibrous filler that has been subjected to such treatment is molded into a composite, and the fibrous fillers are entangled with each other, and in some cases, dispersed in a resin material. Increase the mechanical properties of For this reason, the obtained composite composition has high mechanical strength and low thermal expansion coefficient and humidity expansion coefficient. In addition, by using the composite composition of the present invention, since thermal decomposition and weight loss at high temperature are suppressed, the heat resistance of the fibrous filler is improved, and a composite excellent in discoloration resistance at high temperature is obtained. can get.

  Although the composite composition of the present invention can be composed of only the fibrous filler, here, the composite composition containing the fibrous filler and the resin material will be described in detail.

(Fibrous filler)
The fibrous filler contained in the composite composition of the present invention may be any fiber, but is preferably composed of cellulose fibers.

  Examples of the cellulose fiber include natural cellulose fiber and regenerated cellulose fiber. On the other hand, examples of fibers other than cellulose fibers include chitin fibers and chitosan 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.

  The cellulose fiber used in the present invention is preferably highly crystalline. Such a cellulose fiber has a particularly small linear expansion coefficient and a high mechanical strength, and therefore 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.

  The average fiber diameter of the cellulose fibers contained in the fibrous filler is preferably 4 to 1000 nm, more preferably 4 to 300 nm, and even more preferably 4 to 200 nm. When the average fiber diameter of the cellulose fibers is within the above range, the fibrous filler is prevented from becoming 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.

  On the other hand, the average length of the cellulose fiber is not particularly limited, but is preferably 100 nm or more, and more preferably 200 nm or more. As a result, the reinforcing effect of the fibrous filler becomes more remarkable, and in the composite, further improvement in mechanical strength and further reduction in the thermal expansion coefficient and the humidity expansion coefficient are achieved.

  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.

Here, the measurement of an average fiber diameter can be performed as follows.
First, a dispersion of cellulose fibers having a solid content of 0.05 to 0.1% by weight is prepared. The dispersion is cast on a carbon film-coated grid, and a transmission electron microscope (TEM) observation sample is used. To do. Moreover, when the cellulose 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 microscopic image is acquired at a magnification of 5000 times, 10000 times, or 50000 times depending on the fiber diameter of the cellulose fiber to be constituted. At this time, when assuming an axis of arbitrary vertical and horizontal image widths in the obtained image, the sample conditions and observation conditions (magnification, etc.) are set so that at least 20 cellulose fibers intersect 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 cellulose fibers. Based on the fiber diameter data thus obtained, the average fiber diameter is calculated.

  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 ultrahigh-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. In addition, if the cellulose raw material that has been stored in a dry dry state after isolation and purification is used, the microfibril bundles are likely to swell. The average fiber diameter can be reduced, which is preferable. As an example, the cellulose dispersion medium in the oxidation reaction in this step is water, and the cellulose concentration in the aqueous reaction solution is arbitrary as long as the reagent can be sufficiently diffused. On the other hand, it is about 5% or less.

  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. Salts such as sodium hypochlorite and sodium hypobromite are preferred. Furthermore, when using sodium hypochlorite, it is preferable in reaction rate to advance reaction in presence of alkali metal bromide, for example, 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.

  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, when wood pulp and cotton-based 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 extracted cellulose from sea squirts, the required amount of carboxyl groups is 0.1 to 0.8 mmol / g. Thus, since the necessary oxidation conditions differ depending on the type of cellulose raw material, it is possible to obtain the optimum amount of carboxyl groups for each cellulose raw material by controlling the addition amount of the co-oxidant and the reaction time based on it. it can. As an example, the addition amount of the co-oxidant is preferably set in the range of about 0.5 to 8 mmol with respect to 1 g of the cellulose raw material, and the reaction time is about 5 to 120 minutes, and at most 240 minutes or less. Is preferred.

  In addition, although the carboxyl group is introduced into the cellulose molecule through the oxidation treatment in this oxidation reaction step, an aldehyde group may be introduced partially depending on the progress of the oxidation treatment. Therefore, the hydroxyl group of the cellulose molecule after the oxidation treatment is substituted with at least one of an aldehyde group and a carboxyl group. The composite composition containing such cellulose fibers, which will be described in detail later, is used to determine an index for optimizing various conditions of the composite composition in order to increase the discoloration resistance of the composite at high temperatures. Used for.

[2] Purification step In the purification step, reactant fibers and compounds other than water contained in the reaction slurry such as unreacted hypochlorous acid and various by-products are removed out of the system. At this stage, the reaction product fibers are usually not dispersed evenly to the nanofiber unit. Therefore, a high purity (99% by weight or more) is achieved by repeating normal purification methods, that is, water washing and filtration.

  As the purification method in this purification step, any apparatus can be used as long as it is an apparatus (for example, a continuous decander) that can achieve the above-described purpose, such as a method using centrifugal dehydration. The aqueous dispersion of the reactant fibers thus obtained is in the range of approximately 10 to 50% by weight as the solid content (cellulose) concentration in the squeezed state. In consideration of the dispersion in the nanofibers in the subsequent steps, a solid content concentration higher than 50% by weight is not preferable 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 or the like may be used. Moreover, these mixtures can also be used conveniently.

  Moreover, when diluting and dispersing the dispersion of the above-mentioned reactant fibers with a solvent, the dispersion is gradually added by adding a solvent, and if a stepwise dispersion is attempted, the dispersion of fibers at the nanofiber level is efficiently performed. You may be able to get Due to operational problems, the dispersion conditions may be selected so that the state after the dispersion step is a viscous dispersion 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 a device with strong beating ability under high speed rotation such as homomixer, high pressure homogenizer, ultra high pressure 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 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 dispersion of highly refined fine cellulose fibers can be provided.

  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 fine cellulose fibers are mixed again in the dispersion medium (water, organic solvent or a mixture thereof) and have an appropriate dispersion force (for example, various types used in the dispersion process in the production of the fine cellulose fiber dispersion described above). A dispersion of fine cellulose fibers can be obtained by adding dispersion using a disperser.

  The fine cellulose fiber used in the present invention preferably 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 fine cellulose fiber having the I-type crystal structure is a fiber obtained by subjecting a naturally-derived cellulose solid raw material to surface oxidation and refinement.

Note that the fine cellulose fiber has an I-type crystal structure in two positions of 2 theta = 14 to 17 ° and 2 theta = 22 to 23 ° in the diffraction profile obtained by wide-angle X-ray diffraction image measurement. Can be identified from 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 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), there is absorption at 1730 cm ⁻¹ in the above measurement.

  Fine cellulose fibers can be stably present as finer fiber diameters when the total amount of carboxyl groups and aldehyde groups present in cellulose is larger for the reasons described above. 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, Cellulose fibers excellent in stability as nanofibers are preferably obtained when the amount is 0.2 to 0.8 mmol / g. In addition, when the total amount is smaller than 0.1 mmol / g, the difference in physical properties from the conventionally known refined cellulose fibers (for example, the dispersion stabilization effect in the dispersion) is also reduced. Since it becomes difficult to obtain as a fiber of a fine 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 0.1M hydrochloric acid aqueous solution, and then 0.05M hydroxylated. An aqueous sodium solution is dropped to measure the electrical conductivity. 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)
As the resin material used in the present invention, known materials can be used, and those containing various curable resins, various plastic resins, various water-soluble resins and the like can be mentioned, although not particularly limited.

  The water-soluble resin is not particularly limited as long as it is soluble in water, and examples thereof include thermoplastic resins, curable resins, natural polymers, and the like, preferably polyvinyl alcohol, polyethylene oxide, polyacrylamide, and polyvinylpyrrolidone. Such synthetic polymers, polysaccharides such as starches and alginic acids, natural polymers such as proteins such as hemicellulose, gelatin, glue, and casein, which are constituents of wood.

  The thermoplastic resin is not particularly limited. For example, vinyl chloride resin, vinyl acetate resin, polypolystyrene, 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, polyhydroxyvalerate, polyethylene adipate, polycaprolactone, polypropyllactone, and other polyesters, polyethylene glycol, etc. Polyamides such as ether, polyglutamic acid, and polylysine are listed.

  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.

  In addition, the phenol resin includes an organic compound having one or more phenolic hydroxyl groups in the molecule, for example, a novolak or bisphenol, a resin having naphthol or naphthol in the molecule, a paraxylylene-modified phenol resin, or a dimethylene ether type. Resole resins such as resole and methylol type phenol are listed. 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.

  Epoxy resin refers to 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 isocyanurate Epoxy resin having skeleton, epoxy resin having cardo skeleton, epoxy resin having polysiloxane structure, alicyclic polyfunctional epoxy resin, alicyclic epoxy resin having hydrogenated biphenyl skeleton, alicyclic having hydrogenated bisphenol A skeleton An epoxy resin etc. are mentioned.

  In addition, when a curable resin is used as the resin material, the method for curing the composite composition of the present invention is not particularly limited, but in the composition, a crosslinking agent such as an acid anhydride or an aliphatic amine, or a cationic system is used. It is preferable to add a curing accelerator such as a curing catalyst or an anionic 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). Specific examples of aromatic sulfonium salts include hexafluoroantimonate salts such as SI-60L, SI-80L, SI-100L manufactured by Sanshin Chemical Industry, and SP-66 and SP-77 manufactured by Asahi Denka Kogyo. 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, boron trifluoride imidazole complex, and trifluoride. Examples thereof include boron bromide 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.

  The water-soluble resin, thermoplastic resin, and curable resin described above can be used individually or in combination of two or more.

(Composite 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, the amount of fibrous filler can be increased when reflecting the properties of the fibrous filler, and the amount of resin can be increased when reflecting the properties of the resin material.

  In the composite composition of the present invention, a thermoplastic or thermosetting oligomer or polymer can be used in combination as required. Moreover, the composite composition of the present invention may contain a small amount of a filler such as an ultraviolet absorber, a dye / pigment, other inorganic fillers, etc. as long as the properties 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 composite 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 solvents include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, dioxane, acetone, methyl ethyl ketone, methyl cellosolve, tetrahydrofuran, pentaerythritol, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone etc. are mentioned, These can also be used individually or in mixture of 2 or more types. 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.

  However, it has been a problem that such composites are discolored at high temperatures. This discoloration reduced the light transmittance of the composite and caused a significant decrease in performance as an optical component.

  In response to such a problem, the present inventor has intensively studied the conditions for increasing the discoloration resistance of the composite at high temperatures. And as a fibrous filler which a composite composition contains, the said subject can be solved by using the cellulose fiber which gave the thermal decomposition suppression process which can suppress the thermal decomposition of a cellulose component when compared with a cellulose simple substance. As a result, the present invention has been completed.

  Here, the thermal decomposition inhibiting treatment described above is a cellulose that has been subjected to an oxidation treatment, with the weight loss rate at 180 ° C. measured according to the thermogravimetric measurement method defined in JIS K 7120 for the fibrous filler as A. A treatment that satisfies the relationship of A <B, where B is the weight loss rate at 180 ° C. measured according to the same method as the thermogravimetric measurement method for the cellulose fiber as a measurement object. is there.

  A composite produced using a composite composition satisfying such conditions has particularly high discoloration resistance at high temperatures. For this reason, for example, even if the optical component becomes high temperature in the manufacturing process or use process of the product having the optical component, if the optical component to which the composite of the present invention is applied is used, significant discoloration can be prevented. . For this reason, the optical characteristic of the optical component is prevented from being lowered, and a highly reliable product can be obtained.

  In addition, the discovery of such optimum conditions facilitates the production of the composite composition. That is, conventionally, in producing a composite composition having high discoloration resistance, it is possible to optimize the production conditions from the background that various conditions of the fibrous filler act on the discoloration resistance in a complicated manner. It was impossible.

  On the other hand, the directionality which optimizes the various conditions of a fibrous filler can be established by discovering said optimal conditions in this invention. As a result, according to the present invention, a composite composition having high discoloration resistance at high temperatures can be easily and reliably produced by suppressing the weight loss of the fibrous filler by various treatments.

  The weight reduction rate A and the weight reduction rate B may satisfy A <B, but preferably satisfy the relationship of A / B ≦ 0.9. Thereby, the discoloration resistance at high temperature of the composite becomes more remarkable, and an optical component having excellent optical characteristics can be obtained even when applied to an optical component, for example.

In addition, the measuring method of weight reduction rate A and B is shown below.
First, when a sample is heated, a thermal balance capable of continuously measuring the mass is prepared, and a fibrous filler to be measured is placed on a test piece container of the thermal balance. Next, dry air is allowed to flow around the thermal balance. The flow rate of the dry air at this time is 100 to 300 ml per minute. In addition, as a sample, what shape | molded the fibrous filler in the film form is used.

  Next, the mass of the fibrous filler before heating is measured. Then, prior to heating, dry air flows in for 1 hour or more.

  Next, the temperature rise is started at 10 ° C. per minute and the heating is continued until 180 ° C. is reached. Thereafter, the mass of the fibrous filler that changes with heating is recorded as needed while adjusting the heating pattern so that 180 ° C. is maintained.

  When the weight loss rate measured in this way is the vertical axis and the temperature is the horizontal axis, the obtained curve becomes a thermogravimetric (TG) curve.

  The weight reduction rates after 150 minutes from the start of heating are designated as weight reduction rates A and B, respectively.

  Here, as the thermal decomposition inhibiting treatment that satisfies the above-described conditions for the fibrous filler, for example, a treatment for chemically modifying the fibrous filler described later, a coupling agent or a hydrolysis product of the coupling agent is used. Examples thereof include a treatment to be introduced and a method for introducing an antioxidant.

Among these, examples of the chemical modification include acetylation treatment. By subjecting the cellulose fiber to acetylation treatment, at least a part of the hydroxyl groups in the cellulose molecule is substituted with acetyl groups (—CH ₃ CO) (acetylation). As a result, the thermal decomposability of the fibrous filler at high temperatures is suppressed, and the fibrous filler satisfies the above relationship. Examples of the acetylation treatment include a treatment in which acetic anhydride is added to a dispersion containing cellulose fibers, and a treatment in which cellulose fibers are formed into a film shape are immersed in acetic anhydride. Further, if necessary, acetic anhydride, sulfuric acid, benzene, pyridine, sodium acetate and the like may be added to acetic anhydride.

  Further, it is considered that the thermal decomposability of the fibrous filler is suppressed by acetylating as many hydroxyl groups as possible in the cellulose molecule, but preferably 5% or more, more preferably 10% or more of the hydroxyl groups are acetylated. It is preferable that

  Examples of the method for acetylating cellulose fibers include a method in which acetyl chloride or acetic anhydride is allowed to act on cellulose fibers in the presence of a base. Examples of the base include pyridine and triethylamine.

  Here, an example of a thermogravimetric (TG) curve measured when the fibrous filler is subjected to acetylation is shown in FIG. In the graph shown in FIG. 1, a thermogravimetric curve a indicating the weight reduction rate A (corresponding to the present invention) and a thermogravimetric curve b indicating the weight reduction rate B (corresponding to the prior art) are drawn.

  As is apparent from FIG. 1, in the thermogravimetric curve a, a rapid weight decrease is recognized immediately after the start of heating, but the weight decrease accompanying the subsequent heating is relatively gradual. On the other hand, in the thermogravimetric curve b, a rapid weight loss of 10% or more occurs in about 50 minutes after the start of heating. After that, the weight decreases gradually, but the weight decrease rate in the same temperature region is larger than the thermogravimetric curve a. For this reason, a big difference arises with the thermogravimetric curve a. This difference is thought to ultimately affect the discoloration resistance of the composite.

  Moreover, as a coupling agent, although a well-known thing can be used, a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, an aluminum coupling agent etc. are mentioned, Among these, silane is included. A coupling agent or a titanium coupling agent is preferred. Since these are relatively easily available and have high adhesiveness at the interface between the inorganic material and the organic material, they are suitable as a coupling agent contained in the composite composition.

  Of the above coupling agents, the silane coupling agent preferably contains at least one silicon atom and at least one alkoxy group as a functional group. Other functional groups include an epoxy group, an epoxy cyclohexyl group, an amino group, a hydroxyl group, an acrylic group, a methacryl group, a vinyl group, a phenyl group, a styryl group, and an isocyanate group. In the present invention, since an effect equivalent to that of the coupling agent can be obtained, tetraalkoxysilane containing four alkoxy groups is also included in the silane coupling agent.

  Specific examples of the silane coupling agent include tetraalkoxysilane compounds, alkyltrialkoxysilanes, alkyl group-containing alkoxysilane compounds such as dimethyldialkoxysilane, 3-glycidoxypropyltrialkoxysilane, and 3-glycidpropyl. Epoxysilane compounds such as methyl dialkoxysilane and 2- (3,4-epoxycyclocyclohexyl) ethyltrialkoxysilane, aminoalkoxy such as 3-aminopropyltrialkoxysilane and N-phenyl-3-aminopropyltrialkoxysilane Silane compound, 3-acryloxypropyltrialkoxysilane, methacryloxypropyltrialkoxysilane, 3-methacryloxypropylmethyl dialkoxysilane, 3-methacryloxypropyltrialkoxy (Meth) acrylic alkoxysilane compounds such as silane, vinylalkoxysilane compounds such as vinyltrialkoxysilane, phenyltrialkoxysilane, diphenyldialkoxysilane, and phenyl group-containing trialkoxysilanes such as 4-hydroxyphenyltrialkoxysilane Examples thereof include compounds and styryl group-containing alkoxysilane compounds such as 3-isocyanatopropyltrialkoxysilane. Among these, a tetraalkoxysilane compound, an alkyl group-containing alkoxysilane compound, and a phenyl group-containing alkoxysilane compound are preferable because they are highly effective in increasing water resistance.

  On the other hand, specific examples of the titanium coupling agent include alkoxytitanium compounds having the same substituent as the alkoxysilane compound. For example, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl Titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl trixylphenyl titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, dicumylphenyloxyacetate titanate , Diisostearoyl ethylene Examples thereof include titanate, bis (dioctyl pyrophosphate) ethylene titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate, and the like. .

  Moreover, it may replace with a coupling agent and may use the hydrolyzate of a coupling agent as mentioned above. The coupling agent or its hydrolyzate may be selected as appropriate in consideration of the compatibility with the dispersion medium, the stability of the hydrolyzate, etc. The hydrolyzate is coupled with an acidic aqueous solution such as an acetic acid aqueous solution. It can be easily prepared by stirring and mixing with an agent. Further, the hydrolyzate of the coupling agent may be the same as the hydrolyzate of the coupling agent, even if the hydrolyzable group (alkoxide group) is not hydrolyzed.

  As the coupling agent, a coupling agent having an acrylic group or a methacryl group as a functional group is particularly preferable. By using such a coupling agent, the coupling agent effectively acts to suppress the thermal decomposability of the fibrous filler. This is because free radicals generated by the action of heat at high temperatures are generally responsible for discoloration of cellulose, resin materials, etc., but the acrylic and methacrylic groups capture these free radicals. This is because it is considered to suppress discoloration of the resin material. Thereby, the further improvement of the discoloration resistance of a composite_body | complex is achieved.

  On the other hand, examples of antioxidants include phenolic antioxidants such as hydroquinone monobenzyl ether, 1,1-bis (4-oxyphenyl) cyclohexane, styrenated phenol, and dilauryl thiodipropionic acid ester. Examples thereof include sulfur-based antioxidants and phosphorus-based antioxidants such as tris (nonylphenyl) phosphite. It is considered that such an antioxidant also captures free radicals generated by the action of heat and suppresses discoloration of cellulose and resin materials.

  In addition, the composite obtained from the composite composition as described above is not only highly resistant to discoloration, but is also mechanically entangled with fibrous fillers or reinforced with a resin material by fibrous fillers. The strength is high, and the thermal expansion coefficient and the humidity expansion coefficient are low.

(Complex)
The composite composition of the present invention is formed into a composite having a predetermined shape by being molded.

  The composite composition of the present invention is formed into a plate shape and used as various transparent substrates (composites) such as a solar cell substrate, an organic EL substrate, an electronic paper substrate, and a liquid crystal display plastic substrate.

  From such a viewpoint, the composite of the present invention preferably has a thickness of about 10 to 2000 μm, 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.

  In addition, according to the present invention, even when the composite has a high temperature thermal history, the discoloration is suppressed and the light transmittance is prevented from being lowered. Specifically, the transparent substrate to which the composite of the present invention is applied preferably has a total light transmittance of 50% or more, more preferably 60%, even after heat treatment at 180 ° C. for 2 hours. Or more, and most preferably 65% or more. Such a transparent substrate can sufficiently exhibit the performance of various elements. For example, in the case of a solar cell substrate, a sufficient amount of light can be guided to the element even if a transparent substrate having a high temperature thermal history is used. For this reason, the fall of a photoelectric conversion efficiency can be prevented over a long term.

  Furthermore, the composite of the present invention can be used in optical applications, that is, transparent plates, optical lenses, plastic substrates for liquid crystal display elements, color filter substrates, plastic substrates for organic EL display elements, solar cell substrates, touch panels, optical elements, optical waveguides. When applied to an LED encapsulant or the like, the average thermal expansion coefficient (linear expansion coefficient) of 30 to 150 ° C. is preferably 50 ppm / ° C. or less, more preferably 30 ppm / ° C. or less. In particular, when used for a sheet-like active matrix display element substrate, the average thermal expansion coefficient is preferably 30 ppm / ° C. or less, more preferably 20 ppm / ° C. or less. This is because if the average coefficient of thermal expansion exceeds the upper limit, problems such as warpage of the composite and disconnection of the aluminum wiring formed on the composite may occur in the manufacturing process.

  The lower limit of the average thermal expansion coefficient of the composite at 30 to 150 ° C. is not particularly set, but is −30 ppm / ° C. If the average coefficient of thermal expansion is below the lower limit, when the composite is bonded to another member, the difference in thermal expansion between the two becomes too large, causing local thermal stress at the bonding interface and peeling the bonding interface. There is a risk that.

  When the composite of the present invention is applied to a liquid crystal display element plastic substrate, a color filter substrate, an organic EL display element plastic substrate, a solar cell substrate, a touch panel, etc., the humidity expansion coefficient is preferably 100 ppm / humidity. % Or less, more preferably 50 ppm / humidity% or less, and further preferably 30 ppm / humidity% or less. Thereby, even if the composite_body | complex of this invention absorbs moisture at the time of a manufacturing process or use, the dimensional change will be fully suppressed. 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 sheet, 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.

  The optical sheet to which the composite of the present invention is applied may be provided with a gas barrier layer or a transparent electrode layer against water vapor or oxygen as necessary, particularly when used as a plastic substrate for display elements.

  In addition, a method for obtaining a sheet having a predetermined thickness, such as a solar cell substrate, an organic EL substrate, an electronic paper substrate, and a liquid crystal display element plastic substrate, using the composite composition of the present invention is a general method. There is no particular limitation as long as it is a sheet forming method. For example, a method of forming a composite composition containing a resin material and a fibrous filler into a sheet as it is, or after casting a dispersion medium of a fibrous filler, removing the dispersion medium to obtain a fibrous filler sheet, 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. In which the other components such as the dispersion medium are filtered and / or dried to obtain a sheet comprising the composite composition. 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.
[Preparation of fine cellulose fiber]
(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 5 times. As a result, a reactant fiber having a solid concentration of 25% 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 20 times at a pressure of 20 MPa using a high-pressure homogenizer (manufactured by Noro Sobia, 15MR-8TA type) to obtain a transparent cellulose nanofiber 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. The presence of carbonyl groups was confirmed from the ATR spectrum pattern, and the amounts of aldehyde groups and carboxyl groups in the cellulose fibers evaluated by the above-described method were 0.31 mol / g and 1.7 mol / g. .

[Production of complex]
( Reference Example 1 )
The cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 and a water-soluble acrylic resin (manufactured by Toagosei Co., Ltd., Jurimer AT-210, glass transition temperature −7 ° C.) are mixed, and 30 at room temperature is mixed. Stir for minutes. The obtained mixed solution was poured into a petri dish 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., and the content of cellulose nanofibers was 25% by weight and the thickness was 30 μm. A transparent film was obtained.

  Next, 80 mL of acetic anhydride, 4 g of sodium acetate, and 9.6 mL of ultrapure water were added to a separable flask to prepare a reaction solution. 200 mg of membranous cellulose was immersed in this reaction solution, and the reaction solution was stirred at 95 ° C. for 15 hours. The reaction was performed. After completion of the reaction, the obtained film was washed with ultrapure water, and water was evaporated in an oven at a temperature of 50 ° C. Thereby, the cellulose fiber was acetylated. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 70%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was −10 ppm. Moreover, it was -11 weight% when the weight reduction rate (weight reduction rate A) in 180 degreeC was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

( Reference Example 2 )
The cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 and a water-soluble acrylic resin (manufactured by Toagosei Co., Ltd., Jurimer AT-510, glass transition temperature 28 ° C.) are mixed, and 30 minutes at room temperature. Stir. The obtained mixed solution was poured into a petri dish 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., and the content of cellulose nanofibers was 25% by weight and the thickness was 30 μm. A transparent film was obtained.

  Next, 80 mL of acetic anhydride, 4 g of sodium acetate, and 9.6 mL of ultrapure water were added to a separable flask to prepare a reaction solution. 200 mg of membranous cellulose was immersed in this reaction solution, and the reaction solution was stirred at 95 ° C. for 15 hours. The reaction was performed. After completion of the reaction, the obtained film was washed with ultrapure water, and water was evaporated in an oven at a temperature of 50 ° C. Thereby, the cellulose fiber was acetylated. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 71%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 2 ppm. Moreover, it was -11 weight% when the weight reduction rate (weight reduction rate A) in 180 degreeC was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

( Reference Example 3 )
The cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 and a water-soluble acrylic resin (Cytec, acrylic copolymer Viacry 6286, glass transition temperature 30 ° C.) are mixed, and 30 minutes at room temperature. Stir. The obtained mixed solution was poured into a petri dish 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., and the content of cellulose nanofibers was 25% by weight and the thickness was 30 μm. A transparent film was obtained.

  Next, 80 mL of acetic anhydride, 4 g of sodium acetate, and 9.6 mL of ultrapure water were added to a separable flask to prepare a reaction solution. 200 mg of membranous cellulose was immersed in this reaction solution, and the reaction solution was stirred at 95 ° C. for 15 hours. The reaction was performed. After completion of the reaction, the obtained film was washed with ultrapure water, and water was evaporated in an oven at a temperature of 50 ° C. Thereby, the cellulose fiber was acetylated. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 76%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was −25 ppm. Moreover, it was -10 weight% when the weight reduction rate in 180 degreeC (weight reduction rate A) was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

( Reference Example 4 )
The aqueous solution of cellulose nanofibers having a solid content concentration of 0.2% obtained in Production 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. A transparent film was obtained.

  Next, 80 mL of acetic anhydride, 4 g of sodium acetate, and 9.6 mL of ultrapure water were added to a separable flask to prepare a reaction solution. 200 mg of membranous cellulose was immersed in this reaction solution, and the reaction solution was stirred at 95 ° C. for 15 hours. The reaction was performed. After completion of the reaction, the obtained film was washed with ultrapure water, and water was evaporated in an oven at a temperature of 50 ° C. Thereby, the cellulose fiber was acetylated. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 90%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 13 ppm. Moreover, it was -7 weight% when the weight reduction rate (weight reduction rate A) in 180 degreeC was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

( Reference Example 5 )
Tetraethoxysilane was added to the cellulose nanofiber-dispersed aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 in the same weight as the weight of the cellulose nanofiber solid, and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 88%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 11 ppm. Moreover, it was -14 weight% when the weight decreasing rate (weight decreasing rate A) in 180 degreeC was measured based on the thermogravimetric measuring method prescribed | regulated by JISK7120.

( Reference Example 6 )
Phenyltriethoxysilane was added to the cellulose nanofiber-dispersed aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 in the same weight as the cellulose nanofiber solid weight, and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 89%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 13 ppm. Moreover, it was -14 weight% when the weight decreasing rate (weight decreasing rate A) in 180 degreeC was measured based on the thermogravimetric measuring method prescribed | regulated by JISK7120.

(Example 1 )
3-acryloxypropyltrimethoxysilane was added to the cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 in the same weight as the cellulose nanofiber solid weight, and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 87%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 11 ppm. Moreover, it was -14 weight% when the weight decreasing rate (weight decreasing rate A) in 180 degreeC was measured based on the thermogravimetric measuring method prescribed | regulated by JISK7120.

(Example 2 )
3-Methacryloxypropyltrimethoxysilane was added to the cellulose nanofiber-dispersed aqueous solution with a solid content concentration of 0.2% obtained in Production Example 1 in the same weight as the weight of the solid content of cellulose nanofiber, and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 90%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 12 ppm. Moreover, it was -13 weight% when the weight reduction rate in 180 degreeC (weight reduction rate A) was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

(Example 3 )
Titanium alkoxide was added to the cellulose nanofiber-dispersed aqueous solution having a solid content concentration of 0.2% obtained in Preparation Example 1 in the same weight as the cellulose nanofiber solid weight, and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 88%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 12 ppm. Moreover, it was -13 weight% when the weight reduction rate in 180 degreeC (weight reduction rate A) was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

( Reference Example 7 )
1 part by weight of dibutylhydroxytoluene (antioxidant) was added to the cellulose nanofiber dispersion aqueous solution having a solid content concentration of 0.2% obtained in Production Example 1 (solid content: 100 parts by weight), and stirred at room temperature for 30 minutes. The obtained mixed solution was poured into a petri dish subjected to a mold release treatment, moisture was evaporated in an oven at a temperature of 50 ° C., and further dried in a vacuum oven at 120 ° C. to obtain a transparent film having a thickness of 30 μm. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 89%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 9 ppm. Moreover, it was -8 weight% when the weight reduction rate in 180 degreeC (weight reduction rate A) was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

(Comparative Example 1)
Water-soluble acrylic resin (Cytech, Viacry 6286, glass transition temperature 30 ° C.) 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. to form a transparent film having a thickness of 30 μm. Obtained. The film obtained was evaluated for light transmittance and average coefficient of linear expansion. The total light transmittance was 74%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 180 ppm. Moreover, it was -15 weight% when the weight reduction rate in 180 degreeC (weight reduction rate A) was measured based on the thermogravimetry method prescribed | regulated by JISK7120.

(Comparative Example 2)
The aqueous solution of cellulose nanofibers having a solid content concentration of 0.2% obtained in Production 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. A transparent film was obtained. The film obtained was evaluated for light transmittance and thermal expansion coefficient. The total light transmittance was 91%, and the average linear expansion coefficient in the range of 30 ° C. to 150 ° C. was 8 ppm. Moreover, it was -17 weight% when the weight decreasing rate (weight decreasing rate B) in 180 degreeC was measured based on the thermogravimetric measuring method prescribed | regulated by JISK7120.

[Evaluation of complex]
The characteristic evaluation method is as follows. In addition, about the film obtained by each Example , each reference example, and each comparative example, the total light transmittance, the thermal expansion coefficient, and the humidity expansion coefficient were measured, respectively.

  Each characteristic was evaluated immediately after the production of the film and after heat treatment at 180 ° C. for 2 hours.

a) Total light transmittance The total light transmittance was measured with a spectrophotometer U3200 (manufactured by Shimadzu Corporation).

b) Thermal expansion coefficient (linear expansion coefficient)
Using a TMA / SS120C type thermal stress strain measuring device manufactured by Seiko Electronics Co., Ltd., the temperature was raised from 30 ° C. to 150 ° C. at a rate of 5 ° C. per minute in a nitrogen atmosphere, and then cooled to 0 ° C. once. The temperature was raised again at a rate of 5 ° C. per minute, and the value at 30 ° C. to 150 ° C. was measured and obtained. The load was 5 g and the measurement was performed in the tensile mode.

c) Humidity coefficient of expansion Draw two points to be used for dimensional measurement on the obtained film, leave it in an atmosphere of room temperature 23 ° C and humidity 60% for 24 hours, and then put it in a dryer at 100 ° C for 3 hours to dry .

Immediately after drying, the distance between the two points drawn in advance was measured with a three-dimensional measuring machine, and the distance between the two points at this time was used as a reference. The dried film is allowed to stand again in an atmosphere of room temperature 23 ° C. and humidity 60% for 24 hours, and then the distance between the two points drawn in advance is measured again with a three-dimensional measuring machine to determine the dimensional change rate from the reference distance. Calculated. Further, the apparent humidity after drying was set to 0%, and the humidity expansion coefficient per 1% humidity in the range of 0% to 60% humidity was calculated.
The results of the measurement are shown in Table 1.

As is clear from Table 1, the films obtained in each Example and each Reference Example had a high light transmittance even after the heat treatment. In particular, the tendency was remarkable for those in which the fibrous filler was subjected to acetylation treatment and those in which a coupling agent containing an acrylic group or a methacrylic group was introduced.

  In each example, the weight reduction rate A of the fibrous filler was smaller than the weight reduction rate B of the fibrous filler in the comparative example.

From the above, it was revealed that the composite of the present invention can maintain excellent characteristics before heating even when heated.
In addition, the raw material used by the Example , the reference example, and the comparative example is as follows.

Acrylic polymer: Jurimer AT-210, manufactured by Toagosei Co., Ltd .: Jurimer AT-510, manufactured by Toagosei Co., Ltd .: Viacry 6286, manufactured by Cytec Corporation

Coupling agent: Tetraethoxysilane Wako Pure Chemicals: Phenyltriethoxysilane Azmax: 3-glycidoxypropyltriethoxysilane Shin-Etsu Chemical: 3-acryloxypropyltrimethoxysilane Shin-Etsu Chemical: 3-methacryloxypropyltri Methoxysilane Shin-Etsu Chemical: N-2- (aminoethyl) -3-aminopropyltrimethoxysilane Shin-Etsu Chemical: Titanium alkoxide (made by KR-ET Ajinomoto Fine Techno)

Antioxidant: Dibutylhydroxytoluene (Sumilyzer BHT, manufactured by Sumitomo Chemical)

a Thermogravimetric curve with weight reduction rate A b Thermogravimetric curve with weight reduction rate B

Claims (15)

A composite composition composed of a fibrous filler and a dispersion medium,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting treatment is a treatment for introducing at least one of a coupling agent having an acrylic group or a methacrylic group and a hydrolyzate of the coupling agent into the cellulose fiber, and JIS K for the fibrous filler. The weight loss rate at 180 ° C. measured according to the thermogravimetry method specified in 7120 is A, and the cellulose fiber subjected to oxidation treatment is measured according to the same method as the thermogravimetry method. A composite composition characterized in that, when the weight loss rate at 180 ° C. is B, the treatment satisfies the relationship of A <B. A composite composition composed of a fibrous filler and an acrylic resin-containing resin material,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting treatment is a treatment for introducing at least one of a coupling agent having an acrylic group or a methacrylic group and a hydrolyzate of the coupling agent into the cellulose fiber, and JIS K for the fibrous filler. The weight loss rate at 180 ° C. measured according to the thermogravimetry method specified in 7120 is A, and the cellulose fiber subjected to oxidation treatment is measured according to the same method as the thermogravimetry method. A composite composition characterized in that, when the weight loss rate at 180 ° C. is B, the treatment satisfies the relationship of A <B.   The composite composition according to claim 1, wherein the coupling agent is alkoxysilane or alkoxytitanium. A composite composition composed of a fibrous filler and a dispersion medium,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting process is a process of introducing at least one of alkoxy titanium and a hydrolyzate of alkoxy titanium into the cellulose fiber, and the thermogravimetric measurement method defined in JIS K 7120 is used for the fibrous filler. The weight loss rate at 180 ° C. measured in accordance with A is defined as A, and the weight loss rate at 180 ° C. measured in accordance with the same method as the thermogravimetric method for cellulose fibers subjected to oxidation treatment is defined as B. A composite composition characterized by being a treatment satisfying a relationship of A <B. A composite composition composed of a fibrous filler and an acrylic resin-containing resin material,
The fibrous filler is composed of cellulose fibers subjected to oxidation treatment and thermal decomposition suppression treatment,
The thermal decomposition inhibiting process is a process of introducing at least one of alkoxy titanium and a hydrolyzate of alkoxy titanium into the cellulose fiber, and the thermogravimetric measurement method defined in JIS K 7120 is used for the fibrous filler. The weight loss rate at 180 ° C. measured in accordance with A is defined as A, and the weight loss rate at 180 ° C. measured in accordance with the same method as the thermogravimetric method for cellulose fibers subjected to oxidation treatment is defined as B. A composite composition characterized by being a treatment satisfying a relationship of A <B.   The composite composition according to any one of claims 1 to 5, wherein the weight reduction rate A and the weight reduction rate B satisfy a relationship of A / B ≦ 0.9.   The composite composition according to any one of claims 1 to 6, wherein an average fiber diameter of the cellulose fibers is 4 to 1000 nm.   The composite composition according to any one of claims 1 to 7, wherein the cellulose fiber is obtained by refining a cellulose raw material by at least one of chemical treatment and mechanical treatment.   The cellulose fiber subjected to the oxidation treatment 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. A composite composition as described.   The cellulose fiber subjected to the oxidation treatment uses natural cellulose as a raw material, uses an N-oxyl compound as an oxidation catalyst, and performs an oxidation treatment on the raw material by allowing a co-oxidant to act on the raw material in water. The composite composition according to any one of claims 1 to 9, which is obtained.   The composite composition according to claim 2 or 5, wherein a content of the fibrous filler is 0.1 to 99.9% by weight. A composite formed by molding the composite composition according to claim 2 or 5 ,
A composite having a thickness of 10 to 2000 μm.   The composite according to claim 12, wherein the total light transmittance is 50% or more after the heat treatment at 180 ° C for 2 hours.   The composite according to claim 12 or 13, wherein the coefficient of thermal expansion at 30 ° C to 150 ° C is -30 to 50 ppm / ° C.   The composite according to any one of claims 12 to 14, having a humidity expansion coefficient of 100 ppm / humidity% or less.

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