JP2009096167A - Molded article of microfibrillar cellulose and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-strength microfibrillar cellulose-containing molding having narrow variance of strength stably and efficiently. <P>SOLUTION: The method for manufacturing the molding by flow-casting a dispersion liquid containing microfibrillar cellulose and a dispersion medium comprises the steps of: forming a sheet, which has 1-1,500 μm thickness and 45-75 wt.% dispersion medium content, by using the dispersion liquid; and forming the molding by heating, pressurizing or heating and pressurizing the single sheet or a laminate obtained by layering a plurality of the sheets. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a microfibril cellulose molded article and a method for producing the same.

  In recent years, plastics derived from plants and animals have been actively developed as an alternative to plastics derived from petroleum resources. One method is to use cellulose, which is the most abundant biomass resource on the earth. Cellulose can be produced from organisms other than plants, such as plants, bacteria, and sea squirts, and is not an oil resource. Therefore, even if it is finally incinerated, its impact on the environment is small.

Many plastic substitutes using cellulose have been reported so far. In recent years, it has been reported that a relatively strong molded product can be obtained by drying and molding microfibril cellulose in the form of microfibrils (see, for example, Patent Document 1). However, in the technique disclosed in Patent Document 1, there is no mention of the influence of the thickness of the sheet as the molded product precursor and the dispersion medium content of the sheet on the absolute value of the strength of the molded product and the variation in strength, Depending on the thickness of the sheet, volatile matter mainly due to the dispersion medium may remain inside, or cracks will occur in the molded product due to an increase in internal pressure due to volatilization, resulting in a decrease in the absolute value of the strength and a large variation in strength. I understood. In addition, depending on the content of the dispersion medium, the hydroxyl group of cellulose faces the inside of the glucose ring, the adhesion between microfibrils or sheets decreases, and the amount of volatiles is too high, resulting in a decrease in absolute strength or strength. It was found that the variation of. Thus, when it was going to use cellulose which is a biomass resource industrially as a highly functional material, the improvement of the process leading to shaping | molding was indispensable.
JP 2003-201695 A

  The present invention provides a method for stably and efficiently producing a molded article containing microfibril cellulose having high strength and little strength variation.

  As a result of intensive studies in view of the above problems, the present inventor has obtained a specific thickness and a specific dispersion medium from the dispersion liquid in a method for producing a molded product from the dispersion liquid containing microfibril cellulose and the dispersion medium. By forming a sheet having a content rate and forming the molded body by heating and / or pressurizing the sheet, the present inventors have found that the above problems can be solved, and based on this finding, the present invention has been completed. It is a thing.

That is, the present invention is achieved by the items (1) to (9).
(1) A method for producing a molded product by casting a dispersion containing microfibril cellulose and a dispersion medium,
Using the dispersion, forming a sheet having a thickness of 1 μm or more and 1500 μm or less and a dispersion medium content of 45% by weight or more and 75% by weight or less;
A step of forming a molded body by heating, pressurizing or both heating and pressurizing a laminate obtained by laminating a single sheet or a plurality of sheets;
A method for producing a molded article comprising:
(2) The method for producing a molded article according to item (1), wherein the sheet forming the molded body is impregnated with a binder resin.
(3) The method for producing a molded article according to item (2), wherein the binder resin contains a thermosetting resin.
(4) The sheet forming the molded body is any one of items (1) to (3), which is impregnated with a coupling agent and / or a hydrolyzate of the coupling agent. The manufacturing method of the molded article of description.
(5) The method for producing a molded article according to any one of (1) to (4), wherein the formation of the sheet is performed by a process including filtration.
(6) The method for producing a molded article according to any one of (1) to (5), wherein the dispersion medium is removed by freeze-drying after forming the sheet.
(7) The method for producing a molded article according to item (3), wherein the thermosetting resin is a phenol resin.
(8) The method for producing a molded article according to item (4), wherein the sheet forming the molded body is impregnated with a binder resin and a coupling agent and / or a hydrolyzate of the coupling agent.
(9) A molded article containing microfibril cellulose obtained by the method for producing a molded article according to any one of items (1) to (8).

  According to the present invention, it is possible to stably and efficiently produce a molded product containing microfibril cellulose having high strength and little strength variation.

  The present invention is a method for producing a molded product by casting a dispersion liquid containing microfibril cellulose and a dispersion medium, and using the dispersion liquid, the dispersion medium content is 45% by weight or more at a thickness of 1 μm or more and 1500 μm or less. A step of forming a sheet of 75% by weight or less, and a step of forming a molded body by heating, pressurizing, or heating and pressurizing a laminate obtained by laminating one or a plurality of the sheets. The present invention relates to a method for manufacturing a molded product. Thereby, it is possible to stably and efficiently obtain a molded product containing microfibril cellulose having high strength and little strength variation.

  In the present invention, the microfibril cellulose is a microfibrillated cellulose. The term “microfibrillation” as used herein refers to a state in which cellulose is torn up to its constituent microfibers. Specifically, an external force such as a strong mechanical shearing force is applied to the cellulose to reduce the cellulose to 0. 0. This refers to microfibrillation to a thickness of about 01 to 1 μm.

  Further, the microfibril cellulose in the present invention has a thickness exceeding 1 μm due to mixing of cellulose that is not sufficiently microfibrillated in the process of microfibrillating cellulose or cellulose that has not been microfibrillated. In the case of containing cellulose having a thickness exceeding 1 μm, the amount is preferably 75% by weight or less. More preferably, it is 50 weight% or less. Within the above range, voids between fibers do not occur, and a molded product containing a homogeneous, high-density, relatively thick microfibril cellulose can be stably and more efficiently produced.

  Hereafter, the manufacturing method of the molded article containing the microfibril cellulose of this invention is demonstrated sequentially by a specific example. First, although the flow example of the whole process is shown, this invention is not limited to these. In the present invention, the expression “binder” means a binder resin, a coupling agent and a hydrolyzate of the coupling agent, and the expression “coupling agent” means a coupling agent for convenience. And / or a hydrolyzate of the coupling agent.

As shown in Table 1, in the present invention, the process may be different depending on whether the binder described later is not used or when the binder is used. In the former, for example, in a sheet forming step including a drying step described later, the thickness of the sheet and the content of the dispersion medium are adjusted, and a sheet having a thickness of 1 μm to 1500 μm and a dispersion medium content of 45 wt% to 75 wt%, preferably Forms a sheet having a thickness of 5 μm or more and 1000 μm or less and a dispersion medium content of 45% by weight or more and 60% by weight or less. Thereafter, when a plurality of sheets are used, the sheets are laminated before forming the formed body. After performing, the method of forming a molded object after preheating is mentioned, Moreover, when using the said sheet | seat by one, the method of forming a molded object after performing only preheating is mentioned.
On the other hand, when using a binder, after forming the sheet, if necessary, freeze-drying, binder coating, drying after binder coating, sheet lamination / preheating, a method of forming a molded body, And a microfibril cellulose dispersion to prepare a dispersion by mixing a binder in advance, and then forming a sheet using the dispersion, followed by freeze drying, binder coating, and drying after binder coating as necessary. A method of forming a molded body after stacking and preheating the sheets is mentioned. In addition, when there are a plurality of types of binders to be used, a mixture of them may be used. When a mixed solution cannot be produced due to the solubility problem of the binder to be used, a binder coating may be used. In addition, it may be impregnated stepwise by repeating drying after coating the binder a plurality of times.

Below, the detailed example of the manufacturing method of the molded article containing a microfibril cellulose is demonstrated.
First, a dispersion containing microfibril cellulose is prepared, and the preparation method will be described.
The dispersion containing microfibril cellulose used in the present invention is a method in which the dispersion medium used in the microfibrillation process and the microfibrillated cellulose are uniformly mixed in the process of microfibrillation, Examples include a method in which microfibrillated cellulose and a dispersion medium are separately mixed without using a medium, but the microfibrillated cellulose and the dispersion medium are finally mixed, and about 0.01 to 1 μm. If the microfibril cellulose microfibrillated to the thickness is uniformly dispersed in the dispersion medium, it is not limited thereto. Also, once the dispersion is prepared, other dispersion media, non-microfibrillated cellulose, surfactants, resins, and the like can be added to the extent that dispersibility is maintained.

  Examples of the raw material for microfibril cellulose used in the present invention include plant-derived materials and materials derived from organisms other than plants. Among these, examples of plant-derived materials include wood, bamboo, hemp, cotton, jute, kenaf, farmland waste, sugarcane, sugar beet, shochu and other shochu, cloth, waste paper, etc. Examples of the starting material include microorganisms such as acetic acid bacteria, and sea squirts. Among these, it is preferable to use a plant-derived raw material for reasons such as cost and availability.

  In the present invention, as a method for obtaining microfibril cellulose from the raw material of the microfibril cellulose, it can be obtained by a known method for microfibrillation of cellulose. Examples of the method for microfibrillation include a method using a vibration mill, a method using a high-pressure homogenizer such as a high-pressure homogenizer, and a method using a stone mill. The fiber diameter of the microfibril cellulose obtained by such a method can be used outside the above range, but if the lower limit is 0.01 μm or more, handling is easy, and if the upper limit is 1 μm or less, a homogeneous molded product is produced. It is preferable because it is possible. The fiber length is preferably 0.01 mm to 5 mm. Although it can be used outside the above range, the strength of the molded product is good when the lower limit is 0.01 mm or more, and the dispersibility is good when the upper limit is 5 mm or less.

  The dispersion medium of the dispersion liquid containing the microfibril cellulose is preferably water, but may be a mixed solvent containing an organic solvent compatible with water. Examples of such organic solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, dioxane, acetone, methyl ethyl ketone, tetrahydrofuran, glycerin, neopentyl glycol, methyl cellosolve, ethyl cellosolve, pentaerythritol and Examples thereof include dimethyl sulfoxide. These are the dispersibility of microfibril cellulose in the dispersion, the filtration at the time of casting the dispersion, the spreadability on the base material used in the coating method, the ease of pouring, and the thickness of 1 μm to 1500 μm. It is appropriately selected in consideration of the volatility of the dispersion medium when forming a sheet having a dispersion medium content of 45 wt% or more and 75 wt% or less, the filterability of the dispersion described later, and the like.

  The concentration of the dispersion containing the microfibril cellulose is preferably 0.01 wt% to 10 wt%, and more preferably 0.1 wt% to 5 wt%. When the dispersion concentration is equal to or lower than the upper limit value, the viscosity of the dispersion liquid containing microfibril cellulose is not significantly increased, and a uniform sheet can be obtained. When the dispersion concentration is equal to or higher than the lower limit value, a sheet having a predetermined thickness is obtained. The amount of the dispersion to be used is not increased more than necessary, and the working efficiency is improved. Moreover, in this invention, the solvent for melt | dissolving resin and resin for impregnation mentioned later may be added in the range which does not affect the dispersibility of microfibril cellulose.

Next, a process of forming a sheet having a thickness of 1 μm or more and 1500 μm or less and a dispersion medium content of 45 wt% or more and 75 wt% or less using the dispersion liquid containing microfibril cellulose prepared above will be described.
As a method of casting a dispersion containing microfibril cellulose to form a sheet, a component that substantially forms a molded product such as microfibril cellulose and other components such as a dispersion medium are roughly separated. If it is a process which raises the density | concentration of the component which substantially forms molded articles, such as microfibril cellulose, it will not specifically limit.

In such a process, as a preferable embodiment, a sheet is formed by casting a microfibril cellulose dispersion on a filter paper, a membrane filter, a paper mesh, or the like, and separating other components such as a dispersion medium by filtration. The so-called wet molding method can be used. The filtration may be performed under reduced pressure or increased pressure in order to increase work efficiency. In the case of continuous production, a method of continuously forming a thin layer sheet using a paper machine used in the paper industry is also included in the present invention.
As another example of a preferred embodiment, the dispersion is cast on a substrate, and after performing a dedispersion medium, it is obtained by a so-called coating method in which a thin layer sheet is formed by peeling from the substrate. be able to.

  What is necessary is just to select what the sheet | seat formed after drying can peel easily as said base material, What is necessary is just to use a suitable thing in a metal plate or a resin board. Examples of the metal plate include a stainless plate, a brass plate, an aluminum plate, a zinc plate, a copper plate, and an iron plate. Examples of the resin plate include an acrylic plate, a Teflon (registered trademark) plate, a polyethylene terephthalate plate, a vinyl chloride plate, Examples include polystyrene plates and polyvinylidene chloride plates.

  The amount of the dispersion liquid containing microfibril cellulose in the step of forming the sheet is not particularly limited as long as the thickness of the sheet falls within a predetermined range.

The dispersion medium content adjustment in the sheet is not limited as long as the dispersion medium content is 45% by weight or more and 75% by weight or less, preferably 45% by weight or more and 60% by weight or less.
As such a preferable example, a method of carrying out heat drying or drying at room temperature, drying under reduced pressure, freeze drying, etc. alone or in combination can be exemplified. The drying temperature for the heat drying or drying at room temperature is preferably 20 ° C to 200 ° C. The drying temperature can be used outside the above range, but if the upper limit value is 200 ° C. or less, it is difficult for cellulose to be decomposed by heat, and if the lower limit value is 20 ° C. or more, the drying time is not increased. The drying temperature for the vacuum drying is preferably 20 ° C to 200 ° C. The vacuum drying temperature can be used outside the above range, but if the upper limit value is 200 ° C. or lower, it is difficult for cellulose to be decomposed by heat, and if the lower limit value is 20 ° C. or higher, the drying time is not increased. The degree of vacuum during drying under reduced pressure is preferably 100,000 Pa or less, more preferably 10,000 Pa or less. The degree of decompression can be used even outside the above range, but it is preferable that the degree of decompression is not more than the upper limit because sufficient water removal efficiency can be obtained.

  The lyophilization temperature is preferably 0 ° C. or lower, more preferably −5 ° C. or lower. The degree of vacuum for freeze-drying is preferably 10,000 Pa or less, more preferably 1,000 Pa or less.

  The sheet according to the present invention is obtained through a sheet forming step including a drying step, if necessary, and has a thickness of 1 μm to 1500 μm and a dispersion medium content of 45 wt% to 75 wt%, preferably The technical point is that the thickness is 5 μm or more and 1000 μm or less, and the dispersion medium content is 45% by weight or more and 60% by weight or less. In the present invention, a sheet forming step involving unit operations such as casting and filtering of the dispersion liquid (here, a dedispersing medium is performed to some extent), and if necessary, the sheet contains an appropriate dispersion medium. The drying to adjust the amount (dispersion of the content of the dispersion medium) is performed. At this stage, if the sheet thickness and the content of the dispersion medium are out of the technical scope of the present invention, a molded product containing microfibril cellulose with high strength and little strength variation no matter what steps are added in the subsequent steps. Cannot be produced stably and efficiently. The reason for this is that the hydroxyl group of cellulose expresses the most effective interaction such as hydrogen bonding between microfibrils and between sheets. It is indispensable for the production of the product, and in order to effectively express the interaction, the hydroxyl group of the cellulose is stabilized with an appropriate amount of dispersion medium, while maintaining the structure as much as possible. This is because it is necessary that the dispersion medium volatilizes and evaporates quickly and uniformly to fix the molecular structure of the cellulose uniformly. For these reasons and reasons, the thickness of the sheet obtained in the above-mentioned sheet forming step is 1 μm or more and 1500 μm or less in order to promote the self-sustainability of the sheet and volatilization and transpiration of the uniform and quick dispersion medium during molding. Yes, it is preferably 5 μm or more and 1000 μm or less. If the lower limit is 1 μm or more, preferably 5 μm or more, sufficient strength at the sheet stage can be obtained and the self-supporting property can be maintained, so that workability is improved and a thick molded product is obtained. This is preferable because the number of laminated layers required for this is not enormous. On the other hand, when the upper limit value is 1500 μm or less, preferably 1000 μm or less, the moisture content on the surface of the sheet is not significantly reduced, and the moisture content on the inside and the surface of the sheet can be maintained uniformly. Sufficient moisture content can be maintained, and when forming, the hydroxyl group facing the outside of the cellulose provides sufficient adhesion between the sheets, and the microfibrils in the sheet have a homogeneous interaction. It is preferable because it can be obtained and a molded product having a uniform and high strength can be obtained. The thickness of the sheet can be adjusted as appropriate by the concentration of the dispersion, the amount of casting, the number of castings, and the like.

  The dispersion medium content of the sheet has a lower limit of 45% by weight, an upper limit of 75% by weight or less, and a preferred upper limit of 60% by weight or less. Below the upper limit, the hydroxyl groups of cellulose are arranged at an appropriate distance, the interaction is sufficient, the dispersion medium is sufficiently volatilized and evaporated at the time of molding, and cracks and voids do not occur in the molded product, which is homogeneous and high A strong molded product can be obtained, which is preferable. On the other hand, if it is at least the lower limit, an interaction such as a hydrogen bond of a hydroxyl group in cellulose appears between the microfibrils and between the sheets, and a molded product having a high absolute value of strength and a small strength variation can be obtained.

The sheet obtained above can be impregnated with a binder. The binder is composed of an organic polymer and / or a coupling agent, and the physical properties of the molded product can be improved by impregnating the sheet with the organic polymer and the coupling agent. In the physical properties, in particular, when improving water resistance, heat resistance, dimensional stability, mechanical properties, etc., it is preferable to impregnate a binder according to the properties. In addition, cellulose having a hydrophilic group is preferable because it has a high water absorption rate, and the water resistance can be improved by using a relatively small amount of binder in order to solve the problems caused by this.
As the organic polymer used in the present invention, known polymers can be used, and examples thereof include water-soluble polymers, thermoplastic resins, and thermosetting resins.

  The water-soluble polymer is not particularly limited as long as it dissolves in water, such as a thermoplastic resin, a thermosetting resin, and a natural polymer, such as polyvinyl alcohol, polyethylene oxide, polyacrylamide, and polyvinylpyrrolidone. Examples include synthetic polymers, starches, polysaccharides such as alginic acid, natural polymers such as hemicellulose, gelatin, glue, casein and other proteins such as wood.

  The thermoplastic resin is not particularly limited. For example, vinyl chloride resin, vinyl acetate resin, polystyrene, ABS resin, acrylic resin, polyethylene, polyethylene terephthalate, polypropylene, fluororesin, polyamide resin, polyimide resin, Polyacetal resin, polycarbonate, polylactic acid, polyglycolic acid, poly-3-hydroxybutyrate, poly-4-hydroxybutyrate, polyhydroxyvalerate, polyethylene adipate, polycaprolactone, polyester such as polypropiolactone, polyethylene glycol, etc. Polyamides such as polyether, polyglutamic acid, polylysine, etc., polyvinyl alcohol, polyurethane, starches, polysaccharides such as alginic acid, lignin and hemise which are constituents of wood Loin can be used gelatin, glue, a natural polymer such as a protein or the like, including casein.

  Examples of the thermosetting resin include phenol resins, urea resins, melamine resins, unsaturated polyester resins, epoxy resins, diallyl phthalate resins, polyurethane resins, silicon resins, maleimide resins, polyimide resins, starches, alginic acid and other polysaccharides, Examples include natural polymers such as proteins such as hemicellulose, gelatin, glue, and casein. In particular, the phenol resin herein includes a compound having one or more phenolic hydroxyl groups in the molecule, a novolak or bisphenol, a resin having naphthol or naphthol in the molecule, a paraxylylene-modified phenol resin, or a dimethylene ether type resol. , Resol resins such as methylol-type resole, compounds obtained by further methylolating the above resins, lignin and lignin derivatives containing one or more phenolic hydroxyl groups, lignin degradation products, and lignin or lignin derivatives and lignin degradation products modified Or the thing which mixed these with the phenol resin manufactured from petroleum resources is also included. The water-soluble polymer, the thermoplastic resin, and the thermosetting resin can be used individually or in combination of two or more, but the affinity with cellulose, strength, heat resistance, etc. In consideration of the thermosetting resin. When the thermosetting resin is cured and used, a curing agent for the thermosetting resin can be used in combination.

  Among these, a phenol resin is more preferable because it has high affinity with microfibril cellulose, excellent adhesion to the fiber interface when cured, and consequently excellent mechanical properties such as water resistance and strength.

As a coupling agent used for this invention, a well-known thing can be used and a silane coupling agent and a titanium coupling agent can be mentioned.
The silane coupling agent only needs to contain at least one silicon atom and at least one alkoxy group. Other functional groups include one or more epoxy groups, epoxy cyclohexyl groups, amino groups, hydroxyl groups, acrylic groups, methacryl groups, vinyl groups, phenyl groups, phenol groups, styryl groups, and isocyanate groups in the structure. Is preferred. In the present invention, since the same effect as that of the coupling agent can be obtained, so-called tetraalkoxysilane containing four alkoxy groups is also included in the silane coupling agent.
Specific examples of the silane coupling agent include tetraalkoxysilane compounds; alkyl group-containing alkoxysilane compounds such as methyltrialkoxysilane and dimethyldialkoxysilane; 3-glycidoxypropyltrialkoxysilane, 3-glycol. Epoxy silane compounds such as sidoxypropylmethyl dialkoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrialkoxysilane; 3-aminopropyltrialkoxysilane, N-phenyl-3-aminopropyltrialkoxysilane, And aminoalkoxysilane compounds such as N-phenyl-3-aminopropyltrialkoxysilane; 3-acryloxypropyltrialkoxysilane, 3-methacryloxypropyltrialkoxysilane, and (Meth) acrylalkoxysilane compounds such as 3-methacryloxypropylmethyl dialkoxysilane; vinylalkoxysilane compounds such as vinyltrialkoxysilane; phenyltrialkoxysilane, diphenyldialkoxysilane, and 4-hydroxyphenyltrialkoxysilane , Etc .; styryl group-containing alkoxysilane compounds such as p-styryltrialkoxysilane; isocyanate alkoxysilane compounds such as 3-isocyanatopropyltrialkoxysilane; and the like.
Among these groups, a tetraalkoxysilane compound, an alkyl group-containing alkoxysilane compound, and a phenyl group-containing alkoxysilane compound are preferable because they have a high effect of increasing water resistance.
Further, when used in combination with a binder resin, particularly a thermosetting resin such as a phenol resin, a tetraalkoxysilane compound, an alkyl group-containing alkoxysilane compound, an epoxysilane compound, an aminoalkoxysilane compound, and a phenyl group-containing alkoxysilane compound are water resistant. It is preferable in order to further enhance the property synergistically. This is presumably because the silane coupling agent modifies the surface of the microfibril cellulose, improves the conformability between the binder resin and the microfibril cellulose, and reduces the voids into which moisture enters.

The titanium coupling agent only needs to contain at least one titanium atom and at least one alkoxy group, and other functional groups include an epoxy group, an epoxycyclohexyl group, an amino group, a hydroxyl group, an acrylic group, It is preferable that one or more methacryl groups, vinyl groups, phenyl groups, phenol groups, styryl groups, and isocyanate groups are included in the structure. In the present invention, since the same effect as the above coupling agent can be obtained, so-called tetraalkoxytitanium containing four alkoxy groups is also included in the above-described titanium coupling agent.
Specific examples of the titanium coupling agent include tetraalkoxytitanium compounds; alkyl group-containing alkoxytitanium compounds such as methyltrialkoxytitanium and dimethyldialkoxytitanium; 3-glycidoxypropyltrialkoxytitanium, 3-glycol Epoxyalkoxytitanium compounds such as sidoxypropylmethyldialkoxytitanium and 2- (3,4-epoxycyclohexyl) ethyltrialkoxytitanium; 3-aminopropyltrialkoxytitanium, N-phenyl-3-aminopropyltrialkoxytitanium , And N-phenyl-3-aminopropyltrialkoxytitanium, etc .; aminoalkoxyxytitanium compounds; 3-acryloxypropyltrialkoxytitanium, 3-methacryloxypropyltrialkoxy (Meth) acrylalkoxytitanium compounds such as tan and 3-methacryloxypropylmethyl dialkoxytitanium; vinylalkoxytitanium compounds such as vinyltrialkoxytitanium; phenyltrialkoxytitanium, diphenyldialkoxytitanium, and 4-hydroxyphenyl Examples include phenyl group-containing alkoxytitanium compounds such as trialkoxytitanium; styryl group-containing alkoxytitanium compounds such as p-styryltrialkoxytitanium; isocyanate alkoxytitanium compounds such as 3-isocyanatopropyltrialkoxytitanium;
Among these groups, a tetraalkoxytitanium compound, an alkyl group-containing alkoxytitanium compound, and a phenyl group-containing alkoxytitanium compound are preferable because of their high effects of increasing water resistance.
Further, when used in combination with a binder resin, particularly a thermosetting resin such as a phenol resin, a tetraalkoxytitanium compound, an alkyl group-containing alkoxytitanium compound, an epoxytitanium compound, an aminoalkoxytitanium compound, and a phenyl group-containing alkoxytitanium compound are water resistant. It is preferable in order to further enhance the property synergistically. This is presumably because the titanium coupling agent modifies the surface of the microfibril cellulose, improves the conformability between the binder resin and the microfibril cellulose, and reduces the voids into which moisture enters.
Moreover, you may use a hydrolyzate as said coupling agent. The selection of the coupling agent or hydrolyzate may be appropriately selected in consideration of the compatibility with the dispersion medium, the binder, the stability of the hydrolyzate, etc. Can be easily prepared by stirring and mixing. Further, even if the alkoxide group is not produced by hydrolysis, it is included in the present invention as long as the molecular structure is the same as that of the coupling agent hydrolyzate described above.

In impregnating the binder with the sheet, when the organic polymer is impregnated as the binder impregnating liquid, an organic polymer impregnating liquid in which the organic polymer is dissolved or dispersed in a dispersion medium may be used. The concentration of the organic polymer impregnation liquid is preferably 0.1 to 60% by weight, more preferably 2 to 30% by weight.
When impregnating the coupling agent as a binder impregnating solution, it is preferable to use a coupling agent impregnating solution obtained by dissolving or dispersing the coupling agent in a dispersion medium. The concentration of such a coupling agent impregnating solution is as follows. 0.01 to 40% by weight, more preferably 0.05 to 20% by weight. Moreover, when impregnating the said organic polymer and a coupling agent, both liquid mixture can also be used, As a density | concentration of an organic polymer impregnation liquid, 0.1 to 60 weight% is preferable, More preferably The concentration of the coupling agent impregnating liquid is preferably 0.01 to 40% by weight, and more preferably 0.05 to 20% by weight.

  The solvent for the organic polymer impregnation liquid and the coupling agent impregnation liquid is not particularly limited as long as it can maintain the dispersibility of the microfibril cellulose and can dissolve the organic polymer and the coupling agent, A mixed solvent of water or water containing an organic solvent compatible with water, or an organic solvent compatible with water is preferable because it is less likely to impair the dispersibility of microfibril cellulose. Examples of such organic solvents compatible with water include methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, dioxane, acetone, methyl ethyl ketone, tetrahydrofuran, glycerin, neopentyl glycol, methyl cellosolve, Examples include ethyl cellosolve, pentaerythritol, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, and the like. These may be used alone or in combination of two or more. In the case where the organic polymer and / or the coupling agent are impregnated in a stepwise manner, the dispersion medium of the impregnating liquid is not necessarily the same, and the organic polymer or the coupling agent is dissolved or dissolved. An appropriate selection may be made in consideration of dispersibility.

  The method for impregnating the sheet with the binder can be performed by immersing the sheet obtained above in the binder impregnating liquid, or by impregnating the sheet by spraying the binder impregnating liquid with a spray or the like. . In the dipping method, the impregnation time is preferably 1 second to 10 days, but is not particularly limited.

In the dipping method, the impregnation time is not particularly limited as long as the binder impregnating solution is absorbed and diffused into the sheet and the binder component can sufficiently permeate, but it is preferably 1 second to 10 days. Just choose.
Further, in the impregnation, it is also included in the present invention to appropriately use a method for improving impregnation properties such as heating, pressurization, and reduced pressure.

Another example of a preferred embodiment of the method for impregnating the binder impregnating liquid is that the sheet obtained above is frozen to freeze the molecular structure, freeze-dried to remove the dispersion medium, and then the binder impregnating liquid. It is the method of immersing in.
Further, as another preferred embodiment, a binder and / or a solvent of a binder impregnation liquid is added to the microfibril cellulose dispersion liquid and mixed as necessary, as long as the dispersibility of the microfibril cellulose is not impaired. As a dispersion, a microfibril cellulose is pre-impregnated and impregnated with a binder, and then a sheet is produced. Otherwise, the other preferred embodiments may be formed without performing the same steps or unnecessary steps. .

  When the binder is used, the sheet may be impregnated with the binder, and then a drying process may be performed as necessary. As the conditions, a part or all of the solvent of the binder impregnation liquid is volatilized and evaporated, and when impregnated with a binder resin such as a thermosetting resin as a binder, the reaction is partially advanced, What is necessary is just to select suitably from the conditions etc. which make a semi-hardened state prepreg. The drying temperature is preferably 20 ° C. to 200 ° C., and a method that can be applied when a person skilled in the art manufactures a prepreg or the like of a laminated board can be employed.

  In the sheet that has undergone the plurality of steps, a preheating step can be carried out after arranging the sheet in a state where the sheet can be formed in a single layer or a plurality of layers. In particular, when a plurality of sheets are laminated without using a binder, it is preferable to perform preheating in a state where the sheets are pressure-bonded to fix the molecular structure of the sheet interface, and the temperature in this case is 20 The temperature is preferably from 200 ° C to 200 ° C, more preferably from 20 ° C to 150 ° C. The pressure is preferably from 0.01 to 200 MPa, more preferably from 0.1 to 100 MPa.

  Next, the step of laminating a single sheet or a plurality of sheets obtained as described above and forming a molded body by heating, pressing, or both heating and pressing will be described.

The number of laminated sheets is preferably 1 or more and 1000 or less, but may be appropriately adjusted so that the thickness of the molded product becomes a desired one.
Examples of the heating method include a method using a heating plate such as a hot plate, a heating device such as an oven and a vacuum oven, the method of applying pressure includes a cold press method, and the method of heating and pressing includes a hot press method.
About the processing temperature by the said oven, 20-200 degreeC is preferable, More preferably, it is 70-180 degreeC. When the value is lower than the lower limit, the remaining dispersion medium and solvent are sufficiently removed. On the other hand, when the value is lower than the upper limit, the microfibril cellulose is not easily decomposed, which is preferable.

  The cold press is a method of applying pressure without heating, and the pressure in the cold press is preferably 0.01 to 200 MPa, more preferably 0.1 to 100 MPa. When the pressure is not less than the lower limit, adhesion between cellulose microfibrils and between sheets is sufficient, and when it is not more than the upper limit, the resulting microfibril cellulose is not easily damaged. Moreover, although temperature is not specifically limited, Room temperature is preferable for the convenience of operation. The time for pressurization is not limited, and for example, 5 seconds to 24 hours, preferably 30 seconds to 12 hours can be exemplified, but can be appropriately selected depending on the intended material.

  The hot press is a method of applying pressure while heating, but the conditions for heating and pressurizing vary depending on the intended use, but conditions under which the microfibril cellulose does not deteriorate, for example, the pressure is preferably 0.1 to 500 MPa. More preferably, it is 1 to 250 MPa. The temperature is preferably 20 to 200 ° C, preferably 70 to 180 ° C. Although the time of heating and pressurization is not particularly limited, for example, 5 seconds to 24 hours, preferably 30 seconds to 12 hours can be exemplified, but can be appropriately selected depending on the intended material.

  In the present invention, the molded body may be formed in a vacuum, and the degree of vacuum at this time is preferably 100,000 Pa or less, and more preferably 10,000 Pa or less.

  The present invention has a feature that can stably and efficiently produce a molded product containing microfibril cellulose having high strength and little strength variation, but a large-scale molded product is applied to the papermaking process of the paper industry. In addition, a sheet made of microfibril cellulose is continuously produced, and it is obtained by forming a laminate by heating or pressurizing or both heating and pressurizing one or more layers. Large-area molded products can also be produced efficiently.

The preferred embodiment of the method for producing a molded article containing the microfibril cellulose of the present invention has been described above.
Since the molded article of the present invention can stably and efficiently produce a molded article containing microfibril cellulose having high strength and little strength variation, it can be used for automobile parts such as interior parts such as automobile outer panels and dashboards, railways, and airplanes. Parts for transportation equipment such as ships, sashes in houses and offices, building materials such as wall boards and floor boards, structural members such as reinforcing bars in pillars or reinforced concrete, electronic parts such as electronic circuit boards, personal computers, mobile phones, etc. Household appliances (housing), office equipment such as stationery, furniture, household items such as disposable containers, sports equipment, small items used in the home such as toys, signboards, signs, signs and other outdoor installations, bulletproof shields, bulletproof vests Shock absorbers such as helmets, protective equipment such as helmets, artificial bones, medical supplies, abrasives, sound barriers, protective walls, vibration absorbers, tools, plates Mechanical parts, such as, musical instruments, can be used in packaging materials. In addition, taking advantage of the biodegradability of microfibril cellulose, horticultural structures, rivers, renovation structures such as rivers, installations that are not scheduled to be collected in forests, mountains, deserts, and ice, buried in soil, buried in water It can also be used for things.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this.

(Production Example 1)
It is obtained by adding 800 parts by weight of water to 100 parts by weight of wood pulp chips that have been cut to about 5 mm, and performing a refining treatment 10 times at 1800 rotations with a stone mill grinder (Supermass colloider manufactured by Masuyuki Sangyo Co., Ltd.). Water was further added to the resulting dispersion to prepare a 6% by weight microfibril cellulosic dispersion. As a result of observing this dispersion with a microscope, the average fiber thickness of microfibril cellulose was 0.8 μm and the average fiber length was 0.3 mm.

(Production Example 2)
It is obtained by adding 2500 parts by weight of water to 100 parts by weight of wood pulp chips cut to about 5 mm, and performing a 30-minute refining process at 1800 revolutions with a stone mill grinder (Supermass colloider manufactured by Masuyuki Sangyo Co., Ltd.). Water was further added to the resulting dispersion to prepare a 3% by weight microfibril cellulosic dispersion. As a result of observing this dispersion with a microscope, the average fiber thickness of microfibril cellulose was 0.5 μm and the average fiber length was 0.1 mm.

(Production Example 3)
100% by weight of a resole resin (Sumilite Resin PR-961A manufactured by Sumitomo Bakelite Co., Ltd., 65% non-volatile content, 12% free phenol, 5% free formaldehyde) is added to 100 parts by weight of the dispersion of Production Example 2. Part of the mixture was added to prepare a dispersion.

Example 1
The dispersion of Production Example 1 was put into a filter folder with a tank (manufactured by Advantech Toyo Co., Ltd., model: KST-293-10), cast on filter paper, and filtered under pressure at 0.3 MPa to produce a sheet. did. Thereafter, the sheet was dried at 100 ° C. for 1 hour to obtain a sheet having a thickness of 1200 μm and a circle having a diameter of 26 cm and a dispersion medium content of 60% by weight. A total of two sheets were produced by the same method, these two sheets were laminated on a stainless steel plate, and further, a stainless steel plate was placed on the laminated sheet, and a preliminary press was performed at 105 ° C., 10 MPa for 30 minutes. Heated. Subsequently, hot press molding was performed at 150 ° C. for 2 hours to produce a plate-shaped molded product having a thickness of 1.9 mm. The bending strength of the obtained molded product was n = 10, an average of 260 MPa, a maximum value of 270 MPa, and a minimum value of 250 MPa. The bending strength was measured with a UCT-30T type Tensilon manufactured by Orientec Co., Ltd. under a distance between fulcrums of 36 mm, a crosshead speed of 1 mm / min, 25 ° C., and a relative humidity of 60% in accordance with JIS K 7171.

(Examples 2 and 3)
In Example 1, sheets were produced in the same manner as in Example 1 except that the dispersion prepared in Production Example 2 was used instead of the dispersion in Production Example 1. Details of conditions and evaluation results are shown in Table 2.

Example 4
The dispersion prepared in Production Example 2 was cast on a Teflon (registered trademark) plate and heat-treated in an oven at 130 ° C. for 1 hour. The obtained sheet was a sheet having a thickness of 10 μm, a 30 cm square, and a dispersion medium content of 50% by weight. In the same manner, 225 sheets were prepared, laminated on a stainless steel plate, further placed on the laminated sheet, and preheated with a press machine at 105 ° C., 10 MPa for 30 minutes. Subsequently, hot press molding was performed at 150 ° C. and 100 MPa for 2 hours to produce a plate-shaped molded product having a thickness of 1.9 mm. The bending strength of the obtained molded product was n = 10, the average was 280 MPa, the maximum value was 285 MPa, and the minimum value was 270 MPa.

(Example 5)
A sheet was prepared in the same manner as in Example 2, and the sheet was made of 10 of resole resin (Sumilite Resin PR-961A manufactured by Sumitomo Bakelite Co., Ltd., 65% non-volatile content, 12% free phenol, 5% free formaldehyde). It was immersed in a weight% aqueous solution for 1 hour at room temperature and impregnated, and after applying the binder resin, drying was performed at 100 ° C. for 15 minutes. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, an average of 430 MPa, a maximum value of 440 MPa, and a minimum value of 425 MPa.

(Example 6)
The dispersion of Production Example 3 was put into a filter folder with a tank, cast on filter paper, and filtered under pressure at 0.3 MPa to prepare a sheet. Thereafter, the sheet was dried at 100 ° C. for 15 minutes to obtain a sheet having a sheet thickness of 700 μm and a diameter of 26 cm and a dispersion medium content of 75% by weight. A total of four sheets are produced by the same method, these four sheets are laminated on a stainless steel plate, and further, a stainless steel plate is placed on the laminated sheet, and a preliminary press is performed at 90 ° C., 10 MPa for 30 minutes. Heated. Subsequently, hot press molding was performed at 150 ° C. and 100 MPa for 2 hours to produce a plate-shaped molded product having a thickness of 2.1 mm. The bending strength of the obtained molded product was n = 10, an average of 420 MPa, a maximum value of 430 MPa, and a minimum value of 410 MPa.

(Example 7)
A sheet having a sheet thickness of 800 μm and a diameter of 26 cm and a dispersion medium content of 50% by weight was produced in the same manner as in Example 2. This sheet was freeze-dried at −15 ° C. and a vacuum degree of 200 Pa for 10 hours, and 10 of resole resin (Sumilite Resin PR-961A manufactured by Sumitomo Bakelite Co., Ltd., nonvolatile content 65%, free phenol 12%, free formaldehyde 5%). It was immersed in a weight% aqueous solution for 1 hour at room temperature and impregnated, and after applying the binder resin, drying was performed at 100 ° C. for 15 minutes. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 460 MPa, the maximum value was 475 MPa, and the minimum value was 455 MPa.

(Example 8)
A sheet was prepared in the same manner as in Example 2, and 100 parts by weight of epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., Epicoat 828) and 0.05 part by weight of 2-methylimidazole were separately prepared. Then, it was immersed in a 10% by weight solution dissolved in dimethylformamide (DMF) at room temperature for 1 hour and impregnated, followed by drying at 150 ° C. for 10 minutes after applying the binder resin. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 340 MPa, the maximum value was 350 MPa, and the minimum value was 330 MPa.

Example 9
Phenyltrimethoxysilane was sequentially added to and mixed with a 1% by weight acetic acid aqueous solution at room temperature for 30 minutes, and stirred for another 2 hours after the addition was completed, thereby preparing a 2% by weight phenyltrimethoxysilane hydrolyzate aqueous solution. By diluting a resol resin (Sumitite Bakelite Co., Ltd. Sumitrite Resin PR-961A, 65% non-volatile content, 12% free phenol, 5% free formaldehyde) with the prepared aqueous solution of phenyltrimethoxysilane hydrolyzate, A mixed solution having a methoxysilane content of 1% by weight and a resol resin 10% by weight aqueous solution was prepared. The mixed solution was impregnated with a sheet produced in the same manner as in Example 2 at room temperature for 1 hour, and dried after applying the binder at 100 ° C. for 15 minutes. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 515 MPa, the maximum value was 525 MPa, and the minimum value was 505 MPa.

(Examples 10 and 11)
In Example 9, a molded article was produced in the same manner as in Example 9 except that the amount of phenyltrimethoxysilane was changed. Details of the conditions and evaluation results are shown in Tables 2 and 3.
The bending strength of the molded product obtained in Example 10 was n = 10, an average of 535 MPa, a maximum value of 540 MPa, and a minimum value of 530 MPa.
The bending strength of the molded product obtained in Example 11 was n = 10, the average was 505 MPa, the maximum value was 515 MPa, and the minimum value was 495 MPa.

Example 12
In Example 9, a molded article was produced in the same manner as in Example 9 except that phenyltrimethoxysilane was replaced with tetraethoxysilane. Details of conditions and evaluation results are shown in Table 3. The bending strength of the obtained molded product was n = 10, an average of 515 MPa, a maximum value of 520 MPa, and a minimum value of 510 MPa.

(Example 13)
Aminopropylsilanetriol 22-25% aqueous solution (manufactured by Gelest) was diluted with water to give a 2% by weight aqueous solution, and a sheet produced by the same method as in Example 2 was immersed at room temperature for 1 hour. After impregnation, it was air-dried at room temperature for 1 day. Further, a resol resin (Sumilite Resin PR-961A manufactured by Sumitomo Bakelite Co., Ltd., non-volatile content 65%, free phenol 12%, free formaldehyde 5%) was diluted into a 10% by weight aqueous solution, and this was air-dried first. The placed sheet was immersed and impregnated at room temperature for 1 hour. After applying the binder, drying was performed at 100 ° C. for 15 minutes. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 540 MPa, the maximum value was 550 MPa, and the minimum value was 530 MPa.

(Example 14)
After the microfibril cellulose obtained by the same method as in Production Example 2 was put into a cloth and squeezed, this was dispersed in methyl alcohol, and the process of squeezing with the cloth was repeated three times. The obtained microfibril cellulose was converted into methyl alcohol. A methyl alcohol dispersion was prepared by dispersing. After this was filtered by the same method as in Example 1, the sheet was dried at 40 ° C. for 1 hour to obtain a sheet having a thickness of 900 μm and a diameter of 26 cm and a dispersion medium content of 55% by weight. Next, the obtained sheet was impregnated by being immersed in a 2 wt% methyl alcohol solution obtained by diluting 3-glycidoxypropyltrimethoxysilane with methyl alcohol at room temperature for 1 hour, and then air-dried at room temperature for 8 hours. I let you. Next, after resol resin (Sumitomo Bakelite Co., Ltd. Sumilite Resin PR-961A, non-volatile content 65%, free phenol 12%, free formaldehyde 5%) under reduced pressure at 100 ° C. until 2500 Pa, methyl alcohol was added. The solvent was replaced so that a methyl alcohol solution having a nonvolatile content of 10% was obtained. This was impregnated by immersing the previously air-dried sheet at room temperature for 1 hour. Subsequently, after binder application | coating, drying was performed for 15 minutes at 100 degreeC. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 560 MPa, the maximum value was 575 MPa, and the minimum value was 550 MPa.

(Example 15)
A molded article was produced in the same manner as in Example 14, except that 3-glycidoxypropyltrimethoxysilane was replaced with 3-methacryloxypropylmethyldimethoxysilane in Example 14. Details of conditions and evaluation results are shown in Table 3.
The bending strength of the obtained molded product was n = 10, an average of 520 MPa, a maximum value of 525 MPa, and a minimum value of 515 MPa.

(Example 16)
In Example 14, a molded article was produced in the same manner as in Example 14, except that 3-glycidoxypropyltrimethoxysilane was replaced with tetraethoxytitanium. Details of conditions and evaluation results are shown in Table 3.
The bending strength of the obtained molded product was n = 10, the average was 535 MPa, the maximum value was 540 MPa, and the minimum value was 525 MPa.

(Example 17)
Phenyltrimethoxysilane was sequentially added to a 1% by weight acetic acid aqueous solution at room temperature over 30 minutes, followed by further stirring for 2 hours to prepare a 2% by weight phenyltrimethoxysilane hydrolyzate aqueous solution. A sheet produced by the same method as in Example 2 was immersed and impregnated at room temperature for 1 hour, and dried after applying the binder at 100 ° C. for 15 minutes. Three similar sheets are prepared, laminated on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. and 100 MPa for 2 hours with a press machine. A 2 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, the average was 415 MPa, the maximum value was 425 MPa, and the minimum value was 405 MPa.

(Comparative Example 1)
The dispersion of Production Example 2 was put into a filter folder with a tank, cast on filter paper, and filtered under pressure at 0.3 MPa to prepare a sheet. Thereafter, the sheet was dried at 100 ° C. for 1 hour to obtain a sheet having a sheet thickness of 3000 μm and a diameter of 26 cm and a dispersion medium content of 40% by weight. This sheet is placed on a stainless steel plate, and a stainless steel plate is placed on the laminated sheet, and hot press molding is performed at 150 ° C. for 2 hours with a press machine to form a plate having a thickness of 2.6 mm. An article was made. The bending strength of the obtained molded product was n = 10, an average of 220 MPa, a maximum value of 250 MPa, and a minimum value of 200 MPa.

(Comparative Example 2)
The dispersion of Production Example 2 was put into a filter folder with a tank, cast on filter paper, and filtered under pressure at 0.3 MPa to prepare a sheet. Thereafter, the sheet was dried at 100 ° C. for 1 hour to obtain a sheet having a thickness of 300 μm and a diameter of 26 cm, and a dispersion medium content of 40% by weight. This sheet was impregnated with a 10% by weight solution of a resole resin (Sumitite Resin PR-961A manufactured by Sumitomo Bakelite Co., Ltd., non-volatile content 65%, free phenol 12%, free formaldehyde 5%) at room temperature for 1 hour. After resin application, drying was performed at 100 ° C. for 15 minutes. Ten similar sheets are prepared, laminated on a stainless steel plate, and further, a stainless steel plate is placed on the laminated sheet, and hot press molding is performed with a press machine at 150 ° C. and 100 MPa for 2 hours. A 2.6 mm plate-shaped molded product was produced. The bending strength of the obtained molded product was n = 10, an average of 370 MPa, a maximum value of 400 MPa, and a minimum value of 350 MPa.

Tables 2 and 3 show the results of measuring the bending strength, water absorption, hardness change, and thickness change of the test pieces obtained in the above Examples and Comparative Examples.
Here, the water absorption is the difference between the weight after immersion and the weight before immersion when the test piece of the predetermined size obtained above is immersed in water at 25 ° C. for 24 hours. It is a value obtained by multiplying the value divided by the weight of 100 by 100.
The change in hardness is a value obtained by multiplying the value obtained by dividing the hardness after immersion by the hardness before immersion when the test piece of the predetermined size obtained above is immersed in water at 25 ° C. for 24 hours. . The hardness is a value measured by a durometer rubber hardness meter D type manufactured by Kobunshi Keiki Co., Ltd.
The thickness change is a value obtained by multiplying the value obtained by dividing the thickness after immersion by the thickness before immersion when the test piece of the predetermined size obtained above is immersed in water at 25 ° C. for 24 hours. .

In the examples of the present invention, all have the characteristics of high bending strength and small variation in strength, but Comparative Example 1 has no binder and has a sheet thickness of more than 1500 μm, 3000 μm, and a dispersion medium content of 45% by weight. The absolute value and the variation of the bending strength do not reach the embodiment of the present invention. Further, Comparative Example 2 is an example in which the resol resin is used and the dispersion medium content is 40% by weight lower than 45% by weight, and the absolute value and variation of the bending strength are also examples of using the resole resin of the present invention. It is clear that this is less than 7.
Moreover, in Examples 9-16 which impregnated the binder resin which is this invention, a coupling agent, and the hydrolyzate of this coupling agent, it is much more than Example 5, 7, 8 which impregnated only binder resin. It is clear that the water absorption rate is controlled and the change in hardness and the amount of change in thickness are remarkably suppressed, so that the water resistance is high and the absolute value and variation of the bending strength are excellent.

  Since the molded product containing the microfibril cellulose of the present invention has high strength and little strength variation, it is an automobile part such as an interior of a car outer panel and a dashboard, a part of a transportation device such as a railway, an airplane, a ship, Building materials such as sashes, walls and floorboards in houses and offices, structural members such as columns or reinforcing bars in reinforced concrete, electronic parts such as electronic circuit boards, housings for home appliances such as personal computers and mobile phones, stationery Office equipment such as furniture, household items such as disposable containers, sports equipment, toys and other small items used in the home, signboards, signs and signs, outdoor installations such as bulletproof shields, bulletproof vests, shock absorbers, and helmets Tools, artificial bones, medical supplies, abrasives, sound barriers, protective walls, vibration absorbing members, tools, leaf springs and other machine parts, musical instruments, packing materials, etc. It can be used for. In addition, taking advantage of the biodegradability of microfibril cellulose, horticultural structures, rivers, renovation structures such as rivers, installations that are not scheduled to be collected in forests, mountains, deserts, and ice, buried in soil, buried in water It is also useful for things.

Claims (9)

A method for producing a molded article by casting a dispersion containing microfibril cellulose and a dispersion medium,
Using the dispersion, forming a sheet having a thickness of 1 μm or more and 1500 μm or less and a dispersion medium content of 45% by weight or more and 75% by weight or less;
A step of forming a molded body by heating, pressurizing or both heating and pressurizing a laminate obtained by laminating a single sheet or a plurality of sheets;
A method for producing a molded article comprising:   The method for producing a molded product according to claim 1, wherein the sheet forming the molded body is impregnated with a binder resin.   The method for producing a molded product according to claim 2, wherein the binder resin contains a thermosetting resin.   The method for producing a molded article according to any one of claims 1 to 3, wherein the sheet forming the molded body is impregnated with a coupling agent and / or a hydrolyzate of the coupling agent.   The method for producing a molded article according to any one of claims 1 to 4, wherein the sheet is formed by a process including filtration.   The method for producing a molded article according to any one of claims 1 to 5, wherein the dispersion medium is removed by freeze-drying after the sheet is formed.   The said thermosetting resin is a manufacturing method of the molded article of Claim 3 which is a phenol resin.   The method for producing a molded article according to claim 4, wherein the sheet forming the molded article is impregnated with a binder resin, a coupling agent and / or a hydrolyzate of the coupling agent.   The molded article containing microfibril cellulose obtained by the manufacturing method of the molded article of any one of Claims 1-8.