JP2019099645A - Resin molded body, and coating agent consisting of composition for forming resin molded body - Google Patents

Abstract

To provide a resin molded body having moisture permeability and water permeability even though non-porosity.SOLUTION: A resin molded body consists of a composition containing a synthetic resin and a hydrophilic fiber, in which at least a part of the synthetic is an aggregate by aggregating a plurality of resin particles, forms a sea-island structure in which the synthetic resin and the hydrophilic fiber are phase separated each other, moisture vapor transmission rate is 1×10g/mday t 1×10g/mday, content of the hydrophilic fibber is in a range of 5 pts.wt. to 200 pts.wt. based on 100 pts.wt. of the synthetic resin, average fiber width of the hydrophilic fiber is in a range of 3 nm to 200 nm, having moisture permeability and water permeability, and having non-porosity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin molded product and a coating agent comprising the composition for forming a resin molded product.

  Films and sheets that require moisture permeability and water permeability are used in various fields. For example, there is a water-absorbent sheet for fresh food. Fresh food such as fresh fish and fresh meat exudes water called drip in the process of falling in freshness. This exudation reduces the commercial value as evidence of a loss of freshness, and leaving drips causes further loss of freshness, so many fresh foods are covered with a sheet that absorbs drips. The water-absorbent sheet is required to maintain a proper moisturizing state without absorbing too much water, and to have a good appearance and hygiene in order to directly touch fresh food.

  Alternatively, there are lining curtains used in agricultural greenhouse houses. In the case of lining curtains, the main purpose is to improve the heat retention in the house and reduce the heat energy. In addition, the moisture in the house can be absorbed quickly to prevent excessive humidity, thereby suppressing mold and the like due to humidity, and aggregation water due to humidity does not cause problems in appearance and growth of crops by dripping water. The role of absorbing and sinking water is required. Furthermore, a high light transmittance is required so that the crop can sufficiently capture solar energy.

  Alternatively, a moisture permeable or permeable film is also required for a purification system for purifying water. When cultivating plants by using polluted water such as inorganic salts and radioactive substances as a water source, it is possible to remove substances harmful to plants with a film, purify water at low cost and efficiently, and supply them to plants Desired. In this case, a method of selectively transmitting water vapor and selectively transmitting water vapor, and a method of selectively transmitting only water purified by contacting contaminated water with a film may be employed. In these cases, it is further required to keep the contaminants in the film without flowing out again, and to control the rate of recovery of the purified water according to the situation.

  In addition to the above applications, the required performance and required added value vary widely from the life / environment field such as production of concentrated juice and artificial dialysis to the energy field such as a fuel cell separator.

  In recent years, the use of environmentally-friendly materials (biomass materials) has attracted attention due to global warming due to exhaustion of resources and increase in carbon dioxide concentration in the atmosphere, environmental pollution, waste problems, and the like. This biomass material is characterized in that the amount of fossil resources used at the time of production is small, and it can be treated with low energy at the time of disposal and the emission of carbon dioxide is low. Among biomass materials, cellulose, which accounts for about half of its production, is expected to be effectively used because of its large production. Furthermore, cellulose has high strength, high elastic modulus, very low thermal expansion coefficient, and does not have a glass transition point and exhibits a high thermal decomposition temperature of 230 degrees with respect to heat resistance. On the other hand, it can not be said that cellulose is frequently used as a material for its large amount of production. One of the reasons is the low solubility and dispersibility in aqueous and non-aqueous solvents. Cellulose is a homopolysaccharide in which D-glucopyranose, which is a 6-membered ring of glucose, is β- (1 → 4) glucosidically linked, and has a hydroxyl group at the C2 position, the C3 position, and the C6 position. Therefore, a strong hydrogen bond is formed in the molecule and between the molecules, and it does not dissolve in water or general solvents.

  However, when the cellulose is treated using an oxidation reaction catalyzed by an N-oxyl compound such as 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO), the degree of treatment is adjusted. A mild dispersion process in water gives a homogeneous dispersion. At this time, cellulose is disintegrated to a microfibril level, and exists as a cellulose fiber dispersion in which the fiber width is dispersed in several nm to several hundreds nm. Furthermore, the TEMPO oxidation reaction is extremely adaptable to the environment of the reaction process, for example, the reaction is completed in a short time under mild conditions of normal temperature and normal pressure using only water as a reaction solvent without using an organic solvent.

  The mechanism by which the oxidized cellulose obtained by the TEMPO oxidation reaction is dispersed to the nano level by light mechanical processing is known as follows. First, the hydroxyl group at the C6 position of the surface of the microfibrils of cellulose is selectively oxidized by the oxidation reaction, and the carboxyl group is introduced via the aldehyde group. Then, this carboxyl group is repelled as an anion to exhibit an osmotic pressure effect in the dispersion medium. As a result, nano-order microfibrils are likely to be isolated, and a homogeneous cellulose fiber dispersion can be obtained. Furthermore, the modified cellulose having different properties can be obtained by forming various salts having cationicity as a counter ion by utilizing the electrostatic action of the carboxyl group introduced into cellulose. In this treatment, since the crystallinity of the raw material cellulose can be maintained without breaking it, it has high physical properties.

  As described above, cellulose that can be used as a nanodispersion, liquid state, or modified body has a low environmental load, and further has high physical properties, so that TEMPO oxidation treatment and oxide are new uses of cellulose It is expected as a form.

  One example that is actively developed for industrial use is compounding with a resin. It is an object of the present invention to increase the functionality of a resin utilizing light weight, high strength, high elastic modulus, low linear thermal expansion coefficient, and high heat resistance of cellulose by mixing a cellulose dispersion in the resin. The dispersibility of the cellulose fiber in resin is mentioned as an important element of the functional improvement in this case. It is known that when the cellulose fibers are unevenly distributed or aggregated, the effect of the cellulose fiber mixing is significantly reduced.

  Therefore, in order to enhance the affinity with a resin having hydrophobicity and improve the dispersibility, a method of forming a composite using an aqueous emulsion as a resin has been developed. In the case of an aqueous emulsion, water having high compatibility with cellulose fibers is mainly used as a dispersion medium, and even high molecular weight particles are dispersed as fine resin particles in the dispersion medium. For this reason, the thickening at the time of mixing with a cellulose fiber can be suppressed, and handling becomes simple. On the other hand, the mixture of cellulose fiber and aqueous emulsion has a low solid concentration, and water having a high boiling point is used as a dispersion medium. Therefore, much energy and time are required to remove the dispersion medium. As a result, the productivity of the material using cellulose was generally low.

  As a technique for improving the productivity of materials using cellulose, for example, there is one disclosed in Patent Document 1. This patent document describes a technique of gelling a mixture of an aqueous emulsion and cellulose fibers with a cellulose coagulant, filtering the mixture on a porous substrate and drying it.

Patent No. 5747818 gazette

  As described above, there are techniques for improving the productivity of materials using cellulose, which have been disclosed so far, but non-porous, moisture-permeable and water-permeable using synthetic resin and cellulose fiber There has been no disclosure of technology relating to sheets and films having properties.

  The present invention provides a resin molded body which is nonporous and has moisture permeability and water permeability.

In order to solve the above-mentioned subject, a resin molding concerning one mode of the present invention consists of a composition containing a synthetic resin and hydrophilic textiles at least, and at least one copy of a synthetic resin has a plurality of resin particles carrying out aggregation. The synthetic resin and the hydrophilic fiber form a sea-island structure in which the synthetic resin and the hydrophilic fiber are separated from each other, and the moisture permeability of the resin molded product is 1 × 10 ² g / m ² · day or more 1 × 10 ⁴ g / M ² · day or less, the content of the hydrophilic fiber is in the range of 5 parts by weight to 200 parts by weight with respect to 100 parts by weight of the synthetic resin, the average fiber width of the hydrophilic fiber is 3 nm or more It is characterized by being in the range of 200 nm or less, having moisture permeability and water permeability, and being non-porous.

  Moreover, the coating agent which consists of a composition for resin molded object formation which concerns on 1 aspect of this invention contains a synthetic resin and hydrophilic fiber at least, and content of a hydrophilic fiber is 100 weight part of synthetic resins with respect to a synthetic resin. And the average fiber width of the hydrophilic fibers is in the range of 3 nm to 200 nm.

  According to each aspect of the present invention, it is possible to provide a non-porous resin molded body having moisture permeability and water permeability.

It is a figure showing typically a part of resin molding concerning an embodiment of the present invention. It is the figure which observed a part of resin molding concerning embodiment of this invention by AFM (atomic force microscope). It is a figure which shows the resin molding in a permeability test.

  Hereinafter, an embodiment of the present invention will be described. In addition, this invention is not limited to the following embodiment, A various deformation | transformation is possible unless it deviates from the meaning of this invention. Here, the drawings are schematic. In addition, the embodiments shown below illustrate the configuration for embodying the technical idea of the present invention, and the technical idea of the present invention includes the following for the material, the shape, the structure, and the like. It does not identify. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

  FIG. 1 is a view schematically showing a portion of a resin molded body according to an embodiment of the present invention, FIG. 1 (a) is a front view schematically showing a portion of the resin molded body, and FIG. 1 (b) is a resin It is a cross-sectional schematic diagram of a part of molded object. As shown in FIG. 1, a resin molded body 1 according to the present embodiment is composed of a synthetic resin 2 and a hydrophilic fiber 3. The synthetic resin 2 is formed as an aggregate in which a plurality of resin particles 4 are at least partially aggregated, and the aggregates are partially bound and integrated while the hydrophilic fiber 3 covers the surface of the aggregate. As it exists. Thus, the synthetic resin region and the hydrophilic fiber region are in a continuous non-porous body while being microscopically phase-separated.

  The term "non-porous" as used herein refers to the absence of these voids relative to the porosity where the voids of the submicron size, micron size or more physically exist continuously or discontinuously in the resin molded body. It shows the state. In the case of a porous body, in the case of a water-permeable material, water permeates through the continuously existing pores. By using a water repellent material or reducing the void size, the surface tension of water can not pass through the void due to the surface tension of the water, and only water vapor can be transmitted, and it is designed as a material having both water repellency and moisture permeability. You can also. On the other hand, in the case of the moisture-permeable film or the water-permeable film using the non-porous resin molded body 1 according to the present embodiment, water or water vapor condenses on the material surface and then dissolves inside the material to drive the concentration gradient. Water and water vapor can be transmitted by diffusion and diffusion to lower concentrations.

  Here, in the resin molded body 1 according to the present embodiment, the synthetic resin 2 with high hydrophobicity and the hydrophilic fiber 3 form a phase separation structure microscopically referred to as a sea-island structure. To express the effect of the present invention by covering the aggregate of the synthetic resin 2 to be "island" with the hydrophilic fiber to be "sea" and transmitting water and water vapor through the hydrophilic fiber to "sea" region Make it possible.

<Synthetic resin>
The resin molded body 1 according to the present embodiment contains a synthetic resin 2 composed of an aqueous resin dispersion. Here, the aqueous resin dispersion may be referred to as an aqueous dispersion, an aqueous emulsion, or an aqueous dispersion or an aqueous emulsion, and in the form of a high molecular weight resin dispersed in an aqueous dispersion medium containing water. It shall be contained in the aqueous resin dispersion concerning this embodiment. In addition, the expression synthetic resin is used as an expression to be paired with the hydrophilic fiber.

  This aqueous resin dispersion is one in which the polymer is dispersed in a particle size of submicron to several microns, using water as a main dispersion medium. By volatilizing these dispersion media, the polymers are deformed and fused together to form a continuous structure.

  The aqueous resin dispersion has a design freedom higher than that of a water-soluble monomer or a water-soluble oligomer as a resin, and thus has an advantage of being able to select a material according to a target performance or function. Furthermore, the dispersion stability in the dispersion medium is imparted by the addition of an emulsifier or the introduction of a hydrophilic group to the resin, but the synthetic resin itself is hydrophobic and has high water resistance and moisture resistance. Therefore, it is difficult to be influenced by the external humidity environment, and there is no noticeable deformation even when the moisture content is changed as a resin molded product, and it is possible to maintain the structure as a resin molded product.

  Further, in the form of the aqueous resin dispersion, although the degree of polymerization of the synthetic resin is high, although fine particles are formed independently of one another, the viscosity as the coating liquid is low. Therefore, even if the hydrophilic fiber 3 which is a constituent material of the present embodiment has a high viscosity, it is possible to obtain good mixability.

  As described above, the aqueous resin dispersion in the present embodiment is one in which the resin particles 4 are dispersed in an aqueous dispersion medium containing water. And the resin particle 4 has a distribution in particle diameter to some extent. At the coating liquid stage before molding of the resin molded body 1 and at the time of molding, the interaction with the hydrophilic fiber 3 and other components to be mixed, the melting temperature, etc. affect the aggregation form of the resin particles 4 at the time of deformation and fusion. . For this reason, the particle diameter of the resin particle 4 does not correspond to the factor that uniquely determines the size of the hydrophobic region made of the synthetic resin 2 in the structure of the resin molded body 1. However, when the particle diameter of the resin particle 4 is too small, the interaction with the hydrophilic fiber 3 and other components to be mixed is likely to be large due to the electrical action of the surface of the resin particle 4 because the specific surface area is large. It becomes difficult for fusion of the resin particles 4 to occur. As a result, the size of the hydrophobic region made of the synthetic resin 2 is reduced. In this case, since a large number of interfaces exist in the hydrophobic region formed of the synthetic resin 2 and the hydrophilic region formed of the hydrophilic fibers 3, light is scattered by the interface regardless of the water content, and the haze of the resin molded body 1 rises. Resulting in. On the other hand, when the particle diameter of the resin particle 4 is too large, it becomes difficult to uniformly disperse the synthetic resin 2 and other components including the hydrophilic fiber 3 at the time of molding the resin molded body 1. Therefore, the particle diameter of the resin particle 4 is preferably in the range of 0.01 μm or more and 10 μm or less, which is an appropriate size for the purpose of the present embodiment. In addition, FIG. 2 is a figure which observed a part of resin molding based on this embodiment by AFM (atomic force microscope), and it is expressed that the dimension of the aggregate of the resin particle 4 is 642 nm.

  The aqueous resin dispersion is roughly classified into anionic, cationic and nonionic depending on the ionic property of the surface of the resin particle 4. In the present embodiment, any use is not limited, but when the hydrophilic fiber 3 to be mixed is anionic, mixing of the cationic synthetic resin may inhibit the charge thereof, so the anionic or nonionic property is preferable.

  As the synthetic resin 2, for example, vinyl acetate type, urethane type, acrylic type, styrene type, phenol type, amino type, amide type, polyester type, ethylene type and polyvinyl alcohol type are used. These may be used alone, or may be copolymerized or used in combination of two or more. Alternatively, reactive synthetic resin may be used. In that case, for example, a curing agent, a curing catalyst, a photopolymerization initiator, a chain transfer agent and the like can be used in combination. Here, in order to improve the brittleness caused by the phase separation between the synthetic resin 2 and the hydrophilic fiber 3 constituting the resin molded body 1, it is preferable that the synthetic resin 2 have flexibility, and a urethane type is preferable. More preferable. In the case of urethanes, polyesters, polyethers, polycarbonates and the like have been developed depending on the type of polyol constituting the urethane structure, and any of them can be used.

<Hydrophilic fiber>
As the main role of the hydrophilic fiber 3 used in the present embodiment, the aggregation size of the resin particles 4 of the synthetic resin 2 is adjusted by having appropriate interaction with the synthetic resin 2, or the aggregation interface of the synthetic resin 2 It is to make them bond well. Another role is to secure a hydrophilic region which allows water and water vapor to permeate.

  If the fiber width of the hydrophilic fiber 3 is too large, light is scattered at the interface regardless of the water content, and the haze of the resin molded body 1 rises, and in applications requiring transparency in order to always exhibit white color It can not be used. Therefore, the fiber width of the hydrophilic fiber 3 needs to be sufficiently small. In view of the above, as the hydrophilic fiber 3, any material that at least satisfies the present embodiment in hydrophilicity, ionicity, strength, and fiber width can be used.

  As hydrophilic fiber 3 which fulfills the above-mentioned requirements, for example, cellulose is oxidized by TEMPO oxidation reaction and then mechanical treatment is carried out, and cellulose fiber defibrillated to the nano level can be suitably used. The TEMPO oxidation reaction of cellulose selectively oxidizes the hydroxyl group at the C6 position on the surface of the microfibrils of cellulose to introduce a carboxyl group via an aldehyde group. The charge repulsion of the carboxyl group enables disintegration to the nano level. In addition, since cellulose maintains type I crystals and there is almost no reduction in crystallinity, it is possible to maintain the inherent high elastic modulus of cellulose. In addition, the ionicity can be controlled by the amount of carboxyl groups introduced by TEMPO oxidation reaction conditions. Since the amount of carboxyl groups introduced can be controlled by the TEMPO oxidation reaction conditions, it is possible to adjust the amount of charge derived from the carboxyl groups according to the synthetic resin applied to the resin molded product. In addition, cellulose has three hydroxyl groups per glucose unit, and by having a structure in which a large number of hydroxyl groups are exposed on the surface of microfibrils by being disintegrated to the nano level, it has high hydrophilicity, and hence to water The swelling rate of

  The cellulose fiber used in the present embodiment has an average fiber width of 3 nm or more and 200 nm or less. When the fiber width is larger than 200 nm, the fiber width approaches the wavelength of visible light, which causes the transparency of the resin molded body 1 to be lowered, and the surface area is reduced and the entanglement of fibers is lowered. Cause a decline. In addition, in the case of fibers having a fiber width of less than 3 nm, it is difficult to produce a fiber having excellent mechanical strength and uniformity, so the fiber width is preferably 3 nm or more. Further, as the fiber length is longer, entanglement of the fibers is more likely to occur, so the effect is easily exhibited at a low content. However, if it is too long, the energy required for dispersion and formation increases and dispersion becomes difficult, so the aspect ratio of the fiber width to the fiber length is preferably 100 or more and 1,000 or less.

  Although the measuring method is not specifically limited about the fiber width of the cellulose fiber used by this embodiment, For example, it can measure by the following method. What disperse | distributed cellulose fiber in water so that solid content concentration may be in the range of 0.001 wt% or more and 0.01 wt% or less is developed on mica and naturally dried. Thereafter, the fiber width of the cellulose fiber can be confirmed (measured) by observing the cellulose fiber with a transmission electron microscope.

  Moreover, as a measuring method of the fiber width of the cellulose fiber in the resin molding 1 using things other than a transmission electron microscope, there exists a method of using an atomic force microscope, for example. Specifically, when the phase mode of the atomic force microscope is used, a difference occurs in the phase of the cantilever vibration due to the difference between the characteristics of the cellulose fiber and the synthetic resin 2. Therefore, the cellulose fiber is detected from the phase difference and the width is It can be measured.

  For example, natural cellulose or chemically modified cellulose can be used as a material whose starting material is cellulose used in the present embodiment. Specifically, pulp made from wood such as bleached and unbleached kraft wood pulp, prehydrolyzed kraft wood pulp, sulfite wood pulp, etc., or non-wood pulp such as cotton and bacterial cellulose, and mixtures thereof are used. Can. Also, any of substances obtained by physically or chemically treating them may be used. Preferably, natural cellulose having crystalline Form I is desirable because of its high material properties such as mechanical properties, thermal properties, and chemical resistance.

  As the cellulose used in the present embodiment, for example, a cellulose in which a part of hydroxyl groups of cellulose is substituted by a carboxyl group is used. There is no restriction | limiting in particular as a method of introduce | transducing a carboxyl group into the cellulose used as a raw material, According to the objective, it selects suitably. For example, it can be appropriately selected from methods which are generally known and oxidized to carboxylic acid via aldehyde from hydroxy group. Among them, a method using an N-oxyl compound as a catalyst and using a hypohalite or a halitrite as a co-oxidant is preferable. In particular, using 2,2,6,6-tetramethyl-1-pipedinyloxy radical (TEMPO) as a catalyst and adjusting pH, an oxidant such as sodium hypochlorite, a bromide such as sodium bromide The TEMPO oxidation method of treating with is preferable from the viewpoint of the completeness of reaction in water without using an organic solvent as a reaction solvent, the availability of reagents, cost and stability of the reaction.

  In this TEMPO oxidation method, only the surface of the crystalline cellulose microfibrils is oxidized, and oxidation does not occur inside the crystal, so that the crystal structure can be maintained. Therefore, the product has characteristics of high strength, high modulus of elasticity, low linear thermal expansion coefficient and high heat resistance inherent to cellulose.

(Oxidation treatment by TEMPO oxidation method)
In the present embodiment, the oxidation treatment by the above-described TEMPO oxidation method is performed in the following procedure.

  To the cellulose dispersed in water is added an N-oxyl compound, an oxidizing agent and a co-oxidant to oxidize the cellulose. Sodium hydroxide is added during the oxidation reaction to control the pH in the reaction system to 9-11. The reaction temperature is preferably 0 ° C to 40 ° C. At this time, the hydroxyl group at the C6 position of the cellulose fiber surface is oxidized to a carboxyl group. After stopping the reaction, the reaction product is thoroughly washed with water to recover the oxidized cellulose, which can be used as a constituent material in the present embodiment.

  As the oxidizing agent, for example, hypohalogenous acid or a salt thereof, or a halogenous acid or a salt thereof can be used, and sodium hypochlorite is preferable. In addition, as the co-oxidant, for example, lithium bromide, potassium bromide, sodium bromide and the like can be mentioned, but sodium bromide is preferable in terms of ease of handling.

  The content of the carboxyl group introduced into the cellulose can be adjusted by appropriately setting the reaction conditions. The cellulose into which the carboxyl group is introduced is dispersed in the dispersion medium by the charge repulsion of the carboxyl group in the dispersion step, and therefore, when the content of the carboxyl group in the cellulose is too small, it can be stably dispersed in the dispersion medium Can not. On the other hand, when the content of carboxyl groups in the cellulose is too large, the affinity to the dispersion medium is increased and the water resistance is lowered. From these viewpoints, the content of the carboxyl group introduced into the cellulose is preferably in the range of 0.5 mmol or more and 3.0 mmol or less per 1 g of dry weight of the oxidized cellulose fiber. Furthermore, the inside of the range of 0.8 mmol or more and 2.5 mmol or less per 1 g of dry weights of the oxidation-processed cellulose fiber is more preferable.

  In addition, the amount of carboxyl groups contained in cellulose is calculated by the following method, for example. In a beaker, add 0.2 g of dry oxidized cellulose as dry weight to a beaker, and add 80 ml of deionized water. Thereto, 5 ml of 0.01 M aqueous sodium chloride solution is added, and 0.1 M hydrochloric acid is added while stirring to adjust the whole to pH 2.0. An aqueous solution of 0.1 M sodium hydroxide was injected in 0.05 ml / 30 seconds using an automatic titrator (AUT-701, manufactured by Toa DK Co., Ltd.), and the conductivity and pH value were measured every 30 seconds, pH 11 Continue to measure. The carboxyl group content can be calculated by determining the titration amount of sodium hydroxide from the obtained conductivity curve.

  After the oxidation reaction is stopped, the product is recovered from the reaction solution by filtration. After completion of the reaction, the carboxyl group introduced into the cellulose forms a salt whose counter ion is a metal ion derived from a cation present in the reaction solvent.

As a method of recovering cellulose after oxidation treatment, for example,
(A) A method of filtering off with the carboxyl group forming a salt,
(B) A method in which an acid is added to the reaction solution to adjust the inside of the system to be acidic, and filtered out as a carboxylic acid.
(C) A method of filtering after adding an organic solvent and coagulating,
Can be mentioned. Among them, the method of recovering as (B) carboxylic acid is preferable from the viewpoint of handling property, recovery efficiency and waste liquid treatment. In addition, the method of recovering as (B) carboxylic acid is preferable also from the viewpoint that generation of a by-product can be suppressed if a metal ion is not contained as a counter ion and the substitution efficiency is excellent.

  The metal ion content in the cellulose after the oxidation reaction can be determined by various analysis methods, and for example, it is easily determined by elemental analysis using an electron probe microanalyzer, an EPMA method, or a fluorescent X-ray analysis method. be able to. When collected using the method of filtering off with (A) salt formed, the content of metal ions is 5 wt% or more, whereas when collected by the method of filtering off as (B) carboxylic acid, 1 wt% % Or less.

  Furthermore, the recovered cellulose can be purified by repeated washing, and catalyst and by-products can be removed. At this time, the amount of remaining metal ions and salts can be reduced by repeating the washing with a pure water after washing with a washing solution adjusted to an acidic condition of pH 3 or less using hydrochloric acid or the like.

  By adding a hydroxide containing an alkali metal or an alkaline earth metal to a suspension of cellulose having a carboxyl group introduced, part or all of the carboxyl groups become an alkali metal salt type or an alkaline earth metal salt type Will be replaced. Due to the charge of the carboxyl group, cellulose exhibits an osmotic pressure effect in the dispersion medium, and can be dispersed to the nano order. The amount of the alkali metal or alkaline earth metal hydroxide added is preferably in the range of 0.8 equivalent or more and 2.0 equivalents or less with respect to the carboxyl group introduced into the cellulose. In particular, when the amount of the alkali metal or alkaline earth metal hydroxide added is in the range of 1.0 equivalent or more and 1.8 equivalents or less with respect to the carboxyl group introduced into the cellulose, an excess amount of alkali metal Further, it is more preferable because counter ion exchange can be performed without adding an alkaline earth metal hydroxide. It is also possible to remove excess alkali metal or alkaline earth metal hydroxide by washing the cellulose again after adding an excess amount of alkali metal or alkaline earth metal hydroxide. By removing the excess alkali, it is possible to suppress deterioration over time of materials such as cellulose.

  Here, the alkali metal species or the alkaline earth metal species is not particularly limited as long as the cellulose is dispersed in nano order, but sodium is preferable from the viewpoint of dispersibility.

<Resin molding>
At least a part of the synthetic resin 2 of the present embodiment is formed of an aqueous resin dispersion. At least a part of the synthetic resin 2 is formed as an aggregate in which a plurality of resin particles 4 of the aqueous resin dispersion are aggregated, and the aggregates are partially bound to be integrated while the surface of the aggregate is made hydrophilic. The sexing fibers 3 are present in a covering manner. Thus, synthetic resin 2 with high hydrophobicity and hydrophilic fiber 3 form a phase separation structure microscopically referred to as sea-island structure, respectively. The hydrophilic fiber 3 which becomes "" is covering. Here, as the physical properties of the resin molded body 1, the mechanical properties of the resin particles 4 themselves of the aqueous resin dispersion constituting the synthetic resin 2 to be “island” and the aggregates thereof greatly contribute to the entire resin molded body 1. , Give physical stability as a structure. In addition, due to the high hydrophobicity of the synthetic resin 2, the shape stability is maintained without swelling even under high humidity or in contact with water. On the other hand, in the hydrophilic fiber 3 in the “sea” region, moisture and water permeability are expressed by transmitting water and water vapor. Here, if the synthetic resin 2 and the hydrophilic fiber 3 are compatible with each other without phase separation, it is not possible to secure a sufficient passage for water in the liquid state to permeate, and water permeability due to the low hydrophilicity of the synthetic resin 2 It becomes difficult to give sex.

  The synthetic resin 2 and the hydrophilic fiber 3 chemically interact with each other while forming a phase separation structure with each other, thereby having the structural stability as the resin molded body 1. As the interaction, in addition to the mutual electrical interaction between the synthetic resin 2 and the hydrophilic fiber 3, when the hydrophilic fiber 3 has an amphiphilic property, it is considered to be adsorbed by the hydrophobic interaction.

  The light transmittance at a wavelength of 660 nm when converted to a thickness of 20 mm when the water content of the resin molded body 1 is 8% or less is preferably 70% or more. Furthermore, 80% or more of the light transmittance is particularly preferable. The moisture content of 8% refers to a state in which equilibrium has been reached under an environment of normal temperature and normal humidity or lower. By maintaining transparency at normal temperature and normal humidity, applicable applications are expanded.

  The content of the hydrophilic fiber 3 in the resin molded body 1 is in the range of 5 parts by weight to 200 parts by weight with respect to 100 parts by weight of the synthetic resin 2. When the amount of the hydrophilic fiber 3 is less than 5 parts by weight, the phase separation structure of the resin molded product 1 is not sufficiently developed, and although it has moisture permeability, it becomes difficult to exhibit water permeability. In addition, when the hydrophilic fiber 3 is more than 200 parts by weight, the hydrophobic region by the synthetic resin 2 is dispersed in the “sea” of the hydrophilic fiber 3, and the moisture permeability and permeability of the resin molded body 1 itself are controlled. In addition to difficulty, the interface of the hydrophobic region relatively decreases, which may result in cloudiness.

The moisture permeability of the resin molded body 1 is 1 × 10 ² g / m ² · day or more and 1 × 10 ⁴ g / m ² · day or less. The region substantially contributing to moisture permeability is mostly due to the hydrophilic fiber 3, and the permeability of the resin molded body 1 is determined by the affinity of the hydrophilic fiber 3 to water and the resin molded body of the hydrophilic fiber region. It depends on the ratio to one.

  Furthermore, it is preferable that the contact angle with respect to water of the surface of the resin molding 1 exceeds 60 degrees 10 seconds after liquid contact. When the contact angle exceeds 60 °, the contact time between the water and the resin molded body 1 can be secured in the moisture permeability and the water permeability of the resin molded body 1, so that water can be selectively permeated.

<Method for producing resin molded product>
Hereinafter, the manufacturing method of the resin molding 1 which concerns on this embodiment is demonstrated. The resin molded body 1 in the present embodiment is formed of a composition in which a synthetic resin 2 at least a part of which is an aqueous resin dispersion and a hydrophilic fiber 3 are mixed. At this time, the mixing property with the synthetic resin 2 can be improved by dispersing the hydrophilic fibers 3 in advance with water or an aqueous solvent. The dispersion process of the hydrophilic fiber 3 in an undispersed state may be performed in the aqueous resin dispersion for the purpose of not lowering the solid content concentration of the coating liquid in wet coating. As a method of dispersion treatment, various dispersion treatments which are already known are possible in the case where there is no problem in the dispersibility of the resin particles 4 of the aqueous resin dispersion in the dispersion medium and the formation of the resin molded body 1 thereafter. is there. For example, homomixer processing, mixer processing with a rotary blade, high pressure homogenizer processing, ultra high pressure homogenizer processing, ultrasonic homogenizer processing, nanogenizer processing, disc type refiner processing, conical type refiner processing, double disc type refiner processing, grinder processing, ball mill processing , Kneading processing by a twin-screw kneader, opposing treatment in water, and the like. Among these, mixer processing with a rotary blade, high pressure homogenizer processing, ultra high pressure homogenizer processing, and ultrasonic homogenizer processing are preferable from the viewpoint of miniaturization efficiency. Note that it is also possible to combine two or more of these processing methods for distribution. In addition, the composition said here is what contains the synthetic resin 2 and hydrophilic fiber 3 which at least one part becomes from aqueous resin dispersion, and the state before carrying out structure formation or reaction by heating or light is considered. Point to. Moreover, a resin molded body shall refer to the form of various kinds, such as a film form, a sheet form, a structure, etc. which were formed using the said composition.

  There is no particular limitation on the method of forming the resin molded body 1 using the composition prepared by mixing the synthetic resin 2 and the hydrophilic fiber 3 thus prepared, but the composition has fluidity. The resin molded product 1 can be obtained by wet coating the composition on a support such as a resin base or a glass base and curing the coating.

  A well-known method can be used as a coating method. Specifically, bar coating method, dip coating method, spin coating method, flow coating method, spray coating method, roll coating method, gravure roll coating method, air doctor coating method, blade coating method, wire doctor coating method, knife coating A method, reverse coating method, transfer roll coating method, microgravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, die coating method, etc. can be used.

  In order to improve the wettability and adhesion of the substrate to which the composition obtained by mixing the synthetic resin 2 and the hydrophilic fiber 3 is coated, the substrate may be pretreated. The pretreatment method is not particularly limited, and, for example, an anchor layer may be formed in advance, or corona treatment, plasma treatment, flame treatment or the like may be performed.

  The composition coated on the support is dried, that is, the resin dispersion 1 can be formed by removing the excess dispersion medium in the system. Furthermore, after the preparation of the resin molded body 1, the resin molded body 1 may be additionally heated for the purpose of improving reaction progress of the resin and other characteristics. Moreover, when using a photoreactive material, you may irradiate the resin molded object 1 with the light of the wavelength which advances reaction.

  The thickness T of the resin molded body 1 obtained in the present embodiment is preferably in the range of 1 μm to 500 μm, and particularly preferably in the range of 10 μm to 200 μm. When the thickness T is less than 1 μm, the strength of the resin molded body 1 becomes extremely weak, which is unsuitable for production. If the thickness T exceeds 500 μm, the drying speed is very long, the productivity is extremely reduced, and problems such as excess water remaining in the inside of the resin molded body 1 are preferable. Absent.

  As another support to which the composition is applied when forming the resin molded body 1, one obtained by laminating a moisturizing layer having a moisturizing property may be used to control the water absorption speed and the transparency. There is no particular limitation on the moisturizing agent constituting the moisturizing layer, and examples thereof include cellulose, cellulose derivatives, chitin, chitosan derivatives, starch, hyaluronic acid, alginic acid, gelatin, kaolin, dextrin, glycerin, polyglycerin, D-sorbitol, PVA, etc. And glycerin and sorbitol are particularly preferred. Moreover, only one type of moisturizer can be used for the moisturizing layer, and two or more types may be used in combination.

  Alternatively, in consideration of the mechanical strength of the resin molded body 1 obtained in the present embodiment, part or all of the resin molded body 1 may be covered with another material having moisture permeability or water permeability. The other material and the resin molded body 1 may be in contact with each other, and may be disposed with a gap as needed. Such materials include, for example, relatively hard materials such as metals, plastics, ceramics, wood and the like.

<Various additive materials>
In the present embodiment, a thermosetting resin may be further added to the composition in which the synthetic resin 2 and the hydrophilic fiber 3 are mixed. When a thermosetting resin is used, the step of removing the dispersion medium such as water contained in the coated composition and the step of forming the resin particles 4 of the synthetic resin 2 simultaneously proceed it can

  Moreover, in order to selectively advance hardening of a coating film by irradiating active energy rays, such as an ultraviolet ray and an electron beam, to the coating film of the coated composition, the composition which mixed the synthetic resin 2 and the hydrophilic fiber 3 A photocurable resin may be further added to the product. A heating step may be added for the purpose of removing the solvent or improving the reactivity in the course of the curing reaction.

  By adding the thermosetting resin or the photocurable resin to the composition in which the synthetic resin 2 and the hydrophilic fiber 3 are mixed, the binding property between the hydrophobic regions of the synthetic resin 2 can be enhanced, or a resin molded product can be obtained. Adjustments can be made to meet various purposes, such as controlling the mechanical properties of 1 and the water absorption rate of the hydrophilic fiber 3.

  Moreover, in order to form a crosslinked structure with the objective of improving water resistance or abrasion resistance, the composition which mixed the synthetic resin 2 and the hydrophilic fiber 3 may also contain various crosslinking agents. As a crosslinking agent which forms a crosslinked structure by heating, although it is not limited, for example, oxazoline, divinyl sulfone, carbodiimide, dihydrazide, dihydrazide, epichlorohydrin, glyoxal, organic titanium compound, organic zirconium compound and the like can be used. Moreover, it is also possible to mix and use 2 or more types in them. Among these, carbodiimide is preferable because it can form a crosslinked structure efficiently without applying a large amount of energy.

  Furthermore, when the coating film of the composition to which the photocurable resin is added is irradiated with active energy rays such as ultraviolet rays and electron beams to advance the curing of the coating, a photocrosslinking agent, a photopolymerization initiator, etc. are used. May be The types of these are not particularly limited, but examples include acetophenone photopolymerization initiator, benzoin photopolymerization initiator, benzophenone photopolymerization initiator, thioxanthone photopolymerization initiator, thioxanthone photopolymerization initiator and the like. it can.

  In addition, it is a function to be added to the composition in which the synthetic resin 2 and the hydrophilic fiber 3 are mixed for the purpose of viscosity adjustment, adjustment of drying speed, improvement of affinity with different materials, etc. in a range not causing aggregation or precipitation. Depending on the water, various organic solvents can be mixed. At this time, for example, adjustment of addition speed and pH, stirring method, temperature, and the like can be appropriately selected in order to reduce shock generated by mixing different solvents.

  In addition, the resin molded body 1 may contain a metal or the like. Examples of the metal contained in the resin molded body 1 include, in addition to platinum group elements such as gold, silver, platinum, palladium, ruthenium, iridium, rhodium, and osmium, iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium Or a metal such as molybdenum, gallium, or aluminum, or an alloy thereof, an oxide, a double oxide, a carbide, or the like.

  As a method of supporting the metal, for example, in addition to a method of mixing fine particles of metal or metal oxide with a composition in which the synthetic resin 2 and the hydrophilic fiber 3 are mixed, cellulose fiber having a carboxyl group is metal or metal There is a method of forming a complex of an oxide and depositing it as a metal particle by adding a reducing agent. When this method is used, minute metal particles are uniformly immobilized on the surface of the cellulose fiber, so that the effect can be efficiently exhibited by a small amount of metal.

  A functional group may be introduced to the hydrophilic fiber 3 in order to impart selective separation ability together with water permeation. For example, as an ion exchange group, an anion exchanger functional group such as diethylaminoethyl (DEAE) tertiary amine functional group, quaternary ammonium group, diethylaminopropyl (ANX) amine group, cation exchanger functional group such as sulfo group or the like By introducing a carboxyl group or the like, it is possible to separate ions of water to be permeated. The functional group introduction step may be carried out before the formation of the composition mixed with the synthetic resin 2 or may be carried out after the formation of the resin molded body 1. However, in the case of the former, adjustment of charge balance with the synthetic resin 2 is difficult, and reproducibility may be difficult to be obtained in control of the aggregate size of the aqueous resin dispersion and the coating on the aggregate by the hydrophilic fiber 3.

  Furthermore, the composition in which the synthetic resin 2 and the hydrophilic fiber 3 are mixed is water-soluble for the purpose of further increasing the charge repulsion in the composition and the purpose of controlling the viscosity of the dispersion within a range where aggregation or precipitation does not occur. It may also contain various additives including various polysaccharides and various resins. For example, it can contain chemically modified cellulose, carrageenan, xanthan gum, guar gum, gum arabic, sodium alginate, agar, solubilized starch, glycerin, sorbitol, antifoaming agent, water-soluble polymer, synthetic polymer and the like. Alternatively, various solvents may be included to impart functionality such as coatability and wettability. For example, alcohols, cellosolves, glycols and the like can be included. Furthermore, various dyes, pigments, organic fillers, inorganic fillers and the like may be included for the purpose of imparting design properties. Moreover, pH can be adjusted by adding an acid or an alkali for the purpose of improving reactivity.

  Hereinafter, embodiments of the present invention will be described. The following examples are examples of the present invention, and the present invention is not limited to these examples.

Example 1
According to the following procedure, preparation of a composition in which a synthetic resin formed by at least one of an aqueous dispersion and an aqueous emulsion and a hydrophilic fiber are mixed and production of a resin molded body are performed.

<Method of producing hydrophilic fiber>
The cellulose fiber used as a hydrophilic fiber was produced.
(1) Reagents / materials / cellulose: bleached kraft pulp (Fletcher Challenge Canada "MACHENZIE")
・ TEMPO: Commercial product (Tokyo Chemical Industry Co., Ltd., purity 98%)
・ Hypochlorous acid sodium: Commercial product (Wako Pure Chemical Industries, Cl: 5%)
-Sodium bromide: Commercial item (Wako Pure Chemical Industries, Ltd.)

(2) TEMPO oxidation treatment The bleached kraft pulp with a dry weight of 10 g was allowed to stand overnight in 500 ml of ion exchanged water placed in a 2 liter (1) glass beaker to swell the pulp. Thereto, 0.1 g of TEMPO and 1 g of sodium bromide were added and stirred to prepare a pulp suspension. With further stirring, 5 mmol / g of sodium hypochlorite per cellulose weight was added. At this time, about 1N aqueous sodium hydroxide solution was added to keep the pH of the pulp suspension at about 10.5. Then, the reaction was carried out for 3 hours, 10 g of ethanol was added to stop the reaction, and oxidized cellulose in which carboxyl group was introduced into cellulose was obtained. In addition, the carboxyl group introduce | transduced in this case formed the salt which made the counter ion the sodium ion originating in the reaction reagent which remains in the reaction solvent. Subsequently, the pH was lowered to 2 by dropwise addition of 0.5 N hydrochloric acid. Next, the cellulose is separated by filtration using a glass filter, and further washed three times with 0.05 N hydrochloric acid to convert the carboxyl group into a carboxylic acid, and then washed five times with pure water to obtain a wet state of 20% solid content concentration Of oxidized cellulose. The amount of carboxyl groups per dry weight of cellulose was calculated to be 1.6 mmol / g from the neutralization titration with sodium hydroxide.

(3) Alkali metal treatment Water is added to the oxidized cellulose prepared above so that the solid content concentration becomes 5% to form a suspension, and sodium hydroxide which is a hydroxide of alkali metal as alkali species is oxidized cellulose 1.0 equivalent was added with respect to the amount of carboxyl groups. After stirring for 2 hours, the oxidized cellulose was filtered off using a glass filter to obtain counterion-substituted oxidized cellulose.

(4) Dispersion treatment A solvent-substituted oxidized cellulose is added to water as a dispersion medium, and treated with a mixer (Absolute mill, 14,000 rpm, manufactured by Osaka Chemical Co., Ltd.) for 1 hour to have a solid content concentration of 0.2%. A cellulose fiber dispersion was obtained. The light transmittance of the obtained dispersion at a wavelength of 660 nm was 94%. Moreover, the average fiber width of the cellulose fiber at this time was 4 nm.

<Preparation of a composition and a resin molding>
(1) Preparation of Composition A synthetic resin and a cellulose fiber are prepared using an aqueous resin dispersion (made by Nikka Chemical Co., Ltd., polyurethane dispersion type, X-7096) and a cellulose fiber dispersion prepared by the above-described procedure. The composition was mixed overnight with a stirrer so that the solid content weight ratio would be 100: 10 in this order, to prepare a composition of synthetic resin and cellulose fiber.

(2) Preparation of a resin molded product The above composition prepared above is coated on a PET film (Lumirror T60-75 μm: Toray) with an applicator and dried in an oven at 120 ° C. for 10 minutes, and then the PET film is peeled off. Then, a 20 μm thick resin molding was produced.

(Example 2)
The composition was prepared so that the synthetic resin and the cellulose fiber had a solid content weight ratio of 100: 30 in this order. A resin molding was produced under the same conditions as Example 1 except for the above.

(Example 3)
The composition was prepared such that the weight ratio of the synthetic resin to the cellulose fiber was 100: 100 in this order by weight of solid content. A resin molding was produced under the same conditions as Example 1 except for the above.

(Example 4)
Using a crosslinking agent having a carbodiimide group (Carbodilite V-02-L2 manufactured by Nisshinbo Chemical Co., Ltd.), the composition is such that the synthetic resin, the cellulose fiber and the crosslinking agent have a solid content weight ratio of 100: 30: 10 in this order Prepared. A resin molding was produced under the same conditions as Example 1 except for the above.

(Example 5)
A 15 wt% aqueous solution of PVA (Kuraray Co., Ltd., PVA 105), which is a thermosetting resin with a crosslinking agent, is prepared so that the synthetic resin, cellulose fiber and PVA have a solid content weight ratio of 100: 30: 10 in this order. The composition was prepared. A resin molding was produced under the same conditions as Example 1 except for the above.

(Example 6)
The solid content weight ratio of the synthetic resin, cellulose fiber, photocurable resin (manufactured by KJ Chemicals, HEAA) and photopolymerization initiator (manufactured by BASF, Irgacure 500) become 100: 30: 10: 0.3 in this order The composition was prepared as follows. The prepared composition is coated on a PET film (Lumirror T60-75 μm: Toray) using an applicator and dried in an oven at 120 ° C. for 10 minutes, then irradiated with light at 500 mJ / cm ² with a high pressure mercury lamp under a nitrogen atmosphere. A resin molded product was produced under the same conditions as in Example 1 except that the treatment was performed.

(Comparative example 1)
The composition was prepared such that the weight ratio of the synthetic resin to the cellulose fiber was 100: 250 in this order by weight on solid content. A resin molding was produced under the same conditions as Example 1 except for the above.

(Comparative example 2)
A resin molded product was produced under the same conditions as in Example 1 except that the same weight of water was used instead of the cellulose fiber.

(Comparative example 3)
The same weight of water was used instead of the synthetic resin. Furthermore, a resin molded product was produced under the same conditions as in Example 1 except that the drying conditions were set to 50 ° C. for 7 days.

(Comparative example 4)
The dispersion treatment time using a mixer was 10 minutes in the preparation of the cellulose fiber. A resin molding was produced under the same conditions as Example 1 except for the above. The average fiber width of the cellulose fiber at this time was 500 nm.

[Evaluation]
The production conditions of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1 below, and the evaluation results are shown in Table 2.

[Measurement of cellulose fiber width]
The sample was diluted with water so that the solid content concentration of the cellulose fiber was 0.001 wt%, developed on mica and naturally dried, and then the sample was observed with a transmission electron microscope. Ten samples were randomly taken, and the average value was determined as an average fiber width (nm).

Moisture Permeability of Resin Moldings
The moisture permeability of the resin molded body was measured in accordance with JIS Z 0280: 1976 (The moisture permeability test method for a moisture-proof packaging material; the cup method). A resin molded body was attached as a test piece to a JIS-specific moisture-permeable cup containing calcium chloride, and the edge of the test piece was sealed. The moisture-permeable cup was stored in an environment of 40 ° C. and 90% RH and stored for about 5 days. The measurement was performed three times, and the moisture permeability (g / m ² · day) was obtained from the average value of the weight increase of the cup.

[Permeability of resin molding]
About the water permeability of the resin molding, the resin molding was floated on the petri dish with water, and the oozing of water from the surface on the side opposite to the surface in contact with water was confirmed. The observation was continued for 10 minutes, and those which could confirm the exudation of water as water droplets were shown as ○, and those which could not be confirmed were shown as x. FIG. 3 is a view showing the resin molded body in the water permeability test, showing that a water drop was confirmed on the surface of the resin molded body after 1 minute, and that an exudation of water could be confirmed as a water drop after 10 minutes. is there.

[Water contact angle of resin molding]
About the contact angle with respect to water of the resin molding, it measured based on JISR3257: 1999 (the wettability test method of the substrate glass surface). As one of the test pieces, one surface of a resin molded product was attached to glass with a double-sided tape, 3 μl of distilled water was dropped on the test piece, and the contact angle after 10 seconds of dropping was measured. The measurement was performed three times, and the average value was determined as the contact angle.

[Light transmittance of resin molding]
About the resin molding, the light transmittance (%) of wavelength 660 nm in 20 nm film thickness conversion was measured using UV-VIS spectrophotometer (made by Shimadzu Corporation, UV3600). The resin molded product as a test piece is conditioned at 23 ° C. and 50% RH one day or more before measurement, and is measured with a Karl Fischer moisture meter (manufactured by Mitsubishi Chemical Analytech Co., CA-200) before light transmittance measurement. When the moisture content was measured, all the test pieces were 0.5% or more and 3% or less.

  From the results in Table 2, if the synthetic resin and the cellulose fiber as the hydrophilic fiber have a predetermined composition ratio, and the average fiber width of the hydrophilic fiber is not too wide (in the case of Examples 1 to 6), It was found to have moisture permeability and water permeability.

  On the other hand, when the content of the hydrophilic fiber is too large (in the case of Comparative Example 1), in the case where the hydrophilic fiber is not contained (in the case of Comparative Example 2), and when the synthetic resin is not contained (in the case of Comparative Example 3) Since it is impossible to form a continuous nonporous body while the synthetic resin and the hydrophilic fiber are microscopically phase-separated, the penetration of water by the hydrophilic fiber can not be sufficiently controlled, and I did not have sex. In addition, when the average fiber width of the hydrophilic fiber is large (in the case of Comparative Example 4), the water penetrates into the hydrophilic fiber and the surface of the resin molded body sinks under the water surface, so the bleeding of water as water droplets is caused. I could not confirm.

  According to the resin molded product of the present invention, moisture absorption and moisture retention are achieved using the characteristics of the resin molded product having moisture permeability and water permeability while being nonporous and having high transparency under normal temperature and normal humidity. Can be used in a wide range of applications ranging from the living and environmental fields to the energy field, such as

1 resin molded body 2 synthetic resin 3 hydrophilic fiber 4 resin particle

Claims (8)

A resin molded product comprising a composition comprising at least a synthetic resin and a hydrophilic fiber,
At least a part of the synthetic resin is an aggregate in which a plurality of resin particles are aggregated, and forms a sea-island structure in which the synthetic resin and the hydrophilic fiber are phase separated from each other.
The moisture permeability of the resin molded body is 1 × 10 ² g / m ² · day or more and 1 × 10 ⁴ g / m ² · day or less,
The content of the hydrophilic fiber is in the range of 5 parts by weight to 200 parts by weight with respect to 100 parts by weight of the synthetic resin,
The average fiber width of the hydrophilic fiber is in the range of 3 nm to 200 nm,
A resin molded body characterized by having moisture permeability and water permeability and being nonporous.   The resin molded body according to claim 1, wherein the contact angle of the surface of the resin molded body to water exceeds 60 ° after 10 seconds from the liquid contact.   The light transmittance of a wavelength of 660 nm at a film thickness conversion of 20 nm of the resin molded body in a state where the water content of the resin molded body is 8% or less is 70% or more. The resin molding as described in-.   The resin molded product according to any one of claims 1 to 3, wherein the at least a part of the synthetic resin is an aqueous resin dispersion.   The thickness of the said resin molding is in the range of 1 micrometer or more and 500 micrometers or less, The resin molding of any one of the Claims 1-4 characterized by the above-mentioned.   The aspect ratio of the said hydrophilic fiber is 100-1000, The resin molding of any one of the Claims 1-5 characterized by the above-mentioned.   The resin molded body according to any one of claims 1 to 6, wherein the hydrophilic fiber is a cellulose fiber. A coating agent comprising at least a composition for forming a resin molded product, comprising a synthetic resin and a hydrophilic fiber,
The content of the hydrophilic fiber is in the range of 5 parts by weight to 200 parts by weight with respect to 100 parts by weight of the synthetic resin,
A coating agent characterized in that an average fiber width of the hydrophilic fiber is in a range of 3 nm to 200 nm.