Vacuum bag molding system, method of manufacturing reinforcement fiber composite molded body, and breather

Abstract

Provided is a vacuum bag molding system that, with respect to autoclave molding of reinforcement fiber composite materials and the like, can reduce waste and mold a molded body having a favorable surface appearance. This vacuum bag molding system is provided with a vacuum bag and a vacuum valve for exhausting air from inside the vacuum bag. The interior of the vacuum bag accommodates a laminate comprising: an uncured reinforcement fiber composite material disposed on a mold directly or with another member interposed therebetween; and a breather disposed so as to be in direct contact with the uncured reinforcement fiber composite material. The breather is a nonwoven fabric formed from fibers composed mainly of a thermoplastic resin having a glass transition temperature of 100°C or lower.

Description

Vacuum bag molding system, method for manufacturing a reinforced fiber composite body, and breather

[0001] The present invention relates to a vacuum bag molding system, a reinforced fiber composite body, and a breather.

[0002] Composite materials in which fibers such as natural fibers and carbon fibers are hardened with a base material (matrix) such as resin are known. In the molding of such composite materials, various molding methods are selected according to the final form and characteristics. Among the molding methods, autoclave molding has a high degree of freedom in materials and shapes and is the molding method that most easily brings out the characteristics and performance of composite materials.

[0003] A typical procedure outline of autoclave molding is as follows. A prepreg in which fibers (reinforcing fibers) serving as a reinforcing material are impregnated with a thermosetting resin is cut into a predetermined shape. A mold release agent is applied to a mold (die) having a desired shape, and the required number of prepregs are laminated at a predetermined position inside the mold. A release film and a breather are sequentially arranged on the surface of the laminated prepregs, and these are covered and sealed with a bagging film. By covering and sealing with such a bagging film, a vacuum bag is formed. By exhausting the air inside the vacuum bag and making the inside of the vacuum bag into a vacuum state, the adhesion of the laminated prepregs to the mold is enhanced. Then, a reinforced fiber composite body is obtained by curing the thermosetting resin while heating and pressurizing in an autoclave.

[0004] Autoclave molding can obtain a high-quality molded body, but requires a large number of auxiliary materials (release film, breather, bagging film, etc.). Patent Document 1 describes that when performing autoclave molding, in order to facilitate the exhaust of the inside of the bag, a breather made of a porous material is provided inside the bag. When not using a breather, usually, the air inside the vacuum bag cannot be sufficiently exhausted, or a gap easily remains between the bagging film and the molding material after exhaust.

[0005] International Publication No. 2018 / 163506

[0006] Auxiliary materials used during autoclave molding, such as breather, are difficult to reuse, and thus have problems such as a large amount of waste generated from the auxiliary materials after molding.

[0007] The object of the present invention is to provide a vacuum bag molding system that can reduce waste and enable the molding of a molded body with a good surface appearance in autoclave molding of a reinforced fiber composite material, a method for manufacturing a reinforced fiber composite body using such a vacuum bag molding system, and a breather that enables such a vacuum bag molding system.

[0008] As a result of intensive studies by the present inventors, the following findings were obtained. In autoclave molding or the like, by using a non-woven fabric formed from fibers of a thermoplastic resin having a low glass transition temperature as a breather, the non-woven fabric as a breather melts during heat curing and is fixed to the surface of the molded body obtained integrally with the reinforced fiber composite material. As a result, the breather does not become waste, and a molded body with a good surface appearance is obtained. Based on such findings, the present invention has been achieved.

[0009] In other words, the present invention relates to [1] to [8]. [1] A vacuum bag molding system comprising a vacuum bag and a vacuum valve for exhausting from the vacuum bag, wherein the vacuum bag contains a laminate having an uncured reinforced fiber composite material disposed directly on a mold or via other components, and a breather disposed in direct contact with the uncured reinforced fiber composite material, wherein the breather is a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less; [2] The vacuum bag molding system of [1] wherein the vacuum bag has a polyvinyl alcohol film; [3] The vacuum bag molding system of [2] wherein the polyvinyl alcohol film is in direct contact with the uncured reinforced fiber composite material; [4] Any vacuum bag molding system of [1] to [3] wherein a release film is disposed between the vacuum bag and the laminate. [5] A vacuum bag molding system according to any one of [1] to [4], wherein the nonwoven fabric is a continuous long-fiber nonwoven fabric formed from fibers mainly composed of amorphous thermoplastic phenoxy resin as the thermoplastic resin; [6] The vacuum bag molding system according to [5], wherein the uncured reinforced fiber composite material contains epoxy resin; [7] A method for manufacturing a reinforced fiber composite molded article using a vacuum bag molding system according to any one of [1] to [6], comprising the steps of: discharging air from inside the vacuum bag through the vacuum valve; and heat-curing the uncured reinforced fiber composite material contained in the vacuum bag; [8] A breather for autoclave molding, wherein the breather is a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less; [9] The breather according to [8], wherein the thermoplastic resin is an amorphous resin or a crystalline resin having a melting point of 150°C or less;

[0010] According to the present invention, a vacuum bag molding system is provided that can reduce waste and enable the molding of molded articles with a good surface appearance in autoclave molding of reinforced fiber composite materials, a method for manufacturing a reinforced fiber composite molded article using such a vacuum bag molding system, and a breather that enables such a vacuum bag molding system.

[0011] Figure 1 is a schematic cross-sectional view showing a vacuum bag molding system according to the first embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing a vacuum bag molding system according to the second embodiment of the present invention.

[0012] In this specification, numerical ranges indicated using "~" include the values ​​indicated before and after "~" as the lower and upper limits, respectively. In this specification, the upper and lower limits of numerical ranges (content, physical properties, etc.) can be combined as appropriate. In this specification, "main component" refers to the component with the highest content by mass. In this specification, polyvinyl alcohol may be abbreviated as "PVA," polyvinyl alcohol film as "film," uncured reinforced fiber composite material as "prepreg," and autoclave molding as "AC molding."

[0013] A vacuum bag molding system is a system for performing molding (e.g., AC molding) using a vacuum bag. A vacuum bag is a shape that creates a vacuum inside when the inside is evacuated. A vacuum bag may be, for example, a bag shape, but is not limited to that. A vacuum bag may consist only of a bagging film, or it may consist of a bagging film and other components (e.g., a mold). A vacuum state does not refer only to a completely vacuum state, but to a state where the pressure is sufficiently reduced compared to atmospheric pressure. A vacuum state may be, for example, 0.1 atmospheres or less, or 0.01 atmospheres or less or 0.001 atmospheres or less. An uncured reinforced fiber composite material is a semi-cured material in which a thermosetting resin has been impregnated into the fibers. A reinforced fiber composite material is a material made by compounding reinforcing fibers with other materials (such as resin), and a reinforced fiber composite molded body is a molded reinforced fiber composite material. Reinforcing fibers are fibers (reinforcing materials) used to strengthen a material or molded body.

[0014] A vacuum bag molding system according to one embodiment of the present invention comprises a vacuum bag and a vacuum valve for exhausting air from the vacuum bag, wherein the vacuum bag contains a laminate having an uncured reinforced fiber composite material placed directly on a mold or via other components and a breather placed in direct contact with the uncured reinforced fiber composite material, the breather being a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less.

[0015] This vacuum bag molding system reduces waste during autoclave molding of reinforced fiber composite materials and enables the formation of molded products with a good surface appearance. While the exact reason for these effects is unclear, the following reasons are possible.

[0016] Autoclave molding and similar processes typically involve heat curing at temperatures exceeding 100°C. Therefore, by using a nonwoven fabric formed from fibers primarily composed of a thermoplastic resin with a glass transition temperature of 100°C or lower as a breather, and by positioning such a breather in direct contact with the uncured reinforced fiber composite material, the nonwoven fabric acting as the breather melts during heat curing and becomes fixed to the surface of the molded body, becoming integrated with the reinforced fiber composite material. This eliminates the need for waste from the breather and is expected to result in a molded body with a good surface appearance.

[0017] <Breather> The following describes in detail a breather according to one embodiment of the present invention. The breather is a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less. This breather is useful as a breather for autoclave molding.

[0018] The thermoplastic resin that forms the main component of the fibers constituting the breather according to one embodiment of the present invention may be selected from thermoplastic resins having a glass transition temperature of 100°C or less. The thermoplastic resin having a glass transition temperature of 100°C or less may be a crystalline resin such as polyethylene, polypropylene, or nylon 6, or an amorphous resin such as polyvinyl chloride, polystyrene, or phenoxy resin. However, an amorphous resin or a crystalline resin with a melting point of 150°C or less is preferred, an amorphous resin is more preferred, and an amorphous thermoplastic phenoxy resin is even more preferred. Using such a thermoplastic resin will result in a better surface appearance of the resulting molded article. The presence or absence of an endothermic peak in differential scanning calorimetry (DSC) at a heating rate of 10°C / min in a nitrogen atmosphere can be confirmed. That is, a resin in which an endothermic peak cannot be confirmed in the above DSC is an amorphous resin, and a resin in which an endothermic peak can be confirmed in the above DSC is a crystalline resin. If the endothermic peak is very broad and cannot be clearly identified, it is also determined to be an amorphous resin.

[0019] The upper limit of the glass transition temperature of the thermoplastic resin is 100°C, preferably 98°C, more preferably 95°C, and even more preferably 90°C. If the glass transition temperature of the thermoplastic resin exceeds 100°C, the breather may not melt sufficiently when producing the molded article, resulting in appearance problems such as cloudy residue. If the thermoplastic resin is a crystalline thermoplastic resin, its melting point is preferably 150°C or lower, more preferably 130°C or lower, even more preferably 110°C or lower, and particularly preferably 100°C or lower. The lower limit of the glass transition temperature of the thermoplastic resin can be, for example, 30°C, and may also be 40°C, 50°C, 60°C, or 70°C, from the viewpoint of heat resistance, etc. The glass transition temperature of the thermoplastic resin is measured by differential scanning calorimetry (DSC) and is the value measured by the method described in the examples below.

[0020] Thermoplastic phenoxy resins can be synthesized by conventionally known methods. For example, thermoplastic phenoxy resins can be obtained from a condensation reaction between a divalent phenol compound and an epihalohydrin, or from a polyaddition reaction between a divalent phenol compound and a bifunctional epoxy resin.

[0021] Examples of divalent phenol compounds used in the production of thermoplastic phenoxy resins include hydroquinone, resorcinol, 4,4-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ketone, 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, and 1,1-bis(4-hydroxyphenyl)-1-phenoxyphenyl Examples include ruethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(3-phenyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 1,3-bis(2-(4-hydroxyphenyl)propyl)benzene, 1,4-bis(2-(4-hydroxyphenyl)propyl)benzene, 2,2-bis(4-hydroxyphenyl)-1,1,1-3,3,3-hexafluoropropane, and 9,9'-bis(4-hydroxyphenyl)fluorene. Among these, 4,4-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ketone, 2,2-bis(4-hydroxyphenyl)propane, or 9,9'-bis(4-hydroxyphenyl)fluorene are preferred in terms of physical properties, cost, etc.

[0022] The synthesis of thermoplastic phenoxy resins can be carried out without a solvent or in the presence of a solvent. Suitable solvents include aprotic organic solvents such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, and sulfolane. The thermoplastic phenoxy resin obtained from the reaction can be converted into a solvent-free solid resin by desolvent treatment using an evaporator or the like.

[0023] Conventional known polymerization catalysts that can be used in the synthesis of thermoplastic phenoxy resins include alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, and quaternary phosphonium compounds.

[0024] The weight-average molecular weight of the thermoplastic phenoxy resin is not particularly limited, but is preferably 10,000 to 120,000, more preferably 20,000 to 100,000, and even more preferably 30,000 to 80,000. A weight-average molecular weight within this range makes it easier to obtain a nonwoven fabric with good density, strength, etc. The weight-average molecular weight of the thermoplastic phenoxy resin is the value measured by the method described in the examples below.

[0025] The fibers, which mainly consist of a thermoplastic resin, preferably contain 50% by mass or more of the thermoplastic resin, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. The fibers also preferably contain 50% by mass or more of a thermoplastic phenoxy resin, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

[0026] The aforementioned fibers may contain other components besides thermoplastic resins, to the extent that they do not impede the effects of the present invention. Examples of such other components include antioxidants, antistatic agents, radical inhibitors, matting agents, ultraviolet absorbers, flame retardants, and inorganic substances.

[0027] Examples of the inorganic substances include oxides (silicon oxide, magnesium oxide, alumina, zirconium oxide, titanium oxide, iron oxide, etc.), carbonates (calcium carbonate, magnesium carbonate, dolomite, etc.), sulfates (calcium sulfate, barium sulfate, etc.), hydroxides (calcium hydroxide, magnesium hydroxide, aluminum hydroxide, etc.), carbon black, graphite, carbon nanotubes, fullerenes, talc, wollastonite, zeolites, sericite, mica, kaolin, clay, pyrophyllite, silica, bentonite, alumina silicate, glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, and the like.

[0028] The nonwoven fabric may be formed solely from fibers primarily composed of thermoplastic phenoxy resin. Alternatively, the nonwoven fabric may be formed from fibers primarily composed of thermoplastic phenoxy resin and other fibers. Examples of other fibers include resin fibers other than thermoplastic phenoxy resin, glass fibers, and the like.

[0029] The content of the thermoplastic resin having a glass transition temperature of 100°C or lower in the nonwoven fabric (breather) is preferably 50% by mass or more, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. The content of the amorphous thermoplastic phenoxy resin in the nonwoven fabric (breather) is preferably 50% by mass or more, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

[0030] The nonwoven fabric is preferably a continuous filament nonwoven fabric. A continuous filament nonwoven fabric is a nonwoven fabric obtained by spinning fibers in a continuous manner. The method for producing a continuous filament nonwoven fabric is not particularly limited, but preferred methods include the meltblown method, the spunbond method, the flash spinning method, and the electrospinning method. By employing such methods, a continuous filament nonwoven fabric with excellent density, formed using fibers with a small average fiber diameter, can be easily obtained. Among these, the meltblown method or the spunbond method is preferred from the viewpoint of minimizing environmental impact as it does not require solvents during spinning.

[0031] In the case of the meltblown method, a conventionally known meltblown apparatus can be used as the spinning apparatus. The spinning temperature is not particularly limited and may be, for example, 250 to 400°C, preferably 300 to 380°C, and more preferably 320 to 370°C. The temperature of the hot air applied immediately after discharge from the nozzle hole (primary air temperature) is also not particularly limited and may be, for example, 260 to 400°C, preferably 270 to 380°C, and more preferably 290 to 360°C. Furthermore, the amount of air sprayed per 1 m of nozzle width (amount of air) is also not particularly limited and may be, for example, 5 to 50 Nm ３ Preferably 6 to 40 Nm ３ , more preferably 7 to 30 Nm ３ That's fine.

[0032] In the case of the spunbond method, a conventionally known spunbond spinning apparatus can be used. The spinning temperature is not particularly limited and may be, for example, 250 to 350°C, preferably 260 to 340°C, and more preferably 280 to 330°C. The temperature of the hot air applied immediately after spinning (drawing air temperature) is also not particularly limited and may be, for example, 260 to 370°C, preferably 270 to 350°C, and more preferably 290 to 340°C. Furthermore, the drawing air is also not particularly limited and may be, for example, 500 to 5,000 m / min, preferably 600 to 4,000 m / min, and more preferably 800 to 3,000 m / min.

[0033] The continuous long-fiber nonwoven fabric obtained by the above manufacturing method may be subjected to three-dimensional entanglement treatment using methods such as spunlacing, needle punching, or steam jetting, from the viewpoint of increasing its mechanical strength.

[0034] The upper limit of the average fiber diameter of the fibers constituting the nonwoven fabric is not particularly limited, but is preferably 20 μm, more preferably 15 μm, and even more preferably 10 μm. When the average fiber diameter is below the upper limit, the density of the nonwoven fabric increases, and the surface smoothness and appearance of the resulting molded article tend to improve. The lower limit of the average fiber diameter is not particularly limited, but from the viewpoint of ease of forming the nonwoven fabric and ease of handling, is preferably 1 μm, and more preferably 3 μm.

[0035] The upper limit of the basis weight (A) of the nonwoven fabric is not particularly limited, but is 100 g / m².２ is preferable, 80 g / m ２ is more preferable, 50 g / m ２ is even more preferable, 30 g / m ２ or 20 g / m ２ may also be acceptable. By having the basis weight (A) of the non-woven fabric be below the above upper limit, the entire non-woven fabric can be sufficiently melted during the process of performing heat curing, and a molded body having a better appearance with less cloudiness or the like can be obtained. The lower limit of the basis weight (A) is not particularly limited, but from the perspective of ease of forming the non-woven fabric, etc., 4 g / m ２ is preferable, 7 g / m ２ is more preferable. The basis weight (A) of the non-woven fabric is a value measured by the method described in the examples below.

[0036] The upper limit of the air permeability (B) of the non-woven fabric is not particularly limited, but 1,000 cm ３ / cm ２ ·s is preferable, 900 cm ３ / cm ２ ·s is more preferable, 800 cm ３ / cm ２ ·s is even more preferable, 500 cm ３ / cm ２ ·s, 300 cm ３ / cm ２ ·s or 200 cm ３ / cm ２ ·s may also be acceptable. By having the air permeability (B) be below the above upper limit, the denseness of the non-woven fabric increases, and the surface smoothness of the obtained molded body tends to increase. The lower limit of the air permeability (B) is not particularly limited, but 50 cm ３ / cm ２ ·s is preferable, 70 cm ３ / cm ２ ·s is more preferable. By having the air permeability (B) be above the above lower limit, the exhaustibility can be enhanced, and a molded body having a better appearance with less cloudiness or the like can be obtained because the entire non-woven fabric is sufficiently melted during the process of performing heat curing. The air permeability (B) of the non-woven fabric is a value measured by the method described in the examples below.

[0037] The ratio of the air permeability (B) to the basis weight (A) (air permeability (B) / basis weight (A)) ((cm ３ / cm ２s) / (g / m) ２ The upper limit of )) is not particularly limited, but 100 is preferred, 95 is more preferred, 90 is even more preferred, and it may be 85, 80, 70, 60, 50, 40, 30 or 20. When the ratio (air permeability (B) / basis weight (A)) is less than or equal to the above upper limit, the density of the nonwoven fabric is improved, the exhaust performance is enhanced, and a molded article with a better appearance can be obtained. The lower limit of the ratio (air permeability (B) / basis weight (A)) may be, for example, 5.

[0038] The average thickness of each sheet of the nonwoven fabric is not particularly limited, but from the viewpoint of handling and other factors, it is preferably 0.01 to 3 mm, more preferably 0.05 to 2 mm, even more preferably 0.10 to 1 mm, and may also be 0.10 to 0.50 mm.

[0039] <PVA Film> In the vacuum bag molding system or method for manufacturing a reinforced fiber composite molded article according to one embodiment of the present invention, it is preferable to use a PVA film as the bagging film for forming the vacuum bag. Alternatively, a PVA film may be used as the release film. PVA film has excellent release properties from molded articles obtained from molding materials, such as reinforced fiber composite materials (reinforced fiber composite molded articles) after curing. This is thought to be due to the low affinity between PVA and the resin used in the molding material (especially thermosetting resins such as epoxy resins). The molding material is the material to be molded, such as an uncured reinforced fiber composite material.

[0040] Furthermore, PVA film is considered to be a suitable film for use as a bagging film due to its excellent balance of flexibility and strength. Specifically, when the vacuum bag is evacuated, the PVA film stretches sufficiently to conform to the shape of the molding material, resulting in high conformability to the shape of the molding material and minimizing gaps between the bagging film and the molding material. In addition, PVA film has sufficient strength and is resistant to breakage even when stretched to a certain extent, making it suitable for use as a bagging film. Moreover, PVA film is highly flexible and has excellent release properties from the molding material, making it easy to remove air bubbles (voids) remaining between the molding material and the film during evacuation. Thus, PVA film is considered to enable the formation of good molded products due to its high conformability, minimal gaps between the bagging film and the molding material, and the ability to be directly laminated onto the surface of the molding material. Furthermore, PVA film has low air permeability and excellent moisture permeability under high humidity conditions. Therefore, when a vacuum bag is made using PVA film, it is possible to maintain a vacuum while allowing moisture inside the molding material to escape to the outside of the vacuum bag, making PVA film suitable for the vacuum bag molding system of the present invention.

[0041] Furthermore, because PVA film is highly water-soluble, when PVA film is used for vacuum bags, it is possible to remove the PVA film used as a vacuum bag by washing it with water after molding, such as autoclave molding. Removing the PVA film by dissolving it with water in this way has advantages such as improved work efficiency and further reduction of waste. The following provides a detailed explanation of PVA film.

[0042] PVA film contains PVA as its main component. The main component refers to the component that is present in the largest quantity by mass. The lower limit of the PVA content in PVA film is preferably 50% by mass, more preferably 60% by mass, and even more preferably 80% by mass. The upper limit of the PVA content in PVA film may be 100% by mass, or 99% by mass, 95% by mass, or 90% by mass.

[0043] PVA stands for vinyl alcohol unit (-CH ２It is a polymer having -CHOH-). PVA may have monomer units other than vinyl alcohol units. As PVA, a vinyl ester polymer obtained by polymerizing vinyl ester monomers and then saponifying that polymer can be used. Polymerization and saponification can be carried out by conventionally known methods.

[0044] Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versaticate, with vinyl acetate being preferred.

[0045] The vinyl ester polymer may be obtained using only one or more vinyl ester monomers as monomers, or it may be obtained using only one vinyl ester monomer as monomer. The vinyl ester polymer may be a copolymer of one or more vinyl ester monomers and other monomers copolymerizable thereto. It is also preferable to use modified PVA from the viewpoint of allowing the PVA film to be easily dissolved by washing with water after molding. Modified PVA refers to PVA that has monomer units derived from monomers other than vinyl esters. Modified PVA may be a saponified product of modified polyvinyl ester. Furthermore, modified PVA may be obtained by post-modifying unmodified PVA.

[0046] Other monomers copolymerizable with vinyl ester monomers include, for example, ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, methac Methacrylic acid esters such as n-propyl lylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its salts, N-methylolacrylamide or its derivatives Acrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salts, methacrylamidepropyldimethylamine or its salts, N-methylolmethacrylamide or its derivatives, and other methacrylamide derivatives; N-vinylamide such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and other N-vinylamides; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether Examples include vinyl ethers such as tel, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or its salts, esters, or acid anhydrides; itaconic acid or its salts, esters, or acid anhydrides; vinyl silyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.Vinyl ester polymers and polyvinyl alcohols may have monomer units derived from one or more of these other monomers.

[0047] When the vinyl ester polymer is a copolymer, a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate is preferred. The content of monomer units derived from other monomer copolymerizable with vinyl acetate in the (co)polymer is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 4 mol% or less, when the vinyl ester units in the copolymer are taken as 100 mol%. From the viewpoint of increasing water solubility, the content of monomer units derived from other monomer copolymerizable with vinyl acetate in the (co)polymer may be 0.5 mol% or more, or 1 mol% or more. The ratio of monomer units derived from monomers other than vinyl ester to the total monomer units constituting the modified PVA is also called the modification amount.

[0048] As the modified PVA, acid-modified PVA such as carboxylic acid-modified PVA, sulfonic acid-modified PVA, and phosphate-modified PVA is preferred, and at least one selected from the group consisting of sulfonic acid-modified PVA and carboxylic acid-modified PVA is more preferred. Using such modified PVA tends to increase the water solubility of the PVA film after molding.

[0049] Sulfonic acid-modified PVA is PVA having a sulfo group. The sulfo group may be in the form of a salt or an anhydride. Sulfonic acid-modified PVA may have monomer units derived from unsaturated sulfonic acid (acrylamide alkyl sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, etc.), its salt, or its anhydride, or it may have a sulfo group introduced by post-modification. It is preferable that sulfonic acid-modified PVA has monomer units derived from unsaturated sulfonic acid, its salt, or its anhydride.

[0050] Carboxylic acid-modified PVA is PVA having a carboxyl group. The carboxyl group may be in the form of a salt or an anhydride. Carboxylic acid-modified PVA may have monomer units derived from an unsaturated carboxylic acid (such as acrylic acid, methacrylic acid, maleic acid, itaconic acid), its salt, or its anhydride, or it may have a carboxyl group introduced by post-modification. It is preferable that carboxylic acid-modified PVA has monomer units derived from an unsaturated carboxylic acid, its salt, or its anhydride.

[0051] The modified PVA is preferably a saponified product of a modified polyvinyl ester (a copolymer of a vinyl ester and another monomer other than a vinyl ester). In other words, it is preferable that the modified PVA is not modified by post-modification. The main chain of the modified PVA may consist of vinyl alcohol units, arbitrary vinyl ester units, and units derived from other monomers. The other monomers are preferably monomers having acidic groups (sulfo groups, carboxyl groups, phosphate groups, etc.). The acidic groups may be in the form of salts or anhydrides. Examples of monomers having acidic groups include the unsaturated sulfonic acid, its salt or anhydride, the unsaturated carboxylic acid, its salt or anhydride, etc.

[0052] The degree of polymerization of PVA is not particularly limited, and may be, for example, 500 to 8,000, 1,000 to 6,000, or 1,500 to 4,000. Here, the degree of polymerization of PVA refers to the viscosity-average degree of polymerization (Po) measured in accordance with the description in JIS K6726-1994, and is determined from the intrinsic viscosity [η] (deciliters / g) measured in water at 30°C after resaponification and purification of PVA by the following formula: Po = ([η] × 10⁻¹⁰ ４ (8.29) （１／０．６２）

[0053] The degree of saponification of PVA is not particularly limited, and is, for example, 70 to 100 mol%. From the viewpoint of the flexibility of the PVA film, the lower limit of the degree of saponification of PVA may preferably be 75 mol%, 80 mol%, 85 mol%, 90 mol%, 95 mol%, 98 mol%, or 99 mol%. From the viewpoint of the water solubility of the PVA film after molding, the upper limit of the degree of saponification may preferably be 95 mol%, 93 mol%, or 91 mol%. Here, the degree of saponification of PVA refers to the ratio (mol%) of moles of vinyl alcohol units to the total number of moles of monomer units (typically vinyl ester units) and vinyl alcohol units that can be converted to vinyl alcohol units by saponification. The degree of saponification of PVA can be measured in accordance with the description in JIS K6726-1994.

[0054] In addition to PVA as the main component, the PVA film may also contain water, plasticizers, surfactants, fillers, starch, polymers other than PVA, etc., as long as they do not impair the effects of the present invention.

[0055] The inclusion of plasticizers in the PVA film imparts particularly good flexibility to the film. As a result, when the pressure inside the vacuum bag is reduced, the film stretches appropriately to conform to the shape of the molding material, making it easier to move along with it. This excellent conformability also reduces the likelihood of air bubbles (voids) remaining between the molding material and the film during reduced pressure.

[0056] As plasticizers, polyhydric alcohols such as ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, trimethylolpropane, and sorbitol are preferred from the viewpoint of being less likely to cause bleed-out to the water-soluble film surface, and it is more preferable that at least one is selected from the group consisting of ethylene glycol, glycerin, diglycerin, propylene glycol, and diethylene glycol.

[0057] The amount of plasticizer contained in the PVA film can be appropriately adjusted according to the shape and surface properties of the molded article. The lower limit of the plasticizer content in the PVA film may be 0 parts by mass, preferably 1 part by mass, more preferably 3 parts by mass, and may also be 5 or 10 parts by mass per 100 parts by mass of PVA. By setting the plasticizer content in the PVA film to be above the lower limit, the flexibility of the PVA film can be increased. On the other hand, the upper limit of the plasticizer content is preferably 25 parts by mass, more preferably 20 parts by mass per 100 parts by mass of PVA. By setting the plasticizer content in the PVA film to be below the upper limit, the strength of the PVA film can be increased.

[0058] Examples of surfactants include anionic surfactants and nonionic surfactants. The inclusion of surfactants in the PVA film improves its release properties from the film-forming rolls and drying rolls during film manufacturing, enabling more productive film production.

[0059] As anionic surfactants, R ａ -O-SO ３ － (R ａ Alkyl sulfate salts having an anion represented by an alkyl group (e.g., sodium lauryl sulfate, sodium dodecyl sulfate); R ａ -O-(R ｂ O) ｎ -SO ３ － (R ａ is an alkyl group, R ｂExamples include polyoxyalkylene alkyl ether sulfate salts having an anion represented by an alkylene group (e.g., sodium polyoxyethylene isotridecyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene polyoxypropylene lauryl ether sulfate); dialkyl sulfosuccinates such as dialkyl sulfosuccinate and sodium di-2-ethylhexyl sulfosuccinate; alkyl sulfonates (linear or branched alkyl sulfonates) such as octyl sulfate, lauryl sulfate, sodium lauryl sulfonate, and sodium lauryl sulfoacetate; alphaolefin sulfonates such as alphaolefin sulfonate and sodium tetradecene sulfonate; linear or branched alkylbenzene sulfonates such as alkylbenzene sulfonate and sodium dodecylbenzenesulfonate; condensates of naphthalene sulfonates and formaldehyde, such as sodium naphthalene sulfonate-formaldehyde condensate; and the like.

[0060] The content of the anionic surfactant in the PVA film is not limited as long as it does not affect the effects of the present invention, but for example, it is 0.5 to 1.5 parts by mass per 100 parts by mass of PVA.

[0061] Examples of nonionic surfactants include alkyl ether types (linear or branched alkyl ether types) such as polyoxyethylene alkyl ethers (polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, etc.) and polyoxypropylene alkyl ethers; ester types such as polyoxyethylene sorbitan fatty acid esters; ester ether types such as polyoxyethylene sorbitan monolaurate; amino ether types such as polyoxyethylene lauryl amino ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; alkylamine types such as polyoxyethylene lauryl amino ether; alkylamide types such as polyoxyethylene laurate; polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether; alkanolamide types such as lauric acid diethanolamide and oleic acid diethanolamide; and allylphenyl ether types such as polyoxyalkylene allylphenyl ether.

[0062] The content of the nonionic surfactant in the PVA film is not limited as long as it does not affect the effects of the present invention, but for example, it is 0.3 to 1.2 parts by mass per 100 parts by mass of PVA.

[0063] The lower limit of the total content of PVA and optional components such as water, plasticizers, and surfactants in the PVA film may be, for example, 90% by mass, 95% by mass, 98% by mass, 99% by mass, 99.5% by mass, or 99.9% by mass. The upper limit of the total content of PVA and optional components such as water, plasticizers, and surfactants in the PVA film may be 100% by mass.

[0064] PVA film may contain fillers. By including fillers, the mechanical strength and handling properties of the film can be improved.

[0065] Examples of fillers include carbon black, metal powder, silica, alumina, calcium carbonate, titanium dioxide, talc, mica, and clay minerals such as bentonite. Among these, talc, mica, and clay minerals are preferred.

[0066] The upper limit of the filler content in the PVA film is preferably 20 parts by mass, and more preferably 10 parts by mass, per 100 parts by mass of PVA. The lower limit of the filler content in the PVA film may be 0 parts by mass, 0.1 parts by mass, 0.5 parts by mass, or 1 part by mass, per 100 parts by mass of PVA.

[0067] Examples of starches include natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, and sago starch; and modified starches that have undergone etherification, esterification, oxidation, etc., with modified starches being preferred.

[0068] The lower limit of the starch content in a PVA film is preferably 1 part by mass, and more preferably 2 parts by mass, per 100 parts by mass of PVA. A starch content above this lower limit enhances the mechanical strength of the film. The upper limit of the starch content in a PVA film is preferably 15 parts by mass, and more preferably 10 parts by mass, per 100 parts by mass of PVA. A starch content below this upper limit improves the film's passability during manufacturing.

[0069] Other polymers besides PVA are preferably water-soluble polymers due to their affinity with PVA. Examples include dextrin, gelatin, glue, casein, shellac, gum arabic, polyacrylamide, sodium polyacrylate, polyvinyl methyl ether, copolymer of methyl vinyl ether and maleic anhydride, copolymer of vinyl acetate and itaconic acid, polyvinylpyrrolidone, cellulose, acetylcellulose, acetylbutylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, and sodium alginate.

[0070] The upper limit of the content of water-soluble polymers other than PVA in the PVA film is preferably 15 parts by mass, and more preferably 10 parts by mass, per 100 parts by mass of PVA. The lower limit of the content of water-soluble polymers other than PVA in the PVA film may be 0 parts by mass, 0.1 parts by mass, 0.5 parts by mass, or 1 part by mass, per 100 parts by mass of PVA.

[0071] The PVA film may further contain other components besides those listed above, to the extent that they do not impede the effects of the present invention. Examples of other components include antioxidants, ultraviolet absorbers, lubricants, crosslinking agents, colorants, preservatives, and fungicides.

[0072] The PVA film (bagging film) may have a coated layer formed on its inner surface (the inner surface in the vacuum bag state) by coating with an emulsion solution. Methods for providing a coated layer to the film include coating treatment using a liquid coating agent, such as the roll coater method, air doctor method, blade coater method, spray method, and dip method.

[0073] Coating agents used to form a coating layer include styrene resin emulsions, emulsions containing (meth)acrylic acid ester / styrene copolymers, (meth)acrylic resin emulsions, aqueous solutions of polyvinyl alcohol, polyvinyl alcohol emulsions, aqueous solutions of silicone water repellents, and silicone emulsions.

[0074] Of these, any of the following is preferred: styrene resin emulsion, emulsion containing (meth)acrylic acid ester / styrene copolymer, (meth)acrylic resin emulsion, aqueous polyvinyl alcohol solution, and polyvinyl alcohol emulsion.

[0075] There are no particular restrictions on the dispersant used to disperse the fine particles contained in the emulsion, but it is preferable to use PVA because it has strong adhesion to the PVA film body (the part other than the coating layer), suppresses peeling of the coating layer, and has excellent release properties from the molded article. The PVA is appropriately selected from the PVA used in the PVA film.

[0076] The average particle size of the fine particles contained in the emulsion is not particularly limited, but may be, for example, 0.02 to 0.5 μm or 0.05 to 0.3 μm.

[0077] The amount of coating used in the coating process to create the coating layer is not particularly limited, but for example, the amount of resin particles contained in the emulsion is 0.005 to 0.05 g / m² per side. ２ It may also be 0.01 to 0.03 g / m ２ That's fine.

[0078] The surface of the coating layer provided on the PVA film may be further coated with powder. Examples of powders include organic powders and inorganic powders. Examples of organic powders include starch. Examples of starches include natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, and sago starch; and modified starches that have undergone etherification, esterification, oxidation, water-repellent treatment, etc. Among these, modified starches are preferred, and water-repellent modified starches are more preferred. Examples of inorganic powders include silica, heavy, light or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium dioxide, diatomaceous earth, barium sulfate, calcium sulfate, zeolite, zinc oxide, silicic acid, silicates, mica, magnesium carbonate, kaolin, halosite, pyroferrite, sericite and other clays, talc, etc. These may be used individually or in mixtures of two or three or more types.

[0079] There is no limit to the average particle size of the powder, but when the average particle size of the powder is within a specific range, surface irregularities are formed appropriately, resulting in better release properties from the molded article. For this reason, the lower limit of the average particle size of the powder is preferably 5 μm, and more preferably 10 μm. On the other hand, the upper limit of the average particle size of the powder is preferably 30 μm, and more preferably 20 μm.

[0080] The amount of powder adhering to the PVA film is, for example, 0.1 to 100 mg / m². ３ That is acceptable. The upper limit for the amount of adhesion is 50 mg / m². ３ It may also be 30 mg / m² ３This is also acceptable. The lower limit of the amount of adhesion is 0.5 mg / m². ３ It may also be 1 mg / m² ３ That's fine.

[0081] The powder may be coated on one side of the PVA film, or on both sides. However, from the viewpoint of obtaining good release properties regardless of the orientation of the film, coating on both sides may be preferable.

[0082] In one embodiment of the present invention, the PVA film may not have a coating layer. The PVA film may not be coated with powder. For example, the PVA film may be a single-layer film. In one layer of the single-layer PVA film, PVA and other optional components are substantially uniformly present. The amount of powder adhering to the PVA film is 10 mg / m². ３ It may also be less than 1 mg / m² ３ It may also be less than 0.1 mg / m². ３ It may also be less than 0.1 mg / m². ３ It may be less than this. Thus, even if the PVA film is a single-layer film or a film in which powder is not substantially attached to the surface, it can be used as a bagging film that can fully achieve good effects.

[0083] The lower limit of the Young's modulus of PVA film at 23°C / 50% RH is 25 N / mm². ２ It may also be 50 N / mm ２ , 100 N / mm ２ Or 150 N / mm ２ This may also be the case. On the other hand, the upper limit of the Young's modulus is 350 N / mm ２ Preferably, 300 N / mm ２ More preferably, 250 N / mm ２ , 200 N / mm ２ , 150 N / mm ２ Or 100 N / mm ２This may also be the case. By setting the Young's modulus of the PVA film to a smaller value within the aforementioned range, particularly sufficient flexibility is achieved, and the conformability when used as a bagging film is further improved. The Young's modulus of the PVA film can be adjusted, for example, by the type and content of the plasticizer, the type of PVA, etc.

[0084] The average thickness of the PVA film is not particularly limited as long as it does not impair the effects of the present invention, but the lower limit is preferably 20 μm, and more preferably 25 μm. By setting the average thickness of the PVA film to be above the lower limit, the strength, peelability, workability, etc. of the PVA film can be improved. On the other hand, the upper limit is preferably 100 μm, more preferably 80 μm, and even more preferably 60 μm. By setting the average thickness of the PVA film to be below the upper limit, the conformability, workability, etc. can be improved. Also, by setting the average thickness of the PVA film to be below the upper limit, removal by washing with water tends to be easier. The average thickness of the PVA film is the average value of the thickness at any five locations.

[0085] The PVA film may be a stretched film or an unstretched film, but an unstretched film is preferred. By using an unstretched PVA film as a bagging film, effects such as conformability are more fully realized. An unstretched film is a film that has not undergone substantially any stretching treatment. An unstretched film may be a film with a length-based stretching ratio of 1.0x or more and 1.1x or less, or a stretched film with a length-based stretching ratio of 1.00x or more and 1.01x or less.

[0086] In PVA films used as bagging films, it is preferable that the surface is not embossed. Embossing is generally a processing method in which the film is nipped between an embossing roll and a rubber roll while applying heat and pressure after the film has been formed. PVA films that are not embossed have advantages such as high surface smoothness and excellent release properties.

[0087] Although not limiting to the present invention, a water-soluble PVA film can be used as the bagging film. In the present invention, by using a water-soluble PVA film, the bagging film can be dissolved in water after molding, thereby improving the efficiency of operations such as autoclave molding.

[0088] In one embodiment of the present invention, the heat-treated film obtained by heating a PVA film used as a bagging film at 130°C for 120 minutes is preferably completely soluble in pure water at 70°C or lower. That is, it is preferable that the PVA film has sufficient water solubility even after being heated under predetermined conditions. Hereinafter, the temperature of pure water at which the heat-treated film obtained by heating a PVA film at 130°C for 120 minutes completely dissolves is also referred to as the complete dissolution temperature of the heat-treated film. The complete dissolution temperature of the heat-treated film is preferably 70°C or lower, more preferably 60°C or lower, even more preferably 50°C or lower, even more preferably 45°C or lower, and may also be 40°C or lower. The complete dissolution temperature of the heat-treated film may be 5°C or higher, 10°C or higher, or 15°C or higher.

[0089] Regarding the complete dissolution temperature of a heat-treated film obtained by heating a PVA film at 130°C for 120 minutes, the complete dissolution temperature tends to decrease by lowering the degree of saponification of PVA, the main component of the PVA film, and by increasing the amount of modification. Furthermore, the complete dissolution temperature also tends to decrease by making the PVA film thinner and increasing the plasticizer content. In addition, it can be adjusted by the film formation conditions, drying conditions, and heat treatment conditions during the manufacturing of the PVA film. The complete dissolution temperature is specifically measured by the method described in the examples below.

[0090] In one embodiment of the present invention, the heat of fusion of a PVA film measured using differential scanning calorimetry (DSC) in accordance with ISO 11357-2,3 (2011) at a heating rate of 10°C / min may be 10 to 35 J / g or 12 to 30 J / g. A low heat of fusion indicates low crystallinity of the PVA film, and such a PVA film has higher water solubility after molding, and when attempting to remove the vacuum bag with water after molding, less residue from the film remains. Furthermore, when the heat of fusion is within the above range, the PVA film has an appropriate hardness, which has advantages such as making it easier to manufacture the vacuum bag. The heat of fusion tends to be lowered by lowering the degree of saponification of PVA, the main component of the PVA film, and by increasing the amount of modification. The heat of fusion also tends to be lowered by increasing the content of plasticizers. Furthermore, the film formation conditions, drying conditions, heat treatment conditions, etc., used in the manufacturing of PVA film can also be adjusted.

[0091] <Vacuum Bag Molding System> A vacuum bag molding system according to one embodiment of the present invention comprises a vacuum bag and a vacuum valve. Inside the vacuum bag is a laminate having an uncured reinforced fiber composite material placed directly on a mold or via other components, and a breather placed in direct contact with the uncured reinforced fiber composite material. The vacuum bag molding system may also include a hose connecting the inside and outside of the vacuum bag. Furthermore, a release film or the like may be placed inside the vacuum bag. The details will be explained below with reference to the figures.

[0092] (Vacuum bag molding system of Figure 1) The vacuum bag molding system of Figure 1, which is the first embodiment, comprises a mold 10, an uncured reinforced fiber composite material 12, a breather 13, a release film 14, a bagging film 15, and a vacuum valve 16. Specifically, in the vacuum bag molding system of Figure 1, the reinforced fiber composite material 12 is placed on the mold 10 (the central part of the mold 10) via a release agent 11, and the breather 13 is placed directly on the reinforced fiber composite material 12. The bagging film 15 is placed so as to cover the laminate 17 having the reinforced fiber composite material 12 and the breather 13. The release film 14 is placed between the laminate 17 and the bagging film 15 (between the breather 13 and the bagging film 15). The peripheral portion where the mold 10 and the bagging film 15 overlap is sealed with a sealing tape 18 as an example of a sealing member. In the vacuum bag molding system of the form of Figure 1, a vacuum bag 19 is formed by the mold 10 and the bagging film 15. In other words, the vacuum bag molding system in the form shown in Figure 1 comprises a vacuum bag 19, and a laminate 17 of a reinforced fiber composite material 12 and a breather 13 is housed inside the vacuum bag 19. The reinforced fiber composite material 12 is placed on the mold 10 via a release agent 11, but it may also be placed directly on the mold 10. The mold 10 also constitutes part of the vacuum bag 19. The vacuum valve 16 is positioned inside the vacuum bag 19 so that its connection point (exhaust port) to an exhaust device (not shown) is exposed from the vacuum bag 19 in order to exhaust the inside of the vacuum bag 19. When exhaust is performed, the inside of the vacuum bag 19, which is the space sealed by the sealing tape 18 between the mold 10 and the bagging film 15, becomes a vacuum.

[0093] Although the mold 10 is shown as a plate in Figure 1, its shape can be appropriately changed according to the shape of the target molded product. The vacuum bag molding system according to one embodiment of the present invention can also be applied to molding using molds with complex shapes that have uneven surfaces. The material of the mold 10 is not particularly limited, and metal molds such as aluminum and steel, pearl board molds, FRP (Fiber Reinforced Plastics) molds, etc., can be used.

[0094] The release agent 11 is applied to the mold 10 (the surface on which the reinforced fiber composite material 12 is placed) to improve the release properties of the molded product (reinforced fiber composite material 12 after molding) from the mold 10. The release agent 11 is not required to be applied. That is, the reinforced fiber composite material 12 may be placed directly on the mold 10, or it may be placed via other components such as the release agent 11. Also, as in the vacuum bag molding system shown in Figure 2 described later, a breather 13 may be placed between the mold 10 and the reinforced fiber composite material 12. A release film may be placed between the mold 10 and the reinforced fiber composite material 12 instead of or together with the release agent 11.

[0095] There are no particular restrictions on the release agent 11, and it can be selected according to the material of the mold or prepreg. Examples of release agents include silicone-based, acrylic-based, urethane-based, urethane acrylate-based materials, fluoropolymer-based materials, or combinations thereof.

[0096] The reinforcing fiber composite material 12 is placed in the central part of the mold 10. That is, the reinforcing fiber composite material 12 is not placed in the peripheral part of the mold 10 (the part where the vacuum valve 16 and sealing tape 18 are provided in Figure 1).

[0097] The uncured reinforced fiber composite material is the material for the target molded article. Typically, the uncured reinforced fiber composite material consists of reinforcing fibers impregnated with a matrix resin. The reinforced fiber composite material to be placed is uncured, but may be partially cured or semi-cured. Conventionally known reinforced fiber composite materials can be used.

[0098] The type of matrix resin is not particularly limited, but it is usually a thermosetting resin. Examples of matrix resins include epoxy resins, phenolic resins, unsaturated polyester resins, cyanate ester resins, phenol-formaldehyde resins, and melamine resins, with epoxy resins being preferred. Such resins have particularly good release properties from PVA films.

[0099] The matrix resin may contain various known curing agents depending on the type of resin. For example, when the matrix resin is an epoxy resin, examples of curing agents include amines, amides, imidazoles, acid anhydrides, etc.

[0100] Examples of reinforcing fibers used in reinforced fiber composite materials include artificially produced fibers such as carbon fibers, glass fibers, ceramic fibers, aramid fibers, boron fibers, basalt fibers, steel fibers, nylon fibers, fiber mats, scrim, and woven fabrics; natural fibers such as flax, hemp, jute, ramie, kenaf, sisal, bamboo, silk, cotton, and wood; and semi-natural fibers such as cellulose nanofibers. Two or more of these reinforcing fibers may be used in combination.

[0101] As the reinforcing fiber, carbon fiber or natural fiber is preferred, and carbon fiber is more preferred. That is, the reinforcing fiber composite material may be a carbon fiber composite material, and the reinforcing fiber composite molded body obtained by the vacuum bag molding system or manufacturing method according to one embodiment of the present invention may be a carbon fiber composite molded body.

[0102] In the vacuum bag molding system shown in Figure 1, the breather 13 is positioned so as to be in direct contact with the upper surface of the reinforced fiber composite material 12. The breather 13 is a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less. The specific form and preferred form of the nonwoven fabric that constitutes the breather 13 are as described above. The breather 13 can be used with one or more layers of the nonwoven fabric.

[0103] The release film 14 is placed between the vacuum bag 19 and the laminate 17. Specifically, the release film 14 is placed between the breather 13 and the bagging film 15. By providing such a release film 14, the bagging film 15 can be easily peeled off from the resulting molded product. As the release film 14, fluororesin (polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene hexafluoropropylene copolymer, etc.) film, PVA film, polymethylpentene film, polyolefin (polyethylene, polypropylene, etc.) film, etc. can be used. These films can also be used as a release film that may be placed between the mold 10 and the reinforced fiber composite material 12.

[0104] Conventional known films can be used for the bagging film 15. Examples of bagging films 15 include polyamide films, polyolefin films, fluororesin films, polyester films, and PVA films. While PVA films are preferred as the bagging film 15 in terms of release properties and conformability, other types of bagging films can also be used as appropriate. If a release film 14 is placed between the bagging film 15 and the laminate 17, the release properties of the bagging film 15 itself do not need to be given special consideration.

[0105] The vacuum bag forming system in Figure 1 includes a vacuum valve 16 to evacuate the inside of the vacuum bag 19 and isolate the inside from the outside of the vacuum bag 19. That is, the vacuum valve 16 is provided to be able to evacuate the inside of the vacuum bag 19 and maintain a vacuum state inside the vacuum bag 19. One opening of the vacuum valve 16 is connected to the internal space of the vacuum bag 19, and the other opening (exhaust port) is connected to an exhaust device (not shown) such as a vacuum pump located outside the vacuum bag 19. In the vacuum bag system in Figure 1, the body of the vacuum valve 16 is located inside the vacuum bag 19. In other embodiments, the vacuum valve 16 may be located outside the vacuum bag 19. When the vacuum valve 16 is installed inside the vacuum bag 19, a minimal cut can be made in the vacuum bag 19 (usually the bagging film 15 that constitutes the vacuum bag 19) to expose the exhaust port of the vacuum valve 16 to the outside of the vacuum bag 19, and the cut can be reinforced to prevent leakage. If the vacuum valve 16 is to be installed on the outside of the vacuum bag 19, for example, a hose can be provided to connect the inside and outside of the vacuum bag 19, and the vacuum valve 16 can be installed on the outside.

[0106] In the vacuum bag molding system shown in Figure 1, as described above, the area where the mold 10 and the bagging film 15 overlap is sealed with a sealing tape 18 (sealant tape) as an example of a sealing member. That is, the sealing tape 18 that adheres the mold 10 and the bagging film 15 is used as the sealing area of ​​the vacuum bag 19. As another form of the sealing area, the area where the bagging films 15 overlap may be sealed with the sealing tape 18 and used as the sealing area. Furthermore, the sealing means is not limited to the method using the sealing tape 18, but adhesives may be used, or the bagging films 15 may be directly bonded together by heat pressing or other means.

[0107] The sealing portion (sealing tape 18 in the vacuum bag forming system shown in Figure 1) is preferably located at a suitable distance from the reinforced fiber composite material 12 (for example, 10 cm to 50 cm away). By maintaining a suitable distance between the reinforced fiber composite material 12 and the sealing portion (for example, the location of the sealing tape 18), tearing of the vacuum bag 19 (bagging film 15) and air pockets are less likely to occur. By not making the distance between the reinforced fiber composite material 12 and the sealing portion too large, workability can be improved.

[0108] (Vacuum bag molding system of Figure 2) The vacuum bag molding system of Figure 2, which is a second embodiment, comprises a mold 10, an uncured reinforced fiber composite material 12, a breather 13, a bagging film 15, and a vacuum valve 16. Specifically, in the vacuum bag molding system of Figure 2, the breather 13 is placed on the mold 10 (the central part of the mold 10) via a release agent 11, and the reinforced fiber composite material 12 is placed directly on the breather 13. The bagging film 15 is then placed to cover the laminate 17 having the reinforced fiber composite material 12 and the breather 13. The peripheral portion where the mold 10 and the bagging film 15 overlap is sealed with a sealing tape 18, which is an example of a sealing member. In the vacuum bag molding system of the form of Figure 2, a vacuum bag 19 is formed by the mold 10 and the bagging film 15. That is, the vacuum bag molding system of the form of Figure 2 comprises a vacuum bag 19, and the laminate 17 of the reinforced fiber composite material 12 and the breather 13 is housed inside this vacuum bag 19. The reinforced fiber composite material 12 is placed on the mold 10 via a release agent 11 and a breather 13. The breather 13 is placed on the mold 10 via the release agent 11, but it may also be placed directly on the mold 10. The mold 10 also constitutes part of the vacuum bag 19. The vacuum valve 16 is placed inside the vacuum bag 19 so that the connection point (exhaust port) to the exhaust device (not shown) is exposed from the vacuum bag 19 in order to exhaust the inside of the vacuum bag 19. When exhaust is performed, the inside of the vacuum bag 19, which is the space sealed by the sealing tape 18 between the mold 10 and the bagging film 15, becomes a vacuum.

[0109] Unlike the vacuum bag molding system in Figure 1, the vacuum bag molding system in Figure 2 has the breather 13 side of the laminate 17, which consists of the reinforced fiber composite material 12 and the breather 13, located on the mold 10 side. Also, in the vacuum bag molding system in Figure 2, the release film 14 is not placed between the laminate 17 and the bagging film 15 (between the reinforced fiber composite material 12 and the bagging film 15).

[0110] In the vacuum bag molding system shown in Figure 2, a PVA film is used as the bagging film 15. That is, the vacuum bag 19 has a PVA film as the bagging film 15. This PVA film as the bagging film 15 is provided in direct contact with the uncured reinforced fiber composite material 12. As described above, the PVA film has good peelability and conformability to the uncured reinforced fiber composite material 12 or the molded article formed from this reinforced fiber composite material 12. Furthermore, since the PVA film is water-soluble, it can be removed by washing with water after use. For this reason, the form in which the vacuum bag 19 has a PVA film as the bagging film 15, and furthermore, the form in which such a PVA film (bagging film 15) is in direct contact with the uncured reinforced fiber composite material 12, is a preferred embodiment of the present invention. In this configuration, the bagging film 15, which is a PVA film, can be removed by washing with water, and there is no need to provide a release film between the laminate 17 having the reinforced fiber composite material 12 and the vacuum bag 19 (bagging film 15), which has advantages such as further reduction of waste. In addition, in the vacuum bag molding system of the configuration shown in Figure 2, auxiliary materials (release film, breather, etc.) may be placed between the laminate 17 having the reinforced fiber composite material 12 and the vacuum bag 19 (bagging film 15).

[0111] The specific form and preferred form of the PVA film used as the bagging film 15 are as described above. When multiple bagging films are used in a vacuum bag, it is preferable to use PVA film for at least one of them, and it is more preferable to use PVA film for all of the bagging films.

[0112] The specific and preferred forms of the mold 10, release agent 11, uncured reinforced fiber composite material 12, breather 13, vacuum valve 16, sealing tape 18, etc., used in the vacuum bag molding system shown in Figure 2 are as described above. They are the same as the components used in the vacuum bag molding system shown in Figure 1.

[0113] <Method for Manufacturing Reinforced Fiber Composites> A method for manufacturing reinforced fiber composites according to one embodiment of the present invention is a method for manufacturing a reinforced fiber composite molded article using a vacuum bag molding system according to one embodiment of the present invention, comprising the steps of: discharging air from inside the vacuum bag from the vacuum valve (step B); and heat-curing the uncured reinforced fiber composite material contained in the vacuum bag (step C).

[0114] In the method for manufacturing the reinforced fiber composite molded article, a nonwoven fabric made from fibers mainly composed of a thermoplastic resin with a glass transition temperature of 100°C or less is used as the breather. Therefore, during heat curing in step C, the breather melts on the surface of the reinforced fiber composite material, and a reinforced fiber composite molded article is obtained in which the reinforced fiber composite material and the breather are integrated. As a result, the breather does not become waste, and the surface appearance of the resulting molded article is also good.

[0115] The method for manufacturing the reinforced fiber composite may further include a step (step A) for assembling a vacuum bag molding system. The following describes the process starting from step A.

[0116] In step A, first, the uncured reinforced fiber composite material and the breather are placed on the mold, either directly or via other components. Before placing the uncured reinforced fiber composite material, a release agent may be applied to the surface of the mold, or a release film may be placed. The layering order of the reinforced fiber composite material and the breather is not particularly limited; they may be layered in the order of reinforced fiber composite material 12 and breather 13, as in the vacuum bag molding system of Figure 1, or they may be layered in the order of breather 13 and reinforced fiber composite material 12, as in the vacuum bag molding system of Figure 2.

[0117] Next, the laminate containing the reinforced fiber composite material and the breather is covered with a bagging film via a release film or the like as needed, and sealed with sealing tape to form a vacuum bag. At this time, a vacuum valve is provided in the vacuum bag so that air can be discharged in the next step. In the case of vacuum bag molding systems with other structures, a cylindrical or bag-shaped vacuum bag may be made first using a bagging film, and the mold, reinforced fiber composite material, breather, etc. may be placed inside the vacuum bag, and the vacuum bag may be sealed with sealing tape.

[0118] In process B, the air inside the vacuum bag is expelled through the vacuum valve. At this time, the vacuum valve is connected to the exhaust device to expel the air from inside the vacuum bag. If wrinkles have formed in the vacuum bag (bagging film) after exhausting, the wrinkles can be eliminated by returning a small amount of air to the vacuum bag and then expelling it again.

[0119] After step B (the step of discharging the air inside the vacuum bag 19 from the vacuum valve 16), it is preferable that the bagging film 15 and the contents contained in the vacuum bag 19 (for example, the release film 14 in the case of the vacuum bag molding system in Figure 1, and for example, the reinforced fiber composite material 12 in the case of the vacuum bag molding system in Figure 2) are in close contact. By performing step C with the bagging film 15 and the contents contained in the vacuum bag 19 in close contact in this way, a reinforced fiber composite molded body with a particularly good surface shape can be obtained.

[0120] In step C, the uncured reinforced fiber composite material contained in the vacuum bag is heat-cured. Step C can be carried out in the same manner as conventionally known autoclave molding. That is, while referring to the general manufacturing conditions for reinforced fiber composite molded articles, the pressure and temperature inside the autoclave should be adjusted according to the desired shape and properties of the molded article, taking into account the curing temperature and curing rate of the thermosetting resin constituting the uncured reinforced fiber composite material used.

[0121] The heating temperature in step C is preferably 10°C or more higher than the glass transition temperature of the thermoplastic resin, which is the main component of the fibers forming the nonwoven fabric used as a breather, more preferably 20°C or more higher, and even more preferably 30°C or 40°C or more higher. The lower limit of the heating temperature in step C is preferably 110°C, more preferably 120°C. The upper limit of the heating temperature in step C may be 250°C, or 200°C, 180°C, 160°C, 150°C, or 140°C.

[0122] Through heat curing, the reinforced fiber composite material placed inside the vacuum bag hardens and the breather melts, resulting in a reinforced fiber composite molded body in which the reinforced fiber composite material and the breather are integrated. Therefore, this method of manufacturing a reinforced fiber composite molded body does not result in waste from the breather, thus reducing waste. Furthermore, the reinforced fiber composite molded body obtained in which the breather has sufficiently melted and integrated with the surface of the reinforced fiber composite material has a good surface appearance.

[0123] The method for manufacturing the reinforced fiber composite may further include a step (step D) after step C in which the bagging film constituting the vacuum bag is removed. Here, if the bagging film is a PVA film, the bagging film can be removed by washing with water. In this case, hot water may be used to efficiently dissolve the PVA film. By removing the PVA film by washing with water in this way, waste can be further reduced.

[0124] <Other Embodiments> The present invention is not limited to the embodiments described above, and its configuration can be modified without altering the essence of the invention. For example, the vacuum bag molding system and the method for manufacturing reinforced fiber composite molded articles of the present invention can also be applied to molding methods other than autoclave molding.

[0125] The layer structure of the laminate containing an uncured reinforced fiber composite material and a breather, which is housed inside the vacuum bag in the vacuum bag molding system of the present invention, is not limited to the forms shown in Figures 1 and 2. When the reinforced fiber composite material is denoted as X and the breather as Y, with the left side being the upper part of the layer and the right side being the lower part of the layer (mold side), examples of the layer structure of the laminate include Y / X, X / Y, Y / X / Y, Y / X / Y / X, X / Y / X / Y, Y / X / Y / X / Y, X / Y / X / Y / X, etc.

[0126] In a laminate (a laminate containing an uncured reinforced fiber composite material and a breather, housed inside a vacuum bag), it is preferable that the breather is located on at least one of the two outermost layers (the outermost and innermost layers), more preferably on at least the outermost layer, and even more preferably on both outermost layers (the outermost and innermost layers). That is, it is preferable that the breather is located at least between the uncured reinforced fiber composite material and the bagging film (on the opposite side of the mold in the uncured reinforced fiber composite material), and more preferably both between the uncured reinforced fiber composite material and the bagging film, and between the uncured reinforced fiber composite material and the mold. For example, a preferred configuration is that 50% or more, 70% or more, or 90% or more of the surface of the uncured reinforced fiber composite material is covered by the breather. By arranging the breather in this way, the surface appearance of the resulting molded article is improved. That is, the surface appearance of the resulting molded article is improved when the breather is located on the opposite side of the mold from the uncured reinforced fiber material, rather than on the mold side. Furthermore, by placing breathers on both the mold side and the opposite side of the mold for the uncured reinforced fiber material, the surface appearance of the resulting molded product is further improved.

[0127] The reinforcing fiber composite material and the breather may each be single-layer or multi-layer, and can be appropriately selected according to the structure, physical properties, etc., of the desired reinforcing fiber composite molded product.

[0128] According to the present invention, it is possible to manufacture reinforced fiber composite molded articles that reduce waste compared to conventional methods and have a good surface appearance. Such reinforced fiber composite molded articles can be widely applied to a variety of products, from aircraft such as airplanes and helicopters, to vehicles such as motorcycles and automobiles, to wind turbine blades, fishing rods, golf shafts, rackets, and other leisure goods.

[0129] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way by these examples. The evaluation methods used in the examples and comparative examples are shown below.

[0130] [Weight-average molecular weight of thermoplastic phenoxy resin] The weight-average molecular weight (Mw) of thermoplastic phenoxy resin was determined as a standard polystyrene equivalent value by GPC (gel permeation chromatography). The measurement equipment and conditions were as follows: • Equipment: GPC8020 manufactured by Tosoh Corporation • Separation column: TSKgel G4000HXL manufactured by Tosoh Corporation • Detector: RI-8020 manufactured by Tosoh Corporation • Eluent: Tetrahydrofuran • Eluent flow rate: 1.0 ml / min • Sample concentration: 5 mg / 10 ml • Column temperature: 40°C

[0131] [Glass transition temperature (°C)] In accordance with JIS K 7121, 10 mg of the resin to be measured was placed in an aluminum pan, and the thermogram was measured by differential scanning calorimetry (DSC) under a heating rate of 10°C / min to determine the glass transition temperature.

[0132] [Balance weight of nonwoven fabric (A) (g / m²) ２ In accordance with JIS L 1906, three 20cm x 20cm sample pieces were taken from 1m of nonwoven fabric width, and the mass of each sample piece was measured using an electronic balance. The average of the three points was then used for the test piece area of ​​400cm². ２ The mass per unit area was calculated by dividing by this value and was defined as the basis weight (A) of the nonwoven fabric.

[0133] [Air permeability of nonwoven fabric (B) (cm ３ / cm ２・s) ] In accordance with JIS L 1096 6.27.1 (Method A: Fragile method), the same sample piece was used for basis weight measurement, and for each sample piece, an air permeability meter (TEXTEST (Switzerland): FX3300) was used, with a measurement area of ​​38 cm². ２ The measurement was performed under a pressure of 125 Pa, and the average of the three points was taken as the air permeability of the nonwoven fabric (B).

[0134] [Average fiber diameter (μm) of the fibers constituting the nonwoven fabric] The average fiber diameter of the fibers was determined by taking a scan electron microscope image at 1,000x magnification of an arbitrary point in the nonwoven fabric, measuring the diameter of 100 randomly selected fibers, and taking the average of the measured values.

[0135] [Density of Nonwoven Fabrics] The density of nonwoven fabrics was calculated using the following formula. A lower value indicates higher density. Density = Air permeability (B) / Basis weight (A)

[0136] [Appearance of Reinforced Fiber Composite Molded Articles] The surface appearance of reinforced fiber composite molded articles (cloudiness, presence or absence of trapped air) was visually observed and judged according to the following indicators. Note that if trapped air is present, wrinkles and other appearance defects resulting from the trapped air will occur on the surface of the molded article. A: There was no cloudiness, and no trapped air was observed even when powder was applied to the surface of the molded article to make it easier to see, resulting in a very good appearance. B: There was no cloudiness, no visible trapped air, and the appearance was good. When powder was applied to the surface of the molded article to make it easier to see, trapped air was observed. C: There was some cloudiness and trapped air, but the appearance did not affect practical use. D: There was a lot of cloudiness and trapped air, resulting in a poor appearance.

[0137] [Waste Reduction] In the following examples or comparative examples, if the breather melts during the process of manufacturing the reinforced fiber composite molded body and becomes integrated with the reinforced fiber composite material, resulting in the acquisition of the reinforced fiber composite molded body without any breather remaining as waste, it is determined that waste has been reduced. On the other hand, if the breather does not melt during the process of manufacturing the reinforced fiber composite molded body and does not become integrated with the reinforced fiber composite molded body, resulting in the remaining breather as waste, it is determined that waste has not been reduced.

[0138] [Late of Fusion (°C)] In accordance with ISO 11357-2,3 (2011), 3.6 mg of the film to be measured was placed in an aluminum pan, and the thermogram was measured by differential scanning calorimetry (DSC) under a heating rate of 10°C / min to determine the latend of fusion. The film used for measurement was first vacuum-dried in a vacuum dryer set to 52°C for 90 minutes before measurement.

[0139] [Solubility Test of Unheated Film] The complete dissolution temperature of the unheated films produced in Production Examples 4-7 was measured using the following procedure: (1) A rectangular sample measuring 40 mm in length and 35 mm in width was cut from the film. The sample was then sandwiched and fixed between two 50 mm x 50 mm plastic plates, each with a rectangular window (hole) measuring 35 mm in length and 25 mm in width, so that the length of the sample was parallel to the length of the window and the sample was positioned approximately in the center of the width of the window. (2) 500 mL of deionized water (pure water) prepared to each temperature was placed in a 750 mL beaker, and the water temperature was adjusted to the measurement temperature ± 1.0 °C while stirring with a magnetic stirrer equipped with a 5 cm bar so that the vortex caused by stirring was approximately one-fifth of the water volume. (3) The sample fixed to the plastic plate in (1) was immersed in the deionized water in the beaker, taking care not to let it come into contact with the bar of the magnetic stirrer. (4) The time it took for the sample to completely disappear after being immersed in deionized water was measured. The water temperature was started at 30°C, and if the sample did not completely dissolve within 3 minutes, the temperature was increased by 10°C increments. That is, for example, if the sample did not completely disappear in 3 minutes in 30°C deionized water, a new sample was immersed in 40°C deionized water, and the time it took for the sample to completely disappear was measured. The complete dissolution temperature of the film was determined using the above procedure. Note that "complete disappearance of the sample" means that no visible undissolved film remains are visible. If the film contains visible fillers, such fillers are not included in the undissolved film.

[0140] [Solubility Test of Heat-Treated Films] The films prepared in Production Examples 4-7 (unheated films) were heat-treated in a hot air dryer at 130°C for 120 minutes to obtain heat-treated films. The complete dissolution temperature of the heat-treated films was measured using the same method as in the solubility test of the unheated films described above.

[0141] [Manufacturing Example 1] (Preparation of continuous long fiber nonwoven fabric A) Amorphous bisphenol A (BPA) type phenoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., "YP-50s") with a weight-average molecular weight of 60,000 and a glass transition temperature of 84°C was spun at a spinning temperature of 355°C, a hot air temperature of 340°C, and 11.3 Nm per 1 m of nozzle width. ３ By spraying, the continuous long-fiber nonwoven fabric A has a basis weight (A) of 12.4 g / m². ２ The breathability (B) is 126 cm ３ / cm ２ A meltblown nonwoven fabric with an average fiber diameter of 5.8 μm and an average thickness of 0.19 mm / sheet was obtained. The obtained nonwoven fabric had a ratio (air permeability (B) / basis weight (A)) of 100 or less and exhibited excellent density.

[0142] [Manufacturing Example 2] (Preparation of Continuous Long Fiber Nonwoven Fabric B) A polyetherimide resin (ULTEM9001, manufactured by Savic Innovative Plastics) with a glass transition temperature of 217°C is blown at a spinning temperature of 420°C, a hot air temperature of 420°C, and an air volume of 0.4 MPa to produce continuous long fiber nonwoven fabric B with a basis weight (A) of 10 g / m². ２ , with a breathability rating (B) of 100 cm ３ / cm ２ A meltblown nonwoven fabric with an average fiber diameter of 2.2 μm and a thickness of 0.12 mm / sheet was obtained. The obtained nonwoven fabric had an air permeability (B) / basis weight (A) of 100 or less and exhibited excellent density.

[0143] [Manufacturing Example 3] (Manufacturing of Film (PVA-1)) A film-forming stock solution with a volatile content of 68%, consisting of 100 parts by mass of PVA (degree of polymerization 2,400, degree of saponification 99.4 mol%), 13 parts by mass of glycerin as a plasticizer, 0.1 parts by mass of lauric acid diethanolamide as a surfactant, and water, was melt-extruded from a T-die onto a metal roll at 90°C, dried, and then heat-treated with a heat-treated roll at a surface temperature of 120°C to obtain a PVA film with an average thickness of 50 μm. The obtained PVA film was then surface-coated. Methyl methacrylate / styrene copolymer was applied to both sides of the PVA film by dip method at a rate of 0.020 g / m² per side. ２ The film (PVA-1) was obtained by applying the material in the specified ratio and drying it with hot air at 100°C for 30 seconds. For the surface coating treatment, an emulsion of methyl methacrylate / styrene copolymer (methyl methacrylate units / styrene units (molar ratio) = 50 / 50) with an average particle size of 0.1 μm was added to an aqueous solution containing 1.5% by mass of PVA with a degree of polymerization of 2,400 and a degree of saponification of 99.2 mol% in a mass ratio of 3 / 1, and this emulsion was used as the coating solution. The Young's modulus of the film (PVA-1) was 240 N / mm². ２ That was the case.

[0144] [Manufacturing Example 4] (Manufacturing of Film (PVA-2)) An aqueous solution containing 100 parts by mass of PVA (degree of polymerization 1,700, degree of saponification 88.0 mol%, unmodified PVA), 15 parts by mass of glycerin as a plasticizer, 1.0 part by mass of sodium alkyl sulfonate as an anionic surfactant, 0.5 parts by mass of polyoxyethylene alkyl ether as a nonionic surfactant, and 3.0 parts by mass of starch, with a PVA content of 11.0% by mass, was prepared as a film-forming stock solution. The film-forming stock solution was cast onto a metal drum at 60°C and dried for 20 minutes. The dried film was peeled from the surface of the metal drum to produce a film (PVA-2) with an average thickness of 35 μm. The heat of fusion of the film (PVA-2), measured using DSC, was 27.8 J / g. Furthermore, for the film (PVA-2), the complete melting temperature of the unheated film was 30°C, and the complete melting temperature of the heat-treated film was 40°C. The Young's modulus of the film (PVA-2) is 44 N / mm². ２ That was the case.

[0145] [Production Example 5] (Production of Film (PVA-3)) Film (PVA-3) was produced in the same manner as in Production Example 4, except that PVA was changed to itaconic acid-modified PVA (saponified copolymer of vinyl acetate and itaconic acid) with a degree of polymerization of 1,700, a degree of saponification of 88.0 mol%, and an itaconic acid modification amount of 1.3 mol%. The heat of fusion of the film, measured using DSC, was 23.0 J / g. Furthermore, for film (PVA-3), the complete melting temperature of the unheated film was 30°C, and the complete melting temperature of the heat-treated film was 40°C. The Young's modulus of film (PVA-3) was 40 N / mm². ２ That was the case.

[0146] [Production Example 6] (Production of Film (PVA-4)) Film (PVA-4) was produced in the same manner as in Production Example 4, except that PVA was changed to AMPS-modified PVA (saponified copolymer of vinyl acetate and AMPS) with a degree of polymerization of 1,700, a degree of saponification of 88.0 mol%, and an AMPS ((meth)acrylamide alkyl sulfonic acid) modification amount of 2.0 mol%. The heat of fusion of film (PVA-4), measured using DSC, was 13.9 J / g. Furthermore, for film (PVA-4), the complete melting temperature of the unheated film was 30°C, and the complete melting temperature of the heat-treated film was also 30°C. The Young's modulus of film (PVA-4) was 33 N / mm². ２ That was the case.

[0147] [Manufacturing Example 7] (Manufacturing of Film (PVA-5)) Film (PVA-5) was manufactured in the same manner as in Manufacturing Example 4, except that the PVA was changed to unmodified fully saponified PVA with a degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and no modification. The heat of fusion of film (PVA-5), measured using DSC, was 57.8 J / g. Furthermore, for film (PVA-5), the complete melting temperature of the unheated film was 70°C, and the complete melting temperature of the heat-treated film was 80°C.

[0148] [Example 1] An uncured carbon fiber composite material (W-3101-A / Q-1120E (manufactured by Teijin Limited), consisting of three layers of carbon fibers impregnated with epoxy resin) was placed on a flat mold as a reinforcing fiber composite material. Before placing the uncured carbon fiber composite material, a release agent (ChemLease 2166, manufactured by ChemTrend Japan Co., Ltd.) was applied to the surface of the mold where the uncured carbon fiber composite material would be placed. On top of the uncured carbon fiber composite material, the meltblown nonwoven fabric A obtained in Manufacturing Example 1 was placed as a breather, and then a fluororesin film (currently manufactured by AEROVAC, A5000), which is a release film, was placed. Next, these were covered with a nylon film (AIRTECH, WL7400) as a bagging film to form a vacuum bag. Next, a vacuum valve for air discharge was installed inside the vacuum bag, and the vacuum bag was sealed with sealing tape. A small incision was made in the vacuum bag, and the tip of the vacuum valve for air discharge was exposed outside the vacuum bag, resulting in the vacuum bag molding system of Example 1 as shown in Figure 1.

[0149] A vacuum valve for air discharge was connected to the vacuum hose of the obtained vacuum bag molding system, and the air inside the vacuum bag was sucked out using a vacuum device. This was then placed in an autoclave. Heat curing was performed inside the autoclave while reducing the pressure inside the vacuum bag of the vacuum bag molding system (130°C for 2 hours, with an autoclave pressure of 0.5 MPa). After heat curing, the vacuum bag molding system was removed from the autoclave and allowed to cool to room temperature. Then, the inside of the vacuum bag was released to atmospheric pressure, and the carbon fiber composite molded body was removed to obtain a carbon fiber composite molded body (an example of a reinforced fiber composite molded body). The meltblown nonwoven fabric A used as a breather melted and was incorporated into the carbon fiber composite molded body, so no breather waste remained. Furthermore, the appearance evaluation of the obtained reinforced fiber composite molded body was "A".

[0150] [Example 2] On a flat mold, the meltblown nonwoven fabric A obtained in Manufacturing Example 1 was placed as a breather, and on top of that, an uncured carbon fiber composite material (three layers of W-3101-A / Q-1120E (manufactured by Teijin Limited) in which carbon fibers are impregnated with epoxy resin) was placed as a reinforcing fiber composite material. Before placing the meltblown nonwoven fabric A, a release agent (ChemLease 2166, manufactured by ChemTrend Japan Co., Ltd.) was applied to the surface of the mold where the meltblown nonwoven fabric A would be placed. These were then covered with the film (PVA-1) obtained in Manufacturing Example 3 as a bagging film to form a vacuum bag. Subsequently, a vacuum valve was installed using the same procedure as in Example 1, and the vacuum bag molding system of Example 2, as shown in Figure 2, was obtained.

[0151] Using the obtained vacuum bag molding system, autoclave molding was performed in the same procedure as in Example 1 to obtain a carbon fiber composite molded body (an example of a reinforced fiber composite molded body). The meltblown nonwoven fabric A used as a breather melted and was incorporated into the reinforced fiber composite molded body, so no breather waste remained. The appearance of the obtained reinforced fiber composite molded body was evaluated as "B".

[0152] [Example 3]

[0153] On a flat mold, the meltblown nonwoven fabric A obtained in Manufacturing Example 1 was placed as a breather, and on top of that, an uncured carbon fiber composite material (three layers of W-3101-A / Q-1120E (manufactured by Teijin Limited) in which carbon fibers are impregnated with epoxy resin) was placed as a reinforcing fiber composite material. Before placing the meltblown nonwoven fabric A, a release agent (ChemLease 2166, manufactured by ChemTrend Japan Co., Ltd.) was applied to the surface of the mold where the meltblown nonwoven fabric A would be placed. Furthermore, the meltblown nonwoven fabric A obtained in Manufacturing Example 1 was placed on top of the uncured carbon fiber composite material as a breather, and these were covered with the film (PVA-2) obtained in Manufacturing Example 4 as a bagging film to form a vacuum bag. After that, a vacuum valve was installed in the same procedure as in Example 1 to obtain the vacuum bag molding system of Example 3. That is, in Example 3, breathers were placed on both sides of the uncured carbon fiber composite material (mold side and bagging film side). Subsequently, autoclave molding was performed in the same manner as in Example 1. After autoclave molding, the vacuum bag was immersed in 40°C water, and the bagging film dissolved. Furthermore, the meltblown nonwoven fabric A used as a breather melted and was incorporated into the reinforced fiber composite molded body, so no breather waste remained. The appearance of the obtained reinforced fiber composite molded body was evaluated as "A".

[0154] [Example 4] Autoclave molding was performed in the same manner as in Example 3, except that the film (PVA-3) obtained in Production Example 5 was used as the bagging film. After autoclave molding, the vacuum bag was immersed in 40°C water, and the bagging film dissolved. In addition, the meltblown nonwoven fabric A used as the breather melted and was incorporated into the reinforced fiber composite molded body, and no breather waste remained. The appearance of the obtained reinforced fiber composite molded body was evaluated as "A".

[0155] [Example 5] Autoclave molding was performed in the same manner as in Example 3, except that the film (PVA-4) obtained in Production Example 6 was used as the bagging film. After autoclave molding, the vacuum bag was immersed in 40°C water, and the bagging film dissolved. In addition, the meltblown nonwoven fabric A used as the breather melted and was incorporated into the reinforced fiber composite molded body, and no breather waste remained. The appearance of the obtained reinforced fiber composite molded body was evaluated as "A".

[0156] [Example 6] Autoclave molding was performed in the same manner as in Example 4, except that the film (PVA-5) obtained in Production Example 7 was used as the bagging film. After autoclave molding, the vacuum bag was immersed in 40°C water, and the bagging film did not dissolve. Next, the vacuum bag was immersed in 80°C water, and the bagging film dissolved. The meltblown nonwoven fabric A used as the breather melted and was incorporated into the reinforced fiber composite molded body, and no breather remained as waste. The appearance of the obtained reinforced fiber composite molded body was evaluated as "A".

[0157] [Comparative Example 1] A vacuum bag molding system and a carbon fiber composite molded body (an example of a reinforced fiber composite molded body) of Comparative Example 1 were obtained in the same manner as in Example 1, except that meltblown nonwoven fabric B obtained in Production Example 2 was used as the breather instead of meltblown nonwoven fabric A obtained in Production Example 1. The meltblown nonwoven fabric B used as the breather was incorporated into the reinforced fiber composite molded body without melting, and no breather waste remained. However, the surface of the obtained reinforced fiber composite molded body was cloudy, and the appearance evaluation was "D".

[0158] [Comparative Example 2] An uncured carbon fiber composite material (W-3101-A / Q-1120E (manufactured by Teijin Limited), consisting of three layers) in which carbon fibers are impregnated with epoxy resin was placed on a flat mold as a reinforcing fiber composite material. Before placing the uncured carbon fiber composite material, a release agent (ChemLease 2166, manufactured by ChemTrend Japan Co., Ltd.) was applied to the surface of the mold where the uncured carbon fiber composite material would be placed. A fluororesin film (currently manufactured by AEROVAC, A5000), which is a release film, was placed on top of the uncured carbon fiber composite material, and then the meltblown nonwoven fabric B obtained in Manufacturing Example 2 was placed as a breather. Next, these were covered with a nylon film (Airtech, WL7400) as a bagging film to form a vacuum bag. After that, a vacuum valve was installed in the same procedure as in Example 1 to obtain the vacuum bag molding system of Comparative Example 2.

[0159] Using the obtained vacuum bag molding system, autoclave molding was performed in the same procedure as in Example 1 to obtain a carbon fiber composite molded body (an example of a reinforced fiber composite molded body). The meltblown nonwoven fabric B used as a breather did not melt and remained as waste. Furthermore, the surface of the obtained reinforced fiber composite molded body had many trapped air bubbles, and the appearance evaluation was "D".

[0160] The vacuum bag molding system of the present invention can be suitably used for autoclave molding of reinforced fiber composite materials and the like.

[0161] 10. Mold 11. Release agent 12. Reinforced fiber composite material 13. Breather 14. Release film 15. Bagging film 16. Vacuum valve 17. Laminate 18. Sealing tape (sealing material) 19. Vacuum bag

Claims

1. A vacuum bag molding system comprising a vacuum bag and a vacuum valve for exhausting air from the vacuum bag, wherein the vacuum bag contains a laminate having an uncured reinforced fiber composite material placed directly on a mold or via other components, and a breather placed in direct contact with the uncured reinforced fiber composite material, the breather being a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less.

2. The vacuum bag molding system according to claim 1, wherein the vacuum bag has a polyvinyl alcohol film.

3. The vacuum bag molding system according to claim 2, wherein the polyvinyl alcohol film is in direct contact with the uncured reinforced fiber composite material.

4. The vacuum bag molding system according to claim 1, wherein a release film is disposed between the vacuum bag and the laminate.

5. The vacuum bag molding system according to any one of claims 1 to 4, wherein the nonwoven fabric is a continuous long-fiber nonwoven fabric formed from fibers mainly composed of amorphous thermoplastic phenoxy resin as the thermoplastic resin.

6. The vacuum bag molding system according to claim 5, wherein the uncured reinforced fiber composite material contains an epoxy resin.

7. A method for manufacturing a reinforced fiber composite molded article using a vacuum bag molding system according to any one of claims 1 to 4, comprising the steps of: discharging air from inside the vacuum bag through a vacuum valve; and heat-curing the uncured reinforced fiber composite material contained in the vacuum bag.

8. A breather for autoclave molding, which is a nonwoven fabric formed from fibers mainly composed of a thermoplastic resin having a glass transition temperature of 100°C or less.

9. The breather according to claim 8, wherein the thermoplastic resin is an amorphous resin or a crystalline resin having a melting point of 150°C or lower.

Images