JP2019206153A - Resin-containing multilayer structure - Google Patents

Abstract

To provide a multilayer structure in which, while being composed of a reinforcing material-containing resin-based member, at least the surface has a metal-like physical property (particularly, a high elastic modulus, a low linear thermal expansion coefficient, and a good surface smoothness).SOLUTION: Provided is a multilayer structure including (A) a base material containing a reinforcing material and a first polymer, and (B) a surface modification layer containing a fine fiber structure and a second polymer impregnated in the fine fiber structure. In a preferred embodiment, the fine fiber structure is composed of cellulose fine fibers having an average fiber diameter of 0.005 μm or more and 2 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multilayer structure including a resin that enables weight reduction by replacing a metal-based material with a resin-based material.

  In recent years, due to increasing interest in environmental issues, conventional metal (for example, light metal) materials have a lower density (ie, lighter weight) in a wide range of small and large product members such as electronic products, home appliances, automobiles, and heavy machinery. Substitution with a resin-based material is being studied. Ensuring the same physical properties as metal materials is also an important theme for development. However, when changing materials from metal-based materials to resin-based materials, the inherent characteristics of metals (for example, high strength, high modulus, dimensional stability against heat, and the surface required for component products) In order to maintain the design properties of the resin, various technical difficulties are involved.To ensure high strength and high elastic modulus in resin materials and to ensure dimensional stability against heat, resin composites containing inorganic fillers, Fiber reinforced resins including glass fibers, carbon fibers or fine cellulose fibers have been proposed.

  Patent Document 1 describes a technique related to glass cloth fiber-reinforced plastic, and it is said that the suitable fiber diameter of the glass fiber forming the glass cloth is 10 to 26 μm. The desirable fiber diameter of the carbon fiber in the long fiber reinforced thermoplastic with the carbon fiber described in Patent Document 2 is 3 to 15 μm. According to Patent Document 1 and Patent Document 2, it is possible to provide a composite material having high strength and high elastic modulus. However, since the fiber diameters of the high-strength fibers constituting these composite materials are usually on the order of microns, when the resin is impregnated and solidified or cured, surface irregularities called sinks occur due to shrinkage of the resin layer between the fibers. A problem that occurs and significantly impairs the design is pointed out in Patent Document 3. Since this problem depends on the size of the reinforcing fiber, there is a possibility that it can be solved by using a fiber having a fiber diameter significantly smaller than the conventional fiber diameter.

  On the other hand, Patent Document 4 describes a nanocomposite using an inorganic filler, and Patent Document 5 describes a composite technology using a fine cellulose fiber. However, improvement of mechanical properties such as elastic modulus by a composite in which a filler is dispersed. There is a limit, and in all cases, the physical properties are improved by about several tens of percent with respect to the resin alone.

JP2015-157740A JP 2011-178914 A JP 2007-113142 A JP 2014-265887 A JP 2017-25338 A

  In the resin-based member according to the prior art, there has been a problem of deterioration in designability (for example, surface smoothness) due to the use of a reinforcing material (inorganic filler, reinforcing fiber, etc.) including surface irregularities due to sinks as described above. However, the problem could not be solved while maintaining the mechanical properties of the resin-based member. In particular, there is no technology that achieves both good mechanical properties and design properties (for example, surface smoothness) required for automotive parts and electronic product weight reduction materials using highly versatile resins. It was the current situation.

  In the replacement from the metal-based member to the resin-based member, it is important that the surface of the member has physical properties close to those of the metal. Therefore, it is desired to provide a resin-based member that is lightweight but has at least a surface having metal-like physical properties (particularly high elastic modulus, low linear thermal expansion coefficient, and good surface smoothness).

  The present invention solves the above-described problems and is composed of a resin-based member containing a reinforcing material, but at least the surface has metal-like physical properties (particularly high elastic modulus, low linear thermal expansion coefficient, and good surface smoothness). It is an object of the present invention to provide a multilayer structure having

As a result of intensive studies to solve the above problems, the present inventors have arranged the above-mentioned problems by arranging a fine fiber reinforced resin layer having a specific configuration on a base material composed of a resin-based material including a reinforcing material. It was found that can be solved.
That is, the present invention includes the following aspects.

[1] Surface modification containing (A) a reinforcing material and a base material containing a first polymer, and (B) a fine fiber structure and a second polymer impregnated in the fine fiber structure. layer,
A multilayer structure comprising
[2] The multilayer structure according to Aspect 1, wherein the fine fiber structure is composed of cellulose fine fibers having an average fiber diameter of 0.005 μm to 2 μm.
[3] The multilayer structure according to the aspect 1 or 2, wherein the fine fiber structure is a sheet-like structure composed of regenerated cellulose fibers and / or natural cellulose fibers.
[4] (C) It further includes a metal layer having a thickness of 0.01 mm or more and 3 mm or less disposed on the surface modification layer, and a ratio of the thickness of the metal layer to the total thickness of the multilayer structure is 30% or less. The multilayer structure according to any one of the above aspects 1 to 3.
[5] The multilayer structure according to any one of the above aspects 1 to 4, wherein the first polymer and the second polymer are the same.
[6] The multilayer structure according to any one of the above aspects 1 to 5, wherein the reinforcing material is inorganic particles having an average primary particle size of 3 μm to 100 μm.
[7] The multilayer structure according to any one of the above aspects 1 to 6, wherein the reinforcing material is an organic fiber and / or an inorganic fiber having an average fiber diameter of 3 μm to 50 μm.
[8] The multilayer structure according to aspect 7, wherein the reinforcing material is a woven fabric.
[9] The above (D), further comprising an underlayer disposed between the base material and the surface modified layer and including a fiber structure and a third polymer impregnated in the fiber structure. The multilayer structure in any one of aspects 1-8.
[10] The multilayer structure according to Aspect 9, wherein the first polymer and the third polymer are the same.
[11] A method for producing a multilayer structure according to the above aspect 9 or 10,
The reinforcing material is a woven fabric;
The first polymer, the second polymer and the third polymer are the same polymer;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated; and a woven fabric and the laminated structure in a state where the fine fiber structure is superposed on the outermost layer in a first state. Integrating the polymer by impregnating it.
[12] A method for producing a multilayer structure according to the above aspect 9 or 10,
The reinforcing material is a woven fabric;
The second polymer and the third polymer are the same thermosetting resin;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only the fine fiber structure or both the fiber structure and the fine fiber structure is impregnated with a thermosetting resin and semi-cured, and the woven fabric and the prepreg are Integrating by impregnating the first polymer in an overlaid state to be the outermost layer.
[13] A method for producing a multilayer structure according to the above aspect 9 or 10,
The multilayer structure includes a metal layer disposed on the surface modification layer;
The reinforcing material is a woven fabric;
The second polymer and the third polymer are the same thermosetting resin;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only a fine fiber structure or both a fiber structure and a fine fiber structure are impregnated with a thermosetting resin and semi-cured in advance, and a woven fabric, the prepreg and a metal layer are made of fibers Integrating by impregnating the first polymer with the structure side in contact with the woven fabric and the fine fiber structure side in contact with the metal layer.
[14] The method according to any one of Embodiments 11 to 13, wherein in the laminated structure, the fiber structure and the fine fiber structure are bonded by chemical bonding.
[15] A casing for an electronic product including the multilayer structure according to any one of the above aspects 1 to 10.
[16] An automotive member comprising the multilayer structure according to any one of the above aspects 1 to 10.

  According to the present invention, a multilayer structure having at least a metal-like physical property (particularly a high elastic modulus, a low linear thermal expansion coefficient, and a good surface smoothness) is formed of a resin-based member containing a reinforcing material. The body is provided.

FIG. 1 illustrates an example of a multilayer structure according to one embodiment of the present invention. FIG. 2 illustrates an example of a multilayer structure according to one embodiment of the present invention.

  Hereinafter, exemplary embodiments of the present invention (hereinafter, also referred to as “this embodiment”) will be described in detail, but the present invention is not limited to these embodiments. In the drawings, elements denoted by the same reference numerals are intended to be elements having the same configuration or function.

<Multilayer structure>
Referring to FIG. 1, a multilayer structure 10 according to this embodiment includes (A) a base material 1 including a reinforcing material and a first polymer, and (B) a fine fiber structure, and the fine fiber structure. The surface modification layer 2 containing the 2nd polymer impregnated in is included. In the multilayer laminate of the present embodiment, the base material and the surface modification layer are both made of a resin-based material, and thus can be lighter than, for example, a metal-based member. The surface modification layer may have good physical properties close to metal (particularly high elastic modulus, low linear thermal expansion coefficient, and good surface smoothness) by including a fine fiber structure.

  Referring to FIG. 1, in a preferred embodiment, a multilayer structure is disposed between a substrate 1 and a surface modification layer 2, and includes a fiber structure, and a third polymer impregnated in the fiber structure. The base layer 3 further includes By interposing the base layer between the base material and the surface modified layer, the base layer can buffer the physical property difference even when the physical property difference between the base material and the surface modified layer is large. Such a buffer function that the underlayer may have contributes to prevention of defects such as peeling at the interlayer interface of the multilayer laminate and warpage of the laminate. Therefore, the multilayer structure further including the underlayer can further have excellent characteristics such as being lightweight and having a metal-like surface having good physical properties and few defects such as peeling and warping.

[polymer]
First, each of the first polymer contained in the substrate, the second polymer contained in the surface modified layer, and the third polymer contained in the underlayer (if present) will be described. Each of the first polymer, the second polymer, and the third polymer may be thermoplastic, thermosetting, or photocurable, may be a homopolymer or a copolymer, and may be a single polymer. Or it may be a mixture of two or more polymers. In one aspect, the substrate includes a reinforcement and a first polymer, and optionally further includes additional components. In one embodiment, the surface modified layer includes a fine fiber structure and a second polymer, and optionally further includes additional components. In one embodiment, the underlayer includes a fibrous structure and a third polymer, and optionally further includes additional components. Each of the surface modification layer and the underlayer may further contain a reinforcing material component such as an inorganic or organic filler, glass fiber, or carbon fiber as an additional component, but in a preferred embodiment, these are not included. One or more of the base material, the surface modification layer, and the underlayer are various additives (colorants, conductive agents, antistatic agents, oxidation stabilizers, ultraviolet stabilizers, thermal stabilizers, plasticizers, flame retardants). , Flow regulators, leveling agents, etc.). In addition, the first polymer, the second polymer, and the third polymer may be different from each other, and the polymers are common to each other in two or more of the first polymer, the second polymer, and the third polymer ( That is, the same). In one aspect, at least the first polymer and the second polymer are the same. In one embodiment, at least the first polymer and the third polymer are the same. Here, that the polymers are different from each other means that the compositions and / or molecular weights are different from each other, and that the polymers are the same as each other means that the compositions and the molecular weights are the same. In the present disclosure, the various characteristic values referred to for the polymer are the values for the entire mixture when the polymer is a mixture (specifically, for example, the characteristic values of each of the plurality of components of the polymer include the mole fraction of each component). Value calculated from the value multiplied by the rate).

  In certain exemplary embodiments, a thermosetting resin may be selected as one or more of the first polymer, the second polymer, and the third polymer. Examples of thermosetting resins include epoxy resins, oxetane resins, polyester resins (especially unsaturated polyester resins), polyurethane resins, polyimide resins, phenol resins, and the like. It is also possible to use two or more kinds in combination. For example, a combination in which the first polymer and the third polymer are the same epoxy resin, and the second polymer is an epoxy resin having a different polymer structure and / or molecular weight.

  The thermosetting resin can be obtained by thermosetting a material composition containing a monomer, a curing agent and / or a curing accelerator. Examples of the monomer include an epoxy monomer containing an aromatic group having thermal stability at a high temperature. Examples of the epoxy monomer include a monofunctional epoxy monomer and a bi- or higher functional glycidyl ether type epoxy monomer, such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetrabromobisphenol A, phenol novolac, Cresol novolak, hydroquinone, resorcinol, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl, 1,6-dihydroxynaphthalene, 9,9-bis (4-hydroxyphenyl) fluorene, tris ( Examples thereof include glycidyl ether type epoxy monomers obtained by the reaction of p-hydroxyphenyl) methane, tetrakis (p-hydroxyphenyl) ethane and epichlorohydrin. In addition, an epoxy compound having a dicyclopentadiene skeleton, an epoxy compound having a biphenylaralkyl skeleton, and triglycidyl isocyanurate are also included. Aliphatic epoxy compounds and alicyclic epoxy compounds can also be used as long as they do not cause a significant decrease in Tg.

  Although various forms can be used as the curing agent, a liquid aromatic diamine curing agent may be added. Here, the liquid state means a liquid at 25 ° C. and 0.1 MPa. The aromatic diamine curing agent means a compound having two amine nitrogen atoms directly bonded to an aromatic ring in the molecule and having a plurality of active hydrogens. Here, “active hydrogen” refers to a hydrogen atom bonded to an aminic nitrogen atom. Since the liquid aromatic diamine is liquid, the impregnation property to the reinforcing fiber can be secured, and since it is an aromatic diamine, a cured product having a high Tg can be obtained. Examples of the liquid aromatic diamine curing agent include 4,4′-methylenebis (2-ethylaniline), 4,4′-methylenebis (2-isopropylaniline), 4,4′-methylenebis (N-methylaniline), 4,4′-methylenebis (N-ethylaniline), 4,4′-methylenebis (N-sec-butylaniline), N, N′-dimethyl-p-phenylenediamine, N, N′-diethyl-p-phenylene Diamine, N, N'-di-sec-butyl-p-phenylenediamine, 2,4-diethyl-1,3-phenylenediamine, 4,6-diethyl-1,3-phenylenediamine, 2,4-diethyl- Examples include 6-methyl-1,3-phenylenediamine and 4,6-diethyl-2-methyl-1,3-phenylenediamine. These liquid aromatic diamine curing agents may be used alone or in combination.

  Moreover, you may add a latent hardening | curing agent as another form. A latent curing agent is a compound that is insoluble in an epoxy resin at room temperature, solubilized by heating, and functions as a curing accelerator. It is an imidazole compound that is solid at room temperature, and a solid-dispersed amine adduct system latency. Examples of the curing accelerator include a reaction product of an amine compound and an epoxy compound (amine-epoxy adduct system), a reaction product of an amine compound and an isocyanate compound or a urea compound (urea type adduct system), and the like.

  Examples of imidazole compounds that are solid at room temperature include 2-heptadecylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-undecylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2 -Phenyl-4-benzyl-5-hydroxymethylimidazole, 2,4-diamino-6- (2-methylimidazolyl- (1))-ethyl-S-triazine, 2,4-diamino-6- (2'- Methylimidazolyl- (1) ′)-ethyl-S-triazine isocyanuric acid adduct, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1 -Cyanoethyl-2-methylimidazole-trimellitate, 1 Examples include cyanoethyl-2-phenylimidazole-trimellitate, N- (2-methylimidazolyl-1-ethyl) -urea, N, N ′-(2-methylimidazolyl- (1) -ethyl) -aziboyldiamide, and the like. However, it is not limited to these.

  Examples of the epoxy compound used as one of the raw materials for producing the solid dispersion type amine adduct type latent curing accelerator (amine-epoxy adduct type) include polyhydric phenols such as bisphenol A, bisphenol F, catechol, and resorcinol, glycerin, Polyglycidyl ether obtained by reacting a polyhydric alcohol such as polyethylene glycol with epichlorohydrin; reacting a hydroxycarboxylic acid such as p-hydroxybenzoic acid or β-hydroxynaphthoic acid with epichlorohydrin Glycidyl ether ester obtained by reaction of polycarboxylic acid such as phthalic acid and terephthalic acid with epichlorohydrin; epichlorohydric acid such as 4,4'-diaminodiphenylmethane and m-aminophenol Glycidylamine compounds obtained by reacting with hydrin; furthermore, polyfunctional epoxy compounds such as epoxidized phenol novolak resin, epoxidized cresol novolak resin, epoxidized polyolefin, and the like such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl methacrylate. Functional epoxy compounds; and the like, but are not limited thereto.

  The amine compound used as another raw material for producing the solid dispersion-type amine adduct-based latent curing accelerator has at least one active hydrogen capable of undergoing addition reaction with an epoxy group in the molecule, and a primary amino group, What is necessary is just to have at least one functional group selected from the secondary amino group and the tertiary amino group in the molecule. Examples of such amine compounds are shown below, but are not limited thereto. That is, for example, aliphatic amines such as diethylenetriamine, triethylenetetramine, n-propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, 4,4'-diamino-dicyclohexylmethane; 4,4'-diaminodiphenylmethane , Aromatic amine compounds such as 2-methylaniline; heterocycles containing nitrogen atoms such as 2-ethyl-4-methylimidazole, 2-ethyl-4-methylimidazoline, 2,4-dimethylimidazoline, piperidine, piperazine Compound; and the like.

  Furthermore, you may add a photo-acid generator as a hardening | curing agent. As the photoacid generator, one that generates an acid that can be cationically polymerized by ultraviolet irradiation is used, and the reaction further proceeds by applying heat. Examples of such a photoacid generator include an onium salt comprising an anion component such as SbF6-, PF6-, BF4-, AsF6-, (C6F5) 4-, PF4 (CF2CF3) 2-, and a cation component ( And diazonium salts, sulfonium salts, iodonium salts, selenium salts, pyridinium salts, ferrocenium salts, phosphonium salts, and the like. These may be used alone or in combination of two or more. Specifically, aromatic sulfonium salts, aromatic iodonium salts, aromatic phosphonium salts, aromatic sulfoxonium salts, and the like can be used.

  Regarding the curing start temperature of the material composition, as long as the reaction proceeds sufficiently, there is no particular provision regarding the temperature. On the other hand, when a latent curing agent is used, it is preferable that the reaction does not easily proceed at room temperature. For example, when a latent thermosetting agent is used, it is 40 ° C to 300 ° C, more preferably 60 ° C to 250 ° C. When the reaction temperature of the latent curing agent is less than 40 ° C., it reacts even at room temperature, which makes it difficult to develop the latent and is not preferable. Moreover, if the reaction temperature of the latent curing agent is higher than 300 ° C., it may cause a thermal decomposition reaction as an epoxy resin, which is not preferable.

  Furthermore, in addition to the above components, other additives can be appropriately blended as necessary. For example, for the purpose of enhancing curability, a photosensitizer such as anthracene, an acid proliferating agent, or the like can be blended as necessary. Moreover, in the use which produces hardened | cured material on base materials, such as glass, in order to improve adhesiveness with a base material, you may add coupling agents, such as a silane type or a titanium type. Furthermore, an antioxidant, an antifoaming agent, etc. can be mix | blended suitably. These may be used alone or in combination of two or more. And it is preferable to use these other additives in the range of 5 mass% or less of the whole curable resin composition from a viewpoint which does not inhibit the effect of this invention.

  In another exemplary embodiment, the first polymer, the second polymer, and the third polymer are all thermoplastic resins. Examples of the thermoplastic resin include a chain or cyclic polyolefin resin, polyamide resin, styrene resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, acrylic resin, aliphatic or Aromatic polycarbonate resins, aliphatic or aromatic polyester resins, polyphenylene ether resins, thermoplastic polyimide resins, polyacetal resins, polylactic acid resins, polysulfone resins, fluorine resins and the like can be mentioned. Among these, linear polyolefin resin, polyamide resin, styrene resin, AS resin, ABS resin, polyester resin, polyphenylene ether resin, thermoplastic polyimide resin, and polyacetal resin are preferably used, and further, versatility and heat resistance, For reasons such as durability, polypropylene, polyamide-6, polyamide-6,6, polyphenylene ether resin, polyacetal resin, and ABS resin are particularly preferable.

  The melting point of the thermoplastic resin is preferably 100 to 320 ° C, more preferably 120 to 290 ° C. The melting point is a value measured according to a thermal analysis using a differential scanning calorimeter.

  When the thermoplastic resin has a glass transition point, the glass transition point is preferably 60 to 200 ° C, more preferably 70 to 180 ° C. The glass transition point is a value measured according to dynamic viscoelasticity measurement.

  The number average molecular weight of the thermoplastic resin is, for example, 10,000 to 1,000,000 for the first polymer, 30,000 to 600,000 for the second polymer, and 10,000 to 1 for the third polymer. , 000,000, and so on.

  From the viewpoint of good adhesion of the substrate, the underlayer and the surface modified layer, the SP values of the first polymer, the second polymer and the third polymer are preferably close to each other.

From the viewpoint of good adhesion between the substrate and the underlayer, the difference between the SP value of the first polymer and the SP value of the third polymer is preferably 10 (MPa) ^1/2 or less, more preferably 8 (MPa) ^1/2 or less, more preferably 6 (MPa) ^1/2 or less. As a matter of course, the first polymer and the third polymer may be the same type (that is, the SP value difference is zero).

From the viewpoint of good adhesion between the underlayer and the surface modified layer, the difference between the SP value of the second polymer and the SP value of the third polymer is preferably 15 (MPa) ^1/2 or less, more preferably Is 10 (MPa) ^1/2 or less, more preferably 8 (MPa) ^1/2 or less. As a matter of course, the second polymer and the third polymer may be the same type (that is, the SP value difference is zero).

  Note that the SP value of the present disclosure is a value calculated according to the Fedors method. In the actual calculation, Synthia, which is a module packaged in the software manufactured by BIOVIA, Materials Studio 2017R2, is used.

  Next, each component of the multilayer structure will be described.

[Base material]
The substrate includes a first polymer and a reinforcing material. The reinforcing material may be a fiber, a granular material, a plate-like material, or the like. Examples of the fibers are glass fibers, carbon fibers, and various organic fibers (aramid, polyamide, cellulose, etc.). The fibers may be chopped fibers, sheet-like structures (nonwoven fabrics, woven fabrics, knitted fabrics) or the like, and carbon nanotubes can also be used. In a preferred embodiment, the reinforcing material is a long fiber structure (eg, glass cloth, carbon fiber cloth, etc.). Examples of the granular material include inorganic particles such as calcium carbonate, talc, silica, alumina, titanium oxide, magnesium oxide, and magnesium hydroxide. Examples of the plate-like material include layered silicates. In one aspect, the reinforcement is a woven fabric. Preferred examples of the woven fabric are glass cloth and carbon fiber cloth.

  In one embodiment, the reinforcing material is inorganic particles having a primary particle size of 3 μm to 100 μm. The primary particle size is a volume particle size distribution measured by a laser-type static light scattering method for a sample obtained by subjecting an aqueous dispersion of dilute (0.2% by mass or less) inorganic particles to ultrasonic treatment. The median diameter value. Moreover, in one aspect | mode, a reinforcing material is an organic fiber and / or an inorganic fiber with an average fiber diameter of 3 micrometers-50 micrometers. The average primary particle diameter and the average fiber diameter in the above range are preferable in terms of giving good mechanical strength to the substrate, respectively, but the deterioration of the surface smoothness (increased surface irregularities or roughness) due to sink marks etc. during molding It can be a factor. Therefore, when the reinforcing material has an average primary particle diameter or an average fiber diameter in the above range, the effect of improving the surface smoothness by combining the surface modified layer with the base material is particularly prominent.

  In a preferred embodiment, the content of the first polymer in the substrate is in the range of 30 to 95% by mass, or 40 to 92% by mass. In a preferred embodiment, the content of the reinforcing material in the substrate is 5 to 70% by mass, or 8 to 60% by mass.

  The base material may have various forms such as a sheet shape, a plate shape, and a bulk shape. In the illustrated embodiment, the base material has a plate-like or bulk-like form in which the dimension in the thickness direction (that is, the direction parallel to the thickness direction of the surface modification layer) is 0.2 mm or more.

  The linear thermal expansion coefficient of the substrate is preferably 80 ppm / ° C. or less, more preferably 60 ppm / ° C. or less, and further preferably 50 ppm / ° C. or less, from the viewpoint of physical property stability as a molded body. The linear thermal expansion coefficient is preferably small from the viewpoint of the physical properties of the multilayer structure. In the evaluation of the coefficient of linear thermal expansion (CTE), the multilayer structure of the present invention is cut into 3 mm width × 25 mm length, used as a measurement sample, and using a thermomechanical analyzer (TMA) (for example, TMA6100 type manufactured by SII), In pull mode, 10 mm between chucks, 5 g load, 1 ° C./min. From room temperature to 50 ° C. under nitrogen atmosphere. After raising the temperature at 50 ° C. to 25 ° C., 1 ° C./min. The temperature was lowered at 1 ° C./min. Raise the temperature. Under the present circumstances, the linear thermal expansion coefficient (linear thermal expansion coefficient) in 50 degreeC at the time of the 2nd temperature rise is measured.

  From the viewpoint of obtaining good mechanical strength, the storage elastic modulus of the substrate is preferably 1 GPa or more, more preferably 1.5 GPa or more, and further preferably 2 GPa or more. The storage elastic modulus is preferably large from the viewpoint of the physical properties of the multilayer structure, but may be, for example, 20 GPa or less, 16 GPa or less, or 12 GPa or less from the viewpoint of ease of production. The storage elastic modulus is a value measured at 50 ° C. in the dynamic viscoelasticity measurement, and is measured as follows. The composite resin film is cut into 4 mm width × 30 mm length to obtain a measurement sample. This was measured using a viscoelasticity measuring apparatus (for example, EXSTAR TMA6100 (manufactured by SII Nano Technology Co., Ltd.)) in a tensile mode at 20 mm between chucks, frequency: 1 Hz, in a nitrogen atmosphere from room temperature to 50 ° C. at 1 ° C./min. At 50 ° C to 25 ° C, 1 ° C / min. At 25 ° C. to 1 ° C./min. Raise the temperature. The storage elastic modulus at 50 ° C. at the time of the second temperature increase is obtained.

[Surface modification layer]
The surface modified layer is a layer containing a fine fiber structure and a second polymer impregnated in the fine fiber structure. Various shapes of the fine fiber structure are possible, but a sheet is preferable from the viewpoint of easy control of mechanical properties and easy compounding (impregnation, etc.) with a resin. The sheet may be a single layer or multiple layers, but is preferably a single layer. Examples of the sheet include a fine fiber aggregate sheet, a sheet-like structure composed of fine fibers (knitted fabric, woven fabric, non-woven fabric, etc.), and the like, preferably a fine fiber non-woven fabric sheet. The fine fiber nonwoven fabric sheet can be manufactured, for example, by forming an aqueous dispersion of fine fibers into a sheet by a papermaking method, but it is integrated by fine paper laminated papermaking on the fiber structure used for the underlayer as described later Can be used to obtain a fiber assembly sheet that is more suitable for obtaining the multilayer structure of the present embodiment.

  Examples of fibers constituting the fine fiber structure include cellulosic fibers (for example, natural cellulosic fibers and regenerated cellulosic fibers), wholly aromatic polyamide fibers, aliphatic polyamide fibers, and acrylic fibers. Examples of the raw material for the natural cellulosic fiber and the raw material for the regenerated cellulosic fiber include the same raw materials as described above for the fiber structure. In a preferred embodiment, the fine fiber structure is preferably a cellulose fine fiber from the viewpoint of good impregnation of the second polymer and good mechanical properties (for example, mechanical strength, flexibility, dimensional stability, etc.). Particularly preferred is a sheet-like structure composed of regenerated cellulose fibers and / or natural cellulose fibers.

  The average fiber diameter of the fibers (preferably cellulose fine fibers) constituting the fine fiber structure is preferably 0.005 μm or more, more preferably 0.01 μm or more, further from the viewpoint of good impregnation of the second polymer. The thickness is preferably 0.02 μm or more, and preferably 2 μm or less, more preferably 1 from the viewpoint of giving the surface modified layer good mechanical properties (high elastic modulus), good surface smoothness, and good dimensional stability. 0.5 μm or less, more preferably 0.8 μm or less. In a preferred embodiment, the fine fiber structure is composed of cellulose fine fibers having a fiber diameter of less than 1 μm.

  In the present disclosure, the average fiber diameter is a value evaluated by the following method unless otherwise specified. Cut out the cross section of the corresponding layer (base material, surface modified layer or underlayer) in the multilayer structure, and short in the fiber cross section with minor axis diameter / major axis diameter ≦ 3 detected by viscoelastic mode in atomic force microscope It is a value obtained as a number average value of shaft diameters. Usually, the average fiber diameter substantially coincides with the number average fiber diameter obtained in surface observation by a scanning electron microscope (SEM) in a sheet-like structure composed of fine cellulose fibers used in the preferred case of the present invention.

Basis weight of the fine fiber structure, from the viewpoint of obtaining good mechanical strength, preferably 2 g / m ² or more, more preferably 3 g / m ² or more, still more preferably from 4g / m ² or more, the thinner multilayer structure From the viewpoint of producing a body well, it is preferably 30 g / m ² or less, more preferably 25 g / m ² or less, and still more preferably 20 g / m ² or less.

  From the viewpoint of obtaining good mechanical strength, the thickness of the fine fiber structure is preferably 20 μm or more, more preferably 25 μm or more, and further preferably 30 μm or more, from the viewpoint of producing a multilayer structure having a small thickness. The thickness is preferably 120 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less.

  The air resistance of the fine fiber structure is preferably 2000 s / 100 ml or less, more preferably 1200 s / 100 ml or less, still more preferably 600 s / 100 ml or less, from the viewpoint of good impregnation of the second polymer. From the viewpoint of obtaining excellent mechanical properties, it is preferably 0.2 s / 100 ml or more, more preferably 0.5 s / 100 ml or more, and further preferably 1 s / 100 ml or more. The air resistance is a numerical value measured based on the Gurley tester method described in JIS P 8117.

  The content of the fine fiber structure based on the total mass of the surface modified layer is preferably 5% by mass or more, more preferably 8% by mass or more, and further preferably 12% by mass or more, from the viewpoint of obtaining good mechanical strength. From the viewpoint of good adhesion between the surface modified layer and the substrate or the base layer, it is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 50% by mass or less.

  The content of the second polymer on the basis of the total mass of the surface modified layer is preferably 20% by mass or more, more preferably 30 from the viewpoint of good adhesion between the surface modified layer and the substrate or the base layer. From the viewpoint of obtaining good mechanical strength, it is preferably 95% by mass or less, more preferably 92% by mass or less, and still more preferably 88% by mass or less.

  The thickness of the surface modification layer may be, for example, 0.005 to 0.1 mm, or 0.01 to 0.08 mm, or 0.02 to 0.07 mm.

The surface modification layer can have an advantage that it is lighter than a layer made of, for example, a metal-based material. The density of the surface modified layer is preferably 0.95 to 1.52 g / cm ³ , more preferably 0.98 to 1.48 g / cm ³ , and still more preferably 1.02 to 1.45 g / cm ³ . .

  The linear thermal expansion coefficient of the surface modified layer is preferably 40 ppm / ° C. or less, more preferably 30 ppm / ° C. or less, and still more preferably 26 ppm / ° C. or less, from the viewpoint of physical property stability as a molded body. The linear thermal expansion coefficient is preferably small from the viewpoint of the physical properties of the multilayer structure. In a preferred embodiment, the reinforcing layer has a linear thermal expansion coefficient equal to or less than the linear thermal expansion coefficient of the underlayer. The linear thermal expansion coefficient (ppm / ° C) of the reinforcing layer is preferably 2 ppm / ° C or more and 30 ppm / ° C or less, more preferably 4 ppm / ° C or more and 20 ppm / ° C, than the linear thermal expansion coefficient (ppm / ° C) of the underlayer. Below, it can be small.

  The storage elastic modulus of the surface modified layer is preferably 1.5 GPa or more, more preferably 2 GPa or more, still more preferably 2.5 GPa or more, from the viewpoint of physical property stability as a molded body. The storage elastic modulus is preferably large from the viewpoint of the physical properties of the multilayer structure, but may be, for example, 20 GPa or less, 15 GPa or less, or 12 GPa or less from the viewpoint of manufacturability. In a preferred embodiment, the storage elastic modulus of the surface modified layer is not less than the storage elastic modulus of the underlayer. The storage elastic modulus (GPa) of the surface modified layer can be preferably 0.2 GPa or more and 12 GPa or less, more preferably 0.4 GPa or more and 10 GPa or less than the storage elastic modulus (GPa) of the underlayer.

  In one embodiment, the surface modified layer is exposed on the surface of the multilayer structure (ie, the surface modified layer is the outermost layer of the multilayer structure). In this case, the storage elastic modulus of the surface modified layer is preferably 2 to 15 GPa, more preferably 2.5 to 12 GPa. As a means for obtaining such a particularly high storage elastic modulus, for example, the second polymer has a hard resin (that is, a storage elastic modulus at 50 ° C. (as an index of hardness) defined in the present disclosure is 0.7 GPa or more). Resin) and the like. As the hard resin, as a thermosetting resin, a hard epoxy resin, a polyester resin (particularly unsaturated polyester resin), a polyimide resin, a phenol resin, etc., as a thermoplastic resin, a polyamide resin, a styrene resin, Examples include AS resin, ABS resin, polyester resin, polyphenylene ether resin, thermoplastic polyimide resin, polyacetal resin, polylactic acid resin, and the like.

  In one embodiment, an additional layer is disposed on the surface modified layer (that is, the surface modified layer is not the outermost layer of the multilayer structure). In this case, the storage elastic modulus of the surface modified layer is preferably 1 to 12 GPa, more preferably 1.5 to 10 GPa. In this embodiment, from the viewpoint of good adhesion between the surface-modified layer and the additional layer, the second polymer is a soft resin (that is, the storage elastic modulus at 50 ° C. (as an index of hardness) is 0.7 GPa. It is preferable to include a resin that is less than. In addition to epoxy resins, melamine resins, phenolic resins, urethane resins, which are thermosetting resins, urethane resins, silicone resins, which undergo a curing reaction by contact with hydroxyl groups, which are called one-component curing types, Examples thereof include a resin having a high adhesive ability to other materials such as a silicon-modified resin, a silylated urethane resin, or an ethylene vinyl acetate resin used as a hot melt adhesive.

[Underlayer]
The underlayer is a layer that is disposed on the substrate and includes a fiber structure and a third polymer impregnated in the fiber structure. The fiber structure can have various shapes, but a sheet structure is preferable from the viewpoint of easy control of mechanical properties and easy compounding (impregnation, etc.) with a resin. The sheet may be a single layer or multiple layers. Sheets include sheet-like structures (knitted fabrics, woven fabrics, nonwoven fabrics, etc.), papermaking sheets (so-called paper and functional paper) made of cellulose beating fibers, etc., layers of papermaking sheets and other layers (for example, woven fabrics, nonwoven fabrics, etc.) And the like. In a preferred embodiment, the fiber structure is a papermaking sheet (so-called paper or functional paper) made of cellulose beaten fibers or the like. The fiber structure can be produced by, for example, a papermaking method, a dry papermaking method, or the like.

  As fibers constituting the fiber structure, cellulosic fibers (for example, natural cellulosic fibers and regenerated cellulosic fibers), wholly aromatic or aliphatic polyamide fibers, acrylic fibers, polyester fibers, polyvinyl alcohol fibers, A polylactic acid fiber etc. can be illustrated. Examples of raw materials for natural cellulosic fibers include wood pulp obtained from wood species (broadwood or conifer), and non-wood pulp obtained from non-wood species (bamboo, hemp fiber, bagasse, kenaf, linter, etc.). These pulps are preferably refined pulps that have undergone a refining (such as delignification) step and a bleaching step. Moreover, as a raw material of natural cellulosic fiber, seaweed origin cellulose, squirt cellulose, etc. are mentioned. Examples of the raw material for the regenerated cellulose fiber include rayon, cupra, and tencel. Examples of the polyamide fibers include fully aromatic polyamide fibers (for example, Kevlar fibers) in addition to PA-6 fibers and PA-6,6 fibers.

  The fibers constituting the fiber structure are preferably continuous long fibers, but may be long fibers or short fibers when the main constituent fibers are cellulose fibers. In a particularly preferred embodiment, the fibers constituting the fiber structure are preferably from the viewpoint of good impregnation of the third polymer and good mechanical properties (for example, mechanical strength, flexibility, dimensional stability, etc.). Only cellulose-based fibers (particularly those composed of regenerated cellulose fibers and / or natural cellulose fibers), or a combination of cellulosic fibers and synthetic fibers (for example, polyester fibers, polyamide fibers, acrylic fibers, polyvinyl alcohol fibers, etc.) (Among them, the mass ratio of cellulosic fiber / synthetic fiber is preferably 50/50 to 90/10). The fibers used for the underlayer are preferably fibrillated by a beating process or the like. In addition, in order to laminate a layer made of fine fibers on top of the underlayer, it may be desirable that the underlayer itself has a fine network. For example, the underlayer is 20% by mass or less, preferably 15%. Fine fibers having an average fiber diameter of 0.1% by mass or more and 3 μm or less by mass% or less may be included.

  The average fiber diameter of the main fibers constituting the fiber structure (that is, occupying more than 50% by mass of the entire fibers) is a mechanical property that satisfactorily relaxes the physical property difference between the substrate and the surface modified layer (for example, From the viewpoint of moderate mechanical strength, flexibility and dimensional stability) and ease of forming the underlayer, it is preferably 3 μm or more, more preferably 5 μm or more, still more preferably 8 μm or more, and preferably 60 μm or less, more preferably. Is 40 μm or less, more preferably 30 μm or less.

The basis weight of the fiber structure is a mechanical property (for example, moderate mechanical strength, flexibility and dimensional stability) that satisfactorily eases the difference in physical properties between the substrate and the surface modified layer, and easy formation of the underlayer From the viewpoint of property, it is preferably 7 g / m ² or more, more preferably 10 g / m ² or more, and further preferably 12 g / m ² or more. From the viewpoint of stably producing the multilayer structure of the present invention, 150 g is preferable. / M ² or less, more preferably 100 g / m ² or less, and still more preferably 80 g / m ² or less.

  The thickness of the fiber structure is sufficient for mechanical properties (for example, moderate mechanical strength, flexibility and dimensional stability) to satisfactorily relieve the difference in physical properties between the base material and the surface modified layer, and easy formation of the underlying layer From the viewpoint of property, it is preferably 20 μm or more, more preferably 40 μm or more, further preferably 50 μm or more, and from the viewpoint of producing a multilayer structure having a small thickness, preferably 200 μm or less, more preferably 150 μm or less. is there.

  The content of the fiber structure based on the total mass of the underlayer is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more, from the viewpoint of obtaining good mechanical strength. From the viewpoint of good adhesion between the underlayer, the base material and the surface modified layer (formation of a continuous layer via a resin, etc.), preferably 90% by mass or less, more preferably 70% by mass or less, and still more preferably 60%. It is below mass%.

  The content of the third polymer based on the total mass of the underlayer is preferably 10% by mass or more, more preferably 30% by mass, from the viewpoint of good adhesion between the underlayer, the base material, and the surface modified layer. From the viewpoint of obtaining good mechanical strength, it is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass or less.

  The thickness of the underlayer may be, for example, 0.02 to 0.2 mm, or 0.04 to 0.15 mm, or 0.05 to 0.12 mm.

  The linear thermal expansion coefficient of the underlayer is preferably 50 ppm / ° C. or less, more preferably 40 ppm / ° C. or less, and still more preferably 35 ppm / ° C. or less, from the viewpoint of physical property stability as a molded body. It is preferable that the linear thermal expansion coefficient of the underlayer is not significantly different from the linear thermal expansion coefficient of the substrate. That is, the difference between the linear thermal expansion coefficient (ppm / ° C.) of the base layer and the linear thermal expansion coefficient (ppm / ° C.) of the substrate is preferably 40 ppm / ° C. or less, more preferably 30 ppm / ° C. or less.

  The storage elastic modulus of the underlayer is preferably 0.5 GPa or more, more preferably 1 GPa or more, and still more preferably 2 GPa or more from the viewpoint of obtaining good mechanical strength. The storage elastic modulus is preferably large from the viewpoint of the physical properties of the multilayer structure, but may be, for example, 10 GPa or less, 8 GPa or less, or 5 GPa or less from the viewpoint of manufacturability. In a preferred embodiment, the storage elastic modulus of the underlayer is not less than the storage elastic modulus of the substrate.

Air permeability of the fibrous structure from the point of view of good impregnation of the third polymer, preferably 10ml / cm ² / s or more, more preferably 20ml / cm ² / s or more, more preferably 30 ml / cm ² / From the viewpoint of obtaining good mechanical strength, it is preferably 300 ml / cm ² / s or less, more preferably 260 ml / cm ² / s or less, and still more preferably 240 ml / cm ² / s or less. The air permeability means the air permeability measured with a Frazier type air permeability meter.

[Metal layer]
In one embodiment, the multilayer structure further comprises a metal layer as the additional layer described above. By providing a metal layer originally having a high elastic modulus (usually 5 GPa or more in storage modulus) and a low coefficient of linear thermal expansion (usually 25 ppm / ° C. or less) on the outermost layer, the multilayer structure of the present invention as a whole Not only can it be designed to have a high elastic modulus and a low coefficient of thermal expansion, but it can also exhibit a design effect unique to metals.

  With reference to FIG. 2, in one embodiment, the multilayer structure 20 further includes a metal layer 4 disposed on the surface modification layer 3 in addition to the base material 1, the optional underlayer 3, and the surface modification layer 2. Including. As the material of the metal layer, aluminum, iron, steel, zinc, magnesium, copper, nickel, chromium, titanium and alloys thereof (for example, magnesium alloy containing 90% by mass or more of magnesium, aluminum, zinc, etc., 70 mass) % Of aluminum alloy containing aluminum and zinc or more).

  The thickness of the metal layer may be, for example, 0.01 mm to 3 mm, or 0.03 mm to 1 mm. The ratio of the thickness of the metal layer to the total thickness of the multilayer structure is preferably 30% or less, more preferably 20% or less. The said ratio may be 2% or more, or 4% or more from a viewpoint of obtaining the desired advantage by using a metal layer, for example.

<Manufacture of multilayer structure>
As a manufacturing method of the multilayer structure, molding which is a manufacturing method of fiber reinforced plastic (FRP) can be applied. More specifically, in addition to the hand lay-up method and spray-up method in which the fiber structure is laid on the mold and the resin mixed with the curing agent is degassed, the aggregate and the resin are mixed in advance. In addition to the SMC press method, which compresses the shape with a mold, the RTM method, in which a resin is injected into a mating die in which fibers are laid, such as injection molding, and the method of molding by curing a thermosetting resin in an autoclave. A de-autoclave molding method that does not use a widely used autoclave is also applicable. Hereinafter, as an exemplary embodiment, an example of a mold forming method using a mold corresponding to a desired shape of the multilayer structure will be described.

  Prior to molding, the first, second, and third polymers are composed of other components (specifically, additional components as described above and reinforcing material in the base material), for example, a single-screw kneader, biaxial It can be kneaded by means known to those skilled in the art such as a kneader. The first, second and third polymers are each in the state of a solution or dispersion containing a polymer or monomer and a solvent, in a molten state (in the case of a thermoplastic resin), and in an uncured state (thermosetting or photocuring). For example, solvent removal (in the case of a solution or dispersion), cooling (in the case of a thermoplastic resin), or curing (thermosetting or photocurable) In the case of resin). What is necessary is just to design the conditions of solidification suitably according to the kind etc. of polymer to be used.

Specific examples of the manufacturing method of the multilayer structure are listed below.
(1) A multilayer structure in which the multilayer structure has an underlayer, the reinforcing material is a woven fabric, and the first polymer, the second polymer, and the third polymer are the same polymer.
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated; and a first fabric in a state in which a woven fabric and the laminated structure are overlapped so that the fine fiber structure is an outermost layer. It can be produced by a process that involves integrating by impregnating the polymer.
In this method, a laminated structure is first manufactured by depositing a fine fiber structure on a fiber structure by a papermaking method, a coating method, and the like, and then drying. The manufacturing method of this laminated structure is as follows, for example. For fine fibers, water dispersions of fine fibers are produced by mechanically and / or chemically refining short-fiber aqueous dispersions such as natural cellulose and / or regenerated cellulose that are easily oriented and fibrillated. The laminated paper is made on the functional paper or fabric used as the underlying fiber structure of the present invention, integrated and dried. The method for producing an aqueous dispersion of fine fibers at this time is, for example, a method for producing fine fibers containing cellulose as described in JP-A-2015-14078 and International Publication No. 2016/047764, and a sheet. It may be in conformity with the conversion method. That is, the refinement treatment is performed by dispersing natural cellulose (pulp, etc.) and / or regenerated cellulose cut fibers in water, and then performing pretreatment for promoting fibrillation such as beating treatment, and then high pressure homogenizer, ultrahigh pressure homogenizer (opposing (Including a collision type), a grinder, an ultrasonic homogenizer, or the like, to obtain a fine fiber dispersion. In the sheet forming step, a single-layer sheet may be used, but a more preferable aspect is obtained by laminating and integrating on a functional paper or a non-woven sheet serving as a base layer. In the sheeting step, for example, the solid content concentration of the papermaking dispersion is preferably 0.005% by mass to 0.5% by mass, more preferably 0.01% by mass to 0.35% by mass. In a state of being uniformly dispersed, paper is made on the fiber structure constituting the base layer. Thereafter, a press treatment is appropriately performed and a drying treatment is performed to produce a two-layer laminate in which the integrated base fiber structure and fine fiber structure are laminated. In particular, in order to control a layer composed of fine fibers so as to be within the specific air resistance range of the present disclosure, for example, as disclosed in JP-A-2015-14078, fine cellulose fibers and different fine fibers (for example, wholly aromatic) A method of performing composite paper making such as polyamide fine fiber) or a paper making method using an organic solvent as described in JP 2010-053461 A is preferable. By using these methods, a predetermined porous structure is used. It can be preferably controlled. Alternatively, disperse fine fibers for papermaking with a surfactant (nonionic, anionic, cationic or amphoteric surfactant) that can act on the surface so that the air permeability resistance does not become too large due to shrinkage during drying. It may be effective to form a sheet by a papermaking method after adding it to the liquid. Further, in the production process of the two-layer laminate, it is particularly desirable that the fiber structure layer and the fine fiber structure layer are bonded by chemical bonding. For example, according to the method described in International Publication No. 2015/008868, a crosslinking agent such as blocked isocyanate is added at the time of papermaking, and after the papermaking, drying, and the crosslinking treatment by heating, This is preferable because the adhesive strength with the layer containing the structure becomes extremely large.

  Next, the woven fabric and the laminated structure are overlapped so that the fine fiber structure becomes the outermost layer, and the fine fiber structure side is arranged in the mold so as to follow the inner wall of the mold. Next, the first polymer is supplied to the mold from the fabric side, and the fabric and the laminated structure are impregnated with the polymer. Next, the polymer is solidified by a method (solvent removal, cooling, thermosetting, etc.) according to the type and supply form of the polymer.

(2) The multilayer structure in which the multilayer structure has an underlayer, the reinforcing material is a woven fabric, and the second polymer and the third polymer are the same thermosetting resin, for example,
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only the fine fiber structure or both the fiber structure and the fine fiber structure is impregnated with a thermosetting resin and semi-cured in advance, and the woven fabric and the prepreg are It can manufacture by the method including integrating by impregnating a 1st polymer in the state piled up so that it might become the outermost layer.
In this method, first, a laminated structure is manufactured by the same procedure as described in the method (1) above. Next, only the fine fiber structure or both the fiber structure and the fine fiber structure are impregnated with a thermosetting resin and semi-cured to produce a prepreg. In the present disclosure, semi-cured means a state where the resin is cured to such an extent that fluidity is lost, but still maintains flexibility to follow the mold shape. Next, the woven fabric and the prepreg are overlapped so that the fine fiber structure becomes the outermost layer, and the fine fiber structure side is arranged in the mold so as to be along the inner wall of the mold. Next, the first polymer is supplied to the mold from the fabric side, and the fabric and the laminated structure are impregnated with the polymer. Next, the polymer is solidified by a method (solvent removal, cooling, thermosetting, etc.) according to the type and supply form of the polymer.

(3) The multilayer structure includes a base layer and a metal layer, the reinforcing material is a woven fabric, and the second polymer and the third polymer are the same thermosetting resin.
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only a fine fiber structure or a fiber structure and a fine fiber structure are impregnated with a thermosetting resin and semi-cured in advance,
A method comprising: integrating a woven fabric, the prepreg, and a metal layer by impregnating the first polymer in a state of being overlapped so that the fiber structure side is in contact with the fabric and the fine fiber structure side is in contact with the metal layer. Can be manufactured.
In this method, first, a laminated structure is manufactured in the same procedure as described in the method (2) above, and then only the fine fiber structure or both the fiber structure and the fine fiber structure are produced. A prepreg is produced by impregnating a thermosetting resin and semi-curing it. Next, the woven fabric, the prepreg, and the metal layer are overlapped so that the fiber structure side is in contact with the woven fabric and the fine fiber structure side is in contact with the metal layer, and the metal layer side is disposed in the mold so as to be along the inner wall of the mold. Next, the first polymer is supplied to the mold from the fabric side, and the fabric and the laminated structure are impregnated with the polymer. Next, the polymer is solidified by a method (solvent removal, cooling, thermosetting, etc.) according to the type and supply form of the polymer.

  In the laminated structure, as described above, the fiber structure and the fine fiber structure are preferably bonded in advance by chemical bonding. Examples of chemical bonds include urethane bonds, ester bonds, ether bonds, amide bonds, silyl bonds, and the like.

<Characteristics of multilayer structure>
The multilayer structure of the present embodiment can have an advantage that the surface modified layer is smooth while having excellent mechanical properties. In the illustrated embodiment, when the surface modification layer is exposed on the surface of the multilayer structure, the surface roughness of the exposed surface is determined by the presence or absence of a rough feeling visually confirmed.

The multilayer structure of this embodiment can have the advantage of being lighter than a structure made of, for example, a metal-based material. The density of the multilayer structure is preferably 1.0 to 2.1 g / cm ³ , more preferably 1.05 to 1.95 g / cm ³ , and still more preferably 1.1 to 1.85 g / cm ³ .

  The multilayer structure of the present embodiment is suitably used as a metal substitute member in various applications that require light weight and high strength, for example, housings for electronic products such as housings for display devices, and various automobile members. it can.

  Hereinafter, although an example is shown and an exemplary mode of the present invention is further explained, the present invention is not limited to these examples.

<< Example of production of fine fiber slurry >>
<Slurry production example 1>
Linter pulp, which is natural cellulose obtained from Nippon Paper Pulp Trading Co., Ltd., was used as a raw material, and it was immersed in water so that the linter pulp was 4% by mass. Thereafter, heat treatment was performed at 130 ° C. for 4 hours in an autoclave, and the obtained swollen pulp was washed with water many times to obtain swollen pulp in a state impregnated with water. Thereafter, the obtained refined linter pulp was dispersed in water so as to have a solid content of 1.5% by mass (400 L), and a SDR14 type laboratory refiner (pressure DISK type) manufactured by Aikawa Tekko Co., Ltd. as a disc refiner device. The clearance between the disks was 1 mm, and 400 L of the aqueous dispersion was beaten for 20 minutes. Subsequently, the beating process was continued under conditions where the clearance was reduced to a level almost close to zero. Sampling was carried out over time, and the CSF value of the Canadian standard freeness test method (hereinafter referred to as CSF method) of pulp defined by JIS P 8121 was evaluated for the sampling slurry. Then, it became close to zero once. As the beating process continued further, it was confirmed that the CSF value tends to increase. The beating treatment was continued under the above conditions for 10 minutes after setting the clearance to near zero, and a beating water dispersion having a CSF value of 100 ml or more was obtained. The obtained beating water dispersion was subjected to refinement treatment 5 times under an operating pressure of 100 MPa using a high-pressure homogenizer (NS015H manufactured by Niro Soabi (Italy)) as it was, and a slurry of cellulose fine fibers (solid content concentration) : 1.5% by mass).

<Slurry production example 2>
Tencel cut yarn (3 mm length) which is a regenerated cellulose fiber obtained from Sojitz Corporation was used as a raw material. The tencel cut yarn was put in a washing net in advance, a surfactant was added, and the oil agent on the fiber surface was removed by washing with a washing machine many times. Thereafter, a disc refiner and a high-pressure homogenizer treatment were performed in the same manner as in Production Example 1 to obtain a cellulose fine fiber slurry (solid content concentration: 1.5 mass%). The CSF value was 100 ml or more.

<Slurry production example 3>
A slurry of cellulose fine fibers (solid content concentration: 1.5% by mass) was obtained in the same manner as in Slurry Production Example 1 except that the raw material was changed to Abaca pulp. The CSF value was 630 ml or more.

<Example of sheet production>
<Sheet Production Example 1>
The slurry of the slurry production example 1 was diluted to a solid content concentration of 0.2% by mass and stirred with a home mixer for 3 minutes to prepare 312.5 g of a papermaking slurry. Then, 1.9 g of cationic block polyisocyanate (trade name “Meikanate WEB”, manufactured by Meisei Chemical Co., Ltd., diluted to a solid content concentration of 1.0% by mass) while stirring 312.5 g of papermaking slurry with a three-one motor. The mixture was added dropwise and stirred for 3 minutes to obtain a papermaking slurry (314.4 g in total). The added cationic block polyisocyanate mass ratio was 3% by mass based on the mass of cellulose fine fiber solids. Subsequently, while stirring the slurry with a three-one motor, 6.25 g of Emulgen 103 (polyoxyethylene lauryl ether, HLB 8.1, manufactured by Kao Corporation) diluted to 1% by mass was added dropwise as a porosifying agent. The final papermaking slurry (total 320.5 g) was obtained by stirring for a minute. Since the porosifying agent does not dissolve in water, it was collected after shaking vigorously by hand immediately before the addition.

A plain fabric made of PET / nylon blend (Shikishima Kanbus Co., Ltd., NT20: water permeation amount at 25 ° C. in the atmosphere: 0.03 ml / (cm ² · s), 99 by filtration of cellulose fine fibers at 25 ° C. under atmospheric pressure The above-mentioned final adjustment was performed on a batch type paper machine (made by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm × 25 cm, 80 mesh) with a basis weight of 10 g / m ² as a guide. Papermaking slurry was added, and then papermaking (dehydration) was performed at a reduced pressure with respect to atmospheric pressure of 4 KPa.

The wet paper made of the concentrated composition in a wet state on the obtained filter cloth is peeled off from the wire, pressed at a pressure of 1 kg / cm ² for 1 minute, and then the wet paper surface is brought into contact with the drum surface. In the two layers of wet paper / filter cloth, the wet paper was dried for about 120 seconds so that the wet paper was in contact with the drum surface in a drum dryer whose surface temperature was set to 130 ° C. The filter cloth was peeled off from the obtained dried two-layer sheet to obtain a white cellulose fine fiber sheet. Subsequently, the cellulose fine fiber sheet was sandwiched between two SUS metal frames (25 cm × 25 cm), fixed with clips, heat-treated at 160 ° C. for 3 minutes in an oven, and isocyanate-crosslinked, 20 cm × 20 cm square, A milky white cellulose fine fiber sheet S1 having a thickness of 30 μm and a cellulose fine fiber basis weight of 10 g / m ² was produced.

<Sheet Production Example 2>
The slurry of the slurry production example 2 was diluted to a solid content concentration of 0.2% by mass and stirred for 3 minutes with a home mixer to prepare 312.5 g of papermaking slurry. Then, 1.9 g of cationic block polyisocyanate (trade name “Meikanate WEB”, manufactured by Meisei Chemical Co., Ltd., diluted to a solid content concentration of 1.0% by mass) while stirring 312.5 g of papermaking slurry with a three-one motor. The mixture was added dropwise and stirred for 3 minutes to obtain a papermaking slurry (314.4 g in total). The added cationic block polyisocyanate mass ratio was 3% by mass with respect to the mass of cellulose fine fiber solids.

A plain fabric made of PET / nylon blend (Shikishima Kanbus Co., Ltd., NT20: water permeation amount at 25 ° C. in the atmosphere: 0.03 ml / (cm ² · s), 99 by filtration of cellulose fine fibers at 25 ° C. under atmospheric pressure A thin paper (as a base material) made of cellulose as a base material on a batch type paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm × 25 cm, 80 mesh) set with a mass% or more filter ability Tenma Special Paper Co., Ltd., with a basis weight of 20 g / m ² ) was spread, and the final paper-making slurry adjusted as described above was introduced from above with a basis weight of cellulose fine fiber per unit area of 10 g / m ² . Thereafter, paper making (dehydration) was carried out at a reduced pressure with respect to atmospheric pressure of 4 KPa.
The wet paper made of the concentrated composition in a wet state on the obtained filter cloth is peeled off from the wire, pressed at a pressure of 1 kg / cm ² for 1 minute, and then the wet paper surface is brought into contact with the drum surface. In a two-layer wet paper / filter cloth state, the wet paper was dried for about 120 seconds so that the wet paper was in contact with the drum surface in a drum dryer whose surface temperature was set to 130 ° C. The filter cloth was peeled off from the obtained dried two-layer sheet to obtain a white cellulose fine fiber laminated sheet. Subsequently, the cellulose fine fiber sheet was sandwiched between two SUS metal frames (25 cm × 25 cm), fixed with clips, heat-treated at 160 ° C. for 3 minutes in an oven, and isocyanate-crosslinked, 20 cm × 20 cm square, A milky white cellulose fine fiber laminate sheet S2 having a thickness of 90 μm and a basis weight of 30 g / m ^{2 as} a laminate sheet was produced.

<Sheet Production Example 3>
The slurry of the slurry production example 3 was diluted to a solid content concentration of 0.2% by mass and stirred with a home mixer for 3 minutes to prepare 312.5 g of papermaking slurry. Subsequently, 1-hexanol and hydroxypropylmethylcellulose (trade name “60SH-4000”, manufactured by Shin-Etsu Chemical Co., Ltd.) were added in an amount of 1.2% by mass (3.9 g) and 0.012% by mass (0) while stirring with a three-one motor. .039 g) and then emulsified and dispersed for 4 minutes with a home mixer. Further, 1.9 g of cationic block polyisocyanate (trade name “Meikanate WEB”, manufactured by Meisei Chemical Co., Ltd., diluted to a solid content concentration of 1.0% by mass) was dropped while stirring the papermaking slurry with a three-one motor. The mixture was stirred for 3 minutes to obtain a papermaking slurry (3318.4 g in total). The added cationic block polyisocyanate mass ratio was 3% by mass with respect to the mass of cellulose fine fiber solids.

A plain fabric made of PET / nylon blend (Shikishima Kanbus Co., Ltd., NT20: water permeation amount at 25 ° C. in the atmosphere: 0.03 ml / (cm ² · s), 99 by filtration of cellulose fine fibers at 25 ° C. under atmospheric pressure A thin paper (as a base material) made of cellulose as a base material on a batch type paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm × 25 cm, 80 mesh) set with a mass% or more filter ability) Tenma Special Paper Co., Ltd., with a basis weight of 15 g / m ² ) was laid, and from above, the final papermaking slurry adjusted as described above was introduced using a cellulose fine fiber basis weight of 5 g / m ² as a guide. Thereafter, paper making (dehydration) was carried out at a reduced pressure with respect to atmospheric pressure of 4 KPa.

The wet paper made of the concentrated composition in a wet state on the obtained filter cloth is peeled off from the wire, pressed at a pressure of 1 kg / cm ² for 1 minute, and then the wet paper surface is brought into contact with the drum surface. In a two-layer wet paper / filter cloth state, the wet paper was dried for about 120 seconds so that the wet paper was in contact with the drum surface in a drum dryer whose surface temperature was set to 130 ° C. The filter cloth was peeled off from the obtained dried two-layer sheet to obtain a white cellulose fine fiber laminated sheet. Subsequently, the cellulose fine fiber sheet was sandwiched between two SUS metal frames (25 cm × 25 cm), fixed with clips, heat-treated at 160 ° C. for 3 minutes in an oven, and isocyanate-crosslinked, 20 cm × 20 cm square, A milky white cellulose fine fiber laminate sheet S3 having a thickness of 60 μm and a basis weight of 20 g / m ^{2 as} a laminate sheet was produced.

<< Manufacturing example of multilayer structure >>
《Examples of varnish production》
<Varnish production example 1>
A varnish (V1) having a solid content of 70% by mass was prepared by using methyl ethyl ketone as a solvent and mixing the following compounds with a kneader.
・ 78.9 parts by mass of brominated bisphenol A type epoxy resin 1121N-80M (Dainippon Ink Chemical) ・ 14.0 parts by mass of phenol novolac type epoxy resin N680-75M (Dainippon Ink Chemical) ・ Dicyandiamide (Dainippon Ink Chemical) 2.0 parts by mass, 2-ethyl-4-methylimidazole (Shikoku Kasei) 0.1 part by mass, phenoxy resin YL7553BH30 (Mitsubishi Chemical) 5.0 parts by mass

<< Manufacturing example of multilayer structure >>
<Example 1>
A 30 cm square polyethylene terephthalate support film (thickness 16 μm) was prepared, and 0.3 g of varnish V1 was applied to the release surface with an applicator, and then cut to a 10 cm square, 150 μm thick glass cloth (manufactured by Nittobo) Placed on it. Subsequently, 0.3 g of varnish V1 was applied again with an applicator. The obtained product was heated at 100 ° C. for 4 minutes to remove the solvent, and a semi-cured prepreg sheet (PG1) having a thickness of 170 μm containing glass cloth was obtained.

  Subsequently, after applying 0.3 g of varnish V1 with a film applicator to the release surface of a 30 cm square polyethylene terephthalate support film (thickness 16 μm) in the same manner as described above, the cellulose fine fiber sheet produced in Sheet Production Example 1 was used. S1 was placed, and 0.3 g of varnish V1 was again applied thereon with an applicator. The obtained product was heated at 100 ° C. for 4 minutes to remove the solvent, and a 40 μm-thick semi-cured prepreg sheet (PS1) containing the cellulose fine fiber sheet S1 was obtained.

  With respect to the two prepreg sheets (PG1 and PS1) with a support film obtained above, PG1 was placed on the lower side, and PS1 was placed thereon so that the prepregs adhered to each other. This sheet was subjected to a curing reaction by a vacuum hot press using a 210 μm thick aluminum frame as a spacer in a vacuum hot press (heating temperature 220 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a laminated structure FGS1 having a thickness of 210 μm.

<Example 2>
A 30 cm square polyethylene terephthalate support film (thickness 16 μm) was prepared, and 0.3 g of varnish V1 was applied to the release surface with a film applicator, and then the cellulose fine fiber laminated sheet S2 produced in Sheet Production Example 2 was used. The cellulose fine fiber layer was placed so as to be on the support film side, and varnish V1 was applied thereon again by 0.3 g with an applicator. The obtained product was heated at 100 ° C. for 4 minutes to remove the solvent, and a semi-cured prepreg sheet (PS2) having a thickness of 45 μm including the cellulose fine fiber laminated sheet S2 was obtained.

  With respect to the prepreg sheet (PS2) and the prepreg sheet with support film (PG1) obtained in Example 1, PG1 was placed on the lower side, and PS2 was placed thereon so that the prepregs adhered to each other. Using a vacuum hot press machine, an aluminum frame with a thickness of 265 μm was set as a spacer for this sheet, and a curing reaction was performed by vacuum hot pressing (heating temperature 220 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a laminated structure FGS2 having a thickness of 265 μm.

<Example 3>
Low density polyethylene (made by Idemitsu Petrochemical Co., Ltd., trade name: 0234CL), 30% by mass of talc (average particle size 15 μm) is prepared, and extrusion molding is performed while heating and mixing at 230 ° C. with a sheet extruder. Thus, a talc-containing polypropylene sheet (FP1) having a thickness of 390 μm was produced.

  Subsequently, a 30 cm square polyethylene terephthalate support film (thickness: 16 μm) was prepared, and varnish V1 was applied to the release surface using a spacer, and the solvent was removed by heating at 100 ° C. for 4 minutes. A semi-cured prepreg sheet (PE1) made only of an epoxy resin having a thickness of 40 μm was produced.

  The cellulose fine fiber laminate sheet (S2) produced in Sheet Production Example 2 is placed on the prepreg sheet (PE1) so that the cellulose fine fiber layer is in contact with the prepreg surface of PE1, and further a talc-containing polypropylene sheet ( PE1) was stacked, and a 30 cm square polyethylene terephthalate support film (thickness: 16 μm) was placed thereon. An aluminum frame having a thickness of 500 μm was set as a spacer on this sheet using a vacuum hot press machine, and a curing reaction was performed by vacuum hot pressing (heating temperature 220 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a laminated structure FPS1 having a thickness of 500 m.

<Example 4>
Nylon 6 (manufactured by Ube Industries) was prepared and injection molded at 250 ° C. with an injection molding machine to prepare a nylon sheet (FA1) having a thickness of 320 μm.
Subsequently, an aluminum sheet having a surface roughness of about 1 μm and a thickness of 100 μm is prepared. Varnish V1 is applied to the roughened surface using a spacer, and the solvent is removed by heating at 100 ° C. for 4 minutes. Thus, a semi-cured prepreg sheet (PA1) made only of an epoxy resin having a thickness of 30 μm was produced.

  On the prepreg sheet (PA1), the cellulose fine fiber laminate sheet (S3) produced in Sheet Production Example 3 is placed so that the cellulose fine fiber layer is in contact with the prepreg surface of PA1, and further a nylon 6 sheet (FA1) ) And a support film (thickness 16 μm) of 30 cm square polyethylene terephthalate with a release agent was placed thereon. An aluminum frame having a thickness of 500 μm was set as a spacer on this sheet using a vacuum hot press, and a curing reaction was performed by vacuum hot pressing (heating temperature 250 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a laminated structure FNS1 having a thickness of 500 m.

<Comparative example 1>
A 30 cm square polyethylene terephthalate support film (thickness: 16 μm) was prepared, and 0.6 g of varnish V1 was applied to the release surface with an applicator. Thereafter, two glass cloths (manufactured by Nittobo Co., Ltd.) having a thickness of 150 μm cut into 10 cm squares were placed thereon. Subsequently, 0.6 g of varnish V1 was applied again with an applicator. The obtained product was heated at 100 ° C. for 4 minutes to remove the solvent, and a semi-cured prepreg sheet (PG2) having a thickness of 340 μm including two glass cloths was obtained.

  A 30 cm square polyethylene terephthalate support film (thickness 16 μm) was placed on this sheet, and a curing reaction was performed by vacuum hot press using a 340 μm thick aluminum frame as a spacer in a vacuum hot press (heating temperature). 220 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a single layer structure RG2 having a thickness of 340 μm.

<Comparative example 2>
A 30 cm square polyethylene terephthalate support film (thickness: 16 μm) was prepared, and 0.3 g of varnish V1 was applied to the release surface with an applicator. On top of that, a thin paper (manufactured by Tenma Special Paper Co., Ltd., with a basis weight of 20 g / m ² ) composed mainly of cellulose was placed. Subsequently, 0.3 g of varnish V1 was applied again with an applicator. The obtained product was heated at 100 ° C. for 4 minutes to remove the solvent, and a 50 μm-thick semi-cured prepreg sheet (PT1) containing thin paper was obtained.

  A semi-cured prepreg sheet (PG2) having a thickness of 340 μm including the two glass cloths produced in Comparative Example 1 was placed on the prepreg sheet (PT1) so that the prepreg surface was in contact therewith. An aluminum frame having a thickness of 390 μm was set as a spacer on this sheet using a vacuum hot press, and a curing reaction was performed by vacuum hot pressing (heating temperature 220 ° C., pressure 6.0 MPa, time 160 minutes). The support film attached to both sides was removed from the obtained cured sheet to obtain a laminated structure RTS1 having a thickness of 390 m.

<Comparative Example 3>
A treated 30 cm square polyethylene terephthalate support film (thickness 16 μm) treated with a release agent on both sides of the 390 μm thick 30% by mass talc-containing polypropylene sheet (FP1) produced in Example 3 was provided. An aluminum frame having a thickness of 350 μm was set as a spacer on the sheet using a vacuum hot press machine and subjected to vacuum hot press treatment (heating temperature 220 ° C., pressure 6.0 MPa, time 30 minutes). The support film attached to both sides was removed from the obtained sheet to obtain a single-layer structure RFP1 having a thickness of 350 m.

<Evaluation items>
<< Measurement of physical properties and evaluation method >>
<Number average fiber diameter of fine cellulose fibers>
In the laminated sheet, 10 observations at random from the surface of the cellulose fine fiber were performed at a magnification corresponding to 1,000 to 100,000 times according to the fiber diameter of the fine fiber. With respect to the obtained SEM image, a line was drawn in the horizontal direction and the vertical direction with respect to the screen, and the fiber diameter of the fiber intersecting the line was measured from the enlarged image, and the number of intersecting fibers and the fiber diameter of each fiber were counted. . In this way, the number average fiber diameter was calculated using two series of measurement results for one image. Further, the number average fiber diameter was calculated in the same manner for the other two extracted SEM images, and the results for a total of 10 images were averaged.

<Maximum fiber diameter of cellulose fine fiber>
From the surface of the structure consisting of cellulose fine fibers, observation was carried out at 10 points at random at a magnification of 500 times using a scanning electron microscope (SEM). The fiber diameter of the thickest fiber in the obtained 10 SEM images was defined as the maximum fiber diameter in the cellulose fine fiber sheet. About the laminated sheet laminated | stacked on the other nonwoven fabric etc., SEM observation was performed from the cellulose fine fiber sheet side.

<Sheet weight>
A sample conditioned in an atmosphere of room temperature 20 ° C. and humidity 50% RH was cut into a square piece of 10.0 cm × 10.0 cm and weighed, and calculated from the following formula.
Sheet weight (g / m ² ) = 10 cm square mass (g) /0.01 m ²

<Sheet thickness>
A sample conditioned in an atmosphere of room temperature 20 ° C. and humidity 50% RH was measured for 10-point thickness with a surface contact type (surface contact type film thickness meter (Code No. 547-401) manufactured by Mitutoyo Co., Ltd.). The average value was taken as the thickness of the sample.

<Porosity>
The density of the cellulose fine fiber was assumed to be 1.5 g / cm ³ and was calculated from the following formula.
Porosity (%) = 100 − ((weight per unit area (g / m ² ) /1.5) / sheet thickness (μm)) × 100)

<Air permeability resistance>
Using a Gurley-type densometer (Model G-B2C, manufactured by Toyo Seiki Co., Ltd.), a sample conditioned at room temperature of 23 ° C. and a humidity of 50% RH was used for the permeation time of 100 ml (unit: s / 100 ml). The air resistance measured at room temperature was measured at 10 points, and the average value was taken as the air resistance of the sample.

<Density measurement>
The density measurement of various resin composites was performed by A method (underwater substitution method) of JIS K7112.

<Linear thermal expansion coefficient (CTE)>
The obtained multilayer structure and single layer structure were cut into 3 mm width × 25 mm length to obtain measurement samples. Using a TMA6100 type apparatus manufactured by SII, 10 ° C. between chucks in a pull mode, a load of 5 g and a nitrogen atmosphere from room temperature to 50 ° C. at 1 ° C./min. At 50 ° C to 25 ° C, 1 ° C / min. At 25 ° C. to 1 ° C./min. The temperature was raised. At this time, the linear thermal expansion coefficient at 50 ° C. at the time of the second temperature increase was used as a value.

<Storage elastic modulus (E ')>
The obtained multilayer structure and single layer structure were cut into 4 mm width × 30 mm length to obtain measurement samples. Using a viscoelasticity measuring apparatus EXSTAR TMA6100 (SII Nano Technology Co., Ltd.), the temperature was increased from room temperature to 50 ° C. at 1 ° C./min. The temperature was lowered at 1 ° C./min from 25 ° C. to 25 ° C., and the temperature was raised again at 1 ° C./min from 25 ° C. to 50 ° C. The storage elastic modulus at 50 ° C. at the second temperature rise was did.

<Bending strength>
In accordance with JIS K7171, strip-like test pieces (80 mm in length, 10 mm in width, 3 mm in thickness are stacked and heat-pressed to produce the multilayer structure and single layer structure obtained) Was measured using Tensilon at room temperature under 50% RH, a test speed of 2 mm / min, a distance between fulcrums of 50 mm, and a three-point bending method.

<Surface unevenness evaluation>
By visual observation, whether or not the unevenness (due to sink marks, etc.) following the shape of the reinforcing material occurred on the sample surface after vacuum hot pressing of various samples for reasons such as resin curing shrinkage. Evaluation was performed as follows.
○: All five sheets have no irregularities due to sink marks or the like on the sample surface, and are extremely smooth.
Δ: Concavity and convexity due to sink marks or the like is generated on the sample surface with 2 or less sheets.
-X: Three or more uneven shapes due to sink marks or the like are generated on the sample surface.

<Surface gloss>
The sample surface after vacuum hot pressing of 5 types of samples does not cause fine or rough roughness due to the mixture of resin and filler or fiber, and has gloss specific to resin and metal. Whether or not was evaluated by visual observation as follows.
○: All five sheets have no rough surface on the sample surface and have a gloss unique to resins and metals.
Δ: There are two or less samples that have a rough surface on the surface of the sample or those that do not have a glossiness peculiar to resins and metals.
-X: There are three or more samples that have a rough surface on the sample surface, or those that do not have a glossiness peculiar to resins and metals.

<Metal adhesion evaluation>
For the laminated structure FNS1 having a thickness of 500 m produced in Example 4, using a thermal shock tester (manufactured by Espec Co., Ltd.), as a heating condition, after heating at 160 ° C. for 1.5 hours, as a cooling condition, Cooling at −40 ° C. × 1.5 hours was defined as one cycle, and this was performed for 100 cycles. After carrying out this test, a sample was taken out, and the presence or absence of peeling and cracks occurring between the resin layer and the metal layer was visually determined.
The characteristics of the obtained multilayer structure are as follows.

  The multilayer structure according to the present invention is suitably applied as a metal substitute member in applications where metal-based members have been conventionally used (for example, housings for electronic products such as housings for display devices, various automotive members). Can be done.

DESCRIPTION OF SYMBOLS 10,20 Multilayer structure 1 Base material 2 Surface modification layer 3 Underlayer 4 Metal layer

Claims (16)

(A) a base material containing a reinforcing material and a first polymer, and (B) a surface modified layer containing a fine fiber structure and a second polymer impregnated in the fine fiber structure,
A multilayer structure comprising   The multilayer structure according to claim 1, wherein the fine fiber structure is composed of cellulose fine fibers having an average fiber diameter of 0.005 μm or more and 2 μm or less.   The multilayer structure according to claim 1 or 2, wherein the fine fiber structure is a sheet-like structure composed of regenerated cellulose fibers and / or natural cellulose fibers.   (C) It further includes a metal layer having a thickness of 0.01 mm or more and 3 mm or less disposed on the surface modification layer, and the ratio of the thickness of the metal layer to the total thickness of the multilayer structure is 30% or less. The multilayer structure as described in any one of Claims 1-3.   The multilayer structure according to any one of claims 1 to 4, wherein the first polymer and the second polymer are the same.   The multilayer structure according to any one of claims 1 to 5, wherein the reinforcing material is inorganic particles having an average primary particle size of 3 µm to 100 µm.   The multilayer structure according to any one of claims 1 to 6, wherein the reinforcing material is an organic fiber and / or an inorganic fiber having an average fiber diameter of 3 µm to 50 µm.   The multilayer structure according to claim 7, wherein the reinforcing material is a woven fabric.   (D) It is arrange | positioned between the said base material and the said surface modification layer, and further contains the base layer containing the 3rd polymer impregnated in the fiber structure and the said fiber structure. The multilayer structure according to claim 8.   The multilayer structure according to claim 9, wherein the first polymer and the third polymer are the same. A method for producing a multilayer structure according to claim 9 or 10,
The reinforcing material is a woven fabric;
The first polymer, the second polymer and the third polymer are the same polymer;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated; and a woven fabric and the laminated structure in a state where the fine fiber structure is superposed on the outermost layer in a first state. Integrating the polymer by impregnating it. A method for producing a multilayer structure according to claim 9 or 10,
The reinforcing material is a woven fabric;
The second polymer and the third polymer are the same thermosetting resin;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only the fine fiber structure or both the fiber structure and the fine fiber structure is impregnated with a thermosetting resin and semi-cured, and the woven fabric and the prepreg are Integrating by impregnating the first polymer in an overlaid state to be the outermost layer. A method for producing a multilayer structure according to claim 9 or 10,
The multilayer structure includes a metal layer disposed on the surface modification layer;
The reinforcing material is a woven fabric;
The second polymer and the third polymer are the same thermosetting resin;
The method comprises
Producing a laminated structure in which a fiber structure and a fine fiber structure are integrated;
Producing a prepreg in which only a fine fiber structure or both a fiber structure and a fine fiber structure are impregnated with a thermosetting resin and semi-cured in advance, and a woven fabric, the prepreg and a metal layer are made of fibers Integrating by impregnating the first polymer with the structure side in contact with the woven fabric and the fine fiber structure side in contact with the metal layer.   The method according to any one of claims 11 to 13, wherein in the laminated structure, a fiber structure and a fine fiber structure are bonded by chemical bonding.   The housing | casing for electronic products containing the multilayered structure as described in any one of Claims 1-10.   The member for motor vehicles containing the multilayered structure as described in any one of Claims 1-10.

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