JP2023127055A - laminate - Google Patents

Abstract

To provide a lightweight laminate that can maintain mechanical properties while exhibiting excellent flame retardancy.SOLUTION: A laminate containing fibers, a matrix resin and a flame retardant filler is provided. The flame retardant filler is at least partially zinc borate. When an area occupied by the flame retardant filler in an entirety of a 45° cross section in the cross section 45° with respect to a direction of the fibers is 100%, an area ratio R occupied by the flame retardant filler in a range S of 400 μm from one outermost surface of the laminate is 70% or more. When an area occupied by the flame retardant filler is A and an area occupied by the matrix resin is B in the range S, the laminate satisfies a relation (I): 0.01<A/B<0.2 (I)SELECTED DRAWING: None

Description

The present invention relates to a laminate suitable for aircraft use.

Reinforcing fibers, especially carbon fiber composite materials made of carbon fibers and matrix resin, have excellent mechanical properties and are used in sports equipment such as golf clubs, tennis rackets, and fishing rods, structural materials for aircraft and vehicles, and concrete. It is used in a wide range of fields such as reinforcing structures. In recent years, carbon fiber has not only excellent mechanical properties but also conductivity, so it has been used for the housing of electronic and electrical equipment such as notebook computers and video cameras, making the housing thinner and reducing the weight of the equipment. It is useful for things such as Such carbon fiber reinforced composite materials are often obtained by laminating prepregs obtained by impregnating reinforcing fibers with a thermosetting resin.

Among the various uses of carbon fiber reinforced composite materials, there is a strong demand for materials to have flame retardant properties, especially in structural and interior materials for aircraft and vehicles, to prevent them from igniting and burning in the event of a fire. There is. Furthermore, in electronic and electrical equipment applications, there is a need for materials to be flame retardant in order to prevent accidents such as cases and parts igniting and burning due to heat generation from inside the equipment or exposure to high temperatures outside.

As a method of improving flame retardancy, a method of blending a flame retardant into a thermosetting resin is widely used (for example, Patent Document 1). However, the amount of filler mixed must be reduced because the filler becomes a fracture starting point and deteriorates mechanical properties.

Therefore, a technique of a laminate in which prepreg mixed with a flame retardant filler is laminated on both surfaces of the surface layer has been disclosed (for example, Patent Document 2).

International Publication No. 2005/082982 Japanese Patent Application Publication No. 2007-231073

However, the technique disclosed in Patent Document 2, which is a laminate in which flame retardant filler is laminated on both surfaces, has low flame retardancy and is insufficient to suppress the deterioration of physical properties that progresses from the vicinity of both surfaces. I have issues.

The present invention solves the problems in the prior art described above, and provides a laminate for obtaining a lightweight fiber-reinforced composite material that can maintain mechanical properties while exhibiting excellent flame retardancy.

In order to solve this problem, the present invention has the following configuration. That is, it is a laminate including fibers, a matrix resin, and a flame retardant filler, the flame retardant filler being at least partially zinc borate, and having a cross section of 45 degrees with respect to the fiber direction. When the area occupied by the flame retardant filler in the whole is taken as 100%, the area ratio R occupied by the flame retardant filler in a range S of 400 μm from the outermost surface of one of the laminates is 70% or more, and in this range S, the flame retardant filler A laminate is provided that satisfies the following relational expression (I), where A is the area occupied by the filler and B is the area occupied by the matrix resin.
0.01<A/B<0.2 (I)

According to the present invention, it is possible to achieve the effect of achieving both flame retardancy and mechanical properties of a fiber-reinforced composite material obtained by molding a laminate.

In the laminate of the present invention, in a cross section at 45° with respect to the fiber direction, assuming that the area occupied by the flame retardant filler in the entire 45° cross section is 100%, the flame retardant filler is present in a range of 400 μm from the outermost surface of one of the laminates. The area ratio R occupied by the filler is 70% or more, preferably 80% or more, and more preferably 90% or more. By cutting at 45° with respect to the fiber direction, the fibers in the 0° and 90° directions have the same cross-sectional shape, and the abundance ratio of fibers, resin, and flame retardant filler can be predicted without large errors. When the area occupied by the flame retardant filler is 70% or more, the flame retardancy of the laminate can be efficiently exhibited. The proportion of such flame retardant filler is evaluated according to the area measurement method described in the Examples.

The laminate of the present invention has formula (I) of 0.01<A/B<0.2, preferably 0.015<A/B<0.18, more preferably 0.02<A/ B<0.16. If the value of A/B exceeds 0.01, sufficient flame retardancy can be exhibited. Although it is better to have a large A/B value, it is controlled so that the upper limit is less than 0.2. The flame retardant filler area and matrix resin area are evaluated according to the area measurement method described in the Examples.

The flame retardant filler according to the present invention is at least partially composed of zinc borate, and preferably contains 60% by mass or more of zinc borate, so that the concentration per unit area of the filler is increased and a higher flame retardant effect is exhibited. be able to.

The flame retardant filler according to the present invention preferably has an average particle diameter larger than the fiber diameter and 60 μm or less. By being larger than the fiber diameter, when the fiber layer is impregnated with resin, the flame retardant filler is difficult to impregnate into the fiber layer and remains on the surface layer, thereby exhibiting high flame retardancy. Moreover, if it is 60 micrometers or less, the total surface area of a flame retardant filler will be large enough, and a high flame retardant effect can be expressed. The fiber diameter and the average particle diameter of the flame retardant filler are evaluated according to the calculation method described in the Examples.

In the laminate of the present invention, it is preferable that some or all of the fibers constitute a woven fabric. Since it is a woven fabric, even if a flame retardant filler is added, the mechanical properties are hardly affected, and flame retardancy can be improved.

In the laminate of the present invention, it is preferable that the fibers included in the outermost layer in which the flame retardant filler occupies 70% or more of the area within 400 μm from the outermost surface are woven fabrics. Here, the outermost layer is a layer disposed on the outermost side of the laminate. Since the fibers included in the outermost layer are woven fabrics, even when a flame retardant filler is added, the mechanical properties are hardly affected, and flame retardancy can be improved.

The thickness of the laminate of the present invention is preferably 4 mm or more. When the thickness is 4 mm or more, the influence of the flame retardant filler in the surface layer on the mechanical properties is reduced, and the mechanical properties can be maintained while exhibiting excellent flame retardancy.

Next, the matrix resin in the present invention will be described.

The matrix resin in the present invention includes an epoxy resin and a curing agent.

The epoxy resin in the present invention includes liquid bisphenol A epoxy resin, liquid bisphenol F epoxy resin, solid bisphenol A epoxy resin, solid bisphenol S epoxy resin, glycidyl ether epoxy resin such as aliphatic epoxy resin, and glycidyl amine. Type epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, rubber-modified epoxy resins, and the like can be preferably used. In the present invention, "liquid" refers to something that exhibits fluidity at 25°C.

The curing agent in the present invention is an amine curing agent. The amine curing agent refers to a compound having a nitrogen atom in the curing agent molecule.

Such curing agents are not particularly specified as long as they contain a nitrogen atom in the molecule, but examples include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, Aromatic polyamine compounds with active hydrogen such as m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, bis(aminomethyl)norbornane, bis(4-aminocyclohexyl)methane , aliphatic amines with active hydrogen such as dimer acid ester of polyethyleneimine, modified amines obtained by reacting these amines with active hydrogen with compounds such as epoxy compounds, acrylonitrile, phenol and formaldehyde, thiourea, N , N-dimethylaniline, N,N-dimethylbenzylamine, tertiary amines without active hydrogen such as 2,4,6-tris(dimethylaminomethyl)phenol and monosubstituted imidazole, dicyandiamide, tetramethylguanidine, adipine Examples include acid hydrazide, polycarboxylic acid hydrazide such as naphthalenecarboxylic acid hydrazide, and Lewis acid complex such as boron trifluoride ethylamine complex.

The amine curing agent in the present invention has stability during the resin preparation process, storage stability at room temperature, or stability against thermal history during the process of impregnating carbon fibers with the epoxy resin composition for carbon fiber reinforced composite materials. Therefore, it is preferable to have heat-activated latent properties. Here, the term "thermally activated latent" refers to the property that, although it is in a state of low activity as it is, it undergoes a phase change or chemical change when subjected to a certain thermal history, changing to a state of high activity. .

The matrix resin in the present invention may further contain a thermoplastic resin in order to control viscoelasticity and impart toughness.

Examples of such thermoplastic resins include polymethyl methacrylate, polyvinyl acetals such as polyvinyl formal and polyvinyl butyral, polyvinylpyrrolidone, aromatic vinyl monomers, vinyl cyanide monomers, and rubbery polymers. Examples include polymers containing at least two types of polyamides, polyamides, polyesters, polycarbonates, polyarylene oxides, polysulfones, polyethersulfones, polyimides, phenoxy resins, and the like. Among these, polyvinyl formal and polyether sulfone are preferably used because they have good compatibility with many types of epoxy resins and are highly effective in controlling the fluidity of epoxy resin compositions for carbon fiber reinforced composite materials. It will be done.

In the matrix resin of the present invention, the thermoplastic resin component is preferably contained in an amount of 5 to 20 parts by mass based on 100 parts by mass of the epoxy resin. Within this range, both the drapability of the prepreg and the flame retardancy of the carbon fiber reinforced composite material can be achieved.

Next, the flame retardant filler in the present invention will be described.

At least a portion of the flame retardant filler in the present invention is zinc borate, but preferably contains ZnO and _B2O3 , particularly from the viewpoint of dispersibility and stability in the composition _. Also, the combination of zinc borate and other flame retardants, such as zinc borate and metal hydroxides, zinc borate and red phosphorus, zinc borate and phosphorus compounds, zinc borate and nitrogen-containing compounds, etc. It is also possible to use other flame retardants.

In the laminate of the present invention, it is preferable to use carbon fibers as the fibers. In addition, below, a fiber may be described as a reinforcing fiber. By using carbon fibers as reinforcing fibers, fiber-reinforced composite materials can exhibit excellent flame retardancy, strength, and impact resistance.

As the carbon fiber, any known carbon fiber can be used, but those having a strand elastic modulus of 200 GPa or more and 450 GPa or less in a strand tensile test are preferably used. Note that the strand tensile test is a test conducted based on JIS R7601 (1986).

The number of carbon fiber filaments is preferably 2,000 to 50,000, more preferably 2,500 to 40,000 from the viewpoint that the fiber arrangement does not meander and resin impregnation is easy during prepreg production or molding.

The carbon fibers used in the present invention are classified into polyacrylonitrile-based, rayon-based, pitch-based carbon fibers, and the like. Among these, polyacrylonitrile carbon fibers having high tensile strength are preferably used. Polyacrylonitrile carbon fibers can be produced, for example, through the steps described below. A spinning dope containing polyacrylonitrile obtained from a monomer containing acrylonitrile as a main component is spun by a wet spinning method, a dry-wet spinning method, a dry spinning method, or a melt spinning method. The coagulated yarn after spinning is subjected to a spinning process to become a precursor, and then subjected to processes such as flame resistance and carbonization to obtain carbon fibers.

Commercially available carbon fibers include "Torayca (registered trademark)" T700G-24K, "Torayca (registered trademark)" T300-3K, and "Torayca (registered trademark)" T700S-12K with a tensile modulus of 230 GPa and 294 GPa. Examples include "Torayca (registered trademark)" T800G-24K, "Torayca (registered trademark)" T800S-24K, and 324 GPa "Torayca (registered trademark)" T1100G-24K (all manufactured by Toray Industries, Inc.).

The form and arrangement of carbon fibers can be appropriately selected from long fibers aligned in one direction, woven fabrics, etc., but in order to obtain a carbon fiber reinforced composite material that is lightweight and has a higher level of durability, it is necessary to It is preferable that the fibers are in the form of continuous fibers such as long fibers (fiber bundles) drawn in one direction or woven fabrics. The long fibers herein refer to fiber strands with an average length of 10 mm or more.

The carbon fiber bundle used in the present invention has a single fiber fineness from the viewpoint of not causing damage to the carbon fiber bundle during twisting or the resin composition impregnation process, and from the viewpoint of sufficiently impregnating the carbon fiber bundle with the resin composition. It is preferably 0.2 to 2.0 dtex, more preferably 0.4 to 1.8 dtex.

The laminate of the present invention is obtained by laminating prepregs made by impregnating long fibers, textiles, etc. of carbon fibers aligned in one direction with a mixture of a matrix resin and a flame retardant filler, and then curing the prepregs.

Such prepregs can be manufactured by various known methods. For example, a wet method in which the matrix resin comprising the epoxy resin composition of the present invention is dissolved in an organic solvent selected from acetone, methyl ethyl ketone, methanol, etc. to lower the viscosity and impregnated into reinforcing fibers, or a method without using an organic solvent. A prepreg can be produced by a method such as a hot melt method in which the viscosity of a matrix resin is reduced by heating and impregnated into reinforcing fibers.

In the wet method, reinforcing fibers are immersed in a liquid containing a matrix resin and then pulled up, and the organic solvent is evaporated using an oven or the like to obtain a prepreg. In addition, in the hot melt method, matrix resin whose viscosity has been lowered by heating is directly impregnated into reinforcing fibers, or a release paper sheet with a resin film on which matrix resin is coated on release paper (hereinafter referred to as "resin It is possible to use a method such as first producing a resin film (sometimes referred to as "film"), then layering a resin film on the reinforcing fiber side from both sides or one side of the reinforcing fiber, and impregnating the reinforcing fiber with the matrix resin by applying heat and pressure. .

As the method for producing the prepreg in the present invention, a hot melt method is preferably used in which reinforcing fibers are impregnated with a matrix resin without using an organic solvent, since there is substantially no organic solvent remaining in the prepreg.

The prepreg in the present invention preferably has a reinforcing fiber amount of 70 to 2000 g/m ² per unit area. When the amount of reinforcing fibers is within the range of 70 to 2000 g/ ^m2 , the drape properties of the prepreg are excellent, and the number of layers of prepreg to obtain a predetermined thickness is appropriate when forming a fiber reinforced composite material. It has excellent workability.

The mass content of reinforcing fibers in the prepreg in the present invention is preferably 30 to 90% by mass, more preferably 35 to 85% by mass, and even more preferably 40 to 80% by mass. When the mass content of reinforcing fibers in the prepreg is 30% by mass or more, it is possible to obtain a fiber-reinforced composite material with excellent specific strength and specific modulus, and the curing calorific value when molding the fiber-reinforced composite material is reduced. can be suppressed. Further, when the mass content of reinforcing fibers in the prepreg is 90% by mass or less, the reinforcing fibers are sufficiently impregnated with the matrix resin, and a void-free laminate can be obtained.

The laminate of the present invention can be manufactured by, for example, the method of laminating the prepregs of the present invention described above in a predetermined form and curing the matrix resin by heating and pressing. Examples of methods for applying heat and pressure include press molding, autoclave molding, bagging molding, internal pressure molding, and the like.

Furthermore, methods of directly impregnating reinforcing fibers with the matrix resin composition of the present invention without using prepreg, and then heating and curing the composition, such as hand lay-up method, filament winding method, resin transfer molding method, etc. A laminate can also be produced by a molding method.

When laminating the prepregs, it is preferable to laminate them so that the prepreg mixed with the flame retardant filler is on the outermost layer of one side. The reason for this is that since combustion proceeds from the outermost surface of the laminate, it is most effective to increase the flame retardance of this outermost surface. Although there are no particular limitations on the structure of the laminate, if the thickness of the laminate is 4 mm or less, the fibers and matrix resin should be It is desirable that it be symmetrical.

The laminate of the present invention has high flame retardancy with a maximum heat generation rate of 100 kW m ^-2 or less in a heat release test (OSU method) in accordance with FAR25.853 (Appendix F, Part IV). .

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are shown below.

<Epoxy resin>
- ELM434 (tetraglycidylaminodiphenylmethane resin, manufactured by Sumitomo Chemical Co., Ltd.).
- GAN (N,N-diglycidylaniline resin, manufactured by Nippon Kayaku Co., Ltd.).
- "jER (registered trademark)" 825 (liquid bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation).

<Thermoplastic resin>
- 10 parts by mass of "Sumika Excel (registered trademark)" 5003P (polyether sulfone, manufactured by Sumitomo Chemical Co., Ltd.).

<Flame retardant filler>
- "Firebrake (registered trademark)" 500 (anhydrous zinc borate, manufactured by Borax).

<Carbon fiber>
- "Torayka (registered trademark)" T800SC-24K (tensile strength 5.9 GPa, tensile modulus 294 GPa, fiber specific gravity 1.80, manufactured by Toray Industries, Inc.).

<Reinforced fiber fabric>
Carbon fiber fabric (Toray “Trading Card” cloth CO6343B)
Carbon fiber: Trading card T300B (3K)
Weaving structure: Plain weave Warp density: 12.5 pieces/25mm Weft density: 12.5 pieces/25mm
Fabric weight: 198g/m ² Thickness: 0.23mm.

<Prepreg sheet>
Prepreg sheet: “Trading Card” (registered trademark) Prepreg sheet P2352W-19
Reinforced fiber: T800S
Matrix resin: 3900-2B
Volume content of reinforcing fiber: 56%.

(1) Method for preparing matrix resin After putting the epoxy resins and thermoplastic resins listed in Table 1 into a kneading device, they were heated and kneaded. Next, the temperature was lowered to 60° C. or lower, and an amine curing agent corresponding to Table 1 was added and stirred to uniformly disperse it to obtain a matrix resin.

(2) Method for preparing matrix resin mixed with flame retardant filler After putting the epoxy resin, thermoplastic resin, and flame retardant filler corresponding to Table 1 into a kneading device, heating and kneading were performed. Next, the temperature was lowered to 60° C. or lower, and an amine curing agent corresponding to Table 1 was added and stirred so as to be uniformly dispersed to obtain a flame retardant filler mixed matrix resin.

(3) Preparation of prepreg The matrix resins prepared in (1) and (2) above were coated on release paper to have a basis weight of 66 g/m ² to produce a resin film. This resin film is set in a prepreg making machine, and both sides become films of the matrix resin composition prepared in (1), and both sides become films of the flame retardant filler mixed matrix resin composition prepared in (2). A resin film was layered on the carbon fiber fabric from both sides of "Torayka" (registered trademark) cloth CO6343B, and heated and pressed to impregnate the resin composition to produce a prepreg with a matrix resin mass fraction of 40% by mass.

(3) Preparation of laminate of carbon fiber reinforced composite material "Torayka" (registered trademark) prepreg sheet P2352W-19 is laminated with 11 or 21 plies by cross-ply lamination, and one side is covered with the matrix resin prepared in (1). The prepreg prepared in step (3) using the above method is laminated on the other side, and the prepreg prepared in step (3) using the matrix resin prepared in step (2) is laminated on the other side, each having a total thickness of 2 mm or 5 mm. A board was made. A piece having a width of 150 mm and a length of 150 mm was cut out from this laminate.

(4) Method for evaluating the amount of flame retardant filler mixed in a laminate The laminate obtained in (3) was mixed with EpoKwick FC Resin (Buehler) as a main material and Epokwick FC Hardener (Buehler) as a hardening agent. After embedding in the prepared epoxy resin and curing at room temperature, the cross section in the 45° direction with respect to the fiber axis was wet-polished. A length of 2 mm of the exposed cross section of the laminate was observed at a total magnification of 500 times using a 50 times objective lens of an optical microscope.

Regarding the area ratio R occupied by the flame retardant filler in the range of 400 μm from the outermost surface of one of the laminates, assuming that the area occupied by the flame retardant filler is 100%, the area occupied by the flame retardant filler in the cross-sectional microscopic image of the polished surface is and the area A occupied by the flame retardant filler in a range of 400 μm from the outermost surface of one of the laminates. For the analysis, the Trainable WEKA Segmentation plug-in of the image analysis program FIJI was used. First, in a cross-sectional image, a separate classifier that identifies the region divisions of fibers, matrix resin, and flame retardant filler was determined and applied to the entire cross-sectional image to determine the area At occupied by the flame retardant filler. Next, a 400 μm portion from the outermost surface where the flame retardant filler was present was cut out from the entire cross-sectional image, and the area A occupied by the flame retardant filler was similarly determined to derive the area ratio.
A/B, which is the ratio of the total cross-sectional area A of the flame retardant filler to the cross-sectional area B of the matrix resin in the range of 400 μm from the outermost layer of the laminate, is the ratio of the total cross-sectional area A of the flame retardant filler to the cross-sectional area B of the matrix resin in the range of 400 μm from the outermost layer of the laminate. Similarly, the cross-sectional area B of the resin and the cross-sectional area A of the flame retardant filler were calculated within the range of 400 μm of the outermost surface using the Trainable WEKA Segmentation plug-in of the image analysis program FIJI.

Using the Trainable WEKA Segmentation plug-in of the above-mentioned image analysis program FIJI, the fiber diameter was derived by segmenting and identifying the cross-sectional image within a range of 400 μm from the outermost surface where the flame retardant filler is present. In detail, the area F _i (i=1 to n: number of fibers in the cross-sectional image) of each fiber was derived, and the fiber diameter f _i of each fiber was calculated from this value. Assuming that the fiber cross section in the plane perpendicular to the fiber axis is a circle, the fiber diameter f _i can be calculated as follows, taking into account that the cross-sectional area F _i is 45° with respect to the fiber direction.

f _i =(F _i /π×2√2) ^0.5

The average value of the fiber diameters f ₁ to f _n thus derived was defined as the fiber diameter.

The average particle size of the flame retardant filler was determined from the number average value A/N of the cross-sectional area A determined by the above method. Here, assuming that the flame retardant filler has a spherical shape, the cross-sectional area of the flame retardant filler obtained by the above method is an arbitrary circle that intersects perpendicularly to the axis passing through the center of the sphere. Therefore, when the radius of the flame retardant filler is assumed to be a sphere and the radius of the flame retardant filler is r, the expected value S of the cross-sectional area is calculated by dividing the volume of the sphere by the diameter length 2r of the central axis, and can be calculated using the following formula.

S=2/3× ^r2

Here, assuming S=A/N, the average particle size 2r of the flame retardant filler was determined by the following formula.

2r=(6×A/N) ^0.5 .

(6) Heat release test (OSU method)
The laminate produced in (5) above was subjected to a heat release test (OSU method) in accordance with FAR25.853 (Appendix F, Part IV) so that the burning surface was the prepreg produced in (2). The maximum heat generation rate and the average value of the total heat generation amount during the first 2 minutes were evaluated. Furthermore, as a criterion, when the maximum heat generation rate satisfies 100 kW·m ⁻² and the average value of the total calorific value for the first 2 minutes satisfies 100 kW·min·m ⁻² or less, the test was considered to be passed, and the other cases were considered to be failed.

(Examples 1 to 3)
"Firebrake (registered trademark)" 500 as a flame retardant filler was blended so as to have the A/B and area ratio R shown in Table 1 to prepare the matrix resin composition shown in (2) above, and "Trading Card" (Trademark registered) Cloth CO6343B was used to produce a prepreg. Further, this prepreg was used together with "Torayka" (registered trademark) prepreg sheet P2352W-19 to produce a laminate having a thickness of 2 mm. From the cross-sectional observation of this laminate, the ratio A/B of the flame retardant filler area to the resin area was calculated. A heat release test (OSU method) was also conducted, and the flame retardance was found to be good.

(Example 4)
A laminate was produced in the same manner as in Example 2, except that the components listed in Table 1 were blended as the matrix resin. A heat release test (OSU method) was also conducted, and the flame retardance was found to be good.

(Example 5)
A laminate was produced in the same manner as in Example 2 except that the laminate thickness was 5 mm. A heat release test (OSU method) was also conducted, and the flame retardance was found to be good.

(Comparative example 1)
A laminate was produced in the same manner as in Examples 1 to 3 except that the flame retardant filler was not included. When a heat release test (OSU method) was also conducted, flame retardancy was found to be insufficient.

(Comparative example 2)
A laminate was produced in the same manner as Comparative Example 1 except that the laminate thickness was 5 mm. When a heat release test (OSU method) was also conducted, flame retardancy was found to be insufficient.

(Comparative example 3)
A prepreg was prepared in the same manner as in Examples 1 to 3, except that "Firebrake (registered trademark)" 500 was blended as a flame retardant filler so that the A/B and area ratio R shown in Table 1 was obtained. When prepared, the flame retardant effect was low and the flame retardancy was insufficient.

The contents in the table represent parts by mass. In addition, in the judgment, a case of passing is expressed as A, and a case of failure is expressed as B.

Claims (6)

A laminate comprising fibers, a matrix resin and a flame retardant filler,
The flame retardant filler is at least partially zinc borate,
In a cross section at 45° with respect to the fiber direction, when the area occupied by the flame retardant filler in the entire 45° cross section is taken as 100%, the flame retardant filler occupies a range S of 400 μm from the outermost surface of one laminate. The area ratio R is 70% or more,
And in the range S, a laminate in which the following relational expression (I) holds true, where A is the area occupied by the flame retardant filler and B is the area of the matrix resin.
0.01<A/B<0.2 (I) The laminate according to claim 1, wherein the flame retardant filler contains 60% by mass or more of zinc borate. The laminate according to claim 1 or 2, wherein the average particle diameter of the flame retardant filler is larger than the fiber diameter of the fibers and is 60 μm or less. The laminate according to any one of claims 1 to 3, wherein some or all of the fibers constitute a woven fabric. The laminate according to any one of claims 1 to 4, wherein the fibers included in the outermost layer on the side where the area ratio R is 70% or more constitute a woven fabric. The laminate according to any one of claims 1 to 5, having a thickness of 4 mm or more.