JP7069977B2 - Thermoplastic resin laminate - Google Patents

Description

The present invention relates to a laminate in which a thermoplastic resin and carbon fibers are composited.

In recent years, there has been an increasing need for molded products that are lightweight, have high strength, and have excellent impact resistance, such as housings for large electric appliances, interior materials for automobiles and railways, and exterior materials. In particular, such molded products are also required to emphasize productivity while maintaining performance such as mechanical strength. That is, there is a demand for a material having an excellent balance between mechanical strength and impact resistance. Based on such a background, a material in which a thermoplastic resin and an inorganic fiber are combined has been proposed.

For example, Patent Document 1 describes a core layer made of a synthetic resin foam, a front and back layer made of an aluminum sheet, and a reinforcing layer made of glass fiber between the core layer and the front and back layers via an adhesive layer. The aluminum laminated plate provided with the above is disclosed.

Further, Patent Document 2 discloses a polycarbonate resin laminate having a polycarbonate resin base material and a polycarbonate composite layer containing a filler laminated on the base material.

Japanese Unexamined Patent Publication No. 2001-301092 Japanese Unexamined Patent Publication No. 2009-96048

However, in the aluminum laminated plate disclosed in Patent Document 1, the core layer made of the synthetic resin foam has a foam structure, and the reinforcing fiber-containing resin layer is provided with pores to provide impact resistance and light weight. Although the properties are ensured, the mechanical strength, particularly the flexural modulus, is weakened by the pores existing in the reinforcing fiber-containing resin layer.

In the polycarbonate resin laminate disclosed in Patent Document 2, a laminate having a flexural modulus of around 5 GPa and having an excellent balance with impact resistance is disclosed, but when a flexural modulus larger than 5 GPa is exhibited. There is no mention of its relationship to impact resistance.

An object of the present invention is to provide a thermoplastic resin laminate having excellent mechanical strength and impact resistance.

As a result of diligent studies in view of the above circumstances, the present inventors have found that the following inventions can solve the above-mentioned problems, and have completed the present invention.

That is, the gist of the present invention is as follows.
[1] A core layer containing a thermoplastic resin, a front and back layer containing carbon fibers, and a metal sheet layer having an elongation of 10% or more during a tensile test between the core layer and the front and back layers. Thermoplastic resin laminate having.
[2] The thermoplastic resin laminate according to [1], wherein the thickness ratio of the metal sheet layer to the laminate is 2 to 30%.
[3] The thermoplastic resin laminate according to [1] or [2], wherein the carbon fiber is a polyacrylonitrile-based carbon fiber.
[4] The thermoplastic resin laminate according to any one of [1] to [3], wherein the metal sheet layer is made of aluminum having a purity of 99.99% or more.
[5] The thermoplastic resin laminate according to any one of [1] to [4], wherein the core layer further contains glass fibers.

According to the present invention, it is possible to provide a thermoplastic resin laminate having excellent mechanical strength and impact resistance.

Hereinafter, embodiments of the thermoplastic resin laminate of the present invention will be described in detail.

It should be noted that the upper limit value and the lower limit value of the numerical value range in the present invention are the same as those in the numerical value range of the present invention, even if they are slightly out of the numerical range characteristic of the present invention. It is included in the equal range. The main component in the present invention is a component contained in the largest amount, and is usually a component contained in an amount of 50% by weight or more, preferably 60% by weight or more, and more preferably 70% by weight or more. ..

<Thermoplastic resin laminate>
In the thermoplastic resin laminate of the present invention, the elongation at the time of the tensile test is 10% or more between the core layer containing the thermoplastic resin, the front and back layers containing carbon fibers, and the core layer and the front and back layers. It has a metal sheet layer which is.
Hereinafter, the "thermoplastic resin laminate of the present invention" may be referred to as "the present laminate".
Conventionally, as a laminate having resistance to an impact from the outside while maintaining light weight and high rigidity, a synthetic resin foam as disclosed in Patent Document 1 is used as a core layer, and a fiber reinforced plastic is used as the core layer. A laminated body in which aluminum sheets were laminated was used. However, as described above, in such a configuration, although impact resistance and light weight are ensured, the mechanical strength, particularly the flexural modulus, is weakened by the pores existing in the reinforcing fiber-containing resin layer.
In order to develop the flexural modulus, a means of laminating and arranging high-rigidity materials is taken, but from the viewpoint of impact resistance, the higher-rigidity material is more liable to crack and is damaged by cracks in the material. Cheap. That is, there is a trade-off phenomenon in high rigidity and impact resistance.

On the other hand, this laminated body is excellent in both mechanical strength and impact resistance. The reason for this is not clear, but by arranging a layer containing carbon fibers with high elastic modulus on the front and back layers of the laminate, and arranging a metal sheet layer having tensile elongation characteristics between the core layer and the front and back layers. It is considered that impact resistance is also exhibited without inhibiting the high rigidity developed by the layer containing carbon fibers. In addition, this laminated body is unlikely to be deformed when it receives an impact.
Hereinafter, the core layer, the front and back layers, and the metal sheet of this laminated body will be described.

[Core layer]
The core layer is a layer existing as an intermediate layer of the present laminate and contains a thermoplastic resin.
Since the core layer contains a thermoplastic resin, this laminated body having excellent moldability and heat resistance can be obtained.
The core layer may further contain glass fibers in order to further increase the rigidity of the laminate.

(Thermoplastic resin)
The thermoplastic resin is not particularly limited, and examples thereof include polyolefin-based resins, polycarbonate-based resins, polyamide-based resins, and polyester-based resins. One of these resins may be used alone, or two or more of these resins may be mixed and used.
Among these resins, by using a polyolefin-based resin, a present laminated body having excellent moldability and light weight can be obtained. As will be described later, among the polyolefin resins, polypropylene resin is particularly preferable.

Hereinafter, the polyolefin-based resin, the polycarbonate-based resin, the polyamide-based resin, and the polyester-based resin will be described.

(1) Polyolefin-based resin Examples of the polyolefin-based resin include homopolymers of α-olefins such as propylene and ethylene, random copolymers, block copolymers and the like, and specific examples thereof include polyethylene-based resins, polypropylene-based resins and polybutadienes. Examples include based resins. Polypropylene resin and polyethylene resin are preferable from the viewpoint of moldability and light weight of the thermoplastic resin laminate, and polypropylene resin is particularly preferable from the viewpoint of mechanical properties and heat resistance. Further, as the polyolefin-based resin, a plurality of polyolefin-based resins may be mixed and used.

The polypropylene-based resin may be a homopolymer of propylene, or a comonomer component such as ethylene or butene may be copolymerized with propylene. When the core layer contains glass fibers, a modified polymer can also be preferably used from the viewpoint of adhesion to reinforcing fibers such as glass fibers and ease of compatibility.
Examples of the comonomer other than ethylene and butene include α-olefins having 5 to 20 carbon atoms. Examples of the α-olefin having 5 to 20 carbon atoms include 1-hexene and 1-octene. The α-olefin copolymerized with propylene may be used alone or in combination of two or more.

The polyethylene-based resin may be a homopolymer of ethylene, or may be copolymerized with ethylene and a comonomer component such as α-olefin.

The melt mass flow rate (MFR), which is an index of the molecular weight of the polyolefin resin, is not particularly limited, but it is necessary that kneading, laminating and the like can be stably performed.

The MFR (230 ° C., 21.2 N load) of the polypropylene resin is preferably 1 g / 10 min or more, 100 g / 10 min or less, more preferably 5 g / 10 min or more, or 75 g / 10 min or less, and further. It is preferably 10 g / 10 min or more, or 50 g / 10 min or less.
The MFR (190 ° C., 21.2 N load) of the polyethylene resin is preferably 1 g / 10 min or more, 50 g / 10 min or less, more preferably 2 g / 10 min or more, or 35 g / 10 min or less, and further preferably. It is 5 g / 10 min or more, or 25 g / 10 min or less.

When the MFR of the polypropylene-based resin and the polyethylene-based resin is at least the above lower limit, it becomes easy to follow the mold during press molding. On the other hand, when it is not more than the above upper limit, there is no possibility that the resin will flow out from the molding die due to pressurization during press molding, and the resin impregnation between the carbon fiber and the glass fiber becomes easy.

Here, MFR is a value measured in accordance with JIS K7210-1999 "Test method for melt flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic".

The method for producing the polyolefin resin is not particularly limited, and a known polymerization method, for example, an ion polymerization method using a radical polymerization method, a Ziegler catalyst, a metallocene catalyst, a Phillips catalyst, or the like can be adopted.

(2) Polycarbonate resin The polycarbonate resin that can be used in the present invention may be either a homopolymer or a copolymer. Further, the polycarbonate resin may have a branched structure, a linear structure, or a mixture of the branched structure and the linear structure. Further, a plurality of polycarbonate-based resins may be mixed and used.
The so-called polyester carbonate resin (resin having both an ester bond and a carbonate bond in the molecular chain) is also included in the polycarbonate resin.

Bisphenols are mentioned as a typical example of the dihydric alcohol (diol) constituting the polycarbonate resin, and 2,2-bis (4-hydroxyphenyl) propane, that is, bisphenol A is particularly preferably used.
A polycarbonate resin using a diol other than bisphenol A alone or in combination with a plurality of diols may be used, and any of aromatic diols, aliphatic diols, and alicyclic diols may be used.

The melt mass flow rate (MFR) of the polycarbonate resin is measured according to JIS K7210 (1999) under the conditions of a temperature of 300 ° C. and a load of 1.2 kgf, and is preferably 1 g / 10 min or more and 50 g / 10 min or less, preferably 2 g. It is more preferably 10 min or more, or 35 g / 10 min or less, and particularly preferably 3 g / 10 min or more, or 30 g / 10 min or less. When the MFR is 1 g / 10 min or more, it becomes easy to follow the mold during press molding. On the other hand, when it is 40 g / 10 min or less, there is no possibility that it will flow out from the molding die due to pressure during press molding, and resin impregnation between carbon fibers and glass fibers becomes easy.

The method for producing the polycarbonate resin is not particularly limited, and examples thereof include known polymerization methods such as a phosgene method, a transesterification method, and a pyridine method.

(3) Polyamide-based resin As the polyamide-based resin that can be used in the present invention, an aliphatic polyamide is preferable, one obtained by ring-opening homopolymerization of ω-amino acid, and one obtained by ring-opening copolymerization of different ω-amino acids. Those obtained by copolymerization of diamine and dicarboxylic acid, and the like. In addition, aromatic polyamide and aromatic-aliphatic polyamide can also be used.

In the case of aliphatic polyamide, the melt mass flow rate (MFR) of the polyamide resin is measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kgf according to JIS K7210 (1999), and is 0.1 g / 10 min or more and 60 g / 10 min. It is preferably 0.5 g / 10 min or more, more preferably 30 g / 10 min or less, and particularly preferably 1 g / 10 min or more, or 20 g / 10 min or less. When the MFR is 0.1 g / 10 min or more, it becomes easy to impregnate the mold during press molding. On the other hand, when it is 60 g / 10 min or less, there is no possibility that it will flow out from the molding die due to pressure during press molding, and resin impregnation between carbon fibers and glass fibers becomes easy.

The method for producing the polyamide resin is not particularly limited, and a known polymerization method can be adopted.

(4) Polyester-based resin Examples of the polyester-based resin that can be used in the present invention include aliphatic polyester-based resins and aromatic polyester-based resins. Among them, aromatic polyester-based resins are preferable from the viewpoint of heat resistance and moldability of the thermoplastic resin laminate, and specific examples thereof include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polytrimethylene terephthalate.

The melt mass flow rate (MFR) of the polyester resin is measured according to JIS K7210 (1999) under the conditions of a temperature of 230 ° C. and a load of 2.16 kgf, and is preferably 0.1 g / 10 min or more and 60 g / 10 min or less. , 0.5 g / 10 min or more, or 30 g / 10 min or less, and particularly preferably 1 g / 10 min or more, or 20 g / 10 min or less. When the MFR is 0.1 g / 10 min or more, it becomes easy to impregnate the mold during press molding. On the other hand, when it is 60 g / 10 min or less, there is no possibility that it will flow out from the molding die due to pressure during press molding, and resin impregnation between carbon fibers and glass fibers becomes easy.

The method for producing the polyester resin is not particularly limited, and a known polymerization method can be adopted.

The core layer is preferably made of a thermoplastic resin composition containing various additives in addition to the above-mentioned thermoplastic resin.
Specific examples of the additives that can be contained in the thermoplastic resin composition include colorants containing pigments such as carbon black, flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, and cross-linking agents. Examples thereof include lubricants, nucleating agents, plasticizers, antioxidants, antioxidants, light stabilizers, ultraviolet absorbers, neutralizers, antifogging agents, antiblocking agents, slip agents and the like.

(Glass fiber)
As described above, the core layer may further contain glass fibers in order to further increase the rigidity of the present laminate, and the thermoplastic resin composition preferably contains glass fibers.
Since the core layer contains glass fiber as the reinforcing fiber, the mechanical strength and impact resistance of the thermoplastic resin laminate can be further enhanced.
Only one type of glass fiber may be used, or two or more types having different materials, average fiber lengths, fiber diameters, etc. may be used.

As the glass fiber, generally commercially available one can be appropriately used. The fiber diameter of the glass fiber is preferably 8 to 20 μm, more preferably 10 to 15 μm, and the average fiber length of the glass fiber is preferably 20 to 200 mm, more preferably 25 to 200 mm. When the diameter of the glass fiber is 8 μm or more, the price is suppressed and it is excellent in economy, and when it is 20 μm or less, it is excellent in mechanical strength. From the viewpoint of mechanical strength and impact resistance, the glass fiber is preferably a mixture of glass fibers of various lengths. Further, it is preferable to use it as a fiber bundle containing 100 to 4,000 such single fibers in one fiber bundle.

The breaking elongation of the glass fiber is preferably 2.0% or more, more preferably 2.5% or more, still more preferably 3.0% or more. When the breaking elongation of the glass fiber is 2.0% or more, the impact resistance of the present laminate is likely to be in a more practical range. The upper limit of the breaking elongation rate of the glass fiber is not particularly limited, but the breaking elongation rate of the glass fiber is usually 3 to 5% or less.

The glass fiber that can be contained in the core layer preferably has a higher elongation at break than the carbon fiber used for the front and back layers. Specifically, the difference between the breaking elongation rate (%) of the glass fiber and the breaking elongation rate (%) of the carbon fiber is preferably about 1.0 to 5.0 (%). When the difference in the elongation at break is within this range, the laminated body can exhibit excellent mechanical strength and impact resistance.

The core layer preferably contains glass fiber and a thermoplastic resin, and the content of each component is 30 to 400 parts by weight, preferably 50 to 300 parts by weight of the thermoplastic resin with respect to 100 parts by weight of the glass fiber. , More preferably 60 to 200 parts by weight. Further, the core layer preferably contains glass fiber and a thermoplastic resin in a total amount of 30% by weight or more, and particularly preferably 30 to 100% by weight. When the thermoplastic resin content is in the above range, the laminate is excellent in mechanical strength and has an excellent balance between mechanical strength and impact resistance.

From the viewpoint of impact resistance, the thickness of the core layer is preferably 1.5 mm or more, more preferably 2.0 mm or more, and even more preferably 2.5 mm or more.
Further, the thickness ratio of the core layer to the main laminated body [(thickness of the core layer / total thickness of the main laminated body) × 100] is in the range of 60 to 90%, which means that the uniform follow-up during press shaping. It is preferable from the viewpoint of the balance between the properties and the mechanical strength of the thermoplastic resin laminate and the cost.

The core layer is produced by laminating one or more thermoplastic resin sheets made of the thermoplastic resin composition containing the above-mentioned thermoplastic resin.
When the core layer further contains glass fibers, a glass fiber sheet made of glass fibers and a thermoplastic resin sheet may be laminated and used, or a thermoplastic resin sheet made of a thermoplastic resin composition containing glass fibers. (Thermoplastic resin sheet containing glass fiber) may be used. When laminating a glass fiber sheet and a thermoplastic resin sheet, one or a plurality of each sheet can be used. When a plurality of glass fiber sheets are used, the glass fiber sheets and the thermoplastic resin sheets may be laminated alternately or randomly, or the glass fiber sheets and the thermoplastic resin sheets may be laminated. It may be overlapped with the sheet. When the thermoplastic resin sheet containing glass fiber is also used, one or more thermoplastic resin sheets containing glass fiber can be used. A glass fiber sheet may be further laminated on the thermoplastic resin sheet containing glass fiber, or a reinforcing fiber sheet other than the glass fiber may be further laminated, if necessary.
Among the above, the core layer is preferably manufactured by using one thermoplastic resin sheet containing glass fibers or by laminating a plurality of sheets from the viewpoint of increasing the mechanical strength of the laminated body.

The thermoplastic resin sheet containing glass fiber is preferably glass fiber paper or glass fiber mat. Here, both "glass fiber paper" and "glass fiber mat" are sheets in which fiber bundles are opened, dispersed, molded by a wet method, a dry method, or the like, and then made into a flat film.

Glass fiber paper and glass fiber mats are usually manufactured by either the dry non-woven fabric method or the wet papermaking method, but those manufactured by the dry non-woven fabric method are used from the viewpoint of better productivity and better fiberglass opening. It is preferable to use it.

The thermoplastic resin sheet containing glass fibers may be a so-called prepreg in which glass fibers are impregnated with the above-mentioned thermoplastic resin such as a polyolefin resin. Generally, the "glass fiber mat" is distinguished from the "glass fiber paper" in terms of the content, thickness and the like of the thermoplastic resin. Generally, the glass fiber mat has a higher content of thermoplastic resin and a thicker thickness than the glass fiber paper.

The thermoplastic resin sheet containing glass fibers preferably has a large basis weight (glass fiber amount and thermoplastic resin) from the viewpoint of mechanical strength and impact resistance of the present laminate. Considering the balance between the productivity and cost of the sheet itself, the basis weight (glass fiber amount) of the thermoplastic resin sheet is preferably 50 to 400 g / m ² , more preferably 50 to 350 g / m ² , and particularly preferably 50 to 350 g / m 2. Is 50 to 300 g / m ² . The amount of the thermoplastic resin in the glass fiber sheet is preferably about 0 to 70% by weight with respect to the carbon fiber.

The thickness of the thermoplastic resin sheet containing glass fibers is not particularly limited, and varies depending on whether the thermoplastic resin sheet containing glass fibers is used as a single-layer sheet or a laminated sheet of a plurality of thermoplastic resin sheets containing glass fibers. However, it is usually about 100 to 5000 μm.

[Front and back layers]
The front and back layers are layers that mainly contribute to increasing the rigidity of the main laminate, and are layers containing carbon fibers.
The carbon fiber may be either pitch-based carbon fiber or polyacrylonitrile-based carbon fiber (PAN-based carbon fiber), and these may be used in combination, but the PAN-based fiber is hard to break in the process of producing the reinforcing fiber mat. Carbon fiber is preferred. As the carbon fiber, one type may be used alone, or two or more types may be mixed and used.

From the viewpoint of the mechanical strength of the laminated body, particularly from the viewpoint of facilitating the development of high rigidity in the bending test, it is possible to arrange carbon fibers having a low fracture elongation rate and a high tensile elastic modulus on the front and back layers of the laminated body. preferable.
Therefore, as described above, when the core layer contains glass fibers, it is preferable to use carbon fibers having a lower elongation at break than the glass fibers for the front and back layers.

The fiber length of the carbon fiber is preferably 30 to 200 mm, more preferably 35 to 200 mm, further preferably 40 to 200 mm, and even more preferably 40 to 100 mm. The ratio of the carbon fiber having such a fiber length is preferably 25 to 100 parts by weight, particularly preferably 30 to 100 parts by weight, out of 100 parts by weight of the carbon fiber. When the fiber length of the carbon fiber of 25 parts by weight or more out of 100 parts by weight of the carbon fiber is 30 mm or more, the mechanical strength of the present laminate is more excellent.
From the viewpoint of mechanical strength, it is preferable that the fiber length of carbon fiber is as long as continuous fiber, but from the viewpoint of fiber defibration and dispersibility in the process of producing a non-woven fabric containing carbon fiber by a dry method, carbon fiber fiber. The length is usually 100 mm or less.

Since the carbon fiber has the above-mentioned fiber length, the flexural modulus of the present laminate can be maintained and the impact resistance can be balanced.

Here, the fiber length of the carbon fiber can be measured by the method described in the section of Examples described later.

The elongation at break of the carbon fiber is preferably 1.0% or more, more preferably 1.4% or more, still more preferably 1.5% or more. When the breaking elongation of the carbon fiber is 1.0% or more, it is easy to maintain the impact resistance of the laminated body within the practical range. Further, from the viewpoint of impact resistance, the larger the breaking elongation rate of the carbon fiber is, the more preferable, but the above-mentioned breaking elongation rate of the carbon fiber is usually 2.5% or less.

The front and back layers may contain only one type of the above carbon fibers, or may contain two or more types of carbon fibers having different materials, fiber lengths, fiber diameters, and the like.
Further, the carbon fibers in the outermost layer and the carbon fibers in the back layer may be the same or different, but they are the same from the viewpoint of convenience of material procurement and suppression of warpage of the laminated body. Is preferable.

In addition to the carbon fibers, the front and back layers may contain the above-mentioned thermoplastic resin such as a polyolefin resin as a binder resin so that the carbon fibers do not easily dissociate from each other. Further, the front and back layers may contain various additives that can be contained in the thermoplastic resin composition constituting the core layer, if necessary.
When the front and back layers contain a thermoplastic resin, the content of the thermoplastic resin in the front and back layers is preferably 0 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the carbon fiber, particularly 50 parts by weight. It is preferably 150 parts by weight or less. Further, it is preferable that the front and back layers contain reinforcing fibers and a thermoplastic resin as main components in a total amount of 90% by weight or more, particularly 95 to 100% by weight. When the content of the thermoplastic resin in the front and back layers is 50 parts by weight or more with respect to 100 parts by weight of the carbon fibers, it becomes easy to secure a sufficient amount of carbon fibers in the front and back layers, and the thermoplastic resin laminate is bent. It becomes easy to secure the rigidity.

The thickness of the outermost layer and the outermost layer is 0.1 mm or more, preferably 0.2 mm or more, and more preferably 0.3 mm or more as the thickness of each of the outermost layer and the innermost layer, from the viewpoint of increasing the rigidity of the laminated body. More preferred.
Further, the thickness ratio of the outermost layer and the innermost layer to the present laminated body, that is, [(thickness of the outermost layer / total thickness of the present laminated body) × 100] and [(thickness of the outermost layer / total thickness of the present laminated body) ) × 100] is preferably in the range of 2 to 30%. The thicknesses of the outermost layer and the outermost layer may be different, but it is preferable that they are the same from the viewpoint of suppressing warpage of the present laminated body.

The front and back layers are usually made by preparing a sheet containing the carbon fibers described above and laminating one or more of the carbon fiber sheets. Alternatively, a carbon fiber sheet and a thermoplastic resin sheet may be produced respectively, and these may be produced by laminating them. At that time, if necessary, a reinforcing fiber sheet other than carbon fiber, or a reinforcing fiber other than carbon fiber and a thermoplastic resin sheet may be laminated and used.

The method for producing the carbon fiber sheet is not particularly limited, but the carbon fiber sheet is preferably carbon fiber paper or carbon fiber mat. Here, both the "carbon fiber paper" and the "carbon fiber mat" are sheets in which fiber bundles are opened, dispersed, molded by a wet method, a dry method, or the like, and then made into a flat film.

The carbon fiber sheet is usually produced by either a dry nonwoven fabric method or a wet papermaking method, but it is preferable to use one produced by the dry nonwoven fabric method from the viewpoint of improving productivity and fiber opening.

As described above, the front and back layers may contain a thermoplastic resin, and as a carbon fiber sheet, a so-called prepreg in which the fiber is impregnated with a binder resin made of the above-mentioned thermoplastic resin such as a polyolefin resin is used. May be good. Generally, the "carbon fiber mat" is distinguished from the "carbon fiber paper" in terms of the content, thickness and the like of the binder resin. Generally, the carbon fiber mat has a higher content of the binder resin and is thicker than the carbon fiber paper.

The carbon fiber sheet preferably has a large basis weight (reinforcing fiber amount and binder resin) from the viewpoint of mechanical strength and impact resistance, but in consideration of the balance between the productivity and cost of the sheet itself, the carbon fiber sheet The basis weight (carbon fiber amount) is preferably 50 to 400 g / m ² , more preferably 50 to 350 g / m ² , and particularly preferably 50 to 300 g / m ² . The amount of the binder resin of the carbon fiber sheet is preferably about 0 to 70% by weight with respect to the carbon fiber.

The thickness of the carbon fiber sheet is not particularly limited, and varies depending on whether the carbon fiber sheet is used as a single-layer sheet or as a plurality of carbon fiber sheets or a laminated sheet of carbon fibers and a thermoplastic resin sheet, but it is usually used. It is about 100 to 5000 μm.

[Metal sheet layer]
The metal sheet layer is interposed between the front and back layers and the core layer. That is, the metal sheet layer intervenes both between the outermost layer and the core layer and between the innermost layer and the core layer. The metal sheet layer exists to reduce the amount of deformation (deflection amount) of the laminated body when the main laminated body is impacted, and the elongation at the time of the tensile test is 10% or more (JISZ2241 compliant). ..
The metal sheet layer is not particularly limited as long as the elongation at the time of the tensile test is 10% or more, but is preferably made of aluminum having a purity of 99.99% or more for the reason of improving impact resistance.
Here, the elongation of the metal sheet layer in the tensile test of 10% or more means that the elongation of the metal sheet layer when the tensile strength is 60 N / mm ² and the temperature is 20 ° C. is 10% or more. ..

The thickness of the metal sheet layer is preferably 0.3 mm or more, preferably 0.4 mm or more, and more preferably 0.5 mm or more from the viewpoint of impact resistance.
Further, the thickness ratio of the metal sheet layer to the present laminate, that is, [(thickness of the metal sheet layer / total thickness of the present laminate) × 100] is from the viewpoint of impact resistance, high rigidity, and cost of the present laminate. Therefore, it is preferably in the range of 2 to 30%, more preferably 5 to 30%, and even more preferably 10 to 30%. The thickness of the metal sheet layer interposed between the outermost layer and the core layer and the thickness of the metal sheet layer interposed between the outermost layer and the core layer may be different but are the same. This is preferable from the viewpoint of suppressing the warp of the present laminated body.

For the metal sheet layer, a thermoplastic resin sheet is laminated on the front and back surfaces of the metal sheet layer in order to improve the adhesiveness to the front and back layers containing carbon fibers and the core layer; or a chemical solution is provided on the front and back surfaces of the metal sheet layer. It is preferable to carry out a treatment of adding minute irregularities by a chemical solution treatment or the like to impart the above; or a treatment in which both are combined.
The thermoplastic resin sheet is a sheet containing the above-mentioned thermoplastic resin, and may further contain various additives.

As a method of making unevenness on the front and back of the metal sheet layer, the above-mentioned chemical treatment; a method of forming holes on the metal surface with a laser; a film (oxide film, etc.) is formed on the surface of the metal sheet layer, and the resin is used with a thermoplastic resin. Methods for expecting chemical bonds and the like are generally disclosed, and any one or a combination thereof can be used.

[Method for producing this laminate]
The method for producing the laminated body is not particularly limited as long as it is a method capable of forming a layer structure of the outermost layer / metal sheet layer / core layer / metal sheet layer / innermost layer. For example, the present laminated body can be produced by laminating the sheets described in the description of each layer.

As described above, in the metal sheet layer, it is preferable to laminate a thermoplastic resin sheet on the front and back surfaces of the metal sheet layer in order to improve adhesion to the front and back layers and the core layer containing carbon fibers.
That is, in the present invention, molding is performed with the structure of the outermost layer / thermoplastic resin layer / metal sheet layer / thermoplastic resin layer / core layer / thermoplastic resin layer / metal sheet layer / thermoplastic resin layer / innermost layer. Is preferable.

The present laminated body may have other layers other than the front and back layers, the metal sheet layer, and the core layer. When the other layers are provided, similarly, a sheet constituting the other layers is produced. Other layers may be laminated in the front and back layers, the metal sheet layer, and the core layer. For example, when a flame retardant layer or the like is laminated between the metal sheet layer and the core layer as another layer, the flame retardant is molded into a sheet shape, and the flame retardant sheet is placed between the metal sheet and the thermoplastic resin sheet. It may be laminated. Further, a flame retardant may be blended with the thermoplastic resin composition to prepare a core layer.
When another layer is provided on the outer layer of the metal sheet layer, a sheet constituting the other layer may be prepared in advance and integrated at the time of manufacturing the present laminate, or a surface layer may be further provided after the manufacture.

More specifically, the present laminate is a single-layer sheet or laminated sheet for the front and back layers; a single-layer sheet or a laminated sheet for a metal sheet; a single-layer sheet or a laminated sheet for a core layer; Plastic resin sheets are prepared, respectively, and these are used as a single-layer sheet or laminated sheet for the outermost layer / single-layer sheet or laminated sheet for thermoplastic resin / sheet for metal sheet layer / single-layer sheet or laminated sheet for thermoplastic resin layer. / Single layer sheet or laminated sheet for core layer / Single layer sheet or laminated sheet for thermoplastic resin layer / Single layer sheet or laminated sheet for metal sheet layer / Single layer sheet or laminated sheet for thermoplastic resin layer / For back layer It can be manufactured by stacking single-layer sheets or laminated sheets in this order and press-molding them at an appropriate temperature and pressure. Alternatively, it can be manufactured by directly laminating the constituent sheets of each layer and press-molding them at an appropriate temperature and pressure without preparing a laminated sheet for each layer in advance.
The single-layer sheet or laminated sheet for the front and back layers can be obtained by using the carbon fiber sheet constituting the front and back layers as a single layer, or by laminating the required number of carbon fiber sheets and the thermoplastic resin sheet. can.
The single-layer sheet or laminated sheet for a metal sheet can be obtained by using the metal sheet as a single layer or by laminating a required number of fiber sheets and thermoplastic resin sheets.
As the single-layer sheet or laminated sheet for the core layer, the thermoplastic resin sheet containing the glass fiber constituting the core layer is used in a single layer or two or more layers, or the required number of the glass fiber sheet and the thermoplastic resin sheet are laminated. Can be obtained by
The thermoplastic resin sheet constituting the thermoplastic resin layer can be obtained by using the required number of thermoplastic resin sheets constituting the thermoplastic resin layer as a single layer or laminating them.

Here, when manufacturing a laminated sheet for the front and back layers, the laminated sheet of the carbon fiber sheet and the thermoplastic resin sheet is appropriately laminated with one or more carbon fiber sheets and the thermoplastic resin sheet alternately. Is preferable. When a plurality of carbon fiber sheets are used, the plurality of carbon fiber sheets may be the same or may have different types and thicknesses of carbon fibers, but the same is convenient for material procurement. It is preferable from the viewpoint of sex. When the laminated sheet for the core layer is manufactured by laminating a glass fiber sheet and a thermoplastic resin sheet, when two or more layers of a thermoplastic resin sheet containing glass fibers are used, and when two or more layers of a thermoplastic resin sheet are used. The same is true.

The press molding conditions differ depending on the type of the thermoplastic resin used for each layer, but the press molding temperature is preferably in the range of 170 to 290 ° C, more preferably in the range of 170 to 280 ° C. The press pressure is preferably in the range of 0.5 to 6 MPa, more preferably in the range of 1 to 6 MPa.
By press molding in such a range, a laminate having an excellent balance between mechanical strength and impact resistance can be produced.

The present laminate may be produced by a so-called batch method, or may be produced by a continuous press method in which these sheets are laminated and continuously press-formed while producing reinforcing fibers or thermoplastic sheets used for each layer. good.

The thickness (total thickness) of the present laminate is not particularly limited, but is preferably 3.0 mm or more, more preferably 10.0 mm or less, and further preferably 3.5 mm or more and 10.0 mm or less. It is preferable, and it is particularly preferable that it is 4.0 mm or more and 10 mm or less. When the thickness of the present laminate is 3.0 mm or more, the present laminate; and the product obtained by press-molding the present laminate are excellent in surface appearance. Further, when the thickness of the laminated body is 10.0 mm or less, the laminated body is excellent in press formability.

By providing the outermost layer, which mainly contributes to high rigidity, and the core layer, which mainly contributes to press shaping, within the above thickness range, a characteristic balance such as uniform mold followability and mechanical strength balance during press shaping can be achieved. An excellent laminated body can be obtained.

From the viewpoint of suppressing warpage, the laminated body is preferably configured to be symmetrical in the thickness direction with the core layer as the center.

Hereinafter, examples for describing the present invention more specifically will be shown, but the present invention is not limited to the specific embodiments shown in the following examples.

1. 1. Materials used (1) Carbon fiber / polyacrylonitrile-based carbon fiber used to prepare the carbon fiber sheet: Mitsubishi Chemical Co., Ltd., trade name "Pyrofil TR40", elongation at break = 2.0%, fiber diameter = 7-9 μm, Fiber length 40 mm

(2) Aluminum sheet / High-purity aluminum sheet: Made by Izumi Metal Co., Ltd., product name "5N-H", purity 99.999%
-General aluminum sheet: Japanese Industrial Standards (JIS) product "A5052", purity 99.52%
Each aluminum sheet was subjected to a tensile test at a temperature of 20 ° C. and a tensile strength of 60 N / mm ² using a tensile tester manufactured by Shimadzu Corporation. As a result, a 0.3 mm high-purity aluminum sheet and a 0.5 mm high-purity aluminum sheet were tested. The elongation of the aluminum sheet was 15%. The elongation of the 0.5 mm general aluminum sheet was 7%.

(3) Thermoplastic resin sheet containing glass fiber and glass fiber reinforced polypropylene plate used for producing the core layer: Made by Quadrant Co., Ltd., trade name "GMT (P4038)", glass fiber breaking elongation rate = 4%, glass fiber 100 Ratio of polypropylene resin to parts by weight = 150 parts by weight

(4) Thermoplastic resin (adhesive component between the metal sheet layer and the core layer or front and back layers)
-Polypropylene resin (PP): Mitsubishi Chemical Corporation, trade name "Modic P908" (acid-modified PP resin)

2. 2. Preparation of each sheet (1) Preparation of carbon fiber sheet for forming the outermost layer Using the method of manufacturing a non-woven fabric by a dry method, a carbon fiber cut fiber having a fiber length of 40 mm is opened with a card machine, and a manufacturing method using a needle punching machine. A carbon fiber sheet having a basis weight of 150 g / m ² and a thickness of 4 mm was prepared.

(2) Preparation of Aluminum Sheet for Forming Metal Sheet Layer A high-purity aluminum sheet having a thickness of 0.3 mm or 0.5 mm was used, and a general aluminum sheet having a thickness of 0.5 mm was used.
The obtained high-purity aluminum sheet and general aluminum sheet were each immersed in hydrochloric acid, and the surface was immersed until unevenness having a height difference of 20 μm was formed, and the surface of the aluminum sheet was made uneven.

(3) Preparation of Glass Fiber-Containing Thermoplastic Resin Sheet for Core Layer Formation The above-mentioned glass fiber-reinforced polypropylene plate [GMT (P4038) manufactured by Quadrant Co., Ltd.] was used as the glass fiber-containing thermoplastic resin sheet.

(4) Preparation of Thermoplastic Resin Sheet for Forming Thermoplastic Resin Layer Acid-modified polypropylene resin (PP) (Modic P908) was melt-kneaded using an extrusion seating device. The resin melt-kneaded from the extruder was discharged from the T-die base, and a thermoplastic resin sheet (PP sheet) having a thickness of 30 μm was formed using a casting device and a take-up device.

3. 3. Example and Comparative Example [Example 1]
One carbon fiber sheet (A1) as the outermost layer, five thermoplastic resin sheets (D) as the thermoplastic resin layer, and one high-purity aluminum sheet (B1) (0.5 mm thickness) as the metal sheet layer. One thermoplastic resin sheet (D) as the thermoplastic resin layer, a glass fiber reinforced polypropylene plate (C) (GMT, 3.8 mm thickness) as the core layer, and a thermoplastic resin sheet (D) 1 as the thermoplastic resin layer. A sheet, one high-purity aluminum sheet (B2) as a metal sheet layer (0.5 mm thickness), five thermoplastic resin sheets (D) as a thermoplastic resin layer, and a carbon fiber sheet (A2) as the innermost layer. One sheet was laminated in the order of A1 / D / B1 / D / C / D / B2 / D / A2, press-molded under the conditions of temperature = 180 ° C., pressure = 3 MPa, time = 15 minutes, and thermoplastic resin. A laminate was obtained.
When the thickness of each layer of the obtained thermoplastic resin laminate was measured, the thickness of each of the carbon fiber layer (outermost layer) / aluminum sheet / core layer / aluminum sheet / carbon fiber layer (backmost layer) was 0. It was 46 mm / 0.54 mm / 2.87 mm / 0.53 mm / 0.35 mm.

[Example 2]
The high-purity aluminum sheets (B1) and (B2) used for the metal sheet layer of Example 1 were prepared in the same manner as in Example 1 except that the thicknesses of the high-purity aluminum sheets (B1) and (B2) were 0.3 mm, respectively, to obtain a thermoplastic resin laminate. ..
When the thickness of each layer of the obtained thermoplastic resin laminate was measured, the thickness of each of the carbon fiber layer (outermost layer) / aluminum sheet / core layer / aluminum sheet / carbon fiber layer (backmost layer) was 0. It was 35 mm / 0.27 mm / 2.79 mm / 0.34 mm / 0.36 mm.

[Comparative Example 1]
The glass fiber reinforced PP plate used for the core layer of Example 1 was used. The thickness of this core layer was 3.63 mm.

[Comparative Example 2]
The glass fiber reinforced PP plate (C) of Comparative Example 1 was used as the core layer, and one carbon fiber sheet (A1) was used as the outermost layer; five thermoplastic resin sheets (D) and carbon fibers were used as the intermediate layer on the surface layer side. Combination of 1 sheet (A1) and 5 thermoplastic resin sheets (D); 1 carbon fiber sheet (A2) as the innermost layer; 5 thermoplastic resin sheets (D) as the intermediate layer on the back layer side, A combination of one carbon fiber sheet (A2) and five thermoplastic resin sheets (D); laminated in the order of A1 / D / A1 / D / C / D / A2 / D / A2. , Temperature = 180 ° C., Pressure = 3 MPa, Time = 15 minutes, and press molding was performed to obtain a thermoplastic resin laminate.
When the thickness of each layer of the obtained thermoplastic resin laminate was measured, the thickness of each of the carbon fiber layer (outermost layer) / core layer / carbon fiber layer (backmost layer) was 0.94 mm / 2.09 mm /. It was 0.97 mm.

[Comparative Example 3]
The glass fiber reinforced PP plate (C) of Comparative Example 1 was used as the core layer, and one thermoplastic resin sheet (D) was used as the outermost layer; and one high-purity aluminum sheet (B1) was used as the metal sheet layer on the surface layer side. 0.3 mm thickness), a combination of 5 thermoplastic resin sheets (D) and 1 carbon fiber sheet (A1); 1 thermoplastic resin sheet (D) as the backmost layer; as a metal sheet layer on the back layer side A combination of one carbon fiber sheet (A2), five thermoplastic resin sheets (D), and one high-purity aluminum sheet (B2) (0.3 mm thickness); D / B1 / D / The layers were laminated in the order of A1 / C / A2 / D / B2 / D, and press-molded under the conditions of temperature = 180 ° C., pressure = 3 MPa, and time = 15 minutes to obtain a thermoplastic resin laminate.
When the thickness of each layer of the obtained thermoplastic resin laminate was measured, the thickness of each of the aluminum sheet (surface layer side) / carbon fiber layer / core layer / carbon fiber layer / aluminum sheet (back layer side) was 0. It was 35 mm / 0.36 mm / 2.60 mm / 0.38 mm / 0.37 mm.

[Comparative Example 4]
In the production of the thermoplastic resin laminate of Comparative Example 3, the high-purity aluminum sheets (B1) and (B2) used for the metal sheet layer were used as general aluminum sheets (B1) and (B2) (each having a thickness of 0.5 mm). ) Was used to obtain a thermoplastic resin laminate under the same laminated structure and press conditions.
When the thickness of each layer of the obtained thermoplastic resin laminate was measured, the thickness of each of the aluminum sheet (surface layer side) / carbon fiber layer / core layer / carbon fiber layer / aluminum sheet (back layer side) was 0. It was 37 mm / 0.44 mm / 2.64 mm / 0.45 mm / 0.46 mm.

3. 3. Measurement and Evaluation The thermoplastic resin laminates produced in Examples and Comparative Examples were evaluated for the mechanical strength and impact resistance shown below.

(1) Mechanical strength (flexural modulus)
The prepared thermoplastic resin laminate was cut into a width of 15 mm and a length of 100 mm, and a three-point bending test was performed at a distance between fulcrums = 80 mm, a speed = 5.3 mm / min, and a temperature = 23 ° C. according to JIS K7074, and bending strength was performed. And the flexural modulus was measured.
The flexural modulus was determined according to the following evaluation criteria, and the results are shown in Table 1.
◯: 9.0 GPa or more ×: less than 9.0 GPa

(2) Impact resistance (ball drop test)
The prepared thermoplastic resin laminate is cut into a width of 50 mm and a length of 150 mm, and set in a fixed vise of a falling ball impact test device (two sides in the longitudinal direction of the test piece are bitten by 25 mm and the distance between the vices is set to 100 mm). Then, the state of the sample when the falling weight (500 g) was dropped from a height of 120 cm was observed and evaluated according to the following criteria, and the results are shown in Table 1.
○: No surface crack on the back side of the falling ball ×: Surface crack on the back side of the falling ball

(3) Impact resistance (deformation test)
The prepared thermoplastic resin laminate is cut into a width of 50 mm and a length of 150 mm, and set in a fixed vise of a falling ball impact test device (two sides in the longitudinal direction of the test piece are bitten by 25 mm and the distance between the vices is set to 100 mm). Then, when the falling weight (500 g) was dropped from a height of 120 cm, the deformation of the sample was observed and evaluated according to the following criteria.
The falling spherical surface side was installed on a flat desk surface, and the gap generated by the deformation of the desk surface and the sample was evaluated by the gap, and the results are shown in Table 1. The amount of deformation is shown in Table 1.
○: Less than 1 mm ×: 1 mm or more

As shown in Table 1, the thermoplastic resin laminate of the present invention produced in the examples has an excellent balance between mechanical strength (rigidity) and impact resistance.
On the other hand, the laminated body of the comparative example which does not satisfy the conditions specified in the present invention is inferior in mechanical strength (rigidity) or impact resistance.

This laminate is excellent in mechanical strength, especially bending elasticity and impact resistance, has an excellent balance between the two, and is a laminate that can meet the demands of light weight and cost reduction, so that it is large. It can be suitably used for various molded products such as housings of electric appliances, interior materials of automobiles and railways, and exterior materials.

Claims (5)

With a core layer containing thermoplastic resin,
The front and back layers containing carbon fiber,
A metal sheet layer having an elongation of 10% or more at the time of a tensile test is provided between the core layer and the front and back layers.
A thermoplastic resin laminate in which the metal sheet layer is made of aluminum having a purity of 99.99% or higher . The thermoplastic resin laminate according to claim 1 , wherein the core layer further contains glass fibers. A core layer containing thermoplastic resin and glass fiber,
The front and back layers containing carbon fiber,
A metal sheet layer having an elongation of 10% or more during a tensile test between the core layer and the front and back layers.
Thermoplastic resin laminate having. The thermoplastic resin laminate according to any one of claims 1 to 3, wherein the thickness ratio of the metal sheet layer to the laminate is 2 to 30%. The thermoplastic resin laminate according to any one of claims 1 to 4 , wherein the carbon fiber is a polyacrylonitrile-based carbon fiber.