JPH05117411A - Fiber-reinforced thermoplastic resin sheet and its production - Google Patents

Abstract

PURPOSE:To obtain the title sheet improved in mechanical strengths by integrally laminating a layer of woven or knit fabric of a continuous carbon fiber with a layer of a fibrous structure comprising a heat-resistant fiber and having a specified interlacing strength by using a thermoplastic resin as a matrix. CONSTITUTION:At least one layer of a woven or knit fabric such as plainwoven carbon fiber fabric is laminated with a layer of a fibrous structure comprising a heat-resistant fiber such as a meta-oriented aramid fiber and having an interlacing strength of 1.0kg/mm<2> or above between two rectangularly angularly crossing yarns and at least one thermoplastic resin film of a polycarbonate in such a manner that the thermoplastic resin film is interposed between the above layers. The resulting laminate is molded under pressure at 250-300 deg.C in an open mold to obtain a fiber-reinforced thermoplastic resin sheet in which the total content of the woven or knit fabric and the fibrous structure is 30-70vol.%, the thermoplastic resin matrix is freed from voids larger than the fiber diameter, and the respective layers are inseparably and integrally laminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced thermoplastic resin sheet in which reinforcing fibers and a thermoplastic resin are integrated and a method for producing the same. In particular, it is lightweight, thin-walled, has good mechanical properties (mechanical properties) and excellent thermoformability (shapeability), and is suitable as a composite material for thermoforming. It relates to a method for industrial production.

[0002]

2. Description of the Related Art Sheets of thermoplastic resin reinforced with short fibers of glass fibers or carbon fibers or sheets of thermoplastic resin reinforced with mats of continuous glass fibers or continuous carbon fibers are commercially available as so-called stampable sheets. ing. Further, a composite material composed of a continuous glass fiber or a continuous carbon fiber reinforced thermoplastic resin sheet reinforced in one direction is also known.

JP-B-51-15880 discloses that a glass fiber and a carbon fiber are formed by laminating a thermoplastic resin layer containing a glass fiber and a carbon fiber layer, for example, a carbon fiber cloth, and heating and pressing them. A reinforced thermoplastic resin-based composite material is described.

Japanese Patent Publication No. 60-50146 discloses a stamping molding comprising a cloth-like material obtained by weaving continuous carbon fibers and a non-woven fibrous reinforcing material, for example, a randomly oriented mat of glass fibers. A sheet for use has been proposed. In Example 1, four sheets of carbon fiber woven fabric (“Torayca” cloth # 6344 manufactured by Toray Industries, Inc.), a random orientation mat of glass fibers (M8621 manufactured by Asahi Fiber Glass Co., Ltd. : 300 g / m ² ) 3 sheets and 8 nylon 6 sheets having a thickness of 0.3 mm are disclosed.

In the same publication, the non-woven fibrous reinforcing material in the sheet is intended to improve the fluidity of the resin layer at the time of molding. Since filling is easy and moldability is improved, it is possible to perform stamping molding on molded products that have bosses, ribs, etc., and the surface properties of molded products are improved, and the reinforcing effect of the carbon fiber cloth is effectively expressed. It is stated that it will be done.

However, as shown in a comparative example described later, when the sheet is molded by an open mold which is not completely sealed,
The outflow of the non-woven fibrous reinforcing material causes a problem such as a decrease in sheet thickness and an increase in thickness variation, and at the same time, irregular flow (fiber disorder) of the carbon fiber cloth material is obviously increased.

That is, when forming a sheet having a relatively simple shape such as a flat plate, an open mold is generally used because of its workability. In that case, the sheet thickness control ( That is, there are still problems such as occurrence of thickness variation), sheet yield (decrease in non-defective product rate due to carbon fiber disorder), and treatment of outflow burr. Further, even when a rectangular tray-shaped molded product is stamped by using the sheet, it is essential to use a mold close to a closed mold in order to prevent the non-woven and woven fibrous reinforcing material from flowing out.

Among the above-mentioned thermoplastic resin sheets, a sheet reinforced with a glass short fiber mat or a continuous glass fiber mat has a discontinuous reinforcement by reinforcing fibers (reinforcing fibers), and the reinforcing fibers are bulky. Due to the fact that the reinforcing fiber content (V _f ) in the sheet is low due to the fact that it is a structure or the like, the strength utilization rate of the reinforcing fibers is low, and therefore the mechanical properties are considerably low, limiting its use. ing.

On the other hand, in a thermoplastic resin sheet reinforced with glass fibers aligned in one direction, the strength utilization factor of the reinforcing fibers is large, so a sheet having excellent mechanical properties can be obtained, but the direction of reinforcement is Since it is limited to one direction, the mechanical properties in the direction perpendicular to the strengthening direction show only low mechanical properties possessed by the resin, and the sheet exhibits remarkable anisotropy. In order to provide such sheets with pseudo-isotropic physical properties, at least 3 to 4 ply unidirectionally reinforced thermoplastic resin sheets are laminated in different reinforced directions in order to have plane symmetry and thickness symmetry. Will be required. This results in increasing the thickness and the amount of reinforcing fibers more than necessary, resulting in an increase in material cost and a great deal of labor.

On the other hand, as means for improving the flame resistance of a fiber reinforced resin sheet which is required to have high mechanical properties and thermal characteristics, (a) a matrix resin constituting the fiber reinforced resin sheet has a high oxygen index. A method using a polymer, (b) a method of adding a flame retardant such as aluminum hydroxide, a halogen compound, an antimony oxide type compound and a phosphorus type compound to a matrix resin, or (c) a certain amount or less of inorganic fibers, a filler, etc. There is known a method of improving combustion resistance by adding

First, a polyphenylene sulfide sheet reinforced with carbon fiber or glass fiber is known as a sheet according to the method (a) in which a resin having a high oxygen index is used as a matrix resin constituting a fiber reinforced resin sheet. However, in such a sheet, the matrix resin to be formed is limited to a specific one, so that there is a problem that the fiber-reinforced resin sheet should be improved in sheet performance other than combustion resistance, manufacturing cost, moldability, and the like. In addition, general-purpose matrix resins that form commonly used fiber-reinforced resin sheets, such as unsaturated polyester resins, epoxy resins, nylon resins, and polycarbonate resins, have a low oxygen index, so these resins have good combustion resistance. I can't get anything.

On the other hand, in the method (b) in which the flame retardant is added to the matrix resin constituting the fiber reinforced resin sheet to improve the flame resistance, the flame resistance is improved, but the resin itself and the matrix resin are used. The mechanical properties of the fiber-reinforced resin sheet (especially elongation at break and impact resistance of the sheet) are remarkably lowered. Further arc resistance and C
The deterioration of electrical properties represented by TI-tracking value is also remarkable.

The above methods (a), (b) and (c) are used as means for improving the combustion resistance of a molded article made of resin itself or a fiber reinforced resin sheet having a relatively small content of reinforcing material. Can be said to be an effective method for the time being, despite the problems other than combustion resistance.

However, in the case of a so-called high V _f fiber-reinforced resin sheet containing a high proportion of short fiber reinforcement and continuous fiber reinforcement for the purpose of improving performance such as mechanical properties and thermal properties, the above-mentioned (b) is particularly preferable. ) And (c),
It is difficult to improve the flame resistance. This is because the reinforcing fibers that compose the fiber-reinforced resin sheet suppress the drip behavior of the matrix resin that composes the sheet (in general, the combustion resistance of plastics is significantly improved by the drip behavior of the molten / combustion resin). In addition, it is considered that it serves to increase the surface area of the molten / combustion matrix resin in contact with air in the atmosphere. The combustion resistance of the fiber reinforced resin sheet is determined by the combustion resistance performance of the matrix resin constituting it, but the combustion resistance performance of the matrix resin constituting the fiber reinforced resin sheet decreases due to the action of the above-mentioned reinforcing fibers, As a result, the flame resistance of the fiber-reinforced resin sheet also decreases.

Further, in the method (c) of adding inorganic fibers, fillers, etc., when the content of the inorganic fibers, fillers, etc. exceeds a certain value, conversely, the flame resistance of the resin composition decreases.
For example, the glass fiber amount added to the glass fiber reinforced polycarbonate resin is about 15 in volume content (V _f ).
Up to (%), the combustion resistance of the glass fiber reinforced resin sheet increases, but it is known that the addition of glass fibers in an amount larger than this lowers the combustion resistance of the glass reinforced resin sheet (" Plastics "Vol.30, No.4, P
51).

On the other hand, among the fiber reinforced resin molded products (FRP), as a molding method of a thermoplastic molded product using continuous reinforcing fibers, stamping molding using a press machine is the mainstream, but as another method. The vacuum molding method, autoclave molding method, and diaphragm molding method are used. Further, as a continuous molding method, a filament winding method, a tape lay-up method using a tape material, a drawing method, a roll forming method and the like are widely known as a molding method of a fiber reinforced thermoplastic resin.

Although stamping molding by a press is widely used as described above, it is impossible to mold a cylindrical molded product such as a cylinder by this method. Therefore, among the above methods, the filament winding method, the tape layup method, the pultrusion molding method, and the like are applied to the molding of a tubular molded product such as a cylinder, and the process is being put into practical use. However, since thermoplastic resins have high melting points and high melt viscosities, there is a problem in moldability centering on resin impregnation into reinforcing fibers. For example, in a special heating device using a laser used in the tape layup method. There are various problems to be solved such as necessity.

Therefore, it is practical to produce a tubular molded article such as a cylinder from a thermoplastic resin reinforced with continuous reinforcing fibers,
It is no exaggeration to say that there is no general-purpose molding method.

Moreover, the thermoplastic resin has a higher melting point than the thermosetting resin, and the melt viscosity thereof is several thousand times that of the thermosetting resin. Therefore, high-temperature and high-pressure conditions are indispensable for molding the thermoplastic resin, impregnation of the resin between the reinforcing fibers is difficult, and the molding equipment is large and inevitably expensive.

In order to facilitate impregnation of the thermoplastic resin into the reinforcing fibers, a method of using the reinforcing fibers and the thermoplastic resin fiberized in a woven or knitted woven or knitted form, a thermoplastic resin A method in which the powder is pulverized and used in a state of being sprinkled with a reinforcing fiber is used, but in these methods, the processing cost of the material is high and the material cost is high.

Further, in the above-mentioned filament winding method, tape layup method, and drawing method, it is difficult to form an ultralight cylinder made of a material having a sandwich structure in which a lightweight core material is sandwiched. In addition, the surface property of the molded product is insufficient, and the cylindrical molded product in the pultrusion molding has a large eccentricity of the inner and outer diameters, which requires secondary machining after molding.

[0022]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a fiber-reinforced thermoplastic resin sheet which is free from the above problems and has good moldability.

Another object of the present invention is to provide a fiber-reinforced thermoplastic resin sheet which is lightweight, thin-walled and has excellent mechanical properties.

Still another object of the present invention is to use a continuous fiber knitted woven fabric of carbon fibers and a fiber structure composed of heat resistant fibers, and fibers having excellent mechanical properties substantially free of voids. It is to provide a reinforced thermoplastic resin sheet.

Still another object of the present invention is to provide a flame-retardant fiber-reinforced thermoplastic resin sheet having the above-mentioned excellent properties and further improved in combustion resistance.

Still another object of the present invention is to provide a flame-retardant fiber reinforced thermoplastic resin sheet having a high V _f .

Still another object of the present invention is to provide a method for industrially producing the above fiber reinforced thermoplastic resin sheet of the present invention.

Still another object of the present invention is to use a curved sheet capable of stably forming a cylinder having an ultralight weight, a high roundness and an excellent design property as a fiber reinforced thermoplastic resin sheet of the present invention in a flat plate press. An object of the present invention is to provide a method that can be easily manufactured by using general equipment such as a machine.

Further objects and advantages of the present invention will be apparent from the following description.

[0030]

According to the present invention, the above objects and advantages of the present invention are as follows: (a) a continuous fiber woven or knitted carbon fiber is impregnated with a matrix resin made of a thermoplastic resin. At least one of the first layers consisting of:
(B) At least one second layer comprising a heat-resistant fiber structure impregnated with a matrix resin made of a thermoplastic resin, and the first layer (a) and the second layer. A fiber-reinforced thermoplastic resin sheet in which a layer (b) and a layer (b) are laminated in a non-separated manner, wherein the second layer (b) has a heat resistance that is substantially evenly distributed in a matrix resin in a cross section of the sheet. Of the heat-resistant fibers and substantially free of voids exceeding the fiber diameter of the heat-resistant fibers, and the fiber structure used in the second layer (b) is less in any two orthogonal directions. And a fiber-reinforced thermoplastic resin sheet having a entanglement strength of 1.0 kg / mm ² .

The fiber-reinforced thermoplastic resin sheet of the present invention comprises
As described above, the laminated body is composed of at least one layer of the first layer (a) and at least one layer of the second layer (b).

The first layer (a) is one in which at least one continuous fiber knitted fabric of carbon fibers is present in a matrix resin composed of a thermoplastic resin. The continuous fiber knitted woven fabric of carbon fibers is not particularly limited, and a plain weave, a twill weave, a satin weave, a roving cloth and the like made of generally available continuous fibers can be preferably used.

Examples of the thermoplastic resin serving as the matrix resin include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, polyphenylene sulfide, ABS and polymers thereof. A copolymer consisting of two or more of the above structural units is preferably used.

These thermoplastic resins may contain additives such as colorants, stabilizers, plasticizers, flame retardants and ultraviolet absorbers.

The second layer (b) is such that at least one fibrous structure made of heat resistant fibers is present in a matrix resin made of a thermoplastic resin.

The heat-resistant fiber must be made of a material that retains rigidity even in the thermocompression molding described later. For this purpose, a material having a glass transition point (Tg) of 150 ° C. or higher is preferably used. To be done.

Examples of such heat resistant fibers include meta-aramid fibers, para-aramid fibers, polyarylate fibers, polyacrylonitrile fibers, polybenzimidazole fibers, polyethylene terephthalate fibers, polyethylene-2,6-naphthalate fibers and cellulose fibers. An organic heat resistant fiber selected from the group consisting of the following is preferably used.

The fiber structure made of the heat resistant fiber as described above may be in various forms such as bulky knitted fabric, non-woven fabric or mat. Of these, the form of non-woven fabric or mat is preferred, and non-woven fabric is particularly preferred.

Such a fiber structure must have sufficient interfiber entanglement and an entanglement strength of at least 1.0 kg / mm ² in two orthogonal directions, for example, two fiber directions. If the entanglement strength is less than 1.0 kg / mm ² , the heat-resistant fibers will flow out significantly in open mold molding, for example.
Various problems such as uneven thickness of the sheet, uneven quality of the sheet, disorder of the continuous fiber knitted fabric of carbon fiber, necessity of treatment of the outflow burr portion and the like occur. The preferred confounding strength in the present invention is 1.
It is a ^{5kg / mm 2 ~10kg / mm 2} .

As a means for imparting an entanglement strength of at least 1.0 kg / mm ^{2 to} the fiber structure, for example, a method in which the heat-resistant fiber is crimped, formed into a web, and further needling is effective. Is. A nonwoven fabric or mat made of this crimped fiber becomes bulky, and this bulkiness improves the impregnability of the thermoplastic resin as described later, and is also effective for stably manufacturing a sheet that is lightweight and has excellent mechanical properties. Act on. In addition, the needling has an additional advantage that the handling of the fiber structure is improved. A preferable example of the fiber structure which is entangled by such needling is a spunlace obtained by applying a water jet needle to a web of crimped meta-aramid fiber. Of course, the means for imparting a certain level of entanglement strength in a high temperature state is not limited to the above needling method.

The fibrous structure has a bulkiness of preferably at least 8 and more preferably 10 to 20 before being impregnated in the thermoplastic resin. With a bulky fiber structure of less than 8, impregnation with the resin is likely to be insufficient, the volume content (V _f ) of the carbon fiber cloth layer in the obtained sheet is lowered, and the cloth layer is inside the sheet. It may be slightly offset. Therefore, the mechanical properties of the obtained sheet are often low.

As the thermoplastic resin used in the second layer (b), the same thermoplastic resin as used in the first layer can be exemplified. The polymer of the heat resistant fiber must naturally have a higher melting point than the thermoplastic resin of the matrix resin.

The fiber-reinforced thermoplastic resin sheet of the present invention contains at least one of the above-mentioned first layer (a) and second layer (b). When the first layer and the second layer are adjacent to each other, the second layer is non-separably laminated between the plurality of first layers. When the plurality of first layers are adjacent to each other, the plurality of first layers are non-separated and integrally laminated,
In addition, when the plurality of second layers are adjacent to each other, the plurality of second layers are non-separably integrated, and the first layer and the second layer are also non-separably integrated. In the sheet of the present invention, the thermoplastic resin of the first layer and the thermoplastic resin of the second layer may be the same or different, but are preferably the same.

The sheet of the present invention has the heat-resistant fibers substantially uniformly distributed in the matrix resin, and has substantially no voids having a size exceeding the fiber diameter of the heat-resistant fibers. .. That is, the sheet of the present invention has the heat-resistant fibers substantially uniformly distributed in the matrix resin in the cross section of the sheet, and has no void exceeding the fiber diameter of the heat-resistant fiber. Observation of the sheet cross section is advantageously performed by observing the sheet cross section with a microscope, for example, at a magnification of 85 times.

The fact that the heat-resistant fibers are substantially evenly distributed in the matrix resin means that, for example, in a sheet cross section, at least 1 is present in any virtual square having one side 10 times the fiber diameter of the heat-resistant fibers. Having a book of heat resistant fibers is one indicator. The sheet cross section is, for example, 150 to 600
By doubling the magnification and observing under a microscope, the distribution of the heat resistant fibers in the matrix resin can be easily observed.

The fiber-reinforced thermoplastic resin sheet of the present invention comprises
As mentioned above, the structure of heat resistant fiber is at least 1.0 kg /
An excellent machine that was previously unattainable or difficult to achieve due to its entanglement strength of mm ^{2 and} the fact that this heat-resistant fiber is substantially evenly distributed in the matrix resin and has virtually no voids. It was possible to realize characteristics, particularly strength.

In order to stably produce a fiber-reinforced thermoplastic resin sheet having particularly excellent mechanical properties, at least two layers of the first layer (a) containing the continuous fiber knitted fabric are used for the fiber structure of the heat-resistant fiber. It is important to have a laminated structure in which at least one layer of the second layer (b) containing a substance is sandwiched. By taking such a laminated structure, the continuous fiber woven or knitted fabric can easily prevent “waviness” which is likely to occur during molding, and it is held in the surface layer portion of the sheet in an aligned and tensioned state. Stable development of excellent mechanical properties.

The fiber structure of the heat resistant fiber used in the present invention has the role of preventing the "waviness" of the continuous carbon fiber woven or knitted fabric and enhancing the formability of the reinforced thermoplastic resin sheet. In order to remarkably exhibit such a function, it is preferable that the fibrous structure made of the heat-resistant fiber is bulky and has repulsion property, and a non-woven fabric formed from crimped fibers and having a large interfiber entanglement is more preferable.

In addition, the low density of heat-resistant fibers in the fiber structure, that is, the bulkiness thereof, is an important factor for obtaining a high physical property sheet having a reduced sheet density and a reduced weight, and a molded article made of the sheet. is there.

According to the research conducted by the present inventors, a first layer containing a continuous fiber knitted woven fabric of carbon fibers, a second layer containing a needling non-woven fabric made of short crispy meta-aramid fibers, and a continuous carbon fiber are provided. A sheet in which other first layers including a fiber knitted fabric are laminated in this order, and these are integrated with a matrix resin has a thermoforming (shaping) property of the sheet and mechanical properties and surface properties of the obtained molded product. It has been found to be particularly suitable because it is remarkably excellent.

Further, according to the research conducted by the present inventors, a substantially uniform distribution of a fiber structure made of heat resistant fibers in a matrix resin and a structure index defined below is 1 to 10 g.
It has been revealed that the content within / min is a very important factor because the obtained sheet does not have voids exceeding the fiber diameter of the heat resistant fiber. When there is no fiber in an arbitrary virtual square having one side of 10 times the fiber diameter, such as a fiber structure such as a glass mat, or when the structural index is 10 g / min or more, during molding and pressing. There are many various voids in the surface or on the surface of the formed sheet, which are considered to be caused by the vacuum voids due to the uneven flow of the matrix resin or the contraction of the matrix resin.

On the other hand, in the case of a fibrous structure such as a needling non-woven fabric, the uniform distribution of the fibers prevents the uneven flow of the matrix resin, and even if the fiber amount of the same fibrous structure is the same. Since the wetting length increases, the structural index, which is considered to be one showing the impregnating property of the matrix resin, is also in the optimum range of 1 to 10 g / min.

Since the fibrous structure is uniformly dispersed in the vacuum voids caused by the resin shrinkage during the cooling of the sheet as well as the improvement of the impregnating property of the matrix resin at the time of molding and pressing, voids are less likely to occur.

In the sheet of the present invention, the total of the fiber structure composed of the continuous fiber knitted fabric of carbon fibers and the heat resistant fiber occupies 30 to 70% by volume of the sheet, and V _f = 30 to 70.
% Is preferable.

According to the invention, in the sheet of the invention, the heat-resistant fibers are meltable and have an oxygen index (LOI).
Is at least 28%, and a polymer having no affinity with the thermoplastic resin of the matrix resin in the molten state, for example, the meta-aramid fiber as described above, has flame retardancy (flame resistance). It has become clear that an excellent fiber-reinforced thermoplastic resin sheet can be provided.

Therefore, according to the present invention, secondly, (a)
At least one first layer formed by impregnating a continuous fiber woven or knitted fabric of heat-resistant reinforcing fibers with a matrix resin made of a thermoplastic resin and (b) a matrix made of a thermoplastic resin in a fiber structure made of heat-resistant fibers. A flame-retardant sheet comprising at least one second layer impregnated with a resin, wherein the first layer (a) and the second layer (b) are laminated in a non-separable manner. The second layer (b) has the heat-resistant fibers substantially uniformly distributed in the matrix resin in the sheet cross section of the sheet, and has a void substantially exceeding the fiber diameter of the heat-resistant fibers. And the fiber structure used in the second layer (b) exhibits a entanglement strength of at least 1.0 kg / mm ² in any two orthogonal directions and a heat resistance of the fiber structure. Fiber is meltable and has an oxygen index (L I) a is at least 28%, and the flame-retardant sheet is provided which is characterized by comprising a polymer having no affinity with the thermoplastic resin of the matrix resin in the molten state.

The greatest feature of the flame-retardant sheet of the present invention is that
(A) A polymer which is incompatible with the matrix resin in the melted state, typically does not show compatibility, and (b) has an oxygen index of 28% or more, preferably 3 in the combustion test.
It is to use a fiber structure composed of heat-meltable heat-resistant organic fibers that simultaneously satisfy the two conditions of 0 (%) or more.

As the heat-resistant reinforcing fiber of the fiber structure constituting the second layer (b), when a material which is essentially non-meltable, such as glass fiber, carbon fiber, para-aramid fiber, etc., is used, a fiber-reinforced resin is used. When the matrix resin that constitutes the sheet melts during combustion, it suppresses the drip behavior that promotes flame retardancy of the matrix resin and suppresses the atmosphere of the matrix resin, similar to the effect of the carbon fiber reinforcing material incorporated for the purpose of reinforcement. Since the fiber structure of the heat-resistant fiber also has the effect of increasing the contact area with the medium oxygen, the flame resistance of the resulting fiber-reinforced resin sheet tends to decrease.

Further, even when a polymer which has a sufficiently high oxygen index in the fiber structure constituting the fiber reinforced resin sheet and is in a molten state during combustion is used, it has an affinity with the matrix resin melted upon combustion ( In particular, when they are compatible with each other, the flame retardant effect due to the fiber structure having a high oxygen index is not exhibited. Further, even when a material having a low oxygen index is used as the fiber structure, the flame-retardant effect is not exerted, and the combustion resistance of the fiber-reinforced resin sheet cannot be improved.

Therefore, the fiber structure used to form the second layer of the flame-retardant sheet of the present invention has an oxygen index (LOI) that has no affinity (particularly compatibility) with the matrix resin when melted. A sheet-shaped material (for example, a non-woven fabric, a mat, a woven fabric, or the like) made of 28 (%) or more, particularly 30 (%) or more, of the heat-fusible organic fiber is preferable.

The term "oxygen index (LOI)" used herein means
It is a value measured by conducting a combustion test by the method described in JIS-K-7201. Examples of suitable heat-meltable organic fibers having an oxygen index of 28% or more include fibers such as meta-aramid fibers, polyetherimide fibers, polyphenylene sulfide fibers, liquid crystal polyester fibers, and polyarylate fibers. Of these, meta-aramid fiber is particularly preferable. These fibers may optionally contain a colorant, a stabilizer, and a flame retardant as long as they do not deviate from the above conditions.

The volume content of the fibrous structure of the heat-resistant fiber as described above in the flame-retardant sheet of the present invention is suitably 10 to 20% by volume, and a flame-retardant effect can be obtained if it is more or less than this. It tends to decrease. The thickness of the fiber structure is 1
It is preferably about 50 to 400 μm per layer.

As the thermoplastic resin of the matrix resin in the flame-retardant sheet of the present invention, the same resins as those described above can be used. Further, as the matrix resin, it is also possible to use a flame-retardant grade matrix resin to which a flame-retardant is added to the extent that mechanical properties, electrical characteristics, etc. are not significantly impaired. By improving the flame resistance of the constituent matrix resin itself, the sheet of the present invention also exhibits higher flame resistance.

As described above, it is completely unexpected that the flame resistance of the entire fiber reinforced resin sheet is greatly improved by interposing the fiber structure made of a specific organic heat resistant fiber inside. For the first time, it is possible to improve the flame resistance even with a fiber reinforced resin sheet having a high fiber volume content (V _f ) which is considered to be difficult to make flame retardant (for example, a sheet with V _f = 50 to 70%). The industrial significance of the present invention is great.

It should be understood that the description of the parts of the flame-retardant sheet of the present invention that are not particularly described is the same as the above description.

According to the present invention, the fiber-reinforced thermoplastic resin sheet (including the flame-retardant sheet) of the present invention is at least one continuous fiber knitted woven fabric of carbon fibers, and at least one in a direction orthogonal to each other. The temperature at which the thermoplastic resin softens in the presence of the thermoplastic resin in the state of being superposed with at least one fiber structure made of a heat resistant fiber having a entanglement strength of 1.0 kg / mm ^2. It can be advantageously manufactured by a method characterized by heating and pressurizing at the above temperature to form an integral sheet.

The thermoplastic resin used in the heat and pressure molding is used, for example, in the form of powder, woven fabric, film or sheet, and particularly preferably in the form of film or sheet.

The heat and pressure molding is performed in the form of heat selected from the group consisting of a sheet, a film, a knitted fabric and a powder between a continuous fiber knitted fabric of carbon fibers and a fiber structure composed of heat resistant fibers. It is preferable to carry out the reaction in the presence of a plastic resin.

Further, the overall laminated state at the time of heat and pressure molding is, for example, at least two continuous fiber knitted fabrics of carbon fiber and at least one fiber structure made of heat resistant fiber, It is preferable to superimpose at least one of the fibrous structures between any two of the knitted fabrics, and then to allow a thermoplastic resin to exist between these ones. desirable.

More specifically, for example, when a film, sheet or the like is used as the thermoplastic resin, the thermoplastic resin film / continuous fiber knitted fabric of carbon fiber / thermoplastic resin film / fiber structure of heat resistant fiber / It is preferable that the thermoplastic resin film / continuous fiber knitted fabric of carbon fibers / thermoplastic resin film are superposed in this order.

In the heat and pressure molding, the temperature for impregnating the continuous fiber knitted woven fabric and the fiber structure with the thermoplastic resin and integrating them is not less than the temperature at which the matrix resin (thermoplastic resin) used is softened and melted. Generally, Tg + 50 ° C, though it depends on the polymer of the resin.
From the above temperature, the temperature range of thermal decomposition temperature -20 ° C is preferable. The pressing pressure for molding is preferably 10 kg / cm ² G or more. It is not always necessary to perform the heating and pressurizing under vacuum, but when vacuum is used, there is an advantage that bubbles are less likely to remain.

In the method of the present invention, the fiber structure made of heat resistant fibers has a structure index of 1 to 10 g / mi as described above.
Those showing n are advantageously used. The use of the fiber structure having such a structural index makes the impregnation and integration of the resin as described above extremely smooth and facilitates the production of the sheet of the present invention.

The thus obtained fiber-reinforced thermoplastic resin sheet of the present invention has a thickness of, for example, at least 0.6 μm, preferably 0.1 to 2 mm.

According to the above-mentioned method of the present invention, the continuous fiber knitted fabric and the fibrous structure are superposed so that the material and / or the constitution are plane-symmetric in the superposing direction, and the heating and pressurizing is performed by the flat plate press. The sheet of the present invention can be obtained as a flat sheet.

Further, the continuous fiber knitted fabric and the fiber structure are superposed on each other so that the material and / or the constitution are not plane-symmetric in the superposing direction, and the heat and pressure molding is carried out by a flat plate press. The sheet of the invention can also be obtained as a curved sheet that is spontaneously curved.

In the above-mentioned two embodiments of the method of the present invention, in the method for obtaining the sheet of the present invention as a flat sheet, the continuous fiber knitted fabric and the heat resistant fiber structure are superposed on each other before heat and pressure forming. The material and / or the structure should be plane-symmetric in the mating direction. For example, in a laminated body in which one fibrous structure is sandwiched between two identical continuous fiber knitted fabrics, the fibrous structure is vertically symmetrical (plane symmetry) in the stacking direction, and the other It can be seen that when two different continuous fiber knitted fabrics of different materials are used in this laminated body, they are vertically asymmetrical (not plane symmetrical) with the fiber structure as the center plane.

Another example not having plane symmetry is two continuous fiber knitted fabrics in the above-mentioned laminate, for example, one is a nonwoven fabric and the other one is a knitted fabric. This is the case of using a fiber structure that is composed of, but has a different structure.

Generally, the greater the degree of asymmetry (in other words, the greater the anisotropy in the cross-sectional direction), for example, the combination of different materials and different forms, the greater the spontaneous bending effect by the flat plate press described later, the greater the effect. preferable.

In the case of manufacturing a curved sheet, when the continuous fiber woven fabric of carbon fibers has the same vertical and horizontal performances (for example, plain weave), the arrangement direction of the carbon fibers is approximately ± 45 ° with respect to the longitudinal direction of the curved sheet. The bias direction is preferable. On the other hand, when the continuous fiber knitted woven fabric of carbon fibers has different vertical and horizontal performances (for example, satin weave), the arrangement direction of carbon fibers is almost zero.
It is preferable that the angle is 90 °.

Further, as the heat-resistant fiber of the fiber structure for producing the curved sheet, meta-aramid fiber or glass fiber is preferable.

When a curved sheet is manufactured, when a laminate not having plane symmetry as described above is heated and pressed, the obtained sheet naturally bends so that the upper layer portion is on the outer side. The radius of curvature can be appropriately adjusted by selecting the combination of laminated fiber layers, the type of resin, the heating and pressurizing conditions, and the like.

The curved sheet thus obtained can be applied to various uses by utilizing its form, and is particularly useful as a material for forming a cylinder.

That is, a cylinder can be easily formed by stacking both end portions of the curved sheet and performing bonding by an adhesive, mechanical bonding or heat fusion. Since the curved sheet according to the method of the present invention uses a thermoplastic resin, one feature is that it can be joined by heat fusion when forming a cylinder. Further, if a sheet made of the same material as the fiber-reinforced thermoplastic resin curved sheet is used as a contact plate from the inside of the cylinder for the joint portion and the joint is performed through this, a joint portion without steps can be formed on the surface of the cylinder.

Since such a curved sheet made into a cylinder as it is is a cylinder made of a relatively thin sheet, it does not have high mechanical strength by itself, but large and small sheet cylinders having different diameters are prepared. By concentrically installing a cylinder with a slightly smaller diameter in a large diameter cylinder and injecting a light-weight foaming resin into the gap between both cylinders for molding, the thickness of the sandwich structure with a light weight and high rigidity A cylinder can be obtained. The strength and composition of the cylinder can be met by designing the performance and thickness of the thin curved sheet or the thickness of the foaming resin according to the required values. For example, in the case of a fiber-reinforced thermoplastic resin cylinder having a sandwich structure with a diameter of 200 mm and a total wall thickness of about 6 mm shown in Example 8 described later, the cylinder density is 0.45 to 0.6 (g / cm ³ ). Therefore, the compressive strength in the diameter direction is about 100 to 200 kg / mm ² .

Further, in order to obtain a cylinder having a sandwich structure with high roundness by this method, a thin-walled sheet cylinder that is curved in each of the molds of the inner cylinder and the outer cylinder having the accuracy corresponding to the required accuracy is formed in each mold. And the mold was heated to a temperature equal to or higher than the second-order transition point (Tg) of the thermoplastic matrix resin constituting the thin sheet cylinder, preferably Tg + 10 ° C. to Tg + 50 ° C. After that, a method of injecting a foaming resin or the like between the large-diameter and small-diameter curved thin-walled sheet cylinders is preferable. Comparing the circularity of the molded cylinder when the expandable resin is injected at room temperature and when the expandable resin is injected after heating above the thermoplastic resin Tg forming the cylinder of the curved thin sheet, the injection method after heating is compared. The circularity is remarkably improved.

Further, in the case of a combination in which the Tg of the thermoplastic resin forming the cylinder of the curved thin sheet is lower than the temperature at which the heat-resistant and foaming performance of the injectable foaming resin is lower, first, the cylinder of the above-mentioned sheet is in the mold. By injecting the foaming resin at room temperature and then injecting the foaming resin into the frame, the mold including the molding cylinder is kept in an atmosphere having a temperature of Tg or higher of the thermoplastic resin.
The roundness of the molded cylinder can be improved. In order to control the workability of the foamable resin and the performance such as the density after molding, the possibility of such room temperature injection is extremely useful in practical use. Further, by heating these before and after injecting the foamable resin, it becomes possible to reasonably and stably develop the foaming power of the foamable resin.

In forming a sandwich structure cylinder,
It is preferable to join both ends of the curved sheet with a thermoplastic adhesive that exhibits adhesiveness at a relatively low temperature to form a cylindrical shape. In the process of molding the sandwich structure cylinder, the mold fitted with the thin sheet cylinder is heated and cooled, but the molded product and the mold (generally a metal frame is generally used) are different materials and have different thermal expansion coefficients. Therefore, the binding force of the joint fixing part is reduced until it can move smoothly in proportion to the thermal expansion difference of the cylindrical sheet with respect to the mold in a temperature state increased by the heating of the thin curved sheet and the mold and the heat generated by the foaming resin. It is necessary to. As a result of various studies conducted by the present inventors, it has been found that joining with a thermoplastic adhesive is most preferable in this sense. On the other hand, when joining by thermosetting adhesive or fusion joining of sheets, local bending etc. often occur in the circumferential direction of the cylinder, and as the diameter of the forming cylinder increases, The higher the temperature, the higher the frequency.

The examples in which the curved fiber-reinforced thermoplastic resin sheet according to the present invention is used as the outer shell and the inner shell of the sandwich structure cylinder have been described above, but the use of the sheet is not limited to this. It is naturally possible to use the curved sheet only for the outer shell or the inner shell of the cylinder, to use the curved sheet itself as a cover, or to use it as a molding material other than the cylindrical shape.

The curved sheet according to the present invention is also very useful as a cylindrical molding material other than the sandwich structure. In other words, in addition to strength and rigidity, cylindrical molded products are often required to have mechanical characteristics such as vibration characteristics and fatigue characteristics, and a relatively small cylindrical thickness, so that a cylinder having a solid structure other than the sandwich structure is required. In many cases, the curved sheet according to the present invention is also very useful when molding a solid structure cylinder of such a fiber reinforced thermoplastic resin.

That is, in this curved sheet, (i) the constituent base material is curved along the cylindrical system of the molded product, so that it is easy to superimpose them, and no undue internal stress remains in the molded cylinder. ii) Since it is a thermoplastic resin thin sheet that is completely impregnated with a thermoplastic resin, it has the advantage that it is only necessary to stack thin sheets to form a thick cylinder in order to form a thick cylinder. Among the molds for molding, the Tg of the thermoplastic resin forming the curved sheet is formed by using a material having a high coefficient of thermal expansion for the inner cylinder and a mold designed to have a difference in thermal expansion between the inner cylinder and the outer cylinder. A high performance solid structure fiber reinforced thermoplastic resin cylinder having a thickness of 3 to 5 mm can be easily molded by a TEM (Thermal Expansion Mold) molding method in which heating and pressing are performed at the above temperature. For example, an example of the TEM method is shown in Example 9 described later. According to this method, the density is higher than that of the sandwich structure cylinder, but the roundness is also high and the wall thickness is as thin as about 3 mm, but it is high. A rigid composite cylinder is formed.

[0091]

INDUSTRIAL APPLICABILITY As described above, the fiber-reinforced thermoplastic resin sheet of the present invention has good mechanical properties because the reinforcing effect of the continuous fiber knitted fabric of carbon fibers is sufficiently exerted. Moreover,
It is also excellent in moldability, and can be molded (shaped) into various shapes by putting it in a mold and thermocompressing it like a conventional stampable sheet. For example, by such molding, various molded products used as vehicle parts and structural materials, various housings for home electric appliances, parabolic antennas, bags, interior materials, protective materials, sports equipment, furniture, musical instruments, household goods, etc. Is possible.

As described above, the product obtained by thermopressing (forming) the sheet of the present invention into a desired shape is a molded product having good mechanical properties.

Further, the flame-retardant composite material sheet of the present invention has excellent flame retardancy (flame resistance) and can be used in various fields requiring flame retardancy.

Further, the curved sheet of the present invention can be prepared by joining them into a thin-walled cylinder, and a sandwich structure cylindrical curved sheet in which a core material is injected into the gap as large and small outer and inner shells. It is also possible to form a thick-walled solid structure cylinder or the like by superposing the above. These cylinders are used as furniture parts such as chair stands and table feet, as musical instrument parts such as drum shells, tambourine frames, interior products such as high-grade flower pots, corrosion resistant pipes, and other industrial applications. Widely used effectively. Further, the curved sheet of the present invention has a wide range of uses such as a molding base material other than a cylinder, and as a cover.

In the present invention, various physical properties are defined and measured as follows.

Entangling Strength of Fiber Structure The entanglement strength of the fiber structure indicates a value measured by the following method.

That is, a fiber structure made of heat-resistant fibers was cut into a width of 10 mm and a length of 100 mm, and tabs were attached at both ends with heat-resistant tape or the like (holding interval 100 mm) around a molding temperature (250 to 300 ° C.). It is defined as the breaking stress when a tensile test (pulling speed: 11 mm / min) is performed under the conditions. Then, the entanglement strength is calculated from the average value of the five measurements.

Bulkiness of Fiber Structure The bulkiness of the fiber structure is defined by the following formula.

[0099]

[Equation 1] Bulk height = {thickness / (weight per unit area / fiber true density)} × 10 ³ Here, the thickness is 10 g / cm ^{2 under a} load of 20 g / cm ² according to JIS L1085 (nonwoven fabric interlining test method). It means the average value of the thickness at 5 places measured with a thickness measuring machine after a second.

Structural Index of Fiber Structure Here, the “structural index” is a parameter that quantitatively indicates the resistance value of the matrix resin flowing through the interstices of the fiber structure. The values measured by the method are shown.

A punching plate having an opening ratio of 50 (%) or more was installed on the bottom of a cylinder having an inner diameter of 50 m / m to support the fiber structure, and the fiber structure to be measured was placed on the punching plate.
Cut according to the inner diameter of the cylinder and stack in the range of 1 to 5 sheets,
The contact part with the inner wall of the cylinder is sealed and set. 100 ml of a liquid (for example, glycerin) having a liquid viscosity of 30 cps is injected into the cylinder in which the fibrous structure is set, and the weight of the liquid passing per unit time is defined as the structural index (g / min). The measurement is performed in an atmosphere of 16 to 17 ° C., and the liquid specific gravity is unified to ρ = 1.26. In addition, the fiber volume ratio in the thickness direction of the fiber structure that is the object to be measured, that is, {[weight per unit area / fiber true specific gravity (true density)] × 10 ⁻³ / fiber structure thickness} is around 0.1. It is measured under the following conditions.

[0102]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

[0103]

Example 1 and Comparative Example 1 Carbon fiber (continuous fiber) plain weave cloth (manufactured by Toray Industries, Inc., C / O6343, basis weight 198 g)
/ M ² ) 2 sheets, a span produced by carding crimped fibers of poly-metaphenylene isophthalamide fiber (registered trademark "Conex" manufactured by Teijin Ltd.) which is a meta-aramid fiber and subjected to a water jet needle ^Two laces (with a basis weight of 60 g / m ² , a bulking height of 9, and a vertical and horizontal interlacing strength of 1.5 kg / mm ² or more, an oxygen index of 30%, a structural index of 3 g / min), and a polycarbonate film ( Five sheets of polycarbonate resin “Panlite” (registered trademark) L-1250 manufactured by Teijin Chemicals Ltd., oxygen index 24.9%) were prepared.

These were laminated in the order of polycarbonate film / carbon fiber plain weave cloth / polycarbonate film / meta type aramid fiber spunlace / polycarbonate film / meta type aramid fiber spunlace / polycarbonate film / carbon fiber plain weave cloth / polycarbonate film. ..

This laminated body was opened at 300 ° C. by an open mold.
Was hot-pressed for 30 minutes to obtain a fiber-reinforced polycarbonate sheet having a thickness of 0.75 mm.

At this time, the moldability was good, and almost no outflow burr or disorder of the carbon fiber cloth was observed. The physical properties of this sheet, the entire V _f satisfies 50%, specific gravity 1.36, bending strength 60 kg / mm ^2, a flexural modulus of 4000 kg / mm ^2, was excellent sheet lightweight and mechanical properties.

For comparison (Comparative Example 1), under the same molding conditions, without using the spunlace of the meta-aramid fiber, two carbon fiber plain weave cloths and a polycarbonate film having a thickness of 0.75 mm were molded. The physical properties of the fiber reinforced polycarbonate sheet are as follows: V _f 35%, specific gravity 1.36
However, the bending strength was 50 kg / mm ² and the bending elastic modulus was 2000 kg / mm ² .

From this fact, when the spunlace of the meta-aramid fiber is sandwiched between the carbon fiber plain weave cloths and molded, the reinforcing effect of the reinforcing fibers works effectively even though the sheet specific gravity is the same, and particularly in terms of elastic modulus. It is clear that the physical properties of the sheet are improved.

[0109]

[Examples 2 and Comparative Examples 2 and 3] Two sheets of the same carbon fiber plain weave cloth as in Example 1, two sheets of each core material and 5 sheets of nylon 6 film shown in Table 1 below were used in the same manner as the laminate of Example 1. A laminated body was prepared so as to have a laminated constitution. A fiber-reinforced nylon 6 sheet was obtained by open die molding under molding conditions in which this laminate was pressed at 290 ° C. for 30 minutes.

[0110]

[Table 1]

The "conex" used as the core material
Spunlace (I) has a higher number of water jet needles to increase the entanglement strength, and "Conex" spunlace (II) changes the direction of fiber arrangement and lowers the number of water jet needles. The entanglement strength has been lowered. The glass fiber surfacing mat is SM3 manufactured by Asahi Fiber Glass Co., Ltd.
603 (Basis weight: 60 g / m ² ) was used.

The mechanical properties of each fiber-reinforced resin sheet thus obtained were largely dependent on the carbon fiber plain weave cloth, but in other sheet properties and moldability, the heat resistant fiber sandwiched between the carbon fiber plain weave cloths was used. Due to the difference in the confounding strength of ("Conex"), differences were observed in various points as shown in Table 2 below.

[0113]

[Table 2]

The outflow burr amount shown in Table 2 represents the ratio of the burr weight protruding from the carbon fiber plain weave cloth divided by the weight of the entire formed sheet. The cross disturbance rate is
The ratio of the area of the disordered portion of the carbon fiber plain weave cloth divided by the area of the entire cloth is shown.

The test piece a (Example 2) according to the present invention is a good sheet with small outflow burr amount and cross disturbance, but the test piece b (Comparative Example 2) has a part of the core material during molding. As it flows out and becomes thinner, it became difficult to control the thickness. In addition, variations in physical properties occurred due to variations in the outflow site, and further disturbance of the end portion of the surface layer cloth was observed due to the outflow of the core material. Since the test piece c (Comparative Example 3) had a small entanglement strength in the horizontal direction, the surface cloth was disturbed and the sheet thickness was significantly varied.

[0116]

Example 3, Comparative Examples 4 to 6 Carbon fiber (continuous fiber) plain weave cloth (manufactured by Toray Industries, Inc., C / O6343, basis weight 198 g)
/ M ² ) 2 sheets and a polycarbonate film (polycarbonate resin “Panlite” (registered trademark) L-1250 manufactured by Teijin Kasei Co., Ltd.) 3 sheets, a laminate of 2 sheets
A fiber-reinforced resin sheet (test piece 1, comparative example 4) having a total fiber volume content (V _f ) of about 50% was formed by pressing at 80 to 310 ° C. under the condition of ^{20 to} 40 kg / cm ² . The above-mentioned laminate is obtained by laminating a carbon fiber plain weave cloth (hereinafter sometimes referred to as C) and a polycarbonate film (hereinafter sometimes referred to as P) in the order of P / C / P / C / P.

Further, two pieces of the same kind of carbon fiber plain weave cloth, five pieces of polycarbonate film and the same glass fiber surfacing mat as Comparative Example 3 as a flame retardant core material (SM3603 manufactured by Asahi Fiber Glass Co., Ltd., basis weight 60 g / m 2)
² , sometimes referred to as G hereinafter) and a laminate of 2 sheets (P / C
/ P / G / P / G / P / C / P) was pressed under the same conditions as above to obtain a fiber reinforced resin sheet (test piece 2, comparative example 5) having V _f of about the same level.

Further, the same polymetaphenylene isophthalamide fiber "Conex" (registered trademark) as in Example 1 was used.
A laminate (P / C / P / M / P) was prepared in the same manner as above using two needle punched nonwoven fabrics (oxygen index of about 30) (hereinafter sometimes referred to as M) having a basis weight of about 60 g / m ²
/ M / P / C / P) was prepared and pressed under the same conditions as above to obtain a flame-retardant fiber-reinforced resin sheet (Test piece 3, Example 3) having V _f of about 60%.

The following Table 3 shows the results of evaluating the polycarbonate film itself (Comparative Example 6) used as the material of the matrix resin and the above-mentioned test pieces 1 to 3 by conducting a combustion resistance test.

[0120]

[Table 3]

As is clear from Table 3, the matrix resin (polycarbonate film) constituting the sheet itself has a flame resistance of V-2 grade, whereas the test pieces 1 and 2 are affected by the reinforcing fibers. The flame resistance of the sheet is rather reduced to HB grade. On the other hand, the test piece 3 according to the present invention surprisingly exhibits combustion resistance (V-1 grade) superior to that of the matrix resin constituting the composition.

For comparison, a reinforcing material made of the same carbon fiber plain weave cloth as in the test piece 3 shown in Example 3 and a flame-retardant core material made of "Conex" non-woven fabric, and nylon used as a matrix resin were used. 6 film (manufactured by Toray Synthetic Film Co., Ltd., "Rayfan" (registered trademark) T-1401)
In the same manner as in Example 3, a fiber-reinforced resin sheet (test piece 4) formed by laminating the core material and the core material with the reinforcing material sandwiched therebetween was evaluated. As a result, the test piece 3 was "V-1", while the test piece 4 was "HB".

These results show that when the matrix resin forming the sheet and the molten flame-retardant core material are compatible with each other, the core material does not exert the effect of improving the combustion resistance of the fiber-reinforced resin sheet. ing.

[0124]

Example 4, Comparative Examples 7 and 8 Example 3 and Comparative Example 4,
In various fiber reinforced resin sheets (test piece 1 to test piece 3) shown in FIG. 5, a flame retardant polycarbonate film ("Panlite" LN manufactured by Teijin Chemicals Ltd.) treated with a flame retardant as a matrix resin (polycarbonate) constituting the fiber sheet.
Various fiber-reinforced resin sheets were obtained in the same manner as above, except that the film formed from -1250) was used. The flame resistance evaluation results of each sheet are shown in Table 4 below.

The laminated sheet structure of each test piece is the test piece 5
Is the above-mentioned test piece 1, the test piece 6 is the test piece 2, and the test piece 7 is
Correspond to the test pieces 3, respectively.

[0126]

[Table 4]

The results of the test pieces 5 and 6 (Comparative Examples 7 and 8) in Table 4 show that it is difficult to improve the flame resistance of the fiber reinforced sheet only by making the matrix resin constituting the flame retardant. .. Further, from the results of Table 4, the combustion resistance of the matrix resin constituting the sheet also affects the combustion resistance of the sheet, and the test piece 7 according to the present invention shows remarkably excellent flame resistance (V-0 grade). It is clear.

[0128]

Example 5 and Comparative Example 9 The same carbon fiber plain weave cloth (C), polycarbonate film (P) and poly-metaphenylene isophthalamide fiber "conex" which is a meta-aramid fiber used in Example 3 (non-woven fabric) Using the burned core material, M), the following three types of laminates were manufactured.

P / M / P / C / P / M / P (laminate 1), P / C / P / M / P / C / P (laminate 2), and each of the above two laminates The laminate 1 is pressed under the same conditions as in Example 3 to obtain the test piece 8 and the laminate 2
A test piece 9 was obtained from

Table 5 shows the evaluation results of the flammability resistance of the test pieces 8 and 9. The volume content of the fiber-reinforced resin sheet occupied by one flame-retardant core material is about 10%.

[0131]

[Table 5]

From Table 5, it is clear that it is essential that the flame-retardant core material has a structure in which the flame-retardant core material is sandwiched between the reinforcing fiber materials.

[0133]

Example 6 This example is an example of manufacturing a curved sheet made of a fiber reinforced thermoplastic resin.

CF cloth, GF cloth, "Conex NWF" and the like are laminated as in the following (i) to (v),
A nylon 6 resin film (hereinafter sometimes referred to as N) is sandwiched between the surface, the bottom surface and each layer, and heated and pressed under the conditions of a flat plate press at a temperature of 280 ° C. and a pressure of 30 kg / cm ^{2 to form} a nylon 6 resin. An integral fiber-reinforced resin sheet as a matrix resin was obtained.

The “CF cloth” here is a carbon fiber plain weave cloth (C / O6343, basis weight 198 g / m ² ) manufactured by Toray Industries, Inc., and the “GF cloth” is glass fiber manufactured by Asahi Fiber Glass Co., Ltd. Plain weave cloth (MS-253E,
A unit weight of 250 g / m ² ) and “Conex NWF” are needle-punched nonwoven fabrics (unit weight of 60 g / m ² ) made of crimped short fibers of polymetaphenylene isophthalamide fiber (registered trademark “Conex”) manufactured by Teijin Limited. Represents. (I) CF cloth / conex NWF (ii) CF cloth / conex NWF (2 layers) (iii) CF cloth / conex NWF (3 layers) (iv) CF cloth / conex NWF / GF cloth (v) GF cloth (2 layers) / Conex NWF
(2 layers)

The sheet after heating and pressing has the following thickness,
Further, it was a curved sheet having the following radius curvature, which was curved with the layer described on the right side inside. (I) Sheet thickness 0.40 mm Radius curvature 150
mm (ii) Sheet thickness 0.50mm Radius curvature 80
mm (iii) Sheet thickness 0.60mm Radius curvature 50
mm (iv) Sheet thickness 0.55mm Radius curvature 120
mm (v) Sheet thickness 0.67mm Radius curvature 220
mm

[0137]

[Embodiment 7] This embodiment is an example of producing a cylinder having a sandwich structure using the curved sheet manufactured by the present invention.

Using the curved sheet obtained in Example 6, the length was 200 mm, the outer diameter was 200 mmφ, and the inner thickness was 6 mm.
The sandwich cylinder of was created. In this method, the respective sheets were arranged along the inner peripheral surface of the outer cylindrical mold and the inner peripheral surface of the outer cylindrical mold, and the ends of the sheets were joined together with a thermoplastic resin adhesive to form a cylindrical shape. Then, the whole was heated to 80 ° C., and the expandable polyurethane resin was injected between the sheet along the outer mold and the sheet along the inner mold to foam and fill the gap with foam.

The sandwich-structured cylinder thus obtained has a foamed polyurethane density of 0.15 g / cm ³ and a cylindrical density of 0.45 g / cm ³ using the sheet of (iv).
cm ³ , the circularity of the cylinder is ± 0.10 mm, and the density of polyurethane foam is 0.
15 g / cm ³ , a cylinder density of 0.50 g / cm ³ , and a roundness of the cylinder of ± 0.15 mm were all favorable.

[0140]

[Embodiment 8] This embodiment is an example in which a curved sheet manufactured according to the present invention is used to prepare a cylinder having a sandwich structure with good roundness.

Using the curved sheet of (iv) above obtained in Example 6, a length of 400 mm and an outer diameter of 4 were obtained in the same manner as in Example 7.
A cylinder having a sandwich structure of 00 mmφ and an inner thickness of 7 mm was prepared.

At this time, an experiment was conducted by changing the injection state of the expandable polyurethane resin, and the density of the expanded polyurethane and the circularity of the cylinder were measured. As a result, the one injected at room temperature had a foamed polyurethane density of 0.3 g / cm ³ and a roundness of ±
Although it was 1.0 mm, the one injected by heating to 80 ° C. had a polyurethane foam density of 0.15 g / cm ³ , circularity ±
The roundness is significantly improved to 0.1 mm. Also, after being injected at room temperature and heated to 80 ° C, the density of polyurethane foam is 0.3.
Although it did not change to g / cm ³ , it was found that the circularity was ± 0.3 mm, which was improved compared to the room temperature injection.

[0143]

[Embodiment 9] This embodiment is an example of forming a solid cylinder by molding by the TEM method.

Five curved sheets of the above (iv) obtained in Example 6 were superposed and inserted between a cylindrical outer die and an inner die. In this case, as the inner mold, a heat-expandable thermoplastic resin molded and cut with good circularity was used.

Next, the mold is heated to expand the inner mold, and by the heat and pressure thereof, the laminated curved sheets are strongly pressed against the inner surface of the outer mold, and the respective curved sheets are thermocompression-bonded to be integrated with each other. A solid cylinder having a length of 200 mm, an outer diameter of 200 mmφ and an inner thickness of 3 mm was obtained.

The cylinder thus obtained has a cylinder density of 0.7.
The circularity was 5 g / cm ³ and the roundness was ± 0.15 mm.

[0147]

[Comparative Example 10] Carbon fiber (continuous fiber) plain weave cloth (manufactured by Toray Industries, Inc., C / O6343, basis weight 198 g / m ² ) (C
2 pieces, glass fiber continuous mat (manufactured by Asahi Fiber Glass Co., Ltd., M8625, basis weight 300 g)
/ M ² , entanglement strength 0.2 kg / mm, bulk altitude 11, structure index 17 g / min) (one piece of GF) and polycarbonate film (polycarbonate resin "Panlite" (registered trademark) L manufactured by Teijin Chemicals Ltd.) Six films from -1250) (abbreviated as PC) were prepared.

These are PC / CF / PC / PC / GF
/ PC / PC / CF / PC were laminated in this order.

290 to 290 this laminate with an open mold
Hot press press molding at 300 ° C for 30 minutes, thickness 0.6 ~
0.7 m / m fiber-reinforced polycarbonate sheet (V _f =
50%).

A large number of void defects were found on the surface of this molded sheet, centering on the intersections of the carbon fiber cloths. Further, when the cross section in the sheet thickness direction was observed with a microscope, it was found to be several tens to several hundred times the glass fiber diameter. There were many internal voids to reach. It is easily speculated that these void defects may be a factor that significantly deteriorates the dynamic mechanical properties of the sheet.

[0151]

[Example 10] Two carbon fiber plain weave cloths similar to Comparative Example 10 and five polycarbonate films, and the same meta-aramid fiber as in Example 1 as a fiber structure (Teijin Co., Ltd.).
Spunlace (weight per unit area: 70 g / m ² , 10 times the diameter of meta-aramid fiber) produced by carding crimped fibers (registered trademark "Conex") manufactured by water jet needle There is always at least one fiber in the fiber structure, and a fiber structure in which the fibers are substantially uniformly dispersed (hereinafter abbreviated as CM) is used as PC / CF / PC / C.
M / PC / CM / PC / CF / PC were laminated in this order, and a fiber reinforced polycarbonate sheet was molded under the same molding conditions.

Voids exceeding the diameter of the meta-aramid fiber were not observed at all on the surface of the molded sheet and in the cross-section observation in the thickness direction under a microscope.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B29K 105: 08 B29L 7:00 4F

Claims (22)

[Claims] 1. A matrix comprising a thermoplastic resin in a fiber structure comprising at least one first layer comprising a continuous fiber woven or knitted carbon fiber and a matrix resin comprising a thermoplastic resin and a heat resistant fiber. A fiber reinforced thermoplastic resin sheet comprising at least one second layer impregnated with resin, wherein the first layer and the second layer are laminated in a non-separable and integrated manner. The layer 2 has the heat-resistant fibers substantially uniformly distributed in the matrix resin in the cross section of the sheet, does not substantially contain voids exceeding the fiber diameter of the heat-resistant fibers, and has a second layer. The fiber-reinforced thermoplastic resin sheet, wherein the above-mentioned fiber structure used in the layer has a entanglement strength of at least 1.0 kg / mm ² in any two orthogonal directions. 2. The fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the fiber structure of the heat-resistant fiber is a non-woven fabric or a mat. 3. The heat resistant fiber has a fiber structure of at least 8
The fiber-reinforced thermoplastic resin sheet according to claim 1 or 2, having a bulkiness of. 4. The fiber-reinforced thermoplastic resin sheet according to claim 1, 2 or 3, wherein the heat-resistant fiber is composed of a polymer having a melting point higher than that of the thermoplastic resin serving as the matrix resin. 5. The heat-resistant fiber is selected from meta-aramid fiber, para-aramid fiber, polyarylate fiber, polyacrylonitrile fiber, polybenzimidazole fiber, polyethylene terephthalate fiber, polyethylene-2,6-naphthalate fiber and cellulose fiber. The fiber-reinforced thermoplastic resin sheet according to claim 1, which is an organic heat resistant fiber selected from the group consisting of: 6. The heat resistant fiber comprises a polymer that is meltable, has an oxygen index of at least 28%, and has no affinity with a thermoplastic resin that becomes a matrix resin in a molten state. Item 5. The fiber-reinforced thermoplastic resin sheet according to any one of Items 1 to 4. 7. The fiber-reinforced thermoplastic resin sheet according to claim 6, wherein the heat-resistant fiber is a meta-aramid fiber. 8. The fiber of claim 1, wherein the second layer has at least one refractory fiber in any virtual square having one side 10 times the fiber diameter of the refractory fiber in the sheet cross section. Reinforced thermoplastic resin sheet. 9. The thermoplastic resin as a matrix resin is polyethylene, polypropylene, polyvinyl chloride,
Polyethylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, nylon 6,
The fiber-reinforced thermoplastic resin sheet according to claim 1, which is a resin selected from the group consisting of nylon 66, polyphenylene sulfide, ABS, and a copolymer consisting of two or more kinds of structural units of these polymers. 10. The first layer is present in at least two layers, and the second layer is provided between the first layers.
The fiber-reinforced thermoplastic resin sheet according to any one of 1. 11. A continuous fiber woven or knitted material of carbon fibers and a fiber structure composed of heat resistant fibers have a total of 30 to 70 sheets.
The fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 10, which occupies a volume%. 12. A thermoplastic resin is applied to a fiber structure comprising at least one first layer and a heat-resistant fiber, which is formed by impregnating a continuous fiber woven or knitted fabric of heat-resistant reinforcing fiber with a matrix resin comprising a thermoplastic resin. A fiber-reinforced resin sheet comprising at least one second layer impregnated with a matrix resin, and wherein the first layer and the second layer are laminated in a non-separable manner. The second layer has heat-resistant fibers which are substantially uniformly distributed in the matrix resin in the cross section of the sheet, and does not substantially contain voids exceeding the fiber diameter of the heat-resistant fibers, and the second layer The fibrous structure used in 1. exhibits a entanglement strength of at least 1.0 kg / mm ² in any two orthogonal directions, and the heat resistant fibers of the fibrous structure are meltable and have an oxygen index of at least 28% And a flame-retardant composite material sheet comprising a polymer having no affinity with a thermoplastic resin of a matrix resin in a molten state. 13. The flame-retardant composite material sheet according to claim 12, wherein the heat-resistant fiber is a meta-aramid fiber. 14. The flame-retardant composite material sheet according to claim 12, wherein the matrix resin is a resin containing a flame retardant. 15. The flame-retardant composite material sheet according to claim 12, 13 or 14, wherein the fibrous structure of the second layer occupies 10 to 20% by volume of the entire sheet. 16. At least one continuous fiber woven or knitted carbon fiber and at least 1.0 kg / in two orthogonal directions.
At least one fiber structure made of heat-resistant fibers having a entanglement strength of mm ² is laminated and heated in the presence of a thermoplastic resin at a temperature equal to or higher than the temperature at which the thermoplastic resin softens. A method for producing a fiber-reinforced thermoplastic resin sheet, which comprises pressurizing to form an integrated sheet. 17. The method according to claim 16, wherein the fiber structure made of heat resistant fibers has a structural index of 1 to 10 g / min. 18. A thermoplastic resin in a form selected from the group consisting of a sheet, a film, a woven and knitted material and a powder is present between the continuous fiber woven and knitted material of carbon fibers and the fiber structure made of heat resistant fiber. The manufacturing method according to claim 16. 19. At least two continuous fiber woven or knitted carbon fibers and at least one fibrous structure consisting of heat resistant fibers.
Sheets are laminated so that there is at least one of the fibrous structures between any two of the continuous fiber woven and knitted fabrics, and then heated in the presence of a thermoplastic resin between the layers. The manufacturing method according to claim 16, wherein pressure molding is performed. 20. The continuous fiber woven and knitted fabric and the fiber structure are laminated so that the material and / or the structure are plane-symmetric in the laminating direction, and the heat and pressure molding is carried out by a flat plate press to obtain a flat plate shape. The method according to claim 16, wherein a sheet is obtained. 21. Lamination of a continuous fiber woven and knitted fabric and a fiber structure is carried out so that the material and / or the constitution are not plane-symmetric in the laminating direction, and the heat and pressure molding is carried out by a flat plate press to spontaneously bend. The manufacturing method according to claim 16, wherein a curved sheet is obtained. 22. The method according to claim 21, wherein the heat resistant fiber of the fiber structure is a meta-aramid fiber or a glass fiber.