JP5851714B2 - Fiber reinforced resin molding material - Google Patents

Description

  The present invention relates to a fiber-reinforced resin molding material including reinforcing fibers in which reinforcing fiber bundles are aligned in one direction. In particular, the present invention relates to a fiber-reinforced resin molding material that includes a thermoplastic resin and can be shaped into a complex shape even at room temperature.

  In recent years, reinforcing fiber materials such as carbon fibers, glass fibers, and aramid fibers have been combined with various matrix resins, and the resulting fiber reinforced plastics have been widely used in various fields and applications. When thermoplastic resin is used as a matrix, the composite material has excellent impact resistance, easy prepreg storage management, short molding time, and possible reduction in molding cost. Proposed. In order to classify continuous fiber reinforced thermoplastic resin molding materials by resin impregnation, the resin is once melted and completely impregnated between reinforcing fibers, so-called completely impregnated type and resin not yet used. It can be broadly divided into forms that exist in the molten state.

  Completely impregnated molding materials do not need to be re-impregnated in the molding process because the resin is already impregnated between the fibers, so heat treatment and molding pressure can be performed in a relatively short time. Since a molded product is obtained, it is excellent in high-speed moldability, and is an advantageous material form in order to increase productivity. However, when trying to obtain a molded product having a complicated shape, since it does not have drape, it is difficult to form, and the shape of the molded product tends to be limited to a relatively simple shape. On the other hand, in order to solve such problems, molding materials imparted with drapeability have been developed.

  Patent Document 1 includes a method in which a matrix resin is made into fibers, mixed with reinforcing fibers and then fixed with a binder. In such a method, a resin that has drape properties but cannot be processed into fibers can be used as a matrix resin. In addition, there is a problem in that the type of resin is limited and the cost of the resin increases because it is necessary to fiberize the resin.

  Non-Patent Document 1 includes a method in which a reinforcing fiber aggregate (fiber bundle) to which a thermoplastic resin powder is adhered is heat-treated, and the resin is semi-melted to adhere to the reinforcing fibers. In such a method, although it has a draping property, since the thermoplastic resin is merely semi-melted and adhered to the reinforcing fiber bundle, it cannot completely cover the dropping of the thermoplastic resin powder due to external force, and the resin It is difficult to obtain a molded product having desired mechanical properties due to a change in the mixing ratio of the reinforcing fiber and the reinforcing fiber. In addition, since the thermoplastic resin powder does not restrain the reinforcing fiber bundle, the reinforcing fiber bundle is also easily opened by an external force, which may cause a problem in the handleability of the molding material.

Further, there is a method of solving followability to a complicated shape by making an arbitrary cut (Patent Document 2), but cutting continuous fibers is not preferable from the viewpoint of mechanical properties and substrate manufacturing process.
There is also a method of semi-impregnating a reinforcing fiber sheet with a non-woven thermoplastic resin to form a semi-preg state (Patent Document 3). However, although it is draped rather than a completely impregnated type, it continues in a complicated three-dimensional shape. In the case where the fiber base material is shaped, it is difficult to achieve high-quality shaping because it is stretched in places where the shape surface cannot be covered, but wrinkles are generated in places where the base material remains.

JP-A-6-322159 JP 2010-23449 A Japanese Patent No. 4324649

“VARIABLES AFFECTING THE PHYSICAL PROPERITES OF CONSOLIDATED FLEXIBLE POWDER-COATED TOWPREGS” W. Holty et al. Submitted for publication at the 38th International SAMPE Symposium: May 10-13, 1993

  An object of the present invention is to provide a fiber-reinforced resin molding material that is excellent in formability even at room temperature while being a fiber-reinforced base material including reinforcing fibers in which a plurality of reinforcing fiber bundles are aligned in one direction. is there. A further object of the present invention is to provide a laminate of reinforced fiber thermoplastics and a method for producing fiber reinforced base thermoplastics.

  The present inventors contact a nonwoven fabric made of a thermoplastic resin with at least one of the reinforcing fiber sheets in which the reinforcing fiber bundles are aligned in one direction, and the glass transition temperature (Tg) or higher of the thermoplastic resin is lower than the melting point (Tm). It has been found that the subject can be solved by integrating by pressurizing in the temperature range.

  That is, in the present invention, a nonwoven fabric made of a thermoplastic resin is brought into contact with at least one of the reinforcing fiber sheets in which the reinforcing fiber bundles are aligned in one direction, and the glass transition temperature (Tg) or higher of the thermoplastic resin is lower than the melting point (Tm). It is a fiber reinforced resin molding material characterized by being integrated by pressurizing in a temperature range.

  According to the present invention, it is possible to provide a material for a unidirectional fiber reinforced thermoplastic plastic that can be shaped into a complex shape even at room temperature and has a simple manufacturing method.

Schematic diagram of the fiber-reinforced resin molding material of the present invention Microscopic observation of the nonwoven fabric after peeling the reinforcing fiber sheet from the fiber-reinforced resin molding material obtained in Example 1 Microscopic observation of the nonwoven fabric after peeling the reinforcing fiber sheet from the fiber-reinforced resin molding material obtained in Example 2 Microscopic observation of the nonwoven fabric after peeling the reinforcing fiber sheet from the fiber-reinforced resin molding material obtained in Comparative Example 1

Hereinafter, embodiments of the present invention will be sequentially described.
[Fiber-reinforced resin molding material]
The fiber-reinforced resin molding material of the present invention is a laminate in which a nonwoven fabric made of a thermoplastic resin is integrated with at least one of reinforcing fiber sheets in which reinforcing fiber bundles are aligned in one direction. The nonwoven fabric may be arranged on both sides or one side of the reinforcing fiber sheet according to the fiber reinforced resin molded product to be obtained.
Basis weight of the fiber-reinforced resin molding material, particularly but are not, it is preferable 1 to 1000 g / ^{m 2} in terms of formability for complex shapes, and more preferably from 20 to 500 g / ^{m 2.}

  In the present invention, the integration of the reinforcing fiber sheet and the non-woven fabric is characterized in that no adhesive is used and adhesion is not caused by melting of a thermoplastic resin as a matrix. The fiber-reinforced resin molding material of the present invention can be preferably obtained by pressurizing and bonding a reinforcing fiber sheet and a nonwoven fabric at Tg or more and less than Tm, preferably Tg + 10 degrees or more and Tm-5 degrees or less of a thermoplastic resin. . Adhesion temperature is the temperature of the fiber reinforced resin molding material at the time of bonding. For example, when pressurizing with a heating roller, the temperature should be appropriately controlled by the temperature of the heating roller or the contact time between the roller and the fiber reinforced resin molding material. Can do.

  Although there is no particular limitation on the pressurizing mechanism, the pressurization mechanism can be produced more suitably by taking a continuous pressurization method using a double belt press, a roll or the like rather than a batch pressurization method using a press or the like. For example, when integrating using a calendar roll, the integration is possible by controlling conditions such as the material of the roller, the roller temperature, the pressing force of the roller, and the line speed of the material.

  Since the nonwoven fabric made of a thermoplastic resin is not melt impregnated in the reinforcing fiber sheet, it can be peeled off by an arbitrary load. It is desirable that the test piece obtained by cutting the fiber reinforced resin molding material 100 mm long and 25 mm wide in the fiber longitudinal direction be peeled off with a force of 0.1 to 10 N, more preferably 0.5 to 5 N.

The fiber-reinforced resin molding material of the present invention preferably has an air permeability of 50 to 1000 (ml / min / cm ² ) under a pressure of 98.67 Pa. Thus, by using a material having a certain degree of porosity, it is possible to form a complex shape even at an excellent ordinary temperature, which is an object of the present invention. The air permeability of the fiber-reinforced resin molding material of the present invention is preferably 50 to 500 (ml / min / cm ² ). When the air permeability is less than 50 (ml / min / cm ² ), the formability in obtaining a molded product having a complicated shape is somewhat inferior. If the air permeability exceeds 1000 (ml / min / cm ² ), there may be a slight problem in terms of handling properties as a molding material.

Fiber-reinforced resin molding material of the present invention, in the tensile test in a direction perpendicular to the reinforcing fiber bundle, 0.1～12M shaping force evaluation value defined by the following formula (1) is, at 10% strain ² / it is preferable that the range of s ^2. More preferably, the forming force evaluation value is 0.3 to 6.5 m ² / s ² at a strain of 10%.
X = F / L / w (1)
(X = shaped force evaluation value (m ² / s ² ), F: tensile load (N), L: sample width (m), w: molding material basis weight (g / m ² ))

  The fiber-reinforced resin molding material of the present invention can be used as a precursor of a fiber-reinforced thermoplastic resin composite material. The reinforcing fiber substrate of the present invention can be used by being laminated according to the characteristics and shape of the molded product to be obtained. In this case, the reinforcing fiber bundles may be laminated so that the alignment direction is the same or different. Although there is no limitation in particular as a lamination | stacking method, in the range which does not impair the objective of this invention, it can shape | mold by carrying out a partial melt | fusion or adhesion | attachment processing as needed.

[Reinforced fiber sheet]
The reinforcing fiber sheet in the fiber-reinforced resin molding material of the present invention is obtained by aligning reinforcing fiber bundles in one direction. The reinforcing fiber constituting the reinforcing fiber sheet of the present invention is not particularly limited. For example, inorganic fibers such as glass fiber, carbon fiber, steel fiber (stainless fiber), boron fiber, ceramic fiber, basalt fiber, silicon carbide fiber, And aramid fiber, polyester fiber, nylon fiber and the like. Among these, glass fiber, carbon fiber, and aramid fiber are preferable from the viewpoint of versatility and handleability.

  Of these, carbon fibers are preferred, and any carbon fiber such as polyacrylonitrile (PAN), petroleum / coal pitch, rayon, and lignin can be used. In particular, PAN-based carbon fibers using PAN as a raw material are preferable because they are excellent in productivity and mechanical properties on an industrial scale. PAN-based carbon fibers having an average diameter of 5 to 10 μm can be used. As the PAN-based carbon fiber, a fiber bundle of 1000 to 50000 single fibers can be used. For example, in the case of carbon fiber, a reinforcing fiber bundle of 2 g or more and 500 g or less, preferably 20 g or more and 320 g or less is used per unit area.

A method for aligning the reinforcing fiber bundles in one direction is not particularly limited, but a method of aligning a plurality of fibers preferably using a comb, a guide, a groove roller, or the like can be given. The reinforcing fiber bundle may be opened or overlapped so as to obtain an arbitrary basis weight. The reinforcing fiber sheet may be combined with a thermoplastic resin, and the ratio of the reinforcing fiber sheet and the thermoplastic resin to the total weight of the reinforcing fiber sheet is 99.09 to 80% by weight of the thermoplastic resin 0.01. -20% by weight, more preferably 0.01-7% by weight. The basis weight of the reinforcing fiber sheet is not particularly limited, but in the case of carbon fiber, it is preferably 10 to 800 g / m ² , more preferably 10 to 320 g / m ² in terms of impregnation.

[Nonwoven fabric made of thermoplastic resin]
The matrix of the fiber-reinforced resin molding material of the present invention is a nonwoven fabric made of a thermoplastic resin. The nonwoven fabric preferably has an air permeability of 10-100,000 (ml / min / cm ² ) under a pressure of 98.67 Pa. More preferably, the air permeability is 500 to 50000 (ml / min / cm ² ). By using a porous material having such air permeability as a matrix, it is a fiber reinforced resin molding material that can be shaped into a complex shape at room temperature.

  The method for obtaining the nonwoven fabric made of the thermoplastic resin constituting the fiber reinforced resin molding material of the present invention is not particularly limited, but is a dry method, a wet method, a spunbond method, a spunlace method, a melt blow method, an airlaid method, a chemical method. Examples include a bond method, a thermal bond method, a needle punch method, a hydroentanglement method, an electrospinning method, a flash spinning method, a tow opening method, and the like, and are not particularly limited as long as they have the following characteristics.

Although the fabric weight of a nonwoven fabric is not specifically limited, It is preferable that it is 10-150 g / m < ² > from the point of the fiber content rate of a molding, and handling. The basis weight ratio of the reinforcing fiber sheet to the nonwoven fabric is not particularly limited. For example, when the reinforcing fiber is carbon fiber, the basis weight is preferably 10 to 1000.

  The tensile breaking elongation of the nonwoven fabric is preferably 1 to 200% in terms of followability to complex shapes. More preferably, the tensile strength of the 3 to 100% nonwoven fabric is preferably 50 N / mm or less in the range of up to 10% strain in terms of shaping and handling. Although the average fiber diameter of the fiber which comprises a nonwoven fabric does not have limitation in particular, Preferably it is 0.001-300 micrometers, More preferably, it is 1-100 micrometers. The average fiber length of the fibers constituting the nonwoven fabric is not particularly limited, but is preferably 10 to 1000 mm, more preferably 30 to 500 mm, or a continuous length. The thermoplastic resin constituting the nonwoven fabric is not particularly limited, but is vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyvinyl alcohol resin, polystyrene resin, acrylonitrile-styrene resin (AS resin), acrylonitrile-butadiene-styrene resin. (ABS resin), acrylic resin, methacrylic resin, polystyrene resin, polypropylene resin, polyamide 6 resin, polyamide 11 resin, polyamide 12 resin, polyamide 46 resin, polyamide 66 resin, polyamide 610 resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin , Polyethylene naphthalate resin, polybutylene terephthalate resin, polyarylate resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfate Down resins, polyethersulfone resins, polyimide resins, polyetherimide resins, monomers such as polyether ether ketone polyether, copolymers, and their two or more mixture may be preferably mentioned. Among these, polypropylene resin, polyamide resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyether ether ketone resin, and the like are desirable.

Examples are shown below, but the present invention is not limited thereto.
[Reference Example 1]
PA6 non-woven fabric was obtained by a melt blow method using Novamid (registered trademark) 1010C2 (Tg 47 degrees, Tm 225 degrees) manufactured by DM Japan Engineering Plastics. In the melt blow method used in the present invention, molten polymer is discharged from a plurality of arranged orifice dies, high-speed gas is injected from an injection gas port provided adjacent to the orifice die, and the discharged molten polymer is made into fine fibers. Then, the nonwoven fabric is produced by collecting the fiber stream on a conveyor net as a collector. The obtained nonwoven fabric had an average fiber diameter of 5 μm, an average fiber length: continuous fiber, and a basis weight of 35 g / m ² .

[Reference Example 2]
Prime Polypropylene (registered trademark) J108M (Tg-20 °, Tm 170 °) was used as a raw material, and a polypropylene nonwoven fabric was obtained by the melt blow method in the same manner as in Reference Example 1. The obtained nonwoven fabric had an average fiber diameter: 4 μm, an average fiber length: continuous fiber, and a basis weight of 35 g / m ² . As a result of measuring the air permeability using a pore size distribution measuring instrument (manufactured by Palm Porometer PMI), it was 20534 (ml / min / cm ² ) under a pressure of 98.67 Pa.

[Example 1]
A carbon fiber yarn having a tensile strength of 4000 MPa and a tensile elastic modulus of 240 GPa (tenax (registered trademark) STS40 F13 24K 1600 tex, manufactured by Toho Tenax Co., Ltd.) was opened to a width of 3 cm, and the carbon fiber yarn was in close contact with the carbon fiber yarn. Then, the carbon fiber yarns having a basis weight of 53 g / m ² were formed into a sheet-like product that was aligned in one direction, and the PA6 nonwoven fabric obtained in Reference Example 1 was superimposed on one side (see FIG. 1). Next, this laminate was integrated at a line speed of 1 m / min and an adhesion temperature of about 190 ° C. using a calender roll machine having a clearance of 50 μm between an elastic roller of 25 ° C. and a metal roller of 210 ° C. An m ² fiber-reinforced resin molding material (hereinafter referred to as a base material) was obtained. As a result of measuring the air permeability of the obtained base material using a pore diameter distribution measuring device (manufactured by Palm Porometer PMI), it was 364 ( ^{ml / min} / cm ² ) under a pressure of 98.67 Pa. Subsequently, when the reinforcing fiber of the base material cut out to a length of 100 mm and a width of 25 mm was peeled off in the fiber longitudinal direction, a force of 1.67 N was required. The result of microscopic observation of only the non-woven fabric after peeling is shown in FIG. Many vertical stripes (3) are observed, which are traces of fibers aligned in one direction in the reinforcing fiber sheet. The fiber structure of the nonwoven fabric was maintained and was not integrated like a film. Moreover, when the obtained base material was cut out in the direction orthogonal to the reinforcing fiber bundle and subjected to a tensile test according to JIS-K7127, the load when the strain was 10% was 4.6 N, which was obtained by the following formula (1). The shaping force evaluation value was 2.09 m ² / s ² .
X = F / L / w (1)
(X = shaped force evaluation value (m ² / s ² ), F: tensile load (N), L: sample width (m), w: molding material basis weight (g / m ² ))

[Example 2]
A carbon fiber yarn having a tensile strength of 4000 MPa and a tensile elastic modulus of 240 Gpa (tenax (registered trademark) STS40 F13 24K 1600 tex, manufactured by Toho Tenax Co., Ltd.) was opened to a width of 3 cm, and the carbon fiber yarn was intimately and closely contacted. After forming a sheet-like material in which the fiber yarns having a basis weight of 53 g / m ² are aligned in one direction, the polypropylene nonwoven fabric obtained in Reference Example 2 was superposed on one side (FIG. 1). reference). Next, this laminate was integrated at a line speed of 5 m / min and a bonding temperature of about 130 ° C. with a calender roll machine having a clearance of 50 μm between an elastic roller of 25 ° C. and a metal roller of 150 ° C., and a basis weight of 88 g / m ^2. A base material was obtained. It was 165 [ ^{ml / min} / cm < ² >] under the pressure of 980.67 Pa as a result of measuring the air permeability of the obtained base material using the pore diameter distribution measuring device (made by Palm Porometer PMI). Subsequently, when the reinforcing fiber of the base material cut into a length of 100 mm and a width of 25 mm was peeled off in the fiber longitudinal direction, a force of 0.74 N was required. Only the nonwoven fabric after peeling was observed with a microscope (see FIG. 3). Many vertical stripes (3) are observed, which are traces of the reinforcing fiber sheet aligned in one direction. The fiber structure of the nonwoven fabric was maintained and was not integrated like a film. Moreover, when the obtained base material was cut out in the direction orthogonal to the reinforcing fiber bundle and subjected to a tensile test according to JIS-K7127, the load when the strain was 10% was 9.8 N, and the above formula (1) The shaping force evaluation value obtained in step 4 was 4.45 m ² / s ² .

[Comparative Example 1]
A base material having a weight per unit area of 88 g / m ² was obtained in the same manner as in Example 1 except that pressure bonding was performed using a 260 ° C. elastic roller and a 260 ° C. metal roller, and the adhesion temperature was about 250 ° C. Next, when trying to peel off the reinforcing fibers of the base material cut to a length of 100 mm and a width of 25 mm in the fiber longitudinal direction, the PA6 nonwoven fabric was melt impregnated and could not be peeled off. As a result of measuring the air permeability of the obtained base material using a pore size distribution measuring instrument (manufactured by Palm Porometer PMI), it was 8.1 (ml / min / cm ² ) under a pressure of 980.67 Pa. It was. Next, the obtained base material was observed with a microscope. The resin was not completely impregnated between the reinforcing fibers, and an unimpregnated portion was confirmed (see FIG. 4). Moreover, when the obtained base material was cut out in the direction orthogonal to the reinforcing fiber bundle and subjected to a tensile test according to JIS-K7127, the base material was broken at a strain of 1. The load at this time was 3.3N. Calculating the shaping force evaluation value from the equation (1) using a load at break was 1.5m ² / ^{s 2.}

DESCRIPTION OF SYMBOLS 1 Reinforcing fiber sheet 2 Non-woven fabric made of thermoplastic resin 3 Trace of peeling off the reinforcing fiber sheet

Claims (3)

  A nonwoven fabric made of a thermoplastic resin is brought into contact with at least one of the reinforcing fiber sheets in which the reinforcing fiber bundles are aligned in one direction, and is applied in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the thermoplastic resin. A fiber-reinforced resin molding material characterized by being integrated by pressing. The fiber-reinforced resin molding material according to claim 1, wherein the air permeability under a pressure of 980.67 Pa is 50 to 1000 (ml / min / cm ² ). In the tensile test in the direction orthogonal to the reinforcing fiber bundle, the shaping force evaluation value defined by the formula (1) is in the range of 0.3 to 6.5 m ² / s ^{2 at} a strain of 10%. 2. Fiber-reinforced resin molding material.
X = F / L / w (1)
(X = shaped force evaluation value (m ² / s ² ), F: tensile load (N), L: sample width (m), w: molding material basis weight (g / m ² ))