JPS6050135B2 - Manufacturing method for fiber-reinforced plastic moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing molded articles from fiber-reinforced plastic sheets.

The object of the present invention is to produce a fiber-reinforced plastic sheet (hereinafter referred to as a blank sheet or simply blank).

) when press-molding a molded article, the reinforcing fibers and thermoplastic resin in the blank sheet. To provide a method for producing a fiber-reinforced plastic molded product, which allows for efficient production of high-quality molded products by preventing the two from separating and allowing both to flow smoothly to every corner of the mold. Conventionally, automobile hoods, trunk covers, front end retainers, seat frames, and various other appliances, covers, containers, and the like have mostly been manufactured by press-molding metal.

However, in recent years, press molding technology for glass fiber-reinforced plastics has progressed rapidly, and fiber-reinforced plastic molded products have come to be widely used instead of these metal molded products. These fiber-reinforced plastic molded products can shorten the pressing process, are lightweight, and can freely change the wall thickness of the cross section and add bosses or ribs during molding. It has the advantages of The above-mentioned fiber-reinforced plastic molded products are usually manufactured by heating a blank sheet of reinforcing nonwoven fiber mat and thermoplastic resin and then pressing it between cooled matte dies. For example, SAEpaper 72
006 reduction is disclosed in Plasticage October issue (1971), pages 83-88.

The blank sheet to be press-molded is heated to a temperature above the softening point or melting point of its component thermoplastic resin, and then transferred between press molds which are cooled to a temperature below the softening point or melting point. Then, the mold is closed and pressed to perform molding.

This molding method is usually called hot flow molding, and a blank sheet having an area smaller than the projected area of the product part of the mold is charged into the mold. Techniques for manufacturing such blank sheets are disclosed, for example, in Japanese Patent Laid-Open No. 48-801n and Japanese Patent Laid-Open No. 52-40588. but,
When trying to obtain a thin-walled molded product with a thickness of 1 h or less of the blank plate thickness from a blank using these known methods, the reinforcing fibers and thermoplastic resin often separate, and in many cases, the charging area becomes small and the corners of the mold It was found that the liquid did not flow well even in the parts.

Further, if the thickness of the blank is made thin in advance in order to correspond to a thin-walled molded product, there is a disadvantage that the heating device required before press molding must be extremely large. Furthermore, there is a drawback that the contact surface of the blank with air increases during heating, resulting in adverse effects such as oxidative deterioration. The present inventors solved the drawbacks of conventional methods related to the manufacturing technology of fiber-reinforced plastic molded products, and the reinforcing fibers in the blank separate from the thermoplastic resin during press molding, regardless of the wall thickness or shape. As a result of intensive research to develop a method to efficiently produce high-quality molded products by flowing smoothly and smoothly to every corner of the mold, the present invention was completed and the desired purpose was achieved. It came to this.

The gist of the present invention is to provide a composite sheet consisting of at least two layers of mat obtained by needling nonwoven fibers and a thermoplastic resin attached to the mat at a temperature higher than the melting point or softening point of the thermoplastic resin. A fiber-reinforced plastic characterized in that the mat is heated to include the resin throughout the mat, the mat is separated into one or more arbitrary layers, and the separated sheets are usually placed in a mold and compression molded. This is a method for manufacturing molded products.

Hereinafter, the configuration, embodiments, and effects of the present invention will be explained in more detail.

Thermoplastics used in the present invention include, for example, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrile copolymer, polyamide, polycarbonate, polysulfone, polyacetal, and polystyrene. Resins such as methyl methacrylate, polyphenylene oxide, thermoplastic polyurethane, polyethylene terephthalate, polybutylene terephthalate, etc., and also include mixtures of two or more of these, and commonly used plasticizers, heat stabilizers and Appropriate amounts of light stabilizers, nucleating agents, fillers, dyes and pigments, processing aids, impact-resistant agents, fillers, short glass fibers, etc. can be added.

The fibers of the reinforcing nonwoven fiber mat used in the present invention are:
These include glass fibers, carbon fibers, metal fibers, fibers made of organic compounds, etc.

Particularly in the present invention, it is preferable to use glass fibers, and preferred embodiments of nonwoven fiber mats using glass fibers will be shown below. Each fiber has a diameter of 2 μ to 30 μ, preferably 5 μ to 25 μ, and a length of 2 cm or more, preferably 5 cm or more.

Each fiber is used in the form of a filament or strand, formed into a long fiber mat or chopped strand mat, and held in the saw body by mechanical bonding by needling.

A preferred mat shape in the present invention is a continuous strand mat having a randomly oriented spiral shape, which is mechanically bonded by needling. The surface of the glass fiber is a binder,
It is treated with a sizing agent, which is a multi-component composition consisting of a lubricant, an emulsifier, a PH adjuster, an antistatic agent, a coupling agent, etc. Among these, there is a sizing agent that strengthens the thermoplastic resin and glass fiber. The coupling agent that bonds at these interfaces is important.

It is already known in the art how to select a springing agent for a combination of thermoplastic plastic and glass fiber, but in the present invention, for example, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β- methoxysilane), β-(3,4-epoxycyclohexyl)monoethyltrimethoxysilane, γ-glycidodipropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β ( (aminoethyl) γ-aminopropyltrimethoxysilane, etc.

The amount of reinforcing nonwoven fiber mat contained in the blank sheet of the present invention is between 10 and 7 weight percent, preferably between 15 and 6 weight percent.

Also, the bulk density of the non-woven fiber mat is 30y/Bo~1800y/
It is preferably 120y/a to 1200y/a. Two or more of these layers, preferably 2 to 8 layers, are contained in the blank sheet. Composite sheets made of these nonwoven fiber mats and thermoplastic resins can be easily produced by conventional extrusion lamination, pressing methods, and the like. An important point in the present invention is that the blank sheet can be easily separated between arbitrary nonwoven fiber mat layers after the blank sheet is heated to a temperature higher than the melting point or softening point of the thermoplastic resin that is a component of the blank. Another advantage is that the resin and fibers do not separate within the mold and can flow to the corners of the mold. Usually, nonwoven fiber mats utilize thermosetting resins or thermoplastic resins as mat binders. 2 non-woven fiber mats using thermosetting resin as mat binder
Blank sheets made of layers and thermoplastic resin can separate the mat layers, but have the disadvantage that the resin and fibers separate in the mold during molding. In addition, when a thermoplastic resin is used as the mat binder, it is difficult to separate the mat layers. The mats used in the present invention are mechanically bonded by needling, and the blank sheet is composed of two or more layers of these laminated together and a thermoplastic resin matrix.

This blank sheet expands in the thickness direction when heated above the melting point or softening point of the thermoplastic resin that is a component of the blank. It is believed that a nonwoven fiber mat mechanically bonded by needling loses its bulk when laminated by extrusion lamination or pressing, but regains some of its bulk when reheated. It will be done. The reason for this is not clear, but it is thought that some of the fibers are oriented in the direction of the mat thickness due to needling, thereby restoring bulk. As a result of the increase in board thickness due to expansion, not only is the separation between the mat layers easier, but the resin matrix between the mat layers is absorbed into the mat layer, and as a result, the resin matrix between the mat layers is extremely reduced. , further facilitating separation.

Furthermore, since the mat is held on the saw body by needling, the layers can be easily separated even after being laminated. The fibers making up the needled mat are free to move relative to each other when the resin matrix is allowed to flow, so that they flow into the corners of the mold without separation of the resin and fibers. Embodiments of the present invention will be described in more detail below with reference to the drawings. FIG. 1 is a sectional view of a blank sheet used in the present invention, in which two layers of needled nonwoven fiber mats 2, 2'' are impregnated with (or adhered to) thermoplastic resin 1 inside and outside. shows.

FIG. 2 shows the state (cross section) of the blank sheet after it has been heated to a temperature higher than the melting point or softening point of the thermoplastic resin attached thereto.

The above-mentioned heating is performed by hot air, infrared rays, high frequency, or other heating means, and infrared heating is one of the preferred means. Next, the heated blank sheet is separated into 2,2'' layers as shown in Figure 3. However, if it is used for a special purpose, it may be separated into two or more layers instead of one layer. Separation The charged area of the blank sheet to the mold is larger than that of the blank sheet that is not separated.
A molded product with a wall thickness of h or less can be easily obtained. Separation is performed in a state where the thermoplastic resin is not solidified. The heating step is usually followed by separation. After the resin is solidified, the mats are fused and solidified, so in order to separate the mats, the resin must be heated again to soften it. Separation can be easily carried out manually, but it is of course preferable to use an appropriate machine or instrument. In order to obtain a desired molded product using the blank sheet separated as described above, the blank sheet is transferred to a mold as illustrated in FIG. 4 and charged.

In Fig. 4, 3 is the lower die of the press molding machine, and 5 is its upper die. Separated blank sheets 4, 4'' are charged to the upper part of the lower die 3, and the upper die is formed as shown in Fig. 5. 5 is closed and pressed to perform molding. Fig. 6 shows a cross section of the molded product 6 obtained by the above-mentioned press molding. As described in detail above, according to the method of the present invention, the blank sheet can be It consists of two or more layers of needled mat and thermoplastic synthetic resin, and the blank sheet obtained by heating this can be easily separated into each layer of the mat, and the amount can be adjusted according to the desired use. , it can be subjected to breath molding.

In this molding process, the reinforcing fibers and the resin do not separate, and both flow smoothly into every corner of the mold, making it possible to efficiently produce uniform, high-quality molded products.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the flank sheet of the present invention, FIG. 2 is a schematic cross-sectional view after this blank sheet is heated, and FIG. 3 is a schematic cross-sectional view showing the blank sheet of FIG. 2 in a separated state. Fig. 4 is an explanatory diagram showing the state in which the sheet is charged in a mold, Fig. 5 is an explanatory diagram showing the state in which the mold is used for press molding, and Fig. 6 is a schematic cross-sectional view of the product obtained by press molding. be. 1: Thermoplastic resin, 2,2'': Nonwoven fiber mat, 3: Mold (lower mold), 4,4'': Blank sheet, 5: Mold (upper mold), 6: Molded product.

Claims (1)

[Claims] 1. At least 2. obtained by needling nonwoven fibers.
A composite sheet consisting of a mat layer and a thermoplastic resin adhered to the mat is heated to a temperature higher than the melting point or softening point of the thermoplastic resin so that the resin is contained throughout the mat, and then the mat is heated. 1. A method for producing a fiber-reinforced plastic molded product, which comprises separating into one or more arbitrary layers and compression-molding them. 2 The amount of nonwoven fiber mat contained in the composite sheet is 1
The method for producing a fiber-reinforced plastic molded article according to claim 1, wherein the content is 0 to 70% by weight. 3. The method for producing a fiber-reinforced plastic molded article according to claim 1 or 2, wherein the nonwoven fibers have a bulk density of 30 to 1800 g/m^2. 4. The method for producing a fiber-reinforced plastic molded article according to claim 1, which is a composite sheet containing 2 to 8 layers of mat.