JPH09254248A - Fiber reinforced thermoplastic resin hollow molded object and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber reinforced thermoplastic resin hollow molded object having an outer shell layer composed of a porous fiber reinforced thermoplastic resin higth in voids and a hollow part. SOLUTION: Thermoplastic resin air impermeable films 7, 7' are bonded to both surfaces of a two-layered sheet obtained by mutually laminating and bonding fiber reinforced thermoplastic resin sheets 6, 6' containing reinforcing fibers by a hot-melt adhesive melted at the m.p. of the thermoplastic resin being the matrix of the sheets 6, 6' or lower to form a multilayered sheet 8 which is, in turn, preheated to the m.p. of the thermoplastic resin being the matrix or higher to be expanded in its thickness direction and the expanded multilayered sheet is arranged between a pair of molds planned so as to have a cavity clearance equal to or larger than the thickness of the multilayered sheet 8 after preheating at least at a part of a cavity at a time of the completion of molding while holding the preheated state and, after or while mold clamping is performed, vacuum suction is performed from a plurality of vacuum suction holes preliminarily provided to the molding surface of either one of molds or both molds.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fiber-reinforced thermoplastic resin hollow molded article and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, when a fiber-reinforced thermoplastic resin sheet containing fibers (sheet-shaped molding material) is heated above the melting temperature of a thermoplastic resin as a matrix, it is heated or pressed during the production of the sheet. Of the fiber reinforced thermoplastic resin sheet in the thickness direction by preheating the sheet above the melting temperature of the matrix resin by utilizing the property that the residual stress on the fiber is released (spring back) and expands in the thickness direction. By expanding the sheet, supplying the expanded sheet between a pair of molds while maintaining the preheated state, and clamping the mold so that the mold clamping clearance becomes larger than the thickness of the raw material sheet before preheating, the so-called expansion molding method It is well known to produce a porous molded body having a large porosity, which is thicker than the sheet thickness but thinner than the thickness when expanded by preheating, The porous fiber-reinforced thermoplastic resin molded product with a high porosity obtained by crushing is light in weight, excellent in strength, and also excellent in sound absorption and heat insulation, so that it is used for automobile interior materials, home appliances, building materials. It is used in a wide range of fields such as.

However, in recent years, further improvement in sound absorbing properties and heat insulating properties has been demanded. For this reason, the present inventors use such a porous fiber-reinforced thermoplastic resin having a high porosity as the outer shell of the hollow portion. We investigated to develop a hollow molded body, but the thickness of the molded body obtained by the conventional expansion molding method is limited to the expanded thickness after preheating, and the desired molded body thickness is less than the expanded thickness after preheating of the raw material sheet. It has not been possible to manufacture a hollow molded article having a thick portion and an outer shell forming a hollow portion made of a porous fiber-reinforced thermoplastic resin having a high porosity.

For this reason, the present inventors have examined a method of forming a hollow portion by vacuum-sucking the expanded sheet from one side or both sides in a molding die and dividing the sheet into both sides in the thickness direction. The suction itself is possible by pasting non-breathable films on both sides of the expansion sheet because the expansion sheet has high air permeability, but when the thickness of the molded body exceeds the thickness of the expansion sheet after preheating. In the hollow part, even if a hollow part is obtained, since the hollow part is the result of tearing of the tissue of the expansion sheet at an unspecified site, the hollow part Cannot be reproduced as designed, and the thickness of the outer shell layer that forms the obtained hollow molded body varies depending on the site, resulting in different strength depending on the site, or the hollow body itself is not formed Not obtained there is a problem, such as.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The inventors of the present invention have solved the above problems and use a fiber-reinforced thermoplastic resin sheet as a raw material, and the outer shell forming the hollow portion is a fiber-reinforced thermoplastic resin hollow hollow porous porous fiber-reinforced thermoplastic resin. As a result of further study to manufacture a molded body,
The present invention has been reached.

[0006]

According to the present invention, fiber-reinforced thermoplastic resin sheets containing reinforcing fibers are laminated and bonded together with a hot-melt adhesive which melts at a temperature equal to or lower than the melting point of the thermoplastic resin which is the matrix of the sheets. A multi-layer sheet made by laminating a thermoplastic resin non-breathable film on both sides of a layer sheet is preheated to a temperature above the melting temperature of the thermoplastic resin matrix and expanded in the thickness direction, and then the preheated state is maintained While arranging between the pair of molding dies designed to have a cavity clearance at least a part of the cavity which is equal to or more than the thickness of the preheated multilayer sheet at the time of completion of molding, and then perform mold clamping, or The outer shell is characterized in that vacuum suction is performed from a plurality of vacuum suction holes provided in advance on the molding surface of one or both of the molds while tightening. There is provided a method for producing a fiber-reinforced thermoplastic resin hollow molded body made from a pasted a thermoplastic resin non-breathable film made in the layer porous fiber-reinforced thermoplastic resin.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The fiber-reinforced thermoplastic resin sheet containing the reinforcing fibers used as a raw material in the present invention may be produced by any method as long as it expands by preheating to form a porous fiber-reinforced thermoplastic resin sheet having a high porosity. It is applicable without, for example, a method of stabbing a plurality of strand-shaped needles into a fiber bundle, laminating matte strand reinforcing fibers and thermoplastic resin in which fibers are entangled with each other, and heating and pressing to form a sheet, A method of mixing reinforcing fibers and thermoplastic resin granules that may contain reinforcing fibers and heating and pressing to form a sheet, or uniformly dispersing the reinforcing fibers and thermoplastic resin powder in water, and then papermaking To produce a non-woven material, and various fiber-reinforced thermoplastic resin sheets produced by a known method such as a method of heating and pressing the non-woven material to form a sheet (papermaking method) are used. Among them, although not particularly limited, a fiber-reinforced heat produced by a papermaking method that is homogeneous, can obtain a high expansion ratio, and can adjust the expansion ratio relatively easily. The plastic resin sheet is most preferably used.

In such a fiber-reinforced thermoplastic resin sheet, the expansion ratio and the physical properties are different depending on the content, type, fiber diameter, fiber length, etc. of the reinforcing fibers in the sheet. However, if the reinforcing fiber content is too small, the expandability becomes poor and a porous fiber-reinforced thermoplastic resin molded product having sufficient voids cannot be obtained, so the reinforcing fiber content in the sheet is at least 10% by weight or more, preferably 20% by weight or more,
The content is more preferably 30% by weight or more, and the upper limit thereof is not particularly limited, but if the content of the reinforcing fiber is too large, the amount of the thermoplastic resin serving as the binder becomes too small, which makes it difficult to maintain the shape. Therefore, it is generally 80% by weight or less.

Examples of the reinforcing fibers used in such a fiber-reinforced thermoplastic resin sheet include inorganic fibers such as glass fibers, carbon fibers, metal fibers such as linear stainless steel, organic fibers such as aramid fibers, natural fibers and mixtures thereof. However, glass fiber, which can obtain a high reinforcing effect at low cost, is preferably used. The fiber diameter of such reinforcing fibers is
It is usually 1 to 50 μm, preferably 3 to 30 μm, and the fiber length is 3 mm or more, preferably 5 mm from the viewpoint of reinforcing effect.
As described above, for example, when glass fiber is used as the reinforcing fiber and a fiber-reinforced thermoplastic resin sheet is manufactured by a papermaking method, the content of the glass fiber in the sheet is 30 to 6
0% by weight, fiber diameter 10 μm or more, fiber length 10-30
The sheet weight is preferably about 400 mm / g, and the weight of the sheet is 400-6000 g /
It is preferably in the range of m ² . Further, in order to improve the wettability with the matrix resin, the fiber surface may be subjected to a sizing treatment (for example, JP-A-4-300923).

Examples of the thermoplastic resin which is a matrix resin include polyolefin resins such as polyethylene and polypropylene, polystyrene, acrylonitrile-styrene-butadiene copolymer, polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate,
Typical thermoplastic resins such as polybutylene terephthalate, polyphenylene ether, and styrene / acrylonitrile copolymer, modified products thereof, thermoplastic elastomers such as EPM and EPDM, mixtures thereof, polymer alloys using them, and the like. To be still,
The thermoplastic resin in the present invention is meant to include all of these.

Further, the adhesive for adhering the two fiber-reinforced thermoplastic resin sheets to each other is required to have an adhesive force so that the two layers will not be peeled off until the two-layer sheet adhered to them is preheated. However, the adhesive strength is significantly reduced during molding, and when the two-layer sheet is vacuum-sucked from the molding surface, it is necessary that both laminated layers are easily separated. . Therefore, as the adhesive applied to the present invention, a hot-melt adhesive that melts at a temperature equal to or lower than the melting point of the thermoplastic resin that is the matrix of the raw material sheet is used. Considering the temperature drop, the melting point of the material is 5
A hot melt adhesive having a melting point or softening point lower than 0 ° C. is preferable. By using such an adhesive, the two-layer sheet before preheating can be handled as an integral sheet that is firmly joined without peeling, but this is not less than the melting temperature of the thermoplastic resin that is the matrix. When preheated to the mold and supplied between the molds while maintaining this preheated state, the adhesive melts at the preheat temperature and the adhesive strength is significantly reduced. The two layers easily separate. Diverged 2
The layers are sucked onto the respective molding surfaces as outer shells of the hollow portions while forming hollow portions between the layers. Such a hot melt adhesive is not particularly limited as long as it has the above-mentioned properties, but an ethylene-vinyl acetate copolymer is typically mentioned.

When the two fiber-reinforced thermoplastic resin sheets are bonded to each other, it is not always necessary to bond them over the entire surface of the sheet, but they may be bonded partially, but both the sheets are directly bonded without an adhesive layer. At the contacting parts, the matrix resins of each sheet are in contact with each other in a molten state and integrated, and it becomes difficult to peel off even if vacuum suction is applied.Therefore, at least in the subsequent shaping process, both sheets are vacuum suctioned from the molding surface. It is preferable that a certain portion (hollow forming portion) that needs to be peeled off is bonded to the entire surface or a wide portion so that the sheets do not come into direct contact with each other.

Since such a two-layer sheet has many voids in the preheated and expanded state and has high air permeability, vacuum suction in this state makes no sense. For this reason, it is necessary to bond a non-breathable film or sheet made of a thermoplastic resin on both surfaces of the two-layer sheet. The fiber-reinforced thermoplastic resin sheet may be preliminarily adhered to one surface of each, or two fiber-reinforced thermoplastic resin sheets may be adhered to each other to form a two-layer sheet and then adhered. The method of sticking such a film or sheet is arbitrary, and may be stuck by an adhesive before or after forming a two-layer sheet, but in general, heating at the time of producing a fiber-reinforced thermoplastic resin sheet as a raw material, The film or sheet is placed on one side at the same time when pressure-bonding, and is attached by heat fusion, or it is directly laminated on both sides of a preheated two-layer sheet and is attached by heat fusion. Is preferred.

Examples of the non-breathable film or sheet include polyolefin resins such as polyethylene and polypropylene, polystyrene, acrylonitrile / styrene / butadiene copolymer, polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate,
General thermoplastic resins such as polybutylene terephthalate, polyphenylene ether, and styrene-acrylonitrile copolymer, modified products thereof, single-layer or multilayer films and sheets made of thermoplastic elastomers such as EPM and EPDM are used. The material, thickness, etc. of the two-layer sheet are appropriately selected so that they do not peel off or break during the molding process such as preheating and vacuum suction. Further, when using a film or sheet made of the same or similar material as the matrix resin of the fiber-reinforced thermoplastic resin sheet of the raw material, or a material having a lower melting point than the matrix resin, the film or sheet at the same time during preheating Care must be taken because it may melt and dissolve in the matrix resin, resulting in loss of non-air permeability.

In the present invention, such a non-breathable film or sheet may also serve as a skin layer as the outermost layer, but for the purpose of decoration, a non-breathable film or sheet may be formed on the non-breathable film or sheet. Further, a skin material may be attached. Such a skin material is laminated on one or both surfaces according to the purpose of use, and may be adhered to the surface of the hollow molded body with an adhesive or the like after the molding, but usually the hollow molded body is formed. It is attached at the same time. When the surface is decorated by the latter method, a breathable skin material is used as the skin material,
For example, a woven or non-woven fabric made of a general thermoplastic resin fiber such as polyester, polyurethane, polypropylene or a mixture thereof is used. Such a skin material is superposed on a multilayer sheet before or after preheating,
In the case of the former, it is then preheated, and in the case of the latter, it is supplied between the molds while maintaining the preheated state, and vacuum suction is performed to shape the skin material, so that the skin material is Adhesion strength sufficient for practical use is exhibited by the anchoring effect with the non-breathable film or sheet heated by preheating. At this time, when the strength is insufficient, the adhesive layer is partially or entirely laminated with a hot melt adhesive or the like on the back surface of the skin material or the skin material side of the non-air-permeable film or sheet in advance. However, care must be taken not to impair the air permeability of the skin material by laminating the adhesive layer. Further, the adhesive at this time is preferably made of a resin component having a higher melting temperature than the adhesive used when forming the two-layer sheet so that the adhesive does not peel off during vacuum suction.

The present invention expands a multilayer sheet obtained by laminating a non-breathable film or sheet on both surfaces of a two-layer sheet obtained by laminating two such fiber-reinforced thermoplastic resin sheets with an adhesive. , For producing a fiber-reinforced thermoplastic resin hollow molded body by vacuum suction, the molded body thickness of the hollow portion of the target molded body is required to be at least the expansion thickness of the raw material multilayer sheet, For this reason, the pair of molding dies applied to the present invention must be designed to have a cavity clearance, which is equal to or larger than the thickness of the expanded multi-layer sheet after preheating, in at least a part of the cavities after the completion of molding. Is.

Further, in the method of the present invention, during mold clamping in the molding process, the clearance of the outer peripheral portion of the hollow portion to be formed is not less than the thickness of the raw material multilayer sheet before preheating,
It is necessary that the thickness be less than that after preheating.
If this clearance is less than the thickness before preheating, the cavity will be in a completely closed state after mold clamping, and air inflow from the outside of the mold through the raw material multilayer sheet will be obstructed during vacuum suction from the molding surface. However, it is impossible to form a sufficient hollow portion. Further, if the clearance is equal to or larger than the thickness before preheating, air does not flow in too much from the expanded multilayer sheet even if vacuum suction is performed, the suction effect does not occur, and similarly, the hollow portion cannot be formed. When the clearance is in the above range, while being sucked from each of the molding surfaces of one side or both sides of the expanded multilayer sheet, the air outside the mold during the vacuum suction appropriately flows through the raw material multilayer sheet and melts. The adhesive layer with reduced adhesive force separates and each sheet is adsorbed to the molding surface on each side to form a hollow portion. The clearance other than the portion where the hollow portion is formed is appropriately selected according to the shape of the target molded product, but is generally not less than the pre-heating thickness of the raw material multilayer sheet and not more than the pre-heating thickness thereof. Further, the vacuum suction may be performed from one side or both sides of the expanded multilayer sheet, but when it is from one side, the adhesive layer does not separate and the opposite side is also sucked toward the suction surface at the same time. Therefore, it is particularly preferable to suck from both sides.

Next, the manufacturing method of the present invention will be described with reference to the drawings. In the present invention, as shown in FIG. 1, a pair of molding dies is used, and either one or both of the molding dies is fixed and connected to a mold clamping device (not shown) so as to move vertically or laterally. It can be opened and closed so that it can be moved to. (In FIG. 1, there is shown a case where a molding die composed of an upper mold (1) and a lower mold (2) movable in the vertical direction is used.) In order to form a hollow portion, this molding mold is As described above, it is designed to have a cavity clearance equal to or larger than the thickness of the expanded multi-layer sheet after preheating in at least a part of the cavity (desired hollow part) after the completion of molding. Further, a suitable number of small holes (3) for vacuum suction are provided on the molding surfaces of both molds, and these are appropriately assembled and connected to the vacuum suction device (4). The hole diameter of the small holes for vacuum suction is usually extremely small, but when it is transferred to the design surface of the molded body and adversely affects it, the whole or a part of the molded surface is covered with a porous metal plate ( Instead of 5) or the like, vacuum suction may be performed through the metal plate. The material of the mold is a required accuracy among various commonly used materials such as metal materials, wood, and resin.
It is appropriately selected depending on the strength.

In the production method of the present invention, the pair of molding dies (1, 2) are opened, and the two fiber-reinforced thermoplastic resin sheets (6, 6,) are provided between the molding dies.
6 ') is laminated with an adhesive (13) to form a multi-layer sheet (8) (FIG. 4) obtained by laminating a non-breathable film or sheet (7, 7') on both sides of the sheet. An expansion sheet (9) preheated to a temperature not lower than the melting temperature of the matrix resin and expanded in the thickness direction is arranged while maintaining the preheated state. (FIG. 1) At this time, if necessary, the skin material (10) may be previously attached to one surface or both surfaces of the expansion sheet, or may be simply superposed on the expansion sheet. In the latter case, for example, when using a molding device that moves up and down, when decorating the upper surface of the expansion sheet with a skin material, the skin material may be placed directly on the expansion sheet,
As shown in FIG. 1, the end portion of the skin material may be held by a clamp frame (11) that can be held between the skin and the parting surface, and the skin material may be arranged so as to be located above the expansion sheet. Also, when decorating the lower surface of the expansion sheet with a skin material, the skin material may be placed on the molding surface of the lower mold in advance, and the expansion sheet may be placed on top of this. When decorating with, these methods may be combined.

In the preheating of the above-mentioned multilayer sheet, the preheating temperature varies depending on the types of the reinforcing fibers constituting the sheet and the thermoplastic resin which is the matrix resin, the content of the reinforcing fibers, etc., but when the preheating temperature is low, sufficient expansion occurs. Property is not obtained, and the hot melt adhesive does not melt, making it difficult to create hollow parts, and when bonding a skin material, the adhesiveness between the skin material and a non-breathable film or sheet Since it is inferior, it is necessary to preheat at least above the melting temperature of the matrix resin. Further, the expanded sheet expanded by such preheating needs to be supplied between the molding dies so as to maintain this preheated state and not fall below the melting temperature even if there is a slight temperature decrease. However, heating to an excessively high temperature not only causes deterioration of the matrix resin but also makes handling difficult. Therefore, for example, when glass fiber is used as the reinforcing fiber and polypropylene resin is used as the matrix resin, The preheating temperature is usually about 180 to 220 ° C.

After arranging the expansion sheet in which the preheated state is maintained between the molds, the mold clamping is started, and the mold clamping is completed when the predetermined cavity clearance is reached. (FIG. 2) Upon completion of this mold clamping, the mold outer peripheral clearance of the outer peripheral portion of the hollow portion to be formed needs to be not less than the pre-heating thickness of the raw material multilayer sheet and not more than the pre-heating thickness. In FIG. 2, the space (h) between the respective parting surfaces of both molds corresponding to the clearance is set within the above range. The position control of the completion of mold clamping is performed by any method such as a method of controlling the completion position of the mold clamping device fixed or connected to the mold, but it does not require an expensive control device and is reliable. At the point, the stopper (1
The method of 2) is preferable.

After completion of the mold clamping, the vacuum suction device is operated to perform vacuum suction through the vacuum suction small holes (3) or the porous metal plate (5) provided on the molding surface of the molding die. Due to such suction, the two bonded fiber-reinforced thermoplastic resin sheets (6, 6 ') are pulled outward in a portion having a cavity clearance wider than the thickness of the expansion sheet (hollow portion forming portion). The adhesive layer, which is melted by the heat due to the preheating and whose adhesive strength is significantly reduced, is separated, and the separated fiber-reinforced thermoplastic resin sheet (6,
6 ') is a hollow shell (15, 15') formed by bonding a non-breathable film (7, 7 ') to the outer layer while forming a hollow portion (14) between both sheets, and has a mold shape. Is transferred to each molding surface while being transferred. (FIG. 3) At this time, since the fiber-reinforced thermoplastic resin sheet has been expanded by preheating and has already become porous, the outer shell derived from the sheet also has a porous structure having voids. Here, the degree of vacuum suction varies depending on the molding conditions such as the preheating temperature of the expansion sheet, the expansion ratio, the size of the hollow portion, and the clearance of the outer peripheral portion of the hollow portion when the mold clamping is completed. The higher the degree of reduced pressure, the better the transferability of the shape of the mold, and the better the adhesiveness when the skin material is laminated at the same time, which is preferable, but usually the pressure in the mold is 0.5 kg / cm ² or less. , Preferably 0.3 kg
Vacuum suction is performed to the extent that the pressure is less than / cm ² .

Although the method of starting vacuum suction after the completion of mold clamping has been described above, the mold clamping is performed after the mold clamping is started until the clearance of the outer peripheral portion of the hollow portion is equal to or smaller than the thickness of the expansion sheet. If the inside of the mold becomes a state in which vacuum suction is possible, the vacuum suction may be started while continuing the mold clamping, and the mold clamping and the vacuum suction may be performed in parallel. Of course, in this case, it is not necessary to perform both operations in parallel until the completion of molding, and the mold clamping may be completed first while performing vacuum suction.

In any of the methods, when the inside of the mold is sufficiently vacuum-sucked, the molded body is cooled, the vacuum suction is stopped, the molding die is opened, and the molded body is taken out. It is possible to obtain a fiber-reinforced thermoplastic resin hollow molded article made of a porous fiber-reinforced thermoplastic resin having voids.
(FIG. 5) In order to facilitate the removal of the molded product from the molding die, for example, a projecting pin that can be stored is provided on the molding surface, and after the molding die is opened, the pin is projected to project the molded product from the molding surface. It is also possible to allow it.

In such a method, when the skin material is used by being superposed on the expansion sheet, the skin material is firmly and integrally bonded to the base material through the non-breathable film or sheet in the molding process, and , Without using the skin material,
When a non-breathable film or sheet is also used as the outermost layer also as a skin layer, by providing fine irregularities such as a texture pattern in advance on the molding surface, the surface of the obtained hollow molded article is It is possible to obtain a product with a good appearance by transferring patterns and the like to the character.

Thus, the shape of the mold is accurately transferred, the fiber-reinforced thermoplastic resin sheet as the raw material is expanded, and the non-air-permeable thermoplastic resin film is laminated on the outer layer of the fiber-reinforced thermoplastic resin sheet. A fiber-reinforced thermoplastic resin hollow molded article excellent in lightness and strength is obtained by using a thermoplastic resin as an outer shell and further laminating a surface material on the surface thereof, if necessary, and the hollow molded article utilizes its properties. Thus, it can be widely used for various purposes, in particular, as a heat insulating material, a sound absorbing material, etc., and as an interior material having these properties, as an automobile part, a home electric appliance part, a heat insulation container, and the like.

[0027]

EFFECTS OF THE INVENTION According to the method of the present invention, a fiber-reinforced thermoplastic resin sheet is used as a raw material, and a thermoplastic resin non-breathable film is laminated on the outer layer of the fiber-reinforced thermoplastic resin sheet as a raw material. It is possible to easily obtain a fiber-reinforced thermoplastic resin hollow molded article excellent in lightweight and strength, which is obtained by laminating a resin as an outer shell and further adhering a skin material on the surface thereof, and the hollow molded article thus obtained. Utilizing its properties, it can be widely used for various applications, particularly as a heat insulating material, a sound absorbing material, etc., and as an interior material having these properties, as an automobile part, a home electric appliance part, a heat insulation container, etc.

The present invention will be described below with reference to examples.
It goes without saying that the present invention is not limited to this.

Example 1 Fiber-reinforced thermoplastic resin sheet obtained by the paper-making method (matrix resin: polypropylene, reinforcing fiber: glass fiber, glass fiber filling rate: 50% by weight, average glass fiber length: 25 m
m, average glass fiber diameter: 15μ, basis weight: 1300 g / m
² pieces, 1 mm thick) were bonded with an ethylene / vinyl acetate hot melt adhesive with a softening point of 90 ° C, and a random polypropylene film (melting temperature: 155 ° C,
A two-layer film obtained by dry laminating a nylon film (melting temperature: 260 ° C., thickness: 25μ) on MFR: 9, thickness: 60μ so that the polypropylene film side faces the above sheet side, respectively, to obtain a multilayer sheet. It was The thickness of the compact is designed to be minimum 20 mm and maximum 30 mm, and a pair of upper and lower molds in which a large number of 0.5 mmφ vacuum suction holes are arranged on both mold surfaces are opened, and the mold 210 is opened between both molds. Preheated to ℃ and its thickness is 14
The multilayer sheet expanded to mm was placed. The mold outer peripheral clearance [between each parting surface (h) of both upper and lower molds corresponding to the outer peripheral part of the hollow part in FIG. 2] is 5 m
Both molds are closed to a stopper set at a position of m, and vacuum suction is performed between the surface of the multilayer sheet and each molding surface through a vacuum suction hole until the inside of the cavity becomes approximately 0.3 atm. After cooling the molded body, vacuum suction was stopped, the inside of the cavity was returned to atmospheric pressure, the mold was opened, and the molded product was taken out. The obtained molded body accurately transferred the shape of the mold, and the molded body had a minimum thickness of 20 mm as designed.
The maximum was 30 mm. Also, as seen from the cross section of this molded body, the fiber-reinforced thermoplastic resin sheet as the raw material is almost completely peeled off at the adhesive layer portion of the multilayer sheet and is made of a porous fiber-reinforced thermoplastic resin having a thickness of about 7 mm. An outer shell was formed, and a hollow portion having a width of about 6 mm was formed in a portion having a thickness of 20 mm and a hollow portion having a width of about 16 mm in a portion having a thickness of 30 mm.

Example 2 Example 1 was repeated except that instead of the vacuum suction holes in the molding surface, a porous metal plate capable of vacuum suction was provided on the molding surface and a molding die in which a fine grain pattern was carved on the molding surface was used. A molded product was obtained in the same manner as in. The obtained molded product had a grain pattern on its surface, and its shape accurately transferred the mold shape. In addition, the cross section of this molded body is similar to that of the molded body obtained in Example 1, and an outer shell made of a porous fiber-reinforced thermoplastic resin having a thickness of about 7 mm is formed. In a portion having a width of about 6 mm and a thickness of 30 mm, a hollow portion having a width of about 16 mm was formed.

Example 3 In the method of Example 1, the melting point was 260 ° C. and the basis weight was 50.
A g / m ² polyester non-woven fabric is laminated on one surface with a hot melt adhesive that is softened at about 90 ° C and has good adhesion to nylon, and is preheated so that the hot melt layer is on the sheet side. A hollow molded body was obtained in the same manner as in Example 1 except that the hollow molded body was placed on both sides of the multilayer sheet. The obtained molded product had a polyester non-woven fabric firmly adhered to its surface, and its shape accurately transferred the mold shape. In addition, the cross section of this molded body is similar to that of the molded body obtained in Example 1, and an outer shell made of a porous fiber-reinforced thermoplastic resin having a thickness of about 7 mm is formed. Approximately 16 in width of approximately 6mm and thickness of 30mm
A hollow portion having a width of mm was formed.

Example 4 Fiber-reinforced thermoplastic resin sheet obtained by the paper-making method (matrix resin: polypropylene, reinforcing fiber: glass fiber, glass fiber filling rate: 50% by weight, average glass fiber length: 25 m
m, average glass fiber diameter: 15μ, basis weight: 1300 g / m
² , fiber reinforced thermoplastic resin sheet obtained by the papermaking method (matrix resin: polypropylene, reinforcing fiber: glass fiber, glass fiber filling rate: 30% by weight, average glass fiber length: 25 mm, average glass fiber diameter: 15μ,
Unit weight: 2500 g / m ² , thickness 2 mm), and softening point 9
Bonded with ethylene / vinyl acetate hot melt adhesive at 0 ° C, nylon polypropylene film (melting temperature: 260 ° C, thickness: random polypropylene film (melting temperature: 155 ° C, MFR: 9, thickness: 60μ) on both sides. : 25 μ) was dry-laminated to obtain a multilayer sheet by laminating the polypropylene film side on the sheet side. Minimum thickness of molded body is 19m
m, designed to have a maximum length of 40 mm, and a pair of upper and lower molding dies having a large number of 0.5 mmφ vacuum suction holes arranged on both molding surfaces are opened and preheated to 210 ° C. between both dies. The multilayer sheet expanded to a thickness of 17 mm was arranged. The mold outer peripheral clearance [in FIG. 2, the space between the parting surfaces (h) of the upper and lower molds corresponding to the outer peripheral part of the hollow part] is closed to a stopper set at a position of 7 mm, and vacuum suction is performed. Through the holes, vacuum suction is performed between the surface of the multilayer sheet and each molding surface until the inside of the cavity becomes about 0.3 atm. After cooling the molded body, vacuum suction was stopped, the inside of the cavity was returned to atmospheric pressure, the mold was opened, and the molded product was taken out. The shape of the obtained molded body was accurately transferred, and the thickness of the molded body was 19 mm minimum and 40 mm maximum as designed. Also, looking at the cross section of this molded body, the fiber-reinforced thermoplastic resin sheet as the raw material was almost completely peeled off at the adhesive layer portion of the multilayer sheet, and the thickness was about 7 mm on one side and the thickness on one side. 10m
An outer shell made of a porous fiber-reinforced thermoplastic resin of m is formed, and the width of the molded body is about 2 mm in a portion where the thickness is 19 mm.
A hollow portion having a width of about 23 mm was formed at a portion having a thickness of 40 mm.

[Brief description of drawings]

FIG. 1 is a sectional view of a mold showing an outline of a manufacturing process of a hollow molded body of the present invention.

FIG. 2 is a sectional view of a mold showing an outline of a manufacturing process of the hollow molded body of the present invention.

FIG. 3 is a cross-sectional view of a mold showing an outline of the manufacturing process of the hollow molded body of the present invention.

FIG. 4 shows a cross section of a multilayer sheet.

FIG. 5 shows a cross section of the hollow molded article of the present invention.

[Explanation of symbols]

1: Upper mold 2: Lower mold 3: Vacuum suction hole 4: Vacuum suction device 5: Porous metal plate 6: Fiber reinforced thermoplastic resin sheet 7: Non-breathable film 8: Multilayer sheet 9: Expansion sheet 10: Skin material 11: Clamp frame 12: Stopper 13: Adhesive layer 14: Hollow part 15: Outer shell h: Mold outer peripheral clearance at the time of mold clamping

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B29L 9:00 22:00 (72) Inventor Masui Kouhei 2-27-1 Shinkawa, Chuo-ku, Tokyo Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Yuji Kobayashi 2-27-1 Shinkawa, Chuo-ku, Tokyo Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Satoshi Funakoshi 2-10-1 Tsukahara, Takatsuki, Osaka Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Katsuhiro Nagayama 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Corporation Technical Research Institute (72) Inventor Masami Fujimaki 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Engineering Co., Ltd. Technical Research Institute (72) Inventor Hiroyuki Yoshitake, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Cape La Sheet Co., Ltd.

Claims (5)

[Claims] 1. A fiber-reinforced thermoplastic resin hollow molded article comprising a porous fiber-reinforced thermoplastic resin having an outer shell laminated with a thermoplastic resin film on its outer layer. 2. A thermoplastic resin on both sides of a two-layer sheet in which fiber-reinforced thermoplastic resin sheets containing reinforcing fibers are laminated and adhered to each other with a hot-melt adhesive that melts below the melting point of the thermoplastic resin that is the matrix of the sheets. A multi-layered sheet made by laminating non-breathable film is preheated to above the melting temperature of the thermoplastic resin matrix and expanded in its thickness direction, then preheated at the completion of molding while maintaining the preheated state. One of the molding dies is arranged between a pair of molding dies designed to have a cavity clearance equal to or larger than the thickness of the subsequent multilayer sheet in at least a part of the cavity, and then the mold is clamped, or while the mold is clamped. Alternatively, the outer shell is made of a thermoplastic resin fill film and is vacuum-sucked through a plurality of vacuum suction holes provided in advance on the molding surfaces of both molds. Method for producing a fiber-reinforced thermoplastic resin hollow molded body made of a porous fiber-reinforced thermoplastic resin obtained stuck to. 3. The method for producing a fiber-reinforced thermoplastic resin hollow molded article according to claim 2, wherein one or both of the molding dies is provided with a pair of molding dies each having a finely uneven pattern on its molding surface. 4. A skin material capable of adhering to a non-breathable thermoplastic resin film at a preheating temperature is previously supplied between the multilayer sheet and one or both mold surfaces of a pair of molding dies. 2. The method for producing a fiber-reinforced thermoplastic resin hollow molded article according to 2. 5. The method for producing a fiber-reinforced thermoplastic resin hollow molded article according to claim 2, wherein the fiber-reinforced thermoplastic resin sheet is a papermaking method fiber-reinforced thermoplastic resin sheet.