JPH08174697A - Manufacture of fiber-reinforced thermoplastic resin foam - Google Patents

Abstract

PURPOSE: To obtain a fiber-reinforced thermoplastic resin foam having excellent mechanical strength with relatively light weight. CONSTITUTION: A fiber-reinforced thermoplastic resin foam C is obtained by the steps of continuously shaping glass fiber-reinforced polyvinyl chloride sheet A1 to a hollow element A2, continuously supplying while foaming the foamable polyvinyl chloride into the element A2, and shaping the element in a predetermined sectional shape along a control member by foaming pressure in the case of foaming the foamable chloride while cooling the element from the exterior.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced thermoplastic resin foam comprising a thermoplastic resin foam core layer and a fiber reinforced thermoplastic resin skin layer.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a long synthetic resin composite foam comprising a thermoplastic resin foam core layer and a fiber reinforced synthetic resin skin layer, a thermoplastic resin foam having an irregular cross-sectional shape is continuously produced. A method is known in which continuous fibers impregnated with a thermosetting resin are supplied to the outer surface of the fiber while being transported in one direction, and the fiber is heated to be pultrusion-molded (JP-A-4-33963).
(See Japanese Patent Publication No. 5).

[0003]

In the conventional molding method described above, it is necessary to prepare in advance a foam having an irregular cross-section.
It was very complicated. In addition, since the thermosetting resin impregnated into the continuous fiber has a low viscosity, it is not possible to obtain a fiber-reinforced synthetic resin skin layer with a uniform thickness, and it is impossible to obtain uniform mechanical strength in the composite foam. Met.

As a method for solving this problem, a fiber-reinforced thermoplastic resin sheet is continuously shaped into a hollow body, and a foamable thermoplastic resin composition is supplied into the hollow body to cause foaming, and a foaming pressure is applied. A method of shaping into a desired cross-sectional shape can be considered. However, this manufacturing method has a drawback that mechanical strength such as bending strength and compressive strength is weak although the foaming core layer can be made to have a high foaming ratio to reduce the weight. An object of the present invention is to provide a method for producing a fiber-reinforced thermoplastic resin foam which is relatively lightweight and has excellent mechanical strength.

[0005]

A method for producing a fiber-reinforced thermoplastic resin foam according to the present invention comprises a step of continuously shaping a fiber-reinforced thermoplastic resin sheet into a hollow body,
A step of continuously supplying a foamable thermoplastic resin composition comprising a thermoplastic resin and a foaming agent inside the hollow body while foaming, and the foamable thermoplastic resin composition while cooling the hollow body from the outside. And a step of shaping the hollow body along the regulation member by a foaming pressure at the time of foaming into a predetermined cross-sectional shape.

The method for producing a fiber-reinforced thermoplastic resin foam according to the second aspect of the present invention comprises a step of continuously shaping the fiber-reinforced thermoplastic resin sheet into a hollow body, and a thermoplastic resin inside the hollow body. A step of continuously supplying a foamable thermoplastic resin composition comprising a foaming agent, and foaming the foamable thermoplastic resin composition while cooling the hollow body from the outside, and regulating the hollow body by the foaming pressure. And a step of shaping the member into a predetermined cross-sectional shape.

A method for producing a fiber-reinforced thermoplastic resin foam according to the invention of claim 3 comprises a composite sheet having a fiber-reinforced thermoplastic resin layer and a foamable thermoplastic resin composition layer comprising a thermoplastic resin and a foaming agent, A step of continuously forming a hollow body with the fiber-reinforced thermoplastic resin layer on the outer surface, and foaming the expandable thermoplastic resin composition while cooling the hollow body from the outside, and the foaming pressure thereof. And a step of shaping the hollow body into a predetermined cross-sectional shape along with the regulating member.

Specific examples of the thermoplastic resin used for the fiber reinforced thermoplastic resin sheet include polyethylene, polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate,
Polyvinylidene fluoride, polyphenylene sulfide,
Examples thereof include polyphenylene oxide, polyether sulfone, polyether ether ketone, polymethyl methacrylate and the like. Further, a copolymer composed of the above-mentioned thermoplastic resin monomer, a graft resin or a blend resin of the above-mentioned thermoplastic resin, for example, an ethylene-vinyl chloride copolymer, a vinyl acetate-ethylene copolymer, a vinyl acetate-vinyl chloride. Copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, silane-modified polyethylene, acrylic acid-modified polypropylene, maleic acid-modified polyethylene and the like can also be used. Further, a thermoplastic elastomer or a crosslinked thermoplastic resin can also be used. Considering the molding temperature, 120-25
Polyethylene, polypropylene, polyvinyl chloride, polystyrene, chlorinated polyvinyl chloride, ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl chloride copolymer, acrylonitrile, which can be molded at 0 ° C. -Butadiene-styrene copolymer and acrylonitrile-styrene copolymer are preferable.

The thermoplastic resin used in the present invention may be used alone or in combination, and may be an organic material such as dibutyltin maleate polymer or dibutyltin bis (monoalkylmalate) as long as the physical properties are not impaired. Tin malate type, dibutyl tin laurate, organic tin laurate type such as monobutyl tin fatty acid salt, dioctyl tin sulfide, dibutyl tin 3
Organic tin mercapto type such as mercaptopionate, lead salt such as tribasic lead sulfate, basic lead phosphite, heat stabilizer such as metal soap such as calcium stearate and lead stearate, fatty acid ester wax, low molecular weight polyethylene wax Lubricants such as metal soaps, polyhydric alcohols, aliphatic alcohols and fatty acid aminos, processing aids such as acrylic resins and olefin resins, dibutyl phthalate,
Plasticizers such as dioctyl phthalate, antioxidants, UV absorbers, modifiers, additives such as colorants, and fillers such as talc, mica, calcium carbonate, wood powder, fiber-reinforced thermosetting resin ground powder. May be blended.

As the fibers used in the fiber-reinforced thermoplastic resin sheet, those which are not melt-softened or carbonized by the heat applied in the manufacturing process of the present invention can be used.
Specifically, glass fiber; carbon fiber; silicon / titanium / carbon fiber; boron fiber; metal fiber; aramid fiber, polyester fiber, organic fiber such as polyamide fiber, silk,
Natural fibers such as cotton and hemp can be mentioned, but strength,
Considering cost, glass fiber and carbon fiber are preferable. The diameter of the filament is 1 to 100 μm, especially 3 to 2
3 μm is preferable. When the diameter of the filament is smaller than 1 μm, the reinforcing effect of the fiber is small. Also, 1
When it is larger than 00 μm, the contact area between the thermoplastic resin and the fiber is smaller than that of the same kind and the same diameter of the small diameter fiber, so that the adhesion between the thermoplastic resin and the fiber is lowered,
The reinforcing effect of fibers is small.

The fiber content in the fiber-reinforced thermoplastic resin sheet is preferably in the range of 5 to 80% by weight, particularly 10 to 50% by weight. If the content is less than 5% by weight, the reinforcing effect is small, and if the content is more than 80% by weight, the amount of resin that binds the fibers to each other is small, and thus the fiber-reinforced thermoplastic resin foam has a weak fiber-reinforced thermoplastic skin layer. Become.

The fibers in the fiber reinforced thermoplastic resin sheet are
Those having a diameter of 3 mm or more are used, preferably 10 mm or more, and more preferably continuous fibers. The longer the fiber, the stronger the strength of the fiber-reinforced thermoplastic resin foam, and if the fiber length is shorter than 3 mm, the reinforcing effect is small. Further, in the case of shaping the fiber-reinforced thermoplastic resin hollow body while spreading it in the circumferential direction, in order to improve the spreadability in the circumferential direction, the fibers, particularly continuous fibers, are oriented so as to be in the longitudinal direction of the product. It is preferable that

The fiber-reinforced thermoplastic resin sheet is shaped into a hollow body and then shaped into a predetermined cross-sectional shape by foaming pressure. At that time, the cross-sectional shape is regulated by a regulation member such as a mold from the outside. Therefore, a frictional force is generated between the regulating member and the surface of the hollow body. Therefore, in order to prevent cutting and breakage of the hollow body that occurs during drawing and shaping while resisting frictional force, the fiber form included in this is such that continuous fibers are aligned in the longitudinal direction of the hollow body. It is preferable that the When the fiber-reinforced thermoplastic resin sheets are laminated and used in a plurality of layers, it is sufficient if at least one of the fibers has the above-mentioned form.

The fiber-reinforced thermoplastic resin sheet according to the first and second aspects of the invention is manufactured, for example, as follows. That is, after opening the reinforcing fiber bundle and aligning in one direction, superimposing a thermoplastic resin film on these and passing them between heating pinch rolls, allowing the molten thermoplastic resin to penetrate between the reinforcing fibers, and then The fiber-reinforced thermoplastic resin sheet is obtained by passing between cooling rolls and cooling.

The fiber-reinforced thermoplastic resin sheet can also be manufactured in the following manner. That is, the continuous reinforcing fiber bundle aligned in one direction, after passing through a fluidized bed of the powdery thermoplastic resin and opening the fiber-shaped thermoplastic resin to the reinforcing fiber while opening, The fiber-reinforced thermoplastic resin sheet is obtained by passing between heating pinch rolls, melting the thermoplastic resin to penetrate between the reinforcing fibers, and then passing between cooling rolls for cooling.

In order to produce a fiber-reinforced thermoplastic resin sheet in which fibers are randomly arranged, the reinforcing fibers to which the powdery thermoplastic resin obtained as described above is attached are finely cut with a rotary cutter. A fiber-reinforced thermoplastic resin sheet is obtained by accumulating chopped and chopped reinforcing fibers, pressurizing them under heating to impregnate the chopped reinforcing fibers with a thermoplastic resin, and then cooling.

The thickness of the fiber reinforced thermoplastic resin sheet is
0.1-10 mm is preferable and 0.3-2 mm is more preferable. If the thickness is thinner than 0.1 mm, the strength of the fiber-reinforced thermoplastic resin sheet is weak, and if it is thicker than 10 mm, shaping into a hollow body becomes difficult.

The thermoplastic resin used in the expandable thermoplastic resin composition may be the same as the thermoplastic resin used in the fiber reinforced thermoplastic resin sheet, but it is used in the fiber reinforced thermoplastic resin sheet. The use of a thermoplastic resin capable of heat fusion with the thermoplastic resin
The bending strength of the obtained fiber-reinforced thermoplastic resin foam is improved, which is preferable. Specifically, it is preferable to use thermoplastic resins of the same type (thermoplastic resins polymerized from the same monomer). As combinations when using different types of thermoplastic resins, for example, polyethylene and polypropylene, polyethylene and vinyl acetate-ethylene copolymer, polyethylene and chlorinated polyethylene, polystyrene and acrylonitrile-butadiene-styrene copolymer, polystyrene and polystyrene. Acrylonitrile-styrene copolymer, polyvinyl chloride and chlorinated polyvinyl chloride, polyvinyl chloride and ethylene-vinyl chloride copolymer, polyvinyl chloride and vinyl acetate-vinyl chloride copolymer, polyvinyl chloride and polymethyl methacrylate, Polyvinyl chloride and acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate and polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer and acrylonitrile-styrene copolymer, etc. It is below. Also, a combination of the thermoplastic resin and the same type of modified thermoplastic resin can be used. Examples thereof include polyethylene and silane-modified polyethylene, polyethylene and acrylic acid-modified polypropylene, polyethylene and maleic acid-modified polyethylene, and the like.

The foaming agent used in the expandable thermoplastic resin composition is supplied while foaming (claim 1
Invention), a decomposition-type foaming agent that chemically decomposes to generate gas, and a physical-type foaming agent that utilizes gasification of a volatile liquid can be used. Alternatively, while kneading the thermoplastic resin at a melting temperature or higher, a gas such as carbon dioxide or nitrogen may be injected under pressure to disperse the thermoplastic resin, and the pressure may be released for foaming.

When foaming after supply (inventions of claims 2 and 3), so-called foaming, in which a volatile liquid, carbon dioxide, nitrogen or the like is dissolved as a foaming agent in a decomposable foaming agent or a thermoplastic resin and dispersed. Beads can be used.

Specific examples of the decomposition type foaming agent include azodicarbonamide, azobisisobutyronitrile, N, N '.
-Dinitrosopentamethylenetetramine, pp'-oxybisbenzenesulfonyl hydrazide, barium azodicarboxylate, trihydrazinotriazine, p-toluenesulfonyl hydrazide, sodium bicarbonate, ammonium carbonate and the like. Specific examples of the physical type blowing agent include aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane, chlorinated aliphatic hydrocarbons such as methyl chloride and methylene dioxide, 1,1-dichloro-1-fluoroethane. , 2,2-dichloro-1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, and other chlorofluorocarbon gas. The amount of gas generated varies depending on the type of the foaming agent, so the amount to be blended must be adjusted appropriately, but it is preferably blended in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the blending amount of the foaming agent is too small, a foam cannot be obtained, and if the blending amount of the foaming agent is too large, the cells are broken and a dense cell cannot be obtained, resulting in the fiber-reinforced thermoplastic resin foaming. The bending strength of the body decreases. For example, when a 10-fold thermoplastic resin foam is produced using azodicarbonamide,
It is suitable to mix up to 7.5 parts by weight.

The expansion ratio of the foam layer formed from the expandable thermoplastic resin composition is appropriately selected depending on the strength and specific gravity required for the manufactured product, the type of the thermoplastic resin used, and the like. The expansion ratio in the vicinity of the fiber-reinforced thermoplastic resin skin layer is preferably 1.2 to 10 times. If the expansion ratio is less than 1.2 times, the effect of weight reduction is small, and if it is more than 10 times, the mechanical strength becomes weak. Further, the area other than the vicinity of the fiber-reinforced thermoplastic resin skin layer is preferably in the range of 2 to 30 times.
When the expansion ratio is less than 2 times, the lightness of the obtained fiber-reinforced thermoplastic resin foam is reduced, and when it is more than 30 times,
Not only the bending strength but also the compression strength is very weak.

The composite sheet according to the invention of claim 3 is manufactured, for example, as follows. That is, the foamable thermoplastic resin composition sheet previously produced on one side of the fiber-reinforced thermoplastic resin sheet obtained by the above method is heat-fused, or the one side of the fiber-reinforced thermoplastic resin sheet is unfoamed. A composite sheet is obtained by extruding the expandable thermoplastic resin composition into a sheet shape and laminating it.

The fiber-reinforced thermoplastic resin sheet may be a single layer or a plurality of layers. Further, in the case of the composite sheet, this may be a plurality of layers of either the fiber reinforced thermoplastic resin layer or the expandable thermoplastic resin composition layer.

In the present invention, the hollow body is formed by abutting or overlapping edges of one fiber-reinforced thermoplastic resin sheet or composite sheet, and a slight gap is formed between the edges. It is also included.

The fiber-reinforced thermoplastic resin sheet and the composite sheet may be shaped into a hollow body by only one sheet, or a plurality of sheets may be arranged so as to partially overlap each other in the width direction. You may do it.

As a method for shaping the fiber-reinforced thermoplastic resin sheet and the composite sheet into a hollow body, there is a method of gradually bending the sheet with a synthetic resin or metal shoe or the same roll. In order to prevent the sheet from cracking or tearing, it is preferable that the sheet is heated with a far infrared heater or a hot air blower to perform shaping while the thermoplastic resin is in a softened state. Furthermore, the sheet may be gradually bent and shaped into a hollow body by passing the sheet through a mold having a passage that is shaped into the hollow body.

Here, the softened state generally refers to a state in which the thermoplastic resin begins to deform and is heated to a temperature at which the mechanical properties deteriorate, and in the present invention, more specifically JIS
-The state in which the thermoplastic resin is heated to the Vicat softening temperature or higher measured according to K-7206.

When shaping the hollow body into a predetermined cross-sectional shape,
The hollow body may be wholly or partially extended in the circumferential direction. In such a case, cracking or thinning occurs in the hollow body, and a portion with reduced rigidity is formed in the fiber-reinforced thermoplastic resin skin layer of the obtained product. In order to prevent this, when using a fiber reinforced thermoplastic resin sheet, on the surface which becomes the outer surface or the inner surface of the hollow body, when using a composite sheet, on the surface which becomes the outer surface of the hollow body, stretchability ( You may laminate the thermoplastic resin layer excellent in spreadability.

In the invention of claim 1, when the expandable thermoplastic resin composition is continuously supplied while being foamed inside the shaped hollow body, the expandable thermoplastic resin composition is gas-generated in the extruder. The mixture is kneaded at a temperature or higher, the generated gas is dispersed in a thermoplastic resin, and the gas is extruded into the hollow body through an extrusion port whose temperature is adjusted to the melting temperature or higher of the foamable thermoplastic resin composition. Also, while kneading the thermoplastic resin in the extruder at a temperature higher than the melting temperature, gas such as carbon dioxide or nitrogen is injected under pressure to disperse it in the thermoplastic resin. It may be pushed out inside the body.

In the second aspect of the invention, as a method for continuously supplying the foamable thermoplastic resin into the hollow body,
A method of melting and kneading with an extruder at a melting temperature of a thermoplastic resin or more and a decomposition temperature of a foaming agent or less, and a method for extruding, or a sheet-shaped, pellet-shaped or rod-shaped thermoplastic resin composition or foamed beads containing a foaming agent produced in advance There is a method of continuously supplying the inside of the hollow body.

In the inventions of claims 2 and 3, as a method of foaming the expandable thermoplastic resin composition, a hollow body is inserted into a mold heated to a temperature higher than the foaming temperature of the foaming agent, or the same hollow There is a method of blowing hot air heated above the foaming temperature of the foaming agent into the inside of the body.

In the present invention, the "foaming temperature" means
In the case of a decomposition type foaming agent, it means the decomposition temperature, and in the case of a physical type foaming agent, it means the boiling point thereof.

In the present invention, when the hollow body is shaped by the foaming pressure, the hollow body is cooled from the outside. The "cooling" in the present invention constitutes a foamable thermoplastic resin composition. Cooling to below the softening point of the thermoplastic resin.

To cool the fiber-reinforced thermoplastic resin hollow body from the outside, for example, a method of passing it through a cooling water tank,
Examples thereof include a method of spraying water, a method of passing through a cooling mold, and a method of blowing cold air. At the time of this cooling, vacuuming or regulation of the outer peripheral surface using a mold or the like may be performed at the same time.

A method of shaping the fiber-reinforced thermoplastic resin hollow body into a predetermined cross-sectional shape is as follows: the hollow body is pressed against the inner surface of the mold by the foaming pressure generated by the foaming of the foamable thermoplastic resin composition and is passed. And a method of shaping while controlling the outer peripheral surface of the hollow body with a roll or a shoe. When shaping the hollow body with a mold, vacuuming from the outside of the hollow body, or by providing an air supply pipe inside the regulating member, a regulating member structure capable of supplying gas into the hollow body, Shape formation by foaming pressure may be assisted by compressed air from the inside of the hollow body.

In the present invention, the foaming pressure includes not only the foaming pressure generated from the foamable thermoplastic resin composition but also the following pressures. That is, if the foaming pressure of the expandable thermoplastic resin composition alone does not provide sufficient pressure to press the hollow body against the regulating member, a separate pressure is applied from inside the hollow body or a vacuum pressure is applied from outside the hollow body. In this case, the pressure is added to the foaming pressure of the expandable thermoplastic resin composition.

In the present invention, the shape of the hollow body is not particularly limited, and the cross-sectional shape of the hollow body and the cross-sectional shape of the fiber-reinforced thermoplastic resin foam may be the same or different. The hollow body and the fiber-reinforced thermoplastic resin foam may be shaped such that the outer peripheral lengths thereof are equal to each other, or the hollow body may be shaped while being spread in the circumferential direction. When the hollow body is expanded and shaped, the expandable thermoplastic resin composition and the thermoplastic resin forming the hollow body must have a softening temperature or higher until the final shape is obtained.

The fiber-reinforced thermoplastic resin skin layer of the product preferably has a thickness of 0.1 mm or more. 0.1 mm
When it is less than the above range, the strength of the fiber-reinforced thermoplastic resin foam becomes weak and the hollow body may be broken during molding.

Finally, an example of an apparatus used for producing the fiber-reinforced thermoplastic resin foam according to the present invention will be described below with reference to FIGS. In the following description,
"Front" refers to the right side of FIG. The fiber reinforced thermoplastic resin foam manufacturing equipment is equipped with a rewind roll (1) and a fiber reinforced thermoplastic resin sheet feeding machine, which is arranged in front of it and is connected to an extruder (2) on one side. Extrusion Mold (3)
And a cooling shaping die (4) placed in a continuous manner in front of the extrusion die (3) and a take-up machine (5) placed in front of the cooling shaping die (4). I have it.

The extrusion die (3) usually has a U-shaped inlet and an annular outlet, and is deformed into a U-shape from the inlet to the outlet and inserted into the extrusion die (3). A passage (6) is formed so that both edges of the fiber-reinforced thermoplastic resin sheet (A1) are gradually brought close to each other, and finally both edges are butted or overlapped to form a hollow body. The extruder (2) is connected to the inner core (7) of the extrusion die (3) at a position before the sheet (A1) becomes a completely hollow body. The inner core (7) is provided with a resin passageway (8) having an annular cross section from this connecting portion to near the front end of the extrusion die (3).
Becomes a completely hollow body and tapers in front of the extrusion die (3) to form an annular extrusion port (9). Then, the expandable thermoplastic resin composition is extruded from the extrusion port (9) to the inner surface side of the hollow body (A2). At the center of the inner core (7), there is a hot air supply passage (10) that penetrates from the rear end to the front end.
A hot air conduit connected to a heating device (not shown) is connected to the rear end of (0).

The inner surface of the cooling shaping die (4) matches the outlet shape of the extrusion die (3) on the inlet side, but has a desired cross-sectional shape on the outlet side. The inner surface of the mold changes from the inlet shape to the outlet shape from the inlet to the outlet. The temperature of the cooling shaping die (4) can be controlled.

[0043]

According to the present invention, the foamable thermoplastic resin composition is foamed inside while cooling the fiber-reinforced thermoplastic resin hollow body from the outside, and the foaming pressure when the foamable thermoplastic resin composition is foamed. Since the hollow body is shaped into a predetermined cross-sectional shape along with the regulating member, the expandable thermoplastic resin composition in the vicinity of the hollow body is cooled before sufficiently high foaming, and A low-foaming thermoplastic resin layer having rigidity is formed. Then, the remaining expandable thermoplastic resin composition is foamed only toward the inside of the hollow body, and a high expandable thermoplastic resin layer that contributes to lightness is formed inside the low expandable thermoplastic resin layer. Sent.

A composite sheet having a fiber reinforced thermoplastic resin layer and a foamable thermoplastic resin composition layer is continuously shaped into a hollow body so that the fiber reinforced thermoplastic resin layer is the outer surface, and then In the invention according to claim 3 in which the foamable thermoplastic resin composition on the inside is foamed, gas generated from the foamable thermoplastic resin composition enters the interface between the fiber-reinforced thermoplastic resin skin layer and the thermoplastic resin foam core layer. However, the generation of voids can be prevented.

[0045]

EXAMPLES Examples of the present invention will be described in comparison with comparative examples. Example 1 Four continuous reinforcing fiber bundles aligned in one direction are passed through a fluidized bed of powdery thermoplastic resin to open the fibers, and the powdery thermoplastic resin is adhered to the reinforcing fiber bundle to form a strip shape. After doing 2
10 kg / cm ² between pinch rolls heated to 20 ° C
At a temperature of 0.4 mm and a width of 100 m by allowing the thermoplastic resin to melt and infiltrating between the reinforcing fibers, and then passing between cooling pinch rolls to cool.
A fiber-reinforced thermoplastic resin sheet having m and a fiber content of 23.3% by weight was obtained.

A fiber-reinforced thermoplastic resin foam is manufactured using the apparatus shown in FIGS. 1 and 2. First, the above-mentioned fiber-reinforced thermoplastic resin sheet (A1) is transferred to a feeding machine, and then the feeding machine. Insert the fiber reinforced thermoplastic resin sheet (A1) unwound from the unwinding roll (1) of the above into the extrusion die (3) whose temperature is controlled to 200 ° C, and continuously in the die (3). A hollow body (A2) with a perfect circular cross section is formed by shaping it into a hollow shape, and the shaped hollow body (A2) is introduced into a cooling shaping die (4) whose temperature is controlled at 20 ° C While cooling from
Extrusion die inside the hollow body (A2) that is passing through the cooling shaping die (4)
From the extrusion port (9) of the resin passageway (8) of (3), the foamable thermoplastic resin composition is continuously extruded while being foamed and supplied,
Cooling and shaping mold that is a regulating member for a hollow body that is in a softened state due to foaming pressure when the expandable thermoplastic resin composition foams
According to (4), the circular cross section is shaped into a square with a predetermined cross-sectional shape, and the thermoplastic resin foam core layer (B) and the fiber-reinforced thermoplastic resin skin layer (A3 A fiber-reinforced thermoplastic resin foam (C) having a square cross section with (1) and (2) was obtained (see FIG. 3).

In the thermoplastic resin foam core layer (B), the portion near the fiber-reinforced thermoplastic resin skin layer (A3) had a low expansion ratio, and the remaining portion had a high expansion ratio.

In this example, the continuous reinforcing fibers were glass fibers (Nitto Spinning Glass Roving, 4400 g).
/ Km, fiber diameter 23 μm), as the powdery thermoplastic resin, polyvinyl chloride compounded as shown in Table 1, and as the foamable thermoplastic resin, polyvinyl chloride compounded as shown in Table 2. Were used respectively. The blending was performed using a super mixer until the resin temperature reached 100 degrees.

[0049]

[Table 1]

[0050]

[Table 2]

Example 2 The adjusting temperature of the extrusion die was set to 170 ° C., the expandable thermoplastic resin composition was extruded from the extrusion opening of the resin passage of the extrusion die without foaming, and the hot air supply passage (10 In the same manner as in Example 1 except that the expandable thermoplastic resin composition was foamed by blowing hot air of 250 ° C. into the hollow body (A2) at a rate of 2 kg / cm ² A resin foam was obtained.

Example 3 Instead of the fiber reinforced thermoplastic resin sheet of Example 1, a composite sheet having a fiber reinforced thermoplastic resin layer and a foamable thermoplastic resin composition layer was used, and the same composite sheet was used as the fiber reinforced thermoplastic resin sheet. Forming into a hollow body so that the resin layer is the outer surface, and instead of the extruded expandable thermoplastic resin composition of Example 2, the expandable thermoplastic resin composition inside the shaped hollow body. When the composite sheet is foamed from the extruder, polyvinyl chloride having the composition shown in Table 2 is added from an extruder.
A sheet having a square cross section was obtained in the same manner as in Example 2 except that the sheet was passed through a sheet forming mold whose temperature was adjusted to 0 ° C. and was extruded without foaming and laminated on the fiber-reinforced thermoplastic resin sheet of Example 1. A fiber reinforced thermoplastic resin foam was obtained.

Comparative Example 1 Among the apparatus used in Example 1, the cooling shaping mold was removed, and instead of the cooling shaping mold, a mold gradually changed from a true circular inlet to a square outlet. A shaping mold having an inner surface and a cooling mold are arranged, and the fiber-reinforced thermoplastic resin sheet unwound from a rewinding roll of a feeding machine is inserted into an extrusion mold whose temperature is controlled to 200 ° C. It is made into a hollow body by continuously shaping it into a hollow body, and while guiding the shaped hollow body into the shaping die heated to 180 ° C, the hollow body passing through the shaping die The foamable thermoplastic resin composition is continuously extruded and supplied from the extrusion opening of the resin passage of the extrusion die into the body, and the hollow body in a softened state is pressed against the inner surface of the shaping die by the foaming pressure. Then, shape it into a square as shown in Fig. 3, and then pass it through the cooling mold. And then cooled by a take-up machine and having a thermoplastic resin foam core layer and a fiber-reinforced thermoplastic resin skin layer, one side is 25
A fiber reinforced thermoplastic resin foam having a square cross section of mm was obtained.

Comparative Example 2 The temperature of the extrusion die was 170 ° C. and the temperature of the shaping die was 220 ° C.
In the same manner as in Comparative Example 1 except that the expandable thermoplastic resin composition was extruded from the extrusion opening of the resin passage of the extrusion die without foaming and was extruded and then foamed, the fiber-reinforced thermoplastic resin having a square cross section was used. A resin foam was obtained.

Comparative Example 3 Using the composite sheet of Example 3, the composite sheet was shaped into a hollow body so that the fiber-reinforced thermoplastic resin layer was on the outer surface, and the extruded foaming heat of Comparative Example 2 was used. A fiber-reinforced thermoplastic resin foam having a square cross section was obtained in the same manner as in Comparative Example 2 except that the expandable thermoplastic resin composition inside the shaped hollow body was foamed instead of the plastic resin composition.

From the products of Examples and Comparative Examples, as shown in FIG. 3, rectangular parallelepiped measurement samples of 10 × 10 × 5 mm were respectively measured from the X portion near the fiber-reinforced thermoplastic resin skin layer and the central Y portion. It was cut out and the expansion ratio was measured, and the results are shown in Table 3. The foam layer in Table 3 refers to the entire foam core layer of the obtained fiber reinforced thermoplastic resin.

[0057]

[Table 3]

Next, each product was subjected to a three-point bending test, and the results are shown in Table 4. The three-point bending test condition is that the distance between fulcrums is 1200 mm and the test speed is 20 mm.
/ Min.

[0059]

[Table 4] From the above test results, it can be seen that the fiber-reinforced thermoplastic resin foam obtained by the production method of the present invention is excellent in bending strength.

[0060]

EFFECTS OF THE INVENTION According to the present invention, the mechanical strength is excellent because the vicinity of the fiber-reinforced thermoplastic resin skin layer of the thermoplastic resin foam core layer is relatively light and has a low expansion ratio. A fiber-reinforced thermoplastic resin foam can be obtained. In particular, according to the invention of claim 3, in addition to the above, a gas generated from the foamable resin composition penetrates into the interface between the fiber-reinforced thermoplastic resin skin layer and the thermoplastic resin foam core layer to form voids. Can be prevented from occurring,
It is possible to obtain a fiber-reinforced thermoplastic resin foam having excellent fusion bonding properties between the fiber-reinforced thermoplastic resin skin layer and the thermoplastic resin foam core layer.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an example of an apparatus for producing a fiber-reinforced thermoplastic resin foam used for carrying out the method of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG.

[Explanation of symbols]

 (2): Extruder (3): Extrusion die (4): Cooling and shaping die (A1): Fiber reinforced thermoplastic resin sheet (A2): Hollow body (A3): Fiber reinforced thermoplastic resin skin layer (B): Thermoplastic resin foam core layer (C): Fiber-reinforced thermoplastic resin foam

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B29K 105: 04 105: 06 B29L 9:00

Claims (3)

[Claims] 1. A step of continuously shaping a fiber-reinforced thermoplastic resin sheet into a hollow body, and continuously forming a foamable thermoplastic resin composition containing a thermoplastic resin and a foaming agent inside the hollow body. The step of supplying the hollow body and cooling the hollow body from the outside, the hollow body is shaped into a predetermined cross-sectional shape along the regulating member by the foaming pressure when the expandable thermoplastic resin composition foams. And a step of manufacturing a fiber-reinforced thermoplastic resin foam. 2. A step of continuously shaping a fiber-reinforced thermoplastic resin sheet into a hollow body, and continuously supplying a foamable thermoplastic resin composition containing a thermoplastic resin and a foaming agent inside the hollow body. And the step of foaming the expandable thermoplastic resin composition while cooling the hollow body from the outside, and shaping the hollow body by the foaming pressure along the regulating member into a predetermined cross-sectional shape. A method for producing a fiber-reinforced thermoplastic resin foam, which comprises: 3. A composite sheet having a fiber-reinforced thermoplastic resin layer and a foamable thermoplastic resin composition layer comprising a thermoplastic resin and a foaming agent is continuously prepared so that the fiber-reinforced thermoplastic resin layer is the outer surface. A step of shaping into a hollow body, while the hollow body is cooled from the outside, a foamable thermoplastic resin composition is foamed, and the foaming pressure causes the hollow body to be aligned with a regulating member to have a predetermined cross-sectional shape. And a step of shaping the fiber-reinforced thermoplastic resin foam.