JPH08174698A - Manufacture of fiber-reinforced thermoplastic resin foam - Google Patents

Abstract

PURPOSE: To obtain a fiber-reinforced thermoplastic resin foam of desired sectional shape having a fiber-reinforced thermoplastic resin skin layer having a uniform thickness and uniform mechanical strength. 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 thermoplastic resin into the element A2 while foaming the foamable polyvinyl chloride made of foaming agent, substantially uniformly spreading the element in the circumferential direction by the foaming pressure, and deforming the spread element A3 while holding the outer peripheral length substantially constant, thereby shaping it to a predetermined sectional shape.

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 pultruded (Japanese Patent Laid-Open No. 4-33963).
(See Japanese Patent Publication No. 5).

[0003]

In the conventional molding method described above, it was necessary to prepare in advance a foamed molded article having an irregular cross-section, which 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, in this manufacturing method, when the cross-sectional shape of the fiber-reinforced thermoplastic resin hollow body and the cross-sectional shape of the fiber-reinforced thermoplastic resin foam, which is the product, are greatly different, the hollow body is partially greatly extended, However, there is a drawback in that the strength of the product varies due to the fact that the product becomes thin or breaks. As a method of eliminating this drawback, when the fiber-reinforced thermoplastic resin sheet is shaped into a hollow body, it is shaped into a product shape in advance, and the foamable thermoplastic resin composition is supplied inside the hollow body of the product shape. However, it is difficult to shape it into a complicated cross-sectional shape, and even if it can be shaped, the expandable thermoplastic resin composition will have a hollow body with a complicated cross-sectional shape. Is difficult to supply.

The object of the present invention is to produce a fiber-reinforced thermoplastic resin foam having a fiber-reinforced thermoplastic resin skin layer having a uniform thickness and thus having a uniform mechanical strength and a desired cross-sectional shape. To provide a method.

[0006]

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,
Continuously supplying while foaming a foamable thermoplastic resin composition comprising a thermoplastic resin and a foaming agent inside the hollow body,
A step of controlling the hollow body by the foaming pressure to spread it substantially uniformly in the circumferential direction, and deforming the expanded hollow body while keeping the outer peripheral length substantially constant to shape it into a predetermined cross-sectional shape. And a step of performing.

The method for producing a fiber-reinforced thermoplastic resin foam according to the second aspect of the present invention comprises a step of continuously forming a 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, foaming the foamable thermoplastic resin composition, and spreading the foam substantially uniformly in the circumferential direction while controlling the hollow body by the foaming pressure. And a step of deforming the expanded hollow body while keeping the outer peripheral length thereof substantially constant and shaping it into a predetermined cross-sectional shape.

A method for producing a fiber-reinforced thermoplastic resin foam according to the present invention is a fiber-reinforced thermoplastic resin layer,
A step of continuously shaping a composite sheet having a foamable thermoplastic resin composition layer composed of a thermoplastic resin and a foaming agent into a hollow body so that the fiber-reinforced thermoplastic resin layer is the outer surface; A step of foaming a thermoplastic resin composition and controlling the hollow body by the foaming pressure to spread the hollow body substantially uniformly in the circumferential direction, and deforming the expanded hollow body while keeping the outer peripheral length substantially constant. And a step of shaping into a predetermined cross-sectional shape.

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 and 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 order to uniformly extend the hollow body in the circumferential direction while controlling the hollow body, it is preferable that the fibers, particularly the continuous fibers, are oriented in the longitudinal direction of the hollow body.

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 core layer formed from the expandable thermoplastic resin composition is required strength and specific gravity,
It is appropriately selected depending on the type of thermoplastic resin used, but is preferably 1.2 to 20 times, and particularly preferably 2 to 10 times. When the expansion ratio is less than 1.2 times, the lightness due to foaming is reduced, and when the expansion ratio exceeds 20 times, the strength is reduced.

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 means JIS-K-720.
A state in which the thermoplastic resin is heated to a temperature equal to or higher than the Vicat softening temperature measured according to 6.

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, and it is hollow from the extrusion port whose temperature is adjusted to the melting temperature of the thermoplastic resin or higher. It may be pushed out inside the body.

In the invention of claim 2, as a method for continuously supplying the foamable thermoplastic resin into the hollow body,
A method of melt-kneading and extruding 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 sheet-shaped, pellet-shaped or rod-shaped thermoplastic resin composition or foamed beads containing a foaming agent produced in advance. The method of continuously supplying the inside of the hollow body can be mentioned.

In the inventions of claims 2 and 3, as a method of foaming the expandable thermoplastic resin composition, a method of inserting a hollow body 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 the decomposition temperature in the case of a thermal decomposition type foaming agent, and the boiling point in the case of a physical type foaming agent.

When the hollow body is evenly spread in the circumferential direction, the thermoplastic resin forming the fiber reinforced thermoplastic resin sheet may be in a softened state, and the cross-sectional shape of the hollow body after spreading Is preferably a circle, an ellipse, or a polygon, and a perfect circle is most preferable. In the case of a polygon, it is preferable that the number of corners is large.

As a method for uniformly spreading the hollow body in the circumferential direction, the hollow body is inserted into a regulation mold in which the inner surface of the mold spreads forward, and the foamable thermoplastic resin composition is foamed. A method in which the hollow body is pressed against the inner surface of the mold so as to pass therethrough, or the outer peripheral surface of the hollow body is surrounded by rolls or shoes while heating the periphery of the hollow body to foam the expandable thermoplastic resin composition. There is a method of spreading while controlling so as to uniformly spread in the direction. When expanding the hollow body in the regulation mold, when vacuuming from the outside of the hollow body or when separately applying pressure to the inside of the hollow body, provide air supply piping inside the regulation member and A restricting member structure that allows gas to be supplied to the inside may be used, and the expansion of the hollow body may be assisted by compressed air from the inside.

As a method for making the hollow body soft,
There is a method of heating a mold or a jig that regulates the outer shape of the hollow body with a heater to a temperature not lower than the softening temperature of the thermoplastic resin. In addition, a method of heating with the heat of the expandable thermoplastic resin composition itself supplied into the hollow body is also included.

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.

The degree of circumferential spreading of the hollow body depends on the type of thermoplastic resin, the wall thickness of the hollow body, and the temperature at the time of spreading, but the thickness of the fiber-reinforced thermoplastic resin skin layer is
It is preferable that the thickness is 0.1 mm or more. 0.
When it is less than 1 mm, the strength becomes weak and the fiber-reinforced thermoplastic resin hollow body may be broken when the final cross-sectional shape is formed.

In the present invention, the expanded hollow body is deformed while keeping its outer peripheral length substantially constant and shaped into a predetermined cross-sectional shape. At this time, the method of shaping into a predetermined cross-sectional shape is not particularly limited as long as the outer peripheral length thereof is substantially constant. For example, the shape of the inlet is the same as the expanded hollow body, and the shape of the outlet is the predetermined cross-sectional shape. That is, a hollow body is inserted into a mold in which the inner surface shape of the mold gradually changes to an outlet shape, a method of shaping while controlling from the outside by the mold, or a roll or shoe instead of the mold. The shaping method used may be mentioned.

When shaping the expanded hollow body into a predetermined cross-sectional shape, it is necessary to keep the temperature above the softening temperature of the thermoplastic resin forming the hollow body. The method is not particularly limited, and examples thereof include a method in which the mold, roll, shoe, or the like has a heating function to heat the mold or the like.

Finally, an example of the apparatus used for producing the fiber-reinforced thermoplastic resin foam according to the present invention will be described below with reference to FIGS. 1 and 2. In the following description, “front” refers to the right side of FIG. 1. 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), the regulation die (4) continuously arranged in front of the extrusion die (3), and the shaping die (4) continuously arranged in front of the regulation die (4). 5), a cooling mold (6) continuously arranged in front of the shaping mold (5), and a take-up machine (7) arranged in front of the cooling mold (6). There is.

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 in which both edges of the fiber reinforced thermoplastic resin sheet (A1) are gradually brought close to each other and finally the both edges are abutted or overlapped to form a hollow body.
(8) is formed. The extruder (2) is located inside the core of the extrusion die (3) before the sheet (A1) becomes completely hollow.
It is linked to (9). The inner core (9) is provided with a circular resin passage (10) having a diameter of 5 mm from this connecting portion to the front end of the extrusion die (3). Then, the inner core (9) is provided with a hot air supply passage (11) penetrating from the rear end to the front end, and a hot air conduit connected to a heating device (not shown) is provided at the rear end of the hot air supply passage (11). It is connected.

The inner surface of the regulation die (4) is an extrusion die on the inlet side.
It has the same shape as the passage (8) of (3), but has a larger similar shape on the outlet side. The shape of the inner surface of the mold gradually changes from the entrance to the exit. That is, the inner surface of the mold has a tapered shape that widens forward. The inner surface of the shaping die (5) matches the size of the outlet shape of the regulation die (4) on the inlet side, but on the outlet side it has a predetermined shape, for example, a square as shown in FIG. ing. Then, the shape is gradually changed from the entrance to the exit so as to form the exit shape. The inner surface of the cooling die (6) matches the size of the outlet shape of the shaping die (5). The regulation mold (4) and the shaping mold (5) are equipped with a heater so that they can be heated to an appropriate temperature.

[0043]

According to the present invention, the expandable thermoplastic resin composition is foamed inside the fiber-reinforced thermoplastic resin shaped into a hollow body,
By controlling the foaming pressure to expand the hollow body substantially uniformly in the circumferential direction, and deforming the expanded hollow body while maintaining its outer peripheral length substantially constant to shape it into a predetermined cross-sectional shape. Therefore, the fiber-reinforced thermoplastic resin skin layer having a uniform thickness can be obtained, and the cross-sectional shape of the product can be desired.

A laminated 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 of claim 3 in which the foamable thermoplastic resin composition on the inside is foamed, gas generated from the foamable thermoplastic resin composition is present at the interface between the fiber-reinforced thermoplastic resin skin layer and the thermoplastic resin foam core layer. It is possible to prevent the entry of voids.

[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 a powdery thermoplastic resin to open the fibers, and the powdery thermoplastic resin is attached to the reinforcing fibers to form a band. After doing, 22
Pass through the pinch rolls heated to 0 ° C. while heating under pressure at 10 kg / cm ² , melt the thermoplastic resin and infiltrate between the reinforcing fibers, and then pass through the cooling pinch rolls to cool. , Thickness 0.4mm, width 100mm,
A fiber reinforced thermoplastic resin sheet having 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 fiber-reinforced thermoplastic resin sheet (A1) is transferred to a feeding machine, and then,
Insert the fiber reinforced thermoplastic resin sheet (A1) unwound from the unwinding roll (1) of the feeding machine into the extrusion die (3) whose temperature is adjusted to 200 ° C, and continuously in the die (3). The shape of the hollow body (A2) with a cross-sectional diameter of 31.8 mm is achieved by shaping it into a hollow body (A2), and the shaped hollow body (A2) is heated to 180 ° C inside the regulation mold (4). Guide to and regulate molds (4)
Inside the hollow body (A2) passing through the inside, the resin passageway (1) of the extrusion die (3)
The foamable thermoplastic resin composition was continuously extruded and supplied from the extrusion port of (0) while being foamed, and the hollow body (A2) in a softened state was expanded toward the front of the regulation mold (4) by the foaming pressure. Push it against the tapered inner surface and gradually spread it evenly in the circumferential direction to form a true circle with a cross-sectional diameter of 47.7 mm. Then, expand the hollow body (A3) with a shaping mold at 180 ° C ( 5), deform it while keeping the outer circumference constant, and shape it into a square with a side of 37.5 mm, which has a predetermined cross-sectional shape, and then pass through the cooling mold (6), as shown in FIG. Let it cool, then take it off with a take-off machine (7) to form the thermoplastic resin foam core layer.
A fiber-reinforced thermoplastic resin foam (C) having a cross section of (B) and the fiber-reinforced thermoplastic resin skin layer (A4) was a square having a side of 37.5 mm was obtained.

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 in Table 1 is used, and as the foamable thermoplastic resin, polyvinyl chloride compounded in Table 2 is used. What was done was used respectively. The blending was performed using a super mixer until the resin temperature reached 100 degrees.

[0048]

[Table 1]

[0049]

[Table 2]

Example 2 Except that the controlling temperature of the extrusion die was 170 ° C., the expandable thermoplastic resin composition was extruded from the extrusion opening of the resin passage of the extrusion die without foaming, and foamed after extrusion. A fiber-reinforced thermoplastic resin foam having a square cross section was obtained in the same manner as in Example 1. 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 fiber-reinforced thermoplastic resin layer was used as the composite sheet. Forming into a hollow body so that it becomes the outer surface, and instead of the extruded expandable thermoplastic resin composition of Example 2, foam the expandable thermoplastic resin composition inside the formed hollow body. Then, the composite sheet was prepared by mixing the polyvinyl chloride compounded in Table 2 with 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 In the apparatus used in Example 1, except for the restriction mold and the shaping mold, 31.
A fiber-reinforced thermoplastic resin sheet in which a shaping mold having a mold inner surface gradually changed from a true circular inlet of 8 mm to a square outlet of 37.5 mm on a side is arranged and unwound from a rewinding roll of a feeding machine. Was inserted into an extrusion mold whose temperature was adjusted to 200 ° C., and a hollow body was formed by continuously forming a hollow body in the mold, and the shaped hollow body was heated to 180 ° C. The foamable thermoplastic resin composition is continuously extruded and fed from the extrusion port of the resin passage of the extrusion die into the hollow body passing through the shaping die while being guided into the shaping die and foamed. The softened hollow body is pressed against the inner surface of the shaping mold by pressure, shaped into a square as shown in FIG. 2, then passed through a cooling mold to cool, and then taken up by a take-up machine to generate heat. Has a plastic resin foam core layer and a fiber-reinforced thermoplastic resin skin layer That one side was obtained fiber-reinforced thermoplastic resin foam square cross section is 37.5 mm.

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 foamable 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.

The expansion ratio of the foam core layer in the products obtained in each of the examples and comparative examples was 3.5. When observing the end faces of the products of each example and each comparative example, the thickness of the fiber-reinforced thermoplastic resin skin layer was uniform in each of the examples, but varied in the comparative examples and thin. There was a part.

The thickness of the fiber-reinforced thermoplastic resin skin layer of each of the fiber-reinforced thermoplastic resin foams was measured at the following three points,
Table 3 shows the results. Point a: 0.5 mm from the apex Point b: central point on one side C point: central point between points a and b

[Table 3] From the above results, it is clear that the fiber-reinforced thermoplastic resin foam obtained by the production method of the present invention has no variation in the thickness of the fiber-reinforced thermoplastic resin skin layer. A 20-point fiber-reinforced thermoplastic resin foam obtained above was subjected to a 3-point bending test, and its average bending strength and its standard deviation are shown in Table 4.

The result of the three-point bending test is: distance between fulcrums: 120
The test speed was 0 mm and the test speed was 20 mm / min.

[Table 4] From the above results, it is clear that the fiber-reinforced thermoplastic resin foam obtained by the production method of the present invention has no variation in bending strength.

[0057]

According to the present invention, since a fiber-reinforced thermoplastic resin skin layer having a uniform thickness can be obtained, the produced fiber-reinforced resin foam has a uniform bending strength and a cross-sectional shape thereof. Can be as complex or as desired. In particular, according to the invention of claim 3, in addition to the above, 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, and voids are generated. Since it can be prevented from occurring, it is possible to obtain a fiber-reinforced thermoplastic resin foam having excellent fusion bonding property 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.

[Explanation of symbols]

 (3): Extrusion die (4): Controlling die (5): Forming die (6): Cooling die (A1): Fiber reinforced thermoplastic resin sheet (A2): Hollow body (A3): Expansion Expanded hollow body (A4): 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. Of the hollow body is controlled by the foaming pressure and is spread substantially uniformly in the circumferential direction, and the spread hollow body is deformed while keeping the outer circumference substantially constant. And a step of shaping the fiber-reinforced thermoplastic resin foam into a cross-sectional shape. 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, and substantially uniformly spreading in the circumferential direction while controlling the hollow body by the foaming pressure, and the expanded hollow body, the outer peripheral length A method for producing a fiber-reinforced thermoplastic resin foam, comprising the step of deforming while maintaining substantially constant and shaping into a predetermined cross-sectional shape. 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 with the fiber-reinforced thermoplastic resin layer being the outer surface. A step of forming a hollow body into a hollow body, a step of foaming the expandable thermoplastic resin composition, and a step of spreading the foamable thermoplastic resin composition substantially uniformly in the circumferential direction while regulating the hollow body by the foaming pressure; And a step of deforming the body into a predetermined cross-sectional shape while keeping the outer peripheral length of the body substantially constant, and manufacturing the fiber-reinforced thermoplastic resin foam.