JPH0584737A - Production of fiber reinforced resin laminated sheet for thermal molding - Google Patents

Abstract

PURPOSE:To produce the title sheet molded into a good molded product not generating the raising of a reinforcing fiber or interlaminar separation. CONSTITUTION:Powder of nylon 6 is bonded to glass roving at a ratio of 3:7 and this glass roving is cut into pieces of a length of 25mm to be accumulated. The accumulated layer is held between upper and lower endless belts and the resin is melted in a heating oven at 200 deg.C to form the core layer F5 with a thickness of 2mm of a fiber reinforced thermoplastic resin sheet. 100 pts.wt. of nylon 6 and 3 pts.wt. of triallyl isocyanurate are extruded in a molten state to mold the surface layers S1, S2 of a nylon 6 sheet with a thickness of 0.5mm. The surface layers S1, S2 are laminated to both surfaces of the core layer 75 and the whole is held between upper and lower endless belts 10, 11 to be passed though the nip of the rolls 18 in a heating oven held to 200 deg.C over 5min and the core layer and the surface layers are thermally welded to be cooled. This laminated sheet is transferred to an electron beam irradiation device and irradiated with electron beam of 6Mrad from both surfaces thereof to crosslink nylon 6 of the surface layers to produce an objective laminated sheet P with a thickness of 3mm.

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 resin laminated sheet for thermoforming, which is capable of forming a good molded product free of reinforced fiber protrusion and delamination.

[0002]

2. Description of the Related Art A fiber-reinforced resin sheet for thermoforming is formed into various shaped articles by press forming, drawing, vacuum forming or the like.

As a method for producing this kind of fiber-reinforced resin sheet for thermoforming, there is known a method in which thermoplastic resin sheets are laminated on and under a fiber-reinforced mat and the fiber-reinforced mat is impregnated with the resin by heating and pressurizing this. There is.

When a molded product is molded using the fiber-reinforced resin sheet for thermoforming obtained by such a method, the reinforcing fiber floats on the surface of the molded product, resulting in poor appearance. Further, if the reinforcing fibers float on the surface of the molded product, it also becomes an obstacle when painting or plating is applied to this surface.

In order to improve this, a surface layer having a skin of a thermoplastic resin having a higher melting point than that of the resin of the core layer is laminated on the core layer made of a fiber reinforced thermoplastic resin sheet, and this is laminated with the resin of the core layer. A method of producing a fiber-reinforced resin laminated sheet for thermoforming by heating and pressing at a temperature not lower than the melting point and not higher than the melting point of the resin of the surface skin to heat-weld the core layer and the surface layer has been proposed (Japanese Patent Laid-Open No. 58-188649). (See Japanese Patent Publication).

[0006]

However, in such a method for producing a fiber-reinforced resin laminated sheet for thermoforming, even if the reinforcing fibers can be prevented from rising, the thermal welding of the core layer and the surface layer is not sufficient. I can't say. In order to satisfactorily heat-weld the core layer and the surface layer, a laminate of breathable porous material such as non-woven fabric on the back surface of the high melting point thermoplastic resin skin is used. Laminating the material is troublesome and time-consuming.

The present invention is intended to solve such a problem, and an object of the present invention is to provide a fiber reinforced for thermoforming capable of forming a good molded product free of reinforced fiber protrusion and delamination. It is to provide a method for manufacturing a resin laminated sheet.

[0008]

To achieve the above object, one of the present inventions comprises a thermoplastic resin sheet containing a crosslinking agent on at least one side of a core layer made of a fiber reinforced thermoplastic resin sheet. A surface layer is laminated, and this is heated and pressed to heat-weld the core layer and the surface layer, and the thermoplastic resin of the surface layer is cross-linked by a cross-linking agent (claim 1
Invention).

Another aspect of the present invention is to laminate a surface layer made of a thermoplastic resin sheet containing a cross-linking agent on at least one side of a core layer made of a fiber reinforced thermoplastic resin sheet, and heat and pressurize this to form the core layer and the surface layer. Is heat-welded and then heated to crosslink the thermoplastic resin in the surface layer with a crosslinking agent (the invention of claim 2).

Still another aspect of the present invention is to laminate a surface layer made of a thermoplastic resin sheet on at least one surface of a core layer made of a fiber reinforced thermoplastic resin sheet, and heat and press this to heat-weld the core layer and the surface layer. After this, the surface layer side is irradiated with ionizing radiation to cross-link the surface layer thermoplastic resin (invention of claim 3).

In the present invention, the fiber-reinforced thermoplastic resin sheet used as the core layer is formed into a sheet by impregnating a thermoplastic resin into fiber mats such as chopped strand mats and continuous strand mats or roving fibers cut into short pieces. It was done. Fibers with a length of 3 mm or more have a reinforcing effect, and such reinforcing fibers generally have a thickness of 5 mm.
Those having a size of -100 μm are used.

As the reinforcing fiber, one that does not heat-melt in the manufacturing process is selected from inorganic fibers such as glass fiber, carbon fiber, metal fiber and ceramic fiber, and organic fiber such as aramid fiber, polyester fiber and polyamide fiber. It
Usually, glass fiber is used. In addition, in order to improve chemical affinity and interfacial adhesiveness, it is preferable that the surface of these reinforcing fibers is treated with a silane coupling agent or another adhesiveness improving agent before use.

The thermoplastic resin impregnated into these reinforcing fibers includes polyacrylonitrile, polyacetal,
Polyamide, polycarbonate, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, polybutadiene, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, polyvinyl acetate, polystyrene, etc. Used.

Further, copolymers, graft resins and modified resins containing the above resins as main components, such as acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene- Vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, ethylene-propylene copolymer, chlorinated polyethylene, chlorinated polypropylene,
Maleic acid-modified polystyrene, maleic acid-modified polyethylene, acrylic acid-modified polypropylene, silane-modified polypropylene, styrene-grafted polyphenylene ether, etc. may also be used.

These resins may be used alone or in combination of two or more having good compatibility. Further, if necessary, various known additives such as a filler, an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant and a pigment may be blended with these resins for use.

The fiber-reinforced thermoplastic resin sheet used as the core layer is obtained by, for example, adhering the thermoplastic resin powder to the roving fiber, cutting it into short sheets and accumulating them into a sheet, and heating and pressurizing this accumulated resin powder. Can be obtained by a method of melt impregnation. Further, a mat in which reinforcing fibers and thermoplastic resin fibers are mixed and woven can be obtained by a method of heating and pressing to melt and impregnate only the resin fibers. Further, it can be obtained by a method in which a thermoplastic resin sheet is laminated on the reinforcing fiber mat and the resin sheet is melt-impregnated by heating and pressurizing this.

In the present invention, the thermoplastic resin sheet used as the surface layer is a resin of the same type as the thermoplastic resin of the core layer or a different type of resin having good compatibility therewith, and is crosslinked with a crosslinking agent or ionizing radiation. The obtained thermoplastic resin is formed into a sheet. In this case, as the surface layer resin, a resin having the same melting point as the core layer resin or a resin having a melting point close to that of the core layer resin is generally used.

In the invention of claim 1 and the invention of claim 2, the thermoplastic resin sheet used as the surface layer contains a crosslinking agent. An organic peroxide is mainly used as the crosslinking agent. As this organic peroxide, one having a decomposition temperature higher than the sheet forming temperature is selected. As such an organic peroxide, dialkyl peroxide and peroxyketal are preferable, and examples thereof include dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and t-butylperoxide. Oxycumene, di-
t-butyl peroxide, 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexyne-3 and the like.

For example, when polyethylene or polypropylene is mixed with these organic peroxides and heated above the decomposition temperature of the organic peroxides, crosslinking proceeds. Depending on the thermoplastic resin used, crosslinking may not proceed with the organic peroxide. In this case, a carboxyl group, a vinyl group, a reactive functional group such as a hydroxyl group is introduced into the resin,
Further, crosslinking can be promoted by containing other crosslinking agents such as isocyanate and zinc, calcium, and magnesium metal compounds.

When the crosslinking does not proceed sufficiently, a crosslinking aid is used in combination to enhance the crosslinking efficiency. As the cross-linking aid, a polyfunctional organic compound having two or more unsaturated double bonds in the molecule such as triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane trimethacrylate, and divinylbenzene. Is used.

In the invention of claim 3, the thermoplastic resin sheet used as the surface layer does not contain the above-mentioned crosslinking agent. In this case, crosslinking of the resin proceeds by irradiating the surface layer side with ionizing radiation. Examples of ionizing radiation include electron beams, γ rays, and X rays, and electron beams are particularly preferable. Depending on the thermoplastic resin used, crosslinking may not proceed. In this case, the thermoplastic resin sheet contains a crosslinking aid similar to the above.

In the present invention, the surface layer is laminated on one surface or both surfaces of the core layer, and the core layer and the surface layer are heat-welded by heating and pressing the surface layer. As the heating and pressurizing means, a method of hot plate pressing, a method of passing between hot rolls, a method of passing between endless belts provided in a hot air circulation type or far infrared type heating furnace, and the like are adopted. If the heating temperature is at least a temperature at which the resin of the core layer or the surface layer is melted, the core layer and the surface layer are well heat-welded.

In this case, a thermoplastic resin sheet containing a cross-linking agent is used as the surface layer, and when the heating temperature is higher than the temperature (decomposition temperature) for activating the cross-linking agent, the core layer and the surface layer are heat-welded together. The cross-linking agent causes cross-linking of the resin in the surface layer (the invention of claim 1). When the heating temperature is equal to or lower than the temperature (decomposition temperature) for activating the cross-linking agent, the cross-linking agent does not cross-link the resin in the surface layer. In this case, after heat-sealing the core layer and the surface layer, the core layer is reheated to a temperature at which the crosslinking agent is activated (decomposition temperature) or higher, and the resin in the surface layer is crosslinked by the crosslinking agent (the invention of claim 2).

When a thermoplastic resin sheet containing no crosslinking agent is used as the surface layer, ionizing radiation is applied from the surface layer side to crosslink the resin of the surface layer (invention of claim 3).
When the surface layers are laminated on both sides of the core layer, ionizing radiation is applied from both sides. The irradiation dose is adjusted so that the resin of the core layer does not crosslink. When the crosslinking to the resin of the core layer progresses, the thermoformability of the obtained fiber-reinforced resin laminated sheet for thermoforming is deteriorated. It is desirable that the surface layer resin is uniformly crosslinked throughout the surface layer, but only the surface portion of the surface layer may be crosslinked.

In this way, the core layer and the surface layer are heat-welded, and the resin of the surface layer is crosslinked by the crosslinking agent or the ionizing radiation. When molding using a fiber-reinforced resin laminated sheet, it is preferable to crosslink at a temperature at which the resin of the core layer is sufficiently fluidized and to the extent that the resin of the surface layer has rubber elasticity, and the gel fraction is 20% by weight. It is desirable to crosslink as described above.

The method of the present invention will be described below with reference to the drawings. FIG. 2 is a side view showing an example of a method for producing the core layer used in the present invention. The roving fiber F1 is unwound from the rewinding roll 1 and guided to the fluid tank 2 through the guide 15. Thermoplastic resin powder R is supplied to the flow tank 2. Perforated plate 1 having a large number of ventilation holes at the bottom of the flow tank 2
4 are provided. Then, the gas such as air or nitrogen sent from the gas supply path is configured to be supplied into the flow tank 2 through the ventilation holes of the perforated plate 14 in the arrow direction. The resin powder R supplied into the fluidized tank 2 is in a fluidized state by the ejection of the gas, and a fluidized bed of the resin powder R is formed.

The roving fibers F1 pass through the fluidized bed and the resin powder R adheres to the roving fibers F1. Furthermore, the resin powder R excessively adhered to the roving fibers is removed by the pair of upper and lower scrubbers 3 through the guide 15, and the adhered amount is adjusted. It is preferable that the guide 15 in the fluid tank 2 has a chevron shape or a grooved shape in order to widen the width of the roving fiber F1 passing therethrough.

Roving fiber F2 to which resin powder R is attached
Is supplied between the cutter roll 6 and the rubber roll 7 while being taken up by the take-up drive rolls 4 and 5, and cut into a desired length. The cut roving fiber F3 is supplied between the pair of upper and lower endless belts 10 and 11.

The endless belts 10 and 11 are configured to continuously rotate in the same direction and at the same speed by driving the drive rolls 16 and 17 by a motor (not shown). The upper endless belt 10 and the lower endless belt 11 are formed with transfer portions 10a and 11a, respectively.
a is opposed vertically with a gap.

The transfer portion 11a of the lower endless belt 11 is extended longer than the transfer portion 10a of the upper endless belt 10 forward, and an extended transfer portion 11b is formed. Another endless belt may be arranged in front of the transfer portion 11a of the lower endless belt 11 without forming the extended transfer portion 11b. Such endless belts 10 and 11 are formed of high-strength and heat-resistant belts such as steel belts, stainless belts, and glass cloth reinforced Teflon belts.

Upper endless belt 10 and lower endless belt 11
A heating device 12 is arranged at each of the facing portions of the transfer portions 10a and 11a, and a cooling device 13 is arranged behind the heating device 12 respectively. Heating device 12
Consists of a hot air circulation type or far infrared type heating furnace,
Inside this heating furnace, a plurality of pairs of guide rolls 18 are arranged at positions corresponding to the upper and lower sides. The endless belts 10 and 11 pass through the heating furnace. The heating device 12 may be composed of a heating roll, and the heating roll may directly heat the belt while sandwiching the endless belts 10 and 11.

The cooling device 13 is composed of upper and lower cooling blowers, and a plurality of pairs of guide rolls 19 are arranged at positions corresponding to the upper and lower sides. The cooling device 13 may be configured by a water-cooled guide roll.

The cut roving fibers F3 are dropped and supplied onto the transfer portion 11b of the lower endless belt 11 and accumulated in a predetermined thickness. The accumulated roving fibers F4 are
Transfer section 10 for upper endless belt 10 and lower endless belt 11
The heating device 12 is transferred while being sandwiched between a and 11a.
Is supplied to. Here, the resin powder R is heated to an appropriate temperature of the melting point or higher, and the molten resin is impregnated between the filaments of the fiber.

Here, the gap between the upper and lower endless belts 10 and 11 is adjusted by the guide rolls 18, and the accumulated roving fibers F4 are pressed with an appropriate pressure in the thickness direction. This pressure causes the molten resin to flow, filling the voids between the monofilaments, so that the resin and the reinforcing fibers are integrated. Subsequently, the gap between the upper and lower endless belts 10 and 11 is adjusted by the guide roll 19 of the cooling device 13,
It is cooled to an appropriate temperature while being pressurized. Thus, the core layer F5 made of the fiber-reinforced thermoplastic resin sheet having a predetermined thickness
Is formed.

The core layer F5 manufactured in this manner is supplied between the pair of upper and lower endless belts 10 and 11 as shown in FIG. 1, for example, in a step continuous with the above manufacturing step or another independent step. To be done. This pair of upper and lower endless belts 10
2 and 11 have the same structure as in FIG.
The same reference numerals are given and the description of the device is omitted. In addition,
Behind the pair of upper and lower endless belts 10 and 11, either a heating device 20 or an electron beam irradiation device 21 is provided. In the figure, the heating device 20 or the electron beam irradiation device 21 is shown in the same view for convenience.

In FIG. 1, a core layer F5 made of a fiber reinforced thermoplastic resin sheet is a pair of upper and lower endless belts 10 and 1.
1 and the surface layers S1 and S made of a thermoplastic resin sheet containing a cross-linking agent from above and below.
2 is supplied and laminated above and below the core layer F5. This surface layer may be laminated only on one side above or below the core layer F5 without being laminated above and below the core layer F5.

The surface layers S1 and S2 made of a thermoplastic resin sheet containing a cross-linking agent are prepared by blending the above-mentioned cross-linking agent with the above-mentioned thermoplastic resin, and heating this at a temperature at which the resin is melted by an extruder or calender roll. In addition, it is formed by kneading at a temperature (decomposition temperature) at which the cross-linking agent is not activated and forming into a sheet.

The laminate of the core layer F5 and the surface layers S1 and S2 is
Transfer section 10 for upper endless belt 10 and lower endless belt 11
The heating device 1 is transferred while being sandwiched between a and 11a.
2 and is heated and pressurized to an appropriate temperature above the melting point of the resin constituting the core layer or the surface layer and above the temperature (decomposition temperature) at which the crosslinking agent is activated. As a result, the core layer F5 and the surface layers S1 and S2 are heat-welded, and the surface layers S1 and S
Two resins are crosslinked. Then, it is transferred while being sandwiched between the guide rolls 19 of the cooling device 13 and cooled to an appropriate temperature. Thus, the fiber-reinforced resin laminated sheet P for thermoforming having a predetermined thickness is manufactured.

A temperature (decomposition temperature) at which the laminate of the core layer F5 and the surface layers S1 and S2 is higher than the melting point of the resin forming the core layer F5 or the surface layer and the crosslinking agent is not activated in the heating device 12. When heated and pressed below, the core layer F5 and the surface layers S1 and S2 are heat-welded, and the resins of the surface layers S1 and S2 are not crosslinked. In this case, the temperature is subsequently transferred into the heating device 20 where the cross-linking agent is activated (decomposition temperature).
The resin of the surface layers S1 and S2 is cross-linked by this, and then cooled. Thus, the fiber-reinforced resin laminated sheet P for thermoforming having a predetermined thickness is manufactured.

When the surface layers S1 and S2 made of a thermoplastic resin sheet containing no crosslinking agent are used, the core layer F5 is used.
The laminated body of the surface layers S1 and S2 is supplied to the heating device 12 and heated and pressurized to an appropriate temperature above the melting point of the resin forming the core layer or the surface layer. Thereby, the core layer F5 and the surface layers S1 and S2 are heat-welded. Then, it is transferred while being sandwiched between the guide rolls 19 of the cooling device 13 and cooled to an appropriate temperature. Subsequently, it is transferred to the electron beam irradiation device 21, where an appropriate dose of electron beam is irradiated from both sides thereof, whereby the resins of the surface layers S1 and S2 are crosslinked. Thus, the fiber-reinforced resin laminated sheet P for thermoforming having a predetermined thickness is manufactured.

The method for producing the fiber-reinforced resin laminated sheet for thermoforming of the present invention is not limited to the above method. For example, by a pressing method using a pressing machine, a core layer made of a fiber reinforced thermoplastic resin sheet is formed, and a surface layer made of a thermoplastic resin sheet containing a crosslinking agent, or a thermoplastic resin sheet not containing a crosslinking agent is formed. By laminating the surface layer formed by heat-welding the core layer and the surface layer under heat and pressure by a press, and then heating this, or by irradiating ionizing radiation, by crosslinking the resin constituting the surface layer,
The fiber-reinforced resin laminated sheet for thermoforming of the present invention can be manufactured.

The fiber-reinforced resin laminated sheet for thermoforming obtained by the method of the present invention is heated and softened by a known heating means such as hot air heating or electric heating, and vacuum forming, drawing forming,
By various known thermoforming methods such as press molding, various product shapes are formed.

[0043]

According to the method of the present invention, the core layer made of the fiber reinforced thermoplastic resin sheet and the surface layer made of the thermoplastic resin sheet are made of resins having the same or similar melting points to each other. This makes it possible to firmly weld the core layer and the surface layer to each other with relatively low pressure.

The resin constituting the surface layer is crosslinked by the crosslinking agent or the ionizing radiation while the core layer and the surface layer are being heat-bonded or after the heat-bonding, so that the obtained fiber-reinforced resin laminated sheet for thermoforming is obtained. The surface layer has improved heat resistance and prevents the reinforcing fibers from floating on the surface of the molded product even if the surface layer is molded into various product shapes with relatively high pressure.

[0045]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Example 1 A needling mat having a thickness of 10 mm obtained by mixing and woven glass fibers having an average fiber diameter of about 25 μm and an average fiber length of about 50 at a weight ratio of 1: 4 was used at 180 ° C.
Press to melt the high-density polyethylene fiber to a thickness of 2
A core layer composed of mm fiber reinforced high density polyethylene sheet was formed.

Further, a mixture of 100 parts by weight of high-density polyethylene and 1.5 parts by weight of dicumyl peroxide was melt-extruded at 165 ° C. by using an extruder to obtain an uncrosslinked high-density polyethylene having a thickness of 0.5 mm. A surface layer made of a sheet was formed.

The surface layer was laminated on both sides of the core layer, and the laminate was placed in a flat plate mold having a thickness of 2.5 mm.
Surface pressure 10 kg / cm ² by hand press heated to 0 ℃
The core layer and the surface layer were heat-welded, and the high-density polyethylene in the surface layer was cross-linked. afterwards,
It was cooled to room temperature at a surface pressure of 10 kg / cm ² with a water-cooled press to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of 2.5 mm. The gel fraction of the surface layer of this sheet (using a xylene solvent) was about 60% by weight.

This thermoforming fiber-reinforced resin laminated sheet is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Example 2 A core layer (Radlite: Nippon Steel Co., Ltd.) made of a long glass fiber reinforced propylene sheet having a thickness of 4 mm was prepared.

100 parts by weight of polypropylene and 2,
A mixture of 1.5 parts by weight of 5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 and 3.0 parts by weight of trimethylolpropane trimethacrylate was melt extruded at 185 ° C. using an extruder. Then, a surface layer made of an uncrosslinked polypropylene sheet having a thickness of 0.5 mm was formed.

According to the method shown in FIG. 1, the surface layer is laminated on both surfaces of the core layer, and the laminated product is sandwiched between the upper and lower endless belts which are moving, while the hot air at 200 ° C. circulates. The core layer and the surface layer were heat-welded to pass through the inner rolls for 5 minutes to crosslink the polypropylene resin of the surface layer. Subsequently, it was cooled with a cooling blower to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of 5 mm. The gel fraction of the surface layer of this sheet (using xylene solvent) is about 3
It was 0% by weight.

The fiber-reinforced resin laminated sheet for thermoforming is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Example 3 A large number of glass rovings (fiber diameter 14 μm, 2200 TEX) were continuously passed through a fluidized bed of polyvinyl chloride resin powder by the method shown in FIG. After adhering, the excess resin powder was removed by a scrubber, adjusted so that the weight ratio of the resin powder and the reinforcing fiber was 7: 3, and supplied to the cutter roll.

This is cut by a cutter roll to a length of about 25 mm.
While being cut into pieces, they were dropped and supplied onto the lower endless belt transfer section and accumulated. While sandwiching this accumulated product between the upper and lower moving endless belts, the resin powder was melted by passing through a heating furnace in which hot air of 200 ° C. circulates. Subsequently, the laminate in which the resin powder was in a molten state was cooled by a cooling blower to manufacture a core layer made of a fiber-reinforced thermoplastic resin sheet having a thickness of 2 mm.

30 parts by weight of polyvinyl chloride, 20 parts by weight of chlorinated polyethylene, 2.0 parts by weight of dibutyltin maleate heat stabilizer, 1.5 parts by weight of dicumyl peroxide, 3.0 parts by weight of triallyl isocyanate. Was melt extruded at 170 ° C. using an extruder to give a thickness of 0.
A surface layer made of a mixed resin sheet of 5 mm of uncrosslinked polyvinyl chloride and chlorinated polyethylene was formed.

According to the method shown in FIG. 1, the surface layers are laminated on both surfaces of the core layer, and the laminate is sandwiched between the upper and lower endless belts which move, and a hot air circulated at 200 ° C. is circulated. The core layer and the surface layer were heat-welded by passing between the inner rolls for 5 minutes.

Then, cooling with a cooling blower,
Then, the surface polyvinyl chloride and chlorinated polyethylene were crosslinked and cooled through a heating furnace in which hot air of 200 ° C. was circulated to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of about 3 mm. The gel fraction of the surface layer of this sheet (using a methyl ethyl ketone solvent) was about 40% by weight.

The fiber-reinforced resin laminated sheet for thermoforming is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Example 4 A needling mat having a thickness of 10 mm was prepared by mixing and weaving glass fibers having an average fiber diameter of about 25 μm and an average fiber length of about 50 and high density polyethylene fibers at a weight ratio of 180 ° C.
Press to melt the high-density polyethylene fiber to a thickness of 2
A core layer composed of mm fiber reinforced high density polyethylene sheet was formed.

High-density polyethylene was melt-extruded at 165 ° C. using an extruder to form a surface layer made of a high-density polyethylene sheet having a thickness of 0.2 mm. The surface layer was laminated on both sides of the core layer, and the laminate was placed in a flat plate mold having a thickness of 2 mm and held for 5 minutes at a surface pressure of 10 kg / cm ² by a hand press heated to 180 ° C. The core layer and the surface layer were heat-welded. After that, a surface pressure of 10 with a water-cooled press
The laminate was cooled to room temperature at kg / cm ² to obtain a laminated sheet having a thickness of 2 mm.

Both sides of this laminated sheet were irradiated with an electron beam having an acceleration energy of 300 Kw and an irradiation dose of 4 Mrad to crosslink the high-density polyethylene in the surface layer to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of 5 mm. The gel fraction of the surface layer of this sheet (using a xylene solvent) was about 50% by weight.

The fiber-reinforced resin laminated sheet for thermoforming is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Example 5 A core layer (Radlite: Nippon Steel Co., Ltd.) made of a long glass fiber reinforced propylene sheet having a thickness of 4 mm was prepared.

A mixture of 100 parts by weight of polypropylene and 3.0 parts by weight of trimethylolpropane trimethacrylate was melt extruded at 185 ° C. using an extruder to form a surface layer made of a polypropylene sheet having a thickness of 0.5 mm. ..

According to the method shown in FIG. 1, the surface layer is laminated on both surfaces of the core layer, and the laminated body is sandwiched between the upper and lower endless belts to be moved, while the hot air at 200 ° C. is circulated. The core layer and the surface layer were heat-welded by passing between the inner rolls for 5 minutes. Subsequently, it was cooled with a cooling blower to obtain a laminated sheet having a thickness of 5 mm.

Both surfaces of this laminated sheet were irradiated with an electron beam having an acceleration energy of 500 Kw and an irradiation dose of 6 Mrad to cross-link the polypropylene of the surface layer to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of 5 mm. The gel fraction of the surface layer of this sheet (using a xylene solvent) was about 45% by weight.

The fiber-reinforced resin laminated sheet for thermoforming is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Example 6 A large number of glass rovings (fiber diameter 14 μm, 2200 TEX) were continuously passed through a fluidized bed of nylon 6 powder by the method shown in FIG. After that, the excess resin powder was removed by a scrubber, adjusted so that the weight ratio of the resin powder and the reinforcing fiber was 7: 3, and supplied to the cutter roll.

This is cut by a cutter roll to a length of about 25 mm.
While being cut into pieces, they were dropped and supplied onto the lower endless belt transfer section and accumulated. While sandwiching this accumulated product between the upper and lower moving endless belts, the resin powder was melted by passing through a heating furnace in which hot air of 200 ° C. circulates. Subsequently, the laminate in which the resin powder was in a molten state was cooled by a cooling blower to manufacture a core layer made of a fiber-reinforced thermoplastic resin sheet having a thickness of 2 mm.

A mixture of 100 parts by weight of nylon 6 and 3.0 parts by weight of triallyl isocyanurate was melt extruded at 250 ° C. using an extruder to form a surface layer made of a nylon 6 sheet having a thickness of 0.5 mm. Was molded.

According to the method shown in FIG. 1, the surface layers are laminated on both surfaces of the core layer, and the laminated product is sandwiched between the upper and lower endless belts which are moving, while the hot air at 200 ° C. circulates. The core layer and the surface layer were heat-welded by passing between the inner rolls for 5 minutes. Subsequently, it was cooled by a cooling blower to obtain a laminated sheet having a thickness of about 3 mm.

Both sides of this laminated sheet were irradiated with an electron beam having an acceleration energy of 500 Kw and an irradiation dose of 6 Mrad to cross-link the nylon 6 in the surface layer to obtain a fiber-reinforced resin laminated sheet for thermoforming having a thickness of 3 mm. The gel fraction of the surface layer of this sheet (using a tetrahydrofuran solvent) was about 40% by weight.

This thermoforming fiber-reinforced resin laminated sheet is
The core layer and the surface layer are firmly adhered to each other.
Heat to 0-210 ℃, air pressure 5 kg / cm ² ,
It was vacuum formed into a cup shape having a diameter of 12 cm and a depth of 5 cm.
In this case, the sheet could be well formed into a cup shape, had no peeling or voids between layers, and had no surface irregularities such as glass fiber protrusions, and had a good surface property.

Comparative Example 1 In Example 1, the surface layer made of an uncrosslinked high density polyethylene sheet was preheated to 180 ° C. to crosslink the high density polyethylene (the gel fraction of the sheet was about 60% by weight). Instead of the surface layer made of uncrosslinked high-density polyethylene sheet, the surface layer made of this crosslinked high-density polyethylene sheet was used. Other than that was performed like Example 1.

In this case, the sheet was able to be molded into a cup shape satisfactorily, and there was no surface irregularity such as glass fiber protrusion, and the surface property was good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

Comparative Example 2 In Example 2, a surface layer made of nylon 6 sheet was used instead of the surface layer made of uncrosslinked polypropylene sheet. Other than that was performed like Example 2.

In this case, the sheet can be well formed into a cup shape, and there is no surface irregularity such as glass fiber protrusion, and the surface property is good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

Comparative Example 3 In Example 3, instead of the surface layer made of a mixed resin sheet of uncrosslinked polyvinyl chloride and chlorinated polyethylene,
A surface layer made of a polyethylene terephthalate sheet was used. Other than that was performed like Example 3.

In this case, the sheet can be well formed into a cup shape, and there is no surface irregularity such as glass fiber protrusion, and the surface property is good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

Comparative Example 4 In Example 4, a surface layer made of nylon 6 sheet was used instead of the surface layer made of polypropylene sheet. Further, electron beam irradiation was not performed. Otherwise, Example 4
I went the same way.

In this case, the sheet can be well formed into a cup shape, and there is no surface irregularity such as glass fiber protrusions, and the surface property is good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

Comparative Example 5 In Example 5, a surface layer made of nylon 6 sheet was used instead of the surface layer made of uncrosslinked polypropylene sheet. Other than that was performed like Example 5.

In this case, the sheet can be well formed into a cup shape, and there is no surface irregularity such as glass fiber protrusions, and the surface property is good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

Comparative Example 6 In Example 6, the surface layer made of nylon 6 sheet was
A surface layer composed of a nylon 6 sheet which had been previously cross-linked by irradiating an electron beam was used (the gel fraction of the sheet was about 40% by weight)
Other than that was performed like Example 6.

In this case, the sheet can be well formed into a cup shape, and there is no surface irregularity such as glass fiber protrusion, and the surface property is good. However, although the sheets seem to have good interlayer adhesion at first glance, there were some voids between the surface layer and the core layer at the corners of the cup, and the interlayer adhesion was insufficient.

[0086]

As described above, in the method for producing a fiber-reinforced resin laminated sheet for thermoforming of the present invention, at least one surface of the core layer made of the fiber-reinforced thermoplastic resin sheet contains a crosslinking agent or contains a crosslinking agent. A surface layer composed of a thermoplastic resin sheet not containing is laminated, and the core layer and the surface layer are heat-welded by heating and pressing this, or after the core layer and the surface layer are heat-welded, a surface layer is formed by a crosslinking agent or ionizing radiation. The above-mentioned thermoplastic resin is cross-linked or the thermoplastic resin in the surface layer is cross-linked by ionizing radiation, whereby a good molded product can be formed without the embossing of the reinforcing fiber and delamination.

Further, according to the method of the present invention, as the surface layer, unlike the conventional method, the back surface of the skin of the high melting point thermoplastic resin laminated with the breathable porous material such as nonwoven fabric is not used. In addition, the surface layer and the core layer can be excellently heat-welded. Therefore, the method of this invention is
Compared with the conventional method, it has an advantage that a troublesome and troublesome process of laminating a porous material can be omitted.

[Brief description of drawings]

FIG. 1 is a side view showing an example of the method of the present invention.

FIG. 2 is a side view showing an example of a method for producing a core layer used in the present invention.

[Explanation of symbols]

F5 Core layer made of fiber reinforced thermoplastic resin sheet S1 Surface layer made of thermoplastic resin sheet containing or not containing crosslinking agent S2 Surface layer made of thermoplastic resin sheet containing or not containing crosslinking agent P Fiber reinforced resin for thermoforming Laminated sheet 10 Upper endless belt 11 Lower endless belt 12 Heating device 13 Cooling device 18 Pressure roll 19 Guide roll 20 Heating device 21 Electron beam irradiation device.

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Claims (3)

[Claims] 1. A surface layer made of a thermoplastic resin sheet containing a cross-linking agent is laminated on at least one surface of a core layer made of a fiber reinforced thermoplastic resin sheet, and this is heated and pressed to heat-weld the core layer and the surface layer. At the same time, a method for producing a fiber-reinforced resin laminated sheet for thermoforming, which comprises crosslinking the thermoplastic resin of the surface layer with a crosslinking agent. 2. A surface layer made of a thermoplastic resin sheet containing a cross-linking agent is laminated on at least one surface of a core layer made of a fiber reinforced thermoplastic resin sheet, and this is heated and pressed to heat-weld the core layer and the surface layer. After that, this is heated to crosslink the thermoplastic resin of the surface layer with a crosslinking agent, and a method for producing a fiber-reinforced resin laminated sheet for thermoforming. 3. A surface layer made of a thermoplastic resin sheet is laminated on at least one surface of a core layer made of a fiber reinforced thermoplastic resin sheet, and this is heated and pressed to heat-weld the core layer and the surface layer. A method for producing a fiber-reinforced resin laminate sheet for thermoforming, which comprises irradiating ionizing radiation from the surface layer side to crosslink the thermoplastic resin of the surface layer.