JP2002347101A - Device and method for manufacturing sheet-form molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing breaker plates and sheet-form molded articles capable of providing wide sheet-form molded articles at a high production rate. SOLUTION: In the breaker plate provided with various small holes for closing the resin flowing channel on a discharge side rather than the tip end of the screw shaft of a screw protruder to protrude a thermoplastic resin composition, the discharge side opening part of a small hole screw protruder equipped with the screw shaft side opening part as the introduction port of resin flowing while staying near the screw shaft tip end part of the screw protruder is formed so as to adjoin the outer peripheral side of the resin flowing channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a sheet-like molded article, and more particularly, to a tip of a screw shaft of a screw extruder for extruding a thermoplastic resin composition; Improvement of a sheet-like molded product manufacturing apparatus in which a breaker plate is disposed in a resin flow path between a thermoplastic resin composition extruded from the screw extruder and a sheet molding die for molding the thermoplastic resin composition into a sheet, and The present invention relates to a method for manufacturing a sheet-like molded product using a sheet-like molded product manufacturing apparatus.

[0002]

2. Description of the Related Art In general, a sheet-like molded product is extruded by a sheet-like molded product manufacturing apparatus (hereinafter, referred to as a device shown in FIG. 5) provided with a screw extruder 120 and a sheet molding die 130. This is referred to as “extrusion molding device”.) However, when the screw extruder 120 extrudes the molten thermoplastic resin composition, the extrusion molding apparatus 100 flows with stagnation in the space A formed near the screw shaft tip 122 of the screw 121. Due to the staying thermoplastic resin T, the sheet molding die 13
When the sheet is extruded to zero to shape the sheet, a streamline pattern called a flow mark F is formed on the sheet.

[0003] The flow mark F has an adverse effect such as lowering the strength of the shaped sheet and deteriorating the appearance. Therefore, as a technique for removing the staying thermoplastic resin T staying in the space A near the tip end of the screw shaft in the screw extruder, which causes the generation of the flow mark F, JP-A-56-150526 and JP-A-4-150526.
JP-A-276420 and JP-A-4-339632 disclose extrusions provided with a breaker plate such that the center of the breaker plate is displaced from the axis of the screw shaft, or the retained portion is stirred. A technique for modifying a molding apparatus and a technique for using a gear pump for adjusting a flow rate fluctuation are disclosed.

[0004]

However, in the method of modifying the extrusion molding apparatus provided with the breaker plate described in the above-mentioned publication, the generation of flow marks from the extruded sheet formed by extrusion is reduced. They could do it, but they could not be completely extinguished. In particular, when foaming a sheet molded product formed by extrusion molding to obtain a foam, remaining flow marks that cannot be completely eliminated lower the strength of the foamed sheet molded product. Or adverse effects such as poor appearance.

[0005] Further, the method of eliminating the flow mark using the gear pump described in the above-mentioned publication makes the equipment extremely complicated, and the manufacturing cost of the product becomes extremely high. However, it is difficult to completely remove the flow mark. For this reason, as shown in FIG. 5, the flow mark F is cut from the sheet molding H2 formed into a sheet shape by an extrusion die so as to remove the flow mark F, and the final molded product ( Hereinafter, it is referred to as “product”.) S2 was molded.

However, in such a sheet forming method, the effective width of the obtained product S2 is narrow, which causes a problem in terms of cost, and it is difficult to form a wide product S2. Problem. Therefore,
The present invention has been made in view of the above-described problems, and provides a sheet-shaped article manufacturing apparatus and a sheet-shaped article manufacturing method capable of obtaining a wide sheet-shaped article with high productivity. The purpose is.

[0007]

In order to achieve the above object, an apparatus for manufacturing a sheet-like molded product according to claim 1 of the present invention (hereinafter referred to as a "production apparatus according to claim 1") is provided with a heat source. A screw extruder for extruding the thermoplastic resin composition, and a mold for shaping the thermoplastic resin composition extruded from the screw extruder into a sheet shape, the tip of the screw shaft of the screw extruder and the mold In the apparatus for manufacturing a sheet-like molded product provided with a breaker plate having a large number of small holes penetrating from the upstream side to the downstream side of the extruder in the resin flow path between the inlet and the extruder, In order to prevent a part of the thermoplastic resin composition flowing in the resin flow path from entering the mold, the mold is discharged to the outside through the extruder and / or the peripheral wall of the mold. A resin discharge channel is drilled In addition, the breaker plate has, among the many small holes, small holes whose upstream opening faces the resin flowing with stagnation near the tip of the screw shaft of the screw extruder. And the downstream opening is connected to the inlet of the resin discharge path.

[0008] A method for manufacturing a sheet-like molded product according to claim 2 of the present invention (hereinafter, referred to simply as "the manufacturing method of claim 2") is a method for manufacturing a sheet-like molded product using the manufacturing apparatus of claim 1. The method for manufacturing a product, wherein a breaker plate is arranged in a resin flow path on the outlet side of the tip of the screw shaft of the screw extruder, and the breaker plate is flowing with stagnation near the tip of the screw shaft of the screw extruder. The apparatus is provided with a retained resin discharging step of discharging the retained thermoplastic resin to the outside of the manufacturing apparatus through the small holes of the breaker plate connected to the resin discharge path and the resin discharge path.

According to a third aspect of the present invention, there is provided a method for producing a sheet-like molded article, wherein the thermoplastic resin composition contains a foaming agent in addition to the constitution of the second aspect. The article was a foam that foamed when heated.

In the above configuration, the resin flowing through the resin discharge passage is discharged at a position near the tip end of the screw shaft of the screw extruder while the resin is flowing (hereinafter referred to as “retained resin”). The shape and size are not particularly limited as long as they are provided, and the outlet portion may be provided in the extruder or in the mold.

Further, the shape of the breaker plate is such that among the many small holes, the upstream opening is located at a position facing the retained resin (hereinafter, referred to as “retained resin passage small holes”).
Is arranged so as to connect the downstream opening to the inlet of the resin discharge path, and is not particularly limited as long as the accumulated resin can be discharged out of the manufacturing apparatus. The resin passage small holes may intersect with other small holes.

The number of small holes provided in the breaker plate, the shape of the small holes, the opening ratio of the small holes, the number of the small holes for passing the retained resin and other small holes are not particularly limited.
For example, when the screw extruder is a twin screw, it is preferable to provide at least two or more small holes for passing the retained resin so that the resin inlet faces the vicinity of the tip of each of the two screw shafts. In the case of a shaft screw, it is preferable to provide at least one or more such that the resin inlet faces the position near the tip of one screw shaft.

At this time, the screw-shaft extruder is designed to make the tip of the screw-shaft as sharp as possible.
It is preferable to minimize the amount of resin that stays in the vicinity of the tip end of the screw shaft because the amount of resin discharged to the outside of the manufacturing apparatus can be reduced.

In addition, the diameter of the small hole for passing the retained resin must be appropriately set in consideration of the generated flow mark. That is, if the diameter of the small holes for passing the retained resin is too large, sound resin that does not generate flow marks will be discharged to the outside of the apparatus. The disadvantage is that the efficiency of manufacturing is reduced. Further, if the diameter of the small holes for passing the retained resin is too small, not only the resin that generates the flow mark may not be completely removed, but also the resin path of the small holes for passing the retained resin may have a small size. In addition to being slightly longer than the resin path, the pressure loss may increase due to the structure of being connected to the resin discharge path.

As described above, an adjustment valve or the like for adjusting the amount of resin to be discharged is provided in the staying resin discharge path including the small resin passage small holes and / or the resin discharge path provided in the breaker plate. In order to reduce the amount of resin discharged as much as possible without causing flow marks,
Preferably, the regulating valve is adjusted. The installation of the adjusting valve is not particularly limited, and for example, a throttle valve may be provided in a part of the discharge path of the accumulated resin.

It is preferable to provide a temperature control mechanism in the discharge path of the accumulated resin in order to prevent the discharge path from being blocked due to solidification of the resin to be discharged. On the other hand, small holes other than the small resin passage small holes provided in the breaker plate allow the thermoplastic resin composition extruded from the screw extruder to pass into the mold without stagnation. If it is not particularly limited, for example, a chamfer for smoothly guiding the extruded resin may be provided at the upstream opening of the small hole.

The screw extruder in the present invention is not particularly limited, but is a single screw, two or more screw extruder or a combination thereof. However, it may be a meshing type or a non-meshing type. Further, the type of shaft may be a parallel type or a conical type. In addition, a tandem system in which screw extruders are combined in multiple stages may be used.

The mold for shaping the thermoplastic resin composition extruded from the screw extruder into a sheet is not particularly limited, and examples thereof include a T die, an L die, a coat hanger die and a fish tail die. It does not matter whether it is a single layer or multiple layers. In addition, after obtaining a pipe-shaped object using a thin pipe mold, a part of the pipe-shaped object may be cut out and shaped into a sheet.

The thermoplastic resin used in the present invention is not particularly restricted but includes, for example, olefin resins such as polyethylene, polypropylene and ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride and acrylonitrile styrene. Polymer, polystyrene, (meth)
Examples include acrylic resins, polyamides, polycarbonates, polyacetals, polyvinyl alcohols, thermoplastic polyesters, thermoplastic elastomers, and powdered rubber. These may be used alone or in combination of two or more.

Further, the thermoplastic resin composition used in the present invention may contain a filler, a lubricant,
Additives such as stabilizers, flame retardants, antiblocking agents, defoamers, pigments, dyes and the like may be added within a range that does not impair the purpose of the present invention. Examples of the sheet-like molded article molded by the extrusion molding apparatus provided with the breaker plate according to the present invention include a composite sheet, a foamed sheet, and a foamable composite sheet in addition to a simple sheet molded article.

Next, the case where a foam is formed as a sheet-like molded product as in the production method of claim 3 will be described with reference to the description of a polyolefin-based resin foamable composite sheet in JP-A-11-29142. I do. JP-A-11-29
No. 1425 discloses a foamable resin composition obtained by adding a pyrolytic chemical blowing agent to a modified resin obtained by reacting a polyolefin-based resin with a modifying monomer as a thermoplastic resin and kneading the resultant into a sheet. A method is described in which a sheet-like material having a degree capable of suppressing an in-plane foaming force generated when the sheet is heated and foamed is laminated on at least one surface of the obtained foamable sheet.

By heating the polyolefin-based resin foamable composite sheet and foaming by decomposing the foaming agent, a composite foam can be obtained. In addition, the flow mark generated in the expandable composite sheet and the composite foam often occurs remarkably unless the manufacturing apparatus according to claim 1 is used, and it is very difficult to solve the problem with the conventional technology.
The manufacturing apparatus according to claim 1 and the manufacturing method according to claim 2 or 3 are particularly effective measures.

The above-mentioned "in-plane direction" means any direction in the sheet surface of the foamable sheet.
Including length direction and width direction. The term “sheet” does not refer to a strict form based on the thickness, but includes a relatively thin sheet usually called a film to a relatively thick sheet usually called a plate material.

The polyolefin constituting the main component of the above-mentioned polyolefin resin is a homopolymer of an olefinic monomer or a copolymer of a main component olefinic monomer and another monomer, and is not particularly limited. However, for example, polyethylene such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, homo-type polypropylene, random-type polypropylene, polypropylene such as block-type polypropylene, polybutene, ethylene-propylene copolymer, ethylene-propylene- Copolymers containing ethylene as a main component such as diene terpolymers, ethylene-butene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, and the like. Even with the above combinations There. As described above, as the polyolefin as a main component of the polyolefin-based resin, one or a combination of two or more of the above-described polyethylene and polypropylene is preferable.

The above-mentioned polyolefin resin refers to a resin composition in which the proportion of the polyolefin is 70 to 100% by weight. The resin other than the polyolefin constituting the polyolefin resin is not limited, and examples thereof include polystyrene and styrene elastomer. If the proportion of polyolefin in the polyolefin resin is less than 70% by weight, not only the characteristics of polyolefin such as light weight, chemical resistance, flexibility and elasticity cannot be exhibited, but also it is difficult to secure the melt viscosity required for foaming. This is not preferable because it may result in

The above-mentioned modifying monomer is a compound having two or more functional groups capable of undergoing a radical reaction.
Examples of the functional group include an oxime group, a maleimide group, a vinyl group, an allyl group, and a (meth) acryl group, and a quinone compound. A compound having two oxime groups among the modifying monomers, that is, a dioxime compound has two oxime groups or a structure in which a hydrogen atom thereof is substituted with another atomic group (mainly a hydrocarbon group) in a molecule. And compounds such as p-quinone dioxime and p, p-dibenzoylquinone dioxime. Further, dioxime compounds can be used in combination of two or more.

Further, among the modifying monomers, a compound having two maleimide groups, that is, a compound having a maleimide structure in a molecule.
Examples of the bismaleimide compound having N,
N, '-P-phenylenebismaleimide, N, N,'-
Examples include m-phenylene bismaleimide, diphenylmethane bismaleimide and the like. At this time, bismaleimide compounds can be used in combination of two or more. Also, polymaleimides having two or more maleimide structures in the molecule are included in the category of bismaleimide compounds because they have the same effect.

In addition, the vinyl group of the modifying monomer is 2
Examples of the compound having two, that is, divinyl compound include divinylbenzene, and the two vinyl groups may be in any of ortho, meta and para positions. Further, among the modifying monomers, compounds having two or more allyl groups, that is, as an allyl-based polyfunctional monomer,
Examples include diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, diallyl chlorendate and the like. The allylic polyfunctional monomer may be used in combination of two or more.

The compound having two or more (meth) acryl groups among the modifying monomers, that is, the (meth) allyl polyfunctional monomer is, for example, a compound having 2 to 4 (meth) acryloyloxy groups. Can be With two (meth) acryloyloxy groups, alkanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate , Neopentyl glycol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, ethylene glycol adduct di (meth) acrylate of bisphenol A, propylene glycol adduct di (meth) acrylate of bisphenol A, and the like. And three acryloyloxy groups, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane ethylene oxalate De added tri (meth) acrylate,
Glycerin propylene oxide-added tri (meth) acrylate, tri (meth) acryloyloxyethyl phosphate, and the like. With four (meth) acryloyloxy groups, pentaerythritol tetra (meth) acrylate, ditrimethylolpropanetetra (meth)
Acrylate and the like. Examples of the quinone compound among the modifying monomers that can be used in the method of the present invention include hydroquinone, p-benzoquinone, tetrachloro-p-benzoquinone and the like.

The amount of the modifying monomer may be appropriately selected according to the type of the monomer, but is generally 0.05 to 5 parts by weight, preferably 0.2 to 5 parts by weight, per 100 parts by weight of the polyolefin resin. ~ 2 parts by weight. If the amount of the modifying monomer is less than 0.05 part by weight, the melt viscosity required for foaming cannot be imparted. If the amount exceeds 5 parts by weight, the degree of cross-linking is too high, and the extrudability is poor (for example, High load is applied and melt fracture occurs). Furthermore, the foaming agent to be added later cannot be uniformly kneaded in the resin composition, and the gel fraction is unnecessarily increased excessively, thereby impairing the recyclability. In addition, the foaming pressure at the time of heat foaming becomes too high later, and it becomes impossible to use a sheet-like material having a low tensile strength for suppressing in-plane foaming.

In the above-mentioned method for producing the expandable composite sheet and composite foam, an organic peroxide may be used in combination with the modifying monomer. In particular, when a vinyl compound or an allyl compound is used as a modifying monomer,
It is preferable to use an organic peroxide in combination. The organic peroxide may be any of those generally used for a graft reaction of polyolefin, for example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,
t-butyl baroxy acetate, t-butyl baroxy benzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butyl veroxy) hexane, di-t-butyl peroxide, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexine-3; and these are suitably used alone or in combination of two or more. In particular, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylpyroxy) hexane, di-t-butyl peroxide,
One or more of 5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 and the like are more preferably used.

If the amount of the organic peroxide used is too small, the conversion of the grafting reaction is insufficient, and if it is too large, so-called β-cleavage of polypropylene occurs remarkably, and the molecular weight of the modified product is too low, and the physical properties are too low. In some cases, foaming may be poor due to a decrease in viscosity or a decrease in viscosity. In consideration of these points, the amount of the organic peroxide to be used is preferably 0.001 to 0.5 part by weight, preferably 0.005 to 0.15 part by weight, based on 100 parts by weight of the polyolefin resin. More preferably, there is.

In order to obtain a modified resin, a polyolefin resin and a modifying monomer are melt-mixed and reacted under predetermined conditions using a kneading apparatus such as a screw extruder or a kneader.
The reaction temperature at this time is 170 ° C. or higher and the decomposition temperature of the polyolefin resin or lower, preferably 200 ° C. to 300 ° C.
It is. If the reaction temperature is lower than 170 ° C., the denaturation is insufficient, and the expansion ratio of the finally obtained foam may not be sufficiently high. If it exceeds about 300 ° C., the polyolefin-based resin is easily decomposed.

The apparatus used for the above reaction may be a screw kneader or a melt kneading apparatus generally used in plastic molding, and examples thereof include a kneader, a rotor and a continuous kneader. Among them, a screw extruder capable of continuous operation is preferable, and a single-screw extruder, a twin-screw extruder, a multi-screw extruder having three or more screws, and the like are all suitably used.

As a single screw extruder, in addition to a general full flight screw, an extruder having a discontinuous flight screw, a pin barrel, a mixing head, and the like can be used. Further, as the twin screw extruder, a meshing co-rotating extruder, a meshing different direction rotating extruder, a non-meshing different direction rotating extruder and the like can be suitably used. Providing a vacuum vent at the latter stage of the extruder is effective for preventing volatiles from remaining in the resin composition.

When a screw extruder is used, the polyolefin-based resin is usually introduced into the extruder from a hopper, but it is also preferable to use a screw type feeder, a weight control type feeder or the like in order to increase quantitativeness. The modifying monomer may be introduced into the extruder from the hopper at the same time as the polyolefin-based resin, but in particular, some of divinylbenzene and allyl-based polyfunctional monomers are liquid at normal temperature and pressure. It is preferable to supply the liquid from the liquid injection hole provided in the downstream part of the molten resin from the position where the resin is melted, since this can be uniformly dispersed in the molten resin. At this time, it is desirable that the liquid monomer be sent by a pressure-feeding pump such as a plunger pump.

In the case where an organic peroxide is used in combination with the modifying monomer, the organic peroxide is preliminarily mixed with the modifying monomer and they are simultaneously charged. Alternatively, the organic peroxide is separated before and after the monomer is added. The method of charging can be applied. The modified resin may be further melt-blended with the same or a similar unmodified polyolefin-based resin (hereinafter collectively referred to as a blending resin) for the purpose of improving fluidity. By using a blend of such a modified resin and a blending resin, the flowability of the foamable resin composition to be obtained is improved, whereby an extremely thin raw foam can be molded, and as a result, a thin composite foam Production of sheets becomes possible. In addition, the fluidity works favorably to form spindle-shaped cells, and as a result, it is possible to obtain a foam having higher compressive strength. The unmodified polyolefin resin may be the one described above in the definition of the polyolefin resin before the modification of the modified resin.

The kind and amount of the resin for blending are determined according to the moldability, appearance, and adhesion to the sheet-like material of the expandable composite sheet obtained, and the expansion ratio, mechanical properties, thermal properties, and the like of the composite foam obtained therefrom. It is appropriately adjusted depending on physical properties, cell shape and the like. In particular, it is preferable to newly melt-blend 50 to 200 parts by weight of the same or different unmodified polyolefin-based resin with respect to 100 parts by weight of the modified polyolefin-based resin. More preferably, 70 to 130 parts by weight are blended. If the proportion of the resin for blending is too large, the melt tension required for foaming cannot be maintained, so that the foaming ratio is reduced and a good foam cannot be obtained.

The thermal decomposition type chemical foaming agent is not particularly limited as long as it generates a decomposition gas by heating. As a typical example of such a thermal decomposition type chemical blowing agent,
For example, azodicarbonamide, benzenesulfonylhydrazide, dinitrosopentamethylenetetramine, toluenesulfonylhydrazide, 4,4-oxybis (benzenesulfonylhydrazide) and the like can be mentioned. These may be used alone or in combination of two or more. In particular, azodicarbonamide is most preferably used.

The thermal decomposition type chemical foaming agent is used in an appropriate amount depending on the desired expansion ratio in the range of 1 to 50 parts by weight, preferably 2 to 35 parts by weight, based on 100 parts by weight of the thermoplastic resin to be kneaded. It is preferred to use. If foaming is possible, the foaming agent may be a volatile foaming agent or the like which is originally a gas or a volatile liquid, instead of the above-described thermal decomposition type chemical foaming agent. Absent.

In order to obtain a foamable resin composition by kneading a thermally decomposable chemical foaming agent with a modified resin obtained from a polyolefin resin and a modifying monomer in this manner, a melt-kneading apparatus for the above reaction is used. And a melt kneading device for mixing (the structure may be the same as that of the melt kneading device for reaction), and the two are mixed at a temperature not higher than the maximum temperature at which the blowing agent does not substantially decompose. The mode of the melt kneading is as follows.

(A) In a batch or continuous melt-kneading apparatus for reaction, a polyolefin resin and a modifying monomer are melt-mixed and reacted, and the resulting modified resin is removed from the melt-kneading apparatus and solidified. After performing granulation, etc.
The resin composition is transferred to a batch or continuous kneading apparatus for mixing a foaming agent, into which a foaming agent is charged, and both are melt-kneaded to obtain a foamable resin composition.

(B) In a batch type melt-kneading apparatus for reaction, a polyolefin resin and a modifying monomer are melt-mixed and reacted, and the resulting fusible resin is mixed with a blowing agent in the melt-kneading apparatus. After cooling to a temperature that does not cause a large amount of decomposition, a foaming agent is added thereto, and the two are melt-kneaded to obtain a foamable resin composition.

(C) In a screw extruder for reaction (continuous melt-kneading apparatus), the polyolefin resin and the modifying monomer are melt-mixed at a temperature of 170 ° C. or more, and the reaction is carried out. Is cooled to a temperature at which the foaming agent does not decompose in a large amount, and then the foaming agent is charged through a supply port provided in the middle of the screw extruder, and the two are melt-kneaded to obtain a foamable resin composition.

(D) In another form of continuous operation, 2
After connecting the two screw extruders and the like and melting and mixing the polyolefin-based resin and the modifying monomer in the first generation to cause a reaction and lowering the temperature of the resulting modified resin in the same manner as described above, two units of the same resin composition It is transferred to the eyes, a foaming agent is added thereto, and the two are melt-kneaded to obtain a foamable resin composition.

The foamable resin composition obtained by kneading the mixture with a thermal decomposition type chemical foaming agent is shaped into a sheet. As a shaping method, in addition to extrusion molding, a method generally performed in plastic molding such as press molding, blow molding, calendering molding, and injection molding can be applied.

In particular, the foamable resin composition obtained according to the above-mentioned methods (a) and (b) is taken out from a batch-type kneading apparatus for mixing a foaming agent, and is put into a screw extruder to be continuously fed. The method of directly shaping the foamable resin composition discharged from the screw extruder according to the method of shaping into a sheet shape or the method of the above (a), (c) and (d) has a high productivity. It is preferable from the viewpoint.

The material constituting the sheet-like material used in the above-mentioned method can be freely selected from paper, cloth, wood, iron, non-ferrous metal, plastic, glass, inorganic material, and is not particularly limited. In addition, when the sheet-like material is laminated and integrated with a foamable sheet when forming a composite sheet or the like, it is desirable that the sheet-like material exhibit some degree of adhesiveness with the foamable sheet. Any sheet-like material without any material may be used as long as it can be bonded by a physical anchor effect.

However, if the strength of the sheet-like material for suppressing in-plane foaming is too low, the sheet-like material is torn during foaming, and foaming of the foamable sheet in the in-plane direction is sufficiently suppressed. You may not be able to do it. Therefore, as the sheet-like material for suppressing the in-plane foaming, when the magnification of the foam is 10 times, the tensile strength is 0.1 kgf /.
cm or more. However, this is a value obtained from the measured foaming pressure of the resin, and is not limited because it varies depending on the foaming ratio.

Examples of the sheet-like material that can be suitably used in the above-mentioned production method include glass cloth, cold gauze, woven or non-woven fabric, needle punch, paper and the like. The glass cloth refers to a surface mat obtained by forming glass fibers and a glass roving woven. The cold gauze, the nonwoven fabric and the needle punch are mainly made of synthetic resin fibers such as polyester and nylon. Woven fabrics include those made of general natural fibers and synthetic fibers.

The surface mat may contain a binder for binding short glass fibers. The binder is not particularly limited as long as the tensile strength of the sheet material satisfies the above range, and examples thereof include thermoplastic resins such as polyvinyl alcohol, saturated polyester, and acrylic resins, epoxy resins, and unsaturated polyesters. Thermosetting resin. Woven cloth,
Polyester fiber is used as the organic fiber constituting the nonwoven fabric,
Cotton, acrylic fiber, nylon fiber, carbon fiber, aramid fiber and the like can be mentioned. By using these sheet-like materials, it is possible to obtain a polyolefin-based resin composite foam having light weight and compressive strength.

The sheet may be made of a metal such as an iron sheet or a non-ferrous metal sheet such as aluminum, titanium and copper. The iron sheet includes a molten zinc steel sheet, a molten zinc aluminum alloy steel sheet, a stainless steel sheet and the like. As such a metal sheet,
A rolled thin sheet having a thickness of 0.01 mm to 2 mm is particularly preferably used. In this case, these metals may be arbitrarily plated or painted with an organic paint, an inorganic paint or the like.

When these metal sheet materials are used, the resulting polyolefin resin composite foam can be a lightweight metal composite plate. This is compared with a metal plate having a thickness of 1 to 5 mm or a metal composite plate in which a polyethylene layer or the like is disposed as an intermediate layer, without causing an extremely shortage of strength in practical use.
Further, there is an advantage that weight and cost can be reduced.
In addition, since the composite foam is manufactured by foaming a foamable composite sheet, the surface smoothness is extremely excellent as compared with a metal composite plate in which a metal sheet is pasted on the foam.

The method of laminating the sheet-like material on at least one side of the foamable sheet is not particularly limited.
For example, (a) a method in which a sheet is attached to a foamed sheet that has been cooled and solidified while heating, and (b) the foamable sheet is heated until it is in a molten state, and this is thermally fused to the sheet. And the like.

Here, in order to ensure the thickness accuracy of the expandable composite sheet, the method (a) is most preferable. Method (b)
In the thermal fusion of, for example, in a state in which the sheet-like material is lightly laminated on both sides of the foamed sheet in a molten state immediately after being extruded from the T-die, these are passed between opposed cooling rolls, It is preferable to use a method in which the two are integrated with each other by a pressing force of. It should be noted that, when the foamable sheet and the sheet-like material are laminated and integrated as described above, when the foamable sheet and the sheet-like material are to be peeled off at the interface between the two, the material is destroyed to such an extent that a high rate of material destruction occurs. Means a state in which is fixed.

The foamable composite sheet thus obtained can be foamed to a desired expansion ratio under normal pressure or constant pressure by heating under an appropriate temperature condition. The heating is usually based on the decomposition temperature of the thermal decomposition type chemical blowing agent,
It is performed in a temperature range up to the decomposition temperature + 100 ° C. Particularly, as a continuous foaming apparatus, in addition to a take-up foaming machine that foams while taking out a foam at an outlet side of a heating furnace, a belt-type foaming machine, a vertical or horizontal foaming furnace, a hot-air constant temperature bath, or an oil bath, A hot bath such as a bath or a salt bath is used.

[0057]

Next, an embodiment of a breaker plate according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a sheet-like molded product manufacturing apparatus according to the present invention (hereinafter, simply referred to as “manufacturing apparatus”) and a state in which a sheet-like molded article is obtained from a sheet-shaped product formed by the manufacturing apparatus. FIG.

As shown in FIG. 1, the manufacturing apparatus 1 includes a screw extruder 2 and a sheet forming die 3. The screw extruder 2 has two screws 21
Shaft extruder, these screw shaft tip portions 22
A breaker plate 10 is disposed in the resin flow path R on the outlet side of the screw extruder.

When the thermoplastic resin composition is extruded by the screw extruder 2 as a plurality of small holes, the breaker plate 10 flows with stagnation in the space A near the tip of the tip 22 of the screw shaft. Small holes (hereinafter, simply referred to as “small holes”) 11 for allowing the retained thermoplastic resin T (see FIGS. 1 and 2) to pass through, and other thermoplastic resin compositions to pass therethrough. Small holes 12 and 13 are formed.

As shown in FIGS. 4 (a) and 4 (b), the small hole 11 is formed such that the upstream opening 111 is formed in a space near the tip of the screw shaft tip 22 shown in FIG. 1 (a). Part A
And a downstream opening 1
Reference numeral 22 is provided at a position facing the inlet of the resin discharge passage O formed in the screw extruder 2.

The small holes 12 and 13 indicate small holes other than the small holes 11, and as shown in FIGS. 1, 2 and 4B,
It is provided substantially parallel to the direction in which the thermoplastic resin composition extruded by the screw extruder 2 flows. In addition, small hole 13
As shown in FIGS. 4 (a) and 4 (c), there are chamfered portions 13a and 13b which are processed so that the upstream opening is widened. The thermoplastic resin composition is smoothly guided into the small holes 13.

The sheet molding die 3 has a shape called a T-die, and is formed so that the thermoplastic resin composition extruded from the screw extruder 2 through the resin flow path R is formed into a sheet shape. Has become.

Next, the movement of the thermoplastic resin composition flowing in the screw extruder 2 will be described. Here, FIG. 3 is a cross-sectional view showing the thermoplastic resin composition flowing in the resin flow path at each position in the screw extruder 2 in FIG. That is, FIG. 3A is a diagram showing aa-a in FIG.
FIG. 3B is a sectional view taken along line bb in FIG. 2, FIG. 3C is a sectional view taken along line cc in FIG.
FIG. 3D is a sectional view taken along line dd in FIG. 2, and FIG.
FIG. 3 is a sectional view taken along line ee in FIG. 2.

The thermoplastic resin composition P is extruded in the screw extruder 2 by the rotation of the screw 21 as shown in FIG. 3A, but is extruded as shown in FIG. After passing through the shaft tip portion 22, FIG.
As shown in (1), a stagnant thermoplastic resin T, which also causes a flow mark, is generated in the extended portion of the tip of the screw 21.

The retained thermoplastic resin T passes through the small holes 11 of the breaker plate 10 and is
As shown in FIG. 4 and FIG. 4, the thermoplastic resin composition P discharged to the outside of the manufacturing apparatus 1 through the resin discharge path O and flowing through the resin flow path R is as shown in FIG. In this state, the staying thermoplastic resin T does not exist. (Residual resin transfer step) Thereafter, the thermoplastic resin composition P from which the retained thermoplastic resin T has been removed is extruded into the sheet molding die 3 as shown in FIG.

The thermoplastic resin composition P supplied as described above becomes a sheet-shaped product H1 shaped into a sheet as shown in FIG. At this time, as shown in FIG. 1, at both ends of the sheet molded article H1, portions B having a thickness defect occur. (Sheet molded article forming step) Finally, the sheet molded article H1 has a portion B where the thickness defect has occurred.
Is cut along the inside of the mold, and the remaining part is defined as a final molded product S1. (Final molded product finishing process)

As described above, the retained thermoplastic resin T at the tip of the screw causing the flow mark is discharged to the outside of the manufacturing apparatus 1 by the breaker plate 10 and the resin discharge path O. In the sheet molding H1 obtained by the sheet molding die 3, a flow mark does not occur. Therefore, when the sheet-like molded product is manufactured by the manufacturing apparatus 1, it is possible to obtain the final molded product S1 over substantially the entire width of the sheet molded product H1, and to efficiently obtain a high-quality sheet-like molded product. You can do it.

The stagnant thermoplastic resin T discharged to the outside of the manufacturing apparatus 1 and the portion B having a thickness defect cut in the final molded product finishing step are crushed or re-pelletized in another step. By re-injecting it into the screw extruder 2 after the above, it is possible to effectively reuse.

The method for producing a breaker plate and a sheet-like molded product according to the present invention is not limited to the above embodiment. In the above embodiment, the sheet-shaped molded product is not foamed, but may be foamed. Further, the production method according to the present invention may be applied to the production of a composite foam or a composite foam sheet.

In the above-described embodiment, the chamfered portions 13a and 13b are formed in the small holes 13 provided in the breaker plate 10 to prevent the resin from staying. Thus, the shape may be changed within a range in which the above-described stagnation can be suppressed.

[0071]

Next, the present invention will be described in detail with reference to the production of a foamable resin composite sheet as an example.

I) Production of Foamable Resin Composition (1) Preparation of Modified Polyolefin Resin As a modification screw extruder, a BT40 (Plastic Engineering Laboratory Co., Ltd.) co-rotating twin screw extruder was used. It has a self-wiping double-start screw with an L / D of 35 and a D of 39 mm. The cylinder barrel is composed of first to fourth barrels from upstream to downstream of the extruder. The die is a three-hole strand die, and a vacuum vent is provided in the fourth barrel to collect volatile components.

The operating conditions are as follows.

First, the polyolefin-based resin and the dioxime compound were separately charged from the rear end hopper into the modifying screw extruder having the above-mentioned structure, and the two were melt-mixed to obtain a modified resin. At this time, the volatile components generated in the extruder were evacuated by a vacuum vent. Polyolefin cable resin is a polypropylene random copolymer (Mitsubishi Chemical's "EG
8 ", density: 0.9 g / cm ³ ), and the supply amount was 10 kg / h.

The supply amount of the modifying monomer was p-quinone dioxime ("Barnock GM-P" manufactured by Ouchi Shinko Chemical Co., Ltd.) was 0.75 parts by weight based on 100 parts by weight of the polyolefin resin. The modified resin obtained by melting and mixing the dioxime compound was discharged from a strand die, cooled with water, and cut with a pelletizer to obtain pellets of the modified resin.

(2) Preparation of foamable resin composition and preparation of composite sheet The foaming agent kneading screw extruder is a TEX-44 type (manufactured by Nippon Copper Works Co., Ltd.) co-rotating twin screw extruder,
It is equipped with a self-wiping double-start screw and its L
/ D is 45.5 and D is 47 mm. The cylinder barrel is composed of the first to twelfth barrels from the upstream to the downstream of the extruder, and the sheet forming die has a width of 500 mm and a thickness of 3.5 m.
m T-die. The temperature setting categories are as follows.

The first barrel is constantly cooled. The first zone; the second to fourth barrels; the second zone; the fifth to eighth barrels; the third zone; the ninth to twelfth barrels; the fourth zone; a sheet molding die and a breaker plate part foaming agent. A side feeder is installed in the sixth barrel to supply the gas, and a vacuum vent is installed in the eleventh barrel to collect volatile components. The operating conditions are as follows.

[0078]

The modified resin obtained as described above was supplied from a modifying screw extruder to a blowing agent kneading screw extruder. The supply amount of the modified resin was 20 kg / h.
A blowing agent was supplied to the extruder from the side feeder and dispersed. The blowing agent is azodicarponamide (A
DCA), and the supply rate was 1 kg / h.

The foamable resin composition thus obtained by kneading the modified resin and the foaming agent is extruded from a 500 mm wide T-die through the breaker plate of the present invention, and is passed through three cooling rolls. A polyethylene terephthalate nonwoven fabric (manufactured by Toyobo Co., Ltd., “Spunbond Ecule 63
01A ", weighing 30 g / m ² , tensile strength: 1.6 k in length
g / cm, width 1.2kg / cm, heat-sealed, width 460m
m, a polyolefin resin foamable composite sheet having a thickness of 3.4 mm was obtained.

The breaker plate used had a thickness of 18.5 mm and an area of 38 cm ² (inner hole area of 18.4 c
m ² ), 143 parallel holes (holes leading to the resin flow path in the manufacturing apparatus) and 4 mm in diameter, and two resin discharge holes (holes leading to the resin discharge path in the manufacturing apparatus 1) and 5 mm in diameter. The amount of resin discharged to the outside of the manufacturing apparatus through the resin discharge hole and the resin discharge path is 0.5 k / hole.
g / h, 1.0 kg / h in total. (3) Foaming The obtained polyolefin resin foamable composite sheet was subjected to a continuous foaming machine having a heating zone at 230 ° C.
For about 8 minutes to obtain a composite foam.

(4) Performance Evaluation The obtained composite foam was evaluated for the following items.・ Measurement of effective width as a product: In a composite foam, the effective width of a product when a defective thickness portion or a flow mark portion is cut off is measured. -Expansion ratio measurement: In a composite foam, the expansion ratio is measured. -Compressive strength measurement: The compressive strength of a composite foam is measured.

Comparative Example 1 In the preparation of the foamable resin composition and the preparation of the composite sheet (2), the conventional breaker plate (thickness 18.5 mm, area 38 cm ² (inner hole area 18.3 cm ² ), parallel A polyolefin-based resin foamable composite sheet was obtained in exactly the same manner as in Example 1 except that 65 holes and a diameter of 6 mm were used, and that no resin discharge passage was formed in the manufacturing apparatus. This was heat-foamed by the same method to obtain a composite foam, and the performance was evaluated by the same method. Table 1 summarizes the evaluation results of Example 1 and Comparative Example 1.

[0084]

[Table 1]

As can be seen from Table 1, almost all widths of the composite foam obtained in the examples can be used as products, and it is recognized that good performance is exhibited in any item of the performance evaluation. Can be

[0086]

As described above, the manufacturing apparatus according to the first aspect of the present invention discharges the staying thermoplastic resin which causes the flow mark which flows with the stagnation near the tip of the screw shaft to the outside of the manufacturing apparatus. Can be. As a result, generation of a flow mark can be reliably suppressed, and a high-quality sheet-like molded product can be efficiently obtained.

According to the method for manufacturing a sheet-like molded product of the second aspect, a final molded product from which flow marks are completely eliminated can be efficiently obtained. Further, according to the method for manufacturing a sheet-shaped molded product of the third aspect, even if the sheet-shaped molded product is a foam which is significantly affected by the flow mark, the flow mark can be completely and efficiently removed. When these effects are used for denatured resin, they are also effective for remarkable flow marks, which were very difficult to solve in the prior art.

[Brief description of the drawings]

FIG. 1 shows an apparatus for producing a sheet-like molded product according to the present invention;
It is the schematic which showed typically the sheet shaping thing formed by this manufacturing apparatus.

FIG. 2 is a side sectional view of the screw extruder.

FIG. 3 is a sectional view showing a state in a resin flow path in the screw extruder in FIG. 2; (A) is a sectional view taken along line aa, (b) is a sectional view taken along line bb, (c) is a sectional view taken along line cc, (d) is a sectional view taken along line dd, (e). ) Is ee
It is a line sectional view.

FIG. 4 is a front view, a sectional view taken along line XX, and a sectional view taken along line YY of the breaker plate shown in FIGS. 1 and 2;

FIG. 5 is a schematic diagram schematically showing a conventional sheet-shaped molded product manufacturing apparatus and a sheet-shaped product formed by the manufacturing apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Manufacturing apparatus (for sheet-like molded product) 11 (for passing through retained resin) Small holes 12 Small holes 2 Screw extruder 21 Screw 3 Sheet forming die A Space (position near screw shaft tip) T Residual thermoplastic resin H1 Sheet molding S1 Sheet molding (product) R Resin channel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B29K 105: 04 B29K 105: 04 B29L 7:00 B29L 7:00

Claims (3)

[Claims] 1. A screw extruder for extruding a thermoplastic resin composition, and a mold for shaping the thermoplastic resin composition extruded from the screw extruder into a sheet shape, wherein a screw shaft of the screw extruder is provided. Production of a sheet-like molded product in which a resin flow path between the tip of the mold and the inlet of the mold is provided with a breaker plate having a large number of small holes penetrating from the upstream side to the downstream side of the extruder. In the apparatus, the extruder and / or the mold is provided with a peripheral wall of the extruder and / or the mold so that a part of the thermoplastic resin composition flowing in the resin flow path does not enter the mold. While the resin discharge passage for discharging to the outside is bored, the breaker plate has a large number of small holes, and the upstream opening has a stagnation at a position near the tip end of the screw shaft of the screw extruder. Reluctant flow to small holes made at a position facing the resins are sheet-like molded article manufacturing apparatus characterized by being arranged to connect the downstream opening in the inlet of the resin discharge path. 2. A method for producing a sheet-like molded product using the apparatus for producing a sheet-like molded product according to claim 1, wherein the breaker plate is provided with a resin flow path on the outlet side of the tip of the screw shaft of the screw extruder. Disposed, the retained thermoplastic resin flowing while accommodating at the position near the tip end of the screw shaft of the screw extruder, through the small holes of the breaker plate connected to the resin discharge path and the resin discharge path. A method for manufacturing a sheet-like molded product, comprising a staying resin discharging step of discharging the resin to the outside of a manufacturing apparatus. 3. The method for producing a sheet-like molded article according to claim 2, wherein the thermoplastic resin composition contains a foaming agent, and the sheet-like molded article is a foam that expands by applying heat.