JPH09220730A - Glass fiber reinforced thermoplastic resin lightweight molded article manufacturing method and lightweight molded article - Google Patents

Abstract

(57) [Abstract] [Problem] Light weight with a surface skin layer by injection molding,
Development of glass fiber reinforced thermoplastic resin lightweight molded product with excellent strength and rigidity, surface appearance, and warp-free deformation. A method for manufacturing a glass fiber reinforced thermoplastic resin lightweight molded article by injection molding using glass fibers, wherein a glass fiber content is 20 to 80% by weight as a molding raw material, and the glass fibers are parallel to each other. 2 to 1 arranged in
Using pellets with a length of 00 mm, with the mold open,
A lightweight molded product having voids is manufactured by injecting a molten resin smaller than the volume of the final molded product and closing the required amount of the mold.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a glass fiber reinforced thermoplastic resin lightweight molded article and a lightweight molded article obtained by the method, and more specifically to a specific glass fiber-containing thermoplastic resin pellet. By injection molding, it is lightweight without using a foaming agent, has a good surface condition, and has a high strength and high rigidity. A method for producing a glass fiber reinforced thermoplastic resin lightweight molded article and the lightweight molding obtained by the method. Regarding goods.

[0002]

2. Description of the Related Art A glass fiber reinforced resin is used as an important material because it has high tensile strength, rigidity and heat resistance. Above all, injection-molded products occupy the center of the line because of their easy moldability. However, there are drawbacks that the specific gravity of the molded product increases due to an increase in the amount of the glass fiber compounded, and the strength decreases due to the cutting of the glass fiber during molding. In addition, due to the anisotropy, there is a drawback that the warp deformation is large. Therefore, as a method of improving these drawbacks, a method of using resin pellets reinforced by glass fibers arranged in parallel with each other and having a pellet length of 2 to 100 mm has been proposed (for example, Japanese Patent Publication No. 63-
37694, JP-A-3-188131, etc.). Further, a method for producing a fiber-reinforced thermoplastic resin molded product in which a parallel fiber-reinforced thermoplastic resin pellet having a length of 10 to 100 mm is molded and a reinforcing fiber having a length of 5 to 100 mm is intertwined is proposed. (JP-A-6-198
No. 753). However, even with these methods, the problem that the weight becomes heavy due to the incorporation of glass fibers remains.

On the other hand, as a method for reducing the weight of a glass fiber reinforced resin molded article, a foam injection molding method using a foaming agent is known (Japanese Patent Laid-Open No. 7-247679). However, in this case, a considerable amount of a foaming agent is required, and it is not easy to increase the expansion ratio to 2 to 5, and the glass fiber content is naturally limited.
Further, as another molding method, it is possible to inject a foaming agent-containing resin into a mold cavity in which a mold has been opened in advance, and then to close the mold (injection press) to manufacture a foamed molded product. However, even in this case, if an attempt is made to obtain a molded product with a high expansion ratio by using a large amount of foaming agent, gas runs on the surface of the molded product and a silver mark is generated, as well as the strength and rigidity of the molded product. However, the current situation is that there are many problems and they have not been put to practical use.

[0004]

DISCLOSURE OF THE INVENTION The present invention uses a specific glass fiber-containing thermoplastic resin pellet having a long fiber length to produce a lightweight molded article excellent in surface characteristics, strength and rigidity without using a foaming agent. It is an object of the present invention to provide a manufacturing method and a lightweight molded article obtained by the manufacturing method.

[0005]

Means for Solving the Problems The inventors of the present invention have made diligent studies to obtain a glass fiber reinforced thermoplastic resin lightweight molded product satisfying weight reduction and strength by injection molding, and as a result, a specific molding raw material and molding method have been obtained. It was found that not only the above objects can be achieved but also a lightweight molded product excellent in appearance (surface characteristics) can be obtained by the combination of The present invention has been completed based on such findings.

That is, in the present invention, the glass fiber-containing thermoplastic resin pellet (A) having a glass fiber content of 20 to 80% by weight, glass fibers arranged in parallel with each other and a length of 2 to 100 mm, or A molding raw material comprising a mixture of the pellets (A) and a thermoplastic resin other than (A) such that the glass fiber content in the glass fiber-containing thermoplastic resin pellets (A) is 20 to 80% by weight of the whole. Melt kneading, and inject a predetermined amount of molten resin into the mold opened so that it is larger than the mold volume equivalent to the final molded product, and mold the final molded product before or after the completion of resin injection Of a glass fiber reinforced thermoplastic resin lightweight molded article characterized by closing up to the volume of the above and a specific bending strength having a skin layer having no voids on the surface obtained by the molding method. It is intended to provide an amount moldings.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The method for producing a glass fiber-reinforced thermoplastic resin lightweight molded article of the present invention is achieved by using the specific glass fiber-containing thermoplastic resin pellet (A) as a molding raw material. There is no particular limitation on the thermoplastic resin used here, for example, polyolefin resin,
Polystyrene resin, polyvinyl chloride resin, polyamide resin, polyester resin, polyacetal resin, polycarbonate resin, polyaromatic ether or thioether resin, polyaromatic ester resin, polysulfone resin, acrylate resin, etc. Is mentioned.

Examples of the polyolefin resin include homopolymers of α-olefins such as ethylene; propylene; butene-1; 3-methylbutene-1; 3-methylpentene-1; 4-methylpentene-1 and the like. Examples thereof include copolymers thereof and copolymers of these with other copolymerizable unsaturated monomers. As a typical example,
Polyethylene resins such as high-, medium-, and low-density polyethylene, linear polyethylene, ultra-high-molecular-weight polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, syndiotactic polypropylene, isotactic Polypropylene resins such as tic polypropylene, propylene-ethylene block copolymer or random copolymer, poly-4-methylpentene-1
And the like.

As the styrene resin, for example,
Homopolymers such as styrene and α-methylstyrene, copolymers thereof, and copolymers with unsaturated monomers copolymerizable therewith are exemplified. As typical examples, general-purpose polystyrene, impact-resistant polystyrene, heat-resistant polystyrene (α-methylstyrene polymer), syndiotactic polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer ( AS), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS), acrylonitrile-ethylene-propylene rubber-styrene copolymer (A
ES), acrylic rubber-acrylonitrile-styrene copolymer (AAS), and the like.

As the polyvinyl chloride resin, for example,
Examples thereof include vinyl chloride homopolymers and copolymers with unsaturated monomers copolymerizable with vinyl chloride. Examples of the copolymer include vinyl chloride-acrylate copolymer, vinyl chloride-methacrylate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, and vinyl chloride-vinyl acetate copolymer. Polymers, vinyl chloride-vinylidene chloride copolymers and the like can be mentioned. further,
Those obtained by post-chlorination of these polyvinyl chloride resins to increase the chlorine content can be used.

As the polyamide resin, for example, 6-
Ring-opening polymerization of cyclic aliphatic lactams such as nylon and 12-nylon, and condensation polymerization of aliphatic diamine and aliphatic dicarboxylic acid such as 6,6-nylon; 6,10-nylon; 6,12-nylon And polycondensation products of aromatic diamine and aliphatic dicarboxylic acid, such as polycondensation products of m-xylene diamine and adipic acid, polycondensation products of p-phenylenediamine and terephthalic acid, and m-phenylenediamine And polycondensation products of isophthalic acid and polycondensation products of aromatic diamine and aromatic dicarboxylic acid, and polycondensation products of amino acids such as 11-nylon.

Examples of polyester resins include those obtained by polycondensing aromatic dicarboxylic acids and alkylene glycols, and specific examples thereof include polyethylene terephthalate and polybutylene terephthalate. Examples of the polyacetal resin include homopolymers of polyoxymethylene and formaldehyde-ethylene oxide copolymer obtained from trioxane and ethylene oxide.

As the polycarbonate resin, 4,
A 4'-dihydroxydiarylalkane-based polycarbonate, particularly a bisphenol A-based polycarbonate obtained by a phosgene method of reacting bisphenol A with phosgene or a transesterification method of reacting bisphenol A with a diester carbonate such as diphenyl carbonate is preferably used. . In addition, modification in which a part of bisphenol A is replaced with 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane or 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane Bisphenol A-based polycarbonate and flame-retardant bisphenol A-based polycarbonate can also be used.

The polyaromatic ether or thioether type resin has an ether bond or a thioether bond in the molecular chain. Examples of such a resin include polyphenylene ether and polyphenylene ether grafted with styrene, and polyether. Examples include ether ketone and polyphenylene sulfide. Examples of the polyaromatic ester resin include polyoxybenzoyl obtained by polycondensation of p-hydroxybenzoic acid, polyarylate obtained by polycondensation of bisphenol A and aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid. Is mentioned.

The polysulfone-based resin has a sulfone group in the molecular chain, and examples thereof include polysulfone and phenylene group obtained by condensation polymerization of bisphenol A and 4,4'-dichlorodiphenylsulfone. Include a polyether sulfone having a structure in which p is linked to the p-position via an ether group and a sulfone group, and a polyaryl sulfone having a structure in which a diphenylene group and a diphenylene ether group are alternately linked via a sulfone group. it can.

Examples of acrylate resins include methacrylic acid ester polymers and acrylic acid ester polymers, and examples of these monomers include methacrylic acid and acrylic acid methyl, ethyl, n-propyl, isopropyl. , Butyl ester, etc. are used, and a typical example of industrial molding material is methyl methacrylate resin.

In the present invention, the above thermoplastic resins may be used alone or in combination of two or more kinds. Further, among the above-mentioned thermoplastic resins, polypropylene, lantam copolymers of propylene and other olefins, polypropylene-based resins such as block copolymers or mixtures thereof are preferable, and particularly unsaturated carboxylic acids or derivatives thereof. A polypropylene-based resin containing an acid-modified polyolefin-based resin modified with is preferable.

The polyolefin resin used for the acid-modified polyolefin resin is, for example, polypropylene, polyethylene, ethylene-α-olefin copolymer, propylene-ethylene random copolymer, propylene-ethylene block copolymer, Examples thereof include ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene compound copolymer (for example, EPDM), ethylene-aromatic monovinyl compound-conjugated diene compound copolymer rubber and the like. Examples of the α-olefin include propylene; butene-1; pentene-1; hexene-1; 4-methylpentene-1 and the like, and these may be used alone or in combination of two or more. You may. Among these polyolefin-based resins, a polypropylene-based resin or a polyethylene-based resin containing a copolymer is preferable, and among them, a polypropylene-based resin is most preferable.

Specific examples of the unsaturated carboxylic acid or its derivative used for modification include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, angelica. Unsaturated carboxylic acids such as acids, maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate,
Acid anhydrides, esters, amides, imides, such as methyl methacrylate, ethyl acrylate, butyl acrylate, monoethyl maleate, acrylamide, maleic monoamide, maleimide, N-butylmaleimide, sodium acrylate, and sodium methacrylate; Metal salts and the like can be mentioned. Among these, unsaturated dicarboxylic acids and derivatives thereof are preferred, and maleic anhydride is particularly preferred.

These unsaturated carboxylic acids and derivatives thereof may be used alone or in combination of two or more when modifying the polyolefin resin. The modification method is not particularly limited, and various conventionally known methods can be used. For example, a method of dissolving the polyolefin resin in an appropriate organic solvent, adding an unsaturated carboxylic acid or a derivative thereof and a radical generator, stirring and heating, or supplying each of the components to an extruder and performing melt kneading. A method or the like can be used. In the modified polyolefin resin, the amount of the unsaturated carboxylic acid or derivative thereof added is 0.01 to 20% by weight, preferably 0.1 to 20% by weight.
Those in the range of 1 to 10% by weight are preferred, and especially 0.1 to 1%.
0% by weight of a maleic anhydride-modified polypropylene resin is preferred.

The glass fiber used in the present invention is preferably surface-treated with a coupling agent. As the coupling agent, any one of conventionally known silane coupling agents and titanium coupling agents can be selected and used. Specific examples of the silane coupling agent include triethoxysilane; vinyltris (β-methoxyethoxy) silane; γ
-Methacryloxypropyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; β- (1,1
-Epoxycyclohexyl) ethyltrimethoxysilane; N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane; N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane; γ-aminopropyltriethoxysilane N-phenyl-γ-aminopropyltrimethoxysilane; γ-mercaptopropyltrimethoxysilane; γ-chloropropyltrimethoxysilane; γ-aminopropyltrimethoxysilane; γ-aminopropyl-tris (2-methoxy-ethoxy) Silane; N-methyl-γ-aminopropyltrimethoxysilane; N-vinylbenzyl-γ-aminopropyltriethoxysilane; Triaminopropyltrimethoxysilane;
3-Ureidopropyltrimethoxysilane; 3-4,5
Dihydroimidazolepropyltriethoxysilane; hexamethyldisilazane; N, O- (bistrimethylsilyl) amide; N, N-bis (trimethylsilyl) urea and the like. Among these, γ-aminopropyltriethoxysilane; N-β- (aminoethyl) -γ-
Aminopropyltrimethoxysilane; [gamma] -glycidoxypropyltrimethoxysilane; [beta]-(3,4-epoxycyclohexyl) ethyltrimethoxysilane and other aminosilanes and epoxysilanes are preferred. In particular, it is preferable to use the amino silane compound described above.

Specific examples of titanium coupling agents include isopropyl triisostearoyl titanate; isopropyl tridodecylbenzenesulfonyl titanate; isopropyl tris (dioctyl pyrophosphate) titanate; tetraisopropyl bis (dioctyl phosphite) titanate; tetraoctyl. Bis (ditridecyl phosphite) titanate; Tetra (1,1-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate; Bis (dioctyl pyrophosphate) oxyacetate titanate; Bis (dioctyl pyrophosphate) ethylene titanate; Isopropyl trioctanoyl titanate;
Isopropyl dimethacryl isosteroyl titanate; isopropyl isostearoyl diacryl titanate; isopropyl tri (dioctyl phosphate) titanate; isopropyl tricumyl phenyl titanate;
Isopropyltri (N-amidoethyl, aminoethyl)
Titanate; dicumylphenyloxyacetate titanate; diisostearoylethylene titanate;

The surface treatment of the glass fiber using such a coupling agent can be carried out by an ordinary method without any particular limitation. For example, it is desirable to carry out a sizing treatment in which an organic solvent solution or suspension of the coupling agent is applied to glass fibers as a so-called sizing agent, dry mixing, or a spray method. Further, a film-forming substance for glass can be used in combination with the above-mentioned coupling agent. The film-forming substance is not particularly limited, and examples thereof include polyester-based, urethane-based, epoxy-based, acrylic-based, vinyl acetate-based, and isocyanate-based polymers.

In the present invention, the glass fiber is E
-Glass fibers such as glass and S-glass having an average fiber diameter of 20 µm or less, preferably 1 to 17 µm, particularly preferably 3 to 14 µm. If it is less than 1 μm, it becomes difficult to wet and impregnate the resin during the production of pellets,
If it exceeds m, the fiber tends to be damaged during melt-kneading. Moreover, the thermoplastic resin is reinforced with glass fibers having a length equal to the pellet length of 2 to 100 mm, which is pelletized by using the above-mentioned thermoplastic resin, particularly polypropylene-based resin, using a drawing method or the like. Used as resin pellets. When pelletizing, it is preferable to use a fiber bundle in which glass fibers are converged using an appropriate sizing agent, preferably in the range of 100 to 10,000 fibers, more preferably in the range of 150 to 5000 fibers.

Examples of the sizing agent include urethane-based, olefin-based, acrylic-based, butadiene-based, and epoxy-based binders, and any of them can be used. Among these, urethane-based and olefin-based binders are preferable. The urethane-based sizing agent is usually a polyisocyanate obtained by a polyaddition reaction between a diisocyanate compound and a polyhydric alcohol.
It is contained at a ratio of 0% by weight or more, and there are a one-part type such as an oil-modified type, a moisture-curable type and a block type, and a two-part type such as a catalyst-curable type and a polyol-curable type. be able to. As the olefin resin, a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof can be used.

The glass fiber reinforced thermoplastic resin pellets (A) can be produced by impregnating the thus bundled fiber bundle with a thermoplastic resin. As a method for adhering and impregnating the glass fiber bundle with the resin, For example, a method of dipping the fiber bundle in a molten resin, a method of passing the fiber bundle through a coating die, a method of extruding the molten resin around the fiber bundle using a die, and the like can be adopted. In order to further improve the impregnation and wettability of the molten resin in the fiber bundle, an uneven portion is provided in the die, the fiber bundle (strand) to which the molten resin is adhered is pulled out under tension, and further pressed with a pressure roll. A pultrusion method incorporating the process can also be employed. The use of a sizing agent is not always necessary as long as the impregnability of the thermoplastic resin into the glass fiber and the manufacturability of the pellets are satisfied. After cooling the strand-shaped long-fiber-containing thermoplastic resin obtained in this way, by cutting into pellets of an appropriate length, the glass fibers are arranged in parallel with each other, and the glass fiber length and the pellet length are equal. The glass fiber-containing thermoplastic resin pellet (A) can be obtained.

In the present invention, pellets having a length of 2 to 100 mm are used. As a result, the length of the glass fiber becomes 2 to 100 mm, which is equal to the length of the pellet. If the fiber length is less than 2 mm, even if the manufacturing method of the present invention is adopted, it is difficult to reduce the weight of the molded product, mechanical strength and the like are not sufficient, and warp deformation may increase.
If it exceeds 100 mm, the injection molding becomes difficult, and the dispersibility of the glass fiber and the surface characteristics of the molded product may deteriorate. The pellet length is preferably in the range of 3 to 80 mm from the viewpoints of weight reduction, mechanical strength, appearance characteristics and warp deformation of the molded product, and particularly in the range of 5 to 50 mm considering dispersibility, appearance and surface characteristics. Is more preferable.

The polypropylene resin used for producing the pellets has a melt index: MI (230 ° C.,
2.16 kgf) in the range of 10 to 1000 g / 10 minutes, preferably 30 to 600 g / 10 minutes is preferable from the viewpoint of impregnation property and moldability. As the polypropylene-based resin, MI whose MI is adjusted according to polymerization conditions,
Alternatively, it is possible to use a material prepared by adding a peroxide and melt-kneading and adjusting so as to increase MI. In addition,
The pellets are not limited to those obtained by cutting strands, but those obtained by forming sheets, tapes, and bands into pieces having a fiber length of substantially 2 to 100 mm. Good.

In the method for producing a lightweight molded article of the present invention, the glass fiber-containing thermoplastic resin pellets (A) may be used alone for molding, but a mixture with a thermoplastic resin other than (A) may be used. Can also be used as a forming raw material. In this case, it is necessary that the content of the glass fiber in the pellet (A) is 20 to 80% by weight, preferably 30 to 70% by weight based on the whole forming raw material. In this case, the thermoplastic resin other than (A) is not particularly limited, and its shape such as commercially available general-grade pellets, granules, and powders is not limited,
It is preferable to use pellets. Also, reinforcing agents such as talc, mica, calcium carbonate, glass fiber milled fiber, carbon fiber, magnesium sulfate fiber, potassium titanate fiber, titanium oxide fiber, organic fiber, pellets containing filler, antioxidant, antistatic. Agent, flame retardant,
Examples thereof include pellets containing a pigment and a dispersant.

The method for producing a glass fiber reinforced lightweight molded article of the present invention comprises molding the specific glass fiber-containing thermoplastic resin pellet (A) alone or a mixture of (A) and a thermoplastic resin other than (A). As a raw material, it is usually molded by injection molding under specific conditions. In this case, the glass fibers in the forming raw material have a fiber length in a pellet in which glass fibers are arranged in parallel with each other from 2 to 100 mm, preferably from 3 to 80 mm, and the glass fiber content is from 20 to 80% by weight, preferably It is 30 to 70% by weight. If the glass fiber length is less than 2 mm, it is difficult to achieve sufficient weight reduction, and if it exceeds 100 mm, it becomes difficult to supply it to the injection molding machine, and even if it is supplied, plasticization becomes unstable and a uniform molded product is obtained. Difficult to manufacture. In addition, long fiber (2-100m
When the content of m) is less than 20% by weight, it may be difficult to continuously draw out the glass filament in the production of long fiber pellets, and the weight reduction may not be sufficiently achieved. On the other hand, if it is 80% by weight or more, the glass fiber bundle may not be sufficiently impregnated with the resin, and undisentangled fibers may remain in the molded product. As the glass fiber-containing thermoplastic resin pellets (A), pellets having different glass fiber lengths or pellets having different glass fiber contents can be mixed and used as necessary.

As the melt-kneading and injection method of the molding raw material, the molding raw material is charged into the heating cylinder of the molding machine, heated and melted, the fibers and the like are dispersed, and then sent to the tip of the injection molding machine to make a plan. Method of injecting with a jar, etc., in the heating cylinder,
A method of injecting molding raw material, heating and melting it, then sending it to the screw part of the injection molding machine with a plunger etc. to disperse fibers etc. and then injecting, using a screw with a small compression ratio in the deep groove, and cylinder temperature There is a method in which the resin is fed to the tip of the injection molding machine while the fiber breakage is prevented and the resin is injected and injection molding is performed with a plunger or the like. Here, the injection molding method includes a general injection molding method, an injection compression molding method, and an injection press molding method.

In the production method of the present invention, a molding material is melted and kneaded, and a predetermined amount of molten resin is injected into a mold opened so as to be larger than the mold volume equivalent to the final molded product, and before the completion of injection. Alternatively, a lightweight molded product can be manufactured by a molding method in which the mold is closed after completion. In this case, the degree of opening and closing of the mold can be appropriately set based on the glass fiber content of the forming raw material, the fiber length or the porosity (specific gravity of the molded body) of the target molded product. it can. Further, the timing of closing the mold may be appropriately determined in consideration of the temperature of the mold, the thickness of the skin layer on the surface of the molded product, the thickness of the molded product, and the like.

In the melt-kneaded product of the resin injected into the mold, it is preferable that the glass fibers are intertwined with each other,
The molten resin injected by this entanglement becomes a molten state having expandability in the mold. Next, the final lightweight molded product is obtained by closing the mold so as to have the volume of the final molded product and cooling. In the production method of the present invention, a foaming agent (gas, volatile compound, decomposable foaming agent), various stabilizers, antistatic agents, and
Additives such as weathering agents and colorants can also be added. Furthermore, in the method for producing a lightweight molded article of the present invention, at least one surface of a molding die is preliminarily mounted with a foam material, a fiber material such as a non-woven fabric, or a skin material such as a printing resin film on all or part thereof. It can also be molded.

The lightweight molded product obtained by the production method of the present invention is
The porosity is 10 to 80%, preferably 20 to 70%. If it is less than 10%, the effect of weight reduction is not obtained, and if it exceeds 80%, it becomes difficult to form a skin layer having no voids reliably, and the strength may be insufficient. The porosity in the present invention is the ratio of the volume excluding the volume occupied by glass fiber, resin, etc. in the lightweight molded product. The weight average glass fiber length in the molded product is 1 to
It is 20 mm, preferably 1.5 to 15 mm, more preferably 2.0 to 12 mm. If the glass fiber length in the molded product is less than 1 mm, the expandability of the molten resin is low and it is difficult to secure the porosity. Also, the strength of the molded product is not sufficient, and even if it exceeds 20 mm, the strength due to this However, the molding conditions must be mild, the molding time is long, the productivity is reduced, and it is not practical. The lightweight molded product obtained by the production method of the present invention has a specific bending strength (bending strength / specific gravity) of 80 MPa or more, preferably 9 MPa.
It is 0 MPa or more, more preferably 100 MPa or more. Such a high bending specific strength is achieved by forming a skin layer and reinforcing a specific length of glass fiber.

In the manufacturing method of the present invention, various molded products can be manufactured, and as a plate-shaped molded product and a molded product,
Especially, as a plate-shaped molded product of 30 mm or less, automobile parts,
It is used in the fields of home electric appliances and building materials.

[0036]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The glass fiber-containing thermoplastic resin pellets (long fiber pellets) used in Examples and Comparative Examples were prepared by the following method.

Production Example 1 Die: Attached to the tip of an extruder, and five rods were arranged linearly in the impregnating section. [Manufactured by a method using an apparatus according to JP-A-3-183531, FIG. Fiber bundle; glass roving in which 170 glass fibers having a diameter of 13 μm surface-treated with γ-aminopropyltriethoxysilane are bundled with a urethane-based sizing agent Preheating temperature: 200 ° C. thermoplastic resin: 230 ° C., 2.16 kgf Melt index (hereinafter simply referred to as MI) = 60 g / 10 min 1.0% by weight of modified polypropylene containing inulinic anhydride Melting temperature: 240 ° C. Rod: 5, 6 mm (diameter) × 3 mm (length) Gradient Angle: 25 degrees Under the above conditions, while adjusting the amount of the fiber bundle between the tension rolls, it is fed into the die for impregnation, and after cooling, the glass fiber content is 41% by weight and the length is 2 by a pelletizer.
0 mm glass fiber reinforced pellets (hereinafter referred to as long fiber pellets A-1) were produced.

Production Example 2 Continuous glass fibers having a fiber diameter of 10 μm treated with γ-aminopropyltriethoxysilane were drawn into a polypropylene-based aqueous emulsion, impregnated with a resin, and then dried to obtain a glass fiber content. Produced 97% by weight of glass roving. [Polypropylene-based aqueous emulsion: maleic anhydride content 5% by weight, [η]: 0.20
80 parts by weight of dl / g polypropylene, 100 parts by weight of water, 20 parts by weight of a nonionic emulsifier and 10 parts by weight of a neutralizing agent were stirred while heating to 150 ° C. to emulsify. ]. Using the obtained rovings, glass fiber-reinforced pellets (hereinafter, referred to as long fiber pellets A-2) having a glass fiber content of 69% by weight and a length of 12 mm were produced according to Production Example 1.

In the following examples and comparative examples, the evaluation of the molded product and the test of the test piece cut out from the molded product were carried out by the following methods. (A) Appearance of molded product: Visual evaluation of molded product (b) Bending strength: Measured according to JIS K-7203. Specific strength of bending = Bending strength / Specific gravity (c) Weight average glass fiber length in the molded product: After ashing the molded product, take a picture of the glass fiber with a universal projector at a magnification of 10 and use a digitizer to measure about 3000 pieces were measured and the average value was calculated. (D) State of warped deformation of molded product: A disk having a diameter of 800 mm was placed on a surface plate and evaluated by the degree of floating near the gate and the degree of floating of the circumference from the surface plate. The following criteria were evaluated based on the floating height measured by a height gauge. 0 to 3 mm: Good 3 to 10 mm: Small deformation 10 mm or more: Large deformation

Example 1 Using the long fiber pellets A-1 as a molding raw material, an injection molding machine (manufactured by Mitsubishi Heavy Industries, Ltd .: 850 MGW, equipped with an Idemitsu compression unit) was used, resin temperature: 280 ° C., mold (800
A disc having a diameter of mm and a thickness of tmm) was used. 6m mold in advance
In the opened state, a resin having a volume corresponding to a thickness of 3 mm was injected, the mold was closed to 4.5 mm, and then cooled to obtain a molded product. The molded product was a good lightweight molded product in which a firm skin layer was formed on the surface and there was no silver or the like. Table 1 shows the evaluation results of the porosity of the molded product, the weight average glass fiber length in the molded product, the evaluation of the molded product, the specific gravity, and the specific strength of bending.

Example-2 In Example-1, while the mold was previously opened to 5 mm, a resin having a volume corresponding to a thickness of 2 mm was injected, the mold was closed to 3.5 mm, and then cooled. A molded product was obtained. The molded product was a good lightweight molded product in which a firm skin layer was formed on the surface and there was no silver or the like. The evaluation results of the molded products are shown in Table 1.

Example-3 In Example-1, as a molding raw material, a dry blended product of long-fiber pellet A-2: 80 parts by weight, polypropylene resin having MI = 60 g / 10 min: 20 parts by weight was used and gold was previously prepared. With the mold opened to 8 mm, after injecting a resin with a volume corresponding to a thickness of 3 mm and closing the mold to 6 mm,
Cooled to obtain a molded product. The molded product was a good lightweight molded product in which a firm skin layer was formed on the surface and there was no silver or the like. The evaluation results of the molded products are shown in Table 1.

Example-4 In Example-1, a dry blend of 50 parts by weight of long fiber pellets A-2 and 50 parts by weight of polypropylene resin having MI = 30 g / 10 min was used as a molding raw material, and was preliminarily molded with gold. With the mold opened to 4 mm, after injecting a resin of a volume equivalent to 2 mm thickness, and closing the mold to 3 mm,
Cooled to obtain a molded product. The molded product was a good lightweight molded product in which a firm skin layer was formed on the surface and there was no silver or the like. The evaluation results of the molded products are shown in Table 1.

Comparative Example-1 In Example-1, as the forming raw material, MI = 10 g /
A molded product was obtained according to Example-1, except that short fiber reinforced pellets having a glass fiber content of 40% by weight and a weight average fiber length of 0.45 mm were used for 10 minutes. The molded product was not a lightweight molded product in which sink marks were generated on the surface. The evaluation results of the molded products are shown in Table 1. Comparative Example-2 In Comparative Example-1, foaming agent masterbatch pellets [POLYSLEN TS-182 (manufactured by Eiwa Chemical Industry Co., Ltd.): foaming agent 30% by weight] were used as short fiber reinforced pellets 10.
Comparative Example except that 4 parts by weight was added to 0 parts by weight
A molded product was obtained according to 1. Although the weight reduction of the molded product was achieved, it was not a good molded product because there was no skin layer. The evaluation results of the molded products are shown in Table 1.

Comparative Example-3 In Example-4, except that the dry blended product of long fiber pellet A-2: 15 parts by weight, polypropylene resin: MI = 30 g / 10 min: 85 parts by weight was used as a molding raw material. A molded body was obtained according to Example-4. A sink mark was generated on the surface and a lightweight body was not obtained. The evaluation results of the molded products are shown in Table 1. Comparative Example-4 In Example-4, 5 parts by weight of a foaming agent masterbatch pellet [Polysulene TS-182 (manufactured by Eiwa Chemical Industry Co., Ltd .: foaming agent 30% by weight)] was added as a molding raw material, According to a general injection molding method, the mold was fixed to a thickness of 3 mm, and a resin having a capacity corresponding to a thickness of 3 mm was injected to obtain a molded product. The evaluation results of the molded products are shown in Table 1.

Example-5 In Example-4, a cross-linked polyethylene foam having a thickness of 2 mm was set on one surface of the mold, and a resin having an equivalent volume to a thickness of 2 mm was injected while the mold was previously opened to 6 mm. A molded product was obtained according to the procedure of Example 4 except that the mold was closed to 5 mm and the molding temperature was 250 ° C. The obtained molded product had a light specific gravity (weight: 1486 g), was free from warpage and deformation, and was a good molded product in which the polyethylene foam on the surface was not crushed. Also, from the cut cross section of the molded product, it was found that the glass fiber reinforced polypropylene portion had a skin layer and the middle portion was a light-weight molded product having uniform voids.

Comparative Example-5 In Example-5, the mold thickness was set to 3 mm, and an amount corresponding to 3 mm thickness was injected by a general injection molding method without opening the mold. The obtained molded product weighs 2068 g.
The warp deformation was remarkable, and the polyethylene foam on the surface was in a crushed state in a considerable range centering on the gate portion.

[0048]

[Table 1]

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The method for producing a glass fiber reinforced thermoplastic resin lightweight molded article according to the present invention enables molding under a relatively low mold clamping condition as compared with conventional general injection molding, and particularly requires a foaming agent. In addition, the obtained molded product is lightweight and has excellent appearance such as surface condition and no warp deformation, and since a skin layer is formed on the surface, it has high strength and high rigidity in combination with the reinforcement of glass fiber. A molded product of is obtained.

Claims (5)

[Claims] 1. The glass fiber content is 20 to 80% by weight.
And the glass fibers are arranged parallel to each other and the length is 2
100 mm glass fiber-containing thermoplastic resin pellets (A), or the thermoplastic resin pellets (A) and a thermoplastic resin other than (A), and the total glass fiber content in the glass fiber-containing thermoplastic resin pellets (A) is A molding raw material composed of a mixture of 20 to 80% by weight is melt-kneaded, and a predetermined amount of molten resin is injected into a mold opened so as to be larger than the mold volume equivalent to the final molded product, A method for producing a glass fiber reinforced thermoplastic resin lightweight molded article, characterized in that the mold is closed to the volume of the final molded article before or after the completion of resin injection. 2. The method for producing a glass fiber reinforced thermoplastic resin lightweight molded article according to claim 1, wherein the lightweight molded article has a porosity of 10 to 80%. 3. A glass fiber reinforced thermoplastic resin lightweight molded article according to claim 1, wherein the thermoplastic resin is a polyolefin resin which may contain a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof. Method. 4. The weight average fiber length of the glass fibers is 1 to 20.
mm, content 20 to 80% by weight, porosity 10 to 8
The glass fiber reinforced thermoplastic resin lightweight molded article obtained by the production method according to claim 1, which has a skin layer of 0% and has no voids on the surface. 5. The glass fiber reinforced thermoplastic resin lightweight molded article according to claim 4, which has a specific bending strength of 80 MPa or more.