JPH09277335A - Manufacture of glass fiber reinforced thermoplastic resin lightweight molding and lightweight molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightweight molding excellent in surface properties, strength, and rigidity by a method in which the molding is composed of thermoplastic resin pellets containing specified glass fibers and another thermoplastic resin, and the content of the glass fibers in the pellets is specified. SOLUTION: A molding raw material of glass fiber-containing thermoplastic resin pellets A in which the content of the glass fibers is 20-80wt.%, and the fibers 2-100mm long are oriented, or of a mixture of the pellets A and another thermoplastic resin in which the content of the glass fibers of the pellets A is 5-80wt.%, preferably 20-80wt.% is melt-kneaded. The molten resin is injected into a mold which is closed to make its volume smaller than that of the final molding, and before or after the completion of the injection, the mold is opened to make its volume to correspond with that of the final molding.

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,
Specifically, it is lightweight, has a good surface condition, high strength and high rigidity by injection molding using specific glass fiber reinforced thermoplastic resin pellets or specific glass fiber reinforced thermoplastic resin pellets and a small amount of foaming agent. The present invention relates to a method for manufacturing a glass fiber reinforced thermoplastic resin lightweight molded product and the lightweight molded product.

[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 or a specific glass fiber-containing thermoplastic resin pellet and a small amount of a foaming agent to obtain surface characteristics, strength and rigidity. An object of the present invention is to provide a manufacturing method for manufacturing a light-weight molded product excellent in heat resistance and a lightweight molded product.

[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, the present invention has a skin layer having no voids on the surface, has no large hollow portion inside, and has continuous voids in which fibers are entangled, and is a lightweight molded article excellent in specific bending strength and the like. The following is the summary. (1) The glass fiber content is 20 to 80% by weight, the glass fibers are arranged in parallel with each other, and the length is 2 to 100 mm.
Glass fiber-containing thermoplastic resin pellet (A), or the glass fiber-containing thermoplastic resin pellet (A) and the glass in the glass fiber-containing thermoplastic resin pellet (A), which is made of a thermoplastic resin other than (A) A molding raw material composed of a mixture having a fiber content of 5 to 80% by weight, preferably 20 to 80% by weight, is melt-kneaded and closed so as to be smaller than the mold volume equivalent to the final molded product. A method for producing a glass fiber reinforced thermoplastic resin lightweight molded product, which comprises injecting a molten resin into a mold and opening the mold to the volume of the final molded product before or after the injection of the resin is completed. (2) Further, the molding raw material is a mixture of 100 parts by weight of the molding raw material described in (1) above and 0.01 to 5 parts by weight of a foaming agent, which is subjected to injection molding. Similar to the method for manufacturing glass fiber reinforced thermoplastic resin lightweight molded products.

[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 component of a molding raw material. The thermoplastic resin used here is not particularly limited, and examples thereof include polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, polyester resin, polyacetal resin, polycarbonate resin, polyaromatic ether or Thioether resin, polyaromatic ester resin,
Examples thereof include polysulfone resin and acrylate resin.

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, random 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 obtained by bundling glass fibers with an appropriate sizing agent, preferably in a range of 100 to 10,000, more preferably 150 to 5,000.

Examples of the sizing agent include urethane-based, olefin-based, acrylic-based, butadiene-based, and epoxy-based sizing agents, and any of them can be used. Among these, urethane-based and olefin-based sizing agents are preferable. The urethane 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-containing thermoplastic resin pellets (A) can be produced by impregnating the thus bundled fiber bundle with a thermoplastic resin. The method for adhering and impregnating the glass fiber bundle with the resin is as follows. 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, it is difficult to reduce the weight of the molded product even if the production method of the present invention is used, the mechanical strength is not sufficient, the warpage may be large, and the fiber length may be 100 mm. If it exceeds 300, the injection molding becomes difficult, and the dispersibility of the glass fiber and the surface characteristics of the molded product may decrease. 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) can be used alone, or a mixture with a thermoplastic resin other than (A) can be used. . In this case, it is necessary that the content of the glass fiber in the pellet (A) is 5 to 80% by weight, preferably 20 to 80% by weight based on the whole forming raw material. (A) in this case
There is no particular limitation on the thermoplastic resin other than the above, and the shape thereof such as commercially available general-grade pellets, granules, and powders is not limited, but pellets are preferably used.

In the method for producing a lightweight molded article of the present invention, talc, mica, calcium carbonate, glass fiber milled fiber, carbon fiber, magnesium sulfate fiber, potassium titanate fiber, titanium oxide fiber, organic fiber, etc. are reinforced. Examples thereof include pellets containing an agent and a filler, antioxidants, antistatic agents, flame retardants, pigments, dispersants, and the like.

In the method for producing a glass fiber reinforced lightweight molded product of the present invention, the above-mentioned compound is usually used as a molding raw material and is 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 impregnation of the resin into the glass fiber bundle is not sufficiently carried out, and undisentangled fibers may remain in the molded product. As the glass fiber-containing thermoplastic resin pellet (A), pellets having different glass fiber lengths or pellets having different glass fiber contents can be mixed and used as necessary.

As a method for melting and kneading the molding raw material and injecting it, the molding raw material is put into the heating cylinder of the molding machine, heated and melted, and then 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, the molding raw material is melt-kneaded, and the molten resin is injected into a closed mold so that the volume of the final molded product is smaller than that of the final molded product. It is possible to manufacture a light-weight molded product by a molding method in which the volume of the final molded product is increased. In this case, the first mold closing condition and the final mold opening condition also depend on the glass fiber content of the forming raw material, the fiber length, or the porosity of the target molded product (specific gravity of the molded product). And can be set appropriately. Further, the timing of opening 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.

Further, the cavity is composed of a fixed mold, a movable mold, and an operating core disposed inside the movable mold so as to be able to move forward or backward independently in the same direction as the moving direction of the movable mold. A part formed of the fixed mold, the movable mold and the operating core, and by moving the operating core forward or backward to make the volume of the cavity variable, use an end forming part in the final molded product. Molding may be performed by enlarging the removed portion. That is, the molten resin is injected into the closed mold, immediately before the injection of the resin is completed and the resin is filled into the closed mold, or after the resin is filled and the end of the final molded product is formed, The molding may be performed by retracting the operating core so that the cavity portion is in a state equivalent to the final molded product. Further, the molten resin is injected into the closed mold, and before or simultaneously with the completion of the injection of the resin, the operating core is once advanced so that the resin is filled in the mold, and the resin is simultaneously filled. Alternatively, after the resin is filled and the end of the final molded product is formed, the operating core may be retracted so that the cavity portion is in a state equivalent to the final molded product. According to this method, the resin can be injected at a low injection pressure, so that it is possible to effectively prevent breakage and orientation of the fiber which is likely to occur during injection filling. The operating core is once advanced so that the resin is filled in the mold. In this case, the distance to be advanced is usually 0.1 to
It is better to set the range to 50 mm. In particular, the range of 0.1 to 10 mm is preferably used from the viewpoint of preventing appearance defects such as flow marks from occurring due to air entrainment on the surface of the molded product. The speed of advance is usually appropriately selected from the range of 0.5 to 30 mm / sec.

The term "end portion" as used herein refers to a portion of the final molded product other than the portion formed by the retreat of the operating core. By forming such an end portion prior to the retreating of the operating core, The shape of the end is already formed even when the retreat of the motion core is started, and the final molded product has a good end face appearance and a shape that is faithful to the mold shape without being affected by the retraction of the motion core. Can be obtained. The speed at which the operating core is retracted varies depending on the molding raw material such as the resin used or the shape of the final molded product, but is usually selected in the range of 0.1 to 10 mm / sec. Furthermore, the speed does not necessarily have to be constant, and the speed may be gradually increased from the beginning of the backward movement.

Further, instead of stopping at the position corresponding to the final molded product for the purpose of retreating the operating core, the operating core is once retracted to a position larger than the final molded product equivalent volume, and then the final molded product equivalent volume is reached. Alternatively, a method of advancing the operating core in reverse and compressing it may be adopted. The melt-kneaded product of the resin injected into the mold is preferably in a state where glass fibers are entangled with each other, and the molten resin injected by this entanglement becomes a molten resin state having expandability in the mold. Next, the mold is opened so as to have the volume of the final molded product, and the final molded product is obtained by cooling. In addition, in the production method of the present invention, additives such as a stabilizer, an antistatic agent, a weathering agent, and a coloring agent may be added as long as the purpose is not impaired. Furthermore, in the method for manufacturing a lightweight molded product of the present invention, at least one surface of a molding die is preliminarily or fully fitted with a foam material, a fibrous material such as a nonwoven fabric, and a skin material such as a printed resin film. It can also be molded.

Further, in the method for producing a lightweight molded article of the present invention, the glass fiber-containing thermoplastic resin pellets (A) or the glass fiber-containing thermoplastic resin pellets (A) and thermoplastics other than (A) are used. A compounding material containing 100 to 1 part by weight of a mixture of a foaming agent and 0.01 to 5 parts by weight of a foaming agent is used as a molding raw material. When no foaming agent is added, when the mold is retracted and the cavity is expanded, the cavity becomes a negative pressure state, stable expansion is not performed, and the surface of the molded product becomes wavy and loses smoothness. However, by mixing a small amount of foaming agent, the gas generated by decomposition due to heat causes
It is possible to effectively prevent a negative pressure state in the cavity. The preferable amount of the foaming agent varies depending on the kind of the foaming agent and the kind or amount of the fiber contained in the raw material used for molding, but generally, when the fiber amount is 30 to 80% by weight, the foaming agent is used for molding. 0.0 for 100 parts by weight of raw material
1 to 0.8 parts by weight, when the amount of fiber is 20 to 30% by weight, similarly, it is 0.05 to 1.5 parts by weight, and the amount of fiber is 10 to 10.
In the case of 20% by weight, it is similarly selected from the range of 0.1 to 5 parts by weight.

The type of the foaming agent is not particularly limited, but it is necessary that it be decomposed by heat to generate a gas. Specifically, oxalic acid derivatives, azo compounds, hydrazine derivatives, semicarbazides, azides, nitroso compounds,
Triazole, urea and related compounds, nitrites, hydrides, carbonates, bicarbonates and the like are used. When the amount of the foaming agent is less than 0.01 part by weight, a sufficient amount of gas is not generated, and when the mold is retracted and the cavity is expanded, it is possible to eliminate the negative pressure in the cavity. Can not. Also, the effect of assisting expansion is small. If the amount exceeds 5 parts by weight, the amount of gas in the cavity becomes too large, and uneven distribution of voids may occur in the molded product, or large hollow parts may occur, resulting in a decrease in mechanical strength.

The lightweight molded article of the present invention has a glass fiber content of 5 to 80% by weight, preferably 20 to 80% by weight, more preferably 20 to 70% by weight. The porosity is 10 to 80%, preferably 20 to 70%. 10
If it is less than 80%, there is no effect of weight reduction, and if it exceeds 80%, it becomes difficult to form a skin layer having no voids reliably, and the strength may become 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 20 m.
m, preferably 1.5 to 15 mm, more preferably 2.
It is 0 to 12 mm. The glass fiber length in the molded product is 1 mm
If it is less than 2, the expandability of the molten resin is low, it is difficult to secure the porosity, and the strength of the molded product is not sufficient,
Even if it exceeds 0 mm, this has little effect on the strength,
On the contrary, it is necessary to make the molding conditions mild, the molding time is long, and the productivity is lowered, which is not practical. Further, the lightweight molded product of the present invention has a specific bending strength (bending strength / specific gravity) of 80
MPa or more, preferably 90 MPa or more, more preferably 100 MPa or more. Such a specific strength of bending is achieved by forming a skin layer and reinforcing a specific length of glass fiber.

According to the manufacturing method of the present invention, various lightweight molded products can be manufactured. The glass fiber reinforced thermoplastic resin lightweight molded product according to the present invention is not particularly limited in shape and size, but is preferably a plate-shaped molded product, particularly a plate-shaped molded product of 30 mm or less, or a molded product. included. Specifically, it is as lightweight as a helmet storage box for automobile parts (for example, instrument panel core, bumper beam, door step, roof rack, rear quarter panel, air cleaner case, sunshade, etc.) and a helmet storage box. Various box-shaped objects used in places where impact resistance and strength are required, home appliance parts, building members (for example, concrete panels (concrete formwork), cable troughs, wall materials,
Floor materials, etc., unit bath floor materials, water pans, etc.

[0041]

[Production Example 1]

Die: It is attached to the tip of the extruder, and 5 rods are arranged linearly in the impregnation section. (Manufactured by a method using an apparatus in accordance with JP-A-3-183531, FIG. 2.) Fiber bundle: glass fiber having a fiber diameter of 13 μm, surface-treated with γ-aminopropyltriethoxysilane, was treated with a urethane-based sizing agent for 170 minutes. Pre-heating temperature: 200 ° C Thermoplastic resin: 230 ° C, 2.16 kgf melt index (hereinafter simply referred to as MI) = modified polypropylene containing maleic anhydride containing 1.0% by weight of 60 g / 10 min. Temperature: 240 ° C. Rod: 5, 6 mm (diameter) × 3 mm (length) Inclination angle: 25 ° C. Under the above conditions, the fiber bundle is fed into a die while adjusting the amount of the fiber bundle between the tension rolls, impregnated, and cooled. The glass fiber content is 41% by weight and the length is 2
A 0 mm glass fiber-containing pellet (hereinafter referred to as long fiber pellet A-1) was 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 of 97% by weight
Glass rovings were manufactured. [Polypropylene-based aqueous emulsion: maleic anhydride content 5% by weight,
[η]: 80 parts by weight of 0.20 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 form an emulsion. ]. Using the obtained roving, according to Production Example 1, the glass fiber content was 69% by weight,
A glass fiber-containing pellet having a length of 12 mm (hereinafter referred to as long fiber pellet A-2) was manufactured.

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 conducted by the following methods. (A) Evaluation of molded product: Visual evaluation of molded product (b) Flexural strength and flexural modulus: Measured in accordance with JIS K-7203.

Specific strength of bending = bending strength / specific gravity Specific elasticity of bending = bending elastic modulus / specific gravity (c) Weight average glass fiber length in molded product: after ashing the molded product, use a universal projector The glass fiber was photographed at a magnification of 10 times, about 3000 fibers were measured with a digitizer, and the average value was obtained. [Example 1] Using long fiber pellet A-1 as a forming raw material,
An injection molding machine (manufactured by Mitsubishi Heavy Industries, Ltd .: 850 MGW, equipped with an Idemitsu compression unit) was used, and a resin temperature was 280 ° C. and a mold (a flat plate having a thickness of 400 mm × 800 mm × tmm) was used. A resin having a capacity corresponding to a thickness of 3 mm was previously injected with the mold opening of 3 mm, the mold was opened to 6 mm, and a lightweight molded product was obtained after cooling. A solid skin layer is formed on the surface of the molded product, there is no silver etc.,
In addition, the inside was a good lightweight molded product having no large hollow and uniformly expanding. Table 1 shows the evaluation results of the void ratio of the molded product, the weight average glass fiber length in the molded product, the evaluation of the molded product, the specific gravity, the bending specific strength of the molded product, and the bending specific elastic modulus.

[0044]

[Table 1]

Example 2 In Example 1, as the forming raw material, long fiber pellets A-2: 80 parts by weight, MI = 6
0 g / 10 min polypropylene resin: Using a dry blend with 20 parts by weight, in a state where the mold opening was 2.5 mm in advance, a resin having a volume equivalent to 2.5 mm was injected, and then the mold was moved to 7 A lightweight molded product was obtained in the same manner as in Example 1 except that the product was opened to 0.5 mm and cooled. 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 long-fiber pellet A-2: 50 parts by weight, a dry blended product of polypropylene resin: 50 parts by weight of MI = 30 g / 10 minutes: 50 parts by weight was used, and a mold was preliminarily set to 3 mm. Open so that
2 seconds after injecting a resin of a volume corresponding to a thickness of 3 mm,
The mold was opened and cooled to 5.5 mm to obtain a lightweight 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 molding raw material, MI was used.
= 10 g / 10 minutes, a glass fiber content of 40% by weight, and a molded product was obtained according to Example 1 except that short fiber reinforced pellets having a weight average fiber length of 0.45 mm were used. The molded product was not a lightweight molded product with sink marks on the surface. The evaluation results of the molded products are shown in Table 1. [Comparative Example 2] In Comparative Example 1, blowing agent masterbatch pellets [Polythrene TS-182 (manufactured by Eiwa Chemical Industry Co., Ltd .: blowing agent content = 30% by weight)] were used with respect to 100 parts by weight of short fiber reinforced pellets. A molded product was obtained according to Comparative Example 1 except that 4 parts by weight was added. Although the weight reduction was achieved, it was not a good molded product having a large hollow portion inside and no skin layer. The evaluation results of the molded products are shown in Table 1. [Comparative Example 3] Example 3 was carried out except that a dry blended product of 20 parts by weight of long fiber pellets A-2 and 80 parts by weight of a polypropylene resin having MI = 30 g / 10 min was used as a molding raw material. A molded body was obtained according to Example 3. 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 3, as a molding raw material, a blowing agent masterbatch pellet [POLYSLEN TS-182
(Manufactured by Eiwa Chemical Industry Co., Ltd .: content of foaming agent = 30% by weight) was added to 5 parts by weight and fixed to a mold thickness of 3 mm by a general injection molding method, which corresponds to a thickness of 3 mm. A volume of resin was injected to obtain a molded product. The evaluation results of the molded products are shown in Table 1. [Example 4] It was carried out by the following raw materials, devices, conditions, operations and the like. (1) Molding raw material: Foaming agent masterbatch pellet [Polysulene EE-206 (manufactured by Eiwa Chemical Industry Co., Ltd.): foaming agent content = 100 parts by weight of the long fiber pellet A-1 obtained in Production Example 1 above. 20% by weight] in an amount of 0.5 part by weight. (2) Mold: Cavity part is 800mm in length x 4 in width
A test plate of a rectangular plate test type of 00 mm (variable thickness), which can move forward or backward independently in the same direction as the moving direction of the movable mold, at a position 3 mm from the inner end face of the movable mold. It is arranged. See FIG.

[0046]

[FIG. 1] (3) Molding machine: Injection molding machine (manufactured by Mitsubishi Heavy Industries, Ltd.) An Idemitsu IPM unit is mounted to move the mold. (4) Molding conditions Molding temperature (cylinder temperature): 260 ° C Mold temperature: 50 ° C Injection pressure: 80 kg / cm ² G Injection speed: 60% Resin filling time: 3.2 seconds Holding pressure: 30 kg / cm ² G Hold Time: 3.0 seconds Cooling time: 120 seconds (5) Molding operation The molding operation was performed according to the following procedure.

In the injection molding machine, the movable mold was moved and the mold was closed in the same manner as in normal injection molding. Next, the operating core is advanced so that the clearance between the fixed mold and the operating core in the cavity becomes 4 mm,
Held. From the injection unit, the molten forming raw material was injected into the mold to completely fill the initial cavity.

Immediately after the end of filling, the retreat of the operating core was started. The reverse speed is 0.8 mm / sec and the reverse distance is 8 m.
By setting m, the thickness of the final cavity is 12m.
The retreat was completed as m. After the elapse of the cooling time, the movable mold was retracted, the mold was opened, and the molded product was taken out. (6) Evaluation results The surface of the obtained molded product was smooth, and the end surface of the molded product was faithful to the shape of the mold.

The wall thickness of the final product was 12 mm, and the wall thickness was tripled. The specific gravity of the final product was about 0.4. [Comparative Example 5] In Example 4, the operating core was retracted from the beginning to the state of the final product, and the thickness was about 1
The resin filling amount was optimized so that it was 2 mm, and the resin was filled in the cavity. (1) Evaluation results The surface of the obtained molded product was smooth, and the end surface of the molded product was faithful to the shape of the mold.

The wall thickness of the final product was 12 mm. The final product was about 1.08, and no lightweight product was obtained.

[Brief description of drawings]

FIG. 1 is a schematic view schematically showing injection molding in Example 4.

The method for producing a glass fiber reinforced lightweight thermoplastic resin lightweight molded product according to the present invention enables molding under a relatively low mold clamping condition as compared with conventional general injection molding, and a foaming agent It is unnecessary and requires a small amount even if used, and the obtained molded product is lightweight, and the fibers are uniformly intertwined inside, and the appearance such as the surface condition is excellent,
Moreover, since the skin layer is formed on the surface, it has high strength and high rigidity in combination with the reinforcement of the glass fiber. Further, it is possible to obtain a final molded product that has a good appearance of the end surface of the molded product and is faithful to the shape of the mold.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B29K 105: 12 309: 08

Claims (7)

[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 glass fiber-containing thermoplastic resin pellets (A) and a thermoplastic resin other than the (A) thermoplastic resin pellets (A) Molding raw material composed of a mixture having a glass fiber content of 5 to 80% by weight is melted and kneaded, and a molten resin is placed in a closed mold so as to be smaller than the mold volume equivalent to the final molded product. And a mold is opened up to the volume of the final molded product before or after the injection of the resin is completed, and a method for producing a glass fiber reinforced thermoplastic resin lightweight molded product. 2. 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 glass fiber-containing thermoplastic resin pellets (A) and a thermoplastic resin other than the (A) thermoplastic resin pellets (A) Molding raw material composed of a mixture having a glass fiber content of 20 to 80% by weight is melted and kneaded, and a molten resin is placed in a closed mold so as to be smaller than the mold volume equivalent to the final molded product. And a mold is opened up to the volume of the final molded product before or after the injection of the resin is completed, and a method for producing a glass fiber reinforced thermoplastic resin lightweight molded product. 3. The molding raw material 100 according to claim 1 or 2.
The glass fiber reinforced thermoplastic resin lightweight molded article according to claim 1 or 2, wherein a mixture of 0.01 to 5 parts by weight of a foaming agent is used for injection molding. 4. 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%. 5. The lightweight glass fiber reinforced thermoplastic resin 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. Manufacturing method of molded products. 6. The weight average fiber length of the glass fibers is 1 to 20.
mm, content 5-80% by weight, porosity 10-80
%, And a glass fiber reinforced thermoplastic resin lightweight molded product characterized by having a skin layer having no voids on the surface. 7. The glass fiber reinforced thermoplastic resin lightweight molded article according to claim 6, which has a specific bending strength of 80 MPa or more.