JPH1149937A - Gas-assist injection molding resin composition and process for molding same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain blow moldings having a good appearance and uniformity by using resin compositions excellent in gas-assist injection molding properties. SOLUTION: With the use of resin compositions comprising, based on (A) 100 pts.wt. polybutylene terephthalate resin(PBT resin), (B) 5-100 pts.wt. at least one resin selected from a polycarbonate resin and a polyethylene terephthalate resin(PET resin) and (C) 5-80 pts.wt. fibrous or non-fibrous filler, blow moldings 6 are obtained by gas-assist injection molding. The PBT resin and PET resin may be copolymer resins having 5-40 mole% comonomer units, respectively. The resin compositions may contain 0.01-5 pts.wt., based art 100 pts.wt. PBT resin, phosphorus-based compound (D).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stable moldability,
The present invention relates to a resin composition for gas-assisted injection molding (hereinafter, simply referred to as GAI molding) that provides a hollow molded article having an excellent appearance and a uniform thickness, a gas-assisted injection molding method using the resin composition, and a molded article.

[0002]

2. Description of the Related Art In GAI molding, a molten resin is injected and filled into a mold cavity and, during or after the injection is completed, the molten resin is arranged in a nozzle or a part of a mold provided at the tip of an injection machine. This is a molding method in which a pressurized gas such as nitrogen is injected into a molten resin in a mold cavity by a needle to form a hollow portion in a molded product. This GAI molding method is a molding technique that has recently received particular attention because it has features such as the occurrence of sink marks and warpage and the ability to produce molded articles at a low cost and light weight.

In recent years, demands for GAI molded products having characteristics such as mechanical strength, heat resistance, and chemical resistance have been increasing, and cases in which GAI molding of a crystalline thermoplastic resin (engineering plastic) is required. Has occurred.
In particular, GAI molding of a polybutylene terephthalate resin reinforced with an inorganic filler due to high mechanical strength and heat resistance is expected.

However, when a polybutylene terephthalate resin reinforced with an inorganic filler is GAI-molded, it has high crystallinity. Therefore, due to the flow deformation of the molten resin before gas injection, multiple wrinkled hesitation marks are formed on the molded product. In addition to poor surface appearance such as oil wrinkles and uneven thickness, the inorganic filler is prominent on the surface of the hollow molded product, deteriorating the appearance characteristics. Furthermore, gas leakage occurs from the thin part,
In some cases, a hollow molded article having high uniformity cannot be obtained.

JP-A-58-91761 discloses that poly (alkylene terephthalate) resin is imparted with thermal stability by adding bis (alkylphenyl) pentaerythritol diphosphite. JP-A-56-152863 discloses a resin composition in which bis (2,6-di-t-butyl-4-alkylphenyl) pentaerythryl diphosphite is added to a synthetic resin. Further, JP-A-63-2
No. 65949 discloses that a polymer blend composed of a polyester resin (such as polybutylene terephthalate resin) and a polycarbonate resin is treated with bis (2,2).
A resin composition to which (6-di-t-butyl-4-alkylphenyl) pentaerythryl diphosphite is added is disclosed. However, these documents do not mention GAI molding.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a GAI molding method for obtaining a uniform hollow molded article having no surface of the filler, having a good surface appearance, and having a small uneven thickness. It is to provide a resin composition and a molding method. Another object of the present invention is to provide a resin composition and a molding method useful for efficiently producing a hollow molded article having high uniformity, mechanical strength and heat resistance while maximizing the advantages of the GAI molding method. Is to provide. Still another object of the present invention is to provide a uniform hollow molded article having excellent surface appearance characteristics (surface uniformity).

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object. As a result, when a specific polybutylene terephthalate resin composition material containing a filler is used, a good surface appearance and uniform The present inventors have found that it is extremely suitable for obtaining a thick GAI molded product, and have completed the present invention. That is, the resin composition for gas-assisted injection molding of the present invention comprises (A) a polybutylene terephthalate resin, (B) a polycarbonate resin (B-1) and / or
Or polyethylene terephthalate resin (B-2)
And (C) a filler. The ratio of the component (A) to the component (B) is (B) / (A) = 5/100 to 100/1.
It is about 00 (parts by weight). (A) Polybutylene terephthalate resin or polyethylene terephthalate resin (B-
2) may be a copolymer resin having a comonomer unit. The ratio of component (A) to component (C) is (C) /
(A) = approximately 5/100 to 80/100 (parts by weight). In order to enhance molding stability, the resin composition may further contain (D) a phosphorus-based compound, if necessary.
In the present invention, a gas-assisted injection molding using the resin composition, a method of molding a molded article having a hollow portion, a hollow molded article formed of the resin composition, and molded by a gas-assist molding method is also provided. included.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the components of the resin composition of the present invention will be described in detail. [(A) Polybutylene terephthalate resin] The (A) polybutylene terephthalate resin (PBT resin) which is the base resin of the resin composition of the present invention contains at least terephthalic acid or an ester-forming derivative thereof (lower alcohol ester or the like). Dicarboxylic acid component and alkylene glycol having at least 4 carbon atoms (1,4-butanediol)
Or a polybutylene terephthalate resin obtained by polycondensing a glycol component containing an ester-forming derivative thereof. The PBT resin is not limited to the homo-PBT resin, but has a butylene terephthalate unit of 60 mol% or more (particularly 75 to
(About 95% by mole) (copolymerized PBT resin).

In the copolymerized PBT resin, the dicarboxylic acid component (comonomer component) other than terephthalic acid and its ester-forming derivative includes, for example, aromatic dicarboxylic acid components (isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, etc.). C _6-12 aryl dicarboxylic acid, etc.), aliphatic dicarboxylic acid component (C _4-16 alkyl dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, C _5-10 cycloalkyl dicarboxylic acid such as cyclohexane dicarboxylic acid) And their ester-forming derivatives. These dicarboxylic acid components can be used alone or in combination of two or more. Preferred dicarboxylic acid components (comonomer components) include aromatic dicarboxylic acid components (particularly C _6-10 aryl dicarboxylic acids such as isophthalic acid),
Aliphatic dicarboxylic acid components (particularly C _6-12 alkyl dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid) are included.

Examples of glycol components (comonomer components) other than 1,4-butanediol include aliphatic diol components such as alkylene glycols (ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexagonal glycol). _C2-10 alkylene glycols such as methylene glycol, neopentyl glycol and 1,3-octanediol, polyoxy _C2-4 alkylene glycols such as diethylene glycol, triethylene glycol and dipropylene glycol, etc.), cyclohexanedimethanol, hydrogenated bisphenol A, etc.], aromatic diol components [bisphenol A, aromatic alcohols such as 4,4'-dihydroxybiphenyl, and bisphenol A _C2-4 alkylene oxide] Side adducts (eg, bisphenol A ethylene oxide 2 mol adducts, bisphenol A propylene oxide 3 mol adducts, etc.), and ester-forming derivatives thereof. These glycol components can be used alone or in combination of two or more. Preferred glycol components (comonomer components) include aliphatic diol components (particularly, C _2-6
Polyoxy C _2-3 alkylene glycols such as alkylene glycol and diethylene glycol, and alicyclic diols such as cyclohexane dimethanol).

A homo-PBT resin or a copolymerized PBT resin produced by polycondensation using the compound as a monomer component is as follows:
Any of them can be used as the component (A) of the present invention. Homo P
The BT resin and the copolymerized PBT resin can be used alone or in combination of two or more. In addition, terminally modified PBT
It is also useful to use a resin (homo-PBT resin) in combination with a copolymerized PBT resin.

A preferred PBT resin is a copolymerized PBT resin containing a comonomer unit (modified PBT resin). The content of the comonomer unit in the copolymerized PBT resin is 5 to 40 mol%, preferably 10 to 30 mol%.
The range can be selected from the range of about 5 to 25 mol%. When such a copolymerized PBT resin is used, GAI
When resin is injected using molding, flow deformation before gas injection is small, good appearance is formed, and uneven thickness of the hollow molded body is small. Further, the comonomer unit of the copolymerized PBT resin includes an aromatic dicarboxylic acid residue (particularly at least isophthalic acid residue) and a residue of an aliphatic diol component (particularly at least C _2-10 alkylene glycol residue, polyoxy C _2-3 residue). Alkylene glycol residue). As the PBT resin, a thermoplastic branched PBT resin belonging to the category of a copolymerized PBT resin can also be used. The branched PBT resin is a polyester resin mainly composed of a so-called polybutylene terephthalate or a butylene terephthalate monomer and having a branched structure by a reaction with a polyfunctional compound. Examples of the polyfunctional compound include aromatic polycarboxylic acid components (trimesic acid, trimellitic acid, pyromellitic acid and alcohol esters thereof), polyol components (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc.). Can be exemplified.

The intrinsic viscosity of the PBT resin is, for example, 0.6 to 2 dl / g, preferably 0.7 to 2 at 25 ° C. and 0.5% by weight of o-chlorophenol as a solvent.
It is about 1.5 dl / g, especially about 0.7 to 1.0 dl / g.

A first feature of the present invention is that the PBT resin (A) is combined with at least one resin (B) selected from a polycarbonate resin (B-1) and a polyethylene terephthalate resin (B-2). The point is to match. By adding and blending this specific resin (B) alone or in combination with the (A) PBT resin, the GAI molded article has less multi-wrinkled hesitation marks and can be used in combination with the filler (C). It is possible to improve the appearance of the molded article.
In particular, since the polycarbonate resin is amorphous, PBT
By adding and compounding to the resin, the crystallization speed is reduced, the flow deformation of the resin before gas injection is significantly suppressed, a molded article having an excellent surface appearance is easily obtained, and the mold transferability is also improved. it can. Further, since the shrinkage rate of the polycarbonate resin itself is small, it is possible to suppress the sink phenomenon of the molded article.

[Polycarbonate Resin (B-1)] The polycarbonate resin (B-1) is prepared by reacting a dihydric phenol with a solvent method (ie, in a solvent such as methylene chloride in the presence of a known acid acceptor and a molecular weight modifier). It can be produced by a reaction with a carbonate precursor such as phosgene) or a transesterification reaction (reaction of a dihydric phenol with a carbonate precursor such as diphenyl cartonate).

Examples of the dihydric phenol include hydroquinone, 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) C _1-10 alkane, bis (4
Bisphenols such as -hydroxyphenyl) C _3-10 cycloalkane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) ether Or a substituted product thereof [for example, bis (3,5-dibromo-4-hydroxyphenyl) propane, bis (3,5-dichloro-4-
Halogenated bisphenols such as hydroxyphenyl) propane, and lower alkyl-substituted products corresponding to these halogen-substituted products]. These dihydric phenols can be used alone or in combination of two or more, and the polycarbonate resin may be a homopolymer using a single dihydric phenol or a copolymer using two or more dihydric phenols. Good.

Preferred dihydric phenols are bisphenols such as bis (4-hydroxyphenyl) C _1-8 alkane, especially 2,2-bis (4-hydroxyphenyl) propane, ie bisphenol A. Incidentally, the polycarbonate resin (B-1) may be a homopolycarbonate resin or a copolymerized polycarbonate resin obtained by substituting a part or all of bisphenol A with another dihydric phenol.

Further, the polycarbonate resin used in the present invention may be a thermoplastic random branched polycarbonate resin obtained by reacting a carbonate precursor with a polyfunctional aromatic phenol together with a dihydric phenol.

The viscosity of the polycarbonate resin used here is not particularly limited, and any of them may be used. However, a polycarbonate resin having high fluidity has good appearance.

[Polyethylene terephthalate resin (B-
2)] Similarly to the polycarbonate resin (B-1), a polyethylene terephthalate resin (PET resin) (B-2) is also preferably used. PET resin is a polyethylene obtained by polycondensation reaction of a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof and a glycol component containing at least C2 alkylene glycol (ethylene glycol) or an ester-forming derivative thereof. It is a terephthalate resin and is not limited to a homo PET resin, and may be a copolymer (copolymerized PET resin) containing 60 mol% or more (particularly about 75 to 95 mol%) of ethylene terephthalate units.

In the copolymerized PET resin, examples of the dicarboxylic acid component (comonomer component) other than terephthalic acid and its ester-forming derivative include, for example, aromatic dicarboxylic acid components (such as isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and diphenylether dicarboxylic acid). C _6-12 aryl dicarboxylic acid, etc.), aliphatic dicarboxylic acid component (C _4-16 alkyl dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, C _5-10 cycloalkyl dicarboxylic acid such as cyclohexane dicarboxylic acid) And the like, aromatic hydroxycarboxylic acids (such as hydroxybenzoic acid and hydroxynaphthoic acid), and ester-forming derivatives thereof. These dicarboxylic acid components can be used alone or in combination of two or more. Preferred dicarboxylic acid components (comonomer components) include aromatic dicarboxylic acid components (especially C _6-10 aryl dicarboxylic acids such as isophthalic acid) and aliphatic dicarboxylic acid components (especially C ₆ such as adipic acid, azelaic acid and sebacic acid). _-12 alkyldicarboxylic acid).

As glycol components (comonomer components) other than ethylene glycol, aliphatic diol components [for example, alkylene glycol (propylene glycol,
_C3-10 alkylene glycols such as trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol; polyoxy Cs such as diethylene glycol, triethylene glycol, and dipropylene glycol
_2-4 and alkylene glycol), cyclohexanedimethanol, and alicyclic diols such as hydrogenated bisphenol A], an aromatic diol component [bisphenol A,
Aromatic alcohols such as 4,4'-dihydroxybiphenyl, _C2-4 alkylene oxide adducts of bisphenol A (eg, ethylene oxide 2 mol adducts of bisphenol A, propylene oxide 3 mol adducts of bisphenol A, etc.)] Or an ester-forming derivative thereof. These glycol components can be used alone or in combination of two or more. Preferred glycol components (comonomer components) include aliphatic diol components (particularly, polyoxy C _2-3 alkylene glycols such as C _3-6 alkylene glycol and diethylene glycol, and alicyclic diols such as cyclohexane dimethanol). Homo PET resin and copolymerized PE
The T resins can be used alone or in combination of two or more.

Preferred PET resins are unmodified homo PET
Copolymerized PET containing resin and comonomer units
Resin (modified PET resin). In the copolymerized PBT resin, the content of the comonomer unit is 5 to 40 mol%,
Preferably, it can be selected from a range of about 10 to 30 mol%,
Usually, it is about 5 to 25 mol%. Furthermore, copolymerized PE
The comonomer unit of the T resin includes an aromatic dicarboxylic acid residue (particularly at least isophthalic acid residue) and a residue of an aliphatic diol component (particularly at least C _3-10 alkylene glycol residue, polyoxy C _2-3 alkylene glycol residue). ). Copolymer P
The ET resin includes an isophthalic acid copolymerized PET resin (isophthalic acid-modified PET resin) and the like. In addition, PET
As the resin, similarly to the branched PBT resin, a thermoplastic PET resin having a branched structure obtained by using an aromatic polycarboxylic acid component and / or a polyol component can also be used.

The intrinsic viscosity of the PET resin is, for example, 0.5 to 2 l / g, preferably 0.65 to 5 at 25 ° C. at a concentration of 0.5% by weight using orthochlorophenol as a solvent.
1.3 dl / g, especially about 0.7 to 1.1 dl / g.

In the present invention, any of the polycarbonate resin (B-1) and the polyethylene terephthalate resin (B-2) may be used as the component (B), or both may be used in combination. Both polycarbonate resin (B-1) and polyethylene terephthalate resin (B-2) are excellent in GAI moldability, appearance characteristics and uniformity of molded products, even when combined with filler (C). Therefore, the type of the component (B) depends on the desired properties and the like.
You can use them properly. For example, when sink and warpage of the molded article are conspicuous even by GAI molding, a polycarbonate resin is preferable, and when hydrolysis resistance and weather resistance are required, a polyethylene terephthalate resin is preferable.

The amount of the component (B) can be selected within a range that does not impair the GAI moldability and the like.
5 to 100 parts by weight relative to 0 parts by weight (for example, 10 to 1 parts by weight)
00 parts by weight), preferably 10 to 75 parts by weight (for example,
15 to 50 parts by weight), especially about 10 to 50 parts by weight. If the amount of the component (B) is small, it is difficult to suppress surface appearance defects such as hesitation marks and oil wrinkles due to flow deformation of the molten resin before gas injection during GAI molding. If it is too much, the molding cycle increases, the releasability decreases, and the like, and problems in GAI molding are likely to occur.

[(C) Filler] The filler as the component (C) functions as a reinforcing agent or a reinforcing agent and is effective for obtaining a GAI hollow molded article having high mechanical strength, impact strength and heat resistance. . As the filler (C), at least one filler selected from a fibrous filler (C-1) and a non-fibrous filler (C-2) can be used, and a mixture of both can be used. Good. Although an organic filler can be used as the filler (C), an inorganic filler is usually used.

Examples of the fibrous filler (C-1) of the filler (C) include glass fiber, asbestos fiber, carbon fiber, and ceramic fiber (silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride). Inorganic fibrous substances such as fibers, boron fibers, potassium titanate fibers, etc., whiskers, and metal fibers (stainless steel, aluminum, titanium, copper, brass, etc.). Typical fibrous fillers are glass fibers or carbon fibers.
In addition, a high melting point organic fibrous substance (polyamide such as aromatic polyamide, fluororesin, acrylic resin, etc.) can be used in the same manner as the inorganic fibrous filler.

Examples of the non-fibrous filler (C-2) include carbon black, silica, quartz powder, glass beads, glass powder, silicates (calcium silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, etc.). ), Metal oxides (iron oxide, titanium oxide, zinc oxide, alumina, etc.), metal carbonates (calcium carbonate, magnesium carbonate, etc.), metal sulfates (calcium sulfate, barium sulfate, etc.), ceramics (polysilicon carbide, nitrided) Silicon, boron nitride, etc.) and various metal powders. In addition, powdery particles of a high melting point resin or a crosslinked resin (for example, polyamide, fluorine resin, crosslinked acrylic resin, crosslinked amino resin, etc.) can also be used. Examples of the plate-like filler in the non-fibrous filler (C-2) include mica, glass flake, various metal foils, and the like.

Of these fillers, fibrous fillers (C-
As 1), glass fiber and carbon fiber are preferable. As the non-fibrous filler (C-2), the average primary particle size is 20 μm
The following (for example, 0.5 to 15 μm, preferably 1.0 to
Pulverized or plate-like fillers (for example, glass beads, milled fiber, talc, mica, and kaolin) are preferred.

These fillers can be used alone or in combination of two or more. The fibrous filler (C-1) and the non-fibrous filler (C-2) may be used in combination. . Combinations of fibrous fillers (particularly glass fibers or carbon fibers) and non-fibrous fillers (particularly powdery or plate-like fillers having an average primary particle diameter of 20 μm or less) provide particularly high mechanical strength and dimensional accuracy. This is preferable in obtaining a hollow molded article having good appearance characteristics.

In using these fillers, a sizing agent or a surface treating agent may be used if necessary. As a sizing agent or a surface treatment agent, for example, an epoxy compound,
Functional compounds such as isocyanate compounds, silane compounds and titanate compounds are included. The filler may be subjected to a surface treatment or a convergence treatment in advance, and a sizing agent or a surface treatment agent may be added together with the filler at the time of material preparation.

The amount of the filler (C) can be selected within a range that does not impair the mechanical strength and heat resistance of the hollow molded article.
The amount is 5 to 80 parts by weight, preferably 10 to 50 parts by weight, particularly about 10 to 40 parts by weight based on 100 parts by weight of the component (A). If the amount of the filler is too large, the surface properties of the molded article are deteriorated. If the amount is too small, the mechanical strength and heat resistance cannot be sufficiently improved. The amount of the sizing agent or the surface treatment agent used is 10% by weight or less based on the filler (for example,
0.01 to 10% by weight), preferably about 0.05 to 5% by weight.

When the resin composition composed of the components (A) and (B) and the filler (C) are combined, a high G
Not only AI moldability is obtained, but also (C) a hollow molded body having good appearance characteristics (surface uniformity) without protruding filler, and having high mechanical strength and impact strength. In addition, it is possible to obtain a hollow component having a uniform thickness with little unevenness in thickness without deteriorating surface appearance characteristics due to hesitation marks, oil wrinkles, and the like.

[Other additives] The composition of the present invention comprises:
A general additive added to a thermoplastic resin or the like may be added. Examples of additives include stabilizers (antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, etc.), antistatic agents, flame retardants, lubricants, release agents, coloring agents such as dyes and pigments, plastics, and the like. And the like. In particular, the addition of an antioxidant and a release agent for improving heat resistance and thermal stability is effective.

In particular, the addition of the phosphorus compound (D) is highly effective in suppressing the transesterification reaction between the (A) PBT resin and the (B) polycarbonate resin, maintains high thermal stability, and allows gas injection. This is effective because it suppresses the decomposition of the previous molten resin. Therefore, when the resin composition containing the (D) phosphorus-based compound is used, a stable GAI can be obtained over a long period of time.
Molding becomes possible. As the (D) phosphorus compound, mainly organic phosphites and metal phosphates are suitable. Examples of the compound having a spiro ring or the like among the organic phosphites include the following compounds. Dialkylpentaerythryl diphosphite [for example,
Di-C _{2-18 alkylpentaerythryl} diphosphite such as distearyl pentaerythryl diphosphite], diphenylpentaerythryl diphosphite, bis (alkyl-substituted phenyl) pentaerythryl diphosphite [ For example, a screw (2,4-
Di-t-butylphenyl) pentaerythryl diphosphite, bis (2,6-di-t-butylphenyl)
Bis (diC _1-6 alkylphenyl) pentaerythryl diphosphite such as pentaerythryl diphosphite; bis (2,6-di-t-butyl-4-methylphenyl) pentaerythryl diphosphite Fight,
Bis (2,6-di-t-butyl-4-ethylphenyl)
Bis (2,6-diC _1-6 alkyl-4-C _1-4 alkylphenyl) pentaerythryl diphosphite such as pentaerythryl diphosphite],
Tetrakis (phenyl) -4,4'-biphenylene phosphite, tetrakis (alkyl-substituted phenyl) -4,
4'-biphenylene phosphite [eg, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene phosphite, tetrakis (2,6-di-t-
Butylphenyl) -4,4'-biphenylene phosphite and other tetrakis (di C _1-6 alkylphenyl)-
4,4'-biphenylene phosphite; tetrakis (2,6-di-t-butyl-4-methylphenyl)-
Tetrakis (2,6-diC _1-6 alkyl-4-C _1-4 alkylphenyl) -4,4′-biphenylene phosphite] such as 4,4′-biphenylene phosphite.

Examples of the metal phosphate include alkaline earth metal phosphates such as calcium monophosphate and magnesium phosphate, and alkali metal phosphates such as sodium monophosphate and potassium monophosphate. Salts, and hydrates thereof (monohydrate and the like). These phosphorus compounds can be used alone or in combination of two or more.

The addition amount of the phosphorus compound (D) is, for example,
0.01 to 5 parts by weight based on 100 parts by weight of PBT resin (A)
Parts by weight, preferably about 0.01 to 2.0 parts by weight, more preferably about 0.05 to 0.8 parts by weight. When the phosphorus-based compound is not added or the amount is small, the thermal stability is lowered by the transesterification reaction as described above, and when the amount exceeds 5 parts by weight, the influence of coloring and gas derived from the additive is large. And the quality of the surface appearance of the molded body is likely to be deteriorated.

The phosphorus compound (D) is effectively used in combination with an antioxidant represented by a hindered phenol in order to further enhance the thermal stability. Antioxidants,
Not limited to hindered phenols, phosphorus-based, amine-based,
It may be a sulfur-based, hydroquinone-based, or quinoline-based antioxidant. As the antioxidant, hindered phenols and phosphorus-based antioxidants are usually used.

Hindered phenols include, for example,
2,6-di-t-butyl-p-cresol; 1,3,5
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene; 2,2 '
-Methylenebis (4-methyl-6-t-butylphenol
4,4'-methylenebis (2,6-di-t-butyl
Phenol), 4,4'-butylidenebis (3-methyl
Alkylenebis such as -6-t-butylphenol)
(T-butylphenol) s; 1,6-hexanediol
Rubis [3- (3,5-di-tert-butyl-4-hydro)
C, such as [xyphenyl) propionate]_2-10Archire
Diol-bis [3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate], glycerin
Tris [3- (3,5-di-t-butyl-4-hydroxy)
C such as [cyphenyl) propionate]_3-8Alkylene
Triol-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionate];
Thritol tetrakis [3- (3,5-di-t-butyl)
-4-hydroxyphenyl) propionate]
_4-8Alkylenetetraol-bis [3- (3,5-di
-T-butyl-4-hydroxyphenyl) propione
G]; triethylene glycol-bis [3- (3-t-
Butyl-5-methyl-4-hydroxyphenyl) propyl
Onate] and other di- or trioxy C_2-4Alkylenedi
All-bis [3- (3,5-di-tert-butyl-4-h)
Droxyphenyl) propionate]; n-octadecy
3- (4 ', 5'-di-t-butylphenol)
Lopionate, n-octadecyl-3- (4'-hydro
Xy-3 ', 5'-di-t-butylphenol) propy
Onate, stearyl-2- (3,5-di-t-butyl)
Long length such as -4-hydroxyphenol) propionate
(T-butylphenol) propyl having a chain alkyl group
Onates; distearyl-3,5-di-t-butyl-
Phosphate S such as 4-hydroxybenzylphosphonate
Ters are included.

Examples of the phosphorus-based antioxidants include triphenyl phosphite, trisnonylphenyl phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, and 4,4'- Butylidenebis (3-methyl-6-t-butylphenyl) ditridecyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (2-t-butyl-4-
Methylphenyl) phosphite and the like. These antioxidants can be used alone or in combination of two or more.

The content of the antioxidant is, for example, PB
0.01 to 1 part by weight, preferably 0.05 to 0.7 part by weight (particularly 0.05 to 0.1 part by weight) based on 100 parts by weight of the T resin.
(About 5 parts by weight).

The resin composition for GAI of the present invention can be prepared by using the equipment and method generally used as a conventional method for preparing a resin composition,
That is, it can be easily prepared by dry- or wet-mixing (particularly, melt-kneading) the components of the resin composition of the present invention. For example, (1) a method of collectively mixing predetermined amounts of the constituent components of the composition of the present invention and melting and kneading with a single-screw or twin-screw extruder to obtain pellets of a desired composition; (2) two raw material inlets With a single-screw or twin-screw extruder having the above, the resin, stabilizer, pigment component, etc. are charged and melt-kneaded from the first charging port, and then the filler is charged from the second raw material charging port and melted. The resin composition of the present invention can be prepared by, for example, a method of kneading to obtain pellets of a desired composition.

In the method of the present invention, the step of melting the resin composition and injecting and filling the molten resin into the mold cavity, and the step of injecting nitrogen or the like by a nozzle or a needle during or after the injection of the molten resin. A molded article having a hollow portion is formed by a gas-assisted injection molding method including a step of injecting a pressurized gas into a molten resin. In the injection filling step, the molten resin is injected and filled in an amount smaller than the cavity volume according to the volume of the hollow portion of the molded body. In the injection filling step, as shown in FIG. 3, when the injection resin 2 is non-uniformly injected into the mold cavity 1 through the gate 3 and undergoes flow deformation, hesitation marks and the like are generated on the molded product, and the appearance characteristics are deteriorated. Let it. On the other hand, when the resin composition of the present invention is used, as shown in FIG. 2, the injection resin 2 does not flow and is deformed and is injected into the mold cavity 1 in a uniform shape (for example, into the mold cavity). It is injected into a corresponding shape), and that shape can be maintained. Therefore, it is possible to obtain a hollow molded article having a uniform wall thickness, suppressing generation of multiple wrinkled hesitation marks and oil wrinkles, having a uniform surface, excellent appearance properties, and high commercial value.

In the gas injection step after the injection filling step, as shown in FIG. 1, an inert gas is injected into the molten resin 2 injected from the movable gas injection needle 4, and the molten resin expands. As a result, a hollow molded product having a shape and size corresponding to the mold cavity 1 is obtained. After the gas injection step, the molded article 6 having the hollow portion 5 is obtained as shown in FIG.
The GAI molding can be performed using a conventionally known GAI molding machine according to a conventional method. For example, the injection amount of the molten resin is 30 to 80 times the volume of the mold cavity.
%, Especially from about 50 to 70%,
The gas injection pressure depends on the melt viscosity of the resin composition, etc.
For example, 5 to 500 kg / cm ² , preferably 10 to 3
You may select from the range of about 00 kg / cm < ² >.

The present invention is useful for obtaining a hollow molded article having the properties of a PBT resin reinforced with a filler. Particularly, it is suitably used for interior and exterior parts of automobiles, office automation equipment (OA equipment), internal mechanism parts of home electric appliances, and outer covers (housings, etc.) which require high mechanical strength, high appearance characteristics and light weight.

[0047]

According to the present invention, a PBT resin, a polycarbonate resin and / or a PET resin, and a filler are combined, and if necessary, a phosphorus compound is added. Of the filler can be suppressed, and the floating of the filler can be suppressed. As a result, the surface appearance characteristics (surface uniformity) and uniformity can be reduced with high moldability, because the surface appearance characteristics are not easily degraded and uneven thickness due to multiple wrinkled hesitation marks and oil wrinkles as well as the embossing of the filler. A hollow part excellent in quality can be obtained. In addition, even if a PBT resin, which is a kind of crystalline thermoplastic resin (engineering plastic), is used, the advantage of the GAI molding method is maximized.
A hollow molded body having high uniformity, mechanical strength / impact strength, and heat resistance can be efficiently manufactured.

[0048]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Unmodified polybutylene terephthalate resin (A-1) 100
30 parts by weight of bisphenol A type polycarbonate resin (B-1), 30 parts by weight of glass fiber (C-1), and tetrakis (2,4-di-t-butylphenyl) -4,4 'based on parts by weight. -Biphenylene phosphite (D)
30 parts by weight were added, and the mixture was extruded with a twin-screw extruder to prepare a pellet-shaped resin composition. The obtained pellet-shaped resin composition was melted in a cylinder of an injection molding machine and jetted into a mold cavity. The temperatures of the cylinder and the mold were adjusted to 260 ° C. and 80 ° C., respectively, and the injection amount of the resin was about 70% of the cavity volume. The outline of the mold cavity shape is shown in FIG. Two seconds after resin injection, pressure 100kg / c
m ² compressed nitrogen gas was injected into the injection resin from a movable needle disposed in the mold cavity to expand the resin and transfer it to the mold cavity. Thereafter, the state of compression and pressurization by the gas was released, the mold was cooled, and the molded product was taken out.

The surface condition (hesitation / oil wrinkles) and the degree of uneven wall thickness of the obtained molded product were observed and evaluated by giving the following scores. (1) Surface appearance 1: Good surface appearance without filler bulging, hesitation and oil wrinkles 2: Good surface appearance overall with some surface bulging and oil wrinkling at the end of the flow 3: Hesitation traces and oil wrinkle traces are not much seen, but embossing of filler is seen. 4: Embossing of fillers, hesitation traces and oil wrinkle traces are seen, and mold transfer is not enough. Leakage occurs and the desired shape cannot be obtained. In addition, the embossing of the filler is seen over the entire surface. (2) Uneven thickness 1: Gas is almost uniformly filled and has a uniform thickness of about 2 to 3 mm 2: Although a thin portion of about 1 mm is observed at the end of flow The overall thickness is uniform. 3: A thick portion is about 5 mm, a thin portion is about 1 mm, and two or three uneven portions are found. 4: Extremely thin portions are present and uneven thickness is remarkable. Alternatively, a trace of gas leakage was observed, and the following properties of the molded article were also evaluated.

(3) Flexural modulus: ASTM D-790
It measured according to. (4) W / N Izod impact strength: Notched Izod impact strength was measured according to ASTM D-256.

Example 2 The characteristics of the hollow molded article were evaluated in the same manner as in Example 1, except that the amount of the polycarbonate resin used in Example 1 was changed to 15 parts by weight.

Example 3 Instead of 30 parts by weight of the glass fiber (C-1) of Example 1, 15 parts by weight of the glass fiber (C-1) of Example 1 and talc (C-2) having an average primary particle diameter of 3 μm were used. ) The characteristics of the hollow molded article were evaluated in the same manner as in Example 1 except that 15 parts by weight were added in combination.

Example 4 The characteristics of the hollow molded article were evaluated in the same manner as in Example 3 except that an unmodified polyethylene terephthalate resin was used instead of the polycarbonate resin of Example 3.

Example 5 The procedure of Example 1 was repeated, except that the unmodified polybutylene terephthalate resin of Example 1 was replaced with a 12 mol% isophthalic acid-modified polybutylene terephthalate copolymer in which 12 mol% of terephthalic acid was replaced with isophthalic acid. The characteristics of the hollow molded article were evaluated in the same manner as in Example 1.

Example 6 Instead of the polycarbonate resin of Example 3, 12 mol%
The properties of the hollow molded article were evaluated in the same manner as in Example 3, except that the isophthalic acid-modified polyethylene terephthalate copolymer was used.

Example 7 The characteristics of the hollow molded article were evaluated in the same manner as in Example 3 except that the addition amounts of the glass fiber and talc in Example 3 were each changed to 10 parts by weight.

Example 8 Instead of 30 parts by weight of glass fiber of Example 1, talc 20 was used.
The characteristics of the hollow molded article were evaluated in the same manner as in Example 1 except that the parts by weight were used.

Comparative Example 1 The characteristics of a hollow molded article were evaluated in the same manner as in Example 1 without using a polycarbonate resin.

Comparative Example 2 The characteristics of a hollow molded article were evaluated in the same manner as in Example 1 without adding glass fibers.

Comparative Example 3 The characteristics of a hollow molded article were evaluated in the same manner as in Example 3 without using a polycarbonate resin.

Comparative Example 4 The characteristics of a hollow molded article were evaluated in the same manner as in Example 6 without using a polycarbonate resin.

The results are shown in the table.

[0063]

[Table 1]

[0064]

[Table 2] As is clear from the table, in the examples, hollow molded articles having excellent surface appearance characteristics and uniformity and high mechanical strength were obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a hollow molded product obtained in the present invention and Example 1.

FIG. 2 is a conceptual diagram showing a state of a molten resin before gas injection in the present invention and Example 1.

FIG. 3 is a conceptual diagram showing a state of a molten resin before gas injection in conventional technology and Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Die cavity 2 ... Injection molten resin 4 ... Gas injection needle 5 ... Hollow part 6 ... Molded product

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 69:00 B29L 22:00

Claims (14)

[Claims] 1. A method comprising: (A) a polybutylene terephthalate resin, (B) at least one resin selected from a polycarbonate resin (B-1) and a polyethylene terephthalate resin (B-2), and a filler (C). A resin composition for gas-assisted injection molding which is constituted. 2. (A) 100 parts by weight of polybutylene terephthalate resin, (B) polycarbonate resin (B
The resin composition for gas-assisted injection molding according to claim 1, comprising 5 to 100 parts by weight of at least one resin selected from -1) and a polyethylene terephthalate resin (B-2). 3. Polybutylene terephthalate resin (A)
The resin composition for gas-assisted injection molding according to claim 1 or 2, wherein is a copolymer resin containing a comonomer unit. 4. Polybutylene terephthalate resin (A)
Is a copolymer resin containing 5 to 40 mol% of a comonomer unit. The resin composition for gas-assisted injection molding according to any one of claims 1 to 3, wherein 5. A polybutylene terephthalate resin (A)
Is a copolymer resin containing an isophthalic acid residue and / or an alkylene glycol residue as a comonomer unit. The resin composition for gas-assisted injection molding according to claim 1. 6. A polyethylene terephthalate resin (B-
The resin composition for gas-assisted injection molding according to any one of claims 1 to 5, wherein 2) is a copolymer resin containing a comonomer unit. 7. The filler (C) is composed of a fibrous filler (C-1) and / or a non-fibrous filler (C-2), and the fibrous filler (C-1) is made of glass fiber. Non-fibrous filler (C-2), at least one selected from carbon fibers and carbon fibers
The resin composition for gas-assisted injection molding according to any one of claims 1 to 6, wherein is at least one selected from powdery or granular fillers having an average primary particle diameter of 20 µm or less. 8. The gas according to claim 1, wherein the non-fibrous filler (C-2) is at least one selected from glass beads, milled fibers, talc, mica and kaolin. A resin composition for assist injection molding. 9. The gas-assisted injection according to any one of claims 1 to 8, wherein the filler (C) is contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the polybutylene terephthalate resin (A). Molding resin composition. 10. A filler (C) of 10 to 40 with respect to 100 parts by weight of (A) a polybutylene terephthalate resin (A).
The resin composition for gas-assisted injection molding according to any one of claims 1 to 9, comprising parts by weight. 11. The resin composition for gas-assisted injection molding according to claim 1, further comprising (D) a phosphorus compound. 12. (A) 100 parts by weight of polybutylene terephthalate resin, and (D) 0.01 parts of a phosphorus compound.
The resin composition for gas-assisted injection molding according to any one of claims 1 to 11, comprising from 5 to 5 parts by weight. 13. A method for molding a molded article having a hollow portion by gas-assisted injection molding using the resin composition according to claim 1. Description: 14. A hollow molded article comprising the resin composition according to claim 1 and molded by a gas assist molding method.