JP3290327B2 - Thermoplastic resin composition and molded article thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition containing a polycarbonate resin and a polyacetal resin as components. More specifically, a molded article containing a polycarbonate resin and a polyacetal resin as main components, and a polyfunctional isocyanate and a polycaprolactone resin and / or a polymethyl methacrylate resin, has no surface peeling, has a high surface hardness, and has a high electrical hardness. The present invention relates to a thermoplastic resin composition having good properties, friction / abrasion resistance and impact resistance, and having small molding shrinkage.

[0002]

2. Description of the Related Art Polycarbonate resins have low molding shrinkage, good impact resistance, and are used in a wide range of fields, but have low chemical resistance, low friction and abrasion resistance, Therefore, the field of application is limited.

[0003] On the other hand, polyacetal resins have well-balanced mechanical properties, electrical properties, heat resistance, chemical resistance, friction / abrasion resistance, and the like, and furthermore have excellent fatigue resistance as a plastic material. It is used in a very wide range of fields as a general engineering plastic. However, molding shrinkage and warpage are large and conventionally used only for relatively small molded products.

[0004] Various other polymers have also been blended to further improve the performance of polyacetal resins. For example, it is known that a thermoplastic polyurethane resin is mixed with polyacetal to improve impact resistance, and such a molded product is used for parts requiring toughness such as electric / electronic devices and automobiles. However, the addition of the thermoplastic polyurethane resin has a problem that the surface of the molded article is roughened due to poor dispersibility in the polyacetal resin, and the weld strength elongation is significantly reduced.

In Japanese Patent Application Laid-Open No. 3-188152, an amorphous polymer (acrylonitrile-styrene copolymer or polycarbonate resin) is blended in order to improve molding shrinkage of a polyacetal resin / thermoplastic polyurethane resin blend. However, since these polymers are incompatible with the polyacetal resin, the reduction in mechanical properties is inevitable.

At present, a material obtained by blending a polycarbonate resin and a polyacetal resin and having a small molding shrinkage, good moldability and fluidity, and excellent friction and abrasion resistance has not been obtained.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have found that in a polymer blend in which a polyacetal resin is blended with a polycarbonate resin, injection-molded articles based on poor dispersibility of the two and adhesion between the resin phases are poor. Eliminates problems such as striped phase separation structure on the surface and surface layer peeling, reduces shrinkage and warpage during molding, and improves dispersibility. The surface condition of molded products is uniform and smooth, friction and abrasion characteristics, and scratch resistance. As a result of intensive studies for the purpose of obtaining a thermoplastic resin composition having improved properties and the like, the above-mentioned object was achieved by blending a polyfunctional isocyanate and a polycaprolactone resin and / or a polymethyl methacrylate resin at a certain ratio. I found what I could achieve.

That is, the present invention relates to (A) 5-95% by weight of a polycarbonate resin and (B) 95-95% by weight of a polyacetal resin.
With respect to 100 parts by weight of the resin composition comprising 5% by weight,
A thermoplastic resin composition comprising (C) 0.1 to 10 parts by weight of a polyfunctional isocyanate and (D) 1 to 30 parts by weight of a polycaprolactone resin and / or a polymethyl methacrylate resin, and a molded product thereof. It is.

As the component (A) of the present invention, a polycarbonate resin (hereinafter, referred to as PC) is used. PC is
It can be obtained by melt polycondensation using a divalent hydroxy compound and a carbonic acid diester as raw materials by a phosgene method or a transesterification method. Further, it can be obtained by a solid phase polymerization method.
It is not limited by these manufacturing methods. Basically, it is known to have a repeating carbonate group of (-OCOO-) and, in addition, always have a phenylene group bonded to carbonate. As the aromatic polycarbonate resin, bis (4-hydroxyphenyl) -2,2-propane PC, which is known as a bisphenol A-type polycarbonate resin, is preferable. The PC preferably has a viscosity average molecular weight of 10,000 to 40,000 in consideration of mechanical strength and moldability.

The polyacetal resin (hereinafter referred to as POM) used as the component (B) is a high molecular compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, and is a polyoxymethylene homopolymer or oxymethylene homopolymer. Any of copolymers, terpolymers and block copolymers containing a small amount of other structural units other than this as a main repeating unit of methylene, for example, ethylene oxide, 1,3-dioxolan, 1,4-butanediol, formal and the like. Alternatively, the molecule may have not only a linear shape but also a branched crosslinked structure, or a known modified polyacetal resin having another functional group. The degree of polymerization is not particularly limited as long as it has moldability. For example,
Melt flow value (MFR) under 190 ° C, 2.16kg load
It should just be 1.0-100.

In general, POMs have thermally stable ends, eg, ester or ether groups, eg, acetate or methoxy groups. It generally has a molecular weight between 10,000 and 100,000. If the melt flow rate (MFR) is too high, the melt viscosity of the POM will be too low, making it difficult to achieve adequate intimate mixing of the components at the appropriate shear rate. If the MFR is too low, the temperature of the compounding operation will be too high and degradation will occur.

As the polyfunctional isocyanate used as the component (C), difunctional, trifunctional or higher functional isocyanates are used. Specifically, tolylene diisocyanate (TDI), naphthylene-1,5-diisocyanate (NDI), o-toluylene diisocyanate (TO
DI), diphenylmethane diisocyanate (MD
I), triphenylmethane triisocyanate, tris (p-isocyanatophenyl) thiophosphite,
Polymethylene polyisocyanate, hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate, isophorone diisocyanate (I
PDI), xylylene diisocyanate (XDI), butene diisocyanate, propane hexafluoro-1,3-diisocyanate, 1-methylcyclohexane-2,4-
Diisocyanate, dimethylcyclohexane diisocyanate, dicyclohexylmethane diisocyanate, dimer acid diisocyanate (DDI), lysine diisocyanate (LDI), dimethyldiphenylmethane diisocyanate (DMMDI), polymeric MDI, TD
I dimer, MDI dimer, HDI trimer, XDI trimer, and IPDI trimer. As high molecular weight isocyanates, vinyl isocyanate copolymers and carboxylic acid-containing polymers are converted into isocyanate groups. And those obtained by reacting an amino group-containing polymer with phosgene and adding it to an isocyanate group.

The polycaprolactone resin (hereinafter referred to as PCL) used as the component (D) is a polymer prepared by polymerization of caprolactone, and preferably has a molecular weight of 1,000 to 100,000.

The PCL used in the present invention has the following structure.

[0015]

Embedded image

(Wherein, n represents a positive number of 10 to 100).

If n is less than 10, the molecular weight is low and the liquid is in a liquid state, so that it is difficult to handle and bleed out easily, so that the physical properties of the polymer deteriorate. On the other hand, when n exceeds 100, the viscosity becomes high, the fluidity decreases, and the surface of the molded product becomes rough.

The PCL in the present invention is produced by a known polymerization method and can be obtained, for example, as follows. That is, ε-caprolactone is polymerized to form P
When CL is used, water or a compound having hydroxyl groups at both ends is used as the polymerization initiator.

As a catalyst used in this reaction, an organic tin compound, an organic titanium compound, an organic tin halide compound and the like are generally used.
The desired PCL can be obtained by polymerizing at 230 ° C., preferably in an inert gas.

Examples of the polymerization initiator include resorcin, pyrocatechol, hydroquinone, pyrogallol, chloroglycine, benzenetriol, bisphenol A, bisphenol F, and ethylene oxide adducts thereof.
Dimethylolbenzene, cyclohexanedimethanol,
Tris (2-hydroxyethyl) isocyanurate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,8-butanediol, 2-methyl-1,3-propylene glycol ,
Neopentyl glycol, 1,5-pentanediol,
Dicarboxylic acid components such as glycerin, trimethylolpropane, 1,6-hexanediol, pentaerythritol, sorbitol, glucose, sucrose and terephthalic acid, isophthalic acid, adipic acid, sebacic acid, undecandioic acid and dodecanedioic acid; and ethylene. Glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, trimethylolpropane, glycerin, pentaerythritol, sorbitol Average molecular weight generated from polyol components such as
Polyester polyol of 200 to 600; average molecular weight 200
Polyethylene glycol of ~ 600; average molecular weight 200 ~ 60
0 polypropylene glycol; average molecular weight 200-600
Polytetramethylene glycol; a block or random copolymer of ethylene oxide and propylene oxide with an average molecular weight of 200 to 600; a block or random copolymer of ethylene oxide or propylene oxide with an average molecular weight of 200 to 600, etc. be able to.

In general, the ester portion of a polyester resin is hydrolyzed with time, and in the case of a molded product, the mechanical strength is reduced. PCL is also a polyester resin, and may cause a decrease in molecular weight due to hydrolysis. If an epoxy resin is partially added in place of water as the above-mentioned initiator and polymerization is carried out in order to prevent this, the obtained resin has remarkably improved hydrolysis resistance. Therefore, a small amount of epoxy resin may be added. It is effective to add the most common epi-bis type epoxy resin among the epoxy resins to improve the hydrolysis resistance. The epoxy resin may be added not at the time of polymerization but at the time of blending in producing the resin composition of the present invention.

The polymethyl methacrylate resin (hereinafter referred to as PMMA) also used as the component (D) is a resin prepared by polymerization of methyl methacrylate, and preferably has a molecular weight of 5,000 to 500,000.
A small amount of a copolymer component may be contained. For example,
A copolymer of a copolymer component such as styrene and ethyl acrylate with methyl methacrylate can also be used. Therefore, the PMMA of the present application can be obtained by polymerizing methyl methacrylate alone or a mixture of methyl methacrylate and another copolymerizable vinyl or vinylidene monomer. In the case of copolymerization, it preferably contains 80% by weight or more of methyl methacrylate (MMA). Examples of other copolymerizable vinyl or vinylidene monomers include alkyl acrylates having 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and ethyl hexyl acrylate, styrene and acrylonitrile. No. Preferable examples include alkyl acrylates having 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, styrene and acrylonitrile.

The mixing ratio (by weight) of the components (A) and (B) can be arbitrarily selected within the range of 5 to 95/95 to 5. When the proportion of the component (A) is less than 5% by weight, molding shrinkage and warpage increase, resulting in poor appearance. On the other hand, when the content exceeds 95% by weight, the content of the polyacetal component is small, so that it is insufficient to impart friction and abrasion resistance, scratch resistance, fluidity and chemical resistance. POM exhibits high chemical resistance as described above. In order to maintain the chemical resistance properties of POM, POM must be a continuous phase in the resin composition. Whether or not the POM is in the continuous phase can be determined by a standard method using an electron microscope or a standard method in which the dispersed phase is removed using a selective solvent, and microscopic observation is performed while the continuous phase remains. It can be measured by methods known to those skilled in the art, such as determination of chemical resistance, stress cracking or surface softening.

Component (C) is added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total of components (A) and (B). If the amount is less than 0.1 part by weight, the compatibilizing effect is insufficient. If the amount exceeds 10 parts by weight, the resin composition becomes expensive and the melt viscosity is increased, resulting in reduced workability.

The amount of the component (D) is 1 to 30 parts by weight based on 100 parts by weight of the total of the components (A) and (B). When the amount is less than 1 part by weight, the POM phase and the PC phase are remarkably delaminated, and the mechanical properties of the obtained composition are low. If the amount exceeds 30 parts by weight, the friction and abrasion resistance of the composition deteriorates. In particular, when the PCL exceeds 30 parts by weight, the heat resistance and rigidity are significantly reduced.

As described above, simply melting and kneading PC and POM causes the dispersed resin phase to appear as a striped phase-separated structure on the surface of the injection-molded article. PCL and / or PMMA are blended, and PC and POM at melt-kneading temperature
By adjusting the melt viscosity ratio between the two, the dispersibility of the two can be improved, and the surface condition and the friction and wear resistance of the molded article can be increased.

In order to improve the impact resistance of POM, a thermoplastic polyurethane resin (hereinafter referred to as TPU) is used.
Is generally used, but this method may be applied to the resin composition of the present invention.

Useful TPUs are the condensation products of diisocyanates with one or more dihydroxy compounds. Examples of suitable dihydroxy compounds are dihydroxy-terminated polyethers or polyesters, alkylene glycols and polyalkylene glycols. Examples of suitable materials are, for example, 2,4-tolylene diisocyanate, 1,1,2
Diisocyanates such as 5-naphthylene diisocyanate, 2,7-fluorene isocyanate and methylene diparaphenylene diisocyanate (MDI);
Polyesters such as, for example, polyethylene succinate or polyethylene adipate;
It is a condensation product with a glycol such as butanediol.

A preferred TPU has a hard segment and a soft segment and is the reaction product of MDI with butanediol and polyethylene adipate.

The thermoplastic resin composition of the present invention generally has a component which promotes the reaction of the isocyanate of the component (C) in addition to the components (A), (B), (C) and (D). A small amount of a catalyst may be added. Examples of such a catalyst include bases such as tertiary amines that work nucleophilically with respect to isocyanates, and organometallic compounds that work electrophilically.

Further, mechanical strength, heat resistance, dimensional stability,
Fibrous fillers such as glass fiber and carbon fiber and other fillers can be blended according to the purpose such as electrical properties.

Further, the composition of the present invention comprises an antioxidant,
Heat stabilizers, ultraviolet absorbers, coloring agents, release agents, and other usual additives can be added. In addition, a small amount of a thermoplastic resin can be added as an auxiliary.

The composition of the present invention is desirably prepared by tumbling or mixing the pellets of each component and melt-blending the mixture.

Each component may be mixed and melt-kneaded together, or the pellets obtained by pre-kneading components (B) and (C) may be kneaded with components (A) and (D), The pellets obtained by pre-kneading the components (A) and (D) may be kneaded with the components (B) and (C).

Generally, the temperature at which the compound is kneaded is the temperature at which the POM is melt processed. The POM is usually preferably melt processed at 170 to 220 ° C, more preferably 200 to 220 ° C.

[0036]

As described above, simply melt-kneading PC and POM causes the dispersed resin phase to appear as a striped phase-separated structure on the surface of the injection-molded article. PCL and / or PMMA are blended, and PC and PO at the melt-kneading temperature.
By adjusting the melt viscosity ratio with M, the dispersibility of the two is improved, and the polyfunctional isocyanate compounded as the component (D) acts as a compatibilizer, and the surface state of the molded article is improved. Increases friction and wear resistance.

[0037]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Examples 1-6 and Comparative Examples 1-4 (A) PC (Iupilon S3000 manufactured by Mitsubishi Gas Chemical Co., Ltd.) (B) POM (Duracon M manufactured by Polyplastics Co., Ltd.)
90-44) (C) Isophorone diisocyanate trimer (trifunctional isocyanate, Vestenat IPDI-T18 manufactured by Huls)
90) (D) PMMA (Sumipex B, manufactured by Sumitomo Chemical Co., Ltd.) (D) PCL (Placcel H, manufactured by Daicel Chemical Industries, Ltd.)
7 (nominal molecular weight 70,000)).

The mixture was mixed at the ratio (weight) shown in Table 1, melt-kneaded at a set temperature of 220 ° C. using a twin-screw extruder having an inner diameter of 30 mm at a screw rotation speed of 120 rpm, and pelletized. Next, the pellets were molded at a set temperature of 210 ° C. by an injection molding machine to prepare test pieces, and the following mechanical properties were evaluated.

Surface peeling test: An adhesive tape was stuck to the surface of the tensile test piece, which was instantaneously peeled off, and the presence or absence of surface peeling of the molded piece was visually judged.

Friction and abrasion test: The specific amount of wear on steel S55C was measured by a Suzuki type friction and abrasion tester.

Shrinkage rate: The dimensions of the ASTM tensile test specimen in a certain direction were accurately measured, and the difference (%) from the corresponding metal mold dimension was defined as the shrinkage rate. Molding shrinkage = (Length of mold−Length of molded test piece) × 100
÷ (mold length).

Tensile strength: according to ASTM D638.

Scratch resistance: JIS K 54
A 01 pencil hardness test was performed.

Solvent resistance; injection test piece (10 × 50
× 2 mm) was immersed at 23 ° C. for 4 hours.

Izod impact strength; ASTM
The measurement was performed using a 6.3 mm thick test piece with a mold notch in accordance with D256.

Table 1 shows the results.

[0048]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 69/00 C08L 69/00 // (C08L 69/00 (C08L 69/00 59:00 59:00 33:12 33:12 67:04) 67:04)

Claims (3)

(57) [Claims] 1. A polyfunctional isocyanate of 0.1 to 10% by weight based on 100 parts by weight of a resin composition comprising (A) 5 to 95% by weight of a polycarbonate resin and (B) 95 to 5% by weight of a polyacetal resin. Part and (D) a polycaprolactone resin and / or a polymethyl methacrylate resin 1
A thermoplastic resin composition containing 30 parts by weight. 2. The thermoplastic resin composition according to claim 1, further comprising a filler. 3. A thermoplastic resin molded article having a pencil hardness of JIS K 5401 of B or more, obtained by molding the thermoplastic resin composition according to claim 1 or 2.