JP2003160710A - Polyacetal resin composition - Google Patents

Abstract

(57) [Problem] To provide a polyacetal resin composition which is excellent in mechanical properties such as impact resistance, slidability, and excellent in workability without causing surface layer separation or the like. SOLUTION: (A) 50 to 99 parts by weight of a polyacetal resin, (B) 0.5 to 99 parts by weight of a polyetheresteramide resin.
49 to 49 parts by weight and (C) a polyolefin-based resin modified with at least one functional group selected from the group consisting of an acid anhydride group, an epoxy group and a carboxyl group.
A polyacetal resin composition containing parts by weight.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyacetal resin composition excellent in impact resistance, slidability and moldability. More specifically, the present invention relates to a polyacetal resin composition having well-balanced mechanical properties, excellent sliding properties, and electrical properties, as well as good extrusion processability and moldability.

[0002]

2. Description of the Related Art Polyacetal resins have been in the spotlight in recent years as engineering plastics having well-balanced mechanical properties, good self-lubricating properties and electrical properties, and are widely used in various mechanical parts and electric parts. . However, its impact resistance is not always sufficient as compared with other engineering plastics such as polyamide resin and polycarbonate resin, and therefore its application to fields requiring high impact resistance is limited. Further, due to the recent high performance of mechanical products, electric products, etc., it is required for polyacetal resin to have further improved sliding properties and wear resistance properties.

In order to improve the impact resistance of polyacetal resin, a method of adding various rubbers and elastomers to the polyacetal resin has been tried. For example, it is possible to add a nitrile group-containing rubber in JP-B-45-12674, an ethylene-based copolymer in JP-B-45-26231, and an elastic rubber graft copolymer in JP-B-48-34830. Each of them has been proposed, but such rubbers generally have a problem of compatibility with the polyacetal resin, and therefore it has been difficult to compound a practically sufficient amount with the polyacetal resin. Further, although the use of polyester elastomers and polyether ester amides, which are considered to have relatively good compatibility with polyacetal resins, has been investigated, the improvement of impact resistance was insufficient. In Japanese Patent Laid-Open No. 61-69859 and Japanese Patent Laid-Open No. 08-325430, a phenoxy resin is added as a compatibilizing agent to improve the compatibility between the polyacetal resin and the polyetheresteramide resin to improve the impact resistance. Although a method for improving has been proposed, its improving effect is not sufficient, and further improvement has been desired.

On the other hand, it has been attempted to add a polyolefin resin to the polyacetal resin in order to improve the abrasion resistance and low temperature brittleness of the polyacetal resin.
As with the polyacetal resin, the polyolefin resin has poor compatibility, so if the amount of the polyolefin resin required to exert the improving effect is added, the strands discharged from the die head during melt kneading by a twin-screw extruder or the like. However, there is a problem in that the pellets will be cut off immediately, and it will not be possible to pelletize them well, or that defects such as surface peeling will occur in the injection molded product. In order to improve such problems, it has been attempted to add an acid anhydride-modified polyolefin, an epoxy-modified polyolefin, or the like as a polyolefin resin, but generally the improvement effect is small, and the decomposition or molding of the polyacetal resin is difficult. Since a new problem such as an increase in deposits will occur, further improvement has been desired.

Further, the biggest drawback of the material obtained by blending the different resins represented by the polyacetal resin and the polyolefin resin is that the physical properties of the weld portion greatly deteriorated due to the association of the molten resins flowing from different directions during injection molding. That is, there is a limitation in shape when designing a product or a die.

[0006]

DISCLOSURE OF THE INVENTION The present invention overcomes various drawbacks of such a blend material of a polyacetal resin and a polyether ester amide resin or a polyolefin resin, and has impact resistance, slidability and moldability. An object is to provide an excellent polyacetal resin composition.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies, and as a result, the compatibility is remarkably improved by kneading a polyether ester amide resin and a specific modified polyolefin resin together with a polyacetal resin, The present inventors have found that the extrusion processability is improved, various problems when the respective resins are separately blended are improved, and various physical properties are significantly improved, and the present invention has been achieved. That is, the gist of the present invention is (A) 50 to 99 parts by weight of polyacetal resin, (B) 0.5 to 4 of polyetheresteramide resin.
Polyacetal obtained by blending 9 parts by weight of (C) and 0.5 to 49 parts by weight of a polyolefin resin modified with at least one functional group selected from the group consisting of an acid anhydride group, an epoxy group and a carboxyl group. It exists in the resin composition.

A resin composition of a polyacetal resin and a modified polyolefin resin is disclosed in JP-A-07-188.
Japanese Patent No. 475 discloses that a polyolefin resin is kneaded with (1) a polyether ester amide resin, (2) a thermoplastic polyester resin and / or a polyacetal resin, and (3) a modified low molecular weight polyolefin, and has excellent antistatic properties. Another polyolefin resin composition is disclosed. This composition, in order to impart antistatic properties to the polyolefin resin, is kneaded with a polyetheresteramide resin, in which case a modified low molecular weight polyethylene to prevent peeling of the surface layer of the polyetheresteramide resin, ,
In order to improve the surface inclination of the polyether ester amide resin, a thermoplastic polyester resin or a polyacetal resin is added, and the composition is a composition mainly composed of a polyolefin resin, and the addition of the polyacetal resin is added. The amount is as small as 20% or less, which is completely different from the present invention mainly composed of polyacetal resin.

Further, in Japanese Patent Application Laid-Open No. 08-188475, polyacetal resin is added to (1) polyamide resin,
(2) Polyethylene graft-modified with an aromatic vinyl monomer or an active hydrogen-containing vinyl monomer,
A composition containing (3) a hindered phenol antioxidant and (4) an ester lubricant is disclosed. Thus, this composition is obtained by adding a graft-modified polyethylene known as a high-sliding polyacetal resin composition and a polyacetal resin to which an ester lubricant is added, and further adding a polyamide resin and a hindered phenol as a heat stabilizer. Therefore, the purpose is to improve the slidability, the addition amount of various additives is extremely small, and because the polyamide resin, which is poorly compatible with the polyacetal resin, is added, the compatibility improving effect is considered to be small. , The object and the configuration are completely different from the present invention.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition of the present invention will be described in detail below. The (A) polyacetal resin used in the present invention is a formaldehyde monomer or its trimer (trioxane) or tetramer (tetraoxane).
An oxymethylene homopolymer consisting essentially of an oxymethylene unit produced from a cyclic oligomer such as, and the above raw materials and ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, glycol formal, and diglycol. An oxymethylene copolymer containing 0.1 to 20% by weight of an oxyalkylene unit having 2 to 8 carbon atoms in a polyoxymethylene main chain produced from a cyclic ether such as formal is included. Among these polyacetal resins, preferred are polyoxymethylene copolymers produced from trioxane and ethylene oxide or 1,3-dioxolane, and more preferably polyoxymethylene copolymers containing 2 to 7.5% by weight of oxyethylene units. It is an oxymethylene copolymer.

The (B) polyether ester amide resin used in the present invention is (a) a polyamide unit of 15 to 90.
Wt% and (b) polyoxyalkylene glycol unit 8
It is mainly composed of 5 to 10% by weight and has a molecular weight of 5,
000-50,000, preferably 10,000-4
It is a segmented copolymer in the range of 10,000.
The polyamide unit (a) constituting the polyether ester amide resin is a polymer having an acid amide bond, and is (1) lactam ring-opening polycondensate, (2) aminocarboxylic acid polycondensate, (3). Any polycondensation product of dicarboxylic acid and diamine may be used.

Examples of the lactam (1) include caprolactam, enanthlactam, laurolactam, and undecanolactam. As the aminocarboxylic acid of (2), ω-aminocaproic acid, ω-aminoenanthic acid,
ω-aminocaprylic acid, ω-aminopentonic acid, ω-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and the like can be mentioned. Examples of the dicarboxylic acid (3) include adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, isophthalic acid, and polymerized fatty acids. The diamines include hexamethylenediamine, heptamethylenediamine, octamethylenediamine. , Decamethylenediamine, metaxylylenediamine and the like. The molecular weight of such a polyamide unit is 300 to 15,000, preferably 800 to 5,000.
Is. Incidentally, two or more kinds of those exemplified as the amide unit-forming monomer may be used in combination. Preferred as the polyamide unit is a dimer acid polyamide obtained mainly by a polycondensation reaction of polymerized fatty acid and diamine.
The polymerized fatty acid is a polymer of unsaturated fatty acid or a polymer obtained by hydrogenating such a polymer to reduce the degree of unsaturation. As the polymerized fatty acid used in the present invention, for example, 1
Dimer of monobasic fatty acid (dimer acid) having 0 to 24 carbon atoms and having at least one double bond or triple bond.
And / or hydrogenates thereof are preferred. Examples of the dimer acid include dimers such as oleic acid, linoleic acid and erucic acid.

The (b) polyoxyalkylene glycol unit constituting the polyether ester amide resin is
Consisting of an oxyalkylene unit having 2 to 4 carbon atoms, 200
Polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, and the like having a molecular weight of up to 8,000 are preferred. Of these, preferred is polyoxyethylene glycol. .

Such a polyether ester amide resin and a method for producing the same are already known. For example, ring-opening polymerization of a lactam is carried out using an anion catalyst in the presence of a condensed polyester prepolymer composed of a polyether and a dicarboxylic acid. Method (US Pat. No. 3,993,709), a method of heat-polymerizing lactam or ω-aminocarboxylic acid, dicarboxylic acid and polyol (West German Patent Publication No. 2712).
No. 987 and No. 2936976), a method of condensing a dicarboxylic acid amide having a carboxyl group at the molecular chain end with a polyol using a titanate catalyst (US Pat. No. 4,230,838) and the like.

The polyether ester amide resin of the present invention may be a commercially available general material, but preferably has an acid value or amine value of 2 mgKOH / g or more,
More preferably, it is 4 mgKOH / g or more. By using a polyetheresteramide resin having an acid value or amine value of 2 mgKOH or more, it is possible to further improve the extrusion processability during melt kneading. The acid value can be measured by, for example, dissolving 1 g of the sample in 50 g of benzyl alcohol and titrating this with KOH methanol solution using phenolphthalein as an indicator. Further, the amine value is obtained, for example, by dissolving 1 g of a sample in 50 g of a phenol / methanol mixed solution, titrating with a hydrochloric acid methanol solution using bromphenol blue as an indicator, and converting it into mg of KOH. High acid number polyether ester amide resin is added during the production of polyether ester amide resin 2
It can be produced by adjusting the amount of carboxylic acid or polyalkylene glycol. On the other hand, high amine number polyether ester amide resins are disclosed, for example, in Japanese Patent Laid-Open No.
It can be manufactured by the method shown in Japanese Patent Publication No. 228691.

The modified polyolefin resin (C) used in the present invention is a polyolefin resin having at least one functional group selected from the group consisting of acid anhydride groups, epoxy groups and carboxyl groups. is there. These reactive functional groups can be introduced by means such as copolymerization of a corresponding monomer with an olefin or oxidation of a polyolefin resin. Examples of the polyolefin resin constituting the modified polyolefin resin include α such as ethylene, propylene, butene, 4-methylpentene-1, hexene, octene, nonene, decene, and dodecene.
Examples thereof include an olefin homopolymer, and a copolymer (random, block, or graft copolymer) of the α-olefin and a copolymerizable monomer. As the copolymerizable monomer, a conjugated diene component (butadiene, isoprene, piperylene, etc.), a non-conjugated diene component (1,4-
Hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 2,5-norbonadiene, etc.),
Other than (meth) acrylic acid ester, vinyl ester (vinyl acetate, etc.), (meth) acrylonitrile, aromatic vinyl monomer (styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, etc.), vinyl ether ( Vinyl methyl ether etc.) and the like. The degree of polymerization, the presence or absence of side chains or branches, the degree of branching, the copolymer composition ratio, etc. of the polyolefin resin are not particularly limited as long as the moldability is not impaired.

Examples of the monomer having an acid anhydride group or a carboxyl group for introducing a functional group into a polyolefin resin include, for example, (meth) acrylic acid, propylolic acid, crotonic acid, and other unsaturated aliphatic monomers. Aromatic unsaturated monocarboxylic acids such as monocarboxylic acid and cinnamic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, aliphatic unsaturated dicarboxylic acids such as citraconic acid, maleic acid monoester (monomethyl maleate, Unsaturated dicarboxylic acid monoesters such as maleic acid monoesters such as maleic acid monoethyl and maleic acid monobutyl and corresponding fumaric acid monoesters) can be mentioned. Further, examples of the monomer having an epoxy group include glycidyl (meth) acrylate and allyl glycidyl ether. The amount of these monomers used is, for example, about 0.01 to 10% by weight, preferably about 0.1 to 5% by weight, based on the polyolefin resin. The average molecular weight of the modified polyolefin resin is not particularly limited, and for example, the average molecular weight of 5,000 to 100,0.
It may be about 00, particularly about 5,000 to 50,000.

The preferred modified polyolefin resin is a modified polyethylene resin modified with a monomer having a carboxyl group, an acid anhydride group or an epoxy group or a modified polypropylene resin, for example, a modified polyethylene resin (for example, a low polyethylene resin). Density, medium density or high density polyethylene, linear low density polyethylene, ethylene- (meth) acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, etc.), modified polypropylene resin (for example, polypropylene homopolymer, propylene) And a α-olefin random copolymer, propylene-α-olefin block copolymer, etc.) and the like. In the modified polyolefin resin, the reactive functional group may be bonded to an end of the polyolefin resin or to an appropriate site in the polymer chain.

The composition ratio of the composition of the present invention is 50-99 parts by weight of (A) polyacetal resin and 0.5- (B) of polyether ester amide resin so that the composition of the present invention can give good results.
49 parts by weight, and (C) modified polyolefin resin 0.
5 to 49 parts by weight. A preferable compounding ratio is (A):
{(B) + (C)} = 98: 2 to 50:50, and more preferably (A): {(B) + (C)} = 98: 2 to 7.
It is in the range of 0:30 (both by weight). Further, in the composition of the present invention, (B) polyether ester amide resin /
(C) Weight blending ratio of modified polyolefin resin (b /
c) is preferably 0.3 or more, more preferably 0.5.
That is all. When b / c is 0.3 or less, the compatibility between the (A) polyacetal resin and the (C) modified polyolefin-based resin is not improved, and problems such as surface layer peeling may occur.

In order to obtain the polyacetal resin composition of the present invention by blending the components (A), (B) and (C) described above,
No particular method is required and a known resin blending method can be applied. For example, a kneading method using a Banbury mixer, an extruder or the like at a temperature equal to or higher than the melting point or softening point of the above three members can be used. In addition to the above-mentioned three components, the composition of the present invention further contains a stabilizer within a range not impairing the object of the present invention.
UV absorbers, pigments, fillers, glass fibers, carbon fibers and other known additives can also be added. The thus-obtained polyacetal resin composition of the present invention is excellent in impact resistance, slidability, and moldability, so that it is used as a muffling gear in the field of electric and electronic devices and as a locking component (for example, by press fitting in the field of automobiles). It is suitable for applications such as locking parts, snap fitting fitting parts, clips, etc.).

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. The materials used in the following examples and the methods for evaluation tests of the obtained compositions are as follows. material:

(Production of Polyacetal Resin) Trioxane was copolymerized with 1,3-dioxolane in an amount different from that of trioxane to produce a polyoxymethylene copolymer having different oxyethylene units. With trioxane, 1,
Bulk polymerization of a mixture of 3-dioxolanes was performed using methylal as a molecular weight modifier and boron fluoride dibutyl etherate as a catalyst. The molar ratio of the trioxane to the molecular weight modifier is 1: 2 × 10 ⁻⁵ to 2 × 10 ⁻³ , and the molar ratio of trioxane to the catalyst is 1: 1 × 10 ⁻⁵ to 1 × 1.
It was set to ^0-4 . A twin-screw kneader was used as a polymerization apparatus, and a liquid high-purity monomer, a molecular weight modifier and a catalyst were supplied to carry out polymerization at 90 ° C. A lump polymer was continuously obtained from the polymerization equipment. Using 1,3-dioxolane in an amount of 4.4 parts by weight and 13 parts by weight with respect to 100 parts by weight of trioxane supplied to the polymerization apparatus, the polyacetal resins shown below were obtained.

A-1: Polyoxymethylene copolymer (oxyethylene unit 2.5% by weight, MI value 3.0 g /
10 min). A-2: Polyoxymethylene copolymer (oxyethylene unit 2.5% by weight, MI value 9.0 g / 10 min). A-3: Polyoxymethylene copolymer (oxyethylene unit 6.8% by weight, MI value 2.5 g / 10 min).

B-1: Polyether ester amide resin "Hydrophilic TPAE 10HP (acid value 2.1)" (trade name, manufactured by Fuji Chemical Industry Co., Ltd.). B-2: Polyether ester amide resin "hydrophilic TP
AE 10HP-A (amine value 4.4) "(trade name, manufactured by Fuji Kasei Kogyo Co., Ltd.). B-3: Polyether ester amide resin "hydrophilic TP
AE237CP-5A (amine value 4.6) "(trade name, manufactured by Fuji Kasei Co., Ltd.). In all of the "hydrophilic TPAE", the soft segment is mainly composed of polyethylene glycol and the hard segment is mainly composed of dimer acid polyamide.

C-1: Modified polyolefin resin "Modic-AP M591" (trade name, manufactured by Mitsubishi Chemical Corporation,
Acid anhydride modified LLDPE). C-2: Modified polyolefin resin "Bond First"
BF-E "(trade name, manufactured by Sumitomo Chemical Co., Ltd., ethylene-glycidyl methacrylate copolymer). C-3: Modified polyolefin resin "Bondayne AX8
390 "(trade name, manufactured by Sumika Atchem Co., Ltd., acid anhydride-modified ethylene-ethyl acrylate copolymer). C-4: Modified polyolefin resin "Toughmer MA85
10 "(trade name, manufactured by Mitsui Chemicals, Inc., acid anhydride-modified ethylene-α-olefin copolymer). C-5; Modified polyolefin resin "NUC-ACE G
B-201 "(trade name, manufactured by Nippon Unicar Co., Ltd., carboxyl group-modified ethylene-ethyl acrylate copolymer).

Evaluation Test Method Tensile Yield Strength: Test pieces were prepared and measured according to the ASTM D638 method. Tensile breaking elongation: A test piece was prepared and measured according to the ASTM D638 method. Izod impact value: A test piece was prepared and measured according to the ASTM D256 method. Weld strength retention rate: It was determined by measuring the weld tensile strength using a tensile test piece having a weld portion in the central portion prepared according to the ASTM D638 method and then comparing it with the tensile yield strength. Dynamic friction coefficient: A dynamic friction coefficient with a polyacetal resin "Iupital F20-03" manufactured by Mitsubishi Engineering Plastics Co., Ltd. was measured using a thrust friction wear tester. Measurement conditions are linear velocity 100 mm / sec, surface pressure 1
It is 0 kgf.

Examples 1 to 9 and Comparative Examples 1 to 3 Polyacetal resin, polyether ester amide resin and modified polyolefin resin were blended in the proportions shown in Table 1 and then 200 ° C using a twin-screw extruder.
And melt-kneaded to obtain a polyacetal resin composition. For the obtained polyacetal resin composition, according to the above method, tensile yield strength, tensile elongation at break, Izod impact value,
Weld strength retention and dynamic friction coefficient were determined. Table of results
Shown in 1. In Comparative Example 1, the weld portion of the weld tensile test piece was not already joined. In such a case, the retention rate was set to 0 without performing the test.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

Examples 10 to 17 and Comparative Examples 4 to 10 Polyacetal resin, polyetheresteramide resin and modified polyolefin resin were blended in the proportions shown in Table 2 and then melted at 200 ° C. using a twin-screw extruder. The mixture was kneaded to obtain a polyacetal resin composition. The tensile yield strength, tensile elongation at break, Izod impact value, and weld strength retention rate of this composition were determined by the same methods as in Example 1. Further, when the polyacetal resin composition was prepared by melt-kneading, the extrusion processability was evaluated. As an evaluation method,
(1) When the strand that came out from the die head of the twin-screw extruder was cut and could not be pelletized at all x, (2) In order to prevent the strand from being cut, the winding speed of the pelletizer must be significantly reduced. No, and for those in which the surging phenomenon was observed in the cooling water tank, △, (3)
For those that could be pelletized without any problems, a three-point rating of ◯ was given. The results of evaluation of extrusion processability and the results of evaluation of physical properties are shown in Table 2.

[0032]

[Table 4]

[0033]

[Table 5]

[0034]

[Table 6]

Examples 18 to 20 and Comparative Examples 11 to 15 Polyacetal resin, polyether ester amide resin and modified polyolefin resin were blended in the proportions shown in Table 3 and then 200 ° C. using a twin-screw extruder.
And melt-kneaded to obtain a polyacetal resin composition. For the obtained polyacetal resin composition, according to the above method, tensile yield strength, tensile elongation at break, Izod impact value,
Weld strength retention and dynamic friction coefficient were determined. In addition, only the dynamic friction coefficient was changed, and the linear velocity was 100 mm / s.
It was measured at ec and a surface pressure of 5 kfg. The results are shown in Table-3.

[0036]

[Table 7]

[0037]

[Table 8]

[0038]

According to the present invention, a polyacetal resin,
By blending a polyether ester amide resin and a specific modified polyolefin resin in a specific amount ratio, conventionally,
Difficult to mix due to poor compatibility, mixing different resins to obtain a composition having well-balanced mechanical properties, excellent slidability, and good extrudability succeeded in.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Daisuke Sanada             5-6 Higashi-Hachiman 5-2, Hiratsuka City, Kanagawa Prefecture             Ryo Engineering Plastics Stock Association             Company Technology Center (72) Inventor Takao Kondo             5-6 Higashi-Hachiman 5-2, Hiratsuka City, Kanagawa Prefecture             Ryo Engineering Plastics Stock Association             Company Technology Center F-term (reference) 4J002 BB203 BB213 CB001 CL082                       GM00 GM02 GM04

Claims (6)

[Claims] 1. A polyacetal resin (A) in an amount of 50 to 99 parts by weight and a polyether ester amide resin (B) in an amount of 0.5 to 99 parts by weight.
49 parts by weight, and (C) a polyolefin resin 0.5 to 49 modified with at least one functional group selected from the group consisting of acid anhydride groups, epoxy groups and carboxyl groups.
A polyacetal resin composition containing 1 part by weight. 2. The polyacetal resin composition according to claim 1, wherein a weight mixing ratio of the (B) polyether ester amide resin and the (C) modified polyolefin resin is 0.3 or more. 3. The (A) polyacetal resin has oxyethylene units of 2 to 7 in the polyoxymethylene main chain.
The polyacetal resin composition according to claim 1 or 2, which is an acetal copolymer containing 5% by weight. 4. The polyacetal resin composition according to claim 1, wherein the soft segment constituent component of the (B) polyether ester amide resin is substantially polyethylene glycol. 5. The dimer acid polyamide obtained by the polycondensation reaction of a polymerized fatty acid and a diamine substantially, as the hard segment constituent component of the polyether ester amide resin (B). The polyacetal resin composition according to any one of 1. 6. The polyacetal resin composition according to claim 1, wherein the (B) polyether ester amide resin has an acid value or amine value of 2 mgKOH / g or more.