JP3086293B2 - Polyacetal resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the physical properties such as impact strength obtained by melt-kneading a polyester-based thermoplastic resin or elastomer with a polyacetal resin containing a modified polyacetal copolymer having an ester group in the side chain. And
The present invention relates to a polyacetal resin composition capable of forming a molded article having a good appearance without surface peeling.

[0002]

2. Description of the Related Art As is well known, polyacetal is widely used as an engineering plastic having excellent mechanical properties, electrical properties, chemical resistance and heat resistance. However, with the expansion of fields in which polyacetal resins are used, further improvements in the properties of the materials have been required. For example, it is desired that molded articles used for automobile parts have high impact resistance in a wide temperature range. Many attempts have been made to improve the impact characteristics of polyacetal resins. For example,
Japanese Patent Publication No. 18023/18023 discloses the addition of a so-called ionomer, and Japanese Patent Publication No. 45-26231 discloses the addition of an ethylene-acrylic acid copolymer.
No. 095 proposes the addition of aliphatic polyethers. JP-A-59-145243, JP-A-61-19652 and the like propose the addition of a thermoplastic polyurethane. However, the compositions according to these proposals have some improvement in physical properties such as impact properties, but they are not always sufficient, and all of them have poor compatibility and dispersibility with polyacetal, resulting in poor surface condition of molded products. In many cases, a surface peeling phenomenon occurs, and the appearance is often significantly impaired. The cause of these drawbacks is that polyacetal has a very low affinity for other substances. Therefore, it is understood that impact resistance and the like are not sufficiently improved because the added counterpart material is not finely dispersed, and that a peeling phenomenon occurs due to insufficient adhesion at the interface between the polyacetal resin and the counterpart material. Is done. The present invention solves the drawbacks of affinity and compatibility of the polyacetal resin,
It is an object of the present invention to provide a polyacetal resin composition having excellent dispersibility, a good surface condition of a molded article, and improved physical properties such as impact resistance.

[0003]

The present inventors have conducted intensive studies to obtain a polyacetal resin composition which has solved the above-mentioned problems. As a result, the specific modified polyacetal copolymer having an ester group in the side chain is a polyester. It has excellent compatibility with thermoplastic resins or elastomers, and also has excellent compatibility even when a general polyacetal resin is added. Successfully obtained a polyacetal resin composition having a good appearance, and completed the present invention. That is, the present invention provides (A) a unit represented by the following general formula (1) in the main chain.
Modified polyacetal copolymer containing 0.1 to 30% by weight
% By weight (vs. (A) + (B) + (C))

[0004]

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(Wherein R ¹ is a hydrogen atom or a group having 1 carbon atom.
To 4 alkyl groups. R ² is a divalent ether or alkylene group having 1 to 20 carbon atoms. R ³ has 1 to 1 carbon atoms
4 alkyl group. i is an integer of 1 to 5 and j is an integer of 0 to 2. (B) polyester thermoplastic resin or elastomer 1
80% by weight (based on (A) + (B) + (C)) (C) Polyacetal resin consisting of 0 to 98% by weight (based on (A) + (B) + (C)) other than (A) It relates to a composition.

The modified polyacetal copolymer used as the component (A) in the present invention is mainly composed of an oxymethylene unit (-CH ₂ O-), and contains a unit represented by the general formula (1) in an amount of 0.1 to 30% by weight. % Of a oxyalkylene unit comprising-(CH ₂ ) _k -O- (k is an integer of 2 to 4) in the main chain. There may be. Among them, in general formula (1), it is preferable that i = 1 or 2, j = 0 or 1, R ¹ is a hydrogen atom or an ethyl group, and R ² is an ether group or an alkylene group having 1 to 18 carbon atoms. . Particularly preferably, in the general formula (1), i = 1, j = 0, R ¹ is a hydrogen atom, and R ² is a linear ether group in which the 2-position is an oxygen atom. Those represented by the formula (2) are particularly preferred.

[0007]

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(Wherein R ³ is an alkyl group having 1 to 4 carbon atoms and n is an integer of 1 to 18). The molecular weight of the component (A) is not particularly limited, but the weight average molecular weight is not limited. 5,000 〜
300,000, preferably 10,000 to 100,000.

The modified polyacetal copolymer (component
(A)) is a separate application filed by the present inventors (Japanese Patent Application No. 3-180947).
) Can be obtained.
That is, a mixture of trioxane and a cyclic ether or cyclic formal having a carboxylic acid ester group represented by the following general formula (3), or further having adjacent carbon bonds commonly used in the production of a conventional polyacetal copolymer as a comonomer. It can be obtained by polymerizing a product to which a cyclic ether or cyclic formal is added in the presence of a cationically active catalyst, washing the polymer, and performing a stabilization treatment.

[0010]

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(Wherein R ¹ is a hydrogen atom or a group having 1 carbon atom)
To 4 alkyl groups. R ² is a divalent ether or alkylene group having 1 to 20 carbon atoms. R ³ has 1 to 1 carbon atoms
4 alkyl group. i is an integer of 1 to 5, j is 0 to 2, and p is an integer of 0 to 3. Next, (B) used in the present invention
Component polyester resin or elastomer, polyethylene terephthalate, polybutylene terephthalate,
Or based on these, modified polyethylene terephthalate containing other ester-forming comonomer units, modified polybutylene terephthalate, alkylene terephthalate resin such as polyethylene butylene terephthalate,
Alternatively, it is a polyester elastomer composed of a block copolymer in which these polyalkylene terephthalates are used as hard segments and polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol are used as soft segments. In particular, a polybutylene terephthalate-polytetramethylene glycol block copolymer, a modified polybutylene terephthalate-polytetramethylene glycol block copolymer, and a polyethylene / butylene terephthalate-polytetramethylene glycol block copolymer are preferred.

The polyacetal resin (C) used in the present invention is not particularly essential,
It is preferred that (A) be present as a component that dilutes and maintains the original physical properties of polyacetal. All known polyacetal resins other than (A) having an oxymethylene group (—CH ₂ O—) as a main structural unit can be used, and other structural units other than polyoxymethylene homopolymer and oxymethylene group can be used. Any copolymer, terpolymer, or block copolymer containing a small amount may be used, and the molecule may have not only a linear shape but also a branched or crosslinked structure,
The terminal may be any terminal as long as it is stable. The molecular weight, the degree of branching, and the degree of cross-linking are not particularly limited, as long as it has melt-forming processability, and an appropriate one can be selected and used depending on the purpose.

In the component (A), the carboxylic acid ester group in the side chain thereof undergoes a transesterification reaction with the ester bond of the component (B) to form a graft copolymer, which is formed with the component (A).
It is considered that the compatibility of (B) is improved. Also, even if a general polyacetal (C) having no ester group is present, the component (A) has a main chain structure close to that of the component (C).
The compatibility with (C) is also improved. Therefore, component (A) is (A)
, (B) and (C) exhibit the action of increasing the compatibility of the three, allowing the component (B) to be finely dispersed in the composition, thereby increasing the impact resistance of the molded article, and Component (A) and
It is understood that the interfacial adhesion between (C) and (B) was increased to suppress surface peeling.

(A) a modified polyacetal copolymer having an ester group in the side chain, (B) a polyester-based thermoplastic resin or elastomer, and (C) a polyacetal resin, (A) is 1 to 99. % By weight (vs. (A) + (B) + (C)), (B): 1 to 80% by weight (vs. (A) + (B) + (C)), (C): 0 to 98% by weight
(Pair (A) + (B) + (C)). Among them, the sum of (A) and (C) is 95-
50% by weight and 5 to 50% by weight of (B) are preferable. If the amount of (B) is too small, the effect of improving the physical properties such as impact resistance of the polyacetal resin is poor. Characteristic is lost, which is not preferable. The ratio of (A) to (C) is selected depending on the content of the ester group of component (A) and the desired physical properties, but component (A) is at least 1% by weight.
At least (vs. (A) + (B) + (C)), preferably at least 5% by weight is necessary for improving the dispersibility.

The content of the unit of the formula (1) in the component (A) is 0.1 to 30% by weight, preferably 0.5 to 20% by weight.
If the unit of the formula (1) of the component (A) is too small, the effect of improving dispersibility cannot be obtained, and if it is too large, physical properties are adversely affected, which is not preferable. Maintain physical properties and components of polyacetal resin
From the viewpoint of dispersibility of (B), if the unit of formula (1) of component (A) has a relatively low content in the above range, it is preferable to reduce the amount of component (C), and (1) When the content of the formula unit is high, it is possible to reduce the amount of the component (A) and increase the amount of the component (C), and in this case, the molecular weight of the component (A) is relatively low. Is also good.

Further, the composition of the present invention may be blended with various known additives in order to improve its physical properties according to the intended use. Examples of additives include various stabilizers such as antioxidants, heat stabilizers, and weather (light) stabilizers, coloring agents,
Lubricants, mold release agents, nucleating agents, organic polymer improvers, inorganic and
Examples of the filler include fibrous, powdery, and plate-like fillers such as organic and metal, and one or more of these can be used in combination.

The composition of the present invention or a molded article thereof is prepared basically by subjecting (A) and (B) to melt kneading, optionally with the addition of component (C). Processing conditions are (A)
It is desirable to knead at a temperature of not less than 270 ° C and the highest melting point among the components (B) and (C) for at least 30 seconds or more. Although the specific mode of the preparation method is not particularly limited, it can be generally prepared by a known equipment and method for preparing a synthetic resin composition or a molded article thereof. That is, necessary components are mixed, kneaded using a single-screw or twin-screw extruder or other melt-kneading apparatus, and formed into pellets for molding, followed by molding.

The resin composition of the present invention may be formed by extrusion molding,
It can be formed by any of injection molding, compression molding, vacuum molding, blow molding, foam molding and the like.

[0019]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Preparation of Component (A) Trioxane, 4- (4-methoxycarbonyl-2-oxabutyl) -1,3-dioxolane (hereinafter abbreviated as DO-COOMe) and 1,3 −
The dioxolane monomer mixture was mixed with a small-sized paddle-equipped twin-screw continuous kneader, and boron trifluoride dibutyl etherate was used as a polymerization catalyst.
And the polymerization was carried out at 80 ° C. The polymer was pulverized, and the remaining polymerization catalyst was deactivated with a 0.1% aqueous solution of triethylamine, followed by washing and drying. Then, using a small single screw extruder with vent holes, in the presence of the stabilizer, while sucking the vent holes at a pressure of 300 mmHg, melt-kneading at 230 ° C to remove unstable portions of the polymer. To obtain the desired copolymers A-1, A-2 and A-3.
The molecular weight is a weight average molecular weight measured by gel permeation chromatography using hexafluoroisopropanol as a solvent, and the concentration of the ester group is measured by proton NMR. Indicated by Table 1 shows the results.

Examples 1 to 19 As shown in Table 2, the above components A-1 and A-
2, Polyester elastomer (B-1) having polybutylene terephthalate as a hard segment and polytetramethylene glycol as a soft segment as component (B), or polybutylene terephthalate (B-2) as component (B); As (C) a general polyacetal copolymer resin (manufactured by Polyplastics Co., Ltd., Duracon M)
90) was melt-kneaded at 210 ° C. using a twin-screw extruder to prepare a pellet-shaped composition. Next, a test piece was prepared using the pellet by an injection molding machine and evaluated.
In addition, the impact strength measured the Izod impact strength with a notch based on ASTM D256. The surface peeling state was evaluated by the following five grades by visually observing the surface appearance, peeling state, color unevenness and the like of the test piece. Table 2 shows the results. Comparative Examples 1 to 9 The same evaluation was performed on the examples as above, each component alone or without blending the component (A). Table 3 shows the results.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

Claims (3)

(57) [Claims] (A) 1 to 99% by weight of a modified polyacetal copolymer containing 0.1 to 30% by weight of a unit represented by the following general formula (1) in the main chain (based on (A) + (B) + (C)) (Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R ² is a divalent ether group or an alkylene group having 1 to 20 carbon atoms; R ³ is 1 carbon atom) And i is an integer of 1 to 5, and j is an integer of 0 to 2.) (B) Polyester-based thermoplastic resin or elastomer 1 to
80% by weight (vs. (A) + (B) + (C)) (C) 0 to 98% by weight of polyacetal resin other than (A) (vs.
(A) + (B) + (C)). 2. The polyacetal resin composition according to claim 1, wherein the unit of the formula (1) of the component (A) is represented by the following general formula (2). Embedded image Wherein R ³ is an alkyl group having 1 to 4 carbon atoms, and n is 1 to 18
Is an integer. ) 3. The polyacetal resin composition according to claim 1, wherein the polyester-based thermoplastic resin as the component (B) is an alkylene terephthalate resin or a polyester-based elastomer comprising alkylene terephthalate and polyalkylene glycol.