JPH0532859A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. excellent in impact strength, etc., and giving a molded article free of delamination by compounding a specific modified polyacetal copolymer with a specific thermoplastic resin or elastomer in a specified ratio. CONSTITUTION:The title compsn. comprises 1-99wt.% modified polyacetal copolymer contg. 0.1-30wt.% units of the formula (wherein R<1> is H or 1-4C alkyl; R<2> is a 1-20C ether or alkylene group; R<3> is 1-4C alkyl; i is 1-5; and j is 0-2) in the main chain [e.g. a copolymer obtd. from trioxane, 4-(4-methoxycarbonyl-2- oxabutyl)-1,3-dioxolane, and 1,3-dioxolane)], 1-50wt.% thermoplastic polyester resin or elastomer (e.g. polybutylene terephthalate), and up to 98wt.% arbitrarily selected polyacetal resin except the polyacetal copolymer, the total being 100wt.%.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention improves the physical properties such as impact strength obtained by melt-kneading a polyester-based thermoplastic resin or an elastomer with a polyacetal resin containing a modified polyacetal copolymer having an ester group in the side chain. Is
The present invention relates to a polyacetal resin composition capable of forming a molded product 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, there is a demand for further improvements in the properties of the materials. For example, molded articles used for automobile parts and the like are desired to have a high degree of impact resistance in a wide temperature range. Many attempts have been made in the past to improve the impact properties of polyacetal resins. For example, Japanese Patent Publication Sho 45
-18023, addition of so-called ionomer, JP-B-45-26231, addition of ethylene-acrylic acid copolymer, JP-B-50-33.
In 095, addition of an aliphatic polyether is proposed. In addition, in JP-A-59-145243 and JP-A-61-19652, addition of thermoplastic polyurethane is proposed. However, although the compositions according to these proposals have some improvement in physical properties such as impact properties, they are not necessarily sufficient, and neither of them has poor compatibility or dispersibility with polyacetal, resulting in a surface condition of a molded product. In many cases, the surface peeling phenomenon occurs and the appearance is significantly impaired. The cause of these drawbacks is that polyacetal has a very low affinity for other substances. Therefore, it is understood that the impact resistance, etc. does not sufficiently increase because the added mating material is not finely dispersed, and the peeling phenomenon occurs due to insufficient adhesion at the interface between the polyacetal resin and the mating material. To be done. The present invention solves the problems of affinity and compatibility of the polyacetal resin,
An object of the present invention is to provide a polyacetal resin composition having excellent dispersibility, a molded product having a good surface condition, and improved physical properties such as impact resistance.

[0003]

Means for Solving the Problems As a result of intensive studies to obtain a polyacetal resin composition that solves the above problems, the present inventors have found that a specific modified polyacetal copolymer having an ester group in a side chain is a polyester. It was found that the compatibility with thermoplastic thermoplastic resins or elastomers is excellent, and even if general polyacetal resins are added, the compatibility is also excellent, and by melt-kneading these, it has excellent impact properties, and molded products Succeeded in obtaining a polyacetal resin composition having a good appearance, and completed the present invention. That is, the present invention comprises (A) a unit represented by the following general formula (1) in the main chain.
Modified polyacetal copolymer containing 0.1 to 30% by weight 1 to 99
Weight% (vs. (A) + (B) + (C))

[0004]

[Chemical 3]

(In the formula, R ¹ is a hydrogen atom or has 1 carbon atom.
~ 4 alkyl groups. R ² is a divalent ether group or alkylene group having 1 to 20 carbon atoms. R ³ has a carbon number of 1 to
4 is an 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 to
Polyacetal resin consisting of 80 wt% (vs. (A) + (B) + (C)) (C) (A) other than 0 to 98 wt% (vs. (A) + (B) + (C)) It relates to a composition.

The modified polyacetal copolymer which is the component (A) used in the present invention is mainly composed of oxymethylene unit (--CH ₂ O--) and 0.1 to 30 parts by weight of the unit represented by the general formula (1). % A copolymer contained in the main chain, which further contains 20% by weight or less of an oxyalkylene unit consisting of-(CH ₂ ) _k -O- (k is an integer of 2 to 4). It may be. Among them, it is preferable that in the general formula (1), 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 having 1 to 18 carbon atoms or an alkylene group. . 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, that is, the following general formula Those represented by the formula (2) are particularly preferable.

[0007]

[Chemical 4]

(In the formula, 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 is a weight average molecular weight. 5,000〜
It is 300,000, preferably 10,000 to 100,000.

Such modified polyacetal copolymer (component
(A) is another application by the present inventors (Japanese Patent Application No. 3-180947).
No.).
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 a mixture thereof having adjacent carbon bonds commonly used in the production of conventional polyacetal copolymers as comonomers. It can be obtained by polymerizing a product to which a cyclic ether or a cyclic formal is added in the presence of a cationic active catalyst, washing the polymer, and then subjecting it to a stabilization treatment.

[0010]

[Chemical 5]

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

The polyacetal resin of the component (C) used in the present invention is not particularly an essential component, but the component
It is preferable to dilute (A) and to be present as a component that maintains the original physical properties of the polyacetal. It is possible to use all known polyacetal resins other than (A) having an oxymethylene group (-CH ₂ O-) as the main constituent unit, and to use other constituent units in addition to the polyoxymethylene homopolymer and the oxymethylene group. It may be any of a small amount of a copolymer, a terpolymer and a block copolymer, and the molecule may have not only a linear structure but also a branched or crosslinked structure,
Moreover, the end may be any stable one. The molecular weight, the degree of branching, and the degree of crosslinking are not particularly limited as long as they have melt-molding processability, and suitable ones can be selected and used according to the purpose.

The component (A) has a side chain carboxylic acid ester group which undergoes an ester exchange reaction with the ester bond of the component (B) to form a graft copolymer, which is a component of the component (A).
It is considered to enhance the compatibility of (B). In addition, even if there is a general polyacetal (C) with no ester group, the main chain structure of component (A) is close to that of component (C).
The compatibility with (C) is also improved. Therefore, the component (A) becomes (A)
, (B), (C) have the effect of increasing the compatibility of the three, and enable fine dispersion of the component (B) in the composition, and as a result, increase the impact resistance of the molded article, and Ingredient (A) and
It is considered that the interfacial adhesion between (C) and (B) was increased to suppress the surface peeling.

The blending ratio of (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 is (A) 1 to 99. % By weight (vs. (A) + (B) + (C)), 1-80% by weight (B) (vs. (A) + (B) + (C)), 0-98% by weight (C)
(Pair (A) + (B) + (C)). Above all, the sum of (A) and (C) is 95-
50% by weight and 5 to 50% by weight of (B) are preferable. When (B) is too small, the effect of improving the physical properties such as impact resistance of the polyacetal resin is poor, and when it is too large, the original polyacetal resin such as rigidity is obtained. Is not preferable because the characteristics of are lost. The ratio of (A) to (C) is selected according to the content of the ester group in the component (A) and the desired physical properties, but the component (A) is at least 1% by weight.
(Pair (A) + (B) + (C)) or more, preferably 5% by weight or more is necessary for improving dispersibility.

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

Further, the composition of the present invention may contain various known additives in order to improve the physical properties thereof depending on the intended use. Examples of additives include various stabilizers such as antioxidants, heat resistance stabilizers, weather resistance (light) stabilizers, colorants,
Lubricants, mold release agents, nucleating agents, organic polymer modifiers, and inorganic
Examples of the filler include fibrous, powdery, and plate-like fillers such as organic and metal, and one kind or a mixture of two or more kinds thereof can be used.

The composition of the present invention or a molded article thereof is basically prepared by melt-kneading the components (A) and (B), optionally with the component (C). The processing condition is (A),
It is desirable that the components (B) and (C) are kneaded at a temperature not lower than the highest melting point and not higher than 270 ° C. for at least 30 seconds. The specific mode of the preparation method is not particularly limited, but the preparation can be carried out by the equipment and method generally known as a method for preparing a synthetic resin composition or a molded article thereof. That is, the necessary components can be mixed and kneaded by using a uniaxial or biaxial extruder or another melt kneading device to obtain molding pellets, which can be molded.

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

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Preparation of Component (A) Trioxane, 4- (4-methoxycarbonyl-2-oxabutyl) -1,3-dioxolane (hereinafter abbreviated as DO-COOMe) and 1,3 in the proportions shown in Table 1. −
Using a small twin-screw continuous kneader equipped with a paddle, the monomer mixture of dioxolane was treated with boron trifluoride dibutyl etherate as a polymerization catalyst based on the total amount of monomer.
Polymerization was carried out at 80 ° C. at the concentration shown in. The polymer was crushed, the residual polymerization catalyst was deactivated with a 0.1% aqueous solution of triethylamine, and then washed and dried. Then, using a small single-screw extruder with vent holes, the vent holes were sucked at a pressure of 300 mmHg in the presence of a stabilizer, and melted and kneaded at 230 ° C to remove the unstable portion of the polymer. And stabilized to obtain the intended copolymers A-1, A-2 and A-3.
Incidentally, the molecular weight is a weight average molecular weight measured by gel permeation chromatography using hexafluoroisopropanol as a solvent, the concentration of the ester group is measured by proton NMR, the weight% as the amount of (1) formula unit in the polymer chain. Indicated by. The results are shown in Table 1.

Examples 1 to 19 As shown in Table 2, as the component (A), the above A-1, A-
Polyester elastomer (B-1) or polybutylene terephthalate (B-2), which has polybutylene terephthalate as a hard segment and polytetramethylene glycol as a soft segment, as component (B), or component (C) 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 pelletized composition. Then, using the pellets, a test piece was prepared by an injection molding machine and evaluated.
The impact strength was measured according to ASTM D256 by measuring notched Izod impact strength. Regarding the surface peeling condition, the surface appearance of the test piece, the peeling condition, color unevenness, etc. were visually observed and evaluated in the following 5 grades. The results are shown in Table 2. Comparative Examples 1 to 9 The same evaluation was performed on the examples without using each component alone or the component (A). The results are shown in Table 3.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

Claims (3)

[Claims] 1. 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 (A) 1 to 99% by weight (vs. (A) + (B)). + (C)) [Chemical 1] (In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² is a divalent ether group or alkylene group having 1 to 20 carbon atoms. R ³ is 1 carbon atom. To 4 are alkyl groups, i is 1 to 5, and j is an integer of 0 to 2.) (B) Polyester thermoplastic resin or elastomer 1 to
80% by weight (vs. (A) + (B) + (C)) (C) (A) Polyacetal resin other than 0% to 98% by weight (vs.
A polyacetal resin composition comprising (A) + (B) + (C)). 2. The polyacetal resin composition according to claim 1, wherein the unit (1) of the component (A) is represented by the following general formula (2). [Chemical 2] (In the formula, 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 thermoplastic resin as the component (B) is an alkylene terephthalate resin or a polyester elastomer composed of alkylene terephthalate and polyalkylene glycol.