JPH02166150A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition of improved impact resistance by mixing a polyacetal resin with a specified polyester/polyester block copolymer. CONSTITUTION:A prepolymer obtained by transesterifying an aromatic dicarboxylic acid (esterifiable derivative) (a) with an aliphatic diol (b) at 150-240 deg.C in the presence of a polycondensation catalyst and removing the formed methanol from the reaction product is reacted with a polylactone or an aliphatic dicarboxylic acid (esterifiable derivative) (c) and component (b) at 230-260 deg.C in a high vacuum for several min, and the catalyst is deactivated by the addition of a phosphorus compound to obtain a polyester-polyester block copolymer (A) which is a segmented block copolymer containing a hard segment derived from components (a) and (b) and a soft segment derived from components (b) and (c) in a weight ratio of (40-95)/(60-5). 100 pts.wt. polyacetal resin is mixed with 1-100 pts.wt. copolymer (A).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polyacetal resin composition having excellent impact resistance. More specifically, by adding a polyester block copolymer, a polyacetal resin composition having excellent impact resistance can be obtained.

<Prior Art> Polyacetal resin is an engineering plastic with excellent mechanical strength and R abrasion resistance, and is widely used as mechanical components in automobile parts and electrical/electronic equipment.

However, other engineering plastics,
For example, it has inferior IT resistance compared to polyamide.

Conventionally, various methods have been proposed to improve the impact resistance of polyacetal resin. For example, JP-A-47
In Japanese Patent No. 11136, it is proposed that impact strength can be improved by adding an inorganic nucleating agent such as boron nitride or antimony dioxide to a polyacetal resin.

Further, Japanese Patent Publication No. 48-34830 proposes a method of adding a rubber elastic graft copolymer.

On the other hand, a method of adding polyether ester is proposed in JP-A-52-85249.

Further, a method of adding a polyurethane elastomer has been proposed in JP-A-59-155452.59-145244.

<Problems to be Solved by the Invention> However, in the method disclosed in JP-A No. 47-11136, cracks are likely to occur from the agglomerated portions of the inorganic additive, and the heat resistance is significantly reduced. It has the disadvantage of

Furthermore, the method disclosed in Japanese Patent Publication No. 4B-34830 has the disadvantage that the rubber component reduces the rigidity, which is a characteristic of polyacetal resin.

On the other hand, JP-A-52-85249.59-155452.
In the method disclosed in Publication No. 59-145244,
Since the compatibility of the polyether ester, polyurethane elastomer, and polyacetal resin is insufficient, the blend is non-uniform1, and a significant increase in impact resistance cannot be expected.

Therefore, an object of the present invention is to provide a polyacetal resin composition with an excellent balance between impact resistance and rigidity.

<Means for solving r4a> The present inventors have solved the above fl! As a result of intensive studies to solve the problem, it was discovered that the above object can be achieved by adding a polyester block copolymer having a specific copolymerization composition to a polyacetal resin, and the present invention was achieved.

That is, the present invention is a resin composition comprising 1 to 1001 parts by weight of a polyester-polyester type block copolymer per 100 parts by weight of a polyacetal resin,
The polyester-polyester block copolymer includes (a) a hard segment derived from an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol; (b) a polylactone or an aliphatic dicarboxylic acid or an ester-forming derivative and an aliphatic diol; The present invention is a segmented block copolymer comprising soft segments derived from diols, and provides a resin composition in which the weight ratio of hard segments to soft segments is 40/60 to 9515.

The polyacetal resin used in the present invention is an oxymethylene homopolymer, which is mainly composed of oxymethylene units, and contains up to 1531% by weight of oxyalkylene units having 2 to 8 adjacent carbon atoms in the main chain. Means a methylene copolymer.

The method for producing the oxymethylene homopolymer and oxymethylene copolymer is not particularly limited, and the oxymethylene homopolymer and the oxymethylene copolymer are produced by a known production method.

For example, a typical method for producing an oxymethylene homopolymer involves introducing substantially anhydrous formaldehyde into an organic solvent containing a basic polymerization catalyst such as an organic amine, polymerizing it, and then polymerizing it with acetic anhydride. Examples include a manufacturing method in which stabilization is achieved by oxidation or the like.

Further, typical methods for producing oxymethylene copolymers include substantially anhydrous trioxane and ethylene oxide; A copolymer component such as 3-dioxolane in a solvent such as cyclohexane or without a solvent,
Examples include a method of manufacturing by polymerizing with a Lewis acid catalyst such as boron trifluoride/diethyl etherate and decomposing and removing unstable terminals with a basic compound.

The polyester-polyester type block copolymer used in the present invention is a block copolymer having crystalline polyester as a hard segment and non-grade polyester as a soft segment.

Hard segments are derived from aromatic dicarboxylic acids and aliphatic diols. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2
, 6-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, 3-sulfoisophthalic acid, or a mixture thereof, and terephthalic acid, isophthalic acid, or a mixture of both is particularly preferred. An aliphatic dicarboxylic acid may be copolymerized as long as the amount is 1.
．． 4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, dicyclohexyl-4,4'-
Examples include dicarboxylic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dimic acid, and especially 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, decanedicarboxylic acid, dimic acid, etc. Acids are preferably used.

In addition, examples of the aliphatic diol component constituting the hard segment unit include ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, 1. 6-hexanediol, 1. lO-decanediol, neopentyl glycol, 1. 4-Cyclohexane dimetatool or a mixture thereof is used, with ethylene glycol and 1,4-butanediol being particularly preferred.

On the other hand, the soft segment is derived from an intercyclic lactone, ie, a polylactone, or an aliphatic dicarboxylic acid and an aliphatic diol. As polylactone, the general formula (X
) is used. n
is an integer from 2 to 20, and ε-caprolactone where n=4 is particularly preferred.

Aliphatic dicarboxylic acids constituting the soft segment include oxalic acid, succinic acid, adipic acid, azelaic acid,
Examples include sebacic acid and decanedicarboxylic acid, with adipic acid, sebacic acid, and decanedicarboxylic acid being particularly preferred.Also, examples of aliphatic diols constituting the soft segment include ethylene glycol, propylene glycol, and l.

4-butanediol, diethylene glycol, l.

6-hexanediol, 1.10-decanediol, neopentyl glycol, 1. 4-Cyclohexane dimetatool or a mixture thereof is used,
Especially ethylene glycol, 1. 4-butanediol is preferred.

In the polyester block copolymer used in the present invention, the composition ratio of hard segment and soft segment units is such that the hard segment is 40 to 95% by weight, especially 4% by weight.
5 to 90% by weight is preferred.

If the hard segment unit exceeds 95% by weight, the compatibility with the polyacetal resin will deteriorate. On the other hand, 40% by weight
A lower value is not preferred because polymerization of the polyester block copolymer becomes difficult and the mechanical strength of the composition decreases.

The method for producing the polyester block copolymer is not particularly limited, and is usually produced by a known method. Approximately 150-240℃
Heating to a temperature of 230 to 260 °C to carry out a transesterification reaction and remove the generated methanol.
A block copolymer can be produced by heating the reaction at ℃ for several minutes and then adding a phosphorus compound to deactivate the catalyst.

Other methods include, for example, a method of preparing a block copolymer by heating and mixing a high melting point hard segment prepared in advance with a lactone monomer and carrying out a transesterification reaction while ring-opening the lactone.

In the present invention, the amount of polyester-polyester block copolymer added is polyacetal resin 11i1001
The amount is 1 to 100 parts by weight, preferably 2 parts by weight.
~50 parts by weight. If the amount of the polyester-polyester block copolymer added is less than 1 part by weight, the effect of improving impact resistance will be small, and if it exceeds 100 parts by weight, the properties of the polyacetal resin, especially the mechanical strength, will be significantly impaired, which is not preferable. .

The method for producing the polyacetal resin composition of the present invention is not particularly limited, but it is preferably produced by melt-kneading a polyacetal resin and a polyester-polyester block copolymer. Examples of melt-mixing methods include, for example: 120-280℃ using a Banbury mixer roll kneader, -screw or twin-screw extruder, etc.
A method of melting and kneading at a temperature of

In addition, the polyacetal resin composition of the present invention may include known antioxidants such as hindered phenol-based, phosphite-based, thioether-based, and amine-based antioxidants, benzophenone-based, hindered amine-based, etc., to the extent that the purpose of the present invention is not impaired. weathering agent, formaldehyde scavenger such as melamine, dicyandiamide, polyamide, polyvinyl alcohol copolymer, fluorine-containing polymer, silicone oil, metal stearate, metal montanate, montan acid ester wax, polyethylene wax, etc. Molding agents, colorants such as dyes and pigments, ultraviolet shielding agents such as titanium oxide and carbon black, glass fibers and carbon fibers, reinforcing agents such as titanate potassium fiber, fillings such as silica, clay, calcium carbonate, calcium sulfate, glass peas, etc. A nucleating agent such as talc, a flame retardant, a degradable agent, an adhesion aid, an adhesive, etc. can be optionally contained.

Furthermore, for the purpose of improving the mechanical strength of the polyacetal resin composition of the present invention, other thermoplastic polymers or thermoplastic elastomers may be included.

<Example> The present invention will be explained in detail below using Examples.

Note that all percentages and parts in the examples are based on weight. Moreover, the relative viscosity (ηr) is a value measured at 25° C. of a 0.5% polymer solution using 0-chlorophenol as a solvent. The mechanical properties, average particle diameter, MI value, and melting point of the molded articles shown in Examples and Comparative Examples were measured as follows.

Molding: Using an injection molding machine with a 5 oz. The square plate was injection molded.

Mechanical Properties 2 The tensile strength was measured according to the ASTM D-638 method using the ASTMI dumbbell test piece obtained by the above injection molding. In addition, impact strength was measured using an Izot impact test piece according to ASTM D-256 method.

MI value: ASTM D-1238 method (temperature 190
℃.

The measurement was carried out with a load of 2160 g).

Melting point: Determined by SC (differential scanning calorimetry) at a heating rate of 10° C./min.

In addition, acetal copolymer is copolymerized with ethylene oxide, has an MI value of 9.0 g/10 minutes, and a melting point of 167°C.
polymer was used. Acetal homopolymer has stabilized polymer terminals by acetylation and has an MI value of 9.0g.
/10 minutes, a polymer with a melting point of 175°C was used.

Reference example 1 Polybutylene terephthalate with ηr of 1.47 97.0
3.0 parts of ε-caprolactone and 0.05% of titanium tetrabutoxide catalyst (based on polymer) were charged into a reaction vessel equipped with a helical ribbon stirring blade, and heated at 50 to 260°C.
The mixture was heated and melted for 3 hours to form a transparent homogeneous melt. after that,
The polymerization reaction was stopped by adding 0.5 parts of phosphorus MO. The obtained polymer was discharged into water in the form of a strand and cut into pellets. This polymer is designated as A-1. Polymerization was carried out in the same manner, and A-
2, A-3, A-4, and A-5 were prepared.

Table 1 also lists the relative viscosity (ηr) of the obtained polymer.

Margin Table 1 Below Examples 1 to 6, Comparative Examples 1 to 6 10 parts of the polyester block copolymer produced in Reference Example 1 was mixed with 100 parts of the polyacetal copolymer and homopolymer, and the mixture was heated in a twin-screw 30 mmφ extruder. The mixture was melt-kneaded using a cylinder temperature of 186°C. Table 2 shows the properties of the molded product obtained. From Table 2, it is clear that the composition of the present invention has excellent mechanical properties and impact resistance.

Margin Examples 9 to 16 below. Comparative example! , 4. 7.8 0 to 12031 parts of polyester block copolymer 8-4) per 100 parts of polyacetal copolymer and homopolymer
They were mixed in a ratio of 11 parts and melt-kneaded under the same conditions as in Example 1. The physical properties of the obtained molded article are shown in Table 3. From Table 3, it can be seen that the addition of the polyester block copolymer increases the Izot impact value.

In addition, polybutylene ethylene terephthalate with ηr of 1.47) 4
0.0 parts and 43.8 parts of adipic acid, ! .

Under high vacuum, 27.0 parts of 4-butanediol was added to 230-2.
After a heating reaction at 60° C. for several minutes, triphenylphosphine was added to deactivate the catalyst, thereby producing a polyester block copolymer. Even when this block copolymer was melt-kneaded at a ratio of 10 parts to the polyacetal copolymer and homopolymer, the
! The effect of increasing the value was observed.

Margins below <Effects of the Invention> The resin composition of the present invention has excellent mechanical properties, particularly impact resistance, and thus can be used in a wide range of applications including mechanical parts such as gears.

Claims (1)

[Scope of Claims] A resin composition comprising 1 to 100 parts by weight of a polyester-polyester type block copolymer based on 100 parts by weight of a polyacetal resin, the resin composition comprising:
The polyester block copolymer has (a) a hard segment derived from an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol; and (b) a polylactone or an aliphatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol. A segmented block copolymer consisting of derived soft segments, with a weight ratio of hard segments to soft segments of 40/60 to
A resin composition with a rating of 95/5.