JPH0339547B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel polyacetal composition, and particularly to a polyacetal composition having unprecedentedly excellent impact properties.
Many attempts have been made to improve the impact properties of polyacetal. For example, special public service in 1977-
In Japanese Patent Publication No. 18023, the addition of a so-called ionomer was added, and in Japanese Patent Publication No. 45-26231, the addition of an ethylene-acrylic acid copolymer was added.
-33095 proposes the addition of an aliphatic polyether. Polyacetal, which is a crystalline polymer, and the amorphous polymer proposed in these publications do not easily mix or dissolve, and it is extremely difficult to create a uniform composition of the two. For this reason, the compositions proposed in these publications do not sufficiently improve impact properties, and the appearance of molded products is also poor. To improve non-uniform mixing and dissolution
Publication No. 19425 describes the reaction of a trioxane copolymer containing free amino groups with a polyether containing isocyanate groups. This method requires reducing the nitro groups in the trioxane copolymer to amino groups, and the polymer has the defect of violently decomposing during the reduction operation. Furthermore, JP-A-54-155248 proposes adding an elastomer and processing aids such as segmented polyester and polyurethane to polyoxymethylene. By adopting this method, although the impact value is improved, the appearance of the molded product is still poor. This is due to the fact that uniform mixing and dissolution of the elastomer and polyoxymethylene is insufficient even when segmented polyester and polyurethane are used as processing aids. Furthermore, the strength and rigidity of molded articles based on this composition are greatly reduced due to the addition of segmented polyester and polyurethane. The decrease in strength and rigidity will become clear in the comparative examples later. Polyacetal has well-balanced physical properties,
Useful as engineering plastics. Attempts to improve impact properties even at the expense of strength and rigidity, such as the composition of the present invention, cannot necessarily be said to be an advantageous direction. As a result of extensive research on methods for improving the impact properties of polyacetal, the present inventors discovered a polyacetal composition with outstanding impact properties not found in conventional acetal polymer compositions, and completed the present invention. I came to the conclusion. Moreover, this composition maintains high strength and rigidity,
This composition can be appropriately called a highly balanced composition. That is, the present invention is composed of (A) 1.5 to 90% by weight of polyacetal, (B) a polyacetal portion, and an elastomer portion having a soft segment and a hard segment and having a secondary transition temperature of -120 to +40°C, Impact properties consisting of three components: 97.5 to 5% by weight of an acetal copolymer with a number average molecular weight between 10,000 and 500,000, and (C) 1.0 to 40% by weight of ethylene-propylene copolymer or ethylene-propylene-dien terpolymer. This invention relates to an excellent polyacetal composition. The polyacetal composition of the present invention has, for example, an Izot impact value (notched) of 8 to 100 Kg·cm/cm.
It has unprecedented impact properties. Demand for polyacetal as an engineering plastic has been increasing in recent years, and improving the impact properties of polyacetal has great industrial significance. Next, the polyacetal composition of the present invention will be explained in detail. In the present invention, the polyacetal of component A or the polyacetal segment of component B
includes polyacetal homopolymers and polyacetal copolymers. A polyacetal homopolymer is a polymer consisting of repeating oxymethylene units -(CH ₂ O-), and is obtained by homopolymerizing formaldehyde and trioxane. Polyacetal copolymer has oxyalkylene units in the chain consisting of oxymethylene units. (Ro: selected from hydrogen, alkyl group, and phenyl group, each of which may be the same or different.
This is a polymer having a structure in which =2 to 6) are randomly inserted. The insertion rate of oxyalkylene units in the polyacetal copolymer is 0.05 to 50 mol, more preferably 0.1 to 20 mol, per 100 mol of oxymethylene units. Examples of oxyalkylene units include oxyethylene units, oxypropylene units, oxytrimethylene units, oxytetramethylene units, oxybutylene units, oxyphenylethylene units, and the like. Among these oxyalkylene units, from the viewpoint of improving the physical properties of the polyacetal composition,
Particularly preferred are oxyethylene units -[( _CH2 ) _2O- ] and oxytetramethylene units -[( _CH2 ) _4O- ]. The polyacetal copolymer is obtained by copolymerizing a compound selected from formaldehyde, trioxane, and polyoxymethylene with a cyclic ether. Next, in the present invention, the acetal copolymer used as component B has a polyacetal portion (segment), a soft segment, and a hard segment, and has a second-order transition temperature (Tg,
It is a block copolymer or graft copolymer composed of a thermoplastic elastomer segment having a glass transition temperature) and having a number average molecular weight of between 10,000 and 500,000. Here, the block copolymer is A composed of a polyacetal part (A) and an elastomer part (B).
-B type diblock copolymer or A-B-A
It is a type of triblock copolymer. In addition, a graft copolymer is a polymer in which the elastomer portion is a trunk polymer and the polyacetal portion is a branch polymer. The elastomer part is a thermoplastic polymer, consisting of an amorphous segment with a low secondary transition temperature (soft segment) and a thermoreversible crosslinking and
It is a copolymer with segments (hard segments) that create a bonding structure. Here, the second order transition temperature of the elastomer part is −
The temperature must be between 120 and +40℃. −120〜
The improvement in the impact properties of the composition is only noticeable when using an elastomeric part with a second-order transition temperature of +40°C. The number average molecular weight of the acetal copolymer is 10,000
It needs to be between ~500000. When the number average molecular weight is 10,000 or more, the impact properties of the composition are significantly improved, while when the number average molecular weight is 500,000 or less, it is easy to mix and melt uniformly with the other component, polyacetal. becomes. In the present invention, the elastomer portion that is a component of the acetal copolymer is selected from the group consisting of polyolefin elastomers, polystyrene elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, and the like. The first group of elastomers, polyolefin-based elastomers, include modified ethylene-propylene copolymers and modified ethylene-propylene-diene terpolymers. Here ethylene,
Dienes to be copolymerized with propylene as termonomers include dicyclopentadiene, ethylidene norbornene, methylene norbornene, 1,
Examples include 4-hexadiene. Ethylene-propylene copolymers (EPM), ethylene-propylene-diene terpolymers (EPDM) can be used in the presence or absence of peroxides to react with maleic anhydride, acrylamide, acrylic acid, methacrylic acid, acrylic acid 2- It is modified with an acrylic ester such as hydroxylethyl, a methacrylic ester such as 2-hydroxylethyl methacrylate, or an unsaturated compound such as allyl alcohol. In the present invention, ethylene-propylene copolymers and ethylene-propylene-diene terpolymers modified with unsaturated compounds are used. The second group of elastomer moieties are polystyrene-based elastomers, with polystyrene as the hard segment. Soft segments to be combined with polystyrene include diene systems such as polybutadiene and polyisoprene, and hydrogenated diene systems such as hydrogenated polybutadiene and hydrogenated polyisoprene. Among these polystyrene-based elastomers, polystyrene-
Polybutadiene block copolymers and hydrogenated polystyrene-polybutadiene block copolymers are preferred. In addition, modified polymers such as modified polystyrene-polybutadiene block copolymers and modified hydrogenated polystyrene-polybutadiene block copolymers can also be used in the present invention. The third group of elastomer parts are polyester elastomers, which have hard segments of polyester such as polyethylene terephthalate, polybutylene terephthalate, modified polyethylene terephthalate, and polyethylene-butylene terephthalate. Soft segments to be combined with polyesters include polyethers such as polypropylene glycol, polytetramethylene glycol, and the like. Among these polyester elastomers, polybutylene terephthalate-polytetramethylene glycol block copolymer and polyethylene-butylene terephthalate-polytetramethylene glycol block copolymer are particularly preferred. The fourth group of elastomer portions are polyamide elastomers, which have polyamides such as nylon 6, nylon 6.6, nylon 6.10, nylon 11, and nylon 12 as hard segments. Soft segments to be combined with polyamide include polypropylene glycol,
Examples include polyethers such as polytetramethylene glycol, and polyesters such as polyethylene adipate and polybutylene succinate. Among these polyamide elastomers, nylon 6-
polypropylene glycol block copolymer,
Nylon 6-polytetramethylene glycol block copolymer is preferred. The fifth group of elastomer portions are polyurethane elastomers, with urethane as the hard segment. Here, urethane is produced by reacting diisocyanates such as 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate with glycols such as ethylene glycol and tetramethylene glycol. You can get it by twisting it. Soft segments to be combined with urethane include polyester diols such as polyethylene adipate and polybutylene adipate, and polyether diols such as polypropylene glycol and polytetramethylene glycol. Among these polyurethane elastomers, polyurethanes synthesized from 4,4-diphenylmethane diisocyanate, tetramethylene glycol, and polytetramethylene glycol are particularly preferred. Specific examples of the acetal copolymer are shown below. (1) Diblock copolymer (A-B type) Polyacetal/polystyrene-polybutadiene block copolymer, polyacetal/polyethylene/butylene terephthalate-polytetramethylene glycol block copolymer,
Polyacetal/nylon 6-polypropylene glycol block copolymer (adipic acid linkage) (2) Triblock copolymer (A-B-A type) Polyacetal/hydrogenated polystyrene-polybutadiene block copolymer, polyacetal/polybutylene terephthalate-polytetramethylene glycol block Copolymer, polyacetal/nylon 6-polytetramethylene glycol block copolymer (succinic acid linkage), polyacetal/polyurethane (4,
(3) Graft copolymer Polyacetal/maleic anhydride modified ethylene-propylene copolymer (maleic anhydride modified ethylene-propylene copolymer) Polymer with copolymer as the trunk polymer and polyacetal as the branch polymer), polyacetal/methacrylic acid 2-
Hydroxylethyl (HEMA) modified ethylene-propylene-ethylidene norbornene terpolymer (abbreviated as HEMA-EPDM, HEMA-
Polymers having EPDM as a trunk polymer and polyacetal as a branch polymer) Here, the elastomer content of these acetal copolymers must be in the range of 1.0 to 80% by weight. If the content of the elastomer portion is too low, no improvement in the impact properties of the composition will be observed, while if it is too high, the strength and rigidity of the composition will be reduced. Next, in the present invention, as component C, an ethylene-propylene copolymer or an ethylene-propylene-diene terpolymer is used. Examples of the diene to be copolymerized with ethylene or propylene as a termonomer include dicyclopentadiene, ethylidenenorbornene, methylenenorbornene, and 1,4-hexadiene. In the composition of the present invention, the composition ratio of the polyacetal as component A is in the range of 1.5 to 90% by weight, and the composition ratio of the acetal copolymer as component B is in the range of 1.5 to 90% by weight.
The composition ratio of component C, ethylene-propylene copolymer or ethylene-propylene-diene terpolymer, ranges from 1.0 to 5% by weight.
It is necessary that the content be within the range of 40% by weight. When the composition ratio of the acetal copolymer is 5% by weight or more, the impact properties of the composition are significantly improved, and the miscibility of the polyacetal with the ethylene-propylene copolymer or ethylene-propylene-diene terpolymer is good. Become. On the other hand, it is extremely easy to produce a polyacetal composition having an acetal copolymer composition of 97.5% by weight or less in terms of polymerization technology. Therefore, based on these two constraints, the composition ratio of the acetal copolymer is set between 97.5 and 5% by weight. Next, when the composition ratio of ethylene-propylene copolymer or ethylene-propylene-diene terpolymer is 1.0% by weight or more, the impact properties of the composition are improved. On the other hand, when the composition ratio is 40% by weight or less, the miscibility of the polyacetal and the ethylene-propylene copolymer or ethylene-propylene-diene terpolymer is good. Therefore, due to these two constraints, ethylene-propylene copolymer or ethylene-propylene-
The composition ratio of diene terpolymer is 1.0 to 40% by weight
Set between. In order to further improve the impact properties of the polyacetal composition, the composition ratio of the polyacetal as component A should be in the range of 4.0 to 80% by weight, and the composition ratio of the acetal copolymer as component B should be in the range of 94 to 10% by weight. It is more preferable that the composition ratio of the ethylene-propylene copolymer or ethylene-propylene-diene terpolymer of component C is in the range of 2.0 to 35% by weight. The composition of the present invention can be obtained by mixing each component in a conventional extruder or the like, or by simultaneously obtaining a mixture of polyacetal and acetal copolymer through a polymerization reaction, This is combined with ethylene-propylene copolymer or ethylene-
It can also be obtained by adding a propylene-diene terpolymer and then mixing in an extruder. It is also possible to further add and use a conventionally known compound as a stabilizer for polyacetal to the composition of the present invention. The first of the known stabilizers are thermal stabilizers, such as amide compounds, polyamides, amidine compounds, melamine, polyvinylpyrrolidone, carboxylic acid metal salts, and the like. A second type of known stabilizer is an antioxidant, such as a hindered phenol compound. Further, the third known stabilizer is a light stabilizer,
Examples include benzotriazole compounds and hydroxybenzophenone compounds. These stabilizers are usually polyacetal compositions
It is added in an amount of 0.05 to 10 parts by weight, more preferably 0.08 to 3 parts by weight, per 100 parts by weight. Hereinafter, the present invention will be specifically explained with reference to Examples. The measurement items in the examples are as follows. MI: 0.25 parts of 2,2-methylene-bis(4-methyl-6-tert-butylphenol) to 100 parts of the polymer composition that has been terminally stabilized using acetic anhydride.
1 part, and 0.50 part of nylon 6.6 were added thereto and pelletized using a 50 mmφ extruder. of this pellet
MI was measured according to ASTM-D1238-57T. MI
is a measure of molecular weight. Izot impact value (notched): The above pellet was molded into a flat plate using an injection molding machine. A test piece was cut from this flat plate and measured according to ASTM-D256. The larger the Izot impact value, the better the impact properties. Vibration fatigue characteristics: Cut a test piece from a flat plate,
Measured in accordance with ASTM-D671 at 20°C and repeated vibration cycles of 1800 times/min. 10 The maximum stress that does not cause the specimen to break when subjected to repeated vibrations ⁶ times = fatigue strength, which is used as an index of fatigue resistance. The higher the fatigue strength, the better the fatigue resistance. Tensile strength: Cut a test piece from a flat plate, ASTM
−Measured according to D638. The higher the tensile strength, the better the strength and rigidity. Example 1 (1) Manufacturing method of polyacetal composition 1-1 Polyacetal (component A) Formaldehyde gas with a purity of 99.9% was used as a molecular weight regulator at a rate of 100 parts per hour (hereinafter, parts are expressed as parts by weight). , 0.12gr/methanol, 3.5×10 ^-4 mol/ as polymerization catalyst
toluene containing dibutyltin dimethoxide
It was continuously fed into 500 parts for 3 hours. Toluene containing a molecular weight regulator and a polymerization catalyst at the above concentrations was also continuously supplied at a rate of 500 parts/hr for 3 hours, and the polymerization temperature was maintained at 59° C. during this period.
The polymer was separated from toluene, washed and dried to obtain 283 parts of polymer. The ends of this polymer were then blocked with acetic anhydride to obtain a thermally stabilized polyacetal homopolymer. 1-2 Acetal copolymer (component B) 99.9% pure formaldehyde gas at a rate of 100 parts per hour as a molecular weight regulator.
55.2 gr/ml of hydrogenated polystyrene-polybutadiene block copolymer was continuously fed for 3 hours into 500 parts of toluene containing 3.5 mol/ml of dibutyltin dimethoxide as a polymerization catalyst. Toluene containing a molecular weight regulator and a polymerization catalyst at the above concentration was also added at a rate of 500 parts/hr.
The polymerization temperature is 57℃ during this period.
maintained. Separate the polymer from toluene,
After washing and drying, 405 parts of a polymer was obtained. Next, the ends of this polymer were blocked with acetic anhydride to obtain a thermally stable acetal copolymer. The hydrogenated polystyrene-polybutadiene block copolymer used here as a molecular weight regulator is composed of the following soft segments and hard segments, and the polymer terminal has 1 hydroxyl group.
It is something that is owned individually. Soft segment (unit) - (CH ₂ - CH ₂ - CH ₂ - CH ₂ -) Hard segment (unit) The elastomer content of this polymer is
42% by weight, and the number average molecular weight is 7×10 ⁴ . 1-3 Ethylene-Propylene Polymer (Component C) Ethylene and propylene were copolymerized using VOCl ₃ -(C ₂ H ₅ ) ₃ Al as a catalyst to obtain a random copolymer. The ethylene content of this polymer is
72mol%, MI is 0.4gr/10min (190°C). (2) Composition Components A, B, and C obtained in (1) were mixed in the following composition and homogenized using a 50 mmφ extruder. Component A Polyacetal (homopolymer)
70% by weight Component B Acetal copolymer 15% by weight Component C Ethylene-propylene copolymer
15% by weight The physical properties of this composition are as follows, and it has excellent impact properties as well as fatigue resistance, strength, and rigidity. MI 9.0 (gr/10 minutes) Izot impact value 25.3 (Kg・cm/cm) Fatigue strength 255 (Kg/cm ² ) Tensile strength 580 (Kg/cm ² ) Example 2 (3) Manufacturing method of polyacetal composition 3- 1 Polyacetal (Component A) After mixing 98% of anhydrous trioxane and 2% of ethylene oxide in a kneader having two Σ blades, boron trifluoride dibutyl etherate as a polymerization catalyst was added to initiate polymerization. After polymerization at 80°C for 15 minutes, tributylamine was added to stop the polymerization. A mixture of triethylamine and water was added to this polymer, and the mixture was fed to a 30 mmφ extruder equipped with a vent to stabilize the terminals of the polymer to obtain a thermally stable polyacetal copolymer. The oxyethylene unit insertion rate in this polymer was 1.5 mol%. 3-2 Acetal copolymer (component B) Anhydrous formaldehyde and ethylene oxide, polybutylene terephthalate-polytetramethylene glycol block copolymer as a molecular weight regulator, dimethyl distearyl ammonium acetate and boron trifluoride dibutyl etherate as a polymerization catalyst were supplied into toluene coexisting with the above, and polymerized. The polymer was stabilized by end-capping with acetic anhydride. The polybutylene terephthalate-polytetramethylene glycol block copolymer used here as a molecular weight regulator was dimethyl terephthalate, ethylene glycol,
It is a polymer synthesized using tetramethylene glycol and polytetramethylene glycol as raw materials, and has one hydroxyl group and one carboxyl group at the end of the polymer, and is mainly composed of the following soft segments and hard segments. . The elastomer content of this polymer is
46% by weight, and the number average molecular weight is 4×10 ⁴ . In addition, 1.5 mol% of oxyethylene units are inserted into the polyacetal portion. 3-3 Ethylene-propylene-diene terpolymer A random terpolymer was obtained using ethylene, propylene, and ethylidene norbornene as raw materials. (4) Composition Components A, B, and C obtained in (3) were mixed in the following composition and homogenized using a 50 mmφ extruder. Component A Polyacetal (copolymer) 55% by weight Component B Acetal copolymer 20% by weight Component C Ethylene-propylene-ethylidene norbornene terpolymer 25% by weight The physical properties of this composition are as follows, and it has excellent impact properties. have. MI 4.0 (gr/10 minutes) Izot impact value 23.7 (Kg・cm/cm) Fatigue strength 250 (Kg/cm ² ) Tensile strength 520 (Kg/cm ² ) Example 3 (5) Manufacturing method of polyacetal composition 5- 1 Polyacetal and acetal copolymer (components A, B) Anhydrous formaldehyde gas per hour
as a molecular weight regulator in the proportion of 100 parts;
0.081 gr/methanol and 46.0 gr/polybutylene terephthalate-polytetramethylene glycol block copolymer, continuously for 3 hours in 500 parts of toluene containing 3.0 x 10 ^-4 mol/ dimethyl distearyl ammonium acetate as polymerization catalyst. supplied. The polybutylene terephthalate-polytetramethylene glycol block copolymer used here as a molecular weight regulator has two hydroxyl terminals synthesized from the following raw materials and has the following soft segments and hard segments. Dimethyl terephthalate Tetramethylene glycol Polytetramethylene glycol Toluene containing the molecular weight regulator and polymerization catalyst at the above concentrations was continuously fed at a rate of 500 parts/hr for 3 hours, and the polymerization temperature was maintained at 62° C. during this period. The polymer was separated from toluene, then washed and dried to obtain 432 parts of polymer.
This polymer was stabilized by acetylation. Next, the terminal groups of the polymer were analyzed and quantified using infrared absorption spectroscopy and Zeisel method. The resulting polymers are as follows:
It has become clear that it is made up of different types of polymers. Polyacetal (homopolymer) 43% by weight Acetal copolymer 57% by weight The elastomer content of the acetal copolymer is 52% by weight, and the number average molecular weight is
It is 2.5× ¹⁰⁴ . 5-2 Ethylene-Propylene Copolymer A random copolymer was obtained using ethylene and propylene as raw materials. The ethylene content of this polymer is 67 mol%, and the MI is 0.2 gr/10 min (190
℃). (6) Composition Components A, B, and C obtained in (5) were mixed in the following composition and homogenized using a 30 mmφ twin screw extruder. Component A Polyacetal (homopolymer)
32% by weight Component B Acetal copolymer 43% by weight Component C Ethylene-propylene copolymer
25% by weight The physical properties of this composition are as follows, and it has excellent impact properties. MI 2.6 (gr/10 minutes) Izot impact value 39.4 (Kg・cm/cm) Fatigue strength 250 (Kg/cm ² ) Tensile strength 550 (Kg/cm ² ) Example 4 (7) Preparation of polyacer composition 7 -1 Polyacetal and acetal copolymer (components A, B) Formaldehyde at a ratio of 100 parts/hr, ethylene oxide at a ratio of 2.2 parts/hr, as a molecular weight regulator, 0.014 gr/water and 41.6 gr/hr.
of nylon 6-polypropylene glycol block copolymer in 500 parts of toluene for 5 hours. The elastomer used here as a molecular weight regulator was synthesized from the following raw materials and is a polymer having one carboxyl group end with the amino group end blocked with acetic acid. Prepolymer made by reacting polypropylene glycol and adipic acid ε-caprolactam polymer (nylon 6) This polymer also consists of the following soft segments and hard segments. Toluene containing a molecular weight regulator at the above concentration was also continuously fed at a rate of 500 parts/hr for 5 hours. In addition, as a polymerization catalyst, tetrabutylammonium acetate and boron trifluoride dibutyl etherate were added at 0.03 parts/hr and 0.08 parts, respectively.
parts/hr continuously for 5 hours through separate conduits, during which time the polymerization temperature was maintained at 60°C. The polymer was separated from toluene, washed and dried to obtain 582 parts of polymer. The obtained polymer was stabilized by acetylating the terminal. As a result of terminal analysis and elastomer content analysis, it was revealed that this polymer was composed of the following two types of polymers. Polyacetal (copolymer) 41% by weight Acetal copolymer 59% by weight The elastomer content in the acetal copolymer is 35% by weight, and the number average molecular weight is
It is 2.5× ¹⁰⁴ . Furthermore, 1.5 mol% of oxyethylene units are inserted into the polyacetal portion of the polyacetal and acetal copolymer. 7-2 Ethylene-propylene-diene terpolymer A random terpolymer was obtained using ethylene, propylene, and dicyclopentanediene as raw materials. (8) Composition Components A, B, and C obtained in (7) were mixed in the following composition and homogenized using a 30 mmφ twin screw extruder. Component A Polyacetal (copolymer) 35% by weight Component B Acetal copolymer 50% by weight Component C Ethylene-propylene-dicyclopentadiene terpolymer 15% by weight The physical properties of this composition are as follows, with excellent impact properties. It has characteristics. MI 6.5 (gr/10 minutes) Izot impact value 26.3 (Kg・cm/cm) Fatigue strength 255 (Kg/cm ² ) Tensile strength 550 (Kg/cm ² ) Example 5 (9) Manufacturing method of polyacetal composition 9- 1 Polyacetal and acetal copolymer (components A, B) 5.02 kg of polyoxymethylene, ethylene glycol formal, sufficiently dried under reduced pressure
420 gr, 2.1 gr of acetic acid as a molecular weight regulator, 3.25 kg of maleic anhydride-modified hydrogenated polystyrene-polybutadiene block copolymer, and 50 kg of cyclohexane were charged into the reaction tank. The elastomer used here as a molecular weight regulator is
This is a polymer obtained by hydrogenating a polystyrene-polybutadiene block copolymer synthesized by a living polymerization method and then modifying it with maleic anhydride in an extruder, and has three carboxylic anhydride groups in the polymer. After charging, the contents of the reaction tank were heated to 70°C. The reaction was started by adding 1.25g of boron trifluoride dibutyl etherate to the reaction tank.
After maintaining the internal temperature of the reaction tank at 70℃ for 30 minutes,
The reaction was stopped by adding 570 gr of cyclohexane containing 150 gr of tributylamine. After separating the polymer, it was washed 5 times with a large amount of toluene,
8.18Kg of polymer was recovered. Next, triethylamine-water was added to this polymer and stabilized using a 50 mmφ extruder. As a result of analysis of the end groups of the polymer, it was revealed that the polymer obtained here was composed of the following two types of polymers. Polyacetal (copolymer) 25% by weight Acetal copolymer (graft copolymer with maleic anhydride-modified hydrogenated polystyrene-polybutadiene block copolymer as the trunk polymer and polyacetal copolymer as the branch polymer) 75% by weight The elastomer fraction content in the polymer is 46% by weight and the number average molecular weight is 5×10 ⁴ . Furthermore, 1.5 mol% of oxyethylene units are inserted into the polyacetal portion of the polyacetal and acetal copolymer. 9-2 Ethylene-propylene-diene terpolymer A random terpolymer was obtained using ethylene, propylene, and 1,4-hexadiene as raw materials. (10) Composition Components A, B, and C obtained in (9) were mixed in the following proportions and homogenized using a 30 mmφ twin screw extruder. Component A Polyacetal (copolymer) 23% by weight Component B Acetal copolymer 67% by weight Component C Ethylene-propylene-1,4-hexadiene terpolymer 10% by weight The physical properties of this composition are as follows and are excellent. It has excellent impact properties. MI 4.7 (gr/10 minutes) Izot impact value 32.5 (Kg/cm/cm) Fatigue strength 250 (Kg/cm ² ) Tensile strength 528 (Kg/cm ² ) Examples 6 to 27 Polyacetal, acetal copolymer, and ethylene -Propylene copolymer or ethylene-
The compositions shown in Table 1 were obtained from the three propylene-diene terpolymer components. The physical property values of these compositions are also shown in Table 1. In all Examples, compositions with excellent impact properties were obtained. Comparative Example 1 (method disclosed in JP-A-54-155248) The polyacetal synthesized in 1-1 of Example 1 was added with ethylene-vinyl acetate copolymer as an elastomer, and dimethyl terephthalate and dimethyl isophthalate as processing aids. The following composition was prepared by adding a segmented polyester synthesized from , tetramethylene glycol and polyethylene glycol. Polyacetal 90% by weight EVA copolymer 5% by weight Segmented polyester 5% by weight This composition was uniformly mixed using a 50 mmφ extruder. The physical properties of this composition are as follows. MI 9.2 (gr/10 minutes) Izot impact value 9.6 (Kg・cm/cm) Fatigue strength 190 (Kg/cm ² ) Tensile strength 520 (Kg/cm ² ) Although the impact properties have been slightly improved, fatigue strength , the decrease in tensile strength is large. The physical properties of the polyacetal 1-1 are as follows. MI 12.0 (gr/10 minutes) Izot impact value 6.2 (Kg・cm/cm) Fatigue strength 280 (Kg/cm ² ) Tensile strength 720 (Kg/cm ² ) Comparative example 2 (without adding acetal copolymer) The ethylene-propylene-diene terpolymer obtained in 3-3 of Example 2 was added to the polyacetal obtained in 3-1 of Example 2 to obtain the following composition. Polyacetal 69% by weight Ethylene-propylene-ethylidene norbornene terpolymer 31% by weight This composition was uniformly mixed using a 50 mmφ extruder. The physical properties of this composition are as follows. MI 6.1 (gr/10 minutes) Izot impact value 6.9 (Kg/cm/cm) Fatigue strength 190 (Kg/cm ² ) Tensile strength 425 (Kg/cm ² ) Although impact properties have been slightly improved, fatigue strength , the tensile strength decreased significantly. In addition, the physical property values of the polyacetal of 3-1 are as follows. MI 7.5 (gr/10 minutes) Izot impact value 5.6 (Kg・cm/cm) Fatigue strength 275 (Kg/cm ² ) Tensile strength 645 (Kg/cm ² ) Comparative example 3 (When component C is not added) Example The following composition was prepared using component A (polyacetal) obtained in step 9 and component B (acetal copolymer of polyacetal and polyethylene terephthalate-polyethylene glycol block copolymer). Component A 85% by weight Component B 15% by weight This composition was uniformly mixed using a 50 mmφ extruder. The physical properties of this composition are as follows. MI 6.2 (gr/10 minutes) Izot impact value 9.1 (Kg・cm/cm) Fatigue strength 240 (Kg/cm ² ) Tensile strength 630 (Kg/cm ² ) Improved impact properties when component C is not added is small.

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Claims (1)

[Scope of Claims] 1 (A) 1.5 to 90% by weight of polyacetal (B) A polyacetal portion and a thermoplastic elastomer portion having a soft segment and a hard segment and having a secondary transition temperature of -120 to +40°C composed of a number average molecular weight of 10,000~
Acetal copolymer between 500,000 and 97.5 to 5
Weight % (C) Ethylene-propylene copolymer or ethylene-propylene-diene terpolymer 1.0
~40% by weight polyacetal composition. 2 The polyacetal of component A or the polyacetal part of component B has an oxymethylene unit -(
The composition according to claim 1, which is a polyacetal homopolymer consisting of repeating _CH2O- ). 3 The polyacetal of component A or the polyacetal part of component B contains oxyalkylene units in a polymer consisting of repeating oxymethylene units. (Ro: selected from hydrogen, alkyl group, and phenyl group, each of which may be the same or different.
2. The composition according to claim 1, which is a polyacetal copolymer having a structure in which 2 to 6) are randomly inserted. 4. The composition according to claim 1 or 3, wherein the oxyalkylene unit is an oxyethylene unit -[( _CH2 ) _2O )-]. 5. The composition according to claim 1 or 3, wherein the oxyalkylene unit is an oxytetramethylene unit -[( _CH2 ) _4O- ]. 6. The composition according to claim 1, wherein the elastomer portion of component B is an elastomer selected from the group consisting of polyolefin elastomers, polystyrene elastomers, polyester elastomers, polyamide elastomers, and polyurethane elastomers. 7. The composition according to claim 1 or 6, wherein the polyolefin elastomer is a modified ethylene-propylene copolymer or a modified ethylene-propylene-diene terpolymer. 8. The polystyrene elastomer according to claim 1 or 6, wherein the polystyrene elastomer is an elastomer selected from the group consisting of polystyrene-polybutadiene block copolymer, hydrogenated polystyrene-polybutadiene block copolymer, and modified hydrogenated polystyrene-polybutadiene block copolymer. Composition. 9. The composition according to claim 1 or 6, wherein the polyester elastomer is a polybutylene terephthalate-polytetramethylene glycol block copolymer or a polyethylene-butylene terephthalate-polytetramethylene glycol block copolymer. 10 Polyamide elastomer is nylon-
7. The composition according to claim 1 or 6, which is a 6-polypropylene glycol block copolymer or a nylon-6-polytetramethylene glycol block copolymer. 11 Polyurethane elastomer is 4,4-
7. The composition according to claim 1 or 6, which is a polyurethane synthesized from diphenylmethane diisocyanate, tetramethylene glycol, and polytetramethylene glycol. 12. The composition according to claim 1, wherein the elastomer content of the acetal copolymer of component B is in the range of 1.0 to 80% by weight.