JPH0312583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyacetal resin composition that has excellent rigidity, bending strength, impact resistance, and heat resistance, is free from delamination, and has excellent moldability. Polyacetal resins are expected to be in great demand as engineering plastics because of their excellent heat resistance and mechanical properties.
Polyacetal resin has a characteristic that its mechanical properties have little temperature dependence, so it can be used under a wide range of temperature conditions. It has the disadvantage that it is easily broken if there are small scratches or scratches, and it is not suitable for molding mechanical parts such as gears, bolts, and nuts, or molded products with complex shapes. Therefore, in order to expand the demand for polyacetal resins, it is strongly desired to improve their impact resistance. Conventionally, many attempts have been proposed to improve the physical properties of polyacetal resins, such as their impact resistance. For example, Japanese Patent Publications No. 45-12674 and Japanese Patent Publication No. 45-18023 describe methods for blending unsaturated rubbers, Japanese Patent Publication No. 41-2730, Japanese Patent Publication No. 42-18023
Publication No. 19498, Japanese Patent Publication No. 1972-20376, Japanese Patent Application Publication No. 1973
-15954 Publication, JP-A-49-40346, JP-A-Sho
Publication No. 50-103556 describes polyethylene, polypropylene, polybutene, ethylene/α-olefin elastic copolymers, mixtures of α-olefin polymers and ethylene/vinyl monomer copolymers, and α-olefin polymers such as polyolefins. Method of blending, Japanese Patent Publication No. 43-22669,
-6134 Publication, Special Publication No. 45-26231, Special Publication Sho
Publication No. 45-18023 describes ethylene/vinyl acetate copolymer, saponified product or saponified acetalized product of ethylene/vinyl acetate copolymer, ethylene/(meth)
Acrylic ester copolymer, α-olefin,
A method of blending a polar group-containing α-olefin copolymer such as a metal neutralized salt of an α,β-unsaturated carboxylic acid copolymer has been proposed. Among these methods, the first method of blending unsaturated rubbers has the disadvantage of significantly lowering the heat resistance and weather resistance of the polyacetal resin, and the second method of blending α-olefin polymers is disadvantageous. In this method, the affinity between the polyacetal resin and the α-olefin polymer is poor, so even if the composition is melt-kneaded, it tends to peel off into layers, and a composition with sufficient mechanical strength cannot be obtained. In addition, the third method of blending a polar group-containing α-olefin copolymer can improve impact resistance, but it is insufficient, and in particular, there is a drawback that notched Izo impact strength is not improved much. As a result of intensive study on the development of a polyacetal resin composition with excellent performance, the present inventors found that by blending a specific modified α-olefin polymer with a polyacetal resin to create a composition, the impact resistance The inventors have discovered that a polyacetal resin composition can be obtained that has significantly improved properties, and has excellent heat resistance, mechanical properties, weather resistance, and moldability, and has thus arrived at the present invention. To summarize the present invention, the present invention provides a composition comprising a polyacetal resin (A) and a modified α-olefin polymer (B), [] a modified α-olefin polymer in the composition;
(B) is in the range of 1 to 200 parts by weight per 100 parts by weight of the polyacetal resin (A); [] the modified α-olefin polymer (B) is α-
Modified by graft copolymerizing 0.01 to 10 parts by weight of unsaturated carboxylic acid or its acid anhydride component units to 100 parts by weight of a base α-olefin polymer containing olefin component units as a main component. The gist of the invention is a polyacetal resin composition characterized by being an α-olefin polymer. The polyacetal resin blended into the composition of the present invention is a homopolymer of formaldehyde, trioxane, tetraoxane, etc., a copolymer of two or more thereof, or a combination of the monomer and a cyclic ether, cyclic ester, or vinyl compound. It also includes copolymers with. Here, the cyclic ether includes ethylene oxide, propylene oxide,
Examples include oxacyclobutane and 1,3-dioxolane, and examples of the cyclic ester include β-propiolactone and γ-butyrolactone. Further, the molecular terminal of the acetal resin may be converted into an ether bond, an ester bond, or the like. As the polyacetal resin, one containing oxymethylene units in the main chain of usually 80 mol% or more, more preferably 90 mol% or more is used, and its melt flow rate MFR (190 mol% or more) is used.
°C, 2160g, ASTM D-1238-79) is usually 0.1
to 50g/10min, preferably 0.2 to 30
g/10min range is used. The modified α-olefin polymer (B) blended into the polyacetal resin composition of the present invention is a base α-olefin polymer containing α-olefin component units as a main component.
It is necessary that the unsaturated carboxylic acid or its acid anhydride component unit is graft copolymerized in the range of 0.01 to 10 parts by weight to 100 parts by weight of the olefinic polymer, and more preferably 0.05 to 5 parts by weight. It is preferable to graft copolymerize within a range of about 100%. Here, if the grafting ratio of the unsaturated carboxylic acid or its acid anhydride component unit in the modified α-olefin polymer is less than 0.01 part by weight, the impact strength of the polyacetal resin composition decreases, and furthermore, the layered Peel off. Furthermore, if the grafting ratio is greater than 10 parts by weight, the degree of crosslinking of the graft-modified product will increase, so that even if it is blended into the polyacetal resin, the effect of improving the impact resistance of the composition will decrease. The modified α-olefin polymer usually has a crystallinity of 1 to 85%,
Preferably in the range of 2 to 80%, of which 135
The intrinsic viscosity [η] of decalin at °C is usually 0.5
from 7 dl/g, preferably from 0.7 to 5 dl/g
is within the range of Examples of the unsaturated carboxylic acid or acid anhydride unit of the graft monomer component constituting the modified α-olefin polymer include acrylic acid, methacrylic acid, α-ethyl acrylic acid, maleic acid, fumaric acid, and itaconic acid. , citraconic acid, tetrahydrophthalic acid, endocys-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (nadic acid), methyl-endocys-
Bicyclo[2.2.1]hept-5-ene-2,3-
Unsaturated carboxylic acids such as dicarboxylic acid (methylnadic acid), acid anhydrides of the unsaturated carboxylic acids,
Specifically, maleic anhydride, citraconic anhydride,
Examples include itaconic anhydride, tetrahydrophthalic anhydride, nadic anhydride, and methyl nadic anhydride. Among these, unsaturated dicarboxylic acids or their acid anhydrides are preferred, and maleic acid, nadic acid, and their acid anhydrides are particularly preferred. Conventionally known methods have been employed to graft copolymerize the graft monomer selected from the unsaturated carboxylic acid or its acid anhydride to the α-olefin polymer to produce the modified α-olefin polymer. Ru. For example, there is a method in which the α-olefin polymer is melted and a graft monomer is added to carry out graft copolymerization, or a method in which the α-olefin polymer is dissolved in a solvent and a graft monomer is added to carry out graft copolymerization. In any case, in order to efficiently graft copolymerize the graft monomer,
Preferably, the reaction is carried out in the presence of a radical initiator. The grafting reaction is usually carried out at a temperature of 60 to 350°C. The usage ratio of radical initiator is
The amount is usually in the range of 0.01 to 20 parts by weight per 100 parts by weight of the α-olefin polymer. Examples of the radical initiator include organic peroxides, organic peresters, and azo compounds. α-Constituting the modified α-olefin polymer
Olefin polymers are amorphous or low crystalline polymers whose main component is α-olefin component units;
It may be any crystalline polymer whose main component is an α-olefin component unit. When the base α-olefin polymer is an amorphous or low-crystalline α-olefin elastomeric polymer, the α-olefin elastomer is a non-crystalline polymer mainly composed of α-olefin component units. It is a crystalline or low-crystalline elastic polymer, and may be composed only of two or more α-olefin component units, or may contain a small amount of diene component units in addition to the α-olefin component. I can't help it. The content of α-olefin component units constituting the base α-olefin elastic polymer is usually 80 mol% or more, preferably 80 mol% or more, and the content of the diene component is usually 0 to 20 mol%. %, preferably 0 to 15 mol%
is within the range of Other physical properties of the base α-olefin elastomer are that the degree of crystallinity is usually 20% or less, preferably in the range of 19 to 1%, and the intrinsic viscosity [η] in decalin at 135°C is usually 0.5 to 7.
dl/g, preferably in the range of 0.7 to 5 dl/g, and the glass transition temperature is usually below 0°C, preferably below -10°C. Here, the constituent α-olefin unit includes ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, etc. Examples of diene component units include non-conjugated diene components such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, and 2,5-norbonadiene, and conjugated diene components such as butadiene, isoprene, and piperylene. Examples include diene components. Examples of the base α-olefin elastomer include ethylene/propylene copolymer, ethylene/1-butene copolymer, and ethylene/propylene copolymer.
4-methyl-1-pentene copolymer, ethylene/
1-hexene copolymer, ethylene/1-octene copolymer, ethylene/1-decene copolymer, propylene/ethylene copolymer, propylene/1-butene copolymer, propylene/4-methyl-1-pentene Copolymers, α-olefin elastic copolymers such as propylene/1-octene copolymers, propylene/1-decene copolymers, propylene/1-dodecene copolymers, ethylene/propylene/1,4
-Hexadiene copolymer, ethylene/propylene/dicyclopentadiene copolymer, ethylene/propylene/dicyclopentadiene copolymer,
Propylene/5-ethylidene-2-norbornene copolymer, ethylene/propylene/2,5-norbonadiene copolymer, ethylene/1-butene/dicyclopentadiene copolymer, ethylene/1-butene/1,4-hexadiene Copolymers, α-olefin/non-conjugated diene elastic copolymers such as ethylene/1-butene/5-ethylidene-2-norbornene copolymers can be exemplified. A modified α-olefin elastic polymer is obtained by reacting the base α-olefin elastic polymer with the unsaturated carboxylic acid or its acid anhydride by the method described above. The physical properties of the modified α-olefin elastomer are as follows:
Its crystallinity is usually 20% or less, preferably in the range of 1 to 19%, and its intrinsic viscosity [η] in decalin at 135°C is usually in the range of 0.5 to 7 dl/g, preferably 0.7 to 5 dl/g. , whose molecular weight distribution (w/n) is usually 1.5 to 30,
It is preferably in the range of 2.0 to 25, and the glass transition temperature is usually 0°C or lower, preferably -10°C or lower. When the base α-olefin polymer constituting the modified α-olefin polymer is a crystalline α-olefin polymer, the α-olefin polymer has α-olefin component units as a main component. It is a crystalline polymer with one or more α
It may be composed only of -olefin component units, or may contain a small amount of polar vinyl monomer component units in addition to the α-olefin component units. The content of α-olefin component units constituting the base crystalline α-olefin polymer is usually 60 mol% or more, preferably in the range of 70 to 99 mol%, and when it contains polar vinyl monomer component units, The content thereof is usually in the range of 0 to 40 mol%, preferably 0 to 30 mol%.
The physical properties of the base crystalline α-olefin polymer are as follows:
Crystallinity is usually 30% or more, preferably 80 to 35
%, and the intrinsic viscosity [η] in decalin at 135°C is usually 0.5 to 7 dl/g, preferably
It ranges from 0.7 to 5 dl/g, and the melting point is usually 60
The temperature range is from 80 to 300°C, preferably from 80 to 280°C. Here, the constituent α-olefin component units include ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene,
1-hexene, 1-octene, 1-decene, 1-
Examples include dodecene, and examples of the polar vinyl monomer component unit include vinyl acetate,
Examples include acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, various metal salts of acrylic acid, and various metal salts of methacrylic acid. Examples of the base crystalline α-olefin polymer include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene/ 1-pentene copolymer, ethylene/4-methyl-1-pentene copolymer, ethylene/1-octene copolymer,
Ethylene/1-decene copolymer, ethylene/1-
Examples include dodecene copolymer, ethylene/vinyl acetate copolymer, ethylene/methyl (meth)acrylate copolymer, ethylene/(meth)acrylic acid copolymer, ethylene/(meth)acrylate copolymer, etc. can do. A modified crystalline α-olefin polymer is obtained by reacting the base crystalline α-olefin polymer with the unsaturated carboxylic acid or its acid anhydride by the method described above. The physical properties of the modified crystalline α-olefin elastomer are such that its crystallinity is in the range of 85 to 30%, preferably in the range of 80 to 35%, and its intrinsic viscosity [η] in decalin at 135°C is normally It is in the range of 0.5 to 7 dl/g, preferably 0.7 to 5 dl/g, and its molecular weight distribution (w/n) is usually
1.5 to 30, preferably 2.0 to 25, and its melting point is usually 60 to 300°C, preferably
It is in the range of 80 to 280℃. In the polyacetal resin composition of the present invention, the blending ratio of the modified α-olefin polymer (B) to 100 parts by weight of the polyacetal resin (A) must be in the range of 1 to 200 parts by weight. Yes, more preferably 5 to 100 parts by weight,
Particularly preferred is a range of 10 to 80 parts by weight. If the proportion of the modified α-olefin polymer (B) exceeds 200 parts by weight, the rigidity and bending strength of the polyacetal resin composition will decrease, and if it falls below 1 part by weight, the durability of the composition will decrease. Impact resistance will decrease. In addition to the above-mentioned essential components of the polyacetal resin (A) and modified α-olefin polymer (B), the polyacetal resin of the present invention contains an unmodified α-olefin polymer as a resin component. You can also do that. As the α-olefin polymer, use an amorphous or low crystalline α-olefin elastic polymer or a crystalline α-olefin polymer as exemplified as the base resin for the modified α-olefin polymer. can do. As the α-olefin polymer, an α-olefin polymer of the same type as the base α-olefin polymer of the modified α-olefin polymer or a different type of α-olefin polymer can be blended.
An olefin polymer can also be blended. In this case, the blending ratio of the α-olefin polymer is usually 1 to 1000 parts by weight, preferably 10 to 500 parts by weight, based on 100 parts by weight of the modified α-olefin polymer (B). and the content of unsaturated carboxylic acid or acid anhydride component units in the graft copolymerization component is usually 0.01 to 8% by weight, preferably 0.01 to 8% by weight, based on the total amount of the modified α-olefin polymer and the α-olefin polymer. It ranges from 0.05 to 5% by weight. The polyacetal resin composition of the present invention is prepared by melt-kneading the constituent components by the method described below. The polyacetal resin composition includes a polyacetal matrix made of a polyacetal resin, a modified α-olefin polymer, and in some cases a modified polymer made of the modified α-olefin polymer and the α-olefin polymer. The coalescent matrix is dispersed as fine particles closely adhered to each other. The size of the dispersed fine particles constituting the composition is usually 10μ or less, preferably 5 to 0.1μ, particularly preferably 3 to 0.2μ. In addition to the above-mentioned two essential components, the polyacetal resin composition of the present invention may optionally contain an antioxidant,
UV absorbers, photoprotectants, phosphite stabilizers, peroxide decomposers, basic auxiliaries, nucleating agents, plasticizers, lubricants, antistatic agents, flame retardants, pigments, dyes, carbon black, asbestos It is also possible to incorporate fillers such as glass fiber, potassium titanate whiskers, mica, carrion, talc, silica, and silica alumina. Furthermore, other polymers can be blended into the composition of the present invention within a range that does not impair its physical properties. The blending ratio of these additives is within an appropriate range. The polyacetal resin composition of the present invention can be prepared by melt-mixing using various methods. For example, after premixing a portion of the two essential components,
Methods include mixing with the remaining components or mixing all the essential two components at once. Moreover, the above-mentioned additives, such as antioxidants, can be added at any of these stages as necessary.
It can also be added to the component resins in advance. The polyacetal resin composition of the present invention has excellent properties such as rigidity, impact resistance, heat resistance, and moldability. Among them, when producing the composition, component (B) and some polyacetal resin (A)
A composition obtained by melt-mixing the remaining polyacetal resin (A) component into a premix obtained by preliminary melt-mixing of the components has particularly excellent performance. The melt flowability [melt flow rate (MFR, 190°C, 2160g load)] of the composition of the present invention is usually 0.1
to 50g/10min, preferably 0.2 to 30
The range is g/10min. The polyacetal resin composition of the present invention can be molded into various shapes by various conventionally known melt molding methods. Examples include methods such as injection molding, extrusion molding, compression molding, and foam molding, and are used in a wide range of applications including automobile parts, electrical appliances, and electrical parts. Next, the present invention will be specifically explained using examples. In addition, in the method of the present invention, the degree of crystallinity and the intrinsic viscosity [η] were measured by the following method. Crystallinity: Measured by X-ray diffraction at 23°C. Intrinsic viscosity: Determined using decalin at 135°C. Example 1 Polyacetal resin [Manufactured by Polyplastics Co., Ltd., Jyuracon M25-01, MFR2.76g/10min]
and ethylene-butene-1 copolymer [ethylene content
90 mol%, [η] 1.75 dl/g, density 0.88 g/cm ³ ,
Crystallinity 17%] 0.9 maleic anhydride per 100 parts by weight
Weight part Graft copolymerized maleic anhydride graft modified ethylene-butene-1 copolymer [[η]
1.48 dl/g, density 0.88 g/cm ³ , crystallinity 16%] were mixed using a blender in the proportions shown in Table 1 to prepare a dry blend product. This dry blend composition was supplied to a L/D=28, 25 mmφ single screw extruder,
The mixture was kneaded and granulated by passing once at 190°C and 50 rpm. After drying the granulated pellets at 80°C for 24 hours, physical property test pieces were prepared using a Toshiba IS-50 injection molding machine.
Subsequently, physical properties were evaluated by the following method. MFR: 190℃ according to ASTM D-1238-79,
Measured at 2160g. Bending test: Using a 3.2mm thick test piece, ASTM
Flexural modulus FM (Kg/cm ² ) according to D-790-80,
The bending strength FS (Kg/cm ² ) was measured. Izotsu impact strength: using a 3.2mm thick test piece,
The notched isot impact strength (Kg·cm/cm) at 23°C was measured according to ASTM D-256. Layer peelability: Injection test piece (123mm x 12.7mm x 3.2
mm) and visually judge the layer peelability.
Those in which delamination did not occur were rated ○, and those in which delamination occurred were rated ×. The results are shown in Table 1. Examples 2 to 8, Comparative Examples 3 and 4 Blends were prepared in the same manner as in Example 1, except that the modified α-olefin polymers shown in Table 1 were used in the proportions shown in Table 1, and the physical properties were measured. did. The results are shown in Table 1. Example 9 A blend was prepared in the same manner as in Example 1, except that the two types of modified α-olefin polymers shown in Table 1 were used in the proportions shown in Table 1, and the physical properties were measured. The results are shown in Table 1. Examples 10 to 12 Blends were prepared in the same manner as in Example 1, except that the modified α-olefin polymer shown in Table 1 and the unmodified α-olefin polymer shown in Table 1 were used in the proportions shown in Table 1, and the physical properties were determined. was measured. The results are shown in Table 1. Example 13 A blend was prepared in the same manner as in Example 1, except that polyacetal resin [manufactured by DuPont, Delrin 100, MFR 2.29 g/10 min] was used at the ratio shown in Table 1, and the physical properties were measured. The results are shown in Table 1. Comparative Examples 1 and 2 The physical properties of the polyacetal resin alone were evaluated and shown in Table 1. Comparative Examples 5 to 11 Blends were prepared in the same manner as in Example 1, except that the unmodified or modified α-olefin polymers shown in Table 1 were used in the proportions shown in Table 1, and their physical properties were measured. The results are shown in Table 1.

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Claims (1)

[Scope of Claims] 1. A composition comprising a polyacetal resin (A) and a modified α-olefin polymer (B), [] a modified α-olefin polymer in the composition;
(B) is in the range of 1 to 200 parts by weight per 100 parts by weight of the polyacetal resin (A); [] the modified α-olefin polymer (B) is α-
Modified by graft copolymerizing 0.01 to 10 parts by weight of unsaturated carboxylic acid or its acid anhydride component units to 100 parts by weight of a base α-olefin polymer containing olefin component units as a main component. A polyacetal resin composition characterized by being an α-olefin polymer.