JPH02294352A - Polyoxymethylene composition with high weatherability - Google Patents

Abstract

PURPOSE:To provide the title composition comprising polyoxymethylene, a methacrylic ester polymer and fine granules of a resin highly compatible with said methacrylic ester polymer. CONSTITUTION:The objective composition comprising (A) 100 pts.wt. of polyoxymethylene, (B) 5-100 (pref. 10-50) pts.wt. of a methacrylic ester polymer, pref. a (co)polymer having >=80wt.% of methyl methacrylate unit, and (C) 5-100 pts.wt. of a crosslinked polymer highly compatible with the component B, in the form of fine granules consisting of a polymer with the outermost part consisting of e.g. polymer of (meth)acrylic acid, pref. multi-phase crosslinked polymer granules, esp. having internally a flexible polymer with its glass transition temperature <25 deg.C, esp. <0 deg.C, 0.01-2mum in the granular size in the final composition, with the component A dispersed in both the components B and C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel polyoxymethylene composition having excellent weather resistance and a molded article thereof.

More specifically, the present invention provides a polyoxymethylene composition that retains the good mechanical properties, abrasion characteristics, fatigue properties, moldability, etc. inherent to polyoxymethylene, and also has excellent weather resistance. This article relates to a colored molded product that can be used as an exterior component without any plating or painting treatment on the surface of the molded product. (Prior art) Polyoxymethylene has traditionally been widely used in the electronics/electrical field, automobile field, precision machinery field, etc. because of its high mechanical properties and excellent friction and wear characteristics, fatigue characteristics, and moldability. It is used. However, this polyoxymethylene does not necessarily have sufficient weather resistance; for example, when a polyoxymethylene molded product is exposed to sunlight for a long time, the polyoxymethylene on its surface is molecularly cut by light energy, causing whitening and cracking. This causes various problems when used for exterior parts, etc., as it has the disadvantage that the appearance is significantly impaired and, in severe cases, the mechanical strength is also reduced. In order to improve this point, a method has already been considered in which a thermoplastic resin other than polyoxymethylene with excellent weather resistance is composited with polyoxymethylene. For example, British Patent No. 1.026,017 states that a composition obtained by adding acrylic resin, methacrylic resin, and carbon black to polyoxymethylene has improved hardness, gloss, etc. is disclosed.

In addition, focusing on the fact that polyoxymethylene and polymethacrylic acid ester lack compatibility, attempts have been made to blend the two to obtain a molded product with pearlescent luster.
Japanese Patent Publication No. 51-39746, Japanese Patent Publication No. 49-4595
No. 8), such blends have not been found to be effective in improving weather resistance. As a means to improve the weather resistance of polyoxymethylene,
Japanese Patent Application No. 63-173772 discusses a method of adding polymethacrylic acid ester, a coloring component, preferably a carbon blank, and furthermore an ultraviolet absorber and a light stabilizer to polyoxymethylene. The composition obtained here has the high weather resistance inherent to polymethacrylic acid ester, and is an extremely excellent composition for practical use. However, in the compositions and molded bodies obtained by these methods, the dispersion state of polymethacrylic acid ester in the polyoxymethylene matrix is not stable, so in molded bodies with complex structures, The state of dispersion of the polymethacrylic acid ester varies depending on the location of the molded product, that is, the state of dispersion cannot be maintained uniformly throughout the molded product. As a result, the weather resistance of the molded body with this complex structure also becomes uneven. For example, the weld part in the molded body, the resin overpressure area near the gate part during injection molding, etc. The deterioration of weather resistance is accelerated slightly compared to the parts, resulting in whitening and cracking, resulting in what is called a partial whitening phenomenon. Therefore, molded bodies with complex structures obtained by these methods may have non-uniform weather resistance, which may pose a practical problem. (Problem B to be solved by the invention) The present invention solves the problem of mechanical properties originally possessed by polyoxymethylene,
A composition having excellent weather resistance without impairing properties such as friction and wear properties, fatigue properties, and moldability, and
? 3 [Even if the molded product has a rough structure, it has excellent weather resistance uniformly over the entire molded product, and furthermore, it can be used as is for exterior parts, etc., without plating or painting the surface. The purpose of this invention is to provide a colored polyoxymethylene molded article that has high weather resistance. (Means for Solving the Problems) The present inventors have developed a polyoxymethylene composition that retains the original properties of polyoxymethylene and has excellent weather resistance, and a polyoxymethylene composition that can be used without providing a protective layer on its surface. Polyoxymethylene was developed as a result of intensive research to develop a polyoxymethylene composition, especially a molded product, that has uniform and high weather resistance and can be used as is for exterior parts. and a methacrylic ester polymer in a predetermined ratio, and to this mixture are added microparticles that are a resin that is highly compatible with the methacrylic ester polymer, and if desired, coloring components and ultraviolet absorbing components are added. By using a composition containing a light stabilizer and a light stabilizer, the above object is achieved and the scales are found,
Based on this knowledge, we have completed the present invention.

That is, the present invention includes: (1) Too many parts by weight of polyoxymethylene (A), 5 to 100 parts by weight of methacrylic acid ester polymer (B), and microparticles (C) which are resins that are highly compatible with (B). 5-1
00 parts by weight, in which (B) and (C
) A polyoxymethylene composition characterized in that polyoxymethylene is dispersed in the component. Further, in the present invention, the microparticles (C) are crosslinked polymer particles having a crosslinked structure inside, and the particle size in the present composition is 0. It is also a composition with a diameter between 2.0 and 2.0 μm. Note that the present invention is implemented in accordance with the following implementation method 1! #! It also includes. (1) The composition according to claim 1, wherein the methacrylic acid ester polymer (B) is a homopolymer of an alkyl ester of methacrylic acid having 1 to 6 carbon atoms.

(2) The homopolymer of an alkyl ester having 1 to 6 carbon atoms of methacrylic acid is polymethyl methacrylate (1)
).

(3) The methacrylic acid ester polymer (B) is a random copolymer of methyl methacrylate and an alkyl ester of methacrylic acid having 2 to 6 carbon atoms or a random copolymer of methyl methacrylate and an acrylic ester. A composition according to claim (1). (4) The methacrylic acid ester polymer (B) is a block copolymer of methyl methacrylate and an alkyl ester of methacrylic acid having 2 to 6 carbon atoms or a block copolymer of methyl methacrylate and an acrylic ester. A composition according to claim (1). (5)
The methacrylic acid ester polymer (B) is a graft copolymer obtained by graft-polymerizing polymethyl methacrylate with an alkyl ester having 2 to 6 carbon atoms or an acrylic ester of methacrylic acid. Composition of. (6) The composition according to claim (1), wherein the microparticles (C) are a thermoplastic resin. (7) The composition according to claim (1), further comprising 0.5 to 8 parts by weight of a coloring component based on 100 parts by weight of polyoxymethylene. (8) The composition according to item (7) above, wherein the coloring component is carbon plaque. (9) The above-mentioned (
Composition described in section 7). The present invention will be explained in detail below. Polyoxymethylene (A
), both oxymethylene homopolymers and oxymethylene copolymers can be used. The oxymethylene homopolymer is generally a polyacetal obtained by polymerizing formaldehyde, for example. On the other hand, an oxymethylene copolymer has, for example, an oxymethylene unit represented by the general formula →CH30+-r- (I) (n in the formula is an integer of 1 or more) and a general formula R1-E- (C). 0-}-- ... (■)R
(R1 and Rt in the formula are each a hydrogen atom, an alkyl group, an allyl group, or an aryl group, and they may be the same or different from each other, and m is 2 to
It is a copolymer with a structure in which oxyalkylene units represented by (an integer of 6) are randomly bonded. The proportion of this oxyalkylene unit is preferably 0.05 to 50 mol, more preferably 0.05 to 50 mol, per 100 mol of oxymethylene units. The amount ranges from 1 to 20 moles.
Examples of the oxyalkylene unit include oxyethylene unit, oxypropylene unit, oxytetramethylene level, and oxyphenylene unit. Among these oxyalkylene units, from the viewpoint of improving the physical properties of the oxymethylene copolymer, oxyethylene units→(CH,)i0← and oxytetramethylene units 1+
(cH.) 40← is particularly preferred, and this oxymethylene copolymer can be obtained by copolymerizing or reacting formaldehyde, trioxane, or oxymethylene homopolymer with a cyclic ether or cyclic formal. The oxymethylene copolymer obtained here is desirably subjected to stabilization treatment at the molecular ends. As the stabilization treatment method, a method is usually used in which -OH at the polymer terminal is esterified or hydrolyzed until relatively stable carbon-carbon bonds are present at each terminal.

The number average molecular weight of this polyoxymethylene is 2o,oo
o to 75,000, particularly preferably from 20,000 to 65,000. Moreover, one type of polyoxymethylene may be used, or two or more types may be used in combination.

As the methacrylic ester polymer (B) used in the composition of the present invention, both homopolymers and copolymers of methacrylic esters can be used.
As the homopolymer of methacrylic acid ester, a homopolymer of an alkyl ester of methacrylic acid having 1 to 6 carbon atoms, particularly polymethyl methacrylate, is suitable. On the other hand, as a copolymer of methacrylic acid ester, two selected from alkyl esters having 1 to 6 carbon atoms of methacrylic acid are used.
Those formed by copolymerizing two or more species, those formed by copolymerizing an alkyl ester of methacrylic acid having 1 to 6 carbon atoms and an acrylic acid ester, preferably an alkyl ester of acrylic acid having 1 to 6 carbon atoms, especially Copolymer of methyl methacrylate and alkyl ester of methacrylic acid having 2 to 6 carbon atoms and methyl methacrylate and acrylic acid having 1 to 6 carbon atoms
A copolymer with an alkyl ester of is preferred. These copolymers may be random copolymers or block copolymers, or may be added to a random copolymer by adding one component of the random copolymer as a polymer block. A random block copolymer can also be used.

Furthermore, an alkyl ester having 1 to 6 carbon atoms of methacrylic acid or an acrylic acid ester, preferably an acrylic acid having 1 to 6 carbon atoms, is added to the homopolymer or the random or block copolymer of an alkyl ester having 1 to 6 carbon atoms of methacrylic acid. Graft polymers of 1 to 6 alkyl esters, especially polymethyl methacrylate, random or block copolymers of methyl methacrylate and methacrylic acid alkyl esters having 2 to 6 carbon atoms, or methyl methacrylate and acrylic acid carbons. A graft copolymer in which an alkyl ester of methacrylic acid having 2 to 6 carbon atoms or an alkyl ester of acrylic acid having 1 to 6 carbon atoms is graft-polymerized to the main chain of a random or block copolymer with an alkyl ester having a number of 1 to 6. Polymers can also be preferably used. These copolymers are obtained by copolymerizing two or more types selected from alkyl esters of methacrylic acid having 1 to 6 carbon atoms with two or more types selected from acrylic esters. Good too. In the present invention, among these copolymers, random copolymers are particularly preferred. Further, when the methacrylic ester polymer (B) is a copolymer containing acrylic ester units, the content of the acrylic ester units is preferably 20% by weight or less, preferably 15% by weight or less. desirable. Particularly preferred copolymers contain 80% by weight or more, especially 85% by weight or more of methyl methacrylate units.

Furthermore, this methacrylic acid ester polymer (B) is
Those having a number average molecular weight in the range of 60,000 to 1.50,000, particularly 60,000 to Boo,000 are preferred. Moreover, the methacrylic acid ester polymer (B)
may be used alone or in combination of two or more.

In the composition of the present invention, polyoxymethylene 100
It is necessary to mix 5 to 100 parts by weight of the methacrylic acid ester polymer (B) based on the weight part. If the amount of the methacrylic acid ester polymer (B) is less than 5 parts by weight, the effect of improving weather resistance will not be sufficiently exhibited;
When the amount exceeds 100 parts by weight, the resulting composition loses the properties inherent to polyoxymethylene. The blending amount of the methacrylic acid ester polymer (B) is preferably 10 to 50 parts by weight. The fine particles (C) that can be used in the present invention have high compatibility with the meccrylic acid ester polymer (B), and the particle shape can be changed while the dispersion state of (C) in the present composition remains fine. There is no particular limitation as long as the resin is retained and dispersed in (B). For example, crosslinked polymer particles that are thermoplastic resins that maintain their particle shape even if the microparticles (C) soften under normal temperature conditions where they are melt-kneaded after being mixed with polyoxymethylene, or under the above-mentioned temperature conditions. High melting point, which does not melt under
particles that are thermoplastic resins with high softening temperatures, or
Examples include thermosetting particles. Preferably, since (B) and (C) exhibit high mutual compatibility, (C) is preferably a thermoplastic resin that at least partially softens under melt-kneading conditions with polyoxymethylene. A typical example of such fine particles (C) is a crosslinked polymer particle having a crosslinked structure inside. Examples of crosslinked polymer particles include single crosslinked polymer particles consisting of only one phase, multiphase crosslinked polymer particles having a multiphase structure of two or more phases, or crosslinked polymer particles thereof. Graft-crosslinked polymer particles in which the combined particles have a graft structure on the outermost part of the particles can be used. Crosslinked polymer particles can be formed by polymerizing the following monomers. Furthermore, each polymer, each phase, graft phase, etc. constituting the crosslinked polymer particles may be a homopolymer made of these monomers, or a copolymer made of two or more types of monomers. Examples of monomers that can be used include aromatic vinyl monomers such as styrene and vinyltoluene; vinyl chloride;
Vinyl halide monomers such as vinylidene chloride; Nitrile monomers such as acrylonitrile and methacrylonitrile; Methacrylic acid esters such as methyl methacrylate, butyl methacrylate, and hydroxyethyl methacrylate; Methyl acrylate, ethyl acrylate, butyl acrylate, Acrylic acid esters such as 2-ethylhexyl acrylate and hydroxyethyl acrylate; Vinyl esters such as vinyl acetate and vinyl propionate; Unsaturated amides such as acrylamide and methacrylamide; Vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, etc. Examples include vinyl alcohol ether. Furthermore, conjugated dienes such as butadiene and isobrene may be added to these vinyl polymerizable monomers for copolymerization, or these conjugated dienes may be quasi-isopolymerized. The crosslinked polymer particles (C) referred to in the present invention can be produced using the following conventional emulsion polymerization technique. As a specific example, a method for producing crosslinked polymer particles consisting of two-phase horizontal structure is disclosed. Add the monomers necessary to form the first phase and the polymerization starter to water containing additives necessary for emulsion polymerization such as emulsifiers, and polymerize while stirring. As the emulsifier, alkyl sulfosuccinates such as dioctyl sodium sulfosuccinate; alkyl aromatic sulfonates such as dodecylbenzene sodium sulfonate can be used. As the polymerization initiator, oxidants such as diisobrobylbenzene hydroperoxide and penzoyl peroxide, and azo compounds such as azobisisobutyronitrile can be used. In order to give the first phase, that is, the central phase, a crosslinked structure, the monomer constituting the first phase and a polyfunctional crosslinking agent are copolymerized. As the polyfunctional crosslinking agent, commonly used crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, and dimethacrylic compounds can be used, with ethyl diacrylate and 101-butyl diacrylate being preferred. The amount of the polyfunctional crosslinking agent added is preferably 0.1 to 5.0% by weight, more preferably 0.1 to 2.5% by weight, based on the total weight of the polymer constituting the first phase. More preferable. Furthermore, it is preferred to use a polyfunctional grafting agent in order to create a chemical bond between the first and second phases. Examples of the polyfunctional grafting agent include polyfunctional monomers having different functional agents, such as allyl esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc., with allyl acrylate and allyl methacrylate being preferred.

The amount of the polyfunctional grafting agent added is 0 based on the total weight of the polymer constituting the first phase, that is, the phase that becomes the graft base.
．． 1 to 5.0% by weight is preferable, particularly 0.1 to 2.5% by weight.
Weight % is more preferable. Once the polymerization reaction for forming the first phase is completed, the heptanomer necessary for forming the second phase is then added. At this time, a polymerization initiator may be added if necessary. When the polymerization to form the second phase is completed, the polymerization of the crosslinked polymer particles is terminated. Emulsion polymerization is usually carried out at 50 to 90°C.
It is carried out at a temperature of The crosslinked polymer particles obtained by the above emulsion polymerization can be water-separated while maintaining the particle form using conventional means such as salting out, freeze-thaw, or spray drying. ．． For salting out, an electrolyte solution such as aluminum chloride or sodium chloride is used to filter out the precipitate. Furthermore, the crosslinked polymer particles referred to in the present invention can be obtained through washing and drying steps.

Regarding the outermost part of the crosslinked polymer particles used in the present invention, the polymer constituting the outermost part is preferably a hard polymer with a high glass transition temperature (hereinafter abbreviated as Tg). If a soft polymer with a low Tg constitutes the outermost layer, this frame I! When the polymer particles are mixed with polyoxymethylene and then melted and kneaded using an extruder, the crosslinked polymer particles cause aggregation with each other, making it impossible to maintain the uniform and finely dispersed state obtained by the present invention. ．． The Tg of the polymer constituting the outermost part of the crosslinked polymer particles is preferably 25°C or higher, more preferably 50°C or higher.
C or higher is more preferable.

The polymer constituting the outermost part of the crosslinked polymer particles is preferably composed of methacrylic ester or acrylic ester. Furthermore, an alkyl ester of carbon 111t1 to 6 of methacrylic acid is preferable, and methyl methacrylate is more preferable. Preferred crosslinked polymer particles are multiphase crosslinked polymer particles, and more preferably have a soft polymer inside. The Tg of the soft polymer is more preferably less than 25°C, and even more preferably less than O''C.Also, even if the outermost part of the multiphase crosslinked polymer particles is composed of a hard polymer with a high Tg, If the proportion of the soft polymer based on the entire phase-crosslinked polymer particles, that is, the thickness of the hard polymer is small, the hard polymer is easily destroyed when melt-kneaded with polyoxymethylene, and the hard polymer Multiphase crosslinked polymer particles tend to agglomerate due to the influence of the soft polymer on the inside of the multiphase crosslinked polymer particles. Therefore, it is preferable that the thickness of the hard polymer constituting the outermost layer of the multiphase crosslinked polymer particles is large. When the phase-crosslinked polymer particles have a soft polymer inside them, there is also a great advantage that the impact resistance of the composition obtained by the present invention is improved. It is preferable that the outermost layer does not contain any acid sites that tend to decompose polyoxymethylene, and it is preferable to remove catalysts such as peroxide used during polymerization and impurities as much as possible.

The smaller the particle size of the microparticles (C) in the present composition, the better;
Preferably 0.01 to 2.0 μm, more preferably 0.01 to 2.0 μm.
05~0. It is better to be between 5 μm. Also, (C
) is preferably as close to a spherical shape as possible. The amount of fine particles (C) added is polyoxymethylene 100
5 to 100 parts by weight is required. If the amount added is less than 5 parts by weight, the dispersion state of the methacrylic acid ester polymer CB) in the present composition will not be improved, and the
If it exceeds 0 parts by weight, the excellent mechanical properties and other properties of polyoxymethylene will be impaired.

In addition, in order for (C) to show high compatibility with (B), (C)
The outermost layer (Table N of the particles) is preferably a polymer composed of methacrylic ester and acrylic ester. In order to obtain high weather resistance with excellent uniformity as referred to in the present invention, the amount of the fine particles (C) is preferably 20 to 500 parts by weight, more preferably 40 to 500 parts by weight, per 100 parts by weight of the methacrylic acid ester polymer (B). More preferably 250 parts by weight. In addition, in order to obtain the good effects referred to in the present invention without impairing the excellent characteristics of polyoxymethylene (A), it is necessary to add the methacrylic acid ester polymer (B) and the fine particles (C) in a combined amount. is preferably 100 parts by weight or less, more preferably 70 parts by weight or less, based on 100 parts by weight of polyoxymethylene (A). When the composition obtained according to the present invention is subjected to injection molding or the like, the microparticles (C) having an originally microscopic particle shape can be easily uniformly and finely dispersed in the polyoxymethylene matrix (A), The methacrylic acid ester polymer (B), which is highly compatible with the uniformly finely dispersed fine particles, is also finely dispersed in a form that is compatible with the fine particles. Therefore, the present composition basically forms a morphology in which (C) is dispersed in the above (B) as referred to in the present invention. However, depending on the part of the molded product obtained by the present invention, the above morphology may be slightly disordered, and the microparticles (
In some cases, C) is dispersed alone in the polyoxymethylene matrix (A), but it is in a very small area compared to the whole, and basically (C) is dispersed in (B). I can say that there is. That is, it is expected that the microparticles (C) function as core particles for finely dispersing the thermoplastic resin (B) other than polyoxymethylene (A), in other words, as a compatibilizer. In the composition of the present invention, it is preferable to include a coloring component. By blending this coloring component, a colored molded article that does not require a plating layer or a paint layer can be obtained. A dye or a pigment is used as the coloring component. There are no particular restrictions on the types of dyes and pigments used.
Any one can be selected from those conventionally used in polyoxymethylene compositions. As the dye, for example, an anthraquinone-based dye is preferable, and as a pigment, carbon black, azo-based, phthalocyanine-based, perylene-based, quinacridone-based, anthraquinone-based, indoline-based, titanium-based, iron oxide-based, cobalt-based, etc. are preferable. ．． These coloring components may be used alone or in combination of two or more, but pigments or a combination of pigments and dyes are particularly preferred. Black is generally the most commonly used color, but in this case, adding carbon black as a coloring component has the advantage of further improving the weather resistance of the molded product. As the carbon black, carbon black is commonly used for coloring plastics, such as Micronex (Ml
cronex), Vulcan (Vu1 can)
, Phiblack, Sterling (
Sterling), Carbolac
), Monarch, Cosming (Ku
smink), Ukcarb, Cosmos (
Kosmos), Shawainigan (Shawa ini)
gan), P33, Seval, Regal (
Rega I), acetylene black (Acetyle
ne black), Ketjen black, etc. can be used. In the composition of the present invention, the amount of this coloring component blended is preferably in the range of 0.5 to 8 parts by weight per 100 parts by weight of polyoxymethylene. If the amount is less than 0.5 parts by weight, the coloring effect will not be sufficiently exhibited, and there is no need to add more than 8 parts by weight.
Rather, it deteriorates the physical properties and thermal stability of the composition. Furthermore, the amount of the coloring component added is preferably 0.5 to 4 parts by weight. In the composition of the present invention, in order to further improve weather resistance,
At least one selected from ultraviolet absorbers and light stabilizers
It is preferable to include additional ingredients such as seeds. As this ultraviolet absorber, benzo. Triazole series, penzophenone series, aromatic penzoate series, cyanoacrylate series,
Oxalic acid anilide and the like are used.

Examples of such ultraviolet absorbers include 2-(2゜hydroxy-5゛-methyl-phenyl)penzotriazole, 2-(2''-hydroxy-3゛25゜-di-t-butylphenyl)penzotriazole, 2 -(2'-hydroxy-3'5'-diisoamylphenyl)penzotriazole, 2-[2"-hydroxy-3',5'bis-(α,α-dimethylbenzyl)phenyl]henzotriazole, 2- (2'-hydroxy-4"-octoxyphenyl)penzotriazole, 2-4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy -4-dodecyloxybenzophenone, 22'-dihydroxy-4-methoxybenzophenone, 2.2'-dihydroxy-4.4'' dimethoxybenzophenone, 2-hydroxy-4methoxy-5-sulfobenzophenone, 2-Hydroxy-4-oxybenzylbenzophenone, p-t-butylphenyl salicylate, p-octylphenyl salicylate, 2
-Ethylhexyl 2-cyano 3.3-diphenylacrylate, ethyl-2-cyano 3.3'-diphenylacrylate, N-(2-ethylphenyl)N'-(
Examples include 2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N-(2-ethylphenyl)-N'-(2-ethoxyphenyl) oxalic acid diamide, and the like. Among these ultraviolet absorbers, penzotriazole type is particularly preferred. The amount of these ultraviolet absorbers added is usually selected in the range of 0.1 to 2 parts by weight, preferably 0.15 to 1.8 parts by weight, per 100 parts by weight of polyoxymethylene.

As the light stabilizer, hindered amine light stabilizers are preferred, such as 4-acetoxy-22,6.6-tetramethylpiperidine, 4-stearoyloxy-2.
2,6.6-tetramethylbiperidine, 4-acryloyloxy-2.2,6.6-tetramethylbiperidine,
4-Methoxy-2.2.6.6-tetramethylpiperidine, 4-benzoyloxy-2.2,6.6-tetramethylpiperidine, 4-cyclohexyloxy-2.2,6
．． 6-tetramethylpiveridine, 4-phenoxy-22
6.6-tetramethylbiperidine, 4-penzyloxy-2.2,6.6-tetramethylpiperidine, 4-(phenylylbamoyloxy)-2.2,6.6-tetramethylbiperidine, bis( 2,2.6.6-tetramethyl-4-piveridyl)oxalate, bis(2.2,6,
6-tetramethyl-4-biperidyl)malonate, bis(2,2,6.6-tetramethyl-4-biperidyl)adibate, bis(2.2.6.6-tetramethyl-4-
piperidyl) sebacate, bis(1,2.2,6.6-
Pentamethyl-biveridyl) sebacate, bis(2,2
, 6.6-tetramethyl-4-piveridyl) terephthalate, 1,2-bis(2.2,6.6-tetramethyl-
4-biperidyloxy)ethane, bis(2.2,6.6
(1-tetramethyl-4-piveridyl)hexamethylene-l
6-dicarbamate, bis(1-methyl-2,2,6
．． 6-tetramethyl-4-biveridyl)adipate, tris(2,2.66-tetramethyl-4-piperidyl)
Examples include benzene=1.3.5-tricarboxylate. The amount of these light stabilizers added is usually O. 1-2 parts by weight, preferably 0.15-1. Selected within the range of 8 parts by weight. These additive components may be used alone or in combination of two or more, but it is particularly preferable to use a UV absorber and a hindered amine stabilizer in combination, as this further improves dust resistance. In this case, the amount ratio is 20 to 20 parts by weight of the light stabilizer per 100 parts by weight of the ultraviolet absorber.
It is preferable to use it in a proportion of 0 parts by weight. The composition of the present invention may contain known additives, such as heat stabilizers, in order to impart necessary properties depending on its use and purpose.
A lubricant, a nucleating agent, a mold release agent, an antistatic agent, a surfactant, an inorganic filler, etc. may be added to the extent that they do not fulfill the purpose of the present invention. The composition of the present invention is prepared by mixing each component in advance or supplying the components separately and then melt-kneading them using a kneader, such as a single-screw or twin-screw extruder, a Banbury mixer, or a roll. be able to. As a method of pre-mixing, for example, a method of mixing using a mixer such as a Henschel mixer or a cone blender is usually used. The molded article of the present invention can be produced by using the composition prepared as described above and using a conventional molding method such as injection molding, extrusion molding, blow molding, etc. Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples. The physical properties of the molded product were measured using the following methods. ■Weather resistance: (i) Time until crack occurrence: Ultraviolet irradiation tester (manufactured by Iwasaki Electric Co., Ltd., Eye Super UV Tester SUV-F Type I, UV irradiation intensity: l O
Using ultraviolet rays (O mW/cd) in an atmosphere of 83° C., the time until crack generation was determined.

The time when cracks were clearly visible to the naked eye was defined as the time of crack occurrence. Furthermore, the test piece used for the evaluation was a test piece for evaluating bending properties in accordance with ASTM-D790. (ii) Evaluation of uniformity of weather resistance: The above ultraviolet irradiation tester was used.

The evaluation test pieces were as follows: (a) A test piece conforming to ASTM-D-7 90, which had a double gate shape and had a weld line in the center of the test piece, was used. In addition, the properties of the polyoxymethylene used and the meanings of the abbreviations of the methacrylic acid ester polymers in the table are shown below. (a) Polyoxymethylene copolymer A trioxane 9
Random copolymer of 5 mol% and 5 mol% ethylene oxide, melt index (Ml): 9.3 g/1
0 minutes. (mouth) Polyoxymethylene copolymer B trioxane 9
Random copolymer of 5 mol % and 5 mol % ethylene oxide, MI: 2.6 g/10 min. (c) Polyoxymethylene homopolymer MI: 1B. 7
g/10 minutes, XI: Random copolymer of methyl methacrylate and methyl acrylate, 3.5% by weight of methyl acrylate units. X2: Random copolymer of methyl methacrylate and butyl methacrylate, 4% by weight of butyl methacrylate units. ×3 = Graft copolymer obtained by grafting butyl methacrylate onto polymethyl methacrylate, graft component 3.
5 overlapping%. x4: Graft copolymer obtained by grafting butyl methacrylate to a random copolymer of methyl methacrylate and methyl acrylate, 3.5% by weight of methyl acrylate units, 3% by weight of graft component. xS: Block copolymer of methyl methacrylate and butyl methacrylate, butyl methacrylate unit 4.8% by weight. Xh: Copolymer obtained by blank polymerizing butyl methacrylate to a random copolymer of methyl methacrylate and methyl acrylate, methyl acrylate unit 3.8% by weight,
Butyl methacrylate units 4.4% by weight. In addition, the Ml value of polyoxymethylene is ASTM-D-
According to 1238-57T, 190'C, 2.16kg
This is the measured value under load. Example 1 (Production of crosslinked polymer particles (Y+)) Crosslinked polymer particles containing methyl methacrylate as a main component are produced using emulsion polymerization technology. 10 with stirrer and condenser! Add 5.7 liters of distilled water, 20 g of dioctyl sodium sulfosuccinate as an emulsifier, and 1.2 g of Rongalit as a reducing agent to a beaker and dissolve uniformly.
Next, 220 g of methyl methacrylate, 3.0 g of n-butyl acrylate. A homogeneous solution of Og, 2.0 g of diethylene glycol diacrylate, and 0.2 g of diisopropylene hydroperoxide was added, and polymerization was carried out at 80°C. Approximately 1
The reaction was completed in 5 minutes. The Tg of the obtained polymer was 108°C.

Next, the temperature was raised to 95°C and held for 1 hour. The resulting emulsifier was poured into a 0.5% aluminum chloride aqueous solution to coagulate the polymer. After washing with warm water five times, it was dried to form a white floc. A molding material was obtained.

These floc-like crosslinked polymer particles are referred to as Y1 and are used as microparticles in the present invention.

Next, 0.4 kg of polymethacrylic acid ester (X,) was added to 1 kg of polyoxymethylene (A), and crosslinked polymer particles (Y) were added to 1 kg of polyoxymethylene (A).
+) 0.2 kg was blended. Note that powdered polyoxymethylene, polymethacrylic acid ester, and crosslinked polymer particles were used.

Further, 30 g of acetylene blank as a coloring component, 5 g of Tinuvin 234 manufactured by Ciba Geigy as a UV absorber, and 2.5 g of Sanol LS-770 manufactured by Sankyo Co., Ltd. as a light stabilizer were added to this mixture, and mixed using a Henschel mixer. After thorough mixing, the mixtures were melt-kneaded using a twin-screw extruder with a diameter of 30 mφ at a cylinder temperature of 200° C. to obtain a pellet-like polyoxymethylene composition. After thoroughly drying the pellets, they were injection molded at a cylinder temperature of 200°C to obtain test pieces and molded bodies for evaluation, and their weather resistance was evaluated. The results are shown in Table-1.

Each test piece showed no cracks even after the weathering test, and had uniformly excellent weathering resistance with no partial whitening phenomenon. The particle size of the crosslinked polymer particles (Y1) in this composition was 0.09 to 0.13 μm when observed using an electron microscope. Comparative Example 1 A polyoxymethylene composition was obtained in the same manner as in Example 1, except that the crosslinked polymer particles (Y.) were not blended with the polyoxymethylene (A). In the same manner, test pieces were prepared from this composition and their weather resistance was evaluated. The results are shown in Table 4. The weld test piece showed localized whitening along the weld line, a phenomenon referred to in the present invention as partial whitening, and did not exhibit good weather resistance with excellent uniformity. Examples 2 to 9 In Example 1, polymethacrylic acid ester (x1)
A polyoxymethylene composition was obtained in the same manner as in Example 1, except that the blending amounts of crosslinked polymer particles (Yl) and crosslinked polymer particles (Yl) were changed. Similarly, each test piece was prepared from this composition,
Weather resistance was evaluated. The results are shown in Table 1. In all compositions, good weather resistance with excellent uniformity as defined in the present invention was obtained. Examples 10-17 A polyoxymethylene composition was obtained in the same manner as in Example 1, except that the types of polyoxymethylene and polymethacrylic ester were changed. In the same manner, test pieces were prepared from this composition and their weather resistance was evaluated.
The results are shown in Table 2. In all compositions, good weather resistance with excellent uniformity as defined in the present invention was obtained. Example 18 19 [Production of multiphase crosslinked polymer particles (Y,) consisting of three-phase horizontal structure] 10! equipped with a stirrer and a condenser! Add 5.72 g of distilled water, 20 g of dioctyl sodium sulfosuccinate as an emulsifier, and 1.2 g of Rongalit as a reducing agent to a beaker and dissolve uniformly. The first phase consists of 220 g of methyl methacrylate (hereinafter abbreviated as MMA), 3.0 g of n-butyl acrylate (hereinafter abbreviated as BA), 0.8 g of allyl methacrylate (hereinafter abbreviated as ALMA), and diisopropylbenzene hydroperoxide. (hereinafter abbreviated as PBP) 0.2 g of a homogeneous solution was added and polymerized at 80'C. The reaction was completed in about 15 minutes. The Tg of the obtained polymer was 108°C. Next, as a second phase, 1270 g of BA, 320 g of styrene (hereinafter abbreviated as "st"), 20 g of diethylene glycol diacrylate, 3.0 g of ALMAl, and 1.6 g of PBP were added dropwise over a period of 1 hour at a uniform temperature. After completion of dripping, 40
The reaction was completed in minutes.

The Tg of the polymer obtained by polymerizing this product alone is -3
It was 8℃. Next, as a third phase, to MMA6 80 g, BA4.
A homogeneous solution of Og, 0.6 g of PBP, and 0.2 g of N-octylmerbutane (hereinafter abbreviated as OM) was added. The molecular weight of the polymer obtained by polymerizing this product alone is 1,220
,000, Tg was 109°C. The reaction at this stage was completed in about 15 minutes. The temperature was then raised to 95°C and 1
I kept the time. The obtained emulsifier was poured into a 0.5% aluminum chloride aqueous solution to coagulate the polymer, washed five times with warm water, and dried to obtain a white floc-like molding material. These multiphase crosslinked polymer particles were prepared by Y. Suppose that Weather resistance was evaluated in the same manner as in Example 1, except that (Y*) was used instead of the crosslinked polymer particles (Y.) in Example 1. The results are shown in Table 2. As in Example 1, this composition had uniformly excellent and high weather resistance. Furthermore, the impact resistance (Izod value) of this composition is as shown in Example 1.
This was a significant improvement over the composition obtained in . Further, the particle size of the crosslinked polymer particles (yz) in this composition is 0.11
It was ~0.21 μm.

Example 20.21 In Example 1, acetylene black, Tinuvin 23
4. Test pieces were prepared from this composition in the same manner as in Example 1, except that Sanol LS-7 70 was not added, and weather resistance was evaluated. The results are shown in Table-2.

All test pieces had uniform weather resistance over the entire test piece, although the crack initiation time was shorter than in Example 1. Comparative Example 2 0.5 parts by weight of Tinuvin 234 and 100 parts by weight of polyoxymethylene (a), Sanol LS-7 70
was added at a blending ratio of 0.25 parts by weight, and the weather resistance was evaluated in the same manner as in Example 1. The results are shown in Table 4. The cracking time of this composition is extremely fast, and it cannot be said that it has the high weather resistance as defined in the present invention.

Comparative Example 3 Weather resistance was evaluated in the same manner as in Comparative Example 2, except that 3 parts by weight of acetylene black as a coloring component was further added to 100 parts by weight of polyoxymethylene. The results are shown in Table 4. Although this composition has a longer cracking time than Comparative Example 2 due to the weather resistance improving effect of acetylene black, it does not have the groundbreakingly excellent high weather resistance as defined in the present invention. I understand. Examples 22 to 31 Each test piece was prepared from this composition in the same manner as in Example 1, except that the type and amount of the coloring component, or the amount of the ultraviolet absorber and light stabilizer were changed. We fabricated it and evaluated its weather resistance. The results are shown in Table 3. In all compositions, good weather resistance with excellent uniformity as defined in the present invention was obtained. The red colored pigment used in Example 31 was quinacritone-based PVFAFT RED E3B. (Effects of the invention) The polyoxymethylene composition of the present invention with excellent weather resistance has
It maintains polyoxymethylene's original excellent mechanical properties, friction and wear properties, fatigue properties, moldability, etc., and also has extremely excellent weather resistance, making it suitable for use in, for example, the electronics/electrical machinery, automobile, and precision machinery fields. Suitable for use. In addition, the colored molded product of the present invention formed by molding this composition has excellent weather resistance even without plating or painting the surface, so it can be used as an exterior component as it is. It can be used for. Furthermore, even though the molded article of the present invention has a complicated structure, it has excellent uniformity of weather resistance throughout the molded article.

Claims (4)

[Claims] (1) 100 parts by weight of polyoxymethylene (A), 5 to 100 parts by weight of methacrylic acid ester polymer (B), 5 to 1 part of microparticles (C) which are resins that are highly compatible with (B)
00 parts by weight, in which (B) and (C
) A polyoxymethylene composition characterized in that polyoxymethylene is dispersed in the component. (2) The microparticles (C) are crosslinked polymer particles having a crosslinked structure inside, and the particle size in the present composition is 0.01.
A composition according to claim 1, wherein the composition is between .about.2.0 .mu.m. (3) The composition according to claim (2), wherein the crosslinked polymer particles are multiphase crosslinked polymer particles having a multiphase structure of two or more phases. (4) The composition according to claim 3, wherein the multiphase crosslinked polymer particles contain a soft polymer therein, and the soft polymer has a glass transition temperature of less than 25°C, preferably less than 0°C.