KR910004093B1 - Stabilized oxymethylene copolymer compositions - Google Patents

Abstract

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Description

Stabilized Oxymethylene Copolymer Composition

The present invention is superior to the novel stabilized oxymethylene copolymer composition, and more particularly to the conventional oxymethylene copolymer composition, which has excellent long-term stability, in particular, long-term hot water resistance and long-term heat aging characteristics, and precipitates to a mold during molding processing. This very little oxymethylene copolymer composition is concerned.

The oxymethylene copolymer is a plastic widely used in all of you as an engineering resin because of its excellent mechanical properties and moldability.

However, the oxymethylene copolymer itself is insufficient in stability, causing deterioration in the end portion of the polymer, or a main chain cutting in hot atmosphere or hot water. Therefore, the oxymethylene copolymer itself is usually oxidized after various end treatments. It is necessary to mix | blend and stabilize additives, such as an inhibitor or a heat stabilizer.

In particular, when using this oxymethylene copolymer as an engineering resin, mix | blending a thermal oxidation stabilizer is essential for the quality maintenance and improvement, and various stabilizers have been proposed until now.

For example, a stabilizer composed of at least one of a metal salt of an organic acid having at least one carboxyl group having 2 to 30 carbon atoms and containing no nitrogen, and a metal salt of an alcohol having 2 to 30 carbon atoms and containing no nitrogen (USP-3484399). ), A stabilizer composed of at least one compound selected from hydroxides, inorganic acid salts and alkoxy degrees of alkali metals or alkaline earth metals, nitrogen-containing polymer compounds and steric hindrance phenols (JP-A-56-10939).

In addition, the use of a boric acid ester of glycerin mono fatty acid ester as an antistatic agent of an oxymethylene copolymer (Japanese Patent Application Laid-Open No. 57-15616) has already been known, but its effect as a stabilizer has not been suggested.

As a method of suppressing precipitates (hereinafter referred to as MD) on the surface of the mold during molding, nitrogen compounds such as polyamide USP 2,993,025, (Japanese Patent Application Laid-Open No. 50-145458), an amide compound, or a hydrazine compound ( Japanese Patent Laid-Open Nos. 57-111346, 57-102943 and 59-33353, and Japanese Patent Laid-Open No. 54-32658).

However, the oxymethylene copolymer blended with fatty acid metal salts or metal salts of fatty acid alcohols, although the effect is recognized in the characteristics of long-term heat aging characteristics and long-term heat-resistant water resistance evaluation, there is a drawback that the color change of the test piece is remarkable. The oxymethylene copolymer containing a metal hydroxide, an inorganic acid salt or an alkoxide, a nitrogen-containing high molecular compound and a steric hindrance phenol also has some effects on the long-term heat aging characteristics, but in the long-term hot water resistance evaluation, In addition to the appearance of spots, there is a drawback of lowering the mechanical strength. Polyacetates containing boron esters of glycerin mono fatty acid esters, which are antistatic agents, are excellent in antistatic properties but do not show long-term heat aging characteristics and long-term hydrothermal resistance.

Moreover, the polyamide effective against MD certainly has an effect as a formaldehyde moisturizer, and the MD due to formaldehyde is suppressed, but the resulting MD occurs because the polyamide is easily attached to the mold. Nitrogen compounds, such as amide compounds or hydrazine compounds, have lower adhesion to molds than polaramides, but formaldehyde is less likely to inhibit the generation of MD.

Accordingly, it is an object of the present invention to overcome the drawbacks of conventional oxymethylene copolymers and to provide an oxymethylene copolymer which is excellent in long-term heat aging characteristics and long-term hydrothermal resistance as an engineering resin and with very low generation of MD.

The present inventors have diligently researched to develop excellent long-term heat aging characteristics, stabilizers to improve long-term heat-resistant water resistance and prevent the occurrence of MD without impairing desirable physical properties of the oxymethylene copolymer. The present invention has been accomplished based on this knowledge by discovering that the object can be achieved by alkaline earth metal salts of tribasic inorganic acid esters of monofatty acid esters of alcohols having two or more alcohols.

That is, the present invention is a stabilized oxymethylene copolymer formed by blending at least one compound selected from alkaline earth metal salts of tribasic inorganic acids of mono-fatty acid esters of alcohols having two or more -OH groups as a stabilizer with respect to the oxymethylene copolymer. It is to provide a composition.

The oxymethylene copolymer used in the composition of the present invention is a general formula

Oxymethylene unit represented by

및 옥시테트라메틸렌단위

가 특히 바람직하다.(Wherein R ¹ and R ² are each a hydrogen atom, an alkyl group or an aryl group, which are the same or different from each other and m is an integer of 2 to 6). The ratio of the oxyalkylene unit is not particularly limited as long as it is 0 or more, but is preferably in the range of 0.05 to 50 mol, more preferably 0.1 to 20 mol, relative to 100 mol of the oxymethylene unit. As this oxyalkylene unit, an oxyethylene unit, an oxypropylene unit, an oxy-tetramethylene unit, an oxyphenylethylene unit, etc. are mentioned, for example. Among these oxyalkylene units, an oxyethylene unit from the viewpoint of improving physical properties of the oxymethylene polymer

And oxytetramethylene units

Is particularly preferred.

This oxymethylene copolymer is obtained by copolymerizing or reacting formaldehyde, trioxane, an oxymethylene homopolymer, cyclic ether, and cyclic formal. The oxymethylene copolymer obtained here is preferably subjected to stabilization treatment of the molecular ends. As the stabilization treatment method, a method of usually esterifying the -OH at the polymer terminal or hydrolyzing until a relatively stable carbon-carbon bond is present at each terminal is used.

In the composition of the present invention, an alkaline earth metal salt (hereinafter referred to as stabilizer G) of a tribasic inorganic acid ester of a monofatty acid ester of an alcohol having two or more -OH groups is used as the stabilizer.

In this stabilizer G, as alcohols having two or more -OH groups, ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 6- Polyhydric alcohols such as dihydric alcohols such as hexanediol, 1 and 5-pentanediol, trihydric alcohols such as glycerin, trimethylethane and trimethylolpropane, pentaerythritol, sorbitan, sorbitol, mannitol and sucrose (sugarcane) And phenyl groups such as styrene glycol, phenylglycerol ether, phenoxy group substituents, and bisphenols such as bisphenol A, and the like, and preferred are glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitan, sorbitol, and mannitol. And polyhydric alcohols such as sucrose and the like, and particularly preferred are glycerin and sorbitan.

In this stabilizer G, the fatty acids used are acetic acid, propionic acid, butyric acid, valerianic acid, capronic acid, capric acid, lauric acid, myristiclan, palmitic acid, lauric acid, oleic acid, linoleic acid and behenic acid. And the like, Preferably they are C8-C22 fatty acids, such as capric acid, lauric acid, myristic acid, palmitic acid, lauric acid, oleic acid, linoleic acid, and behenic acid,

More preferred are lauric acid and lauric acid.

In the stabilizer G, for example, basic acid inorganic acid is preferably phosphoric acid or boric acid, and examples of alkaline earth metals include magnesium, calcium, barium, strontium, and the like. Among these, magnesium, calcium and Bathium is preferred.

That is, as the stabilizer G, monoborate ester magnesium salt of ethylene glycol monolaurate, monoborate ester calcium salt of 1,6-hexanediol monolaurate, monoborate ester calcium salt of glycerin monopropionate, and glycerin monolaurate Monoborate ester magnesium salt, monoborate ester barium salt of glycerin monolaurate, monoborate ester calcium salt of glycerin monolaurate, monoborate ester magnesium salt of glycerin monolaurate, monophosphate ester calcium of glycerin monolaurate Salt, monophosphate ester magnesium salt of glycerin monolaurate, monophosphate ester calcium salt of glycerin monolaurate, monophosphate ester magnesium salt of glycerin monolaurate, monoborate ester calcium salt of glycerin monobehenate, sorbitan mono To monoboric acid of laurate Tercalcium salt, monoborate ester magnesium salt of sorbitan monolaurate, monoborate ester barium salt of sorbitan monolaurate, monoborate ester calcium salt of sorbitan monolaurate, monoborate ester magnesium of sorbitan monolaurate Salt, monoborate ester barium salt of sorbitan monolaurate, monophosphate ester calcium salt of sorbitan monolaurate, monophosphate ester magnesium salt of sorbitan monolaurate, monophosphate ester barium salt of sorbitan monolaurate, etc. Can be mentioned.

The method for preparing stabilizer G is not particularly limited, but tribasic alcoholic acid is mixed with polyhydric alcohol monofatty acid and heated to obtain a condensed water, and the obtained compound is dissolved in an appropriate solvent to neutralize with hydroxide of alkaline earth metal to obtain a target product. And a method of mixing, heating and condensing an alkaline earth metal salt of tribasic inorganic acid with polyhydric alcohol monofatty acid ester (Japanese Patent Application No. 43-14322, Japanese Patent Application No. 48-43371).

One type of this stabilizer G may be used, or may be used in combination of 2 or more type.

In the composition of the present invention, the blending amount of stabilizer G is usually selected in the range of 0.01 to 5% by weight, preferably 0.03 to 1% by weight, more preferably 0.05 to 0.5% by weight, based on 100 parts by weight of the oxymethylene copolymer. The range of is selected.

If the blending amount is less than 0.01 part by weight, the effect of improving the long-term heat aging characteristics, the long-term heat-resistant water properties, and the MD inhibitory effect are not sufficiently exhibited. If the amount is more than 5 parts by weight, the silver streaks or silver stays during the injection molding process. It is not preferable because coloring tends to occur.

In the composition of the present invention, an antioxidant commonly used in the oxymethylene copolymer composition can be added. As the antioxidant, steric hindrance phenols, steric hindrance amines and the like are used. Specifically, 2,2'-methylene-bis (4-methyl-6-t-butylphenol) and triethylene glycol-bis [3- (3 -t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythridyl-tetrakis [3-3,5-di-t-butyl-4-hydroxyphenyl) propionate] , 1, 6-hexanediol-bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate], dilauryl-3, 5-di-butyl-4-hydroxybenzyl Phenols such as phosphonate, and 3, 5-di-t-butyl-4-hydroxyphenyl-3, 5-dilauryl-thiotriazylamine, N-phenyl-N'-isopropyl-[-phenylene Diamine, N, N'-diphenyl-p-phenylenediamine, 4, 4'-bis (4-α, α-dimethylbenzyl) diphenylamine, N, N'-di-β-naphthyl-p- Amines, such as phenylenediamine, can be used. Among these antioxidants, in particular, 2, 2'-methylene-bis (4-methyl-6-t-butylphenol), triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydride Hydroxyphenyl) propionate], pentaerythryl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] are effective.

In addition, the composition of the present invention can be blended with at least one nitrogen-containing compound selected from polyamides, triazines and dicyandiamides.

(단, R은 수소원자 또는 알킬기이다)로 나타내는 결합을 갖는 고분자량 화합물로서, 구체적으로는, 카프로락탐, 라우로락탐 등의 락탐으로써 구성된 중합체, 아디핀산, 세바신산, 도데칸 2산, 리놀산의 2량체 등의 디카르복실산과 에틸레디아민, 테트라메틸렌디아민, 헥사메틸렌디아민, 메타크실릴렌디아민 등의 디아민과의 반응에 의하여 얻어지는 중합체, 및 폴리-알라닌(일본 특개소 59-213722 및 59-213752호)나 이들 중합체의 공중합체 등이 사용된다. 구체적으로는, 나이론 6, 12, 46, 66, 610, 612, 폴리(크실릴렌아디프아미드)등이다. 이들 폴리아미드는 1종을 사용할 수도 있고 2종 이상을 조합하여 사용할 수도 있다.As the polyamides used herein, formulas in the dispersion chain

(Wherein R is a hydrogen atom or an alkyl group), specifically, a polymer composed of lactams such as caprolactam and laurolactam, adipic acid, sebacic acid, dodecane diacid, linoleic acid Polymers obtained by the reaction of dicarboxylic acids, such as dimers, with diamines such as ethylediamine, tetramethylenediamine, hexamethylenediamine, and methaxylylenediamine, and poly-alanine (Japanese Patent Laid-Open Nos. 59-213722 and 59 -213752), copolymers of these polymers, and the like. Specifically, nylon 6, 12, 46, 66, 610, 612, poly (xylylene adiamide), etc. are mentioned. One kind of these polyamides may be used, or two or more kinds thereof may be used in combination.

As the triazines, melamine, acetguanamine, acryloguanamine and the like are used, and these triazines may be used either alone or in combination of two or more thereof.

Preferred among these nitrogen-containing compounds is the use of polyamides.

The compounding quantity of these nitrogen-containing compounds is normally 0.01 to 1 weight%, Preferably it is 0.01 to 1 weight% More preferably, it is selected in the range of 0.05 to 0.5 weight%.

In the composition of the present invention, there is no particular restriction on the order of adding the stabilizer G, and further to the antioxidant and the nitrogen-containing compound, and the shape of each of these components, and either powder, solution or solution may be used.

In the present composition, other additives usually blended in the oxymethylene copolymer composition, for example, antistatic agents, lubricants or inorganic fillers such as glass fibers and glass beads, reinforcing materials such as carbon fibers, pigments and the like may be blended as desired. There is a number.

The oxymethylene copolymer composition of the present invention has a tensile strength and weight in the 140 ° C long-term heat aging characteristics test and the 120 ° C long-term hot water resistance test as compared to the conventional oxymethylene copolymer composition by adding stabilizer G to the oxymethylene copolymer. The retention rate is remarkably improved, and the appearance change of the test molded article is extremely small. In addition, when continuous molding is performed, generation of MD is extremely low as compared with the conventional oxymethylene copolymer composition, and the appearance of the molded article is also good.

In such a long-term characteristic, it is considered that the alkaline earth metal heat contained in the stabilizer G effectively acts as a formic acid acceptor generated by thermal decomposition of the oxymethylene copolymer. In addition, it is thought that the stabilizer G is unlikely to be a form-forming catalyst, whereas the alkali metal and alkaline-earth metal hydroxides and oxides form catalysts for forming a formose. Moreover, about the point that MD generation | occurence | production is small in continuous molding, it is thought that the stabilizer G suppresses that formaldehyde gas adheres to the metal mold | die surface. In addition, the generation of MD is suppressed synergistically by the combination of nitrogen-containing compounds.

By these facts, the oxymethylene copolymer composition of the present invention can withstand severe use environments such as under high temperature or in hot water for a long time, and also contributes to the improvement of productivity since there is little MD generation even in long continuous molding. .

Next, the present invention will be described in more detail with reference to Examples.

And in the Example and the comparative example, each characteristic of the composition was calculated | required as follows.

(1) Long-term hydrothermal environmental test

The 120 degreeC hot water test was done using the autoclave with a pressure composition variation. However, the test water was carried out by the 120 degreeC flow-through system using ion-exchange water, attaching a temperature control apparatus and a flowmeter.

For the evaluation, for the initial molded product and the molded product after the retention, the tensile elongation (according to ASTM D-638), the tensile strength (according to ASTM D-638), the retention of weight (measured in 10 mg units), and the appearance change of the molded article The degree was calculated.

(2) appearance change of molded products

Changes in the appearance of the initial molded article and the molded article after the stay were visually observed and evaluated according to the following criteria.

Criteria

○: slight color change due to the naked eye.

(Triangle | delta): A yellowing clearly appears by visual observation, or the uneven | corrugated pattern appears in several places on the surface of a molded article.

× Multicolored change is seen. Or irregularities appear on the front surface of the molded article.

(3) Long-term hot air environmental test

The gear oven (the GPS-222 type | mold (exhaust duct 20 degree opening) made by Divi Corporation) was done for 140 degreeC long-term hot air environment test. The evaluation items and methods are the same as the long-term hydrothermal environmental test.

(4) Evaluation by continuous molding test

Injection molding machine ilgang N 70 A (made by Nippon Steel Co., Ltd.)

Cylinder temperature 200 ℃

Injection pressure 40Kg / cmC

Injection period 5sec Cooling 5sec

Molding temperature 90 ℃ and 30 ℃

Under the above molding conditions, after 5,000 shots of continuous molding of JIS-3 tensile test piece was performed, the state of the mold precipitate was visually observed and evaluated according to the following criteria.

[Criteria]

0: The mold precipitate does not appear at all.

1: Mold precipitate hardly appears.

2: The mold precipitate appears faintly.

3: The mold precipitate appears clearly.

4: The metal mold | die precipitate adhered thickly to the front surface of a metal mold | die.

(5) Change of appearance of molded product after molding stay

After staying at the material temperature of 230 ° C. for 1 hour in an injection molding machine (221-55-250), a ballistic piece having a test piece shape of about 3 × 12 × 120 mm was formed, and the degree of warming of the molded product was observed. It evaluated according to the criterion.

[Criteria]

(Circle): Silver bath or yellowing does not appear on the molded object surface.

(Triangle | delta): A silver bath appears partly on the molded article surface. Or yellowing of the molded article appears.

Silver tin appears on the front surface of the molded article. Or yellowing of the molded article is clearly strong.

[Production of Oxymethylene Copolymer]

98 wt% trioxane and 2 wt% ethylene oxide were polymerized using a boron fluoride butyl ether complex as a catalyst to obtain a crude oxymethylene copolymer, to which triethylamine was added to stop the reaction to give a polymer. Separated. A mixture of triethylamine-water was then added to this polymer to remove terminal instability in a vented 65 ° compressor. M1 of the polymer after the terminal stabilization was 9.5 (g / 10 min).

This polymer is called B-1. Further, 97% by weight of trioxane and 3% by weight of 1,3-dioxane were polymerized as described above to obtain an end stabilized oxymethylene copolymer [M1 9.0 (g / 10 min)]. This polymer is called B-2.

Examples 1 to 36 and Comparative Examples 1 to 11

The compositions shown in Tables 1 to 4 are homogeneously mixed by a Henschel mixer, the mixture is melt stabilized through a 50 ° extruder and the resin is obtained as a strand from the die head. The strands were immediately pelletized and subjected to various evaluations after drying. The results are shown in Tables 1-4.

Symbols in the table indicate the following.

[Stabilizer G]

G-1: Monoborate ester calcium salt of glycerin monolaurate

G-2: monoborate ester magnesium salt of glycerin monolaurate

G-3: monoborate ester calcium salt of glycerin monolaurate

G-4: monophosphate calcium salt of glycerin monolaurate

G-5: monophosphate magnesium salt of glycerin monolaurate

G-6: Monoborate ester barium salt of glycerin monolaurate

G-7: monoborate ester calcium salt of sorbitan monolaurate

G-8: monophosphate ester calcium salt of sorbitan monolaurate

G-9: monoborate ester barium salt of sorbitan monolaurate

G-10: monoborate ester calcium salt of glycerin monopropionate

G-11: monoborate ester magnesium salt of ethylene glycol monolaurate

G-12: monoborate ester calcium salt of 1, 6-hexanediol monolaurate

G-13: monoborate ester calcium salt of glycerin monobehenate

[Antioxidant]

A-1: triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (brand name: Monogax 245 (manufactured by Chiba-Gaiyi Co., Ltd.))

A-2: pentaerythritol-tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate] (brand name: Iganox 1010 (made by Chiba Kaiki))

A-3: 2, 2'-methylene-bis (4-methyl-6-t-butylphenol) (brand name: Yoshinox 2246 (made by Yoshitomi Pharmaceutical Co., Ltd.))

[Nitrogen-containing compound]

C-1: Nylon 66

C-2: Nylon 6/66/610 (40% / 30% / 30%)

C-3: Poly-β-alanine

C-4: Melamine

C-5: dicyandiamide

[Other stabilizers]

D-1: Monoborate Ester of Glycerine Monolaurate

D-2: calcium laurate

D-3: Calcium Ricinolate

D-4: Calcium Hydroxide

D-5: Monoborate ester sodium salt of glycerin monolaurate

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Claims (11)

A stabilized oxymethylene copolymer composition formed by mixing an alkaline earth metal salt of a tribasic inorganic acid ester of a monofatty acid ester of an alcohol having two or more -OH groups as a stabilizer with respect to the oxymethylene copolymer. The stabilized oxymethylene copolymer composition according to claim 1, wherein the alcohols are trivalent or higher polyhydric alcohols. The stabilized oxymethylene copolymer composition according to claim 2, wherein the alcohols are glycerin or sorbitan. The stabilized oxymethylene copolymer composition according to claim 1, wherein the fatty acid of the monofatty acid ester is a fatty acid having 8 to 22 carbon atoms. The stabilized oxymethylene copolymer composition according to claim 4, wherein the fatty acid of the monofatty acid ester is lauric acid or lauric acid. The stabilized oxymethylene copolymer composition according to claim 1, wherein the inorganic acid of the tribasic inorganic acid ester is boric acid or phosphoric acid. The stabilized oxymethylene copolymer composition according to claim 1, wherein the alkaline earth metal salt is a salt of magnesium, calcium or barium. The stabilized oxymethylene copolymer composition according to claim 1, comprising 0.01 to 5% by weight of a stabilizer. The stabilized oxymethylene copolymer composition according to claim 1, wherein the stabilized oxymethylene copolymer composition is blended with at least one nitrogen-containing compound selected from polyamides, triazines, and dicyandiamides. 10. The stabilized oxymethylene copolymer composition of claim 9, wherein the nitrogenous compound is a polyamide. The stabilized oxymethylene copolymer composition according to claim 9, comprising 0.01 to 5% by weight of a nitrogen-containing compound.