JPS585935B2 - Polyester elastomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stabilizing polyester elastomers.

More specifically, the present invention aims to provide a method for improving the oxidation resistance and weather resistance of polyester elastomers at high temperatures.

Conventionally, natural rubber, vinyl-based synthetic rubber, polyurethane, and the like have been widely used as elastomers, but aromatic polyester-based elastomers have recently attracted attention because of their excellent bending fatigue resistance and low-temperature properties.

Polyester elastomers include, for example, terephthalic acid,
It can be obtained by polycondensing tetramethylene glycol, polyoxytetramethylene glycol, etc. using a specific catalyst such as an organic titanium compound (Japanese Patent Laid-Open No. 47-25295).
(see specification).

However, when polyester elastomer is used alone, it deteriorates due to the action of oxygen in the air and light.

Therefore, for the purpose of preventing the deterioration phenomenon, polyester elastomers are added with 4,4'-bis(hindered phenols such as 2,6-di-t-butylphenol), metal salts such as nickel dibutyldithiocarbamate, and N,N'-bis(N,N'-bis). Attempts have been made to add amines such as (β-naphthyl)-P-phenylenediamine as an antioxidant.

However, these have drawbacks such as insufficient effects, scattering during polymerization or molding, or coloring of the polymer when added, and none of them are satisfactory.

As a result of intensive research into a method for stabilizing polyester elastomers that does not have such drawbacks, the present invention has developed a compound specified by the following general formula [I], a compound specified by the following general formula [■], and/or a compound specified by the following general formula We have discovered that if the compound specified in [■] is added at any stage of the manufacturing process, the thermal stability and light stability of polyester elastomers can be significantly improved, and the color tone can also be maintained in a favorable state. We have arrived at the present invention.

That is, the present invention provides (1) dicarboxylic acids and/or ester-forming derivatives thereof (B) low molecular weight glycols and/or ester-forming derivatives thereof (0) polyoxyalkylene glycols having an average molecular weight of 500 to 5000 and/or ester-forming derivatives thereof; In stabilizing the polyester elastomer polycondensed so that the component (C) accounts for 10 to 90% of the total weight of the polyester elastomer, from the raw material preparation stage of the polyester elastomer until the completion of molding of the polyester elastomer. (1) General formula [wherein R1 is a lower alkylene group].

] with one or more of the compounds represented by [where R3 and R4 are the same or different and are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 2 to 10 carbon atoms, and X1 is a halogen atom, n is 0 or 1.

] and/or the general formula [where R5 is a hydrogen atom, an alkoxy group or a hydroxy group].

This is a method for stabilizing a polyester elastomer, which is characterized by adding one or more of the compounds shown below.

It is preferable that 55 mol % or more of the dicarboxylic acid used as a component constituting the polyester elastomer is occupied by only one type of dicarboxylic acid, and the dicarboxylic acid is preferably an aromatic dicarboxylic acid.

Preferred aromatic dicarboxylic acids include terephthalic acid, inphthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 1,5
-naphthalene dicarboxylic acid, diphenyl-4,4'-
Dicarboxylic acid, 3,3'-dimethyldiphenyl-4,
Examples include 4'-dicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 4,4'-diphenoxyethanedicarboxylic acid.

Although aliphatic dicarboxylic acids and alicyclic dicarboxylic acids can also be used, it is preferable to limit the amount of these to 45' mole % or less of component (2).

Such dicarboxylic acids include oxalic acid, adivic acid,
Examples include sebacic acid, 1,4-cyclohexanedicarboxylic acid, and decahydronaphthalene-2,6-dicarboxylic acid.

The dicarboxylic acids may be used alone or in combination of two or more.

Similar to the dicarboxylic acids mentioned above, their ester-forming derivatives can also be used.

Examples of ester-forming derivatives include methyl ester,
Examples include lower alkyl esters such as ethyl ester, substituted aliphatic esters such as 2-hydroxyethyl ester, aryl esters such as phenyl ester, carbonic acid esters, and acid halides.

As the component (B), aliphatic glycols such as tetramethylene glycol hexamethylene glycol are preferably used, but aromatic groups such as bishydroxyethoxybisphenol A, 4,4'-bishydroxyethoxydiphenyl sulfone, etc. Glycols having an alicyclic group such as cyclohexane dimethanol and the like can also be used.

The glycol used as component (B) preferably has a molecular weight of 400 or less.

Similar to the glycols mentioned above, ester-forming derivatives thereof can also be used.

Examples of such ester-forming derivatives include monoesters and diesters with monocarboxylic acids.

Oxycarboxylic acids and ester-forming derivatives thereof can also be used as part of the components (A) and (B), and P-hydroxybenzoic acid is exemplified as a preferable oxycarboxylic acid.

As the component (C), polyoxyalkylene glycol having an average molecular weight of 500 to 5,000 is used.

The average molecular weight of the polyoxyalkylene glycol is 50
If the average molecular weight is less than 0, the resulting polyester will have insufficient elasticity, and if the average molecular weight is more than 5,000, it will be difficult to copolymerize into the polyester and will tend to become a mere blend, which is not preferred.

The polyoxyalkylene glycol includes polyoxyethylene glycol, polyoxypropylene glycol, poly-1,2-butylene ether glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, and polyoxyhebutamethylene glycol.

Examples include polyoxyoctamethylene glycol and polyoxynonamethylene glycol.

Among these, polyoxytetramethylene glycol is particularly preferred.

As the polyoxyalkylene glycol, not only non-copolymerized polyoxyalkylene glycols but also random or block copolymerized polyoxyalkylene glycols can be used.

An ethylene oxide propylene oxide copolymer is exemplified as a typical copolymer.

In the case of copolymers, 80 mol% of the number of repeating units thereof
Preferably, the above groups are occupied by one type of oxyalkylene group.

The polyoxyalkylene glycols may be used alone or in combination of two or more.

In this case, it is preferable that 80% mole % or more of the number of repeating units in the mixed polyoxyalkylene glycol be accounted for by one type of osialkylene group.

Similar to the polyoxyalkylene glycol described above, ester-forming derivatives thereof can also be used. Examples of such ester-forming derivatives include monoesters and diesters with monocarboxylic acids.

? Component C) is preferably used so that its polyoxyalkylene component accounts for 10 to 90% by weight, particularly 20 to 70% by weight, of the polyester produced.

The polyoxyalkylene component referred to in N refers to a polyoxyalkylene moiety composed only of repeating units of the polyoxyalkylene glycol or its ester-forming derivative.

In order to produce a polyester elastomer, the above (4)
, @ and component (C) may be polycondensed by any method.

For polycondensation, ■ A method of starting polycondensation after charging all three components (8) and (C) above ■ After charging both components (B) above and causing a certain degree of polycondensation, (Method of completing polycondensation by adding component 0 and copolymerizing.) After charging the above A and (C) components and causing some degree of polycondensation, component (2) is added and copolymerized to complete the polycondensation. Any method can be used, such as "method for completing the process."

As a reaction catalyst, a conventionally known transesterification catalyst and/or polymerization catalyst can be used.

In particular, it is preferable to use organic titanates as catalysts.

One of the stabilizers that can be used in the present invention is general formula [However, R1 is a lower alkylene group.

] This is a compound represented by

Examples of the lower alkylene group for R1 in the general formula [I] include ethylene group, propion group, butylene group, neopentylene group, and the like.

Representative compounds include 2,2'-thiobis[ethylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), 3,3'-thiobis[propylene-3-(3 , 5-di-t-butyl-4-hydroxyphenyl)propionate], 4,4'-thiobis[butylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 3, 3'-thiobis [
Neopentylene-3-(3,5-di-t-butyl-4-
hydroxyphenyl) propionate] and the like.

One or more types of these can be used. In addition, the compound used in combination with the compound represented by the above general formula [I] [provided that R3 and R4 are the same or different hydrogen atoms, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 2 to 10 carbon atoms; , X1 is a halogen atom, and n is 0 or 1.

] and/or one or more compounds represented by the general formula [■
] [However, R5 is a hydrogen atom, an alkoxy group or a hydroxy group.

] This is a compound represented by

R3 and R4 in the general formula [■] are hydrogen atoms: alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, propyl, butyl, t-butyl, etc., or 2 to 10 carbon atoms such as ethoxy, butoxy, octoxy, etc. is an alkoxy group.

X1 is a halogen atom such as a chlorine atom or a bromine atom.

A representative example of the compound represented by the general formula [■] is 2-(2'-hydroxy-3',5'-di-t-
butylphenyl)benzotriazole, 2-(2'-hydroxy3',5'-di-t-butylphenyl)-5-
Chlorobenzotriazole, 2-(2'-hydroxy-
5'-methylphenyl)benzotriazole, 2-(2
'-Hydroxyphenyl)benzotriazole, 2-(
2'-hydroxy-3',5'-dimethylphenyl)benzotriazole, 2(2'-hydroxy-3'-t-
butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-methyl-5'-t-butylphenyl)
Benzotriazole, 2-(2'-hydroxy-3',
5'-ethylphenyl)benzotriazole, 2-(2
'-hydroxyphenyl)-5-chloropenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di- t-butylphenyl)-5-
Chlorobenzotriazole, 2-(2'-hydroxy-
5'-ethoxyphenyl)benzotriazole, 2-(
2'-hydroxy-5-butoxyphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'
Examples include -methyl-5'-ethoxyphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-4'-octoxyphenyl)penzotriazole.

Further, R5 in the general formula [■] is a hydrogen atom; an alkoxy group such as methoxy, octyloxy, or ethoxy; or a hydroxy group.

Representative compounds represented by the general formula [■] include 2-hydroxy-5-methylbenzophenone, 2,4-
Examples include dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxybenzophenone, 2,5-dihydroxybenzophenone, etc. .

The stabilizer may be added at any stage from the stage of raw material preparation of the polyester elastomer to the completion of molding of the polyester elastomer.

The amount of the stabilizer compound represented by the general formula [I] is preferably 0.001 to 5% by weight based on the polyester;
Particularly preferred is 0.005 to 2% by weight.

If it is less than 0.001% by weight, the effect of the present invention is not sufficient, and if it is more than 5% by weight, the effect does not increase and tends to reach a plateau.

The amount of the compound represented by the general formula [■] or [■] added is preferably 0.001 to 3% by weight, particularly preferably 0.01 to 1% by weight, based on the polyester.

If the amount is less than 0.001% by weight, the effect of the present invention is insufficient, and if the amount is more than 3% by weight, the effect does not increase and tends to reach a plateau.The polyester elastomer stabilized by the method of the present invention is excellent. It has heat oxidation resistance and UV resistance.

Carbon black, titanium oxide, pigments, other modifiers, etc. can be added to the polyester elastomer stabilized by the method of the present invention.

Hereinafter, the present invention will be explained in detail with reference to Examples.

In addition, in the examples, "parts" mean parts by weight.

Further, the reduced specific viscosity is a value measured at 35° C. by dissolving 120 mg of a sample polymer in 10 ml of O-chlorophenol, and [COOH] represents the molar equivalent of carboxyl groups per 106 g of polymer.

Examples 1 to 5 and Comparative Example 1 55.8 parts of dimethyl terephthalate, 38.8 parts of tetramethylene glycol, and 90.8 parts of polyoxytetramethylene glycol with an average molecular weight of 2000 were placed in a reactor equipped with a stirrer, a distiller, and a nitrogen introduction tube. (this component accounts for 60% by weight in the total polymer) and 0.0245 parts of tetrabutoxy titanate, and heated at 180 to 220°C.
After distilling out 90% of the theoretical amount of methanol produced, the temperature was raised to 240°C and the reaction was carried out at normal pressure for 30 minutes, and then the reaction was continued for 30 minutes under a weak vacuum of about 30 mmHg abs. Polymerization was carried out under high vacuum of .1-0.3 mmHg abs for 200 minutes.

Next, the system was returned to normal pressure with nitrogen, and 0.75 parts of 2,2'-thiobis[ethylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (0.75 parts based on the polymer) .5% by weight) and 0.15% of the light stabilizer shown in Table 1.
(0.1% by weight based on the polymer) and stirred for 10 minutes.

The obtained polyester elastomer was made into chips and
It was vacuum dried at ℃ for 5 hours and molded.

The reduced specific viscosity (ηsp/c) of the obtained samples was 2.13, and [COOH] was 11.2.

Next, the sample was irradiated with a weatherometer for 48 hours, and as a result, ηsp/c, its retention rate, and [COOH] were as shown in Table 1.

Example 6 2,2′-thiobis[ethylene-3-(3,5-di-t-butyl-4
-Hydroxyphenyl)propionate] to a polyester elastomer containing 0.5% (by weight) of 2-hydroxy-4-methoxybenzophenone (0.075 parts by weight (based on polymer)). and 2-(2'-hydroxy-4'-octoxyphenyl)
0.075 parts of benzotriazole (0 parts based on polymer)
．． 05% by weight) and mixed for 10 minutes.

The obtained polyester elastomer was made into chips and
It was vacuum dried at ℃ for 5 hours and molded.

The reduced specific viscosity (ηSP/C) of the obtained sample was 1.9
8, [COOH] was 15.1.

Next, the sample was irradiated with a weatherometer for 48 hours, and as a result, ηSP/C was 1.33, and the retention rate of ηSP/C was 6.
7.5%, [COOH] was 26.3.

Example 7 4,4'-thiobis[butylene-3-(3.5-di-t-butyl-4
0.1 part of 2-hydroxy-4-octoxybenzophenone (0.07% by weight based on the polymer) in a polyester elastomer containing 0.5% by weight (based on the polymer) 2-hydroxy-4-octoxybenzophenone. and 2-
0.1 part (2'-hydroquine-3',5'-di-t-butylphenyl)5-chlorobenzotriazole (0.07 parts by weight based on polymer) was added and mixed for 10 minutes.

The obtained polyester elastomer was made into chips and
It was vacuum dried at ℃ for 5 hours and molded.

The reduced specific viscosity (ηSP/C) of the obtained sample was 2.0
8, [C00H] was 14.3.

Next, the sample was irradiated with a weather meter for 48 hours, and as a result, ηSP/C was 1.44, and the retention rate of ηSP/C was 69.
．． 5%, [COOH] was 23.5.

Claims (1)

[Scope of Claims] 1 (A) dicarboxylic acids and/or ester-forming derivatives thereof (B) low molecular weight glycols and/or ester-forming derivatives thereof (C) polyoxyalkylene glycols with an average molecular weight of 500 to 5,000 and/or When stabilizing the polyester elastomer obtained by polycondensing the three ester-forming derivatives so that the component (C) accounts for 10 to 90% of the total weight of the polyester elastomer, the polyester elastomer is used from the raw material preparation stage of the polyester elastomer. At any stage until the molding is completed, [where R1 is a lower alkylene group]. ] and (1) general formula [where R3 and R4 are the same or different and are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 2 to 10 carbon atoms, and X1 is It is a halogen atom, and n is 0 or 1. ] and/or the general formula [where R is a hydrogen atom, an alkoxy group, or a hydroxy group. A method for stabilizing a polyester elastomer, which comprises adding one or more of the compounds shown below.