JPH0657096A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To provide the polyacetal resin composition little in decline in its mechanical properties in hot water and in the discoloration and surface appearance of the molded products therefrom, also excellent in resistance to hydrolysis, by incorporating a polyacetal resin with a specific reaction product. CONSTITUTION:The resin composition can be obtained by incorporating (pref. kneading in a molten state) (A) a polyacetal resin with (B) pref. 0.001-5 pts.wt., based on 100 pts.wt. of the component A, of a reaction product formed by reaction of a hindered amine compound of the formula (R<1> is H or a 1-30C monovalent organic group; R<2>-R<5> are each a 1-5C alkyl; n is 1 or more; R<6> is a n-valent organic residue) [pref. bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate] in the presence of a boron trifluoride-based catalyst (pref. boron trifluoride- phenol complex).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal resin composition which is excellent in hydrolysis resistance and which has little deterioration of mechanical properties in hot water and little coloring and deterioration of surface appearance of molded articles. .

[0002]

2. Description of the Related Art Polyacetal resins have a well-balanced mechanical property and are excellent in heat resistance, chemical resistance, and electric characteristics, and are therefore widely used in automobile parts and electric / electronic fields. However, the polyacetal resin is inferior in hydrolysis resistance, and for example, when it is used in hot water for a long time, mechanical properties are deteriorated due to crack generation, and coloring of the molded product or deterioration of the surface appearance of the molded product is caused. There are drawbacks, and various compounding formulations of stabilizers have hitherto been studied.

For example, JP-A-57-98545 discloses a method of improving weather resistance by adding a piperidine derivative having a specific structure and an oxalic acid anilide derivative.

Further, a method of adding a hindered amine compound having a specific structure as a heavy terminator at the end of heavy term is disclosed in JP-A-62-267312.

Further, a metal salt of an organic acid having 2 to 30 carbon atoms having at least one carboxyl group and 2 to 2 carbon atoms.
Japanese Patent Application Laid-Open No. 3-39351 discloses a method of adding a metal salt containing at least one metal salt of 30 alcohols and hydrotalcite to improve hydrolysis resistance.

However, the above-mentioned JP-A-57-98545
In the method disclosed in Japanese Patent Laid-Open No. 62-267312, the thermal stability and weather resistance are improved, but when used in hot water for a long time, the molded product is colored and cracks are generated. However, it has a drawback that mechanical properties are deteriorated, and it is not sufficiently satisfactory in terms of hydrolysis resistance.

In the method disclosed in Japanese Patent Laid-Open No. 3-39351, deterioration of mechanical properties due to hydrolysis is improved, but suppression of coloring of molded products and deterioration of surface appearance is insufficient.

[0008]

SUMMARY OF THE INVENTION As described above, the conventionally known method sufficiently improves the deterioration of mechanical properties of polyacetal resin in hot water and the coloring of molded articles and the deterioration of surface appearance. is not. Therefore, it is an object of the present invention to obtain a polyacetal resin composition which is excellent in hydrolysis resistance with less deterioration of mechanical properties in hot water, and less coloring of molded products and deterioration of surface appearance.

[0009]

As a result, the inventors of the present invention solve the above problems by using a polyacetal resin containing a reaction product of a hindered amine compound having a specific structure and a boron trifluoride catalyst. The inventors have found that and reached the present invention. That is, the present invention is a polyacetal resin in the following general formula

[Chemical 2]

(Wherein R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, which are the same as each other. And n may be different from each other, n is an integer of 1 or more, and R ⁶ is an n-valent organic residue.) And a reaction product of a hindered amine compound and a boron trifluoride-based catalyst. The present invention provides a polyacetal resin composition comprising

In the present invention, it is important to blend a reaction product of a hindered amine compound having a specific structure and boron trifluoride with the polyacetal resin, whereby a polyacetal resin composition having excellent hydrolysis resistance is obtained. You can get things.

The structure of the present invention will be described in detail below. As the polyacetal resin used in the present invention, a homopolymer consisting of a chain of oxymethylene units and a majority consisting of a chain of oxymethylene units, having a main chain of 2 to 2
It means an oxymethylene copolymer containing up to 15% by weight of oxyalkylene units having 8 adjacent carbon atoms. The oxymethylene homopolymer is produced, for example, by introducing substantially anhydrous formaldehyde into an organic solvent containing a basic polymerization catalyst such as an organic amine to polymerize it, and then acetylating the terminal with acetic anhydride. The oxymethylene copolymer is obtained by, for example, dissolving or suspending substantially anhydrous trioxane and a copolymerization component such as ethylene oxide or 1,3-dioxolane in an organic solvent such as cyclohexane, and then adding boron trifluoride. Polymerize by adding a Lewis acid catalyst such as diethyl etherate,
It is manufactured by decomposing and removing unstable ends. Alternatively, without using a solvent at all, trioxane, a copolymerization component and a catalyst are introduced into a self-cleaning stirrer to perform bulk polymerization, and then unstable terminals are decomposed and removed for production.

Further, those obtained by crosslinking polyacetal by a known method, modified by graft copolymerization, or modified by block copolymerization can be used.

The hindered amine compound constituting the reaction product of the hindered amine compound and the boron trifluoride-based catalyst used in the present invention has the following general formula.

[0015]

[Chemical 3]

(Wherein R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, which are the same as each other. It may or may not be different from each other.)

That is, it is a hindered amine compound having a specific structure.

Specific examples of the hindered amine compound of the present invention include bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate and bis (1,2,2,6,6-).
Pentamethyl-4-piperidinyl) sebacate, 1,
2,3,4-butanetetracarboxylic acid tetrakis (2,3
2,6,6-tetramethyl-4-piperidinyl) ester, poly [[6- (1,1,3,3-tetramethylenebutyl) imino-1,3,5-triazine-2,4-diyl] [ (2,2,6,6-tetramethyl-4-piperidinyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidinyl) imino]], dimethyl succinate 1- (2- Hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, and N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,
2,2,6,6-pentamethyl-4-piperidyl) amino] -1,3,5-triazine condensate, particularly bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, Bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-
2,2,6,6-tetramethylpiperidine polycondensate,
N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,2
6,6-Pentamethyl-4-piperidyl) amino]-
1,3,5-triazine condensates are preferred. This hindered amine compound may be used alone or in combination of two or more.

The boron trifluoride-based catalyst used in the present invention is boron trifluoride, boron trifluoride hydrate, or a coordination compound of an organic compound having an oxygen or sulfur atom and boron trifluoride. is there. Among them, a coordination compound of boron trifluoride is preferable, and boron trifluoride / diethyl ether complex, boron trifluoride / di (n-butyl) ether complex, and boron trifluoride / phenol complex are particularly preferable. The catalyst is used in the form of gas, liquid, or solution of a suitable organic solvent.

The method for producing the reaction product of the hindered amine compound and the boron trifluoride catalyst used in the present invention is not particularly limited. For example, it is produced by mixing a hindered amine compound with a boron trifluoride-based catalyst and subsequently vacuum drying. Or as a reaction solvent,
Aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol, ethanol and isopropanol, chloroform, dichloromethane and 1,2-dichloroethane. Halogenated hydrocarbons such as carbon tetrachloride, acetone, ketones such as methyl ethyl ketone, and ethers such as diethyl ether are used. After reacting the hindered amine and boron trifluoride-based catalyst under stirring, vacuum evaporation is performed. It is produced by removing unreacted materials in.

The reaction product of the hindered amine compound and the boron trifluoride-based catalyst used in the present invention is benzene,
Aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol, ethanol and isopropanol, chloroform, dichloromethane,
It can also be used as a solution of 1,2-dichloroethane, halogenated hydrocarbon such as carbon tetrachloride, acetone, ketones such as methyl ethyl ketone, and ethers such as ethyl ether. Therefore, the hindered amine compound and the boron trifluoride-based catalyst may be reacted in an organic solvent and used as they are.

The main component of the reaction product of the hindered amine compound and the boron trifluoride-based catalyst of the present invention is represented by the following general formula:

[0023]

[Chemical 4]

(Wherein R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, which are the same as each other. May be present or different from each other, n is an integer of 1 or more, and R ⁶ is an n-valent organic residue). It may contain an unreacted hindered amine compound that has not reacted with.

In the present invention, the addition amount of the reaction product of the hindered amine compound and the boron trifluoride-based catalyst is 0.001 to 5 parts by weight based on 100 parts by weight of the polyacetal resin. If it is less than 0.001 part by weight, the effect of improving the hydrolysis resistance is not sufficient, and if it exceeds 5 parts by weight, the mechanical properties are deteriorated, which is not preferable.

The method for producing the polyacetal resin composition of the present invention is not particularly limited, but it is preferably produced by melt-kneading the reaction product of the polyacetal resin, the hindered amine compound and the boron trifluoride catalyst. . As the melt-kneading method, for example, a method of melt-kneading at a temperature of 120 ° C. to 280 ° C. using a Banbury mixer, a roll kneader, a single-screw or twin-screw extruder, etc. can be adopted. Alternatively, a method of once preparing pellets (masterbatch) having different compositions and mixing (diluting) the pellets by a predetermined amount can be adopted.

The polyacetal resin composition of the present invention contains a known hindered phenol-based antioxidant, phosphite-based antioxidant, thioether-based antioxidant, amine-based antioxidant, benzophenone-based antioxidant, benzophenone-based antioxidant, benzophenone-based antioxidant, benzophenone-based antioxidant, benzophenol Triazole-based, hindered amine-based weathering agents, melamine, dicyandiamide, polyamide, polyvinyl alcohol copolymers and other formaldehyde scavengers, titanium oxide, carbon black and other UV-screening agents, glass fibers, carbon fibers, potassium titanate fibers, etc. Reinforcing agents, fillers such as silica, clay, calcium carbonate, calcium sulfate, glass beads, glass flakes, nucleating agents such as talc, branched or reticulated polyacetal, other known release agents, flame retardants, plasticizers, adhesives Auxiliary agents, adhesives, etc. may optionally be included. It is possible. Furthermore, for the purpose of improving the mechanical strength of the polyacetal resin composition of the present invention,
Other thermoplastic polymers and thermoplastic elastomers may also be included.

Since the polyacetal resin composition of the present invention is excellent in hydrolysis resistance, it can be used in a wide range of applications such as electric / electronic parts, machine / mechanical parts and the like.

[0029]

EXAMPLES The effects of the present invention will be described below with reference to examples. All percentages and parts in the examples are by weight.

Molding: Cylinder temperature 200 ° C., mold temperature 70 ° C. using an injection molding machine having an injection capacity of 5 ounces.
And the molding cycle was set to 25 seconds, and ASTM No. 1 dumbbell tensile test piece was injection molded. Hydrolysis resistance test: The obtained tensile test piece and ion-exchanged water were put into a pressure autoclave and heated at 130 ° C for 20 days. did.

Mechanical Properties: Using the test pieces obtained by the above injection molding according to the ASTM D-638 method, the tensile strength retention rate of the molded product before the hydrolysis test and the molded product after the hydrolysis test, And the tensile elongation at break retention was measured.

Color change of molded product: YI value was measured by a color machine using the molded product before and after the hydrolysis resistance test.

Changes in surface appearance of molded products: Changes in surface appearance of molded products before and after the hydrolysis resistance test were visually observed and evaluated according to the following criteria.

Criteria for Surface Appearance ○: No cracks are found at all Δ: Shallow cracks are found in some places ×: Cracks are found on the entire surface

Reference Example 1 Method for Producing Polyoxymethylene Copolymer Trioxane 3 was added to a 3 l kneader having two Σ type stirring blades.
000 g, 90 ml of 1,3-dioxolane, and 15 ml of benzene containing 0.3 g of boron trifluoride / diethyl etherate were added, and the mixture was stirred at 65 ° C. and 40 rpm. After about 1 minute, the reaction started and the internal sound increased. About 10
Although the temperature rose to 0 ° C, stirring was continued for 8 minutes. A powdery polymer was obtained by grinding the reaction mixture. This polymer has a melting point of 168 ° C. and a crystallization temperature of 147.
It was ℃. The reaction product was permeated into an aqueous ammonia solution and stirred. The polymer was then washed with water and dried under vacuum at 120 ° C. Next, as a heat resistance stabilizer, 0.5% by weight of pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenylpropionate] (manufactured by Ciba-Geigy). "Irganox" (1010) was added, the temperature was raised to 210 ° C in 10 minutes, and then the same temperature, 3
Stirred at 0 rpm for 20 minutes. The polymer obtained by this method is designated as A-1.

Reference Example 2 Method for Producing Reaction Product of Hindered Amine Compound and Boron Trifluoride Catalyst Bis (2,2,6,6-
Tetramethyl-4-piperidinyl) sebacate (0.2
mol) in a benzene solution (100 ml), while slowly cooling with an ice bath, boron trifluoride diethyl etherate (0.2 mol) is slowly added with a dropping funnel, and after stirring for 10 minutes with a magnetic stirrer, the reaction solution is filtered. The precipitate was collected and vacuum dried at room temperature. The reaction product of the hindered amine compound and the boron trifluoride-based catalyst is designated as B-1.

Similarly, using the hindered amine compound and the boron trifluoride-based catalyst shown in Table 1, reaction products B2 to 4 of the hindered amine compound and the boron trifluoride-based catalyst were synthesized in a predetermined molar number. Further, instead of the hindered amine compound, triphenylphosphine and triethylamine were used, and C1 and 2 were synthesized with a predetermined molar number of charges.

[0038]

[Table 1]

Examples 1 to 5 A-1 produced in Reference Example 1 as a polyacetal resin,
Alternatively, using DURACON M90 (manufactured by Polyplastics Co., Ltd.) (A-2), reaction products B1 to B4 of various hindered amine compounds synthesized in Reference Example 2 and boron trifluoride
After dry blending in the ratio shown in Table 2, 20 mmφ
Using a single-screw extruder having a screw of 1., melt-kneading was performed at a temperature of 190 ° C., and then pelletizing was performed to prepare a pelletized composition. Next, various test pieces were injection-molded using this pellet, and a hydrolysis resistance test was conducted. The tensile strength before and after the hydrolysis resistance test was measured, and the change in color of the molded product and the change in surface appearance were observed. The results are shown in Table 2.

Example 6 A reaction product of a hindered amine compound and a boron trifluoride-based catalyst was melt-kneaded in the same manner as in Example except that a homopolymer type Delrin 500NC10 (A-3) was used as the polyacetal resin. , Evaluated. The results are shown in Table 2.

Comparative Examples 1 to 6 Triphenylphosphine synthesized in Reference Example 1 as shown in Table 2 as in Example 1 or the reaction product of triethylamine and a boron trifluoride catalyst was melt-kneaded and evaluated. I went. Further, in Comparative Example 5, only the hindered amine compound was melt-kneaded instead of the reaction product of the hindered amine compound and the boron trifluoride-based catalyst. Bis (2,2,6,6-tetramethyl-4- as a hindered amine compound
Piperidinyl) sebacate was used. Further, in Comparative Example 6, homopolymer type Delrin 500NC10 was used as the polyacetal resin. The results are shown in Table 2.

From Table 2, it is clear that the composition of the present invention has excellent hydrolysis resistance.

[0043]

[Table 2]

Appearance of molded product ◯: No cracks are observed at all Δ: Shallow cracks are generated at some places ×: Cracks are generated on the entire surface *: All test pieces are decomposed and cannot be measured

[0045]

The polyacetal resin composition of the present invention is
Due to its excellent resistance to hydrolysis, it can be used in a wide range of applications such as electrical and electronic parts, machinery and mechanical parts.

Claims (1)

[Claims] 1. A polyacetal resin having the following general formula: (In the formula, R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, and even if they are the same, May be different from each other, n is an integer of 1 or more, and R ⁶ is an n-valent organic residue.) A polyacetal containing a reaction product of a hindered amine compound and a boron trifluoride-based catalyst. Resin composition.