JP2005162909A - Polyacetal resin composition and molded product composed thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin composition having excellent thermal stability, and generating a reduced amount of formaldehyde from a pellet and a molded product. <P>SOLUTION: The polyacetal resin composition is obtained by compounding (A) 100 pts. wt. polyacetal resin, (B) 0.01-5 pts. wt. hydrazide compound containing an aromatic group and (C) 0.01-5 pts. wt. sterically hindered phenol. The resin composition is suitable for applications as an interior component and a building material for an automobile and a house, and can improve the working condition at molding processing and reduce the mold staining. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyacetal resin composition and a molded article comprising the same. Specifically, the present invention relates to a polyacetal resin composition excellent in thermal stability and suppressed in the amount of formaldehyde generated from pellets and molded articles, and a molded article comprising the same.

Polyacetal resin is widely used as an engineering plastic having balanced mechanical properties and good self-lubricating properties and electrical properties in various mechanical and electrical components.
However, since the main raw material of the monomer in the polyacetal resin composition is formaldehyde, formaldehyde is generated in a very small amount due to a slight thermal decomposition reaction in the heat history during polymerization or processing of the resin. It pollutes the mold and worsens the work (hygiene) environment. In recent years, sick house syndrome and the like due to formaldehyde generated from the final product has been a problem. The indoor formaldehyde concentration guideline value from the Ministry of Health, Labor and Welfare is defined as 0.08 ppm, and as a measure against sick house syndrome, it is required to further reduce the amount of formaldehyde generated from the current level. For this purpose, a polyacetal resin composition having a low formaldehyde generation amount is desirable.

Conventionally, in order to suppress the amount of formaldehyde generated in pellets and molded articles made of a polyacetal resin composition, methods for blending various additives into the polyacetal resin have been proposed. For example, a melamine-formaldehyde polymer (Patent Document 1), a polyamine reactant obtained by further reacting a reaction product of polyamine and cyanuric chloride with ammonia or a derivative thereof (Patent Document 2), dicyandiamide (Patent Document 3), silane Compound (patent document 4), nitrogen-containing compound-borate (patent document 5), glyoxydiureide compound (patent document 6), urea derivative and / or amidine derivative (patent document 7), phenols and basic nitrogen Examples include condensates of containing compounds and aldehydes (Patent Document 8), triazine ring-containing spiro compounds (Patent Document 9), and the like.
In addition, a strong protonic acid such as trifluoromethanesulfonic acid is used as a catalyst for polymerization of polyacetal resin to suppress the amount of formaldehyde generated (Patent Document 10), and adipic acid dihydrazide or 1,2 as an adsorbent for formaldehyde. Aliphatic dihydrazides such as 3,4-butanetetracarboxylic acid hydrazide (Patent Document 11) have also been reported. However, these have problems such as insufficient suppression of formaldehyde generation and deterioration of physical properties of molded products, and there is a demand for polyacetal resin compositions and molded products in which generation of formaldehyde is further suppressed.

JP-A-5-271516 JP-A-7-207118 JP-A-8-208946 JP-A-9-235447 JP 10-36630 A Japanese Patent Laid-Open No. 10-182928 JP 2000-34417 A JP 2002-212384 A JP2003-113289A JP 2000-86738 A Japanese Patent Laid-Open No. 6-80619

  An object of the present invention is to provide a polyacetal resin composition that is excellent in thermal stability and that significantly reduces the amount of formaldehyde generated from a product.

  As a result of intensive studies to solve the above problems, the present inventors have reduced the amount of formaldehyde generated from pellets and molded products by blending an aromatic hydrazide compound and a sterically hindered phenol into a polyacetal resin. The inventors have found that it can be remarkably suppressed and have reached the present invention. That is, the gist of the present invention is that (A) 0.01 to 5 parts by weight of a hydrazide compound containing an aromatic group and (C) sterically hindered phenol 0.01 to 5 parts per 100 parts by weight of the polyacetal resin. It exists in the polyacetal resin composition characterized by mix | blending a weight part, and the molded article which consists of this resin composition.

  The polyacetal resin composition obtained in the present invention is excellent in thermal stability, suppresses the generation of formaldehyde during molding processing, improves the working environment, reduces mold contamination, etc. Therefore, it is extremely useful as a material for automobile interior parts, building material parts used in houses and schools, and electrical parts as a countermeasure against so-called sick house syndrome.

Hereinafter, the present invention will be described in detail.
The polyacetal resin (A) used in the present invention includes an acetal homopolymer having an oxymethylene group (—CH ₂ O—) as a main structural unit, and a copolymer containing at least one structural unit other than the oxymethylene group ( Including block polymers), and terpolymers. The polyacetal resin may have not only a linear structure but also a branched or crosslinked structure. As structural units other than the oxymethylene group, an oxyethylene group (—CH ₂ CH ₂ O—), an oxypropylene group (—CH ₂ CH ₂ CH ₂ O—), an oxybutylene group (—CH ₂ CH ₂ CH ₂ CH). ₂ O-) and other oxyalkylene groups having 2 to 4 carbon atoms are exemplified, and among them, an oxyethylene group is preferable. The content of the oxyalkylene structural unit having 2 or more carbon atoms is preferably from 0.1 to 20% by weight.

The polyacetal resin which has an oxymethylene group (—CH ₂ O—) and an oxyalkylene group having 2 to 4 carbon atoms as a constituent unit is an oxymethylene group such as formaldehyde trimer (trioxane) or tetramer (tetraoxane). It is produced by copolymerizing a cyclic oligomer and a cyclic oligomer containing an oxyalkylene group having 2 to 4 carbon atoms such as ethylene oxide, 1,3-dioxolane, 1,3,6-trioxocan, 1,3-dioxepane. Can do. Among them, a copolymer of cyclic oligomer such as trioxane or tetraoxane and ethylene oxide or 1,3-dioxolane is preferable. In particular, a copolymer of trioxane and 1,3-dioxolane is more preferable.

  Specific examples of the (B) hydrazide compound used in the present invention include isophthalic acid dihydrazide, terephthalic acid dihydrazide, 1,5-naphthalenedicarbohydrazide, 1,8-naphthalenedicarbohydrazide, and 2,6-naphthalenedicarbohydrate. Hydrazide, salicylic acid hydrazide, 3-hydroxy-2-naphthoic acid hydrazide, 1,5-diphenylcarbonohydrazide, p-toluenesulfonyl hydrazide, 2,4-toluenedisulfonyl hydrazide, aminobenzhydrazide, 4-pyridinecarboxylic acid hydrazide, It is a compound having an aromatic group and a hydrazino group such as 4,4′-oxybisbenzenesulfonyl hydrazide. In the present invention, among the above hydrazide compounds, dihydrazide compounds are preferable, and dihydrazide compounds having a structure represented by the following general formula (1) are particularly preferable.

Examples of the compound having the structure of the formula (1) include 1,5-naphthalenedicarbohydrazide, 1,8-naphthalenedicarbohydrazide, 2,6-naphthalenedicarbohydrazide and the like, and particularly 2,6-naphthalenedi. Carbohydrazide is preferably used.
The said aromatic hydrazide compound may be used independently and may be used in mixture of 2 or more types.

  The (C) sterically hindered phenol (hindered phenol) used in the present invention basically has a structure having a substituent at the ortho position of the phenolic hydroxyl group as represented by the following general formula (2). A compound having at least one in the inside.

(In General Formula (2), R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group. Further, an arbitrary substituent may be present at the meta position with respect to the hydroxy group. ).

  Specific examples of the (C) sterically hindered phenol having the structure of the formula (2) include, for example, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), 4,4′-methylene- Bis (2,6-di-t-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,5- Di-t-butyl-4-hydroxybenzyldimethylamine, stearyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, 2 , 6,7-trioxa-1-phospha-bicyclo [2,2,2] -oct-4-yl-methyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate, 3,5-di − -Butyl-4-hydroxyphenyl-3,5-distearyl-thiotriazylamine, 2- (2-hydroxy-3,5-di-t-butylphenyl) -5-chlorobenzotriazole, 2,6-di -T-butyl-4-hydroxymethylphenol, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, N , N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), octadecyl-3- (3,5-di-butyl-4-hydroxyphenyl) propionate, 1, 6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-dimethyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5- Methyl-4-hydroxyphenyl) propionate] triethylene glycol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thiodiethyl-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate] and the like. Among these, a compound having at least one structure represented by the following general formula (3) is particularly preferable. .

(In general formula (3), R ₁ and R ₂ have the same meaning as in general formula (2)).

  Specific examples of the compound having the structure of the general formula (3) include N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), Octadecyl-3- (3,5-di-butyl-4-hydroxyphenyl) propionate, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], Pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-dimethyl-4-hydroxyphenyl) propionate], Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], triethylene glycol Bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thiodiethyl-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate] and the like.

  Further, among these, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-dimethyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- ( 3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2′- Thiodiethyl-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

  The composition of the present invention contains the above (A), (B) and (C) as essential components, but preferably further contains (D) an amino-substituted triazine compound. The (D) amino-substituted triazine compound used in the present invention is basically a substituted triazine having a structure represented by the following general formula (4), or an initial polycondensate of the amino-substituted triazine and formaldehyde. It is.

(In the general formula (4), R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, halogen atom, hydroxyl group, mercapto group, alkyl group, alkenyl group, aralkyl group, aryl group, cycloalkyl group, Represents an amino group or a substituted amino group, and at least one of R _{3 to} R ₅ represents an amino group or a substituted amino group.

  Specific examples of the amino-substituted triazine compound include, for example, guanamine, melamine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N-diallylmelamine, N, N ′, N ″ -triphenylmelamine N, N ′, N ″ -trimethylolmelamine, benzoguanamine, 2,4-diamino-6-methyl-sym-triazine, 2,4-diamino-6-butyl-sym-triazine, 2,4-diamino-6 -Benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, ameline (N, N, N ′, N′— Tiger cyanoethyl benzoguanamine). Examples of the initial polycondensate of the amino-substituted triazine compound and formaldehyde, melamine - include initial polycondensate of the amino-substituted triazines with formaldehyde, such as formaldehyde resins. Among these, melamine, methylol melamine, benzoguanamine, and a water-soluble melamine-formaldehyde resin are particularly preferable.

  The composition of the present invention preferably contains (E) at least one metal-containing compound selected from alkali metal or alkaline earth metal hydroxides, inorganic acid salts, and alkoxides. Examples of the metal-containing compound (E) used in the present invention include alkali metal hydroxides such as sodium and potassium, or alkaline earth metal hydroxides such as calcium and magnesium, and carbonates, phosphates, and silicic acids of these metals. Examples thereof include inorganic acid salts such as salts and borates, and alkoxides such as methoxides and ethoxides of these metals. As the component (E) used in the present invention, an alkaline earth metal compound is particularly preferable, and specifically, calcium hydroxide, magnesium hydroxide, calcium carbonate, and magnesium carbonate are preferable.

  The resin composition of the present invention contains (B) and (C) components, preferably (D) and (E) components in a specific quantitative ratio, thereby reducing thermal stability and reducing the amount of formaldehyde generated. Balance can be achieved. The amount of the (B) hydrazide compound in the resin composition of the present invention is 0.01 to 5 parts by weight, preferably 0.03 to 4 parts by weight, more preferably 0.05 to 3 parts per 100 parts by weight of the polyacetal resin. Parts by weight. The amount of (C) sterically hindered phenol is 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the polyacetal resin. (D) The amount of the amino-substituted triazine compound is 0.01 to 7 parts by weight, preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the polyacetal resin. (E) The amount of the metal-containing compound is 0.004 to 5 parts by weight, preferably 0.005 to 5 parts by weight with respect to 100 parts by weight of the polyacetal resin.

  In addition to the above components, the polyacetal resin composition of the present invention can contain known additives and / or fillers as long as the original purpose is not impaired. Examples of the additive include a lubricant, an antistatic agent, an ultraviolet absorber, and a light stabilizer. Examples of the filler include glass fiber, glass flake, glass bead, talc, mica, calcium carbonate, potassium titanate whisker, and the like. Further, pigments and dyes can be added to achieve a desired color.

  The production method of the polyacetal resin composition of the present invention is not particularly limited, and is prepared by mixing and kneading the above components (A) to (C) and other components added as necessary. Can do. The mixing / kneading method is not particularly limited, and includes a method using a conventionally known mixing / kneading apparatus. The kneading is preferably performed at a temperature equal to or higher than the temperature at which the polyacetal resin melts.

  Specifically, for example, for (A) polyacetal resin, (B) hydrazide compound, (C) sterically hindered phenol, (D) amino-substituted triazine compound if necessary, and (E) if necessary. Add the metal-containing compound in the specified amount at the same time, add other resin additives as necessary, mix with a tumbler type blender, etc., and melt the resulting mixture with a single or twin screw extruder A polyacetal resin composition having a desired composition can be obtained by kneading, extruding into a strand, and pelletizing.

  The resin composition of the present invention can be molded according to a known polyacetal resin molding method. As a molded article made of the resin composition of the present invention, it is known as an application of polyacetal resin such as materials such as pellets, round bars, thick plates, sheets, tubes, various containers, machinery, electricity, automobiles, building materials, and other various parts. There are various products.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not restrict | limited to the specific example shown below, unless the summary is exceeded.
First, materials and measurement methods used in Examples and Comparative Examples are shown below.

(1) Polyacetal resin: Acetal copolymer using 4.2% by weight of 1,3-dioxolane as a comonomer based on the resin, melt index (10.5 g / 10 min).
(2) Hydrazide compound-1: 2,6-naphthalenedicarbohydrazide (Formula (5)).

(3) Hydrazide compound-2: Isophthalic acid dihydrazide.
(4) Hydrazide compound-3: adipic acid dihydrazide.

(5) Sterically hindered phenol: triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], manufactured by Ciba Specialty Chemicals, Inc., trade name “Irganox 245 "

(6) Amino-substituted triazine compound: melamine.
(7) Metal-containing compound: magnesium hydroxide.

The physical properties were evaluated as described below.
(A) Formaldehyde amount: A 100 mm × 40 mm × 2 mm flat plate was molded at a cylinder temperature of 215 ° C. using a PS-40E5ASE molding machine manufactured by Nissei Plastic Industry Co., Ltd. -Measured according to the method described in (Quantification of Formaldehyde Emission by Revised Flask Method).
(i) Put 50 ml of distilled water in a polyethylene container, close the lid with the test piece suspended, and heat in a sealed state at 60 ° C. for 3 hours.
(ii) After leaving at room temperature for 60 minutes, the test piece is taken out.
(iii) The formaldehyde concentration absorbed in the distilled water in the polyethylene container is measured by the acetylacetone method using a UV spectrometer.

(B) Thermal stability: Using a PS-40E5ASE molding machine manufactured by Nissei Plastic Industrial Co., Ltd., a 100 mm × 40 mm × 2 mm flat plate was molded at a cylinder temperature of 215 ° C. for 10 minutes, and the molding stability during residence was as follows. The properties (colorability, presence or absence of silver generation, etc.) were evaluated.
A: Thermal stability is very good.
○: Thermal stability is good.
Δ: Thermal stability is normal.
X: Thermal stability is poor.

(C) Mold contamination: Sumitomo Heavy Industries Co., Ltd. mini mat M8 / 7A molding machine is used, and a drop mold is used to continuously mold 500 shots at a molding temperature of 230 ° C and a mold temperature of 35 ° C. The presence or absence of deposits on the rear mold was observed and evaluated according to the following criteria.
A: Very little deposit on the mold B: A little deposit on the mold B: A lot of deposit on the mold
X: There are very many deposits on the mold.

[Examples 1-8, Comparative Examples 1-4]
With respect to 100 parts by weight of the polyacetal resin, each component was weighed according to the formulation shown in Tables 1 and 2 below, and mixed by a tumbler type blender. Next, the obtained mixture was melt-kneaded and pelletized in a 40 mmφ single-screw extruder (manufactured by Tanabe Plastics Co., Ltd., model: VS-40) at a cylinder temperature of 200 ° C. and a discharge rate of 13 kg / hr, to obtain a desired polyacetal. After obtaining the resin composition, the above-mentioned various test pieces were molded by injection molding, and the amount of formaldehyde generated, thermal stability, and mold adhesion were measured. The results are shown in Tables 1 and 2.
The amount of generated formaldehyde was displayed as a relative value when the value of Comparative Example 1 was used as the standard (1.00).

Claims (6)

  (A) To 100 parts by weight of a polyacetal resin, (B) 0.01 to 5 parts by weight of a hydrazide compound containing an aromatic group and (C) 0.01 to 5 parts by weight of a sterically hindered phenol are blended. A polyacetal resin composition characterized by the above.   (B) The polyacetal resin composition according to claim 1, wherein the hydrazide compound is a dihydrazide compound. The polyacetal resin composition according to claim 1 or 2, wherein the (B) hydrazide compound is at least one selected from naphthalenedicarbohydrazide compounds represented by the following general formula (1).
  The polyacetal resin composition according to any one of claims 1 to 3, wherein 0.01 to 7 parts by weight of (D) an amino-substituted triazine compound is further blended with 100 parts by weight of (A) polyacetal resin.   (A) With respect to 100 parts by weight of the polyacetal resin, 0.004 to 5 parts by weight of at least one metal-containing compound selected from (E) a hydroxide, an inorganic acid salt or an alkoxide of an alkali metal or alkaline earth metal The polyacetal resin composition according to any one of claims 1 to 4, which is blended.   A molded article comprising the polyacetal resin composition according to any one of claims 1 to 5.