JP2011116905A - Polyacetal copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal copolymer having high heat stability and achieving remarkable stiffness. <P>SOLUTION: The polyacetal copolymer is obtained by copolymerization of (A) 100 pts.wt. of trioxane, (B) 0.1-30 pts.wt. of a cyclic ether compound which can be copolymerized with the trioxane, and (C) 0.005-20 pts.wt. of an allyl ether compound represented by structural formula, wherein R<SP>1</SP>represents 2-20C alkylene or substituted alkylene, or 2-20C polyalkylene oxide, R<SP>2</SP>is 1-12C alkyl, substituted alkyl, aryl, substituted aryl or halogen, n is an integer of 0-5, R<SP>2</SP>may be the same or different when n is ≥2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a polyacetal copolymer having high heat resistance and rigidity.

Polyacetal copolymer has excellent balance of mechanical properties, chemical resistance, slidability, etc. and is easy to process. As a typical engineering plastic, it can be used as electrical / electronic parts, automobile parts and other various machines. Widely used mainly in parts.

However, with the expansion of the field where polyacetal resins are used, there are cases where further improvement in rigidity and strength is required without impairing thermal stability. As means for improving the rigidity and creep resistance of the polyacetal resin composition as described above, a method of filling a polyacetal with a fibrous filler and a method of reducing the amount of comonomer in a polyacetal copolymer are known.

  Furthermore, in recent years, an example in which rigidity and creep resistance are improved by a polyacetal copolymer into which a branched structure is introduced by reacting a monofunctional glycidyl ether compound during polymerization has been disclosed (see Patent Document 1). However, according to the study by the present inventors, the effect of improving the rigidity of the modified polyacetal compound by this method is not always satisfactory.

  As a method for improving rigidity by modification, a polyacetal copolymer in which an aromatic functional group such as a phenyl group is introduced by reacting an aromatic glycidyl ether compound such as a phenyl group during polymerization is disclosed (patent) Reference 2). According to the study by the present inventors, it has been found that the thermal stability is remarkably lowered even though the rigidity improving effect is recognized by this method. Therefore, not only is stable production difficult, but the appearance defect of the molded product is remarkably impaired and the increase in odor is remarkably increased, which is not always satisfactory.

Japanese Patent No. 3926484 Japanese Patent No. 3926512

In view of the current situation, the present invention relates to a polyacetal copolymer that has high thermal stability and enables significant rigidity.

（式中、R¹はC₂〜C₂₀のアルキレン基若しくは置換アルキレン基又はC₂〜C₂₀のポリアルキレンオキシド基を示す。R²はC₁〜C₁₂のアルキル基、置換アルキル基、アリール基、置換アリール基又はハロゲンを示す。nは0〜5の整数であり、ｎが２以上の場合R²は同一でも異なっていても良い） As a result of intensive studies to solve the above problems, the present inventors have been able to maintain thermal stability by using a polyacetal copolymer into which a branched structure has been introduced by copolymerizing certain specific allyl ether compounds, In addition, the rigidity could be remarkably improved. That is, the present invention comprises (A) 100 parts by weight of trioxane, (B) 0.1 to 30 parts by weight of a cyclic ether compound copolymerizable with trioxane, (C) an allyl ether compound represented by the following structural formula: The present invention relates to a polyacetal copolymer obtained by copolymerizing 005 to 20 parts by weight.

(In the formula, R ¹ represents a C _{2 to} C ₂₀ alkylene group or substituted alkylene group or a C _{2 to} C ₂₀ polyalkylene oxide group. R ² represents a C _{1 to} C ₁₂ alkyl group, substituted alkyl group, aryl. A group, a substituted aryl group or a halogen, n is an integer of 0 to 5, and when n is 2 or more, R ² may be the same or different.

    According to the present invention, it is possible to provide an acetal copolymer whose rigidity is greatly improved while maintaining thermal stability.

As the polymerization method of the acetal copolymer in the present invention, a bulk polymerization method using substantially no solvent is suitable. This is a polymerization method using a monomer in a molten state. As the polymerization proceeds, the polymer is crystallized in the monomer mixture, and eventually the whole system is agglomerated and powdered to obtain a solid polymer. Is. The polymerization is carried out in the absence of oxygen, preferably in a nitrogen atmosphere.

Polymerization catalysts that can be used in the present invention include boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride, antimony pentafluoride and their coordination compounds, heteropoly Cationic active catalysts such as acids, isopolyacids, perfluoroalkyl sulfonic acids or their derivatives are known. It is also known to use two or more of these catalysts in combination. Among them, a compound containing boron trifluoride, or boron trifluoride hydrate and a coordination complex compound are particularly preferable. Boron trifluoride diethyl etherate and boron trifluoride dibutyl etherate, which are coordination complexes with ethers, are particularly preferred. The addition amount is generally 3.0 × 10 ^{−6 to} 2.0 × 10 ⁻⁴ wt%, preferably 8.0 ×, in terms of boron trifluoride with respect to trioxane as the main monomer. It is used in the range of 10 ^{−6 to} 8.0 × 10 ⁻⁵ wt%. In order to disperse these catalysts uniformly in the reaction system, it is preferable to use them diluted with an organic solvent that does not adversely influence the polymerization reaction. Examples of the organic solvent include ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and n-butyl ether, aromatic hydrocarbons such as benzene and toluene, aliphatic hydrocarbons such as n-hexane and cyclohexane, methylene dichloride and ethylene dichloride. And halogenated hydrocarbons.

The raw material monomer in the present invention is trioxane which is a cyclic trimer of formaldehyde as the component (A), and cyclic ether and / or cyclic formal which is a comonomer as the component (B). Specific examples of the comonomer include, for example, 1,3-dioxolane, 2-ethyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 2-butyl-1,3-dioxolane, 2,2-dimethyl- 1,3-dioxolane, 2-phenyl-2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 2,4-dimethyl-1,3-dioxolane, 2-ethyl-4-methyl- 1,3-dioxolane, 4,4-dimethyl-1,3-dioxolane, 4,5-dimethyl-1,3-dioxolane, 2,2,4-trimethyl-1,3-dioxolane, 4-hydroxymethyl-1 , 3-dioxolane, 4-butyloxymethyl-1,3-dioxolane, 4-phenoxymethyl-1,3-dioxolane, 4-chloromethyl-1,3-dioxolane 1,3-dioxabicyclo [3,4,0] nonane, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide, oxytane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, and 1,3-dioxepane Examples include oxepanes, oxocanes such as 1,3,6-trioxocane, and oxetanes. Of these, 1,3-dioxolane is particularly preferred.

The amount of the comonomer added is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 25 parts by weight with respect to 100 parts by weight of trioxane. When the amount of comonomer used is more than 30 parts by weight, the polymerization yield decreases, and when it is less than 0.1 parts by weight, the thermal stability decreases.

  The allyl ether compound as component (C) has an alkylbenzyl glycidyl ether such as allyl benzyl ether, 4-methoxyallyl benzyl ether, 2-methoxyallyl benzyl ether, and a benzyl skeleton such as 1,4-diallyloxymethylbenzene. Polyfunctional allyl ether is mentioned, and allyl benzyl ether is particularly preferable.

These allyl ether compounds are added in the range of 0.005 to 20 parts by weight per 100 parts by weight of trioxane. If it is less than this, the effect of improving the rigidity and strength is thin, and if it is more than this, not only the toughness is lowered, but also the productivity is lowered due to the reduced polymerization rate. Moreover, the preferable addition amount is 0.01-15 weight part, More preferably, it is 0.05-10 weight part.

  There is no restriction on the position at which the allyl ether compound is introduced. A method in which all of trioxane, a comonomer, a chain transfer agent, and a catalyst are combined together at the inlet of the polymerization machine and quickly introduced into the polymerization machine, or after mixing with one or more of trioxane, a comonomer, and a chain transfer agent in advance. It is possible to carry out a polymerization reaction by combining them with each other or by mixing them in advance with any one or more of a comonomer and a chain transfer agent and further including a catalyst and then combining them with trioxane.

Also in the polymerization method of the present invention, a chain transfer agent can be added to adjust the degree of polymerization of the acetal copolymer. Examples of chain transfer agents include carboxylic acids, carboxylic anhydrides, esters, amides, imides, phenols, acetal compounds, and the like, and phenol, 2,6-dimethylphenol, methylal, and polyacetal dimethoxide are particularly suitable. Used. Of these, methylal is most preferred, and it can be used alone or in the form of a solution. As the addition amount, it is usually used in the range of less than 2 × 10 ⁻¹ wt% as methylal with respect to the main monomer trioxane. When used in the form of a solution, examples of the solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated hydrocarbons such as methylene dichloride and ethylene dichloride. Can be mentioned.

For the deactivation after the polymerization reaction, a catalyst deactivator such as a trivalent organic phosphorus compound, an amine compound, an alkali metal or an alkaline earth metal hydroxide can be used. As the amine compound, primary, secondary, and tertiary aliphatic amines, aromatic amines, heterocyclic amines, hindered amines, and other known catalyst deactivators can be used. For example, ethylamine, diethylamine, triethylamine, mono-n-butylamine, di-n-butylamine, tri-n-butylamine, aniline, diphenylamine, pyridine, piperidine, morpholine and the like can be used. Of these, trivalent organophosphorus compounds and tertiary amines are particularly preferred, and triphenylphosphine is most preferred. As the addition amount is not particularly limited as long as it is an amount sufficient to deactivate the catalyst, the molar ratio to the catalyst, usually used in an amount of ^1.0 × 10 -1 ~1.0 × 10 ¹ Is done. When these catalyst deactivators are used in the form of a solution or suspension, the solvent used is not particularly limited, but water, alcohols, acetone, methyl ethyl ketone, hexane, cyclohexane, heptane, Various aliphatic and aromatic organic solvents such as benzene, toluene, xylene, methylene dichloride and ethylene dichloride can be used.

  After the polymerization and deactivation operations (the acetal copolymer before stabilization is referred to as “crude copolymer”), if necessary, washing the crude copolymer, separating and recovering unreacted monomers, drying, etc. In the present invention, a crude copolymer having a high yield and excellent thermal stability can be obtained, and therefore this step can be omitted.

Examples of the stabilization treatment include a method of removing the unstable portion by heating and melting the acetal copolymer obtained above. At this time, in addition to the hindered phenol compound and the amine-substituted triazine compound, any one or more of alkali or alkaline earth metal hydroxide, inorganic salt, carboxylate, etc. may be added. . Further, if necessary, general additives for thermoplastic resins, such as colorants such as dyes and pigments, lubricants, mold release agents, antistatic agents, ultraviolet absorbers, light stabilizers, surfactants, or One or more organic polymer materials, inorganic or organic fibrous, powdery, and plate-like fillers can be added.

Examples of the antioxidant include 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis-3- (3-t- Butyl-4-hydroxy-5-methylphenyl) propionate, pentaerythrityl-tetrakis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (6-t- Butyl-4-methylphenol), 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl] propionyloxy) -1,1-dimethylethyl} -2,4 , 8,10-tetraoxaspiro [5,5] undecane, N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionamide], 3,5-bis (1,1-dimethylethyl) -4-hindered phenols such as hydroxy benzenepropanoic acid 1,6-hexanediyl ester. These may be used alone or in combination of two or more.

The addition amount of these hindered phenol compounds is preferably 0.01 to 0.4 parts by weight, more preferably 0.005 to 0.3 parts by weight, with respect to 100 parts by weight of the polyacetal polymer.
In particular, since the allyl ether compound used in the present invention has a slight slight decrease in thermal stability, if it is less than this, the decrease in thermal stability becomes significant. Moreover, when there are more addition amounts than this, the physical property fall will arise.

Examples of the heat stabilizer include melamine, methylol melamine, guanamine, benzoguanamine, cyanoguanidine, N, N-diarylmelamine, melamine-formaldehyde condensate, urea, urea heat condensate synthesized by heating from urea, polyacryl Nitrogen-containing compounds such as amines, polyethyleneimines, polyacrylamides, polyamides, urethane compounds, and pyridine compounds are exemplified, and among these, melamine, methylol melamine, and melamine-formaldehyde condensates that are amine-substituted triazine compounds are more preferable. These may be used alone or in combination of two or more.

The addition amount of these amine-substituted triazines is preferably 0.0001 to 0.15 parts by weight and more preferably 0.005 to 0.10 parts by weight with respect to 100 parts by weight of the polyacetal polymer. If it is less than this, the viscosity drop during production will be remarkably increased, leading to a reduction in production, and the thermal stability will be significantly impaired when the colorant is compounded. If it is larger than this, a decrease in toughness is observed.

In addition, it is preferable to mix a metal-containing compound represented by a group consisting of an alkali metal or alkaline earth metal hydroxide, an inorganic acid salt, or an alkoxide as a heat stabilizer, such as sodium, potassium, calcium, magnesium, barium. And hydroxides, inorganic acid salts, alkoxides, and the like. Among these, calcium hydroxide, magnesium hydroxide, potassium hydroxide, calcium carbonate, and magnesium carbonate are most preferable. These may be used alone or in combination of two or more.

The amount of the metal-containing compound represented by the group consisting of the alkali metal or alkaline earth metal hydroxide, inorganic acid salt, or alkoxide is 0.001 to 5 with respect to 100 parts by weight of the polyacetal polymer. 0.0 part by weight is preferable, and 0.001 to 1.0 part by weight is more preferable.

In the present invention, hindered amine compounds, benzophenone compounds, benzotriazole compounds, aromatic benzoate compounds, cyanoacrylate compounds, oxalic acid anilide compounds, and the like may be added as weathering (light stabilizer) agents. The addition amount of these weathering agents is preferably 0.01 to 5 parts by weight and more preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the polyacetal copolymer.

A metal salt of a higher fatty acid may be added as a lubricant and a heat stabilizer to the polyacetal copolymer of the present invention. Although the metal salt of a higher fatty acid is not particularly limited, magnesium salts, calcium salts, barium salts, and the like of higher fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid, and 12-hydroxystearic acid are preferable.
The amount of the higher fatty acid metal salt added is preferably 0.0001 to 5 parts by weight, more preferably 0.0001 to 3 parts by weight, based on 100 parts by weight of the polyacetal polymer.

Moreover, it is preferable to mix | blend the higher fatty acid amide which has a C10 or more long chain, the fatty acid ester of a polyhydric alcohol, and paraffin wax as a mold release agent. The higher fatty acid amide having a long chain having 10 or more carbon atoms is not particularly limited, but examples thereof include stearic acid amide, ethylene bisstearamide, methylene bisstearamide, methylene bislauramide, palmitic acid amide, and oleic acid amide. be able to. Among these, ethylene bisstearamide, methylene bisstearamide, and methylene bislauramide are more preferable. Specific examples of fatty acid esters of polyhydric alcohol include glycerin, diglycerin, pentaerythritol, sorbitan, polyhydric alcohols such as ethylene glycol, diethylene glycol, trimethylol methane, trimethylol ethane, behenic acid, serotic acid, and montanic acid. And fatty acid esters such as laccellic acid and the like, and paraffin wax having a molecular weight of 1,000 to 2,000,000 is preferable. These may be used alone or in combination of two or more.

  The addition amount of these paraffin wax, higher fatty acid amide having a long chain having 10 or more carbon atoms and fatty acid ester of polyhydric alcohol is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of polyacetal polymer. -3 parts by weight is more preferred.

  A nucleating agent may be added to the polyacetal resin composition of the present invention for the purpose of improving moldability and shortening the molding cycle. The nucleating agent is not particularly limited, but boron nitride, hydrous magnesium silicate, three-dimensional crosslinked polyacetal and the like are more preferable.

  The amount of the nucleating agent added and blended in the present invention is preferably 0.0001 to 10.0 parts by weight and more preferably 0.001 to 5.0 parts by weight with respect to 100 parts by weight of the polyacetal polymer (component A). .

You may add a coumarin type | system | group fluorescent whitening agent and a benzoxazole type | system | group fluorescent whitening agent as a fluorescent whitening agent with respect to the polyacetal copolymer of this invention. The coumarin fluorescent whitening agent and the benzoxazole fluorescent whitening agent are not particularly limited, but 3- (4′-acetylaminophenyl) -7-acetylaminocoumarin, 3- (4′-carboxyphenyl) -4-methyl. -7-diethylaminocoumarin, 2,5-bis (5′-t-butylbenzoxazol-2′-yl) thiophene, 2,5-bis [5′-t-butylbenzoxazolyl (2)] Thiophene is preferred. The addition amount of these coumarin fluorescent brighteners and benzoxazole fluorescent brighteners is preferably 0.001 to 500 ppm, more preferably 0.01 to 100 ppm, based on the polyacetal polymer.

  Glass beads, mica, kaolin, silicon dioxide, clay, asbestos, silica, diatomaceous earth, graphite, molybdenum disulfide, carbon black, titanium oxide, glass fiber, milled fiber, potassium titanate fiber, boron fiber as fillers Carbon fiber, aramid fiber or the like may be added. The amount of these fillers is preferably 0.01 to 200 parts by weight and more preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the polyacetal polymer.

  The melt flow index (MI) value (190 ° C., load 2,160 g) of the polyacetal copolymer according to the present invention is usually 0.5 to 100 g / 10 min, preferably 1.0 to 70 g / 10 min.

  The polyacetal copolymer which has deactivated the polymerization catalyst can be sent to the subsequent stabilization step as it is, but if further purification is required, washing, separation and recovery of unreacted monomers, drying, etc. Can pass.

  In the present invention, these various stabilizers and additives are mixed with the polyacetal polymer in which the polymerization catalyst has been deactivated, and heated and melt-kneaded by a single-screw or twin-screw extruder, a twin-screw paddle type continuous mixer, or the like. Heat-stabilized. At this time, some of these various stabilizers or additives may be added separately after the thermal stabilization treatment, and water, alcohol, amine, etc. may be added during the thermal stabilization. .

    The method of blending and mixing these various stabilizers and additives with the polyacetal polymer that has deactivated the polymerization catalyst is not particularly limited, and any method that can be used industrially may be used. For example, after mixing each component with a blender such as a turnbull mixer or a Henschel mixer, a method of kneading with a single screw or twin screw extruder, a twin screw paddle type continuous mixer, a bumper mixer, a roll or the like is appropriately selected. . Each component is preferably dried before kneading.

    Examples and Comparative Examples of the present invention are shown below, but it goes without saying that the present invention is not limited to these. In addition, the term and measurement method in an Example and a comparative example are shown below.

Continuous reactor : It has an inner section with two overlapping circles, the inner section has a major axis of 20 cm, L / D of 7.2, and a pair of shafts in a long case with a jacket around it. , A continuous mixer in which each shaft is fitted with a large number of pseudo-triangular plates that mesh with each other, and the tip of the pseudo-triangular plate can clean the inner surface of the case and the surface of the counterpart pseudo-triangular plate.
Stopper mixer : An inner section with two overlapping circles, the inner section has a major axis of 12 cm, L / D of 7.2, and a pair of shafts in a long case with a jacket around it Equipped with a structure in which a number of screw-like blades are fitted in each shaft, and a stopper solution is injected from the supply port portion and continuously mixed with the polymerization product.
MI value (melting index) : Triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] (trade name: IRGA, manufactured by Ciba Geigy Co., Ltd.) with 100 parts by weight of the crude copolymer Knox 245) Add 0.3 parts by weight, 0.1 parts by weight of melamine, 0.05 parts by weight of magnesium hydroxide, mix, and then melt and knead in a lab plast mill at 220 ° C under a nitrogen stream for 20 minutes. After the treatment, the measurement was performed according to ASTM-D1238 (190 ° C., under a load of 2.16 kg). This MI value indicates that the lower the value, the higher the degree of polymerization of the crude copolymer.
Tensile test : A test piece was molded using an injection molding machine and measured according to the ISO 527-1,2 method.
Weight reduction rate by heating : Pellet weight reduction rate after the inside of the test tube containing the pellets was purged with nitrogen, kept under reduced pressure of 10 mmHg, and held at 222 ° C. for 2 hours.

<Examples 1-4, Comparative Examples 1-5>
As the continuous reaction apparatus, an acetal copolymer was produced using the above-mentioned two continuous reactors and a stopper mixer connected in series. A mixture of 90.0 kg / hr trioxane and 3.6 kg / hr 1,3-dioxolane from the inlet of the first reactor was mixed with a benzene solution of an allyl ether compound and methylal benzene under the conditions described in Table 1. A solution (25 wt%) and a benzene solution of boron trifluoride diethyl etherate (preparation concentration: 0.3 mol / kg) as a catalyst were added and immediately introduced into the reactor to carry out the reaction continuously. The first unit jacket temperature (polymerization temperature) was set to 85 ° C., and the second stage and terminator mixer jacket temperatures were set to 60 and 40 ° C., respectively. Also, from the inlet of the terminator mixer, triphenylphosphine twice the amount of the catalyst used was continuously supplied as a benzene solution (preparation concentration: 0.6 mol / kg) to stop the polymerization and pulverize. As a result, a crude copolymer was obtained. The polymerization yield of the crude copolymer obtained at this time was 98%. Next, to 100 parts by weight of the obtained crude copolymer, glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (manufactured by Ciba Specialty Chemicals, trade name; Irganox 245) ) 0.3 parts by weight and 0.05 parts by weight of melamine were added and premixed using a Henschel mixer. Thereafter, it was supplied to a vented twin-screw extruder, and melt-kneaded at 200 ° C. under reduced pressure of 21.3 kPa to be pelletized. Using the obtained pellets, a tensile test and a heating weight reduction rate were measured. The results are shown in Table 1.

Claims (2)

(A) 100 parts by weight of trioxane, (B) 0.1-30 parts by weight of a cyclic ether compound copolymerizable with trioxane, (C) 0.005-20 parts by weight of an allyl ether compound represented by the following structural formula A polyacetal copolymer obtained by copolymerization.

(In the formula, R ¹ represents a C _{2 to} C ₂₀ alkylene group or substituted alkylene group or a C _{2 to} C ₂₀ polyalkylene oxide group. R ² represents a C _{1 to} C ₁₂ alkyl group, substituted alkyl group, aryl. A group, a substituted aryl group or a halogen, n is an integer of 0 to 5, and when n is 2 or more, R ² may be the same or different. 2. The polyacetal copolymer according to claim 1, wherein the allyl ether compound is allyl benzyl ether.