JPH03128911A - Stabilized polyacetal resin molding and its preparation - Google Patents

Abstract

PURPOSE:To prepare a trioxane copolymer molding contg. a very low amt. of unstable terminal parts in the polymer molecule by copolymerizing trioxane with a cyclic ether or a cyclic formal in the presence of a terminal-blocking agent and a cation polymn. catalyst, treating the resulting copolymer in the form of fine particles with a base, and drying the copolymer in an inert atmosphere. CONSTITUTION:Trioxane is copolymerized with a cyclic ether or a cyclic formal in the presence of a terminal-blocking agent of the general formula: R1OCH2OR2 (wherein R1 and R2 are each 1-10C alkyl and may be the same or different) and a cation polymn. catalyst. The resulting copolymer in the form of fine particles is treated with a base and dried in an inert atmosphere. Thus, before a terminal-stabilizing treatment is conducted, a stabilized trioxane copolymer molding contg. unstable terminal parts in the polymer molecule of lower than 1% is obtd. The copolymer molding is then subjected to the terminal-stabilizing treatment in the presence of a hydrolyzing agent such as water, usually on an extruder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a stabilized polyacecool resin molded article and a method for producing the same.

More specifically, the present invention relates to a molded trioxane copolymer having a high stabilization rate after polymerization and a method for producing the same.

(Prior Art) It is well known to copolymerize trioquinone and ethylene oxide or butanediol formal to obtain a polyacetal resin.

For example, in Japanese Patent Publication No. 36-14640, trioxane and ethylene oxide or dioxolane, 1.4-
Copolymerization with cyclic ethers or cyclic formals such as butanediol formals is disclosed. In the case of this copolymerization, it is also well known to use methicul, butyral, etc. as molecular weight regulators.

However, the copolymer obtained in this way has many unstable parts and cannot be used as is, so efforts are being made to remove the unstable parts. For example,
Publication No. M-29 proposes heating a copolymer in a solvent such as water in the presence of a base to hydrolyze unstable terminal portions.

Hydrolysis of these unstable regions stabilizes the polymer, but much polymer loss is unavoidable. Typically, there will be a polymer loss of 5-10% by weight.

(Problem to be solved by the invention) Conventionally, by hydrolysis of the unstable part of the polymer,
Considering that there is a polymer loss of 10% by weight, the present inventor found that the polymer loss could be reduced by first examining the polymerization conditions (Japanese Patent Laid-Open No. 57-14141).
Publication No. 8).

Furthermore, the present inventor found that the particle size is important for the deactivation of the polymerization catalyst (Japanese Patent Application Laid-Open No. 5E138713).
.

However, even when these methods are adopted, the unstable portion of the polymer is still 1% or more.

Polyacecool resins and their production that have less than 1% unstable parts are desired.

(Means for Solving the Problems) As a result of intensive study based on the above situation, the inventor has determined that
We succeeded in obtaining a trioxane copolymer molded article having an unstable portion of less than 1%.

That is, the present invention is;
A copolymer mainly composed of trioxane and cyclic ether or cyclic formal that has been subjected to catalyst deactivation treatment with a base, characterized in that the unstable portion at the polymer terminal before terminal stabilization treatment is less than 1%. 3~ It is a stabilized trioxane copolymer molded body, and also contains trioxane and a cyclic ether or a cyclic formal, -Sailor: % formula % [1] (However, R1 and R2 are , the same or different alkyl groups having 1 to 10 carbon atoms) are polymerized using a cationic polymerization catalyst in the presence of an end-capping agent, and then the obtained copolymer is treated in the form of fine particles with a base, A method for producing a stabilized trioxane copolymer molded article having an unstable portion at the polymer end of less than 1% before terminal stabilization treatment, which comprises drying.

The present invention will be specifically explained below.

Before being subjected to such terminal stabilization step, the destabilizing portion is
% of trioxane copolymers was previously unknown.

The existence of such trioxane copolymers was first revealed by the present invention.

Next, a method for producing such a trioxane copolymer will be specifically explained.

■ First, using highly purified trioxane and using cyclic ether or cyclic formal as a copolymerization component, preferably in a hydrocarbon solvent, -Sailor: % formula % [1 (where R1 and R2 are , which represents an alkyl group having 1 to 10 carbon atoms.) is polymerized using a polymerization catalyst, preferably a cationic catalyst, in the presence of an end-capping agent, to produce a trioxane copolymer, and the particle size of the polymer is 1fflL11. Contact with the base in the form of fine particles of the following, preferably 0.5 m or less, more preferably Q, 3 mm or less, without contacting with air, and in an atmosphere of 110'C or more under an inert gas in continuous operation. It is advantageously produced by drying in a vacuum.

Further, embodiments of the present invention will be explained in detail.

The trioxane used in the present invention is preferably highly purified. For example, impurities such as water and formic acid are
pm or less is desirable.

As a method for purifying trioxane, for example, the method described in Japanese Patent Publication No. 10513/1988 by the present inventor can be adopted.

Next, examples of cyclic ethers and cyclic formals used as copolymerization components include ethylene oxide, 1.3
-dioxolane, 14-butanediol formal, diethylene glycol formal, trioxepane and the like. Among these, ethylene oxide, 1,4-butanediol formal, and diethylene glycol formal are preferred copolymerization components.

The ratio of the copolymer components is not particularly limited, but is 0.
It is preferably 5 to 10 mol%, particularly preferably 2 to 6 mol%.

The polymerization catalyst that can be used is preferably a cationic catalyst. Specific examples of cationic polymerization catalysts include tin tetrachloride, titanium tetrachloride; boron fluoride and boron trifluoride coordination compounds such as boron trifluoride diethyl ether and boron trifluoride dibutyl ether; Inorganic acids and organic acids such as phosphorus, trifluoromethyl sulfuric acid, dichloroacetic acid, and P-toluenesulfonic acid; alkyl metals such as diethylzinc and triethylargonium; in particular, boron trifluoride dibutyl ether It is a suitable cationic polymerization catalyst.

These polymerization catalysts may be used alone or in combination of two or more.

Further, the amount of the polymerization catalyst used is not particularly limited, but is 5 x 10-'mol/m based on the monomers used.

Desirably 1 or less.

The terminal capping agent used in the present invention is represented by the following formula: %[1 (wherein, R1 and R2 are the same or different alkyl groups having 1 to 10 carbon atoms.) Preferred examples include methicul and butyral. Furthermore, any other acetals, such as acetals obtained by heating formalin and various alcohols, can also be used as the terminal capping agent.

The amount of the terminal capping agent used is not particularly limited, but is generally preferably 1/1000 to 1150, particularly preferably 1/700 to 1/100, per mole of monomer.
is the amount of

In the present invention, the copolymerization of trioxane and cyclic ether or cyclic formal is carried out without a solvent or in an organic solvent, particularly a hydrocarbon solvent.

Hydrocarbon solvents that can be used in the present invention include n
- Aliphatic hydrocarbons such as pentane, n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and cyclopentane; aromatic hydrocarbons such as henzene, toluene and xylene; and those such as carbon tetrachloride and chloroheptane. Examples include hydrocarbon halides, which can be used alone or in combination.

A preferred polymerization solvent is cyclohexane.

The copolymerization of the present invention is carried out at 20-160°C, preferably at 50-160°C.
The reaction temperature is 120°C, more preferably 80 to 110°C.

A preferred method for carrying out the above copolymerization is a method using a self-cleaning continuous negoo.

Examples of kneaders used include Coney Goo manufactured by Busu Kogyo■ and KR manufactured by Kuriki Iron Works.
Examples include a C kneader and a ZSK twin screw extruder manufactured by Uniluna.

In the present invention, the catalyst in the polymer after copolymerization is brought into contact with a base to be deactivated. At that time, the diameter of the polymer particles contacted with the base as described in JP-A-58-38713 by the present inventors is 1 ffl [1 or less, preferably 0. 5mm or less, more preferably 0.3m
It is important to carry out the process in the form of fine particles with a particle diameter of m or less.

The base used for deactivating the polymerization catalyst in the present invention is not particularly limited, and inorganic bases and organic bases can be used, but bases such as calcium hydroxide and organic ammoniums such as triethylamine are preferably used. .

There is no particular limit to the amount of base used, but it is between 2 and 20% of the catalyst amount.
It is 0 times the mole, preferably 10 to 100 times the mole.

Here, the copolymer particles obtained by copolymerization in a self-cleaning Ni-Goo are pulverized into fine particles of 1 K or less using a known pulverizer or the like before being subjected to deactivation treatment with a base. It is necessary to Unless it is made into fine particles by this pulverization treatment, the stabilized trioxane copolymer molded article intended in the present invention cannot be obtained.

In addition, what is important in the present invention is that the polymer after polymerization is contacted with a base without contacting with air, and then continuously dried at an ambient temperature of 110°C or higher in an inert gas atmosphere. It is to be done.

Here, the ambient temperature means the temperature of the gas in contact with the polymer.

In this way, a finely divided polymer molded article containing less than 1% of unstable terminal parts can be obtained.

This polymer molded article is subjected to the next terminal stabilization step.

The terminal stabilization step is usually carried out in an extruder in the presence of a hydrolyzing agent such as water.

In the present invention, the polymer molded article having less than 1% of terminal unstable parts before being subjected to the terminal stabilization step is a substance that has not existed in the world so far. The final product obtained after subjecting such a polymer molding to a stabilization step exhibits very good thermal stability.

Although the molecular weight of the copolymer of the present invention is not particularly limited, it preferably has a molecular weight of 10,000 to 100,000, particularly preferably 25,000 to 70,000.

The shape of the copolymer molded article of the present invention may be any shape such as pellet, powder, or particle.

The stabilized copolymer molded article of the present invention may contain, if desired, various additives conventionally used in polyacecool resins, such as antioxidants, ultraviolet absorbers, lubricants, lubricants, etc.
Pigments, fillers, reinforcing agents and flame retardants can be added alone or in various combinations.

The copolymer molded article of the present invention can be made into various molded articles by employing conventional molding means such as injection molding or extrusion molding.

(Examples) Hereinafter, the present invention will be explained in detail using Examples, but these are not intended to limit the scope of the present invention.

Example 1 Boron trifluoride dibutyl etherate was dissolved in cyclohexane at 3 x 1.0-5 mol % based on trioxane as a catalyst, and ethylene oxide was dissolved at 4 x 1.0-5 mol % based on trioxane.
A copolymer of trioxane and ethylene oxide is produced from a mixture with trioxane containing mol% using a twin-screw self-cleaning kneader.

However, as an end-blocking agent, methicool was added in advance in an amount of 1/300 molar ratio to trioxane. The copolymer is brought into contact with a 0.5% by weight aqueous triethylamine solution in a tank and stirred with a stirrer at 62°C for about 90 minutes. The proportion of the copolymer to the 0.5% by weight aqueous tri2-ethylamine solution is about 20% by weight. Simultaneously with the stirring, an aqueous triethylamine solution of the slurry-like copolymer was extracted from the bottom of the tank, and the copolymer was pulverized using a pulverizer. The slurry containing copolymer fine particles of approximately 0.4 mm or less is centrifuged, and the copolymer is separated from an aqueous triethylamine solution, washed with water, and then heated and dried at an ambient temperature of 125°C for approximately 3 hours under nitrogen flow. It was done.

The proportion of unstable parts in the obtained dried copolymer was determined.

To measure the unstable part, dry the polymer under vacuum for 22 hours.
Heat at 2'C for 50 minutes, measure the weight, and calculate the reduction rate with respect to the weight before heating.

The unstable portion of the polymer was 0.7%.

Furthermore, 3% by weight of water was added to the obtained polymer.
, 1-ethylamine was added in O,]% by weight, and the temperature was heated at 200°C.
The mixture was then applied to an extruder and volatile components were taken out from the vent section.

A transparent strand was obtained from the extruder nozzle.

This pellet was cut and had good thermal stability.

Comparative Example 1 The same operation as in Example I was performed except that the crusher was not used in Example 1. The unstable part of the polymer after drying is 6.
It was 1%.

To this polymer, 3% by weight of water and 0.1% by weight of triethylagon were added to the polymer, and the mixture was put into an extruder at 200°C, and volatile components were taken out from the hent section. A foamed strand was obtained from the extruder nozzle.

This pellet was cut and had poor thermal stability.

Example 2 The same operation as in Example 1 was carried out except that the copolymer fine particles were used to have a size of about 0.2 mm or less.

The unstable portion of the polymer after drying was 0.4%.

In addition, the strand from the extruder nozzle has good transparency,
Pellets with good thermal stability were obtained.

5 (Effects of the Invention) In the present invention, since the trioxane copolymer molded article has a structure in which the unstable portion at the polymer end is less than 1% before the terminal stabilization treatment, polymer loss due to the terminal stabilization treatment is reduced. It is possible to obtain a polyacetal resin molded article with a small amount of heat and good thermal stability.

In addition, in the present invention, the trioxane copolymer polymerized with a cationic polymerization catalyst in the presence of an acetal end-blocking agent was subjected to catalyst deactivation treatment with a base in the form of fine particles. A trioxane copolymer with stable parts of less than 1% is obtained.

6

Claims (2)

[Claims] (1) Polymerized with a cationic catalyst in the presence of an end-capping agent,
A copolymer mainly composed of trioxane and cyclic ether or cyclic formal that has been subjected to catalyst deactivation treatment with a base, characterized in that the unstable portion at the polymer terminal before terminal stabilization treatment is less than 1%. A stabilized trioxane copolymer molded article. (2) Trioxane and cyclic ether or cyclic formal are represented by the general formula: R_1OCH_2OR_2...[I] (However, R_1 and R_2 represent the same or different alkyl groups having 1 to 10 carbon atoms.) An end-stabilizing treatment characterized by polymerization using a cationic polymerization catalyst in the presence of an end-blocking agent, followed by treating the obtained copolymer in the form of fine particles with a base and drying in an inert atmosphere. A method for producing a stabilized trioxane copolymer molded article having less than 1% of unstable parts at the end of the polymer.