JPH03265615A - Production of acetal block copolymer - Google Patents

Abstract

PURPOSE:To produce the title copolymer improved in impact resistance and flexibility without detriment to the excellent properties of polyacetal by polymerizing form-aldehyde or trioxane in the presence of a specified particulate elastomer. CONSTITUTION:A styrene, ester or amide elastomer having functional groups selected from among hydroxyl, carboxyl and amino on one or both ends is purified and optionally ground to obtain a particulate elastomer of a particle diameter of 1000mum or below. 100 pts.wt. formaldehyde or trioxane is (co) polymerized with optionally 0.03-100 pts.wt. cyclic ether or cyclic formal in the presence of the obtained elastomer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an acetal block copolymer having excellent impact resistance and flexibility.

More specifically, the present invention relates to hydroxyl groups, carboxyl groups,
and homopolymerization of formaldehyde or trioxane in the presence of microparticulate styrene, ester, amide, or urethane elastomers having a functional group selected from the group consisting of amino groups at one or both ends, or Alternatively, the present invention relates to a method for producing an acetal block copolymer having excellent impact resistance and flexibility by copolymerizing formaldehyde or trioxane with a cyclic ether or a cyclic formal.

[Conventional technology]

Polyacetal has excellent mechanical properties, fatigue properties, and friction and wear properties, so demand as an engineering plastic has been increasing in recent years.

However, polyacetal has the disadvantage that it has a low impact resistance, for example, a notched Izod value, and is easily destroyed in the presence of residual stress from molding or small scratches.

In order to improve this drawback, copolymers of elastomers and polyacetals have been studied.

For example, JP-A-60-40111 discloses that a graft copolymer having a structure in which polyacetal is grafted onto an elastomer such as a modified ethylene-propylene copolymer or a modified styrene-butadiene copolymer has high impact resistance. What is being done is disclosed.

Moreover, in Japanese Patent Publication No. 62-20203, A-
It is disclosed that B-A) rib block copolymers have excellent impact resistance.

However, in these methods, copolymerization is performed in a system in which the elastomer is completely dissolved in a polymerization solvent, etc., so the resulting acetal copolymer becomes a viscous slurry, making it difficult to filter and dry the acetal copolymer. This problem arose, and it was extremely difficult to stably mass-produce the acetal copolymer in terms of production technology. Moreover, the above-mentioned problem becomes more pronounced as the amount of elastomer introduced into the acetal copolymer increases, and has been a major obstacle in improving the impact resistance of the acetal copolymer.

[Problem to be solved by the invention]

The object of the present invention is to overcome these problems in the prior art and to develop a method for producing an acetal block copolymer that has excellent impact resistance and flexibility while retaining the excellent properties of polyacetal. It is about providing.

[Means and effects for solving the problem] As a result of intensive studies to solve the problem, the present inventors found that it is possible to easily produce an acetal block copolymer based on production technology, and the obtained copolymer We have discovered a method for producing an acetal block copolymer that has high impact resistance and flexibility without impairing the excellent properties originally possessed by polyacetal.

That is, the present invention is directed to the use of microparticles of styrenic, ester, amide, or urethane elastomers having a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at one or both ends. , homopolymerize formaldehyde or trioxane, or
Alternatively, the present invention relates to a method for producing an acetal block copolymer having excellent impact resistance and flexibility by copolymerizing formaldehyde or trioxane with a cyclic ether or a cyclic formal.

The method for producing the acetal block copolymer of the present invention will be specifically explained.

The acetal block copolymer of the present invention is a block copolymer consisting of polyacetal units (A) and elastomer units (B). When the elastomer has a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at one end, the A-B diblock copolymer is
When the elastomer has a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at both ends, A
-B-A triblock copolymer can be obtained.

The polyacetal referred to in the present invention includes acetal homopolymers and acetal copolymers.

Acetal homopolymer is an oxymethylene unit (-
It is a polymer n-form formed by repeating +CHO+), and is stabilized against decomposition from the terminal end of the polymer. An acetal copolymer is a polymer having a structure in which oxyalkylene units are randomly inserted into a chain of repeating oxymethylene units. Examples of oxyalkylene units in acetal copolymers include oxyethylene, oxypropylene, oxytrimethylene, oxytetramethylene, oxybutylene, oxyphenylethylene units, and the like.

The elastomers that can be used in the present invention include styrene-based, ester-based, and
It is an amide-based or urethane-based elastomer. Generally, these elastomers are thermoplastic polymers, which are copolymers consisting of a soft segment with a low glass transition temperature and a hard segment that forms a thermoplastic crosslinking and bonding structure.

In order for the acetal block copolymer of the present invention to have high impact resistance, the glass transition temperature of the soft segment of the elastomer is preferably between -120°C and +40°C. Furthermore, it is more preferably between -120 and -20°C.

The first example of the elastomer constituting the acetal block copolymer of the present invention is a styrene elastomer, which has polystyrene as the node segment. Soft segments to be combined with polystyrene include diene systems such as polybutadiene and polyisoprene,
There are hydrogenated diene systems such as hydrogenated polybutadiene and hydrogenated polyisoprene. Among these styrene elastomers, polystyrene-polybutadiene block copolymers and polystyrene-hydrogenated polybutadiene block copolymers are particularly preferred.

A second example of the elastomer is an ester-based elastomer, in which a hard segment is a polyester such as polyethylene terephthalate, polybutylene terephthalate, modified polyethylene terephthalate, or polyethylene-butylene terephthalate. Soft segments to be combined with polyesters include polyethers such as polypropylene glycol, polytetramethylene glycol, and the like. Among these ester elastomers, polybutylene terephthalate-polytetramethylene glycol block copolymer and polyethylene-butylene terephthalate-polytetramethylene glycol block copolymer are particularly preferred.

A third example of the elastomer is an amide elastomer, in which the hard segment is made of polyamide such as nylon-6, nylon 6-6, or nylon 6-10. Soft segments to be combined with polyamide include:
Examples include polyethers such as polypropylene glycol and polytetramethylene glycol, and polyesters such as polyethylene adipate and polybutylene succinate. Among these amide elastomers, nylon-6-polypropylene glycol block copolymer nylon-
6-Polytetramethylene glycol block copolymers are preferred.

A fourth example of the elastomer is a urethane-based elastomer, in which urethane is used as a hard segment.

Here, urethane is diisocyanate such as 4,4°-diphenylmethane diisocyanate, 4,4°-dicyclohexylmethane diisocyanate, and ethylene glycol.
It is obtained by reacting with a glycol such as tetramethylene glycol. Soft segments to be combined with urethane include polyester diols such as polyethylene adipate and polybutylene adipate, and polyether diols such as polypropylene glycol and polytetramethylene glycol.

Among these urethane elastomers, especially 4.4°
- Polyurethanes synthesized from diphenylmethane cysocyanate, tetramethylene glycol and polytetramethylene glycol are preferred.

The elastomer that can be used in the present invention must have a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at one or both ends. When formaldehyde or trioxane is polymerized in the presence of these elastomers, these functional groups have a molecular weight adjustment function, and at the same time adjust the molecular weight of the polyacetal unit of the resulting acetal block copolymer, the elastomer will be introduced in

Elastomers that can be used in the present invention are classified into the following four types.

The first is a styrene-based elastomer, such as polystyrene-polybutadiene block copolymer (hydroxyl group terminal), polystyrene-hydrogenated polyptadiene block copolymer (hydroxyl group terminal), polystyrene-polyisoprene block copolymer (hydroxyl group terminal), polystyrene-polybutadiene block copolymer (hydroxyl group terminal),
Hydrogenated polyisoprene block copolymer = (hydroxyl group terminal), etc.

The second is an ester-based elastomer, such as polyethylene terephthalate-polypropylene glycol block copolymer (hydroxyl group, carboxyl group terminal), polybutylene terephthalate-polytetramethylene glycol block copolymer (hydroxyl group terminal), polyethylene-butylene terephthalate-polytetramethylene glycol block There are copolymers (hydroxyl group, carboxyl group terminal), etc.

The third type is an amide elastomer, such as nylon-
6-polypropylene glycol block copolymer (terminated with amino group, carboxyl group), nylon-6-polyethylene adipate block copolymer (terminated with carboxyl group), nylon 6.6-polybutylene succinate block copolymer (terminated with amino group), nylon-6- Examples include polytetramethylene glycol block copolymers (terminated with amino groups and hydroxyl groups).

The fourth is a urethane-based telechelic elastomer, such as a polyurethane (hydroxyl group terminal) synthesized from 4,4°-diphenylmethane diisocyanate, tetramethylene glycol, and polytetramethylene glycol;
Examples include 4'-dicyclohexylmethane diisocyanate, propylene glycol, and polyurethane (hydroxyl group terminal) synthesized from polypropylene glycol.

Prior to polymerization, these elastomers are washed, adsorbed,
It is desirable to purify it by methods such as drying. Moreover, these elastomers can be used alone,
Alternatively, two or more kinds can be mixed and subjected to polymerization.

Next, a method for producing the acetal graft copolymer will be described.

In order to easily produce an acetal block copolymer in terms of production technology, which is a feature of the present invention, it is necessary to have the elastomer used in the polymerization system exist in the form of fine particles.

In order to make the elastomer into fine particles, the elastomer may be pulverized using a conventional pulverizer, or the particles existing in the elastomer manufacturing process may be used as they are.

In order to enhance the function of the elastomer having a functional group as a molecular weight regulator, the particle size of the elastomer used is preferably small. Preferably, the particle size of the elastomer is 1,000 μm or less, more preferably 500 μm.
m or less is better.

Furthermore, it is preferable that the elastomer particles swell to some extent within the polymerization system to the extent that the shape of the particles is not significantly impaired. This is also to enhance the function of the elastomer having functional groups as a molecular weight regulator. vice versa,
If the elastomer particles swell too much in the polymerization system and lose their particle shape, or if they are completely dissolved in the polymerization system, the resulting acetal block copolymer will be in a viscous slurry state. Become. Therefore, it becomes difficult to filter and dry the acetal block copolymer, and the object of the present invention cannot be achieved.

The proportion of elastomer in the acetal block copolymer obtained in the present invention, that is, the amount introduced, is preferably 0.5 to 50% by weight based on the total weight of the acetal graft copolymer. If the amount of elastomer introduced is less than 0.5% by weight, the impact resistance of the resulting acetal block copolymer will not improve, and if it is more than 50% by weight, the acetal block copolymer will not improve the impact resistance of the resulting acetal block copolymer. This results in the loss of the excellent mechanical properties.

The amount of elastomer introduced into the acetal block copolymer is more preferably 5 to 40% by weight.

In the homopolymerization of the present invention, formaldehyde or trioxane is used. In addition, in copolymerization,
Formaldehyde or trioxane and cyclic ethers or cyclic formals are used.

Cyclic ethers used in copolymerization include, for example, ethylene oxide, propylene oxide, butylene oxide,
epichlorohydrin, styrene oxide, oxetane,
Examples include 3.3-bis(chloromethyl)oxetane, tetrahydrofuran, and oxepane. Among these cyclic ethers, ethylene oxide is particularly preferred.

In addition, cyclic formals include, for example, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,
There are 5-bentanediol formal and 1,6-hexanediol formal. Among these cyclic formals, ethylene glycol formal, diethylene glycol formal and 1,4-butanediol formal are particularly preferred.

Cyclic ether, cyclic formal, formaldehyde,
The amount used is 0.03 to 100 parts by weight, more preferably 0.1 to 50 parts by weight, based on 100 parts by weight of trioxane.

In the homopolymerization and copolymerization of the present invention, a cationic polymerization catalyst,
Anionic polymerization catalysts are used.

Examples of cationic polymerization catalysts include tin tetrachloride, tin tetrabromide, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate, So-called Friedel-Crafts type compounds such as boron trifluoride coordination compounds such as boron trifluoride acetic anhydrate and boron trifluoride triethylamine complex compounds, perchloric acid, acetyl barchlorate, hydroxyacetic acid, trichloroacetic acid, Inorganic and organic acids such as p-toluenesulfonic acid, complex salt compounds such as triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate, allyldiazonium hexafluorophosphate, allyldiazonium tetrafluoroborate, diethylzinc, triethyl Examples include alkyl metals such as aluminum and diethyl aluminum chloride.

Examples of anionic polymerization catalysts include alkali metals such as sodium and potassium, alkali metal complex compounds such as sodium-naphthalene and potassium-anthracene, alkali metal hydrides such as sodium hydride, and alkaline earth metal hydrides such as calcium hydride. compounds, alkali metal alkoxides such as sodium methoxide, potassium t-butoxide, potassium octoxide, sodium caproate,
alkali metal carboxylic acids such as potassium stearate;
Carboxylic acid alkaline earth metal salts such as magnesium caproate and calcium stearate, amines such as n-butylamine, dibutylamine, distearylamine, trioctylamine, and pyridine, ammonium stearate,
Quaternary ammonium salts such as tetrabutylammonium methoxide, tetrabutylammonium octanoate, dimethyl distearylammonium acetate, trimethylbenzylammonium acetate, trimethylbenzylammonium methoxide, tetramethylphosphonium propionate, trimethylbenzylphosphonium ethoxide, Phosphonium salts such as tetrabutylphosphonium stearate, four organotin compounds such as tributyltin chloride, diethyltin dilaurate, dibutyltin dimethoxide, dibutyltin dilaurate, dioctyltin dilaurate, tributyltin dilaurate, n-butyllithium,
Examples include alkyl metals such as ethylmagnesium bromide and organic chelate compounds such as trisacetylacetone cobalt.

These cationic polymerization catalysts and anionic polymerization catalysts are usually used in an amount of 0.0005 to 5 parts by weight per 100 parts by weight of formaldehyde or trioxane. Homopolymerization or copolymerization is carried out without a solvent or in an organic medium.

Organic media that can be used in the present invention include:
For example, n-pentane, n-hexane, n-heptane, n
- Aliphatic hydrocarbons such as octane, cyclohexane, and cyclopentane; Aromatic hydrocarbons such as benzene, toluene, and xylene; Methylene chloride, chloroform, carbon tetrachloride,
Examples include halogenated aliphatic hydrocarbons such as ethylene chloride and trichlorethylene; halogenated aromatic hydrocarbons such as chlorobenzene and O-dichlorobenzene. These organic media may be used alone or in combination of two or more.

It is preferable that these organic media be selected in combination so that the elastomer particles dispersed in the polymerization system are appropriately swollen.

The polymerization temperature is usually set between -20 and 230°C,
In the case of no solvent, the temperature is more preferably between 20 and 210°C;
When an organic medium is used, a temperature between -1O and 120°C is more preferable.

The polymerization time is not particularly limited, but is set between 5 seconds and 300 minutes.

After a predetermined period of time, a terminator is added into the reaction system or
Alternatively, the polymerization is completed by separating the polymer from the medium. The obtained polymer is usually stabilized by removing unstable ends by hydrolysis or blocking unstable ends by a method such as esterification. The stabilized acetal polymer is put into practical use with the addition of a stabilizer.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these Examples.

The measurement items and measurement conditions in the Examples and Comparative Examples are as follows.

(1) Polymerization slurry state Polymerization slurry obtained by polymerization is filtered through a glass filter (G2
, maximum pore diameter of 100 to 150, czm), and relative judgment was made based on the ease of filtration and the time required for filtration.

(2) Amount of elastomer introduced The acetal block copolymer obtained by polymerization is extracted for about 5 hours at the boiling point of the elastomer-soluble solvent used in the polymerization. 5. This acetal block copolymer.
Weigh out exactly 0 g, add it to 100 ml of IN hydrochloric acid solution, and leave it at 130°C for 2 hours to completely decompose the polyacetal part in the acetal block copolymer. Furthermore,
After washing and drying the decomposition residue, the weight of the decomposition residue, i.e.
The amount of elastomer introduced into the acetal block copolymer was determined.

(3) Physical property measurement ■ I zod impact value (with notch) Measured according to ASTM D-258.

■Bending modulus Measured according to ASTM D-790.

Example 1 A polystyrene-hydrogenated polybutadiene block copolymer (hereinafter abbreviated as PSt-PBD) having hydroxyl groups at both ends was used as an elastomer.

This PSt-PBD has a number average molecular weight of 4X10' polystyrene content of 48% by weight, and is freeze-pulverized using a conventional pulverizer at -150°C, and its particle size is 180%.
It is less than μm.

This pst-PBD was sufficiently dried and dehydrated under reduced pressure.
1,020 g was suspended in dehydrated cyclohexane lO2.

Into a 12fI polymerization tank filled with cyclohexane,
(7) PSt-PBD at 250z/Hr, purity 99.
9% formaldehyde at 1,000 g/Hr
, cyclohexane at 5ρ/Hr, and tetrabutylammonia acetate as a polymerization catalyst at 0.15g/fi.
r continuously for 4 hours. During this time, the polymerization temperature was 50
It was maintained at ℃.

The polymerization slurry obtained here contained particulate polymer, and when this polymerization slurry was filtered using a glass filter (G2), it could be easily and quickly separated into particles and the polymerization solvent.

Furthermore, the particles were stabilized by contacting with acetic anhydride in a vapor state to obtain the acetal block copolymer referred to in the present invention.

The amount of pst-PBD introduced into this acetal block copolymer was 19.7% by weight.

Next, after adding a known stabilizer to the obtained acetal block copolymer, it was extruded using a twin-screw extruder having a diameter of 30+wmφ at a cylinder temperature of 200°C and a screw rotation speed of 11.
The mixture was melt-kneaded under the conditions of 00 rpm and a discharge rate of 5 kg/Hr to obtain a pellet-like acetal block copolymer. After thoroughly drying the pellets, the cylinder temperature was set to 200.
After producing a molded piece by injection molding under the conditions of
d impact value and flexural modulus were measured.

It was found that the material had an I zod impact value of 47 kg-cm/cm and a flexural modulus of 17.000 kg/cI#, indicating that it had excellent impact resistance and flexibility as defined in the present invention.

Examples 2 to 6 Evaluations were made in the same manner as in Example 1, except that the amount of PSt-PBD used as the elastomer introduced was changed. The evaluation results are summarized in Table-1.

It was found that an acetal block copolymer can be easily produced regardless of the amount of elastomer introduced, and the resulting acetal block copolymer has excellent impact resistance and flexibility as defined in the present invention. did.

Examples 7 to 11 Evaluations were made in the same manner as in Example 1, except that the particle size of PSt-PBD used as the elastomer was changed. Similarly, the evaluation results are summarized in Table 1. Regardless of the particle size of the elastomer, the obtained acetal block copolymer had excellent impact resistance and flexibility as referred to in the present invention.

Examples 12 to 18 Evaluations were made in the same manner as in Example 1, except that the elastomers shown in Table 2 were used. The evaluation results are summarized in Table-2.

An acetal block copolymer could be easily produced using any of the elastomers, and the obtained acetal block copolymer had excellent impact resistance and flexibility as defined in the present invention.

Example-19 PSt-PBD used in Example-1, which had been pulverized to a particle size of 45 μm or less, was added to a kneader having two Σ blades, and 15 kg of trioxane was added.

750 g of ethylene oxide, 0.50 f of boron trifluoride.

50 g of methylal was added and polymerized at 80° C. for 45 minutes.

Next, 1.200 g of triethylamine was added to this kneader.
The polymer was stabilized by adding 5 kg of water and stirring at 150° C. for 30 minutes. A stabilizer was added to this polymer, and it was pelletized using a 30 mm diameter single screw extruder, and the evaluation was then carried out in the same manner as in Example-1.

The results are shown in Table-2. As in this example, it can be seen that the acetal block copolymer obtained in the cationic polymerization system also has very good results.

Comparative Example-1 In Example-1, PSt-PBDl used, 00
0 g was completely dissolved in 10 ρ of dehydrated toluene, and 250 g/PSt-PBD was added to cyclohexane.
The operation was carried out in the same manner as in Example-1, except that the water was continuously supplied so that the amount of water was 100 hr.

The obtained polymerization slurry was quite viscous, and no particulate acetal block copolymer was clearly observed in the polymerization solvent.

In the filtration using the glass filter (G2), it took a very long time to separate the acetal block copolymer and the polymerization solvent from the obtained polymerization slurry, and the filtrate became somewhat cloudy. This is thought to be due to the acetal block copolymer that has not yet been formed into particles being extracted to the filtrate side, and it must be said that this is impossible in terms of actual production technology.

Comparative Example-2 In Comparative Example-1, PSt-PBD2.00 used
0 g of toluene dehydrated 20. PS t -PBD was completely dissolved in cyclohexane and 500%
Except that it was continuously supplied so that it was g/Hr,
It was operated in the same manner as in Comparative Example-1.

When the obtained polymer slurry was filtered using a glass filter (G2), no filtrate came out and could not be filtered.

When the elastomer used in this way is completely dissolved in a solvent and used, if the amount of elastomer introduced into the acetal block copolymer becomes this high, it is no longer possible to stabilize the acetal block copolymer in terms of practical production technology. It has become clear that manufacturing is now impossible.

〔Effect of the invention〕

According to the present invention, an acetal block copolymer composed of polyacetal and an elastomer and having excellent impact resistance and flexibility can be easily produced in terms of production technology.

(Margin below)

Claims (2)

[Claims] (1) Homopolymerization of formaldehyde or trioxane in the presence of a styrene, ester, amide, or urethane elastomer having a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at one or both ends. A method for producing an acetal block copolymer, characterized in that the elastomer is present as fine particles in the polymerization system. (2) In the presence of a styrene, ester, amide, or urethane elastomer having a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at one or both ends, formaldehyde or trioxane and a cyclic ether are combined. Alternatively, a method for producing an acetal block copolymer, which comprises causing the elastomer to exist as fine particles in the polymerization system during copolymerization with a cyclic formal.