阅读说明：本技术 聚缩醛共聚物及其聚合方法 (Polyacetal copolymer and method for polymerization thereof ) 是由 喜来直裕 增田荣次 于 2019-01-18 设计创作，主要内容包括：本发明的目的是提供维持刚性、蠕变特性、滑动特性的水平,且生产稳定性、甲醛产生量等热稳定性也优异的聚缩醛共聚物和聚合方法。通过聚缩醛共聚物和聚缩醛共聚物的聚合方法来实现,所述聚缩醛共聚物是使三氧杂环己烷、在环内具有碳原子数为2以上的氧亚烷基的环状缩醛化合物、以及在1分子中具有2个以上的环氧基且除了环氧基之外由烃形成的聚环氧化合物进行共聚而得的,所述聚缩醛共聚物的聚合方法中,使三氧杂环己烷、在环内具有碳原子数为2以上的氧亚烷基的环状缩醛化合物、以及在1分子中具有2个以上的环氧基且除了环氧基之外由烃形成的聚环氧化合物在阳离子聚合催化剂的存在下进行共聚。(The present invention aims to provide a polyacetal copolymer and a polymerization method, which maintain the rigidity, creep characteristics and sliding characteristics, and have excellent production stability, formaldehyde generation amount and other thermal stability. The polymerization method is realized by a polyacetal copolymer and a polymerization method of the polyacetal copolymer, wherein the polyacetal copolymer is obtained by copolymerizing trioxane, a cyclic acetal compound which has an oxyalkylene group with the carbon number of more than 2 in a ring, and a polyepoxy compound which has more than 2 epoxy groups in 1 molecule and is formed by hydrocarbon except the epoxy group, in the polymerization method of the polyacetal copolymer, the trioxane, the cyclic acetal compound which has the oxyalkylene group with the carbon number of more than 2 in the ring, and the polyepoxy compound which has more than 2 epoxy groups in 1 molecule and is formed by hydrocarbon except the epoxy group are copolymerized in the presence of a cationic polymerization catalyst.)

1. A polyacetal copolymer obtained by copolymerizing trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups.

2. The polyacetal copolymer according to claim 1, wherein the polyepoxide is a polyepoxide represented by the following formula,

p represents an integer of 0 to 20.

3. A method for polymerizing a polyacetal copolymer, wherein trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups are copolymerized in the presence of a cationic polymerization catalyst.

4. The method for polymerizing a polyacetal copolymer according to claim 3, wherein the polyepoxide is a polyepoxide represented by the following formula,

p represents an integer of 0 to 20.

5. The polymerization method of a polyacetal copolymer according to claim 3 or 4, wherein the cationic polymerization catalyst is a protonic acid.

Technical Field

The present invention relates to a polyacetal copolymer having high rigidity, excellent creep characteristics and sliding characteristics, and further having a very small formaldehyde emission amount, and a polymerization method thereof.

Background

Polyacetal resins have excellent properties in terms of mechanical properties, thermal properties, electrical properties, slidability, moldability and the like, and are widely used mainly as structural materials, mechanical parts and the like for electrical equipment, automobile parts, precision machine parts and the like. However, as the field of application of polyacetal resins has been expanded, the required properties have been increasingly advanced, compounded and specialized. As such required properties, further improvement in rigidity and suppression of formaldehyde emission while maintaining excellent sliding properties and appearance inherent in polyacetal resins is required.

In contrast, a method of filling a fibrous filler or the like into a polyacetal resin is generally used for the purpose of improving the rigidity, but this method has problems such as poor appearance and reduced sliding properties of a molded article due to the filling of the fibrous filler or the like, and further has a problem of reduced toughness.

Further, it is known that the rigidity of the polyacetal copolymer is improved without substantially impairing the slidability and the appearance by reducing the amount of the comonomer, but the method of reducing the comonomer causes problems such as not only a decrease in toughness but also a decrease in thermal stability of the polymer, and thus the method is not always satisfactory.

However, depending on the kind of the comonomer, when a cationic polymerization catalyst, particularly a protonic acid, is used as the polymerization catalyst, the initiation of polymerization may be delayed, and the polymerization may suddenly and explosively occur, and there is a problem in view of production stability.

For example, as for the polyacetal copolymer, a copolymer obtained by copolymerizing trioxane with a compound having 2 or more glycidyl ether groups in 1 molecule has been proposed (patent document 1). However, when a compound having a plurality of epoxy groups represented by glycidyl ether groups and ether oxygen groups as functional groups is used in polymerization, there remains a problem in polymerization stability. In particular, when a protonic acid is used as a polymerization catalyst, polymerization does not occur in a low catalytic amount, and if the catalytic amount is increased, a phenomenon in which a sharp polymerization reaction suddenly occurs after an irregular induction period occurs, and it is difficult to control the polymerization.

Disclosure of Invention

Problems to be solved by the invention

Although suppression of the generation of formaldehyde is a continuous problem in polyacetal copolymers, the demand for such a polyacetal copolymer is becoming severer year by year.

The present invention aims to provide a polyacetal copolymer and a polymerization method, which maintain the levels of rigidity, creep characteristics and sliding characteristics by introducing a branched structure as described above and are excellent in production stability and thermal stability such as the amount of formaldehyde generated.

Means for solving the problems

The object of the present invention is achieved as follows.

1. A polyacetal copolymer obtained by copolymerizing trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups.

2. The polyacetal copolymer according to claim 1, wherein the polyepoxide is a polyepoxide represented by the following formula.

P represents an integer of 0 to 20.

3. A method for polymerizing a polyacetal copolymer, wherein trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups are copolymerized in the presence of a cationic polymerization catalyst.

4. The method for polymerizing a polyacetal copolymer according to the above 3, wherein the polyepoxide is a polyepoxide represented by the following formula.

P represents an integer of 0 to 20.

5. The method for polymerizing a polyacetal copolymer according to the above 3 or 4, wherein the cationic polymerization catalyst is a protonic acid.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided a polyacetal copolymer and a polymerization method, which are excellent in production stability, formaldehyde generation amount and the like, while maintaining the levels of rigidity, creep characteristics and sliding characteristics.

Detailed Description

The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the intended scope of the present invention.

< polyacetal copolymer >

The polyacetal copolymer of the present invention is characterized by being obtained by copolymerizing trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups.

Trioxane

Trioxane used in the present invention is a cyclic trimer of formaldehyde, and is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and is used by purifying it by a method such as distillation.

A cyclic acetal compound having an oxyethylene group having 2 or more carbon atoms in the ring (hereinafter also referred to as component (A))

The cyclic acetal compound having an oxyethylene group having 2 or more carbon atoms in the ring of the present invention is a compound generally used as a comonomer in the production of a polyacetal copolymer, and specific examples thereof include 1, 3-dioxolane, 1,3, 6-trioxane, 1, 4-butanediol formal, and the like.

In the present invention, the component (A) is preferably used in an amount within a range of 0.01 to 20 parts by mass, and more preferably within a range of 0.05 to 5 parts by mass, based on 100 parts by mass of trioxane.

Polyepoxy compound having 2 or more epoxy groups in 1 molecule and formed of hydrocarbon other than epoxy groups (hereinafter also referred to as component (B))

The component (B) used in the present invention is characterized by being a polyepoxy compound having 2 or more epoxy groups in 1 molecule and formed of a hydrocarbon other than the epoxy groups.

In general, when an epoxy group is introduced into a molecule, epichlorohydrin is often used as a raw material and introduced in a glycidyl ether group structure, but the epoxy group of the present invention is characterized by having an epoxy group not derived from a glycidyl ether group.

The glycidyl ether group in the present invention refers to a group having the following structure. Denotes the site of bonding to other structures.

As a known technique, an epoxy compound having an epoxy group derived only from a diglycidyl ether group is known as a comonomer, but the present invention has found that: in the absence of a glycidyl ether group, the strength of the polyacetal copolymer can be maintained and the amount of formaldehyde generated can be suppressed.

Specific examples thereof include 1, 3-butadiene diepoxide (described below as B-5), 1, 4-pentadiene diepoxide, 1, 5-hexadiene diepoxide (described below as B-4), 1, 6-heptadiene diepoxide, 1, 7-octadiene diepoxide (described below as B-3), 1, 8-nonadiene diepoxide, 1, 9-decadiene diepoxide (described below as B-2), 1, 10-undecadiene diepoxide, and 1, 11-dodecene diepoxide (described below as B-1).

Preferred are epoxy compounds represented by the following general formulae 1 and 2.

Formula 1

Formula 2

P represents an integer of 0 to 20, n represents an integer of 0 to 10, and m represents an integer of 1 to 10.

In the present invention, the component (B) is preferably used in an amount within a range of 0.01 to 5 parts by mass, more preferably 0.03 to 1 part by mass, based on 100 parts by mass of trioxane.

< method for polymerizing polyacetal copolymer >

The method for polymerizing a polyacetal copolymer of the present invention is characterized by copolymerizing trioxane, a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring, and a polyepoxide compound having 2 or more epoxy groups in 1 molecule and being formed of a hydrocarbon other than the epoxy groups in the presence of a cationic polymerization catalyst.

< cationic polymerization catalyst >

As the cationic polymerization catalyst, a polymerization catalyst known in cationic copolymerization using trioxane as a main monomer can be used. Typically, Lewis acids and protonic acids are mentioned. Protic acids are particularly preferred.

Proton acid

Examples of the protonic acid include perfluoroalkanesulfonic acid, heteropolyacid, and isopoly acid.

Specific examples of perfluoroalkanesulfonic acids include trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, undecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentadecafluoroheptanesulfonic acid, and heptadecafluorooctanesulfonic acid.

The heteropoly acid is a polyacid produced by dehydration condensation of various kinds of oxo acids, and has a single-core or multi-core complex ion in which a specific different element is present in the center and an oxygen atom is shared to enable condensation of a condensed acid group. Isopoly acids, also known as isopoly acids, homonuclear condensation acids, isopoly acids, refer to high molecular weight inorganic oxoacids formed from the condensation of inorganic oxoacids of a single type of metal having a valence of V or VI.

Specific examples of the heteropoly-acid include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, silicomolybdotungstovanadic acid, and the like. In particular, the heteropoly-acid is preferably selected from the group consisting of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, phosphotungstic acid, from the viewpoint of polymerization activity.

Specific examples of the isopoly acid include tungsten isopoly acids exemplified by paratungstic acid, metatungstic acid, and the like; molybdenum isopolyacids exemplified by paramolybdic acid, metamolybdic acid, and the like; metavanadate, vanadium isopoly acid, and the like. Among them, tungsten isopoly acid is preferable from the viewpoint of polymerization activity.

Lewis acid

Examples of the lewis acid include halides of boron, tin, titanium, phosphorus, arsenic and antimony, and specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, antimony pentafluoride, and complexes or salts thereof.

The amount of the polymerization catalyst is not particularly limited, but is preferably 0.1ppm to 50ppm, more preferably 0.1ppm to 30ppm, based on the total amount of all monomers. Particularly preferably 0.1ppm to 10 ppm.

In the production of the polyacetal copolymer of the present invention, in addition to the above-mentioned components, a component for adjusting the molecular weight may be used in combination to adjust the amount of the terminal group. Examples of the component for adjusting the molecular weight include compounds having an alkoxy group such as methylal, monomethoxymethylal, dimethoxymethylal, which are chain transfer agents not forming an unstable terminal.

The method for polymerizing the polyacetal copolymer of the present invention is not particularly limited. The polymerization apparatus is not particularly limited during the production, and any known apparatus, such as a batch type or a continuous type, may be used. Further, the polymerization temperature is preferably maintained at 65 ℃ or higher and 135 ℃ or lower.

The cationic polymerization catalyst is preferably used by diluting with an inactive solvent which does not adversely affect the polymerization.

The deactivation of the polymerization catalyst after the polymerization can be carried out by a conventionally known method. For example, the polymerization may be carried out by adding a basic compound or an aqueous solution thereof to the reaction product discharged from the polymerization reactor or the reaction product in the polymerization reactor after the polymerization reaction.

The basic compound used for neutralizing and deactivating the polymerization catalyst is not particularly limited. After polymerization and deactivation, washing, separation and recovery of unreacted monomers, drying, and the like are further performed by a conventionally known method as needed.

The weight average molecular weight of the polyacetal copolymer obtained in the above-mentioned manner is preferably 10000 to 500000, and particularly preferably 20000 to 150000. Further, with respect to the terminal group, use is made of¹The amount of hemiformal detected by H-NMR is preferably 0 to 4mol/kg, particularly preferably 0 to 2 mmol/kg.

In order to control the hemiformal end group content within the above range, impurities, particularly water, in the total amount of monomers and comonomers to be polymerized are preferably 20ppm or less, and particularly preferably 10ppm or less.

Further, to the polyacetal copolymer of the present invention, 1 or 2 or more kinds of additives commonly used for thermoplastic resins, for example, coloring agents such as dyes and pigments, lubricants, nucleating agents, mold release agents, antistatic agents, surfactants, or organic polymer materials, inorganic or organic fibrous, powdery, and plate-like fillers, may be added as necessary.