JP2020084071A - Polyacetal resin composition and manufacturing method of polyacetal resin composition - Google Patents

Abstract

To provide a polyacetal resin composition with enhanced level of mechanical properties.SOLUTION: The invention is achieved by a polyacetal resin composition obtained by mixing 100 pts.mass of a polyacetal resin (A) and 0.1 to 100 pts.mass of a polyacetal copolymer (B) obtained by copolymerizing at least trioxane (a) and a compound (b) having at least one kind of trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group, and an alkoxysilyl group, in which the trioxane copolymerizable functional group and the alkoxysilyl group bind only via a binding chain selected from a carbon-carbon bond or an ether bond.SELECTED DRAWING: None

Description

The present invention relates to a polyacetal resin composition having excellent mechanical properties and a method for producing the polyacetal resin composition.

Polyacetal resin has excellent properties in mechanical properties, thermal properties, electrical properties, slidability, moldability, etc., and is mainly used as structural materials and mechanical parts in electrical equipment, automobile parts, precision machinery, etc. Widely used in parts, etc. However, with the expansion of fields in which polyacetal resins are used, required properties tend to become more sophisticated, complex, and specialized. As such required properties, further improvement is required for improving rigidity and suppressing generation of formaldehyde while maintaining the excellent slidability, appearance, etc. originally possessed by the polyacetal resin.

On the other hand, for the purpose of merely improving the rigidity, a method of filling the polyacetal resin with a fibrous filler or the like is generally used, but in this method, the appearance of the molded product is poor due to the filling of the fibrous filler or the like. There are problems such as deterioration of sliding characteristics and sliding properties, and further deterioration of toughness.

In addition, in the polyacetal copolymer, by reducing the amount of comonomer, it is known that the rigidity is improved without substantially impairing the slidability and appearance, but in the method of reducing the comonomer, the toughness decreases. In addition to this, problems such as a decrease in the thermal stability of the polymer occur, and it is not always possible to meet the demand.

Attempts have also been made to improve the rigidity by blending a polyacetal copolymer having a branched structure introduced therein (Patent Document 1), but at the time of polymerization of the polyacetal copolymer having a branched structure introduced, a cationic polymerization catalyst, depending on the type of comonomer, In particular, when a protonic acid is used as the polymerization catalyst, the initiation of polymerization may be delayed and the polymerization may suddenly and explosively occur, which is a problem from the viewpoint of production stability.

For example, regarding a polyacetal copolymer, a copolymer obtained by copolymerizing trioxane and a compound having two or more glycidyl ether groups in one molecule has been proposed (Patent Document 2). However, when using a compound having a plurality of epoxy groups represented by glycidyl ether groups and ether oxygen as functional groups for polymerization, there remains a problem in polymerization stability. Especially when a protic acid is used as a polymerization catalyst, polymerization does not occur at a low catalyst amount, and increasing the catalyst amount causes a phenomenon in which a sudden violent polymerization reaction occurs after an irregular induction period, which makes polymerization control difficult. ing.

Japanese Patent Publication No. 55-019942 JP 2001-163944 A

An object of the present invention is to provide a polyacetal resin composition having improved mechanical properties.

The present inventor, as a result of extensive studies in order to achieve the above object, based on a polyacetal resin as a base, a triacetal and a specific compound having a trioxane copolymerizable functional group and an alkoxysilyl group are copolymerized with a polyacetal copolymer. It has been found that the incorporation of the coalescent compound can improve mechanical properties that have not been predicted previously, and has reached the present invention described below.

1. At least one trioxane copolymerizable functional group selected from the group consisting of trioxane (a), epoxy group and cyclic acetal group and alkoxysilyl group per 100 parts by mass of the polyacetal resin (A), and the trioxane copolymerizable functional group. 0.1 to 10% of the polyacetal copolymer (B) obtained by copolymerizing the alkoxysilyl group with a compound (b) bonded only by a bond chain selected from a carbon-carbon bond or an ether bond. A polyacetal resin composition obtained by mixing 100 parts by mass.

2. 2. The polyacetal resin composition according to 1, wherein the copolymer (B) is a polyacetal copolymer (B) obtained by using at least one selected from perfluoroalkanesulfonic acid, heteropolyacid and isopolyacid as a polymerization catalyst.
3. The copolymer (B) is a polyacetal copolymer (B) obtained by copolymerizing (c) a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring as a comonomer 1 or 2. The polyacetal resin composition according to 2.
4. 4. The polyacetal resin composition according to 1 to 3, wherein the alkoxysilyl group is at least one selected from a trialkoxysilyl group and a dialkoxysilyl group.

5. 1 to 3 wherein the compound (b) is at least one selected from 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)-ethyltriethoxysilane. Polyacetal resin composition of.
6. The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) is an acetal copolymer.

7. With respect to 100 parts by mass of the polyacetal resin (A),
At least one trioxane (a), at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group, and an alkoxysilyl group are contained, and the trioxane copolymerizable functional group and the alkoxysilyl group are carbon-carbon bonds. Alternatively, a polyacetal resin obtained by mixing 0.1 to 100 parts by mass of the polyacetal copolymer (B) obtained by copolymerizing the compound (b) bonded only by a bond chain selected from an ether bond. A method for producing a composition,
A method for producing a polyacetal resin composition, wherein the copolymer (B) is a polyacetal copolymer (B) obtained by using at least one selected from perfluoroalkanesulfonic acid, heteropolyacid, and isopolyacid as a polymerization catalyst.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and is appropriately modified within the scope of the object of the present invention. can do.

<Polyacetal resin composition>
The polyacetal resin composition of the present invention has a polyacetal resin (A), trioxane (a), a trioxane copolymerizable functional group and an alkoxysilyl group, and the trioxane copolymerizable functional group and the alkoxysilyl group are carbon-carbon. A polyacetal obtained by copolymerizing a compound (b) bonded only by a bond chain selected from a bond or an ether bond and a cyclic acetal compound (c) optionally having an oxyalkylene group having 2 or more carbon atoms in the ring It is characterized by being a polyacetal resin composition containing the copolymer (B). In the resin composition of the present invention, the compounding amount of the polyacetal copolymer (B) is 0.1 to 100 parts by mass, preferably 0.5 to 100 parts by mass, relative to 100 parts by mass of the polyacetal resin (A). It is a department.

<(A) Polyacetal resin>
Hereinafter, the constitution of the polyacetal resin composition of the present invention will be described in detail.
The polyacetal resin (A), which is the base of the resin composition of the present invention, is a polymer compound having an oxymethylene unit (—CH ₂ O—) as a main constituent unit, and an acetal homopolymer (for example, manufactured by DuPont, USA). (Trade name "Delrin" and the like), and acetal copolymers containing other comonomer units in addition to the oxymethylene group (for example, trade name "Duracon" manufactured by Polyplastics Co., Ltd.) are included.

In the acetal copolymer, the comonomer unit has an oxyalkylene unit having about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms) (for example, oxyethylene group (—CH ₂ CH ₂ O—), oxypropylene group, oxy). (Eg, a tetramethylene group).

In addition, the content of the comonomer unit is an amount that does not significantly impair the crystallinity of the resin, for example, 0.01 to 20 mol% as a proportion of the constitutional unit of the polyacetal polymer, and preferably, It can be selected from the range of about 0.03 to 10 mol %, and more preferably about 0.1 to 7 mol %.

The acetal copolymer may be a two-component copolymer, a three-component terpolymer, and the like. The acetal copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like.

The degree of polymerization, the degree of branching and the degree of crosslinking of the polyacetal resin (A) are not particularly limited as long as they can be melt-molded. As the polyacetal resin (A) blended in the present invention, an acetal copolymer is particularly preferable in terms of its thermal stability and the like.

<(B) Polyacetal copolymer>
The polyacetal copolymer (B) of the present invention has a trioxane (a), a trioxane copolymerizable functional group and an alkoxysilyl group, and the trioxane copolymerizable functional group and the alkoxysilyl group have a carbon-carbon bond or An alkoxysilyl group obtained by copolymerizing a compound (b) bonded only by a bond chain selected from an ether bond and optionally a cyclic acetal compound (c) having an oxyalkylene group having 2 or more carbon atoms in the ring; It is a polyacetal copolymer (B) containing.

<<(a) Trioxane>>
The trioxane used in the present invention is a cyclic trimer of formaldehyde, which is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and is used after being purified by a method such as distillation. ..

<<(b) having at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group and an alkoxysilyl group, wherein the trioxane copolymerizable functional group and the alkoxysilyl group are carbon-carbon bonds or ethers Compounds that are bound only by the bond chains selected from the bonds >>
The component (b) used in the present invention has at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group and an alkoxysilyl group, and the trioxane copolymerizable functional group and the alkoxysilyl group are , A compound bonded only by a bond chain selected from a carbon-carbon bond or an ether bond.

In the component (b) of the present invention, the trioxane copolymerizable functional group and the alkoxysilyl group are bonded only by a bond chain selected from a carbon-carbon bond or an ether bond.
That is, it means that only a carbon chain or an ether bond exists between the trioxane copolymerization functional group and the alkoxysilyl group.
The distance is preferably 2 to 20 carbon atoms, and the number of ether bonds is preferably 0 to 5, more preferably 0 to 2.

The component (b) can be easily obtained as a silane coupling agent.
The preferred compounds are exemplified below. In addition, Me represents a methyl group and Et represents an ethyl group. Among these, the most preferable compound is b-1 (2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane) or b-2 (2-(3,4-epoxycyclohexyl)) from the viewpoint of polymerization yield. -Ethyltriethoxysilane).

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

<<(c) Cyclic acetal compound having oxyethylene group having 2 or more carbon atoms in the ring>>
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, specifically, 1,3-dioxolane ( DO), 1,3,6-trioxocane, 1,4-butanediol formal (abbreviated as BDF) and the like.

In the present invention, the component (c) is preferably used in an amount of 0.01 to 20 parts by mass, more preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of trioxane. ..

<Polymerization method of polyacetal copolymer (B)>
The method for polymerizing the polyacetal copolymer (B) of the present invention comprises (a) trioxane, (b) at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group, and an alkoxysilyl group, The trioxane copolymerizable functional group and the alkoxysilyl group are bonded to each other only by a bond selected from a carbon-carbon bond or an ether bond, and optionally (c) an oxyalkylene group having 2 or more carbon atoms in the ring. And a cyclic acetal compound having the formula (1) are copolymerized in the presence of a cationic polymerization catalyst.

<Cationic polymerization catalyst>
As the cationic polymerization catalyst, a known polymerization catalyst in cationic copolymerization containing trioxane as a main monomer can be used. Typically, a Lewis acid and a protic acid are used. In particular, the following protic acids are preferable.

≪Protonic acid≫
Examples of the protonic acid include perfluoroalkane sulfonic acid, heteropoly acid and isopoly acid.
Specific examples of perfluoroalkanesulfonic acid include trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, undecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentadecafluoro Examples thereof include heptane sulfonic acid and heptadecafluorooctane sulfonic acid.

Heteropolyacid refers to a polyacid produced by dehydration condensation of different oxygen acids, which is a mononuclear or multinuclear compound formed by condensation of a condensed acid group having a specific heterogeneous element in the center and sharing an oxygen atom. It has complex ions. The isopoly acid is also referred to as iso-polyacid, homonuclear polycondensation acid or homopolyacid, and refers to a high molecular weight inorganic oxygen acid composed of a condensate of an inorganic oxygen acid having a single V- or VI-valent metal. .

Specific examples of the heteropoly acid include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdo tungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdic acid. Examples thereof include tungstic acid and silico molybdenum tovanadic acid. In particular, from the viewpoint of polymerization activity, the heteropolyacid is preferably selected from silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, and phosphotungstic acid.

Specific examples of isopolyacids include paratungstic acid, isopolytungstic acid exemplified by metatungstic acid, paramolybdic acid, isopolymolybdic acid exemplified by metamolybdic acid, metapolyvanadate, isopolyvanadate. Etc. Among them, isopolytungstic acid is preferable from the viewpoint of polymerization activity.

<<Lewis acid>>
Examples of the Lewis acid include boron, tin, titanium, phosphorus, arsenic, and antimony halides, and specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride. , Antimony pentafluoride and complex compounds or salts thereof.

Although the amount of the polymerization catalyst is not particularly limited, it is preferably 0.1 ppm or more and 50 ppm or less, and more preferably 0.1 ppm or more and 30 ppm or less, based on the total of all monomers. Particularly preferably, it is 0.1 ppm or more and 10 ppm or less. (Hereafter, all units of ppm are mass standards.)

The polymerization method of the polyacetal copolymer of the present invention is not particularly limited. In the production, the polymerization apparatus is not particularly limited, and a known apparatus is used, and any method such as batch type and continuous type is possible. The polymerization temperature is preferably maintained at 65°C or higher and 135°C or lower.
It is preferable to use the cationic polymerization catalyst after diluting it with an inert solvent that does not affect the polymerization.

Deactivation of the polymerization catalyst after the polymerization can be performed by a conventionally known method. For example, after the polymerization reaction, a basic compound or an aqueous solution thereof may be added to the reaction product discharged from the polymerization machine or the reaction product in the polymerization machine.
The basic compound 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, if necessary.

The polyacetal copolymer (B) obtained as described above preferably has a weight average molecular weight (polymethylmethacrylate conversion value measured by size exclusion chromatography) of 10,000 to 500,000, particularly preferably 20,000 to It is 150,000. Regarding the terminal group, the amount of hemiformal terminal group detected by ¹ H-NMR (for example, according to the method described in JP 2001-11143 A) is preferably 0 to 4 mol/kg, particularly preferably 0. It is 2 mmol/kg.

In order to control the amount of hemiformal terminal groups within the above range, it is preferable that the amount of impurities, especially water, in the total amount of monomers and comonomer to be used for the polymerization is 20 ppm or less, particularly preferably 10 ppm or less.

<Other ingredients>
It is preferable to add various stabilizers selected as necessary to the resin composition of the present invention as described above. Examples of the stabilizer used here include any one or more of hindered phenol compounds, nitrogen-containing compounds, alkali or alkaline earth metal hydroxides, inorganic salts, and carboxylates. it can.

Further, as long as it does not hinder the present invention, if necessary, general additives to the thermoplastic resin, for example, weathering (light) stabilizers, dyes, colorants such as pigments, lubricants, nucleating agents, release agents, charging An inhibitor, a surfactant, or an organic polymer material, an inorganic or organic fibrous, powdery, or plate-like filler can be added singly or in combination of two or more.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
The polyacetal resin and the polyacetal copolymer (B) used in the examples and comparative examples are as follows.

<Polyacetal resin (A)>
The polyacetal resin was prepared as follows.
A twin-screw paddle type continuous polymerization machine was continuously fed with a mixture of 96.7% by mass of trioxane (TOX), 3.3% by mass of 1,3-dioxolane (DO) and 800 ppm of methylal, and a trifluoride catalyst was used. Polymerization was carried out by adding 20 ppm of boron chloride.
The polymer discharged from the discharge port of the polymerization machine was immediately deactivated by adding an aqueous solution containing 1000 ppm of triethylamine, pulverizing and stirring the mixture. Then, the polymer was recovered by centrifugation and dried to obtain a polyacetal resin.

<Polyacetal copolymer (B)>
The polyacetal copolymer (B) was prepared as follows.
300 g of trioxane (TOX) (a) was placed in a closed autoclave having a jacket through which a heat medium can be passed and a stirring blade, and the compounds shown in Table 1 as the component (b) and 1,3 as the component (c). -Dioxolane (DO) or 1,4-butanediol formal (BDF) was added so as to be the mass parts shown in Table 1, respectively. After stirring the contents and passing warm water of 80°C through the jacket to keep the internal temperature at about 80°C, the catalyst solution (phosphotungstic acid solution in methyl formate, trifluoromethanesulfonic acid solution in cyclohexane) is shown in Table 1. Polymerization was initiated by adding in such a manner that the catalyst concentration indicated (relative to all monomers) was obtained.
After 5 minutes, 300 g of water containing 1000 ppm of triethylamine was added to the autoclave to stop the reaction, and the contents were taken out and pulverized to 200 mesh or less. Then, after washing with acetone, it was dried to obtain a polyacetal copolymer.

For comparison, an attempt was made to produce a polyacetal copolymer using the following diglycidyl compound (having two glycidyl ether groups) in place of the component (b) of the present invention.

<Examples and Comparative Examples>
The various components shown in Table 1 were added and mixed in the proportions shown in Table 1, and melt-kneaded with a vented twin-screw extruder to prepare pelletized compositions.
In all the samples, when melt-kneading, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-) was added to 100 parts by mass of the total amount of the components (A) and (B). Hydroxy-m-tolyl)propionate] (IRGANOX245 manufactured by BASF) and 0.08 part by weight of melamine were added.

In Comparative Examples 2 and 3, regarding the polyacetal copolymer (B), no polymerization reaction was observed under the conditions shown in Table 1 even if the other polymerization conditions were the same as those of the examples.

<Evaluation>
The characteristic evaluation items and evaluation methods in the examples are as follows.
[Bending test]
As a mechanical property, a flexural modulus (FM) according to ISO178 was measured. The conditions of the measuring chamber were 23° C. and 55% RH.

From Table 1, it can be seen that the composition of the present invention has excellent mechanical properties (flexural modulus).

Claims (7)

With respect to 100 parts by mass of the polyacetal resin (A),
At least one trioxane (a), at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group, and an alkoxysilyl group are contained, and the trioxane copolymerizable functional group and the alkoxysilyl group are carbon-carbon bonds. Alternatively, a polyacetal resin obtained by mixing 0.1 to 100 parts by mass of the polyacetal copolymer (B) obtained by copolymerizing the compound (b) bonded only by a bond chain selected from an ether bond. Composition. The polyacetal resin composition according to claim 1, wherein the copolymer (B) is a polyacetal copolymer (B) obtained by using at least one selected from perfluoroalkanesulfonic acid, heteropolyacid, and isopolyacid as a polymerization catalyst. .. The copolymer (B) is a polyacetal copolymer (B) obtained by copolymerizing (c) a cyclic acetal compound having an oxyalkylene group having 2 or more carbon atoms in the ring as a comonomer. The polyacetal resin composition according to 1 or 2. The polyacetal resin composition according to claim 1, wherein the alkoxysilyl group is at least one selected from a trialkoxysilyl group and a dialkoxysilyl group. The compound (b) is at least one selected from 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)-ethyltriethoxysilane. The polyacetal resin composition according to item 3. The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) is an acetal copolymer. With respect to 100 parts by mass of the polyacetal resin (A),
At least one trioxane (a), at least one trioxane copolymerizable functional group selected from an epoxy group and a cyclic acetal group, and an alkoxysilyl group are contained, and the trioxane copolymerizable functional group and the alkoxysilyl group are carbon-carbon bonds. Alternatively, a polyacetal resin obtained by mixing 0.1 to 100 parts by mass of a polyacetal copolymer (B) obtained by copolymerizing the compound (b) bonded only by a bond chain selected from an ether bond. A method for producing a composition, comprising:
A method for producing a polyacetal resin composition, wherein the copolymer (B) is a polyacetal copolymer (B) obtained by using at least one selected from perfluoroalkanesulfonic acid, heteropolyacid, and isopolyacid as a polymerization catalyst.