JP2002003694A - Polyacetal resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin composition in which rigidity and surface hardness are high, and sliding property is also excellent. SOLUTION: To polyacetal resin (A) of 100 pts.wt., polyacetal copolymer in which amount of all end-groups is 15-150 mmol/kg (B) of 0.01-100 pts.wt. and which can be obtained by copolymerizing trioxane (a) of 100 pts.wt., compound containing two or more cyclic ether unit per one molecule (b) of 0.0005-2 pts.wt. and compound containing one cyclic ether unit per one molecule (c) of 0-20 pts.wt., is compounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyacetal resin composition having high rigidity, high surface hardness and excellent sliding properties.

[0002]

2. Description of the Related Art Polyacetal resins have excellent properties in mechanical properties, thermal properties, electrical properties, slidability, moldability, and the like. Widely used for parts, precision machine parts, etc. However, with the expansion of the field in which polyacetal resins are used, the required characteristics tend to be increasingly sophisticated, complex, and specialized. As one example, there is a demand for a material that has further improved rigidity, surface hardness, sliding characteristics, and the like while maintaining the excellent moldability and surface state inherently possessed by the polyacetal resin. In order to meet such demands, a method of filling a polyacetal resin with a fibrous filler is generally used as a means for improving rigidity. However, this method has problems such as poor appearance of molded products and deterioration of sliding characteristics. There is. Further, in polyacetal copolymers, it is known that rigidity and the like are improved by reducing the amount of comonomer to be copolymerized, but the rigidity is slightly improved by this method, and the sliding characteristics are not impaired. On the other hand, while there has been no improvement, problems such as a decrease in the thermal stability of the polymer have arisen, and it has not always been possible to meet the demand.

In view of the problems of the prior art described above, the present inventor changed the idea completely and modified the polymer skeleton itself of the polyacetal copolymer and the rigidity, surface hardness, and slidability of the resin composition using such a polymer. We focused on improvement of dynamic characteristics. Conventionally, although there are some literatures on the modification of the polymer skeleton of the polyacetal resin (for example, Japanese Patent Application Laid-Open No. 3-170526), the findings on the improvement of the rigidity and sliding characteristics of the polyacetal resin based on the above-mentioned idea are as follows. It is not an exaggeration to say that it hardly existed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyacetal resin composition which solves the above-mentioned problems and has high rigidity, excellent surface hardness and excellent sliding characteristics.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have made a polyacetal copolymer having a crosslinked structure introduced by copolymerizing a certain glycidyl compound on a polyacetal resin. It has been surprisingly found that the blending of the coalesced material can improve the rigidity, the surface hardness, and the sliding characteristics unexpectedly and unexpectedly, and have completed the present invention.

That is, the present invention relates to a polyacetal resin (A)
For 100 parts by weight, 100 parts by weight of trioxane (a),
A compound (b) having two or more cyclic ether units in one molecule (b) is obtained by copolymerizing 0.0005 to 2 parts by weight of a compound having one cyclic ether unit in one molecule (c) 0 to 20 parts by weight, A polyacetal resin composition comprising 0.01 to 100 parts by weight of a polyacetal copolymer (B) having a total terminal group content of 15 to 150 mmol / kg.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the polyacetal resin (A) used as the base resin in the present invention has an oxymethylene unit (—CH ₂ O—)
Is a high molecular compound having, as a main structural unit, a polyacetal homopolymer (for example, trade name “Delrin” manufactured by DuPont, USA) or a polyacetal copolymer having other comonomer units in addition to the oxymethylene group (for example, Polyplastics (Trade name, "Duracon", etc.). In the polyacetal copolymer, the comonomer unit has about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms) oxyalkylene unit (for example,
Oxyethylene group (-CH ₂ CH ₂ O-), oxypropylene group,
Oxytetramethylene group). In addition, the content of the comonomer unit is an amount that does not significantly impair the crystallinity of the resin, for example, as a percentage of the constituent units of the polyacetal polymer, generally 0.01 to 20 mol%, preferably 0.03 to 10 mol. %, More preferably from about 0.1 to 7 mol%. Polyacetal copolymers are
It may be a copolymer composed of two components, a terpolymer composed of three components, or the like. The polyacetal copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like. The degree of polymerization of the polyacetal resin (A) is not particularly limited as long as it can be melt-molded. As the polyacetal resin (A) used as the base resin in the present invention, a polyacetal copolymer is particularly preferred in view of its thermal stability and the like. The effect of improving rigidity by blending the polyacetal copolymer (B) is more remarkable than when the base resin is a polyacetal copolymer.

Next, in the resin composition of the present invention, the polyacetal copolymer (B) blended with the polyacetal resin (A) contains trioxane (a) as a main component,
It is obtained by copolymerizing a compound (b) having two or more cyclic ether units in one molecule and, if necessary, a compound having one cyclic ether unit in one molecule.

The trioxane (a) used in the production of the polyacetal copolymer (B) is a cyclic trimer of formaldehyde, and is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst. ,
This is purified by a method such as distillation and used. The trioxane (a) used in the polymerization preferably contains as little as possible impurities such as water, methanol and formic acid.

Next, the compound (b) having two or more cyclic ether units in one molecule used in the production of the polyacetal copolymer (B) refers to an epoxy unit,
Glycidyl unit, 1,3-dioxolan unit, 1,4-
It is a generic term for compounds having two or more cyclic ether units such as a butanediol formal unit, a diethylene glycol formal unit and a 1,3,6-trioxepane unit. Among them, two to four cyclic ether units
Compounds having 3 or 4 cyclic ether units are particularly preferred. The cyclic ether unit is preferably a glycidyl unit, and a diglycidyl ether compound, a triglycidyl ether compound and a tetraglycidyl ether compound are preferred or particularly preferred. Examples include ethylene glycol diglycidyl ether,
Propylene glycol diglycidyl ether, 1,4-
Butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether,
Polypropylene glycol diglycidyl ether, polybutylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol polyglycidyl ether, diglycerol poly Glycidyl ether and the like.

In particular, aliphatic compounds such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, glycerol triglycidyl ether, and trimethylolpropanetri Glycidyl ether and pentaerythritol tetraglycidyl ether are preferred. These compounds can be used alone or in combination of two or more for copolymerization with trioxane (a).

In one molecule, two cyclic ether units are contained.
The copolymerization amount of the compound (b) having at least one compound is 0.0005 to 2 parts by weight, preferably 0.001 to 1.5 parts by weight, particularly preferably 0.005 to 1.5 parts by weight, per 100 parts by weight of trioxane (a).
1 part by weight. If the copolymerization amount of the component (b) is too small, it is difficult to obtain a resin composition having the desired properties. Conversely, if the copolymerization amount is too large, the resulting polyacetal copolymer (B), , The moldability, impact resistance, and surface properties of the composition containing the compound are undesirably deteriorated.

The polyacetal copolymer (B) used in the present invention is preferably a copolymer obtained by further adding a compound (c) having one cyclic ether unit in one molecule as a copolymerization component. Such a compound (c) having one cyclic ether unit is not particularly essential for improving the rigidity, surface hardness and sliding properties which are the objects of the present invention, but the polyacetal copolymer (B) may be used. In order to stabilize the polymerization reaction during the production and to increase the thermal stability of the produced polyacetal copolymer (B), it is necessary to use such a compound (c) having one cyclic ether unit as a copolymerization component. Extremely effective.

The compound (c) having one cyclic ether unit in one molecule includes ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane,
3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1,3-dioxolan, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol Formal, 1,
6-hexanediol formal and the like. Among them, ethylene oxide, 1,3-dioxolan, 1,4
-Butanediol formal and diethylene glycol formal are preferred.

In the polyacetal copolymer (B) used in the present invention, the compound (c) having one cyclic ether unit
Is from 0 to 20 parts by weight, preferably from 0.05 to 15 parts by weight, particularly preferably from 0.1 to 10 parts by weight, per 100 parts by weight of trioxane (a). Cyclic ether unit 1
If the copolymerization ratio of the compound (c) is too small, the copolymerization reaction becomes unstable and the thermal stability of the resulting polyacetal copolymer becomes poor, and conversely, the compound (c) having one cyclic ether unit If the copolymerization ratio in ()) is excessive, mechanical properties such as rigidity and strength, which are the object properties of the present invention, are reduced and become insufficient.

The polyacetal copolymer (B) used in the present invention is basically composed of the above trioxane (a), the compound (b) having two or more cyclic ether units in one molecule, and if necessary, The compound (c) having one cyclic ether unit in one molecule is used, and more generally, an appropriate amount of a molecular weight modifier is added thereto, and bulk polymerization is performed using a cationic polymerization catalyst. .

Examples of the molecular weight modifier include low molecular weight acetal compounds having an alkoxy group such as methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and oxymethylene di-n-butyl ether; and alcohols such as methanol, ethanol and butanol. Kind,
Examples thereof include an ester compound, an acid compound, and water. Among them, a low molecular weight acetal compound having an alkoxy group is particularly preferable. Further, by using these molecular weight regulators, it is possible to regulate the total terminal group content of the polyacetal copolymer (B) used in the present invention. Generally, as the molecular weight modifier increases, the total terminal group content of the obtained polyacetal copolymer increases. In determining the actual amount of the molecular weight modifier to be used, other factors affecting the total terminal group amount of the polyacetal copolymer, for example, the amount of the component (b), water contained in the monomer, and methanol contained in the monomer. In consideration of the amount of impurities, etc., the amount to be added is determined empirically or by a preliminary polymerization test so as to be in the range of the desired total terminal group amount.

The polyacetal copolymer (B) used in the present invention has a weight average molecular weight of 10,000 to 5,000.
00, particularly preferably 20000 to 1500
00. The polyacetal copolymer (B) used in the present invention has a total terminal group content of 15 to 150 mmol / kg detected by ¹ H-NMR. Especially the total amount of terminal groups is 20
~ 100 mmol / kg is preferred. If the total amount of the terminal groups is too small, the fluidity is extremely poor, and processing such as injection molding of a composition containing the compound becomes extremely difficult, and the surface roughness becomes remarkable. If the total amount of the terminal groups is excessive, the melt viscosity is remarkably reduced, and it may not be possible to form pellets in a manufacturing process such as extrusion of a composition containing the same, and the remarkable toughness may be obtained. Is undesirably reduced.
Further, the polyacetal copolymer (B) preferably has a hemiformal terminal group content of 4 mmol / kg or less, particularly preferably 0 to 2 mmol / kg. If the amount of the hemiformal terminal group exceeds 4 mmol / kg, problems such as foaming due to decomposition of the polymer during molding may occur. In order to control the amount of the hemiformal terminal group within the above range, it is preferable that impurities, particularly water, in the total amount of monomers and comonomer to be subjected to polymerization be 20 ppm or less, particularly preferably 10 ppm or less.

As the cationic polymerization catalyst, lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride,
Zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, trifluoride Boron trifluoride coordination compound such as boron trifluoride triethylamine complex compound, boron trichloride, t-butyl perchlorate, t-butyl perchlorate, hydroxyacetic acid, trichloroacetic acid,
Trifluoroacetic acid, inorganic and organic acids such as p-toluenesulfonic acid, triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate,
Complex salt compounds such as allyldiazonium hexafluorophosphate and allyldiazonium tetrafluoroborate,
Alkyl metal salts such as diethylzinc, triethylaluminum, diethylaluminum chloride and the like, heteropoly acids, isopoly acids and the like can be mentioned. Among them, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic anhydrate, boron trifluoride triethylamine complex compound, etc. Boron fluoride coordination compounds are preferred. These catalysts can be used after being diluted with an organic solvent or the like in advance.

In producing the polyacetal copolymer (B) used in the present invention, the polymerization apparatus is not particularly limited, and a known apparatus is used, and any method such as a batch type and a continuous type can be used. It is. The polymerization temperature is 65
It is preferred to keep it at ~ 135 ° C. Deactivation after polymerization is the product reactant discharged from the polymerization machine after the polymerization reaction, or
The reaction is performed by adding a basic compound or an aqueous solution thereof to the reaction product in the polymerization machine.

Examples of the basic compound for neutralizing and deactivating the polymerization catalyst include ammonia, amines such as triethylamine, tributylamine, triethanolamine and tributanolamine;
Alkaline earth metal hydroxide salts and other known catalyst deactivators are used. After the polymerization reaction, it is preferable to add these aqueous solutions to the product promptly to deactivate the product.
After such a polymerization method and a deactivation method, if necessary,
Washing, separation and recovery of unreacted monomers, drying and the like are performed by a conventionally known method.

In the present invention, the blending amount of the above-mentioned polyacetal copolymer (B) is 100 parts by weight of the polyacetal resin (A).
It is 0.01 to 100 parts by weight, preferably 1 to 80 parts by weight based on parts by weight.

It is preferable that the resin composition of the present invention contains various stabilizers selected as necessary. Examples of the stabilizer include any one or more of a hindered phenol compound, a nitrogen-containing compound, an alkali or alkaline earth metal hydroxide, an inorganic salt, and a carboxylate. Furthermore, as long as the objects and effects of the present invention are not impaired, if necessary, general additives for thermoplastic resins, for example, coloring agents such as dyes and pigments, lubricants, release agents, antistatic agents, and surfactants Alternatively, one or more kinds of organic polymer materials, inorganic or organic fibrous, powdery, and plate-like fillers can be added.

The composition of the present invention can be easily prepared by a known method generally used as a conventional method for preparing a resin composition. For example, after mixing each component, the mixture is kneaded and extruded with an extruder to prepare pellets, a predetermined amount of the pellets are mixed and subjected to molding to obtain a molded product having a desired composition after molding. Alternatively, any method such as a method of directly charging two or more can be used.

[0025]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. still,
The evaluation was performed by the following method. [Bending elastic modulus] A test piece was molded using an injection molding machine.
The measurement was performed according to the SO method. [Tensile strength] A dumbbell-shaped test piece was molded using an injection molding machine and measured according to the ISO method. [Rockwell hardness] A test piece was molded using an injection molding machine and measured according to the ASTM method. [Evaluation of slidability] Using a resin composition to be evaluated, a cylindrical Suzuki-type test piece (outer diameter 25.6 mm, inner diameter 20 m
m) Mold 2. Next, using a Suzuki type friction and wear tester (manufactured by Orientec Co., Ltd., EFM-III-EN),
As shown in FIG. 1, a SUS304 round bar (φ5 mm × 5 mm) 1 was slid against a cylindrical Suzuki-type test piece 2 under the conditions of a load of 98 N and a linear velocity of 5 cm / sec. The time at which the torque became 120% of the initial torque was detected and defined as the rupture life of the sliding surface (the rupture life was expressed in terms of the repetitive contact rotation of the round bar 1 and the Suzuki test piece 2). Examples 1 to 7 A paddle was prepared by using a continuous mixing reactor comprising a barrel having a jacket through which a heat (cooling) medium passes and having a cross section having a shape in which two circles partially overlap with each other, and a rotary shaft with a paddle. While rotating the two rotating shafts marked with at 150 rpm,
Trioxane (a): 2 cyclic ether units per molecule
Compound (b) having one or more cyclic ether units in one molecule at a ratio shown in Table 1,
Furthermore, methylal is continuously supplied as a molecular weight regulator,
Bulk polymerization was carried out by continuously adding and supplying 0.005% by weight of a catalyst, boron trifluoride, based on trioxane. The reaction product discharged from the polymerization machine was immediately passed through a crusher and added to an aqueous solution containing 0.05% by weight of triethylamine at 60 ° C. to deactivate the catalyst. Further, after separation, washing and drying, a crude polyacetal copolymer was obtained.

Next, the crude polyacetal copolymer 1
4 wt% of a 5 wt% aqueous solution of triethylamine and pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] was added in an amount of 0.3% by weight, and the mixture was melt-kneaded at 210 ° C. with a twin-screw extruder to remove unstable portions. The obtained polyacetal copolymer was confirmed for its copolymer composition by ¹ H-NMR measurement using hexafluoroisopropanol d ₂ as a solvent, and was quantified from the peak area corresponding to each terminal, and the total terminal group amount was determined. And the amount of hemiformal terminal groups were determined.

Next, the polyacetal copolymer (B) obtained by the above-mentioned method was blended with the polyacetal resin (A) (Duracon M90, manufactured by Polyplastics Co., Ltd.) in the ratio shown in Table 1 to obtain a biaxial resin. The mixture was melt-kneaded at 210 ° C. by an extruder to obtain a pellet-shaped polyacetal resin composition. Table 1 shows the results of evaluating the physical properties by the methods described above. Comparative Examples 1 to 5 Compound (b) having two or more cyclic ether units in one molecule when the polyacetal copolymer (B) is not blended
Polyacetal copolymer (B) prepared without the use of
In the case of blending, for example, a pellet-shaped composition was prepared and evaluated in the same manner as in the examples. Table 1 shows the results.

[0028]

[Table 1]

Component (b) BDGE: butanediol diglycidyl ether TMPTGE: trimethylolpropane triglycidyl ether GTGE: glycerol triglycidyl ether PETGE: pentaerythritol tetraglycidyl ether (c) Component DO: 1,3-dioxolane EO: ethylene oxide

[Brief description of the drawings]

FIG. 1 is a view showing a test situation of slidability evaluation in an example.

[Explanation of symbols]

 1 SUS304 round bar 2 Suzuki type test piece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihisa Tajima 973 Miyajima, Fuji-shi, Shizuoka Polyplastics Co., Ltd. F-term (reference) 4J002 CB001 CB002

Claims (9)

[Claims] 1. A compound having two or more cyclic ether units in one molecule (b) 0.0005 to 100 parts by weight of trioxane (a) based on 100 parts by weight of polyacetal resin (A)
A polyacetal copolymer (B) obtained by copolymerizing 2 parts by weight and 0 to 20 parts by weight of a compound (c) having one cyclic ether unit in one molecule and having a total terminal group amount of 15 to 150 mmol / kg ) A polyacetal resin composition containing 0.01 to 100 parts by weight. 2. The compound (b) having two or more cyclic ether units in one molecule is a diglycidyl ether compound,
The polyacetal resin composition according to claim 1, wherein the composition is at least one member selected from the group consisting of a triglycidyl ether compound and a tetraglycidyl ether compound. 3. The compound (b) having two or more cyclic ether units in one molecule is ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl. The polyacetal resin composition according to claim 2, wherein the polyacetal resin composition is at least one member selected from the group consisting of ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether. 4. The polyacetal resin composition according to claim 1, wherein the copolymerization ratio of the compound (c) having one cyclic ether unit in one molecule is 0.05 to 15 parts by weight. 5. The compound (c) having one cyclic ether unit in one molecule, wherein the compound (c) is selected from the group consisting of ethylene oxide, 1,3-dioxolan, 1,4-butanediol formal and diethylene glycol formal. The polyacetal resin composition according to any one of claims 1 to 4, which is at least one kind. 6. The polyacetal resin composition according to claim 1, wherein the total amount of terminal groups of the polyacetal copolymer (B) is 20 to 100 mmol / kg. 7. The polyacetal copolymer (B) has a thickness of 4 mm.
The polyacetal resin composition according to any one of claims 1 to 6, which has a hemiformal terminal group content of ol / kg or less. 8. The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) is a polyacetal copolymer. 9. The polyacetal resin composition according to claim 1, wherein the amount of the polyacetal copolymer (B) is 1 to 80 parts by weight.