JP2002234924A - Polyacetal copolymer and its composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin material improved particularly in sliding characteristic, while keeping inherent properties of polyacetal resin, such as excellent appearance, rigidity, heat stability, etc. SOLUTION: This polyacetal copolymer is obtained by copolymerizing 100 pts.wt. trioxane (A), 0.01-40 pts.wt. polysiloxane compound (B) having at least a cyclohexene oxide group, and 0-20 pts.wt. cyclic ether compound (C) capable of copolymerizing with trioxane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyacetal copolymer having 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 automotive parts, precision machine parts, etc. However, as the field in which polyacetal resins are used expands, the required characteristics tend to be increasingly sophisticated, complex, and specialized. As such required characteristics, there is a case where further improvement in sliding characteristics is required while maintaining the original rigidity of the polyacetal resin. To meet such demands, it is common to simply add and knead silicone oil etc. for the purpose of improving the slidability, but polyacetal resins have poor activity and have an affinity with many components. Insufficiency has caused problems such as a decrease in rigidity, poor molding, surface peeling of molded pieces, and insufficient improvement in sliding characteristics.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a polyacetal resin having excellent sliding properties while maintaining various properties such as excellent appearance, rigidity and thermal stability. It is to provide a polyacetal resin material.

[0004]

In order to achieve the above object, the present inventors have found that the modification of the polymer skeleton of the polyacetal resin itself and the design of a resin composition based on such a polymer are important keys for solving the problems. As a result of intensive investigations, it was found that the above-mentioned problems could be solved by a polyacetal copolymer obtained by copolymerizing a specific polysiloxane compound in the production of a polyacetal resin, and the present invention was reached.

That is, the present invention relates to (A) trioxane 10
0 parts by weight, (B) 0.01 to 40 parts by weight of a polysiloxane compound having at least one cyclohexene oxide group, and (C) 0 to 20 parts by weight of a cyclic ether compound copolymerizable with trioxane. It relates to a polyacetal copolymer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the polyacetal copolymer of the present invention will be described in detail.

As described above, the polyacetal copolymer of the present invention comprises (A) 100 parts by weight of trioxane, (B) 0.01 to 40 parts by weight of a polysiloxane compound having at least one cyclohexene oxide group and (C) It is obtained by copolymerizing 0 to 20 parts by weight of a cyclic ether compound copolymerizable with trioxane.

[0008] The trioxane (A) 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 which is obtained by a method such as distillation. It is used after purification. The trioxane used for the polymerization is in a liquid state, and its temperature is preferably 65 to 135 ° C.

Next, the component (B) used in the present invention is a polysiloxane compound having at least one cyclohexene oxide group. The cyclohexene oxide group has a polysiloxane compound at the terminal of the polysiloxane structure constituting the main skeleton. Any of those in the side chain can be used. The polysiloxane structure constituting the main skeleton is not particularly limited, but a polysiloxane structure represented by the following formula, that is, a polydimethylsiloxane structure having a main skeleton is generally preferable.

[0010]

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Further, as the polysiloxane compound (B) having at least one cyclohexene oxide group, those having a polyoxyalkylene chain as a component can also be used.

The above polysiloxane compound (B) used in the present invention has a viscosity at 25 ° C. of 0.5.
It is preferably in the range of ５5000 cSt, more preferably 1１〜３3000 cSt. If the viscosity of the polysiloxane compound (B) is too large, the polysiloxane compound (B) is not uniformly mixed with the component (A) at the time of copolymerization, and the desired copolymer cannot be obtained stably.

These compounds can be used alone or in combination of two or more for copolymerization with trioxane (A).

In the present invention, the above polysiloxane compound (B) is used in an amount of 0.01 to 40 parts by weight based on 100 parts by weight of (A) trioxane. Preferably, it is used in the range of 0.1 to 30 parts by weight, particularly preferably 0.5 to 20 parts by weight. When the amount of the polysiloxane compound (B) is too small, the sliding characteristics of the obtained polyacetal copolymer are not improved, and a sufficient effect cannot be obtained. On the other hand, when the amount of the polysiloxane compound (B) is excessive, the production of the polyacetal copolymer cannot be stably performed, and the fluidity of the obtained copolymer is greatly reduced.

The cyclic ether compound (C) copolymerizable with trioxane used in the present invention includes ethylene oxide, propylene oxide, butylene oxide,
Epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane,
3-dioxolan, propylene glycol formal,
Diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal,
Examples thereof include 1,5-pentanediol formal and 1,6-hexanediol formal, and among them, ethylene oxide, 1,3-dioxolan, diethylene glycol formal, and 1,4-butanediol formal are preferable. The amount of these cyclic ether compounds (C) used is 0 to 1 or 2 or more with respect to 100 parts by weight of (A) trioxane in consideration of the rigidity, chemical resistance and the like of the obtained polyacetal copolymer. 20 parts by weight, preferably 0.01 to 15 parts by weight, particularly preferably 0.1 to 15 parts by weight
10 parts by weight.

In the production of the polyacetal copolymer of the present invention, the amount of the terminal group is adjusted by using a component for adjusting the molecular weight in addition to the above components. As a component for adjusting the molecular weight, a chain transfer agent that does not form an unstable terminal, that is, methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, oxymethylenedi-
Compounds having an alkoxy group such as n-butyl ether are exemplified. In the present invention, it is preferable that the total amount of terminal groups of the resulting polyacetal copolymer is adjusted to 15 to 200 mmol / kg by adjusting the use amount of these molecular weight modifiers, and it is particularly preferable that the total terminal amount be 20 to 200 mmol / kg. ~ 1
It was adjusted to 00 mmol / kg. If the total amount of the terminal groups of the obtained polyacetal copolymer is too small, the fluidity becomes extremely poor, and processing such as injection molding becomes very difficult. On the other hand, if the total amount of terminal groups is excessive, the melt viscosity becomes extremely low, and it becomes impossible to form pellets in a manufacturing process such as extrusion. Further, the obtained copolymer has a remarkably low toughness.

In producing the polyacetal copolymer of the present invention comprising the above-mentioned monomer component and comonomer component, a cationic polymerization catalyst is generally used as a catalyst. Specifically, lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride, trifluoride Boron trifluoride coordination compounds such as boron diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic anhydride, boron trifluoride triethylamine complex compound, perchloric acid, Acetyl perchlorate, t-butyl perchlorate, hydroxyacetic acid, trichloroacetic acid, trifluoroacetic acid, p-
Inorganic and organic acids such as toluenesulfonic acid, triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate, allyldiazonium hexafluorophosphate, complex salt compounds such as allyldiazonium tetrafluoroborate, diethyl zinc, triethyl aluminum, diethyl aluminum One or more of alkyl metal salts such as chlorides, heteropoly acids, isopoly acids, and the like. Among them, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic unhydrate,
Boron trifluoride coordination compounds such as boron trifluoride triethylamine complex compounds are preferred. These cationic polymerization catalysts can be used as they are, or can be used by diluting them in advance with an organic solvent or the like.

The method for producing the polyacetal copolymer of the present invention is not particularly limited, but is generally a liquefied trioxane (A), a polysiloxane compound (B) having a cyclohexene oxide group (B), and a cyclic ether. The compound (C) is polymerized mainly by using a cationic polymerization catalyst to obtain a solid powder bulk polymer by bulk polymerization. The polymerization apparatus is not particularly limited, and a known apparatus is used, and any method such as a batch method and a continuous method can be used. Further, the polymerization temperature is preferably maintained at 65 to 135 ° C.

The deactivation of the catalyst after the polymerization is carried out by adding a basic compound or an aqueous solution thereof to the reaction product discharged from the polymerization machine after the polymerization reaction or 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, or hydroxide salts of alkali metals and alkaline earth metals. And other known catalyst deactivators. After the polymerization reaction, it is preferable to add these aqueous solutions to the product promptly to deactivate the product. After the polymerization method and the deactivation method, if necessary, washing, separation and recovery of unreacted monomers, drying, etc. are performed by a conventionally known method. Further, if necessary, a stabilizing treatment is carried out by a known method such as decomposition removal of an unstable terminal or sealing of an unstable terminal with a stable substance, and various necessary stabilizers are blended. Examples of the stabilizer used here include one or more of a hindered phenol compound, a nitrogen-containing compound, an alkali or alkaline earth metal hydroxide, an inorganic salt, a carboxylate, and the like. it can.

With respect to the terminal group of the polyacetal copolymer obtained as described above, the amount of hemiformal detected by ¹ H-NMR is preferably 0 to 4 mmol / kg, particularly preferably 0 to 2 mmol / kg. Is 4mm
If it exceeds ol / kg, problems such as foaming due to decomposition of the polymer during molding will occur. In order to control the amount of the hemiformal terminal group within the above range, the amount of impurities, particularly water, in the total amount of monomers and comonomer to be subjected to polymerization is preferably 20 ppm or less, particularly preferably 10 ppm or less.

The polyacetal copolymer of the present invention may further contain, if necessary, general additives for thermoplastic resins, for example, coloring agents such as dyes and pigments, lubricants, nucleating agents, release agents, antistatic agents. One or more kinds of agents, surfactants, or organic polymer materials, inorganic or organic fibrous, powdery, or plate-like fillers can be added.

Above all, it is effective to add silicone oil to further improve the sliding characteristics. In this case, the amount of the silicone oil is 0.01 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polyacetal copolymer. By using the polyacetal copolymer of the present invention and blending it with silicone oil, not only sliding properties but also problems such as moldability (improper molding, surface peeling of molded pieces) and the like, which have been a problem so far, have been solved. Be improved.

[0023]

EXAMPLES The present invention will now be described specifically with reference to examples.
However, the present invention is not limited to these examples.
No. The evaluation in the examples was performed by the following method. [Melt index (MI)] Polymer after deactivation treatment
(Powder and granule), melt index measured at 190 ° C
(G / 10 min). This is relative to the molecular weight
It was evaluated as a specific value. That is, the lower the MI, the higher the molecular weight
No. However, in order to prevent decomposition during measurement, certain stabilizers (
Bagaigie, Irganox 1010 (0.5 weight
%) And melamine (0.1% by weight)) and mix well.
Measured. [Tensile strength] A dumbbell type test piece was formed using an injection molding machine.
And measured according to the ISO method. [Flexural Modulus] A test piece was molded using an injection molding machine.
The measurement was performed according to the SO method. [Terminal group analysis] Hexafur
Dissolved in oroisopropanol d2, ¹H-NMR measurement
Was done. It was quantified from the peak area corresponding to each end. [Peeling test] 50mm x 50mm x 1mm flat plate pin gate mold
Using the injection molding at 2 m / sec.
The surface condition was visually observed. [Evaluation of slidability] Cylindrical Suzuki-type test piece by injection molding
(Outer diameter 25.6mm, inner diameter 20mm), Suzuki type friction
Wear tester (Orientec Co., Ltd., EFM-III-
EN) and installed on the fixed side against metal or resin material
A sliding test was performed on the material, and the dynamic friction coefficient and specific friction after 24 hours
The amount of wear was measured.

Sliding condition against resin; load: 0.06 MPa, linear velocity: 15 cm / sec Sliding against metal; load: 0.98 MPa, linear velocity: 30 cm / sec Examples 1 to 7 Outside heat (cooling) medium Using a continuous mixing reactor consisting of a barrel having a shape in which two circles partially overlap with each other and a rotating shaft with paddles, the two rotating shafts with paddles were each rotated at 150 rpm. While rotating, (A) trioxane, (B) polysiloxane compound, and (C) cyclic ether compound copolymerizable with trioxane are added at the ratio shown in Table 1. Further, methylal as a molecular weight regulator and trifluoride as a catalyst are added. The bulk polymerization was carried out while continuously supplying 0.005 parts by weight of boron to the polymerization machine, and the reaction product discharged from the polymerization machine was quickly passed through a crusher while containing 0.05% by weight of triethylamine. The catalyst was deactivated by addition to the aqueous solution at 60 ° C. After further separation, washing and drying, a crude polyacetal copolymer was obtained.
Next, 4 parts by weight of a 5% by weight aqueous solution of triethylamine was added to 100 parts by weight of the crude polyacetal copolymer.
Pentaerythrityl-tetrakis [3- (3,5-di-
tert-butyl-4-hydroxyphenyl) propionate] was added and melt-kneaded at 210C with a twin-screw extruder to remove unstable portions. The obtained polyacetal copolymer is hexafluoroisopropanol d2
The structure and copolymer composition were confirmed by ¹ H-NMR measurement using as a solvent.

To 100 parts by weight of the polyacetal copolymer obtained by the above method, 0.03 parts by weight of pentaerythrityl-tetrakis [3- (3,5-di-tert-4-hydroxyphenyl) propionate] as a stabilizer was added. Parts and 0.15 parts by weight of melamine,
The mixture was melted and kneaded at a temperature of ℃ ° C. to obtain a pellet-shaped polyacetal copolymer. Table 1 shows the evaluation results evaluated by the above-described method.

Example 8 At the time of melt-kneading using a twin-screw extruder, a silicone oil (Toray Dow Corning Silicone SH200 (viscosity 50)
Polymerization and kneading by an extruder were carried out in the same manner as in Example 2 except that 00cSt)) was added to obtain a pellet-like polyacetal copolymer. Table 1 shows the evaluation results evaluated by the above-described method.

Comparative Examples 1-4 Polyacetal copolymers prepared without using the polysiloxane compound (B) and silicone oils (Toray Dow Corning Silicone SH200 (viscosity 5000)
cSt or 60000 cSt)) was evaluated in the same manner as in the examples.

[0028]

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[0029]

[Table 1]

Claims (8)

[Claims] (A) 100 parts by weight of trioxane,
(B) a polyacetal copolymer obtained by copolymerizing 0.01 to 40 parts by weight of a polysiloxane compound having at least one cyclohexene oxide group and (C) 0 to 20 parts by weight of a cyclic ether compound copolymerizable with trioxane . 2. The polyacetal copolymer according to claim 1, wherein the polysiloxane compound (B) has a polysiloxane structure represented by the following formula as a main skeleton. Embedded image 3. The polysiloxane compound (B) has a content of 0.5
3. The polyacetal copolymer according to claim 1, which has a viscosity of about 5,000 cSt. 4. The method according to claim 1, wherein the polysiloxane compound (B) is 1 to 3
3. The polyacetal copolymer according to claim 1, which has a viscosity of 000 cSt. 5. The polyacetal copolymer according to claim 1, wherein the polysiloxane compound (B) contains a polyoxyalkylene chain as a constituent. 6. The polyacetal copolymer according to claim 1, wherein the total terminal group content is 15 to 200 mmol / kg. 7. The polyacetal copolymer according to claim 1, wherein the amount of hemiformal terminal groups is 4 mmol / kg or less. 8. A polyacetal composition obtained by adding 0.01 to 10 parts by weight of silicone oil to 100 parts by weight of the polyacetal copolymer according to any one of claims 1 to 7.