JP2002348345A - Modified polyoxymethylene copolymer, its manufacturing method and composite molding using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified polyoxymethylene copolymer having excellent adhesion and welding properties to various kinds of polyolefin materials. SOLUTION: The modified polyoxymethylene copolymer comprises a polyoxymethylene skeleton of 50-99.99 wt.% and a polyvinyl acetal skeleton of 0-01-50 wt.% as constituent units.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene copolymer having excellent adhesion and welding properties to various polyolefin materials.

[0002]

2. Description of the Related Art Polyoxymethylene resins are engineering plastics having well-balanced and excellent properties in many physical properties such as mechanical properties, electrical properties, and chemical resistance. It is widely used as a material for structural parts such as automobile parts, electric / electronic equipment parts, and mechanical parts. On the other hand, besides polyoxymethylene resin, resin materials that are widely used in these fields include polyolefins represented by polyethylene and polypropylene. In recent years, such polyolefin parts and polyoxymethylene resin parts have been used. Attempts are often made to obtain a composite part that utilizes the properties of each resin by bonding or welding. Further, there has been an attempt to obtain a composite molded product by integrating a polyolefin component and a polyoxymethylene resin component during molding by using molding means such as two-color molding.

However, since polyoxymethylene resin inherently has low affinity for polyethylene and polypropylene, a composite part having sufficient strength can be obtained simply by bonding or welding these polyolefin parts and polyoxymethylene resin parts. You can't get it.

In order to improve this, various types of adhesives have been studied in the bonding method, but it is still difficult to obtain a composite part having a sufficient bonding strength.

In the method of forming a composite by heat welding or two-color molding, the key is to improve the affinity between the polyoxymethylene resin and the polyolefin, and a polyolefin modified with maleic anhydride or the like is used as the polyolefin. By using a polyoxymethylene resin composition containing such an acid-modified polyolefin as a polyoxymethylene resin, or by using such a polyoxymethylene resin, the affinity between the two resins is improved, and the adhesion and adhesion between the polyoxymethylene resin part and the polyolefin part are improved. It has been studied to improve the adhesiveness, but its adhesiveness and weldability have not yet been sufficient, and further improvement has been desired.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to provide a resin material which can meet such demands. As a result, the present inventors have made a polyoxymethylene skeleton as a main component and a polyvinyl acetal skeleton as a structural unit. By introducing the modified polyoxymethylene resin, it has been found that a modified polyoxymethylene copolymer having excellent adhesion and welding properties with a polyolefin material can be obtained without impairing the excellent mechanical properties inherent in the polyoxymethylene resin. Reached.

That is, the present invention provides a polyoxymethylene skeleton 5
The present invention relates to a modified polyoxymethylene copolymer having a structural unit of 0 to 99.99% by weight and a polyvinyl acetal skeleton of 0.01 to 50% by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The modified polyoxymethylene copolymer of the present invention and a method for producing the same will be described in detail below.

The modified polyoxymethylene copolymer of the present invention has a polyoxymethylene skeleton of 50 to 99.
99% by weight and a polyvinyl acetal skeleton of 0.01 to 5
0% by weight as a structural unit.

The polyoxymethylene skeleton constituting the modified polyoxymethylene copolymer of the present invention includes a polyoxymethylene homopolymer skeleton consisting essentially of oxymethylene repeating units, an oxyalkylene group and the like in addition to the oxymethylene group. It may be a polyoxymethylene copolymer skeleton having another structural unit, or a skeleton having a branched structure or a crosslinked structure using an oxymethylene group as a main repeating unit. Such polyoxymethylene homopolymer backbone by polymerization, such as polymerization of anhydrous formaldehyde or a cyclic trimer of formaldehyde trioxane and polyoxymethylene copolymers backbone, formaldehyde or general formula (CH ₂ O) _n [where , N is an integer of 3 or more], for example, by copolymerizing a cyclic oligomer of formaldehyde, for example, trioxane, with a cyclic ether and / or cyclic formal. Examples of the cyclic ether or cyclic formal for copolymerization include ethylene oxide, propylene oxide, tetrahydrofuran,
3-dioxolan, oxepane, ethylene glycol formal, diethylene glycol formal, 1,4-
Butanediol formal, 1,6-hexanediol formal and the like are used. Further, instead of the cyclic ether or cyclic formal in the copolymerization, or in combination with these cyclic ethers or cyclic formal, a polyfunctional compound such as a diglycidyl ether compound or a monofunctional compound having a specific structure such as an alkyl glycidyl ether. By using, a polyoxymethylene skeleton having a branched structure or a crosslinked structure can be obtained.

The polyoxymethylene skeleton constituting the modified polyoxymethylene copolymer of the present invention may be any of the above-described polyoxymethylene skeletons. It is preferably a polyoxymethylene copolymer skeleton into which an alkylene group has been introduced. In addition, as the polyoxymethylene copolymer skeleton, those having an oxymethylene group as a main repeating unit and having a comonomer unit of 0.05 to 10 mol% are preferable, and particularly preferably 0.1 to 0.1.
It has 5.0 mol% of comonomer units. The fact that the modified polyoxymethylene copolymer has such a polyoxymethylene copolymer skeleton means that, from the viewpoint of the thermal stability of the resin itself, the molded part comprising the modified polyoxymethylene copolymer of the present invention comprises a polyolefin. It is particularly preferable from the viewpoint of heat resistance when being welded or bonded to a molded part by heat welding or the like.

Next, the polyvinyl acetal skeleton constituting the modified polyoxymethylene copolymer of the present invention is introduced by using a polyvinyl acetal resin and chemically bonding it to the polyoxymethylene skeleton. The polyvinyl acetal resin used here is basically obtained by reacting polyvinyl alcohol with an aldehyde in the presence of an acid catalyst such as hydrochloric acid or sulfuric acid to acetalize a part or all of the hydroxyl groups of the polyvinyl alcohol. The reaction product with formaldehyde is called polyvinyl formal resin, and the reaction product with butyraldehyde is called polyvinyl butyral resin. Further, depending on the type of aldehyde to be reacted, polyvinyl acetoacetal, polyvinylpropylacetal, and the like are known.
As a method for producing these polyvinyl acetal resins,
For example, when polyvinyl acetate is hydrolyzed with an acid, an aldehyde is added at the initial stage, and hydrolysis and acetalization are allowed to proceed at the same time, or polyvinyl alcohol generated by hydrolysis of polyvinyl acetate is separated once. There may be mentioned a two-stage method of converting this into an acetal. The polyvinyl acetal resin thus obtained has a vinyl acetal group as a main component and a vinyl alcohol group and optionally a vinyl acetate group, and is represented by the following general formula (1).

[0013]

Embedded image

Here, R ¹ is represented by — (CH ₂ ) _n —CH ₃ [where n = 0 to 3], and is generally —CH ₃ . R ² is hydrogen or any alkyl group having 4 or less carbon atoms, and a typical example is —CH ₃ or —C ₃
H ₇ and the like. X, Y, and Z are arbitrary,
As the polyvinyl acetal resin used in the present invention, those having a vinyl acetal group of 60% by weight or more as a constitutional unit are preferable, and the vinyl alcohol group is preferably 0.1 to 40% by weight.

The polyvinyl acetal resin has an average degree of polymerization of 100 to 3 from the viewpoints of improving the molecular weight and fluidity of the modified polyoxymethylene copolymer to be formed, and improving the weldability with the polyolefin as the object of the present invention. Is preferred. In addition, among polyvinyl acetal resins, polyvinyl formal resin and polyvinyl butyral resin are particularly preferable.

In the modified polyoxymethylene copolymer of the present invention, the ratio of the polyvinyl acetal skeleton is as follows:
It is 0.01 to 50% by weight based on 50 to 99.99% by weight of the polyoxymethylene skeleton, and particularly preferably 0.5 to 5%.
~ 5% by weight. If the proportion of the polyvinyl acetal skeleton is less than 0.01% by weight, the effect of welding and bonding with the polyolefin material is not sufficiently exhibited, and if it exceeds 50% by weight, the mechanical properties of the resulting modified polyoxymethylene copolymer are obtained. Causes extreme deterioration. Further, the polymerization system becomes non-uniform and the polymerization becomes difficult.

The modified polyoxymethylene copolymer of the present invention has a weight average molecular weight of 3,000 to 300,000.
0, preferably between 10,000 and 200,000;
This can be adjusted to any value by adjusting the polymerization conditions described below.

The method for producing the modified polyoxymethylene copolymer of the present invention having a polyoxymethylene skeleton and a polyvinyl acetal skeleton as described above is not particularly limited. Once a polyoxymethylene polymer or copolymer is manufactured using a monomer component and a comonomer component such as
A method of reacting this with a polyvinyl acetal resin is also possible, but a particularly preferable method is to polymerize a monomer or a comonomer capable of forming a polyoxymethylene skeleton in the presence of the polyvinyl acetal resin as described below. It is a method of reacting. Thereby, a polyoxymethylene skeleton is formed, and a modified polyoxymethylene copolymer having a polyvinyl acetal skeleton is obtained by a reaction with a polyvinyl acetal resin.

Hereinafter, a method for producing the modified polyoxymethylene copolymer having a polyoxymethylene copolymer skeleton and a polyvinyl acetal skeleton, which are preferred, will be described.

Such a modified polyoxymethylene copolymer is prepared by using a cationic active catalyst in the presence of a polyvinyl acetal resin, using formaldehyde or a cyclic oligomer thereof as a main monomer and the above-mentioned cyclic ether and / or cyclic formal as a comonomer. It can be produced by copolymerization. As the main monomer, trioxane is typical and most preferable, and as the comonomer, ethylene oxide, 1,3-dioxolan, diethylene glycol formal, and 1,4-butanediol formal are preferable. Further, as the polyvinyl acetal resin, it is preferable to use a polyvinyl formal resin and / or a polyvinyl butyral resin. As described above, such a polyvinyl acetal resin has a vinyl alcohol group or a vinyl acetal group having a cyclic structure, and mainly by the function of a vinyl alcohol group serving as a chain transfer agent with a polyoxymethylene chain,
A bond with the polyoxymethylene skeleton is formed by the reaction of the vinyl acetal group having a cyclic structure that functions as a polymerizable functional group. Part of the polyvinyl acetal resin added during the polymerization may remain in the system without being reacted.

Such a polymerization reaction can be basically performed by using a known trioxane copolymerization method. That is, trioxane, a comonomer component, a polyvinyl acetal resin, a molecular weight regulator and a polymerization catalyst may be added at the same time, or they may be added separately. Alternatively, two or more of these optional components may be mixed in advance and supplied to be used for polymerization. The cation-active catalyst used in the polymerization may be any known cation-active catalyst generally used in the polymerization of trioxane, and examples thereof include Lewis acids, particularly halogens such as boron, tin, titanium, phosphorus, arsenic, and antimony. Compounds such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride and antimony pentafluoride, and complexes or salts thereof, protic acids such as trifluoromethane Esters of sulfonic acid, perchloric acid, protonic acid, especially esters of perchloric acid with lower aliphatic alcohols (for example, tertiary butyl perchlorate), anhydrides of protic acid, especially of perchloric acid with lower aliphatic carboxylic acid Mixed anhydrides (eg, acetyl perchlorate), or isopoly acids, heteropoly acids (eg, Phosphomolybdic acid), or triethyloxonium hexafluorophosphate, triphenylmethyl hexafluoro ARUZE diisocyanate, acetyl hexafluoro borate and the like. Among them, boron trifluoride or a coordination compound of boron trifluoride and an organic compound (for example, ethers) is the most common and suitable. The amount of the catalyst used in the present invention is 1 × 10 ⁻³ to 2 × 1 with respect to all monomers.
0 ^-1 mol% are preferred. Further, impurities having a reaction inhibiting effect, such as water, such as low molecular alcohols, acids (formic acid) it is preferably substantially free is of course, these are relative to the total amount of monomers, 1 × 10 ^-2 mol % Or less is preferable.

Although the molecular weight of the modified polyoxymethylene copolymer of the present invention can be adjusted to some extent by the molecular weight of the polyvinyl acetal resin added as a copolymer component, the molecular weight of the polyoxymethylene skeleton depends on the chain used during polymerization. It can be adjusted by the amount of the transfer agent. Typical examples of the chain transfer agent include a low molecular weight linear acetal compound, such as methylal, but any of the other known chain transfer agents (molecular weight regulators) in trioxane polymerization may be used.

The copolymerization method of the present invention can be carried out with the same equipment and method as the conventionally known trioxane copolymerization method. That is, any of a batch type and a continuous type can be used, and any of a solution polymerization, a melt bulk polymerization and the like may be used, but a continuous bulk polymerization using a liquid monomer and obtaining a solid powder bulk polymer with the progress of polymerization. The method is industrially common and preferred. In this case, if necessary, an inert liquid medium may coexist. As the continuous polymerization apparatus, a co-kneader, a twin-screw continuous extrusion mixer, a twin-screw paddle type continuous mixer, and other continuous polymerization apparatuses for trioxane that have been proposed so far can be used. It may be divided into steps or more. Particularly, those having a crushing function such that a solid polymer produced by a polymerization reaction can be obtained in a fine form are preferable. After the completion of the polymerization, the crude polymer discharged from the polymerization machine must be immediately brought into contact with a deactivator to deactivate the polymerization catalyst.
Examples of the basic compound for deactivating the polymerization catalyst in the present invention include ammonia, amines such as triethylamine and tributylamine, or alkali metal and alkaline earth metal hydroxides and salts, and other known catalyst deactivators. Is used. These deactivators are preferably dissolved in a cooling medium for the reaction product, such as water or an organic solvent such as cyclohexane, benzene, and toluene, and contacted with a catalyst simultaneously with cooling of the polymer to neutralize the same. It is particularly preferable to use an aqueous solution. At this time, it is preferable to grind and treat as fine powder, if necessary.

In the present invention, the copolymer in which the polymerization catalyst has been deactivated is further subjected to washing, separation and recovery of unreacted low-molecular monomers, drying, etc., if necessary, and further to a stabilization step, if necessary. Further, additives such as various co-stabilizers are added, and the mixture is melt-kneaded and pelletized to obtain a product. As the co-stabilizer, for example, an antioxidant such as a hindered phenol compound, an amidine compound (melamine or a derivative thereof, cyanoguanidine or the like), a nitrogen-containing compound such as a hindered amine or polyamide, an oxide of an alkali metal or an alkaline earth metal, An acid or formaldehyde absorbent such as a hydroxide, an inorganic or organic acid salt (for example, a carboxylate) is used alone or in combination of two or more.

The modified polyoxymethylene copolymer of the present invention, by itself, exhibits a remarkable effect on adhesion and welding to a polyolefin resin due to the polymer constitution as described above. Even when used as a composition obtained by melt-kneading with a system resin or a general polyoxymethylene resin, excellent effects are produced. Furthermore, it can be used as a composition obtained by melt-kneading with another thermoplastic resin. Here, examples of the other thermoplastic resin include, for example, a polyester resin, a polyamide resin, a polystyrene resin, a polyacrylic resin, a polyurethane resin, a fluororesin, and the like, which can be selectively used depending on the purpose. . Furthermore, in order to impart desired properties to the modified polyoxymethylene copolymer of the present invention, conventionally known additives, for example, stabilizers such as antioxidants and formaldehyde scavengers, lubricants, lubricants, nucleating agents And additives such as coloring agents such as dyes and pigments, release agents, antistatic agents, plasticizers and flame retardants. In addition, powdery or plate-like fillers such as glass fibers, carbon fibers, other inorganic or organic fibrous reinforcing materials, glass beads, glass flakes, and mica can also be appropriately compounded.

[0026]

The modified polyoxymethylene copolymer of the present invention has a polyvinyl acetal skeleton having a high affinity for polyolefin, so that it can be used as a polyolefin methylene resin component as compared with a conventional polyoxymethylene resin material. Can greatly improve the adhesion. In addition, due to the presence of the cross-linked structure inherent in polyvinyl acetal resin and the branched structure formed by the polyoxymethylene skeleton and the polyvinyl acetal skeleton by the polymerization reaction, mechanical properties are higher than those of linear polyoxymethylene (co) polymer. Strength is also improved.

[0027]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 6 A continuous polymerization reactor having a partially overlapped cross section of two circles, a jacketed barrel through which a heat (cooling) medium passes, and a plurality of paddles meshing with each other inside. 2
A continuous mixing propulsion reactor consisting of three rotating shafts was used. Hot water of 80 ° C. is passed through the jacket, and while rotating the two rotating shafts at a constant speed, trioxane, 1,3-dioxolane and polyvinyl acetal resin in the proportions shown in Table 1 from a supply port provided at one end thereof. Was supplied continuously. In addition, methylal as a molecular weight regulator was added in an amount of 100 p with respect to the total amount of monomers (including polyvinyl acetal resin).
pm. Further, a butyl ether solution of boron trifluoride dibutyl etherate was used as a catalyst, and the amount of boron trifluoride in terms of boron trifluoride was 1 to the total amount of monomers.
Copolymerization was carried out by continuous addition at a ratio of 00 ppm. The reaction product is discharged from a discharge port provided at the other end of the polymerization reactor, and immediately contains 0.1% of triethylamine.
And pulverized into water containing, and left overnight at room temperature to deactivate the catalyst. The obtained polymer flakes were collected by centrifugation, washed with warm water at 70 ° C., and dried at 50 ° C. for 2 days.

Next, 0.1% by weight of Irganox 1010 manufactured by Ciba Specialty Chemicals as an antioxidant was added to the resulting copolymer, and the resulting copolymer was mixed well using a twin-screw extruder equipped with a vent. The unstable portion was decomposed and removed by melting and kneading while deaeration to prepare a stabilized pellet-like polyoxymethylene copolymer.

The evaluation was carried out by the following method.
Shown in

[Evaluation Method] Adhesive strength: A flat plate (15 mm × 10 mm) was prepared using the prepared pellet-form polyoxymethylene copolymer under the conditions shown in Table 2.
0 mm x 2 mm). On the other hand, maleic anhydride-modified polyolefin (trade name: Tuffmer MP061 manufactured by Mitsui Petrochemical Industries, Ltd.) is used as the polyolefin resin material.
0) using a flat plate (15 mm × 100 mm) under the conditions shown in Table 2.
mm x 2 mm). Subsequently, the flat plates obtained above were heated and welded at 200 ° C. under a pressure of 1 kg and bonded to obtain a test piece for measuring adhesive strength.

As shown in FIG. 1, the adhesive strength was measured by peeling off the flat plates from the end of the bonded test piece and measuring the strength required for peeling.

Tensile strength: A tensile test piece was molded from the prepared pellet-shaped polyoxymethylene copolymer under the conditions shown in Table 2, and the tensile strength was measured according to ASTM D638.

Comparative Examples 1 to 3 When polymerization was carried out without adding any polyvinyl acetal resin (Comparative Example 1), the polyvinyl acetal resin was added in an amount of 0.00
Evaluation was made in the same manner as in Examples 1 to 6 for the case where polymerization was performed with 5% by weight added (Comparative Example 2) and the case where polymerization was performed with excessive addition (Comparative Example 3). The results are shown in Table 1.

The types of polyvinyl acetal in Table 1 are described below. Polyvinyl acetal type A: Polyvinyl formal (Vinilec K manufactured by Chisso Corporation) B: Polyvinyl butyral (Denka Butyral 2000-L manufactured by Denki Kagaku Kogyo Co., Ltd.)

[0036]

[Table 1]

[0037]

[Table 2]

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a test piece for measuring adhesive strength used in Examples and a situation of measuring adhesive strength.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA15B AA40 AA40B BB06 4F211 AA23E AK03 TA01 TH06 4J032 AA02 AA05 AB05 AB21 AF08

Claims (11)

[Claims] 1. A polyoxymethylene skeleton of 50 to 99.9.
9% by weight and a polyvinyl acetal skeleton of 0.01 to 50
% By weight as a structural unit. 2. The modified polyoxymethylene copolymer according to claim 1, wherein the polyvinyl acetal skeleton is a polyvinyl formal skeleton, a polyvinyl butyral skeleton or a skeleton in which these coexist. 3. The poly (vinyl acetal) skeleton is 100 to 100.
3. A polymer having a degree of polymerization of 3,000.
The modified polyoxymethylene copolymer according to the above. 4. The modified polyoxymethylene copolymer according to claim 1, wherein the polyvinyl acetal skeleton has at least 60% by weight of a vinyl acetal unit as a constitutional unit. 5. The modified polyoxymethylene copolymer according to claim 1, wherein the polyvinyl acetal skeleton has a vinyl alcohol unit of 0.1 to 40% by weight as a constitutional unit. 6. The method according to claim 1, wherein the polyoxymethylene skeleton is a polyoxymethylene copolymer skeleton.
The modified polyoxymethylene copolymer according to the above item. 7. The polyoxymethylene copolymer skeleton comprises:
Oxymethylene group as the main repeating unit, 0.05
The modified polyoxymethylene copolymer according to any one of claims 1 to 6, which has 10 to 10 mol% of a comonomer unit. 8. In the presence of a polyvinyl acetal resin,
Formaldehyde or trioxane is polymerized, or formaldehyde or trioxane and cyclic ether and / or
Or characterized by copolymerizing a cyclic formal,
A method for producing a modified polyoxymethylene copolymer having a polyoxymethylene skeleton and a polyvinyl acetal skeleton as constituent units. 9. A composite molded article obtained by heat-welding a molded article made of the modified polyoxymethylene copolymer according to claim 1 and a molded article made of a polyolefin resin. 10. A composite molded article obtained by using the modified polyoxymethylene copolymer according to any one of claims 1 to 7 and a polyolefin resin to form a composite by molding means. 11. The molding means is two-color molding.
The composite molded article according to the above.