JPH08311302A - Polyoxymethylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a new polyoxymethylene composition composed of a polyoxymethylene resin and an N-vinylcarboxylic acid amide (co)polymer and generating extremely little formaldehyde at 230 deg.C in air. CONSTITUTION: This polyoxymethylene resin composition is produced by compounding (A) a polyoxymethylene resin (preferably a polyoxymethylene homopolymer sealed its both terminals with acetyl groups) with (B) a compound selected from a poly(N-vinylcarboxylic acid amide) and a copolymer of an N-vinylcarboxylic acid and other vinyl monomer. The N-vinylcarboxylic acid amide used as a raw material for the component B is preferably N- vinylacetamide and the other vinyl monomer in the component B is preferably a polyfunctional unsaturated monomer. The amounts of the component A and the component B are preferably 50-99.99wt.% and 0.01-50wt.%, respectively. The objective composition is preferably pelletized with a vacuum-vented twin screw extruder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel polyoxymethylene resin composition. More specifically, the present invention provides a polyoxymethylene resin composition having an excellent low formaldehyde generation property especially under heating with air.

[0002]

2. Description of the Related Art Conventionally, polyoxymethylene resins have been widely used as engineering plastics having well-balanced mechanical properties and excellent wear resistance in various mechanical parts and OA equipment. However, this polyoxymethylene resin is extruded / formed because its monomer is a gas called formaldehyde.
Formaldehyde gas was generated during the molding process, and the working environment of the person who handles it was extremely bad. For that reason, measures such as strengthening ducts and gas masks were compelled. Under these circumstances, it has long been desired to develop a polyoxymethylene resin with low form generation.

The following are known heat stabilization methods for polyoxymethylene resins. First, JP-B-34-5440 discloses a method of adding a polyamide copolymer, and JP-B-39-21118 discloses a method of adding a polysulfonamide compound, and JP-B-42-17.
No. 107, a method of adding a copolymer of acrylamide and styrene or vinylnaphthalene, JP-B-4
No. 3-14329, a method of adding a copolymer with an acrylamide derivative, and Japanese Patent Publication No. 43-22670, a method of adding super polyamide, Japanese Examined Patent Publication No.
-1752 discloses a method of adding polyamide thiophenol, and JP-A-51-64558 discloses a melting point of 1
A method of adding a copolyamide at 80 ° C. or lower, a method of adding a polyamide and a fatty acid in JP-A-54-13551, and a method of adding an alkyl urethane and a carboxylic acid amide in JP-B-55-24465. JP-A-59-213752, JP-A-63-108051.
Japanese Patent Publication No. 7-1990 discloses a method of adding a poly-β-alanine copolymer, and Japanese Patent Publication No. 11625/1990 discloses a method of adding polytetramethylene adipamide particles pulverized to 10 microns or less. 33461 discloses a method of adding a non-melting polymer having an aldehyde reactive group.

However, in reality, the situation was still insufficient.

[0005]

Under these circumstances, the present invention has been made for the purpose of providing a polyoxymethylene resin composition which produces a remarkably small amount of formaldehyde at 230 ° C. in air. It is a thing.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that (A) polyoxymethylene resin and (B) poly (N-vinylcarboxylic acid amide) and N -A polyoxymethylene resin composition comprising one or more selected from the group consisting of a copolymer of vinylcarboxylic acid amide and another vinyl monomer was found to be excellent in low formaldehyde generation, and the present invention was based on this finding. Has been completed.

That is, the present invention is selected from the group consisting of (A) polyoxymethylene resin and (B) poly (N-vinylcarboxylic acid amide) and copolymers of N-vinylcarboxylic acid amide with other vinyl monomers. A polyoxymethylene resin composition comprising one or more of the above. Hereinafter, the present invention will be described in detail.

The polyoxymethylene resin used as the component (A) in the present invention is a polymer obtained by polymerizing a formaldehyde monomer or a cyclic oligomer such as a trimer (trioxane) or a tetramer (tetraoxane) thereof. Including homopolymers whose ends are blocked with ether or ester bonds, the above-mentioned trioxane or tetraoxane with ethylene oxide, propylene oxide, 1,3-
0.1 to 2 oxyalkylene units having 2 to 8 carbon atoms obtained by copolymerizing with a cyclic ether such as dioxolane, formal glycol, and formal diglycol
It is an oxymethylene copolymer containing 0% by weight, a oxymethylene block copolymer further having a branched molecular chain, and an oxymethylene block copolymer containing 50% by weight or more of a segment composed of oxymethylene units and 50% by weight or less of a different component segment.

Among the above-mentioned polyoxymethylene resins having a particularly low low form-forming effect, a polyoxymethylene homopolymer having both ends blocked with acetyl groups and a polyoxymethylene block having one end blocked with a different component. It is a copolymer. The polyoxymethylene block copolymer can be produced, for example, by the method disclosed in Japanese Patent Publication No. 2-24307.

A preferred block copolymer is a copolymer having one end blocked with an alkylene oxide adduct residue on an alcohol. Preferred alcohols constituting the alkylene oxide adduct residue to the alcohol constituting one end are aliphatic alcohols having 12 to 22 carbon atoms, and preferable alkylene oxides are propylene oxide and tetramethylene oxide. The number of moles of the alkylene oxide added to the alcohol is preferably 1 to 1,000. Furthermore, it is 1 to 50. The number average molecular weight excluding the terminal groups of this block copolymer is preferably 10,000 to 500,000.

Also, for a blend of a polyoxymethylene resin homopolymer having both ends blocked with acetyl groups and a polyoxymethylene block copolymer having one end blocked with an alkylene oxide adduct residue to alcohol. Shows good low formaldehyde generation. The content of the polyoxymethylene resin as the component (A) in the present invention is preferably 50 to 99.99% by weight. If this amount is less than 50% by weight or more than 99.99% by weight, the low formaldehyde generation property is lowered.

In the composition of the present invention, what is used as the component (B) is poly (N-vinylcarboxylic acid amide) or a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer. Poly (N-vinylcarboxylic acid amide) refers to JP-A-4-182437 and JP-A-4-182437.
The materials described in JP-A-230250 and JP-A-4-323213 can be used. Specifically, N-
It is a polymer obtained by polymerizing at least one N-vinylcarboxylic acid amide selected from vinylacetamide, N-vinylformamide, N-methylvinylacetamide and the like. A preferable average degree of polymerization is 100 to 500,000.

A preferred poly (N-vinylcarboxylic acid amide) is poly (N-vinylacetamide).
There is. Further, in the present application, even if a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer is added to the polyoxymethylene resin, the low formaldehyde-generating polyoxymethylene resin composition intended in the present application can be obtained similarly. To be Copolymers of N-vinylcarboxylic acid amide with other vinyl monomers are disclosed in JP-A-4-182437, JP-A-4-230250, and JP-A-4-323213.
It is possible to use those disclosed in the publication. N-
The other vinyl monomer in the copolymer of vinyl carboxylic acid amide and other vinyl monomer is specifically propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1. , Octene-1,
Nonene-1, decene-1, undecene-1, dodecene-
1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, or eicosene-1, aliphatic substituted vinyl monomers such as isobutylene, styrene, substituted styrene, etc. Aromatic vinyl monomers, vinyl acetate such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, acrylic Acrylic esters such as nonyl acid, dodecyl acrylate, stearyl acrylate, palmityl acrylate, methacrylic acid esters corresponding to the acrylic acid esters, glycidyl acrylic acid esters, (or methacrylic acid esters) , Hydroxyethyl acrylic acid ester (or methacrylic acid ester), hydroxypropyl acrylic acid ester (or methacrylic acid ester), hydroxybutyl acrylic acid ester (or methacrylic acid ester), etc., hydroxyl-based ester, acrylamide, methacrylamide, allylamine, Nitrogen-containing vinyl monomers such as vinyl-p-aminobenzene, acrylonitrile and N-vinyl-2-pyrrolidone, ether type monomers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether and butyl vinyl ether, ketones such as methyl vinyl ketone and ethyl vinyl ketone. Monofunctional unsaturated monomers such as system monomers, butadiene, cyclopentadiene, 1,
4-hexadiene, isoprene, divinylbenzene, divinyl ether, ethylene glycol diacrylic acid ester (or methacrylic acid ester), butylene glycol diacrylic acid ester (or methacrylic acid ester), butanediol diacrylic acid ester (or methacrylic acid ester) , Hexanediol diacrylic acid ester (or methacrylic acid ester), oligoethylene glycol diacrylic acid ester (or methacrylic acid ester), polyalkylene glycol diacrylic acid ester (or methacrylic acid ester), trimethylolpropane diacrylic acid ester ( Or methacrylic acid ester), trimethylolpropane triacrylic acid ester (or methacrylic acid ester), allyl alcohol Acrylic acid esters (or methacrylic acid ester), diallyl maleate, Jiarirufumaru acid esters, Jiariruitakon acid esters, N, N'-methylene bisacrylamide, N, N '
-Diacrylamide (or dimethacrylamide) such as ethylenebisacrylamide, N, N'-methylenebis (N-vinylacetamide), N, N'-ethylenebis (N-vinylacetamide), N, N'-propylenebis ( N, N'-alkylenebis (N-vinylcarboxylic acid amide), tetra, such as N-vinylacetamide), N, N'-butylenebis (N-vinylacetamide), N, N'-hexylenebis (N-vinylacetamide) There are polyfunctional unsaturated monomers such as allyloxyethane, methylolpropane diallyl ether, N, N '-(diacetyl) -N, N'-(divinyl) -1.3-bis (aminomethyl) cyclohexane.

A preferred copolymer of N-vinyl carboxylic acid amide and other vinyl monomer is a cross-linked product obtained by copolymerizing with a polyfunctional unsaturated monomer because a low formaldehyde generation property can be obtained. Among the copolymers of N-vinylcarboxylic acid amide and other vinyl monomers, it is preferable to use 70% by weight or less of the other vinyl monomer. 70
This is because the low formability is lowered when the content exceeds the weight percentage.

As a method for polymerizing poly (N-vinylcarboxylic acid amide) and a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer in the present application, Japanese Patent Application Laid-Open No. 4-1
The radical polymerization methods described in JP-A-82437, JP-A-4-230250, and JP-A-4-323213 are preferable. Further, in the present application, one or more selected from poly (N-vinylcarboxylic acid amide) and a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer can be added to the polyoxymethylene resin. .

The poly (N-vinylcarboxylic acid amide) or the copolymer of N-vinylcarboxylic acid amide and another vinyl monomer of the present invention preferably has an average particle size of 10 μm or less. More preferably, it is 5 μm or less. Furthermore, it is 1 μ or less. Further, the poly (N-vinylcarboxylic acid amide) or the copolymer of N-vinylcarboxylic acid amide and another vinyl monomer of the present application is
It is preferable to add 0.01 to 50% by weight to the entire composition. This is because the low formaldehyde generation property is reduced when the amount is less than 0.01% by weight or exceeds 50% by weight.

The composition of the present invention can be melt kneaded and pelletized at a temperature higher than the melting point of the polyoxymethylene resin used by using a commonly used melt kneader. As the melt-kneader, a kneader, a roll mill, a single-screw extruder,
A twin-screw extruder and a multi-screw extruder can be mentioned, but the vent pressure was reduced in consideration of oxygen blocking and working environment.
Pelletizing with a shaft (two-row) extruder is preferable.

If desired, the composition of the present invention may be one conventionally used as a plastic additive, for example, a hindered phenol, a hindered amine, an ultraviolet absorber, talc, etc. within a range that does not impair the object of the present invention. Inorganic fillers, pigments, carbon black, release agents, lubricants may be added, and additional components usually used in polyoxymethylene resins such as polyamide and poly-β-alanine copolymers. , Polyacrylamide, melamine, melamine-formaldehyde condensate, calcium stearate and the like may be added.

The composition of the present invention comprises OA equipment, automobile gears, bearings, levers, key stems, cams, ratchets,
It can be used for rollers, VTR guide rollers, side plates, cam gears, copier gears, LBP paper feed parts, toner stirring gear trains, cartridge gears, CD-ROM parts, etc.

[0020]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

[0021]

Examples 1 to 5 Intrinsic viscosity 1.2 (α-pinene 2% by weight) by the method described in U.S. Pat. No. 2,998,409.
Value measured at 60 ° C. for a solution prepared by dissolving 0.1% by weight of a polymer in p-chlorophenol containing
Melt Index [ASTM D1238-57
(E)] Polyoxymethylene homopolymer powder having both ends acetylated at 10 g / 10 min was dried at 80 ° C. for 3 hours, and used as an antioxidant, Irganox 2 manufactured by Ciba Gaggy.
Polyacetal resin homopolymer containing 0.3 part of 45 and poly (N produced by the method described in JP-A-4-182437, JP-A-4-230250, and JP-A-4-323213 shown in Table 1 -Vinyl carboxylic acid amide) or N-vinyl carboxylic acid amide and a copolymer of other vinyl monomer are blended under a nitrogen atmosphere, and a twin screw vent extruder of L / D25 set to 200 ° C. is used, Screw-rotation speed 100 rpm, discharge rate 3
melt-kneading under conditions of kg / hour, maximum resin temperature 205 to 210 ° C., kneading time (residence time) 0.5 to 0.7 minutes,
A resin composition having the composition shown in Table 1 was prepared, further pelletized and dried at 80 ° C. for 3 hours.

Next, 3 g of the pellets are put into an aluminum container and 2 are put under an air stream (6 N liter / min.).
The total amount of formaldehyde gas generated when melt-heated at 30 ° C. for 60 minutes was introduced into a 1 mol / liter sodium sulfite solution and titrated with 0.01N hydrochloric acid to measure the amount of formaldehyde gas generated (sample unit). Formaldehyde gas pp generated per weight
m).

The results are shown in Table 1.

[0024]

Comparative Examples 1 to 3 The same test as in Example 1 was conducted except that the composition shown in Table 2 was used instead of the poly (N-vinylcarboxylic acid amide) in Example 1, and the amount of formaldehyde gas generated was determined. It was measured. Table 2 shows the results.

[0025]

Example 6 Intrinsic viscosity of 1.1 and melt index of 10 by the method described in US Pat. No. 3,027,352.
A test was conducted in the same manner as in Example 2 except that a polyoxymethylene copolymer containing 2.8% by weight of oxyethylene groups in g / 10 minutes was used as the polyoxymethylene resin, and the amount of formaldehyde gas generated was measured.

As a result, the amount of formaldehyde gas generated was 90 ppm. The amount of formaldehyde gas generated was 1500 ppm in the composition in which the copolymer of N-vinylcarboxylic acid amide and other vinyl monomer was not added.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

Industrial Applicability According to the present invention, a low formaldehyde generation rate (in air) more than that hitherto known is obtained.

Claims (5)

[Claims] 1. One selected from the group consisting of (A) polyoxymethylene resin and (B) poly (N-vinylcarboxylic acid amide) and a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer. A polyoxymethylene resin composition comprising the above. 2. The polyoxymethylene resin according to claim 1, wherein the polyoxymethylene resin is a polyoxymethylene homopolymer having both ends blocked with acetyl groups or a polyoxymethylene block copolymer having one end blocked with a different component. Resin composition. 3. The polyoxymethylene resin composition according to claim 1, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. 4. The polyoxymethylene resin composition according to claim 1, wherein the copolymer of N-vinylcarboxylic acid amide and another vinyl monomer is a crosslinked product. 5. The number average particle size of poly (N-vinylcarboxylic acid amide) or a copolymer of N-vinylcarboxylic acid amide and another vinyl monomer is 10 μm or less. The polyoxymethylene resin composition described.