JP2971533B2 - Antistatic methacrylic resin composition with excellent heat stability - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an antistatic methacrylic resin composition having excellent heat stability.

[Conventional technology]

Methacrylic resin is widely used for lighting fixtures, signboards, various decorative articles, etc. because of its excellent transparency, good mechanical properties, workability, and beautiful appearance of molded articles.

However, methacrylic resin has the drawback that surface resistivity is high, static electricity induced by contact, friction, etc. is difficult to escape and disappear, and dust and the like adhere to the surface of the molded product during use and the beautiful appearance is easily damaged. I have.

Conventionally, as a method for eliminating such electrostatic damage, a method of blending sodium sulfonic acid and glycerin monofatty acid ester with methacrylic resin (Japanese Patent Publication No. 60-38415), a method of blending glycerin monofatty acid ester and a specific phosphorus compound (JP-A-59-93745), a method of blending a higher fatty acid monoglyceride with a specific phosphorus compound and a polyalkylene glycol (JP-B-53-15896), a method of preparing high-purity glycerin monolaurate and a specific alkanol or glycerin. Kneading method (Japanese Unexamined Patent Publication No.
No. 7), a method of adding a boric acid ester of glycerin monofatty acid ester (Japanese Patent Application Laid-Open No. 52-102362), a method of compounding a quaternary salt of alkyl sulfate, glycerin monofatty acid ester and a complex ionic organic boron compound ( Tokiko Sho 61
No. -40258), a method in which a higher fatty acid monoglyceride is separately added during suspension polymerization and kneading (Japanese Patent Publication No. 59-49935), a method in which a polyhydric alcohol fatty acid ester and 2-hydroxyl are added to a thermoplastic resin. A method of adding an alcohol (Japanese Patent Publication No. 61-398) is disclosed.

However, in all of these methods, a part of the added antistatic agent is thermally decomposed due to the heat history received during molding processing (injection molding, extrusion sheet molding, etc.), and silver, foaming, poor appearance gloss and the like are generated. Or
Discoloration before and after molding and reduction of antistatic ability
In some cases, there is a problem that the antistatic ability is lost in a part of the molded article.

[Problem to be solved by the invention]

An object of the present invention is to solve the above-mentioned problems of the conventional technology. That is, an object is to provide a composition which imparts a stable antistatic ability to a methacrylic resin, and has good stability against thermal decomposition due to a heat history received during molding, and which has greatly improved moldability. .

[Means for solving the problem]

The present invention relates to (1) (a) 100 parts by weight of a methacrylic resin having 60% by weight or more of methyl methacrylate, (b) 0.1 to 5 parts by weight of an alkali metal or alkaline earth metal salt of alkyl sulfonic acid, and (c) thioether-based antioxidant. An antistatic methacrylic resin composition having excellent heat stability, comprising 0.1 to 5 parts by weight of an agent; (2) the composition described in the above item (1); and (d) a methacrylic resin in the composition; a) 100
An antistatic methacrylic resin composition comprising 5 parts by weight or less of a phenolic antioxidant per part by weight and having excellent heat stability.

In the present invention, an alkali metal or alkaline earth metal salt of an alkylsulfonic acid is used as an essential component as an antistatic agent.

Specific examples of the alkyl sulfonate of the general formula _{^{R 1 SO 3 - · X +}} (R 1 is an alkyl group of C ₈ ~C _20, X ⁺ is ^{Na +, Li +, Ca 2+} , Mg 2 ⁺ Represents an alkyl sulfonate represented by the general formula (X is 0-9, R ₂ is a C ₄ -C ₁₅ hydrocarbon group, and X ⁺ is N
a ⁺ , Li ⁺ , Ca ²⁺ , and Mg ²⁺ are shown. ) A sulfoacetate type anionic surfactant represented by the formula: (X and Y are 0 to 9, R ₃ and R ₄ are C _{4 to} C ₁₅ hydrocarbon groups, and X ⁺ represents Na ⁺ , Li ⁺ , Ca ²⁺ , Mg ²⁺ ). And sulfosuccinate type anionic surfactants.

Of particular preference, the general formula _{^{R 1 SO 3 - · Na +}} (. R 1 is showing an alkyl group of C ₁₀ -C ₁₆₎ alkyl sodium sulfonate represented by, further R ₁ represents a linear Alternatively, a branched alkyl group is preferable, and a mixture thereof is more preferable.

In the present invention, a thioether antioxidant and, if necessary, a phenolic antioxidant are used as the heat stabilizer.

Examples of thioether-based antioxidants include dilauryl thiodipropionate, distearyl thiodipropionate, distearyl-β, β'-thiodibutyrate, laralyl stearyl thiodipropionate, and dimyristyl thiodipropionate. , Ditridecyl thiodipropionate, (MARK AO-412S; Adeka Argus Chemical Co., Ltd.) (MARK AO-23; manufactured by Adeka Argus Chemical Co., Ltd.). Particularly preferably, MARK AO-412S and MAR
K AO-23.

A typical phenolic antioxidant is β- (3,5-
Di-tert-butyl-4-hydroxyphenyl) -propionic acid-n-octadecyl ester, pentaerythritol
Tetra- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,3,5-tris- (3,5-
Di-tert-butyl-4-hydroxybenzyl) -isocyanurate, N, N'-hexamethylene-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionamide], triethylene glycol-bis − [3- (3-t
Butyl-5-methyl-4-hydroxyphenyl) -propionate], 1,6-hexanediol-bis- [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 2,4-bis- (n-octylthio) -6
-(4-hydroxy-3,5-di-t-butylanilino)-
1,3,5-triazine, 2,2-thio-diethylenebis- [3
-(3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 2,2-thiobis- (4-methyl-6-
t-butylphenol), 3,5-di-tbutyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5
-Trimethyl-2,4,6-tris- (3,5-ditertbutyl-4
-Hydroxybenzyl) benzene and the like.

Examples of the methacrylic resin used in the present invention include a polymer obtained by copolymerizing 60% by weight or more of methyl methacrylate and 40% by weight or less of another copolymer vinyl monomer. Or two or more of them may be used in combination.

Examples of the copolymerizable vinyl monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylic acid, methacrylic acid, 2-hydroxy acrylate, ethylene glycol monoacrylate, glycerin monoacrylate, and styrene. Or α
Copolymerizable monomers such as -methylstyrene.

In the above case, the proportion of methyl methacrylate contained in the polymer is preferably at least 60% by weight, more preferably at least 80% by weight. If the proportion of methyl methacrylate is less than 60% by weight, mechanical properties, particularly flexural modulus, tend to decrease.

60% by weight of methyl methacrylate used in the present invention
As a more preferred example of the methacrylic resin having the above,
There is a resin obtained by blending an acrylic multi-stage polymer with the methacrylic resin. The acrylic multi-stage polymer used here is disclosed in JP-A-53-58554, JP-A-55-94917, JP-A-61-32346, etc. A multi-stage polymer produced by a multi-stage sequential polymerization method in which an elastic layer and an inelastic layer are alternately formed around a core material.

More specifically, an acrylic multi-stage having a polymer elastic layer mainly composed of alkyl acrylate and a polymer inelastic layer mainly composed of methyl methacrylate alternately surrounding a polymer core material mainly composed of methyl methacrylate ( (Multilayer) polymer, and preferably has a weight average particle size of 0.1 to 1 μm. Further, an acrylic multi-stage (multi-layer) polymer having an intermediate layer in which alkyl methacrylate gradually increases between the elastic layer and the inelastic layer is also effective.

In the present invention, the addition amount of the alkali metal or alkaline earth metal salt of the alkyl sulfonic acid is a methacrylic resin.
0.1 to 5 parts by weight, preferably 0.4 to 4 parts by weight, per 100 parts by weight. If the amount is less than 0.1 part by weight, the antistatic effect is insufficient, and if it exceeds 5 parts by weight, peeling occurs in the molded product,
There is a problem that the mold becomes dirty during molding.

In the present invention, the addition amount of the thioether-based antioxidant is 0.1 to 5 parts by weight based on 100 parts by weight of the methacrylic resin. If it is less than 0.1 parts by weight, the heat stabilizing effect is insufficient,
Exceeding 5 parts by weight is not preferable because the mold is stained during molding and the resin is colored.

On the other hand, the addition amount of the phenolic antioxidant is 0 to 5 parts by weight based on 100 parts by weight of the methacrylic resin. In the present invention, a phenolic antioxidant is not an essential component, but it is desirable to use 5 parts by weight or less, preferably 0.1 to 5 parts by weight, in combination with a thioether-based antioxidant, since the effect of using the phenolic antioxidant is recognized. . At that time, the weight ratio of the phenolic antioxidant to the thioether antioxidant was 1/9 to 9
It is more preferred that the ratio be in the range of / 1.

The composition of the present invention may further contain an antistatic agent, an antistatic auxiliary agent, other additives, a pigment, a light diffusing agent, and a filler.

Specific examples of the antistatic agent include fatty acid esters of glycerin, mono-, di-, triethanolamine, amide compounds of diethanolamine and higher fatty acids, and ethylene oxide adducts thereof, among which diethanolamine and higher fatty acids are particularly preferred. Amide compounds are preferred because of their high combined effect.

Examples of the antistatic auxiliary include specific phosphorus compounds disclosed in JP-B-61-16770, higher alcohols, ethylenebisstearylamides, and alkali metal salts of stearic acid. (R ₁ , R ₂ , and R _{3 each} represent an aromatic compound) and a small amount of a higher alcohol and a phosphorus compound represented by the formula (I) are extremely desirable because the combined effect is recognized.

The resin composition of the present invention can be obtained by melt-kneading a methacrylic resin, an alkyl sulfonate, a thioether-based antioxidant, a phenol-based antioxidant, and if necessary, other additives with an extruder or the like. At that time, the alkyl sulfonate, thioether-based antioxidant, phenol-based antioxidant, and other additives are mixed in advance and then melt-kneaded with the methacrylic resin, or melted after preparing a master batch. Kneading is more preferred because the additives are well intermingled and dispersed.

The resin composition of the present invention thus obtained can be molded by a method such as injection molding, extrusion molding, blow molding, vacuum molding, or the like to obtain a molded product. The molded article thus obtained has a stable antistatic ability and also has a high molding stability especially against the heat history received during molding processing such as injection molding and extrusion sheet molding.

〔Example〕

 Next, the present invention will be described in more detail by way of examples.

Examples 1 to 9 and Comparative Examples 1 to 4 Methacrylic resin composed of 95% by weight of methyl methacrylate and 5% by weight of methyl acrylate, sodium alkylsulfonate (Electrostripper PC-2, manufactured by Kao Corporation), thioether-based antioxidant (MARS AO-412
S, manufactured by Adeka Argus Chemical Co., Ltd.), phenolic antioxidant (MARS AO-60, Adeka Argus Chemical Co., Ltd.)
And other additives were premixed in the proportions shown in Table 1.

This mixture was pelletized at 250 ° C. using a 40φ extruder, and then dried at 80 ° C. for 5 hours. Next, using a 3 ounce injection molding machine, a molding cycle at a temperature of 260 ° C. and one shot 5
Injection molding was performed at a mold temperature of 70 ° C. to obtain a 150 × 150 × 3 mm flat plate. After conditioning the plate at a constant temperature of 23 ° C. and 50% RH for 24 hours, the surface resistance and half-life were measured. Table 1 shows the results.

The surface resistance was measured using a super insulation meter SM-10 (manufactured by Toa Denpa Kogyo), and the half-life was measured using a static honest meter (manufactured by Shishido Shokai).

In addition, as a result of analyzing the water-soluble component of sodium alkyl sulfonate (Electro-Stripper PC-2, manufactured by Kao Corporation) under the following conditions, it was found that C _{11 to} C ₁₅ linear and branched alkyl sulfonic acids were used. mixture of sodium, in particular C ₁₂ -C ₁₄
It has been found that a mixture of the above-mentioned linear and branched sodium alkyl sulfonates is a main component. The water-soluble component is 82
% By weight.

<Analysis conditions> The water-soluble component solution was evaporated to dryness while blowing with nitrogen at 100 ° C, and then trimethylsilylation was performed to convert non-volatile compounds into volatile compounds, which were then applied to gas chromatography / mass spectrometry (GC / MS). Identified and quantified. GC /
The conditions for the MS method were as follows: Model; Hewlett-Packard (GC; HP5890, MS; HP5970B) column; DB-1 capillary, length 30 m, injection temperature; 300 ° C, carrier: helium.

(Notes) 1) Sodium alkylsulfonate is electrostripper PC-2 2) Thioether antioxidant is MARK AO-412S 3) Phenol antioxidant is MARK AO-60 4) Phosphite is MARK 2112 5) High grade Alcohol is a mixture of 50% by weight of stearyl alcohol and cetyl alcohol. 6) Jutanolamide is diethanolamide stearic acid. 7) Variation in antistatic ability is 150 × 150 × 3 mm plate.
Measure the surface resistance value of 5 points at the corner and center x 10 points on both sides,
The minimum and maximum values were compared.

Examples 10 to 17 and Comparative Examples 5 to 8 Pellets were produced at the compounding ratios shown in Table 2, and pellets were prepared at 80 ° C.
Dried for hours. Next, extrusion sheet molding was performed using a screw diameter 60 mmφ, L / D = 32 vented single screw extruder,
Die is fishtail type, lip opening is 3mm, extruder temperature and die temperature are 270 ℃, polishing roll temperature is 130 ℃, sheet thickness is targeted at 2.0mm by polishing roll clearance at die exit. The adjustment was performed while adjusting the discharge amount of the extruder. The sheet obtained here was adjusted and measured in the same manner as in Examples 1 to 9. Table 2 shows the results.

The bank is a resin pool that stores a small amount of molten resin at the entrance between the polishing rolls in order to make the thickness of both sides and the center of the sheet uniform. If air bubbles enter this bank, it may cause poor appearance of the sheet, etc.
Product value is completely lost.

(Note) 1) Methacrylic resin consisting of 95% by weight of methyl methacrylate and 5% by weight of ethyl acrylate 2) Electrostripper PC for sodium alkylsulfonate 3) MARK AO-23 for thioether antioxidant 4) Phenolic antioxidant Is MARK AO-30 5) Phosphite is MARK 329K 6) Higher alcohol is NAA-42 (Nippon Yushi Co., Ltd.)
7) Fatty acid ester of glycerin was glycerin monostearate 8) The difference in surface resistance value on both sides of the sheet was compared.

Examples 18 to 22 and Comparative Examples 9 to 12 Preparation of acrylic multistage polymer; 250 parts of ion-exchanged water, 1 part of sodium sulfosuccinate, and 0.05 part of sodium formaldehyde sulfoxylate were charged into a reaction vessel equipped with a condenser. After stirring under a nitrogen stream, 10 parts of MMA and 0.05 parts of AMA are charged.

In MMA, 0.1% of CHP is dissolved in MMA. For all monomers added in the subsequent steps, 0.1% C
HP is included.

The temperature of the reaction vessel is increased to 70 ° C. while stirring at a rotation speed of 200 rpm under a nitrogen stream, and the mixture is stirred for 30 minutes, whereby the polymerization of the layer (A) is completed. Followed by 10 parts MMA, 10 parts BuA, 0.10 parts AM
Add the mixture of A over 10 minutes and hold for another 40 minutes to complete the second stage polymerization. Then 38 parts BuA,
The third layer component consisting of 0.20 parts of AMA and 2.0 parts of BD is added over 10 minutes and held for 40 minutes to complete polymerization of the third layer. Next, a fourth layer component consisting of 10 parts of MMA, 10 parts of BuA, and 0.10 parts of AMA is dropped in 10 minutes, and the polymerization of the rubber layer (B) is completed when the composition is kept for 50 minutes.

Further, an outermost layer (C) component composed of 10 parts of MMA and 0.03 parts of n-OSH was added and polymerized in 10 minutes to synthesize an acrylic multi-stage polymer (B-1) composed of five layers.

The observation of the sampled sample after polymerization of each layer by an electron microscope confirmed that no new particles were generated at the time of polymerization of each layer, and complete seed polymerization was performed.

The resulting emulsion was subjected to coagulation, coagulation, and solidification reactions using aluminum chloride, and after washing with water and water, a dried acrylic multistage polymer (B-1) was obtained.

 The abbreviations are as follows.

Methyl methacrylate: MMA Butyl acrylate: BuA Allyl methacrylate: AMA 1,3-butylene methacrylate: BD Cumene hydroperoxide: CHP n-octyl mercaptan: n-OSH Using the acrylic multistage polymer prepared above, Table 3 The pellets were produced at the mixing ratio shown in Table 1 and dried at 80 ° C for 5 hours. Next, an extruded sheet was formed under the same conditions as in Examples 10 to 17 to obtain a sheet. The results are summarized in Table 3.

(Note) 1) Methacrylic resin consisting of 90% by weight of methyl methacrylate and 10% by weight of methyl acrylate 2) The sodium alkyl sulfonate is Statexan K
-1 (manufactured by Bayer AG) 3) thioether antioxidant is MARK AO-412S 4) phenolic antioxidant is MARK AO-20 5) phosphite is MARK 1178 6) Higher alcohol is calcol (Kao) 7) Other additives TEA; triethanolamine DEA; diethanolamine SS-10; sorbitan monostearate MYS-55; polyethylene glycol monostearate BS-20: polyoxyethylene stearyl ether (Nikko Chemicals Co., Ltd. TAMDS-4; polyoxyethylene alkylamine stearamide (manufactured by Nikko Chemicals Co., Ltd.) TDP-10; polyoxyethylene alkyl ether phosphate (manufactured by Nikko Chemicals Co., Ltd.) Tables 1 and 2 The following is clear from the results in Tables and Table 3. The resin compositions of the present invention (Examples 1 to 22) all have stable antistatic ability and have good thermal stability at the time of injection-molded extruded sheet molding. No trouble occurred.

On the other hand, as shown in Comparative Examples 1 to 12, in the resin composition to which the thioether-based antioxidant was not added, not only was the variation in the antistatic ability recognized, but also trouble during molding frequently occurred.

〔The invention's effect〕

As described above, the methacrylic resin composition of the present invention has a stable antistatic property, and also has excellent injection molding stability and extruded sheet molding stability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI C08K 5:36 5:42) (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 33/06-33/14 C08L 9/00-9/10 C08L 51/00-51/06 C08K 5/00-5/59

Claims (2)

(57) [Claims] (A) 60% by weight of methyl methacrylate
100 parts by weight of methacrylic resin having the above (b) Alkali metal or alkaline earth metal salt of alkyl sulfonic acid 0.1 to 5 parts by weight (c) Thioether antioxidant 0.1 to 5 parts by weight A methacrylic resin composition having an inhibitory property. 2. The composition according to claim 1, which comprises: (d) 5 parts by weight or less of a phenolic antioxidant per 100 parts by weight of the methacrylic resin component (a) in the composition; Excellent antistatic methacrylic resin composition.