JPS6028314B2 - thermoplastic resin composition - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD This invention relates to a novel thermoplastic resin composition.

More specifically, the present invention relates to a novel thermoplastic resin composition that has excellent paintability, impact resistance, and processability.
ABS resin has traditionally been widely used as a material for various molded products in parts for electrical appliances, automobiles, office equipment, etc. due to its excellent balance of performance. It is also an important use to compensate for the lack of strength.

Various paints have been developed for this purpose and are used in molded products while taking advantage of the characteristics of resin. This has become a problem as it causes partial non-uniformity and a decrease in strength, resulting in a decrease in commercial value. As a countermeasure for this, it is common to change the molding process or coating conditions, but the selection of conditions for improvement is narrow and workability is also restricted, so it is unavoidable to use paint with inferior performance. The reality is that there are many examples where it is used.

In order to solve these drawbacks, we investigated the structure of ABS resins and found that the amount of unsaturated nitrile monomer has a significant effect on improving the paintability, leading to the present invention.

Generally, as the unit content of unsaturated nitrile monomer increases,
Although it is effective in improving the solvent resistance of polymers, it is known to reduce impact strength and fluidity. However, after a detailed study of the relationship between the content of unsaturated nitrile monomer units and paint resistance, we found that in rubbery dispersion ABS resin,
In other words, a composition produced by mixing a graft polymer with a large unit content of side chain unsaturated nitrile monomer with a graft polymer with a small unit content of side chain unsaturated nitrile monomer, It has been found that the coating properties are superior to compositions prepared from graft polymers having an average content of side chain unsaturated nitrile monomer units. This has made it possible to produce resin compositions with good paintability that are free from the restrictions imposed by polymers with a high unsaturated nitrile monomer unit content. An object of the present invention is to provide a new thermoplastic resin composition that has excellent paintability, impact resistance, and processability. The gist of this is that the gel content is 70% or more and the average particle diameter is 0.2.
Unsaturated nitrile monomer units in the side chain portion of a graft polymer obtained by polymerizing a monomer consisting of an unsaturated nitrile compound and an aromatic vinyl compound in the presence of a rubbery polymer having a molecular weight or more. One or more graft polymers having a content of 20 to 32% and one or more graft polymers having a content of 32 to 37% unsaturated nitrile monomer units in the side chain portion, unsaturated nitrile monomer units. In a composition comprising one or more copolymers containing 20 to 37% of monomer units and the remainder being aromatic vinyl monomer units, unsaturated nitriles in the side chain portions of all graft polymers A thermoplastic resin characterized in that the content of monomer units is 28 to 35% and is mixed so that the content of unsaturated nitrile monomer units in the total free polymer is 22 to 35%. To provide a composition. The present invention will be explained in detail below.

The rubber-based polymer used in the present invention has a gel content of 7.0% in order to obtain a resin composition with good processability and excellent impact strength development.
It is necessary that the polymer is based on a gen monomer having an average particle size of 0.24 or more and an average particle size of 0.24 or more.

When this rubbery polymer is used, uniform and stable dispersion of the polymer particles in the resin composition can be maintained up to a high content, making it possible to create a variety of compositions with a wide range of physical properties, such as excellent impact strength, It is possible to produce thin molded products for painting that not only have good appearance but also good workability. The monomer forming the rubbery polymer is a diene compound represented by ptagene, and a monopolymer copolymerizable with diene can be used as a part of it, such as an aromatic vinyl compound represented by styrene, Included are unsaturated nitriles represented by acrylonitrile, unsaturated esters represented by methyl acrylate, and crosslinkable polyfunctional monomers such as tri-IJ lucyanurate. A rubbery polymer is then produced by emulsion polymerization using the above monomers, and conventionally known methods can be used. The graft polymer in the resin composition according to the present invention can be produced by a conventional method, in which a monomer mixture consisting of an unsaturated nitrile and an aromatic vinyl compound is polymerized in the presence of the rubbery polymer.

There are various forms of polymerization, such as emulsion polymerization in which the above-mentioned rubbery polymer is used as it is, suspension or bulk polymerization in which the rubbery polymer is converted into a monomer, and a complex method in which it is converted to another form during polymerization. I can find out. In the graft polymer of the present invention, the content of unsaturated nitrile monomer units in the side chain polymer bonded to the rubbery polymer (abbreviated as GN below the weight percentage of the opposite side chain polymer) is 32 to 37%. One type of graft polymer and
G
If N is 28 to 35%, the paintability of the ABS resin composition using this is good. In other words, the paintability of the Amo resin composition using a graft polymer with a CN of less than 32% is poor, whereas the paintability of a graft polymer with a GN of 32 to 37% and a graft polymer with a GN of 20 to 32% is poor. Mix the polymers,
Even if its GN is 28-32%, its paintability is much better. This makes it possible to produce a composition that has improved paintability and has practical impact strength.
In the resin composition according to the present invention, the copolymer blended into the graft polymer has a content of unsaturated nitrile monomer units (hereinafter abbreviated as FN) of 20 to 37%, and the remainder is aromatic vinyl monomer units. It is a quantitative unit.

In addition, the content of unsaturated monomer units (hereinafter abbreviated as MN) in the free polymer that is the matrix of the resin composition must be 22 to 35%, with the remainder being aromatic vinyl monomer units. It is. By setting the GN in the above range, an ABS resin composition with good paintability can be obtained, but by setting the MN to 35% or less, the impact strength and fluidity are good, resulting in an overall useful composition. . MN
If the GN is less than 22%, the paintability will be poor even if the GN is 32% or more, and only a composition with low impact strength will be obtained. FN is 3
When the FN exceeds 7%, the paintability is good, but the impact strength or fluidity of the composition using this composition is significantly reduced, and the commercial value as a resin composition is lost, and when the FN is 20%, the composition impact strength is insufficient. The monomers used in the production of the graft polymer of the present invention and the copolymer used for blending are unsaturated nitriles and aromatic vinyls. Examples of unsaturated nitriles include acrylonitrile (methacrylonitrile) and aromatic vinyls. Compounds include styrene, Q
- Methyl styrene and other monomers include unsaturated ester methyl (meth)acrylate.

These monomers can be charged into the polymerization system in any manner such as mixing, partially mixing individually or all at once, dividing, continuously, or in combination thereof. Inorganic and organic peroxides and azo compounds can be used as polymerization initiators, but various redox systems are also effective in emulsion polymerization.

Depending on the polymerization method, inorganic or organic suspension stabilizers, emulsifiers,
A viscosity modifier is required, and it is also possible to add a polymerization degree modifier, an antioxidant, a lubricant, etc. In addition, it is desirable from the viewpoint of quality and economy to expel and recover the monomer by reducing pressure, blowing an inert gas, or heating during and/or after the polymerization. In addition, as long as the graft polymer and compounding copolymer are within the above composition range, it is possible to use a mixed combination of more than one type of each type.If both polymers are compounded by emulsion polymerization, a latex mixture can also be used. The method can also be arbitrarily selected depending on the form of the polymer depending on the polymerization method, and stabilizers, plasticizers, lubricants, colorants, etc. can be further added at a certain stage after polymerization.

Next, the measurement of unsaturated nitrile monomer units will be explained.

GN is dispersed and dissolved in acetone after removing the cyclohexane soluble portion from the mixed graft polymer.

Next, it is centrifuged, the insoluble matter is decomposed by ozonation, the rubbery polymer is removed, and the graph portion is taken out. The concentration of unsaturated nitrile monomer units is then determined from the nitrogen analysis of this portion and expressed as a weight percentage in the graph portion. MN is expressed as a unit concentration of unsaturated nitrile single unit in weight percentage in the free polymer (acetone soluble part) after separating the acetone soluble part from nitrogen analysis. FN is also shown as the content of unsaturated nitrile monomer units based on nitrogen analysis of the copolymer for blending. The present invention will be explained below with reference to Examples.

Graft 1 Acrylonitrile (hereinafter abbreviated as AN) and styrene (hereinafter S
A graft polymer (abbreviated as G-1) with a rubber content of 30% and GN of 27.0% was obtained by emulsion polymerization with the addition of 2 parts of butylated hydroxytoluene per 10 parts of rubber, followed by drying.
).

Graft 2 Increased AN in Graft 1 to 30% rubber content, GN
A 31.8% graft polymer (G-2) is obtained.

Graft 3 Increase AN in Graft 2 to make rubber content 30%, GN
A 33.0% graft polymer (G-3) is obtained.

Graft 4 In Graft 1, the amount of rubber was reduced by half and the amount of AN increased to obtain a graft polymer (G-4) with a rubber density of 15%, GN of 28.3%, and MN of 29.2%.

Copolymerization 1: Suspension polymerize AN and ST, wash and dry to obtain FN23.0
% copolymer (F-1) is obtained.

Copolymerization 2 Increase AN in Copolymerization 1 and perform the same procedure as FN2
A 6.5% copolymer (F-2) is obtained. Copolymerization 3 Increase AN in copolymerization 2 and perform the same procedure to achieve FN of 32.9%.
A copolymer (F-3) is obtained.

Copolymerization 4 Repeat the same procedure as in Copolymerization 3 with increasing AN, but no FN unevenness. 3%
An English polymer (F-4) is obtained.

The total of the blended graft polymer and copolymer was 10 parts by weight (PHR), and the mark PEP-8 (manufactured by Adeka Argus Chemical Co., Ltd.) was 0. is HR, barium stearate 0. Feed HR is pelletized using a Henschel mixer and a mixing extruder.

The rubber content is adjusted to 1 R on the same day. The blended composition was molded into a test plate and a shank by injection molding, and subjected to coating and impact tests, and its fluidity was measured using a melt indexer.
The results are shown in the table. Test method Izod impact strength ASTM D-256 method (230
〇) Melt index ASTM D-12 powder method G (
200q0 5k9) Paintability Judgment for painting by spraying method ○ No gloss or color unevenness△ Slight gloss or color unevenness × Gloss or color unevenness* Significant gloss or color unevenness

Claims (1)

[Claims] 1 Graft polymer obtained by polymerizing monomers consisting of an unsaturated nitrile compound and an aromatic vinyl compound in the presence of a diene rubbery polymer with a gel content of 70% or more and an average particle size of 0.2μ or more. One or more graft polymers with a content of unsaturated nitrile monomer units in the side chain portion of 20 to 32% by weight (the same applies hereinafter) and a content of unsaturated nitrile monomer units in the side chain portion of 32% by weight. ~37% A composition comprising one or more graft polymers mixed with one or more copolymers having an unsaturated nitrile monomer unit content of 20 to 37% and the remainder being aromatic vinyl monomer units. The content of unsaturated nitrile monomer units in the side chain portion of the total graft polymer is 28 to 35%, and the content of unsaturated nitrile monomer units in the total free polymer is 22 to 35%. A thermoplastic resin composition characterized in that it is mixed to a concentration of 35%.