JPS61268746A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition of improved practical characteristics such as impact strength and elongation without impairing transparency and weatherability, by blending aromatic vinyl-methyl methacrylate copolymer with specific graft copolymer. CONSTITUTION:The objective composition can be obtained by blending (A) a graft copolymer prepared by graft polymerization, in the presence of A1: 5-45pts.wt. of a rubbery polymer latex made from polymerization between (i) 30-70wt% of (meth)acrylic ester monomer with the homopolymer therefrom being <=0 deg.C in the glass transition temperature, (ii) 10-50wt% of conjugated diene and (iii) 10-30wt% of aromatic vinyl compound, of A2: 95-55pts.wt. of monomer mixture made up of (a) 40-80wt% of methyl methacrylate, (b) 4-25wt% of vinyl cyanide compound, (c) 2-20wt% of alpha-methylstyrene and (d) 0-20wt% of another vinyl monomer copolymerizable therewith and (B) an aromatic vinyl-methyl methacrylate copolymer so that the rubbery polymer content in the final composition falls between 2 and 15wt%. The difference in the refractive index between the components (A) and (B) is pref. <=0.005.

Description

[Detailed description of the invention] a. Industrial application field The present invention improves practical properties such as impact strength and elongation without impairing the excellent properties of styrene-methyl methacrylate copolymer, such as transparency and weather resistance. The present invention relates to improved resin compositions.

b. Prior art Aromatic-methacrylic acid ester copolymers, specifically styrene-methyl methacrylate copolymers, have excellent physical properties such as transparency, weather resistance, and mechanical strength, but have poor impact strength and It exhibits low elongation and brittle properties.

In order to improve this brittle property and prevent loss of transparency, for example, a resin composition prepared by melt-mixing a styrene-methyl methacrylate copolymer and a styrene-butadiene methacrylate copolymer having the same refractive index. Also known are graft copolymers in which vinyl monomers such as styrene and methyl methacrylate are grafted onto rubber-like substances such as butadiene polymers and styrene-butadiene copolymers.

C1 Problems to be Solved by the Invention However, such methods have drawbacks such as reduced transparency and insufficient impact strength.

In addition, since the resin contains many diene components with double bonds, it causes problems with the weather resistance, which is an excellent property of styrene-methyl methacrylate copolymer, and increases UV deterioration and ozone deterioration. is limited in its use.

The present inventors conducted extensive research to improve these drawbacks, and as a result, we found that aromatic vinyl-methacrylic acid ester copolymers have improved impact strength, elongation, and other practical properties without impairing their excellent properties such as transparency and weather resistance. We have now invented a resin composition with improved properties.

Means for Solving the Direct Zero Problem In other words, in order to solve the above problems, the present invention provides (a) a (meth)acrylic acid ester monomer whose homopolymer has a glass transition temperature of 0°C or lower; In the presence of 5 to 45 parts by weight (as solid content) of a rubbery polymer latex obtained by polymerizing 30 to 70% by weight of polymer, 10 to 50% by weight of a conjugated diene, and 10 to 30% by weight of an aromatic vinyl compound. 40-80% by weight of methyl methacrylate, 4-25% by weight of vinyl cyanide compound, 2% by weight of α-methylstyrene.
Graft copolymer (A) obtained by graft polymerization of 95 to 55 parts by weight of monomers consisting of
) and (b) aromatic vinyl-methyl methacrylate copolymer C
B) The present invention provides a resin composition having excellent impact strength and weather resistance, characterized in that the rubber polymer content in the composition is 2 to 15% by weight.

The present invention will be explained in detail below.

The glass transition temperature of the homopolymer used in the rubbery polymer in the graft copolymer (A) used in the present invention is 0°C
The following (meth)acrylic acid alkyl ester monomers (hereinafter also referred to as monomer + al) are preferably esters having an alkyl group having 2 or more carbon atoms, such as ethyl acrylate, acrylic acid- n-propyl,
n-butyl acrylate, 2-ethylhexyl acrylate, tert-butyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-decyl methacrylate, lauryl methacrylate, methacrylic acid Examples include tetradecyl, but in the case of acrylic acid alkyl esters, esters having an alkyl group having 2 to 10 carbon atoms are preferable, and in the case of methacrylic acid alkyl esters, esters having an alkyl group having 4 to 14 carbon atoms are preferable. preferable.

Among these, n-butyl acrylate, 2-ethylhexyl acrylate, and n-propyl acrylate, in which the glass transition temperature of the homopolymer of each monomer is 125°C or lower, are more preferred, and particularly preferred are acrylic acid. n-butyl acid. These can be used alone or in combination of two or more.

In the rubbery polymer, the amount of the above monomer (al) used is from 30 to
70% by weight, preferably 35-65% by weight. If the amount of monomer ta) used is less than 30% by weight, sufficient weather resistance cannot be obtained, while if it exceeds 70% by weight, both transparency and impact strength cannot be achieved.

For example, if the content of the (meth)acrylic acid alkyl ester monomer with a glass transition degree of 0° C. or lower is less than 30% by weight and the amount of methyl methacrylate is large, the material will not be rubber-like elastic and the impact strength will be poor.

As the conjugated diene, butadiene, isoprene, piperine, etc. can be used, but among these, butadiene is preferred.

The amount of conjugated diene used in the rubbery polymer is 10 to 50% by weight, preferably 15 to 45% by weight.

If the amount of conjugated diene used exceeds 50% by weight, weather resistance will decrease, and if it is less than 10% by weight, sufficient impact strength will not be obtained and transparency will also deteriorate.

Furthermore, examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, etc., with styrene being preferred. The amount of the aromatic vinyl compound used is 10 to 30% by weight, preferably 15 to 25% by weight, based on the rubbery polymer. If the amount used is less than 10% by weight, transparency will deteriorate, and if it exceeds 30% by weight, impact strength will be insufficient. In addition, vinyl cyanide and crosslinkable monomers such as divinylbenzene, dimethacrylates, divinyl adipates, divinyl ethers, etc. can be used as necessary.

The above-mentioned rubber-like substance can be obtained by polymerization, for example, using monomers (
a) 30-70% by weight, conjugated diene 10-50% by weight,
A monomer mixture consisting of 10 to 30% by weight of an aromatic vinyl compound is emulsified in water in the presence of an emulsifier, an udical polymerization initiator is added, and a polymerization reaction is carried out under stirring using a general method and conditions. It will be done.

Next, the grafting reaction in the present invention is carried out in the presence of 5 to 45 parts by weight, preferably 10 to 40 parts by weight (as solid content) of the above-mentioned rubbery polymer latex, and 40 to 80 parts by weight, preferably 45 parts by weight, of methyl methacrylate. ~77% by weight, vinyl cyanide compound 4-25% by weight, preferably 5-2
95 to 55 parts by weight of monomers consisting of 0% by weight, α-methylstyrene 2 to 20% by weight, preferably 3 to 15% by weight, and 0 to 20% by weight of other vinyl monomers copolymerizable therewith; Preferably, 9 to 60 parts by weight are copolymerized in an emulsified state.

Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile.

Other copolymerizable vinyl monomers include (meth)acrylic acid esters other than methyl methacrylate, (meth)
Examples include acrylic acid.

In particular, in order to obtain a resin composition with excellent transparency, it is necessary that the refractive indexes of the rubbery substance and the matrix resin component be the same or fairly similar, and that a sufficient amount of the graft component be produced. Since the refractive index has a value specific to each vinyl monomer, it is preferable to appropriately select the type of vinyl monomer, the amount used, the grafting rate, etc., and adjust the refractive index so that the refractive index is the same or similar. The refractive index difference between the rubbery material and the matrix resin component is preferably about 0602 or less in nr, and the graft ratio is preferably 30% or more.

Methyl methacrylate is required for transparency and weather resistance, and acrylonitrile is required for impact strength. Furthermore, sufficient impact strength was surprisingly achieved for the first time when α-methylstyrene was used within the scope of the invention in the compositions of the invention. If the α-methylstyrene content is less than the range of the present invention, the impact strength will not be sufficient, while if it exceeds the range, processability and thermal stability will decrease.

The graft polymerization reaction method is not particularly limited, but emulsion polymerization is preferred, and particularly preferred are formulations using redox initiators called dextrose formulations and sulfoxylate formulations, in which the vinyl monomer accounts for 80% of the total amount.
This is a method in which the above steps are added sequentially over 4 hours or more.

As the emulsifier, a fatty acid alkali metal type, a rosin acid alkali metal salt, a neutral emulsifier, etc. are used, but in any case, it is particularly preferable to recover the polymer by salt coagulation.

In particular, in the resin composition of the present invention, the effect of using α-methylstyrene in the graft polymerization composition of the graft copolymer (A) is unique. Conventionally, AB
It is well known that α-methylstyrene is used instead of styrene in S resins to improve heat resistance, but the present invention improves the impact strength of the graft copolymer, thereby improving the composition. A unique effect, previously unknown, was discovered in that impact strength could be improved and the purpose could be achieved.

Next, aromatic vinyl-methyl methacrylate copolymer (B
) is produced by known suspension polymerization, solution polymerization, etc.

The same aromatic vinyl as shown above can be used as the aromatic vinyl. Further, other copolymerizable vinyl monomers can be used as necessary.

Furthermore, in the resin composition of the present invention, resin compositions with different transparency can be obtained by changing the difference between the refractive index of the graft copolymer (A) and the refractive index of the copolymer (B). The required transparency varies depending on the application, but for example, it ranges from the excellent transparency of glass to the transparent transparency of resin compositions, which allows deep and beautiful colors to be obtained when coloring. , the required range of transparency is wide.

In the resin composition of the present invention, when the difference in refractive index between the graft copolymer (A) and the copolymer (B) is small, especially when it is less than o, oos, a resin composition with excellent transparency can be obtained. Preferably, even if the refractive index difference is o, oos or more, the composition of the present invention has a transparent feeling, so that when colored, a beautiful color can be obtained.

One way to adjust the refractive index difference is to use a graft copolymer (
It can be adjusted by selecting the type and amount of monomers used in A) and copolymer (B).

A transparent resin composition having excellent impact strength and weather resistance is obtained by kneading the graft copolymer (A) having the above characteristics and the styrene-metaflyte copolymer (B). The composition ratio is determined so that the content of the rubbery polymer therein is in the range of 2 to 15% by weight. If the rubbery polymer content is less than 2% by weight, the impact strength will be insufficient, while if it exceeds 15% by weight, the mechanical strength will be low, which is not preferable.

The graft copolymer (A) and the styrene-methacrylate copolymer (B) are mixed by a known method such as a roll, a kneader, a one-axle or two-wheeled extruder, or a Banbury mixer.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the number of parts in the examples indicates parts by weight.

e. Examples and Comparative Examples Rubber Latex II゛6 0.2 parts of potassium stearate, 1.5 parts of potassium laurate, alkyl Prepare 90 parts of ion exchange water containing 0.1 part of sodium naphthalene sulfonate, 0.1 part of potassium hydroxide, and 1.5 parts of potassium chloride.
Next, 100 parts of the rubber component monomer mixture shown in Table 1 was added. The temperature was raised under stirring at a rotation speed of 9 Orpm under a nitrogen atmosphere, and when the temperature reached 45°C, potassium persulfate was added,
Thereafter, the polymerization reaction was carried out while controlling the reaction temperature to be kept constant at 45°C, and when the polymerization rate reached 90%, 0.1 part of diethylhydroxyamine was added to stop the reaction, and unreacted was removed by steam distillation. substantially removing monomer;
A rubbery polymer latex was obtained.

Grafting material (A) 1゛6 In a 71 glass flask equipped with a stirring blade, 26 parts of the rubber latex obtained by the above method (as solid content), 0.14 parts of potassium laurate, and 100 parts of ion-exchanged water were added. of the mixture was added, and the temperature was raised while stirring. When the temperature reached 45°C, an active agent aqueous solution consisting of 0.4 part of sodium pyrophosphate, 0.5 part of glucose, ferrous sulfate o, oos part and 30 parts of ion-exchanged water was added, and at the same time laurine was added. acid potassium 0
．． 40 parts of ion-exchanged water containing 4 parts, 76 parts of a monomer mixture consisting of methyl methacrylate, acrylonitrile, α-methylstyrene, and styrene shown in Table 1, and an emulsifying monomer consisting of 0.4 parts of tertiary dodecyl mercaptan. Half of the mixture, the above-mentioned aqueous solution of other active agents, and 0.4 part of cumene hydroperoxide were added continuously over 6 hours. After the addition started, the temperature was raised to 70°C in about 1 hour, and then kept constant at 70°C.

After holding for 1 hour after the addition, 2,2-methylenebis=
0.2 part of (4-ethyl-6-t-butylphenol) was added and taken out from the flask.

It was coagulated using 2 parts of calcium chloride, dehydrated, washed with water, and dried to recover a powdered graft resin.

To the obtained powder were added 0.2 parts of 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole and 0.3 parts of ethylene bisstearamide, and the mixture was pelletized using an extruder.

Styrene-methyl methacrylate Ushigeto (B) 100 parts of a monomer mixture of styrene-methyl methacrylate, 50 parts of toluene, and 0.1 part of tertiary dodecyl mercaptan were charged into an ION autoclave equipped with a 1-inch stirring blade, and nitrogen Thermal polymerization was carried out at 140° C. for 8 hours with stirring under air flow.

This polymerization solution was steam distilled to remove unreacted monomers, pulverized and dried, and then pelletized using an extruder.

By this method, styrene with the composition shown in Table 1 is produced.
A methyl methacrylate copolymer was obtained.

・11,118 pairs of B&B pellets of the graft copolymer (A) and styrene-methyl methacrylate copolymer (B) obtained by the method described above were mixed at the blending ratio shown in Table 1, and then put into an extruder. Melt mixing was performed to obtain a pellet of a transparent resin composition.

Pellets of this composition were injection molded and subjected to various physical property evaluations.

The Izot impact strength of one 8-inch thick unnotched test piece was measured using 11 Impact Strength 8 STM D256.

(2) Tensile strength and elongation Measured based on ASTM 0638. A tensile speed of 5/sin was used.

(3) Total light transmittance, cloudiness Measured based on ASTH01003.

(4) Exposure to a weather resistance tester using a weather resistance carbon arc as a light source,
After 00 hours of irradiation, the Izot impact strength and total light transmittance were measured and the retention rate was determined.

Example 1.2 Examples 1 and 2 shown in Table 1 were carried out within the range specified by the present invention. The results are summarized in Table 1, showing transparency,
It had excellent impact strength and weather resistance.

Comparative example 1. 2. 3 Comparative Examples 1.2.3 are examples using rubber latex manufactured outside the scope of the present invention. Comparative Examples 1.2 had insufficient impact strength, and Comparative Example 3 had excellent transparency and impact strength, but poor weather resistance.

Comparative Examples 4 and 5 The rubber latex used in Example 2 was used, and the graft component was outside the scope of the present invention. None of these had sufficient impact strength.

Example 3 Using the graft copolymer (A) used in Example 2,
The blending ratio of the composition was varied. This composition had excellent transparency, impact strength and weather resistance.

Comparative Example 6.7 Using the graft copolymer (A) used in Example 2,
The amount of rubbery polymer in the composition was outside the scope of this invention.

It can be seen that when the rubbery polymer content is small, the impact strength is insufficient, while when the rubbery polymer content is large, the tensile strength is poor.

Example 4 Using the graft copolymer (A) used in Example 2,
The difference in refractive index with the styrene-methyl methacrylate copolymer (B) is outside the scope of the present invention. This product was not sufficiently transparent, but as a result of being colored with carbon black, a deep and beautiful color was obtained.

f. Effects of the invention As is clear from the above, according to the present invention, practical improvements such as impact strength and elongation can be achieved without impairing the excellent properties of aromatic vinyl-methyl methacrylate copolymer, such as transparency and weather resistance. A resin composition with improved properties can be obtained.

Claims (2)

[Claims] (1) (A) 30-70% by weight of a (meth)acrylic acid ester monomer whose homopolymer has a glass transition temperature of 0°C or lower, 10-50% by weight of a conjugated diene, and 10% by weight of an aromatic vinyl compound. In the presence of 5 to 45 parts by weight (as solid content) of a rubbery polymer latex obtained by polymerizing ~30% by weight, 40 to 80% by weight of methyl methacrylate, 4 to 25% by weight of vinyl cyanide compound, - A graft copolymer (A
) and (b) aromatic vinyl-methyl methacrylate copolymer (
B) A resin composition characterized in that the content of the rubbery polymer in the composition is 2 to 15% by weight. (2) The difference in refractive index between the graft copolymer (A) and the aromatic vinyl-methyl methacrylate copolymer (B) is 0.0
05 or less, the resin composition according to claim (1).