JPH01163209A - Production of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain the title resin having excellent transparency, weather resistance and impact resistance, by subjecting monomers consisting of a (meth) acrylic acid ester and another vinyl monomer to graft copolymerization in the presence of a specific rubber-like polymer. CONSTITUTION:(B) Monomers consisting of a (meth)acrylic acid ester (preferably methyl acrylate) having >=50 deg.C glass transition temperature in formation of a homopolymer and another vinyl monomer (e.g., acrylonitrile) copolymerizable with the (meth)acrylic acid ester are subjected to graft copolymerization in the presence of (A) a rubber-like polymer prepared by hydrogenating a block copolymer consisting of an aromatic vinyl compound (preferably styrene) and a conjugated diene compound (preferably butadiene or isoprene) to give the aimed resin. Preferably the composition of the monomers B is selected in such a way that the difference between the refractive index of the polymer A and that of a polymer obtained by polymerizing only the monomer mixture B is <=0.01.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for producing a thermoplastic resin having excellent transparency, weather resistance, and impact resistance. More specifically, (meth)
The composition of a monomer consisting of an acrylic ester and another vinyl monomer copolymerizable with the acrylic ester is selected so as to have a refractive index substantially equal to that of the rubbery polymer, and the composition is graft-polymerized. The present invention relates to a method for producing a thermoplastic resin.

b. Conventional technology In general, polymethyl methacrylate resins or resins containing methyl methacrylate as a main component are widely used in automobile parts, electrical parts, display displays, etc. due to their excellent properties such as transparency, gloss, and weather resistance. Although it is used in the field, it has the disadvantage of low impact strength. As a method to improve this impact strength, a vinyl monomer mixture consisting of methyl methacrylate, styrene, acrylonitrile, etc. is added in the presence of a diene rubber such as polybutadiene, and the refractive index of the diene rubber and the vinyl monomer mixture are mixed. A method is known in which the composition of a vinyl monomer mixture is selected so that the refractive indices of the polymers obtained by polymerizing the vinyl monomers alone are substantially the same. For example, methyl methacrylate-butadiene-styrene copolymer resins and methyl methacrylate-butadiene-styrene-acrylonitrile copolymer resins obtained by this method are used in various fields. However, since these resins contain unsaturated double bonds in their molecular main chains, they are degraded by ultraviolet rays and oxygen in the air, causing discoloration and reduced impact resistance, which is a fatal drawback of poor weather resistance. .

As a method to improve this weather resistance, a rubber-like polymer whose molecular main chain is substantially saturated is used instead of diene rubber.
Methods have been proposed in which various vinyl monomers are graft-polymerized to this. However, unlike diene rubbers, this rubber-like polymer does not have double bonds and has low radical activity, so the vinyl monomer does not undergo graft polymerization and simply combines the rubber-like polymer and vinyl polymer resin. Often a blend. Therefore, when the resin obtained is injection molded,
It has the drawbacks of unevenness on the surface, extremely low gloss and transparency, and poor mechanical properties such as impact resistance and tensile strength.

C1 Problems to be Solved by the Present Invention Regarding these problems, the present inventors have made extensive studies and found that in the presence of a rubber-like polymer obtained by hydrogenating a block copolymer consisting of an aromatic vinyl compound and a conjugated diene compound, To,
It has been discovered that a thermoplastic resin fully meeting the above purpose can be obtained by graft polymerizing a vinyl monomer containing (meth)acrylic acid ester as a main component and satisfying specific conditions, and the present invention reached.

A means for solving the d0 problem, that is, the present invention, is a glass that is made into a homopolymer in the presence of a rubbery polymer (a) obtained by hydrogenating a block copolymer consisting of an aromatic vinyl compound and a conjugated diene compound. Production of a thermoplastic resin characterized by graft copolymerization of a monomer (b) consisting of a (meth)acrylic acid ester having a transition temperature of 50°C or higher and another vinyl monomer copolymerizable with the same. The present invention provides a method.

The present invention will be explained in detail below.

As a hydrogenated product of a block copolymer composed of an aromatic vinyl compound and a conjugated diene used in the present invention, for example, a block copolymer typified by a block copolymer of styrene and butadiene is hydrogenated. The aliphatic double bonds based on a conjugated diene compound are saturated and converted into an olefinic polymer.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, and vinyltoluene, with styrene being preferred. Conjugated dienes include butadiene, isoprene, 1,3-pentadiene, 2゜3-dimethyl-1
, 3-butadiene, among others, butadiene, isoprene, and combinations thereof are preferred.

The ratio of aromatic vinyl to conjugated diene is not particularly specified, but in order to maintain impact resistance when used as a resin, the ratio of aromatic vinyl to conjugated diene should be 5 to 60/95 to 4.
0% by weight is preferred, particularly preferably 10-50/90
~50.

The molecular structure of this block copolymer is linear, branched,
The block structure may be radial or a combination thereof, and the block structure may be diblock, triblock, multiblock, or a combination thereof. In addition, the water vapor addition rate of these block copolymers is
It is required to be at least 50%, preferably at least 65%, particularly preferably at least 80%.

If it is less than 50%, it tends to reduce weather resistance, which is not preferable.

As a method for producing these hydrogenated block copolymers, a boat-based method can be used. Typical methods include those described in Japanese Patent Publications No. 42-8704 and Japanese Patent Publication No. 43-6636. As such a hydrogenated block copolymer, KRAT, a commercially available polymer, is used.
ON-G (trade name manufactured by Shell Chemical Company) etc. can be used.

In the present invention, as the vinyl monomer to be graft-polymerized to the hydrogenated block copolymer rubber, it is necessary to use (meth)acrylic acid ester and other monomers copolymerizable therewith in combination.

The above-mentioned (meth)acrylic acid alkyl ester is one whose glass transition temperature (measured by differential scanning calorimeter (DSC)) is 50°C or higher when made into a polymer by itself, and where the alkyl is carbon Numbers 1 to 10 are preferable, more preferably 1 to 6, particularly preferably 1 to 10.
4. Among methacrylic esters and acrylic esters, methacrylic esters are preferred.

Examples of these include methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate,
t-Butylcyclohexyl methacrylate, butyl methacrylate, hexyl methacrylate, (meth)acrylic ester represented by the following formula (n is O-3, R is hydrogen or an alkyl group, m is 3-4
), and one or more of these can be used.

Among these, methyl methacrylate and ethyl methacrylate are preferred, and methyl methacrylate is more preferred.

Examples of other copolymerizable vinyl monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; acrylic acid. methyl,
Other than those used in the above (meth)acrylic acid alkyl esters such as ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, etc. (Meth)acrylic acid alkyl ester monomer; Unsaturated acid anhydrides such as maleic anhydride and itaconic anhydride; Unsaturated acids such as acrylic acid and methacrylic acid; α such as N-phenylmaleimide and N-cyclohexylmaleimide ,
Examples include imide compounds of β-unsaturated dicarboxylic acids.

When using the (meth)acrylic acid ester and the above copolymerizable monomer, the difference between the refractive index of the rubbery polymer (a) and the refractive index of the monomer mixture (b) is 0.01. Hereinafter, it is preferable to carry out graft polymerization by appropriately selecting the composition of the monomer mixture so that the ratio is preferably 0.005 or less. Here, the refractive index difference between the two is 0. If it exceeds O),
Transparency of thermoplastic resin decreases. In addition, the monomer mixture (
The refractive index of a matrix resin consisting only of bl can be determined by calculating from a theoretical formula or by measuring the refractive index of a resin obtained by polymerizing a monomer mixture having this composition in advance.

The ratio of the (meth)acrylic acid ester to the other vinyl monomer is not particularly limited, and can be determined as appropriate depending on the refractive index of the rubbery polymer (al), but is preferably 30 to 30%.
98/70 to 2% by weight, more preferably 50 to 2% by weight
95150-5% by weight, particularly preferably 60-9%
It is 0/40 to 10% by weight.

The rubbery polymer (a) used in producing the thermoplastic resin of the present invention
The content of l can be arbitrarily selected depending on the purpose, but in order to satisfy the impact resistance, moldability and transparency of the resin,
The range is 5-35% by weight, preferably 10-30% by weight. If the rubber content is less than 5% by weight, a resin with insufficient impact resistance will be obtained, and if it exceeds 35% by weight, the moldability of the surface hardness will decrease, which is not preferable. Therefore, the monomer mixture (b) that becomes the matrix resin has the remaining content.

As the polymerization method for producing the thermoplastic resin of the present invention, known methods such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be adopted. Preferably legal.

The thermoplastic resin of the present invention thus obtained has excellent transparency, weather resistance, and impact resistance, and can be widely used in various applications that take advantage of these properties.

Moreover, this thermoplastic resin can be blended with other polymers such as methacrylic acid ester polymer, styrene-methyl methacrylate copolymer, and styrene-methyl methacrylate-acrylonitrile copolymer depending on the purpose. However, the difference in refractive index between the other polymers and the thermoplastic resin obtained in the present invention is 0.01 or less, preferably 0.005.
The following ranges are preferred; if these conditions are not met, a transparent composition cannot be obtained.

In addition, the thermoplastic resin of the present invention and the composition using the same may contain antioxidants such as hindered phenol, phosphorus, and sulfur, light stabilizers, ultraviolet absorbers, lubricants, colorants, and Commonly used additives such as fuel agents and reinforcing agents can be added to the extent that they do not impede the transparency.

e. Examples The present invention will be explained in more detail by Examples below.
All "parts" and "%" in the example sentences are based on weight.

In addition, various physical property test methods were measured according to the following procedures.

(1) Refractive index: Measured at 25°C using an Atsube refractometer.

(4) Weather resistance: Exposure to a sunshine weatherometer using a carbon arc as a light source for 1000 hours, and measure the Izot impact strength. Blank panel temperature: 63±3° C. Water showering was performed for 18 minutes every 2 hours.

Example-1 A homogeneous solution with a refractive index of 1.50 was prepared in advance in a stainless steel autoclave with an internal volume of 101 and equipped with a paddle type stirring device.
7 hydrogenated block copolymer KRATON G-16
50 (5RBS manufactured by Shell Chemical Company), 10.8 parts of styrene, 100 parts of toluene, and 0.1 part of t-dodecyl mercaptan were added, and the temperature was raised while stirring to 50°C.
79.2 parts of methyl methacrylate and 0.5 part of t-butylperoxyisopropyl carbonate were added. After the inside of the system was purged with nitrogen, the temperature was further raised to 90°C, and polymerization was continued at this temperature with stirring until the polymerization conversion rate reached 74%.

When the polymerization conversion rate reached 74%, the polymerization was stopped, an antiaging agent was added, and the mixture was taken out of the autoclave and unreacted monomers and solvent were removed by steam distillation. This material was finely ground and dried, and then pelletized using a 1.401) Iφ vented extruder. The rubber content of the obtained graft copolymer was 13%, and the refractive index of the copolymer resin consisting only of the monomer mixture was 1.5068.

The graft copolymer pellets obtained by the above method were molded into test pieces using an injection molding machine, and the physical properties were measured. The results are shown in Table-1.

Example-2 Hydrogenated block copolymer KRA with refractive index of 1.5105
TONG-1701X (Shell Chemical Co., Ltd. 5EP)
15 parts, 12.8 parts of styrene, 72 parts of methyl methacrylate
．． 2 parts, and a polymerization reaction was carried out in the same manner as in Example-1. After the polymerization was stopped when the polymerization conversion rate reached 70%, post-treatment was carried out in the same manner as in Example-1 to obtain a graft copolymer. The rubber content of the obtained graft copolymer was 20%, and the refractive index of the copolymer resin consisting only of a monomer mixture was 1.51)3.

This graft copolymer was injection molded and the physical properties were measured. The results are shown in Table 1.

Example 3 Polymerization, post-treatment, and evaluation were performed in the same manner as in Example 2, except that the monomer composition was changed to 12 parts of styrene, 68 parts of methyl methacrylate, and 5 parts of acrylonitrile.

The results are shown in Table-1.

The refractive index of a copolymer resin consisting only of a monomer mixture is
It was 1.5122.

Example 4 Polymerization was carried out under the following conditions using a polymerization reaction apparatus in which two stainless steel autoclaves each having an internal volume of 3ON and equipped with a paddle type stirring device were connected.

The reactor was supplied from the bottom of the reactor, and the two reactors were connected in such a way that they overflowed from the top. The polymerization solution overflowing from the second reactor was once held in a tank and then directly introduced into a 65 mφ vented extruder to separate and remove volatile components and form pellets.

The rubber content of the obtained graft copolymer was 24.8 parts, and the refractive index of the copolymer resin consisting only of the monomer mixture was 1.5066.

This graft copolymer was injection molded and the physical properties were measured. The results are shown in Table 1.

Comparative Example-1 <Manufacture of rubber-like polymer> Internal volume 100 equipped with paddle type stirring device! In a stainless steel autoclave, add ion exchange water containing 0.2 parts of potassium stearate, 1.5 parts of potassium laurate, 0.1 part of sodium alkylnaphthalene sulfonate, 0.1 part of potassium hydroxide, and 1.5 parts of potassium chloride. Next, 70 parts of n-butyl acrylate and 30 parts of styrene were added. The temperature was raised under stirring at 9 rpm in a nitrogen atmosphere, and when it reached 45°C, potassium persulfate was added.
The polymerization reaction was carried out while being controlled to maintain a constant temperature of 5°C. When the polymerization rate reached 90%, 0.1 part of diethylhydroxylamine was added to stop the reaction, and unreacted monomers were substantially removed by steam distillation. was removed to obtain a rubbery polymer latex.

This polymer latex was precipitated with accol, purified, and then dried to obtain a rubbery polymer.

<Production of Graft Copolymer> In place of the hydrogenated block copolymer, an n-butyl acrylate-styrene copolymer elastic body having a refractive index of 1.507 obtained by the above method was used. Other than this, polymerization and post-treatment were carried out in the same manner as in Example-1, and evaluation was performed. The results are shown in Table-1.

Comparative Example-2 Production of rubbery polymer> Rubber was produced in the same manner as in Comparative Example-1 except that the monomer composition was changed to 50 parts of n-butyl acrylate, 30 parts of 1,3-butadiene, and 20 parts of styrene. A polymer was obtained.

Production of Graft Copolymer> Instead of the hydrogenated block copolymer, an n-butyl acrylate-1,3-butadiene-styrene copolymer elastomer with a refractive index of 1.512 obtained by the above method was used.

Other than this, polymerization and post-treatment were carried out in the same manner as in Example-2,
evaluated. The results are shown in Table-1.

Comparative Example-3 The monomer composition in Example-1 was changed to 22.5 parts of styrene,
Polymerization, post-treatment and evaluation were conducted in the same manner except that 67.5 parts of methyl methacrylate was used. The results are shown in Table-1.

The refractive index of a copolymer resin consisting only of a monomer mixture is
It was 1.5196.

Comparative Example-4 Polymerization was carried out in the same manner as in Example-2 except that the monomer composition was changed to 34 parts of styrene and 51 parts of methyl methacrylate.
Post-processed and evaluated. The results are shown in Table-1.

Note that the refractive index of the copolymer resin consisting only of monomer mixtures is 1
．． It was 534.

Comparative Example-5 Polymerization, post-treatment and evaluation were conducted in the same manner as in Example-1 except that the monomer composition was changed to 54 parts of styrene and 36 parts of acrylonitrile. The results are shown in Table-1.

Note that the refractive index of a copolymer resin consisting only of a monomer mixture is 1.
．． It was 5628.

Comparative Example-6 Polymerization was carried out in the same manner as in Example-1 except that the base rubber was 10 parts of ethylene-propylene copolymer rubber JSREPOIP with a refractive index of 1.4855, 81 parts of methyl methacrylate, and 9 parts of methyl acrylate. processed and evaluated. The results are shown in Table-1.

Note that the refractive index of a copolymer resin consisting only of a monomer mixture is 1.
．． It was 4887.

Judging from the results shown in Table 1, Examples 1 to 4 were
l! It can be seen that thermoplastic resins with excellent transparency, weather resistance, and impact resistance can be obtained by using hydrogenated block copolymers such as BS and SEP.

In Comparative Example 1, it can be seen that impact resistance is extremely low when a rubbery polymer with a saturated molecular main chain is used.

In Comparative Example 2, impact resistance is developed by introducing a double bond into the molecular main chain of the rubber-like polymer, but it can be seen that weather resistance deteriorates.

Moreover, according to Comparative Examples 3 and 4, the difference between the refractive index of the rubbery polymer and the refractive index of the copolymer resin made only of the monomer mixture to be graft copolymerized was 0. It can be seen that when the temperature exceeds Ol, the transparency deteriorates.

f0 Effects of the Invention As is clear from the above, according to the present invention, methyl methacrylate and the copolymer thereof are produced in the presence of a rubbery polymer obtained by hydrogenating a block copolymer consisting of an aromatic vinyl compound and a conjugated diene compound. Transparency and durability can be improved by graft polymerizing a monomer mixture consisting of other polymerizable vinyl monomers with a composition selected so as to form a polymer having a refractive index substantially equal to that of the rubbery polymer. A thermoplastic resin with excellent impact resistance and weather resistance can be obtained.

The thermoplastic resin obtained in the present invention can be made into various transparent molded products, and can also be colored black or various colors to make molded products with deep and vivid colors. Such thermoplastic resins are useful in various home appliances, automobile parts, household goods, and various other industrial materials, as well as optical materials such as lenses and optical discs.

Patent applicant: Japan Synthetic Rubber Co., Ltd. (and 2 others)

Claims (3)

[Claims] (1) When a block copolymer consisting of an aromatic vinyl compound and a conjugated diene compound is made into a homopolymer in the presence of hydrogenated rubbery polymer (a), the glass transition temperature is 5.
Monomer (b) consisting of a (meth)acrylic acid ester having a temperature of 0°C or higher and another vinyl monomer copolymerizable with the same
A method for producing a thermoplastic resin, which comprises graft copolymerizing. (2) The refractive index of the rubbery polymer (a) and the monomer mixture (
The difference in refractive index from the polymer obtained by polymerizing only b) is 0.0.
1. The method for producing a thermoplastic resin according to claim 1, wherein the composition of monomer (b) is selected so that the composition of monomer (b) is 1 or less. (3) The amount of component (a) used is 5 to 35% by weight based on the total amount of (a) and (b), and the amount of the (meth)acrylic acid ester used in component (b) is 30% by weight. 98% by weight of the thermoplastic resin according to claim (1).