JPH0477008B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a thermoplastic resin having excellent heat deformation resistance and impact resistance. [Prior Art] Conventionally, a method has been proposed in which monomers containing α-methylstyrene, acrylonitrile, and styrene as main components are polymerized in the presence of a diene rubber to obtain a thermoplastic resin. [Problems to be solved by the invention] However, when the content of α-methylstyrene is small, the copolymers obtained by these methods have sufficient heat deformation resistance when made into molded products. However, if the α-methylstyrene content is high, sufficient impact resistance cannot be obtained when molded products are formed. In addition, for the purpose of improving heat deformation resistance and impact resistance, copolymers of aromatic vinyl monomers, acrylonitrile monomers, etc. and maleimide or its N-aryl substituted derivatives, and diene rubbers containing aromatic vinyl A method has been proposed in which a monomer is mixed with a graft copolymer obtained by polymerizing acrylonitrile monomer, etc. (Japanese Patent Application Laid-open No. 167341/1983).
Even with this method, it is not possible to obtain a resin composition that provides a molded article with sufficient heat deformation resistance and impact resistance. The present invention has been made in order to overcome these drawbacks and produce a thermoplastic resin that can provide molded products with excellent heat deformation resistance and impact resistance. [Means for solving the problem] The present invention involves polymerizing a monomer mixture consisting of acrylonitrile and styrene in the presence of a diene rubber, and then adding a monomer mainly composed of α-methylstyrene. Then, by adding a monomer mixture containing maleimide and/or its N-aryl substituted derivative and acrylonitrile little by little to substantially complete the polymerization, a thermal deformation resistance and impact resistance excellent. This method was developed based on the discovery that a plastic resin could be obtained by mixing 95 to 70 parts of the diene rubber and the monomer in the presence of 5 to 30 parts (parts by weight, the same shall apply hereinafter) of the diene rubber. When polymerizing so that the total amount of monomers is 100 parts, 2 to 40 parts of a monomer mixture (A) of acrylonitrile and styrene in which the weight ratio of acrylonitrile/styrene is 10/90 to 40/60. After polymerization, 10 to 80 parts of monomer (B) containing 80 to 100% (by weight, the same applies hereinafter) of α-methylstyrene is added, and then maleimide and/or its N
- Contains 1 to 20 parts of aryl substituted derivative, monomer
Add acrylonitrile-containing monomer mixture (C) to 18 to 83% of the monomer mixture (C) containing (B) so that the weight ratio of α-methylstyrene/acrylonitrile is 90/10 to 65/35.
The present invention relates to a method for producing a thermoplastic resin having excellent heat deformation resistance and impact resistance, which is characterized by partial polymerization. [Example] In the present invention, in the presence of 5 to 30 parts of diene rubber, preferably 7 to 25 parts, 95 to 70 parts, preferably 93 to 75 parts of monomers are added so that the total amount is 100 parts. are superimposed. Examples of the diene rubber include polybutadiene, SBR (styrene-butadiene rubber),
Examples include, but are not limited to, NBR (acrylonitrile-butadiene rubber) and butyl acrylate-butadiene rubber. If the proportion of the diene rubber is out of the range of 5 to 30 parts, the resulting molded article from the thermoplastic resin will have reduced impact resistance and poor heat deformation resistance. In the polymerization of 95 to 70 parts of monomer in the presence of 5 to 30 parts of diene rubber, the weight ratio of acrylonitrile/styrene is 10/90 to 40/60, preferably 15/85 to 35/65. After polymerizing 2 to 40 parts, preferably 2 to 20 parts, of a certain monomer mixture (A) of acrylonitrile and styrene, a monomer containing 80 to 100%, preferably 85 to 100% of α-methylstyrene is obtained. 10 to 80 parts, preferably 20 to 80 parts of compound (B) are added, and then 1 to 20 parts, preferably 3 to 20 parts of maleimide and/or its N-aryl substituted derivative are added, and the monomer ( B) together with α-methylstyrene/
18 to 83 parts, preferably 20 to 80 parts of a monomer mixture (C) containing acrylonitrile is polymerized so that the weight ratio of acrylonitrile is 90/10 to 65/35, preferably 85/15 to 65/35. It is done by letting Acrylonitrile constituting monomer mixture (A)/
If the weight ratio of styrene is out of the range of 10/90 to 40/60, the molding processability of the resulting thermoplastic resin will decrease, and the impact resistance of the molded product will decrease.
Up to 30% of the acrylonitrile and styrene may be replaced with other vinyl monomers. Specific examples of the other vinyl monomers include α
- Examples include methylstyrene, chlorstyrene, methyl methacrylate, and methacrylonitrile. Furthermore, if the polymerized amount of the monomer mixture (A) is less than 2 parts, the impact resistance of the molded product molded from the obtained thermoplastic resin will decrease, and if it exceeds 40 parts, the heat deformation resistance will decrease. If the proportion of α-methylstyrene in the monomer (B) is less than 80%, the resulting thermoplastic resin will have poor heat deformation resistance. Components that can be contained in the monomer (B) at a rate of 20% or less include vinyl monomers other than α-methylstyrene, such as styrene, chlorostyrene,
Examples include acrylonitrile, methacrylonitrile, methyl methacrylate, acrylic acid, and methacrylic acid. If the amount of monomer (B) added is less than 10 parts, the heat deformation resistance of the resulting thermoplastic resin molded product will decrease, and if it exceeds 80 parts, the polymerization conversion rate will decrease. impact resistance decreases. The amount of maleimide and/or its N-aryl substituted derivative contained in the monomer mixture (C) is 1
A range of ~20 parts is preferable from the viewpoint of impact resistance, heat deformation resistance, moldability, etc., and the weight ratio of α-methylstyrene/acrylonitrile in the monomer (B) and monomer mixture (C) is A range of 90/10 to 65/35 is preferable from the viewpoint of impact resistance, heat deformation resistance, polymerization conversion rate, etc. There is no particular restriction on the weight ratio of acrylonitrile/maleimide and/or its N-aryl substituted derivative in the monomer mixture (C). Examples of N-aryl substituted derivatives of maleimide include phenylmaleimide, monomethylphenylmaleimide, dimethylphenylmaleimide, ethylphenylmaleimide, chlorphenylmaleimide, and the like. When the amount of monomer mixture (C) added is less than 18 parts,
The impact resistance of the resulting thermoplastic resin decreases, and if it exceeds 83 parts, the heat deformation resistance decreases. The monomer mixture (C) contains α-methylstyrene, styrene, chlorstyrene, methacrylonitrile, methyl methacrylate, methacrylic acid, etc. in addition to acrylonitrile, maleimide and/or its N-aryl substituted derivative. may have been done. Monomer mixture (A), monomer (B) and monomer mixture
There are no particular limitations on the method of adding (C), but after 60% or more of the monomer mixture (A) has polymerized, monomer (B) is added, and then a small amount of the monomer mixture (C) is added. It is preferable to add them one by one. The monomer mixture (C) may be added continuously or in several steps, but the weight ratio of α-methylstyrene and acrylonitrile present in the system may be It is desirable to add so that the ratio is 80/20, preferably 90/10, and more preferably 95/5 or more until the conversion rate is 40%. The polymerization method used in the present invention is preferably an emulsion polymerization method, but is not limited to the emulsion polymerization method. When emulsion polymerization is employed, it can be carried out by conventional methods. For example, the monomer may be polymerized in an aqueous dispersion in the presence of a diene rubber using a radical initiator. Examples of radical initiators include peroxides such as potassium persulfate, ammonium persulfate, and kyumene hydroperoxide. Other polymerization accelerators, polymerization degree regulators, emulsifiers, etc. that have been generally used in emulsion polymerization may be appropriately selected and used. The polymerization temperature is preferably 30 to 80°C. A known method may be used to obtain the resin from the obtained latex. Further, if necessary, conventional stabilizers, plasticizers, lubricants, pigments, antistatic agents, ultraviolet absorbers, etc. may be added. A molded article formed using the thermoplastic resin thus obtained has excellent heat deformation resistance and impact resistance. The method of the present invention will be specifically explained below based on Examples, but these Examples are not intended to limit the present invention. Examples 1 to 6 and Comparative Examples 1 to 5 200 parts of water, sodium alkylbenzenesulfonate
2.0 parts of sodium formaldehyde sulfoxylate, 0.4 parts of sodium formaldehyde sulfoxylate, 0.01 part of disodium ethylenediaminetetraacetate, and 0.0025 parts of ferrous sulfate were charged into a reactor equipped with a stirrer, and after deoxidizing, heated and stirred at 60°C in a nitrogen stream to form a rubber latex. Then, monomer mixtures (A), (B) and (C) shown in Table 1 were sequentially charged. That is, the monomer mixture (A) was added continuously over a period of 1 hour, and when the polymerization conversion rate reached 60% or more after the addition was completed, the monomer (B) was added all at once to thoroughly emulsify it. Thereafter, the monomer mixture (C) was continuously added over a period of 6 hours, and then heating and stirring were continued at 60° C. to complete the polymerization. Note that sodium alkylbenzene sulfonate and sodium formaldehyde sulfoxylate were initially charged in an amount of 0.2 parts and 0.2 parts, respectively, and the remainder was added in two portions during the continuation of the polymerization. After adding an antioxidant to each of the obtained polymer latexes and salting them, they were washed with water, filtered, and dried to form pellets, and the physical properties of the molded products were measured by the following method. (Heat distortion temperature) Measured at a load of 18.6 kg/cm ² according to ASTM D-648. (Izot impact value) Notched according to ASTM D-256, measured at 23°C. (Tensile strength) Measured at 23°C according to ASTM D-636. The rubber latex in Table 1 is manufactured by Kanebuchi Chemical Industry Co., Ltd.
Polybutadiene manufactured by Co., Ltd., AN is acrylonitrile, St is styrene, αMst is α-methylstyrene,
PMI stands for phenylmaleimide, MPMI stands for parameter phenylmaleimide, tDM stands for t-dodecyl mercaptan, and CHP stands for kyumene hydroperoxide.

【table】

[Table] * Not measured due to low conversion rate From the results in Table 1, it can be seen that the thermoplastic resin of the present invention has excellent heat deformation resistance and impact resistance. [Effects of the Invention] When a thermoplastic resin is produced by the method of the present invention, a resin having excellent heat deformation resistance and impact resistance of a molded article can be obtained.

Claims (1)

[Claims] 1 95-70 in the presence of 5-30 parts by weight of diene rubber
A monomer mixture of acrylonitrile and styrene in which the weight ratio of acrylonitrile/styrene is 10/90 to 40/60 when polymerizing the monomers in a total amount of 100 parts by weight (A) After polymerizing 2 to 40 parts by weight of α-methylstyrene, 80 to 100 parts by weight of
Adding 10 to 80 parts by weight of monomer (B) containing % by weight,
The monomer (B) contains 1 to 20 parts by weight of maleimide and/or its N-aryl substituted derivative.
Heat-resistant deformation characterized by polymerizing 18 to 83 parts by weight of a monomer mixture (C) containing acrylonitrile so that the weight ratio of α-methylstyrene/acrylonitrile is 90/10 to 65/35. A method for producing thermoplastic resin with excellent durability and impact resistance.