JP3367575B2 - Thermoplastic copolymer composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl cyanide-styrene copolymer obtained in a specific polymerization reaction environment and a specific copolymer in the presence of a diene rubber polymer. The present invention relates to a thermoplastic copolymer composition containing a graft copolymer obtained by graft copolymerizing a monomer. 2. Description of the Related Art Among vinyl cyanide-styrene copolymers, acrylonitrile styrene copolymers are particularly useful as chemical-resistant thermoplastic resins for sundries, cosmetic containers, and the like.
Widely used for electrical appliances and the like. Also, by being mixed with a graft polymer of a diene rubber polymer, it is widely used as a main raw material of impact-resistant and chemical-resistant ABS resin. It is well known that the quality of an acrylonitrile-styrene copolymer is important when the acrylonitrile-styrene copolymer is used alone or as a main raw material of an ABS resin. [0003] Industrial production methods for obtaining this acrylonitrile-styrene copolymer include an emulsion polymerization method, a suspension polymerization method and a continuous bulk polymerization or a continuous solution polymerization method. The continuous bulk polymerization method or the continuous solution polymerization method has become mainstream because of its smallness, cost and energy advantages. In these polymerization methods, thermal polymerization is generally employed as a polymerization reaction, but a method of performing polymerization with a peroxide for the purpose of improving productivity has been proposed. [0004] However, in the reaction by thermal polymerization, the polymerization temperature must be increased so as not to impair the productivity, and the vapor pressure of the polymerization solution becomes high, so that the apparatus becomes expensive. There are also disadvantages in that the molecular weight distribution is widened, a large amount of oligomers are formed, the hue is deteriorated, and desired physical properties cannot be obtained. [0005] On the other hand, the polymerization reaction using a peroxide has a drawback that the acrylonitrile contained in the acrylonitrile styrene copolymer is colored yellow due to a cyclization reaction or impairs transparency. These phenomena are remarkable when an acrylonitrile-styrene copolymer having a high acrylonitrile content is produced. SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the acrylonitrile-styrene copolymer and to obtain a vinyl cyanide having excellent hue and transparency.
By using a styrene copolymer, in a thermoplastic copolymer composition containing a graft copolymer of a vinyl cyanide-styrene copolymer and a diene rubber polymer, the hue, gloss, and physical properties can be balanced. To provide a resin composition. The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that when copolymerizing vinyl cyanide-styrene monomers, It has been found that by using a specific peroxide, a vinyl cyanide-styrene copolymer having good hue and excellent transparency can be obtained without impairing productivity. In particular, an acrylonitrile-styrene copolymer can provide an acrylonitrile-styrene copolymer which suppresses cyclization of acrylonitrile, has a good hue, and has an excellent balance of physical properties. Then, a graft obtained by graft copolymerization of the vinyl cyanide-styrene copolymer and a copolymerizable monomer other than a styrene monomer and a styrene monomer in the presence of a diene rubber polymer. It is obtained by containing a copolymer. In particular, a typical example is an ABS resin. That is, a method of continuously polymerizing a monomer mixture containing 15 to 60% by weight of a vinyl cyanide monomer and 40 to 85% by weight of a styrene monomer in the presence or absence of a solvent. In the compound represented by the following general formula [I], the decomposition temperature with a half-life of 10 hours is 70 to
Using a compound at 110 ° C. as a polymerization initiator, 0.001 to 0.1 part by weight based on 100 parts by weight of the monomer mixture, and copolymerizing under the conditions of a polymerization temperature of 90 to 150 ° C. A graft copolymer obtained by graft copolymerization of the obtained vinyl cyanide-styrene copolymer and a copolymerizable monomer other than a styrene monomer and a styrene monomer in the presence of a diene rubber polymer. An object of the present invention is to provide a thermoplastic copolymer composition containing a polymer (hereinafter, referred to as a graft copolymer). [0009] Hereinafter, the present invention will be described in detail. First, a method for producing the vinyl cyanide-styrene copolymer of the present invention will be described. As the styrene monomer used in the present invention, styrene, side chain substituted styrene such as α-methylstyrene, p-methylstyrene, o-chlorostyrene,
p-chlorostyrene, 2,4-dimethylstyrene, t-
Typical examples include nuclear-substituted styrene such as butylstyrene, and examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, fumaronitrile, and α-chloroacrylonitrile. These monomers of each system may be used alone or in combination of two or more. The proportion of vinyl cyanide monomer in these monomer mixtures is 15 to 60% by weight, preferably 20 to 5%.
5% by weight, more preferably 25 to 50% by weight.
When the amount of the vinyl cyanide monomer is less than 15% by weight, the mechanical properties and chemical resistance of the obtained copolymer are inferior. When the amount of the vinyl cyanide monomer exceeds 60% by weight, the thermal stability of the obtained copolymer is not sufficient. When the present invention is carried out by a continuous polymerization method, it can be carried out in the presence or absence of a solvent.
The organic solvent that can be used is preferably a solvent that can dissolve the generated vinyl cyanide-styrene copolymer, but in some cases, a poor solvent for the generated copolymer may be used. There is no particular limitation. Representative organic solvents include aromatic hydrocarbons such as ethylbenzene, toluene, and xylene; ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetophenone; alcohols such as methanol and ethanol; and other compounds such as tetrahydrofuran and dimethylformamide. Can be These may be used alone or as a mixed solvent of two or more. The amount used as the solvent is not particularly limited, but is preferably 0 to 40% by weight based on the total amount of the monomer mixture. If the content exceeds 40% by weight, the reaction is undesirably delayed and the equipment for recovering the solvent becomes large. As a specific example of the compound represented by the general formula [I], the decomposition temperature of the polymerization initiator used in the present invention having a half-life of 10 hours is 70 to 110 ° C.
-Amyl peroxyisopropyl carbonate, t-hexyl peroxyisopropyl carbonate, t-octyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, etc. No. The decomposition temperature of these compounds for a half-life of 10 hours is 70
The temperature is preferably from 110 to 110 ° C, more preferably from 80 to 100 ° C. Decomposition temperature of 70 ° C to obtain a half-life of 10 hours
If it is below, there is a possibility that it is locally decomposed in the polymerization reactor to generate a gel or to deteriorate the uniformity inside the reactor. If the temperature is higher than 110 ° C., the polymerization temperature must be increased in order to maintain sufficient productivity, and is susceptible to thermal degradation during polymerization, causing coloration or low molecular weight oligomers. Or worsen the physical properties. The decomposition temperature at which the polymerization initiator has a half-life of 10 hours can be determined as follows. Using a solvent relatively inert to radicals (eg, benzene), prepare a solution of about 1 mol / L of a polymerization initiator, seal in a glass tube purged with nitrogen, and set at a predetermined temperature. By immersing in a constant temperature bath and thermally decomposing, and determining the amount of active oxygen in the glass tube at a predetermined time, the concentration of the decomposed polymerization initiator can be known. The amount of active oxygen is
It can be determined by iodometric titration or gas chromatography. Since this decomposition reaction can be approximately treated as a first-order reaction, the concentration of the decomposed polymerization initiator is expressed as x (mol / mol).
Liter), the decomposition rate constant is k (1 / second), and the time is t
(Seconds), the initial concentration of the polymerization initiator is a (mol / liter)
Then, the following equation is established. ln [a / (ax)] = kt Therefore, at a certain temperature T (° K), the polymerization initiator is decomposed at various times, and the time t versus ln [a / (ax)]
= Kt, and the decomposition rate constant k at that temperature is determined from the slope of the obtained straight line. Since the half-life is the time when the initial concentration of the polymerization initiator is reduced by half,
When the half life is represented by t _1/2 and a / 2 is substituted for x in the above equation, the half life at that temperature can be obtained from the following equation. kt _1/2 = ln [2] This is repeated for several temperatures, ln (t _1/2 ) and 1 / T are plotted, and the decomposition temperature at which a half-life of 10 hours is obtained from the obtained straight line. . The 10-hour half-life temperature in the present invention is a value measured using benzene as a solvent. In the general formula [I] of the polymerization initiator, R ₁
The substituent represented by must be an alkyl group having 2 or more carbon atoms. This alkyl group may be linear, branched, or cyclic. However, when the carbon number is 1 or hydrogen, the radical generated by decomposition is a t-butoxy radical or an isopropoxy radical having a high hydrogen abstracting ability, and the acrylonitrile-cyclization reaction contained in the produced acrylonitrile-styrene copolymer. And a polymer having excellent hue and transparency, which are the objects of the present invention, cannot be obtained. On the other hand, when R ₁ is an alkyl group or a cyclic alkyl group having 2 or more carbon atoms, the alkoxy radical once generated by decomposition of the peroxide immediately releases acetone, and an alkyl radical or a cyclic alkyl radical having a low hydrogen abstraction ability. And the hue and transparency of the formed acrylonitrile-styrene copolymer are not impaired. In the practice of the present invention, the usable amount of the peroxide represented by the general formula [I] is as follows.
The amount is 0.001 to 0.1 part by weight, preferably 0.01 to 0.08 part by weight based on part by weight. If the amount is less than 0.001 part by weight, the effect of the present invention is low. If the amount is more than 0.1 part by weight, the polymerization rate becomes too fast and control becomes difficult. In the present invention, other types of polymerization initiators can be used in combination with the polymerization initiator represented by the general formula [I]. Specifically, t-butylperoxy (2-ethylhexanoate), 1-1-bis (t-butylperoxy) 3,3,3
Organic peroxides such as 5-trimethylcyclohexane, t-butylperoxypivalate, t-butylperoxyisopropyl carbonate, dicumyl peroxide, t-butylperoxyacetate, t-butylperoxybenzoate, and benzoyl peroxide; Examples include azo compounds such as azobisisobutyronitrile and 1,1′-azobis-1-cyclohexanecarbonitrile. They are,
One or more compounds may be used in combination with the compound represented by the general formula [I], but organic peroxides other than the compound represented by the general formula [I], especially aromatic organic peroxides The polymerization initiator may cause a chromophore by its decomposition, which may cause deterioration and coloring of the finally produced copolymer,
It is better not to use it. Care must be taken when using it. Further, in carrying out the present invention, a suitable chain transfer agent can be used. Representatively, thiols such as tertiary decyl mercaptan and normal dodecyl mercaptan, α-methylstyrene dimer, terpinolene, octyl thioglycolate and the like can be mentioned. In addition, a lubricant such as stearic acid, zinc stearate, ethylenebisstearylamide, or a phosphorus-based or hindered phenol-based antioxidant can be added in the polymerization step and / or the granulation step. As the polymerization reaction vessel for carrying out the present invention, a full or non-full type complete mixing tank having a stirring blade for medium / high viscosity such as a helical ribbon blade, screw blade, pitched paddle blade and the like is used. A single or a plurality of known reactors such as a column reactor, a tubular reactor with a static mixer, a horizontal self-cleaning reactor, or a complete mixing tank type reactor alone or Although it can be used in combination with a plurality, it is preferable to use a full or non-full type complete mixing tank type reactor alone. Among the polymerization conditions, the polymerization temperature is 90 to 150.
C, preferably 100 to 140C. If the polymerization temperature is too high, a gel is generated, and furthermore, the vapor pressure of the polymerization solution becomes high, so that the equipment becomes expensive, and if it is too low, the efficiency of the polymerization reaction deteriorates. The concentration of the copolymer in the polymerization solution at the outlet of the polymerization step is preferably from 40 to 90% by weight. When the concentration of the copolymer is less than 40% by weight, the production efficiency is poor. In the present invention, the unreacted monomer and the solvent are recovered by preheating the polymerization solution in a heat exchanger and then supplying it to a flash tank under reduced pressure for separation. A generally adopted method such as a method of supplying the mixture to a machine and performing heating separation may be used. Next, the graft copolymer will be described. The graft copolymer used in the present invention is obtained by copolymerizing a diene rubber polymer with a styrene monomer and a copolymerizable monomer other than the styrene monomer. Examples of the diene rubber polymer constituting the graft copolymer include latexes such as polybutadiene, styrene-butadiene copolymer, ethylene-propylene-butadiene copolymer, butadiene-alkyl acrylate copolymer, isoprene rubber, and chloroprene rubber. Can be Examples of the styrene-based monomer to be graft-copolymerized include at least one or more of styrene, α-methylstyrene, and p-methylstyrene. Also,
Examples of copolymerizable monomers other than styrene monomers include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, alkyl acrylates such as ethyl acrylate, octyl acrylate and 2-ethylhexyl acrylate, and methyl methacrylate. And at least one type of monomer among alkyl methacrylates such as ethyl methacrylate and the like. As a method of copolymerizing a diene rubber polymer with a styrene monomer and a copolymerizable monomer other than the styrene monomer, there are bulk-suspension polymerization method, emulsion polymerization method and solution polymerization method. However, an emulsion polymerization method capable of maximizing the rubber concentration is preferred. The proportion of the diene rubber polymer in the graft copolymer is preferably from 30 to 80% by weight, particularly preferably from 40 to 65% by weight. When the proportion of the diene rubber polymer is less than 30% by weight, cost is required to sufficiently exhibit the impact strength of the thermoplastic copolymer composition containing the vinyl cyanide-styrene copolymer. The mixing ratio of the high graft copolymer must be increased, which is not effective. If it exceeds 80% by weight,
Since the graft ratio of the graft copolymer is reduced, when it is applied to a molded article, impact resistance is reduced and gel flash is generated on the surface to lower the surface gloss. Next, a thermoplastic copolymer composition of a vinyl cyanide-styrene copolymer and a graft copolymer will be described. The mixing ratio of the vinyl cyanide-styrene copolymer and the graft copolymer is generally the same as that of the thermoplastic copolymer composition comprising the vinyl cyanide-styrene copolymer and the graft copolymer. Mixing ratios can be applied. In particular, the ratio of the vinyl cyanide-styrene copolymer is 30 to 85% by weight, preferably 4% by weight.
The content is preferably 0 to 80% by weight, more preferably 50 to 75% by weight. When the ratio of the vinyl cyanide-styrene copolymer is 3
If the amount is less than 0% by weight, when the obtained thermoplastic copolymer composition is used as a molded article, the molding processability is poor, the surface gloss of the molded article is low, and the heat resistance is not sufficient. On the other hand, when the content exceeds 85% by weight, the resulting thermoplastic copolymer composition cannot exert sufficient impact strength. The vinyl cyanide obtained by the above method
An apparatus for mixing and kneading a thermoplastic copolymer composition containing a styrene copolymer and a graft copolymer includes a Henschel mixer, a tumbler mixer, a single screw extruder,
A generally known mixing device such as a co-rotating twin-screw extruder or a different-direction twin-screw extruder can be used. If necessary, an antioxidant, a lubricant and the like can be kneaded. further,
The thermoplastic copolymer composition thus obtained is excellent in hue, gloss, chemical resistance and impact resistance. By molding this thermoplastic copolymer composition, the electric and
It can be used for housing of electronic products, automobile interior parts and the like. The present invention will be described more specifically below with reference to examples. Various physical properties were measured based on the following methods. (1) Polymer concentration in the reaction solution The reaction solution is sampled, weighed, and dissolved in methyl ethyl ketone. This is dropped into methanol,
The polymer was precipitated, dried and weighed. (2) Weight average molecular weight of polymer Determined by gel permeation chromatography. (3) Acrylonitrile content in the polymer Calculated based on the quantitative analysis of nitrogen by the Kjeldahl method. (4) Gloss, Yellowness and Haze Using a 2 oz. In-line screw molding machine at Niigata Iron Works, molding temperature 230 ° C., length 60 mm × width 40 mm
X A plate having a thickness of 2 mm was injection molded, and the center of the plate was measured according to JIS K 7105. (5) Izod impact strength No. 2 A test piece having a width of 1/2 inch, a thickness of 1/4 inch and a length of 5/2 inch was injection molded. Using this test piece, J
Izod impact strength was measured according to IS K 7110. (6) Melt flow rate (MFR) Measured according to JIS K7210. The test temperature and test load are as follows. (A) Experimental examples 1 to 3 are at a test temperature of 200 ° C. and a test load of 5 kg.
Performed in f. (B) Example 1 Contact and Comparative Examples 1 and 2 Test Temperature 220
C. and a test load of 10 kgf. Experimental Example 1 Preparation of acrylonitrile-styrene copolymer 31 parts by weight of acrylonitrile and 31 parts by weight of styrene were used.
A monomer mixture was prepared so as to be 9 parts by weight. Ethylbenzene was used as a solvent, and t-hexylperoxyisopropyl carbonate (decomposition temperature with a half-life of 10 hours was 95 ° C.) was used as a polymerization initiator. 0.07 to 100 parts by weight of ethylbenzene
It was added so as to be parts by weight to obtain a solvent / initiator mixed solution.
The monomer mixture and the solvent / initiator mixture are heated at an internal temperature of 1
1.11 kg / h of the monomer mixture was placed in a reactor equipped with double helical ribbon blades having an internal volume of 7 liters maintained at 20 ° C.
r and a solvent / initiator mixture at a rate of 0.33 kg / hr. The polymerization solution was continuously withdrawn by a pump by the same weight as the supplied amount, and heated with a preheater so that the temperature of the molten polymer after gas-liquid separation became 210 ° C.
The solution was sent to a flash tank maintained at orr, and the unreacted monomer and solvent were separated by gas-liquid separation, and then collected as pellets. At this time, the polymer content in the polymerization solution at the reactor outlet was about 58
%Met. Table 1 shows the analysis results and the evaluation results of physical properties of the obtained pellets. Experimental Example 2 Production of Acrylonitrile-Styrene Copolymer A polymerization reaction was carried out in the same manner as in Experimental Example 1 except that t-butylperoxyisopropyl carbonate was used as a polymerization initiator to obtain pellets. At this time, the polymer content in the polymerization solution at the outlet of the reactor was about 60%. Table 1 shows the analysis results and the evaluation results of physical properties of the obtained pellets. EXPERIMENTAL EXAMPLE 3 Preparation of Acrylonitrile-Styrene Copolymer Acrylonitrile and styrene were each 40 parts by weight and 6 parts by weight.
A monomer mixture was prepared to be 0 parts by weight. As a solvent
Use ethylbenzene, and use t-
Butyl peroxyacetate was used. This solvent 10
0.06 parts by weight of the polymerization initiator to 0 parts by weight
Was added to give a solvent / initiator mixture. This monomer mixture
And the solvent / initiator mixture was maintained at an internal temperature of 122 ° C.
Reaction with double helical ribbon wing with 7 liters inner volume
1.11 kg / hr of monomer mixture and solvent / open
Initiator mixture was continuously supplied at a rate of 0.33 kg / hr.
Was. The polymerization solution is continuously pumped by the same weight as the feed rate.
The temperature of the molten polymer after gas-liquid separation is 210 ° C
It was heated with a preheater and kept at 30 torr
Liquid is sent to the flash tank and unreacted monomer and solvent are vapor-liquid
After separation, they were collected as pellets. At this time, the polymer content in the polymerization solution at the outlet of the reactor was about 62%. Table 1 shows the analysis results and evaluation of physical properties of the obtained pellets. [Table 1] Experimental Example 4 Production of Graft Copolymer (Preparation of Rubber Latex) In a reaction vessel, 2.0 parts by weight of potassium stearate, 0.1 part by weight of potassium persulfate, and 0.2 part by weight of sodium acetate were dissolved. 200 parts by weight of water were charged, and 0.08 parts by weight of divinylbenzene was further added. Then, butadiene 1
Then, 00 parts by weight were injected, and the mixture was stirred at 65 ° C. for 30 hours to carry out polymerization. After 30 hours, unreacted butadiene was removed to obtain a rubber latex. (Pressure hypertrophy treatment) The rubber latex obtained above was supplied to a model 15M8TBA homogenizer manufactured by Menton Gorin, USA, to obtain a hypertrophy-treated rubber latex having a weight average particle diameter of 0.35 µm. In addition, the weight average particle diameter, using a polystyrene latex of a known weight average particle diameter, to determine the relationship between the absorbance and the weight average particle diameter to create a calibration curve, using this calibration curve to measure the absorbance I asked. (Graft Copolymerization) The above-described enlarged rubber latex (solid content: 28
%) 357 parts by weight, then add water 210 parts by weight, ferrous sulfate 0.005 parts by weight, tetrasodium ethylenediaminetetraacetate 0.01 parts by weight, sodium formaldehyde sulfoxylate 0.3 parts by weight, and add nitrogen atmosphere Stir underneath. The contents were maintained at 60 ° C., and a monomer mixture consisting of 25 parts by weight of acrylonitrile, 75 parts by weight of styrene, 0.6 parts by weight of t-dodecyl mercaptan, and 0.2 parts by weight of t-butyl peroxyacetate was added for 5 hours. To the latex. After the addition of the monomer mixture, 0.1 part by weight of cumene hydroxy peroxide was added, and the mixture was further stirred at 70 ° C. for 2 hours to complete the polymerization. (Recovery of Graft Copolymer) An aqueous solution containing 8 parts by weight of calcium chloride was poured into the obtained latex, and the mixture was stirred at 95 ° C. for 3 minutes to obtain a precipitate. The precipitate was dehydrated and dried to obtain a graft copolymer powder. Next, the thermoplastic copolymer composition of the acrylonitrile-styrene copolymer and a graft copolymer are shown in Comparative Examples 1 and 2 and contact the first embodiment. Example 1 67 parts by weight of the acrylonitrile styrene copolymer obtained in Experimental Example 1 and 37 parts by weight of the graft copolymer obtained in Experimental Example 5, 2,6-di-t-butyl-4-methylphenol 0 0.1 part by weight, triphenylphosphite 0.1 part by weight, and ethylene bisstearylamide 2.0 parts by weight, and the mixture was supplied to an extruder to obtain pellets. Table 2 shows the evaluation results of the obtained pellets. Comparative Example 1 The same mixture and ratio as in Example 1 were used, except that the acrylonitrile styrene copolymer obtained in Experimental Example 2 was kneaded and pelletized. Table 2 shows the evaluation results of the physical properties. Comparative Example 2 A kneaded mixture was prepared in the same manner as in Example 1 except that the acrylonitrile styrene copolymer obtained in Experimental Example 3 was used, and the mixture was pelletized. Table 2 shows the evaluation results of the physical properties. [Table 2] As shown in Examples and Comparative Examples, ABS obtained by using a specific organic peroxide of the present invention as a polymerization initiator and acrylonitrile-styrene copolymer obtained under specified production conditions. The resin has better yellowness and gloss than the ABS resin obtained using an acrylonitrile styrene copolymer obtained using a polymerization initiator outside the scope of the present invention, and has a higher Izod impact strength and melt flow rate. The fluidity shown is also good. As is evident from the above results, the thermoplastic copolymer composition containing the vinyl cyanide-styrene copolymer of the present invention and the specific graft copolymer has a specific structure. By using a vinyl cyanide-styrene copolymer with good hue obtained by using an appropriate amount of organic peroxide, it has good hue, good gloss, and excellent balance between impact resistance and fluidity. .

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Claims (1)

(57) [Claim 1] It contains 15 to 60% by weight of a vinyl cyanide monomer and 40 to 85% by weight of a styrene monomer in the presence or absence of a solvent. In a method of continuously polymerizing a monomer mixture, a compound having a decomposition temperature of 70 to 110 ° C. with a half-life of 10 hours among compounds represented by the following general formula [I] is used as a polymerization initiator, The agent is used in an amount of 0.001 to 0.
1 part by weight of a vinyl cyanide-styrene copolymer obtained by copolymerization at a polymerization temperature of 90 to 150 ° C., and a styrene monomer and styrene in the presence of a diene rubber polymer. A thermoplastic copolymer composition containing a graft copolymer obtained by graft copolymerizing a copolymerizable monomer other than a single monomer. Embedded image