JPH0458486B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing an impact-resistant styrenic resin having excellent strength, gloss, and colorability. More specifically, by using polybutadiene with a special structure as a toughening agent,
The present invention relates to a method for producing an impact-resistant styrenic resin that has practical impact-resistant strength, gloss, and excellent colorability with coloring agents. (Prior art) Conventionally, rubber-modified styrenic resins have been produced by dissolving unvulcanized rubber in styrenic monomers and subjecting this solution to bulk, solution or bulk-suspension polymerization, or by simply polymerizing unvulcanized rubber. It has been manufactured by mechanically mixing rubber. In particular, rubber-modified styrenic resins obtained by bulk or bulk-suspension polymerization are widely used industrially. In this case, unvulcanized rubbers commonly used as toughening agents include polybutadiene rubber and styrene-butadiene rubber.
Polybutadiene rubber is most commonly used because it is superior to styrene-butadiene rubber in terms of the low-temperature impact resistance of the resulting rubber-modified styrenic resin. However, one of the drawbacks of rubber-modified styrenic resins using polybutadiene rubber as a toughening agent is poor coloring properties with colorants. Styrenic resins such as polystyrene that do not contain toughening agents originally have better coloring properties than other resins such as polyethylene, but in order to improve impact resistance, rubber-like toughening resins When the agent is added, the coloring property is significantly impaired. This tendency is better when using polybutadiene rubber as a toughening agent.
significantly more than in the case of styrene-butadiene rubber.
Furthermore, polybutadiene rubber can be solution-polymerized using a Ziegler-based catalyst rather than so-called low-cis polybutadiene rubber, which has a cis-1,4 bond structure of 25 to 45% and is obtained through solution polymerization using a lithium-based catalyst. 90% of the cis-1,4 bond structure obtained by
The so-called high-cis polybutadiene rubbers described above have even worse coloring properties. Rubber-modified styrenic resins generally have a two-phase structure consisting of a rubber phase and a polystyrene phase, and it is speculated that this two-phase structure is one reason why rubber-modified styrenic resins have reduced coloring properties. . In other words, the presence of the rubber phase reduces transparency, and although the dispersed rubber phase has a so-called salami structure containing a styrene polymer inside, the polybutadiene portion has poor coloring properties, and as a result, the rubber as a whole It has been thought that this reduces the colorability of modified styrenic resins. On the other hand, rubber-modified styrene resins are often used to mold so-called home appliances such as TV frames, radio and video housings by injection molding, but in this case, the physical properties required of the resin are colorability. It is desired that the material not only has good and practical impact resistance, but also has good gloss. It is generally known that the size of the rubber phase dispersed in the two-phase structure of rubber-modified styrenic resin has a large effect on gloss. In other words, if the size of the rubber phase is reduced,
The gloss will be better, but the impact resistance will be poor; on the other hand, if it is made larger, the impact resistance will be stronger, but the gloss will be lower. To date, a satisfactory method for obtaining a rubber-modified styrenic resin with excellent practical impact resistance, coloring properties, and gloss has not yet been clarified. As a disclosure of these improved techniques,
There is a publication No. 130791. This specifies the polymer structure of polybutadiene rubber used as a toughening agent. That is, in JP-A-53-130791, the polymer structure of polybutadiene is 7 to 35% 1,2-vinyl bond structure, 20 to 80% cis 1,4 bond structure, and weight average molecular weight (Mw ) and number average molecular weight (Mn) (Mw/Mn)
By dissolving a polybutadiene rubber with styrene and a Williams recovery value of 2.6 or more and a Williams recovery value of 2.6 mm or more and subjecting the solution to bulk polymerization or bulk-suspension polymerization, both low-temperature impact resistance and coloring properties are improved. It is said that high-impact polystyrene can be obtained. However, when the method described in JP-A-53-130791 is examined in detail, it is true that it has a certain degree of improvement effect in terms of colorability and low impact resistance compared to conventional polybutadiene rubber, but it is not practical. Furthermore, it is not possible to obtain a satisfactory gloss, which is a necessary physical property. JP-A-59-20334 discloses a technique that further improves gloss. This also specifies the polymer structure of polybutadiene rubber used as a toughening agent. In other words, JP-A-59-
In Publication No. 20334, the polymer structure of polybutadiene is a rubber-like polymer having a branched structure obtained by a coupling reaction between a living polymer obtained by polymerization using an organolithium catalyst and a tin halide compound, and By using a rubber-modified thermoplastic resin composition obtained using polybutadiene with a degree of coupling of 20 to 80% by weight and a content of 1,2-vinyl bonds of 30 to 90%, impact-resistant polystyrene with good gloss can be obtained. It is said that it will be done. However, when we examine the method described in JP-A No. 59-20334 in detail, we find that although it does show an improvement in gloss compared to conventional polybutadiene, it is not satisfactory in terms of practical impact resistance. has not been obtained. (Problems to be Solved by the Invention) In order to solve these problems and obtain a rubber-modified polystyrene resin that has an excellent balance of the three above-mentioned physical properties, which are important in practical terms, the present inventor has conducted extensive research and found the following: The present inventors discovered that a rubber-modified polystyrene resin with excellent colorability, practical strength, and gloss can be obtained by using two specific rubber-like polymers, leading to the completion of the present invention. (Means for solving the problem) That is, the present invention dissolves polybutadiene rubber in a styrene monomer and polymerizes the solution to produce an impact-resistant styrenic resin. , 2-vinyl bond structure accounts for 20-40%, cis-1,4 bond structure accounts for 15-35%, and the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw/
(B) 1,2
(A )/(B)=3.0 to 1/3. The present invention will be explained in more detail below. First, the polybutadiene rubber used as the toughening agent of the present invention will be described. The specific polybutadiene rubber used in the present invention includes organic lithium compounds such as n-butyllithium,
sec-butyllithium, t-butyllithium, n
- Solution polymerization using propyllithium, isopropyllithium, benzyllithium, trimethylenelithium, etc. as a catalyst. The polybutadiene rubber used in the present invention is group (A) and group (B).
Unless these groups are used in combination, it is not possible to obtain the desired impact-resistant styrenic resin that is excellent in practical impact resistance, gloss, and colorability with coloring agents. Each group of polybutadiene rubber will be explained in more detail. The polybutadiene rubber (A) used in the present invention is 1,2
Vinyl bond structure is 20-40%, preferably 23-35%
and the cis 1,4 bond structure should be 15-35%, preferably 18-27%. When a polybutadiene having a microstructure outside this range is used, the resulting impact-resistant styrenic resin has significantly poor colorability and is of poor practical value. Furthermore, if the 1,2-vinyl bond structure exceeds 40%, the properties as a rubber toughening agent will be poor. Furthermore, the weight average molecular weight (Mw) and number average molecular weight (Mn) of polybutadiene rubber
It is necessary that the ratio (Mw/Mn) is 1.2 or more and less than 1.8. When it is less than 1.2, the resulting impact-resistant styrenic resin has excellent gloss but low practical strength, and when it is 1.8 or more, it has excellent practical strength but does not have gloss. In addition, the colorability is also poor. The polybutadiene rubber (B) must have a 1,2-vinyl bond structure of 13-30%, preferably 15-25%, and a cis-1,4 bond structure of 20-50%, preferably 30-40%. If a polybutadiene having a microstructure outside this range is used, the resulting impact-resistant styrenic resin will have significantly poor gloss and colorability, and its practical value will be poor. Furthermore, it is necessary that the above Mw/Mn ratio of the polybutadiene rubber is 2.5 to 5.0. If it is less than 2.5, the practical impact resistance strength will be poor, and if it exceeds 5.0, the practical strength will be excellent but the gloss will not be achieved. Furthermore, it is necessary that the polymer chains of the polybutadienes (A) and (B) have a branched shape. That is, it has a shape coupled with a trifunctional or tetrafunctional binder such as silicon tetrachloride, monomethyl silicon trichloride, tin tetrachloride, etc. degree) must be 50% or more. If the degree of coupling is less than 50%, the coloring properties of the resulting impact-resistant styrenic resin will be poor, and in particular, if the degree of coupling is less than 30%, the coloring properties will be extremely poor and it will not be suitable for practical use. In the method of the present invention, the degree of coupling must be at least 50%, preferably at least 65%. The method for producing such polybutadiene may be any conventionally known method. Solution polymerization is carried out using a lithium compound as a catalyst, and as described above, polyfunctional binders such as halogen compounds such as silicon tetrachloride, tin tetrachloride, and carbon tetrachloride, and diesters such as diethyl adipate and dimethyl maleate are used. , coupling reaction [J.Polym.Sci.Part A Vol.13p.93-103 ('65)]
However, any other conventionally known method may be used as long as it satisfies the scope of the claims of the present invention. In the present invention, it is necessary to use polybutadiene rubber (A) and (B) together, and the ratio of their combination is (A)/(B)=
It needs to be 3.0 to 1/3. If it exceeds 3.0, the impact resistance will be poor, and if it is less than 1/3, the gloss will not be sufficient. In the method for producing a rubber-modified styrenic resin of the present invention, the ratio of polybutadiene rubber to styrene monomer is preferably 2 to 15 parts by weight to 85 to 98 parts by weight. If the concentration of polybutadiene rubber is less than 2% by weight with respect to the content of polybutadiene rubber and styrene monomer, the impact resistance strength of the resulting resin will be insufficient, and if it exceeds 15% by weight, the strength will increase at an economical rate. The most suitable range is from 2 to 15% by weight, since problems such as a small degree of oxidation and an excessively high viscosity of the polymerization system tend to occur. As a method for producing the rubber-modified styrenic resin of the present invention, bulk, solution or bulk-suspension polymerization methods are advantageously used. For example, in the case of bulk-suspension polymerization, the polybutadiene rubber of the present invention is dissolved in a styrene monomer, and the solution is mixed with an azo compound such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, or peroxide. This solution is heated with stirring in the presence or absence of a catalyst such as a peroxide such as benzoyl, t-butyl peroxybenzoate, di-t-butyl peroxide, or dicumyl peroxide to perform radical polymerization. , polymerization rate 20
When reaching ~40%, the polymerization solution is suspended in water to continue polymerization and complete the polymerization. At this time, a molecular weight regulator such as mercaptan and a plasticizer such as white mineral oil may be used as appropriate. or,
It is also possible to separately add a catalyst and a molecular weight regulator during the polymerization. In the present invention, styrenic monomers include styrene, paramethylstyrene, t-butylstyrene,
α-methylstyrene, chlorstyrene, etc.
These may be used alone or in combination. or,
A portion of the styrenic monomer may be replaced with a monomer that can radically copolymerize with these monomers, such as acrylonitrile, methyl methacrylate, and methyl acrylate. The impact-resistant styrenic resin thus obtained has excellent practical impact resistance, gloss, and colorability with coloring agents compared to conventional resins. The impact-resistant styrenic resin obtained by the method of the present invention can be processed with antioxidants, ultraviolet absorbers, lubricants, mold release agents, etc. in addition to coloring agents.
Fillers and the like can be added in advance and used for a series of applications such as injection molding and extrusion sheet molding. The present invention will be specifically explained below using Examples and Comparative Examples. The present invention is not limited only to these examples. Examples are shown in Table-1 and comparative examples are shown in Table-2.
It can be seen that the impact-resistant styrenic resins shown in Examples are excellent in all physical property items, and that the resins according to the present invention have a good balance of physical properties. Example 1 [Manufacture of polybutadiene rubber (A)] 50 mmol of dehydrated and purified benzene, 10 mmol of n-butyllithium, and 0.9 g of THF (tetrahydrofuran) as a vinylating agent were charged into an autoclave having an internal volume of 100 mm. 7000g of butadiene was added and polymerized at 60°C for 2 hours. Tin tetrachloride was added as a coupling agent to the obtained polymer, and after further reaction for 1 hour, 70 g of methanol was added to terminate the polymerization reaction, and tin tetrachloride was added as an anti-aging agent.
-Methyl-2,6-ditertiarybutylphenol and trinonylphenyl phosphorite were added in an amount of 50 g each, and the polymer was precipitated by a steam stripping method. Table 1 shows the physical properties of the polybutadiene rubber obtained by drying using a conventional drying method. [Manufacture of polybutadiene rubber (B)] 30 dehydrated cyclohexane, 20 benzene, 6 mmol of n-butyllithium, and as a vinylation agent were placed in an autoclave with an internal volume of 100.
0.21 g of THF (tetrahydrofuran) was charged.
7000g of butadiene was added and polymerized at 60°C for 2 hours. To the obtained polymer, 1.5 mmol of tin tetrachloride was added as a coupling agent, and the reaction was continued for an additional hour. After that, 70 g of methanol was added to terminate the polymerization reaction, and 4-methyl-2,6 was added as an antiaging agent. - 50 each of ditertiarybutylphenol and trinonylphenyl phosphorite;
The polymer was precipitated by a steam stripping method. Table 1 shows the physical properties of the polybutadiene rubber obtained by drying using a conventional drying method. [Manufacture of impact-resistant styrenic resin] A rubber solution in which the polybutadiene rubber (A) and polybutadiene rubber (B) obtained above were dissolved in 92 parts by weight of styrene at a combination ratio of 1.0,
The mixture was placed in a No. 100 autoclave, 0.05 parts by weight of dicumyl peroxide and 0.05 parts by weight of tertiary decyl mercaptan were added, and the mixture was stirred at 250 rpm. After purging the inside of the autoclave with nitrogen gas, it was sealed and the temperature was raised. After polymerizing at 110°C for 4 hours, it was cooled, and then 100 kg of pure water, 0.5 g of sodium dodecylbenzenesulfonate, and 800 g of tribasic calcium phosphate were added to an autoclave with a capacity of 200, and while stirring at 130 rpm, 3.
Add 70 kg of the prepolymerization solution to which 77 g of 3-ditertiary butyl peroxybutyl acid ethyl ester was added, and after purging with nitrogen, seal and raise the temperature to 110°C for 3 hours and 120°C for 3 hours. Polymerization was carried out at ℃ for 4 hours and cooled. After neutralization, dehydration, and drying according to a conventional method, the polymer was formed into a conventional pellet shape using an extruder to obtain an impact-resistant styrenic resin. The results of this physical property measurement are shown in Table 1. Examples 2-3, Comparative Examples 1-2 Polybutadiene rubber obtained in Example 1
Impact resistant styrenic resins of Examples 2 to 3 and Comparative Examples 1 to 2 were obtained by the same bulk-suspension polymerization method as in Example 1, with different combination ratios of (A) and (B). Table 1 shows the measured values of these physical properties. Examples 4-5 Polybutadiene rubber (A) and (B) in Example 1
Polybutadiene samples with different microstructures, degree of coupling, and Mw/Mn were obtained using the same method as that used for obtaining polybutadiene samples. Bulk polymerization was carried out under the following conditions by changing the ratio of polybutadiene rubber (A) and polybutadiene rubber (B) used together to obtain an impact-resistant styrenic resin. Polymerization liquid composition: Styrene 92 parts by weight Polybutadiene 8 parts by weight Irganox 1076 1.0 parts by weight t-dodecyl mercaptan 0.0002 parts by weight Polymerization vessel: Jacket with internal volume of 5, 10, 10 and a stirrer Polymerization conditions: 120°C 70 rpm 2 Time: 140°C, 25rpm, 4 hours, 165°C, 10rpm, 4 hours, unreacted monomer removed, 230°C, 45 minutes This was shaped into pellets using a 20mmφ extruder. Table 1 shows the physical property measurement results. Comparative Examples 3 to 6 Polybutadiene rubber (A) and (B) in Example 1
The polybutadiene rubbers (A) and (B) of the present invention were obtained in the same manner as above, and three types of commercially available polybutadiene rubbers were used in combination to obtain impact-resistant styrenic resins. Table 2 shows the brand of the commercially available polybutadiene rubber used and the measured physical properties. Comparative Examples 7 and 8 Polybutadiene rubber (A) and (B) in Example 1
The polybutadiene rubbers (A) and (B) of the present invention were obtained in the same manner as the polybutadiene rubbers (A) and (B) of the present invention. Each of these was used alone to obtain an impact-resistant styrenic resin. Table 2 shows the measured values of these physical properties. The microcomposition of polybutadiene rubber was determined by measuring the infrared spectrum using an infrared spectrophotometer (Model A-302 manufactured by JASCO Co., Ltd.) using carbon disulfide as a solvent, and using the Morello method [D.Morero et al., Chim.6Ind., 41, 758
(1959)]. The Mw/Mn and coupling degree of polybutadiene were determined using GPC [HLC-802A manufactured by Toyo Soda].
Measurement was performed under the following conditions. Solvent: Tetrahydrofuran (THF) Column: Toyo Soda GMH-6 2Feet 2 columns Constant temperature bath temperature: 38℃ Solvent flow rate: 1.5ml/min Sample concentration: 0.1% by weight Sample injection amount: 0.5ml Detector: Differential refractometer data Processing equipment: Toyo Soda CP-8000 Coupling degree is calculated by calculating the peak area ratio on the GPC chart corresponding to the molecular weight of uncoupled rubber and the molecular weight of coupled rubber, respectively, in the GPC data obtained under the above GPC measurement conditions. Find it and use it as coupling %. The physical properties of the rubber-modified styrenic resin were measured by the following method. (1) Tensile strength: According to JIS-K-6871. (2) Izot impact strength: According to JIS-K-6871. (3) Falling weight strength: 2mm thick 12cm x 12 by injection molding
At the center of a cm square plate, weight tip 5R, weight diameter 14
A weight of mmφ1Kg is dropped, and the strength is expressed as the product of the height (cm) at which cracks do not occur and the weight of the weight. The molding machine was a 2-ounce inline screw injection molding machine SN-51B manufactured by Niigata Tekkosho Co., Ltd., and molding was performed at a molding temperature of 230°C. It should be noted that molded products formed by injection molding are susceptible to directionality, and even when they break due to external force, they tend to break in the direction of the molding flow. In this respect, since it is easiest to find the direction of falling weight strength,
In the present invention, falling weight strength is adopted as an expression suitable for the actual situation. (4) Gloss: According to JIS Z-8741 (5) Colorability: 0.5 part of Nippon Pigment Co., Ltd. blue pigment PSD-B-871 was added to 100 parts by weight of resin.
A three-stage step plate is formed by injection molding, and the one that exhibits a deep ultramarine blue color, closest to the color of the pigment itself, and has the best coloring properties is designated A, and the one that has a pale gray-blue color and has the poorest coloring properties. was evaluated as E, and the intermediate values were evaluated as B, C, and D in order.

【table】

【table】

【table】

Claims (1)

[Scope of Claims] 1. Polybutadiene rubber is dissolved in a styrene monomer and the solution is polymerized to produce an impact-resistant styrenic resin. is 20-40%, cis1,
The 4-bond structure is 15 to 35%, and the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw/
Mn) is 1.2 or more and less than 1.8, and the degree of coupling is 50% or more, (B) 1,2 vinyl bond structure is 13 to 30%, cis 1,
The 4-bond structure is 20-50% and the above Mw/Mn is
2.5 or more and 5.0 or less, and coupling degree is 50%
A method for producing an impact-resistant styrenic resin, characterized in that it is used in combination with the above polybutadiene, and (A)/(B) = 3.0 to 1/3. 2. The method for producing an impact-resistant styrenic resin according to claim 1, wherein the polybutadiene rubber is 2 to 15 parts by weight and the styrenic monomer is 85 to 98 parts by weight.