JPH0522724B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an impact-resistant resin, and more specifically, after producing a polyorganosiloxane latex with a controlled particle size and copolymerizing a graft cross-agent showing high grafting efficiency into the organosiloxane, This invention relates to a method for producing impact-resistant resin obtained by graft polymerization. It is known that the weather resistance and impact resistance of vinyl thermoplastic polymers can be improved by polyorganosiloxanes containing graft-polymerizable functional groups. However, when polyorganosiloxane is used as a resin composition, it has poor reactivity with other vinyl monomers, making it difficult to form effective chemical bonds. U.S. Patent No. 3,898,300 states:
It is stated that the impact strength of styrenic polymers can be improved by polymerizing vinyl monomers in emulsions of vinylsiloxane-containing polydimethylsiloxane polymers. This method produces notched Izot impact strengths of 0.4 to 7 foot-pounds, depending on the amount of vinyl siloxane in the siloxane polymer; however, as the amount of siloxane relative to the vinyl polymer increases, impact strength decreases. For example, 20% siloxane has an optimum value of about 7 foot-pounds, but 49%
For siloxane, it drops to 2.1 foot-pounds. In addition, the gel content of the polydimethylsiloxane graft polymer was measured by the acetone extraction method, and the maximum ratio of the graft polymer to polydimethylsiloxane was 1.76, and the ratio of monomers involved in grafting among the graft monomers was 10.97%. Grafting efficiency is extremely poor. Therefore, as the amount of siloxane relative to the vinyl polymer increases, the impact strength decreases. US Pat. No. 4,071,577 describes a method for improving the impact strength of vinyl polymers by replacing vinyl-containing siloxanes with mercaptosiloxanes. However, the impact strength of vinyl polymers obtained by this method varies greatly depending on the mercapto group content in the polydimethylsiloxane-mercaptopropylsiloxane copolymer, and the presence of graft polymers via mercapto groups is responsible for the impact strength. has been shown to improve However, there is no description of the graft ratio, nor is there any description of the rubber particle diameter during emulsion polymerization. In general, as a means of improving impact resistance, it is desirable for the grafting rate to have as high a grafting efficiency as possible in terms of resin production, and for the rubber particle size of the rubber component, the optimum particle size that can exhibit impact resistance is determined by the grafting monomer. If present and acrylonitrile-styrene graft polymer
It is said to be 0.2 to 0.3μ. As a result of various studies in view of the above situation, the present inventors discovered that, in order to obtain a polyorganosiloxane rubber, the particle size of the resulting siloxane rubber and the grafting agent were devised during emulsion polymerization of siloxane. It has been found that the grafting efficiency of the grafting monomer can be improved and a resin composition having good impact resistance and weather resistance can be obtained. In the present invention, in the presence of polyorganosiloxane,
Represented by the general formula R ¹ nSiO _(4-o)/2 () (in the formula, R ¹ is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a phenyl group, and n represents the number of 0, 1, or 2) 100 parts by weight of an organosiloxane having the unit and the general formula (In the formula, R ² is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a phenyl group, R ³ is a hydrogen atom or a methyl group, m is 0, 1, or 2, and p is a number from 1 to 6) This is a method for producing an impact-resistant resin, which comprises graft-polymerizing a vinyl monomer onto polyorganosiloxane particles obtained by polymerizing 0.001 to 10 parts by weight of an organosiloxane graft-crossing agent having units of 0.001 to 10 parts by weight. According to the method of the present invention, the particle size of the polymer can be adjusted to a range where the impact resistance and absorption ability is maximized, that is,
It can be controlled to 0.2~0.3μ. Furthermore, since the grafting efficiency of the polymer is high, the amount of grafting monomer can be suppressed, which is advantageous for exhibiting impact resistance performance. Important factors that determine the graft structure include the proportion of polymer grafted to the backbone polymer, that is, the grafting ratio, as well as the proportion of grafted monomers in the polymerized monomer, that is, the grafting efficiency.
It has been extremely difficult to control the grafting efficiency to polyorganosiloxane using conventional methods. Vinyl group-containing polyorganosiloxanes or mercapto group-containing polyorganosiloxanes are known as graft cross-agents in conventional methods, but it is difficult to achieve a grafting efficiency of 40% or more no matter which graft cross-agent is used. It was hot. On the other hand, when using the graft crossover agent of the formula, not only a high grafting rate but also a high grafting efficiency, that is, a grafting efficiency of 40% or more can be easily obtained. In producing the polymer of the present invention, a polyorganosiloxane is produced by first adding a grafting agent of the formula formula to an organosiloxane and polymerizing it in the presence of a polyorganosiloxane latex whose polymerization is almost completed. Examples of organosiloxane include hexamethyltricyclosiloxane, octamethyltetracyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane,
Trimethyltriphenyltricyclosiloxane and the like are used. The amount of the grafting agent of the formula added is 0.001 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the organosiloxane. If the amount of the grafting agent added is less than 0.001 parts by weight, the grafting ratio will be too small to obtain the desired grafting effect. Furthermore, although the graft ratio increases in proportion to the amount of the graft cross-agent added, the degree of polymerization of the graft polymer decreases as the amount of the graft cross-agent increases, so it is preferably 10 parts by weight or less. However, the formation of graft polymers that are not bonded to polyorganosiloxane decreases significantly as the amount of graft cross-agent increases. In other words, the grafting efficiency can be significantly increased, reaching 90% if the polymerization conditions are appropriately selected.
It is also fully possible to obtain the above grafting efficiency. In the polymerization of organosiloxane, the polymerized polyorganosiloxane latex is 1 to 50% by weight, preferably 10 to 30% by weight in terms of polymer.
It is necessary to carry out the process in the presence of this latex. Polyorganosiloxane latex with almost complete polymerization can be prepared by adding organosiloxane to an aqueous alkylbenzenesulfonic acid solution, adding a cyclic or linear low-molecular-weight siloxane, preferably a terminally hydroxy-blocked polysiloxane, a crosslinking agent and a formula crosslinker as necessary. It can be obtained by adding an agent, homomixing, and then carrying out ordinary emulsion polymerization. This is used as a prepolymerized latex. Cyclic or linear low-molecular-weight siloxanes and crosslinking agents include, for example, the general formula R ₄ 4qSiO _(4-q)/2 (wherein R ⁴ is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a phenyl group, q represents 0, 1 or 2). A mixture of this prepolymerized latex and an aqueous alkylbenzenesulfonic acid solution is prepared, an organosiloxane and a grafting agent of the formula are added to this mixture, and by homomixing, a low molecular weight siloxane is added to the polymer in the polyorganosiloxane latex. Large particle size polyorganosiloxane latex can be obtained by swelling and enlarging the particles and then carrying out conventional emulsion polymerization. The polymer particle size of prepolymerized latex is 0.08~
0.16μ, and the particle size after swelling and swelling polymerization is 0.17
~0.40μ. The rate of increase in particle size varies depending on the proportion of prepolymerized latex used and the amount of crosslinking agent. Copolymerization of a grafting agent is not necessarily required in the production of prepolymerized latexes. Further, such swelling and enlargement polymerization can be carried out repeatedly, but as the number of repeated polymerization increases, the rate of increase in the latex particle size decreases. The polyorganosiloxane must contain trifunctional or tetrafunctional silicon atoms in order to properly gel. This silicon atom acts as a so-called crosslinking agent. Trifunctional crosslinking agents such as methyltrimethoxysilane, phenyltrimethoxysilane, and ethyltriethoxysilane, or tetrafunctional crosslinking agents such as tetraethoxysilane, per 100 parts by weight of organosiloxane represented by the formula,
By preparing an emulsion using 0.1 to 10% by weight, gelation of the polyorganosiloxane is caused, and the degree of swelling of the polymer (when the unit weight of the polyorganosiloxane is saturated at 25°C in a toluene solvent, the polyorganosiloxane is The weight ratio of absorbed toluene is adjusted to 4-30, preferably 5-15. The degree of swelling is measured as follows. Adding the polyorganosiloxane latex to about 3 to 5 times the amount of isopropyl alcohol while stirring,
The siloxane polymer is obtained by breaking and coagulating the emulsion. The polymer thus obtained is washed with water and dried under reduced pressure at 80°C for 10 hours. After drying,
Approximately 1 g of polymer is accurately weighed, immersed in approximately 30 g of toluene, and left at 25°C for 100 hours to allow the toluene to swell in the polymer. Next, the remaining toluene is separated and removed by decantation, weighed accurately, and then dried under reduced pressure at 80° C. for 16 hours, the absorbed toluene is removed by evaporation, and weighed accurately again. The swelling degree is calculated by the following formula. Swelling degree=
(Swollen polymer weight) - (Dry polymer weight)/(
Dry Polymer Weight) The emulsion polymerization of organosiloxane can be carried out by a normal emulsion polymerization method, but it is preferable to age the latex by cooling it after polymerization and storing it at a low temperature. By polymerizing the polyorganosiloxane thus obtained with a graft monomer, a polyorganosiloxane graft polymer can be produced. This polymerization reaction can be carried out by conventional radical polymerization techniques. Examples of graft monomers include aromatic alkenyl compounds such as styrene, α-methylstyrene, and methylenestyrene; methacrylic esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate; and acrylonitrile. , conjugated diolefins such as methacrylonitrile, ethylene, propylene, butadiene, isoprene, and chloroprene, vinyl acetate, vinyl chloride, vinylidene chloride, allyl methacrylate, triallyl isocyanurate, ethylene dimethacrylate, etc., and mixtures of two or more of these. used. Preferred monomer proportions include 65-75% by weight styrene and 25-35% by weight acrylonitrile. Various radical polymerization initiators can be used during graft polymerization. Further, when using a certain type of radical polymerization initiator, it is necessary to neutralize the polyorganosiloxane latex acidified with alkylbenzenesulfonic acid to neutrality with an alkali. As alkali, caustic soda,
Caustic potash, soda carbonate, sodium hydrogen carbonate, triethanolamine, triethylamine, etc. are used. As the radical polymerization initiator, for example, the following compounds are used. Ditertiary butyl peroxide, dicumyl peroxide, tertiary butyl perphthalate, tertiary butyl perbenzoate, tertiary butyl peracetate, ditertiary amyl peroxide, methyl isobutyl ketone peroxide, lauroyl peroxide, cyclohexanone peroxide , 2,5-dimethyl-2,5-ditertiary butyl peroxyhexane, tertiary butyl peroctanoate, tertiary butyl perisobutyrate, tertiary butyl peroxyisopropyl carbonate,
Organic peroxides such as diisopropyl peroxydicarbonate; dimethyl-2,2'-azobisisobutyrate, 1,1'-azobiscyclohexanecarbonitrile, 2-phenylazo-2,4-dimethyl-4-methoxyvalero Azo compounds such as nitrile, 2-carbamoylazoisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobisisobutyronitrile; and hydroperoxide-ferrous sulfate - glucose - sodium pyrophosphate, hydroperoxide - ferrous sulfate - dextrose sodium pyrophosphate - sodium phosphate, hydroperoxide - ferrous sulfate - sodium pyrophosphate - sodium phosphate, hydroperoxide - ferrous sulfate - formaldehyde Redox initiators such as sodium sulfoxylate-ethylenediamine acetate, persulfate-potassium hexacyanoferrate, and persulfate-sodium thiosulfate-copper sulfate. Hydroperoxides include cumene hydroperoxide, tertiary butyl hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethylhexane-2,5 -dihydroperoxide etc. are used. Persulfates include potassium persulfate,
Ammonium persulfate etc. are used. Persulfates can also be used alone. As a graft cross-agent, free radicals are added to mercaptosiloxane and vinyl groups, which utilizes the continuous addition reaction of graft monomers through chain transfer of mercapto groups, and the generated radicals undergo continuous addition reactions of graft monomers. Although vinyl siloxane, acryloxysiloxane, or methacryloxysiloxane that takes advantage of the above formula is considered, it is known that acryloxysiloxane or methacryloxysiloxane of the formula shows a specifically high grafting efficiency. This is presumed to be because the acryloxy group or methacryloxy group, unlike the vinyl group, receives an electron-withdrawing effect from the adjacent carbonyl group, thereby greatly increasing its reactivity. The ratio of the graft monomer to the polyorganosiloxane can be set to 1 to 70% by weight for graft polymerization. Preferably 20~
It is 60% by weight. The grafting ratio of the graft polymer is determined as follows. A graft polymer is obtained by adding the graft polymer latex to about 3 to 5 times the amount of methanol with stirring and coagulating the latex. The polymer thus obtained was washed with water and then dried under reduced pressure at 80°C for 10 hours to remove moisture. After drying, accurately weigh about 1g of polymer and add about 50ml.
of acetone. This is boiled for about 5 hours at the boiling point of acetone, and the acetone-soluble graft polymer not bonded to the polyorganosiloxane is dissolved in the acetone. After cooling, approx.
After centrifugation at 10,000 rpm for 1 hour, the polymer bound to polyorganosiloxane and the acetone-soluble polymer are separated by decantation. The polymer bound to the polyorganosiloxane is washed by further adding acetone and repeating the same centrifugation and decantation operations, and then dried under reduced pressure at 80° C. for 10 hours, and then the weight of the acetone-extracted residue is determined. The grafting rate and grafting efficiency are calculated by the following formula. Grafting rate (%) = (Acetone extraction residue weight) - (Polyorganosiloxane weight) / (Polyorganosiloxane weight) x 100 Grafting efficiency (%) = Grafting rate (%) /
Proportion of graft monomer (%) x 100 It is preferable to coagulate this graft polymer latex by a normal salting-out coagulation method, wash the obtained powder with water, dry it, shape it with an extruder, and pelletize it. . At this time, in order to dilute the siloxane polymer content in the shaped polymer, a polymer such as an acrylonitrile-styrene copolymer may be added and extrusion shaped. Additionally, additives such as fillers, heat stabilizers, ultraviolet absorbers, and lubricants may be added during extrusion shaping. The pelletized siloxane polymer is processed and molded by conventional means such as compression molding and injection molding. Impact strength was measured using an Izod impact tester on notched specimens (notches at 45° and 0.1 inch deep) prepared by injection molding in accordance with ASTM-D-256-56. Example 1 3.0 parts by weight of ethyl orthosilicate, 1.5 parts by weight of γ-methacryloxypropylmethyldimethoxysilane
Parts by weight and octamethyltetracyclosiloxane
97 parts by weight were mixed, and this was poured into 300 parts by weight of distilled water in which 2.0 parts by weight of dodecylbenzenesulfonic acid had been dissolved, and emulsified by stirring at 8000 rpm for 3 minutes using a homomixer. This emulsion is poured into a condenser,
The mixture was transferred to a separable flask equipped with a nitrogen inlet and a stirring blade, and heated at 90° C. for 6 hours while stirring.
This latex is called (A). Obtained latex
The weight percentage of (A) is 90.2%, the degree of swelling is 9.6, and the particle size of the polyorganosiloxane polymer measured by the turbidity method is
It was 0.13μ. 40 parts by weight of latex (A), 1.8 parts by weight of dodecylbenzenesulfonic acid, and 270 parts by weight of distilled water were mixed and stirred to be homogeneous. A mixture of 2.7 parts by weight of ethyl orthosilicate, 0.675 parts by weight of γ-methacryloxypropylmethyldimethoxysilane and 87.3 parts by weight of octamethyltetracyclosiloxane was added to this mixture, and the mixture was mixed with a homomixer.
The mixture was emulsified by stirring at 8000 rpm for 3 minutes. then 90
The siloxane was polymerized by heating at ℃ for 6 hours. This latex is called (B). The polymerization rate of the obtained polyorganosiloxane is
The degree of swelling was 90.8%, the degree of swelling was 9.9, and the particle size of the polyorganosiloxane polymer measured by turbidity method was 0.20μ. This polyorganosiloxane latex (B),
Adjust the pH to 7.5 with an aqueous sodium carbonate solution, dissolve 1.0 parts by weight of sodium dodecylbenzenesulfonate, 700 parts by weight of distilled water, and 1.5 parts by weight of potassium persulfate, and prepare a separator equipped with a condenser, nitrogen inlet, and stirrer. The mixture was transferred to a blue flask and heated to 75°C in a nitrogen stream. Then acrylonitrile 50
A mixed monomer mixture of parts by weight and 150 parts by weight of styrene was slowly added using a dropping bottle over about 4 hours. After the monomer dropwise addition was completed, the polymerization reaction was carried out for 2 hours, and after the polymerization was substantially completed, the mixture was cooled. The polymer particle size of the obtained latex was 0.32μ
It was hot. This latex was mixed with 15 parts by weight of _CaCl2 .
The polymer was separated by pouring it into hot water in which 2H ₂ O was dissolved and performing salting out coagulation. After washing thoroughly with water, heat at 80℃.
After drying for 16 hours, a polyorganosiloxane grafted polymer powder was obtained. The grafting ratio of the obtained grafted polymer was 87.6
%, and the polymerization rate of the graft monomer was 99.7%.
The monomer charge ratio of 60% by weight of this graft polymer powder and acrylonitrile and styrene is 25:
75% by weight of the copolymer obtained by polymerization,
Using a single screw extruder with L/D=25, heated to 220℃,
It was shaped to obtain pellets. This pellet was injection molded into a notched Izot test mold to obtain an Izot test piece. The Izot impact value of this test piece was 49.6 kg·cm/cm. Example 2 The type and amount of crosslinking agent used during polymerization of polydimethylsiloxane rubber was investigated. Siloxane rubber was repeatedly polymerized using various crosslinking agents, with the prepolymerization composition and the swelling and swelling polymerization composition being the same, and the degree of swelling and polymerization rate were measured.
The results are shown in Table 1. The polymerization conditions were the same as in Example 1, at 90° C. for 6 hours, and the swelling and swelling polymerization was carried out in the presence of 10% by weight of the latex prepared in the preliminary polymerization. The particle diameter of the obtained latex was measured by a turbidity method, and the results shown in Table 1 were obtained. It is known that there is a correlation between the degree of swelling of the siloxane polymer and the particle size of the latex, and the greater the degree of swelling, the larger the particle size of the latex.

[Table] Example 3 The amount of γ-methacryloxypropyldimethoxymethylthilane used as a graft cross-agent was changed, and the other conditions were the same as those of Example 1. Swelling and swelling polymerization was performed using prepolymerization. It was carried out in the presence of 10% by weight. Next, acrylonitrile and styrene were graft-polymerized. Graft polymer thus obtained and Example 1
The acrylonitrile-styrene copolymer used in Example 1 was mixed in the same proportion as in Example 1. The relationship between the impact resistance performance and the graft ratio of the obtained resin composition was investigated, and the results shown in Table 2 were obtained. It is known that as the amount of γ-methacryloxypropyldimethoxymethylsilane increases, the grafting rate increases greatly, the grafting efficiency also increases, and the amount of polymer not involved in grafting decreases. It is also known that the impact resistance converges to a certain value as the grafting ratio increases.

[Table] Example 4 Using 400 parts by weight of the polyorganosiloxane latex (B) produced by swelling and swelling polymerization in Example 1, the pH was adjusted to 7.8 with an aqueous sodium carbonate solution.
700 parts by weight of distilled water and 2.0 parts by weight of potassium persulfate were mixed, and the mixture was transferred to a separable flask equipped with a dropping bottle, a condenser, a nitrogen inlet, and a stirring blade, and the temperature was raised to 74° C. while flowing nitrogen. To this, 200 parts by weight of methyl methacrylate monomer and n
- A mixture of 0.2 parts by weight of octyl mercaptan was slowly added dropwise over a period of about 3 hours. then 2
After maintaining the reaction for a time, it was cooled and the graft polymer was evaluated in the same manner as in Example 1. The grafting rate of the obtained graft polymer was 93.6%, and the grafting efficiency was 46.8%. Also, the 1/4 inch notched Izot value at this time was 11.6Kg・cm/
It was cm. On the other hand, using 400 parts by weight of the polyorganosiloxane latex (A) produced in Comparative Example 1,
Similarly, when a graft polymer was prepared by performing graft polymerization with a mixture of 200 parts by weight of methyl methacrylate monomer and 0.2 parts by weight of n-octylmercabutane, the grafting rate of the polymer was 56.2% and the grafting efficiency was 28.1%. . At this time, the 1/4 inch notched Izotsu value is 4.6Kg・cm/
It was cm. Comparative Example 1 Polydimethylsiloxane was produced in the same manner as in Example 1 except that 0.75 parts by weight of vinylsiloxane or 0.75 parts by weight of mercaptosiloxane was used instead of γ-methacryloxypropyldimethoxymethylsilane during polymerization of polyorganosiloxane. Then, acrylonitrile and styrene were graft-polymerized. Furthermore, the acrylonitrile-styrene copolymer used in Example 1 was blended in the same manner,
The obtained resin composition was extruded and molded. Extrusion, molding, etc. were performed in the same manner as in Example 1. Table 3 shows the grafting rate, grafting efficiency, and physical properties of the molded product of the obtained polymer.

[Table] Comparative Example 2 A graft polymer was produced using the latex (A) obtained in Example 1. After adjusting 400 parts by weight of latex (A) to pH 7.5 with an aqueous sodium carbonate solution, sodium dodecylbenzenesulfonate, distilled water and potassium persulfate were added in the same manner as in Example 1, followed by 50 parts by weight of acrylonitrile and 150 parts by weight of styrene. The mixture was slowly added dropwise over about 4 hours using a dropping bottle.
After the dropwise addition was completed, the reaction was continued for 2 hours and then cooled.
The polymer was separated by pouring it into CaCl ₂ .2H ₂ O water. Example 1: 60 parts by weight of this graft polymer powder
Acrylonitrile-styrene copolymer 40 used in
It was mixed with parts by weight and shaped into pellets. An Izot test piece was prepared from this pellet, and the Izot impact value was determined, and the value was as low as 19 kg·cm/cm.

Claims (1)

[Claims] 1 In the presence of polyorganosiloxane, a compound of the general formula R ¹ _o SiO _(4-o)/2 () (wherein R ¹ is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a phenyl group) , n represents a number of 0, 1 or 2), and 100 parts by weight of an organosiloxane having the general formula (In the formula, R ² is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a phenyl group, R ³ is a hydrogen atom or a methyl group, m is 0, 1, or 2, and p is a number from 1 to 6) 1. A method for producing an impact-resistant resin, which comprises graft-polymerizing a vinyl monomer onto polyorganosiloxane particles obtained by polymerizing 0.001 to 10 parts by weight of an organosiloxane graft cross-agent having units of 0.001 to 10 parts by weight.