JPH0655873B2 - Impact resistant resin composition - Google Patents

Description

The present invention relates to an impact resistant resin composition, and more particularly to an impact resistant resin composition using a vinyl monomer graft polyorganosiloxane-based graft copolymer.

Generally, the impact resistant resin is formed of a rubber layer and a matrix layer, and it is advantageous to absorb the impact energy by using a resin having a glass transition temperature (Tg) as low as possible in the rubber layer. It is said that there is. This means that a polybutadiene resin having a Tg of −55 ° C. is used as a rubber, and a polybutadiene resin having a Tg of −80 ° C. is used as a rubber.
It is also clear from the fact that ABS resin has better impact resistance. Therefore, if polydimethylsiloxane having Tg of -123 ° C is used as a rubber source of impact-resistant resin,
It is thought that a resin with more excellent impact resistance than ABS resin can be made. However, in general, polyorganosiloxane has poor reactivity with vinyl monomers, and it is difficult to form chemical bonds. Several methods have been disclosed for the bond formation between these two components, but they have not always been satisfactory. For example, in U.S. Pat. No. 3,898,300, a vinyl copolymer is polymerized in an emulsion of a polydimethylsiloxane polymer containing vinyl siloxane or allyl siloxane to form a graft copolymer to improve impact strength. It has been reported. However, the fluidity of the polymer, the surface hardness, and the like that determine the effectiveness as a molding material resin are not described, and the suitability as a molding material is not clear.

U.S. Pat. No. 4,071,577 discloses a method of further improving impact strength by using mercaptosiloxane instead of vinyl group-containing siloxane. That is, the impact strength is greatly changed by the inclusion of the mercapto group in the polydimethylsiloxane-mercaptopropylsiloxane copolymer, and it is shown that the presence of the graft copolymer through the mercapto group improves the impact properties. However, there is no specific description of the graft ratio, and it is not clear whether the graft structure is proper or not. Further, there is no suggestion of polymer fluidity, surface hardness, etc., which define the effectiveness as a molding material resin. The present inventors have conducted various studies in view of such circumstances, and as a result, by using a specific graft crossing agent, the graft efficiency is improved, and the fluidity, impact resistance, surface hardness, etc. of the graft copolymer are improved. It was found that a well-balanced impact resistant resin can be produced.

The present invention is based on this finding, and has the general formula R ¹ _n SiO ( ₄ -n) / ₂ (I) (wherein R ¹ is a hydrogen atom, a methyl group, an ethyl group, a propyl group or a phenyl group, and n is 0). 1 or 2) is added to 100 parts by weight of an organosiloxane having a unit represented by the general formula (Wherein 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, n is 0,
1 or 2, p is a number of 1 to 6) and an organosiloxane graft crossing agent having a unit represented by 0.001 to 0.001
5 to 60% by weight of a graft copolymer obtained by graft-polymerizing 40 to 95% by weight of a methacrylic acid ester and / or an acrylic acid ester to 5 to 60% by weight of a polyorganosiloxane obtained by adding 10 parts by weight of polymerization. And 40 to 95% by weight of a (co) polymer obtained by (co) polymerizing one or more vinyl monomers selected from aromatic alkenyl compounds, methacrylic acid esters, acrylic acid esters and vinyl cyanide compounds. An impact-resistant resin composition containing a polyorganosiloxane-based graft copolymer, which is obtained by mixing.

In producing the polyorganosiloxane-based graft copolymer, first, the polyorganosiloxane is produced by adding and condensing the graft crossing agent of the formula II to the organosiloxane.

As the organosiloxane, for example, hexamethyltricyclosiloxane, octamethyltetracyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane, trimethyltriphenyltricyclosiloxane, etc. are used.

The amount of the graft cross type compound of the formula II added is 0.001 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the organosiloxane. If the amount of the graft crossing agent added is less than 0.001 part by weight, the graft ratio becomes too small and the desired graft effect cannot be obtained. Further, the graft ratio increases in proportion to the amount of the graft crossing agent added, but the degree of polymerization of the graft copolymer decreases with an increase in the amount of the graft crossing agent, so 10 parts by weight or less is preferable. However, the formation of the graft copolymer which is not bonded to the polyorganosiloxane is significantly reduced with the increase of the amount of the graft crossing agent. That is, the grafting efficiency can be remarkably increased, and it is sufficiently possible to obtain the grafting efficiency of 90% or more by appropriately selecting the polymerization conditions.

As described above, methacryloxysiloxane has a very high graft selectivity with respect to vinyl siloxane and mercapto siloxane, and when a graft copolymer is produced using polyorganosiloxane as a trunk polymer, a wide range of graft polymerization conditions for various vinyl monomers can be selected. can do. Polyorganosiloxanes are described in US Pat. No. 289192.
No. 0, No. 3294725, etc., that is, a method of shear mixing in the presence of an organosiloxane and an emulsifier such as an alkylbenzene sulfonic acid as a graft crossing agent of the formula II using, for example, a homogenizer. It is preferable to manufacture. Alkylbenzene sulfonic acid is preferable because it functions as an emulsifier of polyorganosiloxane and also serves as a polymerization initiator.
At this time, it is preferable to use a metal salt of alkylbenzenesulfonic acid in combination, because it is effective in maintaining the polymer stably during the graft polymerization.

In the emulsion polymerization of such an organosiloxane, the polyorganosiloxane may contain a trifunctional or tetrafunctional silicon atom. These polyfunctional silicon atoms act as a so-called cross-linking agent, and the cross-linked polyorganosiloxane using this is effective when used as a rubber source for impact-resistant resins. Specific examples include trifunctional crosslinking agents such as methyltrimethoxysilane, phenyltrimethoxysilane and ethyltriethoxysilane, and tetrafunctional crosslinking agents such as tetraethoxysilane. Of these 100 parts by weight of the polyorganosiloxane polymer, 0.1 to 10% by weight is used to prepare emulsion to form crosslinks of the polyorganosiloxane, and the degree of swelling of the polymer (polyorganosiloxane unit weight However, when saturated at 25 ° C. in a toluene solvent, the weight ratio of toluene absorbed by the polyorganosiloxane) is adjusted to 5.0 to 15.0.

The swelling degree is measured as follows. The prepared polyorganosiloxane latex is added to about 3 to 5 times the amount of isopropyl alcohol with stirring, and the emulsion is broken and coagulated to obtain a siloxane polymer. After washing the polymer thus obtained with water, 8
Dry under reduced pressure at 0 ° C. for 10 hours. After drying, about 1 g of the polymer is precisely weighed, immersed in about 30 g of toluene and left at 25 ° C. for 100 hours, and toluene is added to the polymer to swell. Then, the residual toluene is separated and removed by decantation, precisely weighed, and then dried under reduced pressure at 80 ° C. for 16 hours to evaporate and remove the absorbed toluene, and again weigh precisely. The degree of swelling is calculated by the following formula.

The compound of formula II is then graft polymerized with a methacrylic acid ester and / or an acrylic acid ester. Methacrylic acid esters for this purpose include, for example, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, butyl methacrylate, and the like, and acrylic acid esters include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.

The ratio of the methacrylic acid ester and / or acrylic acid ester to the polyorganosiloxane is 5 to 60% by weight, preferably 5 to 30% by weight, based on the total amount of these.

The methacrylic acid ester and / or the acrylic acid ester can be graft-polymerized to the polyorganosiloxane by a usual radical polymerization method. Various radical polymerization initiators can be used for the graft polymerization, but these initiators must be added before the graft polymerization. Depending on the type of radical polymerization initiator, it is necessary to neutralize the polyorganosiloxane latex acidified with alkylbenzene sulfonic acid with an alkali. As alkali, caustic soda, caustic potash, sodium carbonate,
Sodium hydrogen carbonate, triethanolamine, triethylamine and the like are used.

Examples of the radical polymerization initiator used in the present invention include 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, diisopropyl Organic peroxides such as peroxydicarbonate, dimethyl-2,2'-azobisisobutyrate, 1,1'-azobiscyclohexanecarbonitrile, 2-phenylazo-2,4-dimethyl-4-methoxyvalerronitrile , 2-carbamoylazoisobutyronitrile, 2,2'-azobis-2,4
-Azo compounds such as dimethyl valeronitrile, 2,2'-azobisisobutyronitrile, hydroperoxide-ferrous sulfate-glucose-sodium pyrophosphate, hydroperoxide-ferrous sulfate-dextrose-sodium pyrophosphate-phosphorus Sodium acid salt, hydroperoxide-ferrous sulfate-sodium pyrophosphate-sodium phosphate, hydroperoxide-ferrous sulfate-formaldehyde sodium sulfoxylate-ethylenediamine acetate salt, persulfate-potassium hexacyanoferrate (II), persulfate Redox-based initiators such as salt-sodium thiosulfate-copper sulfate are mentioned. Hydroperoxides include cumene hydroperoxide, tertiary butyl hydroperoxide,
Diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, and the like. Persulfates include potassium persulfate and persulfate. Ammonium sulfate or the like is used. The persulfate can be used alone.

The graft ratio of the graft copolymer was determined by the following method.
The graft copolymer latex is added to about 3 to 5 times the amount of methanol with stirring and the latex is solidified to obtain a graft copolymer. The polymer thus obtained is washed with water and then dried under reduced pressure at 80 ° C. for 10 hours to remove water. After completion of the drying, about 1 g of the polymer is precisely weighed and about 50 ml of acetone is added. This is boiled for about 5 hours at the boiling point of acetone, and the graft copolymer which is soluble in acetone and is not bonded to polyorganosiloxane is dissolved in acetone. After cooling, centrifugation is performed at about 10,000 rpm for 1 hour, and the polymer bound to the polyorganosiloxane and the acetone-soluble polymer are separated by decantation. Acetone was further added to the polymer bonded to the polyorganosiloxane, and the polymer was washed by repeating centrifugation and decantation in the same manner, and then 10 ° C. at 80 ° C.
After drying under reduced pressure for an hour, the weight of the acetone extraction residue is determined. The graft ratio and the graft efficiency are calculated by the following equations.

The obtained graft copolymer latex is coagulated by an ordinary salt coagulation method, and the powder obtained is washed with water and dried, and when mixed with a (co) polymer obtained from a vinyl monomer described below, an impact-resistant resin composition is obtained. The thing is obtained.

Generally, the impact resistant resin is a rubber modified so that a rubber having impact absorption is dispersed in a matrix resin and a proper graft ratio is obtained in order to achieve an affinity between the rubber and the matrix. Here, there is an appropriate range for the graft ratio, and it is preferably 20 to 100% based on the rubber weight. If the graft ratio is 20% or less, the affinity between the matrix and the rubber cannot be secured. 100%
When the graft ratio is above, the polymer fluidity in the case of using an impact resistant resin is impaired, which is unsuitable. Therefore, while maintaining high graft efficiency, the graft ratio is 20
When it is -100%, the amount of free polymer generated during the graft polymerization can be reduced, and a polyorganosiloxane-based graft copolymer having a high rubber content can be produced. However, if it is attempted to carry out all of the matrix resin polymerization after the graft polymerization, the polymerization will be carried out in the presence of rubber, so that it is difficult to adjust the polymer chain length, the copolymerization ratio, etc.
It results in a polymer with low fluidity and low surface hardness. Therefore, at the time of graft polymerization, the structure is provided with fluidity to the extent that it can be compatibilized with the matrix resin,
The remaining matrix resin is preferably added by a blending method.

The (co) polymer is obtained by (co) polymerizing one or more vinyl monomers selected from aromatic alkenyl compounds, vinyl cyanide compounds, methacrylic acid esters, and acrylic acid esters (co). Polymers may be mentioned. For example, a copolymer obtained by copolymerizing 70% by weight of styrene and 30% by weight of acrylonitrile or polymethylmethacrylate is preferable. These (co) polymers can be produced by a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, or the like.

The mixing ratio of each component in the resin composition is 5 to 60% by weight of the polyorganosiloxane-based graft copolymer and 40 to 95% by weight of the (co) polymer. The resin composition is preferably shaped by an extruder to form a pellet. Additives such as a filler, a heat stabilizer, an ultraviolet absorber and a lubricant may be added during extrusion shaping. The pelletized resin composition is processed and molded by usual means such as compression molding and injection molding.

Molded articles comprising the resin composition of the present invention can generally obtain high impact strength with a low polyorganosiloxane content, and have good weather resistance, good surface hardness, good moldability, and excellent resistance to low temperatures. It has excellent properties such as impact resistance.

The impact strength of the molded articles in the following examples is ASTM-D-256.
According to -56, notched test piece (notch is 45 ° and 0.
1 inch depth) was prepared by injection molding and measured by the Izod impact test. The dying shock test was conducted according to the DIN53453 standard. The fluidity of the molded product is shown by the melt flow rate, and is determined by ASTM-D-1238.
Measured according to the standard. The surface hardness of the molded product was shown by the Rockwell method and measured by ASTM-D-785. Reduced viscosity of acrylonitrile-styrene copolymer (ηsp /
C) was measured with an acetone solvent at 25 ° C. at a concentration of 0.1 dl / g.

Reference Example 1.0 parts by weight of ethyl orthosilicate, 0.75 parts by weight of γ-methacryloxypropyldimethoxymethylsilane and 99 parts by weight of octamethyltetracyclosiloxane were mixed and dissolved in 1.0 part by weight of dodecylbenzenesulfonic acid. It was put in 300 parts by weight of distilled water, pre-stirred with a homomixer, and then 250 with a homogenizer.
The mixture was emulsified and dispersed by passing it twice at a pressure of kg / cm ² .

This mixed solution was transferred to a separable flask equipped with a condenser, a nitrogen inlet and a stirring blade, and mixed with stirring 9
The mixture was heated at 0 ° C. for 6 hours to complete the polymerization of polydimethylsiloxane. The polymerization rate of the obtained polyorganosiloxane was 90.3%, the degree of swelling was 9.8, and the particle size of the polyorganosiloxane polymer measured by the turbidity method was 0.14 μ.
It was.

Example 1 The polyorganosiloxane latex obtained in the reference example was neutralized to pH 8 with sodium carbonate, 700 parts by weight of distilled water and 1.5 parts by weight of potassium persulfate were added, and nitrogen was flowed at 75 ° C. As the first-stage graft polymerization, 166 parts by weight of methyl methacrylate was slowly added using a dropping bottle for 2 hours. 1 hour after the dropping, 75 ° C
After the temperature was maintained, a mixed monomer of 66.7 parts by weight of methyl methacrylate and 0.2 parts by weight of n-octyl mercaptan was added as a second stage graft polymerization over a period of 1 hour using a dropping bottle. After the monomer was dropped, the temperature was maintained at 75 ° C. for 2 hours, and then salting out and coagulation were carried out by a conventional method to recover the polymer. The graft ratio of the first-stage polymer was 68.3% and the graft efficiency was 41%.
The polymerization rate of the graft monomer was 99.9%.
50 parts by weight of this polymer powder and 50 parts by weight of polymethylmethacrylate having an ηsp / C of 0.55 dl / g measured with a chloroform solvent were mixed, shaped and molded, and physical properties were evaluated. As a result, the Izod impact value is 21 kg.
・ Cm / cm, melt flow value (230 ℃, 3.8kg load)
Was 0.8 g / 10 minutes and the hardness (R scale) was 118.

Claims (1)

[Claims] 1. A compound represented by the general formula R ¹ _n Si 2 O 3 _{(4-n) / 2} (I) (wherein R ¹ is a hydrogen atom, a methyl group, an ethyl group, a propyl group or a phenyl group, and n is 0, 1 or 2). Of the organosiloxane having a unit represented by the general formula (Wherein 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, n is 0, 1 or 2, and p is a number from 1 to 6). Organosiloxane graft crossing agent having units
1 to 10 parts by weight of a polyorganosiloxane obtained by polymerizing 5 to 60% by weight, and 40 to 95% by weight of a methacrylic acid ester and / or an acrylic acid ester are graft-polymerized. % By weight,
40% to 95% by weight of a (co) polymer obtained by (co) polymerizing one or more vinyl monomers selected from aromatic alkenyl compounds, methacrylic acid esters, acrylic acid esters and vinyl cyanide compounds is mixed. An impact-resistant resin composition containing a polyorganosiloxane-based graft copolymer comprising: