JPS6146004B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an impact-resistant vinyl chloride resin-reinforcing graft polymer with excellent weather resistance. As is well known, vinyl chloride resins have good mechanical and chemical properties and are widely used commercially. However, the disadvantage of vinyl chloride resins is that they have poor impact resistance, and various methods for improving this are known. For example, a widely used method is to mix a butadiene-styrene-methyl methacrylate graft polymer or, in some cases, a polymer obtained by grafting unsaturated nitrile with a vinyl chloride resin to improve impact strength. It is being said. However, since these graft polymers contain a large amount of double bonds in their main chains, they rapidly deteriorate when left outdoors, resulting in extremely low impact resistance. Therefore, many reinforcing agents have been proposed that do not impair this impact resistance and also have weather resistance. Typical examples include ethylene-vinyl acetate copolymer rubber grafted with vinyl chloride, and cross-linked acrylic acid ester-based rubber grafted with methyl methacrylate, styrene, and acrylonitrile monomers. Are known. However, these still have insufficient impact resistance and have a significant decrease in tensile strength. On the other hand, a method has also been proposed in which methyl methacrylate is graft-polymerized onto an acrylic acid ester-conjugated diolefin copolymer rubber. (Special Public Interest Publication 1969-9628)
However, in this method, since the graft component is methyl methacrylate, although it has excellent thermal stability, it is difficult to develop impact strength. In order to improve these problems, proposals have been made such as a method of graft polymerizing methyl methacrylate and styrene in two stages and a method of graft polymerizing methyl methacrylate, styrene, and acrylonitrile to acrylic acid ester-conjugated diolefin copolymer rubber. has been done. (Japanese Patent Publication No. 50-40142, 46-31458) However, these are still insufficient in strength, especially in low kneading processes such as pipe extrusion molding. On the other hand, containing acrylonitrile is unfavorable in terms of thermal stability and hygiene. The inventors of the present invention have conducted extensive research to overcome these drawbacks and have discovered an interesting fact. That is, when graft polymerizing methyl methacrylate and styrene to the acrylic acid ester-conjugated diophine copolymer rubber, methyl methacrylate and styrene such as ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate are used as graft polymerization components. It has been found that when a monomer whose glass transition temperature is lower than that of the polymer is used in combination, extremely high impact strength is exhibited, and the decrease in tensile strength is extremely small. Based on the above-mentioned findings, we have succeeded in obtaining a graft polymer that provides a weather-resistant vinyl chloride resin composition that has excellent tensile strength and high impact strength, which has not been previously available. The present invention is directed to an acrylic acid alkyl ester having an alkyl group having 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms.
95% by weight, preferably 60 to 90% by weight, 5 to 50% by weight, preferably 10 to 40% by weight of a conjugated diolefin, and 0 to 5% by weight, preferably 0.01 to 3% by weight of a polyfunctional crosslinking agent. 40-90% by weight of methyl methacrylate, preferably 40-80% by weight, and 5-50% by weight of styrene, preferably 10-40% by weight, and ethyl methacrylate, butyl methacrylate in the presence of 50-80 parts by weight of a stem rubber polymer. , ethyl acrylate, and butyl acrylate, preferably 5 to 50% by weight of one or more monomers selected from the group consisting of 5 to 40% by weight,
And the glass transition temperature (Tg) of the polymer is 20℃
This is a graft polymer for reinforcing a vinyl chloride resin, which is obtained by graft polymerizing 20 to 50 parts by weight of a mixed monomer at a temperature of 50 to 95°C, preferably 50 to 95°C. This will be explained in detail below. The degree of weather resistance deterioration of a conjugated diolefin-containing vinyl chloride resin reinforcing agent is controlled by the conjugated diolefin content in the reinforcing agent. That is, if the content of conjugated diolefin in the base rubber polymer exceeds 50% by weight, the ability of the reinforcing agent to enhance weather resistance is significantly lost. On the other hand, if the conjugated diolefin content in the backbone rubber polymer is less than 5% by weight, its ability to strengthen impact resistance will be poor. That is, an amount of conjugated diolefin in the base rubber polymer of 5 to 50% by weight is optimal for a graft polymer that also has impact resistance and weather resistance. The base rubber polymer of the present invention is usually produced by emulsion polymerization. The acrylic acid alkyl ester used at this time has an alkyl group having 2 to 12 carbon atoms, and may be linear or branched. Examples include ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. These monomers can be used alone or in combination. Typical conjugated diolefins copolymerized with alkyl acrylates include butadiene, isoprene, and the like, and these can be used alone or in combination. The polyfunctional crosslinking agent used by copolymerizing with acrylic acid alkyl ester and conjugated diolefin is 0
It is used in a range of 5% by weight. More than 5% by weight,
The use of polyfunctional crosslinkers significantly reduces the impact resistance effect. Examples of polyfunctional crosslinking agents include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate,
1,3-butylene glycol diacrylate,
1,4-butylene glycol diacrylate,
Di- or triacrylates of polyhydric alcohols such as 1,6-hexene glycol diacrylate and trimethylolpropane triacrylate, di- or trimethacrylates of polyhydric alcohols corresponding to the above acrylic acid, polyhydric alcohols such as ethylene glycol divinyl ether, etc. polyvinyl esters of polybasic acids such as divinyl ether, divinylbenzene, divinyl adipate, diallyl phthalate, diallyl maleate, diallyl fumarate,
Polybasic acids such as diallyl sebacate, di- or triallyl esters, diallyl ethers, triallyl cyanurate, triallyl isocyanurate, triallyl compounds such as triallylphosphate,
allyl methacrylate, allyl acrylate,
Examples include polyfunctional unsaturated compounds such as allyl esters of polymerizable carboxylic acids such as allyl itaconate, monoallyl fumarate, and monoallyl maleate. Among these polyfunctional crosslinking agents, crosslinking agents containing di- or triacrylates of polyhydric alcohols and allyl groups are particularly preferred. The backbone rubber polymer should be 50 to 80 parts by weight in the graft polymer. If the amount is less than 50 parts by weight, the effect of improving the impact resistance of the resulting composition of the graft copolymer and vinyl chloride resin will be small. or,
If it exceeds 80 parts by weight, it will become lumpy during the salt (acid) precipitation or drying stage, making it difficult to mix uniformly with the vinyl chloride resin, which will cause variations in the physical properties of the resulting molded product. The aqueous dispersion of the trunk rubber polymer is preferably obtained by an emulsion polymerization method, and a known method is used as the emulsion polymerization method, in which the rubber monomer is mixed with an emulsifier,
The entire amount may be initially charged together with the initiator and other additives, or the entire amount or a portion thereof may be added continuously or intermittently while polymerization proceeds. The average primary particle diameter of the base rubber polymer latex can be 0.08 to 0.3μ, but the average particle diameter of 0.12 to 0.4, which is obtained by adding a flocculant to this rubber latex to cause micro-agglomeration, can be used.
It is also possible to use μ agglomerated rubber particles. As the flocculant, hydrochloric acid, sulfuric acid, inorganic salts, organic acids and organic acid anhydrides, which are generally used as latex flocculants, and organic substances having flocculating properties can be used. The graft polymerization in the present invention is usually carried out by grafting 20 to 50 parts by weight of the graft monomer into an aqueous medium containing 50 to 80 parts by weight of the above-mentioned trunk rubber polymer in an emulsified and dispersed manner. At this time, ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate, which are copolymerized with methyl methacrylate and styrene, are essential components to obtain high impact strength.
The species and type must be carefully examined. In other words, if the glass transition temperature of the graft component polymer is too low, the tensile strength will drop significantly, and in extreme cases, it will form into lumps during coagulation and drying, making it difficult to mix uniformly with the vinyl chloride resin. On the other hand, if the glass transition temperature is too high, It becomes difficult to develop impact resistance strength. If the styrene content in the graft component exceeds 50% by weight, the compatibility with the vinyl chloride resin will deteriorate and the tensile strength will drop significantly. In other words, in order to maintain the high tensile strength of vinyl chloride resin and to stably provide high strength development ability, the styrene content in the graft component should be increased from 5 to 50%.
50% by weight, and the Tg of the graft component polymer
It is important to set the temperature between 20℃ and 95℃. The Tg of the graft component polymer does not necessarily need to be measured, but can be substituted with a value expressed as the sum of the polymerization fraction of each monomer in the graft component multiplied by the Tg of the homopolymer of each monomer. is practical. In the present invention, the values in Table 1 below in the Polymer Handbook were used as the Tg of the homopolymer of each monomer.

[Table] The graft monomer can be polymerized in whole or in part by adding it continuously or all at once. Graft polymerization may be carried out using known redox-type initiator systems or thermally decomposed initiators. The graft polymer obtained by the above method may be salted out, coagulated, and dried by known methods, and at this time it is also possible to co-coagulate it with an aqueous dispersion of vinyl chloride resin or the like. It is also possible to add known antioxidants, ultraviolet absorbers, heat stabilizers such as vinyl chloride resins, etc. during coagulation. The graft polymer obtained by the above method is mixed with a vinyl chloride resin to form a vinyl chloride resin composition that has weather resistance, impact resistance, and excellent tensile strength. Mixed in a way. In the case of powder mixing, a Henschel mixer, a Banbury mixer, a ribbon blender, etc. are used. The amount of graft polymer to be mixed with vinyl chloride resin varies depending on the application, but generally 3 to 30% of graft polymer is mixed to 97 to 70% by weight of vinyl chloride resin.
Weight%. In addition, vinyl chloride-based resins include vinyl chloride homopolymers, copolymers containing vinyl chloride in an amount of 70% by weight or more, and vinyl chloride monopolymers or vinyl chloride copolymers with a dominant amount and a subordinate amount of chlorine. Examples include a mixture with 63 to 70% chlorinated vinyl chloride polymer. It is also possible to add specific processing aids, stabilizers, ultraviolet absorbers, lubricants, fillers, antistatic agents, or, if necessary, plasticizers, if necessary. Examples will be shown below, where parts are by weight. Example 1 The following components were charged into a pressure vessel and polymerized at 40°C for 12 hours. Water 150 parts n-Butyl acrylate 45 Butadiene 15 Ethylene glycol dimethacrylate 1.0 Ferrous sulfate (FeSO _{4.7H 2} O) 0.005 Ethylenediamine tetraacetate disodium salt 0.01 Sodium formaldehyde condensed naphthalene sulfonate 0.2〃 Sodium oleate 3.0〃 Cumene hydroperoxide 0.05〃 Sodium formaldehyde sulfoxylate
0.05〃 The average particle size of the obtained rubber latex is 0.1μ
The polymerization yield was 99%. To the obtained base rubber polymer latex, 40 parts of a 0.3% aqueous hydrochloric acid solution was gradually added to effect flocculation, and then a 2% aqueous sodium hydroxide solution was added to stabilize the latex. The rubber latex was aggregated to an average particle size of 0.15μ. To this, the graft components shown below were polymerized at 60°C for 6 hours. The polymerization conversion rate was 98%.

[Table] The desired graft polymer was obtained by salting out and dehydrating and drying the obtained polymer latex. The obtained graft polymer was molded into a 1-inch hard vinyl chloride pipe of 80 mm diameter under the following lead compounding conditions.
This was carried out using a twin-screw extruder with different directions. Blended polyvinyl chloride (degree of polymerization 1000) 100 parts Graft polymer of the present invention 7 Lead stabilizer 2.0 Calcium stearate 1.0 Wax lubricant 0.5 The physical properties of the molded product were as shown in Table 2. Examples 2 to 10 and Comparative Examples 1 to 7 are summarized in a table.
Shown in 2. The polymerization conditions other than the graft polymerization components listed in Table 2 and the mixing molding conditions with the vinyl chloride resin are all the same as in Example 1.

[Table] Example 11 To the trunk rubber polymer latex obtained in the same manner as in Example 1, 28 parts of a 1% acetic acid aqueous solution was gradually added to cause flocculation, and then a 2% aqueous sodium hydroxide solution was added. was added to stabilize it. The rubber latex was aggregated to an average particle size of 0.15μ. 2% to this
10 parts of an aqueous potassium persulfate solution was added, and the following graft component was polymerized at 60° C. for 6 hours. The polymerization conversion rate was 99%. Graft polymerization components Methyl methacrylate 25 parts Styrene 10 parts Butyl methacrylate 5 parts The obtained polymer latex was salted out and dehydrated and dried to obtain the intended graft polymer. The obtained graft polymer was molded into a 1-inch hard vinyl chloride pipe in the same manner as in Example-1. The physical properties of the molded product were as shown in Table 3. Example 12 A 10% aqueous sodium sulfate solution was added to the base rubber polymer latex obtained in the same manner as in Example 1.
10 parts of a 2% aqueous potassium persulfate solution and 65 parts of water were added, and the following graft components were polymerized at 60°C for 6 hours. The polymerization conversion rate was 99%. Furthermore, at the end of the graft polymerization, the latex had an average particle size of 0.16μ. Graft polymerization components Methyl methacrylate 25 parts Styrene 10 parts Butyl methacrylate 5 parts The obtained polymer latex was salted out and dehydrated and dried to obtain the intended graft polymer.
The obtained polymer was molded into a 1-inch hard vinyl chloride pipe in the same manner as in Example-1. The physical properties of the molded product were as shown in Table 3.

【table】

【table】

Claims (1)

[Claims] 1. A backbone rubber polymer obtained by copolymerizing 50 to 95% by weight of an acrylic acid alkyl ester having an alkyl group with 2 to 12 carbon atoms, 5 to 50% by weight of a conjugated diolefin, and 0 to 5% by weight of a polyfunctional crosslinking agent. In the presence of 50 to 80 parts by weight, 40 to 90% by weight of methyl methacrylate, 5 to 50% by weight of styrene, and one or more selected from ethyl methacrylate, butyl methacrylate, ethyl acrylate, and butyl acrylate. Monomer 5 of
~50% by weight of vinyl chloride, characterized in that it is obtained by graft polymerization of 20 to 50 parts by weight of a mixed monomer whose glass transition temperature is set between 20°C and 95°C. Graft polymer for reinforcing system resins.