JPS637565B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an impact-resistant vinyl chloride resin-reinforcing graft polymer that has excellent weather resistance. As is well known, vinyl chloride resins have good mechanical and chemical properties and are widely used in practical applications. 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 butadiene-styrene-methyl methacrylate graft copolymer or, in some cases, a graft copolymer obtained by graft copolymerizing an unsaturated nitrile monomer thereto is mixed with a vinyl chloride resin to increase impact resistance. There are widely used methods to improve However, since these graft copolymers contain a large amount of double bonds brought in by butadiene in their main chains, they rapidly deteriorate if left outdoors, and the effect of improving the impact resistance of vinyl chloride resins is extremely reduced. It ends up. For this reason, many so-called weather-resistant reinforcing agents have been proposed that do not reduce their impact resistance improvement effect even when left outdoors. Typical examples include ethylene-vinyl acetate copolymer rubber grafted with vinyl chloride monomers, and cross-linked acrylic acid ester-based rubbers with monomers such as methyl methacrylate, styrene, and acrylonitrile. It is known that the body has been grafted. However, these methods are still unsatisfactory in their effect on improving the impact resistance of vinyl chloride resins. On the other hand, a rubber made of acrylic acid ester-conjugated diolefin copolymer grafted with monomers such as acrylonitrile, styrene, and methyl methacrylate has been proposed. These are excellent in improving the impact resistance of vinyl chloride resins, but in order to develop sufficient impact strength, it is necessary to
When the content of conjugated diolefin is increased,
Although the initial impact resistance improvement effect of vinyl chloride resin is excellent, compared to the case where cross-linked acrylic ester is used as the backbone rubber, it is less likely to be left outdoors due to the residual carbon-carbon double bond caused by the conjugated diolefin. When this happens, the impact resistance decreases significantly. That is, the degree of weather resistance deterioration of a vinyl chloride resin containing a reinforcing agent is mainly controlled by the content of conjugated diolefin contained in the reinforcing agent. On the other hand, however, it is known that since conjugated diolefin has a low glass transition temperature, the higher its content in the backbone rubber polymer, the better the ability to develop strength. The present inventors have arrived at the present invention as a result of intensive research in order to overcome such drawbacks. First, an acrylic acid alkyl ester-conjugated diolefin copolymer is obtained, and this is used as a core, and a conjugated diolefin is further graft-polymerized to obtain a two-layered backbone rubber polymer, methyl methacrylate, styrene, and glass. It consists of one or more monomers of ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate, which produce a polymer with a low transition temperature, and if necessary, it can be graft-polymerized with an acrylonitrile monomer. This graft copolymer can provide high impact strength even if the content of conjugated diolefin is reduced. In other words, when a base rubber polymer consisting of these two layers is used, a reinforcing agent having the same high impact strength improving effect as the base rubber of an alkyl ester-conjugated diolefin copolymer containing a large amount of conjugated diolefin can be obtained; Since the content of conjugated diolefin in the backbone rubber polymer is relatively small, the degree of weather resistance deterioration is low.
They discovered that even when the molded product is left outdoors and used in a very small amount, the improvement effect is excellent in persistence. Based on the discovery of the above facts, we have now obtained a graft polymer that provides an impact-resistant vinyl chloride resin composition with excellent weather resistance that has not been previously available. That is, in the present invention, (1) as the backbone rubber polymer of the graft copolymer, first, a part of the conjugated diolefin and, if necessary, all or part of the polyfunctional crosslinking agent are added to an alkyl group having 2 to 12 carbon atoms. After copolymerizing with acrylic acid alkyl ester containing methyl methacrylate and styrene in the presence of the backbone rubber polymer (A) obtained by polymerizing the remaining conjugated diolefin and the remaining polyfunctional crosslinking agent, methyl methacrylate, styrene, and Graft polymerization of a monomer mixture (B) consisting of one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate and, if necessary, acrylonitrile. The content is a method for producing a graft copolymer characterized by the following. The quantitative relationship of each component composition of the polymer of the present invention, ie, the composition of the two-stage polymerized backbone rubber polymer (A) and the monomer mixture (B) to be graft-polymerized thereto, is preferably within the following range. That is, first, an acrylic acid alkyl ester having an alkyl group having 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms is used.
~95% by weight (more preferably 60-95% by weight) and 5-50% by weight (more preferably 5% by weight) of the conjugated diolefin.
~40% by weight) and their total 100% by weight,
If necessary, after the first stage copolymerization with 0 to 5% by weight (preferably 0 to 3% by weight) of a polyfunctional crosslinking agent, 50 to 95% by weight (preferably 60 to 95% by weight) of this copolymer ), then 5 to 50% by weight (preferably 5 to 40% by weight) of conjugated diolefin as a second stage polymerization,
Based on a total of 100% by weight of these, 50 to 50% of the base rubber polymer (A) is obtained by polymerizing 0 to 5% by weight (preferably 0 to 3% by weight) of a polyfunctional crosslinking agent, if necessary.
methyl methacrylate in the presence of 80 parts by weight
% by weight (preferably 25-95% by weight), styrene 5
~80% by weight (preferably 5-70% by weight) and further 5-50% by weight of one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate. %
It is preferable to graft-polymerize 20 to 50 parts by weight of a monomer mixture (B) consisting of (preferably 5 to 40% by weight) and 0 to 40% by weight acrylonitrile. The present invention will be explained in more detail below. The degree of weather resistance deterioration of a reinforcing agent for vinyl chloride resin containing a conjugated diolefin is controlled by the content of the conjugated diolefin in the reinforcing agent. That is, if the content of the conjugated diolefin component in the backbone rubber polymer is extremely high, the weather resistance will be extremely poor. On the other hand, in order to impart high impact strength, when using a backbone rubber of an acrylic acid alkyl ester-conjugated diolefin copolymer produced by conventional one-stage polymerization, it is sometimes necessary to use an extremely large amount of conjugated diolefin. Therefore, it had poor weather resistance. However, when using a backbone rubber polymer consisting of two layers consisting of the acrylic acid alkyl ester-conjugated diolefin copolymer of the present invention as a core and further graft copolymerized with conjugated diolefin, the content of conjugated diolefin in the backbone rubber polymer can be improved. High impact strength can be achieved by reducing the amount. The first stage and second stage during polymerization of the trunk rubber polymer of the present invention
In both cases, if the amount of conjugated diolefin added is less than 5% by weight, the impact strength reinforcement ability will be poor, and if it exceeds 50% by weight, the weather resistance will deteriorate. A content in the range of 5 to 50% by weight is necessary to obtain excellent 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 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. When it is used in an amount exceeding 5% by weight, the effect of imparting impact resistance is significantly reduced. Examples of the polyfunctional crosslinking agent include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, 1.3
-Butylene glycol diacrylate, 1,4-
Di- or triacrylates of polyhydric alcohols such as butylene glycol diacrylate, 1,6-hexene glycol diacrylate, trimethylolpropane triacrylate; di- or trimethacrylates of polyhydric alcohols corresponding to the above acrylic acid; ethylene glycol diacrylates; Divinyl ether of polyhydric alcohol such as vinyl ether; polyvinyl ester of polybasic acid such as divinylbenzene, divinyl adipate; polybasic acid such as sialyl phthalate, diallyl maleate, diallyl fumarate, diallyl sebacate; di- or triallyl ester , triallyl compounds such as diallyl ether, triallyl cyanurate, triallyl isoanurate, triallylphosphate; polymerizable carboxylic acids such as allyl methacrylate, allyl acrylate, allyl itaconate, monoallyl fumarate, monoallyl maleate, etc. Examples include polyfunctional unsaturated compounds such as allyl esters. Among these polyfunctional crosslinking agents, crosslinking agents containing di- or triacrylates of polyhydric alcohols and allyl groups are particularly preferred. The amount of the trunk rubber polymer is preferably 50 to 80 parts by weight in the graft copolymer. If it 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. Moreover, if it exceeds 80 parts by weight, it will become lumpy during the salting out, 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. Sometimes. The aqueous dispersion of the trunk rubber polymer is preferably obtained by an emulsion polymerization method, and known methods can be used as the emulsion polymerization method. The copolymer of acrylic acid alkyl ester and conjugated diolefin, which is used as the core of the base rubber polymer, can be polymerized by initially charging the entire amount of the monomer together with an emulsifier, an initiator, and other additives. Next, the conjugated diolefin to be graft-polymerized onto these copolymers is added in its entirety at once when the polymerization of the acrylic acid alkyl ester and the conjugated diolefin mixed monomer used as the core of the trunk rubber polymer is substantially completed. Alternatively, the polymerization can be carried out while being added continuously or intermittently. The average primary particle diameter of the trunk rubber polymer latex can be 0.08 to 0.3μ, but
Furthermore, it is also possible to add an aggregating agent to this rubber latex to cause micro-agglomeration, thereby producing agglomerated rubber particles having an average particle diameter of 0.12 to 0.4 .mu.m. As flocculants, hydrochloric acid, sulfuric acid or inorganic salts, organic acids and organic acid anhydrides, which are generally used as latex flocculants,
Furthermore, organic substances with cohesive properties can be used. The graft polymerization in the present invention is usually carried out using 20 to 50 parts by weight of methyl methacrylate, styrene, acrylonitrile, and ethyl acrylate in an aqueous medium containing 50 to 80 parts by weight of the above-mentioned trunk rubber polymer as an emulsion and dispersed. , butyl acrylate, ethyl methacrylate, and butyl methacrylate, and one or more graft monomers selected from the group consisting of butyl acrylate, ethyl methacrylate, and butyl methacrylate are graft-polymerized in one or multiple stages. Ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate, which are copolymerized with methyl methacrylate during graft polymerization, are effective components for obtaining high impact strength.
The amount depends on the type. In other words, if the glass transition temperature (Tg) of the grafted part of the graft copolymer is too low, the tensile strength will drop significantly, and in extreme cases, it will salt out and form lumps during drying, making it difficult to mix uniformly with the vinyl chloride resin. becomes. On the other hand, if the glass transition temperature is too high, it becomes difficult to develop impact strength. That is, it is important that the Tg of the polymer component containing ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate in the graft component polymer is set between 20°C and 95°C. The Tg in the graft component does not necessarily need to be measured, but can be determined by the temperature expressed as the sum of the weight fraction of each monomer in the graft component multiplied by the Tg value of the homopolymer of each monomer. Can be substituted. In addition, in the present invention, "polymer handbook"
(“Polymer Handbook”, Interscience
The values in Table 1 below in the following publication (Publishers, London) were used as the Tg values of the homopolymers of each monomer.

[Table] One or more monomers of these ethyl methacrylate, butyl methacrylate, ethyl acrylate, and butyl acrylate are used as the graft monomer to be copolymerized with methyl methacrylate, and the copolymer thereof is Setting the Tg of 20 to 95°C will result in high impact strength, but it will not prevent a decrease in tensile strength. To compensate for this drawback, after grafting these monomer components, grafting a mixed monomer of styrene and acrylonitrile, which has excellent affinity with vinyl chloride, will reduce the degree of decrease in tensile strength and develop high impact strength. Therefore, the ratio of styrene and acrylonitrile polymerized in the second stage of graft copolymerization is 60 to 90% by weight of styrene, preferably 60 to 80% by weight.
and acrylonitrile is 10 to 40% by weight, preferably 20 to 40% by weight. In addition, this styrene and acrylonitrile are methyl methacrylate, ethyl methacrylate, butyl methacrylate,
It is preferable that a mixed monomer consisting of one or more of ethyl acrylate and butyl acrylate is polymerized in the first stage of graft copolymerization, and then polymerized in the second stage. The graft copolymerization of the present invention is carried out in one or two or more stages of multistage polymerization. When carrying out multistage polymerization of two or more stages, each polymerization stage is started substantially after the previous stage polymerization has been completed. The monomers or monomer mixtures of the graft components in each stage can be added all at once, or can be added continuously or intermittently for polymerization. Graft copolymerization may be carried out using known redox-type initiator systems or thermally decomposed initiators. The graft copolymer 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 copolymer 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, but there are no known mixing methods. mixed in the following manner. In the case of powder mixing, a Henschel mixer, a Banbury mixer, a ribbon blender, etc. are used. The amount of graft copolymer mixed with vinyl chloride resin varies depending on the application, but generally 3% of graft copolymer is mixed with 97 to 70% by weight of vinyl chloride resin.
~30% by weight. As vinyl chloride resin,
Vinyl chloride homopolymer or 70% vinyl chloride by weight
Examples include copolymers containing the above, and mixtures of a dominant amount of vinyl chloride alone or a vinyl chloride copolymer with a minor amount of a chlorinated vinyl chloride polymer having a chlorine content of 63 to 70%. 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 represent parts by weight. Example 1 The following initial ingredients were charged into a pressure vessel and polymerized at 40°C for 8 hours. Initial ingredients Water 150 parts Butyl acrylate 45〃 Butadiene 10〃 Ferrous sulfate (FeSO _{4.7H 2} O) 0.005〃 Ethylenediaminetetraacetic acid disodium salt 0.01〃 Sodium formaldehyde condensed naphthalene sulfonate 0.2〃 Sodium olefinate 3.0 〃 Cumene hydroperoxide 0.05〃 Sodium formaldehyde sulfoxylate
0.05 The polymerization conversion rate of the obtained polymer latex was 98%
It was hot. In addition, butadiene 5 parts cumene hydroperoxide 0.03 Sodium formaldehyde sulfoxylate
0.03〃 was added and polymerization was carried out at 40°C for an additional 5 hours. The average particle size of the obtained rubber latex was 0.1μ
The polymerization conversion rate was 99%. Add 0.3% hydrochloric acid aqueous solution 40% to the obtained base rubber polymer latex.
After agglomeration was carried out by gradually adding 50% of the mixture, a 2% aqueous sodium hydroxide solution was added to stabilize the mixture. The rubber latex was agglomerated and enlarged to an average particle size of 0.15μ. To this, add 60% of the graft polymerization additive components shown below.
Polymerization was carried out at ℃ for 6 hours. Polymerization conversion rate is 98%
It was hot. Graft polymerization additive component Methyl methacrylate 20 parts Styrene 10〃 Butyl methacrylate 10〃 Cumene hydroperoxide 0.2〃 Sodium formaldehyde sulfoxylate
0.2〃 Ethylenediamine tetraacetic acid disodium salt 0.01〃 Ferrous sulfate 0.005〃 The obtained polymer latex was salted out and dehydrated and dried to obtain the intended graft copolymer. Example 2 In the synthesis of the backbone rubber polymer, instead of the initial charge of butyl acrylate of 45 parts in Example 1,
50 parts, and the amount of butadiene initially charged as well.
The desired graft copolymer was obtained in exactly the same manner as in Example 1 except that the amount was changed from 10 parts to 5 parts. Example 3 To the trunk rubber polymer latex obtained in the same manner as in Example 1, the following first and second stage graft polymerization addition components were added in two stages and polymerized. First-stage graft polymerization additive component Methyl methacrylate 20 parts Butyl methacrylate 4 Cumene hydroperoxide 0.1 Sodium formaldehyde sulfoxylate
0.2〃 Ethylenediaminetetraacetic acid disodium salt 0.01〃 Ferrous sulfate 0.005〃 Second stage graft polymerization additive component Styrene 12 parts Acrylonitrile 4〃 Cumene hydroperoxide 0.1〃 The first stage was polymerized for 3 hours. The polymerization conversion rate was 98%. Thereafter, the second stage was similarly polymerized for 3 hours. The final conversion rate was 97%.
Thereafter, the desired graft copolymer was obtained in the same manner as in Example 1. Comparative Example 1 Same as Example 1 except that 5 parts of butadiene which was added in the synthesis of the backbone rubber polymer of Example 1 was initially charged as 15 parts of butadiene as the initial charge.
A trunk rubber polymer was synthesized in the same manner as in Example 1, and graft copolymerization was performed in exactly the same manner as in Example 1 to obtain a graft copolymer. Comparative Example 2 Example 2 except that 5 parts of butadiene, which is additionally added during the synthesis of the backbone rubber polymer of Example 2, was initially charged as 10 parts of butadiene as the initial charge.
Make a latex of stem rubber polymer in the same manner as
Graft copolymerization was performed in the same manner as in Example 2 to obtain a graft copolymer. Comparative Example 3 A backbone rubber polymer was produced in the same manner as in Example 3, except that 5 parts of butadiene, which was added during the synthesis of the backbone rubber polymer in Example 3, was initially charged as 15 parts of butadiene. A latex was prepared, and graft copolymerization was performed in the same manner as in Example 3 to obtain a graft copolymer. The graft copolymers obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were mixed according to the following formulation-1.
Polyvinyl chloride resin (Kanevinyl)
S1001 (manufactured by Kanebuchi Kagaku Kogyo Co., Ltd.) and stabilizers, etc. to form 1-inch diameter hard PVC pipe.
This was carried out using an 80 mmφ twin screw extruder in different directions. Compounding recipe-1 Polyvinyl chloride resin 100 parts Graft copolymer 7. Lead-based stabilizer 2. Calcium stearate 1. Wax-based lubricant 0.5. Characteristics of each molded product were measured and tabled as pipe physical properties.
Shown in 2.

[Table] Also, according to the following formulation recipe-2, 8 parts each of the graft copolymers obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were blended with 100 parts of polyvinyl chloride resin (Kanevinyl S1001). Blend and heat at 180℃ for 8 minutes
After heating and kneading with a roll, press molding was performed at 200° C. for 15 minutes to create a sheet-like molded product. Compounding recipe-2 Polyvinyl chloride resin 100 parts Graft copolymer 8〃 Tribasic lead sulfate 5〃 Dibasic lead stearate 1〃 Lead stearate 0.25〃 Calcium stearate 0.25〃 Impact strength from the obtained sheet-shaped molded product A test sample was prepared and subjected to an Izod impact strength measurement test at 23°C in accordance with JIS-K7110, and the results are shown in Table 3.

【table】

[Table] Next, in order to evaluate the durability of the impact resistance improvement effect of vinyl chloride resin in the outdoors, Example 1
The graft copolymers obtained in ~3 and Comparative Examples 1 to 3 were blended with polyvinyl chloride resin (Kanevinyl S1001), stabilizers, etc. according to the following formulation -3, and heated and kneaded using the same rolls and press molded. A test sample was prepared using the following method. Compounding recipe-3 Polyvinyl chloride resin 100 parts Graft copolymer 18〃 Tribasic lead sulfate 5〃 Dibasic lead stearate 1〃 Lead stearate 0.25〃 Calcium stearate 0.25〃 Wetherometer of the prepared test sample ( An artificially accelerated exposure test was conducted using Toyo Rika's WE SUN-HC model), and the impact strength of each sample was measured after 300 and 600 hours of exposure using Izotsu impact strength measurement in accordance with JIS-K7100. A comparison with the results is shown in Table 4.

【table】

Claims (1)

[Scope of Claims] 1. As the backbone rubber polymer of the graft copolymer, first, a part of the conjugated diolefin and, if necessary, all or part of the polyfunctional crosslinking agent are combined into an alkyl group having 2 to 12 carbon atoms.
After copolymerizing with acrylic acid alkyl ester having , a monomer mixture (B) consisting of styrene, one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate, and, if necessary, acrylonitrile. A method for producing a graft copolymer, which comprises graft polymerizing. 2. The composition of the backbone rubber polymer (A) is, first, 50 to 95% by weight of an acrylic acid alkyl ester and 5 to 50% by weight of a conjugated diolefin, based on a total of 100% by weight of these,
If necessary, after the first stage copolymerization with 0 to 5% by weight of a polyfunctional crosslinking agent, 50 to 95% by weight of this copolymer,
Conjugated diolefin 5-50% by weight as second stage polymerization
This is a polymer composition obtained by polymerizing 0 to 5% by weight of a polyfunctional crosslinking agent, if necessary, based on the total 100% by weight of these, and the monomer mixture (B) to be graft-polymerized to this. The composition is methyl methacrylate 5
-95% by weight, 5-80% by weight of styrene, 5-50% by weight of one or more monomers selected from the group consisting of acrylic esters and methacrylic esters, and 0-40% by weight of acrylonitrile. The graft copolymer according to claim 1, which is a mixture of monomers and has a composition of 50 to 80 parts by weight of the base rubber polymer (A) and 20 to 50 parts by weight of the monomer mixture (B). Method of manufacturing coalescence. 3 Monomer mixture (B) is methyl methacrylate 40~
90% by weight, 5 to 50% by weight of styrene, and one or two selected from ethyl methacrylate, butyl methacrylate, ethyl acrylate, and butyl acrylate.
A mixture consisting of 5 to 50% by weight of one or more monomers, and the glass transition temperature of the polymer is 20 to 95°C
The method for producing a graft copolymer according to claim 1 or 2, wherein 20 to 50 parts by weight of the copolymer is graft-polymerized. 4 In the presence of 50 to 80 parts by weight of the backbone rubber polymer, 50 to 95% by weight of methyl methacrylate and one or more selected from the group consisting of ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate. Consists of 5 to 50% by weight of two or more types of monomers, and the glass transition temperature of the polymer is 20 to 95°C
First, 10 to 40 parts by weight of mixed monomers set to
The method for producing a graft copolymer according to claim 1 or 2, wherein 10 to 40 parts by weight of the copolymer is graft-polymerized.