JPS6132324B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing block copolymers modified with maleic acid compounds. More specifically, the present invention relates to a new method for producing thermoplastic rubber having excellent melt flow properties, tensile strength properties, etc., by modifying a block copolymer consisting of a conjugated diene compound and a vinyl aromatic compound with a maleic acid compound. . Conventionally, many attempts have been made to modify resins or rubbers with highly functional maleic acid compounds to improve adhesion, green strength, and the like. Regarding conjugated diene synthetic rubber, various methods have been proposed for modifying it with maleic acid compounds (maleization). For example, JP-A-49-20294 describes a method for maleating polyisoprene in an inert solvent in the presence of a radical initiator. A drawback of this method is that post-processing steps such as solvent removal are complicated. Furthermore, Japanese Patent Publication No. 45-32707 describes a method in which mastication and maleation of polyisoprene are carried out sequentially in a screw type extruder in the absence of a radical initiator. This method has a simpler process and can be said to be a better method than the maleation in an inert solvent. However, this method cannot be applied to the maleation of block copolymers as in the present invention. This is because, in the case of a block copolymer in which the conjugated diene portion is mainly composed of butadiene, mastication causes a crosslinking phenomenon, that is, gelation, of the butadiene portion. Furthermore, in the case of a block copolymer in which the conjugated diene moiety is mainly composed of isoprene, mastication causes molecular chain scission in the isoprene moiety, resulting in loss of structural characteristics as a block copolymer. In addition, JP-A-1987
No. 56427 suggests a method of maleating a block copolymer of butadiene and styrene in the coexistence of a rubber developing oil by generating radicals using a radical initiator or heating. Also,
JP-A-52-123443 also suggests a method of maleating a block copolymer consisting of butadiene and styrene together with polyethylene in a screw type extruder in the presence of a radical initiator.
However, in both of these methods, maleation occurs under the generation of radicals, so it is difficult to avoid gelation of the resulting modified block copolymer. The modified block copolymer results in a significant deterioration in properties as a thermoplastic rubber, such as melt flow characteristics and appearance characteristics. As described above, it can be said that an industrially satisfactory method for modifying a block copolymer composed of a conjugated diene compound and a vinyl aromatic compound with a maleic acid compound has not yet been found. Under these circumstances, the present inventor has conducted extensive research to solve the above problems, and as a result has arrived at the present invention. That is, the present invention contains at least one polymer block mainly composed of a conjugated diene compound and at least one polymer block mainly composed of a vinyl aromatic compound, and the weight ratio of the conjugated diene compound and the vinyl aromatic compound is At least one block copolymer consisting of 30/70 to 95/5 and at least one maleic acid compound are supplied to a screw type extruder, and generation of radicals can be substantially suppressed in the absence of a radical initiator. The above block copolymer and the above maleic acid compound are reacted under the conditions of reaction temperature, reaction time and shear rate, and the ratio of the melt viscosity index of the modified block copolymer obtained at that time and the block copolymer before modification. The present invention relates to a method for producing a modified block copolymer, characterized in that the The feature of the present invention is that it not only provides an industrial production method for obtaining a modified block copolymer with a high maleation reaction rate without causing product deterioration such as gelation, but also
A new modified block that exhibits excellent properties as a thermoplastic rubber, with significantly improved appearance properties such as color tone and surface texture, mechanical properties such as melt flow properties and tensile strength, and adhesive properties with metals, glass, wood, etc. The present invention provides a copolymer. The present invention will be described in more detail below. The block copolymer used in the present invention has at least one polymer block mainly composed of a conjugated diene compound, at least one polymer block mainly composed of a vinyl aromatic compound, and preferably two polymer blocks mainly composed of a vinyl aromatic compound.
Must contain at least 100%. In the block polymer of the present invention, the weight ratio of the conjugated diene compound to the vinyl aromatic compound is limited to a composition range of 30/70 to 95/5, preferably 50/50 to 90/10. Furthermore, in the block copolymer of the present invention,
The polymer block mainly composed of a conjugated diene compound is limited to a composition in which the weight ratio of the conjugated diene compound to the vinyl aromatic compound is from 100/0 to 60/40. In this case, the distribution of vinyl aromatic compounds is
It may be random or tapered (monomer components increase or decrease along the molecular chain), partially block-like, or a combination thereof. Furthermore, in the block copolymer of the present invention, the polymer block mainly composed of a vinyl aromatic compound is limited to a composition in which the weight ratio of the vinyl aromatic compound to the conjugated diene compound is within a range of 100/0 to 70/30. Ru. In this case, the distribution of the conjugated diene compound may be random, tapered, partially block-like, or a combination thereof. When there are two or more polymer blocks mainly composed of vinyl aromatic compounds, or when there are two or more polymer blocks mainly composed of conjugated diene compounds, each polymer block may have the same structure. However, different structures are also possible. In the above block copolymer, the weight ratio of the polymer block mainly consisting of a vinyl aromatic compound to the polymer block mainly consisting of a conjugated diene compound is 5/95 to 95/5, preferably 10/90 to 90. /Ten
is within the range of The above range limitation regarding the block copolymer of the present invention is based on the fact that the block copolymer of the present invention or the modified block copolymer obtained by maleation reaction has properties as a thermoplastic rubber, such as good melt flow properties. This is an essential condition for exhibiting properties such as tensile strength. As the conjugated diene compound constituting the block copolymer of the present invention, one or more of butadiene, isoprene, piperylene, 1,3-pentadiene, etc. is selected. In addition, as vinyl aromatic compounds,
One or more types of styrene, α-methylstyrene, vinyltoluene, etc. are selected, and styrene is preferable. The block copolymer of the present invention includes styrene-
Particularly preferred are butadiene block copolymers. The block copolymer used in the present invention has a number average molecular weight of 10,000 to 1,000,000, preferably 20,000.
The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably within the range of 1.01 to 10. Further, the molecular structure of the block copolymer used in the present invention may be linear, branched or radial. The rubber may be slightly modified with an organic compound or an inorganic compound as long as the properties of the thermoplastic rubber are not lost. Furthermore, in the block copolymer used in the present invention, when butadiene is used as the conjugated diene compound, the microstructure of the butadiene moiety has a cis-1,4 content of 20 to 50% and a 1.2 content of 5 to 40%. % is preferred. The above-mentioned block copolymer used in the present invention is usually prepared by using an organic lithium compound such as butyllithium as a catalyst in an inert hydrocarbon solvent such as benzene, toluene, hexane, or cyclohexane.
It is obtained by block copolymerizing a conjugated diene compound and a vinyl aromatic compound. It is also possible to make branched or radial block copolymers by reacting a block copolymer with a lithium active end with a polyfunctional coupling agent such as carbon tetrachloride or silicon tetrachloride. be.
In the present invention, block copolymers obtained by any polymerization method can be used within the range of the above limitations. The above-mentioned block copolymers may be not only one type but also a combination of two or more types. Examples of these combinations include a styrene-butadiene block copolymer and a styrene-isoprene block copolymer. combination, a combination of two types of styrene-butadiene block copolymers with different molecular weights, a combination of two types of styrene-butadiene block copolymers with different styrene contents, a combination of three blocks of styrene-butadiene-styrene; Examples include combinations of styrene-butadiene block copolymers with different block structures, such as one consisting of four blocks: butadiene-styrene-butadiene-styrene. On the other hand, the maleic acid compound used in the present invention includes maleic acid, maleic anhydride, half-alkyl ester of maleic acid, maleic acid amide,
It is selected from maleic acid imide and the like, and among these, maleic anhydride is preferred. Furthermore, in the present invention, the block copolymer and the maleic acid compound may be fed to the screw extruder either separately or simultaneously, but in order to obtain a homogeneous modified block copolymer, they must be mixed in advance and fed. It is preferable to do so. On this occasion,
It is also possible to feed inorganic or organic compounds to the screw extruder as required along with the block copolymer and maleic acid compound. These include so-called additives such as stabilizers (antioxidants), tackifiers, plasticizers, fillers, lubricants, flame retardants, and colorants, as well as thermoplastics, thermoplastic elastomers, and unmodified additives. It is selected from high molecular compounds such as sulfur rubber or low polymers thereof. Thermoplastics include polystyrene, high-impact polystyrene, AS resin,
Styrene polymers such as ABS resin, polyolefin polymers such as polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-acrylic acid copolymer, polyvinyl chloride polymer , polyvinyl acetate polymer, polyamide polymer, thermoplastic polyester polymer, polyacrylate polymer, polyphenylene ether polymer, polyphenylene sulfide polymer, polyacetal polymer, polybutadiene polymer Examples include polymers, thermoplastic polyurethane polymers, and the like. Examples of thermoplastic elastomers include styrene-butadiene block copolymers, polyurethane thermoplastic elastomers, polyester thermoplastic elastomers, polyolefin thermoplastic elastomers, and unvulcanized rubbers include polybutadiene, polyisoprene, etc. , styrene-butadiene copolymer, butadiene-acrylonitrile copolymer,
Examples include ethylene-propylene copolymer, ethylene-propylene-diene copolymer, silicone rubber, epichlorohydrin rubber, acrylic rubber, and ethylene-vinyl acetate copolymer. Other materials that can be supplied to the extruder include mono- to trivalent metal compounds that can form ionic bonds with maleic acid compounds, and vinyl monomers that do not cause gelation. The operating conditions for the screw type extruder in the present invention include the temperature below the melt zone of the extruder.
150-280℃, preferably 180-250℃, more preferably 180-220℃, average residence time (reaction time) in the extruder 30-500 seconds, preferably 60-300 seconds, shear rate in the extruder 180 seconds ^{- 1} or less, preferably
It is selected from the range of 120 sec ^-1 or _less , more preferably 60 sec ^-1 or less, and these conditions must be such that the generation of radicals in the extruder can be substantially suppressed. If the extruder temperature is 150℃ or lower or the residence time is 30 seconds or less, the addition rate of the maleic acid compound is low; conversely, if the extruder temperature is 280℃ or higher, the residence time is 500 seconds or more, or the shear rate is
A temperature of 180 sec ^-1 or more is undesirable because gelation of the block copolymer occurs. In addition, the said shear rate is the value calculated by the method shown in SPE Journal June (1967) P53. In particular, in the present invention, in order to avoid gelation during the maleation reaction of the block copolymer, a radical initiator such as peroxide or an azo compound such as azobis-iso-butyronitrile is added to the reaction system. is undesirable and should be avoided. On the other hand, in the present invention, in order to suppress radicals generated during the reaction under heating or high shear,
It is preferable to add a phenol-based, phosphorus-based, amine-based, or other gelation inhibitor. These additives are effective even when used alone, but it is preferable to combine two components, and more preferably to combine three components, especially phenol-based gelation inhibitors, phosphorus-based gelation inhibitors, and others. It is particularly preferred to combine three components consisting of one component of the gelation inhibitor. Examples of the above phenolic gelation inhibitor include 2,6-di-tert-butyl-4-methylphenol, 2,2'-methylenebis-(4-methyl-
6-tert-butylphenol), 4,4-butylidenebis-(3-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-
tert-butylphenol), n-octadecyl-
Examples include β-(4′-hydroxy-3′·5′-di-tert-butylphenyl)propionate. Examples of the phosphorus-based gelation inhibitor include tri(nonylphenyl) phosphite, tridecyl phosphite, distearyl pentaerythrityl diphosphite, and the like. Other anti-gelling agents include 1,2-dihydroxynaphthalene, 1-
Naphthol gelation inhibitors such as amino-2-naphthol and 1-nitro-2-naphthol, trimethylamine, phenyl-β-naphthylamine, P-
phenylenediamine, mercaptoethylamine,
Amine gelation inhibitors such as N-nitroso-dimethylamine, phenothiazine, 1,2-dihydro-2,2,4-trimethylquinoline, dilaurylthiodipropionate, dilaurylsulfide, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, metal salts of 2-mercaptobenzothiazole, sulfur-based gelation inhibitors such as diethylxanthogen sulfide, quinone-based gelation inhibitors such as hydroquinone, urea-based gelation inhibitors There are inhibitors, and other compounds can also be used if they have the same effect. These are 0.001 for block copolymers.
~5 parts by weight, preferably 0.05 to 2 parts by weight. However, it is not preferable to use a compound that reacts with the maleic acid compound to cause gelation. The block copolymer modified with a maleic acid compound obtained according to the present invention has a maleic acid compound added in an amount of 0.05 to 20% by weight, preferably 0.1 to 10% by weight. The melt viscosity index of the modified block copolymer is
The ratio must be between 0.025 and 2.0.
If it is less than 0.025, the melt flow characteristics will deteriorate, and if it is more than 2.0, the properties as a thermoplastic rubber will be impaired. A more preferable range of this melt viscosity index ratio is 0.025 to 1.0 when the weight ratio of butadiene and isoprene constituting the conjugated diene is 70/30 to 100/0;
The weight ratio of butadiene and isoprene is 0/100 ~
In the case of 70/30, it is 1.0 to 2.0. The toluene insoluble content of the modified block copolymer obtained in the present invention is 1% or less, preferably 0.5% or less. However, if the above-mentioned modified block copolymer is reversibly crosslinked with a metal salt or acid anhydride, after decomposing the reversible crosslinking by acid treatment, etc.
The above-mentioned melt viscosity index or toluene insoluble content shall be measured. The modified block copolymer obtained in the present invention may be mixed with other thermoplastic resins, various unvulcanized rubbers, high molecular compounds such as thermoplastic elastomers, or low molecular weight polymers thereof, as necessary. Alternatively, it is possible to add polymerizable monomers, thermosetting resin intermediates, and the like. Examples of the thermoplastic resin include styrene polymers such as polystyrene, impact-resistant polystyrene, AS resin, and ABS resin, polyolefin copolymers such as polyethylene, polypropylene, polybutene, and ethylene-propylene copolymers, and polyvinyl chloride polymers. Copolymers, polyvinyl acetate polymers, polyamide polymers, thermoplastic polyester polymers, polyacrylate polymers, polyphenylene ether polymers, polyphenylene sulfide polymers, polyacetal polymers , polybutadiene polymers, thermoplastic polyurethane polymers, etc. As thermoplastic elastomers, styrene-based polymers, etc.
Examples include butadiene block copolymer, polyurethane thermoplastic elastomer, polyester thermoplastic elastomer, polyolefin thermoplastic elastomer, etc. Unvulcanized rubber includes polybutadiene, polyisoprene, styrene-butadiene copolymer, butadiene-acrylonitrile. Copolymer ethylene-propylene copolymer, ethylene-
Examples include propylene-diene copolymer, silicone rubber, epichlorohydrin rubber, acrylic rubber, ethylene-vinyl acetate copolymer, and the like. Examples of thermoplastic resin intermediates include phenolic resin, urea resin, melamine resin, unsaturated polyester resin, thermosetting polyurethane resin,
Examples include intermediates such as epoxy resin and silicone resin. Furthermore, examples of polymerizable monomers include vinyl aromatic compounds such as styrene, cyanovinyl compounds such as acrylonitrile, unsaturated carboxylic acid esters such as methyl methacrylate, unsaturated carboxylic acids such as acrylic acid, etc. Examples include compounds having amino groups, hydroxyl groups, isocyanate groups, epoxy groups, etc. that can react with the functional groups of the block copolymer, such as ammonia, dimethylamine, and methyl alcohol. Further, other additives such as stabilizers, tackifiers, plasticizers, fillers, lubricants, flame retardants, colorants, crosslinking agents, etc. can also be added. Among these additives, crosslinking agents include polyfunctional reagents such as sulfur, peroxides, and diamines;
Although metal compounds of groups 1 to 10 of the periodic table can be used, crosslinking with a metal compound is preferable in order for the modified block copolymer of the present invention to maintain its properties as a thermoplastic rubber. The modified block copolymer obtained by the present invention can be used in various molded products, shoe soles, metals such as aluminum, iron, glass, cellophane, etc., plastics, etc.
Examples include adhesives for paper and inorganic materials, laminates of the above resins or rubbers such as polyolefin, polystyrene, polyamide and polyvinyl chloride, paints as emulsions or powders, blends with asphalt, and various surface treatment agents. Hereinafter, some Examples will be shown, but these are intended to explain the present invention in more detail, and are not intended to limit the scope of the present invention. Example 1 Under a nitrogen atmosphere, in a cyclohexane solvent, using buterithium as a polymerization catalyst, monomers were sequentially added in the order of styrene, butadiene, and styrene.
By polymerizing at a temperature of 80℃, styrene/
Composition ratio of butadiene/styrene 15/70/15
An SBS3 type block copolymer was obtained. This polymer 100
After adding 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol as an antioxidant to the polymer solution, the solvent was distilled off. The melt viscosity index of this block copolymer (measured at 200° C. under a load of 5 kg, unit: g/10 min) was 11.8. To the pellets of this block copolymer were added 2 parts by weight of maleic anhydride and 0.3 parts by weight of a phenothiazine stabilizer per 100 parts by weight of the block copolymer, and these were mixed uniformly using a Henschel mixer. After that, use a screw type extruder (single screw, screw diameter 20 mmφ, L/D = 22) under a nitrogen atmosphere.
was supplied to perform the maleation reaction. The maleation conditions are shown below. Extruder screw rotation speed: 30 rpm Extruder temperature: Cylinder C ₁ : (12D from the screw tip) 220 ℃ Cylinder C ₂ : (5D from the screw tip) 200 ℃ Die 200 ℃ Polymer retention in the cylinder Time 180 sec Shear rate 20 sec ^-1 The obtained maleated modified block copolymer had a melt viscosity index of 6.7 and a toluene insoluble content of 0.1% or less, and the polymer was titrated with sodium methylate. When the acid content was measured,
The amount of maleic anhydride added to the polymer is 1.06
% by weight, and from this the reaction rate of maleic anhydride is 53%. The block copolymer extruded with an extruder has a 120
Unreacted maleic anhydride was removed by drying under reduced pressure at °C for 1 hour. Unreacted maleic anhydride remaining in the block copolymer after drying under reduced pressure was extracted with acetone and reduced to 0.05% by weight of the polymer.
It was below. Examples 2 to 5, Comparative Examples 1 to 6 Various block copolymers were maleated in the same manner as in Example 1. The reaction conditions and results are shown in Table 1 as Examples 2 to 5. Furthermore, a modified block copolymer was obtained using the screw type extruder used in Example 1 under conditions outside the scope of the present invention. These reaction conditions and results are shown in Table 2 as Comparative Examples 1 to 6. As is clear from the results in Tables 1 and 2, Examples 1 to 5 were obtained under the reaction conditions limited by the present invention.
The modified block copolymer of Comparative Example 1, which was obtained under conditions outside the scope of the present invention, had extremely low toluene insoluble content and a good melt viscosity index.
The modified block copolymers No. 6 to 6 all contained a large amount of toluene insoluble matter and had poor flow characteristics. Furthermore, the modified block copolymer obtained from the styrene-isoprene-styrene block copolymer of Comparative Example 6 has an increased melt viscosity index due to isoprene chain scission. Table 3 shows various physical property values of the modified block copolymers obtained in Examples 3 and 4, the modified block copolymers obtained in Comparative Examples 2 and 6, and these block copolymers before modification. Ta. From the results in Table 3, it is clear that the modified block copolymer obtained by the method of the present invention has good melting properties and tensile strength compared to the unmodified block copolymer.
It has improved modulus by 300% and has excellent adhesion to aluminum. In addition, modified block copolymers obtained by methods outside the scope of the present invention are
The appearance characteristics and melting characteristics are poor, and there is little improvement in tensile strength, etc. Further, in the case of Example 4 obtained from a styrene-isoprene-styrene block copolymer, a slight decrease in tensile strength was observed, and in Comparative Example 6, the tensile strength decreased significantly due to molecular chain scission.

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Claims (1)

[Scope of Claims] 1. Contains at least one polymer block mainly composed of a conjugated diene compound and at least one polymer block mainly composed of a vinyl aromatic compound, and the weight ratio of the conjugated diene compound and the vinyl aromatic compound is at least one block copolymer having a ratio of 30/70 to 95/5 and at least one maleic acid compound
The seeds are fed into a screw type extruder, in the absence of a radical initiator, the temperature after the melt zone of the extruder is 150-280℃, and the average residence time of the extruder is 30-280℃.
for 100 parts by weight of block copolymer in 500 seconds.
Reacting the block copolymer and the maleic acid compound in the presence of 0.001 to 5 parts by weight of a stabilizer,
The ratio of the melt viscosity index of the modified block copolymer obtained at that time and the block copolymer before modification is
A method for producing a modified block copolymer, characterized in that the copolymer has a block copolymer of 0.025 to 2.0. 2. The method according to claim 1, wherein the toluene insoluble content in the modified block copolymer is 1% by weight or less.