JPH0413367B2 - - Google Patents

Description

[Detailed description of the invention]

Transparent polymers containing high-impact styrene are highly desirable in many applications, particularly in the field of packaging, and are suitable for applications such as pails, cup lids, blister packs, and the like. Polystyrene is too brittle for many applications, and high-impact polystyrene is not transparent enough for many packaging applications. Impact-resistant transparent resins have been made by a variety of methods by anionic polymerization using utyllithium as an initiator. Another technique is to use methyl methacrylate in a styrene polymer to produce impact resistant resins in which the rubber regions do not significantly impede light transmission. The present invention provides an improved transparent impact resistant resin composition containing styrene monomer and conjugated diene monomer as monomer materials in a polymerized state without anionic polymerization and associated purity problems. It is something to do. The present invention also provides an improved method for producing the resin composition. Various advantages of the present invention include moldable polymers in which the majority of the diene region is small in diameter.
This is achieved in a free-radically polymerized, transparent, impact-resistant alkenyl aromatic resin that has a rod-like or spherical shape of less than 70 nanometers and is characterized by the absence of occlusion of polymerized alkenyl aromatic monomers. The resin composition of the present invention is preferably AB or
AB (BA) n configuration (A represents a block of polymerized alkenyl aromatic monomer, B represents a block of polymerized conjugated diene monomer, n is 1 to 5
is made by polymerizing alkenyl aromatic monomers in the presence of a block copolymer (integer of ). Also within the scope of this invention is a method of making a transparent alkenyl aromatic resin composition comprising: That is,
AB or AB(BA) having n configuration (A represents a block of polymerized alkenyl aromatic monomer, B represents a block of polymerized conjugated diene monomer, n is an integer from 1 to 5) A method for producing a transparent alkenyl aromatic resin composition comprising free radical polymerization of at least one alkenyl aromatic monomer in which a block copolymer is dissolved, the block copolymer having a weight average molecular weight of at least 40,000; The block copolymer includes 30-70% by weight polymerized alkenyl aromatic monomer and 70-30% by weight polymerized conjugated diene such that the diene polymer regions in the composition are 70 nanometers in diameter. This method is characterized in that it has a rod shape and a spherical shape less than a meter in size, and no occlusion of polymerized alkenyl monomers is observed. When using polybutadiene block copolymer, the molecular weight of the block copolymer is 40,000 to 150,000.
is advantageous. The resulting resin composition usually has a
~85% by weight alkenyl aromatic units in polymerized state and
15 to 30% by weight of conjugated diene units in a polymerized state. The alkenyl aromatic monomer has the following general formula: (In the formula, Ar represents an aromatic hydrocarbon group or a benzene series aromatic halohydrocarbon group, and R
is hydrogen or a methyl group). Examples of such alkenyl aromatic monomers are styrene, ortho-methylstyrene,
Meta-methylstyrene, para-methylstyrene,
These include ar-ethylstyrene, ar-vinylxylene, and mixtures thereof. Block copolymers suitable for carrying out the present invention are:
Alkenyl aromatic monomer and AB or AB(BA)n
Configuration (A represents a block of polymerized alkenyl aromatic monomer, B represents a block of polymerized conjugated diene monomer, such as polybutadiene, polyisoprene, copolymer of butadiene and isoprene, etc., n is an integer from 1 to 5)
It is a block copolymer with a diene. Preferably n is 1. The proportion of alkenyl aromatic monomer is 30-70% by weight, and the proportion of diene is 70-30%
Weight%. Furthermore, if the block copolymer is limited, the weight average molecular weight measured by gel permeation chromatography is 40,000 or more, which is below the molecular weight at which the desired morphology cannot be obtained. Copolymers of butadiene and isoprene are also useful as B blocks. It is believed that the polymers according to the invention are mixtures of many different components. Advantageously, the matrix is primarily a polyalkenyl aromatic monomer having a weight average molecular weight of 75,000 to 350,000 as determined by gel permeation chromatography.
When an alkenyl aromatic monomer is grafted onto a block copolymer, it is assumed that some degree of graft copolymer is present. The free initiator is a known one, for example, 4-(t
-butyl)-1,1-bis(t-butylperoxy)cyclohexane, benzoyl peroxide, or lauroyl peroxide. The amount of initiator used ranges from 0.025 to 0.2% by weight, based on the combined weight of monomer plus block copolymer. When the diene is polybutadiene, it is often and especially desirable to use a chain transfer agent to maintain the molecular weight of the polymer within the desired range. Suitable chain transfer agents include organic thiols such as aliphatic mercaptans, typically dodecyl mercaptan, halogenated hydrocarbons such as carbon tetrachloride, alpha-methylstyrene dimers, and the like. When adding the chain transfer agent,
Concentrations of from 0.001 to 0.5% by weight, based on the combined weight of monomer plus block copolymer, are usually used. Similarly, if the diene is polybutadiene, an antioxidant is added at or near the end of the polymerization to prevent cross-linking between the diene polymer blocks. Such antioxidants are well known to those skilled in the art and include bound phenols such as 2,6-di-
Examples include combinations of (tertiary butyl)-4-methylphenol, bound phenol, alkylated allyl phosphite, and the like. The polymers of the present invention are produced by mass, solution, or suspension polymerization, usually in the temperature range of 105 to 175°C. If necessary, inert agents may be added prior to polymerization to reduce the viscosity of the reaction mixture. Typical solvents include benzene, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane, and the like. Upon completion of the polymerization process,
The solvent and residual monomer are typically removed from the polymer by subjecting the molten polymer to a reduced pressure, eg, from about 0.1 to about 100 mm Hg, to remove the solvent and residual monomer from the polymer. The polymer composition thus obtained may be directly thermally processed into a desired shape such as a sheet or film, or it may be extruded as a strand and the strand may be cooled and then cut into pellets. The invention is further illustrated by the following examples. In the examples, parts and percentages are by weight unless otherwise specified. Example 1 121 g of ethylbenzene was placed in a pressure vessel equipped with a stirrer along with 115 g of styrene-butadiene block copolymer dissolved in 334 g of styrene. The block copolymer had a weight average molecular weight of 90,000 gmol as determined by gel permeation chromatography and contained 45% by weight styrene and 55% by weight butadiene. Alphamethylstyrene 1 1/10 g was used as a chain transfer agent, and at the same time 1.7 g of mineral oil was used as a lubricant, and 4-(tert-butyl)-1,1-bis-(tert-butylperoxy)cyclohexane was used as a free initiator. 0.24g was used. The reaction mixture thus obtained was heated to 105° C. and stirred with a stirrer rotating at about 30 revolutions per minute.
The temperature of the reaction mixture was increased from 105°C over 5 1/2 hours.
The temperature was raised to 155℃. At this time, 2.8 g of 2,6-di-(tert-butyl)-4-methylphenol and 1.8 g of trisnonylphenyl phosphite were added as antioxidants. After the antioxidant is dispersed into the reaction mixture, put the reaction mixture into a tray and vacuum up to 20mm.
Ethylbenzene and unreacted styrene were removed by heating at 175° C. for 1.5 hours under Hg pressure. The resulting polymer product contained approximately 19% by weight of polymerized butadiene units. The polymer thus obtained was pulverized and compressed test bars were made from it. The test results were as follows: Notched Izod Impact 0.38 ft-lbs/in. Notched (2.02
Kg/cm); Tensile breaking strength 3375lbs/in ²
(23270KPa); Tensile modulus 248000lbs/in ²
(17.0991×10 ³ KPa); Vikatsu heating strain temperature
97.2℃; Melt flow rate using condition G
1.71g. A 10 mil (0.254 mm) thick plate was molded from the polymer and the absorbance was measured using a Beckman Model B spectrophotometer. A wavelength of 640 nanometers was used and the film was placed approximately 9 cm from the center of the photocell photodetector. The absorbance was 0.07. Electron micrographs of cross-sections of the molded samples revealed polybutadiene regions that had the shape of rods or spheres with a diameter of about 35 nanometers and no polystyrene occlusion was observed. Example 2 Various types of styrene were prepared in the same manner as in Example 1.
A number of polymerizations were carried out using butadiene block copolymers. The results are shown in Table 1. In the table, product composition S/B indicates the weight ratio of styrene to butadiene units in the final product. The weight ratio of styrene to butadiene in the block copolymer is listed under the elastomer S/B composition section, w
is the weight average molecular weight of the elastomer in grams moles; n. Izot impact is notched Izot impact; HD is heating strain in °C; nm is nanometers; MFR.Sch.G.
is the melt flow velocity of Addendum G.
rate).

[Table] All polymerizations were performed using 500 ppm (based on styrene with elastomer) of 4-(t-butyl)-1,
This was done using 1-bis(t-butylperoxy)cyclohexane. Ethylbenzene diluent was used in all polymerizations at a level of 15-22% of the total feed solution. 0.2-0.4% alpha-methylstyrene duplex CT agent and 0.3% mineral oil were included in the feed solution. All polymer products are 1% 2-6
-di-t-butyl-4-methylphenol and 0.5
% trisnonylphenyl phosphite antioxidant. For comparison, the first two runs in Table 1 used block copolymers outside the preferred ranges in composition (first run) and molecular weight (second run). In both runs, the absorbance of the product was high and unsatisfactory. Electron microscopy reveals that the polybutadiene regions of both products contain a "shell and shell" structure. This structure is
It consists of a polybutadiene shell with a diameter of over 100 nanometers and a polystyrene occluded core. Example 3 A large number of block copolymers containing styrene and isoprene and some block copolymers of styrene with isoprene or butadiene copolymer blocks were used in substantially the same manner as in Example 1. Polymerization was carried out. The results are shown in Table 2. In Table 2, "S/I" means styrene isoprene block copolymer, the item "composition" indicates the weight percent composition, and "molecular weight" indicates the gel/isoprene block copolymer.
Weight average molecular weight measured by permeation chromatography is shown. The letters in the notes column refer to footnotes indicating differences from the method used in Example 1.
All of the polymers thus obtained had a diameter of approximately
It showed rod-like and spherical polydiene regions less than 50 nanometers in size, and no occluded polystyrene was observed. As a stabilizer, a mixture of 2,6-di-(t-butyl)-4-methylphenol and trisnonyl phenyl phosphite as used in Example 1 or (n-octadecyl-3-(4- hydroxy-3,5-ditertially-butylphenyl)
-propionate) in the final product.
It was used in an amount of 0.2% by weight.

[Table] Similar to the previous examples, it is easy to make transparent impact resistant resins using other alkenyl aromatic monomers and mixtures thereof.

Claims (1)

[Claims] 1. 30 to 70% by weight of alkenyl aromatic monomer and 70
~30% by weight of diene in polymerized state, AB
or AB(BA)n configuration (A represents a block of polymerized alkenyl aromatic monomer, B represents a block of polymerized conjugated diene monomer, n is 1
is an integer between 5 and 5. ), molecular weight 40000-150000
A moldable resin composition comprising a diene polymer dispersed in an alkenyl aromatic polymer matrix obtained by polymerizing an alkenyl aromatic monomer in the presence of a block copolymer of The diene polymer region in the resin composition is rod-shaped or spherical with a diameter of less than 70 nanometers, and is free-radically polymerized and transparent, characterized by no occlusion of the polymerized alnickel aromatic monomer. Impact resistant alnickel aromatic resin composition. 2. The resin composition according to claim 1, wherein the block copolymer is a styrene-butadiene copolymer. 3. The resin composition according to claim 1, wherein the block copolymer is a styrene-isoprene copolymer. 4. The resin composition according to claim 1, wherein the polymerized conjugated diene monomer block in the block copolymer is a copolymer of butadiene and isoprene. 5 AB or AB(BA)n configuration (A represents a block of polymerized alkenyl aromatic monomer, B
represents a block of polymerized conjugated diene monomers, and n is an integer from 1 to 5). A method for producing a group resin composition, wherein the weight average molecular weight of the block copolymer is 4,000 to 150,000, and the block copolymer contains 30 to 70% by weight of a polymerized alkenyl aromatic monomer and 70 to 30% by weight. The diene-based polymer region in the composition is rod-shaped or spherical with a diameter of less than 70 nanometers, and no occlusion of the polymerized alkenyl monomer is observed. How to characterize it. 6. The method according to claim 5, wherein the block copolymer contains butadiene in a polymerized state and the antioxidant is added after polymerization has begun. 7. The method according to claim 5, wherein the block copolymer includes isoprene in a polymerized state.