JP2001316542A - Anion-polymerized styrenic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin composition which has excellent moldability, excellent thermal stability and excellent secondary processability of printability. SOLUTION: This styrenic resin composition characterized by comprising 1 to 99 pts.wt. of a styrenic polymer obtained by an anion polyurerization method and having a weight-average mol.wt. of 50,000 to 200,000 and 99 to 1 pts.wt. of a styrenic polymer obtained by an anion radical polymerization method and having a weight-average mol.wt. of 200,000 to 750,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anion-polymerized styrene-based resin composition having a very low content of monomers and oligomers and having excellent moldability, heat stability and printability.

[0002]

2. Description of the Related Art Conventionally, styrene resins are inexpensive and have excellent transparency, moldability, and rigidity. Therefore, various molding methods such as injection molding, extrusion molding, hollow molding, vacuum molding, and injection molding are used. And widely used in household electric appliances, office equipment, household goods, food containers, packaging materials, toys and the like. In general, styrene resins are mainly produced by thermal polymerization or radical polymerization using an initiator. The main production processes include a bulk polymerization method and a suspension polymerization method, but the bulk polymerization method is mainly used because impurities such as a dispersant are hard to mix and the cost is advantageous.

[0003] However, it is well known that such radical polymerization of styrene generally involves the formation of oligomers, and that styrene monomers are also likely to remain. For example, Encyclopedia of Chemical Technology, Kirk-Oth
According to mer, Third Edition, John Wily & Sons, vol. 21, p. 817, thermal polymerization at 100 ° C. or higher involves by-products of oligomers such as styrene dimer and styrene trimer, and the amount is about 1 wt%. ing. Specific oligomer components include 1-phenyl-4- (1′-phenylethyl) tetralin, 1,2-diphenylcyclobutane, 2,4-diphenyl-1-butene, and 2,4,6-triphenyl-1. Hexene and the like are present.

[0004] In the bulk polymerization process, polymerization is usually carried out at 80 to 180 ° C, and then most of the contained solvent and unreacted monomer is devolatilized in a recovery step. The recovered solvent, unreacted monomers, and the like are recycled, but some monomers, oligomers such as dimers and trimers are hardly volatilized, and some remain in the product resin.

As a result of analyzing the styrene-based resin thus produced, it was found that impurities, residues and by-products during polymerization were contained in the raw material. Specifically, styrene, α-
Methylstyrene, n-propylstyrene, n-propylbenzene, iso-propylbenzene, 1,3-diphenyl-1-butene, 1,2-diphenylcyclobutane,
1-phenyltetralin, 2,4,6-triphenyl-1-hexene, 1,3,5-triphenylbenzene, 1
-Phenyl-4- (1'-phenylethyl) tetralin and the like were found to be included in such styrene resins.

It is well known that such a monomer or oligomer in a styrene resin causes a decrease in thermal stability or an oily substance attached to a mold or a molded product during injection molding to cause a decrease in moldability. is there. Furthermore, since the monomer or oligomer in the styrene resin penetrates from the inside of the molded article to the surface, there is a problem that the printed surface of the molded article is easily peeled off. In general, to improve the moldability of styrenic resins, it is well known to increase the molecular weight distribution of the resin.However, if the molecular weight distribution of a styrene-based resin obtained by conventional radical polymerization is increased, low molecular weight components such as oligomers can be obtained. Is relatively increased.

On the other hand, a method of polymerizing polystyrene by anionic polymerization using an organometallic compound as an initiator is also known (for example, Journal of Organometallic Chemisty., 10 (1)
967) 1-6). According to the anionic polymerization method, since the polymerization reaction is continued as long as the monomer is substantially present, it is possible to greatly reduce unreacted monomers in the product,
If an active hydrogen compound such as water or alcohol, or impurities such as allenes and alkynes are present in the polymerization system, the carbanion at the polymerization terminal is deactivated, the polymerization reaction is stopped halfway, and a large amount of monomer remains or heat stability occurs. A large amount of low molecular components and the like that deteriorate the properties are produced as by-products.

Particularly in the anionic polymerization of styrene,
PK of phenylacetylene by-produced in styrene production process
a is relatively high (Accounts Chem. Res., 21, 456 (1988))
It acts as an impurity such as inactivating the polymerization reaction in the middle. In order to obtain a polystyrene-based resin by anionic polymerization in which oligomers such as monomers, dimers and trimers are reduced, it is necessary to control the amount of these impurities sufficiently.

US Pat. No. 4,725,654, US Pat. No. 4,572,819 and Japanese Patent Publication No. 6-17409 propose an anionic polymerization method of styrenes using an organometallic initiator. In these, a resin having a constant molecular weight is introduced by continuously introducing a raw material into a reaction vessel having stirring, taking out a reaction product mixture at the same speed, measuring a molecular weight of a produced resin, and controlling a flow rate of an initiator and the like. Is obtained. However, there is no disclosure or suggestion about the amount of oligomer in the polymer for the purpose of the present invention.

[0010]

As described above, the styrene-based resin obtained by the radical polymerization method widely used at present has a low molecular weight component consisting of oligomers such as monomers, dimers and trimers due to its production method. Including many. That is, the present invention proposes an anion-polymerized styrene-based resin composition having a low amount of low molecular weight components such as a monomer amount and an oligomer amount such as a dimer and a trimer in a product, and excellent in moldability, heat stability and printability.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a low-molecular styrene polymer obtained by anionic polymerization having a specific molecular weight distribution and a high-molecular styrene polymer obtained by anionic polymerization having a specific molecular weight distribution. It has been made based on the surprising fact that an anion-polymerized styrene-based resin composition having excellent thermal stability and excellent moldability can be obtained by reducing the amount of monomers and oligomers in a product by mixing with the union. It is.

That is, according to the present invention, the component (A) has a weight average molecular weight of 50,000 to 200,000 and a molecular weight distribution (weight average molecular weight /
(Number average molecular weight) is in the range of 1 to 3, and the total amount of the styrene monomer, dimer and trimer is 1000 p
pm less than 1 pm
Parts by weight and component (B) weight average molecular weight of 200,000 to 75
Anionic polymerized styrene-based polymer having a molecular weight distribution (weight-average molecular weight / number-average molecular weight) in the range of 1.5 to 4 and a total amount of styrene-based monomer, dimer and trimer of less than 1000 ppm; The styrene-based resin composition is a styrene-based resin composition comprising a styrene-based resin composition, wherein the total amount of the styrene-based monomer, dimer and trimer is less than 1000 ppm. .

Further, the present invention provides the styrenic resin composition, wherein the component (A) and the component (B) are styrenic polymers obtained by using an organolithium initiator, wherein lithium metal in the polymer is 1 to 1000 ppm. 3. The anionic polymerized styrenic resin composition according to claim 1 or 2, which is a styrenic polymer.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a styrene resin composition according to the present invention will be described in detail. Component (A) of the present invention is an anionically polymerized styrene-based polymer having a weight average molecular weight in the range of 50,000 to 200,000. When the weight average molecular weight is less than 50,000, the strength of the obtained styrene resin composition is not sufficient, and when it exceeds 200,000, the moldability deteriorates.

The component (B) of the present invention is an anionically polymerized styrene polymer having a weight average molecular weight in the range of 200,000 to 750,000. When the weight average molecular weight is less than 200,000, the strength of the resulting anion-polymerized styrene resin composition is not sufficient, and when it exceeds 750,000, the moldability deteriorates. Further, the component (A) of the present invention is an anion-polymerized styrene-based polymer having a molecular weight distribution (weight average molecular weight / number average molecular weight) in the range of 1 to 3. When the molecular weight distribution exceeds 3, the strength of the resulting anionic polymerized styrene resin composition is not sufficient.

The component (B) of the present invention is an anionic styrene polymer having a molecular weight distribution (weight average molecular weight / number average molecular weight) in the range of 1.5 to 4. When the molecular weight distribution is less than 1.5, the moldability of the obtained anion-polymerized styrene-based resin composition may be deteriorated, and when it exceeds 4, the strength of the obtained anion-polymerized styrene-based resin composition is not sufficient.

Further, the components (A) and (B) of the present invention
Is a styrene-based polymer obtained by anionic polymerization in which the total amount of styrene-based monomer, dimer and trimer is less than 1000 ppm. Styrene-based polymers having a total amount of styrene-based monomer, dimer and trimer of less than 500 ppm are more preferred. More preferably 200p
pm. When the amount of the low molecular weight components such as the styrene monomer, the dimer and the trimer is large, the thermal stability and the moldability are reduced.

Further, the styrene-based polymer obtained by anionic polymerization of the components (A) and (B) of the present invention contains lithium metal originating from an organic lithium as a polymerization initiator, and its hot water content is determined by anionic polymerization. The content is 1 to 1000 ppm based on the obtained styrene-based polymer. When lithium metal exceeds 1000 ppm, thermal stability may be deteriorated. The styrene-based polymer obtained by such anionic polymerization is obtained by anionic polymerization of a styrene-based monomer with an organolithium initiator which is an anionic polymerization initiator.

Specific examples of the organolithium initiator include n-butyllithium, sec-butyllithium and t-butyllithium.
-Butyllithium, methyllithium, ethyllithium,
Benzyl lithium, 1,6-dilithiohexane, and the like. These may be used alone or as a mixture of two or more. Preferred examples include n-butyllithium, sec-butyllithium, and t-butyllithium. These organic lithium initiators include hydrocarbon solvents, for example, aliphatic hydrocarbon solvents such as hexane, cyclohexane, pentane and heptane, aromatic hydrocarbon solvents such as benzene, toluene, ethylbenzene and xylene, tetrahydrofuran and dityl. ether,
It can be used by dissolving it in ethers such as dimethyl ether.

The amount of the organolithium initiator used depends on the molecular weight of the polymer to be obtained. That is, the molecular weight of the polymer is basically determined by the monomer amount and the composition ratio of the organolithium initiator. The amount of organolithium used per 100 g of monomer ranges from 0.05 to 20 mmol. Preferably it is in the range from 0.1 to 10 mmol, particularly preferably from 0.2 to 5 mmol.

There are various styrene monomers used in the method of the present invention. Specific examples are styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, 2,4-dimethylstyrene, , 5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-
Examples thereof include alkyl styrenes such as dimethyl styrene, p-ethyl styrene, m-ethyl styrene, and o-ethyl styrene. These styrene monomers may be used alone or in combination of two or more. The most preferred styrene monomer includes styrene.

In the present invention, an anionic copolymerizable monomer can be used together with the above-mentioned styrene-based monomer. Copolymerizable monomers include aromatic monovinyl compounds such as α-methylstyrene, vinyltoluene, vinylethylbenzene, and vinylxylene; conjugated diene compounds such as 1,3-butadiene and isoprene; and methyl methacrylate. Can be mentioned. These copolymer monomers may be useful in improving or adjusting the heat resistance, softening temperature, impact strength, rigidity, processability, etc. of the resin.

The industrial raw material or the commercially available styrene monomer contains the corresponding acetylene (phenylacetylene in the case of styrene). When phenylacetylene is polymerized with n-butyllithium using styrene as a monomer, it deactivates n-butyllithium,
And / or acts as a chain transfer agent, reducing the efficiency of the n-butyllithium used and / or producing a low molecular weight polymer. In order to obtain the styrenic resin of the present invention, the content of the phenylacetylene-based compound is preferably less than 200 ppm based on the styrenic monomer. More preferably less than 150 ppm, most preferably less than 100 ppm. When a styrene-based monomer containing 200 ppm or more of phenylacetylenes is used, the above-mentioned problems become apparent, low molecular components and the like in the product increase, and thermal stability during molding and the like is impaired.

The process for producing the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention is not particularly limited. Generally, it is carried out by the following process. For example, a complete batch polymerization method in which the entire amount of the monomer and the initiator is charged into the reaction tank and then polymerization, a semi-batch polymerization method in which the reaction tank is charged with part or all of the initiator, and then polymerization is performed while the monomer is additionally charged, and complete stirring. The raw material system (monomer and initiator) is continuously charged into the reaction tank in the state, and the same amount of the production system (polymer solution) is taken out while continuously stirring, or the reaction raw material system is started from one end of the tubular reaction tank. , And the product system is taken out from the other end. A continuous polymerization method of plug flow, or a series connection process thereof is conceivable.

In the production of the styrenic resin of the present invention, it can be preferably produced by a combined process in which a continuous polymerization tank with complete stirring and then a continuous polymerization tank with plug flow are combined. In the continuous polymerization process with complete stirring, the molecular weight distribution of the obtained polymer is broadened, and the remaining monomer can be efficiently converted in the continuous polymerization process in the next plug flow. Broadening the molecular weight distribution helps to improve the processability of the resin, and complete conversion of the monomer can eliminate low molecular weight components derived from the monomer mixed into the resin.

The production of the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention may be a bulk polymerization without solvent or a solution polymerization. Lower to facilitate stirring and heat removal,
Solution polymerization is preferred. That is, a styrene-based monomer is converted into a hydrocarbon-based solvent, for example, hexane, cyclohexane,
Polymerization is carried out by dissolving in an aliphatic hydrocarbon solvent such as heptane or an aromatic hydrocarbon solvent such as benzene, toluene, ethylbenzene or xylene. Preferred solvents are cyclohexane, toluene, ethylbenzene and xylene, most preferably ethylbenzene and toluene.

The amounts of the styrene monomer and the hydrocarbon solvent are preferably 80 to 10 parts by weight for the styrene monomer and 20 to 90 parts by weight for the hydrocarbon solvent. More preferably, the styrene monomer is 60 to 10 parts by weight, and the hydrocarbon solvent is 40 to 90 parts by weight. If the styrene monomer exceeds 80 parts by weight, the viscosity of the polymerization solution increases,
Extremely large power is required for stirring and transfer, and if the polymerization temperature is increased to lower the viscosity, the reaction rate becomes very fast and heat removal becomes difficult, or the polymerization is stopped by heat deactivation. If the amount is less than 10 parts by weight, a large amount of thermal energy is required for the recovery of the solvent, so that the heat history in the recovery step becomes excessive and the thermal decomposition of the resin is promoted.

In the production of the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, the polymerization temperature is preferably in the range of 0 to 130 ° C. More preferably 10 to 120 ° C, particularly preferably 20 to 110 ° C.
It is in the range of ° C. When the polymerization temperature is extremely low, the reaction rate is reduced, and the method is not practical. On the other hand, if the polymerization temperature is extremely high, the reaction rate is lowered due to decomposition of the initiator, which is not preferable. If the temperature is higher than 110 ° C., the polymer may be colored, which is not preferable depending on the application.

In the production of a styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, the viscosity of the solution during the polymerization is generally extremely high depending on the monomer concentration of the raw material system. For this reason, it is often difficult to remove the heat of polymerization by a jacket attached to a normal polymerization tank. A known method can be used as a method for increasing the heat removal capability of the equipment. For example, a method in which a heat removal coil is stretched in a reaction tank, an external circulation jacket is provided separately from a polymerization tank jacket, or a reflux condenser is provided can be preferably used.

The pressure in the polymerization tank needs to be sufficient to keep the system in a liquid tank. When a reflux condenser is used for removing the reaction heat, a reduced pressure can be used if necessary. In the production of the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, a carbon-lithium bond remains at the polymer terminal after the polymerization. If this is left as it is, it may be subjected to air oxidation or the like at the finishing stage or the like, which may cause a decrease in stability or coloring of the obtained styrene-based polymer. After polymerization, it is preferable to stabilize the active terminal of the polymer, that is, the carbon-lithium bond. For example, addition of a compound having an oxygen-hydrogen bond such as water, alcohol, phenol, and carboxylic acid, an epoxy compound, an ester compound, a ketone compound, a carboxylic anhydride, and a compound having a carbon-halogen bond can be expected to have similar effects. . The use amount of these additives is preferably about equivalent to about 10 times equivalent to the carbon-lithium bond. If it is too much, it is not only disadvantageous in terms of cost, but also there are many cases where mixing of the remaining additives becomes an obstacle.

In the production of a styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, a coupling reaction is carried out with a polyfunctional compound using a carbon-lithium bond to increase the polymer molecular weight. Further, the polymer chain may be formed into a branched structure. The polyfunctional compound used for such a coupling reaction can be selected from known compounds. Examples of the polyfunctional compound include a polyhalogen compound, a polyepoxy compound, a mono- or polycarboxylic acid ester, a polyketone compound, a mono- or polycarboxylic anhydride, and the like. Specific examples include silicon tetrachloride, di (trichlorosilyl) ethane,
1,3,5-tribromobenzene, epoxidized soybean oil,
Examples thereof include tetraglycidyl 1,3-bisaminomethylcyclohexane, dimethyl oxalate, tri-2-ethylhexyl trimellitate, pyromellitic dianhydride, and diethyl carbonate.

In the production of the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, an alkali component derived from an organolithium, for example, lithium oxide or lithium hydroxide is added to an intermediate by adding an acidic compound. Sum stabilization is also possible. Examples of such acidic compounds include carbon dioxide, boric acid, various carboxylic acid compounds, and the like. By these additions, the coloring resistance can be particularly improved in some cases. In the production of the styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention, lithium metal derived from the organolithium initiator remaining in the styrenic polymer is removed by a known method. Ash)
It is also possible. In particular, lithium metal is 100 per styrene-based polymer obtained by anionic polymerization.
When the amount exceeding 0 ppm remains, it becomes essential.

The styrenic polymer obtained by anionic polymerization of the components (A) and (B) of the present invention is known to improve its thermal or mechanical stability, antioxidant property, weather resistance and light resistance. Stabilizers can be added.
For example, JP-A-7-292188 discloses that addition of a 2,4,6-trisubstituted phenol is advantageous as a method for stabilizing polystyrene. 2,
Preferred examples of the 4,6-trisubstituted phenol include 2,6-
Di-tert-butyl-4-methylphenol, triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritoltetrakis [3- (3 5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-t-butyl-4
-Hydroxybenzyl) benzene, n-octadecyl 3
-(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2 [1- (2-hydroxy-3,5-di-tert-pentyl) Phenyl)]-4,6-di-
t-pentylphenyl acrylate, tetrakis [methylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 3,9bis [2-
{3- (t-butyl-4-hydroxy-5-methylphenyl) propynyloxy} -1,1-dimethylethyl]
-2,4,8,10-tetraoxo [5,5] undecane, 1,3,5-tris (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) -s-triazine-2,
4,6 (1H, 2H, 3H) -trione, 1,1,4-
Tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4,4′-butylidenebis (3-methyl-6-t-butylphenol) and the like can be mentioned.

These stabilizers can be mixed after the recovery of the polymer. However, it is preferable to add them at the stage of the solution after the polymerization because mixing is easy and deterioration in the solvent recovery step can be suppressed. Components (A) and (B) of the present invention
In the production of a styrenic polymer obtained by anionic polymerization of the above, after the polymerization is completed, the obtained polymerization solution is volatilized and removed from the polymer to recover unreacted monomers and a solvent. Known methods can be used for volatilization. As the volatilization removing device, for example, a method of flashing in a vacuum tank and a method of devolatilization by an extruder can be preferably used. Generally, the temperature is 18 ° C, depending on the volatility of the solvent.
Volatile components such as a solvent and residual monomers are volatilized and removed at 0 to 260 ° C. and a degree of vacuum of 100 Pa to 50 kPa. It is also effective to connect the devolatilizers in series and arrange them in two stages. A method of adding water between the first and second stages to increase the volatility of the second-stage monomer can also be used.

As a method for mixing the components (A) and (B) thus obtained, the components independently obtained are mixed with a known device, for example, a kneader, a Banbury mixer, a single-shaft or a twin-shaft. They can be mixed by melt kneading with an extruder or the like. Alternatively, it can be obtained by mixing the polymerization liquid of the component (A) and the polymerization liquid of the component (B), continuing the polymerization as needed, and devolatilizing and drying by a known method.
In some cases, the component (A) pellets and the component (B) pellets may be dry-blended by a known method.

The total amount of the styrene monomer, dimer and trimer in the anionic polymerized styrene resin composition obtained by the present invention is less than 1000 ppm. When the total amount of the styrenic monomer, dimer and trimer is 5
Preferably it is less than 00 ppm. More preferably, it is less than 200 ppm. When the amount of the low molecular weight components such as the styrene monomer, the dimer and the trimer is large, the thermal stability and the moldability are reduced.

The anionic polymerized styrenic resin composition obtained according to the present invention may contain, if necessary, various additives usually used, for example, stabilizers, dyes, pigments, fillers, lubricants, release agents, plasticizers, A molding material can be obtained by adding an antistatic agent, an antioxidant and the like. Further, the anion-polymerized styrene-based resin composition obtained by the present invention, polystyrene or high-impact polystyrene obtained by radical polymerization, if desired, other thermoplastic resins, such as styrene-butadiene block copolymers and hydrogenated products thereof, Polyphenylene ether, ABS and the like can be blended.

The anionic polymerized styrenic resin composition obtained by the present invention can be molded by a conventionally known method, for example, injection molding, extrusion molding, hollow molding, vacuum molding, injection molding or the like. The styrenic resin of the present invention thus obtained is excellent in moldability, thermal stability and printability, so that it can be widely used in household electric appliances, office equipment, household goods, food containers, various packaging materials, toys and the like. Available.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Styrene monomers, dimers and trimers were quantified using gas chromatography. Here, the dimer is the total amount of 1,2-diphenylcyclobutane and 2,4-diphenyl-1-butene, and the trimer is 1-phenyl-4- (1′-phenylethyl) tetralin,
It was determined as the total amount of 4,6-triphenyl-1-hexene.

The molecular weight and the molecular weight distribution were determined by the GPC method.
At 5 ° C., using tetrahydrofuran as a measuring solvent,
It was detected by UV / RI and determined by polystyrene conversion. Component (A) of the present invention according to the following Reference Examples 1 to 5
Of styrene-based polymers A1 and A2, and styrene-based polymers B1 to B3 of component (B). Table 1 shows the properties of the obtained styrenic polymer. Reference Example 6 shows a method for producing polystyrene by radical polymerization, and Reference Example 7 shows a method for producing anion-polymerized polystyrene by batch polymerization.

[0041]

Reference Example 1 Production of Styrenic Polymer A1 A reflux condenser with a heat transfer area of 0.2 m ³ was mounted on the upper part of a 12-liter capacity complete mixing type reactor equipped with a stirrer and equipped with a jacket. did. Further, a 4 L piston flow reactor (L / D = 3.5) equipped with a stirrer was arranged in series downstream of the first reactor to form a second reactor. The insides of the first and second reactors were degassed under reduced pressure, and the inside of the tank was set to a nitrogen atmosphere.

Degassed styrene from which a polymerization inhibitor (tertiary butyl catechol) and water have been removed in advance (phenylacetylene in the styrene was 31 ppm) was added in 50 parts.
50 parts by weight of degassed and purified ethylbenzene as a polymerization solvent were mixed in a mixing tank. In the first reactor and the second reactor, the temperature of the reaction vessel was set at 80 ° C. A mixed solution of styrene monomer and ethylbenzene was fed from the blending tank at a flow rate of 8 L / h. The amount held in the tank of the first reactor was controlled at 8 L. The pressure in the first reactor was reduced, the pressure was maintained at 15 kPa, and ethylbenzene was refluxed to maintain the polymerization temperature at 80 ° C. n-Butyl lithium was fed to the first reactor in an amount corresponding to 1.0 mmol per 100 g of styrene monomer.

The reaction solution flowing out of the first reactor was subsequently introduced into the second reactor and passed through a piston flow.
The conversion from monomer to polymer at the point of exit from the first reactor was 98.5% on average, and the conversion after passing through the second reactor was 99.99% or more. The resulting polymer solution was deactivated by adding 10 times equivalent of methanol to the amount of lithium. Thereafter, 0.05 g of an antioxidant was added to the polymer solution per 100 g of the polymer, and volatile components were removed by a reduced pressure flushing tank and a vented extruder to form a pellet.
The content of lithium metal is 490pp by atomic absorption analysis.
m.

[0044]

Reference Example 2 Production of Styrenic Polymer A2 The same procedure as in Reference Example 1 was carried out except that n-butyllithium was fed to the first reactor in an amount equivalent to 1.3 mmol per 100 g of styrene monomer. The content of lithium metal determined by atomic absorption analysis was 660 ppm.

[0045]

Reference Example 3 Production of Styrenic Polymer B1 The same procedure as in Reference Example 1 was carried out except that n-butyllithium was fed to the first reactor in an amount corresponding to 0.9 mmol per 100 g of styrene monomer. The content of lithium metal determined by atomic absorption analysis was 390 ppm.

[0046]

Reference Example 4 Production of Styrene Polymer B2 The same procedure as in Reference Example 1 was carried out except that n-butyllithium was fed to the first reactor in an amount corresponding to 0.7 mmol per 100 g of the styrene monomer. The content of lithium metal was 280 ppm by atomic absorption analysis.

[0047]

Reference Example 5 Production of Styrene-Based Polymer B2 The same procedure as in Reference Example 1 was carried out except that n-butyllithium was fed to the first reactor in an amount corresponding to 0.5 mmol per 100 g of the styrene monomer. The content of lithium metal as measured by atomic absorption analysis was 190 ppm.

[0048]

Reference Example 6 Production of Radical Polymerized Polystyrene A completely mixed reactor having a capacity of 12 L and equipped with a stirrer was used as a first reactor. Furthermore, a 4 L piston flow reactor equipped with a stirrer (L / D =
3.5) was arranged in series downstream of the first reactor to form a second reactor. The insides of the first and second reactors were degassed under reduced pressure, and the inside of the tank was set to a nitrogen atmosphere.

85 parts by weight of degassed styrene from which a polymerization inhibitor (tertiary butyl catechol) and water had been removed, and 15 parts of degassed and purified ethylbenzene as a polymerization solvent.
The parts by weight were mixed in the compounding tank. The temperature of the reactor in the first reactor was set at 140 ° C. and the temperature of the reactor in the second reactor was set at 180 ° C. A mixture of styrene monomer and ethylbenzene is fed at a flow rate of 1.2 L / h from the blending tank,
Thermal radical polymerization was performed. The amount held in the tank of the first reactor was controlled at 8 L.

The reaction solution flowing out of the first reactor was subsequently introduced into the second reactor and passed through a piston flow.
Then, the polymer solution per 100g of polymer,
After adding 0.05 g of an antioxidant, a volatile component was removed by heat treatment at 240 ° C. in a reduced pressure flushing tank to form a pellet. The radically polymerized polystyrene obtained here is designated as C1.

[0051]

Reference Example 7 Production of Anion-Polymerized Styrenic Polymer C2 by Batch Polymerization Using only the first reactor of Reference Example 1, the inside of the reactor was degassed under reduced pressure, and the inside of the tank was set to a nitrogen atmosphere. In advance, 4 kg of degassed styrene from which a polymerization inhibitor (tertiary butyl catechol) and water had been removed and 4 kg of degassed and purified ethylbenzene as a polymerization solvent were all introduced into a reactor.

The temperature of the reactor was set at 100.degree. A mixture of styrene monomer and ethylbenzene in the reactor was charged at 10 L / min. At a flow rate of n-Butyl lithium was fed into the circulating flow in an amount corresponding to 0.52 mmol per 100 g of the styrene monomer, and thoroughly mixed with a line mixer. Depressurize the first reactor and reduce the pressure to 15
The polymerization temperature was kept at 80 ° C. by maintaining the pressure at kPa and refluxing ethylbenzene.

The polymerization reaction was continued for one hour. The monomer conversion in the reactor was 99.99% or more. Thereafter, the same operation as in Reference Example 1 was performed. The styrene-based polymer obtained here is designated as C2. The content of lithium metal was 210 ppm by atomic absorption analysis.

[0054]

Examples 1 to 6 and Comparative Examples 1 to 4 Preparation of Styrenic Resin Composition The styrenic polymers obtained in Reference Examples 1 to 7 were mixed in a twin-screw extruder at the compounding ratio shown in Table 2. And melt-kneaded to obtain a styrene resin composition. The obtained styrenic resin was 280
After staying in the melt indexer heated to 10 ° C. for 10 minutes, the amounts of monomers and oligomers were quantified, and the thermal stability was evaluated.

Further, using the obtained styrene resin composition, a 1.2 mm thick sheet was injection molded at a resin temperature of 240 ° C. and a mold temperature of 50 ° C. The moldability was evaluated in the state of the flow mark on the molded sheet. The printability was determined by silk-screen printing a printing ink for polystyrene on the molded sheet, drying at 90 ° C. for 2 hours, and further drying at 25 ° C. for 24 hours.
After leaving for a period of time, a cellophane tape was adhered to the tape, and the tape was peeled off. Table 3 shows the results.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

(In the table, the moldability was evaluated as follows: ○: no flow mark was observed, Δ: slight flow mark was observed, ×: flow mark was noticeably observed. No peeling of the printed surface is observed, Δ:
X: Slight peeling of the printed surface was observed. X: Remarkably peeling of the printed surface was observed. )

[0060]

The molded article using the anionically polymerized styrene resin composition of the present invention is excellent in moldability, heat stability and printability.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 BC03W BC03X BC04W BC04X BC07W BC07X BC08W BC08X FD030 GC00 GG01 GG02 GQ00 4J100 AB02P AB04P CA01 CA04 DA01 DA04 FA00 FA08 JA43 JA57 JA58

Claims (3)

[Claims] (1) Component (A) having a weight average molecular weight of 50,000 to 20
Anionically polymerized styrenic polymers 1 to 99 in the range of 10,000
Parts by weight and component (B) weight average molecular weight of 200,000 to 75
Anionic polymerized styrene-based polymer 99-1 in the range of 10,000
An anionically polymerized styrene resin composition comprising parts by weight. 2. Anionic polymerization wherein the molecular weight distribution (weight average molecular weight / number average molecular weight) of the anionic polymerized styrene-based polymer of component (A) is 1 to 3, and the total amount of styrene-based monomer, dimer and trimer is less than 1000 ppm. A molecular weight distribution (weight average molecular weight / number average molecular weight) of the anionic polymerized styrene-based polymer of the component (B) is in the range of 1.5 to 4, and a styrene-based monomer;
The anionic polymerized styrene-based resin composition according to claim 1, wherein the total amount of the dimer and the trimer is less than 1000 ppm. 3. The component (A) and the component (B) are styrenic polymers obtained with an organolithium initiator, and the lithium metal in the polymer is a styrenic polymer of 1 to 1000 ppm. 2. An anionically polymerized styrenic resin composition according to item 2.