JP2001026619A - Styrene-based resin, preparation thereof, and food packing vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrene-based resin and a preparing process thereof which resin is excellent in the productivity at the time of fabricating and in the external appearance of a molded article and also is suitable for a use as a food packaging vessel with almost odorlessness and to provide a sheet there from. SOLUTION: A styrene-based resin, comprising 50-80 wt.% of a styrenic monomer unit, 20-50 wt.% of a (meth)acrylic ester monomer unit and 0-20 wt.% of other copolymerizable monomer unit, is characterized in that the sum total content of unreacted monomers in this styrene-based resin is 1,000 ppm or less, and the sum total content of styrene dimers and styrene trimers is 1,000 ppm or less, and also a content of the sulfur derived from a sulfur-based chain transfer agent is 70 ppm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a styrenic resin, and more particularly to a styrenic resin based on an unreacted monomer, the total amount of styrene dimer and styrene trimer, and a sulfur-based chain transfer agent. Food packaging containers with excellent odor and low odor during injection molding, sheet production and secondary processing, and with a low odor, characterized in that the sulfur content is not more than the specified amount. The present invention relates to a styrene-based resin suitable for applications such as the above, a method for producing the styrene-based resin, and a styrene-based resin sheet and a food packaging container using the styrene-based resin.

[0002]

2. Description of the Related Art Styrene resins represented by polystyrene are excellent in transparency, rigidity, moldability, etc., and are inexpensive. Therefore, they are used for household goods, toys, housing materials for OA equipment, food packaging containers, and the like. I have. In particular, the use of food packaging containers has grown remarkably due to the spread of microwave ovens for business use and home use, and an increase in the number of convenience store stores. Accordingly, it has been required to improve productivity and appearance of sheets and food packaging containers, and to reduce odor when heated.

[0003] As a method of improving the productivity of sheets and food packaging containers, a method of lowering the melt viscosity of a styrene resin by adding a lubricant and a plasticizer to improve sheet extrudability, sheet processability, or injection moldability. However, if a large amount of a lubricant or plasticizer is added, the lubricant or plasticizer bleeds out on the sheet surface during sheet production and contaminates the sheet surface or rolls, resulting in poor sheet appearance and frequent roll cleaning. . Further, when a sheet is formed, mold contamination and transfer of contaminants to the molded product occur, and the frequency of mold cleaning is high, and the appearance of the molded product is deteriorated, so that productivity is impaired. Similarly, during injection molding, the injection mold is contaminated, contaminants adhere to the molded product, the frequency of mold cleaning is high, and the appearance of the molded product is inferior, so that productivity is impaired.

[0004] As a technique for improving the appearance of sheets and food packaging containers, the molecular weight of a styrene resin is reduced.
Although there is a method for improving the mold transferability, if the molecular weight is low, the sheet and the food packaging container become brittle, and the sheet breaks during the production of the sheet or cracks occur when the edge of the sheet molded product is punched. As a method of further reducing odor, there is a method of reducing residual volatile components, but there is a limit to the reduction of residual volatile components, and it is not always satisfactory.

[0005]

That is, the present invention relates to a styrene-based resin which is excellent in productivity at the time of molding and appearance of a molded article, and has low odor and is suitable for use in food packaging containers and the like, and a method for producing the resin. It is to provide a styrene resin sheet and a food packaging container using the resin.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have developed an unreacted monomer or a non-reacted monomer remaining in a styrene resin having a styrene monomer unit and a (meth) acrylate monomer unit as main components. The styrene dimer and styrene trimer contained as a by-product, and the sulfur content based on the sulfur-based chain transfer agent cause the productivity, appearance and odor of styrene-based resin sheets and food packaging containers made of styrene-based resin. The amount of these unreacted monomers, the amount of by-products of styrene dimer and styrene trimer, and the sulfur content based on the sulfur-based chain transfer agent are suppressed by a specific polymerization method. The present invention has been completed for the first time with a styrenic resin obtained by controlling the content of the styrenic resin to a certain value or less.

That is, the present invention provides a styrene monomer unit 50
-80% by weight, 20-50% by weight of (meth) acrylate monomer units and 0-20% by weight of other copolymerizable monomer units, wherein the copolymer contains (1)
The total content of unreacted monomers is 1000 ppm or less,
And (2) a styrene-based resin having a total content of styrene dimer and styrene trimer of 1000 ppm or less, and (3) a sulfur content based on a sulfur-based chain transfer agent of 70 ppm or less, and a styrene resin thereof. The present invention relates to a styrene resin sheet and a food packaging container using a styrene resin.

Further, a total of 0.01 to 5 parts by weight of a polyfunctional organic peroxide or two or more monofunctional organic peroxides as a polymerization initiator is added to a total of 100 parts by weight of the monomers, and The present invention relates to a method for producing the styrenic resin, wherein the polymerization temperature is controlled to less than 110 ° C. until the rate reaches 50% by weight or more, and then the polymerization temperature is controlled to exceed 125 ° C. to carry out radical copolymerization.

Further, a styrene resin composition containing 10 parts by weight or less (but not including 0) of a rubbery polymer with respect to 100 parts by weight of the styrene resin, and a styrene resin composition comprising The present invention relates to a styrene resin sheet and a food packaging container used.

The styrenic monomer constituting the styrenic resin of the present invention refers to styrene, α-methylstyrene, or styrene in which a part of a benzene nucleus is substituted with an alkyl group. Particularly preferred is styrene. These styrene monomers may be used alone or in combination of two or more.

The (meth) acrylate monomers used in the present invention include methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, and n-methacrylate. Acrylic esters such as butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, and decyl acrylate are exemplified, and methyl methacrylate or n-butyl acrylate is preferred.
Particularly preferred is methyl methacrylate. These (meth) acrylate monomers may be used alone or in combination of two or more.

The other copolymerizable monomer is not particularly limited as long as it is a monomer copolymerizable with a styrene monomer and a (meth) acrylate monomer.
Radical-polymerizable polybasic acids such as itaconic acid, maleic anhydride and itaconic anhydride and their anhydrides, maleimide, N-
Examples thereof include maleimide monomers such as methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide, and monomers such as acrylic acid, methacrylic acid, or (meth) acrylamide and (meth) acrylonitrile. Preferred is methacrylic acid.

Further, when heat resistance is imparted to these styrenic resins, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, etc. are taken into consideration in order to reduce unreacted monomers remaining in the copolymer. Acid, maleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, methacrylic acid and the like are used.

The styrenic resin of the present invention contains 50 to 80% by weight of a styrene type monomer unit, 20 to 50% by weight of a (meth) acrylate monomer unit and 0 to 50% of another copolymerizable monomer unit. It is obtained by radical copolymerization of a copolymer consisting of 20% by weight. If the styrene-based resin of the present invention contains less than 50% by weight of styrene-based monomer units, the moldability will be poor, and if it exceeds 80% by weight, the production ratio of styrene dimer and styrene trimer will increase. Not preferred. Also,
If the amount of the other copolymerizable monomer unit exceeds 20% by weight, the productivity, appearance, and odor balance of the styrene resin sheet and the food packaging container will be poor, which is not preferable. A more preferred range is 50 to 75% by weight of a styrene monomer unit, and 25 to 50% of a (meth) acrylate monomer unit.
% By weight, other copolymerizable monomer units from 0 to 18% by weight, particularly preferably 50 to 65% by weight of styrene-based monomer units, and 35 to 5 of (meth) acrylate monomer units.
0% by weight and 0 to 15% by weight of other copolymerizable monomer units. The monomer may be present in the entire amount at the beginning of the polymerization, or may be added while the monomer is being added during the polymerization.

In addition, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, maleimide, N-methylmaleimide, N
-Ethylmaleimide, N-cyclohexylmaleimide,
When a monomer such as N-phenylmaleimide or methacrylic acid is used, the amount is preferably 1% by weight to 20% by weight, more preferably 3 to 18% by weight, and particularly preferably 5 to 15% by weight.
% By weight.

The total amount of the unreacted monomer remaining in the styrenic resin of the present invention is 1000 ppm or less. 1
If it exceeds 000 ppm, these unreacted monomers will adhere to a mold or cause odor when molding using the styrene resin. In particular, during sheet production, unreacted monomers bleed out to the sheet surface, contaminating the sheet surface and rolls. In addition, the mold is contaminated during sheet molding. Therefore, it is preferably 800 ppm or less, more preferably 600 ppm or less.

The styrene dimer referred to in the present invention is 1,2-
Diphenylcyclobutane, 2,4-diphenyl-1-butene, and the like, and styrene trimer is 2,4,6-triphenyl-1-hexene, 1-phenyl-4- (1′-phenylethyl) tetralin, Although it is triphenylcyclohexane or the like, specifying the structure of these oligomers is not directly related to the object of the present invention or the effects of the present invention.

The styrene resin of the present invention has a total content of styrene dimer and styrene trimer of 1000 pp.
m or less. If the content exceeds 1000 ppm, it bleeds out to the sheet surface during sheet production and contaminates the sheet surface and the roll. In addition, the mold is contaminated during sheet molding. It also causes odor. More preferably 80
0 ppm or less, more preferably 600 ppm or less.

The sulfur content based on the sulfur-based chain transfer agent of the present invention refers to n-dodecyl mercaptan, n-octyl mercaptan, t-dodecyl mercaptan and the like for the purpose of adjusting the molecular weight and the like during the polymerization of a styrene resin described later. When a sulfur-based chain transfer agent is added, it refers to the sulfur content in the styrene-based resin based on the chain transfer agent.

The sulfur content of the styrenic resin of the present invention based on the sulfur chain transfer agent is 70 ppm or less. 7
If it exceeds 0 ppm, it causes a specific odor. More preferably 50 ppm or less, still more preferably 30 ppm.
ppm or less. It is particularly preferable to use a sulfur-free additive such as α-methylstyrene dimer in order to adjust the molecular weight and the like of the styrene resin.

It is preferable that the styrene resin of the present invention has Mw (weight average molecular weight) of 100,000 to 450,000 and Mz (Z average molecular weight) / Mw of 1.5 to 3.0. M
If w is smaller than 100,000, the styrene-based resin itself tends to be brittle, and the styrene-based resin sheet and its molded article also tend to be brittle. On the other hand, when Mw is larger than 450,000, the melt viscosity becomes large, and sheet forming and secondary forming processability are difficult, and the productivity tends to be poor. Further, Mz / Mw is 1.5 to
When the ratio is out of the range of 3.0, sheet forming and secondary forming are difficult, and productivity tends to be poor. More preferably, Mw
Is 120,000 to 400,000, particularly preferably 150,000 to 3
80,000. In the case of Mz / Mw, it is more preferably from 1.5 to 2.8, and particularly preferably from 1.6 to 2.5.
It is.

Next, a method for producing a styrene resin satisfying the conditions of the present invention will be described. According to the findings of the present invention, the formation of styrene dimer and styrene trimer is suppressed by allowing a sufficient amount of a polymerization initiator to be present at the time of radical polymerization and by performing polymerization at a relatively low temperature. However, if the polymerization is carried out at a low temperature, a large amount of monomers will remain or the productivity will be reduced. Therefore, it is necessary to carry out the polymerization while maintaining a controlled temperature state in the high conversion region. In the present invention, by using a polyfunctional organic peroxide or two or more monofunctional organic peroxides as the polymerization initiator, a sufficient amount of the polymerization initiator is present in a high conversion region, and a styrene dimer, It has been found that formation of a monomer can be suppressed, and that a large amount of monomer remains or a decrease in productivity can be suppressed.

That is, a polyfunctional organic peroxide or two or more monofunctional organic peroxides is used as a polymerization initiator in a total amount of 0.01 to 5 parts by weight, more preferably 100 parts by weight of the total of the monomers used. Is from 0.03 to 3 parts by weight, more preferably from 0.
0.5 to 1 part by weight, and the conversion is 50% by weight or more, more preferably 60% by weight or more, further preferably 70% by weight.
After controlling the polymerization temperature up to the above to less than 110 ° C., preferably less than 105 ° C., more preferably less than 100 ° C., then the polymerization temperature more than 125 ° C., more preferably more than 127 ° C., still more preferably Is controlled at a polymerization temperature higher than 129 ° C., but the upper limit is 250 ° C. or lower, whereby a styrene resin satisfying the object of the present invention can be produced by performing radical copolymerization.

When the content of the organic peroxide is less than 0.01 part by weight, the effect of suppressing by-products of oligomers including styrene dimer and trimer is insufficient, and when the content exceeds 5 parts by weight, the effect is insufficient. In addition to being economically unfavorable because of saturation, the obtained resin is inferior in heat stability and light resistance. The conversion is 50% by weight.
If the polymerization temperature up to 110 ° C. is 110 ° C. or higher, oligomers are by-produced, which is not preferable. Even when the polymerization temperature until the conversion reaches 50% by weight is controlled to less than 110 ° C., unless the subsequent polymerization temperature is controlled to a temperature exceeding 125 ° C., a large amount of monomer remains and the sheet Bleed-out on the sheet surface during production, and contamination or odor on the sheet surface tends to be inferior. However, the upper limit temperature is preferably 250 ° C. or lower as described above. When the temperature exceeds 250 ° C., the obtained styrene resin tends to have poor thermal stability.

In the present invention, examples of the polyfunctional organic peroxide include 1,1-bis (t-butylperoxy) -3,
3,5-trimethylcyclohexane, 1,1-bis (t
-Butylperoxy) -cyclohexane, 2,2-bis (4,4-di-butylperoxycyclohexyl) propane, ethyl-3,3-di (t-butylperoxy) butyrate and the like. Examples of monofunctional organic peroxides include t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, and t-butylperoxy. Isopropyl monocarbonate, t-hexylperoxybenzoate, t-butylperoxyacetate, t-butylperoxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, di-t-butylperoxide, t-butylperoxy -2-ethylhexanoate and the like. As the half-life temperature, the one-hour half-life temperature is preferably from 80 to 160C, more preferably from 100 to 145C.

In the present invention, it is necessary to add a polyfunctional organic peroxide or two or more monofunctional organic peroxides for polymerization, and to add only one kind of monofunctional organic peroxide. If the polymerization is carried out, the desired product cannot be obtained, for example, a large amount of monomer remains. If a polyfunctional organic peroxide or two or more monofunctional organic peroxides are used, polymerization may be further performed by adding another polyfunctional organic peroxide or monofunctional organic peroxide. Can also.

Further, there is a chain transfer agent added during polymerization for the purpose of adjusting the molecular weight of the styrenic resin of the present invention. Examples thereof include sulfur-based chain transfer agents such as n-dodecyl mercaptan, n-octyl mercaptan, t-dodecyl mercaptan, and α-methylstyrene dimer.

When a sulfur-based chain transfer agent such as n-dodecyl mercaptan, n-octyl mercaptan or t-dodecyl mercaptan is used, the sulfur content in the styrene-based resin based on the sulfur-based chain transfer agent is 70 ppm. It is necessary to use it in the following amount.

The styrenic resin of the present invention is produced by radical polymerization. Specifically, suspension polymerization, bulk polymerization, solution polymerization and the like are preferable, and suspension polymerization is preferable. Suspension polymerization can easily remove heat generated by polymerization and can efficiently polymerize to a high conversion region, so that unreacted monomers, styrene dimers and styrene trimers can be efficiently suppressed.

The styrenic resin of the present invention may be mixed with a rubbery polymer for the purpose of improving the impact strength of the styrenic resin and the toughness or smoothness of the sheet, or may be used in the presence of a rubbery polymer. Polymerized monomer (co)
These rubbery polymer-containing (co) polymers obtained by polymerizing a polymer, a styrenic monomer and a (meth) acrylate monomer and / or a monomer copolymerizable therewith. Coalescence can be mixed. Further, a rubbery polymer and a (co) polymer containing a rubbery polymer can be used in combination. Hereinafter, these are referred to as styrene resin compositions. Since the rubbery polymer-containing (co) polymer also has a rubbery polymer, it can be said that the styrenic resin composition of the present invention contains a rubbery polymer.

The rubbery polymer used for the rubbery polymer or the rubbery polymer-containing (co) polymer is preferably polybutadiene, styrene-butadiene block copolymer or styrene-butadiene random copolymer,
The composition ratio of styrene and butadiene is preferably set so that the difference in refractive index between the resin component and the continuous phase is within the following range.

When the rubbery polymer and / or the copolymer containing a rubbery polymer is mixed with the styrene resin of the present invention, the transparency of the mixture (styrene resin composition) is emphasized. For the purpose of ensuring the above, the difference in the refractive index between the resin component as the continuous phase of the styrene resin composition and the rubber particles forming the dispersed phase is preferably 0.1 or less, more preferably 0.01 or less.

The styrene monomer used in the rubbery polymer-containing (co) polymer is the above-mentioned monomer such as styrene, and the (meth) acrylate monomer is the above-mentioned monomer. Monomers such as methyl methacrylate, as the monomer copolymerizable with these monomers, methacrylic acid, maleic acid, monomers mentioned as other copolymerizable monomers such as acrylonitrile Used.

The amount that can be mixed into the styrene resin composition is preferably 10 parts by weight or less (however, 0 is not included) as the content of the rubbery polymer with respect to 100 parts by weight of the styrene resin. It is more preferably 0.01 to 8 parts by weight, particularly preferably 0.05 to 5 parts by weight. If the rubber-like polymer is less than 0.01 part by weight, the improvement effect cannot be sufficiently exhibited,
If it is more than 10 parts by weight, the effect is not only saturated but also tends to be poor in transparency, rigidity and oil resistance.

In the mixture of the styrenic resin of the present invention and a rubbery polymer and / or a (co) polymer containing a rubbery polymer, the volume average particle diameter of the rubber particles as a dispersed phase is 0.0
It is 3 μm to 5 μm, preferably 0.1 μm to 4 μm, more preferably 0.2 μm to 3 μm. If the average particle size of the rubber particles is less than 0.03 μm, the effect of improving toughness and smoothness cannot be sufficiently exhibited, and if it is more than 5 μm, not only the effect is saturated, but also the transparency, rigidity, and oil resistance decrease. Show the trend.

The method for producing the rubbery polymer-containing (co) polymer is not particularly limited, but the rubbery polymer-containing (co) polymer is dissolved in a monomer constituting a resin component in the presence of a rubbery polymer latex produced by emulsion polymerization. A method of bulk polymerization, solution polymerization or suspension polymerization is preferred. For example, the techniques disclosed in JP-B-45-31677, JP-B-46-32748, and JP-B-47-8624 are known. . It is also possible to use a rubber-like polymer-containing (co) polymer having different properties of rubber particles produced by different methods in combination.

The styrenic resin of the present invention may contain, if necessary, an antioxidant, a lubricant, a release agent, a plasticizer, a pigment, a dye, a foaming agent, a foam nucleating agent, an inorganic filler, an antistatic agent, a sliding agent, and the like. Known additives can be contained. Further, the styrenic resin of the present invention is GP-PS, HI-PS, MS resin,
BS resin, AS resin, ABS resin, PE, PP, PPO
It can also be used in combination with known resins.

The styrene resin and the styrene resin composition of the present invention can be made into a styrene resin sheet and a food packaging container by a known method. For example, a method for producing a styrene-based resin sheet includes a uniaxial stretching method, a biaxial stretching method, a multiaxial stretching method, a foam molding method, a coextrusion method, and a lamination method. Among them, the biaxial stretching method is preferred. Examples of the method for manufacturing the food packaging container include an injection molding method, a pressure forming method, a vacuum forming method, and a vacuum pressure forming method for the sheet. Among them, the injection molding method and the vacuum pressure molding method are preferable.

[0039]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. “%” Is based on weight. First, the evaluation method in the present invention will be described below.

(1) Measurement of monomer units: Using ¹³ C-NMR, the resin composition was calculated from the area ratio of the spectrum peak caused by each monomer unit. (2) Measurement of unreacted monomer: It was measured by the internal standard method using gas chromatography described below. Apparatus name: GC-12A (manufactured by Shimadzu Corporation) Column: glass column φ3 mm × 3 m Quantification: internal standard method (cyclopentanol) (3) Measurement of styrene dimer and trimer: measurement by gas chromatography For details, refer to Literature issued by the Polyolefin Hygiene Council, "Self-regulatory Standards for Polyolefin and Other Synthetic Resin Food Containers and Packaging" (Third Edition),
The measurement was performed according to the measurement method described in Part 3 Hygiene Test Method-Supplement (May, 1993). (4) Measurement of Sulfur Content Based on Sulfur-Based Chain Transfer Agent: Using a styrene resin plate, sulfur was quantified by a fluorescent method of X-ray analysis. (5) Weight average molecular weight (Mw) and Z average molecular weight (M
Measurement of z): Measured under the GPC measurement conditions described below. Apparatus name: SYSTEM-21 Shodex (manufactured by Showa Denko KK) Column: three PLgel MIXED-Bs in series Temperature: 40 ° C Detection: differential refractive index Solvent: tetrahydrofuran Concentration: 2% by weight Calibration curve: standard PS (manufactured by PL) (The molecular weight is converted to PS.) (6) Volume average particle diameter of rubber particles: Measured by the method described below. Apparatus name: Laser diffraction type particle analyzer LS-23
Type 0 (manufactured by Coulter, Inc.) Solvent: dimethylformamide

(7) Evaluation of productivity: Sheet extrusion was performed under the following conditions, and the degree of contamination of the roll was evaluated. Sheet extruder: φ40mm extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) T die width: 500mm Extrusion temperature: 230 ° C Extrusion time: 5 hours Roll contamination: ◎ almost none, ○ slightly, △ half of roll surface contamination Yes, x Roll surface almost contaminated (8) Evaluation of productivity: The uneven thickness of the sheet obtained in productivity was evaluated. Uneven thickness: ◎ almost no uneven thickness, ○ slightly uneven thickness, × uneven thickness (9) Odor: cup container obtained by injection molding (100 m inner diameter)
m, depth 100 mm, thickness 1 mm) were placed in a glass container, sealed with aluminum foil, and heated at 60 ° C. for 3 hours. Thereafter, the aluminum foil was peeled off, and the odor was evaluated by a sensory test according to the following criteria. ◎ almost none, ○ slightly present, × unpleasant odor. (10) Brittleness of molded product: A 0.3 mm thick biaxially stretched sheet obtained by stretching the sheet obtained in (7) twice in the longitudinal direction and three times in the transverse direction was obtained. The biaxially stretched sheet was covered with a lid container (170) using a vacuum pressure air molding machine PK400 manufactured by Kansai Automatic Molding Machine Co., Ltd.
mm length × 120 mm width × 30 mm height).
Twenty lid containers were stacked and the edges were trimmed (punched). When this operation was performed 20 times (trimming was performed for 400 lid containers), the number of broken lid containers was counted. (11) Impact strength: Based on ASTM D256, a V-notch was formed in the test piece, and the test piece was hit with a hammer fixing the lower part of the notch, and the impact strength was determined from the energy required to break the test piece. Measuring device: Fully automatic impact tester manufactured by Toyo Seiki Co., Ltd. Test piece: 63.5 mm × 12.7 mm × 6.4 mm V notch: A 2.54 mm depth was inserted at a position 31.8 mm from one end of the test piece. (12) Heat resistance: Vicat softening point (JIS K-687)
15 kg load)

Example 1 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L and stirred. Next, 62 kg of styrene, 38 kg of methyl methacrylate and t
-Butyl peroxy-2-ethylhexanoate 180
g, 40 g of t-butyl peroxyacetate, and 200 g of α-methylstyrene dimer, and the temperature was raised to 95 ° C. to carry out polymerization for 6 hours. The conversion after polymerization at 95 ° C. for 6 hours was 98%. Further, the temperature was maintained at 130 ° C. for 6 hours to complete the polymerization. The beads obtained by polymerization were washed, dehydrated and dried, and then pelletized resin was obtained using an extruder. A biaxially stretched sheet having a thickness of 0.3 mm was obtained using the resin. Using the biaxially stretched sheet, a lid container (170 mm length × 120 mm width × 30 mm height) was obtained by a vacuum pressure forming method. In addition, cup container (inner diameter 100mm, depth 100mm, thickness 1mm) by injection molding
Also got. Table 1 shows the resin composition and the evaluation results.

Example 2 62 kg of styrene and methyl methacrylate 3 of Example 1
8 Kg, α-methylstyrene dimer 200 g, styrene 70 Kg, methyl methacrylate 30 Kg, α-methylstyrene dimer 50 g, and kept at 130 ° C. for 6 hours, and kept at 130 ° C. for 5 hours. . In addition, the conversion at the time of performing polymerization at 95 degreeC for 6 hours was 98%. Table 1 shows the resin composition and the evaluation results.

Example 3 62 kg of styrene and methyl methacrylate 3 of Example 1
The procedure was performed in the same manner as in Example 1 except that 8 kg, 200 g of α-methylstyrene dimer was changed to 77 kg of styrene, 23 kg of methyl methacrylate, and 400 g of α-methylstyrene dimer, and further maintained at 130 ° C. for 6 hours and at 130 ° C. for 4 hours. . In addition, the conversion at the time of performing polymerization at 95 degreeC for 6 hours was 98%. Table 1 shows the resin composition and the evaluation results.

Example 4 62 kg of styrene and methyl methacrylate 3 of Example 1
The procedure was performed in the same manner as in Example 1 except that 8 kg and 200 g of α-methylstyrene dimer were changed to 77 kg of styrene, 21 kg of methyl methacrylate, 2 kg of methacrylic acid, and 20 g of t-dodecylmercaptan. In addition, the conversion at the time of performing polymerization at 95 degreeC for 6 hours was 98%. Table 1 shows the resin composition and the evaluation results.

Example 5 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L and stirred. Next, 66 kg of styrene, 26 kg of methyl methacrylate, 4 kg of methacrylic acid, 180 g of t-butylperoxy-2-ethylhexanoate, 40 g of t-butylperoxyacetate, and 50 g of α-methylstyrene dimer were charged and heated to 95 ° C. For 6 hours. At this time, 4 Kg of methacrylic acid was further added over 2 hours from when the temperature reached 95 ° C. The conversion after polymerization at 95 ° C. for 6 hours was 98%. Further, the temperature was maintained at 130 ° C. for 6 hours to complete the polymerization. Other than that, it carried out similarly to Example 1. Table 1 shows the resin composition and the evaluation results.

Example 6 180 g of t-butylperoxy-2-ethylhexanoate and 200 g of α-methylstyrene dimer of Example 1
To t-butylperoxy-2-ethylhexanoate 1
The procedure was performed in the same manner as in Example 1 except that 50 g was added without α-methylstyrene dimer, and the temperature was raised to 95 ° C. for 6 hours, and the temperature was raised to 90 ° C. for 10 hours. Note that 9
When polymerization was carried out at 0 ° C. for 10 hours, the conversion was 99%. Table 1 shows the resin composition and the evaluation results.

Example 7 51 kg of styrene was placed in an autoclave having an inner volume of 230 L.
6 kg of a styrene-butadiene copolymer (styrene content: 40%, trade name: Asaprene 670A, manufactured by Asahi Kasei Corporation) is dissolved in a mixed monomer of 43 kg of methyl methacrylate, and 40 g of benzoyl peroxide and 600 g of α-methylstyrene dimer are added and stirred. Polymerization was carried out at 90 ° C. under the following conditions. When the total amount of the conversion of styrene and methyl methacrylate and the amount of the styrene-butadiene copolymer reached 45% by weight, the bulk polymerization was stopped to obtain a polymerization solution. Further, 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L, and the mixture was stirred. The polymerization solution and 200 g of dicumyl peroxide were added, and the mixture was heated at 100 ° C. for 2 hours at 115 ° C.
For 3.5 hours and at 130 ° C. for 2.5 hours to complete the suspension polymerization. After washing, dehydrating and drying the beads obtained by polymerization, a pellet-shaped rubbery polymer-containing copolymer was obtained using an extruder. Next, 5 parts by weight of the rubbery polymer-containing copolymer was mixed with 100 parts by weight of the styrene-based resin obtained in Example 1 using a Henschel mixer, to obtain a mixture of φ40.
The mixture was extruded while being melted and kneaded with a mm single screw extruder to obtain a styrene resin composition. Table 2 shows the evaluation results of the resin composition.

Example 8 51 g of styrene, 43 kg of methyl methacrylate, and a styrene-butadiene copolymer (styrene content 40%, manufactured by Asahi Kasei Corporation) at the time of production of the rubbery polymer-containing copolymer of Example 7
Performed in the same manner as in Example 7, except that 6 kg of trade name Asaprene 670A) was changed to 5 kg of styrene 40 kg, methyl methacrylate 55 kg, and styrene-butadiene copolymer (styrene content 25%, manufactured by Asahi Kasei Corporation, trade name Toughden 2000), respectively. A rubbery polymer-containing copolymer was obtained. Next, 40 parts by weight of the above-mentioned rubbery polymer-containing copolymer was mixed with 100 parts by weight of the styrene resin obtained in Example 1 using a Henschel mixer, and extruded while being melt-kneaded with a φ40 mm single screw extruder. A resin composition was obtained.
Table 2 shows the evaluation results of the resin composition.

Comparative Example 1 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L and stirred. Next, 100 kg of styrene, t-butyl peroxyacetate 8
0 g, 30 g of di-t-butyl peroxide,
The temperature was raised to 100 ° C., and polymerization was performed for 10 hours. In addition, 10
When polymerization was carried out at 0 ° C. for 10 hours, the conversion was 97%. The temperature was further maintained at 140 ° C. for 3 hours to complete the polymerization.
Other operations after polymerization were performed in the same manner as in Example 1. Table 2 shows the resin composition and the evaluation results. Table 3 shows that productivity and odor are poor.

Comparative Example 2 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L and stirred. Next, 50 kg of styrene, 25 kg of methyl methacrylate, 5 kg of methacrylic acid, 180 g of t-butyl peroxy-2-ethylhexanoate, 40 g of t-butyl peroxy acetate, and 150 g of t-dodecyl mercaptan were charged, and the temperature was raised to 95 ° C. Polymerization was performed for 10 hours. At this time, 20 kg of methacrylic acid was further added over 10 hours from when the temperature reached 95 ° C. The conversion after polymerization at 95 ° C. for 10 hours was 98%. 130 ° C
For 4 hours to complete the polymerization. Other operations after polymerization were performed in the same manner as in Example 1. Table 2 shows the resin composition and the evaluation results. Table 3 shows that productivity and odor are poor.

Comparative Example 3 62 kg of styrene and methyl methacrylate 3 of Example 1
8 kg, 200 g of α-methylstyrene dimer were converted into 70 kg of styrene, 30 kg of methyl methacrylate, and 1800 g of α-methylstyrene dimer.
Example 1 except that the time was kept at 125 ° C. for 3 hours.
The same was done. The conversion after polymerization at 125 ° C. for 3 hours was 98%. The styrene resin has a styrene monomer unit of 63% by weight, a (meth) acrylate monomer unit of 37% by weight, Mw of 50,000, and Mz / M.
w was 2.1, the total amount of the monomer was 4000 ppm, and the total amount of the styrene dimer was 2500 ppm. Next, the styrene resin obtained in Example 2 and the styrene resin were mixed in a Henschel mixer at a ratio of 15 parts by weight and 85 parts by weight, respectively, and extruded while being melt-kneaded with a φ40 mm single screw extruder to obtain a styrene resin. Obtained. Table 3 shows the resin composition and the evaluation results. Inferior in productivity and odor from Table 3,
It can be seen that the molded product is brittle.

Comparative Example 4 100 kg of pure water and 100 g of polyvinyl alcohol were added to an autoclave having an inner volume of 230 L and stirred. Next, 50 kg of styrene, 50 kg of methyl methacrylate, t-
120 g of butyl peroxyisobutyrate and 50 g of n-dodecyl mercaptan were charged, and the temperature was raised to 80 ° C. to carry out polymerization for 8 hours. The conversion after polymerization at 80 ° C. for 8 hours was 97%. Further, the temperature was kept at 100 ° C. for 2 hours to complete the polymerization. Other than that, it carried out similarly to Example 1. Table 3 shows the resin composition and the evaluation results. Table 3 shows that productivity and odor are poor.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

The styrenic resin of the present invention and the molded articles, sheets and biaxially stretched sheets using the resin are, as is clear from the comparison between the examples and the comparative examples, the productivity during molding and the appearance of the molded articles. And has excellent characteristics with little odor. Therefore, molded articles, sheets, biaxially stretched sheets, and the like using the resin are most suitable for food packaging containers such as microwave ovens. A styrene-based resin composition containing a rubber-like polymer in the styrene-based resin exhibits the same effect, and further has characteristics excellent in impact strength.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 220/10 C08F 220/10 4J015 220/14 220/14 4J100 C08J 5/18 CET C08J 5/18 CET C08L 25/14 C08L 25/14 33/06 33/06 // B29C 55/12 B29C 55/12 (C08L 25/14 21:00) B29K 25:00 33:04 B29L 7:00 22:00 F term (reference ) 3E035 AA06 BA05 BB03 BC02 BD06 BD10 4F071 AA10 AA22X AA32X AA33X AA81 AC08 AD06 AE06 AG02 AH05 BA01 BB08 BC01 BC04 4F210 AA13A AA13E AA21E AA45 AB01 AB16 AE01 AG01 ACO3 ACO3 JB14 JB22 JB26 NA25 NB04 NB06 4J015 BA05 BA07 BA08 BA10 BA11 EA10 4J100 AB02P AB03P AB04P AJ02R AJ08R AJ09R AK31R AK32R AL03Q AL04Q AM02R AM15R AM43R AM45R AM47R AM48R BC03R CA04 CA05 DA01 DA04 FA03 FA04 FA28 FA34 JA58

Claims (11)

[Claims] 1. A styrene monomer unit of 50 to 80% by weight, a (meth) acrylate monomer unit of 20 to 50%
% By weight, a copolymer comprising 0 to 20% by weight of other copolymerizable monomer units, wherein the total content of (1) unreacted monomers in the copolymer is 1000 ppm or less, And,
(2) A styrene-based resin characterized in that the total content of styrene dimer and styrene trimer is 1000 ppm or less, and (3) the sulfur content based on the sulfur-based chain transfer agent is 70 ppm or less. . 2. The method according to claim 1, wherein the styrene resin has an Mw (weight average molecular weight) of 100,000 to 450,000 and a ratio of Mz (Z average molecular weight) to Mw of 1.5 to 3.0. Item 4. The styrene resin according to Item 1. 3. The styrene resin according to claim 1, wherein the styrene monomer unit of the styrene resin is styrene and the (meth) acrylate monomer unit is methyl methacrylate. . 4. The styrene resin unit of the styrene resin is styrene, the (meth) acrylate monomer unit is methyl methacrylate, and the other copolymerizable monomer unit is methacrylic acid. 2. The method according to claim 1, wherein
Or the styrene resin according to 2. 5. The styrenic resin 1 according to claim 1, wherein
A styrenic resin composition comprising 10 parts by weight or less (but not including 0) of a rubbery polymer based on 00 parts by weight. 6. The styrenic resin composition according to claim 5, wherein the rubber particles composed of the rubbery polymer have a volume average particle diameter of 0.03 μm to 5.0 μm. 7. A styrene resin sheet comprising the styrene resin or the styrene resin composition according to claim 1. 8. A biaxially stretched styrene resin sheet obtained by biaxially stretching the styrene resin sheet according to claim 7. 9. A food packaging container obtained by subjecting the styrene-based resin sheet according to claim 7 to secondary molding. 10. A food packaging container obtained by injection molding the styrene resin or the styrene resin composition according to claim 1. 11. A total of 0.01 to 5 parts by weight of a polyfunctional organic peroxide or two or more monofunctional organic peroxides as a polymerization initiator is added to a total of 100 parts by weight of the monomers, and 5. A styrene-based copolymer according to claim 1, wherein after controlling the polymerization temperature until the conversion reaches 50% by weight or more to less than 110.degree. C., radical polymerization is performed by controlling the polymerization temperature to more than 125.degree. Method of manufacturing resin.