JP2529615B2 - Novel styrene resin and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel styrene resin and a method for producing the same.

More specifically, the present invention comprises a styrene-based structural unit in a specific ratio and a structural unit having a long-chain alkyl chain represented by a specific structural formula, and comprises a styrene-based monomer, a styrene-based dimer, and a styrene-based monomer. By limiting the content of the system trimer and the polymerization solvent to a certain amount or less, a tensile stress-having a yield point and a breaking point in a strain test, and relates to a styrene resin having excellent strength. .

The present invention also relates to a method for producing the above styrene resin with high productivity.

(Problems to be Solved by Conventional Techniques and Inventions) Styrenic resins have been widely used as molding materials for household products, electric appliances, etc. since they are excellent in transparency, moldability, and rigidity. It was Recently, there has been a trend toward switching from other high-quality resins to relatively low-cost resins due to soaring raw materials, and the demand for styrene-based resins is on the rise. At the same time, in order to expand the fields of use and increase the productivity of products, there is an increasing demand for improvements in the strength and moldability of styrene resins.

It is a well-known fact that the average molecular weight should be increased to obtain a styrene resin having high strength.
However, increasing the average molecular weight inevitably results in a decrease in moldability.

Although the use of a plasticizer to supplement the moldability is a known method, the addition of the plasticizer lowers heat resistance and rigidity, and also lowers strength. In some fields, high-speed molding is desired in order to increase the productivity of products, and it cannot be dealt with only by increasing the molecular weight and improving the strength and moldability by using a plasticizer.

On the other hand, in some fields such as the use of large-sized molded articles, moldability and strength are required to be stronger than heat resistance and rigidity. It is common knowledge to use a plasticizer, but when a plasticizer is added to a conventional styrene resin, the strength is greatly reduced, and it has not always satisfied the market demand. There is a demand for a styrenic resin having high strength and excellent moldability that can satisfy the market demand even if a plasticizer is added to cause a decrease in strength.

A molded product obtained by foam-molding a styrene-based resin is often used for food packaging, but a styrene-based resin having a wide molding width during thermoforming, that is, a styrene-based resin having good elongation is required.

Japanese Patent Publication No. 62-61231 discloses that it is effective to reduce the content of the low molecular weight polymer component as much as possible in order to improve the strength of the styrene resin. Further, a method for producing and containing a high molecular weight component using a polyfunctional low-temperature decomposable organic peroxide is disclosed in JP-A-60-83.
JP-A No. 04 and JP-A No. 60-13805 describe a method for producing a styrene-based resin having excellent strength by using a polyfunctional low-temperature decomposable organic peroxide.

However, although some improvement in strength can be expected by these methods, the original brittle fracture behavior of the styrene resin has not yet been changed.

That is, in the tensile stress-strain test, as shown by the pattern B in FIG. 1, the elongation changes linearly with respect to the tensile stress, and does not show a yield point and reaches fracture. This pattern does not change with increasing molecular weight.

As long as it has such a pattern, improvement in impact strength is insignificant.

For example, the area value under the tensile stress-strain curve, which is a measure of strength, does not change much and changes only about several percent.

Even if a polyfunctional low-temperature decomposable organic peroxide is used, unless an appropriate method is used to produce an appropriate styrene resin,
It cannot be expected that the strength of styrene resin will be significantly improved.

In the methods described in JP-A-60-8304 and JP-A-60-13805, unreacted styrene-based monomer is recovered in the recovery system because the polymerization temperature is low and the final polymerization rate is low. As a result of being exposed to a high temperature, a large amount of styrene-based dimers and styrene-based trimers are produced. Further, a large amount of low molecular weight polymer having a molecular weight of 20,000 or less is produced, and as a result, in the tensile stress-strain test, the yield point is not occupied and fracture occurs, and high strength improvement is not recognized.

Also in the method described in JP-A-60-152517, a polyfunctional low-temperature decomposable organic peroxide is used in the copolymerization reaction of styrene and α-methylstyrene, but the same polymerization as in the above-mentioned publication is used. As a result of adopting the conditions, the expected improvement effect was not obtained.

As described above, although various improvements have been made to conventional styrene resins, the brittle fracture behavior has not been changed.

It is a known fact to introduce a rubbery polymer as a method for changing this pattern. So-called high impact polystyrene. However, such resins are opaque and impair the transparency, which is the first characteristic of styrenic resins.

Further, a method of introducing a second monomer copolymerizable with a styrene-based monomer for improving strength and fluidity is known. For example, there are AS resin introduced with acrylonitrile, BAS resin introduced with butyl acrylate, and the like. While these resins have achieved their original goals, they have lost some of the characteristics of styrenic resins. That is, the AS resin has a markedly poor fluidity and a poor color tone. Also, the heat resistance of BAS resin is significantly reduced.

A characteristic feature of the copolymer resin having the second monomer introduced therein is that it has a drawback of impairing transparency when mixed with a styrene resin. Therefore, it cannot be used under the same conditions as styrene resins.

(Means for Solving the Problems) In view of the present situation, the present inventors have conducted extensive studies, and as a result, introduced a specific amount of a long-chain alkyl chain into a styrene-based polymer using an appropriate method, and By controlling the total amount of styrene-based monomer, styrene-based dimer, styrene-based trimer and polymerization solvent in the styrene-based resin to a certain amount or less, it is possible to significantly improve the tensile stress different from the conventional brittle fracture behavior- In the strain test, it was found that a novel styrene-based resin having a yield point and a break point and excellent in strength was obtained, and the present invention was completed.

That is, the present invention is: (In the formula, l and n are integers of 1 to 20, m is 0 or an integer of 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are each hydrogen or an alkyl group having 1 to 5 carbon atoms, It is a cyclohexyl group or a phenyl group.) (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an alkyl group having 1 to 5 carbon atoms), and the structural unit ratio SA / SB is 0.006 to 0.00001, A novel styrene-based resin having a weight-average molecular weight of 200,000 or more and 600,000 or less, and a total amount of styrene-based monomers, styrene-based dimers, styrene-based trimers and polymerization solvents of 0.8% by weight or less. Is. In the method for producing a styrene resin by bulk polymerization or solution polymerization of a styrene monomer, a general formula; (In the formula, l and n are integers of 1 to 20, m is 0 or an integer of 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen or an alkyl group having 1 to 5 carbon atoms, cyclohexyl. A low-temperature decomposable organic peroxide containing at least three repeating units represented by the formula: It is added at a ratio of 85 ° C to 125 ° C until the conversion of the styrenic monomer reaches at least 15% by weight. It is intended to provide a method for producing a styrene resin by obtaining a styrene resin by advancing the polymerization until the styrene resin concentration reaches 70% by weight or more.

Furthermore, in the latter-stage polymerization, the temperature showing a 10-hour half-life of 0.0002 to 0.006 parts by weight in terms of the amount of active oxygen per 100 parts by weight of all styrene-based monomers supplied to the reaction system is 80
℃ ~ 140 ℃ organic peroxide is added at one or more places, 1
It is also possible to use a method for producing a styrene-based resin in which the styrene-based resin is obtained by proceeding the polymerization at a temperature not exceeding 70 ° C until the styrene-based resin concentration in the reaction solution becomes 70% by weight or more.

Further, the present invention also provides a styrene-based resin excellent in moldability and strength, which contains 8 parts by weight or less of a plasticizer per 100 parts by weight of the styrene-based resin.

The present invention also provides a styrene-based resin molded body having excellent strength, which is obtained by molding a mixture of the styrene-based resin and the styrene-based resin.

As the styrene monomer of the present invention, styrene, α-
Methyl styrene, vinyl styrene, p-methyl styrene, etc. can be used. These styrenic monomers can be used alone or in combination.

Further, other vinyl-based monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, and maleic anhydride may be used in combination with the styrene-based monomer of the present invention.

The weight average molecular weight of the styrene resin of the present invention is in the range of 200,000 to 600,000 in consideration of the shape of the molded article, the purpose of use, etc.
More preferably, it is set in the area of 200,000 to 500,000.

When the weight average molecular weight is less than 200,000, the structural unit (A)
However, it is not preferable since the improvement of the strength is little even if the compound is introduced, and it is difficult to adjust the molecular weight during the production of the styrene resin. If the molecular weight exceeds 600,000, the productivity and moldability of the styrene resin will be significantly deteriorated, which is not practical.

The value of the structural unit ratio SA / SB must be in the range of 0.006 to 0.00001. More preferably, it is in the range of 0.003 to 0.00003.

When the value of the structural unit ratio SA / SB is less than 0.00001, the effect of improving strength is not exhibited. If it exceeds 0.006,
Rigidity and heat resistance decrease. Further, since the polymerization initiator used for introducing the structural unit (A) is expensive, the cost of the styrene resin is increased, which is not preferable.

The total amount of the styrene-based monomer, the styrene-based dimer, the styrene-based trimer, and the polymerization solvent needs to be 0.8% by weight or less. It is more preferably 0.75% by weight or less.

If the total amount of these exceeds 0.8% by weight, in the tensile stress-strain test, no yield point is shown and fracture occurs, and no improvement in strength is observed. Further, the total amount of the styrene-based monomer and the polymerization solvent is preferably 0.2% by weight or less. More preferred
0.1% by weight or less. When the total amount of these exceeds 0.2% by weight, the heat resistance of the styrene-based resin decreases, and during molding,
This is not preferable because it leads to reduction of defects such as mold and sweat. Also, it is not preferable from the viewpoint of food hygiene.

The molecular weight distribution of the styrene resin is not particularly limited, but the content of the styrene resin having a molecular weight of 20,000 or less is 5
It is preferable that the content be not more than weight%. It is more preferably at most 3% by weight. When the content of the styrene-based resin having a molecular weight of 20,000 or more exceeds 5% by weight, even if a long-chain alkyl chain is introduced, the yield point is not shown in the tensile stress-strain test and the material is easily broken. The content of styrene resin having a molecular weight of 2,000,000 or more is preferably 0.1% by weight or more. More preferably, it is 0.2% by weight or more. If it is less than 0.1% by weight, the degree of strength improvement is small.

Although the value of the molecular weight distribution of the styrene resin is not particularly limited, it is preferably 3.5 or less from the viewpoint of the ease of the method for producing the styrene resin, the moldability during molding, and the like.

Up to 8 parts by weight of plasticizer can be added to 100 parts by weight of styrene resin. It is more preferably 6% by weight or less. When the amount of the plasticizer exceeds 8 parts by weight, the heat resistance is remarkably reduced, which is not preferable. In addition, during molding, defects such as mold deposit and mold sweat are reduced, which is not preferable.

The plasticizer referred to in the present invention includes mineral oil, liquid paraffin, C8 to C22 higher fatty acids, C4 to C22 higher fatty acid metal salts (calcium, magnesium, zinc, etc.), ethylene bis fatty acid (C16, C18) amide, Higher fatty acid alcohols such as stearyl alcohol, dibutyl or dioctyl esters of adipic acid and sebacic acid, higher fatty acids (C8
To C22) mono-, di-, triglycerides, hydrogenated castor oil, hydrogenated beef tallow, dimethylpolysiloxane and the like.

In the present invention, examples of the structural unit (A) include those having the following structures.

Alternatively, it may have two or more constituent units of the above structural formula at random.

Further, examples of the structural unit (B) include those having the following structures.

In the method of the present invention, it is first necessary to carry out the first stage polymerization step in the presence of a specific low temperature decomposition type organic peroxide-based polymerization initiator. This low temperature decomposable organic peroxide contains at least 3, preferably 5 to 30 repeating units represented by the general formula (C). Examples of such an organic peroxide include those having the following repeating units.

A low temperature decomposable organic peroxide in which two or more structural units having the above structure are randomly bonded can also be used. In the present invention, the organic peroxides having these repeating units can be used alone or in combination of two or more.

These organic peroxides can be synthesized according to the methods described in JP-B-63-32089, JP-A-59-176320 and JP-A-59-93725.

The decomposition temperature showing the 10-hour half-life of these organic peroxides was determined by dissolving them in a solvent relatively inert to radicals, such as toluene and benzene, at a concentration of 0.1 mol / L, and subjecting this solution to nitrogen substitution. It can be determined according to the method described in JP-A-60-13805 by sealing in a glass tube and immersing in a constant temperature bath.

In the method of the present invention, it is preferable to use an organic peroxide having a 10-hour half-life temperature of 40 ° C to 90 ° C. If the temperature is lower than 40 ° C, there is a risk of explosion during storage and handling, and if the temperature is higher than 90 ° C, the polymerization takes a long time and the productivity is remarkably lowered.

In the present invention, it is preferable to use the low temperature decomposable organic peroxide in an amount of 0.00015 to 0.10 parts by weight in terms of the amount of active oxygen per 100 parts by weight of the styrene-based monomer. More preferably 0.
0006 to 0.05 parts by weight. The amount of active oxygen mentioned here is
Active oxygen (-) in the peroxide bond present in the organic peroxide
Means the amount of O-).

Polymerization in the method of the present invention, the bulk polymerization used in the polymerization of ordinary styrene-based resin, according to the solution polymerization, reacting a mixture of a raw material monomer with a polymerization initiator and optionally a solvent and other necessary additives. It can be carried out by supplying it to a machine and heating it while pressurizing and depressurizing it as necessary.

The first stage polymerization of the present invention is thus carried out at a temperature of 85 ° C.
It is necessary to carry out the polymerization at ˜125 ° C. until the conversion of the styrenic monomer reaches at least 15% by weight.
More preferably, it is carried out at 85 ° C to 120 ° C until the conversion rate of the styrenic monomer is at least 20% by weight.

At this stage, a styrene resin containing the repeating unit represented by the general formula (C) in the styrene resin chain is obtained. Also, a reaction solution containing an ultrahigh molecular weight styrene resin is produced.

The polymerization in the first stage is carried out until the conversion of the styrenic monomer is at least 15% by weight or more. More preferably, it is polymerized up to 20% by weight or more. If it is less than 15% by weight, the amount of the styrene resin having a peroxide bond in the styrene resin chain is small, and the content of the long-chain alkyl chain represented by the general formula (A) is very small, which is not preferable. . Also,
The amount of ultra-high molecular weight styrene resin produced is insufficient. As a result, a high strength resin cannot be obtained. When the amount of the low-temperature decomposable organic peroxide per 100 parts by weight of the styrene-based monomer exceeds 0.10 parts by weight in terms of the amount of active oxygen, it becomes difficult to control the reaction. In addition, the amount of ultra-high molecular weight styrene resin produced is insufficient, and as a result, the degree of improvement in strength is reduced.
In addition, since it is an expensive initiator, the cost of the styrene resin is increased, which is not preferable.

On the other hand, if it is less than 0.00015 parts by weight, the content of the long-chain alkyl chain represented by the general formula (A) becomes insufficient, and a styrene resin having excellent strength cannot be obtained. In addition, the time required for the polymerization becomes long and the productivity is lowered, which is not preferable.

On the other hand, when the polymerization temperature is lower than 85 ° C., it is advantageous for the production of the ultrahigh molecular weight styrene resin, but the reaction rate becomes remarkably slow and the productivity is lowered, which is not preferable.

Further, at a temperature exceeding 130 ° C., the amount of ultra-high molecular weight styrene-based resin produced is extremely reduced, the low-temperature decomposition type polymerization initiator is decomposed all at once, and the above-mentioned general formula (C) is added to the styrene-based resin chain. The content of the alkyl chain having a peroxide bond as shown is remarkably reduced, and as a result, the content of the structural unit (A) becomes insufficient, and a styrene resin having excellent strength cannot be obtained.

After the first-stage polymerization is performed in this manner, it is preferable to further advance the polymerization until the polymer concentration in the reaction solution is 40% by weight or more. More preferably, the polymerization is allowed to proceed to the range of 40% by weight to 55% by weight. The polymerization temperature at this time is not particularly limited, but is preferably in the range of 100 ° C to 140 ° C. At this time, a styrene-based monomer or a polymerization solution obtained by polymerization in another reactor may be added for polymerization. Also,
It is also possible to add a polymerization initiator and polymerize.

The polymerization temperature in the latter stage depends on the molecular weight of the styrene resin to be produced, but any styrene resin of any molecular weight must be polymerized at 170 ° C. or lower. More preferably, the polymerization is performed at 160 ° C or lower. Polymerization at a temperature above 170 ° C. produces a large amount of styrene-based dimers and styrene-based trimers and a large amount of low-molecular-weight styrene-based resins, and the effects of the present invention are not exhibited. When the target molecular weight cannot be adjusted only by the polymerization temperature, it is necessary to control it by the amount of the polymerization initiator to be added, the amount of the polymerization solvent or the amount of the molecular weight adjuster.

More preferably, the polymerization temperature is 130 ° C to 160 ° C. 130
At temperatures below ℃, the peroxide bonds containing long alkyl chains present in the styrene resin chain formed in the previous polymerization did not decompose and decomposed in the recovery system, resulting in the formation of long high molecular weight styrene resin. It is not preferable because the amount thereof is reduced and the introduction amount of the long-chain alkyl chain represented by the general formula (A) is reduced in the styrene resin chain.

The concentration of the styrene resin in the polymerization solution at the outlet of the final reactor must be 70% by weight or more, preferably 75% by weight or more. When the concentration of styrene resin is less than 70% by weight, a large amount of styrene dimer and styrene trimer are produced in the recovery system where the reaction solution is exposed to high temperature, and a large amount of low molecular weight styrene resin is produced. To generate. In addition, the general formula (A)
Sufficient amount of the repeating unit represented by does not enter the styrene resin chain, and as a result, a styrene resin having a yield point and a breaking point cannot be obtained in the tensile stress-strain test of the present invention.

When carrying out the polymerization in the latter stage, it is preferred to add the polymerization initiator at least at one or more points in the beginning or in the middle of the polymerization to proceed the polymerization.

The amount of the polymerization initiator is 0.0002 to 0.006 in terms of the amount of active oxygen per 100 parts by weight of all styrene-based monomers supplied to the reaction system.
The range is parts by weight. More preferably, it is in the range of 0.0005 to 0.005 parts by weight. When the amount of the polymerization initiator to be added is less than 0.0002 parts by weight, the productivity is greatly reduced, especially when a high molecular weight styrene resin is produced, which is not preferable. Also, 0.
When it exceeds 006 parts by weight, a large amount of low molecular weight styrene resin is produced, resulting in a decrease in strength. Moreover, since the concentration of the polymerization initiator is high, it is difficult to control the polymerization reaction, which is not preferable.

As a method for adding the polymerization initiator, the polymerization initiator may be added alone or may be dissolved in a styrene-based monomer, a polymerization solvent or the like and added.

As the type of polymerization initiator, a temperature with a half-life of 10 hours is 80
Organic peroxides in the range of ℃ to 140 ℃ are preferred. Typical of such organic peroxides are 2,2-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) octane, 1,1-bis (t -Butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 4,4-bis (t-butylperoxy) peroxy such as n-butylvalerate Ketals; 2,5-dimethyl-2,5-di (t-
Dialkyl peroxides such as butylperoxy) hexane-3; t-butylperoxyacetate, t-butylperoxy-3,3,5-trimethylhexanoate,
t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate Examples thereof include peroxyesters such as ## STR6 ##; ketone peroxides such as methylethylketone peroxide and cyclohexanone peroxide; and pidropoperoxides such as diisopropylbenzene hydroperoxide and p-methanehydroperoxide.

A polymerization initiator having a 10-hour half-life temperature of less than 80 ° C. is not preferable because a decomposition reaction occurs in a short time and the radical concentration is locally increased to form a low molecular weight styrene resin. Also, with a polymerization initiator having a 10-hour half-life temperature of over 140 ° C, it is not completely consumed in the reactor and remains in the recovery process exposed to high temperature, and low molecular weight styrene resin is generated in the recovery process. However, it is not preferable because the molecular chain is broken and the quality is deteriorated.

The polymerization solution discharged from the final reactor is sent to a recovery step used in a usual styrene-based resin bulk or solution polymerization method, devolatilized, and pelletized.

The polymerization of the present invention can be performed by either a batch polymerization method or a continuous polymerization method. The type of reactor used for the polymerization is not particularly limited. Especially in the case of the batch polymerization method, any reactor may be used as long as it has sufficient stirring power.

In the case of the continuous polymerization method, it is preferable to use the following reactor.

As the pre-stage polymerization reactor, a known reactor such as a complete mixing type reactor or a tubular reactor can be used. It is also possible to use a plurality of reactors arranged in parallel or in series.

As the second-stage polymerization reactor, a reactor that gives a flow rate pattern close to an extrusion flow is preferable. As such a reactor, a horizontal twin-screw reactor having a space, a reactor having a built-in static mixer, and a stirred tower reactor can be used. Alternatively, these reactors can be used in combination. In particular, it is preferable to use a reactor having a built-in static mixer or a horizontal twin-screw reactor as the final reactor. As such a reactor, HTR made by Hitachi, SM made by Sruzer
R and SMX built-in reactors can be used. If a reactor that gives a flow pattern close to perfect mixing characteristics is used, as the conversion rate of the styrene-based monomer increases, the mixing characteristics and heat removal capacity deteriorate, making it difficult to control the polymerization reaction. As a result, a large amount of low molecular weight styrene resin is produced, which is not preferable.

In addition, in the case of producing by a continuous polymerization method, when a polymerization initiator is added in the latter stage, it is preferable to use a static mixer as a mixer when mixing the polymerization solution and the polymerization initiator solution. As the static mixer, a Kenix type static mixer or a sruther type static mixer can be used. In a dynamic mixer, for example, a stirring blade type complete mixer, a shear stress due to stirring locally causes an overheated state to generate a low molecular weight styrene resin, or molecular chain breakage occurs, which is not preferable because of deterioration in quality. .

When the initiator is added in the middle of the horizontal biaxial reactor, it is sufficient to drop the polymerization initiator solution on the surface of the reaction solution because the mixing characteristics of the reactor itself are excellent.

The uniform mixing time is not particularly limited, but it is preferable to perform uniform mixing within 30 minutes. More preferably 15
Within minutes. It takes a long time for uniform mixing, so that a high concentration of the polymerization initiator is localized for a long time, a low molecular weight styrene resin is produced, the effect of the present invention is not exhibited, and strength is lowered, which is not preferable. .

The recovery device is also not particularly limited. What is generally used for the production of styrene resin can be used.

As the heat exchanger, a shell-and-tube type and a double tube type with a built-in static mixer are preferable. These heat exchangers can be mounted outside or inside the recovery device.

A falling-strand type recovery device can be preferably used. The recovery device can be used in a single stage or multiple stages.

The operating conditions of the heat exchanger are also not particularly limited, but the treatment is preferably carried out for a residence time of 15 minutes or less, more preferably 10 minutes or less. If the residence time is long, styrene-based dimers, styrene-based trimers, and low-molecular-weight styrene-based resins are likely to be formed, and it is difficult to expect strength improvement.

The temperature of styrene resin treatment in the recovery unit varies depending on the molecular weight of the styrene resin produced, but it is 200 ℃ -260 ℃,
It is more preferable to handle at 200 ° C to 250 ° C. 260
If the temperature exceeds ℃, styrene-based dimers, styrene-based trimers and low-molecular-weight styrene-based resins are formed, which is not preferable. In addition, the molecular chain is broken and the quality is deteriorated, which is not preferable. In the case of 200 ℃ or less, unreacted styrenic monomer,
It is not preferable because removal of the polymerization solvent becomes difficult. Also,
A method generally used for increasing the efficiency of removing the styrene-based monomer and the polymerization solvent, that is, a method of adding water, carbon dioxide gas or the like can also be used.

As another recovery device, a single-screw or twin-screw multi-stage vented extruder can be used. It is necessary to set, as the operation condition, a condition that does not deteriorate the quality.

The polymerization solvent is not particularly limited, but toluene, xylene, ethylbenzene and the like can be preferably used.

At any stage before or after recovering the unreacted styrene-based monomer and / or solvent, additives commonly used in styrene-based resins, such as antioxidants, lubricants, plasticizers, colorants, etc., are added. You can also

The styrene resin of the present invention, as an antioxidant, hindered phenols, hindered bisphenols,
Hindered trisphenols, etc., such as 2,6-di-
t-butyl-4-methylphenol, stearyl-β-
(3,5-di-t-hydroxyphenyl) propionate and the like; phosphorus compounds such as tris (2,4-di-t-butylphenyl) phosphite, 4,4'-butylidene-bis- (3-methyl) -6-t-Butyl-phenyl-di-tridecyl) phosphite and the like can be added.

It is also possible to use the styrene resin of the present invention in combination with another styrene resin.

The styrene resin of the present invention can be molded into various molded products by known methods generally used for molding thermoplastic resins, for example, molding methods such as injection molding, vacuum molding, extrusion molding and compression molding. Can be done.

Further, after being formed into a film, a biaxially stretched film, a sheet, a foam sheet, foam beads, etc., it can be formed into a desired molded body.

Further, in order to improve the surface properties of the obtained styrenic resin molded product, particularly a film, sheet, foam or the like, an antistatic agent or a lubricant such as silicone may be applied on the surface.

There is no particular limitation on the shape of the molded body, but for example VT
R cassette tape case window, audio cassette tape half, case, window, copier paper storage box, paper storage box cover, copy paper tray, beverage cup, fishbowl, bird cage, office equipment storage tray, floppy disk It can be suitably used for a storage case, a compact disc case, toys, tableware, a cup, a ballpoint pen, a tableware storage case, a medical petri dish, a food storage foam tray, and the like.

In the present invention, the weight average molecular weight of the styrene resin is measured by GPC according to the GPC method, GPC (HLC-802A) manufactured by Toyo Soda Industry Co., Ltd., GP manufactured by the same company.
Measure using a C column (two TSK-GEL-GMH6 are used).

The content of styrene resin in each molecular weight region is calculated by the area ratio.

The styrene-based monomer, styrene-based dimer, styrene-based trimer, and polymerization solvent are measured by gas chromatography.

The conversion rate of styrene-based monomer and the concentration of styrene-based resin in the reaction solution are 200 ℃, 5mm after precisely measuring a certain amount of reaction solution.
After drying for 30 minutes under a vacuum of Hg, the amount of residual styrene resin is precisely weighed.

The value of the structural unit ratio SA / SB is quantified by the following method.

After dissolving the styrene resin in 10 times the amount of methyl ethyl ketone, the same amount of methanol is slowly added to precipitate the styrene resin. The deposited styrene resin is 200
Dry under reduced pressure of 5 mmHg for 30 minutes. Using dried styrene resin, JNM-GX400 FT manufactured by JEOL Ltd.
13C is measured using NMR. Measurement and calculation are performed under the measurement conditions described below.

Pulse width = 9.2 μs; 45 ° pulse Data point = 32768 Repetition time = 2.0 seconds AD converter = 16 bits Accumulation count = 30,000 to 100,000 times Sample concentration = 20 Wt% Solvent = 1,1,2,2-tetrachloroethane- (d2 ) Sample tube = 10 mm Measurement temperature = 120 ° C A peak derived from the carbon of the methylene group of the long-chain alkyl chain appears at 29.4 ppm.

On the other hand, peaks derived from the methine group and methylene group of the structural unit (B) appear at 39 to 50 ppm.

Let SB be the value of the total area of the peaks appearing at 39 ppm to 50 ppm derived from the structural unit (B). Let SA be the value of the area of the peak appearing at 29.4 ppm derived from the structural unit (A). The value of SA / SB is calculated from these values.

Hereinafter, the present invention will be specifically described with reference to Examples. The invention is not limited by these examples.

 In addition, the physical-property test method in an Example is described below.

(A) Melt flow rate: According to ISO R1133.

(B) Vicat softening point: According to ASTM D1525.

(C) Tensile strength: A test piece is molded at a molding temperature of 220 ° C and an injection pressure of SSP + 5 kg / cm ² , and is allowed to stand in a thermostatic chamber at 23 ° C for 24 hours and then according to ASTM D638.

(D) Tensile stress-strain curve pattern: Judgment was made from the chart during tensile strength measurement.

(E) Area under tensile stress-strain curve: Using Shimadzu autograph AG-5000A, ASTM
Measure according to the method of D638 and calculate with the attached computer processor.

(F) Repeated impact strength: Molding temperature = 220 ° C, molding pressure = SSP + 5 kg / cm ² , mold temperature = 60 ° C, 5 cm x 8.8 cm x 2 mm test piece was injection molded to give 6.35.
R, 150 g missile is dropped from the height of about 10 cm to the center of the test piece, and the number of times until cracking is found.

In addition, the height is finely adjusted so that the value of the repeated impact strength is 58 to 60, using a conventional polystyrene having a weight average molecular weight of 320,000 (Styron 693 manufactured by Asahi Kasei Co., Ltd.) as a standard sample.

(G) Dart impact strength of the gate of the beverage cup: A 2 cm x 2 cm square test piece is cut out from the molded beverage cup with the gate centered, and this test piece is fixed and a 40 g missile is attached. Drop and determine the height at which 50% destruction occurs, and then determine the impact strength.

(H) Beverage cup mouth compression strength: Using a tensile tester, the beverage cup mouth is bent at a speed of 50 mm / min. Calculate the stress when the mouth is broken.

(Example) (Example-1) Polystyrene was polymerized by the apparatus shown in the attached FIG.

The first-stage polymerization reactors-1, 2 ... Are perfect mixing type reactors, each having a capacity of 30, and the reaction solution capacity can be changed within a range of 5-25.

The second-stage polymerization reactors -1, -2 are tubular polymerization reactors each having a built-in static mixer, and each has a capacity of 20.
In order to mix the polymerization solution and the polymerization initiator, static mixers-1 and-2 were installed at the inlet of the second-stage polymerization reactor-1 and the inlet of the second-stage polymerization reactor-2, respectively. Its capacity is 1 each. First-stage polymerization reactor-1, -2, second-stage polymerization reactor-2,
And, gear pumps 1 to 5 were installed at the outlet of the recovery system.
Further, a pump-5 for supplying the additive to the supply side of the gear pump and piping were installed at the outlet of the latter-stage polymerization reactor-2.

Styrene 99.85 parts by weight and formula The raw material solution consisting of 0.15 parts by weight of a low-temperature decomposable organic peroxide containing 7 repeating units (10-hour half-life temperature 64.4 ° C, active oxygen amount 0.04g / 1g) at a flow rate of 4.547Kg / hr It is continuously supplied to the polymerization reactor-1, the liquid amount is controlled so that the residence time in the reactor is 5 hours, and the polymerization is carried out at a temperature of 105 ° C.

Styrene 85.034 parts by weight, ethylbenzene 14.941 parts by weight, 1,1-bis (t-butylperoxy) cyclohexane (10-hour half-life temperature 91 ° C, active oxygen content 8.62%) 0.025
A raw material solution consisting of parts by weight is continuously supplied to the pre-stage polymerization reactor-2 at a flow rate of 4.551 Kg / hr, the liquid amount is controlled so that the residence time in the reactor is 5 hours, and the temperature is 120 ° C. Polymerize with. The conversion rate of styrene in the first-stage reactor-1 is 28.
% By weight, and the concentration of styrene resin in the polymerization solution in the first stage polymerization reactor-2 is 48% by weight.

The polymerization solutions discharged from the first-stage polymerization reactors-1, 2 and are mixed and introduced into static mixers -1 and 2. A 1% by weight solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene is continuously supplied to the mixed polymerization solution at a flow rate of 90 g / hr. The polymerization solution uniformly mixed in the static mixer is supplied to the second-stage polymerization reactor-1. In the second-stage polymerization reactor-1, polymerization is carried out at a temperature of 130 ° C. In the second-stage polymerization reactor-2, polymerization is carried out at a temperature of 155 ° C. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor-2 was 76% by weight.

The polymerization solution discharged from the second-stage polymerization reactor-2 is guided to a preheater. The preheater has a built-in static mixer and a capacity of about 0.8. 24 after being heated to 240 ° C in the preheater
It is introduced into a recovery device kept at 0 ° C, devolatilized under a vacuum of 10 mmHg, and pelletized.

The product is sampled 48 hours after the start of polymerization and the physical properties are evaluated. The results of physical property evaluation are shown in (Table 2).

(Example-2) The first-stage polymerization was carried out under the same conditions as in Example-1, except that the amount supplied to the first-stage polymerization reactor-1 was 2.273 kg / hr and the residence time was 6 hours. The conversion rate of styrene in the first-stage polymerization reactor-1 was 31% by weight. Static mixer-1,-
A 1% by weight solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene is continuously supplied to the inlets of 2 and 1-2 at a flow rate of 40 g / hr. In the latter-stage polymerization reactor-1, 135 ° C, in the latter-stage polymerization reactor-2, 155
Polymerizes at a temperature of ° C. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor-2 was 81% by weight.

The styrene resin is obtained from the polymerization solution by operating under the same conditions as in Example-1, and the physical properties are evaluated. The results (Table-2)
Shown in

(Example-3) The amount of the raw material solution supplied to the first-stage polymerization reactors-1, -2, ... was half that in Example-2, and the polymerization initiator was not added to the static mixer. Other than that, the styrene resin is obtained by operating under the same conditions as in Example-2. At this time, the conversion rate of styrene in the first-stage polymerization reactor-1 was 31% by weight, and the styrene resin concentration in the weight solution discharged from the second-stage polymerization reactor-2 was 76% by weight. The results of physical property evaluation are shown in (Table 2).

(Example-4) Styrene 99.956 parts by weight and formula A low temperature decomposition type organic peroxide containing 7 repeating units (10 hours half-life temperature 64.4 ℃, active oxygen amount 0.04g / 1g) 0.044 parts by weight of raw material solution at a flow rate of 2.271Kg / hr It is continuously supplied to the reactor-1, the liquid amount is controlled so that the residence time in the reactor is 8 hours, and the polymerization is carried out at a temperature of 105 ° C. Polymerize.

The conversion rate of styrene in the first-stage polymerization reactor-1 is 22% by weight.

In the second-stage polymerization, the polymerization is conducted under the same conditions as in Example-2 except that the polymerization temperature of the second-stage polymerization reactor-1 is 130 ° C. The styrene resin concentration in the polymerization solution discharged from the second-stage polymerization reactor-2 was 77% by weight. By operating under the same conditions as in Example-1, a styrene resin is obtained from the polymerization solution.

 The results of physical property evaluation are shown in (Table 2).

(Example-5) A 50 wt% ethylbenzene solution of a styrene dimer / styrene trimer mixture was continuously supplied to the polymerization solution discharged from the second-stage polymerization reactor-2 at a flow rate of 25 g / hr. A styrene resin is obtained by operating under the same conditions as in Example-4. The results of physical property evaluation are shown in (Table 2).

As the styrene dimer and styrene trimer mixture, methanol was added to the polymerization solution discharged from the second-stage polymerization reactor-2, and a solution obtained by removing the precipitated polymer by distillation separation and purification was used.

(Example-6) The low-temperature decomposable organic peroxide supplied to the first-stage polymerization reactor-1 was a repeating unit represented by the following formula (repeating unit was 7, 10-hour half-life temperature 65 ° C, active oxygen Amount 0.04g /
A styrene resin is obtained in the same manner as in Example 2 except that the amount is 1 g).

The results of physical property evaluation are shown in (Table 2). First-stage polymerization reactor-
The conversion rate of styrene at 1 is 31% by weight. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor-2 was 81% by weight.

(Example-7) The low temperature decomposable organic peroxide supplied to the first-stage polymerization reactor-1 is a repeating unit represented by the following formula (the repeating unit is 7, the 10-hour half-life temperature is 64 ° C, and the amount of active oxygen is 0.04g / 1
A styrene resin is obtained by the same operation as in Example 2 except that the above is g).

The physical property measurement results are shown in (Table 2). The conversion rate of styrene in the first-stage polymerization reactor-1 is 30% by weight. The styrene resin concentration in the polymerization solution discharged from the second-stage polymerization reactor-2 was 80% by weight.

When Is a repeating unit that is randomly combined at a ratio of 93/7.

(Example-8) Styrene 99.85 parts by weight and formula Low-temperature decomposable organic peroxide containing 7 repeating units shown in (10-hour half-life temperature 64.4 ℃, active oxygen amount 0.04g / 1g)
A raw material solution consisting of 0.15 parts by weight was continuously supplied to the pre-stage polymerization reactor-1 at a flow rate of 2.273 Kg / hr, and the liquid amount was controlled so that the residence time in the reactor was 8 hours, and the temperature was 100 ° C. Polymerize with.

95.13 parts by weight of styrene, 4.84 parts by weight of ethylbenzene,
1,1-bis (t-butylperoxy) cyclohexane (1
0 hour half-life temperature 91 ℃, active oxygen content 8.62%) 0.022 parts by weight of raw material solution was continuously supplied to the pre-stage polymerization reactor-2 at a flow rate of 4.541 Kg / hr, and the residence time in the reactor was increased. 5
The liquid volume is controlled so that the time is reached, and the polymerization is carried out at a temperature of 115 ° C. The conversion rate of styrene in the first-stage reactor-1 was 24% by weight, and the styrene resin concentration in the polymerization solution in the first-stage polymerization reactor-2 was 47% by weight.

The polymerization solution is introduced into the latter-stage polymerization machine. A 1 wt% solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene is continuously fed to each of the static mixers -1, -2 and -1 and 2 at a flow rate of 40 g / hr. In the second-stage polymerization reactor-1, polymerization is carried out at a temperature of 130 ° C. In the second-stage polymerization reactor-2, polymerization is carried out at a temperature of 140 ° C. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor-2 was 78% by weight. 250 ℃ after being heated to 250 ℃ in the preheater
It is led to a recovery device that is kept warm, devolatilized under a vacuum of 10 mmHg, and pelletized.

 The physical property measurement results are shown in (Table 2).

(Example-9) The flow rates of the polymerization initiator solutions supplied to the static mixers-1, -2, -1 and -2 were 50 g / hr, respectively, and the pre-stage polymerization reactor-
2, the polymerization temperature at 120 ℃, the second-stage polymerization reactor-2,
A styrene resin is obtained by operating under the same conditions as in Example-8, except that the polymerization temperature is 135 ° C.

The styrene resin concentration in the polymerization solution in the first-stage polymerization reactor-2 was 52% by weight, and the styrene resin concentration in the polymerization solution discharged from the second-stage polymerization reactor-2 was 82% by weight.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-1) In the latter-stage polymerization, static mixers-1, -2, -1
No polymerization initiator solution was added to ~ 2, and the latter-stage polymerization reactor-
A styrene resin is obtained by operating under the same conditions as in Example-2, except that the polymerization temperature of 1 is 130 ° C and the polymerization temperature of the second-stage polymerization reactor-2 is 150 ° C.

The styrene resin concentration in the polymerization solution discharged from the second-stage polymerization reactor-2 was 63% by weight.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-2) A 50 wt% ethylbenzene solution of a mixture of styrene dimer and trimer was added to the polymerization solution discharged from the second-stage polymerization reactor-2.
A styrene resin is obtained by operating under the same conditions as in Example-5 except that the flow rate is 40 g / hr.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-3) A 50 wt% ethylbenzene solution of a mixture of styrene dimer and trimer was added to the polymerization solution discharged from the second-stage polymerization reactor-2.
A styrene resin is obtained by operating under the same conditions as in Example-5 except that the gas is continuously fed at a flow rate of 65 g / hr.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-4) A 50 wt% ethylbenzene solution of a styrene dimer and trimer mixture was added to the polymerization solution discharged from the second-stage polymerization reactor-2.
A styrene resin is obtained by operating under the same conditions as in Example-5 except that the gas is continuously fed at a flow rate of 80 g / hr.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-5) 86.57 parts by weight of styrene, 13.40 parts by weight of ethylbenzene,
1,1-bis (t-butylperoxy) cyclohexane (1
0 hour half-life temperature 91 ℃, active oxygen amount 8.62%) 0.030 parts by weight of raw material solution is continuously supplied to the pre-stage polymerization reactor-1, pre-stage polymerization reactor-2, at a flow rate of 3.581 Kg / Hr. ,
The liquid amount is controlled so that the residence time in the reactor is 5 hours, and the polymerization is carried out at a temperature of 115 ° C. Front-stage reactor-1,-
The concentration of styrene resin in the polymerization solution in 2 and 4 is 44% by weight.

The polymerization solution is introduced into the latter-stage polymerization machine. Static mixer-1,
A 1% by weight solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene was continuously fed to each of -2 and -1 at a flow rate of 40 g / hr. Second-stage polymerization reactor-
In 1, the polymerization is carried out at a temperature of 130 ° C. Second-stage polymerization reactor-
In 2, polymerization is carried out at a temperature of 155 ° C. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor was 78% by weight.
After being heated to 240 ° C by a preheater, it is introduced into a recovery device kept at 240 ° C, devolatilized under a vacuum of 10 mmHg, and pelletized.

 The physical property measurement results are shown in (Table 2).

(Comparative Example-6) Styrene 99.85 parts by weight and formula Low-temperature decomposable organic peroxide containing 7 repeating units shown in (10-hour half-life temperature 64.4 ℃, active oxygen amount 0.04g / 1g)
The raw material solution consisting of 0.15 parts by weight was continuously supplied to the pre-stage weight reactor-1 at a flow rate of 2.273 Kg / hr, and the liquid amount was controlled so that the residence time in the reactor was 8 hours, Polymerize at temperature.

Styrene 89.984 parts by weight, ethylbenzene 10.00 parts by weight, 1,1-bis (t-butylperoxy) cyclohexane (10-hour half-life temperature 91 ° C, active oxygen content 8.62%) 0.020
A raw material solution consisting of parts by weight is continuously supplied to the pre-stage polymerization reactor-2 at a flow rate of 4.501 Kg / hr, the liquid amount is controlled so that the residence time in the reactor is 5 hours, and the temperature is 120 ° C. Polymerize with. The conversion rate of styrene in the first-stage reactor-1 is 24
% By weight, and the concentration of styrene resin in the polymerization solution in the first stage polymerization reactor-2 is 51% by weight.

The polymerization solutions discharged from the first-stage polymerization reactors-1, 2 and are mixed and introduced into a static mixer. A 1% by weight solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene is continuously supplied to the mixed polymerization solution at a flow rate of 40 g / hr. The polymerization solution uniformly mixed in the static mixer is supplied to the second-stage polymerization reactor-1. In the second-stage polymerization reactor-1, polymerization is carried out at a temperature of 130 ° C. Polymerization is carried out at a temperature of 180 ° C. in the second-stage polymerization reactor-2.

The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor-2 was 82% by weight.

A recovery device is operated under the same conditions as in Example-1 to obtain a styrene resin.

 The physical property evaluation results are shown in (Table 2).

(Comparative Example-7) Styrene 99.85 parts by weight and formula The low temperature decomposition type organic peroxide containing 7 repeating units (10 hours half-life temperature 64.4 ℃, active oxygen amount 0.04g / 1g) 0.006 parts by weight of raw material solution at a flow rate of 2.271Kg / hr It is continuously supplied to the reactor-1, and the residence time in the reactor is
The liquid volume is controlled so that the time is 10 hours, and the polymerization is carried out at a temperature of 107 ° C.

A raw material solution consisting of 86.034 parts by weight of styrene, 13.941 parts by weight of ethylbenzene, and 0.025 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane is continuously supplied to the pre-stage polymerization reactor-2 at a flow rate of 4.551 Kg / hr. Then, the liquid amount is controlled so that the residence time in the reactor is 5 hours, and the polymerization is carried out at a temperature of 118 ° C. The conversion rate of styrene in the first-stage reactor-1 is 21% by weight, and the styrene resin concentration in the polymerization solution in the first-stage polymerization reactor-2 is 51% by weight.

In the second-stage polymerization, the styrene resin was operated under the same conditions as in Comparative Example 5 except that the temperature of the second-stage polymerization reactor-1 was 135 ° C and the temperature of the second-stage polymerization reactor-2 was 150 ° C. To get

The styrene resin concentration in the polymerization solution discharged from the second-stage polymerization reactor-2 was 75% by weight.

 The physical property evaluation results are shown in (Table 2).

(Comparative example-8) 94.43 parts by weight of styrene, 5.55 parts by weight of ethylbenzene,
1,1-bis (t-butylperoxy) cyclohexane (1
0 hour half-life temperature 91 ° C, active oxygen amount 8.62%) A raw material solution consisting of 0.020 parts by weight was continuously supplied to the pre-stage polymerization reactor-1 and the pre-stage polymerization reactor-2 at a flow rate of 3.601 Kg / Hr. ,
The liquid amount is controlled so that the residence time in the reactor is 6 hours, and the polymerization is carried out at a temperature of 105 ° C. Front-stage reactor-1,-
The styrene resin concentration in the polymerization solution in Nos. 2 and 43 is 43% by weight.

The polymerization solution is introduced into the latter-stage polymerization machine. Static mixer-1,
A 1% by weight solution of 1,1-bis (t-butylperoxy) cyclohexane in ethylbenzene was continuously fed to each of -2 and -1 at a flow rate of 40 g / hr. Second-stage polymerization reactor-
In 1, the polymerization is carried out at a temperature of 130 ° C. Second-stage polymerization reactor-
In 2, polymerization is carried out at a temperature of 140 ° C. The concentration of styrene resin in the polymerization solution discharged from the second-stage polymerization reactor was 76% by weight.
After being heated to 250 ° C by a preheater, it is introduced to a recovery device kept at 250 ° C, devolatilized under a vacuum of 10 mmHg, and pelletized.

 The physical property measurement results are shown in (Table 2).

(Comparative Example-9) The temperature of the first-stage polymerization reactor-2 was 115 ° C, the polymerization initiator solution was not added in the second-stage polymerization, and the polymerization temperature of the second-stage polymerization reactor-2 was 145 ° C. Other than the examples-
A styrene resin is obtained by operating under the same conditions as in No. 9.

The styrene conversion rate in the first-stage polymerization reactor-2 was 24% by weight, and the styrene resin concentration in the polymerization solution in the first-stage polymerization reactor-2 was 47% by weight. Second-stage polymerization reactor-
The concentration of styrene resin in the polymerization solution from step 2 was 62% by weight.
Is.

 The physical property evaluation results are shown in (Table 2).

The relationship between the amount of low molecular weight substances (styrene, styrene dimer, styrene trimer, polymerization solvent) and the area value under the stress-strain curve is shown in FIG. It can be seen from this figure that the specific long-chain alkyl chain of the present invention has a low molecular weight substance content of 0.8% by weight.
The styrene resin which is below has a low molecular weight substance content of 0.8.
The energy required to break the test piece (area value under the stress-strain curve) is higher than that in the case where the content exceeds 50% by weight or does not contain a long alkyl chain but the amount is small. You can see that

Further, from (Table-2), the repeated impact strength also contains a specific long-chain alkyl chain, and the low molecular weight substance content is 0.
It can be seen that the styrene resin content of 8% by weight or less is high.

Furthermore, it can be seen from Table 2 that physical properties other than strength, fluidity, and rigidity do not change.

The styrene resin of the present invention has the same fluidity and rigidity as the conventional styrene resin, and has significantly improved strength.

It can be seen from Table 1 that the styrene resin of the present invention is optimally produced by using the polymerization method of the present invention.

When the polymerization temperature in the latter stage is 180 ° C (Table-1, Comparative Example-
In 6), a large amount of a low molecular weight substance is generated and a large amount of a low molecular weight styrene resin is generated, and the styrene resin of the present invention cannot be obtained.

When the styrene resin concentration in the reaction solution exiting the final reactor is less than 68% by weight (Table-1, Comparative Examples-1, 9)
However, it is understood that a large amount of low molecular weight substances are produced.

In the latter-stage polymerization, the styrene resin of the present invention can be obtained without using a polymerization initiator, but it is understood that the styrene resin of the present invention can be obtained with higher productivity by using an appropriate amount of the polymerization initiator.

(Example-10) Except that mineral oil (Sulyl PS-260) was continuously fed at a flow rate of 120 g / hr to the polymerization solution discharged from the latter-stage polymerization reactor, the same operation as in Example-6 was carried out. , Styrene resin is obtained.

 The results of physical property evaluation are shown in (Table 3).

(Example-11) A styrene resin is obtained by operating under the same conditions as in Example-10 except that the supply amount of mineral oil is 250 g / hr.

 The results of physical property evaluation are shown in (Table 3).

(Example-12) A styrene resin is obtained by operating under the same conditions as in Example-10 except that the supply amount of mineral oil is 350 g / hr.

 The results of physical property evaluation are shown in (Table 3).

(Comparative Example-10) Except that mineral oil (Sulyl PS-260) was continuously supplied at a flow rate of 130 g / hr to the polymerization solution discharged from the second-stage polymerization reactor, the same operation as in Example-8 was carried out. , Styrene resin is obtained.

 The results of physical property evaluation are shown in (Table 3).

(Comparative Example-11) A styrene resin is obtained by operating under the same conditions as in Comparative Example-10, except that the supply amount of mineral oil is 250 g / hr.

 The results of physical property evaluation are shown in (Table 3).

(Comparative Example-12) A styrene resin is obtained by operating under the same conditions as in Comparative Example-10 except that the supply amount of mineral oil is 350 g / hr.

 The results of physical property evaluation are shown in (Table 3).

 The relationship between fluidity and repeated impact strength is shown in FIG.

A styrene resin containing a specific long-chain alkyl chain of the present invention and having a low molecular weight content of 0.8% by weight or less has a decrease in strength as mineral oil is added, but a fluidity-strength balance is a comparative example. It can be seen that the styrene resin is significantly improved. The change in heat resistance due to the addition of mineral oil is the same as that of the styrene resin of the comparative example.

(Example-13) Using an injection molding machine Neomat 350 / 120BX (manufactured by Sumitomo Heavy Industries, Ltd.), a cylinder temperature of 250 ° C and an injection pressure of 9
The styrene resin obtained in Example-2 is injection-molded under the conditions of 0 kg / cm ² and a mold temperature of 45 ° C. to mold a beverage cup.

The results of examining the impact strength of the gate portion of the beverage cup are shown in (Table 4).

(Example-14) An experiment similar to that of Example-13 is performed using the styrene resin obtained in Example-3. The results are shown in (Table 4).

(Comparative Example-13) The same experiment as in Example-13 is performed using the styrene resin obtained in Comparative Example-1. The results are shown in (Table 4).

(Comparative Example-14) The same experiment as in Example-13 is performed using the styrene resin obtained in Comparative Example-2. The results are shown in (Table 4).

(Example-15) Using an injection molding machine Saicap 480/150 (manufactured by Sumitomo Heavy Industries, Ltd.), a cylinder temperature of 260 ° C and an injection pressure of 1
The styrene resin obtained in Example-6 is injection-molded under the conditions of 00 kg / cm ² and a mold temperature of 45 ° C. to mold a beverage cup.

The strength of the mouth of the beverage cup was examined, and the results are shown in (Table-5).

(Example-16) An experiment similar to that of Example-15 is conducted using the styrene resin obtained in Example-7. The results are shown in (Table-5).

(Comparative Example-15) An experiment similar to that of Example-15 is performed using the styrene resin obtained in Comparative Example-8. The results are shown in (Table-5).

(Comparative Example-16) An experiment similar to that of Example-15 is performed using the styrene resin obtained in Comparative Example-9. The results are shown in (Table-5).

By using a styrene resin having a specific long-chain alkyl chain of the present invention and a low molecular weight substance content of 0.8% by weight or less, the strength of the molded product, particularly the impact of the gate part of a container such as a beverage cup. The molded product has excellent practical strength, such as excellent strength and mouth strength.

(Effects of the Invention) As described above, the styrene-based resin of the present invention comprises a specific ratio of styrene-based structural units and structural units having a long alkyl chain represented by a specific structural formula, and Since the content is limited to a small amount of a certain value or less, the styrene-based resin itself inherently retains the properties such as fluidity and rigidity, which are shown by excellent brittle fracture behavior, high repeated impact strength, etc. Provided is a novel styrenic resin having a significantly improved strength.

In the production of the styrene-based resin of the present invention, a multifunctional low-temperature decomposable organic peroxide is used as a polymerization initiator, and the amount of the organic peroxide added and the polymerization conditions such as the polymerization temperature are controlled in a stepwise manner. By advancing the polymerization reaction, a new and useful styrene resin can be optimally produced.

Further, since the novel styrene resin of the present invention has the above-mentioned excellent properties, it is required to be used in applications requiring strength of molded articles, for example, practical strength such as gates and mouths of containers such as beverage cups. It can be used suitably for the purpose.

[Brief description of drawings]

FIG. 1 is a pattern diagram showing stress-strain curves of Examples of the present application and Comparative Examples. FIG. 2 is a diagram showing the relationship between the amount of low molecular weight substances and the area value under the stress-strain curve. FIG. 3 is a relationship diagram between the repeated impact strength and the fluidity of the example of the present application and the comparative example. FIG. 4 is an apparatus diagram in which the example of the present application and the comparative example are performed. …… Pre-stage polymerization reactor-1 (complete mixing type reactor) …… Pre-stage polymerization reactor-2 (complete mixing type reactor) …… Post-stage polymerization reactor-1 (built-in static mixer) …… Post-stage polymerization reaction Machine-2 (Built-in static mixer) ...... Devolatization tank -1, -2 ...... Raw material solution feed pump -3, -4 ...... Polymerization initiator solution Fido pump -5 ...... Additive solution feed pump -1, -2, -3 ... Polymerization solution transfer pump -4 ... Molten resin transfer pump -1, -2 ... Static mixer ... Preheater (with static mixer) ... Vacuum line ... Molten resin transfer line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 1 -166969 (32) Priority date Hei 1 (1989) June 30 (33) Priority claiming country Japan (JP) (31) Priority Claim number Japanese patent application No. 1 -198032 (32) Priority date No. 1 (1989) August 1 (33) Country of priority claim Japan (JP) (31) No. of priority claim Japanese patent application No. 1-2242298 (32) Priority Hihei 1 (1989) September 20 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 1-2242299 (32) Priority Day Hei 1 (1989) September 20 (33) ) Country of priority Japan (JP)

Claims (2)

(57) [Claims] 1. A general formula; (In the formula, l and n are integers of 1 to 20, m is 0 or an integer of 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are each hydrogen or an alkyl group having 1 to 5 carbon atoms, It is a cyclohexyl group or a phenyl group.) (Wherein, R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an alkyl group having 1 to 5 carbon atoms), and the structural unit ratio SA / SB =
0.006 to 0.00001, weight average molecular weight of 200,000 to 600,000,
A novel styrene resin, characterized in that the total amount of styrene monomer, styrene dimer, styrene trimer and polymerization solvent is 0.8% by weight or less. 2. A method of producing a styrene-based resin according to claim 1, wherein the styrene-based monomer is bulk-polymerized or solution-polymerized. (In the formula, l and n are integers of 1 to 20, m is 0 or an integer of 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen or an alkyl group having 1 to 5 carbon atoms, cyclohexyl. A low-temperature decomposable organic peroxide containing at least three repeating units represented by the formula (1) or a phenyl group), in an amount of 0.00015 parts by weight to 0.10 parts by weight in terms of active oxygen per 100 parts by weight of the styrene-based monomer. It is added at a ratio of 85 ° C to 125 ° C until the conversion of the styrenic monomer reaches at least 15% by weight. A method for producing a styrene-based resin, which comprises proceeding the polymerization until the concentration of the styrene-based resin reaches 70% by weight or more.