JP4787480B2 - Resin modifier and thermoplastic resin composition - Google Patents

Description

  The present invention relates to a resin modifier excellent in transparency and impact resistance, comprising a vinyl aromatic hydrocarbon and a conjugated diene, a thermoplastic resin composition thereof, and a sheet obtained by molding them.

A block copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene is used as a modifier for a styrenic polymer. The styrenic polymer mixed with the resin modifier is processed into a sheet by extrusion molding or the like, and is provided for various packaging materials having improved impact resistance while maintaining transparency.
In addition, there are disclosure examples (for example, Patent Documents 1, 2, and 3) of block copolymers used for such applications.

Japanese Patent No. 2986178 Japanese Patent No. 2968919 Japanese Patent No. 3332281

An object of the present invention is to provide a novel resin modifier using a block copolymer.
By using the resin modifier of the present invention, the neck-in phenomenon and the winding cracking phenomenon can be reduced.
The neck-in phenomenon refers to a phenomenon in which when a sheet is manufactured using a T-die, the width of the extruded sheet becomes narrower than the die width. When this phenomenon appears greatly, a sheet having a necessary width is obtained. It may not be possible. A winding crack means that a crack occurs on the surface of a sheet when the sheet is rolled and stored after manufacturing the sheet.

The present invention relates to a linear block copolymer (I) that is a linear block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene and simultaneously satisfies the following conditions (1) to (4): 30 to 95 masses %, And a linear block copolymer (II) that simultaneously satisfies the following conditions (5) to (8) with a linear block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene: 5 to 70% by mass A resin modifier having a conjugated diene content of 25 to 35% by mass in the resin modifier.
(1) At least one end portion is a block portion mainly composed of vinyl aromatic hydrocarbon, and the subsequent block portion is composed of conjugated diene and vinyl aromatic, and the conjugated diene gradually decreases toward the other end portion. A block copolymer that is a tapered block portion. The block containing mainly conjugated diene may exist in the part containing a large amount of conjugated diene, and the vinyl aromatic carbonization having a different molecular weight from the other end may be present in the part containing a large amount of vinyl aromatic hydrocarbon. There may be a block mainly composed of hydrogen.
(2) The molecular weight of the linear block copolymer is 50,000 to 150,000, and the molecular weight of the block part mainly composed of vinyl aromatic hydrocarbon is 5,000 to 30,000.
(3) The content rate of conjugated diene is 25-40 mass%.
(4) The mass ratio of vinyl aromatic hydrocarbon / conjugated diene contained in the tapered block portion is 1.6 / 1 to 2.5 / 1.
(5) One end portion is a block portion mainly composed of vinyl aromatic hydrocarbon, and the subsequent block portion is composed of conjugated diene and vinyl aromatic, and the conjugated diene gradually decreases toward the other end portion. A block copolymer having a tapered block portion, the other end of which is a block portion mainly composed of vinyl aromatic hydrocarbons having a different molecular weight from the other end. In a portion containing a large amount of conjugated diene, a block portion mainly composed of conjugated diene may exist.
(6) The molecular weight of the linear block copolymer is 150,000 to 400,000, and the molecular weight of the block part mainly composed of one vinyl aromatic hydrocarbon is 5,000 to 30,000.
(7) The content of conjugated diene is 10 to 25% by mass.
(8) The mass ratio of vinyl aromatic hydrocarbon / conjugated diene contained in the tapered block portion is 1.6 / 1 to 6.0 / 1.

Further, in the present invention, linear block copolymer (I) and linear block copolymer (II) (hereinafter simply referred to as block copolymer (I) and block copolymer (II)). From the thermoplastic resin composition consisting of 40 to 95% by mass of the resin modifier having the above-mentioned ratio and 5 to 60% by mass of the styrene polymer, as well as the sheet formed from the thermoplastic resin composition and the thermoplastic resin composition thereof A multilayer sheet having at least one layer.

  Compared to conventional resin modifiers, the resin modifier of the present invention improves impact strength and rigidity while reducing the decrease in transparency of the thermoplastic resin composition blended with the styrene polymer. It can be maintained to some extent. In addition, when a sheet is produced using the thermoplastic resin composition of the present invention, the film forming property is excellent, and there are few problems of winding cracks. Further, a secondary processed product obtained by thermoforming the sheet also has a balance between strength and transparency. It will be excellent.

The block copolymer (I) and the block copolymer (II) are composed of an organic lithium compound as a polymerization initiator in an organic solvent, and one or more vinyl aromatic hydrocarbons and one or more conjugated dienes as living anions. It can be produced by polymerization.

  Examples of the vinyl aromatic hydrocarbon include styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl styrene, 2,4-dimethyl styrene, 2,5-dimethyl styrene, α-methyl styrene, vinyl naphthalene. , Vinyl anthracene and the like, and styrene is particularly preferable.

  Examples of conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. Among them, 1,3-butadiene and isoprene are particularly preferable.

The resin modifier is essential to be a mixture of the block copolymer (I) and the block copolymer (II) in order to achieve both transparency and impact resistance. As for the ratio, it is preferable that block copolymer (I) exists in the range of 30-95 mass% and block copolymer (II) is 5-70 mass%, More preferably, block copolymer (I) is in the range. It is 40 to 80% by mass, and the block copolymer (II) is in the range of 20 to 60% by mass. When the block copolymer (I) is less than 30% by mass, the impact resistance of the thermoplastic resin composition becomes weak, and when the block copolymer (I) exceeds 95% by mass, the transparency of the thermoplastic resin composition is reduced. However, there is a tendency that the neck-in phenomenon at the time of manufacturing the sheet becomes large and the molding processability is lowered.

  The content of the conjugated diene relative to the entire resin modifier is preferably 25 to 35% by mass. More preferably, it is 26-33 mass%. If the conjugated diene is less than 25% by mass, the thermoplastic resin composition obtained by blending the resin modifier has good transparency but does not exhibit impact resistance. If the conjugated diene exceeds 35% by mass, the thermoplastic resin composition has rigidity. In addition to the lack of transparency, the transparency of the thermoplastic resin composition decreases, and the sheets produced therefrom are more likely to be blocked.

  The molecular weights of the block copolymer (I) and the block copolymer (II) are peak values (polystyrene conversion method) by gel permeation chromatography (hereinafter referred to as GPC), and in the block copolymer (I), 50,000 to 150,000. In the block copolymer (II), it is 150,000 to 400,000. When the molecular weights of the block copolymer (I) and the block copolymer (II) are smaller than the respective prescribed ranges, the viscosity is reduced when the sheet is produced from the thermoplastic resin composition obtained by blending the resin modifier. It is too low to hold the shape, and the appearance of the sheet may deteriorate. Moreover, since fluidity | liquidity will worsen when larger than each regulation range, it exists in the tendency for manufacture of a resin modifier to require much time and energy, or for the sheet processability of a thermoplastic resin composition to fall. Therefore, the 200 ° C. melt mass flow rate of the resin modifier and the thermoplastic resin composition of the present invention is 1 to 20 (g / 10 minutes).

The molecular weight of the block part mainly composed of vinyl aromatic hydrocarbons of the block copolymer (I) and the block copolymer (II) is based on the value of the total molecular weight (in terms of polystyrene) by GPC described above. The calculated value was apportioned with the charged weight ratio. When the molecular weight of the block part mainly composed of vinyl aromatic hydrocarbon at least one end of each block copolymer is less than 5000, the sheet obtained from the thermoplastic resin composition is likely to be broken or wound. And when it becomes larger than 30000, the tendency for the transparency of a thermoplastic resin composition to fall is seen.
The molecular weight of the block part mainly composed of vinyl direction hydrocarbons at the other end of the block copolymer (II) is not particularly limited, but is preferably 30,000 to 200,000, more preferably 40000 to 150,000.

Both the block copolymer (I) and the block copolymer (II) have a block part mainly composed of vinyl aromatic hydrocarbons at one end, and the subsequent block part is conjugated diene and vinyl aromatic. It is characterized by a taper structure that is composed of hydrocarbons and in which conjugated dienes gradually decrease toward the other.
Following the block portion mainly composed of vinyl aromatic hydrocarbon, there is no tapered block portion (there may be a block portion mainly composed of conjugated diene between them), for example, mainly composed of conjugated diene. In the case of only the block, the strength of the sheet of the thermoplastic resin composition composed of a resin modifier using the block tends to decrease or the sheet tends to break.

  The value of the ratio of vinyl aromatic hydrocarbon / conjugated diene in the tapered block portion is 1.6 / 1 to 2.5 / 1 for the block copolymer (I) and 1.6 / 2.5 for the block copolymer (II). It is preferable to be in the range of 1 to 6.0 / 1. More preferably, the block copolymer (I) has a ratio of 1.8 / 1 to 2.5 / 1 and the block copolymer (II) has a ratio of 1.8 / 1 to 2.5 / 1. A thermoplastic resin obtained by blending a resin modifier when the ratio of vinyl aromatic hydrocarbon / conjugated diene of the block copolymer (I) and the block copolymer (II) is smaller than 1.6 / 1 Although the impact resistance of the composition is increased, the transparency is decreased, and conversely, the ratio of vinyl aromatic hydrocarbon / conjugated diene of the block copolymer (I) is greater than 2.5 / 1, or block copolymer When the ratio of the vinyl aromatic hydrocarbon / conjugated diene of the compound (II) is larger than 6.0 / 1, the thermoplastic resin composition has good transparency but the impact resistance tends to decrease.

  In living anionic polymerization, as long as the polymerization active terminal is present, the polymerization of the raw material monomer is continued, so that the residual monomer can be kept low. In addition, the polymerization reaction is characterized in that there is little deactivation of reaction active terminals during polymerization due to chain transfer reaction and generation of new active sites. Therefore, the molecular weight and molecular structure of the block copolymer in the present invention are the same as those of a monomer, a polymerization initiator, a randomizing agent, and a proton donating substance used for deactivation of the active terminal (hereinafter referred to as “polymerization terminator”). It can be controlled by appropriately changing the charged amount, the timing of addition, the number of times of addition, and the order of addition.

  Here, when obtaining a block copolymer consisting of a block part mainly composed of vinyl aromatic hydrocarbon and a block part mainly composed of conjugated diene, the raw material preparation of vinyl aromatic hydrocarbon and conjugated diene is carried out with one reaction. After the process is completed, the next preparation may be performed.

  In order to obtain a tapered block portion, a vinyl aromatic hydrocarbon and a conjugated diene may be charged simultaneously. At this time, the composition ratio of the tapered portion changes with the growth of the block portion due to the difference in the reactivity ratio between the vinyl aromatic hydrocarbon and the conjugated diene, but this can be adjusted by the concentration of the randomizing agent.

  The randomizing agent is a molecule having polarity. For example, amines, ethers, thioethers, phosphoramides, alkylbenzene sulfonates, and potassium or sodium alkoxides can be used. Suitable amines are tertiary amines such as trimethylamine, triethylamine, tetramethylethylenediamine, and cyclic tertiary amines. Suitable ethers include, for example, dimethyl ether, diethyl ether, diphenyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, tetrahydrofuran and the like. In addition, triphenylphosphine, hexamethylphosphoramide, potassium alkylbenzenesulfonate or butoxide such as sodium, potassium, and sodium can also be used.

One or more kinds of randomizing agents can be used, and the addition concentration is suitably 0.001 to 10 parts by mass in total per 100 parts by mass of the raw material monomer.
When polymerizing the block copolymer (I) or the tapered block portion of the block copolymer (II), in order to suppress a single reaction during charging, the vinyl aromatic hydrocarbon and It is desirable to charge the conjugated diene into the reaction system at the same time. And after adding all the raw materials which form a tapered block part, it is desirable to heat the reaction system and to complete superposition | polymerization.
If the temperature exceeds 50 ° C., polymerization of the raw material charged earlier will precede, so the arrangement of the conjugated diene and the vinyl aromatic hydrocarbon does not have a tapered block structure, and the conjugated diene or vinyl aromatic hydrocarbon is not present in the middle. The block part which becomes a main body arises, and the impact resistance of the resin composition obtained as a result may be insufficient.

  Examples of the organic solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane, and alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, or Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene can be used.

  The organic lithium compound as a polymerization initiator is a compound in which one or more lithium atoms are bonded in the molecule. For example, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert- A monofunctional polymerization initiator such as butyl lithium or a polyfunctional polymerization initiator such as hexamethylene dilithium, butadienyl dilithium, or isoprenyl dilithium can be used.

  As the polymerization terminator, for example, at least one kind selected from water, alcohol, inorganic acid, organic acid, and phenolic compound is added to the reaction system to deactivate the active terminal and stop the polymerization. Water is particularly recommended for ease of handling. Since the deactivation stoichiometric number of the polymerization active terminal is proportional to the stoichiometric number of the added polymerization terminator, only a part of the polymerization active terminal is deactivated during the polymerization, and then additional raw material monomers are added. In addition, a production method in which polymerization is further continued can be employed. There is no particular limitation on the number of deactivations during the process unless all the polymerization active terminals are deactivated.

  Examples of the polymerization terminator alcohol include methanol, ethanol, butanol and the like. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, boric acid, phosphoric acid, and carbonic acid. Examples of organic acids include octylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, olefinic acid, linoleic acid, linolenic acid, ricinoleic acid, behenic acid and other carboxylic acids, other sulfonic acids, sulfinic acids, etc. Is mentioned. Examples of phenolic compounds include 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 2-tert-butyl-6. -(3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the like.

  When the polymerization is completed, it is necessary to deactivate all the active ends by adding a sufficient amount of a polymerization terminator to the number of active ends at that time.

  As a method of separating the solvent from the solution containing the deactivated block copolymer, (b) a method of depositing the polymer solution in a large amount of poor solvent such as methanol to precipitate the polymer, or (b) heating. A method in which a polymer solution is supplied to a roll and the like, and only the solvent is evaporated to separate the polymer (drum dryer method). (C) The heated polymer solution is more than the equilibrium vapor pressure at that temperature of the organic solvent contained therein. Method of devolatilization by supplying continuously or intermittently into a can kept at a low pressure (flash evaporation method), (d) Method of devolatilizing a polymerization solution through a vent type extruder, (e) Stirring hot water However, there are a method in which a polymerization solution is blown into the solvent to evaporate the solvent (a steam stripping method), or a method in which these are combined, and any method may be used.

  As described above, the method for producing the resin modifier comprising the block copolymer (I) and the block copolymer (II) comprises inactivating part of the polymerization active terminal during the polymerization, There is a method in which the polymerization is continued and the block copolymer (I) and the block copolymer (II) are simultaneously obtained by one polymerization. There is also a method of mixing a polymerization solution obtained by independently polymerizing the block copolymer (I) and the block copolymer (II). Furthermore, after removing the solvent from each polymerization solution, there is also a method in which each is metered and mixed, for example, in the form of pellets, and kneaded and mixed again using an extruder or the like. At this time, there is no problem even if a styrene polymer is mixed. Further, when the sheet is formed, the block copolymer (I), the block copolymer (II) pellets, and the styrenic polymer can be simultaneously mixed and put into a sheet extruder.

  The resin modifier of the present invention thus produced is used by mixing with one or more selected from the following styrenic polymers.

  The styrenic polymer is polystyrene, styrene- (meth) acrylic acid ester and / or (meth) acrylic acid copolymer, high impact polystyrene, or the like. For example, polystyrene can be used to increase the rigidity of the obtained sheet, and high impact polystyrene can be used to improve the blocking property of the sheet. Further, when it is necessary to minimize the decrease in transparency, styrene- (meth) acrylic acid ester and / or (meth) acrylic acid copolymer can be used in combination. These styrenic polymers are not particularly limited even if they are used alone or in combination of two or more.

Examples of vinyl aromatic hydrocarbon monomers used in these styrenic polymers include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 2 , 5-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene and the like. Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), Examples include 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. In particular, styrene is preferred as the vinyl aromatic hydrocarbon, and 1,3-butadiene and isoprene are preferred as the conjugated diene.
As a (meth) acrylic acid ester monomer used in a styrene- (meth) acrylic acid ester and / or (meth) acrylic acid copolymer which is a kind of styrenic polymer, for example, methyl methacrylate, ethyl methacrylate, Examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like. Examples of (meth) acrylic acid monomers include acrylic acid and methacrylic acid. Particularly preferably, the former monomer is methyl methacrylate and n-butyl acrylate. Of course, two or more types of (meth) acrylic acid ester monomers and / or (meth) acrylic acid monomers such as methyl methacrylate and n-butyl acrylate can be used in combination.

  The blending ratio of the resin modifier and the styrene polymer is preferably 5 to 60% by mass of the styrene polymer with respect to 40 to 95% by mass of the resin modifier. If the styrene polymer exceeds 60% by mass, the impact resistance of the resulting molded product tends to be impaired. In particular, when high-impact polystyrene is used, the amount of high-impact polystyrene is 20% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less. When the high impact polystyrene exceeds 20% by mass, the decrease in transparency is large. It is preferable to melt and knead these using an extruder or the like. Moreover, it can also shape | mold into a sheet | seat, melt-kneading simultaneously with a sheet extruder.

  Various additives can be blended in the resin modifier and the thermoplastic resin composition obtained in the present invention as necessary. For example, this additive is subjected to heat treatment, or the molded product is used in an oxidizing atmosphere or under irradiation with ultraviolet rays or the like, and physical properties are deteriorated. Furthermore, they are added for imparting, for example, stabilizers, lubricants, processing aids, antiblocking agents, antistatic agents, antifogging agents, weather resistance improvers, softeners, plasticizers, pigments and the like.

  Examples of the stabilizer include 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6- Phenolic antioxidants such as di-tert-butyl-4-methylphenol, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, trisnonylphenyl phosphite, bis (2,6 -Di-tert-butyl-4-methylphenyl) pentaerythritol-di-phosphite Such as down-based antioxidants.

  Examples of lubricants, processing aids, antiblocking agents, antistatic agents, and antifogging agents include saturated fatty acids such as palmitic acid, stearic acid, and behenic acid, and fatty acids such as octyl palmitate, octyl stearate, and pentaerythritol fatty acid ester. Esters, erucic acid amide, oleic acid amide, stearic acid amide, etc., ethylene bis stearic acid amide, glycerin-mono-fatty acid ester, glycerin-di-fatty acid ester, sorbitan-mono-palmitic acid ester, Examples include sorbitan fatty acid esters such as sorbitan mono-stearate, higher alcohols typified by myristyl alcohol, cetyl alcohol, stearyl alcohol and the like.

  Furthermore, examples of the weather resistance improver include benzotriazoles such as 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole and 2,4-di-tert- Salicylates such as butylphenyl-3 ′, 5′-di-tert-butyl-4′-hydroxybenzoate, benzophenone UV absorbers such as 2-hydroxy-4-n-octoxybenzophenone, tetrakis (2, Examples include hindered amine type weather resistance improvers such as 2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate.

As other additives, white oil, silicone oil, and the like can be added.

  These additives are desirably used in a range of 5 parts by mass or less with respect to 100 parts by mass of the resin modifier or the thermoplastic resin composition. If it exceeds 5 parts by mass, it may cause a decrease in transparency, or may bleed on the surface of the molded article and cause an appearance failure or a decrease in printability.

  The resin modifier of the present invention may be used not only as a resin modifier in a styrenic polymer, but may be processed into a sheet by itself and further processed into a sheet for practical use. It can also be used for the production of bottle-like containers by blow molding.

  The sheet manufacturing method includes extrusion molding using a T-die, calendering, etc., and the sheet is hung on a tenter provided in a heating furnace and / or a plurality of rolls having different rotational speeds, or a single shaft, or It is also possible to produce a sheet with further orientation by stretching in the biaxial direction.

  In addition, an antistatic agent or a lubricant may be applied to the surface in order to improve the surface characteristics of the obtained sheet. Further, in order to balance sheet properties such as impact resistance and transparency with surface characteristics, it is also possible to make a multilayer sheet having at least one layer of the thermoplastic resin composition of the present invention.

In the case of producing a multilayer sheet, the resin modifier and the thermoplastic resin composition can be multilayered by using a T die having a feed block or a multi-manifold die. In addition, a sheet obtained by extruding the resin modifier alone may be laminated with a sheet obtained by extruding the thermoplastic resin composition.
Furthermore, one or more layers of resins other than these can be laminated within a range that does not impair the physical properties of the resin modifier and / or thermoplastic resin composition. Resins other than these include, for example, block copolymers other than the present invention composed of vinyl aromatic hydrocarbons and conjugated dienes, block copolymers composed of vinyl aromatic hydrocarbons and conjugated dienes, and styrenic polymers. Examples of the resin composition other than the present invention and styrene-based polymers. The styrene polymer referred to here is the one described above.
The multilayer sheet thus obtained is a sheet that is further oriented by stretching it in a uniaxial or biaxial direction on a tenter provided in a heating furnace and / or on a plurality of rolls having different rotational speeds. It is also possible to produce.

For the (multilayer) sheet of the present invention, various molded bodies can be obtained by a known molding method such as a vacuum molding method, a vacuum / pressure forming method, or a hot plate molding method.
Examples of the molded body include a tray, a lid material, a blister pack, a case, and a cup (container), and can be appropriately used as other general resin molded bodies.

  Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples.

  The block copolymer polymerization solutions used in the examples and comparative examples were prepared by the methods shown in the following reference examples.

[Reference Example 1]
(1) Take 480 kg of cyclohexane containing 150 ppm of tetrahydrofuran in a sealable pressure-resistant container having an inner diameter of 1.0 m, a volume of 1.3 m ³ and a Max Blend blade (manufactured by Sumitomo Heavy Industries-60 rpm), and then n-butyl 1490 mL of a cyclohexane solution (hereinafter referred to as initiator) containing 10% by mass of lithium was added, and the liquid temperature was kept at the outside air temperature (about 20 to 30 ° C.).
(2) After 16.0 kg of styrene monomer was added thereto, the temperature inside the can was raised to 70 ° C. for anionic polymerization of the styrene monomer. Thereafter, the temperature inside the can was cooled to 40 ° C.
(3) Next, 96.0 kg of styrene monomer and 48.0 kg of butadiene were added simultaneously, the temperature was raised again, and the reaction was continued. In the anionic polymerization reaction, when water is present, the polymerization active terminal is deactivated. Therefore, a solvent and a raw material monomer with moisture kept at 5 ppm or less were used.
(4) After completion of the reaction, the internal temperature of the can was cooled to 70 ° C., and then the polymerization solution was transferred to another container and 110 g of water was added to deactivate the solution, thereby obtaining a solution containing the polymer of Reference Example 1.

[Reference Examples 2-29]
Using the same equipment as in Reference Example 1, block copolymer solutions of Reference Example 2 to Reference Example 29 were prepared in the same procedure. In addition, about the addition amount of the raw materials in each reaction stage, it combined with the reference example 1 and showed in Table 1-Table 6 collectively.
Tables 7 to 10 show the formulations of resin modifiers and thermoplastic resin compositions using these reference examples and the evaluation results after forming them into sheets, as will be described later. In this, the meaning of the formula showing a molecular structure is as follows. In addition, the number 1 represents belonging to the block copolymer (I), and the number 2 represents belonging to the block copolymer (II).
A1: Block part mainly composed of vinyl aromatic hydrocarbon B1: Tapered block part mainly composed of vinyl aromatic hydrocarbon and conjugated diene C1: Block part mainly composed of conjugated diene A1 ′: Vinyl aromatic having a molecular weight different from that of A1 Block part mainly composed of hydrocarbon A2: Block part mainly composed of vinyl aromatic hydrocarbon B2: Tapered block part composed mainly of vinyl aromatic hydrocarbon and conjugated diene C2: Block part mainly composed of conjugated diene A2 ′: Other than this block part mainly composed of vinyl aromatic hydrocarbons having a molecular weight different from that of A2, the meanings of the abbreviations in the table are as follows.
Bd: Butadiene St: Styrene GP: General-purpose polystyrene (manufactured by Toyo Styrene Co., Ltd .: Toyostyrene G14L)

The molecular weight of the present invention was measured using the following apparatus.
Device name: SYSTEM-21 Shodex (manufactured by Showa Denko)
Column: Three PLgel MIXED-B series connection temperature: 40 ° C
Detection: Differential refractometer Solvent: Tetrahydrofuran concentration: 1 mg / 1 mL (THF)
Flow rate: 1.0 mL / min Pressure: 3.8 MPa
Others: The molecular weight of the present invention was determined by applying the retention time of the peak top of each sample to a calibration curve prepared using a standard polystyrene set with known peak top molecular weight (manufactured by PL, PS-1) (PS Conversion value).
Molecular weight of each block: The total molecular weight determined by measurement was prorated according to the monomer charge mass ratio of each block.

[Example 1]
In each of the polymerization solutions of Reference Example 1 (Block Copolymer (I)) and Reference Example 3 (Block Copolymer (II)), the stabilizer per 100 parts by mass of the total amount of all charged monomers (ie, styrene monomer and butadiene) As a result, 0.40 parts by mass of Sumitizer GS manufactured by Sumitomo Chemical Co., Ltd. and 0.30 parts by mass of Irganox 1076 manufactured by Ciba Specialty Chemicals Co., Ltd. were dissolved. Each of these polymerization solutions was pre-concentrated, and further devolatilized and extruded with a twin-screw extruder equipped with a vacuum vent to obtain pellet-shaped block copolymers.
The block copolymer pellets were mixed at the ratio shown in Table 7, and further melt-kneaded using a single screw extruder to obtain resin modifier pellets.
Furthermore, the resin modifier pellets and general-purpose polystyrene (Toyostyrene Co., Ltd .: Toyostyrene G14L) were mixed at a mass ratio of 60/40, and a sheet having a thickness of 0.6 mm was obtained using a sheet molding machine shown below. Was formed. The sheet thickness was adjusted by the lip opening of the die, and the sheet take-up speed (cooling roll peripheral speed) was constant.
Sheet forming machine: Tanabe Plastic Co., Ltd. 40mmφ single screw extruder VE40 (with 40cm width T die)
Cooling roll diameter: 25cmφ
Distance between cooling roll (touch part) and die outlet: 10 (cm)
Cooling roll peripheral speed: 1.0 m / min

[Example 2 to Example 5, Example 8, Example 9] , [Examination Examples 1 and 2] , [Comparative Example 1 to Comparative Example 12]
A sheet was molded in the same manner as in Example 1, and the moldability, transparency (cloudiness), impact resistance, and sheet cracking property were evaluated. The molecular weight of each resin, the conjugated diene content, the blending ratio of the block copolymer (I) and the block copolymer (II), and the evaluation results are shown in Tables 7 to 10 together with Example 1. It was. Each evaluation method is described below.

[Evaluation method of sheet film formability]
The film forming property (degree of neck-in) of the sheet was evaluated by the following formula. 70% or more can be judged as good.
L1 = Width of the obtained sheet (cm)
L2 = Extrusion die width = 40 (cm)
Neck-in ratio (%) = L1 / L2 × 100

[Transparency evaluation method]
The transparency (cloudiness) of the sheet was measured in accordance with ASTM D1003 using a 4 cm × 8 cm test piece cut out from the molded sheet and using the following evaluation apparatus. If the haze value is 5% or less, it can be judged as good.
Evaluation device: Nippon Denshoku Industries Co., Ltd. Haze meter NDH-1001DP type

[Evaluation method of cracking property]
As for the sheet cracking property, a sheet cut to a length of 50 cm in the MD direction and 30 cm in the TD direction from the molded sheet is closely attached to a core tube made of cardboard having a diameter (outer diameter) of 10 cm along the MD direction. Wrapping and fastening both ends with vinyl adhesive tape. This state was stored in a room adjusted to a state of 23 ° C. and 50% RH, and the state of the curved sheet surface was visually observed over time (up to one month). A sheet that did not cause fine cracks on the sheet surface was regarded as a good product.

[Evaluation method of sheet impact resistance]
The impact resistance is the energy value required for breaking the sheet according to the following steps 1) to 4) using 20 test pieces cut out 6 cm square from each sheet, using a 300 g drop weight and a 1/4 inch R punch. Was calculated. For the measurement, a DuPont impact tester (manufactured by Toyo Seiki Seisakusho) was used.
1) A test piece was placed on the cradle, and the punch was further placed on the test piece. Then, a falling weight was dropped on the upper end of the punch, and the presence or absence of a crack generated in the sheet was examined visually. In addition, before this measurement, 2 to 3 separate preliminary test pieces were used to obtain an approximate height of falling weight where the sheet started to break.
2) The first sheet was measured at the falling weight height determined from the result of the preliminary measurement.
3) From the second sheet onward, based on the previous results, when the sheet did not break, the falling weight height was increased by 5 cm, and when the sheet was broken, the falling weight height was lowered by 5 cm and the measurement was performed in the same manner.
4) This operation was continuously performed 20 times, and impact resistance was evaluated by the following formula from the records of falling weight height and presence / absence of cracks at each time. In addition, impact resistance was converted into an energy value and displayed.
○ represents a sheet in which no cracks occurred, and ● represents a sheet in which cracks occurred.
X (m) = (height x number of circles) / number of circles
Y (m) = (total of height x ● number) / number of ●
Z = (X + Y) / 2 (m)
Impact resistance (J) = 0.3 (kg) × 9.8 (m / s2) × Z (m)

  The thermoplastic resin composition using the resin modifier of the present invention is excellent in transparency and impact strength, and has excellent film forming properties. Therefore, after sheet forming, it is further processed into various containers such as food packs. Thus, it is possible to protect the contents from external impacts while making the contents look beautiful.

Claims (3)

30 to 95% by mass of a linear block copolymer (I) that simultaneously satisfies the following conditions (1) to ( 4 ) with a linear block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene: From 5 to 70% by mass of a linear block copolymer (II) that simultaneously satisfies the following conditions ( 5 ) to ( 8 ) with a linear block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene: A thermoplastic resin comprising 40 to 95% by weight of polystyrene modifier having a conjugated diene content of 25 to 35% by weight and 5 to 60 % by weight of polystyrene. Resin composition.
(1) At least one end portion is a block portion mainly composed of vinyl aromatic hydrocarbon, and the subsequent block portion is composed of conjugated diene and vinyl aromatic, and the conjugated diene gradually decreases toward the other end portion. A tapered block portion.
(2) The peak top molecular weight is 116000 to 132000 , and the molecular weight of the block part mainly composed of vinyl aromatic hydrocarbon is 13000 to 15000 .
(3) The content of conjugated diene is 30 to 34% by mass.
(4) the mass ratio of the vinyl aromatic hydrocarbon / conjugated diene contained in the tapered block portion of 1.6 / 1-2 / 1.
( 5 ) One end portion is a block portion mainly composed of vinyl aromatic hydrocarbon, and the subsequent block portion is composed of conjugated diene and vinyl aromatic, and the conjugated diene gradually decreases toward the other end portion. The tapered block portion has a block portion mainly composed of a vinyl aromatic hydrocarbon whose other end has a molecular weight different from that of the other end.
( 6 ) The peak top molecular weight is 211,000 to 240000 , and the molecular weight of one block part mainly composed of vinyl aromatic hydrocarbon is 11000 to 22000 .
(7) The content of conjugated diene is 16 to 25% by mass.
( 8 ) The mass ratio of vinyl aromatic hydrocarbon / conjugated diene contained in the tapered block portion is 1.6 / 1 to 1.8 / 1. A sheet obtained by molding the thermoplastic resin composition according to claim 1. A multilayer sheet having at least one layer comprising the thermoplastic resin composition according to claim 1.