JP2011202064A - Biaxially stretched styrenic resin sheet, and molded article prepared by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially stretched styrenic resin sheet which is capable of providing a good molded article that has excellent optical characteristics, exhibits sufficient reproducibility of a mold shape and punchability of a molded article in a radiation heating vacuum pressure molding method, and is free from thickness deviation, without generating a gelatinous substance during extrusion processing, is capable of having a heating time range of one second or more, and exhibits excellent productivity during secondary processing.SOLUTION: The biaxially stretched styrenic resin sheet is a sheet obtained by biaxially stretching a styrenic resin composition containing a multibranched copolymer that is obtained by copolymerizing a styrenic monomer (a1), an acrylic ester (a2) and a multibranched macromonomer (a3), wherein Mw of the composition is 300,000-600,000; a ratio (Mw/Mn) between Mw and Mn is 2.7-4.0; a proportion (a1)/(a2) of (a1) to (a2) is 87/13 to 96/4; and heating contraction stresses in the lengthwise and crosswise directions of the provided sheet are 0.20-0.45 MPa.

Description

The present invention is a biaxially stretched styrene resin sheet which is secondarily formed mainly by means of vacuum forming, pressure vacuum forming, hot plate pressure forming, etc., and used for lightweight food packaging containers and other various containers, and uses the same. Related to the molded product.
More specifically, a mold for optical characteristics (transparency, gloss), molding processing characteristics, for example, radiation heating type compressed air vacuum forming (hereinafter used in the meaning including radiation heating type pressure forming and radiation heating type vacuum forming). Excellent reproducibility, punching of molded products, etc., further improving the thickness uniformity of radiant heating type compressed air vacuum molded products, and wide range of optimum molding time when applying the molding method, during secondary processing The present invention relates to a styrene resin sheet obtained by biaxially stretching a styrene resin composition, which has reduced production management problems, and a molded article using the same.

  Conventionally, styrene-based resin sheets have been widely used because they are excellent in transparency and are mainly molded into containers in which the contents can be seen.

  However, since the styrene resin sheet is extremely fragile, it is not supplied in an unstretched state, and is usually stretched with a value of 0.5 MPa or more as a heat shrinkage stress. Moreover, as a forming method, in order to prevent shrinkage due to stress during heating, the forming is performed by using a contact heating type pressure forming method in which a sheet is clamped with a hot plate and formed.

  On the other hand, in recent years, with the increase in take-out type foods, a more transparent food container lid is strongly demanded from the market. In the conventional mainstream contact heating pressure forming method, since the biaxially stretched styrene resin sheet is heated in contact with the hot plate, the unevenness of the hot plate or the antifogging agent attached to the hot plate is transferred to the sheet, There is a problem of impairing the transparency of the molded product, and the radiant heating type vacuum forming method has been reviewed.

As a biaxially stretched styrene resin sheet that can be molded by a radiant heating type pressure air vacuum forming method, for example, a styrene resin in which a styrene butadiene copolymer rubber is dispersed in a styrene resin is approximately biaxially heated and contracted by stress. A sheet stretched and oriented at ^{2 to 4} kg / cm ² (0.196 to 0.392 MPa) has been proposed (see, for example, Patent Document 1).

  In addition, as a method for improving the generation of a gel-like substance due to insufficient thermal stability during extrusion of a styrene-butadiene copolymer, for example, a styrene resin not containing a rubber component, a styrene monomer, and an unsaturated carboxylic acid ester It consists of a copolymer consisting of a monomer, mineral oil, and inorganic or organic particles, and the heat shrinkage stress is MD (longitudinal direction) 0.20 MPa or more, TD (transverse direction) 2.00 MPa or less, and TD and MD A biaxially stretched styrene resin sheet having a difference (TD-MD) of 0.22 MPa or more has been proposed (see, for example, Patent Document 2).

JP 59-71829 A JP 2003-238703 A

  However, the biaxially stretched styrenic resin sheet provided in Patent Documents 1 and 2 improves the thickness uniformity of the molded product in the radiation heating type compressed air vacuum forming method by adjusting the heat shrinkage stress, Although there is a certain effect on the thickness uniformity, there is a problem that the range of the heating time for obtaining a good molded product is very narrow. That is, in the radiant heating type pressure air vacuum forming method, generally, when the heating time is short, the mold reproducibility is insufficient, and when the heating time is lengthened in order to obtain sufficient mold reproducibility, the molding is performed. There is a problem that uneven thickness tends to occur in the product. The range of the optimum heating time for preventing the occurrence of these problems and obtaining a good molded product is less than 1 second when the compositions of Patent Documents 1 and 2 are used. This is very difficult in terms of process control, and from the viewpoint of productivity, it was difficult to apply these biaxially stretched styrene resin sheets to the radiant heating type pressure-air vacuum forming method. Industrial production of molding a resin-based resin sheet by the molding method has not been performed.

  The present invention has been made in view of the above-described problems of the prior art, and the problem to be solved by the present invention is that no gel-like substance is generated during extrusion, excellent optical characteristics, and a radiant heating type compressed air vacuum. Excellent molding reproducibility and punching performance of molded products in molding methods, and good molded products with no uneven thickness are obtained, heating time range can be obtained for 1 second or more, and productivity during secondary processing is excellent. The object is to provide a biaxially stretched styrene resin sheet.

  As a result of diligent studies to solve the above problems, the present inventors obtained a copolymer of a multi-branched macromonomer originally developed by the present inventors, a styrene monomer and an acrylate ester. A sheet obtained by biaxially stretching using a styrene resin composition having a specific weight average molecular weight and a molecular weight distribution, and comprising heat-shrinkage in the longitudinal and transverse directions The inventors have found that a stress in a specific range can solve the above problems, and have completed the present invention.

That is, the present invention has a weight average molecular weight of 1,000 to 1,000, having a styrene monomer (a1), an acrylate ester (a2), a plurality of branches, and a polymerizable double bond at the tip thereof. Biaxially stretched styrene obtained by biaxially stretching a styrene-based resin composition containing a multibranched copolymer (A) obtained by copolymerizing 15,000 multibranched macromonomers (a3) The weight average molecular weight (Mw) calculated | required by GPC-MALS method of this composition is 300,000-600,000, and the ratio of a weight average molecular weight (Mw) and a number average molecular weight (Mn) ( Mw / Mn) is 2.7 to 4.0, and the use ratio (a1) / (a2) of the styrene monomer (a1) to the acrylate ester (a2) is 87/13 to 96 /. 4 (mass ratio) and obtained biaxial elongation Any of the heat shrinkage stress in the longitudinal and transverse directions of the styrenic resin sheet is also intended to provide a biaxially stretched styrenic resin sheet which is a range of 0.20MPa～0.45MPa.
In addition, the present invention provides a molded product obtained by subjecting the biaxially stretched styrene resin sheet to radiant heating type pressure vacuum forming.

  According to the present invention, a biaxial stretching that can obtain a good molded product having sufficient mold reproducibility and no uneven thickness in a radiant heating type compressed air vacuum forming method without generating a gel substance during extrusion processing. A styrene resin sheet is obtained. When this is subjected to secondary processing by a radiant heating type compressed air vacuum forming method, the forming time is sufficiently longer than that conventionally provided, there is no problem in production management, and it is not in contact with the hot plate. Therefore, there is no occurrence of hot plate contamination, and the transparency of the styrene resin is not impaired and the image clarity is excellent. Therefore, it can be suitably used for lid materials for various packaging containers that are mass-produced.

FIG. 3 is a process diagram illustrating an example of a continuous bulk polymerization line incorporating a tubular reactor having a static mixing element.

The present invention will be described in detail below.
The styrene resin composition used in the present invention has a styrene monomer (a1), an acrylate ester (a2), a weight average having a plurality of branches and a polymerizable double bond at the tip. A styrenic resin composition containing a multibranched copolymer (A) obtained by copolymerizing a hyperbranched macromonomer (a3) having a molecular weight of 1,000 to 15,000, the composition The weight average molecular weight (Mw) calculated | required by GPC-MALS method of a thing is 300,000-600,000, and the usage-amount (a1) / (of the said styrene-type monomer (a1) and the said acrylic ester (a2). a2) is 87/13 to 96/4 (mass ratio), and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 2.7 to 4.0. There is something.

  The GPC-MALS method is a method for measuring molecular weight using a multi-angle light scattering detector, and is useful for measuring molecular weight in highly branched polymers. In the present invention, GPC-MALS measurement of a styrene-based resin composition is performed using Shodex HPLC, detector Wyatt Technology DAWN EOS, Shodex RI-101, column Shodex KF-806L × 2, solvent THF (tetrahydrofuran), flow rate 1.0 ml. Per minute. Moreover, the analysis of the measurement of GPC-MALS is performed by the analysis software ASTRA of Wyatt, the weight average molecular weight / number average molecular weight of the styrene resin composition is calculated, and the styrene resin composition is defined by this value. Is.

  It is essential that the weight average molecular weight (Mw) of the styrenic resin composition used in the present invention is 300,000 to 600,000 determined by the above-described method. When the molecular weight is less than 300,000, the optimum heating time in the radiant heating type compressed air vacuum forming method is shortened, and the strength of the molded product may be insufficient. On the other hand, when the molecular weight distribution exceeds 600,000, moldability is insufficient even if the molecular weight distribution is wide, and uneven thickness tends to occur.

  Further, the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by the GPC-MALS method of the styrene resin composition is in the range of 2.7 to 4.0. Required. Mw / Mn smaller than 2.7 is equivalent to the styrene-based resin composition having a multi-branched structure that has been provided by the present inventors, and has a moldability when various molding methods are applied. Is insufficient, and is not suitable for improving the productivity in the radiant heating type pressure air vacuum forming method. In addition, it is difficult to obtain a product having Mw / Mn exceeding 4.0 by a production method described later.

  Further, from the viewpoint of optical properties such as transparency, the melt mass flow rate (hereinafter sometimes referred to as “MFR”) of the styrene resin composition used in the present invention is preferably 2.0 g / 10 min or more. The measurement conditions for the melt mass flow rate are JIS K7210, Condition H (200 ° C., 5 kg).

  Examples of the styrenic monomer (a1) that can be used in the present invention include styrene and derivatives thereof; for example, styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, Alkyl styrene such as butyl styrene, hexyl styrene, heptyl styrene, octyl styrene, halogenated styrene such as fluoro styrene, chloro styrene, bromo styrene, dibromo styrene, iodo styrene, nitro styrene, acetyl styrene, methoxy styrene, etc. These may be used alone or in admixture of two or more. Among these, styrene is preferably used because of its versatility and excellent reactivity with an acrylic ester (a2) described later.

The acrylic ester (a2) that can be used in the present invention is not particularly limited, and, for example, an acrylic alkyl ester having an alkyl group having 1 to 6 carbon atoms or a substituted alkyl group is preferable. Here, the substituted alkyl group refers to an alkyl group in which part or all of the hydrogen atoms of the alkyl group are substituted with a halogen atom, a hydroxyl group or the like, and examples of the halogen atom include fluorine, chlorine, bromine and iodine.
Specific examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, hydroxy acrylate Propyl etc. are mentioned, and may be used alone or in admixture of two or more. Among these, acrylic can be used because the branched structure can be suitably arranged in the obtained multibranched copolymer (A), and the molding processability of the styrene resin composition containing this can be improved. Butyl acid is preferred.

  The multi-branched macromonomer (a3) used in the present invention is a macromonomer having a plurality of branches and having a polymerizable double bond at the tip thereof and a weight average molecular weight of 1,000 to 15,000. Any structure may be used, and the structure is not particularly limited. From the viewpoint of industrial availability, for example, it is preferable to use a multi-branched macromonomer already disclosed by the present inventors in JP-A-2003-292707.

Examples of the hyperbranched macromonomer include those obtained by any of the following methods (1) to (5).
(1) Multi-branched self-condensation polycondensate obtained by nucleophilic substitution reaction of AB ₂ type monomer having active methylene group and bromine, chlorine, methylsulfonyloxy group or tosyloxy group in one molecule Obtained by introducing a polymerizable double bond by subjecting an unreacted active methylene group or methine group remaining in the polycondensate to a nucleophilic substitution reaction with chloromethylstyrene, bromomethylstyrene or the like. Hyperbranched macromonomer,
(2) A compound having one or more hydroxyl groups, a monocarboxylic acid in which the carbon atom adjacent to the carboxyl group is a saturated carbon atom, and all the hydrogen atoms on the carbon atom are substituted, and the monocarboxylic acid has two or more hydroxyl groups. A hyperbranched macromolecule obtained by reacting with acrylic acid, methacrylic acid, an isocyanate group-containing acrylic compound, 4-chloromethylstyrene, etc. by introducing a polymerizable double bond. monomer,
(3) A compound having at least one hydroxyl group is reacted with a cyclic ether compound having at least one hydroxyl group to form a multi-branched polymer, and then the hydroxyl group as a terminal group of the polymer is converted to acrylic acid, methacrylic acid, isocyanate. A hyperbranched macromonomer obtained by reacting a group-containing acrylic compound, 4-chloromethylstyrene, etc., and introducing a polymerizable double bond;
(4) A multi-branched polymer is obtained by reacting a compound having one or more hydroxyl groups with two or more hydroxyl groups and a compound containing a halogen atom, —SO ₂ OCH ₃ , —OSO ₂ CH ₃ or the like. Then, the multi-branched macromonomer obtained by reacting acrylic acid, methacrylic acid, isocyanate group-containing acrylic compound, 4-chloromethylstyrene, etc. with the hydroxyl group which is the terminal group of the polymer and introducing a polymerizable double bond ,
(5) Acrylic acid, methacrylic acid, an isocyanate group-containing acrylic compound, 4-chloromethylstyrene, etc. are reacted with a PAMAM dendrimer in which the amide bond has a repeating structure via a nitrogen atom, and a polymerizable double bond is formed. Multibranched macromonomer obtained by introduction.

Examples of the AB type ₂ monomer having an active methylene group and a bromine, chlorine, methylsulfonyloxy group, or tosyloxy group in one molecule in the above (1) include halogenated alkoxy-phenylacetonitriles or tosyloxy groups. And phenylacetonitriles having

  Examples of the monocarboxylic acid in (2) in which the carbon atom adjacent to the carboxyl group is a saturated carbon atom, all the hydrogen atoms on the carbon atom are substituted, and having two or more hydroxyl groups include, for example, dimethylol. Propionic acid, α, α-bis (hydroxymethyl) butyric acid, α, α, α-tris (hydroxymethyl) acetic acid, α, α-bis (hydroxymethyl) valeric acid or α, α-bis (hydroxymethyl) propionic acid Etc.

  Examples of the cyclic ether compound having one or more hydroxyl groups in (3) above include 3-ethyl-3- (hydroxymethyl) oxetane, 2,3-epoxy-1-propanol, and 2,3-epoxy-1- Examples include butanol or 3,4-epoxy-1-butanol.

Examples of the compound containing two or more hydroxyl groups in (4) above, a halogen atom, —SO ₂ OCH ₃ , —OSO ₂ CH _{3 and the} like include, for example, 5- (bromomethyl) -1,3-dihydroxybenzene, 2-ethyl-2- (bromomethyl) -1,3-propanediol, 2-methyl-2- (bromomethyl) -1,3-propanediol, 2- (bromomethyl) -2- (hydroxymethyl) -1,3 -Propanediol etc. are mentioned.

  The PAMAM dendrimer in the above (5) can be produced, for example, by the technique shown in Japanese Patent Publication No. 6-070132 and Japanese Patent Publication No. 7-043522.

  In addition, it is essential that the weight average molecular weight of the hyperbranched macromonomer (a3) is 1,000 to 15,000. The molecular weight is determined by GPC-MALS measurement method (Shodex HPLC, detector Wyatt Technology DAWN EOS, Shodex RI-101, column Shodex KF-806L × 2, solvent THF (tetrahydrofuran), flow rate 1.0 ml / min). Can be measured. When the molecular weight is less than 1,000, the introduction amount of the branched structure is insufficient, and the physical properties are close to those of the conventional linear styrene-acrylic copolymer, and a styrene resin composition having a wide molecular weight distribution range defined in the present application is obtained. In some cases, the molded product obtained is difficult to be obtained and the practical strength is insufficient. On the other hand, when the molecular weight is 15,000 or more, it is difficult to handle the hyperbranched macromonomer, and it may be difficult to uniformly copolymerize the styrene monomer (a1) and the acrylate ester (a2). A more preferable molecular weight is 2,500 to 7,000.

  The multi-branched macromonomer (a3) preferably contains 0.1 to 5.5 mmol of polymerizable double bond per gram. Within this range, the introduction amount of the branched structure in the resulting multibranched copolymer (A) can be controlled, and the desired high molecular weight component is appropriately contained while preventing gelation during production, and is wide. It becomes easy to obtain a styrene resin composition having a molecular weight distribution. A more preferable content is in the range of 1.0 to 3.5 mmol. This content is determined, for example, in the case of a double bond based on methacrylic acid or a derivative thereof as containing 1 mol of double bond in the formula amount of methyl methacrylate, and styrene or the like. In the case of a double bond based on a compound, this is the value determined as containing 1 mole of double bond in the formula weight of styrene.

  The hyperbranched copolymer (A) used in the present invention is obtained by copolymerizing the styrene monomer (a1), the acrylate ester (a2), and the hyperbranched macromonomer (a3). It is what

  As a method for producing the multibranched copolymer (A) used in the present invention, the styrene monomer (a1), the acrylate ester (a2) and the multibranched macromonomer (a3) are copolymerized. The styrenic resin composition containing the multi-branched copolymer (A) is not particularly limited as long as it has the molecular weight / molecular weight distribution range specified in the present application. It is preferable to employ a production method already provided by the present inventors in Japanese Patent Application Laid-Open No. 2005-053939 and the like from the viewpoint that the objective styrenic resin composition can be efficiently produced by a one-step reaction.

  Specifically, the mixture containing the raw materials (a1) to (a3) is preferably reacted by a solution polymerization method or a melt polymerization method (bulk polymerization method). In this case, the reaction can be carried out without adding an organic solvent, but it is preferable to use a small amount of an organic solvent in combination because the viscosity of the reaction product is lowered and the molecular weight of the polymer is easily controlled.

As the organic solvent that can be used, one having a chain transfer constant of 0.1 × 10 ⁻⁵ to 1 × 10 ⁻⁴ is preferable, and one having a chain transfer constant of 0.2 × 10 ^{−5 to} 0.8 × 10 ^−5. More preferred. For example, toluene, ethylbenzene, xylene, acetonitrile, benzene, chlorobenzene, dichlorobenzene, anisole, cyanobenzene, dimethylformamide, N, N-dimethylacetamide, methyl ethyl ketone and the like are preferable. About the usage-amount, 5 mass parts-50 mass parts are preferable with respect to a total of 100 mass parts of a raw material monomer, and 6 mass parts-20 mass parts are more preferable. In addition, when it superposes | polymerizes using an organic solvent, it is easy to suppress the production | generation of an organic solvent insoluble part, and it is preferable.

  In particular, when it is desired to increase the amount of the multi-branched macromonomer (a3), it is necessary to use the organic solvent from the viewpoint of suppressing gelation. Thereby, it is possible to increase the addition amount of the multibranched macromonomer shown above.

  In starting the polymerization, a radical polymerization initiator is used. As such an initiator, those having a half-life of 10 hours are preferably 75 to 140 ° C, more preferably 85 to 135 ° C. For example, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) butane, 2,2-bis (4,4-di-butylperoxycyclohexyl) propane, etc. Hydroperoxides such as peroxyketals, cumene hydroperoxide, t-butyl hydroperoxide, dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, di-t-hexyl peroxide, Diacyl peroxides such as benzoyl peroxide and disinamoyl peroxide, peroxyesters such as t-butyl peroxybenzoate, di-t-butyl peroxyisophthalate, and t-butyl peroxy isopropyl monocarbonate, N , N'-Azobisisobutylnitrate N, N′-azobis (cyclohexane-1-carbonitrile), N, N′-azobis (2-methylbutyronitrile), N, N′-azobis (2,4-dimethylvaleronitrile), N, N′-azobis [2- (hydroxymethyl) propionitrile] and the like can be mentioned, and these can be used alone or in combination.

  As these usage-amounts, 50 ppm-1,000 ppm are preferable on a mass basis with respect to the monomer synthetic | combination mass of a raw material, More preferably, it is 100-500 ppm.

  Further, a chain transfer agent may be added so that the molecular weight of the styrene resin composition containing the multibranched copolymer (A) does not become excessively large. As the chain transfer agent, a monofunctional chain transfer agent having one chain transfer group or a polyfunctional chain transfer agent having a plurality of chain transfer agents can be used. Examples of the monofunctional chain transfer agent include alkyl mercaptans and thioglycolic acid esters.

  Polyfunctional chain transfer agents such as ethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, etc. are esterified with thioglycolic acid or 3-mercaptopropionic acid. The thing which was done is mentioned.

  The styrenic resin composition used in the present invention contains the multi-branched copolymer (A) as an essential component. When the multi-branched copolymer (A) is synthesized as described above, Is obtained as a mixture containing a linear copolymer of the styrene monomer (a1) and the acrylate ester (a2) at the same time. In the present invention, the styrenic resin composition only needs to contain the multi-branched copolymer (A) as an essential component, so there is no need to remove such a linear copolymer. If the ratio is Mw / Mn, the styrene resin composition used in the present invention can be used as it is. Further, if the Mw and Mw / Mn specified above are not satisfied in the one-stage manufacturing process, a resin obtained by separately copolymerizing the styrene monomer (a1) and the acrylate ester (a2) is used. It can also be mixed and adjusted.

In the use ratio of the styrene monomer (a1) and the acrylate ester (a2) in the styrene resin composition used in the present invention, the acrylate ester (a2) is used from the viewpoint of improving low-temperature moldability and image clarity. The use ratio is essential to be 4% by weight or more. Moreover, 13 weight% or less is essential from a viewpoint of practical heat resistance, such as blocking prevention at the time of sheet transport. That is, it is essential that the ratio (a1) / (a2) of the styrene monomer (a1) and the acrylate ester (a2) is 87/13 to 96/4 (mass ratio).
Moreover, it is preferable to use the said hyperbranched macromonomer (a3) by 100-1,000 ppm on a mass basis with respect to the sum total of the said styrene-type monomer (a1) and the said acrylic ester (a2).
By mix | blending a raw material in the said range, it becomes easy to obtain the styrene-type resin composition which has Mw and Mw / Mn prescribed | regulated above by a one-stage manufacturing process. From the viewpoint of excellent physical property balance of the obtained molded product, butyl acrylate is used as the acrylate ester (a2), and the ratio of use with the styrene monomer (a1) is (a1) / butyl acrylate is 92 / More preferably, it is 8 to 96/4 (mass ratio).

  The styrene resin composition used in the present invention is a styrene resin composition containing the multi-branched copolymer (A) as described above, and is a weight average determined by the GPC-MALS method of the composition. The molecular weight (Mw) may be 300,000 to 600,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) may be 2.7 to 4.0. It may be composed only of the copolymer (A), or may be composed of the multi-branched copolymer (A) and other components. Here, as the other components, the use of the other components is not particularly limited as long as the weight average molecular weight and the number average molecular weight of the styrenic resin composition are not deviated from the above ranges and the effects of the present application are not hindered. However, various additives and polymer compounds such as the above-mentioned linear copolymers can be used depending on the application.

  Examples of the additive include various stabilizers, antiblocking agents, antistatic agents, lubricants, antifogging agents, antibacterial agents, antioxidants, dyes, and ultraviolet absorbers. However, since the styrenic resin composition used in the present invention is excellent in these performances without using mineral oil or the like that has been used for imparting releasability and molding processability, the use of additives However, it is necessary to pay attention to a point different from the method of using the additive in the conventional styrene- (meth) acrylic copolymer.

  The biaxially stretched styrene resin sheet of the present invention is formed by biaxially stretching using the styrene resin composition obtained as described above, and is heated in any of the longitudinal and lateral directions of the sheet. The shrinkage stress is also in the range of 0.20 MPa to 0.45 MPa.

The heat shrinkage stress is a physical property value usually used in this technical field as described in Patent Documents 1 and 2, and specifically, a value measured according to ASTM D-1504. is there.
In the present invention, both the longitudinal direction (MD) of the biaxially stretched sheet and the transverse direction (TD) perpendicular thereto are set to a heat shrinkage stress of 0.20 MPa to 0.45 MPa which is a relatively low value range. In addition, even when radiant heating type pressure vacuum forming which forms without fixing the sheet is applied, uneven thickness or the like does not occur, and the thickness uniformity of the formed product is excellent. It has already been found in Patent Document 1 that such a low heat shrinkage stress is preferable for radiant heating type compressed air vacuum forming, but the present invention has the transparency inherent in styrene resins. In order to ensure the optimum heating time that can be a practical problem as described above without impairing, it is essential to use a styrene resin composition having a multi-branched structure and having a specific molecular weight / molecular weight distribution width. Is.
In addition, when the heat shrinkage stress is less than 0.20 MPa, the optimum heating time in the radiant heating type compressed air vacuum forming method becomes long, but the strength of the molded product may be insufficient. Further, when the heat shrinkage force is 0.45 MPa or more, the molding process characteristics are impaired.

  It does not specifically limit as a method for setting it as the biaxially stretched sheet which has the specific heat contraction stress of this invention. Heat shrinkage stress can be adjusted by stretching temperature, stretching ratio, etc., but it also varies depending on the sheet extrusion speed and sheet width at the time of extrusion (before stretching), so specify specific production conditions. It is difficult. However, in general production conditions, the stretching temperature is preferably the Vicat softening point of the above-mentioned styrenic resin composition + (0-40) ° C., and the stretching ratio is 1.5-5.0 in one direction. It is preferable that it is double. If these values are within this range, a sheet having the heat shrinkage stress defined in the present invention can be easily produced.

  Further, the thickness of the sheet obtained by biaxial stretching is not particularly limited, but is preferably in the range of 0.1 to 1 mm because it can be applied to a general-purpose radiant heating type pressure vacuum forming machine. It is.

  The production method of the biaxially stretched styrene resin sheet of the present invention is not particularly limited, and may be performed by a method used in the production of a conventional stretched sheet. For example, a styrenic resin composition is supplied to an extruder, melted and kneaded, and then continuously extruded with a T die or a circular die. This is a method of axial stretching.

  Moreover, the biaxially-stretched styrene resin sheet of this invention can apply | coat an antifogging agent or a mold release agent to at least one surface or both surfaces. You may use an antifogging agent and a mold release agent together. Examples of the antifogging agent include nonionic surfactants such as sorbitan fatty acid ester, sucrose fatty acid ester, polyglycerin fatty acid ester, and polyoxyethylene derivative, and these can be used alone or in a mixture. Examples of the release agent include silicone oil and emulsion thereof. Various nonionic surfactants, cationic surfactants, anionic surfactants, and the like may be applied as an antistatic agent. Examples of these coating methods include spray coaters, roll coaters, gravure roll coaters, knife coaters, air knife coaters, rotor dampening coaters, and applicator systems.

  The biaxially stretched styrenic resin sheet of the present invention provides design, functionality, etc. within a range that does not impair the effects of the present invention, so printing on the surface of the sheet, barrier properties, antibacterial properties, heat A resin having functionality such as a sealing property may be laminated on the surface of the sheet. Moreover, you may use as a part of container, such as laminating the biaxially-stretched styrene resin sheet of this invention on a foam sheet.

The biaxially stretched styrene resin sheet of the present invention can contain various fine particles in order to impart an antiblocking effect. Examples of the fine particles include resin crosslinked particles such as styrene resin crosslinked particles, (meth) acrylic ester resin crosslinked particles, polyurethane resin crosslinked particles; silica, hydrophobized silica, spherical silica, light calcium carbonate, oxidized Examples thereof include inorganic fine particles such as titanium and talc, and rubber fine particles such as styrene grafted diene rubber.
In particular, styrene-grafted diene rubber is particularly preferred because it improves the strength, anti-blocking property and peelability of the biaxially stretched styrene resin sheet and a molded article using the same. Here, as the styrene graft diene rubber, a biaxially stretched styrene-based resin sheet and a molded article using the same can be obtained with an excellent balance between strength and appearance, so that the average particle size is 0.1 to 5. What is contained in the biaxially-stretched styrene-based resin sheet so that the diene component is in the range of 0.05 to 3.0% by mass at 0 μm is preferable. In order to obtain higher transparency, it is preferable to contain 0.05-0.5 mass%.

In addition, the biaxially stretched styrene resin sheet of the present invention improves the stretchability at the time of forming the biaxially stretched styrene resin sheet, the deep drawability at the time of secondary molding to be molded into a container, and the low temperature moldability. Mineral oil may be contained. However, the volatile matter of mineral oil generated at the time of melt extrusion is aggregated and adhered to the sheet manufacturing apparatus, and this is transferred to the sheet to prevent the appearance failure of the biaxially oriented styrene resin sheet. It is preferable to do.
The above-mentioned various particles and mineral oil can be added to the styrenic resin composition before biaxial stretching obtained by the method described above and contained in the biaxially stretched styrene resin sheet.

  The molded product of the present invention is obtained by subjecting the above-mentioned biaxially stretched styrene resin sheet to secondary processing, and the molding method is preferably radiant heating type pressure vacuum forming. The shape and use of the molded product are not particularly limited, and examples thereof include food container lids, trays, food packs, blister packs, other various packs, and cases. In particular, the molded product obtained by radiant heating type pressure-air vacuum forming using the biaxially stretched styrene resin sheet of the present invention is non-contact with the hot plate, so the fineness applied to the hot plate for pressure adjustment Since no hot holes are transferred or hot plate stains derived from the antifogging agent or the like coated on the surface of the sheet are not transferred, the transparency is excellent.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”.

The measurement method used will be described.
[GPC-MALS measurement conditions]
GPC-MALS measurement of styrenic resin composition was performed under the conditions of Shodex HPLC, detector Wyatt Technology DAWN EOS, Shodex RI-101, column Shodex KF-806L × 2, solvent THF (tetrahydrofuran), flow rate 1.0 ml / min. I went. Moreover, the analysis of the measurement of GPC-MALS was performed with the analysis software ASTRA of Wyatt, and the weight average molecular weight, the number average molecular weight, etc. about the styrene resin composition were calculated | required.

[Melt Mass Flow Rate Measurement Method]
The measurement was performed according to JIS K7210. The measurement conditions are a temperature of 200 ° C. and a load of 49N.

[Vicat softening temperature]
It measured based on JISK7206: 99.

(Image clarity)
Evaluation was made at JIS K7374 comb spacing of 0.5 mm, and 50% or more was judged as acceptable (◯). Further, 70% or more was rated as “◎”.

(Folding strength)
JIS P8115 The average of the vertical direction and the horizontal direction was 6 times or more as a pass (◯). Moreover, 10 times or more was set as ◎.

[Heating shrinkage stress]
Measured according to ASTM D-1504.

[Optimum heating time]
Using FK-0431-10 manufactured by Asano Laboratory Co., Ltd., changing the heating time at a heater temperature of 370 ° C., forming a sheet with a mold having a frontage of 10 cm × 10 cm and a drawing ratio of 0.3, and obtaining the same heating time The time when the weight difference of the molded product was ± 10% or more was defined as the upper limit of molding. Further, molding was performed with a mold having a hole of 5 mmφ, and the time when the height of the protrusion was 1.5 mm or more was defined as the lower limit of molding. Those with a molding range of 1 second or more were evaluated as acceptable (◯).

Reference Example 1 Synthesis of Multibranched Macromonomer (a3-1) <Synthesis of Multibranched Polyether Polyol>
To a 2 liter flask equipped with a stirrer, thermometer, dropping funnel and condenser, 50.5 g of ethoxylated pentaerythritol (5 mol-ethylene oxide-added pentaerythritol) and 1 g of BF ₃ diethyl ether solution (50%) were added at room temperature. Heated to 110 ° C. To this, 450 g of 3-ethyl-3- (hydroxymethyl) oxetane was slowly added over 25 minutes while controlling the exotherm due to the reaction. When the exotherm had subsided, the reaction mixture was further stirred at 120 ° C. for 3 hours and then cooled to room temperature. The resulting multi-branched polyether polyol had a weight average molecular weight of 3,000 and a hydroxyl value of 530.

<Synthesis of a hyperbranched macromonomer having a methacryloyl group and an acetyl group>
In a reactor equipped with a Dean-Stark decanter equipped with a stirrer, a thermometer, a condenser, and a gas introduction tube, 50 g of the multi-branched polyether polyol obtained in the above-mentioned <Synthesis of multi-branched polyether polyol 1>, methacrylic acid 13 .8 g, 150 g of toluene, 0.06 g of hydroquinone and 1 g of paratoluenesulfonic acid, and stirring under normal pressure while blowing 7% oxygen-containing nitrogen (v / v) into the mixed solution at a rate of 3 ml / min. Heated. The amount of heating was adjusted so that the amount of distillate in the decanter was 30 g per hour, and heating was continued until the amount of dehydration reached 2.9 g. After completion of the reaction, the mixture was cooled once, 36 g of acetic anhydride and 5.7 g of sulfamic acid were added, and the mixture was stirred at 60 ° C. for 10 hours. Thereafter, in order to remove the remaining acetic acid and hydroquinone, it was washed with 50 g of 5% aqueous sodium hydroxide solution four times, and further washed once with 50 g of 1% aqueous sulfuric acid solution and twice with 50 g of water. To the obtained organic layer, 0.02 g of methoquinone was added, the solvent was distilled off under reduced pressure while introducing 7% oxygen-containing nitrogen (v / v), and a multibranched macromonomer having an isopropenyl group and an acetyl group ( a3-1) 60 g was obtained. The obtained multibranched macromonomer (a3-1) has a weight average molecular weight of 3,900, and the introduction ratio of isopropenyl group and acetyl group into the multibranched polyether polyol is 30 mol% and 62 mol%, respectively. there were. Therefore, the introduction amount of the polymerizable double bond is 1.51 mmol / g.

(Reference Example 2) Synthesis of hyperbranched macromonomer (a3-2) <Synthesis of hyperbranched macromonomer having a styryl group and an acetyl group>
In a reactor equipped with a stirrer, a condenser equipped with a drying tube, a dropping funnel and a thermometer, 50 g of the multibranched polyether polyol obtained in the above-mentioned <Synthesis of multibranched polyether polyol 1>, 100 g of tetrahydrofuran and sodium hydride 4.3 g was added and stirred at room temperature. To this was added dropwise 26.7 g of 4-chloromethylstyrene over 1 hour, and the resulting reaction mixture was further stirred at 50 ° C. for 4 hours. After completion of the reaction, the reaction mixture was once cooled, 34 g of acetic anhydride and 5.4 g of sulfamic acid were added, and the mixture was stirred at 60 ° C. for 10 hours. Thereafter, the tetrahydrofuran was distilled off under reduced pressure, the resulting mixture was dissolved in 150 g of toluene, washed with 50 g of 5% aqueous sodium hydroxide solution to remove the remaining acetic acid, and further 50 g of 1% aqueous sulfuric acid solution. And once with 50 g of water. The solvent was distilled off from the obtained organic layer under reduced pressure to obtain 70 g of a hyperbranched macromonomer (a3-2) having a styryl group and an acetyl group. The obtained multibranched macromonomer (a3-2) had a weight average molecular weight of 4,800, and the introduction ratios of styryl groups and acetyl groups into the multibranched polyether polyol were 38 mol% and 57 mol%, respectively. It was. Therefore, the introduction amount of the polymerizable double bond is 1.31 mmol / g.

Reference Example 3 Synthesis of Multibranched Macromonomer (a3-3) <Synthesis of Multibranched Macromonomer Having a Methacryloyl Group and an Acetyl Group>
A four-necked flask was equipped with a stirrer, pressure gauge, condenser and saucer, to which 308.9 g of ethoxylated pentaerythritol and 0.46 g of sulfuric acid were added. Then, it heated to 140 degreeC and 460.5g of 2, 2- di (hydroxymethyl) propionic acid was added over 10 minutes. After 2,2-di (hydroxymethyl) propionic acid is completely dissolved and becomes a transparent solution, the pressure is reduced to 30 to 40 mmHg and the reaction is continued for 4 hours while stirring and the acid value becomes 7.0 mgKOH / g. I let you. Thereafter, 921 g of 2,2-di (hydroxymethyl) propionic acid and 0.92 g of sulfuric acid were added to the reaction solution over 15 minutes to obtain a transparent solution, and then the pressure was reduced to 30 to 40 mmHg, while stirring. The polyester polyol was obtained by reacting for a period of time. In a reaction vessel equipped with a 7% oxygen introduction tube, a thermometer, a Dean-Stark decanter equipped with a condenser, and a stirrer, 10 g of the polyester polyol produced above, 1.25 g of dibutyltin oxide, and 100 g of methyl methacrylate having an isopropenyl group And 0.05 g of hydroquinone were added, and the mixture was heated with stirring while blowing 7% oxygen at a rate of 3 ml / min. The amount of heating is adjusted so that the amount of distillate in the decanter is 15 to 20 g per hour, the distillate in the decanter is taken out every hour, and the corresponding amount of methyl methacrylate is added for 4 hours. Reacted. After completion of the reaction, methyl methacrylate was distilled off under reduced pressure, and 10 g of acetic anhydride and 2 g of sulfamic acid were added to cap the remaining hydroxy groups, followed by stirring at room temperature for 10 hours. After removing sulfamic acid by filtration and distilling off acetic anhydride and acetic acid under reduced pressure, the residue was dissolved in 70 g of ethyl acetate and washed 4 times with 20 g of 5% aqueous sodium hydroxide to remove hydroquinone. Further, it was washed twice with 20 g of a 7% aqueous sulfuric acid solution and twice with 20 g of water. To the obtained organic layer, 0.0045 g of methoquinone was added, and the solvent was distilled off while introducing 7% oxygen under reduced pressure to obtain 11 g of a hyperbranched macromonomer having an isopropenyl group and an acetyl group. The resulting multi-branched macromonomer (a3-3) had a weight average molecular weight of 3,000, a number average molecular weight of 2,100, and isopropenyl group and acetyl group introduction rates of 55 mol% and 36 mol%, respectively. It was. Therefore, the introduction amount of the polymerizable double bond is 2.00 mmol / g.

Reference Example 4 Synthesis of hyperbranched macromonomer (a3-4) <Synthesis of PAMAM dendrimer having a styryl group>
To a reactor equipped with a stirrer, a condenser equipped with a drying tube, a dropping funnel and a thermometer, 50 g of a methanol solution (20%) of PAMAM dendrimer (Generation 2.0: manufactured by Dentritech) was added and stirred under reduced pressure. Methanol was distilled off. Subsequently, 50 g of tetrahydrofuran and 3.0 g of finely divided potassium hydroxide were added, and the mixture was stirred at room temperature. 4-chloromethylstyrene 7.0g was dripped at this over 10 minutes, and the obtained reaction mixture was further stirred at 50 degreeC for 3 hours. After completion of the reaction, the mixture was cooled and the solid was filtered, and then tetrahydrofuran was distilled off under reduced pressure to obtain 13 g of a PAMAM dendrimer having a styryl group. The resulting dendrimer had a styryl group content (introduced amount of polymerizable double bond) of 2.7 mmol / gram. The weight average molecular weight of the obtained multibranched macromonomer (a3-4) was 4,050.

Reference Example 5 Synthesis of Multibranched Macromonomer (a3-5) <Multibranched Polyether Polyol Having Styryl Group and Acetyl Group>
A light-shielding reaction vessel equipped with a stirrer, a condenser, a light-shielding dropping funnel and a thermometer, and capable of nitrogen sealing. Under nitrogen flow, anhydrous 1,3,5-trihydroxybenzene 0.5 g, potassium carbonate 29 g, 18-crown -6 2.7 g and acetone 180 g were added, and a solution composed of 21.7 g of 5- (bromomethyl) -1,3-dihydroxybenzene and 180 g of acetone was added dropwise over 2 hours while stirring. Thereafter, the mixture was heated and refluxed with stirring until 5- (bromomethyl) -1,3-dihydroxybenzene disappeared. Thereafter, 9.0 g of 4-chloromethylstyrene was added, and the mixture was further heated and refluxed with stirring until the disappearance. Thereafter, 4 g of acetic anhydride and 0.6 g of sulfamic acid were added to the reaction mixture, and the mixture was stirred overnight at room temperature. After cooling, the solid in the reaction mixture was removed by filtration, and the solvent was distilled off under reduced pressure. The resulting mixture was dissolved in dichloromethane and washed three times with water, and then the dichloromethane solution was added dropwise to hexane to precipitate the product. This was filtered and dried to obtain 12 g of a hyperbranched macromonomer (a3-5) having a styryl group and an acetyl group. The weight average molecular weight was 3,200, and the styryl group content was 3.5 mmol / gram.

Example 1
In this example, an apparatus having lines arranged as shown in FIG. 1 was used. A mixed solution containing styrene, butyl acrylate, a solvent, and the like was supplied to a stirring reactor (2) by a plunger pump (1). Then, it supplied to the circulation polymerization line (I) with the gear pump (3). The circulation polymerization line (I) is used to circulate the 2.5 inch inner diameter tubular reactor (SMX static mixer manufactured by Gebrüu Sulzer, Switzerland) (4), (5), (6) and the mixed solution in order from the inlet. Gear pump (7). The reaction volume of (4) to (6) is about 20L. Between the tubular reactor (6) and the gear pump (7), there is an outlet that leads to the non-circulating polymerization line (II). Tubular reactors (8), (9), (10) and a gear pump (11) similar to the above are connected in series from the inlet to the non-circulating polymerization line (II). The reaction volume of (8) to (10) is about 16L.

93.5 parts of styrene, 6.5 parts of butyl acrylate, 7 parts of ethylbenzene, 300 ppm of the hyperbranched macromonomer (a3-1) of Reference Example 1 with respect to 100 parts in total of styrene and butyl acrylate, a polymerization initiator [ 1,2-bis (4,4-di-t-butylperoxycyclohexyl) propane] was prepared by adjusting a mixed solution consisting of 150 ppm with respect to a total of 100 parts of styrene and butyl acrylate, and using the apparatus shown in FIG. Polymerization was continuously performed under the following conditions.
Feed rate of mixed solution: 9.0 liter / hour Reaction temperature in stirred reactor: 116 ° C.
Reaction temperature in circulation polymerization line (I): 120 ° C
Reaction temperature in non-circulation polymerization line (II): 155 to 170 ° C.

  The mixed solution obtained by polymerization was heated with a heat exchanger at 260 ° C., and after removing volatile components under a reduced pressure of 5 kPa, pelletized to obtain a styrene resin composition. The polymerization average molecular weight Mw of the styrene-based resin composition was 380,000, and the MFR was 4.0 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8.

  A twin screw extruder (TEX30α-31.5BW- manufactured by Nippon Steel Works, Ltd.) having 2% high impact polystyrene dick styrene GH-8300-5 added to the styrene-based resin composition obtained above and having a φ30 mm diameter screw 5V), melt kneading, extrusion from a T-die, cooling with a roll, reheating, stretching in the sheet flow direction (MD) due to the speed difference of the roll group, and then the sheet flow direction with a tenter. Stretching was performed in the orthogonal direction (referred to as TD) to produce a sheet having a thickness of 0.25 mm. The draw ratio is as shown in the table of Example 1. The stretching temperature was adjusted to be the heat shrinkage stress in the table. The sheet was excellent in image definition and folding strength, and the optimum heating time in the radiant heat type pressure air vacuum forming method was sufficient.

Example 2
A styrene resin composition was obtained in the same manner as in Example 1 except that the multibranched macromonomer (a3-2) was used instead of the multibranched macromonomer (a3-1) in Example 1. The polymerization average molecular weight Mw was 350,000, and the MFR was 3.9 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 3
A styrene resin composition was obtained in the same manner as in Example 1 except that the multi-branched macromonomer (a3-3) was used instead of the multibranched macromonomer (a3-1) in Example 1. The polymerization average molecular weight Mw was 390,000, and MFR was 4.0 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was prepared in the same manner as in Example 1 using the obtained resin composition.

Example 4
A styrene resin composition was obtained in the same manner as in Example 1 except that the multibranched macromonomer (a3-4) was used instead of the multibranched macromonomer (a3-1) in Example 1. The polymerization average molecular weight Mw was 360,000, and MFR was 4.0 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 5
A styrene resin composition was obtained in the same manner as in Example 1 except that the multibranched macromonomer (a3-5) was used instead of the multibranched macromonomer (a3-1) in Example 1. The polymerization average molecular weight Mw was 320,000, and MFR was 3.9 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 6
A styrene resin composition was obtained in the same manner as in Example 1 except that the amount of the hyperbranched macromonomer (a3-1) added in Example 1 was changed to 100 ppm. The polymerization average molecular weight Mw was 340,000, and MFR was 4.3 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 7
A styrene resin composition was obtained in the same manner as in Example 1 except that the amount of the hyperbranched macromonomer (a3-1) added in Example 1 was changed to 500 ppm. The polymerization average molecular weight Mw was 460,000, and the MFR was 3.6 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 8
A styrenic resin composition was obtained in the same manner as in Example 2 except that the amount of the hyperbranched macromonomer (a3-2) added in Example 2 was changed to 100 ppm. The polymerization average molecular weight Mw was 310,000, and MFR was 4.4 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.7. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 9
A styrenic resin composition was obtained in the same manner as in Example 2 except that the amount of the hyperbranched macromonomer (a3-2) added in Example 2 was changed to 500 ppm. The polymerization average molecular weight Mw was 430,000, and the MFR was 3.5 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 10
A styrene resin composition was obtained in the same manner as in Example 3 except that the amount of the hyperbranched macromonomer (a3-3) added in Example 3 was 100 ppm. The polymerization average molecular weight Mw was 360,000, and MFR was 4.6 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 11
A styrene resin composition was obtained in the same manner as in Example 3 except that the amount of the hyperbranched macromonomer (a3-3) added in Example 3 was changed to 500 ppm. The polymerization average molecular weight Mw was 510,000, and MFR was 3.3 g / 10 min. Moreover, ratio Mw / Mn of the weight average molecular weight and the number average molecular weight was 3.0. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 12
A styrenic resin composition was obtained in the same manner as in Example 4 except that the amount of the hyperbranched macromonomer (a3-4) added in Example 4 was changed to 100 ppm. The polymerization average molecular weight Mw was 330,000, and MFR was 4.3 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 13
A styrene resin composition was obtained in the same manner as in Example 4 except that the amount of the hyperbranched macromonomer (a3-4) added in Example 4 was changed to 500 ppm. The polymerization average molecular weight Mw was 440,000, and the MFR was 3.2 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 14
A styrenic resin composition was obtained in the same manner as in Example 5 except that the amount of the hyperbranched macromonomer (a3-5) added in Example 5 was changed to 100 ppm. The polymerization average molecular weight Mw was 310,000, and MFR was 4.4 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 15
A styrene resin composition was obtained in the same manner as in Example 5 except that the amount of the hyperbranched macromonomer (a3-5) added in Example 5 was changed to 500 ppm. The average molecular weight Mw was 400,000, and the MFR was 3.4 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 3.3. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 16
A styrene resin composition was obtained in the same manner as in Example 1 except that the amount of butyl acrylate added in Example 1 was 4.5 parts. The polymerization average molecular weight Mw was 330,000, and MFR was 4.2 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 17
A styrene resin composition was obtained in the same manner as in Example 1 except that the amount of butyl acrylate added in Example 1 was 12.5 parts. The polymerization average molecular weight Mw was 440,000, and MFR was 4.0 / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 18
A tylene-based resin composition was obtained in the same manner as in Example 2, except that the amount of butyl acrylate added in Example 2 was 4.5 parts. The polymerization average molecular weight Mw was 320,000, and MFR was 4.0 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.7. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 19
A styrene resin composition was obtained in the same manner as in Example 2 except that the amount of butyl acrylate added in Example 2 was 12.5 parts. The average molecular weight Mw was 430,000, and the MFR was 4.2 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 20
A styrene resin composition was obtained in the same manner as in Example 3 except that the amount of butyl acrylate added in Example 3 was 4.5 parts. The polymerization average molecular weight Mw was 360,000, and MFR was 4.0 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 21
A styrene resin composition was obtained in the same manner as in Example 3 except that the amount of butyl acrylate added in Example 3 was 12.5 parts. Polymerization average molecular weight Mw was 470,000, and MFR was 4.2 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 22
A styrene resin composition was obtained in the same manner as in Example 4 except that the amount of butyl acrylate added in Example 4 was 4.5 parts. The polymerization average molecular weight Mw was 330,000, and MFR was 3.9 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.7. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 23
A styrene resin composition was obtained in the same manner as in Example 4 except that the amount of butyl acrylate added in Example 4 was 12.5 parts. The polymerization average molecular weight Mw was 440,000, and the MFR was 4.1 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 24
A styrene resin composition was obtained in the same manner as in Example 5 except that the amount of butyl acrylate added in Example 5 was 4.5 parts. The polymerization average molecular weight Mw was 310,000, and MFR was 3.7 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 25
A styrene resin composition was obtained in the same manner as in Example 5 except that the amount of butyl acrylate added in Example 5 was 12.5 parts. The polymerization average molecular weight Mw was 460,000, and the MFR was 4.6 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 3.6. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 26
A styrene resin composition was obtained in the same manner as in Example 6 except that the amount of butyl acrylate added in Example 6 was 4.5 parts. The polymerization average molecular weight Mw was 310,000, and MFR was 3.8 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.7. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 27
A styrene resin composition was obtained in the same manner as in Example 6 except that the amount of butyl acrylate added in Example 6 was 12.5 parts. The average molecular weight Mw was 400,000, and the MFR was 4.4 g / 10 minutes. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 28
A styrene resin composition was obtained in the same manner as in Example 7 except that the amount of butyl acrylate added in Example 7 was 4.5 parts. The average molecular weight Mw was 400,000, and the MFR was 3.5 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.8. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 29
A styrene resin composition was obtained in the same manner as in Example 7 except that the amount of butyl acrylate added in Example 7 was 12.5 parts. The polymerization average molecular weight Mw was 580,000, and MFR was 4.1 g / 10 min. Moreover, ratio Mw / Mn of the weight average molecular weight and the number average molecular weight was 3.0. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Example 30
A styrene resin composition was obtained in the same manner as in Example 1 except that the addition amount of the hyperbranched macromonomer (a3-1) in Example 1 was changed to 600 ppm. The polymerization average molecular weight Mw was 520,000, and the MFR was 1.8 g / 10 min. The ratio Mw / Mn of the weight average molecular weight to the number average molecular weight was 2.9. A sheet was produced in the same manner as in Example 1 using the obtained resin composition.

Comparative Example 1
Using the same reactor as in Example 1, 98 parts of styrene, 2 parts of butyl acrylate, 6 parts of ethylbenzene, and 100 parts of the multi-branched macromonomer (a3-1) of Reference Example 1 in total of styrene and butyl acrylate 100 ppm of the polymerization initiator [2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane] was prepared by adjusting a mixed solution of 150 ppm with respect to a total of 100 parts of styrene and butyl acrylate. Polymerization was carried out under the same conditions as in Example 1.

The mixed solution obtained by polymerization was heated with a heat exchanger at 250 ° C., and after removing volatile components under a reduced pressure of 5 kPa, pelletized to obtain a styrene-based resin composition. The obtained styrene resin composition had a weight average molecular weight of 370,000 and a molecular weight distribution (Mw / Mn) of 3.2.
A sheet was produced in the same manner as in Example 1 except that this styrene resin was subjected to the same drawing temperature and heat shrinkage stress as shown in the comparative example. The obtained sheet has sufficient heating time in the radiant heat type pressure-air vacuum forming method and has excellent folding strength, but the MFR is 1.5 g / 10 min and the viscosity is high, so the image clarity of the sheet is insufficient. Met.

Comparative Example 2
Using the same reactor as in Example 1, 98 parts of styrene, 2 parts of butyl acrylate, 7 parts of ethylbenzene, and 100 parts of the multi-branched macromonomer (a3-1) of Reference Example 1 in total of styrene and butyl acrylate 100 ppm, and a polymerization initiator t-butyl peroxybenzoate was prepared by adjusting a mixed solution consisting of 300 ppm with respect to a total of 100 parts of styrene and butyl acrylate, and using an apparatus having lines arranged as shown in FIG. The polymer was continuously polymerized under the conditions.
Feed rate of mixed solution: 9.0 liter / hour Reaction temperature in stirred reactor: 130 ° C
Reaction temperature in circulating polymerization line (I): 130 ° C
Reaction temperature in non-circulation polymerization line (II): 135 to 145 ° C

  The mixed solution obtained by polymerization was heated with a heat exchanger at 260 ° C., and after removing volatile components under a reduced pressure of 5 kPa, pelletized to obtain a styrene resin composition. The obtained resin composition had a weight average molecular weight of 270,000, a ratio Mw / Mn of the weight average molecular weight to the number average molecular weight of 2.2, and MFR of 3.5 g / 10 min. A sheet was produced in the same manner as in Example 1 except that this styrene resin composition was subjected to stretching temperature and heat shrinkage stress as shown in the table. Although the obtained sheet was excellent in image definition and folding strength, the optimum heating time in the radiant heat type compressed air vacuum forming method was very short.

Comparative Example 3
A sheet was produced in the same manner as in Example 1 except that the styrene-based resin composition obtained in Example 1 was used and the ORS and the draw ratio were as shown in the table. Although the obtained sheet was excellent in image definition and folding strength, the optimum heating time in the radiant heat type compressed air vacuum forming method was very short.

Comparative Example 4
A sheet was prepared in the same manner as in Example 1 except that the styrene resin composition obtained in Example 1 was used and the ORS and the draw ratio were changed as shown in the table. The obtained sheet was excellent in image sharpness, and the optimum heating time in the radiant heat type compressed air vacuum forming method was sufficient, but the folding strength was insufficient.

(1): Pusher pump (2): Stirred reactor (3): Gear pump (4): Tubular reactor with static mixing element (5): Tubular reactor with static mixing element (6): Static Tubular reactor with static mixing element (7): gear pump (8): tubular reactor with static mixing element (9): tubular reactor with static mixing element (10): tubular with static mixing element Reactor (I): Circulation polymerization line (II): Non-circulation polymerization line

Claims (5)

A styrene monomer (a1), an acrylate ester (a2), a polymer having a plurality of branches and a weight average molecular weight of 1,000 to 15,000 having a polymerizable double bond at the tip. A biaxially stretched styrene resin sheet obtained by biaxially stretching a styrene resin composition containing a multibranched copolymer (A) obtained by copolymerizing a branched macromonomer (a3). And
The weight average molecular weight (Mw) calculated | required by GPC-MALS method of this composition is 300,000-600,000, and ratio (Mw / Mn) of a weight average molecular weight (Mw) and a number average molecular weight (Mn) is 2. 7 to 4.0, and the use ratio (a1) / (a2) of the styrene monomer (a1) to the acrylate ester (a2) is 87/13 to 96/4 (mass ratio). ,and,
A biaxially stretched styrene resin sheet characterized in that the heat shrinkage stress in the longitudinal and lateral directions of the obtained biaxially stretched styrene resin sheet is in the range of 0.20 MPa to 0.45 MPa.   The biaxially stretched styrene resin sheet according to claim 1, wherein a melt mass flow rate of the styrene resin composition is 2.0 g / 10 min or more.   The usage ratio of the multi-branched macromonomer (a3) is 100 to 1,000 ppm on a mass basis with respect to the total of the styrene monomer (a1) and the acrylate ester (a2). Or the biaxially-stretched styrene resin sheet of 2.   The biaxially stretched styrene resin sheet according to any one of claims 1 to 3, wherein the acrylic ester (a2) is butyl acrylate.   A molded product obtained by subjecting the biaxially stretched styrene resin sheet according to any one of claims 1 to 4 to radiant heating type pressure air vacuum forming.

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