JP3734892B2 - Styrene resin stretched sheet - Google Patents

Description

【００７０】
［比較例１］
製造例４で得られたＡＰＳシートを用いた以外は、実施例５と同様に行った。結果を表２に示す。
【００７１】
［比較例２］
製造例３で得られたＳ／Ａ＝１００／０シートを用いた以外は、実施例５と同様に行った。結果を表２に示す。
【００７２】
［比較例３］
製造例５で得られたＳ／Ａ＝２０／８０の十分結晶化したシートを用いた以外は、実施例５と同様に行った。結晶化したシートは脆く、延伸できなかった。結果を表２に示す。
【００７３】
［比較例４］
製造例３で得られたＳ／Ａ＝２０／８０シートを用い、２軸延伸時の原反表面温度を１１５℃とした以外は、実施例１と同様に行った。結果を表２に示す。
【００７４】
［比較例５］
製造例３で得られたＳ／Ａ＝２０／８０シートを用い、２軸延伸時の原反表面温度を１３５℃とした以外は、実施例１と同様に行った。結果を表２に示す。
【００７５】
［比較例６］
製造例３で得られたＳ／Ａ＝３０／７０シートを用い、２軸延伸時の原反表面温度を１３５℃とした以外は、実施例１と同様に行った。結果を表２に示す。
【００７６】
【表２】

【００７７】
【発明の効果】
以上の如く本発明におけるスチレン系樹脂組成物のシートは、伸長粘度特性に優れ、十分なレベルで結晶化が進行し、延伸時の破断がなく、熱収縮率が小さく、食品包装材料等の包装材料、電気・電子用材料、その他産業用資材に有効な利用が期待できる。
【図面の簡単な説明】
【図１】実施例３に用いた樹脂組成物の非線形パラメーター（λ）の算出例を示す図である。
【図２】比較例３に用いた樹脂組成物の非線形パラメーター（λ）の算出例を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention is excellent in elongational viscosity characteristics, excellent in gloss, transparency, visible light transmittance, etc., and retains characteristics such as low water absorption rate and low moisture absorption rate, and has a thermal shrinkage rate, crystallinity, and uneven thickness. The present invention relates to a sheet of improved styrene resin composition and a method for producing the same.
[0002]
[Prior art]
Conventionally, polystyrene sheets have excellent characteristics such as gloss, transparency, and visible light transmittance, and have a low water absorption rate and low moisture absorption rate, and have been widely used as various packaging materials. Therefore, it is widely used as an electrical insulating material for capacitors, high frequency cable insulation, polyvaricon, and other insulation.
[0003]
In recent years, syndiotactic polystyrene sheets and films have been developed. For example, a heat-resistant sheet and film using syndiotactic polystyrene disclosed in Japanese Patent Application Laid-Open No. 62-187708 is disclosed in Japanese Patent Publication No. 6-104337. Although it has been proposed, since syndiotactic polystyrene tends to break during stretching, it cannot be stretched at a high magnification, and there is a problem that uneven thickness occurs when stretched at a low magnification. Moreover, in order to advance crystallization in order to provide heat resistance, the heat setting process at the temperature higher than a cold crystallization temperature is required.
[0004]
JP-B-7-88430 describes a stretched film having an improved elastic modulus, but its production method shows that the elastic modulus is improved by stretching in various temperature ranges including the cold crystallization temperature. There is no mention of crystallization and the film uniformity is not sufficient. Japanese Patent Laid-Open No. 5-200858 proposes an improvement in heat shrinkage, but the thickness uniformity is not sufficient, and there is no description about crystallization.
[0005]
In addition, in order to improve moldability at low temperatures, it may be possible to add atactic polystyrene, and a composition comprising atactic polystyrene and syndiotactic polystyrene will improve shrinkage, heat resistance and printability. Is disclosed in Japanese Patent Application Laid-Open No. 7-20785, but the film uniformity has not been improved and crystallization has not been achieved.
[0006]
On the other hand, the Journal of the Japan Rheology Society,1113 (1983), Journal of the Japanese Society of Rheology,1393 (1985) describe polystyrene, polyethylene and the like excellent in elongational viscosity characteristics, both of which are branched polymers and polymers containing ultrahigh molecular weight components, and are attackable by adding a small amount of syndiotactic polystyrene. There has been no report on imparting elongational viscosity characteristics of tic polystyrene.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a stretched sheet having excellent elongation viscosity characteristics, crystallization progressing at a sufficient level, stretchability, that is, no breakage during stretching, excellent thickness uniformity, and less heat shrinkage. .
[0008]
[Means for Solving the Problems]
As a result of intensive research to develop a styrene resin sheet having the above-mentioned preferable properties, the present inventor has obtained from a styrene polymer having a specific proportion of a syndiotactic structure and a styrene polymer having an atactic structure. A raw sheet is formed so that the amorphous fixing ratio specified by a specific formula is equal to or greater than a predetermined value, and the raw sheet is stretched under specific conditions, The present inventors have found that the object can be achieved, and have completed the present invention based on this finding.
[0009]
That is, the first of the present invention is a resin having a composition of (a) 1 to 49% by weight of a styrene polymer having a syndiotactic structure and (b) 51 to 99% by weight of a styrene polymer having an atactic structure. A stretched sheet made of a styrene resin, comprising a composition, having a heat shrinkage rate of 3% or less, a crystallinity Xc of 0.4 or more, and a thickness unevenness Dt of less than 5%.
[0010]
The second of the present invention has a composition of (a) 1 to 49% by weight of a styrene polymer having a syndiotactic structure and (b) 51 to 99% by weight of a styrene polymer having an atactic structure. It is made of a resin composition having a nonlinear parameter (λ) of elongation viscosity of 10 or more, a heat shrinkage rate of 3% or less, a crystallinity Xc of 0.4 or more, and a thickness unevenness Dt of less than 5%. A stretched sheet made of styrenic resin is provided.
[0012]
The present invention will be described in detail below. The syndiotactic structure as used in the present invention is a syndiotactic structure mainly having a syndiotactic structure, that is, a phenyl group or a substituted phenyl group which is a side chain with respect to a main chain formed from a carbon-carbon bond is alternately in the opposite direction. It has a three-dimensional structure located at, and its tacticity is an isotope carbon nuclear magnetic resonance method (¹³C-NMR method). The tacticity measured by this method can be indicated by the abundance ratio of a plurality of consecutive structural units, for example, a dyad for two, a triad for three, a pentad for five.
[0013]
In the present invention, the “styrene polymer having a syndiotactic structure” (hereinafter referred to as syndiotactic polystyrene) is usually 75% or more by dyad, preferably 85% or more, or 30% or more by pentad, Preferably, it is a polymer having a syndiotacticity of 50% or more, and a styrene, alkyl styrene, halogenated styrene, alkoxy styrene, vinyl benzoic acid homopolymer and a mixture thereof, or a monomer component thereof as a main component. It means a copolymer.
[0014]
Examples of the alkyl styrene include methyl styrene, ethyl styrene, isopropyl styrene, and tertiary butyl styrene. Examples of the halogenated styrene include chlorostyrene, bromostyrene, and fluorostyrene. Examples of alkoxystyrene include methoxystyrene, ethoxystyrene, and tertiary butoxystyrene. Of these, polystyrene, p-methylstyrene, m-methylstyrene, p-tertiary butylstyrene, p-chlorostyrene, m-chlorostyrene, p-fluorostyrene homopolymer, and further styrene Mention may be made of copolymers with p-methylstyrene.
[0015]
The syndiotactic polystyrene used in the present invention generally has a weight average molecular weight of 5,000 or more, preferably 10,000 to 20,000,000, a number average molecular weight of 2,500 or more, preferably 5,000 to 10,000, If the polymer is deashed with an acid or alkali washing solution after polymerization, and further washed and dried, a styrenic polymer with extremely high syndiotacticity can be obtained.
[0016]
Syndiotactic polystyrene as described above is mainly obtained by polymerizing a styrene monomer and / or a substituted styrene monomer in the presence of a catalyst composed of a titanium compound and an alkylaluminoxane, for example, in an inert hydrocarbon solvent or in the absence of a solvent. Can be manufactured.
[0017]
There are various titanium compounds used as the catalyst, but preferably the general formula TiR¹ _aR² _bR³ _cX¹ _{4- (a + b + c)}Or TiR¹ _dR² _eX¹ _{3- (d + e)}[Wherein R¹, R²And R³Are each hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an arylalkyl group, an acyloxy group having 1 to 20 carbon atoms, and cyclopenta A dienyl group, a substituted cyclopentadienyl or indenyl group;¹Represents halogen. a, b and c each represents an integer of 0 to 4, and d and e each represents an integer of 0 to 3. And at least one compound selected from the group consisting of titanium chelate compounds. Moreover, you may use the said titanium compound which formed the complex with ester, ether, etc.
[0018]
On the other hand, the alkylaluminoxane constituting the main component of the catalyst together with the titanium compound is obtained by contacting various organoaluminum compounds with a condensing agent.
[0019]
Various organoaluminum compounds can be used, but trialkylaluminum is usually used. Examples of the trialkylaluminum include trimethylaluminum, triethylaluminum, and tri-i-butylaluminum. These organoaluminum compounds may be used alone or in combination with a condensing agent. A typical example of the condensing agent is water, but any other condensing agent for the organoaluminum compound may be used. The reaction between the organoaluminum compound and water is not particularly limited, and may be performed according to a known method. Typical examples of the alkylaluminoxane obtained by the reaction of an organoaluminum compound and water include a chain alkylaluminoxane and a cyclic alkylaluminoxane. In addition, unreacted trialkylaluminum, a mixture of various condensation products, There are molecules in which they are complexly associated, and these become various products depending on the contact conditions between trialkylaluminum and water. In addition, when using an alkylaluminoxane as a catalyst, you may use 1 type, 2 or more types, and you may mix an organoaluminum compound. Furthermore, other organometallic compounds can be mixed, or an alkylaluminoxane can be used by being adsorbed or supported on an inorganic substance.
[0020]
When the above-described titanium compound and alkylaluminoxane are the main components, the ratio varies depending on the type of each component, the raw material styrene, the type of styrene derivative, and other conditions, but is not uniquely determined. Ratio of aluminum in alkylaluminoxane to titanium in titanium compound, that is, 1 to 10 as aluminum / titanium (molar ratio)⁶, Preferably 10-10⁴It is.
[0021]
Further, in the present invention, styrene or a styrene derivative is polymerized in the presence of the main component catalyst, but the polymerization may be bulky, an aliphatic hydrocarbon such as pentane, hexane or heptane, an alicyclic hydrocarbon such as cyclohexane or the like. You may carry out in aromatic hydrocarbon solvents, such as benzene, toluene, and xylene. Further, the polymerization temperature is not particularly limited, but it can usually be carried out at 0 to 120 ° C.
[0022]
In addition, the styrene polymer having an atactic structure used in the present invention (hereinafter referred to as atactic polystyrene) is industrially obtained by radical polymerization by a method such as bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization. Polystyrene. Polystyrene obtained by such radical polymerization usually has an atactic structure and does not have stereoregularity. The atactic polystyrene used herein is a polymer composed of one or more aromatic vinyl compounds, or a copolymer of one or more other vinyl monomers copolymerizable with one or more aromatic vinyl compounds. A polymer, a hydrogenated polymer of these polymers, and a mixture thereof may be used.
[0023]
Preferred aromatic vinyl compounds used herein include styrene, α-methylstyrene, methylstyrene, ethylstyrene, isopropylstyrene, tertiary-butylstyrene, phenylstyrene, vinylstyrene, chlorostyrene, bromostyrene, fluorostyrene, chloro There are methyl styrene, methoxy styrene, ethoxy styrene and the like, and these are used alone or in combination. Among these, more preferred aromatic vinyl compounds are styrene, p-methylstyrene, m-methylstyrene, p-tertiary butylstyrene, p-chlorostyrene, m-chlorostyrene, and p-fluorostyrene.
[0024]
Other vinyl monomers that can be copolymerized include vinylcyan compounds such as acrylonitrile and methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, Acrylic acid alkyl esters such as cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, Octadecylmetac Methacrylate, alkyl methacrylate such as phenyl methacrylate, benzyl methacrylate, maleimide, N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (p There are maleimide compounds such as -bromophenyl) maleimide.
[0025]
The molecular weight of the atactic polystyrene is not particularly limited, but those having a weight average molecular weight of 100,000 or more are generally used. Preferably, it is 250,000 or more and 350,000 or less. Here, when the weight average molecular weight is less than 100,000, the thermal properties and mechanical properties of the obtained molded product are deteriorated, which is not preferable.
[0026]
Moreover, there is no restriction | limiting of a molecular weight distribution, and various things can be applied.
[0027]
In the styrenic resin composition used in the present invention, the blending amount of the syndiotactic polystyrene as the component (a) is 1 to 49% by weight, preferably 3 to 45% by weight, more preferably 5 to 30% by weight. The blending amount of the atactic polystyrene as the component (b) is 51 to 99% by weight, preferably 55 to 97% by weight, more preferably 70 to 95% by weight. If the amount of syndiotactic polystyrene is more than 49% by weight, the cold crystallization temperature will be low, so when the raw sheet is stretched, crystallization partially proceeds due to annealing, which inhibits crystallization due to stretch orientation. However, uniform stretching becomes difficult. On the other hand, if the amount of syndiotactic polystyrene is less than 1% by weight, sufficient elongational viscosity characteristics cannot be obtained, and crystallization by uniform and effective stretching orientation cannot be performed.
[0028]
Further, the extensional viscosity represents a viscosity that resists the deformation at a stage where the strain amount is large with the deformation of the resin. This elongational viscosity characteristic is closely related to the good stretchability, thickness unevenness, crystallinity, and heat shrinkage of the sheet. This non-linear parameter (λ) of elongational viscosity is 130 ° C, constant strain rate 0.02 seconds^-1Slope of the first-order approximate straight line in the non-linear region in the time-elongation viscosity curve (logarithmic plot) obtained by uniaxial extensional viscosity measurement under conditions (m₁) And the slope of the first-order approximation line in the linear region (m₂) (Λ = m₁/ M₂). The nonlinear parameter (λ) is preferably 10 or more, more preferably 30 or more, and desirably 50 or more. When the nonlinear parameter is smaller than these ranges, crystallization by uniform and effective stretch orientation cannot be performed.
[0029]
Further, in the present invention, the styrene resin composition includes various additive components such as an antioxidant, a nucleating agent, a plasticizer, a release agent, a flame retardant, a pigment, carbon black, and the like within a range that does not impair the object of the present invention. In addition, additives such as antistatic agents or other thermoplastic resins can be blended, and reinforcing materials such as inorganic fillers can be blended.
[0030]
In the styrenic resin composition used in the present invention, various mixing methods such as melt-kneading syndiotactic polystyrene and atactic polystyrene, and kneading after dissolving in a solvent can be used. As the melt-kneading, a known melt-kneading apparatus such as a single screw extruder or a twin screw extruder can be used, but a vented twin screw extruder is preferable. The melt-kneading temperature when each component is melt-kneaded is usually set in the range of 270 to 370 ° C, preferably in the range of 280 to 330 ° C. When the melt kneading temperature is lower than 270 ° C., the raw material becomes insufficiently melted, so that a uniform composition cannot be obtained. A melt kneading temperature higher than 370 ° C. is not preferable because decomposition of the raw material occurs. As a method of mixing after dissolving in a solvent, the present styrene-based resin composition can be obtained by a method of dissolving both syndiotactic polystyrene and atactic polystyrene and then distilling off the solvent.
[0031]
In the method of the present invention, first, the styrenic resin composition thus obtained is molded into a raw sheet having an amorphous fixing ratio (Hcc / Hm) of 0.7 or more, preferably 0.8 or more. To do. There is no particular limitation on the method for forming the raw sheet having an amorphous fixing ratio of 0.7 or more, but usually in the range of 270 to 370 ° C, preferably in the range of 280 to 330 ° C, press or T-die, circular. Styrenic resin composition having an amorphous fixed ratio of 0.7 or more by thermoforming using a die or the like, and preferably cooled at a temperature lowering temperature of 150 ° C./min or more using a cooling press or a cooling roll or a cooling tank. An original sheet of material is obtained. At this time, if the cooling rate is low, crystallization proceeds, and the amorphous fixing ratio of the original fabric becomes 0.7 or less. From such an original fabric, it is difficult to obtain a stretched sheet with improved target thickness uniformity. Note that the amorphous fixation ratio is determined by the crystallization exothermal enthalpy ΔHcc (J / g), which is an irreversible process measured by a dynamic differential scanning calorimeter (D-DSC), and the melting endothermic enthalpy of a crystal, which is a reversible process. The ratio to ΔHm (J / g) is defined by ΔHcc / ΔHm.
[0032]
Further, there is no particular limitation on the stretching method of the raw sheet having an amorphous fixed ratio of 0.7 or more, and conventionally used methods such as a rolling method, a tenter stretching method, a roll stretching method, a bubble stretching method, etc. Stretching can be performed 2 to 6 times in the axial direction using a method such as simultaneous or sequential biaxial stretching or uniaxial stretching, but the stretching temperature is extremely important.
[0033]
The stretching temperature of the raw fabric sheet is stretched in a very narrow temperature range of the raw fabric surface temperature of 120 to 135 ° C. By doing so, a sheet having a crystallinity Xc of 0.4 or more can be obtained. The crystallinity Xc here is defined by the following equation.
[0034]
Xc = 1−ΔHcc ′ / ΔHm ′
Here, Hcc ′ and Hm ′ are the cold crystallization enthalpy and reversible endotherm measured as an irreversible exothermic peak when the stretched sheet was measured with a dynamic differential scanning calorimeter (D-DSC), respectively. The melting enthalpy measured as the peak.
[0035]
In the production method of the present invention, if the stretching temperature of the raw sheet is less than 120 ° C., breakage or the like occurs during stretching, and if it is 135 ° C. or more, the molecular chain oriented by stretching relaxes, and sufficient oriented crystals Can not be obtained. That is, the crystallinity Xc is less than 0.4.
[0036]
Moreover, if the stretched sheet is heat-set at a temperature equal to or higher than the cold crystallization temperature, the thickness uniformity of the sheet decreases. The cold crystallization temperature of syndiotactic polystyrene is about 140 ° C, and when adding atactic polystyrene, the cold crystallization temperature rises. The problem of unevenness does not occur.
[0037]
A feature of the present invention is that a limited amount of syndiotactic polystyrene is blended with atactic polystyrene, and the resin composition once melted is cooled and solidified without sufficiently crystallizing, so that it does not exist in atactic polystyrene. Excellent stretch viscosity characteristics at low temperatures (100 to 200 ° C.) can be imparted, and a specific raw sheet is formed and stretched in an extremely narrow raw surface temperature range, thereby exhibiting the stretch viscosity characteristics and effective. This is because a highly oriented crystallization is achieved, and a sheet having a small thickness nonuniformity and a small thermal shrinkage rate is obtained due to its excellent stretchability.
[0038]
In addition, the stretched sheet here may be called a stretched film depending on the thickness.
[0039]
【Example】
Hereinafter, the present invention will be described in more detail with reference to production examples, examples, and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist thereof.
[0040]
Various physical properties used in Examples and Comparative Examples of the present invention were measured based on the following test methods.
[0041]
(1) Nonlinear parameter of elongational viscosity (λ)
Using a Meissner type uniaxial elongational viscosity apparatus (Melten rheometer manufactured by Toyo Seiki Co., Ltd.), temperature: 130 ° C., constant strain rate: 0.02 seconds^-1The measurement was performed under the conditions, and the nonlinear parameter was defined by the following equation.
[0042]
Nonlinear parameter (λ) = m₁/ M₂
m₁: Constant strain rate 0.02 seconds^-1The slope m of the first-order approximation line of the nonlinear region in the time-elongation viscosity curve (logarithmic plot) determined by measurement under the conditions₂: M₁Slope of linear approximation line in the same curve (logarithmic plot)
That is, λ indicates the degree of rising immediately before cutting of the time-extension viscosity curve, and the greater the value, the better the extension viscosity characteristic. 1 and 2 show measurement examples.
[0043]
FIG. 1 is a diagram showing a calculation example of the nonlinear parameter (λ) of Example 3 described later, and FIG. In the figure, the solid line is a time-elongation viscosity curve obtained by the above measurement, and the dotted line is a linear approximation line in the nonlinear region and the linear region.
[0044]
(2) Amorphous fixation ratio
A raw DSC is used as a sample, and a dynamic DSC (TAC DSC2920
Using Modulated DSC), the heating rate was 5 ° C./min. , Amplitude 0.5 deg. Measured under the condition of a vibration period of 60 seconds and defined by the following equation.
[0045]
Amorphous fixing ratio = △ Hcc / △ Hm
ΔHcc: Cold crystallization enthalpy obtained as an irreversible process (J / g)
ΔHm: melting enthalpy of crystals obtained as a reversible process (J / g)
[0046]
(3) Evaluation of thickness uniformity
The thickness of the sheet obtained by stretching was measured at nine locations with a film microgauge, thickness unevenness (Dt) was defined by the following formula, and the stretchability was evaluated based on Dt.
[0047]
○: Dt is less than 5%
X: Dt is 5% or more
Dt (%) = (t_max-T_min) / T_av× 100
t_max: Maximum thickness among 9 thicknesses
t_min: Minimum thickness among 9 thicknesses
t_av: Average thickness at 9 locations
[0048]
(4) Crystallinity Xc
A stretched sheet was used as a sample, and a dynamic DSC (DSC2920 Modulated DSC manufactured by TA) was used, and the temperature rising rate was 5 ° C./min. , Amplitude 0.5 deg. Measured under the condition of a vibration period of 60 seconds and defined by the following equation.
[0049]
Crystallinity Xc = 1−ΔHcc / ΔHm
ΔHcc: Cold crystallization enthalpy obtained as an irreversible process (J / g)
ΔHm: melting enthalpy of crystals obtained as a reversible process (J / g)
[0050]
(5) Thermal shrinkage (%)
The stretched sheet was cut into a strip of 70 × 10 mm, the distance between the marked lines was 50 mm, suspended in an oven set at 120 ° C. for 15 minutes with no load, and the distance (Lmm) between the marked lines after removal was measured.
[0051]
Thermal contraction rate (%) = (50−L) / 50 × 100
[0052]
[Production Example 1]
Production of syndiotactic polystyrene (abbreviated as SPS):
KRC manufactured by Kurimoto Iron Works as the reactor (inner volume 8.6 liters, blade diameter 100 mm, effective cylinder length 1000 mm, number of paddles 44 pairs, clearance 1 mm between cylinder inner wall and paddle) is inclined 5 degrees, and the internal temperature is 80 ° C. And the rotational speed was 60 rpm.
[0053]
While supplying styrene monomer to this reactor at a rate of 1 liter per hour, polymerization was conducted for 5 hours while supplying methylaluminoxane as a catalyst at a rate of 75 mmol per hour and pentamethylcyclopentadienyltitanium trimethoxide at a rate of 0.15 mmol per hour. Carried out.
[0054]
The obtained syndiotactic polystyrene was 2950 g, and the reaction rate was 65.6%. The syndiotacticity of the polymer in racemic pentad was 97%.
[0055]
[Production Example 2]
Production of Syndiotactic Polystyrene (SPS) / Atactic Polystyrene (abbreviated as APS) Resin Composition
The SPS obtained in Production Example 1 was extruded at 290 ° C. using a vented twin screw extruder and passed through a cooling water bath to obtain pellets (sample name: S / A = 100/0). After blending so that the obtained SPS pellets were 5 wt% and APS (GP685 manufactured by Asahi Kasei) was 95 wt%, the pellets were obtained by extrusion at 290 ° C. using a vented twin screw extruder (sample) (sample) Name: S / A = 5/95). Similarly, pellets with S / A = 10/90, S / A = 20/80, and S / A = 30/70 were obtained.
[0056]
    [Production Example 3]
  Production of Syndiotactic Polystyrene (SPS) / Atactic Polystyrene (APS) Resin Composition Raw Material Sheet S / A = 5/95 Pellets were pressed with a compression molding machine at 280 ° C. for 4 minutes, and then rapidly cooled with a water bath. A raw sheet having a thickness of 1 mm was obtained. Similarly, S / A = 10/90, S / A = 20/80, S / A =30/70A raw sheet with S / A = 100/0 was obtained.
[0057]
In order to prepare a sample for measuring extensional viscosity, the press sheet was cut into a thickness of 1 mm, a width of 1 mm, and a length of 200 mm. Using this sample, 130 ° C, strain rate 0.02 seconds^-1The elongational viscosity was measured at.
[0058]
[Production Example 4]
Manufacture of atactic polystyrene (APS) raw sheet
The GP685 pellets were pressed at 250 ° C. for 4 minutes with a compression molding machine and then rapidly cooled with a water bath to obtain a raw sheet having a thickness of 1 mm.
[0059]
The elongational viscosity was measured in the same manner as in Production Example 3.
[0060]
[Production Example 5]
Production of raw sheet of syndiotactic polystyrene (SPS) / atactic polystyrene (APS) resin composition
After pressing S / A = 20/80 pellets with a compression molding machine at 280 ° C. for 4 minutes, the temperature control switch is turned off and the sheet is gradually cooled for 17 hours, leaving a raw sheet with a thickness of 1 mm. Obtained.
[0061]
The elongational viscosity was measured in the same manner as in Production Example 3.
[0062]
[Example 1]
The S / A = 5/95 sheet obtained in Production Example 3 was mounted on a Toyo Seiki biaxial stretching test apparatus X4HD-HT type which was previously set to have a raw surface temperature of 125 ° C., and after preheating for 5 minutes The biaxial stretching was performed 3 × 3 times at a strain rate of 12500% / min, and after the stretching was forcibly cooled with cold air. The crystallinity, shrinkage rate, and thickness unevenness of the obtained sheet were measured. The results are shown in Table 1.
[0063]
[Example 2]
The same operation as in Example 1 was performed except that the S / A = 10/90 sheet obtained in Production Example 3 was used. The results are shown in Table 1.
[0064]
[Example 3]
The same operation as in Example 1 was performed except that the S / A = 20/80 sheet obtained in Production Example 3 was used. The results are shown in Table 1.
[0065]
[Example 4]
The same operation as in Example 1 was performed except that the S / A = 30/70 sheet obtained in Production Example 3 was used. The results are shown in Table 1.
[0066]
[Example 5]
This was carried out in the same manner as in Example 1 except that the S / A = 10/90 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was 130 ° C. The results are shown in Table 1.
[0067]
[Example 6]
The same procedure as in Example 1 was performed except that the S / A = 20/80 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was 130 ° C. The results are shown in Table 1.
[0068]
[Example 7]
The same procedure as in Example 1 was performed except that the S / A = 30/70 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was 130 ° C. The results are shown in Table 1.
[0069]
[Table 1]

[0070]
[Comparative Example 1]
The same operation as in Example 5 was performed except that the APS sheet obtained in Production Example 4 was used. The results are shown in Table 2.
[0071]
[Comparative Example 2]
The same operation as in Example 5 was performed except that the S / A = 100/0 sheet obtained in Production Example 3 was used. The results are shown in Table 2.
[0072]
[Comparative Example 3]
The same procedure as in Example 5 was performed except that the sufficiently crystallized sheet of S / A = 20/80 obtained in Production Example 5 was used. The crystallized sheet was brittle and could not be stretched. The results are shown in Table 2.
[0073]
[Comparative Example 4]
The same procedure as in Example 1 was performed except that the S / A = 20/80 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was 115 ° C. The results are shown in Table 2.
[0074]
[Comparative Example 5]
This was carried out in the same manner as in Example 1 except that the S / A = 20/80 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was set to 135 ° C. The results are shown in Table 2.
[0075]
[Comparative Example 6]
The same procedure as in Example 1 was performed except that the S / A = 30/70 sheet obtained in Production Example 3 was used and the surface temperature of the original fabric during biaxial stretching was set to 135 ° C. The results are shown in Table 2.
[0076]
[Table 2]

[0077]
【The invention's effect】
As described above, the sheet of the styrenic resin composition in the present invention is excellent in elongational viscosity characteristics, crystallized at a sufficient level, has no breakage during stretching, has a small heat shrinkage rate, and is packed in food packaging materials and the like. Effective use for materials, electrical / electronic materials, and other industrial materials can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram showing a calculation example of a nonlinear parameter (λ) of a resin composition used in Example 3.
FIG. 2 is a diagram showing a calculation example of a nonlinear parameter (λ) of a resin composition used in Comparative Example 3.

Claims (2)

(A) a resin composition having a composition of styrene polymer 51-99 wt% having a styrene-based polymer 1 to 49 wt% and the (b) atactic structure having a syndiotactic structure, 5 at 120 ° C. A stretched sheet made of a styrenic resin, having a heat shrinkage rate of 3% or less per minute, a crystallinity Xc of 0.4 or more, and a thickness unevenness Dt represented by the following formula of less than 5%.
Dt (%) = (t _max −t _min ) / t _av × 100
t _max : measured maximum thickness
t _min : measured minimum thickness
t _av : average thickness measured It has a composition of (a) 1 to 49% by weight of a styrenic polymer having a syndiotactic structure and (b) 51 to 99% by weight of a styrenic polymer having an atactic structure . Nonlinear elongational viscosity defined by the ratio (m ₁ / m ₂ ) of the slope (m ₂ ) of the first-order approximation line in the nonlinear region to the slope (m ₁ ) of the first-order approximation line in the linear region under the condition of 02 sec- ¹ parameter (lambda) is a resin composition is 10 or more, at 5 minutes of thermal shrinkage rate at 120 ° C. 3% or less, and crystallinity Xc is 0.4 or more, and uneven thickness Dt of the following formula Is a stretched sheet made of a styrenic resin, characterized by being less than 5%.
Dt (%) = (t _max −t _min ) / t _av × 100
t _max : measured maximum thickness
t _min : measured minimum thickness
t _av : average thickness measured

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