JP2000000886A - Inflation film of styrene resin and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inflation film of a styrene resin as a packaging material which is excellent in dimensional stability, water resistance, and mechanical strength, has good dead holding properties and a method for producing the film. SOLUTION: A styrene resin film is obtained by inflation-molding a material containing syndiotactic polystyrene. The crystallinity of the film is 30 % or more, and the elongation at break is 10% or more. The film is produced under specified conditions when the crystallization temperature (Tc) of the material is 236 deg.C or above, or 236 deg.C or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin film and a method for producing the same, and more particularly, to a styrene polymer having a syndiotactic structure (hereinafter simply referred to as "syndiotactic polystyrene" or "S
PS ". ) Or a resin composition thereof, and an SPS blown film having specific properties and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, not only paper but also aluminum foil and cellophane have been used for various purposes as a packaging material. Sex. Dead-hold property means the property of maintaining a folded state when a certain packaging material is folded,
If the dead-hold property is poor, it will be released immediately after packaging, and will not serve as a packaging material. On the other hand, even if it is excellent in that it cannot be unraveled, it is not suitable as a packaging material when a considerable force must be applied to fold it or it is cut at a fold.

As the packaging material, not only the dead-hold property but also dimensional stability, water resistance, strength and the like are important required characteristics, and a packaging material satisfying these various characteristics is desired. Was. Conventionally, aluminum foil used as a packaging material is excellent in heat resistance and dead-hold property, but has a problem that pinholes are easily generated.
Paper is excellent in heat resistance and dead hold property, but is remarkably inferior in water resistance. Cellophane is also excellent in heat resistance and dead hold property, but has a problem that physical properties change due to humidity. In view of such a problem, as a base material having excellent heat resistance, water resistance and dead hold property, a material obtained by laminating a polystyrene film having a syndiotactic structure and paper having excellent heat resistance and chemical resistance has been proposed. (JP-A-04-255350).

However, it is inevitable that the laminate of resin and paper becomes expensive, and there is a problem in terms of versatility.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above viewpoints, and is excellent in dimensional stability, water resistance and mechanical strength, and further has a polystyrene as a packaging material having a good dead-hold property. It is an object of the present invention to provide a system blown film and a method for producing the same.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a specific blown film mainly composed of a styrenic polymer having a syndiotactic structure and a resin composition containing the polymer has been obtained. It has been found that it has dimensional stability and water resistance, and is excellent in mechanical strength and dead-hold property. The present invention has been completed based on such findings.

That is, the present invention provides the following styrene resin blown film and a method for producing the same. (1) A film obtained by inflation molding a styrene-based polymer mainly having a syndiotactic structure or a resin composition containing a styrene-based polymer mainly having a syndiotactic structure, and having a crystallinity of 30% or more. And a styrene-based resin film having a breaking elongation of 10% or more. (2) a resin composition containing a styrenic polymer mainly having a syndiotactic structure is 1 to 98% by weight of a styrenic polymer mainly having a syndiotactic structure;
The styrene resin film according to the above (1), comprising 99 to 2% by weight of a polyethylene and / or rubber-like elastic body. (3) The crystallization temperature (T at a cooling rate of 20 ° C./min.
c) a styrene-based resin having a syndiotactic structure or a composition thereof having a temperature of 236 ° C. or more,
The styrene resin film according to the above (1) or (2), wherein the styrene resin film is extruded from an annular die after being melted at a temperature of up to 320 ° C. and blown at a blow ratio of 1.5 or more and a draw ratio of 5 or more. Production method. (4) The crystallization temperature (T
a) a styrenic resin having a predominantly syndiotactic structure or a composition thereof,
After melting at ~ 320 ° C, extruding from a circular die at a die exit speed of 3.0m / min or less, blow ratio of 2.0 or more, draw ratio of 10 or more, bubble surface temperature of (Tc-80) ° C or more, (Tc +
20) The above (1), characterized in that blowing is performed at a temperature of not more than ° C.
Or the method for producing a styrene resin film according to (2). (5) The method for producing a styrene resin film according to the above (3) or (4), wherein the film is folded at a surface temperature of 70 to 130 ° C. after blowing. Method.

[0008]

Embodiments of the present invention will be described below. I. Styrene-based resin blown film The styrene-based resin blown film according to the present invention is obtained by molding a styrene-based polymer mainly having a syndiotactic structure or a resin composition containing the styrene-based polymer described below by an inflation molding method. Can be obtained. 1. Styrene polymer mainly having a syndiotactic structure Syndiotactic structure in a styrene polymer mainly having a syndiotactic structure means that the stereochemical structure is a syndiotactic structure, that is, a main chain formed from carbon-carbon bonds. Has a steric structure in which phenyl groups, which are side chains, are alternately located in opposite directions, and its tacticity is determined by nuclear magnetic resonance (13C)
-NMR). Tacticity measured by the 13C-NMR method can be represented by the existence ratio of a plurality of continuous structural units, for example, a dyad for two, a triad for three, and a pentad for five. The styrenic polymer having a predominantly syndiotactic structure as referred to in the present invention generally means at least 75%, preferably at least 85%, in racemic diad, or at least 30%, preferably 50%, in racemic pentad.
Polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (halogenated alkylstyrene), poly (alkoxystyrene), poly (vinylbenzoic acid ester) having the above syndiotacticity, and hydrogenation It refers to a coalescence, a mixture thereof, or a copolymer containing these as a main component. Here, poly (alkylstyrene) includes poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiarybutylstyrene), poly (phenylstyrene), poly (vinylnaphthalene) , Poly (vinylstyrene), and the like, and poly (halogenated styrene) includes poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), and the like. As poly (halogenated alkylstyrene), poly (chloromethylstyrene)
Examples of the poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

Among these, preferred styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), and poly (p-chlorostyrene). ), Poly (m-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene and copolymers containing these structural units. A particularly preferred styrene-based polymer includes a styrene-p-methylstyrene copolymer containing 3 to 20 mol% of a p-methylstyrene repeating unit.

Such a styrenic polymer having a predominantly syndiotactic structure can be prepared, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent.
It can be produced by polymerizing a styrene-based monomer (a monomer corresponding to the above-mentioned styrene-based polymer) (JP-A-62-187708). For poly (halogenated alkylstyrene), see JP-A-1-4691.
No. 2, these hydrogenated polymers are disclosed in JP-A-1-1785.
It can be obtained by the method described in JP-A-05-2005. 2. Resin composition containing syndiotactic polystyrene As the material for molding a styrene-based resin blown film according to the present invention, not only syndiotactic polystyrene but also a resin composition containing syndiotactic polystyrene may be used as the molding material. Can be. In this resin composition, (1) syndiotactic polystyrene may be contained as a resin component, and as other resin components, a rubber-like elastic body and / or a thermoplastic resin other than syndiotactic polystyrene are cited. Can be As the resin component, 3 units of p-methylstyrene repeating units were used as syndiotactic polystyrene.
It is preferable to use a styrene-p-methylstyrene copolymer containing up to 20 mol%, and to use a branched-chain polymer such as a high-pressure low-density polyethylene as a thermoplastic resin other than syndiotactic polystyrene. In this case, the rubber-like elastic body is not particularly limited, and may be appropriately selected from those described below.

Further, (2) an inorganic filler, and (3) various additives such as an antiblocking agent, an antioxidant, a nucleating agent, an antistatic agent, a process oil, a plasticizer, a release agent, a flame retardant, Flame retardant aids, pigments and the like can be blended. Also, regarding kneading of each of the above components, a method of blending and melt-kneading at any stage of the syndiotactic polystyrene production process, a method of blending and kneading each component constituting the composition, and a method of forming a blown film. Various methods such as dry blending and kneading in an extruder of an inflation molding machine may be used. (1) Resin component Regarding the blending ratio in the resin component, syndiotactic polystyrene is 10 to 98% by weight, preferably 2% by weight.
0 to 98% by weight, more preferably 40 to 98% by weight, and the total amount of the rubbery elastic body and / or the thermoplastic resin other than syndiotactic polystyrene is 2 to 90% by weight, preferably 2 to 80% by weight, Furthermore, it is 2 to 60% by weight.

Specific examples of the rubber-like elastic material include, for example, natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiochol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber Styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer ( SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SI
S), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), or ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPD)
M), an olefin rubber such as a linear low-density polyethylene elastomer, or butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene-core-shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene Core-shell rubber (MAS), octyl acrylate-butadiene-styrene-core-shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene-core-shell rubber (AAB)
S), butadiene-styrene-core-shell rubber (SB
R), a core-shell type particulate elastic material such as a siloxane-containing core-shell rubber such as methyl methacrylate-butyl acrylate-siloxane, or a rubber modified from these.

Thermoplastic resins other than syndiotactic polystyrene Examples of thermoplastic resins other than syndiotactic polystyrene include linear high-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, and syndiotactic polypropylene. Otactic polypropylene, block polypropylene, random polypropylene, polybutene, 1,2-polybutadiene, 4-methylpentene, cyclic polyolefins and polyolefin resins represented by these copolymers, atactic polystyrene, isotactic polystyrene, HIPS, A
BS, AS, styrene-methacrylic acid copolymer, styrene-methacrylic acid / alkyl ester copolymer, styrene-methacrylic acid / glycidyl ester copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid / alkyl ester copolymer Polystyrene resins such as polymers, styrene-maleic acid copolymers and styrene-fumaric acid copolymers, polyester resins such as polycarbonate, polyethylene terephthalate and polybutylene terephthalate, polyamide 6, polyamide 6,6 And any other known resins such as polyamide resins, polyphenylene ether, PPS, and the like. In addition, these thermoplastic resins can be used alone or in combination of two or more.

In the styrene-based resin film according to the present invention, in particular, in order to exhibit its breaking elongation and film impact, it is preferable to use SBR, SEB, SB.
S, SEBS, SIR, SEP, SIS, SEPS, core shell rubber, EPM, EPDM, linear high density polyethylene, linear low density polyethylene, high pressure low density polyethylene, isotactic polypropylene, syndiotactic polypropylene, block polypropylene,
Polypropylene resins represented by random polypropylene, polybutene, 1,2-polybutadiene, 4-methylpentene, cyclic polyolefins and copolymers thereof, atactic polystyrene, isotactic polystyrene, HIPS, ABS, AS, styrene-methacryl Acid copolymer, styrene-methacrylic acid-alkyl ester copolymer, styrene-methacrylic acid-glycidyl ester copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl ester copolymer, styrene-maleic acid A polystyrene resin represented by a copolymer or a styrene-fumaric acid copolymer can be used alone or in combination of two or more with syndiotactic polystyrene.

In order to improve the bubble stability of the blown film, it is preferable to use a branched-chain polymer such as a high-pressure low-density polyethylene. (2) Inorganic filler The inorganic filler may be fibrous, granular or powdery. As the fibrous filler,
For example, glass fiber, carbon fiber, whisker and the like can be mentioned. The shape is a cross shape, mat shape, focused cut shape,
There are short fibers, filaments, whiskers, etc., and in the case of a bundle cut, those having a length of 0.05 mm to 50 mm and a fiber diameter of 5 to 20 μm are preferred.

On the other hand, as the granular or powdery filler, for example, talc, carbon black, graphite, titanium dioxide, silica, mica, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, Oxysulfate, tin oxide, alumina, kaolin, silicon carbide, metal powder, glass powder, glass flake, glass beads and the like can be mentioned.

Among the various fillers described above, glass fillers such as glass powder, glass flake,
Glass beads, glass filaments, glass fibers, glass lobing, and glass mats are preferred. Also,
These fillers are preferably surface-treated.
The coupling agent used for the surface treatment is used for improving the adhesiveness between the filler and the resin,
Any one of conventionally known ones such as a so-called silane coupling agent and a titanium coupling agent can be selected and used. Above all, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane And aminosilane, epoxysilane and isopropyl tri (N-amidoethyl, aminoethyl) titanate.

As the film former, a conventionally known one can be used, and among them, urethane type, epoxy type, polyether type and the like are preferably used. In addition, these inorganic fillers can be used alone or in combination of two or more. About the compounding amount of the inorganic filler, the resin component 1
1 to 350 parts by weight with respect to 00 parts by weight. (3) Various additives As long as the object of the present invention is not impaired, various additives exemplified below can be blended.

Antiblocking Agent (AB Agent) Examples of the antiblocking agent include the following inorganic particles or organic particles. As the inorganic particles, IA
, IIA, IVA, VIA, VIIA, VII
Oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxyls of Group I, IB, IIB, IIIB and IVB elements Acid salts, silicates, titanates, borates and their hydrated compounds, composite compounds centered on them, and natural mineral particles are included.

Specifically, Group IA element compounds such as lithium fluoride, borax (sodium borate hydrate), magnesium carbonate, magnesium phosphate, magnesium oxide (magnesia), magnesium chloride, magnesium acetate, magnesium fluoride, titanium Magnesium silicate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, titanate Group IIA compounds such as calcium, strontium titanate, barium carbonate, barium phosphate, barium sulfate, barium sulfite, titanium dioxide (titania), titanium monoxide, titanium nitride, zirconium dioxide (zirconia), monoxide Group IVA element compounds such as ruconium, molybdenum dioxide, molybdenum trioxide, molybdenum sulfide and the like; Group VIIA element compounds such as manganese chloride and manganese acetate; Group VIIIA element compounds such as cobalt chloride and cobalt acetate; Group IB element compounds such as cuprous copper; Group IIB element compounds such as zinc oxide and zinc acetate; IIIB such as aluminum oxide (alumina), aluminum hydroxide, aluminum fluoride, and alumina silicate (alumina silicate, kaolin, kaolinite) Group element compounds, silicon oxide (silica, silica gel), graphite,
Examples include IVB group element compounds such as carbon, graphite, and glass, and particles of natural minerals such as kernalite, kainite, mica (mica, kinmo), and virose ore.

Examples of the organic particles include Teflon, melamine resin, styrene / divinylbenzene copolymer, acrylic resin, and crosslinked products thereof. Here, the average particle size of the inorganic particles used is 0.1 to 10 μm, and the amount added is 0.01 to 15 parts by weight based on 100 parts by weight of the resin component.
Parts by weight are preferred. These inorganic fillers can be used alone or in combination of two or more.

Antioxidant The antioxidant can be arbitrarily selected from known ones such as phosphorus, phenol and sulfur. In addition, these antioxidants may be used alone, or
Two or more can be used in combination. Nucleating agents As nucleating agents, metal salts of carboxylic acids such as aluminum di (pt-butylbenzoate) and metal salts of phosphoric acid such as sodium methylenebis (2,4-di-t-butylphenol) acid phosphate , Talc, phthalocyanine derivatives and the like can be arbitrarily selected and used. These nucleating agents can be used alone or in combination of two or more. Plasticizers Examples of the plasticizer include polyethylene glycol, polyamide oligomer, ethylene bisstearamide, phthalic acid ester, polystyrene oligomer, and the like. Any known materials such as polyethylene wax and silicone oil can be arbitrarily selected and used. These plasticizers can be used alone or in combination of two or more.

Release Agent Any known release agent such as polyethylene wax, silicone oil, long-chain carboxylic acid, or metal salt of long-chain carboxylic acid can be used as the release agent. These release agents may be used alone or in combination of two or more.

Process oil In the present invention, in order to improve elongation, the oil is further treated at 40 ° C.
It is preferable to incorporate a process oil having a kinematic viscosity at 15 to 600 centistokes (cs). Process oils are roughly classified into paraffin-based oils, naphthenic-based oils, and aroma-based oils depending on the type of oil. Among them, the total number of carbon atoms related to paraffin (straight-chain) calculated by the ndM method A paraffinic oil having a percentage of 60% Cp or more based on the weight of the oil is preferred.

The viscosity of the process oil is preferably 15 to 600 cs in kinematic viscosity at 40 ° C.
cs is more preferred. Kinematic viscosity of process oil is 15c
If it is less than s, the elongation is improved, but the boiling point is low and SP
It causes melting, kneading with S, and white smoke, gas burning, and roll adhesion during molding. If the kinematic viscosity exceeds 600 cs, burning of white smoke gas and the like is suppressed, but the elongation improvement effect is poor.

The amount of the process oil to be added is preferably from 0.01 to 1.5 parts by weight, more preferably from 0.05 to 1.4 parts by weight, based on 100 parts by weight of the total of the resin components in the resin composition. And more preferably 0.1 to 1.3 parts by weight.
If the amount is less than 0.01 part by weight, the effect of improving the elongation of the process oil cannot be expected. If the amount exceeds 1.5 parts by weight, even if a high viscosity process oil is used, white smoke, gas burning, etc. Control may be difficult.
These process oils can be used alone or in combination of two or more.
. 3. Properties of syndiotactic polystyrene or a resin composition containing the same The syndiotactic polystyrene or a resin composition containing the same used for forming a styrene-based resin blown film according to the present invention preferably satisfies the following properties. (1) The melt index value (MI) measured at a temperature of 300 ° C. and a load of 2.16 kg (10 minutes) is 0.5 or more and 20 or less, preferably 1 or more and 15 or less.

When the MI is less than 0.5, the extrudability deteriorates, and the appearance of the film such as melt fracture tends to be poor. When the MI is more than 20, the inflation moldability deteriorates, such as instability of bubbles, and the resulting film has poor uniformity in thickness, wrinkles on the surface, and the like. , And the breaking elongation and the film impact may be insufficient. 4. Properties of the styrene-based resin blown film according to the present invention (1) The crystallinity (Xc) needs to be 30% or more, and preferably 35% or more. When Xc is less than 30%, the dimensional stability under heat and / or the dead hold property and the heat resistance tend to be insufficient. Further, in this case, the heat shrinkage may be 5% or more, and the film is likely to be wrinkled at the time of secondary processing such as lamination, printing, and heat sealing. (2) The elongation at break in at least one direction of the film is 1
It needs to be 0% or more. When the elongation at break is less than 10%, pinholes are apt to occur in the dead hold portion, and it cannot be used for packaging. (3) Further, the film impact is desirably at least 2,000 J / m, preferably at least 3,000 J / m. 5. Production method of styrene-based resin blown film according to the present invention In order to produce the inflation film according to the present invention,
First, the styrene polymer having a syndiotactic structure and its composition of the present invention are melt-extruded at 270 to 320 ° C from a ring die. Here, the screw at the time of extrusion may be either a single screw or a twin screw, and a screw having a single kneading portion with a single screw or a single screw can easily increase the bubble surface temperature. The lip opening of the ring die is 0.5 to 4.0
mm, preferably 0.5 to 3.0 mm. Here, the extrusion direction from the die is upward (upward blowing), downward (downward blowing)
Either may be used. The die exit speed can be adjusted by selecting the extrusion amount, die diameter, and die gap. After being extruded from the die, it is blown by gas pressure sealed in a bubble formed between the take-off nip rolls, drawn by take-up, and folded by the nip rolls to obtain an inflation film. In order to adjust the bubble temperature and stabilize the bubble, a ring-shaped nozzle generally called an air ring is taken up from the vicinity of the die outlet, and is placed between the nip rolls.
Two or more may be provided, and the temperature of the blowing air is 270 ° C.
The adjustment may be made as follows. Further, a heat insulating material may be provided on the bubble stabilizer.

In the present invention, the inflation film of the present invention can be produced efficiently by classifying the styrenic polymer having the syndiotactic structure and its composition according to the crystallization temperature and selecting specific conditions during the production of inflation. can do. Here, crystallization temperature (Tc)
The term refers to a crystallization peak temperature when the temperature is lowered from 300 ° C. at a rate of 20 ° C./min using a differential scanning calorimeter (DSC).

When the crystallization temperature of the syndiotactic styrenic polymer and its composition is 236 ° C. or more, the blow ratio (film diameter after blow / die diameter) is 2.0 or more and the draw ratio is (Winding speed / normal speed of molten resin at die exit) is preferably 5 or more. Here, when the blow ratio is less than 2.0 and / or the draw ratio is less than 5, the elongation at break of the film and the impact of the film become low, and a pinhole is generated at the time of dead hold, which is not preferable.

The syndiotactic styrenic polymer and its composition have a crystallization temperature (Tc) of 236.
If the temperature is lower than ℃, the die exit speed is 3.0m / min or less,
The blow ratio (film diameter / die diameter after blow) is 2.0 or more, the bubble surface temperature from the blow start height to the intermediate height of the frost height is Tc-80 ° C to Tc + 20 ° C, and the draw ratio (winding speed (Normal speed of molten resin at die exit) is preferably 10 or more.

Here, when the die exit speed exceeds 3.0 m / min, and / or when the blow ratio is less than 2.0, and / or when the bubble surface temperature at the time of blow is less than Tc-80 ° C., or Tc + 20 If the temperature exceeds ℃ and / or the draw ratio is less than 10, not only is it difficult to obtain a crystallized film, but also the elongation at break of the film and the impact of the film become low, and pinholes occur during dead hold. It is not preferable because it becomes easy.

Further, in any of the above methods, the film surface temperature at the time of folding in the nip roll is 7
The temperature is preferably from 0 to 130 ° C. If the film surface temperature is lower than 70 ° C., the film is likely to wrinkle,
If the temperature exceeds 0 ° C., the film tends to cause blocking. The bubble surface temperature at the time of blowing and the film surface temperature at the time of folding at the nip roll can be adjusted by the die exit speed (die lip area / extrusion amount), the take-up speed, the blow ratio, and the air ring airflow / temperature. These surface temperatures can be measured by a non-contact thermometer such as an infrared method. 6. Use of the styrene-based resin blown film according to the present invention The styrene-based resin blown film according to the present invention can be used for various applications. However, since it is excellent in dead hold property and toughness, it is particularly suitable for twist packaging, It is suitably used as a packaging material such as a container lid base material, an adhesive label and a simple adhesive tape, and an industrial material such as a masking film, a label, a magazine tape and a release film.

[0033]

[Evaluation method of blown film]

(1) Crystallinity The enthalpy of fusion (ΔH) obtained by measuring the temperature of the film with a differential scanning calorimeter at a rate of 20 ° C./min.
f) and the enthalpy of cold crystallization (ΔH _Tcc ) were calculated by the following equation.

Crystallinity (%) = 100 × (ΔHf−ΔH)
( _Tcc ) / 53 (J / g) (2) Elongation at break Measured in accordance with JIS Z1702 (3) Film impact Measured with a 1 inch impact head using a film impact tester (a pendulum type) manufactured by Toyo Seiki Seisakusho Co., Ltd. . (4) Thermal shrinkage rate The film is cut exactly 100 mm square,
Was placed in an air oven for 3 minutes, and the heat shrinkage was measured. (5) Dead hold property, oil resistance The film is cut into a circle of 100 mmφ, folded in two (180 °), sandwiched between aluminum plates, and a load of 5 kg is applied for 12 hours. After removing the load and the aluminum plate and leaving no load for 12 hours, the angle between the two folds is measured. Further, an oil-based ink is applied to the folded portion, and the presence or absence of seepage on the back side of the film is evaluated.

○: Folding angle is less than 45 ° and no ink seeping out ×: Folding angle is 45 ° or more and / or ink seeping out [raw materials used] ・ SPS1: Syndiotactic polystyrene Idemitsu Petrochemical Zarek Tm = 270 ° C, MI = 3 (300 ° C, 1.2 kgf) ・ SPS2: Syndiotactic polystyrene Izumi Petrochemical Zarek Tm = 270 ° C, MI = 13 (300 ° C, 1.2 kgf) ・ SEBS1: SEBS type Elastomer Tuftec H1081 made by Asahi Kasei Kogyo Co., Ltd. SEBS2: SEBS type elastomer Septon 8006 made by Kuraray Co., Ltd. PE1: High pressure method low density polyethylene Novatec HE30 made by Polychem Japan PE2: High pressure method low density polyethylene Novatec LH100N made by Japan Polychem 3: Ultra-low-density polyethylene Naflex DFDA-1138 manufactured by Nippon Unicar PE4: Ultra-low-density polyethylene Naflex DFDA-1210 manufactured by Nippon Unicar PE5: Low-density polyethylene-based elastomer Dupont Dow Elastomer ENGAGE 8400 AB agent 1: Antiblocking agent Talc Asada Flour Talc FFR ・ AB agent 2: Antiblocking agent Aluminosilicate Mizusawa Chemical AMT-08 ・ Nucleating agent 1: Asahi Denka Co., Ltd. NA-11 [Example 1] SPS1 (Syndiotactic polystyrene, Idemitsu Petrochemical) “Zarek” (Tm = 270 ° C., MI = 3 (30
0 ° C, 1.2 kgf))) 69.8 wt%, PE1 (high-pressure low-density polyethylene, “Novatech H” manufactured by Nippon Polychem)
E30 ”), 24 wt%, SEBS1 (SEBS type elastomer,“ ToughTech H108 ”manufactured by Asahi Kasei Corporation)
AB) 1 (talc, manufactured by Asada Flour Milling Co., Ltd.)
FR ”) is 0.2 wt%, and“ Irga ”is used as an antioxidant.
nox1010 "(manufactured by Ciba-Geigy)," PEP3
6 "(manufactured by Asahi Denka Co., Ltd.) and" Sumilyzer GS "(manufactured by Sumitomo Chemical Co., Ltd.) were each blended in 0.1 part by weight, dry blended, and melt-kneaded with a 65 mmφ twin screw extruder to obtain pellets. The obtained material had a melt flow index (MI) of 7.0 ° C., 2.16 kg, and 10 minutes of 7.0, and a crystallization temperature of 240 ° C. measured by a differential scanning calorimeter (DSC).

The material was attached to a 50 mmφ single screw (Dalmage type screw) extruder with an annular die having a 50 mmφ and a gap of 1 mm.
The mixture was melt-extruded at a temperature of ° C. and adjusted to have a blow ratio of 2.5 and a draw ratio of 13, to obtain an inflation film. At the time of inflation molding, an air ring was used, and a heat insulating material was attached to a stabilizer to stabilize bubbles. When the surface temperature of the bubble between the start of the blowing of the bubble and the height of the frost and the surface temperature of the bubble immediately before the nip were measured by an infrared non-contact thermometer, they were 150 ° C. and 102 ° C., respectively.
Table 1 shows the characteristics and practical characteristics of the obtained blown film.

[0037]

[Table 1]

[Examples 2 to 7 and Comparative Examples 1, 5, and 6]
By changing the material composition, the crystallization temperature showing various MI values is 23
Prepare a kneading material of 5 ° C or higher, and prepare a 50mmφ 0.5mm gap, 50mmφ 1mmφ gap, 50mmφ
A die having a gap of 1.5 mm was used according to each condition, and the extrusion amount, blow ratio and take-up speed were adjusted to obtain a film.

Table 1 shows the properties of each composition material, the inflation molding conditions, the properties of the blown film, and the practical properties. Example 8 Inflation molding was performed directly using a dry-blended material having the same composition as in Example 3. Table 1 shows the results
Shown in [Examples 9 to 14 and Comparative Examples 2 to 4] By changing the material composition, kneading materials having various MI values and a crystallization temperature of less than 235 ° C were prepared, and a 50 mmφ 0.5 mm gap, 50 m
A die having a gap of mφ 1 mmφ and a gap of 50 mmφ 1.5 mm was used according to each condition, and the extrusion amount, blow ratio and take-up speed were adjusted to obtain a film.

Table 1 shows the properties of each composition material, the inflation molding conditions, the properties of the blown film, and the practical properties.

[0041]

According to the present invention, a styrene-based resin blown film as a packaging material having excellent dimensional stability, water resistance and mechanical strength and having good dead-holding properties was obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) // B29K 21:00 23:00 25:00 B29L 7:00 F Term (Reference) 4F071 AA10 AA15 AA22 AA89 AB30 AF05 AF14 AF20 AF21Y AF54 AH04 BA01 BB06 BB09 BC01 BC10 4F210 AA05 AA13A AA13C AA47 AB06 AB16 AE01 AG01 AR06 AR08 AR20 QA01 QK01 QK05 4J002 AA013 AC012 AC032 AC092 BB152 BC031 BC092 BC111 BG PN BG PN BG CB PN BG 012 BG 012 BG 012 BG BG

Claims (5)

[Claims] A film obtained by inflation molding a resin composition containing a styrenic polymer having a predominantly syndiotactic structure or a styrenic polymer having a predominantly syndiotactic structure, wherein the film has a crystallinity of 30. % And a styrene resin film having a breaking elongation of 10% or more. 2. A resin composition containing a styrenic polymer having a predominantly syndiotactic structure, the styrene-based polymer having a syndiotactic structure being 1 to 98.
% By weight, polyethylene and / or rubbery elastic body 99-2
The styrene-based resin film according to claim 1, wherein the styrene-based resin film is composed of 1 wt%. 3. A styrenic resin having a crystallization temperature (Tc) of 236 ° C. or higher at a cooling rate of 20 ° C./min or more having a syndiotactic structure or a composition thereof at 270 to 320 ° C. Extruded from a ring die,
The method for producing a styrene resin film according to claim 1 or 2, wherein the blow is performed under the conditions of a blow ratio of 1.5 or more and a draw ratio of 5 or more. 4. A styrenic resin having a crystallization temperature (Tc) of less than 236 ° C. at a cooling rate of 20 ° C./min and having a mainly syndiotactic structure or a composition thereof at 270 to 320 ° C. Exit speed 3.0m /
2. Extrusion from an annular die in less than a minute, and blowing at a blow ratio of 2.0 or more, a draw ratio of 10 or more, and a bubble surface temperature of (Tc−80) ° C. or more and (Tc + 20) ° C. or less. 3. The method for producing a styrene resin film according to item 2. 5. The method for producing a styrene resin film according to claim 3, wherein after blowing, the film is folded at a surface temperature of 70 to 130 ° C. .