JP3515584B2 - Packaging bags - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate and a packaging bag, and more particularly to a laminate having excellent solvent resistance, moisture resistance, dimensional stability and hand-cutting property, and a packaging comprising the laminate. It's about bags.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
A bag manufactured using a plastic film has a drawback that extra special processing such as a notch such as a buoy notch or continuous fine holes is required for easy opening. Then, as a bag that can be torn by hand and opened,
A bag manufactured from a cellophane / polyolefin film laminate has been put into practical use. This type of bag has the following drawbacks. 1) Since the cellophane manufacturing process is wet, the efficiency is poor. 2) Use a large amount of harmful chemicals in the cellophane manufacturing process. 3) Cellophane film shows remarkable changes in physical properties due to humidity. For example, it is difficult to cut by hand. Inferior dimensional stability. Poor water resistance. Further, a bag manufactured from a laminate of biaxially stretched polystyrene film (amorphous) / polyolefin film has been proposed (for example, JP-A-63-79). However, since the biaxially stretched polystyrene film is amorphous, it has the following drawbacks. 1) Poor heat resistance, shrink and deform by heat sealing. 2) The solvent resistance is poor, and the solvent is limited during lamination and printing. Furthermore, recently, there is a strong demand for an easily openable bag because of the simplification of packaging work or the ease of handling, and the development of a material suitable for this is desired.

Therefore, in view of the above situation, the present inventors have considered
The inventors have made earnest studies to develop a laminated body which is excellent in solvent resistance, moisture resistance, dimensional stability, and excellent in hand-cutting ability, and a packaging bag made of the laminated body, which solves the drawbacks of the conventional method. As a result, they have found that a film containing a styrene-based polymer having a syndiotactic structure as a main component, especially a laminate using a stretched film has desired properties and suitability. The present invention has been completed based on such findings.

[0004]

That is, the present invention is
(A) A styrene-based polymer having a high syndiotactic structure or a composition containing the same, having a crystallinity of 35% or more, a surface tension of 35 dyne / cm or more, a thickness of 10 to 40 μm, and heat shrinkage. Rate (190 ℃, 5 minutes)
Is a biaxially stretched polystyrene film and (b) a heat-sealable polyolefin film.
Good hand-cutting characteristics characterized by being composed of a laminate
It is intended to provide a packaging bag .

The laminated body of the present invention essentially includes both layers (a) and (b). Here, the polystyrene film (a) is composed of a styrene polymer having a high syndiotactic structure or a composition containing the styrene polymer. This styrene-based polymer having a high syndiotactic structure is one having a high syndiotactic structure in stereochemical structure, that is, phenyl which is a side chain with respect to the main chain formed from carbon-carbon bonds. A group or a substituted phenyl group has a steric structure in which they are alternately located in opposite directions, and the tacticity thereof is quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ¹³ C-
Tacticity measured by the NMR method can be indicated by the abundance ratio of a plurality of continuous constitutional units, for example, diad in the case of 2, triad in the case of 3, and pentad in the case of 5. The styrene-based polymer having a high syndiotactic structure referred to in the present invention is usually a racemic dyad of 75% or more, preferably 85% or more, or a racemic pentad of 30% or more, preferably 50% or more. Polystyrene having syndiotacticity, poly (alkylstyrene), poly (halogenated styrene), poly (alkoxystyrene), poly (vinyl benzoate), hydrogenated polymers thereof and mixtures thereof, or structures thereof It refers to a copolymer containing units. Here, as poly (alkylstyrene), poly (methylstyrene), poly (ethylstyrene), poly (propylstyrene), poly (butylstyrene), poly (phenylstyrene), poly (vinylnaphthalene), poly (Vinylstyrene), poly (acenaphthylene), etc., and as poly (halogenated styrene), poly (chlorostyrene),
Examples include poly (bromostyrene) and poly (fluorostyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferred styrene polymers are polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tertiarybutylstyrene), poly (p-chlorostyrene), poly ( m-chlorostyrene), poly (p-fluorostyrene), and a copolymer of styrene and p-methylstyrene (JP-A-62-1877).
08 publication).

Further, as the comonomer in the styrene-based copolymer, in addition to the above-described styrene-based polymer monomers, olefin monomers such as ethylene, propylene, butene, hexene and octene, diene monomers such as butadiene and isoprene, and cyclic compounds. Examples thereof include diene monomers, polar vinyl monomers such as methyl methacrylate, maleic anhydride, and acrylonitrile. The styrene-based polymer is not particularly limited in molecular weight, but it is preferable that the weight average molecular weight is 10000 to 3,000,000, and particularly preferably 50,000 to 150,000. is there. Here, the weight average molecular weight is 100,000.
If it is less than 0, stretching cannot be sufficiently performed. Further, the molecular weight distribution is not limited in width and width, and various kinds can be applied, but the weight average molecular weight (Mw)
/ Number average molecular weight (Mn) is preferably 1.5 to 8. In addition,
The styrene-based polymer having the syndiotactic structure has remarkably excellent heat resistance as compared with the conventional styrene-based polymer having the atactic structure.

The styrene-based polymer having such a high syndiotactic structure may be used as it is in the layer (a) of the laminate of the present invention, or if desired, the styrene-based polymer of the present invention can be used. It is also possible to use a composition in which various additives and the like are added to this styrene-based polymer as long as the curing is not hindered. Here, various additives such as inorganic fine particles, antioxidants, antistatic agents, flame retardants, and other resins can be used as additives to be blended.

Here, the inorganic fine particles are group IA and IIA.
Group, IVA Group, VIA Group, VIIA Group, VIII Group, IB
Group, IIB, IIIB, IVB group oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxylates, silicic acids We show salts, titanates, borates and their hydrous compounds, complex compounds centered on them, and natural mineral particles. 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, magnesium titanate, silicic acid Magnesium, magnesium silicate hydrous salt (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, calcium titanate, titanic acid Group IIA element compounds such as strontium, barium carbonate, barium phosphate, barium sulfate, barium phosphite, titanium titania), titanium monoxide, titanium nitride, zirconium dioxide, zirconium monoxide, etc. Element compounds, Group VIA element compounds such as molybdenum dioxide, molybdenum trioxide, molybdenum sulfide, Group VIIA element compounds such as manganese chloride and manganese acetate, Group VIII element compounds such as cobalt chloride and cobalt acetate, cuprous iodide, etc. Group IB group element compounds such as zinc oxide, zinc acetate, etc. group IIIB group element compounds such as aluminum oxide (alumina), aluminum hydroxide, aluminum fluoride, aluminosilicate (alumina silicate, kaolin, kaolinite), Examples thereof include particles of IVB group elements such as silicon oxide (silica, silica gel), graphite, carbon, graphite, and glass, and natural mineral particles such as carnal stone, kainite, mica (mica, quinnemo), and birose ore. The average particle size of the inorganic fine particles used here is not particularly limited, but is preferably 0.01 to 3
μm, more preferably 0.01 to 1 μm, and the content in the molded product is 0.001 to 1% by weight, preferably 0.005 to 1% by weight. The inorganic fine particles are contained in the final molded article, but the method of containing them is not limited. For example, a method of adding or precipitating in an arbitrary process during polymerization, a method of adding in an arbitrary process of melt extrusion can be mentioned.

There are various other resins that can be added to the above-mentioned styrene-based polymer. For example, a styrene-based polymer having an atactic structure, a styrene-based polymer having an isotactic structure, and a polyphenylene ether. And the like. These resins tend to be compatible with the styrene-based polymer having the syndiotactic structure described above, are effective in controlling the crystallization when preparing a preform for stretching, and the subsequent stretchability is improved. It is possible to obtain a film in which control of conditions is easy and which has excellent mechanical properties. Among these, when a styrene polymer having an atactic structure and / or an isotactic structure is contained, a styrene polymer having a chemical structure similar to that of the styrene polymer having a syndiotactic structure is preferable. Further, the content ratio of these compatible resin components may be 70 to 1% by weight, particularly preferably 50 to 2% by weight. Here, if the content of the compatible resin component exceeds 70% by weight, heat resistance, which is an advantage of the styrene-based polymer having a syndiotactic structure, is impaired, which is not preferable. Other resins which can be added to the polymer of the present invention and which are incompatible resins include, for example, polyolefins such as polyethylene, polypropylene, polybutene and polypentene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like. Polyester, polyamide such as nylon-6 or nylon 6,6, polythioether such as polyphenylene sulfide, polycarbonate, polyarylate, polysulfone, polyether ether ketone,
Vinyl halide polymers such as polyether sulfone, polyimide, Teflon, acrylic polymers such as polymethylmethacrylate, polyvinyl alcohol, etc. are all equivalent except for the above compatible resins. The cross-linking resin containing is mentioned. Since these resins are incompatible with the styrene polymer having a syndiotactic structure of the present invention, when contained in a small amount, they should be dispersed like islands in the styrene polymer having a syndiotactic structure. It is effective in imparting a moderate gloss after stretching and improving the surface slipperiness. The content ratio of these incompatible resin components is 50 when gloss is intended.
~ 2% by weight, 0.001 for controlling surface properties
-5% by weight is preferred. Further, when the temperature used as a product is high, it is preferable to use an incompatible resin having relatively high heat resistance.

For the layer (a) in the laminate of the present invention, a styrene polymer having a high-purity syndiotactic structure as described above or a composition containing the styrene polymer is used, and the thickness is in the range of 5 to 50 μm. It is a film formed on. The method for producing this film is not particularly limited, but in the case of stretching, the above styrene-based polymer or a composition containing the same is heated and melted to obtain a preformed body, which is then heated and further required. It is obtained by heat-treating according to. That is, first, a styrene-based polymer obtained as described above or a composition containing the styrene-based polymer is used as a molding material, which is usually extrusion-molded, and if necessary, a preform for stretching (film, sheet). Or tube). In this molding, it is common to mold the heat-melted molding material into a predetermined shape with an extruder, but do not heat the molding material and mold it in a softened state. Good. The extruder used here is
It may be a single-screw extruder or a twin-screw extruder, and may or may not have a vent. In addition,
If a suitable mesh is used for the extruder, it is possible to remove impurities and foreign substances. Further, the shape of the mesh can be appropriately selected and used such as a flat plate shape, a cylindrical shape, and a leaf disk shape. Then, the extrusion conditions here are not particularly limited and may be appropriately selected according to various situations,
Preferably, the temperature is 50 ° C from the melting point of the molding material to the decomposition temperature.
Select in the high temperature range and set the shear stress to 5 × 10 ⁶ dyn
e / cm ² or less. The die used may be a T-die, an annular die or the like.

After the above extrusion molding, the obtained preform for stretching is cooled and solidified. At this time, various refrigerants such as gas, liquid and metal roll can be used. When a metal roll or the like is used, it is effective to prevent thickness unevenness and waviness according to methods such as an air knife, an air chamber, a touch roll, and electrostatic printing. The temperature for cooling and solidification is usually 0 ° C.
-The temperature is in the range of 30 ° C higher than the glass transition temperature of the preform for stretching, preferably in the range of 70 ° C lower than the glass transition temperature-glass transition temperature. The cooling rate is 2
It is appropriately selected in the range of 00 to 3 ° C / sec. In the present invention, the cooled and solidified preform is uniaxially or biaxially stretched to form a film. When biaxially stretching, the stretching may be performed simultaneously in the machine direction and the transverse direction, but may be sequentially performed in any order. Further, the stretching may be performed in one step or in multiple steps. The draw ratio is 2 times or more, preferably 3 times or more in terms of area ratio. When the stretching ratio is within this range, the crystallinity of the film is 25% or more, and favorable physical properties can be obtained.

Here, there are various stretching methods, such as a tenter method, a method of stretching between rolls, a method of bubbling utilizing gas pressure, a method of rolling, etc., and these are appropriately selected or combined and applied. do it. The stretching temperature may be generally set between the glass transition temperature and the melting point of the preform. The stretching speed is usually 1 × 10 to 1 × 10 ⁵ % / min, preferably 1 × 10 5.
^{It is 3} to 1 × 10 ⁵ % / min. When the stretched film obtained by stretching under the conditions as described above is required to have dimensional stability at high temperature, heat resistance, and strength balance in the film plane, it is preferable to further perform heat setting. .
The heat setting can be carried out by a commonly used method, but the stretched film is subjected to a tensioned state, a relaxed state or a restricted shrinking state, from the glass transition temperature to the melting point of the film, preferably 100 ° C. lower than the melting point. It may be carried out by maintaining the temperature in the temperature range from the temperature to immediately before the melting point for 0.5 to 120 seconds. The heat setting can be performed twice or more by changing the conditions within the above range. Further, this heat fixing may be performed in an atmosphere of an inert gas such as argon gas or nitrogen gas. Further, for the purpose of improving the surface tension of the obtained film, chemical treatment such as corona treatment, plasma treatment and sulfonation may be performed.

The polystyrene film thus obtained (hereinafter abbreviated as SPS film) may be an unstretched film or a uniaxially stretched film, but a biaxially stretched film is preferable because of its excellent mechanical strength and controlled stretching conditions. By doing so, high tearability can be imparted only in one direction, which is suitable as a packaging base material and has various properties. That is, the crystallinity of such an SPS film is 35% or more (DSC method) and the thermal shrinkage (1
90 ° C, 5 minutes) becomes 5% or less. Crystallinity is 35
If it is less than%, the heat shrinkage rate becomes 10% or more, which is not preferable as a packaging base material. Furthermore, the preferred crystallinity is 4
When it is 0% or more, the heat shrinkage rate is 3% or less, which is more preferable. With respect to solvent resistance, the crystallinity is stable at 35% or more.
Further, the surface tension of this SPS film should be 35 dyne / cm or more from the viewpoint of hand tearability. When the surface tension is less than 35 dyne / cm, the laminating strength is not sufficient, and the surface base material (SPS film) and the sealant film (heat-sealable film) are peeled (derami) during tearing, and the tear propagation resistance (tearing strength) is remarkable. It rises and makes tearing and opening difficult. And the surface tension is 38 dyne
/ Cm or more is more preferable in maintaining the heat seal strength. The thickness of the SPS film is 5 to 50 μm, preferably 10 to 40 μm, in order to maintain the function of the packaging bag made of the laminated body using the SPS film. Here, if the thickness is less than 5 μm, the tear strength is small, but the mechanical strength of the bag cannot be maintained. On the other hand, when it exceeds 50 μm, the mechanical strength of the bag is satisfactory, but the hand-cutting property is remarkably deteriorated, and tear opening becomes difficult. Therefore, the thickness is 10 to 40 μm.
Is preferable because it is well balanced in terms of both sufficient mechanical strength and hand tearability.

Next, the layer (b) constituting the laminate of the present invention is made of a polyolefin film, and its thickness is preferably 20 to 100 μm. This polyolefin film has heat sealability. Examples of the heat-sealable polyolefin film include polypropylene, polyethylene or ethylene,
Not extending Shin film propylene was mainly the copolymer is used. The laminate of the present invention essentially comprises the above-mentioned (a) SPS film and (b) polyolefin film, particularly a polyolefin film having a good heat-sealing property, and is obtained by laminating both layers. Here, the polyolefin film may be laminated by laminating film-like ones. Alternatively, the film may be formed on the SPS film by an extrusion coating method. If necessary, an adhesive may be used between the SPS film and the polyolefin film to improve the adhesion between the two layers.
When the extrusion coating method is used, various anchor coating agents are used, and when the dry lamination method is used, various adhesive agents are used. Examples of the anchor coating agent include natural rubber, casein, polyvinyl alcohol, polyacrylamide, vinylmethyl, an ether-maleic anhydride copolymer, a styrene-based copolymer, and a polyphenylene ether-based copolymer.

The packaging bag of the present invention comprises the above-mentioned laminated body, preferably with a polyolefin film layer inside, and this packaging bag is excellent in hand-cutting property, simple and easy. It has the advantage that it can be opened.

[0016]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Production Example (Production of Syndiotactic Polystyrene) Preparation of Contact Product of Aluminum Compound and Water 200 ml of toluene, copper sulfate pentahydrate (C
23.1 g (95 mmol) of uSO ₄ .5H ₂ O) and 24 ml (250 mmol) of trimethylaluminum were added and reacted at 30 ° C. for 30 hours. After the reaction was completed, the solid portion was removed, and the volatile component was distilled off under reduced pressure from the resulting solution to obtain 7.04 g of a contact product. The molecular weight of this product as measured by a freezing point depression method in a benzene solution was 1,100.

Production of Styrene Polymer To a glass container equipped with a stirrer having an internal volume of 500 ml, 50 ml of toluene and 3 mmol of the contact product obtained in the above (1) were added as aluminum atoms, and then triisobutylaluminum was added thereto. 3 mmol, pentamethylcyclopentadienyl titanium trimethyl 0.0
Add 6 mmol and 200 ml of styrene, and
The polymerization reaction was carried out at 0 ° C. for 1 hour. After completion of the reaction, the product was washed with methanol and dried to obtain 36.1 g of a polymer. The weight average molecular weight of this polymer was 40,000, and the number average molecular weight was 200,000. Melting point and ¹³ C-NM
R measurement revealed that the polymer obtained was polystyrene with a syndiotacticity in racemic pentad of 97%. The aluminum content in this polymer was 4,500 ppm and the titanium content was 8 ppm.

Example 1 Production of SPS Biaxially Stretched Film The powder of the styrenic polymer obtained in the above Production Example
It was dried under vacuum at 0 ° C. for 2 hours with stirring. This powder was melt-extruded by a device having a die equipped with a plurality of capillaries at the tip of a vented single-screw extruder, cooled, and cut to prepare an extrusion molding material (pellet). At this time, the melting temperature was 300 ° C., the screw diameter of the extruder was 50 mm, a full flight type was used, the extrusion rate was 30 kg / hour, and the vent pressure was 10 mmHg. After this, the pellets were crystallized and dried with stirring in hot air. The obtained pellet had an amount of residual styrene monomer of 1,100 ppm and a crystallinity of 35%. The pellets were extruded by a vibration-proof device equipped with a T-die at the tip of a single-screw extruder. At this time, the extrusion temperature is 320 ° C. and the shear stress is 3 ×.
It was 10 ⁵ dyne / cm ² . This melt-extruded sheet was brought into close contact with a metal cooling roll and cooled by electrostatic printing to prepare a raw material for stretching. At this time, the metal cooling roll was adjusted to 70 ° C. The cooling rate was 50 ° C / sec. Further, the thickness of the prepared original fabric was 300 μm, and the crystallinity was 15%. This original fabric was sequentially biaxially stretched in a table tenter at a rate of 3,000% / min at 110 ° C. in the extrusion direction and then in the direction perpendicular thereto by 3 times. Then, this stretched film is heat-treated at 260 ° C for 30 seconds under limited shrinkage, and SP
An S biaxially stretched film (BO-SPS film) was produced. The thickness of the obtained BO-SPS film was 30 μm,
The crystallinity was 55%.

Manufacture of Laminated Body The BO-SPS film was subjected to corona discharge treatment to adjust the surface tension to 40 dyne / cm. This BO-S
One side of the PS film was prepared by using ethyl acetate as a solvent, and the adhesive for lamination having a solid content concentration of 30% [AD-30
8A, manufactured by Toyo Morton Co., Ltd.] by a roll coater and dried with hot air at 80 ° C. for 30 seconds, and then as a heat-sealable polyolefin film by a nip roll (pressure 4 kg / cm ² ), Unilux LS-711C.
[Polyethylene film, manufactured by Idemitsu Petrochemical Co., Ltd.] was pressure-bonded. The laminated film obtained is laminated 4
The adhesive was cured by aging at 0 ° C. for 24 hours.

Automatic Filling and Packaging Using the above-mentioned laminated film, sugar was packaged under the following packaging conditions by a powder multiple automatic filling and packaging machine [SAM-R202 type manufactured by Sanko Kikai Co., Ltd.], and the packaging suitability was evaluated. Packaging conditions Number of shots: 50 pieces / min Sealing temperature: 180 ° C

Example 2 In Example 1, as a laminating adhesive, AD-
308B, manufactured by Toyo Morton Co., Ltd., as a heat-sealable polyolefin film, Unilux RS-50
3C [Polypropylene film, Idemitsu Petrochemical Co., Ltd.
Manufactured] and a sealing condition of 20
Example 1 was repeated except that the temperature was 0 ° C.

Comparative Example 1 The procedure of Example 1 was repeated, except that the BO-SPS film was replaced with a 20 μm thick SPS film (unstretched). Comparative Example 2 The procedure of Example 2 was repeated, except that a 20 μm thick SPS film (unstretched) was used in place of the BO-SPS film. Example 3 The procedure of Example 1 was repeated, except that a 10 μm thick BO-SPS film was used. Example 4 The procedure of Example 2 was repeated, except that the 10 μm thick BO-SPS film was used. Comparative Example 3 In Example 1, instead of the BO-SPS film, 9
With a table tenter, the original fabric made to a thickness of 0 μm
Example 1 was repeated except that an SPS uniaxially stretched film (O-SPS) that was uniaxially stretched three times in the extrusion direction at 110 ° C. and 3,000% / min was used. Comparative Example 4 In Example 2, instead of the BO-SPS film, 9
With a table tenter, the original fabric made to a thickness of 0 μm
Example 2 was carried out in the same manner as in Example 2 except that an SPS uniaxially stretched film (O-SPS) that was uniaxially stretched three times in the extrusion direction at 110 ° C and 3,000% / min was used.

Comparative Example 5 Example 1 was repeated except that cellophane (# 300) was used instead of the BO-SPS film. Comparative Example 6 The procedure of Example 2 was repeated, except that cellophane (# 300) was used instead of the BO-SPS film. Comparative Example 7 The procedure of Example 1 was repeated, except that a 25 μm-thick biaxially stretched polystyrene film [manufactured by Asahi Chemical Industry Co., Ltd., Styro film] was used in place of the BO-SPS film. . Comparative Example 8 The procedure of Example 2 was repeated, except that a 25-μm thick biaxially stretched polystyrene film [styrofilm manufactured by Asahi Kasei Kogyo KK] was used in place of the BO-SPS film. . Comparative Example 9 Comparative Example 9 was carried out in the same manner as Comparative Example 7 , except that the following alcohol type adhesive was used for dry lamination. Alcohol-type adhesive Takelac A-369 (manufactured by Takeda Pharmaceutical Co., Ltd.) Solvent: Isopropyl alcohol Comparative Example 10 The same operation as in Comparative Example 8 was carried out except that the following alcohol-type adhesive was used for dry lamination. Alcohol type adhesive Takelac A-19 [manufactured by Takeda Pharmaceutical Co., Ltd.] Solvent: Isopropyl alcohol

Comparative Example 11 The procedure of Example 1 was repeated except that a BO-SPS film having a crystallinity of 30% was used. Comparative Example 12 The procedure of Example 2 was repeated except that a BO-SPS film having a crystallinity of 30% was used. Comparative Example 13 The procedure of Example 1 was repeated except that a BO-SPS film having a surface tension of 33 dyne / cm was used. Comparative Example 14 The procedure of Example 2 was repeated, except that a BO-SPS film having a surface tension of 33 dyne / cm was used. Comparative Example 15 Except that a BO-SPS film having a thickness of 3 μm was used,
It carried out like Example 1. Comparative Example 16 Except that a BO-SPS film having a thickness of 3 μm was used,
It carried out like Example 2. Comparative Example 17 The procedure of Example 1 was repeated, except that a BO-SPS film having a thickness of 50 μm was used. Comparative Example 18 The procedure of Example 2 was repeated except that a BO-SPS film having a thickness of 50 μm was used.

In each of the Examples and Comparative Examples, the properties of the base film, suitability for laminating and suitability for packaging were evaluated. The results are shown in Tables 1 and 2.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

The criteria for each evaluation are as follows. 1) Lamination processability ○: Good processability Δ: Solvent resistance and film stiffness are poor ×: Solvent resistance and film stiffness are poorer 2) Sealability ○: Sealability is favorable Δ: Waistless and wrinkled Difficult and difficult to transfer heat x: Wrinkles due to heat shrinkage 3) Packaging suitability ◎: Very good ○: Good x: Wrinkles and pitch shift due to heat shrinkage, waist 4) Hand tearability ◎: Very good ○: Good △: Initial tear strength is extremely difficult x: Tear cannot occur due to heat shrinkage or tear due to sealant delamination *: Very good (however, only in a specific direction) 5) Moisture resistance ○: Good △: Tear strength is very difficult when moisture is included × : Tear resistance increases when moisture is included and tearing is not possible 6) Bag evaluation Heat shrinkage: Visual tearability: tearability by hand without notch (23 ℃ / 50% RH) Stability against moisture: Due to hand tearability at 40 ° C / 80% RH Valence 7) in other tables -: solvent the film is affected in non-assessable table =: 23 ℃ / 50% RH, 40 ℃ / 80% RH
Both are bad

[0030]

As described above, the laminate of the present invention has no dimensional change due to shrinkage during heat-sealing, is not attacked by organic solvent during laminating / printing, has stable physical properties against humidity, and has good tearability by hand. The packaging bag made of this material can be easily and easily tear-opened without a buoy notch. Therefore, the laminate of the present invention can be effectively used as a material for packaging bags such as food packaging and medical product packaging.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-3-124736 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 27/08 B32B 27/00 B32B 27 / 30-27/32 B65D 33/00

Claims (2)

(57) [Claims] 1. A composition comprising (a) a styrene-based polymer having a high syndiotactic structure or a composition containing the same, having a crystallinity of 35% or more and a surface tension of 35 dyne.
/ Cm or more, the thickness is 10 to 40 μm, and the heat shrinkage ratio (19
A hand comprising a laminate composed of a biaxially stretched polystyrene film and (b) a heat-sealable polyolefin film, which is 5% or less at 0 ° C. for 5 minutes.
Packaging bag with good cutting performance . 2. The packaging bag according to claim 1, wherein the heat-sealing polyolefin film (b) is an unstretched film of polypropylene, polyethylene, or a copolymer mainly composed of ethylene and propylene.