JPH10278198A - Polyolefinic biaxially stretched laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film enhanced in moistureproofing properties as compared with a conventional polypropylene stretched film, also excellent in easy tearing properties, and suitable for packing film for foods and medicines or a base film for a self-adhesive tape. SOLUTION: This laminated film is constituted by laminating a biaxially stretched layer (E) of crystalline polyolefin on at least one surface of a layer (D) formed by biaxially stretching a resin compsn. consisting of 3-9 pts.wt. of a petroleum resin (A), 91-97 pts.wt. of crystalline polyolefin (B) and 5-20 pts.wt. of a cyclic olefinic resin (C) with respect to 100 pts.wt. of the sum of (A) and (B) and a ratio of the thickness of the layer (E) to the thickness of the layer (D) and the layer (E) is 10-50% and the tensile breaking point strength in the longitudinal direction of the tensile breaking point elongation in the longitudinal direction thereof is 40-120%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based biaxially stretched laminated film, and more particularly, to mechanical properties,
The present invention relates to a polyolefin-based biaxially stretched laminated film having excellent transparency and moisture resistance and excellent tearability.

[0002]

BACKGROUND OF THE INVENTION Films obtained by biaxially stretching crystalline polyolefins such as crystalline polypropylene are excellent in mechanical properties such as tensile strength, rigidity, surface hardness and impact strength, and are glossy and transparent. It is excellent in optical properties such as properties and also excellent in food hygiene such as non-toxicity and odorlessness, and has been widely used as a packaging film in the fields of foods and pharmaceuticals.

[0003] Polyolefin-based biaxially stretched films used in such applications are required to have more gas barrier properties and moisture-proof properties in order to maintain the quality of foods and pharmaceuticals.

[0004] For this reason, a sheet or film formed by adding a petroleum resin to polypropylene (JP-A-7-157573, etc.) or a cyclic olefin polymer has been disclosed (JP-A-2-289637). Such a sheet or film is excellent in stretch resistance, gas barrier properties and easy tearability, but further improvement is required in terms of oil resistance.

It has been known that the addition of a cyclic polyolefin and a petroleum resin at a specific ratio to a polyolefin improves moisture resistance and oil resistance (Japanese Patent Application Laid-Open No. 5-262898). Such films,
Gloss, transparency and oil resistance are still insufficient and further improvements are required.

[0006]

An object of the present invention is to solve the above-mentioned problems of the prior art, and is excellent in mechanical properties, transparency, oil resistance and moisture resistance, and also excellent in tearability. It is intended to provide a polyolefin-based biaxially stretched film.

[0007]

SUMMARY OF THE INVENTION The polyolefin-based biaxially stretched laminated film according to the present invention comprises 3 to 9 parts by weight of a petroleum resin (A), 91 to 97 parts by weight of a crystalline polyolefin (B), (A) and (B). A biaxially oriented crystalline polyolefin is stretched on at least one surface of a layer (D) obtained by biaxially stretching a resin composition comprising 5 to 20 parts by weight of a cyclic olefin-based resin (C) with respect to 100 parts by weight of the total. (E) are stacked.

[0008] The polyolefin-based biaxially stretched laminated film according to the present invention is characterized in that it is heat-set at a temperature of 160 ° C to 190 ° C.

Further, the polyolefin-based biaxially stretched laminated film according to the present invention is characterized in that the ratio of the thickness of the layer (E) to the sum of the thicknesses of the layers (D) and (E) is 10 to 50%. I have.

The polyolefin biaxially stretched laminated film according to the present invention has a strength at break in the longitudinal direction of 50 to 90 MPa and an elongation at break in the longitudinal direction of 40 to 120% by heat treatment. It is characterized by having.

[0011]

DETAILED DESCRIPTION OF THE INVENTION

The polyolefin-based biaxially stretched laminated film according to the present invention will be specifically described below.

[0013] The polyolefin-based biaxially oriented laminated film according to the present invention comprises 3 to 9 parts by weight of a petroleum resin (A), 91 to 97 parts by weight of a crystalline polyolefin (B), and (A) and (B). Biaxially oriented layer of crystalline polyolefin on at least one side of layer (D) obtained by biaxially extending a resin composition comprising 5 to 20 parts by weight of cyclic olefin resin (C) based on 100 parts by weight of total (E).

First, each component of the resin composition of the layer (D) used in forming such a laminate will be described.

Petroleum Resin The petroleum resin used in the present invention is a resin obtained by (co) polymerizing a cyclopentene-based fraction or a cyclohexene-based fraction and hydrogenating the same.

Further, examples of the petroleum resin used in the present invention include a resin obtained by hydrogenating an alicyclic polymer obtained by (co) polymerizing a cyclic olefin such as a cyclopentene derivative or a cyclohexene derivative.

As such a petroleum resin, specifically,
For example, Arakawa Chemical's trade name "Alcon P-100" or Tonex Corporation's trade name "Escolets E500"
0 "and the like.

The petroleum resin used in the present invention has a glass transition temperature (hereinafter abbreviated as Tg) of 80 ° C. to 140 ° C., preferably 120 ° C. to 140 ° C.

Polyolefin The polyolefin used in the present invention is a polymer containing propylene or ethylene as a main component, and may further contain components such as butene, pentene, hexene and 4-methylpentene. Specific examples include polypropylene or polyethylene and / or copolymers of these with other monomers (eg, random or block copolymers such as ethylene-propylene copolymers and butene-propylene copolymers).

The polypropylene used herein may be any of known ones, but has an isotactic index (hereinafter abbreviated as II) of 90% or more, more preferably 9% or more.
5% or more, melt flow index at 230 ° C (AS
TM1238, hereinafter abbreviated as MI) is preferably 0.5 to 20 g / 10 min.

The polyethylene mentioned here may be any of low density, high density, linear low density polyethylene, etc., but has a density of 0.920 to 0.950 and an MI at 190 ° C. of 1 to 3.
Are preferred.

The copolymer used herein is preferably an ethylene-propylene random copolymer (hereinafter abbreviated as EPRC), and the ethylene component content of the EPRC is preferably 0.5 to 7% by weight.
More preferably, it is in the range of 1 to 5% by weight.

Cyclic Olefin Resin The cyclic olefin resin used in the present invention includes an ethylene / cyclic olefin random copolymer [I-
1], a ring-opening (co) polymer of a cyclic olefin [I-2],
Any of the above-mentioned hydride [I-3] of the ring-opening (co) polymer and graft-modified [I-4] of these (co) polymers can be used alone or in combination. You can also.

Of these, an ethylene / cyclic olefin random copolymer [I-1] is preferably used. :
[I-1] Obtained by copolymerizing ethylene with a cyclic olefin represented by the following formula [I] or [II], preferably in an ethylene / cyclic olefin (molar ratio) of 20 to 95/80 to 5. Ethylene / cyclic olefin random copolymer,

[0025]

Embedded image

(In the formula [I], n is 0 or 1, m
Is 0 or a positive integer; q is 0 or 1;
^{1 to} R ¹⁸ and Ra and Rb are each independently a hydrogen atom, a halogen atom or a hydrocarbon group optionally substituted with halogen, and R ^{15 to} R ¹⁸ are bonded to each other to form a monocyclic or polycyclic ring And the monocyclic or polycyclic ring may have a double bond, and may form an alkylidene group with R ¹⁵ and R ¹⁶ or with R ¹⁷ and R ^18. Good. ),

[0027]

Embedded image

(In the formula [II], p and q are 0 or a positive integer, m and n are 0, 1 or 2, and R ¹
To R ¹⁹ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group which may be substituted with halogen, and a carbon atom to which R ⁹ or R ¹⁰ is bonded and R ¹³ are bonded to each other. May be directly or via an alkylene group having 1 to 3 carbon atoms, or may be bonded to the carbon atom to which R ¹¹ is bonded. When n = m = 0, R ¹⁵ and R ¹² or R ^{12 15} and R ¹⁹ may combine with each other to form a monocyclic or polycyclic aromatic ring. ),

[I-2] A ring-opened polymer or copolymer of a cyclic olefin represented by the above formula [I] or [II],
[I-3] The above ring-opened polymer or copolymer [I-2]
And [I-4] [I-1] and [I-4]
-2] or [I-3].

The softening temperature (TMA) of the cyclic olefin resin measured by a thermal mechanical analyzer is 6
0 ° C. or higher, preferably 70 ° C. or higher, and a glass transition point
(Tg) is 30 ° C. or higher, preferably 60 ° C. or higher, and more preferably 70 to 200 ° C.

Further, the cyclic olefin-based resin
° C melt flow rate (MFR: ASTM D
1238) is 1 to 100 g / 10 min, preferably 5
５０50 g / 10 min.

Examples of such a cyclic olefin resin include a copolymer of ethylene and bicyclo [2.2.1] -2-heptene (= norbornene) or a derivative thereof (eg, cyclopentadiene-acenaphthylene adduct). No. These cyclic olefin resins can be used alone or in combination of two or more.

Such cyclic olefin resins are described in JP-A-60-168708, JP-A-6-120815, JP-A-61-115912, JP-A-61-115961, and JP-A-61-15961.
1-271308, 61-272216, 62
It can be manufactured according to the method described in each gazette such as -252406 and 62-252407.

As the modifier for the graft modified product [I-4], unsaturated carboxylic acids, derivatives thereof and the like are used.

The resin composition of the layer (D) will be described.

Resin Composition The resin composition used in the layer (D) in forming the polyolefin-based biaxially stretched laminated film in the present invention comprises a petroleum resin, a crystalline polyolefin, and a cyclic olefin resin as described above. , A petroleum resin and a crystalline polyolefin in a ratio of 3:97 to 9:91, preferably 5:95 to 9: 9.
When they are contained at a weight ratio of 1 and the sum of their weights is 100%, the cyclic olefin resin is contained at a weight ratio of 3 to 20%, preferably 5 to 15%.

It should be noted that, as far as the properties of the present invention are not impaired, known additives such as heat stabilizers, antioxidants, crystal nucleating agents,
A slipping agent, an antistatic agent, a viscosity modifier, a light stabilizer and the like may be added.

Such a resin composition can be adjusted by applying a conventionally known melt kneading method.

Next, the (E) layer will be described.

The crystalline polyolefin in the layer (E) is the same as the layer (D), and the crystalline polyolefin preferably has an II of 90% or more and an MI of 1 to 20 g / 10 minutes.

The known additives shown in the layer (D) may be added to the layer (E) as long as the characteristics of the present invention are not impaired.

Biaxially Stretched Laminated Film The biaxially stretched laminated film of the present invention is obtained by supplying the resin composition of the layer (D) and the crystalline polyolefin of the layer (E) as described above to separate extruders. , Resin temperature 2
After melt-mixing in the range of 00 ° C to 260 ° C, it is obtained by laminating by a coextrusion method from a die on a slit and biaxially stretching a cast sheet obtained by cooling and solidifying it.

As the method of biaxial stretching, any known method, for example, sequential biaxial stretching, simultaneous biaxial stretching, or the like can be used. For example, in the case of sequential biaxial stretching, the above cast sheet is heated to 120 ° C. to 145 ° C., and then 4 to 8 in the longitudinal direction.
Draw, preferably 6 to 8 fold, and immediately cool to room temperature. Subsequently, the stretched film is stretched 5 to 12 times, preferably 6 times in the width direction in a tenter maintained at 140 ° C to 165 ° C.
The film is stretched by 10 to 10 times, and then the film is heat-treated at 160 ° C. to 190 ° C. for 3 seconds to 10 seconds while reducing the width of the tenter so that the film is 2% to 15%, preferably 3% in the width direction.
Get ~ 12% reduction in film.

The biaxially stretched laminated film of the present invention has a tensile strength at break in the longitudinal direction of 50 to 90 MPa, preferably 60 to 80 MPa.
MPa, elongation at break in the longitudinal direction of 40 to 120%, preferably 40 to 100%, more preferably 50 to 80%, and impact strength of 1500 kgcm / cm to 2500 kgcm / c
m.

Those having a tensile strength at break in the longitudinal direction of less than 50 MPa and an impact strength of less than 1500 kgcm / cm have poor practical strength when used for packaging films and adhesive tapes, and have a tensile strength at break in the longitudinal direction. If the strength exceeds 90 MPa and the impact strength exceeds 2500 kg cm / cm, the hand-cutting property and the dispenser-cutting property tend to be deteriorated.

Those having a tensile elongation at break in the longitudinal direction of less than 40% have poor practical elongation when used for packaging films and adhesive tapes, and those having a tensile elongation of more than 120% when cut by hand or with a dispenser. Tends to be difficult to cut due to elongation at the time of cutting.

The biaxially stretched laminated film of the present invention has a haze of 1% / 4 to 15% / 4 and has good transparency.

(D) of the biaxially stretched laminated film of the present invention
(E) The layers are each 4 to 8 times in the longitudinal direction and 5 to 5 in the width direction.
It is a layer stretched 12 times, and the ratio of the thickness of the (E) layer to the sum of the thicknesses of the (D) layer and the (E) layer is 10 to 50%, preferably 15 to 40%, more preferably 20 to 30%. is there. When the ratio of the thickness of the layer (E) to the sum of the layers (D) and (E) is 10% or less, the oil resistance is poor, and when it is 50% or more, the tearability tends to decrease.

The total thickness of the film is 10 to 100 μm.
m, preferably 15 to 50 μm, more preferably 20
４０40 μm.

The polyolefin-based biaxially stretched laminated film of the present invention obtained as described above has excellent mechanical properties such as tensile strength, rigidity and impact strength, and also has optical properties such as gloss and transparency. It is also excellent in food hygiene such as non-toxicity and odorlessness.

Further, the polyolefin-based biaxially stretched laminated film according to the present invention is superior in oil resistance to a biaxially stretched film made of a cyclic olefin-based resin. Furthermore, the polyolefin-based biaxially stretched film according to the present invention has improved moisture-proof properties as compared with the conventional polypropylene stretched film, and the heat-treated one has excellent tearability.

The polyolefin-based biaxially stretched laminated film according to the present invention is suitable as a packaging film for applications such as foods and pharmaceuticals and a base film for an adhesive tape.

[0053]

The biaxially stretched polyolefin-based laminated film according to the present invention obtained as described above has a mechanical strength such that the tensile strength at break is 50 MPa or more, the elastic modulus is 1500 MPa or more, and the impact strength is 1500 kgcmcm or more. The haze is 15% / 4 or less and the optical characteristics are excellent, and the moisture proof and moisture permeability are excellent at 0.15 g mm / m2 24 hours or less.
In addition, since the film is a polyolefin-based biaxially stretched laminated film having a tensile breaking strength in the longitudinal direction of the film, the film has both toughness and tearability required for processing steps such as printing and adhesive application.

[0054]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[Measurement Methods and Evaluation Methods] The measurement and evaluation methods for film physical properties and the like used in the following Examples and Comparative Examples are as follows.

A test piece having a breaking strength, a breaking elongation and a modulus of elasticity of 15 mm was placed between the chucks of a tensile tester at 100 mm.
mm, and a tensile test was performed at a speed of 300 mm / min.

Haze Measured based on JIS-K6714 method.

Tearability (hand tearability, dispenser cutability) It was evaluated whether or not the film having a width of 15 mm could be easily torn directly by hand in the lateral direction. The evaluation criteria were “○” for easily tearing without resistance, “△” for slightly resistant but tearing, and “×” for no tearing. The cut property with a commercially available dispenser was evaluated. The evaluation criteria were the same as above.

Impact Resistance Using a film impact tester (manufactured by Toyo Seiki Co., Ltd., sphere having a tip radius of 1/2 inch), the impact resistance was evaluated based on the breaking-through strength of the film.

The moisture permeability was measured based on the JIS-Z 0208 method.

[0060]

Example 1 Polypropylene resin (MI2.0, II at 230 ° C)
96%) and 32% by weight of EPRC (MI 0.5 at 230 ° C.) and 8% by weight of a petroleum resin (“Escolets E5000” manufactured by Tonex Corporation). APL6011T "
The above polypropylene was co-extruded on both sides of a resin composition containing 5 wt% of Mitsui Petrochemical Industry Co., Ltd.) and cooled and solidified on a cooling cast drum maintained at 30 ° C. to form a laminated sheet. Obtained. The laminated sheet was stretched 6 times in the longitudinal direction between roll gaps on a 130 ° C. preheating roll. The laminated stretched film was immediately introduced into a tenter and stretched 10 times in the width direction at 155 ° C., and the film was reduced by 9% in the width direction by heat treatment at 180 ° C. for 7 seconds while reducing the width of the tenter. Subsequently, one surface of the film was subjected to a corona discharge treatment, and a surface treatment was performed so as to have a wetting tension of 40 dyne / cm.

The total thickness of the thus obtained polyolefin-based biaxially stretched laminated film was 35 μm, the layer (D) was 28 μm, and the layer (E) was 7 μm on both sides.

Table 1 shows the characteristic values of the obtained film. From the table, it can be seen that the polyolefin-based biaxially stretched laminated film of the present invention is excellent in gloss, transparency and moisture resistance, and also excellent in tearability (hand tearing property, dispenser cut suitability).

[0063]

Example 2 A polyolefin-based biaxially oriented laminated film was obtained in the same manner as in Example 1, except that the EPRC of the layer (D) was changed to 20% by weight.

The properties of the film thus obtained are shown in Table 1.
It was shown to.

[0065]

Example 3 In Example 1, the preheating roll temperature was set to 14
A polyolefin-based biaxially stretched laminated film was obtained in the same manner except that the temperature was set to 0 ° C and the stretching temperature in the width direction was 165 ° C.

The properties of the film thus obtained are shown in Table 1.
It was shown to.

[0067]

Example 4 Polypropylene resin (MI2.0, II at 230 ° C)
96%) and 32% by weight of EPRC (MI 0.5 at 230 ° C.) and 8% by weight of a petroleum resin (“Escoletto E5000” manufactured by Tonex). APL6011T "
The above polypropylene was coextruded on both sides of a resin composition containing 5 wt% of Mitsui Petrochemical Industry Co., Ltd.) and mixed with 10 wt.
The mixture was heated to 5 ° C. and simultaneously biaxially stretched 6 times in the longitudinal direction and 6 times in the width direction by the tubular method to obtain a polyolefin-based biaxially stretched laminated film. Subsequently, the biaxially stretched laminated film was guided to a tenter, and the film was reduced by 9% in the width direction by heat treatment at 180 ° C. for 7 seconds while reducing the width of the tenter.

The total thickness of the thus obtained polyolefin-based biaxially oriented laminated film was 26 μm, the layer (D) was 20 μm, and the layer (E) was 6 μm on both sides.

As in Example 1, the polyolefin-based biaxially stretched laminated films thus obtained were all excellent in characteristics.

[0070]

[Comparative Example 1] Polypropylene resin (MI2.0, II at 230 ° C)
96%) and 32% by weight of EPRC (MI 0.5 at 230 ° C.) and 8% by weight of petroleum resin (“Escolets E5000” manufactured by Tonex). And cooled on a cooling cast drum maintained at 30 ° C. to obtain a laminated sheet. The laminated sheet was stretched 10 times in the longitudinal direction between roll gaps on a preheating roll at 130 ° C. The laminated stretched film was immediately introduced into a tenter and stretched 10 times in the width direction at 155 ° C., while reducing the width of the tenter at 180 ° C.
A 7 second heat treatment reduced the film width by 9%.

The total thickness of the thus obtained polyolefin-based biaxially stretched laminated film was 33 μm, the layer (D) was 27 μm, and the layer (E) was 6 μm on both sides.

The film sample thus obtained was excellent in gloss and transparency optical properties, but poor in tearability.

[0073]

Comparative Example 2 In Example 1, the heat treatment temperature was 158 ° C.
A polyolefin-based biaxially stretched film was obtained in the same manner except for the above.

The total thickness of the biaxially stretched polyolefin-based laminated film thus obtained was 35 μm, the layer (D) was 28 μm, and the layer (E) was 7 μm on both sides.

The film sample thus obtained was excellent in gloss and transparency optical properties, but poor in tearability.

[0076]

Comparative Example 3 The procedure of Example 1 was repeated except that only 25% of the cyclic polyolefin-based copolymer was added. The film was whitened and cut frequently during transverse stretching. Could not be obtained.

[0077]

[Table 1]

Claims (5)

[Claims] (A) a petroleum resin; 3 to 9 parts by weight;
Crystalline polyolefin; 91 to 97 parts by weight; (C) a cyclic olefin-based resin; 5 to 20 parts by weight ((A)
And (B), a biaxially stretched layer (E) of crystalline polyolefin is laminated on at least one surface of the layer (D) obtained by biaxially stretching the resin composition comprising Polyolefin-based biaxially stretched laminated film. 2. The polyolefin-based biaxially stretched laminated film according to claim 1, which is heat-treated at a temperature of 160 ° C. to 190 ° C. 3. The ratio of the thickness of the layer (E) to the sum of the thicknesses of the layers (D) and (E) is 10 to 50%.
3. The polyolefin-based biaxially stretched laminated film according to item 1. 4. A cyclic olefin-based resin comprising: an ethylene / cyclic olefin random copolymer obtained by copolymerizing ethylene with a cyclic olefin; a hydrogenated product of a ring-opened (co) polymer of a cyclic olefin; 2. The polyolefin-based biaxially stretched laminated film according to claim 1, comprising one or more kinds of graft-modified (co) polymers. 3. 5. The tensile strength at break in the longitudinal direction of the film.
50 ~ 90MPa, elongation at break in the longitudinal direction is 40 ~ 120%
The polyolefin-based biaxially stretched laminated film according to claim 1, which is: