JPH1076620A - Laminated film and glass scatter preventive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the tear resistance of a film by a method wherein the film is formed by laminating at least two layers to each other so as to realize the specified longitudinal and lateral tear propagation resistances and each polyester consisting of each layer has a specified Young's modulus and is stretched at least to one direction. SOLUTION: This film is formed by laminating at least two layers so as to realize the longitudinal and lateral tear propagation resistance of 2,000g/mm or higher and each polyester consisting of each layer has the Young's modulus of 1,400MPa or higher. In addition, the tensile elongation at break of each polyester consisting of each layer is set to be 50% or lower. In order to obtain a laminated film, respective layers are laminated to each other by means of a coextrusion method such as a multimanifold die method, a feed block method and a static mixer method and simultaneously extruded under molten state from a die. As a result, the propagating method of teat is different in layers from each other, resulting in remarkably improving the tear resistance of a film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly to a stretched laminated film resistant to tearing.
It is mainly used for a glass scattering prevention film which is attached to glass to prevent glass scattering when the glass is broken.

[0002]

2. Description of the Related Art Various thermoplastic resin films are industrially produced and used in fields that meet their characteristics. Above all, biaxially stretched polyester films represented by polyethylene terephthalate are used in various fields because of their excellent mechanical properties, thermal properties, electrical properties, and chemical resistance. Generally, these films have low tear resistance due to their high modulus and creep resistance. However, a combination of these seemingly inconsistent properties is required for shatterproof films.

[0003] The shatterproof film is prepared by applying an adhesive to a transparent polyethylene terephthalate film, peeling off the overcoat film, and sticking it to the entire inner surface of the window glass. It is intended to reduce even a little. Also, a thin layer of aluminum is deposited on a polyethylene terephthalate film, and a protective layer is combined on the front surface with a pressure-sensitive adhesive on the back surface. , Bronze and brown) may be added to provide a heat insulating effect.

[0004] Since the shatterproof film is intended to reduce the shattering of the broken pieces even if the glass breaks, it must be a film having high strength and excellent tear resistance so that the tearing of the film does not propagate. Must.

[0005] Such a film is disclosed in
JP-A-0995 and JP-A-6-190997 propose a film in which rigid polyester and a ductile polymer material are laminated in multiple layers in the thickness direction. Although the glass shatterproof film using such a laminated film has improved tear resistance as compared with a conventional film, a further improvement is expected.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a laminated film having significantly improved tear resistance as compared with conventional tear-resistant films.

[0007]

According to the present invention, at least two layers are laminated in a thickness direction, a tear propagation resistance in a longitudinal direction and a transverse direction is 2000 g / mm or more, and each polyester constituting each layer is The present invention relates to a laminated film having a Young's modulus of 1400 MPa or more and being stretched in at least one direction.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the laminated film of the present invention, at least two layers are laminated in the thickness direction, and more preferably, three to 50 layers are laminated. More preferably, 7 to 25 layers are stacked.

[0009] As a method for obtaining a laminated film, a polyester constituting each layer which has been sufficiently dried is supplied to each extruder, and after passing through a filter selected as necessary,
It is preferable that the respective layers are laminated using a co-extrusion method such as a known technique such as a multi-manifold die method, a feed block method, or a static mixer method, and the layers are melt-coextruded from the die. The multi-manifold method uses a die having a plurality of manifolds. In this type, after the resin flows into the manifold corresponding to each layer from the inlet and the flow is widened across the die width in the manifold,
It is discharged through a joining slit. In the feed block method, a combined flow is formed by a feed block before a plurality of resins are fed into a die, and then fed into a usual single manifold die to widen and extrude the flow. In addition, the static mixer method is a method in which several types of resins combined in a certain arrangement are divided into multiple layers by a mixer, and is suitable when the arrangement of the laminate is a simple repetition of the arrangement. The film-like laminate obtained by any of these methods is rapidly cooled and solidified on a casting drum controlled at a temperature of 20 to 60 ° C. to be in an amorphous state. At this time, it is more preferable to improve the adhesion between the drum and the film using a known electrostatic application device. The laminated film is preferably stretched in at least one direction, more preferably in two directions. As a method of biaxial stretching, a cast film is first stretched in the longitudinal direction between rolls having a difference in peripheral speed, and then laterally stretched by a tenter that grips both ends of the film with clips, so-called sequential biaxial stretching in which heat treatment is performed. The method is most preferably used.

In the laminated film of the present invention,
Each polyester constituting each layer has a Young's modulus of 14
00MPa or more is required, 1400MPa or more and 600
It preferably has a Young's modulus of 0 MPa or less.
This is because such polyester is hardly deformed by an external force.

Further, the tensile elongation at break of each polyester constituting each layer must be 50% or less.
When it is 1% or more and 50% or less, the breaking strength is sufficiently high, so that it is more preferable.

Further, each polyester constituting each layer has a Young's modulus of 1400 MPa or more, and has a 50%
It is preferable to satisfy the following tensile elongation at break, since the way of propagation of the tear varies depending on each layer and the tear resistance is greatly improved.

In the laminated film of the present invention, the laminated film has a tear propagation resistance of 2000 g / mm in the longitudinal and transverse directions.
2,000 g / mm or more and 500 or more
It is preferably not more than 00 g / mm. More preferably, the film has a longitudinal and transverse tear propagation resistance of 40.
00 g / mm or more, more preferably 7000 g
/ Mm or more. Films having a tear propagation resistance of less than 2000 g / mm in the longitudinal and transverse directions of the film are not preferable because there is no significant difference compared to ordinary polyester films, and the film does not have sufficiently improved tear resistance.

The F-5 value of the laminated film in the longitudinal and transverse directions is preferably 100 MPa or more, more preferably 100 MPa or more and 500 MPa or less. More preferably, the F-5 value in the vertical or horizontal direction is 150M
It is good to be Pa or more. When the F-5 value in the longitudinal direction and the lateral direction of the film is 100 MPa or less, it is not preferable because the film can easily be plastically deformed by the force applied to the film and easily deformed by impact. Preferably, the laminated film having a tear propagation resistance in a longitudinal direction and a transverse direction of 2000 g / mm or more and an F-5 value in a longitudinal direction and a transverse direction of 100 MPa or more is a polyester having sufficiently high strength and excellent tear resistance. It can be called a film.

In the laminated film of the present invention, the polyester constituting the main layer preferably has an average value of tear propagation resistance in the longitudinal and transverse directions of 2000 g / mm or less. The main layer refers to a layer having the largest lamination ratio among the layers constituting the laminated film. Further, the average value of the tear propagation resistance in the longitudinal direction and the transverse direction of the polyester constituting the main layer is preferably that of the stretched film. As the stretching method, the glass transition temperature Tg of the polyester constituting the main layer is used.
It is performed by sequential biaxial stretching in which the film is stretched 3 times to 3.5 times in the longitudinal and transverse directions at a temperature of + 5 ° C. to Tg + 15 ° C. and heat-treated at a temperature of 140 ° C. to 240 ° C. Surprisingly, the tear propagation resistance of such a monolayer is 2000 g / m 2.
By laminating polyesters having m or less in multiple layers, the tear propagation resistance is greatly improved, and a tear-resistant film that has never existed before can be obtained.

The polyester in the present invention is a polymer obtained by condensation polymerization of a dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, Etc., and
The diol is represented by ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol, polyalkylene glycol, bisphenol A ethylene oxide adduct and the like. Specifically, for example, polymethylene terephthalate, polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-p-oxybenzoate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalate and the like are used. Of course, these polyesters may be a homopolymer or a copolymer, and as the copolymerization component, for example, diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol, and bisphenol A ethylene oxide adduct, Dimer acid, adipic acid, sebacic acid,
Dicarboxylic acid components such as phthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are used. Further, as long as the effect of the present invention is not impaired, a flame retardant, a heat stabilizer,
An antioxidant, an ultraviolet absorber, an antistatic agent, a plasticizer and the like may be blended.

The laminated film of the present invention preferably contains a polyester copolymerized with a bisphenol A group. More preferably, it contains at least one layer of a polyester obtained by copolymerizing an ethylene oxide adduct of bisphenol A. More preferably, a layer (a layer) composed of a polyester mainly composed of polyethylene terephthalate and a layer (b) composed of a polyester in which an ethylene oxide adduct of bisphenol A is copolymerized
Layers) at least one layer at a time. The copolymerization ratio of the ethylene oxide adduct of bisphenol A is preferably at least 5 mol% based on all diol components.
More preferably, it is at least 20 mol%, and 50 mol%
More preferably, it is the above. The order of the polyester to be laminated is not particularly limited, but it is preferable that the layers a and b are alternately laminated. Layers other than the layer a and the layer b may be laminated between them. The thickness of the layer a is preferably 1 to 50 μm, and 5 to 25 μm.
More preferably, it is μm. The thickness of the layer b is preferably 10 μm or less, more preferably 3 μm or less. Such a laminated film has high strength and excellent tear resistance.

As long as the object of the present invention is not impaired, a hard coat layer, an adhesive layer, a metal deposition layer, a colored layer, an ultraviolet absorbing layer, etc. may be provided on any one or both surfaces of the film in any combination. Absent. The adhesive is required when fixing the glass shatterproof film to the glass surface, heat,
It can be activated by a solvent, pressure or a combination thereof, such as acrylate. Further, the hard coat layer is suitable for protecting the glass shatterproof film from mechanical abrasion when the film is attached or washed.

[0019]

[Evaluation method of physical properties]

(1) Tearing Propagation Resistance A light-weighted elementaldorf tearing tester manufactured by Toyo Seiki Seisaku-sho, Ltd. is used. 63.5m long sample film
m, sample a rectangle of 50.8 mm in width, make a vertical 12.7 mm cut at the center of both grips along the horizontal direction, and determine the tearing force (g) for the remaining 50.8 mm. This force was divided by the thickness of the film to obtain the tear propagation resistance (g / mm).

(2) Young's modulus and tensile elongation at break The Young's modulus and tensile elongation at break of the polyester constituting each layer were in accordance with ASTM test method D882-88. The sample film was an unstretched film obtained by quenching and solidifying on a casting drum controlled at a temperature of 25 ° C. and improving the adhesion between the drum and the film using a known electrostatic application device. A sample film having a width of 10 mm was set on a tensile tester RTA-100 manufactured by Orientec Co., Ltd. so as to have a chuck-to-chuck length of 100 mm, and the tensile speed was 100 mm at 23 ° C. and 65% RH.
The tensile test was performed at a rate of / min, and the Young's modulus (MPa) and tensile elongation at break (%) were measured.

(3) F-5 value A sample film having a width of 10 mm was placed on a tensile tester RTA-100 manufactured by Orientec Co., Ltd., and the length between chucks was set to 50 m.
m, and a tensile test is performed at a tensile speed of 200 mm / min under the conditions of 23 ° C. and 65% RH, and the strength at 5% elongation of the film is measured. The F-5 value (MPa) is obtained.
And

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments.

Examples 1 to 6 Polyethylene terephthalate (A) (intrinsic viscosity 0.6
5, glass transition temperature 79 ° C, Young's modulus 1990 MPa,
The pellet having a tensile elongation at break of 4.2%) was vacuum-dried at 180 ° C. for 3 hours, and then supplied to the extruder 1 heated to 280 ° C. The dicarboxylic acid component is isophthalic acid 49mo.
1%, terephthalic acid 51 mol%, diol component is ethylene glycol 35 mol%, polyester (B) comprising ethylene oxide adduct of bisphenol A 65 mol% (intrinsic viscosity 0.65, glass transition temperature 75 ° C.,
The pellets having a Young's modulus of 2300 MPa and a tensile elongation at break of 3.8%) were vacuum-dried at 55 ° C for 24 hours, and then supplied to the extruder 2 heated to 280 ° C. Each polyester extruded from the extruder was alternately laminated in the thickness direction in the mixer section, and formed into a sheet from a T-die. Further, this film was adhered and solidified on a cooling drum having a surface temperature of 25 ° C. by electrostatic force to obtain an unstretched cast film.

The unstretched film is guided to a plurality of rolls heated to 90 ° C. and preheated, then longitudinally stretched at a stretch ratio of 3.3 times, and guided to a tenter in which both ends are gripped by clips, and is heated at 90 ° C. After a transverse stretching of 3.3 times, a heat treatment was performed at 140 ° C. Table 1 shows the ratio of the thickness of the layer A to the layer B of the obtained film, the number of layers, the tear propagation resistance, and the F5 value.
The thickness of the laminated films of Examples 1 to 6 was about 25 μm.
Unified.

Comparative Example 1 The polyethylene terephthalate of Examples 1 to 6 was dried in a single layer under the same conditions as in Examples 1 to 6, extruded, stretched in the longitudinal direction, and subsequently stretched in the transverse direction and subjected to heat treatment. The thickness of the obtained film was 25 μm, and the F5 value was 11 in the vertical direction.
0 MPa and 130 MPa in the horizontal direction, and the tear propagation resistance was 880 g / mm in the vertical direction and 800 g / mm in the horizontal direction.

Comparative Examples 2 to 4 The polyethylene terephthalate (A) pellets of Examples 1 to 6 were vacuum-dried at 180 ° C. for 3 hours and then supplied to the extruder 1 heated to 280 ° C. The dicarboxylic acid component is composed of 60 mol% of terephthalic acid and 40 mol of sebacic acid.
%, Diol component is ethylene glycol 100mol%
Polyester (B) (intrinsic viscosity 1.2, glass transition temperature 2 ° C, Young's modulus 85 MPa, tensile elongation at break 33
(0%) was vacuum-dried at 85 ° C for 24 hours, and then supplied to the extruder 2 heated to 280 ° C. The polyester extruded from each extruder was alternately laminated in the thickness direction in a mixer section, and formed into a sheet shape from a T-die. Further, this film was adhered and solidified on a cooling drum having a surface temperature of 25 ° C. by electrostatic force to obtain an unstretched cast film.

The unstretched film was guided to a plurality of rolls heated to 90 ° C. and preheated, and then longitudinally stretched at a stretching ratio of 3.3. The film was guided to a tenter in which both ends were gripped with clips and stretched 3.3 times at 90 ° C.
Heat treatment was performed at 140 ° C. Table 2 shows the ratio of the thicknesses of the layers A and B, the number of layers, the tear propagation resistance, and the F5 value of the obtained film. Further, the thicknesses of the laminated films of Comparative Examples 2 to 4 were unified to about 25 μm.

[0028]

[Table 1]

[Table 2]

[0029]

The laminated film of the present invention is excellent in mechanical properties and greatly improved in tear resistance as compared with conventional ones, and is suitable for applications such as glass shatterproof films.

Claims (10)

[Claims] 1. A laminate having at least two layers laminated in the thickness direction and having a tear propagation resistance of 2000 g /
mm or more, each polyester constituting each layer has a Young's modulus of 1400 MPa or more, and is stretched in at least one direction. 2. The laminated film according to claim 1, wherein the tensile elongation at break of each polyester constituting each layer is 50% or less. 3. The laminated film according to claim 1, comprising at least one layer mainly composed of a polyester obtained by copolymerizing a bisphenol A group. 4. The laminated film according to claim 1, comprising at least one layer mainly composed of a polyester obtained by copolymerizing an ethylene oxide adduct of bisphenol A. 5. The tear propagation resistance (g / m) of the polyester constituting the main layer of the laminated film in the machine direction and the transverse direction.
The laminated film according to any one of claims 1 to 4, wherein the average value of m) is 2000 g / mm or less. 6. The vertical and horizontal F-5 values are 100M.
The laminated film according to any one of claims 1 to 5, wherein the laminated film is Pa or more. 7. The laminated film according to claim 1, wherein five or more layers are laminated in a thickness direction. 8. The method according to claim 1, wherein at least one layer mainly composed of polyethylene terephthalate is provided.
The laminated film according to claim 7. 9. A glass shatterproof film comprising a pressure-sensitive adhesive layer on one side of the laminated film according to any one of claims 1 to 8. 10. The glass shatterproof film according to claim 9, wherein a hard coat layer is formed on the surface opposite to the surface where the pressure-sensitive adhesive layer is provided.