JP2000246828A - Heat-pressed laminate and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high quality heat-pressed laminate free from curling and printed pattern dislocation. SOLUTION: In a heat-pressed laminate, one is a plastic film or its laminate, the other is a plastic film having at least two layers 6 kg/mm2 or below in tensile strength at break or its laminate, and at least one is has a lamination surface of 100 deg.C or below Vicat softening point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocompression laminated body which does not use an adhesive or a solvent in a laminating step, and a method for producing the same.

[0002]

2. Description of the Related Art Increase in strength, protection of printing, improvement of beautifulness,
It is well known that another plastic film or the like is laminated on a plastic film for use in packaging and the like for the purpose of improving heat sealing properties and gas barrier properties. As a laminating method, a printing method is applied to a base film, if necessary, then an adhesive is applied, and then, a dry laminating method of laminating a film having other characteristics is already disclosed in JP-A-56-7711.
No. 6, JP-A-56-109726, JP-A-5-109726
Japanese Patent Application Laid-Open No. 7-47624 proposes a thermocompression lamination method that does not use an organic solvent in the laminating step. The thermocompression lamination method is different from the dry lamination method
Because it does not use organic solvents, it has high environmental hygiene,
Since the drying process can be omitted at the time of lamination, the number of steps can be reduced.

[0003]

However, in the thermocompression bonding method proposed in each of the above publications, even if a laminate of good quality can be obtained under certain conditions, it takes a long time for maintenance and the like to be performed. Also, the allowance for obtaining a good laminate was narrow, and in some cases, the quality of the laminate was large. Specifically, in the conventional thermocompression laminating method, since the heat and pressure are literally applied for lamination, the obtained laminate is deformed and causes a curl phenomenon, or a pattern shift occurs when printing is performed. , Etc. could not be easily solved. Furthermore, in order to solve the problem, a method of laminating at a low temperature is conceivable, but in the laminating method disclosed in each of the above-mentioned publications, a film adheres to one surface of a roll nip device used as a thermocompression bonding device. However, it has been extremely difficult to provide a laminate having a substantially low temperature and good quality at a substantially low temperature due to troubles such as poor sliding between the film and the guide roll or nip roll of the thermocompression bonding apparatus.

In view of such circumstances, the present inventors have conducted intensive studies and as a result, have provided a method for thermocompression laminating a plastic film or a plastic film laminate at a substantially low temperature and easily. The purpose is to easily improve the quality of the laminate obtained by the method such as curl, pattern distortion, slip, etc., or to expand the allowance of the conditions for obtaining a good laminate, and to easily obtain a thermocompression laminate Thus, the present invention has been completed.

[0005]

As a means for solving the above-mentioned problems, the present invention provides a plastic film (A) having one side.
Or a laminate (A ′) thereof, and the other has a tensile fracture strength of 6
Thermocompression bonding comprising a plastic film (B) comprising at least two layers of kg / mm ² or less or a laminate (B ′) thereof and at least one of which has a laminated surface having a Vicat softening point of 100 ° C. or less. It is a laminate.

Further, the plastic film (B) or the laminate (B ') thereof is characterized in that the melting point of the laminated surface is lower than the melting point of the non-laminated surface by 20 ° C. or more. Further, the non-laminated surface of the plastic film (A) or the laminate (A ′) constituting the laminate has a glossiness of 100% or more.

Further, the method is characterized in that a step of laminating with a roll nip device in which a surface temperature of a heating roll is 40 to 100 ° C. is provided when obtaining a thermocompression-bonded laminate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The plastic films (A) and (B) according to the present invention are not particularly limited. Examples of the plastic film (A) include polyolefins such as polyethylene, polypropylene, polybutene and polymethylpentene; Nylon 6, Nylon 6, 6, Nylon 6, 6, 1
Polyamides such as 2 nylon, 12 nylon, aromatic nylon resin, amorphous nylon and the like, polyesters such as polyethylene terephthalate and polybutylene terephthalate,
Generally, a plastic film of 100 μm or less containing polyacrylonitrile, polycarbonate, polystyrene, polyvinyl chloride, polyvinylidene chloride or the like can be exemplified. Examples of the laminate (A ') include a laminate of the plastic film (A) exemplified above and a nonwoven fabric, paper, synthetic paper, warif, metal composite material, or the like.

Examples of the plastic film (B) include polyethylene such as polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene and ultra-low-density polyethylene, and polyolefins such as polybutene and polymethylpentene. And copolymers containing these monomer units as main components, for example, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene methacrylic acid copolymer. Polymer, saponified ethylene vinyl acetate copolymer, partially saponified product, ionomer, etc., or modified products thereof with maleic anhydride, 6 nylon, 6,66 nylon, 6,1
Polyamides such as 2 nylon, 12 nylon, aromatic nylon resin, amorphous nylon and the like, polyesters such as polyethylene terephthalate and polybutylene terephthalate,
It is composed of at least two layers including polyacrylonitrile, polycarbonate, polystyrene, polyvinyl chloride, polyvinylidene chloride and the like.

The laminate (B ') includes the plastic film (B) exemplified above, a nonwoven fabric, paper,
Examples thereof include those obtained by laminating synthetic paper, warif, metal composite material, and the like.

The plastic film (B) or its laminate (B ′) has a tensile breaking strength of at least 6 kg / mm ² in at least one of a longitudinal direction and a direction perpendicular to the longitudinal direction.
Preferably 5 kg / mm ² or less, more preferably 4 kg / mm ²
/ Mm ² or less. Tensile breaking strength is 6kg / m
Beyond m ^2, the film becomes too hard, difficult adhesion strength or the adhesive strength during thermocompression bonding lamination is obtained,
Also, the desired transparency and glossiness tend not to be obtained.

Further, of the plastic film (A) or its laminate (A '), the plastic film (B) or its laminate (B'), the material forming the surface to be laminated has a Vicat softening point of 100 °. It is desirable to have a resin of C or less, and any one of, preferably, both of the laminated surfaces of the plastic films (A) and (B) or the laminates (A ′) and (B ′) thereof. It is desirable to have a resin having a Vicat softening point of 100 ° C. or less. Also preferably, it is desirable to have a Vicat softening point of 80 ° C. or less,
More preferably, it has a Vicat softening point of 60 ° C. or less. Vicat softening point is 100 ° C
If it exceeds 300, the laminated surface will be hard, and it will be difficult to obtain sufficient adhesion strength or adhesion strength after thermocompression lamination, and it will be difficult to obtain good transparency and glossiness. Sufficient thermocompression bonding strength means that peel strength is 50 g /
It is 15 mm or more, preferably 100 g / 15 mm or more, and more preferably 180 g / 15 mm or more.

As a material having a Vicat softening point of 100 ° C. or less for forming a laminate surface, for example, a vinyl acetate content is about 3 to 50% by weight, preferably 15 to 48% by weight.
%, More preferably 19-47 wt% ethylene vinyl acetate copolymer, acrylic acid content of about 2-25 wt%, preferably 5-20 wt% ethylene acrylic acid copolymer, and methyl acrylate content of 3-5 wt%. 40wt%
About 15 to 35 wt% ethylene methyl acrylate copolymer, methacrylic acid content of 2 to 30 wt%
Ethylene methacrylate copolymer of about 8 to 15 wt%, ethyl acrylate content of about 3 to 40 wt%, preferably 15 to 35 wt% of ethylene ethyl acrylate copolymer, butene having a butene content of 40 wt% or more Examples thereof include (co) polymers, ionomers having a methacrylic acid content of about 2 to 30% by weight, preferably 3 to 15% by weight, or modified products thereof.

By specifying the plastic film (A), the laminate (A '), the plastic film (B), and the laminate (B') as described above, lamination can be performed at a low temperature. When printing is performed, a high-quality laminate body such as no misregistration can be easily obtained.

The material forming the laminated surface includes a lubricant,
It may contain an antiblocking agent, an antistatic agent, an antioxidant, a deodorant, and the like. As lubricants, fatty acids, fatty acid metal salts, silicone oils, waxes, stearic amide, oleic amide, palmitic amide,
Fatty acid amides such as erucic acid amide and behenic acid amide, ethylenebisfatty acid amide, derivatives thereof,
And their modified products. The coefficient of dynamic friction of the laminate surface is 0.05 to 2.0, preferably 0.1 to 2.0.
It is desirable to be in the range of 1.5, more preferably 0.15 to 1.0. If the coefficient of kinetic friction is less than 0.05, it tends to slip too much when the film is wound into a long length,
If it exceeds 2.0, slippage is so poor that wrinkles are generated when the film is wound into a long length, it is difficult to pass through the film when applied to a thermocompression laminating apparatus, and scratches are liable to occur.

Examples of the antiblocking agent include inorganic particles such as silica, talc, feldspar, calcium carbonate, titanium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, aluminosilicate, clay, kaolin, and glass, and polymethacrylic. Examples thereof include organic particles such as acid methyl copolymers and urea resins, and fatty acid-coated products thereof. Examples of the antistatic agent include fatty acid esters such as glycerin fatty acid ester and sorbitan fatty acid ester, condensation products such as fatty acid and diethanolamine, N, N bisaliphatic amines, and derivatives obtained therefrom, and alkyl sulfonates. Etc. can be exemplified.

After the thermocompression lamination, an aging treatment may be performed after the thermocompression lamination in order to promote the transfer of the various additives to the surface of the thermocompression laminate and further impart the dimensional stability of the thermocompression laminate. The aging condition may be appropriately selected depending on the type of the film material and the additive. Aging is preferably performed at 25 to 45 ° C. for 5 to 24 hours.

Plastic film (B) for laminating by thermocompression bonding for the purpose of imparting heat sealing property
As a uniaxially stretched film rather than a biaxially stretched film,
More preferably, it is a non-stretched film. Further, when the laminate is used as a package and sufficient heat sealing strength is required, depending on the material, an adhesive layer may be provided between the layer forming the laminate surface and the layer forming the non-laminate surface. Good. A sufficient heat seal strength when used as a package is 500
g / 15 mm or more, preferably 1000 g / 15 mm or more, more preferably 2000 g / 15 mm or more.

If necessary, the surfaces of the plastic films (A) and (B) and the laminates (A ') and (B') to be laminated thereon may be air, nitrogen, helium, argon or the like. A surface treatment such as a corona discharge treatment, a plasma treatment, a flame treatment, an acid treatment, or a sandblast treatment in an active gas may be performed. Especially when the plastic film (A) or its laminate (A ') is printed, lamination of the plastic films (A), (B) or their laminates (A'), (B ') The surface is
Due to the surface treatment and the like, the wetting index is 35 to 75 dyn.
e / cm, preferably 40 to 70 dyne / cm. If it is less than 35 dyne / cm, especially on the laminated surface of the plastic film (B), it tends to be difficult to obtain the adhesive strength at the time of thermocompression bonding with the printed portion of the plastic film (A).
If it exceeds e / cm, the stickiness of the film increases,
Workability before lamination tends to be poor.

On the laminated surface of the plastic film (A) or its laminate (A '), for example, toluene, IP
Printing may be performed using an ink using an organic solvent such as A (isopropanol) or ethyl acetate as a solvent, or an ink using water or a mixture of alcohol and water as a solvent. According to the present invention, since no pattern shift occurs, it is even more preferable.

The melting point (hereinafter referred to as mp1) of the material forming the laminated surface of the plastic film (B) or the laminate (B ') thereof is based on the melting point (hereinafter referred to as mp2) of the material forming the layer of the non-laminated surface. It is desirable to have a configuration lower than 20 ° C. or more. The melting point of each layer refers to a melting peak temperature measured by a differential scanning calorimeter (DSC) at a temperature of 10 ° C./min in accordance with JIS K 7121. When a plurality of melting peak temperatures are obtained, The minimum value of mp1 and the maximum value of mp2 are defined as the melting point of the layer. The difference between the melting points is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, still more preferably 40 ° C. or higher, and most preferably 60 ° C. or higher. If the temperature is less than 20 ° C., stickiness and slippage are likely to be deteriorated after thermocompression bonding, and the laminate tends to be very difficult to handle. Further, as the layer on the non-laminated surface, a layer on the opposite side of the laminated surface (the surface to be laminated) can be particularly exemplified.

The roll nip device according to the present invention is not particularly limited, and a known method may be used. However, a method of nipping a heated metal roll and a rubber roll is simple and preferable. The nip pressure is 5 to 300 kg / linear pressure.
cm, preferably 10 to 150 kg / cm, more preferably 15 to 100 kg / cm. If it is less than 5 kg / cm, good adhesion and adhesive strength may not be obtained, and if it is more than 300 kg / cm, the abrasion of the rubber roll is severe, and it tends to be impractical. In order to further increase the laminating speed, preheating of the film by contacting another roll in front of the roll nip device, or preheating by increasing the contact time of the film with the metal roll of the roll nip device, infrared heating, etc. Preheating by non-contact heating may be given. The laminating speed is usually about 10 to 200 m / min, but is not particularly limited thereto.

As for the heating method, a method of heating from the side of the plastic film (A) or the laminate (A ′) thereof,
A method of heating from the side of the plastic film (B) or its laminate (B ') or a method of heating from both sides can be considered. According to the gist of the present invention, the plastic film (B) or its laminate (B') A method of heating from the side is more preferable.

The heating roll according to the present invention, which is substantially thermocompression-bonded, literally means that the laminate is not thermocompression-bonded before passing through a roll nip device, but is thermocompression-bonded after passing through a roll nip device. Alternatively, the surface temperature of the roll is preferably 40 to 100 ° C, more preferably 45 to 90 ° C, still more preferably 50 to 80 ° C, and most preferably 55 to 75 ° C. C. If it exceeds 100 ° C., problems such as deterioration of lubricity due to thermal deformation of the film tend to occur, and if it is less than 40 ° C., sufficient adhesive strength tends to be not obtained. In order to produce a laminate of good quality, the laminating speed, thermocompression roll nip pressure, film tension before and after lamination, etc. may be appropriately selected depending on the roll temperature.

The glossiness of the unprinted portion of the non-laminated surface of the plastic film (A) or the laminate (A ') forming the laminate according to the present invention is determined by the appearance and the beautifulness of the laminate. 10 to create a feeling
Desirably, it is 0% or more. More preferably 120
% Or more, more preferably 140% or more. In order to make the glossiness a certain value or more, the laminating speed, laminating temperature and nip roll pressure may be appropriately selected, but according to the present invention, since the laminating surface has a low softening point,
Compared to the conventional thermocompression lamination method, it can be said that a glossy feeling is easily exhibited, and thus a laminate having a high glossiness is easily obtained.

[0026]

The present invention will be specifically described below with reference to examples and comparative examples.

The measurement of each physical property value and the evaluation of the pattern shift and the transparency of the uncoated portion are as follows.

The tensile breaking strength of the plastic film (B) or its laminate (B ') is measured according to JIS K-7127, and the tensile strength is determined in the longitudinal direction of the film or in the direction perpendicular to the longitudinal direction. Strength.

The Vicat softening point is determined according to JIS K 7206 in accordance with JIS K 7206. The material constituting the surface of the plastic film (A), the laminate (A '), the plastic film (B), and the laminate (B') is laminated. It was measured by the test load A method.

The melting point (mp) of the material constituting the laminated surface of the plastic film (B) and its laminate (B ')
1) and the melting point of the material constituting the non-laminated surface (mp2)
Is as follows. That is, the melting point is defined by JIS K 7121, and the temperature is raised at 10 ° C./min.
Refers to the melting peak temperature measured in C), and when a plurality of melting peak temperatures are obtained, the minimum value of mp1 and the maximum value of mp2 are defined as the melting point of the layer.

The glossiness of the non-laminated surface of the plastic film (A) or its laminate (A ') is opposite to the laminated surface of the plastic film (A) or the laminate (A') forming the laminate. This is a measurement of the glossiness of the portion of the surface that has not been printed, and
According to SZ8741, the measurement was performed with an incident angle and a light receiving angle of 45 degrees.

The thermocompression bonding strength of the uncoated part was determined at a tensile speed of 20
The peeling was performed at a rate of 0 mm / min in the direction of 180 degrees to measure.

The coefficient of kinetic friction of the non-laminated surface of the film (B) after lamination was measured according to ASTM D-1894.

The heat-sealing strength between the films (B) of the laminate was 130 ° C., 2 kg / cm ² , and a test piece heat-sealed at 1 second at a tensile speed of 200 mm / min.
Peeled in 80 degree direction and measured

The evaluation of the pattern misalignment and the transparency of the uncoated area are visually observed.

Example 1 Propylene homopolymer (MF
R 3), melting point of 138 ° C., Vicat softening point of 12
A propylene ethylene copolymer (MFR 8) having an ethylene content of 3.8% by weight at 3 ° C. was laminated and co-extruded from a T die at 230 ° C., and then roll-stretched 5 times in the longitudinal direction at a temperature of 120 ° C. The film is stretched 8 times tenter in a direction perpendicular to the film at 150 ° C.
m, propylene ethylene copolymer layer 2 μm, total thickness 22
A μm biaxially oriented polypropylene film A-1 was obtained. On the other hand, an ethylene vinyl acetate copolymer having a melting point of 66 ° C. and a Vicat softening point of 35 ° C. (M
FR 30), melting point 138 ° C, Vicat softening point 1
Propylene ethylene copolymer (MFR 8) having an ethylene content of 3.8% by weight at 23 ° C.
Laminate co-extrusion was performed from a T die at 80 ° C. to obtain a film B-1 having an ethylene vinyl acetate copolymer layer of 4 μm, a propylene ethylene copolymer layer of 36 μm, and a total thickness of 40 μm.
To improve workability, 0.3 wt% of silica was added as an anti-blocking agent and 0.3% of erucic acid amide was added as a lubricant to the film B-1 before extrusion. Propylene-ethylene copolymer surface of film A-1 and film B
-1, a film B-1 was placed in contact with a heated metal roll, the surface temperature of the heated metal roll was 70 ° C., the laminating speed was 120 m / min, and the thermocompression roll nip pressure ( Linear pressure) 40
The laminate was laminated at kg / cm to obtain a laminate 1.

(Example 2) 70% of water and ethyl alcohol 3 were applied to the surface of the propylene-ethylene copolymer of A-1 in Example 1.
An ink using a mixture of 0% and a solvent as a solvent was printed and dried so that the printing area was about 40% of the total area, to obtain a film A-2. A film B-2 was obtained in the same manner as in Example 1, except that the surface of the ethylene-vinyl acetate copolymer of B-1 in Example 1 was subjected to a corona discharge treatment in air at 30 W · min / m ² .
Next, a laminate 2 was obtained in the same manner as in Example 1.

Example 3 A nitrogen concentration of 9 W / min at 30 W · min / m ² was applied to the surface of the ethylene-vinyl acetate copolymer of B-1 in Example 1.
Example 2 except that a corona discharge treatment was performed at 8 vol%.
A film B-3 was obtained in the same manner as described above, and a laminate 3 was obtained in the same manner as in Example 2.

Example 4 Instead of the biaxially oriented polypropylene-based film of Example 3, a biaxially oriented polyethylene terephthalate film having a thickness of 12 μm (Embret PET manufactured by Unitika Ltd.) was designated as A-4. Instead of the ethylene-vinyl acetate copolymer, an ethylene-methyl acrylate copolymer (MFR 20) having a methyl acrylate content of 20 wt%, a melting point of 80 ° C. and a Vicat softening point of 59 ° C. was used. The melting point is 106 ° C and the Vicat softening point is 8
A film B-4 was obtained in the same manner as in Example 3 except that a low-density polyethylene (MFR 8) of 2 ° C was used, and a laminate 4 was obtained in the same manner as in Example 3.

Example 5 Example 4 was repeated except that the biaxially oriented polyethylene terephthalate film of Example 4 was replaced by A-5 instead of a 15 μm thick biaxially oriented 6 nylon film (Emblem ON manufactured by Unitika Ltd.). As well as
A laminate 5 was obtained in the same manner as in Example 4.

Example 6 The melting point was 48 ° C. and the Vicat softening point was 3 in place of the ethylene-vinyl acetate copolymer of Example 1.
Using an ethylene vinyl acetate copolymer (MFR 6) having a vinyl acetate content of 46% by weight of 5 ° C or less, a laminating temperature of 55 ° C, a laminating speed of 40m / min, and a thermocompression roll nip pressure (linear pressure) of 15kg / cm. Except for the above, a film B-6 was obtained in the same manner as in Example 1, and then a laminate 6 was obtained in the same manner as in Example 1.

COMPARATIVE EXAMPLE 1 A monolayer of the propylene-ethylene copolymer of Example 1 was used instead of the two-layer laminate of the ethylene-vinyl acetate copolymer and the propylene-ethylene copolymer of Example 1. Was performed in the same manner as in Example 1 to obtain a laminate 1 ′.

(Comparative Example 2) A monolayer of the ethylene-vinyl acetate copolymer of Example 1 was used instead of the two-layer laminate of the ethylene-vinyl acetate copolymer and the propylene-ethylene copolymer of Example 1. A laminate 2 'was obtained in the same manner as in Example 1 except for the above.

(Comparative Example 3) In place of the two-layer laminate of the ethylene-vinyl acetate copolymer and the propylene-ethylene copolymer in Example 1, a propylene homopolymer having a melting point of 166 ° C (MFR 3) was used. After co-extrusion with the ethylene-vinyl acetate copolymer of Example 1, it was stretched in the same manner as in Example 1, and a propylene homopolymer layer of 36 μm, an ethylene-vinyl acetate copolymer layer of 4 μm, and a biaxially stretched polyolefin film having a total thickness of 40 μm were used. B-3 'was prepared, and a laminate 3' was obtained in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer surface of B-3 'was used as a laminate surface.

The physical properties and evaluations of the obtained laminates are as shown in the table below.

[0046]

According to the present invention, it is possible to easily improve the beautiful appearance of a thermocompression-bonded laminate or to improve the workability in a process after lamination, and to obtain a good laminate in a thermocompression lamination method. Because it is possible to expand the allowance of the conditions, it is possible to perform thermocompression lamination without applying an adhesive in a laminating process even with a relatively simple conventional dry laminating machine or the like, and thermocompression lamination becomes more widespread, It is thought to be very useful for solving various environmental problems.

Continued on the front page F term (reference) 4F100 AA20 AA20H AH02 AH02H AK01A AK01B AK01C AK07 AK64 AK68 BA03 BA04 BA07 BA15 CA19 EH20 EJ192 EJ38 EJ452 JA04 JK02B JK02C

Claims (4)

[Claims] In a thermocompression-bonded laminate, one is a plastic film (A) or a laminate thereof (A '), and the other is a plastic film (B) comprising at least two layers having a tensile breaking strength of 6 kg / mm ² or less. ) Or a laminate (B ′) thereof, at least one of which has a laminate surface having a Vicat softening point of 100 ° C. or less. 2. The thermocompression lamination according to claim 1, wherein the plastic film (B) or the laminate (B ′) has a structure in which the melting point of the laminating surface is lower than the melting point of the non-laminating surface by 20 ° C. or more. body. 3. The thermocompression-bonded laminate according to claim 1, wherein the glossiness of the non-laminated surface of the plastic film (A) or the laminate (A ′) thereof is 100% or more. 4. The heating roll has a surface temperature of 40 to 100 ° C.
The method for producing a thermocompression-bonded laminate according to any one of claims 1 to 3, further comprising a step of laminating with a roll nip device.