JPH11179873A - Manufacturing method of laminate - Google Patents

Abstract

(57) [Problem] To provide a method for producing a laminate in which a decrease in film adhesive strength due to boiling treatment is small. SOLUTION: This is a method for producing a laminate comprising a plastic base material and a resin for extrusion lamination and not using an anchor coating agent, wherein the plastic base material is subjected to a corona treatment satisfying the following conditions. A method for producing a laminate, comprising bonding at least one surface of a material to at least one surface of a resin for extrusion lamination that has been melt-extruded into a film and subjected to ozone treatment, and pressure-bonded. <Corona treatment conditions> (1) Corona treatment density is 30 W × min / m ² or more (2) Corona discharge parameter represented by the following formula is 7 or more Discharge parameter = X / (Y × Z) where X: plastic type Length of corona discharge part in flow direction of substrate (mm) Y: Output frequency of corona treatment (kHz) Z: Gap between insulator and conductor constituting corona treated electrode (mm)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a laminate. More specifically, the present invention relates to a method for producing a laminate comprising a plastic base and a resin for extrusion lamination, wherein the plastic base and the resin for extrusion lamination are firmly bonded without using an anchor coat agent. The present invention relates to a method for producing a laminate adhered to a substrate.

[0002]

2. Description of the Related Art Several kinds of materials are laminated as materials which simultaneously satisfy characteristics that are difficult to have with a single-layer film, such as strength, gas barrier properties, moisture-proof properties, heat-sealing properties, and the like. The laminated body is widely used for packaging materials. Such laminates have different required performance depending on the application.For example, in a system composed of a polyamide resin film and a polyethylene resin film, in addition to the performance of a single layer film constituting the laminate such as gas barrier properties and heat sealability, Also, the adhesive performance between the constituent single-layer films, such as the boil resistance, is important.

As a method for producing a laminate having excellent adhesive performance, for example, a method such as a dry lamination method, an extrusion lamination method, and a wet lamination method can be cited. As a method for forming a heat seal layer on a plastic base material having strength, gas barrier properties and the like as a packaging material, an extrusion lamination method, which is the lowest cost, is widely used. In addition, examples of the extrusion laminating resin used for the heat seal layer include polyethylene, polypropylene, and polyolefin resins such as ethylene copolymers and ionomer resins. in use.

When extruding and laminating these polyolefin-based extrusion laminating resins onto a nylon-based or polyester-based substrate, an anchor coat agent or an adhesive resin having an adhesive property is used in order to develop adhesiveness.

The anchor coating agent is usually diluted with an organic solvent such as xylene or ethyl acetate, applied to the surface of a plastic base material, dried by a dryer, and then melt-extruded for polyolefin extrusion lamination. Laminated with resin. In this method, the anchor coating agent is relatively expensive, the operation steps such as the coating and drying steps of the anchor coating agent are complicated, the working environment is adversely affected by the organic solvent that is a diluting liquid, and the remaining in the final product. There is a possibility that odor caused by an anchor coating agent or an organic solvent may become a problem.

In the method of using an adhesive resin as the resin for extrusion lamination, the above-mentioned anchor coating agent is not required, but the adhesive resin is extremely expensive. Since the roll release property during processing and the thermal stability in the processing temperature range are inferior to, for example, polyethylene resins, processing conditions were sometimes restricted.

That is, the most preferable method for producing a laminate is a method in which a plastic base material and a resin for extrusion lamination are sufficiently bonded without using an anchor coat agent or an adhesive resin.

[0008] As the method, for example, a laminate is obtained by subjecting a melt-extruded polyolefin resin to an ozone treatment, laminating the resin on a plastic substrate, and then aging at a temperature of 50 ° C. or more and the melting point of the polyolefin resin or less. (JP-A-5-193018), extrusion-lamination of a polyethylene resin blown with air containing 1 g / m ³ or more of ozone on a polyester base film coated with an imine-based substance or a polyester-based substance. And a method for producing a laminate (Japanese Patent Application Laid-Open No. 6-246883). Further, an ethylene-methyl acrylate copolymer melt-extruded at 300 ° C. or lower is subjected to ozone treatment, and the ozone-treated surface and a polyester-based plastic base material are treated. (Japanese Patent Application Laid-Open No. 7-89019).

In addition, the present inventors have applied a technique of oxidizing and activating a surface of a plastic base material by a surface oxidizing treatment, and an ozone treatment of an extrusion laminating resin having no adhesive function as its original function. An extrusion laminating technique capable of firmly adhering a plastic base material and an extrusion laminating resin without using an anchor coat agent or an adhesive resin by a method combining activation techniques has been proposed (JP-A-7-314629). Gazette).

[0010] The extrusion laminating technology which does not use an anchor coating agent which applies this surface oxidation treatment exhibits a very high level of film adhesive strength, and shows a performance which is more than sufficient for dry matter packaging. When used in applications, the film adhesive strength was sometimes inferior to products using an anchor coat agent.

It is an object of the present invention to provide a method for producing a laminate in which a decrease in film adhesion strength due to boiling processing is small.

[0012]

In view of such circumstances, the present inventors have conducted intensive studies on the surface activation treatment conditions of a method for producing a laminate without using an anchor coating agent, and as a result, have found that corona under specific treatment conditions. It has been found that the object of the present invention is achieved when the surface of the plastic base material is activated by performing the treatment, and the present invention has been completed.

That is, the present invention relates to a method for producing a laminate comprising a plastic base material and a resin for extrusion lamination and not using an anchor coat agent, wherein a corona treatment satisfying the following conditions is performed. A method for producing a laminate, characterized in that at least one surface of the applied plastic base material and at least one surface of the resin for extrusion lamination that has been melt-extruded into a film and subjected to ozone treatment are adhered and pressure-bonded. <Corona treatment conditions> (1) Corona treatment density is 30 W × min / m ² or more (2) Corona discharge parameter represented by the following formula is 7 or more Discharge parameter = X / (Y × Z) where X: plastic type Length of corona discharge part in flow direction of substrate (mm) Y: Output frequency of corona treatment (kHz) Z: Gap between insulator and conductor constituting corona treatment electrode (mm) Hereinafter, the present invention will be described in detail. explain.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The plastic substrate used in the present invention may be in the form of a film or sheet.
It may be a stretched product or an unstretched product. Further, it may be a coated product, a woven fabric, or a nonwoven fabric. Further, the substrate may be a product bonded to another material, for example, aluminum foil, iron, paper, or the like, as long as the surface of the substrate in contact with the resin for extrusion lamination is made of plastic. In addition, printing may be performed in advance on the surface in contact with the resin for extrusion lamination,
In that case, the type of printing ink is not particularly limited. Further, the surface of the plastic base material may be subjected to a surface treatment such as a corona treatment or a flame treatment as needed. The thickness of the plastic base material is not particularly limited as long as extrusion lamination can be performed. However, considering workability, the thickness is 1 μm or more and 1000 μm or more.
The range is preferably 5 μm or more and 500 μm or less.

The plastic substrate used in the present invention includes, for example, polyamide resin, polyester resin, polypropylene resin, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol resin, polyvinylidene chloride resin, A substrate made of a resin such as a polystyrene resin, a polycarbonate resin, and cellophane is preferable.

Among the above, a plastic substrate made of a polyamide resin is more preferable for use as a liquid material.
A plastic-based substrate made of this polyamide-based resin,
It may be a single-layer film or two or more types of multilayer films. Further, at least the surface of the plastic base material to be laminated with the resin for extrusion lamination may be made of a polyamide resin.

The resin for extrusion lamination used in the present invention includes low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer. And at least one polyethylene resin selected from the group consisting of: Examples of the α-olefin of the ethylene-α-olefin copolymer include α-olefins having 3 to 18 carbon atoms such as propylene, butene-1, hexene-1, octene-1, decene-1, and octadecene-1. Can be The content of these α-olefins is usually 2 to 25% by weight. As the resin for extrusion lamination used in the present invention, low-density polyethylene, high-density polyethylene, or ethylene-α-olefin copolymer is preferable in terms of thermal stability and odor.

The resin for extrusion lamination used in the present invention contains known additives such as antioxidants, antiblocking agents, weathering agents, neutralizing agents, flame retardants, antistatic agents, antifogging agents,
A lubricant, a dispersant, a pigment, an organic or inorganic filler, or the like may be used in combination.

The method for producing a laminate according to the present invention comprises:
A corona treatment is performed on at least one surface of the plastic base material fed from a known extrusion laminator feeder under the following specific conditions, and then ozone is applied to at least a side of the melt-extruded extrusion laminating resin that contacts the plastic base material. Ozone treatment is performed by blowing air containing the resin, and the corona-treated surface of the plastic base material and the ozone-treated surface of the resin for melt extrusion lamination are bonded and pressed.

The above-mentioned corona treatment can be carried out by a known corona treatment apparatus for the purpose of activating the surface of the plastic base material. Corona treatment is performed by applying a high voltage to a load electrode composed of an insulator and a conductor placed at a certain distance and passing the plastic base material into the corona atmosphere generated by the plastic base material. This is a surface activation treatment for activating the material surface. <Corona treatment conditions> (1) Corona treatment density is 30 W × min / m ² or more (2) Corona discharge parameter represented by the following formula is 7 or more Discharge parameter = X / (Y × Z) where X: plastic type Length of corona discharge part in flow direction of substrate (mm) Y: Output frequency of corona treatment (kHz) Z: Gap between insulator and conductor constituting corona treated electrode (mm)

The degree of surface activation is determined by the corona treatment density (W × min / m ² ). In the present invention, the corona treatment density may be 30 W × min / m ² or more. The upper limit is not particularly limited, but is preferably about 300 W × min / m ² from the viewpoint of economy. The corona treatment density is preferably 50 W × min / m ² or more, still more preferably from 80～300W × min / m ^2. 30W
If it is less than × min / m ^2, it is not preferable because the film adhesive strength of the laminate is insufficient.

However, it is sometimes difficult to organize the degree of activation of the surface of the plastic base material by corona treatment only with the corona treatment density (W × min / m ² ). When corona treatment is applied to a plastic substrate, the degree of activation is determined by the gap between the insulator and the conductor that constitute the corona treated electrode (distance between electrodes)
It became clear that the characteristics depended on the characteristics of the corona treatment device such as the shape of the corona treatment electrode and the output frequency. Therefore,
The present inventors have derived the following discharge parameters. When the treatment is performed with a predetermined amount of corona treatment density by using this discharge parameter, the film adhesive strength after the boil treatment of the laminate according to the present invention is estimated even when various treatment conditions of the corona treatment device are different. Became possible. Discharge parameter = X / (Y × Z) where X: length of corona discharge section in the flow direction of the plastic base material (mm) Y: output frequency of corona treatment (kHz) Z: insulation constituting corona treatment electrode FIG. 1 is a conceptual diagram of one embodiment of corona treatment of a plastic base material, wherein X is the length of a corona discharge portion in the flow direction of the plastic base material, and Z is It shows a gap between an insulator and a conductor constituting the corona-treated electrode. The configuration of the electrodes (conductors and insulators) of the corona treatment device is changed depending on whether the plastic base material to be treated has conductivity.

The discharge parameters include the gap (distance between load electrodes) between the insulator and the conductor constituting the corona-treated electrode of the above-mentioned known corona-treating apparatus, the shape of the corona-treated electrode, and the like.
Even when the output frequency or the like is different, it becomes an index of the degree of activation of the substrate surface, and it is preferable that this value be 7 or more. If the upper limit is 7 or more, the effect is not insufficient, but it is preferably 50 or less in consideration of the size of the installed device. Further, the discharge parameter is more preferably from 7.5 to 40. If the discharge parameter is less than 7, the degree of activation is low, and the resulting laminate is not preferable because the boil resistance is insufficient.

Next, the ozone treatment for the melt-extruded resin for extrusion lamination according to the present invention will be described. This ozone treatment can be performed by a known ozone treatment device in order to improve the film adhesive strength of the laminate manufactured in the present invention. The ozone treatment is a step of melt-extruding the resin for extrusion lamination into a film or a sheet, and subjecting at least the surface of the molten film to a surface in contact with the substrate, for example, between air gaps below a T-die. A gas (eg, air) containing ozone can be blown onto the melt-extruded film from a nozzle provided or a blowout port on the slit. The amount of the ozone to be sprayed is preferably 1 to 40 g / m ² , more preferably 1 to 30 g / m ² , per unit area of the melt-extruded resin for extrusion lamination, in consideration of performance characteristics such as adhesion performance of the obtained laminate. m ² .

The processing temperature range for melt-extruding the resin for extrusion lamination is not particularly limited as long as it can be melt-extruded into a film.
~ 340 ° C is preferred.

Further, in the present invention, the step of bringing the ozone-treated surface of the resin for extrusion lamination melt-extruded into contact with the corona-treated surface in a region satisfying the discharge parameters of the plastic base material and pressing the same is performed by a known laminator. , For example, by pressure bonding between a cooling roll and a nip roll.

In the most preferred embodiment of the present invention, corona treatment for a plastic base material and ozone treatment for a resin for melt extrusion lamination are provided on the same line of an extrusion laminator, and the respective treated surfaces are brought into immediate contact with each other in line. Crimping. Further, the time from the corona treatment to the plastic base material to the contact with the ozone-treated resin for melt extrusion lamination and the pressure bonding is preferably as short as possible.
Seconds or less are preferred.

Further, in the present invention, from the viewpoint of further improving the film adhesive strength, a step of aging the obtained laminate while keeping the temperature after lamination may be provided. Aging temperature is 30 ~
The temperature is 60C, preferably 35-50C. If the aging temperature is too low, the effect of improving the film adhesive strength by aging may be difficult to see, and if it is too high, the heat sealability and hot tack performance of the resin forming the sealant layer may be reduced. May be invited. The aging time is usually 1 to 120 hours, preferably 10 to 80 hours.
If the aging treatment time is too short, the effect of the aging treatment is difficult to see, and if it is too long, the resin for extrusion lamination may deteriorate, which is disadvantageous in terms of economy. This aging treatment can be carried out using a normal oven or a room whose temperature can be adjusted.

In the present invention, a coextrusion lamination method, a tandem lamination method, a single lamination method, and the present invention relates to a case in which an extrusion lamination resin is laminated on a plastic base material by any extrusion lamination method such as a sandwich extrusion lamination method. Applicable to all.

[0030]

As described in detail above, according to the present invention,
It is possible to provide a method for producing a laminate in which a decrease in film adhesion strength due to boiling processing is small. The laminate produced by the present invention can be used for various packaging materials, industrial materials, industrial materials, and the like, and is particularly suitable for liquid materials.

[0031]

Next, the present invention will be described based on examples.
The present invention is not limited to these examples. The measurement and evaluation methods performed in Examples and Comparative Examples are as follows. (1) Membrane adhesive strength The laminate was cut into 180 mm x 160 mm, folded in two, and made into a three-side seal bag filled with 80 ml of water, and a small retort high-pressure steam sterilizer RK-3040 manufactured by Alp Co., Ltd. The three-side seal bag was placed in hot water adjusted to 95 ° C., and preheated for 10 minutes, followed by boil processing at 95 ° C. for 30 minutes. Then, it cooled in cold water for 10 minutes. After draining the water in the three-sided seal bag and wiping off the water with a cloth, etc., the width is 15 mm and the length is 1 in the extrusion laminating direction.
After preparing a test piece of a laminate cut out to 50 mm and peeling the adhesive interface between the plastic base material of the test piece and the resin for extrusion lamination over 50 mm in the length direction, an autostrain type tensile test manufactured by Toyo Seiki Co., Ltd. Machine, 2
The peel strength when peeled at 180 ° at a pulling speed of 00 mm / min was measured to evaluate the film adhesive strength. (2) Measurement of the length, output frequency, and gap between the insulator and the conductor constituting the corona treatment electrode in the flow direction of the plastic base material. Kenwood, Inc. was connected to the high voltage output terminal of the step-up transformer of the corona treatment device. A high-voltage probe P6015 manufactured by Tektronix Corporation connected to a 40 MHz oscilloscope CS-4035 manufactured by Tektronix was installed, and corona treatment was performed under predetermined conditions. The discharge voltage waveform of the corona treatment at that time was monitored with an oscilloscope, and the output frequency was determined from the peak-to-peak length of the discharge waveform. The length of the corona discharge portion in the film flow direction was determined by measuring the discharge length on a scale during discharge. Further, the gap between the insulator and the conductor constituting the corona-treated electrode was measured using a gap gauge before discharging.

Example 1 A biaxially stretched nylon film (ONy: Emblem ON-RT manufactured by Unitika Ltd.) was used as a plastic base material.
The resin 1 for extrusion lamination in contact with a plastic base material is a low-density polyethylene (LD: Sumikasen L5816 manufactured by Sumitomo Chemical Co., Ltd .; MFR1).
0 g / min, density 0.917 g / cm ³ ), and linear low-density polyethylene (LL: Sumikasen-α LZ752-1 manufactured by Sumitomo Chemical Co., Ltd.) as the resin for extrusion lamination 2 for forming a sealant layer; MFR10.5g
/ Min, density 0.914 g / m ³ , 1-hexane unit content 14% by weight). Attaching the biaxially stretched nylon film on Shigeru Sumitomo Industries, Ltd. coextrusion laminator feeding machine, feeding at 80 m / min processing speed, a corona treatment density on the surface in contact with the extrusion laminating resin 100W × min / m ² 7. The length of the corona discharge section in the flow direction of the plastic base material is 110 mm, and the output frequency is 8.
The corona treatment was performed under the conditions of 8 kHz and a gap of 1.0 mm between the insulator and the conductor constituting the corona treatment electrode. The discharge parameter at this time was 12.5. At the same time, extrusion laminating resins 1 and 2 were melt-kneaded using extruders 1 and 2 having a diameter of 65 mmφ, respectively. The resin temperature was 300 ° C., the width was 500 mm, and the thickness was 30 μm and 40 μm, respectively, from a dual slot T-die. Melt extrusion was performed under the following conditions. Further, the surface of the melt-extruded extrusion laminating resin 1 which is in contact with the biaxially stretched nylon film is 12 m with respect to the passage area of the laminating resin 1 melt-extruded from a nozzle provided at a position 30 mm below the die.
The laminate was produced by performing ozone treatment under a condition of g / m ² , laminating and bonding to a corona-treated surface of a biaxially stretched nylon film, and winding the laminate with a winder. Table 1 shows the results.

Comparative Example 1 In Example 1, the length of the corona discharge section in the flow direction of the plastic base material was 93 mm, and the output frequency was 10 kHz.
z, the condition that the gap between the insulator and the conductor constituting the corona-treated electrode was 2.6 mm, that is, the discharge parameter was 3.
6 was performed in the same manner as in Example 1 except that the corona treatment was performed. Table 1 shows the results.

Comparative Example 2 In Example 1, the processing speed was 40 m / min, and the corona treatment was performed.
Density of 80W · min / m ^Two, Ozone treatment amount is 19mg / m^Two
And corona discharge in the flow direction of the plastic substrate
The length of the electric part is 52 mm, the output frequency is 17.7 kHz,
The gap between the insulator and the conductor constituting the corona-treated electrode is set as follows.
0 mm, that is, under the discharge parameter 2.9.
Except having performed corona treatment, it carried out similarly to Example 1.
Table 1 shows the results.

[0035]

[Table 1] 1) Out of resin

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment of corona treatment of a plastic base material.

[Description of Signs] X: Length of corona discharge portion in the flow direction of plastic base material Z: Gap between insulator and conductor constituting corona-treated electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29L 9:00

Claims (5)

[Claims] 1. A method for producing a laminate comprising a plastic base material and a resin for extrusion lamination without using an anchor coating agent, wherein the plastic material has been subjected to a corona treatment satisfying the following conditions: A method for producing a laminate, comprising bonding at least one surface of a substrate and at least one surface of a resin for extrusion lamination that has been melt-extruded into a film and subjected to ozone treatment, followed by pressure bonding. <Corona treatment conditions> (1) Corona treatment density is 30 W × min / m ² or more (2) Corona discharge parameter represented by the following formula is 7 or more Discharge parameter = X / (Y × Z) where X: plastic type Length of corona discharge part in flow direction of substrate (mm) Y: Output frequency of corona treatment (kHz) Z: Gap between insulator and conductor constituting corona treated electrode (mm) 2. The method for producing a laminate according to claim 1, wherein the corona treatment density applied to the plastic base material is 50 W × min / m ² or more. 3. The resin for extrusion lamination is low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-
2. The method for producing a laminate according to claim 1, wherein the laminate is at least one polyethylene resin selected from (meth) acrylate copolymers. 4. The method for producing a laminate according to claim 1, wherein the plastic base material and the film made of the resin for extrusion lamination are pressed and then aged at a temperature of 30 to 60 ° C. 5. The method for producing a laminate according to claim 1, wherein the surface of the plastic substrate to be laminated with a polyamide resin or at least a resin for extrusion lamination is a polyamide resin.