JP2003011220A - Lamination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve such a defect that energy for heating is required heretofore because ageing is accompanied after a lamination method using a thermosetting adhesive and there is restriction such that energy for heating is not handled during an ageing period and the capacity of a final product can not be measured if the ageing period is not elapsed. SOLUTION: The thermosetting adhesive is applied to a first sheet 3 by a roller 5 and, after the coated sheet 3 is dried if necessary in a drying zone 8, the coated sheet 3 is pressed between a second sheet 10 and a pair of rollers 11 and 12 under heating to form a laminate 13 of both sheets. Ultrasonic waves are allowed to act on the laminate 13 by an ultrasonic irradiator 15 to accelerate the crosslinking of the adhesive layer to increase adhesive force. After the thermosetting adhesive is applied, ultrasonic waves are allowed to act after the first sheet is previously stuck to the second sheet 10 and, thereafter, the laminate can be dried if necessary.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a problem in that, when laminating long sheets, the adhesive used for laminating is cured in a short time and then handled or used as a product. Difficulty relates to an improved laminating method.

[0002]

2. Description of the Related Art To bond long sheets together,
Depending on the material of the sheet, the surface may be melted and adhered, but in general, an adhesive is used and a laminating method using a laminating machine is used. There are various sheets to be adhered, but usually paper, cloth, non-woven fabric,
A relatively thin, flexible, usually called film or sheet, such as a plastic film or a metal foil, is a target of the laminating method. In this specification, for the sake of simplicity, the term "sheet" is used to mean that these films and sheets are gathered together.

The methods of laminating sheets are roughly classified into
There are (1) wet laminating method and (2) dry laminating method. Adhesives are used in these. In addition to this, (3) hot melt laminating method using wax and (4) using polyolefin resin
There is also an extrusion lamination method.

In the wet laminating method (1) and the dry laminating method (2) using an adhesive, an adhesive selected according to the material of the sheet to be adhered is used. As a result of lamination, including securing the adhesiveness of the obtained product at high temperature or low temperature,
Thermosetting adhesives are used as adhesives due to the increasing demand for adhesiveness.

However, thermosetting adhesives are used for lamination when the amount of sheets to be laminated is large and it takes a long time to complete the lamination because crosslinking progresses even during lamination. The viscosity of the solution increases, making it difficult to keep the applied amount constant, and after the lamination is completed or when the lamination is interrupted, the adhesive solution remains cross-linked in the laminating machine and is difficult to remove. There may be drawbacks.

Therefore, the reactivity between the main agent having a reaction site and the cross-linking agent (also referred to as a curing agent), which constitutes the thermosetting adhesive and is capable of reacting with the main agent to crosslink, is lowered, By blocking the reaction so that the thermosetting adhesive supplied to the laminating machine is prevented from cross-linking,
When heated and pressed between a pair of nip rollers on the laminating machine, a part of the crosslinking is carried out to cure it to such an extent that it does not hinder transportation and storage, and then at room temperature to 50
The curing is completed by advancing cross-linking by so-called curing, which is left for 1 to several days in an environment set to around 0 °.

When carrying out the curing as described above, it is necessary to prepare an environment in which the temperature can be controlled, energy for heating is required, and further processing or shipping as a product cannot be performed during the curing period. Etc., restrictions on handling cannot be avoided,
In addition, there is a quality control bottleneck that the final product performance cannot be measured until after the curing period.

Attempts have been made to eliminate the above-mentioned drawbacks of the laminating method using a thermosetting adhesive by using an electron beam curing adhesive. In the electron beam curable adhesive, crosslinking is temporarily promoted by irradiation with electron beams, and the degree of crosslinking can be adjusted by the irradiation dose. However, the electron beam irradiation device used must be shielded to ensure safety during operation, which causes the laminating machine to grow in size, and it is necessary to sufficiently crosslink the electron beam curable adhesive. Sheet, especially the sheet made of plastic material, tends to deteriorate and the mechanical strength tends to decrease.If this is avoided, the adhesive will be insufficiently crosslinked and Only adhesive strength can be obtained, and unreacted monomers and oligomers remain to cause problems such as odors not being released.

Therefore, as disclosed in JP-A-5-124111, as the adhesive, an electron beam curable adhesive, more preferably a thermosetting-electron beam curing dual cure type adhesive, is used. Attempts have been made to overcome the above-mentioned drawbacks in the conventional laminating method using an electron beam curable adhesive by applying ultrasonic vibration in addition to electron beam irradiation. However, even with the technique described here, the point of increasing the size of the laminating machine is not solved, and the use of ultrasonic vibration is not limited to the case where the adhesive used is an electron beam curable adhesive, more preferably a thermosetting adhesive. -It is limited to electron beam curing dual cure adhesives, and there is no idea to use ultrasonic vibration for a laminating method using ordinary thermosetting adhesives.

Japanese Patent Laid-Open No. 5-124112 discloses a moisture-curable urethane liquid adhesive or a moisture-curable urethane hot-melt adhesive when a surface plate is attached to the top and bottom of a core material of a honeycomb core. It is described that water is applied to the urethane adhesive to cure it by utilizing the isocyanate component held by the urethane adhesive itself, and water or amine is encapsulated, and pressure bonding is performed by ultrasonic heating bonding. By this method, heating and pressure clamping (temporary fixing)
It is described that the time required for can be reduced.

However, the above-mentioned Japanese Patent Laid-Open No. 5-124112.
Conventionally, the "clamping" described in the publication is carried out for 30 seconds or longer. Also in the embodiment of this publication, 12.5 seconds are used in Example 2 in which ultrasonic heating is used together, and about 17 to 20 seconds in Example 4. Which is very advantageous in terms of improving the adhesive strength,
No acceleration of curing of the thermosetting adhesive in the method of laminating sheets as in the present invention is shown.

[0012]

In the present invention, a thermosetting adhesive is used instead of the electron beam curable adhesive, but conventionally, a room where the temperature can be adjusted is required, and heating for heating is required. It is an object of the present invention to improve the drawbacks such as energy consumption, restrictions during the curing period, and inconvenience that the final product performance cannot be measured until after the curing period elapses.

[0013]

In the present invention, an adhesive which is not electron beam curable, preferably a thermosetting adhesive, is used,
After being applied to at least one of the sheets, the adherends are overlapped with each other, and pressure or pressure and heat are applied for adhesion, and then ultrasonic waves are applied to the adhesion portion to promote adhesion, I was able to solve the problem.

According to a first aspect of the present invention, when laminating long first and second sheets while continuously running them, at least one of the surfaces of the first and second sheets on the side of laminating. After applying a thermosetting adhesive to one side to form an adhesive layer, the first and second sheets are superposed to form a superposed body, and the superposed body is applied while passing between opposing rollers. By adhering by pressure and heating to form a laminated body in which the first and second sheets are laminated via the adhesive bonding, immediately after that, by applying ultrasonic waves to the laminated body,
The present invention relates to a laminating method characterized by increasing the adhesive force by promoting crosslinking of the adhesive layer in the laminate. A second invention relates to the laminating method according to the first invention, wherein the adhesive is a polyurethane adhesive. Third
The present invention relates to the laminating method according to the second invention, wherein the adhesive is a two-component curing type polyurethane adhesive. According to a fourth invention, in any one of the first to third inventions, the first and second inventions are provided.
Each of the above-mentioned sheets is selected from the group consisting of paper, cloth, non-woven fabric, plastic film, and metal foil.
A fifth invention relates to the laminating method according to the fourth invention, wherein one of the first and second sheets is a plastic film and the other is a metal foil. A sixth invention relates to the laminating method according to any one of the first to fifth inventions, which further comprises curing the laminated body after the ultrasonic wave is applied. .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The laminating method of the present invention will be described with reference to the drawings. However, since a considerable part of the laminating method of the present invention is common to the conventional laminating method, the essential points of the conventional laminating method will be described first. Then, the procedure for explaining the difference from the conventional laminating method will be described.

FIG. 2A is a schematic view of a laminating machine 101A used in a conventional dry laminating method.
First, the first sheet 103 is supplied from the first sheet feeding device 102 on the left side of the laminating machine 101A, fed out in the direction of the arrow, and runs. Next, the roller 105 which the lower part is dipped in the pan 4 for accumulating the adhesive solution, and the adhesive solution whose amount is regulated by the doctor device 106 rotate between the rollers 105 and 107 facing each other.
When 03 travels and passes, it is applied to the lower surface of the first sheet 103. The first sheet 103 coated with the adhesive solution continues to travel to reach the drying zone 108 at the upper part of the laminating machine 101A, and is blown with air when traveling and passing through the drying zone 108 to bond. The solvent in the agent solution is evaporated and dried to form a dry adhesive layer.

First sheet 103 on which an adhesive layer is laminated
Is supplied from the second sheet feeding device 109 on the right side of the laminating machine 101A, is fed in the direction of the arrow, and is overlapped with the traveling second sheet 110 to form a superposed body, and the opposing rollers 111 and When the stacked body travels between 112 and passes, it is pressurized and heated to activate the dried adhesive layer, and the first sheet 10
2 and the second sheet 110 are adhered to each other, and a laminated body 113 of both sheets 102 and 110 adhered via an adhesive layer.
Is then run and hoisted by hoisting device 114 to the left of rollers 111 and 112.

The above series of steps are all performed on the same laminating machine, and the first sheet 103 and the second sheet 103
Each of the sheets 110 is supplied in a long length, and while being continuously run on the laminating machine, they are subjected to application of an adhesive solution, drying, superposition of sheets, and pressurization and heating. The above is the conventional dry laminating method.

FIG. 2B is a schematic view of a laminating machine 101B used in the conventional wet laminating method. First, the first leftmost laminating machine 101B
The first sheet 103 is supplied from the sheet feeding device 102 and is fed in the direction of the arrow to run. Next, the roller 105 is rotated by immersing the lower part in a pan 104 for storing the adhesive solution
And the lower surface of the first sheet 103 when the adhesive solution whose amount is regulated by the doctor device 106 passes through the rollers 105 and 107 opposed to the first sheet 103 by traveling the first sheet. Is painted on. A first sheet 103 coated with an adhesive solution and a laminating machine 1
The second sheet 110 fed from the second sheet feeding device 109 located substantially in the center of 01B and fed in the direction of the arrow is superposed to form a superposed body, and the rollers 111 and 112 facing each other are superposed. When the combined body travels and passes, the combined body is pressurized and heated, and the first sheet 102 and the second sheet 110 are bonded to each other via the adhesive layer to form the laminated body 113. In this case, the adhesive layer has not been dried yet and is active, so that heating may be omitted.

Subsequently, the laminated body 113 continues traveling to reach the drying zone 108 at the upper part of the laminating machine 101B, and when traveling through the drying zone 108, air is blown to the laminated body 113 in the adhesive solution. The solvent evaporates and dries, and then runs and is wound up by the winding device 114 on the right side of the laminating machine 101B.

The above series of steps are all carried out on the same laminating machine, and the first sheet 103 and the second sheet 103
Each of the sheets 110 of is supplied in a long length, and while they continuously run on the laminating machine, application of an adhesive solution, superposition of sheets, pressurization and heating,
Also get dried. When the sheet is permeable to the adhesive solution, a laminating machine without the drying zone 108 may be used and the drying step may be omitted. The above is the conventional wet laminating method.

The dry laminating method and the wet laminating method described above are premised on the use of a solvent-type adhesive obtained by diluting the adhesive with an organic solvent or the like, but the laminating method is not diluted with a solvent. There is also a laminating method using a solventless adhesive.
The laminating method using a solventless adhesive is
In terms of methodology, there is a wet laminating method that does not perform drying. From the viewpoint of the apparatus used, the apparatus used in the wet laminating method can be used by omitting the drying zone.

FIG. 1 is a diagram illustrating an outline of a laminating machine for carrying out the laminating method of the present invention.
(A) is a laminating machine 1 used in the dry laminating method
It is a figure which shows A, and FIG.1 (b) is a figure which shows the laminating machine 1B used for a wet laminating method. The laminating machine of FIG. 1 (a) corresponds to the laminating machine of FIG. 2 (a), and the laminating machine of FIG. 1 (b) corresponds to the laminating machine of FIG. 2 (b). Each part has a number obtained by subtracting 100 from the corresponding number in FIG.
It is attached as a symbol in FIG.

The laminating method of the present invention is the same as the laminating method described with reference to FIGS. 2 (a) and 2 (b).
Further, ultrasonic waves are added to the laminated body 13 composed of the first sheet 3, the adhesive layer, and the second sheet 10.

When performing the dry laminating method using the laminating machine 1A as illustrated in FIG. 1 (a),
Application of adhesive solution, drying, superposition of sheets,
Also, for the laminated body 13 that has been subjected to each process of pressurization and heating, it is placed at a position between the opposing rollers 11 and 12 used in the process of pressurizing and heating, and the winding device 14 that finally winds the product. An ultrasonic wave is applied by the installed ultrasonic device 15. By the action of this ultrasonic wave, crosslinking of the adhesive layer between the first sheet 3 and the second sheet 10 of the laminated body 13 is promoted, and the adhesive force is increased.

When performing a wet laminating method using a laminating machine 1B as shown in FIG. 1B, application of an adhesive solution, superposition of sheets, pressurization and heating, and Ultrasonic waves are applied to the laminated body 13 that has undergone the respective drying steps by the ultrasonic device 15 installed between the drying zone 8 and the winding device 14 that finally winds the product. Similar to the case of the dry laminating method described above, the action of this ultrasonic wave promotes the crosslinking of the adhesive layer between the first sheet 3 and the second sheet 10 of the laminate 13 to increase the adhesive force. To do.

The above is the addition of applying the ultrasonic wave to the dry laminating method and the wet laminating method which are premised on the use of the solvent type adhesive, but the application of the ultrasonic wave is further added. This can also be carried out by a laminating method using a solventless adhesive. In this case, ultrasonic waves are applied to the laminated body 13 that has been subjected to the steps of applying the adhesive solution, stacking the sheets, and applying pressure and heating, instead of using the drying zone, by using the installed ultrasonic device. Let

As an ultrasonic wave generation source when applying an ultrasonic wave, a Langevin type vibrator using a piezoelectric ceramic such as BaTiO ₃ , PZT or PbTiO ₃ , a piezoelectric polymer film or a piezoelectric thin film such as ZnO, A magnetoresistive vibrator can be used, and a plate-shaped or rod-shaped vibrator can be used. From the viewpoint of increasing the efficiency of the action of ultrasonic waves, it is preferable that ultrasonic waves be introduced into the closed box and the stack 13 be taken in and out via a slit provided on the wall surface of the box. Further, the rod-shaped one can apply an ultrasonic wave by moving the laminated body 13 close to the rod-shaped vibrator to run.

The frequency of the ultrasonic wave to be applied is 10
KHz to 50 KHz is preferable, but from the viewpoint of avoiding noise, 20 KHz or more outside the human audible range (which is said to be about 20 Hz to about 20 KHz) is more preferable, and
The time for applying ultrasonic waves is preferably about 10 seconds to 2 minutes.

The timing of applying the ultrasonic wave in each step of the laminating method is as described above, and the first sheet 3 and the second sheet 10 are laminated with the adhesive layer interposed therebetween. It is preferable to carry out after forming the body, and therefore, in the dry laminating method, it is preferable to carry out immediately after lamination. Further, in the wet laminating method, it is preferable to carry out after laminating and drying, but when drying is omitted, it may be carried out immediately after laminating.

When ultrasonic waves are applied to the laminate immediately after being heated and laminated as in the present invention, although the thin sheets are originally weak in adhesive strength due to heating, they are temporarily Since the laminated body is bonded to form a laminated body, and the strength of the entire body is increased, the laminated body can be improved in adhesive strength with almost no thermal damage due to ultrasonic waves.

The sheet which is the object of the laminating method of the present invention is a relatively thin and flexible film or sheet such as paper, cloth, non-woven fabric, plastic film or metal foil as described above. Is. Of these sheets, the same type or different types can be combined and laminated.

Application of the laminating method of the present invention is effective in unstretched polypropylene (CPP), polyethylene (PE), polyvinyl chloride (PVC), polyamides such as various nylons, polyvinyl alcohol (PV).
A), vinylidene chloride resin coated PP, polystyrene (PS), ethylene-vinyl alcohol copolymer resin (E
This is the case where various plastic films such as VOH), polycarbonate (PC), cellophane, or the like, or these plastic films are attached to a metal foil such as aluminum, tin, or copper.

In particular, when applied to the production of a laminated film for constituting a food film retort pouch made of a polyamide film or a non-stretched polypropylene film and aluminum or the like, heat resistance to withstand boiling is exhibited early after lamination. Therefore, it is particularly preferable.

Adhesives usable in the laminating method of the present invention include thermosetting urea resins, melamine resins, phenol resins, resorcinol resins, furan resins, epoxy resins, unsaturated polyester resins, polyurethane resins, polyimide resins. , Polyamide-imide resin,
Examples thereof include polybenzimidazole resin and polybenzothiazole resin.

Above all, when applied to a laminating method using a thermosetting polyurethane resin adhesive, especially a two-component curing type polyurethane resin adhesive, the effect of the present invention can be exhibited well. These polyurethane resin-based adhesives not only have high peel strength, but also have excellent heat resistance and cold resistance, and have good "wetting" with respect to sheets made of various materials. It is suitable for use in a laminating method that targets metal foil and the like. In addition, the two-component curing type polyurethane resin-based adhesive is usually designed so that the reactivity is moderate, and the usable time after blending the two-component is long and it takes a lot of sheets for a long time. Suitable for use when laminating. Usually, the method for laminating a film using a thermosetting polyurethane resin-based adhesive, especially a two-component curing type polyurethane resin-based adhesive is a dry laminating method.

Polyurethane resin adhesives are (1) polyester polyols or polyether polyols crosslinked with (2) isocyanate compounds having an isocyanate group. (1) and (2) are stored separately, and they are mixed at a predetermined mixing ratio at the time of use, and are applied as a solventless type by heating as needed or by diluting with a solvent. The solvent type is adjusted so that the viscosity is suitable for coating, and it is applied at room temperature.

In the above, examples of the isocyanate compound include toluylene diisocyanate, xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, triphenylmethane triisocyanate and the like.

According to the laminating method of the present invention, the so-called curing, which is carried out in the conventional laminating method for one day to several days under an environment of about 50 °, is basically unnecessary. However, it may be accompanied by curing after performing the laminating method of the present invention. The reason is that when ultrasonic waves are applied, the sheet is heated. Therefore, when the sheet is a plastic film, if the heating for forming a laminate and the heating by ultrasonic waves are extremely excessive, This is because softening, deformation, or deterioration may occur, or in the case of heat-shrinkable plastic film (so-called shrink film), it is necessary to avoid exceeding the shrinkage start temperature before shrinking processing, and apply ultrasonic waves. This is because the sheet is subjected to such an extent that the sheet is not softened, deformed, deteriorated, or shrunk, so that it may not always be a good idea to sufficiently improve the adhesive force.
However, even when accompanied by curing, the effect of improving the adhesive force by ultrasonic waves is slid and maintained as it is, so that there is an advantage that the planned adhesive force can be reached quickly.

[0040]

[Example] (Example 1) As a sheet to be laminated,
Aluminum foil with a thickness of 30 μm and 70 μm
m CPP film was prepared, and a polyurethane resin adhesive prepared by mixing a polyester polyol and an isocyanate compound in a predetermined compounding amount was applied so that the applied amount per unit area was 4.3 g / m ^2, and Dry laminating was performed under the conditions described above, and immediately after the dry laminating, ultrasonic waves having a frequency of 20 KHz were irradiated using an ultrasonic vibrator while changing the irradiation time to complete the lamination.

For evaluation, the sheet after laminating was
The peeling strength (unit: N / 15 mm, pulling speed: 50 mm / min, sample width: 15 mm) due to mold peeling was used, and for comparison, ultrasonic irradiation was performed only with normal dry lamination (“with treatment”). Was displayed, and the number of seconds is the number of seconds of irradiation.), And those without ultrasonic irradiation (displayed as "no treatment") were also measured. After laminating, all the samples were kept at room temperature and the peel strength after a predetermined time was measured. The evaluation results are shown in "Table 1".

[0042]

[Table 1]

As shown in "Table 1", the peel strength tended to be higher in the case where the ultrasonic irradiation was performed immediately after the lamination. After lamination, the peel strength tends to increase with the passage of time, regardless of whether or not ultrasonic waves are applied, but the one that has been subjected to ultrasonic waves does not peel at any elapsed time. The intensity was high, and the movement was parallel with an almost constant difference (0.7 to 1.8) as compared with the case where the ultrasonic irradiation was not performed. The value of peel strength required as a product varies depending on the material of the sheet, the type of adhesive, and the application of the product, but as an example, the food is packaged, sealed and sold, and the purchaser boils the whole package. In the case of a retort packaging material that heats and eats food by heating, it is desirable that the peel strength is 7.0 N / m or more before the retort treatment, but the time required to reach this value is However, I was able to confirm that it was accelerated by 2 to 3 hours.

[0044]

According to the first aspect of the present invention, sheets are laminated according to a normal laminating method to form a laminated body,
Immediately after applying ultrasonic waves, it is possible to further improve the initial adhesive force, which is insufficient with heating in the normal laminating method.After the laminating method is completed, the peel strength is changed with time. Is improving,
It is possible to provide a laminating method capable of shortening the time required to reach a predetermined peel strength. According to the invention of claim 2, in addition to the effect of the invention of claim 1, in addition to the peeling strength, heat resistance, cold resistance, and a laminating method using an adhesive having good "wetting" to sheets of various materials. Can be provided. According to the invention of claim 3, in addition to the effect of the invention of claim 2, there is provided a laminating method suitable for laminating a large number of sheets over a long period of time after being compounded. be able to. According to the invention of claim 4, in addition to the effect of the invention of any one of claims 1 to 3, it is possible to provide a laminating method suitable for laminating sheets of practical materials. According to the invention of claim 5, in addition to the effect of the invention of claim 4, it has excellent air barrier properties, particularly oxygen barrier properties, and light barrier properties, and has high durability that can withstand the conditions of boiling and frozen storage. A laminating method suitable for obtaining a laminated product can be provided. According to the invention of claim 6, in addition to the effect of the invention of any one of claims 1 to 5, by further curing, peeling of the product obtained compared to curing after performing the conventional laminating method. It is possible to provide a laminating method capable of improving strength in a shorter time.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a laminating machine used in a laminating method of the present invention.

FIG. 2 is a diagram showing an example of a laminating machine used in a conventional laminating method.

[Explanation of symbols]

1 laminating machine 2 First paper feeder 3 first sheet 4 bread 5, 7, 11, 12 rollers 6 Doctor device 8 drying zones 9 Second paper feeder 10 Second sheet 13 laminate 14 hoisting device 15 Ultrasonic device

Claims (6)

[Claims] 1. When laminating long first and second sheets while continuously running them, thermosetting on at least one of the surfaces of the first and second sheets to be laminated. After applying a conductive adhesive to form an adhesive layer, the first and second sheets are superposed to form a superposed body, and the superposed body is pressed and heated while passing between opposed rollers. The first and second sheets are laminated by adhesive bonding to form a laminated body, and immediately after that, ultrasonic waves are applied to the laminated body to form a laminated body. A laminating method comprising increasing the adhesive force by promoting crosslinking of the adhesive layer. 2. The laminating method according to claim 1, wherein the adhesive is a polyurethane adhesive. 3. The laminating method according to claim 2, wherein the adhesive is a two-component curing type polyurethane adhesive. 4. Each of the first and second sheets comprises:
The laminating method according to claim 1, wherein the laminating method is selected from the group consisting of paper, cloth, non-woven fabric, plastic film, and metal foil. 5. The laminating method according to claim 4, wherein one of the first and second sheets is a plastic film and the other is a metal foil. 6. The laminating method according to claim 1, further comprising curing the laminate after applying the ultrasonic waves.