JP2897015B2 - Manufacturing method of laminate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a laminate using an adhesive made of a UV-curable resin.

[Prior Art] An existing plastic film is stuck on the surface of a printed material for the purpose of protecting the printed surface and aesthetic finishing, or a film or sheet having a different property is provided for the purpose of having various performances together. There are many laminated sheets attached with an adhesive.

In the process of obtaining these laminates, an adhesive made of a curable resin is frequently used. For example, an adhesive made of a two-component curable resin made of an isocyanate-cured polyether polyurethane resin, or a photopolymerized resin made of an ultraviolet-curable resin. An adhesive or the like made of a polymerizable monomer component is used as an initiator and a diluent.

[Problems to be Solved by the Invention] By the way, the bonding using the adhesive of the two-component curable resin is carried out by closely contacting and pressing the adherend against the surface to which the adhesive is to be applied, and then applying the adhesive to the surface. A curing step of aging for about 10 days must be performed, and the production efficiency of the laminate is extremely poor. For this reason, it is not possible to cope with a quick delivery date, but equipment for an aging step is required, which is uneconomical.

Further, when using an adhesive made of a UV-curable resin and a photopolymerization initiator having a monomer component as a diluent, it is inevitable that low-molecular-weight substances due to the monomer component as the diluent remain, particularly There is a problem of hygiene of a packaging material composed of a laminated sheet often used for packaging snacks and the like.

For this reason, as an adhesive of an ultraviolet-curable resin without the problem of residual low-molecular-weight products due to the above-mentioned monomer components, the solid component concentration of a solvent solution containing an ultraviolet-curable resin and a photopolymerization initiator is determined. High adhesives have been proposed.

However, even with a laminated sheet made of this adhesive, there is a problem of odor due to decomposed products of a photopolymerization initiator generated by irradiation of ultraviolet rays, for example, cyclohexane, benzaldehyde, methyl benzoate, and the like. Is not suitable, and the detrimental product of the photopolymerization initiator and unreacted photopolymerization initiator bleed out on the surface of the laminated sheet, e.g.,
There are problems such as migration to the contents in the package formed by the laminated sheet, and reduction in the heat seal strength of the sealant film in the laminated sheet in which the sealant film is laminated.

On the other hand, the present invention is a method for obtaining a laminate of a substrate and a film for a sealant, which does not require a long-term curing step by aging, and does not use a diluent based on a monomer component. There is no problem of residual low molecular weight substances due to the monomer components, and furthermore, the harmful effects of decomposition products of the photopolymerization initiator generated by irradiation with ultraviolet light,
By using an ultraviolet-curing adhesive that does not have the adverse effects of residual unreacted photopolymerization initiator, an efficient bonding process eliminates odors and hygiene problems caused by residual monomers, and manufactures laminates An object of the present invention is to provide a method for producing a laminate capable of obtaining a laminate in which a film for a sealant is adhered without a decrease in heat sealing performance as time passes.

[Means for Solving the Problems] The method for producing a laminate of the present invention comprises:
After applying an adhesive from a solvent solution containing a UV-curable resin and a photopolymerization initiator having an acryloyl group, the solvent in the adhesive applied to the substrate is evaporated, and then the adhesive is applied. A sealant film having heat welding performance is brought into close contact with the coated surface, and then the laminate is obtained by irradiating ultraviolet rays.

In the method for producing a laminate of the present invention having the above configuration, it is preferable to use a film having a UV transmittance of 250% to 400 nm of 20% or more as the sealant film.

Further, in the case of the method for producing a laminate of the present invention using a sealant film having a UV transmittance of 250 to 400 nm of 20% or more, the laminate is obtained by irradiating ultraviolet rays from the sealant film surface. Is preferable.

In the method for producing a laminate of the present invention having the above-described structure, examples of the ultraviolet-curable resin used as one component in the adhesive include epoxy (meth) acrylate, polyurethane (meth) acrylate, polyolefin glycol (meth) acrylate, Polyester (meth) acrylate or the like having a molecular weight of 300 to 6000, preferably 1000 to 3
000 oligomers having two or more polymerizable functional groups, specifically, one or a mixture of two or more oligomers having a (meth) acrylic double bond are preferred.

The epoxy (meth) acrylate includes a reaction product of an epoxy resin having a glycidyl group at a terminal and (meth) acrylic acid, for example, a bisphenol-A type epoxy acrylate, and a polyurethane (meth) acrylate.
Examples of the acrylate include a reaction product of a polyurethane resin having an isocyanate group at a terminal and a compound having a vinyl group and a hydroxyl group in a molecule such as 2-hydroxyethyl (meth) acrylate, and a polyolefin glycol (meth) acrylate. For example, di (meth) acrylic acid esters of polyethylene glycol and the like, and polyester (meth) acrylates include reaction products obtained by treating a polyester with phthalic anhydride and diethylene glycol with (meth) acrylic acid. used.

In addition, it goes without saying that the above-mentioned (meth) acryl-modified oligomers may be a mixture thereof.

The photopolymerization initiator contained in the adhesive is a photopolymerization initiator having an acryloyl group, for example, an acetophenone-based photopolymerization initiator having an acryloyl group introduced, a benzoin-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. Photopolymerization initiators, benzophenone-based photopolymerization initiators, specifically, 4- (2-acryloyl-oxyethoxy) -phenyl-2-hydroxy-2-propyl ketone, alkylated benzophenone ether, 2-acryloyl-benzophenone, 3-acryloyl-benzophenone, 4-acryloyl-benzophenone, 2-acryloyl-2-benzoylbenzoate, 3-acryloyl-2-benzoylbenzoate, 4-acryloyl-2-benzoylbenzoate, 3,3-dimethyl-2-acryloyl-4 -Methoxy-
Benzophenone, 3,3-dimethyl-4-acryloyl-4
-Methoxy-benzophenone, 3,3-dimethyl-5-acryloyl-4-methoxy-benzophenone and the like.

For the photopolymerization initiator, if necessary, for example, dimethylaminoethanol, triphenylphosphine,
Of course, a photosensitizer such as N, N-dimethylaniline or dimethylaminobenzoate can be used in combination.

As the solvent in the adhesive, for example, a single solvent such as ethyl acetate, toluene, methyl ethyl ketone, isopropyl alcohol, ethyl alcohol, methyl alcohol, and butyl alcohol, a mixed solvent, and a mixed solvent of the alcohols and water are used. In the case of a water-alcohol mixed solvent, water is added to 100 parts by weight of alcohol.
A mixed solvent of about 0 to 1000 parts by weight is suitable.

When an alcohol or a mixed solvent of water and alcohol is used as the solvent in the adhesive, the problem of the residual solvent can be solved simultaneously with the problem of the residual monomer.

The adhesive used in the production method of the laminate of the present invention is usually a photopolymerization initiator 0.2 per 100 parts by weight of the resin component.
A composition comprising about 10 to 10 parts by weight of a solvent and about 50 to 1000 parts by weight. For example, a coating method such as gravure coating, direct roll coating, reverse roll coating, or the like, produces 0.5 to 10 g with respect to the coated surface of the substrate. (Resin component) / m ²

In the method for producing a laminate of the present invention using the adhesive, as the base material, for example, a monolayer film such as a biaxially stretched polypropylene film, a biaxially stretched polyester film, a biaxially stretched polyamide film, or the like, In addition to the laminated film, a laminated film made of the above film and a metal foil or paper is suitable, and a base material to which design characteristics are imparted by printing or the like is used as necessary.

Examples of the sealant film adhered to the base material by the above-mentioned adhesive include a low-density polyethylene film, a medium-density polyethylene film, a high-density polyethylene film, an ethylene-vinyl acetate copolymer film, and ethylene-α · Polyolefin resin films such as olefin copolymer films and unstretched polypropylene films are used.

In the method for producing a laminate according to the present invention, after the above-mentioned adhesive is applied to the substrate surface, the solvent in the adhesive applied to the substrate surface is evaporated and removed by, for example, blowing hot air. Thereafter, a step of contacting and closely contacting the sealant film with the adhesive-coated surface and further irradiating ultraviolet rays is performed.
Irradiation with ultraviolet rays is usually performed by a high-pressure mercury lamp, a metal halide lamp, or the like.

In the ultraviolet irradiation treatment step, if the ultraviolet irradiation treatment speed is too fast, the irradiation dose is insufficient, the curing of the adhesive becomes insufficient, and if the irradiation treatment speed is too slow, the irradiation from the ultraviolet lamp. Heat and ultraviolet rays cause adverse effects on the sealant film, such as curling due to shrinkage of the film and deterioration in heat sealing performance. For this reason, generally, the output of the ultraviolet lamp: 80-1
It is preferable to irradiate ultraviolet rays at 20 w / cm and an irradiation speed of about 20 to 150 m / min.

[Example] Hereinafter, a specific configuration of the method for manufacturing a laminate of the present invention will be described with reference to examples.

Example 1 An adhesive consisting of the following adhesive composition [1] was coated on the printing surface of a substrate made of a biaxially stretched polyester film having a thickness of 25 μm on which printing by back printing was performed by a gravure roll coating method. 3 g (resin component) / m ² was applied, and then isopropyl alcohol as a solvent in the adhesive was evaporated and dried by blowing hot air of 80 ° C. on the coated surface of the adhesive for 2 seconds. A coating layer of a curable resin was formed. Adhesive composition [1] UV-curable resin [Polyether-based polyurethane diacrylate prepared by treating a reaction product of polyethylene glycol and tolylene diisocyanate with hydroxyethyl acrylate: average molecular weight 3000] 30 weights Part Photopolymerization initiator [4- (2-acryloyl-oxyethoxy) phenyl-2-hydroxy-2-propylketon] 1 part by weight isopropyl alcohol 69 parts by weight Next, coating of an adhesive with the ultraviolet curable resin A film for a sealant made of a low-density polypropylene film with a thickness of 40μ was brought into close contact with the surface of the work layer, brought into close contact with the sealant, and further pressed by a nip roll.
0cm, Nippon Battery Co., Ltd.], the distance to the film for sealant: 10cm, irradiation speed (line speed during irradiation: 10
UV irradiation at 0 m / min. Was performed from the surface of the film for sealant to obtain a laminated sheet [a] as a target product.

Comparative Example 1 Using the same substrate as that used in Example 1,
3 g (resin component) of an adhesive having the following composition [2] was applied to the printed surface of the substrate by a gravure roll coating method.
A laminated sheet [b] for comparison was obtained by the same steps as the corresponding steps of Example 1 except that the coating was performed at a ratio of / m ² . Adhesive composition [2] UV-curable resin [Polyurethane diacrylate based on polyether prepared by treating the reaction product of polyethylene glycol and tolylene diisocyanate with hydroxyethyl acrylate: average molecular weight 3000] 30 Parts by weight Photopolymerization initiator [1-hydroxycyclohexyl phenyl ketone (self-cleavable photopolymerization initiator)] 1 part by weight [benzyldimethyl ketal (self-cleavable photopolymerization initiator)] 1 part by weight Photosensitization Agent [p-dimethylaminobenzoic acid ethyl ester] 1 part by weight Isopropyl alcohol 69 parts by weight Comparative Example 2 Using the same base material as used in Example 1,
Isocyanate-curable polyether polyurethane resin using ethyl acetate as a solvent [Takelac A-969, Takenate A-5: Takeda Pharmaceutical Co., Ltd.]
3g by gravure roll coating method
(Resin component) / m ² was applied, and the same low-density polyethylene resin film as that used in Example 1 was brought into close contact with the coated surface and pressed with a nip roll.
The laminated sheet [c] for comparison was obtained by performing aging treatment at 40 ° C. for 7 days.

[Experiment 1] After cutting each of the laminated sheets obtained in Example 1 and Comparative Examples 1 and 2 into a narrow tape having a width of 15 mm, a gap between the base material and the sealant film made of a low-density polyethylene film was obtained. Adhesive strength, peeling angle 90 °, peeling speed 100mm / min.
It measured based on the peeling strength at the time of peeling by the above. The results are shown in Table 1.

[Experiment 2] The heat seal strength of each laminated sheet folded in Example 1 and Comparative Examples 1 and 2 was measured using a sealant film.

The heat seal strength of the laminated sheet is set such that the surfaces of the film for a sealant (low-density polyethylene film) in the laminated sheet are in contact with each other, and that
Fold it and use a sentinel heater to
After hot-press bonding under the heat sealing conditions of 0 ° C, 2 kg / cm ² , 1 second, the adhesive strength between the film surfaces for the sealant of the obtained laminate was measured at a peel angle of 90 ° and a peel speed of 300 mm / mi.
The measurement was performed based on the peel strength when peeled at n.

Further, each laminated sheet is left in a thermostat at 37 ° C., a part of the laminated sheet is taken out every one week, and the heat sealing strength is measured by the above-mentioned method. The change in heat seal strength was measured. The results are shown in Table 2.

The decrease in the heat seal strength with the lapse of the standing time of the laminated sheet [b] is caused by the decomposition of the photopolymerization initiator and the unreacted photopolymerization initiator contained in the adhesive over time. Therefore, it is caused by bleeding out to the sealant film surface.

[Experiment 3] Each of the laminated sheets obtained in Example 1 and Comparative Examples 1 and 2 was cut into 100 × 100 mm, and five sheets of each type were sealed in a 200 ml Erlenmeyer flask with a stopper. Then, after being left in an oven at 40 ° C. for 1 hour, the odor in each flask was evaluated organoleptically. The results are shown in Table 3.

[Function and Effect of the Invention] In the method for producing a laminate of the present invention, an adhesive comprising a solvent solution containing an ultraviolet-curable resin and a photopolymerization initiator having an acryloyl group is used. Therefore, there is no generation of decomposition products of the photopolymerization initiator in the adhesive due to the irradiation of ultraviolet rays.

Therefore, according to the method for producing a laminate of the present invention, a laminate of a substrate and a film for a sealant, the problem of odor due to the decomposition product of the photopolymerization initiator, and the decomposition of the photopolymerization initiator A laminate having no problem of bleeding out of the product or unreacted photopolymerization initiator or the like to the surface of the laminate and having no problems such as odor to the contents and transfer of the bleedout to the contents can be obtained.

Further, the adhesive used in the method for producing a laminate of the present invention has no problem of bleeding out to the surface of the laminate such as a decomposition product of a photopolymerization initiator or an unreacted photopolymerization initiator. According to the method for producing a laminate of the above, the adhesive strength is not inferior to the adhesive strength immediately after the production of the laminate obtained by the conventional adhesive using a two-component curable resin, A laminate of a substrate and a film for a sealant whose force does not decrease over time after the production of the laminate is obtained.

Further, since the adhesive used in the method for producing a laminate of the present invention is composed of a solvent solution of an ultraviolet-curable resin, the viscosity of the adhesive used for applying the adhesive during the production process of the laminate is used. According to the method for producing a laminate of the present invention, which is easy to adjust, a laminate of a good quality base material and a sealant film free from odor and hygiene problems due to residual monomers can be obtained.

Further, the adhesive used in the method for producing a laminate of the present invention does not need to undergo an aging step in the bonding step using the adhesive, for example, when using an adhesive using a two-component curable resin, According to the method for manufacturing a laminate of the present invention, the manufacturing process can be extremely shortened, so that it is possible to sufficiently cope with delivery within a short period of time, and to inspect the bonding state immediately after the bonding process. So you can
Production management is easy.

As described above, according to the method for producing a laminate of the present invention, an efficient adhesive step, no odor or hygiene problems due to residual monomers, and heat over time after production of the laminate A laminate is obtained in which a sealant film is adhered to a substrate without a decrease in sealing performance.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C09J 11/06 C09J 11/06 155/00 155/00 // B29L 7:00 (58) Fields surveyed (Int.Cl. ⁶ , DB name) C09J 9/00 C09J 11/06 C09J 4/02 C08F 299/00 C09J 155/00 B32B 31/28 B29C 65/14

Claims (3)

(57) [Claims] An adhesive comprising a solvent solution containing an ultraviolet-curable resin and a photopolymerization initiator having an acryloyl group is applied to the back surface of a substrate, and then the solvent in the applied adhesive is applied. A method for producing a laminated pair, which comprises evaporating, then closely contacting a sealant film having a heat-sealing performance on the coated surface of the adhesive, and further irradiating ultraviolet rays. 2. The method for producing a laminate according to claim 1, wherein a film for a sealant having a UV transmittance of 250 to 400 nm of 20% or more is used. 3. The method for producing a laminate according to claim 2, wherein ultraviolet rays are irradiated from the surface of the film for a sealant.