JP5579464B2 - Adhesive for polyvinyl alcohol polymer film - Google Patents

Description

  The present invention relates to an adhesive for polyvinyl alcohol polymer films. More specifically, the present invention relates to an adhesive capable of firmly bonding polyvinyl alcohol polymer films to each other in a short time.

  Conventionally, when manufacturing a bag using a polyvinyl alcohol [hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”] polymer film, or in the production of a polarizing film, the length wound in a roll shape. PVA polymer films may be bonded together when switching the roll of PVA polymer film used for stretching to another roll when continuously stretching the PVA polymer film of the scale, For such bonding, thermocompression bonding or glue bonding has been employed. However, in thermocompression bonding, it is necessary to adjust an appropriate temperature depending on the moisture content of the film to be bonded and the kind and amount of the plasticizer to be contained, which is troublesome, and the film is discolored or deformed. There was a case. In glue bonding, a glue such as an aqueous solution of PVA polymer is usually used. However, when bonding PVA polymer films having a relatively high degree of saponification, a sufficient adhesion effect can be obtained. In addition to the absence, a complicated drying process may be required.

  As a method of adhering a highly saponified PVA polymer film, a method of adhering using a mixture of PVA and glycerin or ethylene glycol is known (see Patent Document 1). However, even in this method, complicated thermocompression treatment is required for adhesion.

JP-A-3-39381

  The object of the present invention is to provide an adhesive for bonding PVA polymer films that can firmly bond PVA polymer films to each other in a short time without complicated thermocompression bonding and drying treatment, Bonding method between PVA polymer films using an adhesive, manufacturing method of an adhesive bonded with PVA polymer films using the adhesive, and PVA polymer films manufactured by the manufacturing method are strong It is in providing the adhesive body adhere | attached on.

  The present inventors have intensively studied to achieve the above object. As a result, by using a lithium compound as a component constituting the adhesive, the PVA polymer films are firmly bonded to each other in a very short time by a simple operation without complicated thermocompression bonding and drying treatment. The PVA polymer film obtained by using the adhesive has a high water resistance without being peeled on the adhesive surface even when immersed in water. It has been found that the adhesive is extremely useful as an adhesive for bonding films for stretching that are stretched in water. The present inventors have further studied based on these findings and completed the present invention.

That is, the present invention
[1] an adhesive for bonding the PVA polymer films together, seen containing a lithium compound, the lithium compound are dissolved in a solvent, the solvent is a mixture of water and methanol, and water An adhesive in which the mass ratio of methanol is water: methanol = 50: 50 to 75:25 ;
[2] The adhesive according to [1], wherein the lithium compound is lithium chloride,
[3] The adhesive according to [1] or [2], containing 10 to 28 % by mass of the lithium compound ,
[4 ] The adhesive according to any one of [1] to [ 3 ], wherein the PVA polymer film is a film for stretching.
[ 5 ] A step of applying any one of the adhesives of [1] to [ 4 ] to at least one adhesive surface of the PVA polymer film and then bonding the adhesive to the other adhesive surface of the PVA polymer film. , A method for bonding PVA polymer films,
[ 6 ] A method for producing an adhesive body in which PVA polymer films are bonded to each other, wherein any one of the above [1] to [ 4 ] is applied to at least one adhesive surface of the PVA polymer film. After, the manufacturing method which has the process of bonding with the other adhesive surface of a PVA-type polymer film,
[ 7 ] An adhesive produced by the production method of [ 6 ] above,
About.

  The adhesive for adhering the PVA polymer films of the present invention can firmly adhere the PVA polymer films to each other in a short time without complicated thermocompression bonding and drying treatment. Moreover, the adhesive body of this invention is excellent also in water resistance while PVA polymer film has adhere | attached firmly.

The present invention is described in detail below.
The adhesive of the present invention is an adhesive for adhering polyvinyl alcohol polymer films. And the said adhesive agent contains a lithium compound.
Any lithium compound used in the present invention can be used as long as the effects of the present invention are not impaired. Among these, lithium chloride is particularly preferable in terms of adhesiveness.

  The content of the lithium compound in the adhesive of the present invention is preferably in the range of 5 to 30% by mass, more preferably in the range of 10 to 28% by mass, and in the range of 15 to 25% by mass. More preferably it is. Adhesive force can be further improved when the content rate of a lithium compound exists in the said range.

  In the adhesive of the present invention, it is preferable that at least a part, preferably all, of the lithium compound is dissolved in a solvent. As a result, an adhesive with improved adhesive strength can be obtained. Examples of the solvent include water; monoalcohols such as methanol and ethanol; glycols such as glycerin and ethylene glycol. These solvents may be used alone or in combination of two or more. Among these solvents, a mixture of water and alcohol is preferable, a mixture of water and monoalcohol is more preferable, and a mixture of water and monoalcohol is more preferable because lithium compounds can be prevented from precipitating after the adhesive is applied and the adhesive force is reduced. A mixture of water and methanol is particularly preferred because it can increase the permeability to the combined film and the adhesion rate. When the solvent is a mixture of water and methanol, the mass ratio is preferably in the range of water: methanol = 40: 60 to 80:20, and more preferably in the range of 50:50 to 75:25. preferable.

  Although the adhesive agent of this invention may be comprised only from the lithium compound and the solvent, as needed, it may further contain other components other than a lithium compound and a solvent. Examples of such other components include various additives such as a dispersant, a filler, and a reaction accelerator. The content of these other components in the adhesive of the present invention is preferably 50% by mass or less, more preferably 20% by mass or less, and further preferably 5% by mass or less.

  The adhesive of the present invention is used to bond PVA polymer films to each other. Examples of the PVA polymer constituting the PVA polymer film to be adhered include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, Those obtained by saponifying a polyvinyl ester polymer obtained by polymerizing one or more of vinyl esters such as vinyl benzoate and isopropenyl acetate can be used. What is obtained by saponifying the obtained polyvinyl ester polymer is preferable.

  The above-mentioned polyvinyl ester polymer is preferably obtained using only one or two or more kinds of vinyl esters as a monomer, and obtained using only one kind of vinyl ester as a monomer. Is more preferable, but may be a copolymer of one or more vinyl esters and other monomers copolymerizable therewith, as long as the effects of the present invention are not impaired. .

  Examples of other monomers copolymerizable with the vinyl ester include, for example, α-olefins having 2 to 30 carbon atoms such as ethylene, propylene, 1-butene and isobutene; (meth) acrylic acid or a salt thereof; (Meth) methyl acrylate, (meth) ethyl acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, ( (Meth) acrylic acid esters such as t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate; (meth) acrylamide, N-methyl ( (Meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acryl (Meth) acrylamide derivatives such as amide, (meth) acrylamide propanesulfonic acid or salts thereof, (meth) acrylamidepropyldimethylamine or salts thereof, N-methylol (meth) acrylamide or derivatives thereof; N-vinylformamide, N-vinyl N-vinylamides such as acetamide and N-vinylpyrrolidone; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, etc. Vinyl ether; vinyl cyanide such as (meth) acrylonitrile; halogenated vinyl such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride; vinegar Allyl compounds such as allyl acid and allyl chloride; maleic acid or salts thereof, esters or acid anhydrides; itaconic acid or salts thereof, esters or acid anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; unsaturated sulfonic acids or salts thereof And so on. Said polyvinyl ester-type polymer can have a structural unit derived from 1 type, or 2 or more types of an above described other monomer.

  The proportion of structural units derived from the other monomers in the polyvinyl ester polymer is 15 mol% or less based on the number of moles of all structural units constituting the polyvinyl ester polymer. Preferably, it is 10 mol% or less, more preferably 5 mol% or less.

  Although there is no restriction | limiting in particular in the polymerization degree of the PVA type polymer which comprises a PVA type polymer film, Preferably it is 500 or more, More preferably, it is 1000 or more, More preferably, it is 1500 or more. The degree of polymerization of the PVA polymer is preferably 8000 or less because the production of the PVA polymer is easy. In addition, the polymerization degree of a PVA polymer as used in this specification means the average degree of polymerization measured according to description of JIS K 6726-1994.

  There is no particular limitation on the degree of saponification of the PVA polymer constituting the PVA polymer film, and it can be appropriately set according to the use of the PVA polymer film, preferably 80 to 100 mol%, More preferably, it is 95-100 mol%, More preferably, it is 98-100 mol%. In this specification, the saponification degree of the PVA polymer is the total of the structural units (typically vinyl ester units) of the PVA polymer that can be converted to vinyl alcohol units by saponification and vinyl alcohol units. The proportion (mol%) of the number of moles of the vinyl alcohol unit relative to the number of moles. The degree of saponification of the PVA polymer can be measured according to the description of JIS K 6726-1994.

  The PVA polymer film may be composed of only the above PVA polymer, but may further contain other components than the PVA polymer as necessary. Examples of such other components include water, plasticizers, surfactants, antioxidants, antifreezing agents, pH adjusting agents, masking agents, anti-coloring agents, and oil agents. The content of these other components in the PVA polymer film is preferably 50% by mass or less, more preferably 20% by mass or less, and further preferably 5% by mass or less.

  The adhesive of the present invention is applied to at least one adhesive surface (surface to be bonded) of the PVA polymer film, and then bonded to the other adhesive surface of the PVA polymer film, thereby bonding the PVA polymer film. Combined films can be bonded together. The PVA polymer film to be bonded may have the same configuration as each other, the type of PVA polymer constituting the PVA polymer film, the content of the PVA polymer, and the other components described above. Kinds and contents may be different from each other. In addition, the PVA polymer film to be bonded may be a separate film such as two roll-shaped long films, or when a bag is produced by folding one film. Thus, a single film may be used. In adhering the PVA polymer film, it may be performed by applying the adhesive of the present invention to both adhesive surfaces to be adhered, and then bonding them together. Since it can adhere | attach, after apply | coating the adhesive agent of this invention only to one adhesion surface of a PVA-type polymer film, it adhere | attaches by sticking the other adhesion surface on it. Although it does not specifically limit as a method of apply | coating the adhesive agent of this invention to a PVA-type polymer film, For example, the method using an air spray, a nozzle spray, a roll coater etc. is mentioned.

  The adhesive of the present invention can firmly bond PVA polymer films to each other in a short time without performing thermocompression bonding or drying treatment, but the PVA polymer films can be bonded to each other using the adhesive of the present invention. In bonding, heat treatment, pressure-bonding treatment, drying treatment or the like may be performed as necessary.

  The adhesive of the present invention can be used for any application as long as it is an application for adhering PVA polymer films. For example, in the manufacture of a bag composed of a PVA polymer film, the films are adhered to each other. It can be used for applications such as bonding films for stretching processing used in the production of polarizing films and retardation films. Among these, according to the adhesive of the present invention, the PVA polymer films are firmly bonded to each other, and an adhesive having excellent water resistance can be obtained. Even if the adhesive is stretched in water, the bonded portion is obtained. Therefore, the adhesive of the present invention is preferably used for the purpose of bonding a film for stretching.

  The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[Examples 1 to 7 and Comparative Example 1]
Lithium chloride, water and / or methanol were mixed in the proportions shown in Table 1, and stirred at room temperature (23 ° C.) for 5 minutes to prepare adhesives of Examples 1 to 7, respectively. Further, polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 99 mol% and water were mixed in the proportions shown in Table 1, and the mixture was heated to 95 ° C., stirred for 3 hours, and then cooled to room temperature (23 ° C.). An adhesive was prepared.

The adhesive was applied to one of two films made of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 99.9 mol%, and the other was quickly pasted thereon. And 45 degree after bonding, the 180 degree | times peeling test was implemented and the mode of the peeling part was observed. If the material (film) is destroyed and no peeling is observed on the bonding surface, “○” is indicated. In some cases, peeling is observed on the bonding surface of the film. When it was destroyed, it was evaluated as “Δ”, and when the material (film) was peeled off without being broken, it was evaluated as “x”.
Further, the same test was performed by changing the time from the pasting to the 180 degree peel test from 45 seconds to 60 seconds.

  Two samples having a width of 10 cm and a length of 7 cm were cut out from a film made of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 99.9 mol%. Next, the adhesive is applied to a portion 2 cm from the end in the length direction of one sample, and is quickly bonded to a portion 2 cm from the end in the length direction of the other sample, and the width 10 cm × length 12 cm ( Among them, a test piece having a bonding portion of 2 cm) was obtained. Then, 60 seconds after bonding, the test piece is immersed in water at 30 ° C. for 60 seconds, and then uniaxially at a speed of 0.1 m / min in the length direction until the test piece breaks while being immersed in water. Stretching was performed. When the test piece was broken at a portion other than the bonded portion, it was evaluated as “◯”, and when the test piece was broken at the bonded portion or peeled off at the bonded surface, it was evaluated as “x”.

  The above results are shown in Table 1.

  As is clear from the above results, in Examples 1 to 7 using an adhesive containing lithium chloride, a PVA polymer was obtained after only 60 seconds after bonding, although no thermocompression bonding or drying treatment was performed. An adhesive body in which the films were firmly bonded to each other was obtained. Moreover, even when the obtained bonded body was uniaxially stretched in water, it was excellent in water resistance without being broken at the bonded portion or peeled off at the bonded surface. On the other hand, in Comparative Example 1 using an adhesive that does not contain lithium chloride, it is difficult to bond the PVA polymer films to each other within 60 seconds after bonding, and the obtained adhesive (bonded) ) Was also inferior in water resistance.

  Since the adhesive of the present invention can firmly bond PVA polymer films to each other in a short time without complicated thermocompression bonding and drying treatment, the obtained adhesive is excellent in water resistance. By using an adhesive, the film of the roll to be finished and the film of the new roll can be easily changed in a short time when switching the roll of the PVA polymer film for stretching that is stretched in water during the production process. Can be bonded and can switch to the next roll without stopping continuous production.

Claims (7)

An adhesive for bonding the polyvinyl alcohol polymer film together, seen containing a lithium compound, the lithium compound are dissolved in a solvent, the solvent is a mixture of water and methanol, water and methanol The adhesive whose mass ratio is water: methanol = 50: 50-75: 25 .   The adhesive according to claim 1, wherein the lithium compound is lithium chloride. The adhesive according to claim 1 or 2, comprising 10 to 28 % by mass of the lithium compound . The adhesive according to any one of claims 1 to 3 , wherein the polyvinyl alcohol polymer film is a film for stretching. After applying the adhesive according to any one of claims 1 to 4 to at least one adhesive surface of the polyvinyl alcohol-based polymer film, the step of laminating the other adhesive surface of the polyvinyl alcohol-based polymer film, Adhesion method between polyvinyl alcohol polymer films. It is a manufacturing method of the adhesive body which polyvinyl alcohol polymer films adhered, Comprising: After apply | coating the adhesive of any one of Claims 1-4 to the at least one adhesive surface of a polyvinyl alcohol polymer film The manufacturing method which has the process of bonding together with the other adhesive surface of a polyvinyl alcohol-type polymer film. The adhesive body manufactured by the manufacturing method of Claim 6 .