JPH04283283A - Free sealing tape - Google Patents

Abstract

PURPOSE:To provide a free sealing tape to be used as a flap of a bag made of various kinds of plastic film, paper, metallic foil, etc., and capable of sealing and unsealing the flap freely. CONSTITUTION:A free sealing tape formed by laminating a strongly adhesive layer 6 and a weakly adhesive layer 5 doubly on a base material 4. Its production is simple and easy and it does not produce wrinkles or the like in its applied section even when it is left to stand for a long period of time.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an openable tape that is used for the lids of bags made of various plastic films, papers, metal foils, etc., and allows the lids to be opened and closed freely. .

0002

[Prior Art] As shown in Fig. 1, the structure of a conventional resealable tape is such that adhesives of the same type are coated on both sides of a base film in different widths. This method utilizes the difference in adhesive strength due to the difference in the area of the adhesive layer. In practical use, the release paper is peeled off and one side of the double-sided adhesive tape is applied to the inside of the bag lid. When the lid is closed, it is sealed, and when the lid is opened, the smaller adhesive layer peels off.

[0003] The manufacturing method of such an openable tape will be explained in order: 1. First, an adhesive is applied to one side of the base film. 2. Next, the same adhesive is applied in streaks to the other side of the base material so that the width of the coated area and the uncoated area are in a ratio of 1:1 to 1:2. 3. On one side of the obtained double-sided pressure-sensitive adhesive sheet, the part on the streak-coated side where the pressure-sensitive adhesive is not coated is suitably slit to form a tape. 4. A release tape slit to a size 2 to 3 times the size of the double-sided tape slit in step 3 is laminated to obtain the desired openable tape. Another manufacturing method is to first bond double-sided adhesive tape and release paper, and then slit the tape.

0004

[Problems to be Solved by the Invention] However, the production of such conventional tearable tapes requires many steps as mentioned above, and in the three steps mentioned above, the width of the original double-sided adhesive sheet is usually large. Therefore, it is not possible to slit a few millimeters wide, which is the width of the double-sided adhesive tape actually used, in one go. Therefore, it is necessary to first slit the material once to a width of 250 to 300 mm, and then slit it to the desired width. In addition, if the material of the base film coated with adhesive on both sides is different from the material of the bag, if it is used or left for a long time, wrinkles etc. may occur due to the difference in the elongation rate of the material due to humidity and temperature, which is undesirable in terms of appearance. There are also problems such as not having one. Therefore, there is currently a need for a resealable tape that can be easily manufactured and that does not cause any problems in terms of appearance or physical properties even when used or left for a long period of time.

[0005]

[Means for Solving the Problems] Therefore, as a result of intensive research in order to solve the problems, the inventors of the present invention have developed a method in which the adhesive force is controlled by the difference in the area of the adhesive layer, and the application area is almost the same. At the same time, we developed a removable tape that takes advantage of the difference in the adhesive strength of the adhesive itself. That is, the present invention is "a resealable tape formed by laminating a strong adhesive layer and a weak adhesive layer on a base material."

The tearable tape of the present invention is characterized in that pressure-sensitive adhesives with different adhesive strengths are laminated on the same side of a base film, and the method for manufacturing such a tape is as follows: 2. Coat one adhesive on the surface of the release tape that will serve as the base material; Further, coat the other adhesive over the adhesive; 3. A tamper-proof tape as shown in FIG. 2 can be obtained by a simple process such as slitting the raw material. Therefore, when the resealable tape of the present invention is applied to the lid of a bag, only two layers of adhesive remain on the surface of the lid base material, and no base material (core) is present. , there are no appearance problems such as wrinkles as with conventional tapes.

The adhesive used in the present invention is not particularly limited to rubber adhesives, acrylic adhesives, silicone adhesives, vinyl adhesives, etc., and similar adhesives may be used as long as they have different adhesive strengths. They may be used together or in combination with different types of adhesives. However, in view of the adhesion of the interface between adhesives, it is generally preferable to use a combination of adhesives of the same type, and acrylic adhesives are more practical.

[0008] In addition to the above-mentioned combinations of different types of adhesives, methods for producing differences in the adhesive strength of the adhesives of the present invention include changing the types and amounts of polymeric components and additives in the same type of adhesives. The adhesive strength can be varied by changing the composition of the adhesive. The ratio of the adhesive force A of the weak adhesive of the present invention to the adhesive force B of the strong adhesive is preferably A/B≦0.9,
It is more preferable that A/B≦0.6. Adhesive strength to the same base film is JISZ 023.
7.

Among the adhesives used in the present invention, the most practical acrylic adhesive will be further explained. Generally, the factors that affect the adhesive strength of acrylic adhesives include the glass transition temperature (
Tg), average molecular weight, type and content ratio of functional group-containing monomers, etc., depending on the structure of the resin, and in addition to these, types of additives such as tackifiers and crosslinking agents added to the acrylic copolymer. and quantity.

Among these factors, the functional group-containing monomer is important in the acrylic copolymer as the main component, and among these, the type and amount of the carboxyl group-containing monomer and hydroxyl group-containing monomer must be appropriately selected and adjusted. is actually often practiced. It is known that the lower the content of the carboxyl group-containing monomer component and the hydroxyl group-containing monomer component, the more the adhesive strength tends to improve, and the higher the content, the lower the adhesive strength. Therefore, it is adjusted according to the desired adhesive strength. do it.

The constituent components of the acrylic copolymer used in such an acrylic adhesive include a soft main monomer component with a low glass transition temperature, a hard comonomer component with a high glass transition temperature, and, if necessary, a small amount of a functional group-containing monomer. Ingredients include. Examples of the main monomer component include acrylic acid alkyl esters in which the alkyl group has about 2 to 12 carbon atoms, methacrylic acid alkyl esters in which the alkyl group has about 4 to 12 carbon atoms, and the like. Methyl acid, methacrylic acid alkyl ester having an alkyl group of 1 to 3 carbon atoms, vinyl acetate, acrylonitrile, methacrylonitrile, styrene, etc., and the functional group-containing monomer component is typically a carboxyl group-containing monomer. Examples of carboxyl group-containing monomers include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and polycarboxylic acids such as maleic acid, fumaric acid, citraconic acid, glutaconic acid, and itaconic acid. , and their anhydrides.

As the hydroxyl group-containing monomer, 2
-Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-
Examples include hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and N-methylol acrylamide. Examples of functional group-containing monomer components other than those mentioned above include dimethylaminoethyl methacrylate, acrylamide, methacrylamide, methylolacrylamide, glycidyl methacrylate, allylglycidyl methacrylate, and the like.

The above-mentioned tackifiers include rosin, rosin ester, hydrogenated rosin ester, phenolic resin,
There are no particular limitations as long as they are used in conventional acrylic adhesives, such as aromatic modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins, etc. Moreover, as the crosslinking agent, crosslinking agents used in ordinary adhesives such as epoxy type, urea type, isocyanate type, metal chelate type, melamine type, and aziridine type can be used without any limitation.

Among these, isocyanate compounds are particularly preferred, and polyfunctional isocyanates are particularly preferred, such as trimethylolpropane adducts of tolylene diisocyanate, ethylene diisocyanate, 1,4-butane diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, 2, Practical examples include 6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and isophorone diisocyanate.

[0015] Other adhesives used in the present invention include phthalic acid esters, phosphoric acid esters, adipate esters, sebacic acid esters, ricinoleic esters, polyester type,
Plasticizers such as epoxy and chlorinated paraffin, animal and vegetable oils,
Oils and fats such as mineral oil and silicone oil, coloring agents such as titanium oxide, zinc white, and calcium carbonate, UV inhibitors such as benzophenone, salicylate, benzotriazole, and substituted acrylonitrile, arsenite, cuprous oxide, Inorganic compounds such as mercury oxide, organic mercury compounds, organic sulfur compounds,
Known additives such as anti-mold agents of organic compounds such as phenolic compounds and organic copper compounds, silicone emulsions, antifoaming agents such as alcohols, thickeners such as polyvinyl alcohol, sodium polyacrylate, carboxymethylcellulose, and methylcellulose. can be added as desired without departing from the conditions of the present invention.

There are no particular restrictions on the release tape that is the base material on which the adhesive of the present invention is applied, and paper, polyvinyl chloride,
Any material may be used, such as a synthetic resin film or sheet such as polyester, polycarbonate, or polyolefin, or metal foil such as aluminum, tin, iron, etc., and the coated surface may be subjected to mold release treatment if necessary.

[0017] There are no particular restrictions on the target substrate for which the tearable tape of the present invention is used, and examples thereof include various plastics such as polyethylene, polypropylene, polyester (polyethylene terephthalate), vinylon, and polyvinyl chloride, or paper, cloth, and metal. Examples include foils and composite molded products made from these materials. The shape of these target substrates may be arbitrary, such as a bag, a container, a film, or a sheet.

[0018]

[Function] The releasable tape of the present invention is made by simply coating two adhesive layers with different adhesive strengths on a releasable base material, and is easier to manufacture than conventional tapes.

[0009]

[Production of weak adhesive]

n-butyl acrylate 90
．． 55% by weight vinyl acetate
5% by weight acrylic acid
A toluene solution of a polymer having a copolymer composition of 4% by weight of 2-hydroxyethyl methacrylate and 0.45% by weight (40% by weight, 5400 cps/2
Trimethylolpropane (1 mol) of tolylene diisocyanate (3 mol) as a crosslinking agent per 100 parts by weight (5°C)
1.5 parts by weight of a 75% by weight solution of the adduct in ethyl acetate was added. The adhesive strength was 460 g/25 mm.

[Production of strong adhesive] n-butyl acrylate
46% by weight 2-ethylhexyl acrylate
46% by weight vinyl acetate

5% by weight acrylic acid
A toluene solution of a polymer having a copolymer composition of 2.9% by weight of 2-hydroxyethyl methacrylate and 0.1% by weight (40% by weight, 75% by weight)
20 parts by weight of hydrogenated rosin as a tackifier, 4 parts by weight of xylene resin, and an adduct of trimethylolpropane (1 mol) of tolylene diisocyanate (3 mol) as a crosslinking agent. 75% by weight
Two parts by weight of ethyl acetate solution was added. Adhesive strength is 1280g
/25mm.

[Manufacture and use of tearable tape] The following experiment was conducted using the above-mentioned weak adhesive and strong adhesive (adhesive strength ratio: 0.36). A high-density polyethylene film having a width of 500 mm and a thickness of 30 μm was prepared as a release tape by an inflation method. A coating liquid with a weak adhesive was used on the release tape to form a dry film with a width of 5 mm and a thickness of 25 μm.
30 strips of a weak adhesive layer were transfer-coated in a direction parallel to the winding direction, leaving an interval of 10 mm so that the length was 10 mm.

[0022] Next, a strong adhesive coating solution was applied as a dry film on the formed weak adhesive layer in a layered manner so as to have a width of 5 mm and a thickness of 25 μm. The part of the release tape between the adhesive layers of the original fabric manufactured as described above was
A slit was processed into 0 pieces to obtain the intended tearable tape. When this resealable tape was laminated onto a vinylon bag, it was confirmed that the process was carried out smoothly. Further, after leaving the tape for one month, it was visually confirmed that no wrinkles were formed in the used area of the tape.

Example 2 Except for changing the copolymer composition of the weak adhesive and strong adhesive and the types and amounts of the tackifier and crosslinking agent to those shown below (adhesive strength ratio: 0.51) in Example 1. When an experiment was conducted in the same manner as in the same example, it was confirmed that the lamination process could be performed smoothly and no wrinkles were generated.

[Weak adhesive] Copolymer composition n-butyl acrylate 75% by weight ethyl acrylate
20% by weight acrylic acid
4.8% by weight 2-hydroxyethyl methacrylate 0.
2% by weight crosslinker Same as Example 1. The adhesive strength was 400g/25mm.

[Strong adhesive] Copolymer composition n-butyl acrylate 45% by weight isobutyl acrylate
11% by weight 2-ethylhexyl acrylate 35% by weight methyl methacrylate 5% by weight acrylic acid
3.8% by weight 2-hydroxyethyl methacrylate 0.2% by weight Tackifier Hydrogenated rosin 20
Part by weight Terpene phenol 5
Adhesive strength of 2 parts by weight of adduct of trimethylolpropane (1 mol) to crosslinking agent tolylene diisocyanate (3 mol) was 790 g/25 mm.

Comparative Example 1 Same as Example 1 except that the copolymer composition of the weak adhesive and strong adhesive and the added amounts of the tackifier and crosslinking agent were changed to the following (adhesive strength ratio 0.95). An experiment was conducted in the same manner as in Example 1, and lamination was carried out in the same manner as in the same example, but when the vinylon bag was opened, the adhesive layer separated and remained on both sides of the bag.

[Weak adhesive] Copolymer composition n-butyl acrylate 75% by weight methyl acrylate
20% by weight acrylic acid
4.9% by weight 2-hydroxyethyl methacrylate 0.
Adhesive strength of 1.0 parts by weight of trimethylolpropane (1 mol) adduct of 1% by weight crosslinking agent tolylene diisocyanate (3 mol) was 520 g/25 mm.

[Strong adhesive] Copolymer composition n-butyl acrylate 75% by weight methyl acrylate
20% by weight acrylic acid
4.8% by weight 2-hydroxyethyl methacrylate 0.
2% by weight Tackifier Hydrogenated rosin 10 parts by weight Crosslinking agent 2.0 parts by weight Trimethylolpropane (1 mol) adduct of tolylene diisocyanate (3 mol) Adhesive strength was 550 g/25 mm.

Comparative Example 2 The strong adhesive of Example 1 was used in the same manner as before, with a thickness of 0.02 mm and a width of 5 mm.
A double-sided adhesive tape is manufactured by providing a 25 μm thick adhesive layer as a dry film on the entire surface of one side of a 25 mm thick polyethylene phthalate tape, and a 25 μm thick adhesive layer with a width of 25 mm in the center of the other side. Created. When such an openable tape was used to process a vinylon bag in the same manner as in Examples 1 and 2, if it was left indoors for one month after use, the area where the tape was used became wrinkled and adhered to the bag base material. There were some areas that were not covered.

[0030]

[Effects of the Invention] The releasable tape of the present invention is made by simply coating two adhesive layers with different adhesive strengths on a base material with releasable properties, and is easier to manufacture and easier to use than conventional tapes. It is extremely useful industrially, as the bag does not wrinkle even if it is left for a long period of time.

[0031]

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the structure of a conventional tearable tape.

FIG. 2 is a cross-sectional view of the structure of the tearable tape of the present invention.

[Explanation of symbols]

1. mold release tape 2. adhesive layer 3. base film 4. Base tape with releasability 5. Weak adhesive (or strong adhesive) layer 6. Strong adhesive (or weak adhesive) layer

Claims (2)

[Claims] 1. A resealable tape comprising a base material and a double layer of a strong adhesive layer and a weak adhesive layer. 2. The tearable tape according to claim 1, wherein the adhesive force A of the weak adhesive and the adhesive force B of the strong adhesive to the same base material are A/B≦0.9.