JP2966965B2 - Adhesive tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape.
To be more specific, in the case of waste recycling when products such as styrofoam to be bonded are no longer required, it is not necessary to peel off the adhered adhesive tape from the styrofoam product, and the waste can be recycled as it is. Related to adhesive tape.

[0002]

Styrofoam containers have advantages such as light weight, water resistance and heat insulation, and are therefore used for storing and transporting a wide variety of objects, including vegetables and marine products. ing. In using these containers, it is widely practiced to attach paper labels or film tapes for displaying contents, company names, and other information.

[0003] For example, in the case of a film tape, a tape on which necessary items such as contents and a company name are printed in advance is prepared, and cut into predetermined dimensions and attached to a styrofoam container. As such a tape, a tape based on a biaxially stretched polypropylene film (OPP film) or the like is often used because of its beautiful print finish. In addition, a tape is often stuck around the lid in order to ensure the hermeticity of the container.

[0004] In recent years, attention has been paid to the impact of waste disposal on the environment or the problem of resource protection, and the possibility of recycling waste materials without reusing them without reusing them is also considered. Are coming to think. In particular, with regard to a styrofoam container, it is particularly necessary to collect, re-melt and regenerate it, and various measures have been proposed. However, it has been pointed out that the presence of a paper label or an adhesive tape stuck on the surface of the container may hinder the reproduction in such a reproduction, and a solution to the problem has been seriously desired.

[0005] That is, in the state where the paper label is left attached, when the polystyrene product is melted to be regenerated, it is not melted and often remains as foreign matter, causing line clogging. In the case of an OPP film, since polypropylene has a low melting point, when polystyrene is dissolved, it is dissolved together with the polystyrene and is mixed in the regenerated pellets. If mixed in the regenerated pellets, in a subsequent foaming step, polystyrene and polypropylene have different expansion ratios, so that a uniform product surface cannot be obtained, which may cause unevenness of the product.

For this reason, when recycling polystyrene products, paper labels or OPPs are required when collected as waste.
The tape had to be removed. However, the work for peeling is a very laborious and time-consuming work, and it is difficult to completely remove it.

In order to solve such a problem, the present inventors have developed a pressure-sensitive adhesive tape which does not need to be peeled off after collecting the waste, that is, which can be subjected to a regenerating process even when the tape is stuck. We thought that it was necessary and conducted research to provide such an adhesive tape.

[0008] In order to obtain a tape which does not need to be peeled off after recovery, it is easily considered that it is appropriate to use a polystyrene resin as a base material. However, when such a polystyrene-based resin film is used as a tape base material, there are various problems in adhesive processing, and these problems have to be solved and cannot be simply achieved.

In general, when the pressure-sensitive adhesives are roughly classified into three types according to their forms, they can be classified into a solvent type, an emulsion type and a hot melt type. However, when processing an adhesive on a polystyrene resin film, there is a difficult problem to be solved regardless of which type of adhesive is used.

In the case of the first solvent-type pressure-sensitive adhesive, the polystyrene resin film also dissolves very well in a solvent such as toluene or ethyl acetate which is generally used as a solvent for the pressure-sensitive adhesive. Therefore, when making a tape using a solvent-type adhesive, apply it to another release paper once to avoid dissolution of the polystyrene resin film, and then attach it to the polystyrene resin film, A process of peeling the paper is required. In addition, although it is manufactured by such a complicated transfer method, the adhesiveness between the adhesive and the base film is poor, and furthermore, the use of process release paper results in a high cost, so that it is conventionally used. The price competitiveness with OPP film-based tape has been lost.

When an emulsion-type pressure-sensitive adhesive is used, the film substrate does not melt, but the adhesion and anchoring of the pressure-sensitive adhesive to a polystyrene film are poor. Therefore, even after pasting, if pasting fails and reattachment is attempted, it will be peeled off between the polystyrene film substrate and the pressure-sensitive adhesive layer, leaving the pressure-sensitive adhesive in the styrofoam box. It happens. Also, if the adhesive surface comes to something else during work, the adhesive will remain on the other party when it is peeled off.

In the case of a hot-melt type pressure-sensitive adhesive, the heat resistance of the polystyrene film is too low, so that the film shrinks due to heat during coating and cannot be processed.

As described above, the adhesive processing of a polystyrene-based film has its own drawbacks, and it has not been possible to produce a polystyrene-based film tape until now.

An object of the present invention is to manufacture and provide an adhesive tape free of such problems.

[0015]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention.

That is, the present invention provides an emulsion-type pressure-sensitive adhesive comprising a polystyrene resin film as a base material and an organic solvent having a solubility parameter of 8 to 10 in a range of 0.5 to 15% (weight). The present invention relates to an adhesive tape provided with an adhesive layer formed by coating and drying.

The polystyrene resin film used as the base material is not limited to a polystyrene film alone, but may be obtained by forming a film from a blend of polystyrene with another polymer or a copolymer of styrene and other monomers. Film is also included. Preferred copolymers include rubber-modified polystyrene, styrene-acrylonitrile copolymer, ABS (acrylonitrile-butadiene.
Styrene copolymer).

In order to form an adhesive layer, an organic solvent having a solubility parameter of 8 to 10 is mixed in the emulsion type adhesive.

The solubility parameter is expressed as the square root of the evaporation energy per ml of pure liquid. 1m of the substance
It means the energy difference between the gas state (interaction is almost 0) and the liquid state (weak interaction) per 1 and is a parameter related to intermolecular force. This solubility parameter is a parameter that is useful in producing a solvent by applying a solvent to plastics and dissolving and bonding the surface thereof, mixing an adhesive with a solvent, or mixing a mixture of two or more polymers. Yes, The Chemical Society of Japan, “Chemical Handbook Application,” Second Edition, pp. 742-5 (Showa 41, Maruzen Co., Ltd.)
Publication) shows the values of the solubility parameters of the various main solvents.

The use of an organic solvent having a solubility parameter of 8 to 10 is based on the fact that a solvent in this range is a good solvent capable of dissolving the polystyrene film well. -10 solvents must be used. Organic solvents outside this range do not give good results in practice.

As the solvent having a solubility parameter of 8 to 10, for example, toluene (8.9), xylene (8.8),
Aromatic hydrocarbons such as benzene (9.1), esters such as methyl acetate (9.6) and ethyl acetate (9.10), acetone (9.77), and methyl ethyl ketone (9.
Ketones such as 27), halogenated hydrocarbons such as chloroform (9.21) and carbon tetrachloride (8.65), and carbon disulfide (9.97).

As the emulsion-type pressure-sensitive adhesive, known ones such as an acrylate ester type, a styrene / butadiene type, an ethylene / vinyl acetate type, or a mixed type thereof can be used.

The acrylic ester-based pressure-sensitive adhesive uses, for example, an alkyl ester of acrylic acid and / or methacrylic acid as a main monomer component,
It can be obtained by emulsion polymerization of a copolymerizable α, β-unsaturated carboxylic acid and, if necessary, another copolymerizable monomer in the presence of an emulsifier and a radical polymerization initiator. Acrylic acid ester or methacrylic acid ester, which is the main monomer component (hereinafter the terms acrylic and methacrylic are collectively referred to as (meth) acrylic)
Examples thereof include n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, and at least one of these is used in an amount of 50 to 99% by weight, preferably 65 to 99% by weight based on the total amount of the monomers. It is valid. Monomers copolymerizable with these monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, vinyl acetate, vinyl propionate, vinyl chloride, styrene and acrylonitrile. Etc.,
At least one of these is used in an amount of 0 to 50% by weight, preferably 0 to 35% by weight, based on the total amount of the monomers. As the α, β-unsaturated carboxylic acid, acrylic acid, methacrylic acid,
Crotonic acid, itaconic acid, maleic acid, fumaric acid and the like, and at least one of them may be used in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight based on the total amount of the monomers. It is valid.

Further, if necessary, functional groups such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylamide and N-methylol (meth) acrylamide may be used. Can be used, a monomer having
It is effective to use at least one of these in an amount of 0 to 10% by weight, preferably 0 to 5% by weight, based on the total amount of the monomers.

The acrylate emulsion-type pressure-sensitive adhesive may contain a tackifier such as a rosin derivative, if necessary.

In addition to the acrylate-based emulsion-based adhesive, a styrene / butadiene-based emulsion-based adhesive or an ethylene-vinyl acetate-based emulsion-based adhesive can be used.

Since the adherend is Styrofoam, it is desirable that the adhesive strength of the PSA to the Styrofoam be 100 g / 25 mm or more. In addition, biting of the adherend is required. Since the ball tack according to the Dow method is 10 or more, and furthermore, it is stuck to a styrofoam box containing wet vegetables and marine products, it is necessary to have a certain degree of water resistance.

A solvent having a solubility parameter of 8 to 10 is added to such an emulsion-type pressure-sensitive adhesive. When mixing the solvent, it is necessary to add the solvent little by little while stirring the emulsion-type adhesive gently. If added rapidly, the emulsion may be broken and gelled. Although it depends on the amount of the solvent added, it is necessary to gradually add the solvent over at least 10 minutes or more, preferably 30 minutes or more.

The amount of the solvent added is from 0.5% to 15%, preferably from 0.5% to 10%, based on the total weight of the emulsion.
%. If the amount of the solvent is less than 0.5%, the anchoring property of the pressure-sensitive adhesive to the base film is not improved. Fifteen
%, Most of the emulsion-type pressure-sensitive adhesive gels and cannot be used. The optimum amount depends on the components of the emulsion, the solid content, the particle size, the type and concentration of the emulsifier, and the type of the added solvent, and thus needs to be determined each time. Such an organic solvent is insoluble in water, but it is possible to add an organic solvent in the above-mentioned range by solubilization by an emulsifier in the emulsion-type pressure-sensitive adhesive or absorption expansion of polymer particles.

In the present invention, the solubility parameter is 8
When forming an adhesive layer by applying and drying an emulsion-type adhesive containing 0.5 to 15% of an organic solvent of 0.5 to 10%, the substrate is separated from the surface of the substrate opposite to the adhesive layer in order to avoid adhesion of the tape surface. It is common to do the processing. In performing the release treatment, either a silicone-based or non-silicone-based release agent may be used. These peeling treatments are usually performed prior to the formation of the adhesive layer as in the case of the ordinary adhesive tape. However, it goes without saying that aromatic hydrocarbons and ketones, which are solvents for the polystyrene resin film, cannot be used. For example, a silicone release agent was dispersed and dissolved in an aliphatic hydrocarbon having 5 to 7 carbon atoms, and applied so as to 0.1g / m ² ~1.0g / m ² in dry, also of 90 ° C. or higher Release treatment is performed by drying at a temperature. As a coating method, a known method such as a gravure coater, a bar coater, and a roll coater is used.

In many cases, printing is performed when a polystyrene resin film is taped. In this case, the printing ink that can be used may be a printing ink for a polystyrene resin film which is generally commercially available. Of course, even in these printing inks, good solvents for polystyrene resin films such as aromatic hydrocarbons and ketones are not used, and poor solvents such as aliphatic hydrocarbons and alcohols are used. As the printing method, a known printing method such as a gravure printing method or a flexographic printing method is applied.

For example, a printing ink using a butyl diglycol acetate maleate resin or the like as a binder, an alcohol having 4 to 5 carbon atoms as a solvent, adjusting the viscosity, and then printing using a gravure printing machine. In addition,
The drying temperature at this time is 9 in consideration of the heat resistant temperature of the film.
The temperature is preferably set to 0 ° C. or lower.

<Examples> The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 On one side of a colorless and transparent polystyrene film having a thickness of 40 μm, a silicone-based release agent X62-
A normal hexane diluent (solid content: 2%) of 2416 (manufactured by Shin-Etsu Chemical Co., Ltd.) was coated with a gravure coater at a wet amount of 5 g / m ² and dried gently at a set temperature of 90 ° C.

Emulsion type adhesive BPW-5037
While gently stirring (manufactured by Toyo Ink Co., Ltd.), 3% by weight of toluene (solubility parameter: 8.9) was gradually added over about 30 minutes. After addition of the solvent, about 3 more
After gently stirring for 0 minutes, the mixture was filtered with a 120-mesh filter cloth.

[0036] The adhesive is subjected to a peeling treatment on the polystyrene film as described above.
It was coated with a roll coater to a dry amount of 35 g / m ² , dried, and wound up into a tape.

The adhesive strength, ball tack, holding power, and anchoring property of the adhesive to the base material of the pressure-sensitive adhesive tape thus manufactured are good as shown in Table 1. The results of the actual use test on the styrofoam box are also shown in Table 1. It was good.

Embodiment 2 FIG. A normal hexane diluent (solid content: 1%) of a non-silicone release agent, Piroyl 1010 (manufactured by YAS & Co., Ltd.) was wet onto a surface of a colorless and transparent polystyrene film having a thickness of 30 μm with a gravure coater at a wet weight of 10 g / m 2. ^Two coats were applied and dried slowly at a set temperature of 90 ° C.

On the opposite side of the film, a printing ink PW-6 for polystyrene film manufactured by Toyo Ink Manufacturing Co., Ltd.
06-12 (manufactured by Toyo Ink Mfg. Co., Ltd.) to provide a printing layer.

5.5 While stirring the emulsion-type adhesive TS-1219 (manufactured by Nippon Carbide Co., Ltd.) gently.
% By weight of methyl ethyl ketone (solubility parameter 9.27) was added slowly over about 30 minutes. After the addition was completed, the mixture was gently stirred for about 30 minutes, and then filtered with a 120-mesh filter cloth.

This pressure-sensitive adhesive was applied on a printed surface of a peeled and printed polystyrene film by a comma coater so as to have a dry amount of 40 g / m ² , dried and wound up into a tape.

The adhesive strength, ball tack, holding power, and anchoring property of the adhesive on the base material of the pressure-sensitive adhesive tape thus manufactured are good as shown in Table 1, and the results of the actual use test on the styrofoam box are also shown in Table 1. It was good.

Comparative Example 1 A tape was produced in the same manner as in Example 1 except that toluene was not added to the pressure-sensitive adhesive.

Comparative Example 2 A tape was produced in the same manner as in Example 2 except that toluene was not added to the pressure-sensitive adhesive.

The pressure-sensitive adhesive tapes of Comparative Examples 1 and 2 have the same adhesive strength, ball tack and holding power as those of Examples 1 and 2, respectively.
Although the results were almost the same as in the case of No. 2, the anchoring property of the adhesive to the substrate was remarkably poor and the workability was not good.

The adhesive strength, ball tack, holding power,
The anchoring property to the substrate was measured by the method shown in JISZ0237.

[0047]

According to the present invention, polystyrene which can be used particularly effectively and practically for styrofoam products, and which can be used for styrofoam product recycling as it is without the necessity of a peeling treatment before recycling. An adhesive tape using a base resin film as a base material could be provided.

The pressure-sensitive adhesive tape of the present invention has excellent adhesive properties as well as excellent anchoring force to the substrate and good workability. Low cost.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-131677 (JP, A) JP-A-49-124137 (JP, A) JP-A-48-102141 (JP, A) JP-A-51- 55330 (JP, A) JP-A-49-340 (JP, A) JP-A-51-80341 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09J 7/02

Claims (1)

(57) [Claims] An emulsion-type pressure-sensitive adhesive containing a polystyrene-based resin film as a base material and containing an organic solvent having a solubility parameter of 8 to 10 in a range of 0.5 to 15% (by weight) is applied and dried. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer formed by forming a pressure-sensitive adhesive layer.