JP2654574B2 - Method for producing polystyrene adhesive tape for box sealing made of expanded polystyrene - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polystyrene-based pressure-sensitive adhesive tape suitable for sealing a box made of expanded polystyrene.

[Related Art] In recent years, demand for boxes for storing and transporting fresh foods, fresh flowers, and the like has been increasing by utilizing the excellent heat insulating properties of expanded polystyrene.

The foam polystyrene box has a lid and a main body that are separated from each other, and an adhesive tape made of paper or polypropylene is used to fix the lid to the main body at the time of use.

[Problems to be Solved by the Invention] Recycling of expanded polystyrene is being studied because it is difficult to incinerate it.

However, if the adhesive tape made of paper or polypropylene used for sealing in the recycling process is mixed, the performance of polystyrene is affected as an impurity because paper and polypropylene are not compatible with polystyrene, and high quality recycled polystyrene is produced. There is a problem that it cannot be obtained. For this reason, in order to regenerate high-quality polystyrene, it is necessary to remove all the adhesive tapes used for sealing from the box made of expanded polystyrene, and the operation is complicated.

Further, since the adhesive tape made of polypropylene cannot be cut by hand, it is necessary to use scissors or a cutter for tape, and the working efficiency is poor.

On the other hand, if the adhesive tape is made of polystyrene, it is possible to obtain a good recycled polystyrene without removing the sealing adhesive tape.

However, polystyrene is inferior in solvent resistance, and there is a problem in that when a release agent layer is formed with a solvent-dispersed, curable silicone-based release agent, the base of polystyrene is cut off, making production impossible. There are also solventless and emulsion types, but the release agent layer formed with the solventless type has a slow peeling force and is curled when applying a polystyrene adhesive tape. This is not desirable as a release agent layer of the adhesive tape for sealing. Further, the emulsion type has a problem that productivity and other characteristics are inferior.

The present invention has been made in view of the above problems, and has made it possible to easily produce an adhesive tape for a polystyrene film having poor solvent resistance by using a curable silicone release agent of a solvent-mixed dispersion type. For example, it is possible to obtain an inexpensive sealing adhesive tape of the same material as that of a foamed polystyrene box such as a fish box and the like, so that good recycled polystyrene can be obtained from the expanded polystyrene box with the sealing adhesive tape attached. The purpose is to.

[Means and Actions for Solving the Problems] The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention as a means for achieving the above objects, and have a draw ratio in the transverse direction. the draw ratio of .lambda.T _D longitudinally when the λM _D, 2 ≦ _{λT D} <on one side of a polystyrene film is .lambda.M _D, with respect to the addition type silicone 100 parts by weight of a platinum based catalyst 3-7 parts by weight, A curable silicone-based mold release agent obtained by mixing and dispersing 6 to 14 parts by weight of an acetylene-based cure retarder in 500 to 1500 parts by weight of a solvent selected from hexane, heptane or a mixture thereof is 50 mg / m ^{2 to 2} g / m ² , dried within 3 seconds, and coated on the other surface of the polystyrene-based film with an emulsion-type acrylic adhesive having a concentration of 40 to 65% by weight of 5 g / m ² or more. Polystyrene for box sealing made of expanded polystyrene There is provided a method for producing a system pressure-sensitive adhesive tape.

 Hereinafter, the present invention will be described in detail.

The polystyrene-based film used in the present invention is a stretched film selected from polystyrene, a polystyrene copolymer such as a butadiene-styrene copolymer and a styrene-acrylonitrile copolymer, and a mixture of polystyrene and these copolymers. is there.

Further lateral stretching ratio of the stretched film the stretching ratio of .lambda.T _D longitudinally when the .lambda.M _D, it is necessary that 2 ≦ λT _{D <λM D.} Such a stretched film can improve the brittleness and tensile strength of the polystyrene-based film, and can improve the transverse tearability required for the tape, and can also somewhat improve the solvent resistance.

Next, the curable silicone release agent used in the present invention is obtained by mixing and dispersing an addition silicone, a platinum-based catalyst, and an acetylene-based cure retarder in a solvent.

In the present invention, a mixture obtained by mixing and dispersing the curable silicone release agent in a solvent selected from hexane, heptane or a mixture thereof is applied to a polystyrene film.

Conventionally, when applying a silicone-based release agent to a polystyrene-based film, a solvent in which the release agent is dispersed,
For example, it has been said that an adhesive tape of a polystyrene film cannot be produced because the polystyrene film is dissolved by xylene or toluene. In the present invention, a solvent having little effect on polystyrene is selected, and the solvent is dried immediately after application, thereby enabling production of a polystyrene-based pressure-sensitive adhesive tape. In addition, the use of a curable silicone-based release agent as the release agent layer ensures that the required release action can be obtained with a small amount of use, and prevents the deterioration of the properties of recycled polystyrene due to the mixing of this release agent. It is for doing.

In the present invention, it is necessary to remove (dry) the solvent within 3 seconds after applying the release agent to the film. It is assumed that the solvent removal is completed when the silicone is sufficiently cured as a release agent.

In the present invention, the amount of each component mixed and dispersed in a solvent is 3 to 7 parts by weight of a platinum-based catalyst, 6 to 14 parts by weight of an acetylene-based curing retarder, based on 100 parts by weight of an addition-type silicone.
The solvent is 500 to 1500 parts by weight.

The coating amount of the release agent is 50 mg / m ^{2 to 2} g / m ² of the mixture of the above components. If the amount of the release agent is less than 50 mg / m ² , there is a problem that the back surface releasability of the pressure-sensitive adhesive tape is deteriorated, and the cut pressure-sensitive adhesive tape is curled and becomes difficult to handle.
Further, even if it exceeds ² g / m ² , the effect is not changed, and an application amount exceeding ² g / m ² is unnecessary from an economic viewpoint.

In the present invention, the formation of the acrylic pressure-sensitive adhesive layer by applying an emulsion-type acrylic pressure-sensitive adhesive provides the necessary adhesive force without damaging a polystyrene-based film that is weak to a solvent, and at the same time, this adhesiveness is obtained. This is for forming the agent layer from a material having good compatibility with polystyrene. The acrylic pressure-sensitive adhesive layer is formed by applying an emulsion-type acrylic pressure-sensitive adhesive having a concentration of 40 to 65% by weight of 5 g / m ² or more and drying. If the coating amount is less than 5 g / m ² , the adhesive strength will be insufficient. As the emulsion-type acrylic pressure-sensitive adhesive, for example, “EMPS-30” manufactured by Cemedine can be used.

The specific production method of the polystyrene-based pressure-sensitive adhesive tape of the present invention is not particularly limited as long as the above-mentioned production conditions are satisfied, but it is preferable to apply the release agent while moving the polystyrene-based film at a constant speed. Is
It is preferable to dry with a dryer at a temperature of 80 ° C. for 2 seconds.

The polystyrene-based pressure-sensitive adhesive tape of the present invention can be easily cut by hand, and is excellent in printability, transparency, and gloss. Moreover, even if it is used to seal a box made of expanded polystyrene, it can be reprocessed without peeling because it is the same material.

[Examples] Examples of the present invention will be shown below, but the present invention is not limited thereto. Further, "parts" in the examples are all parts by weight.

Example 1 Thickness 30 μm, stretch ratio λT_D= 2, λM_D= 6 stretch points
Polystyrene film (Styrov manufactured by Asahi Kasei Corporation)
Film ) 50m / min speed using gravure printing press
Silicon 100 on one side while moving the film in degrees
Parts, 1,200 parts of heptane, 5 parts of catalyst, 9 parts of retarder
2g / m^TwoApply and pass through a hot air dryer (1.5m length) at 75 ° C to dissolve
The agent was removed and the silicone was cured. Is release agent applied?
It took about 1.8 seconds to remove the solvent.
In addition, 50% by weight of acrylic emuljo
20g / m^TwoIt was applied to remove water. It
It was lit and wound on a 200 m paper tube with a width of 50 m / m.

The pressure-sensitive adhesive tape of this example could be easily cut by hand.

In addition, the foamed polystyrene box sealed with the adhesive tape of this example was pulverized, pelletized, and a regenerated polystyrene film was formed by an inflation method, but the transparency was good, and the strength was formed only from the foamed polystyrene box. Little difference from the ones.

Example 2 An adhesive tape was prototyped in the same manner as in Example 1 except that 1200 parts of heptane of Example 1 was changed to 900 parts of hexane. The results were as good as in Example 1.

Example 3 An adhesive tape was prototyped in the same manner as in Example 1 except that 1200 parts of heptane of Example 1 was changed to 600 parts of hexane and 400 parts of heptane. The results were as good as in Example 1.

Example 4 An adhesive tape was prototyped in the same manner as in Example 1 except that the stretched polystyrene film of Example 1 was changed to a styrene-butadiene copolymer film. Results are in Example 1.
As good as.

Comparative Example 1 A recycled polystyrene film was molded in the same manner as in Example 1 using a foamed polystyrene box sealed with a polypropylene adhesive tape, but the transparency of the film was poor, and the strength was weak. Use was not possible.

Comparative Example 2 A silicone mixed solution in which heptane was changed to xylene in Example 1 was applied, but the stretched polystyrene film was cut at the time of application, and a prototype of the adhesive tape could not be produced.

Comparative Example 3 Production of an adhesive tape was attempted in the same manner as in Example 1 except that the temperature of the hot-air dryer was lowered and the time from the application of the release agent to the removal of the solvent was changed to 5 seconds. And the production of the adhesive tape was not possible.

[Effect of the Invention] As described above, the polystyrene-based adhesive tape of the present invention can be reprocessed without peeling when used for sealing a box made of expanded polystyrene, and is cut in comparison with the conventional polypropylene adhesive tape. And the workability of sealing and recycling of the expanded polystyrene box can be remarkably improved.

Further, a highly cosmetic pressure-sensitive adhesive tape can be produced by utilizing the excellent properties of polystyrene such as printability, transparency and gloss.

Claims (1)

(57) [Claims] The method according to claim 1] in the transverse direction draw ratio draw ratio of .lambda.T _D longitudinally when the .lambda.M _D, on one side of a polystyrene film is 2 ≦ λT _{D <λM D,} with respect to the addition type silicone 100 parts by weight , A platinum-based catalyst (3-7 parts by weight), an acetylene-based curing retarder (6-14 parts by weight) mixed and dispersed in a solvent selected from hexane, heptane or a mixture thereof in 500-1500 parts by weight. 50 mg / m ^{2 to 2} g / m ² and dried within 3 seconds, and 5 g of an emulsion type acrylic pressure-sensitive adhesive having a concentration of 40 to 65% by weight was applied to the other surface of the polystyrene film. A method for producing a polystyrene-based pressure-sensitive adhesive tape for box sealing made of expanded polystyrene, which is applied at a rate of at least / m ² .