JPH0432114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for continuous production of embossed hot melt adhesive films or sheets whose surfaces may be temporarily protected.

[Prior Art] Conventionally, the method of forming fine irregularities on the surface of plastic film, that is, applying eboning processing, involves sandwiching the film between a heated embossing roll and a back-up roll, and softening the film by heating. A method has been used in which the embossing roll pattern is transferred to the film by pressure bonding. However, if this method is applied to a plastic film that exhibits significant tackiness during hot molding, the film will stick to the embossing roll and cannot be peeled off. Or, even if it is possible to separate the film from the roll by applying strong tension to the film, the tension may cause uneven deformation of the heat-softened film or extreme netting, making it difficult to take off or handle after embossing. This causes significant inconvenience and adversely affects the product shape of the film.

The method devised to overcome the above drawbacks is
Consideration of operating conditions and surface treatment (for example,
54-150365) to provide non-adhesive properties, but both are insufficient as countermeasures. The method (2) often has significant restrictions on the emboss shape and processing conditions, and the method (2) may have little effect depending on the resin to be processed. In particular, in the case of hot-melt adhesives that rapidly soften and melt when heated and exhibit strong adhesive properties, the above-mentioned drawbacks often become apparent. However, this kind of film requires embossing to improve the tacking properties after processing, and in this case, embossing is relatively often applied to both sides of the film, which imposes significant restrictions on processing conditions. The method is very difficult.

[Problems to be Solved by the Invention] An object of the present invention is to enable simultaneous embossing on both sides without severe restrictions on processing conditions in embossing a hot melt adhesive film.
The purpose is to provide a stable continuous processing method. or,
Depending on the use of the product, the processing method must have the possibility of preventing the release agent from being transferred to the product.

[Means for Solving the Problems] The present invention provides a method for continuously manufacturing an embossed hot melt adhesive film or sheet by an embossing method that achieves the above-mentioned objectives, namely: It is an invention of

Roll pressure bonding of a non-adhesive film or sheet to both sides of a hot-melt adhesive film or sheet, in which case at least one of the non-adhesive films or sheets has fine irregularities on the surface in contact with the hot-melt adhesive. The non-adhesive film or sheet is further peeled off after the roll crimping, and if necessary, the non-adhesive film or sheet is further peeled off after the roll crimping. A method for continuously producing a film or sheet of a hot melt adhesive having fine irregularities on at least one side, which may be protected by an adhesive film or sheet.

In the present invention, the hot melt adhesive film or sheet is hereinafter referred to as a hot melt adhesive film. A non-adhesive film or sheet is also referred to as a non-adhesive film. Although films and sheets are distinguished by their thickness (generally, films with a thickness of less than 0.2 mm are called films, and films with a thickness of 0.2 mm or more are called sheets), but the present invention is not limited by these names. . That is, both of the above may be a film or a sheet, and below, a film will be used as a representative.

The thickness of the hot-melt adhesive film in the present invention is not particularly limited, but it is usually approximately 1 mm or less, particularly 0.5 mm or less. Most preferably, it is less than 0.2 mm and is referred to as a film in the narrow sense as described above.

The material is made of various thermoplastic resins known as hot melt adhesives or thermoplastic resins containing a small amount of crosslinking agent. Of course, it may contain colorants, stabilizers, flame retardants, fillers, and other additive components. Examples include vinyl acetate resins, ethylene-vinyl acetate copolymer resins, linear polyester resins, thermoplastic polyurethane resins, polyvinyl butyral resins, and polyamide resins. The softening point is suitably about 150°C or lower, particularly preferably about 60 to 130°C.

The most preferred hot melt adhesive is about 80~
These are thermoplastic polyurethane resins, linear polyester resins, and ethylene-vinyl acetate resins that have a softening point of 130°C.

The thickness of the non-adhesive film is not particularly limited as long as it has flexibility, but is usually about 0.2
Films with a thickness of less than mm, especially about 0.01 to 0.1 mm, are preferred. The material is not particularly limited as long as it is non-adhesive to the hot melt adhesive.
Alternatively, the surface of a film made of an adhesive material may be coated with a non-adhesive substance, or a film made of an adhesive material may be mixed with a non-adhesive substance to make the surface non-adhesive. For example, a plastic material coated with or mixed with silicone oil or the like can be used. However, in these cases, there is a considerable risk that the non-adhesive substance will migrate to the surface of the hot melt adhesive, reducing its adhesive properties. Therefore, the non-stick film is preferably made of a non-stick material. For example, films made of polyolefin resins, fluorine-containing resins, linear polyester resins such as polyethylene terephthalate, etc. are preferred. Particularly preferred is polypropylene resin. In addition, the hot melt adhesive must have a softening point that does not soften when it is pressed against the film, and the softening point is at least about 10°C higher than the temperature at the time of pressing, preferably about 150°C or more. It is preferable to have a point. Further, it is preferable that the material has hardness and heat resistance to the extent that the embossing does not collapse or shrinkage wrinkles occur during crimping. A polypropylene film of about 20 to 50 μm is most preferred under the normal pressure bonding temperature of around 100° C., and a polyethylene terephthalate film, a polyimide film, and a fluorine-containing resin film are suitable at higher temperatures.

At least one of the two non-adhesive films,
The surface in contact with the hot-melt adhesive (hereinafter referred to as the inner surface) has fine irregularities, that is, embossments. The non-stick film may have embossing on both sides. Both of the two non-adhesive films may have embossments on their inner surfaces. In this case, a hot melt adhesive film having embossing on both sides is obtained. When only one of the two non-adhesive films has an embossment on its inner surface, a hot melt adhesive film having an embossment on one side is obtained. Preferred in the present invention is a hot melt adhesive film having embossing on both sides. The height of the embossing on both films is not particularly limited, but is about 0.1 to 10μ, especially about
0.5 to 5μ is appropriate. Furthermore, when two embossed non-adhesive films are used, the shapes and patterns of the embossments may be different.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of implementing the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic side view showing one example of the manufacturing method of the present invention. A hot melt adhesive film A, which is embossed on both sides, is fed between rolls C and D together with non-tacky films B and B' having embossments on their inner surfaces, as shown in the figure. At this time, it goes without saying that the embossed surfaces of the non-adhesive films B and B' must be on the E and F sides, respectively. In this case, the rolls C and D are generally pressed against each other by air pressure, oil pressure, etc. and rotate in the direction of the arrow, thereby laminating the films A, B, and B' while continuously drawing them in.

The rolls C and D do not need to be particularly limited to metal rolls or rubber rolls, and may be made of different materials. Moreover, heating and cooling may be performed as necessary.

There is no particular limitation on the method of supplying the film A, and it can be supplied either directly from a film die during extrusion molding or from some kind of cut-out part off-line.

It is preferable that the pressure bonding be carried out at a temperature at which the hot-melt adhesive softens, but at a temperature at which the non-tacky film does not soften. Of course, it is possible to transfer the embossing under temperature conditions that allow plastic deformation even below the softening temperature of the hot melt adhesive. However, crimping is usually carried out at temperatures of about 80 to 130°C. A relatively low pressure can be used as long as the pressure is higher than the softening temperature of the hot melt adhesive.

Hot-melt adhesive films temporarily protected with a non-tacky film are usually not stripped of the non-tacky film until the point of use. Therefore, hot-melt adhesive films protected with this non-adhesive film are used as commercial products. However, if the adhesive film is used for adhesion immediately after the pressure bonding, the non-adhesive film may be peeled off immediately after the pressure bonding.
Therefore, what is produced in the present invention is an embossed hot-melt adhesive film protected with a non-adhesive film, but in some cases, an embossed hot-melt adhesive film from which the non-adhesive film has been peeled off. It may also be a film.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

[Example] A thermoplastic polyurethane hot melt adhesive (softening temperature 90°C) was heated and melted in an extruder to a width of 450 mm.
Thickness is obtained by discharging at 120℃ from a mm film die.
A 150μ film was prepared and this film was continuously fed to a roll as film A in FIG. Roll D is a rubber-lined roll and roll C is a metal roll, which are pressed against each other with a linear pressure of 10 kg/cm. The metal roll C is cooled with a heat medium.
Films B and B' were both polypropylene films with a thickness of 50 μm and having embossments on the surface with a depth of about 1 μm.

As a result, stable take-up and winding operations were made possible without the film sticking to the roll.

Furthermore, when the polypropylene film was peeled off from the thermoplastic polyurethane film after processing, embossments approximately the same as those of the polypropylene film were formed on both sides with a depth of approximately 1μ, indicating that the thermoplastic polyurethane film itself had tacking properties at room temperature. It stopped happening at all.

Note that when embossing was performed on the hot melt adhesive film using an embossed silicone rubber or fluorine resin coated roll without using the polypropylene film, the resin stuck to the roll and the embossing was interrupted. It was virtually impossible.

[Effects of the Invention] As described above, the present invention has excellent effects in terms of the range of processing conditions during molding, the arbitrariness of the embossing shape, and the stability of molding, and allows simultaneous embossing on both sides. It is also advantageous in some respects compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention.
In the figure, A is a hot melt adhesive film to be embossed, B and B' are non-adhesive films with embossments to be transferred to film A,
E indicates the embossed surface of film B, and F indicates the embossed surface of B'. C, D are films A, B,
This is a roll for crimping B′.

Claims (1)

[Claims] 1 Roll pressure bonding of a non-adhesive film or sheet to both sides of a hot-melt adhesive film or sheet, at which time at least one of the non-adhesive films or sheets has fine irregularities on the surface in contact with the hot-melt adhesive. The invention is characterized in that fine irregularities are transferred to the surface of the hot-melt adhesive film or sheet during the roll pressure bonding, and if necessary, the non-adhesive film or sheet is further peeled off after the roll pressure bonding. A method for continuously producing a hot-melt adhesive film or sheet having fine irregularities on at least one side, which may be protected by a non-adhesive film or sheet.