JPH05202339A - Production of hot-melt adhesive and hot-melt adhesive - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a method for producing a hot melt adhesive, which prevents adhesives from adhering to each other in a corrugated cardboard or a hopper of an applicator to cause blocking or bridge. [Structure] A resin composition of a hot melt adhesive is continuously extruded from a mold, and the extruded product is conveyed to a cooling process by a belt conveyor having irregularities on the surface, cooled, and then cut into a predetermined length. In the method for producing a hot melt adhesive, cooling water is sprayed on a fluid extruded product in the cooling step to form an uneven pattern on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hot melt adhesive and a hot melt adhesive produced by the method.

[0002]

2. Description of the Related Art Conventionally, hot melt adhesives have a wide range of applications and have been used in many fields such as furniture, woodworking, plywood, bookbinding, packaging, shoes, can manufacturing, sewing and construction.

These hot melt adhesives are, for example,
Various shapes such as strips, spheres, tablets, pellets, and biscuits are available on the market.
However, many of these hot melt adhesives have a smooth surface. For example, when the hot melt adhesives are stored in a cardboard box or a paper bag and stored at room temperature or at a temperature slightly higher than room temperature, the hot melt adhesives are Joined together,
There is a problem that blocking is likely to occur.

Further, there is a problem that the hot melt adhesive put in the hopper of the applicator adheres to each other with the passage of time to form a bridge, and finally cannot be taken out from the hopper.

There are strip-shaped hot-melt adhesives having a cloth belt striped pattern on one surface, but a striped pattern provided on only one side has almost no effect of preventing blocking or bridging. Absent.

Some hot-melt adhesives have an uneven pattern formed on the surface. As a method for forming the uneven pattern, for example, a pair of embossing rolls having an uneven pattern on the roll surface during the manufacturing process are used. A method is used in which the hot-melt adhesive is passed through the rolls to give an embossed pattern while the hot-melt adhesive is fluid.

However, in the method using the embossing roll, when the temperature of the hot-melt adhesive is high, the hot-melt adhesive adheres to the roll surface and does not separate when passing through the embossing roll. Is lost, and it becomes difficult to apply an embossed pattern.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to form an uneven pattern on the surface of a cardboard box without using special equipment. It is an object of the present invention to provide a method for producing a hot melt adhesive in which adhesives are prevented from adhering to each other in a hopper of an applicator or the like and blocking or bridging occurs, and the hot melt adhesive according to the above production method.

[0009]

The present invention comprises the following two. The method for producing a hot melt adhesive according to claim 1,
The hot melt adhesive resin composition is continuously extruded from a mold, and the extruded product is conveyed to a cooling step with a belt conveyor having irregularities on the surface and cooled, and then cut into a predetermined length. In the method for producing an adhesive, cooling water is sprayed on an extruded product having fluidity in a cooling step to form an uneven pattern on the surface.

The hot melt adhesive according to claim 2 is characterized in that a surface is provided with an uneven pattern by the method for producing a hot melt adhesive according to claim 1. From the above, the above object is achieved.

The present invention will be described in detail below. The resin composition of the hot melt adhesive used in the present invention,
The base polymer is blended with additives such as a viscosity modifier and a tackifying resin.

Examples of the base polymer include ethylene / vinyl acetate copolymer (EVA), ethylene / acrylate copolymer (EA), polyethylene and the like.

Examples of the viscosity modifier include paraffin wax, microcrystalline wax, various low molecular weight polyethylene waxes, modified wax, atactic polypropylene and the like.

Examples of the tackifying resin include rosin and rosin derivatives, phenol resins, terpene resins,
Examples include coumarone / indene resin and petroleum resin.
Additives other than the base polymer are appropriately determined according to the required performance of the hot melt adhesive, the use conditions, the application, and the like.

Next, the method for producing the hot melt adhesive of the present invention will be described. As shown in FIG. 1, a resin composition of a hot melt adhesive is continuously extruded from a mold 1 attached to the tip of an extruder (not shown).

As the mold 1, a mold having a structure capable of simultaneously extruding a plurality of extruded products 2 is used. The temperature of the extruded product 2 extruded from the mold 1 is usually 10
The temperature is in the range of 0 to 150 ° C., supported by the belt conveyor 3 and conveyed to the cooling step.

Further, since the belt conveyor 3 has a surface 31 having irregularities (not shown), the extruded product 2 reaching the surface 31 of the belt conveyor 3 is conveyed to the cooling step. Up to now, the cross-section is deformed to become flat due to its own weight, and the unevenness formed on the surface 31 of the belt conveyor 3 forms an uneven pattern on the lower surface 22 of the extruded product 2.

The unevenness of the belt conveyor 3 can obtain the same effect as that of the unevenness by using, for example, a coarse material of the belt conveyor 3 without any special processing.

In the cooling step, the extruded body 2 is cooled by spraying the cooling water 5 from above the extruded body 2 by the spraying device 4, and the uneven surface pattern 23 is formed on the upper surface 21 of the extruded body 2. Is formed.

The spraying device 4 is not a special one. For example, spray nozzles are arranged downward at regular intervals in the water supply pipe, and cooling water is sprayed from this nozzle to the surface 21 of the extruded product 2. An uneven pattern can be formed.

When the temperature of the extruded product 2 conveyed to the cooling step becomes high, it becomes difficult to maintain its shape, and when it becomes low, it becomes difficult to form an uneven pattern on the surface 21 and the surface 22 of the extruded product 2. For example, when EVA is used as the base polymer, the temperature range of 90 to 140 ° C. is preferable.

If the temperature of the cooling water 5 is too high, the cooling effect is lowered and the uneven pattern 23 cannot be formed efficiently. Therefore, the temperature is preferably 30 ° C. or lower. The shape of the unevenness 23 formed on the surface 21 of the extruded product 2, the depth of the concave portion, and the height of the convex portion can be adjusted by adjusting the spray pressure of the cooling water 5.

That is, when the spray pressure is increased, the concave portion becomes deep and the convex portion becomes high. When the dimensional difference between the convex portion and the concave portion is small, the effect of preventing the occurrence of blocking or bridge is lost, and when it is large, it becomes difficult to remove the cooling water. is there.

The uneven pattern may be formed on the surface of the hot melt adhesive as what is recognized as a concave portion and a convex portion, and does not necessarily have to be formed uniformly on the entire surface.

After the extruded product 2 is cooled, it is cut into a predetermined length by a cutting device (not shown) to obtain a hot melt adhesive. The hot-melt adhesive of the present invention is molded into various shapes such as a strip shape, a column shape, a biscuit shape, a pellet shape, and a string shape by changing the shape and the cut shape at the time of extrusion molding by the above method. It is possible to form an uneven pattern on the entire surface of the molded product.

[0026]

[Function] The resin molding of the hot melt adhesive is conveyed to the cooling step by the coarse belt conveyor and sprayed with cooling water to cool the resin molding and simultaneously form an uneven pattern on the surface of the resin molding. Therefore, no special equipment such as embossing roll is required.

By forming an uneven pattern on the surface of the hot melt adhesive, it is possible to prevent the hot melt adhesives contained in the corrugated cardboard or the applicator hopper from sticking to each other, and to prevent blocking or bridging.

[0028]

EXAMPLES Examples of the present invention will be described below. (Example 1) 1) Production of hot-melt adhesive sample During production of a hot-melt adhesive (Esdyne 8512AS manufactured by Sekisui Chemical Co., Ltd., softening point: 106 ° C) using an ethylene / vinyl acetate copolymer (EVA) as a base polymer. , The resin molded body extruded from the mold is conveyed by a coarse belt conveyor, and cooling water is sprayed in the cooling step to form an uneven pattern on both surfaces of the hot melt adhesive, and then to a predetermined length. By cutting, a substantially square sample (about 2 mm thick, about 1 cm square) was manufactured. 2) Blocking test The sample of the hot-melt adhesive produced in 1) is filled in the hopper 6 shown in FIG. 2 so as to fill it up and left at ambient temperature of 30 ° C. and 40 ° C. for a certain period of time. Open and observe the falling state of the sample, measure the time until the samples block each other and do not fall at once,
The results are shown in Table 1. (Example 2) A hot melt adhesive sample was produced in the same manner as in Example 1 except that "Esdyne 8512H6" (base polymer EVA, softening point 109 ° C) manufactured by Sekisui Chemical Co., Ltd. was used as the hot melt adhesive. After that, the same blocking test as in Example 1 was performed, and the results are shown in Table 1.
It was shown to. (Comparative Example 1) A blocking test was conducted in the same manner as in Example 1 except that a hot melt adhesive having no uneven pattern on both sides was used as a sample, and the results are shown in Table 1. (Comparative Example 2) A blocking test was conducted in the same manner as in Example 2 except that a hot melt adhesive having no uneven pattern on both sides was used as a sample, and the results are shown in Table 1.

[0029]

[Table 1]

[0030]

According to the present invention, by forming an uneven pattern on the surface of the hot melt adhesive, it is possible to prevent the hot melt adhesives from sticking to each other, and to prevent blocking when the hot melt adhesive is packed in a corrugated cardboard or an applicator. It is possible to prevent the occurrence of bridges when the hopper is filled.

Further, according to the present invention, by spraying the high temperature hot melt adhesive with cooling water in the cooling step,
Since the uneven pattern can be formed, no special equipment is required.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing an embodiment of a method for manufacturing a hot melt adhesive according to the present invention.

FIG. 2 is a perspective view showing a hopper used for a blocking test of a hot melt adhesive in the present invention.

[Explanation of symbols]

 1 Mold 2 Extruded Product 3 Belt Conveyor 4 Sprayer 5 Cooling Water 6 Hopper

Claims (2)

[Claims] 1. A resin composition of a hot melt adhesive is continuously extruded from a mold, and the extruded article is conveyed to a cooling step by a belt conveyor having irregularities on its surface and cooled, and then a predetermined length is obtained. A method for producing a hot-melt adhesive, which comprises spraying cooling water onto an extruded product having fluidity in a cooling step to form an uneven pattern on the surface. 2. A hot melt adhesive characterized in that an uneven pattern is formed on the surface thereof by the method for producing a hot melt adhesive according to claim 1.