JP2003020467A - Solid hot-melt adhesive having mutual blocking resistance and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid hot-melt adhesive decreasing the intrusion of foreign materials such as a film into the hot-melt adhesive as far as possible, preventing the mutual bonding of the hot-melt adhesive blocks, having excellent workability and solving the problem of packaging methods to prevent the mutual adhesion of conventional hot-melt adhesives and provide a method for producing the hot-melt adhesive. SOLUTION: The method for the production of a solid hot-melt adhesive resistant to mutual bonding comprises the charging of a hot-melt adhesive heated at or above the flow point into a wax-coated porous vessel while cooling the vessel, the cooling of the vessel until at least the surface of the hot-melt adhesive is solidified, the contact of the vessel with hot water heated above the melting point of the wax and the taking of the solidified adhesive out of the vessel. The invention further provides the solid hot-melt adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for packaging a hot melt adhesive with a wax and a packaged hot melt adhesive solid having an anti-adhesion property.

[0002]

2. Description of the Prior Art Hot melt adhesives which are generally heated and applied in a fluid state are solid at room temperature. Although hot melt adhesives are generally provided in block form and heat melted during use, these material properties cause various problems when handling and packaging hot melt adhesives. The solid hot melt adhesive block not only sticks or sticks to hands or mechanical handling devices, but also sticks or sticks together these hands or devices, or picks up dirt and contaminants. In addition to this, the hot-melt adhesive, which has an adhesive surface, is filled in paper containers, plastic containers that have undergone a mold release treatment such as silicone in order to avoid mutual adhesion and improve workability. Has been used.

[0003]

However, in such a packaging method, when the packaged hot melt adhesive is used, it is necessary to remove the packaging material and dispose of it.
It is time-consuming and may cause environmental pollution due to waste.

Therefore, from the viewpoint of resource saving and environmental protection, a method is adopted in which these containers are not used, a hot-melt adhesive is wrapped in a thin polyolefin film, and the polyolefin film is melted as it is without being stripped off. However, these methods also take a long time to uniformly dissolve in the hot-melt adhesive composition because the softening point of the polyolefin film is relatively high, and due to the properties of the polyolefin, the performance of the hot-melt adhesive may be reduced or the hot-melt adhesive may be deteriorated. There was a problem that the thermal stability in the melt tank was reduced. Also, a method has been proposed in which wax or the like is sprayed inside the metal container in advance and the container is filled with hot-melt adhesive to eliminate surface tackiness, but the amount of wax adhered on the side surface is smaller than that on the bottom surface. In addition, there is a problem that adhesiveness appears on the surface and side surfaces during storage, and the blocks reattach when they are taken out from the container and stored.

To solve these problems, a wax is used to coat as large a block of the hot melt adhesive as possible, and a fusible film is applied to the parts in contact with each other, whereby the proportion of different materials is increased. Need to be as low as possible. As such a method, for example, a method of spraying wax into a tray of various shapes such as a cylinder and a rectangular parallelepiped and filling and molding the hot-melt adhesive has been studied. However, when the coating amount of wax is small, the tray and the hot-melt adhesive are melted. It is difficult to peel off the adhesive. Further, when a large amount of wax is used, peeling from the tray becomes easy, but a large amount of wax is mixed when the hot melt adhesive is used, which has a drawback that the performance as an adhesive is affected.

An object of the present invention is to solve the above-mentioned problems of the conventional packaging method for preventing mutual adhesion of hot melt adhesives, and to prevent mixing of different materials such as films into the hot melt adhesive as much as possible. It is an object of the present invention to provide a hot-melt adhesive solid material which is reduced in amount and prevents the hot-melt adhesive block from adhering to each other and has excellent workability, and a method for producing the same.

[0007]

According to the present invention, a hot-melt adhesive heated to a flow temperature or higher is inserted into a porous container coated with wax while the container is cooled, and at least the surface of the hot-melt adhesive is solidified. After being cooled to the temperature, the container is brought into contact with hot water having a temperature not lower than the melting point of the wax, and the hot melt adhesive is taken out from the container. A method and the hot melt adhesive solids.

When the adhesive is cooled until it solidifies, it is also preferable to apply a wax to the surface of the adhesive which is not in contact with the container, if necessary. Further, by removing the adhesive from the container and washing the adhesive with hot water or hot water having a melting point of wax or higher, if necessary, unnecessary wax can be removed from the surface of the hot melt adhesive and hot melt can be performed. As a result, the wax is uniformly coated on the surface of the adhesive, and the effect of preventing the hot melt adhesives from adhering to each other can be further expected and is more preferable.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The porous container used in the present invention means a container having a large number of minute openings, and more specifically, the main part of which is made of wire mesh and is in the shape of a basket or basket. However, it is also possible to use a hole-conical container having a large number of small holes in a metal tray. The use of a container having a large number of mesh-like holes prevents the wax adhering to the side surface from flowing down, facilitates the formation of a required amount of wax layer on the hot melt adhesive, and causes excess wax to be present on the lower surface portion. Since it drips out of the container, it has an effect of preventing more wax than necessary from adhering to the hot melt adhesive. In addition to this, the reason for using a wire net or a porous metal container is that it has excellent thermal conductivity and that heating and cooling are performed quickly. When the container is in a mesh shape, a part of the hot melt adhesive in the container comes into contact with the refrigerant directly or through a thin wax layer, so that the hot melt adhesive at a high temperature is cooled more quickly than when using a film. .

The ratio of the openings of the porous container used in the present invention is appropriately selected depending on the viscosity of the wax used, the temperature of the refrigerant, and the shape of the container.
A mesh (JIS G 3555) is preferable, and a mesh having 10 to 50 mesh is particularly preferable.
If the opening ratio is too large, the wax film may not be formed sufficiently and the treated hot melt adhesives may adhere to each other. If the opening ratio is too small, the excess wax may not be sufficiently removed or removed. Takes time.

Although the form of the container according to the present invention is not particularly limited, for example, a basket shape, a basket shape, a tray shape, an inverted trapezoidal shape, a hemispherical shape, a cylindrical shape, a semicylindrical shape, a conical shape, a kamaboko shape and the like. In general, it is preferable that the upper surface is opened and there is a slight squeeze from the upper edge toward the bottom because it is easy to take out the hot melt adhesive. When a container having an open upper part is used, it is preferable to fill the container with the hot melt adhesive, cool it, and then apply wax to the surface of the hot melt adhesive not in contact with the container. In this case, the wax is applied by brushing or spraying. The object of the present invention can also be achieved by applying an appropriately selected film, sheet or the like to this surface during packaging instead of applying wax. It is also possible to omit the wax coating step by using a container in which a hot melt adhesive injection port is provided on one side and an exhaust port is provided on the other side, which is partially enclosed by a hinge or other means. Is.

Examples of hot melt adhesives used in the present invention include synthetic resins, synthetic rubbers, plasticizers, petroleum-based substances,
There are adhesives made of natural resins, fillers and the like. The wax used in the present invention is not particularly limited, but includes, for example, petroleum wax such as paraffin or microcrystalline wax, or synthetic wax such as polyethylene wax and Fischer-Tropsch wax. The melting point of wax is 50 ~ 100 ℃
The range is preferably about 60 to 90 ° C.

As means for coating the container with wax, the container is soaked in a wax bath heated to a softening point or higher by a heating device and then lifted, and excess wax is removed by natural dripping or centrifugal force. A method of applying a molten wax with a brush by a means or spraying the wax from a nozzle is used. The container coated with wax by these means is usually immersed in a refrigerant or brought into contact with cold air before inserting the hot melt adhesive in advance, or cooled to a temperature below the melting point of the wax by any means. Further, the cooling may be continued during the insertion of the hot melt adhesive or after the insertion of the hot melt adhesive.

The hot melt adhesive is heated to a temperature equal to or higher than the softening point and filled in a container by an extrusion pump or the like.
The filled hot melt adhesive is cooled together with the container by contacting it with, for example, a cooling medium or cold air until at least its surface is solidified. After at least the surface of the hot melt adhesive is solidified, the container is immersed in a hot water bath having a temperature equal to or higher than the melting point of the wax, or hot water is sprayed from the outside of the container. This melts some of the wax coated on the container, facilitates removal of the hot melt adhesive solids from the container, and removes excess wax from the surface of the hot melt adhesive. The larger the amount of wax forming the film on the solid material of the hot melt adhesive, the more effective it is to prevent the hot melt adhesives from sticking to each other, but it is not only uneconomical, but also affects the performance of the hot melt adhesive. Therefore, the immersion time in the hot water bath is appropriately determined in consideration of the workability of taking out and the required amount of wax to be attached to the hot melt adhesive. Further, when the removal of the excessive wax is insufficient, it is preferable to wash the taken-out hot melt adhesive solid with further warm water or hot water. By properly cleaning the surface of the hot melt adhesive in this way, unnecessary wax can be removed from the surface of the hot melt adhesive and the wax is evenly coated on the surface of the hot melt adhesive. The anti-adhesion effect can be further expected.

It is more effective to select a hemispherical shape, a semi-cylindrical shape, or a conical shape as the shape of the container used for carrying out the present invention. Even in the method of the present invention, since the wax is slightly coated on the bottom surface rather than the side surface of the container, the wax layer on the surface of the hot-melt adhesive solid has a slightly thick layer formed on the top thereof. When the melt adhesive solids are stacked, the wax layer at the contact portion becomes thicker, and the effect is exerted by preventing mutual adhesion. Furthermore, when shipped in a stack of cardboard boxes, etc., hemispheres, kamaboko, and cones have clues when taking them out. Workability is improved.

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the invention is not limited thereto.

Example 1 Paraffin wax having a melting point of 75 ° C. was heated to 130 ° C. and sprayed into a hemispherical container made of a 16 mesh stainless wire mesh. At that time, the wire mesh was coated with wax with a thickness of about 2 mm without any gap. Furthermore, in order to fully confirm that there is no gap, the coated container was immersed in a water tank, and it was confirmed that there were no water drops on the inner surface of the container. While dipping this container in cold water to cool it from the outside, add 15 parts of plasticizer, 55 parts of petroleum resin, 3 parts of synthetic rubber to it.
About 650 g of hot melt adhesive consisting of 0 part and 0.5 part of antioxidant is poured and cooled at a temperature of 130 ° C to 150 ° C and heated to 130 ° C from the upper surface when the fluidity of the hot melt adhesive disappears. The sprayed paraffin wax was sprayed. This was repeated so that the surface of the wire mesh was the top surface, and hot water at 90 ° C. to 100 ° C. was applied to this to easily separate the hot melt adhesive from the container. 90 ℃ for the hot melt adhesive taken out
When hot water of 100 ° C. was poured, the mixture became white to semi-transparent, excess wax was washed off moderately, and the target hot-melt adhesive solid was obtained.

Example 2 The residual amount of wax in the hot melt adhesive prepared in Example 1 was weighed. As a result, it was found that about 0.3% of paraffin wax remained on the surface of the hot melt adhesive. The properties of the hot-melt adhesive alone and the properties of the wax-coated hot-melt adhesive are
B method of SK 6862, softening point is JIS K 686
3, 180 degree peeling was tested according to JIS Z 0237. The results are shown in Table 1.

[0019]

[Table 1]

From the table, the hot-melt adhesive coated with paraffin wax showed a tendency that the viscosity, the softening point and the 180 ° peel strength were lower than those of the unmelted hot-melt adhesive. However, it does not prevent the use as an adhesive or a pressure-sensitive adhesive, and sufficient quality has been obtained.

Test Example 1 The following experiment was conducted in order to investigate the relationship between the thickness of the wax layer on the surface of the hot melt adhesive and the tackiness. Plasticizer 20
Part, petroleum resin 57 parts, synthetic rubber 23 parts, antioxidant 0.
Paraffin wax was sprayed onto the surface of a hot melt adhesive consisting of 5 parts to obtain a paraffin wax layer having an average thickness of about 385 microns. Next, the paraffin wax on this surface was washed off with hot water to obtain an average thickness of about 163 microns. Further, the paraffin wax on the surface was washed off with hot water to obtain an average thickness of about 135 μm. The tack of the surface of these hot melt adhesives was measured. The average thickness of the paraffin wax layer of the hot melt adhesive coated with paraffin wax of Example 1 was about 150 microns. The measuring method is JIS
A hot melt adhesive was attached to the test plate side using a method with reference to the Z0237 loop tack test, and the force required to peel off the hot melt adhesive surface and the loop-shaped PET film was measured. The results are shown in Table 2.

[0022]

[Table 2]

From the table, it can be seen that the coated surface is much less sticky than the surface not coated with paraffin wax, and the wax is washed off with hot water moderately as compared with the surface coated with spray wax. The resulting surface was thinner and more uniformly coated, and the tackiness was further eliminated.

Example 3 Paraffin wax was spray-coated in the same manner as in Example 1 on a cylindrical container composed of a 20 mesh wire mesh. Molten plasticizer 17 while cooling the outside of the container with water.
Part, 60 parts of petroleum resin, 23 parts of synthetic rubber, and 1 part of a hot melt adhesive, about 1.5 Kg, were filled in the container. After the hot melt adhesive was cooled and solidified, the container was turned upside down and hot water was poured to take out the hot melt adhesive from the container. Further, the taken out hot melt adhesive was washed with hot water to obtain a hot melt adhesive block having a cylindrical shape having a length of 25.5 cm and a diameter of 9 cm and having a surface paraffin wax layer having a thickness of about 60 μm.

Test Example 2 Two hot melt adhesive blocks prepared in the same manner as in Example 3 were stacked so that their lengthwise directions were horizontal and left at 25 ° C. for 3 days. After that, when the upper block was peeled off from the lower block, it was easily peeled off and it was confirmed that they were not attached to each other. The hot melt adhesive blocks similar to those in Example 3 were stacked in the same manner as above except that they were not wax-coated, and were left under the same conditions. After that, the peeling was attempted in the same manner as described above, but the blocks were attached to each other and could not be peeled off.

[0026]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to minimize the wax layer which gives the anti-adhesion effect to the hot melt adhesive, and to substantially improve the performance of the hot melt adhesive for the intended purpose. It is possible to prevent the adhesives from adhering to each other without damaging the adhesive. Further, according to the present invention, by using a porous container, it is possible to easily separate the hot melt adhesive and the container without requiring an excessive external force. Further, the product according to the method of the present invention is
Since the content of different materials such as films can be extremely reduced, it is not necessary to provide excessive quality in product design. Further, since it can be put into the melting tank as it is, it is easy to handle, and an extremely excellent packaging form is provided without generating waste such as a packaging container.

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Claims (4)

[Claims] 1. A wax-coated porous container is inserted with a hot-melt adhesive heated to a flow temperature or higher under cooling of the container and cooled at least until the surface of the hot-melt adhesive is solidified. A method for producing a hot-melt adhesive solid having mutual adhesion preventing property, which comprises bringing the hot-melt adhesive into contact with hot water having a temperature higher than the melting point of wax to take out the hot-melt adhesive from the container. 2. The method according to claim 1, wherein the porous container has a shape selected from the group consisting of hemispherical shape, semicylindrical shape and conical shape. 3. The manufacturing method according to claim 1, further comprising a step of washing the taken out hot melt adhesive with warm water or hot water. 4. A hot-melt adhesive solid having a mutual adhesion preventive property, which is obtained by the method according to any one of claims 1 to 3 and is mostly covered with a wax layer.