JPS608065B2 - Hot melt organic-inorganic mixed adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a hot-melt organic-inorganic mixed adhesive, more specifically, a mixture of hot-melt organic powder and inorganic powder, which is particularly suitable for bonding nonwoven fabrics and has excellent heat resistance. This invention relates to an adhesive capable of exhibiting adhesive strength.

As conventional hot melt adhesives, for example, those with a 100% solid content mainly composed of thermoplastic resin are used, which generally have an extremely short bonding time and are suitable for high-speed mass production of adhesives, and are suitable for a wide range of applications. It has been put into practical use as an adhesive that can be applied to signage.

This adhesive is used by being heated and melted in a high-temperature pot, applied to various adherends, and then cooled and solidified under pressure. In contrast, recently, suspended or colloidal hot melt adhesives have been developed, which are made by dispersing hot melt resin powder in water in the presence of an emulsifier or dispersant. It is used by applying it to the material and then applying pressure or heating/pressure. This suspension or colloidal adhesive is 100%
Compared to solid materials, they are advantageous in that they do not require preliminary heating and melting treatment, do not require heating and melting equipment, and are easy to clean up after use. If the kimono is placed in a high-temperature atmosphere close to or above the softening point of the hot melt resin powder, the adhesive strength will decrease and the kimono will naturally peel off, or it will easily peel off due to weak external force. occurs.

For this reason, the hot-melt resin powder used has a softening point or melting point higher than the temperature of the high-temperature atmosphere and is of a high grade, and high-temperature heating must be used during bonding. On the other hand, various hot melt adhesives have been proposed that exhibit relatively little decrease in adhesive strength in the above-mentioned high-temperature atmosphere, that is, have heat resistance.

In particular, it exhibits good adhesive strength in instant processing where heating and pressure times of 1/500 to 1/10 of sand are used.
Heat-resistant adhesives are generally solvent-based, such as chloroprene-based or nitrile-based synthetic rubber solvent-based adhesives. However, these adhesives do not have sufficient heat resistance, and in order to be applied to bonding non-woven fabrics, the adhesive viscosity and application amount must be selected under appropriate conditions (for example, chloroprene-based adhesives The optimal conditions for bonding non-woven fabrics with a fabric weight of 9 mm with adhesive are a viscosity of 2,000 to 250 ps, and an adhesive film thickness of 15 ps.
If not selected, adhesive permeation phenomenon may occur, staining the processing machine or causing fluffing of the non-woven fabric, so special care must be taken especially when molding of the non-woven fabric is involved. There is. Furthermore, the biggest problem is pollution caused by solvent scattering during adhesion and processing. With the aim of providing a hot melt adhesive that is non-polluting, has excellent heat resistance, and exhibits adhesive strength, the inventors have conducted intensive research and discovered that a suspension or colloid of hot melt resin powder in water It has been discovered that the desired adhesive can be obtained by mixing an inorganic powder into the solution.

The present invention was completed based on the above-mentioned findings, and the gist thereof is to use hot melt resin powder and 50 to 10% by weight of pentonite to the hot melt resin powder.
A hot-melt organic-inorganic mixed adhesive comprising at least one inorganic substance selected from kaolin and silica dispersed in water.

In the present invention, as the hot-melt resin powder, a conventional one may be used, such as vinyl acetate powder (polyvinyl acetate, vinyl acetate-ethylene copolymer, etc.), vinyl chloride IJden powder (vinylidene chloride-ethylene copolymer, etc.), (vinyl chloride copolymer, etc.), ethylene (low molecular weight polyethylene,
(ethylene-pinyl acetate copolymer, etc.), polyimide, phenoxy resin/ethyl cellulose, polyisobutylene,
Examples include powders such as petroleum resin and polyester, and at least one of these is used.

In the present invention, examples of the inorganic powder include pentonite, kaolin, silica, etc., and at least one of these is used.

The amount used is usually 50 to 100% (wt%, same hereinafter), preferably 6% to the above hot melt resin powder.
It may be selected within the range of 5 to 75%. If it is less than 50%, the desired heat resistance cannot be obtained, and if it exceeds 100%, the adhesive strength of the hot melt resin powder tends to be damaged by freezing.

The adhesive of the present invention is composed of a system in which hot-melt resin powder and inorganic powder are dispersed in water in the above-mentioned predetermined proportions.

As a method for preparing the adhesive, for example, hot-melt resin powder may be added to a suspension of inorganic powder, and the mixture may be mixed together. In this way, a suspended or colloidal adhesive of the invention is obtained with a total organic/inorganic powder concentration of 45 to 60%. In addition, in such preparation, if the hot melt resin powder used has poor moisture resistance, it will cause uneven adhesive strength. It is preferable to mix an appropriate amount of an emulsifier or a dispersant into the water. Further, there is no problem in adding commonly used plasticizers, tackifiers, melt viscosity modifiers, oxidation and decomposition inhibitors, and the like. The adhesive of the present invention can be used in the same applications as ordinary hot melt adhesives (for example, packaging, bookbinding, shoe making, plywood, etc.).
It can be applied to bonding of woodworking/building materials, textiles, etc., and is particularly useful for bonding nonwoven fabrics such as acrylic fibers, nylon fibers, and polyester fibers.

According to the adhesive of the present invention having the above-mentioned structure, it is possible to exhibit an excellent heat resistance effect that is as good as that of conventional solvent-based adhesives, and the problem of pollution caused by solvent scattering is completely eliminated.

Also, the type of resin powder (especially in terms of softening and melting points), such as traditional suspension or colloidal adhesives,
The resin powder can be used freely without being limited to. Next, the present invention will be specifically explained with reference to Examples.

Note that Examples include examples for comparison. Example
1 Polyester powder (softening point (JIS-K-2531)
(by ring and ball method): 16300, melting point: 180-200
(○) is mixed and dispersed in emulsifier-containing water (for example, water to which several parts of a nonionic surfactant such as polyoxyethylene monolaurate, sorbitan sesquiolate, or polyoxyethylene alkylphenol ether have been added) to form a polyester powder. Create a suspension with a concentration of 30%.

The above suspension was applied to one of two sheets of nonwoven fabric (polyester nonwoven fabric with a weight of 90g/thickness of 190mm) in the form of a band (0.
3 mid-rib), overlay the other non-woven fabric on top of this,
190q0, 30k9/Glue by heating and pressurizing between 1/50 sand underground. The peel strength of the adhesive nonwoven fabric obtained is 2
It was more than 2 females/skin. However, this is 2 with 150q○
When it was left in an oven for an hour (heat resistance test), all the adhesive parts came off due to natural peeling. (→Comparative example). On the other hand, 20
% concentration of colloidal silica, an equal weight of emulsifier-containing water, which is the dispersed soot of the above suspension, is added and mixed, and then the above polyester powder is mixed and dispersed therein to obtain a colloidal solution of the polyester powder concentration of 30% (the present invention). adhesive).

As a result of bonding using this colloidal solution under the same conditions as above, the peel strength of the bonded nonwoven fabric was 22 female/female or more, which was the same peel strength as when silica was not mixed. Moreover, we conducted a heat resistance test under the same conditions as above, but
No natural peeling was observed. Example 2 Chloroprene-based synthetic rubber solvent-based adhesive (viscosity 2000~
250 ratio ps) to a polyester non-woven fabric with a basis weight of 90 g/thickness of 190 m, in the form of a belt (0.3 side medium) with a film thickness of 15~
When applied at a thickness of 25 m, another sheet of the same nonwoven fabric is layered on top of this, and the peel strength of the bonded nonwoven fabric is 30 to 40 g. A substance as thick as skin was obtained.

However, when this was subjected to a heat resistance test under the same conditions as in Example 1, although no natural peeling occurred, the peel strength had decreased to such an extent that it could not be measured. (→Comparative example). On the other hand, the polyester powder of Example 1 is mixed and dispersed in water with a 10% suspension of bentonite or kaolin to prepare a suspension (adhesive of the present invention) having a concentration of the polyester powder of 30%.

Claims (1)

[Scope of Claims] 1. Consisting of a hot melt resin powder and at least one inorganic powder selected from bentonite, kaolin, and silica dispersed in water in an amount of 50 to 100% by weight based on the hot melt resin powder. A hot melt organic-inorganic mixed adhesive characterized by: 2. The adhesive according to item 1 above, which is used for nonwoven fabrics.