JPS5811908B2 - Polyvinyl alcohol resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyvinyl alcohol adhesive compositions.

Recently, attention has been paid to the water solubility and thermoplasticity properties of polyvinyl alcohol, and attempts have been made to use polyvinyl alcohol as a basis for rewetting type or water dispersion type hot melt adhesives.

However, when polyvinyl alcohol is used as the basis for a hot-melt adhesive, polyvinyl alcohol itself has properties such as high melt viscosity, hardness, and brittleness. , polyhydric alcohols such as pentaerythritol, glycols such as ethylene glycol, diethylene glycol, trimethylene glycol, polyethylene glycol, urea, urea compounds such as ethylene urea, etc. are used as softeners for polyvinyl alcohol. .

In order to further improve the adhesive properties of hot-melt adhesives, it is preferable to incorporate adhesion-imparting agents. Rosins such as saturated hydrocarbons, rosin, hydrogenated rosin, polymerized rosin, disproportionated rosin, esterified products of these rosins with glycerin, methyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, etc., α or β
Pinene polymers, turpentine oil polymers, triterpene resins, terpene phenol resins, rosin-modified phenol resins, phenol resins, xylene resins, coumaroindene resins, styrene resins, etc. have poor compatibility with polyvinyl alcohol, so polyvinyl alcohol compositions Even if it is blended into a product, it is difficult to be miscible with the product, and the adhesion imparting effect cannot be predicted, and instead, the adhesive property tends to decrease.

The present invention has been made based on various studies aimed at obtaining an adhesion promoter suitable for polyvinyl alcohol compositions. As a result, thermoplastic resins produced by the reaction of rosins and pentavalent or hexavalent alcohols are compatible with polyvinyl alcohol. , which was discovered to be suitable as an adhesion-imparting agent.

That is, the present invention uses polyvinyl alcohol as a base,
The present invention relates to a polyvinyl alcohol adhesive composition characterized in that it contains a thermoplastic resin produced by a reaction between a rosin and a pentavalent or hexavalent alcohol.

The polyvinyl alcohol used in the present invention is generally a substance obtained by hydrolyzing polyvinyl acetate, and preferably has a degree of polymerization of 500 or less and a degree of saponification of 50 to 95 mol%.

Next, rosins include what is generally called rosin, hydrogenated rosin, polymerized rosin, and disproportionated rosin, and all of these rosins have carboxyl groups in their molecules. It has the property of reacting with alcohol to form an ester.

Next, examples of the pentahydric alcohol in the present invention include arabite, xylit, attonite, etc., and examples of the hexavalent alcohol include mannitol, sorbitol, dalgit, etc.

In the present invention, a thermoplastic resin obtained by esterifying the rosin and the pentavalent or hexavalent alcohol is used.

Incidentally, the above esterification reaction may be carried out according to a conventional method for producing rosin ester.

In the above reaction product, the number of ester groups produced differs depending on the number of hydroxyl groups in the alcohol molecules participating in the reaction, but in the present invention, any esterified product can be used, and in particular, Monoesters, diesters and triesters are preferred, and it is also possible to use a mixture of pentahydric alcohols and hexahydric alcohols as the alcohol to be reacted with the rosin in the above esterification reaction.

Therefore, the present invention uses the above-mentioned polyvinyl alcohol as a base material, and a thermoplastic resin produced by the reaction of the above-mentioned rosin and a pentavalent or hexavalent alcohol is added and mixed therein. The amount of plastic resin used is 30 to 100 parts by weight of polyvinyl alcohol.
Preferably, 150 parts by weight are used.

In addition, in order to mix the above-mentioned two, a method used for manufacturing a hot-melt adhesive may be adopted, such as adding the two together, heating and melting, and mixing to form a uniform composition.

In addition, in the present invention, softeners for polyvinyl alcohol, such as polyhedral alcohols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, and mannitol, and modified products thereof; ethylene glycol, diethylene glycol, triethylene glycol,
Glycols such as trimethylene glycol and polyethylene glycol and their modified products; urea, urea derivatives such as ethylene urea and propylene urea, etc. may be used, and other fillers and colorants that are usually used in hot melt adhesives may also be used. May be added.

As described above, the thermoplastic resin produced by the reaction of the rosin and the pentavalent or hexavalent alcohol used in the polyvinyl alcohol adhesive composition of the present invention differs from conventional adhesion promoters in that the thermoplastic resin used in the polyvinyl alcohol adhesive composition of the present invention The polyvinyl alcohol adhesive composition of the present invention containing the above-mentioned thermoplastic resin has good adhesion because it is highly compatible with alcohol and has an adhesive effect on polyvinyl alcohol. It has excellent adhesive properties, especially at high temperatures and high humidity, and is suitable for use as a hot-melt adhesive.

Examples of the present invention will be described below.

Note that parts below mean parts by weight.

Example 1 17 ingredients shown in Table 1 as Example 1 and Comparative Example 1
The mixtures were melt-mixed at 0° C. to obtain transparent blends with good compatibility.

When the adhesive strength was measured using these blends, the results shown in Table 2 were obtained.

Examples 2 and 3 Each of the components shown as Examples 2 and 3 in Table 2 was 17
A composition with good compatibility was obtained by melt-mixing at 0°C.

When the compositions of Examples 2 and 3 were used to stiffen the back of a book and their adhesive properties were examined, they both showed good not only normal but also good cold- and heat-resistant adhesive properties.

On the other hand, when the components shown as Comparative Examples 2 and 3 in Table 2 were melt-mixed at 170°C, the compatibility was poor and a uniform composition could not be obtained.

For this reason, even when bookbinding was performed using the compositions of Comparative Examples 2 and 3, adhesion failures normally occurred.

Examples 4 and 5 The ingredients shown in Table 3 as Examples 4 and 5 were
A composition with good compatibility was obtained by melt-mixing at .degree.

When book binding was performed using the compositions of Examples 4 and 5 and the adhesion was examined, both were found to have good adhesion in normal conditions as well as in cold and heat resistance.

In addition, the book obtained by back-hardening was left in a high temperature and high humidity environment at 50°C and 90% (relative humidity) for 4 days, and then the adhesive strength was measured in the same temperature atmosphere immediately after taking it out.
cm (material failure).

Claims (1)

[Claims] 1. A polyvinyl alcohol adhesive composition comprising polyvinyl alcohol as a base and containing a thermoplastic resin produced by a reaction between a rosin and a pentavalent or hexavalent alcohol.