JPS6312107B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesive composition that has improved initial adhesion, low-temperature film forming properties, and adhesive strength of a synthetic resin emulsion adhesive. In general, problems in using emulsion adhesives include poor initial adhesion and a trade-off between low-temperature film-forming properties and adhesive strength. Initial adhesion is the force that holds the adherends in place after they are pasted together until the adhesive dries and solidifies, and is an important property that is a prerequisite for the completion of adhesion. If this initial adhesion is low, adhesion failures such as peeling and shifting often occur. In addition, the minimum film-forming temperature is the lowest temperature at which the emulsion can be applied to form a continuous film while the particles are fused.It is important to note that when using emulsions for adhesives, paints, etc. Not only can it be used alone, but it is of no use unless the individual emulsion particles fuse together to form a continuous film during the process of water evaporation. For example, very hard particles do not stick together even if they come into contact one by one, much less a fusion phenomenon occurs, and after the water evaporates, only a white lump remains and falls off. Therefore, if it is used above this temperature, it can be formed into a film, and below this temperature, it cannot be formed into a film. Therefore, in order to compensate for the poor initial adhesion, modified rosin, modified rosin derivative, polyterpene resin, terpene-phenol resin, petroleum resin, alkylphenol-acetylene resin, xylene resin, coumaron indene resin, Additives such as alkylphenol-formaldehyde resin and plasticizers are used. However, the combined use of these additives can develop adhesive strength once the emulsion has dried, and its effect is hardly noticeable in undried or semi-dry conditions where a large amount of water is present. Can not. For example, dibutyl phthalate (hereinafter abbreviated as DBP) is commonly used as an adhesive with good initial adhesion.
A polyvinyl acetate emulsion containing the following is used. However, this material is not necessarily optimal in terms of wet adhesion. In addition, the amount of DBP added is about 10 to 20 PHR, and the difficulty is that the amount added is large. On the other hand, one of the important properties of emulsion is the above-mentioned minimum film forming temperature. This is particularly important when used as an adhesive, such as polyvinyl acetate emulsion, where the processing temperature is room temperature. The minimum film forming temperature of polyvinyl acetate emulsion is
Since the temperature is around 30°C, it is necessary to lower it further for applications that require film formation at room temperature. For this purpose, high-boiling point solvents such as carpitol acetate and cellosolve acetate, and plasticizers such as dioctyl phthalate (hereinafter abbreviated as DOP) and DBP are added as film-forming aids. By increasing the amount of these film forming aids added, it is possible to gradually lower the minimum film forming temperature of the emulsion adhesive, but on the other hand, as the amount added increases, the adhesive strength decreases. In addition to this, if the amount added is further increased, it becomes sticky and fails to form a film. As mentioned above, in order to lower the minimum film-forming temperature and improve the performance of emulsion adhesives, various additives are added depending on the purpose and method of use of the emulsion adhesive, but none are fully satisfactory. I can't say that. As a result of intensive research into these problems, the present inventors found that 2.2.4-trimethyl-3-hydroxypentyl isobutyrate (hereinafter referred to as
The present invention was completed based on the discovery that initial adhesion, low-temperature film forming properties, and adhesive strength can be improved by using TMHPIB (abbreviated as TMHPIB) as an additive. That is, the adhesive composition of the present invention is characterized by comprising a synthetic resin emulsion and 2.2.4-trimethyl-3-hydroxypentyl isobutyrate, and more specifically comprises a synthetic resin emulsion.
The amount of 2.2.4-trimethyl-3-hydroxypentyl isobutyrate is 20 parts by weight or less per 100 parts by weight. The synthetic resin emulsion used in the present invention includes vinyl acetate homopolymer, vinyl acetate polymer (vinyl acetate copolymer with acrylic acid ester, ethylene, maleic acid ester, vinyl chloride, tertiary carboxylic acid vinyl ester, propionic acid vinyl ester, etc.). Examples include all types of polymers such as acrylic acid ester polymers, vinyl chloride copolymers, vinylidene chloride copolymers, vinyl propionate polymers, styrene-butadiene, butadiene-acrylic esters, but especially vinyl acetate emulsions,
Acrylic emulsions and butadiene emulsions are suitable for the adhesive composition of the present invention. TMHPIB used in the present invention is represented by the following formula, and is produced by a method such as condensation of isobutyraldehyde. The adhesive composition of the present invention has the advantage that it uses TMHPIB, which is different from the conventionally widely used additive DBP, and that it can obtain the same initial adhesion and low-temperature film-forming properties with a smaller amount. In particular, when the amount added is 2 parts by weight or less per 100 parts by weight of the synthetic resin emulsion, the initial adhesion and adhesion strength are characterized by high values that cannot be obtained with conventional products.
Therefore, there are economic advantages as well. Also used
Since TMHPIB has a low boiling point, it has the advantage of rapid evaporation after film formation, and this is considered to provide excellent initial adhesion and adhesive strength even when used in small amounts. The adhesive composition of the present invention will be explained below using Examples and Comparative Examples. Tests in Examples and Comparative Examples were conducted in the following manner. Initial adhesion is determined by applying the adhesive composition to colored galvanized iron.
After coating at 30 g/m ² and laminating the cardboard and pasting the plasterboard, it was immediately peeled off and the area ratio (%) of the cardboard remaining after adhering to the colored galvanized iron was measured. For low-temperature film-forming properties, the adhesive composition was applied once to one side of a glass plate using an applicator with a gap of 4 mils, and the lowest film-forming temperature was observed using a test piece. The adhesion strength is as ^follows : 13 mm long,
Apply it at a rate of about 100g/ ^m2 to a width of 25mm and immediately apply 2
After weighing the two plates, a load of 2.0 kg/cm ² was applied and left for 24 hours. After removing the pressure, the test pieces were cured for 96 hours. The tensile shear force was measured using a Tensilon UTM-1 model) at a loading rate of 2.4 mm/min. The temperature during this test was maintained at 20±1° C. and humidity 50±3%. Example 1, Comparative Example 1 Butadiene (20 parts by weight), methacrylic acid (78 parts by weight)
An adhesive composition was prepared by adding TMHPIB to 100 parts by weight of a 40% emulsion of 2 parts by weight) and acrylic acid (2 parts by weight). As comparative examples, adhesive compositions were prepared in which TMHPIB was not added and DBP was added in place of TMHPIB. The test results of these initial adhesion properties (residual area ratio) are shown in Table 1. It can be seen that initial adhesion strength can be obtained with TMHPIB in a smaller amount than DBP.

[Table] * Comparative Example Example 2, Comparative Example 2 The 40% emulsion of Example 1 was mixed with butadiene (50%
(parts by weight) - 148 parts by weight of methacrylic acid) - acrylic acid (2 parts by weight), and the same procedure was repeated except for the following. The results are shown in Table 2. It can be seen that initial adhesion strength can be obtained with TMHPIB in a smaller amount than DBP.

[Table] * Comparative Example Example 3, Comparative Example 3 To 100 parts by weight of vinyl acetate homopolymer emulsion (Nicazole PL668 manufactured by Nippon Carbide Co., Ltd.)
A predetermined amount of TMHPIB was added and thoroughly stirred with a stirrer to prepare an adhesive composition. As a comparative example, when TMHPIB is not added and
Adhesive compositions were similarly made using DBP in place of TMHPIB. Table 3 shows the measurement results of the minimum film forming temperatures of these adhesive compositions. Particularly noteworthy are the
By adding a small amount of TMHPIB, the minimum film forming temperature is lower than that of general-purpose DBP.

[Table] Example 4, Comparative Example 4 Add TMHPIB to 100 parts by weight of styrene-butyl acrylate copolymer emulsion (resin content 45%)
was added in a predetermined amount and thoroughly stirred with a stirrer to prepare an adhesive composition. For comparison, the commonly used DBP is
An adhesive composition was prepared in the same manner except that TMHPIB was added in place of TMHPIB. Measure the tensile shear force of these adhesive compositions,
The relationship with the amount added is shown in Figure 1. Example 5, Comparative Example 5 Vinyl acetate homopolymer emulsion (resin content
50%), and the same procedure as in Example 4 and Comparative Example 4 was carried out in other respects. The results are shown in FIG. Example 6, Comparative Example 6 Vinyl acetate homopolymer emulsion (resin content
The same procedure as in Example 5 and Comparative Example 5 was carried out except that 45%) was used. The results are shown in FIG. What is particularly noteworthy about the results of Examples 4 to 6 and Comparative Examples 4 to 6 is that a large tensile shear force was exhibited when a small amount (2 PHR or less) of TMHPIB was added. This is currently considered the best additive when considering the minimum film forming temperature.
It requires a smaller amount to be added than DBP.

[Brief explanation of the drawing]

Figures 1, 2, and 3 show the relationship between the amounts of TMHPIB (a) and DBP (b) added and the tensile shear force.

Claims (1)

[Claims] 1. An adhesive composition comprising a synthetic resin emulsion and 2.2.4-trimethyl-3-hydroxypentyl isobutyrate. 2. The composition according to claim 1, comprising 100 parts by weight of a synthetic resin emulsion and 20 parts by weight or less of 2.2.4-trimethyl-3-hydroxypentyl isobutyrate. 3. The composition according to claim 2, wherein the amount of 2.2.4-trimethyl-3-hydroxypentyl isobutyrate is 0.1 to 2 parts by weight.