JPS5898372A - Adhesive for tennis ball melton dumbbell - Google Patents

Abstract

PURPOSE:To provide the titled adhesive excellent in workability and shelf stability, prepared by adding a high-temperature decomposing vulcanizing agent and a heat-resistant gelling agent to rubber latex. CONSTITUTION:The adhesive is prepared by adding (B) high-temperature decomposing vulcanizing agent (decomposing at around 60-160 deg.C, e.g. 4, 4-dithiodimorpholine) and (C) heat-sensitive gelling agent (gelling at 60 deg.C or lower, e.g. polysiloxane with polyvinyl methyl ether functional group) to (A) rubber latex (having adhesive strength of about 15-200g/cm when measured by cellophane adhesive tape test, etc. and a viscosity of about 3,000-7,000cP at 20 deg.C). (B) and (C) are added in about 2-10 and about 3-15wt%, respectively based on the total solids. A pack of tennis ball melton dumbbells is dipped in the adhesive and dried at around 60 deg.C or lower. The dumbbells are peeled off and are attached to ball core, followed by vulcanization and bonding under heat.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive suitable for adhering melton dumbbells of tennis balls.

Tennis balls are manufactured by bonding flat Melton dumbbells to a spherical core ball. To apply the adhesive to the melton dumbbells, as shown in Figure 1, layer multiple melton dumbbells (1), and apply the adhesive to the end plate (2).
This is done by dipping the Melton pack (8) sandwiched between the two into the adhesive, and after drying, removing the end plate and peeling off the Melton dumbbells one by one.

As for the above adhesive for Melton dumbbells, (1)
After the adhesive has dried, the Melton dumbbells are peeled off one by one from the Melton pack, and (2) the adhesive is firmly attached to the sides of the Melton dumbbells that have been peeled off.
(3) Various properties are required, such as having an appropriate initial surface adhesive force for bonding a flat Melton dumbbell to a spherical core ball. In order to satisfy requirements (1) and (2), the internal cohesive force of the adhesive itself must be weakened to an extent that does not impair adhesive performance.

Therefore, conventional adhesives for melton dumbbells are made by dissolving natural rubber, synthetic rubber, etc. in an organic solvent such as naphtha, which has undergone excessive molecular scission by repeatedly kneading it in a kneading roll machine etc. for a long time. Solvent-based adhesives containing vulcanizing agents, vulcanization accelerators, vulcanization accelerators, anti-aging agents, fillers, etc. are used.

However, since this solvent-based adhesive exhibits Newtonian viscosity as its flow characteristic, it sag during drying and the amount of adhesive adhered to the top and bottom of the melton pack is different, and the viscosity is high compared to the concentration. The amount of adhesive deposited by one immersion is small, and therefore the melton bag must be dipped multiple times, at least twice, and each time the melton bag must be turned upside down and dried.

There have been proposals to use latex adhesives to improve the above-mentioned drawbacks of solvent-based adhesives, but latex adhesives usually undergo pre-vulcanization during storage and their initial adhesive strength decreases over time. Internal cohesion tends to increase (ie, pot life becomes shorter). Further, the dispersion medium of such latex adhesives is usually water, which has the disadvantage that it dries and separates, and that a thin film is formed on the surface in the early stage of drying, further reducing the drying rate.

The present invention is intended to improve the above-mentioned drawbacks of conventional meleton dumbbell adhesives.

That is, the present invention provides a tennis pole, melton, and dumbbell adhesive, which is a rubber latex compounded with a temperature-decomposable vulcanizing agent and a heat-sensitive gelling agent.

The rubber latex used in the present invention generally has a weak internal cohesive force and preferably has a high surface adhesive force. Such adhesive components include natural and/or synthetic rubbers such as polyisoprene, polybutadiene, polychloroprene, nitrile rubber, styrene-butadiene copolymers, acrylonitrile-butadiene-styrene copolymers,
Or a mixture of these, or a depolymerization treatment of them,
For example, by heating in the coexistence of a peroxide or an azo compound, by a radical reaction using a redox initiator containing a persulfate as one component, or by irradiation with radiation such as X-rays, α-rays, β-rays, and γ-rays. can get.

Particularly preferred rubbers are natural rubber, synthetic polyimprene rubber latex, or depolymerized products thereof.

Although the above rubber latex is not particularly limited, it is usually J
For example, the adhesive strength according to IS-Z-1522 (cellophane adhesive tape test) and JIS-Z-1528 (both figures adhesive tape test) is 15 to 20 in the case of natural rubber latex.
01/ctn especially 20-180 g/crr+(25°
C) is preferred and generally has an adhesive strength of 299/”c
If it is less than m, the initial adhesive force required for the adhesive will be too small and the internal cohesive force will be too large, and if it is more than 1B0f/cm, the surface adhesive force will be too large, making work such as bonding difficult.

Various conventional additives are appropriately blended into the rubber latex thus prepared.

Such additives include tackifiers such as QE65.
03B (Nippon Zeon Co., Ltd. commercial product), Claprene LIR-7
00 (commercial product from Kurarain Prene Chemical Co., Ltd.), vulcanizing agent (
sulfur), vulcanization accelerators such as 2-mercaptobenzothiazole zinc salt, zinc diethyldithiocarbamate, vulcanization accelerators such as lead oxide, stearic acid, oleic acid, triethanolamine, fillers such as carbonic acid Calcium, kaolin, clay, barium sulfate, anti-aging agent,
For example, 2,2'-methylenebis(4-methyl-6-(-
butylphenol), 2,2'-methylenebis(4-ethyl-6-(-butylphenol), increase@! JIL e.g. force! levoxymethyl cellulose, methyl cellulose,
Examples include hydroxypropyl methylcellulose, polyvinyl alcohol, and polyethylene oxide.

The total amount of these additives is usually 20 to 60 parts by dry weight per 100 parts by dry weight of the rubber component.

The viscosity of the adhesive prepared as described above is usually 300.
0~70000 CPS (20℃) CBM type viscometer &
40-tar:12 or 6r, p, m,] is preferably adjusted.

The adhesive according to the present invention exhibits chicken-tropic properties as its fluidity properties [Fig. 1 (1) to (3)], and its solid content is also higher than that of conventional solvent adhesives (usually 35 to 70% solids). )
Therefore, even with a single dip coating process, any amount of adhesive can be uniformly deposited on a predetermined area such as the seam of the melton, and since the zero shear viscosity is high, the adhesive will not flow downward when left to dry. There is little dripping and the amount of application between the top and bottom can be kept uniform.

The vulcanizing agent used in the present invention is a high temperature decomposition type.

Preferred vulcanizing agents are disulfide-based high-temperature decomposition compounds, such as morpholine disulfide (4,4'-dithiodimorpholine), alkylphenol disulfide, methoxyphenyl disulfide, ethoxyphenyl disulfide, hydroxybenzyl disulfide, etc., especially those with a decomposition temperature of 60 to 160 ℃ is preferred. If the decomposition temperature is too low, it may decompose during storage and cause the rubber components in the adhesive to vulcanize and coagulate; if it is too high, the temperature should be lowered when bonding the melton dumbbell to the ball.

The amount of the high-temperature decomposition type vulcanizing agent added is 2 to 10% by weight, preferably 3 to 8% by weight, based on the total solid content.

The heat-sensitive gelling agent used in the present invention is preferably a substance that causes fusion of latex particles by heating, and specific examples thereof include polysiloxane having a polyvinyl methyl ether functional group, which has a heat-sensitive gelling temperature. is preferably higher than the decomposition temperature of the high-temperature decomposition type vulcanizing agent.

When such a heat-sensitive gelling agent is used, the latex particles are fused and gelled at a temperature below the decomposition temperature of the sieve temperature decomposition type vulcanizing agent and above the heat-sensitive gelling temperature of the heat-sensitive gelling agent, and moisture etc. Not only does it precipitate on the coated surface, making it easier to dry, but
It is possible to blow hot air at a temperature below the decomposition temperature of the high-temperature decomposition type vulcanizing agent, and the adhesive can be dried more quickly.

The amount of heat-sensitive gelling agent added is 3 to 15% by weight of the total solid content,
Preferably it is 5 to 12% by weight.

A melton bag is immersed in the adhesive thus obtained and dried by heating at a temperature below about 60°C. After sufficiently drying the Melton pack, the Melton dumbbells are peeled off one by one and bonded to the core pole, which is then heated to a temperature higher than the decomposition temperature of the vulcanizing agent to vulcanize and bond.

It goes without saying that the adhesive of the present invention may contain components other than those mentioned above, such as fillers, surfactants, viscosity modifiers, etc.

By the method of the present invention, the concentration of the adhesive can be easily controlled, a highly concentrated adhesive can be obtained, and sufficient and uniform adhesive adhesion can be achieved with a single dipping.

Further, vulcanization does not occur during heating and drying, so the above-mentioned troubles due to internal aggregation do not occur, and the adhesive itself gels when heated and dries easily because water is expelled. Furthermore, the adhesive of the present invention has many advantages such as good storage stability and long pot life.

The present invention will be explained below with reference to Examples. In the examples, parts and percentages are expressed by weight unless otherwise specified.

Example 1.2 and Comparative Example 1.2 Tennis pole melton dumbbell adhesives were blended according to the formulations shown in Table 1. 1. Apply the latex adhesive onto the polyester film. Apply it on a thick layer of Ol and immediately apply 5
It was heated at 0°C for 1 minute and then dried with air at 35°C. The water content of the coated latex layer was measured over time, and the results are shown in FIG. In FIG. 2, curve (4) is the moisture content curve of Examples 1 and 2, and curve (5) is the moisture content curve of Comparative Examples 1 and 2.

Further, the above adhesive (within 12 hours of blending) was applied onto a polyester film (nominal thickness No. 25 specified in JIS C2818 (11i polyester film)) to a thickness of 20 to 25 μm, and the above-mentioned drying process was performed. While drying in the same manner as in the test, the adhesive strength was measured in accordance with JIS-Z-1522 (cellophane adhesive tape test) and JIS-Z-1528 (double-sided adhesive tape test). The results are shown in Figure 3. In the figure, curve (6) shows changes in adhesive strength over time in Example 1 and Comparative Example 1, curve (7) in Example 2, and curve (8) in Comparative Example 2. That is, it is shown that when morpholine disulfide, which is a high-temperature decomposition type vulcanizing agent, is used, no decrease in adhesive strength is observed over time.

Furthermore, the latex adhesives of Example 1 and Comparative Example 2 were stored at room temperature and the changes in adhesive strength over time were investigated.
It was fixed at 1. The results are shown in Figure 4. In the diagram, song #1lf9)
shows the results of Example 1, and curve (10) shows the results of Comparative Example 2. This result shows that the pot life of the rubber latex adhesive is significantly extended by using a degradable vulcanizing agent.

[Brief explanation of the drawing]

Figure 1 shows a Melton bag stacked with Melton dumbbells sandwiched between end plates, Figure 2 shows changes in the moisture content of applied latex over time, and Figure 8 shows the relationship between adhesive strength and drying time. FIG. 4 is a graph showing the relationship between the adhesive strength of the adhesive and the number of storage days. In the figure, m is a Melton dumbbell, (2) is an end plate, (3) is a Melton bag, and (4) is Examples 1 and 2.
, (5) is Comparative Examples 1 and 2, (6) is Example 1, Comparative Example 1, (7) is Example 2, (8) is Comparative Example 2, (9) is Example 1, (lO) shows the results of Comparative Example 2, respectively.

Claims (1)

[Claims] ■. An adhesive for tennis poles and dumbbells, which is made of rubber latex mixed with a high-temperature decomposition type vulcanizing agent and an age-sensitive gelling agent. 2. The adhesive according to item 1, wherein the high-temperature decomposition type vulcanizing agent is a disulfide compound having a decomposition temperature of 60 to 160°C. 3. The adhesive according to item 1, wherein the heat-sensitive gelling agent is a polysiloxane having a polyvinyl methyl ether functional group. 4. Heat-sensitive gelling agent gels rubber latex at 60°C
2. The adhesive according to claim 1, which is capable of forming at a lower temperature. 5. The first rubber latex is natural rubber, synthetic polyisoprene rubber, or a latex of a depolymerized product thereof.
Adhesives listed in section.