JPH0236395B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a rubber material having a display pattern used for binding materials, packaging materials, protective materials, etc. [Prior Art] Sheets, tubes,
Rubber materials such as rubber bands are known. A method for manufacturing a rubber material having such a display pattern includes printing the surface of the rubber material using a common printing ink used for printing paper or synthetic resin film. There is also a method in which a solvent that can penetrate well into the rubber material, such as a solvent that is highly compatible with rubber, is used as the solvent for the printing ink used in the above-described printing method, and printing is performed using such a printing ink. Another method is to print an unvulcanized rubber film that can be vulcanized by screen printing using rubber-based printing ink, and then attach this rubber film to the unvulcanized rubber material on which the display pattern is to be formed. There is a method in which a rubber film having an attached display pattern is also vulcanized at the same time as the rubber material is vulcanized, and the rubber film is vulcanized and adhered onto the rubber material. [Problems to be Solved by the Invention] In the case of a rubber material in which a display pattern is formed by printing using the above-mentioned first ordinary printing ink, the rubber material is subject to repeated expansion and contraction, as well as repeated expansion and contraction under stretching. The disadvantage is that the display pattern easily peels off due to contact or abrasion of the printed surface with other objects. The biggest reason for this is that in the printing method using ordinary printing ink (which mainly uses pigments as colorants), the ink simply adheres to the surface of the rubber material and does not penetrate into the rubber material at all. This is because the adhesion of the display pattern to the rubber material is poor, and the elongation of the printed display pattern does not follow the large elongation rate of the rubber material, resulting in tearing. In addition, a printing method using a printing ink that uses a solvent with good compatibility with rubber as the solvent of the second printing ink was proposed as an improvement to the printing method using the above-mentioned ordinary printing ink, but in this case, In extreme cases, the coloring agent dissolved in the solvent does not stay on the surface of the rubber material with the solvent, but permeates into the rubber material indefinitely as long as the solvent is present, resulting in the display pattern blurring and becoming unclear. In some cases, it may become impossible to even distinguish the display pattern.
Furthermore, when such a solvent is used, the rubber material itself is swollen, which makes the displayed pattern unclear and has the serious drawback that it may also impair the physical properties inherent in the rubber material. For this reason, it has the disadvantage of not being able to supply stable products. In addition, the third method of using an unvulcanized rubber film requires that the rubber material on which the display pattern is to be formed be in an unvulcanized or semi-vulcanized state, and already vulcanized rubber materials cannot be used. . Furthermore, since the rubber material is in an unvulcanized or semi-vulcanized state, the attached rubber film and the rubber material change in shape during vulcanization, which has the disadvantage that the displayed pattern tends to become unclear. In addition, since the printed rubber film also contains a vulcanizing agent, when stored for a long time, vulcanization may progress during storage and vulcanization adhesion with the rubber material may become impossible. has. Also, this method has very poor workability;
Higher costs are unavoidable. Therefore, an object of the present invention is to provide a display pattern that does not peel off due to expansion and contraction of the rubber material or abrasion under stretching, does not cause blurring of the display pattern, can be easily formed with good workability, and does not undergo deterioration during storage. It is an object of the present invention to provide a method for manufacturing a rubber material having a display pattern that is unique to the user. [Means for Solving the Problems] The present invention resides in a rubber material having a display pattern in which the display pattern is permeated and fixed to the surface of the rubber material, and a method for producing the same. The above manufacturing method involves dissolving thermoplastic rubber and/or thermoplastic resin as a film-forming material in cyclohexanone, and using an ink in which dyes and pigments are dissolved or dispersed in this solution, a pattern is displayed on the surface of the rubber material. Print, dry if necessary,
It consists of heat treating the printed rubber material and then hot water treatment. The printing ink used in the present invention uses cyclohexanone as a solvent, in which thermoplastic rubber and/or thermoplastic resin as a film-forming material is dissolved, and in this, dyes and pigments as colorants are further dissolved or dispersed. This is what I did. Incidentally, a surfactant may be added to the printing ink as an auxiliary agent, if necessary, in order to enhance adhesion to and penetration into the surface of the rubber material. The thermoplastic rubber and thermoplastic resin used in the printing ink of the present invention adhere well to the rubber material that is the printing material, and the heat treatment temperature described below is, for example, 80 to 80°C.
It softens at a temperature of 150℃ and hot water treatment temperature, for example, at a temperature of 80℃ or higher, is soluble in the solvent cyclohexanone, and has an elongation rate that can follow the elongation of the rubber material when a film is formed on the surface of the rubber material. death,
It is necessary to have durability against friction. Such thermoplastic rubber materials are preferably styrene-butadiene-styrene (SBS) block copolymers and styrene-isoprene-styrene (SIS) block copolymers, and the thermoplastic resin is preferably polystyrene resin. The above-mentioned thermoplastic rubber and thermoplastic resin may be used individually or in the form of a mixture. These thermoplastic rubbers and thermoplastic resins are appropriately selected depending on the hardness and elongation of the rubber material to be printed. Generally, when the hardness of the rubber material is low and the elongation is high, thermoplastic rubber or a mixture with a thermoplastic resin containing a large amount of thermoplastic rubber is used. In this case, it is preferable to use a thermoplastic resin or a mixture with a thermoplastic rubber containing a large amount of thermoplastic resin. Pigments and dyes are used in combination as colorants for the printing ink used in the present invention. As these dyes and pigments, dyes and pigments conventionally used in printing inks used for printing rubber materials can be used. The mixing ratio of dye and pigment is preferably 10:90 to 40:60 by weight in relation to the hot water treatment described below. If the mixing ratio of the dye is greater than 40, when the dye permeates from the surface of the rubber material together with water during hot water treatment, it will also dissolve into the hot water and flow out, causing areas other than the display pattern to disappear again. This is not preferable because there is a risk that it may also color the material. Furthermore, if the mixing ratio of the dye is less than 10, the amount of penetration from the rubber surface into the interior during hot water treatment will be reduced, making it insufficient to clearly fix the display pattern, which is not preferable. Note that if the wetting effect of the printing ink on the surface of the rubber material is small and the penetrating effect of the colorant is small, a small amount of surfactant may be mixed into the printing ink. The solvent used in the printing ink used in the present invention is preferably a solvent with relatively low volatility.
When using a highly volatile solvent that evaporates quickly, when the surface of a rubber material is printed with printing ink using such a solvent, the solvent evaporates and dries before the surface of the rubber material is sufficiently wetted. As a result, the penetration and fixation of the colorant from the rubber surface to the inside and the fixation of the film-forming material to the rubber material surface are extremely deteriorated, and as a result, during the next heat treatment and hot water treatment described later. It may come off due to vibration, contact with other objects, etc. Furthermore, if a solvent with very low volatility, that is, a very slow volatilization rate, is used, the solvent, along with some of the coloring agent contained therein, may penetrate too deeply from the surface of the rubber material into the interior and diffuse. As a result, the display pattern becomes blurred and unclear. Therefore, in the printing ink used in the present invention, the colorant does not diffuse inside the rubber material and make the display pattern unclear, and the colorant and film-forming agent can properly penetrate from the surface of the rubber material into the inside. , and found that cyclohexanone is suitable as a solvent capable of fixing. The printing ink used in the method of the present invention has a solid content in the range of about 20 to 60% by weight, and preferably 30 to 50% by weight. The rubber material used in the present invention may be any rubber material conventionally used for binding materials, packaging materials, protective materials, etc., and its form may be any shape such as sheet, tube, or ring. can. When printing the display pattern on the surface of the rubber material with the printing ink described above, any conventional printing method such as transfer printing, gravure printing, flexo printing, etc. can be used. In the method of the present invention, the above-described printing ink is used to print a desired display pattern on the surface of a rubber material, and after drying, heat treatment is performed, and then hot water treatment is performed. The above heat treatment is preferably carried out at a temperature of 80°C to 150°C. In addition, temperatures above 80°C and up to the boiling point can be used for hydrothermal treatment. If the above heat treatment is performed at a low temperature of less than 80°C, the thermoplastic rubber and/or
Or the softening and flow of the thermoplastic resin is insufficient,
The adhesion to the surface of these rubber materials may become insufficient or incomplete, which is undesirable. Also
If the temperature exceeds 150°C, there is a risk that the rubber material itself, which is the printing material, may change in quality or change in color. Regarding the time, at 80℃, about 1 hour is appropriate.
Around 150℃, about 5 minutes is sufficient. The above-mentioned hot water treatment is carried out in order to allow the dye in the coloring agent to properly penetrate into the rubber material from the surface thereof. At this time, the penetration is preferably about 30μ.
If it penetrates deeper than this, the display pattern will blur,
This is not preferable as it may cause blurring. Therefore, if the hot water treatment is carried out at a temperature below 80°C, the penetration of the dye in the coloring agent into the rubber material from the fixed film forming material will be insufficient, which is undesirable, and the film forming material will not stick to the surface of the rubber material. This is not preferable as it may cause a decrease in In addition, the hot water treatment time is 20~20℃ at 80℃.
For 30 minutes, 5 to 10 minutes at 90°C is appropriate, and longer time will not have any negative effect on quality, but no penetration effect can be expected. For example, an air circulation heater,
Conventional heating devices such as electric heaters and infrared heaters can be used. Further, for the hot water treatment, ordinary hot water treatment equipment such as an immersion type hot water bath or a shower type hot water bath can be used. According to the method of the present invention, after forming a display pattern on a sheet-like, tube-like, or ring-like rubber material as described above, these can be changed into a desired size and shape by cutting as appropriate in post-processing. .
For example, a tube-like rubber material may be formed with a display pattern and then cut into rubber bands, or a sheet-like material may be cut into strips. [Operation] In the method of the present invention, when a display pattern is printed on the surface of a rubber material with the printing ink of the present invention,
Before the cyclohexanone is evaporated and removed, a portion of the rubber material penetrates into the interior from the surface of the rubber material, and at this time, the coloring agent having a small particle size, mainly the dye, settles and adheres near the surface of the rubber material together with the cyclohexanone.
On the other hand, the remaining colorant and film-forming material are integrally fixed to the surface of the rubber material. However, due to the evaporation of cyclohexanone at this time, the fixed display pattern is in a relatively sparse density state, and the degree of adhesion of the display pattern to the rubber material surface at this time is very weak, and due to the expansion and contraction of the rubber material, Otherwise, it is only to the extent that it easily peels off when it comes into contact with other objects. According to the present invention, the temperature is then increased to 80 to 150°C as described above.
At this time, the film-forming material in the display pattern that has been fixed by the above printing becomes soft and fluid, and the film-forming material and coloring agent become dense within the display pattern, and the surface of the rubber material softens and becomes fluid. It flows into the recesses that may exist in the surface of the rubber material and improves the adhesion of the display pattern to the surface of the rubber material. According to the present invention, following the above-mentioned heat treatment, 80°C
The hot water treatment is carried out as described above, and at this time the hot water penetrates into the fixed display pattern and further penetrates into the inside of the rubber material from the surface. At this time, mainly the water-soluble dye permeates into the interior of the rubber material from the surface of the rubber material together with water and precipitates into the rubber material. Following this, the pigment and film-forming material are densely aggregated and fixed on the surface of the rubber material. At this time, the water absorption effect of the rubber material is small unlike the absorption effect of solvents, so even if the dye permeates into the rubber material together with water, the display pattern will not smear or become unclear. Furthermore, the film-forming material becomes denser due to this hot water treatment and firmly adheres to the surface of the rubber material, so it is extremely robust against the expansion and contraction of the rubber and will not peel off. It has been found that this hot water treatment generally allows the dye to penetrate up to about 30μ from the surface of the rubber material. If hot water treatment is performed immediately after printing without the heat treatment described above, the adhesion of the film-forming material to the rubber surface will be weak, and the film-forming material will also have a sparse density, so colorants, especially dyes, will not be absorbed in the hot water. These may color the non-display pattern portions on the surface of the rubber material, or the film-forming material containing the colorant may fall off. [Example] The present invention will be described below with reference to Examples. Parts are parts by weight. Example 1 Printing was carried out on the outer peripheral surface of a tube-shaped rubber material having a wall thickness of 1 mm, a length of 2 m, and a folded diameter of 5 cm using a gravure printing machine as shown in FIG. 1 using a printing ink having the following composition. Composition of printing ink Pigment Carbon black 12 parts Black metal dye 3 Polystyrene resin 20 Gilsonite 3 Paraffin wax 2 Cyclohexanone 60 Total 100 After printing, dry at room temperature, then heat at 120℃ for 5 minutes with an air circulation heater heat treated in
A rubber material having a display pattern as shown in FIG. 1 was obtained by hot water treatment in a minute-long immersion bath. In this product, the dye in the display pattern part penetrated up to 20μ into the rubber material, and a film having a display pattern with a thickness of 10μ was formed on the rubber material. The tube-shaped rubber material obtained as described above and having the display pattern shown in Fig. 1 was cut into rounds of 10 mm in width, and the obtained rubber bands as shown in Fig. 2 were subjected to a friction test on the display pattern surface under the following conditions. I did it. Conditions Rubber band elongation: 100% Friction surface: Gauze (type 1) Number of times of friction: 200 The results are shown as A in Table 1 below. Table 1 also shows the results of the same test for a similar rubber band printed only with commercially available printing ink as B.

[Table] As is clear from Table 1, the display pattern of the rubber material formed according to the present invention does not peel off and has good abrasion resistance. Example 2 A display pattern as shown in FIG. 2 was printed on the outer peripheral surface of a rubber band having a wall thickness of 1 mm, a width of 10 mm, and a folded diameter of 5 cm using a printing ink having the following composition by flexographic printing. Composition of printing ink Pigment Carbon black 12 parts Black metal dye 3〃 SBS 10〃 Polystyrene resin 10〃 Gilsonite 3〃 Parafine wax 2〃 Cyclohexanone 60〃Total 100〃 Immediately after printing, heat at 120℃ for 15 minutes in an air circulation heater The rubber band C was then treated with hot water at 95° C. for 15 minutes in an immersion bath to obtain a rubber band C having a display pattern as shown in FIG. In this product, the dye of the display pattern penetrated up to 5μ into the rubber material, and a film having a display pattern with a thickness of 10μ was formed on the rubber material. This rubber band was subjected to a friction test in the same manner as in Example 1. The results are shown in Table 2.

〔Effect of the invention〕

The rubber material obtained by the present invention has an excellent effect that the display pattern does not peel off or become unclear due to wear, even if it is stretched during use or subjected to friction with other objects, for example.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of a rubber material having a display pattern obtained according to the present invention;
The figure is a perspective view of a rubber band.

Claims (1)

[Claims] 1. Thermoplastic rubber and/or thermoplastic resin as a film-forming material are dissolved in cyclohexanone, and an ink in which dyes and pigments are dissolved or dispersed in this solution is used to coat the surface of a rubber material. A method for producing a rubber material having a display pattern, which comprises printing a display pattern, heat-treating the printed rubber material, and then subjecting it to hot water treatment. 2. The manufacturing method according to claim 1, wherein the rubber material is sheet-shaped, tube-shaped, or ring-shaped. 3. The manufacturing method according to claim 1 or 2, wherein the thermoplastic rubber is a styrene-butadiene-styrene (SBS) block copolymer or a styrene-isoprene-styrene (SIS) block copolymer. 4. The manufacturing method according to claim 1 or 2, wherein the thermoplastic resin is a polystyrene resin. 5. The manufacturing method according to any one of claims 1 to 4, wherein the heat treatment is performed at a temperature of 80 to 150°C. 6. The manufacturing method according to any one of claims 1 to 4, wherein the hot water treatment is carried out in hot water at 80°C or higher.