JP3138528B2 - Method of manufacturing polyurethane roller for printing press - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane roller for a printing press suitable for a setting roller or a kneading roller of an offset printing press or the like used for seal printing.

[0002]

2. Description of the Related Art Conventionally, a rubber roller having a metal core coated with rubber has been used as a setting roller and a kneading roller for an offset printing machine. This rubber roller has a problem that the ink is easily absorbed and discolored and deformed. Recently, polyurethane rollers formed by molding and bonding polyurethane to a metal core with a mold have been used. Its hardness (Shore A) is often 50 ° or 60 °. 2. Description of the Related Art In recent years, in order to automatically print a seal or a label at a high speed, a printing machine using a UV ink capable of promoting drying of the ink by irradiation of ultraviolet rays has been widely used. Particularly, in such printing, the polyurethane roller is deformed by the solvent of the UV ink, causing a problem. In particular, the roller may swell under the influence of the solvent of the ink, and for example, a roller having a diameter of 36 mm may become 37 to 38 mm. If so, the relationship between the plate cylinders and their rollers will be disrupted and the quality of the printing will be impaired, requiring delicate readjustment often. Therefore, a roller which is hardly affected by the solvent has been strongly demanded.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyurethane roller which has a lower hardness than conventional urethane rollers, improves printing performance, and is less susceptible to the influence of ink solvents. It is in.

[0004]

In order to achieve the above object, a method for producing a urethane roller according to the present invention comprises heating a polyester for polyurethane elastomer, injecting and stirring a plasticizer, and injecting a curing agent. A method for producing a polyurethane roller for a printing press, which is stirred, dewatered under reduced pressure, poured into a mold, heated and released after sulfurization, wherein the plasticizer includes diethyl phthalate, and the curing agent includes tolylene diisocyanate. It is configured.

[0005]

In the method of the present invention, a polyester for polyurethane elastomer is used as a main component, a plasticizer and a curing agent are added thereto, and a solvent-resistant roller for a printing press is provided by the following method. ○ Polyester for polyurethane elastomer 1 Properties of polyester Product name Polylite OD-X-2195 (Dainippon Ink) Applications Polyurethane elastomer type Saturated polyester structure containing a small amount of triol Succinic acid-mixed glycols Molecular weight About 2,200 Appearance Light yellow transparent viscous liquid OH value (mgKOH / g) 58-62 Acid value (mgKOH / g) 1.0max Water content (%) 0.030max Color number (Gardner) 2max Viscosity (CPS at 7 ° C) 2,500-4,000 ○ Plasticizer Diethyl phthalate (trade name DEP Kyowa Hakko Kogyo Co., Ltd.) ○ Curing agent Tolylene diisocyanate (T-80 Cosmonate Mitsui Toatsu Chemicals)

Next, a roller portion relatively soft and having excellent solvent resistance is formed around a mandrel serving as a shaft of the roller by using the above-mentioned agent. Example of First Manufacturing Method [First Step] The polyester for polyurethane elastomer (100 parts by weight) is heated to 100 ° C. [Second step] The plasticizer (22 parts by weight) is injected and well stirred. [Third Step] A curing agent (75 parts by weight) is mixed and further stirred. [64 steps] Insert the whole container into the vacuum chamber and reduce the pressure from 3 to
A dehydration treatment is performed at 5 mmHg for 15 minutes. [Fifth step] A release agent is sufficiently applied to the inner surface of a cylindrical mold having a mandrel as a center, filled with the dewatered material, and placed in an electric furnace. And the furnace temperature is 150
The mixture was heated at the temperature of 3 ° C. for 3 hours for vulcanization, taken out of the furnace and released from the furnace. The hardness (Shower A) of the polyurethane surface of the cored roller thus obtained was 30.

Embodiment of Second Manufacturing Method [First and Second Steps] Same as the first embodiment. [Third Step] A curing agent (69 parts by weight) is mixed and further stirred. [Fourth and fifth steps] Same as the first embodiment. The hardness (Shower A) of the polyurethane surface of the roller with the mandrel thus obtained was 20.

Embodiment of Third Manufacturing Method [First and Second Steps] Same as the first embodiment. [Third Step] A curing agent (67 parts by weight) is mixed and further stirred. [Fourth and fifth steps] Same as the first embodiment. The hardness (Shower A) of the polyurethane surface of the cored roller thus obtained was 15.

[0009]

As described above, the hardness (Shower A) of the polyurethane surface of the roller with the mandrel obtained in the first embodiment is about 30 ° and that of the roller in the second embodiment is about 20 °. there were. Conventional ordinary polyurethane roller,
Polylite OD-X-2195 (100 parts by weight) and 4,
Polyurethane elastomers combined with 4'-diphenylmethane isocyanate (10 parts by weight)
It is reported that the surface hardness will be 30 ° (hereinafter referred to as a conventional roller). However, according to the additional test of the present inventor, such a small surface hardness was not obtained, and the hardness was far more than the above-mentioned hardness of 30 °. However, according to the method of the present invention, the hardness is equal to or less than the surface hardness as described above.

As a method for estimating the solvent resistance of the roller to the solvent of the ink, there is a method of examining the rate of weight increase (preferably not increasing) when immersed in a specific solvent.
The elastomer of the roller (first embodiment) manufactured by the method according to the present invention and the elastomer corresponding to the conventional roller are mixed with a solvent A: methyl ethyl ketone (ME
K), solvent B: trichloroethylene, solvent C: toluene, and solvent D: methanol, for comparison. As shown below, the increase in weight at each of 5, 10, and 20 hours is almost equal to or less than that of the conventional roller. Even after 40 and 60 hours, there is not much change and it is stable.

Next, the above-mentioned solvents A, B, and
The weight increase measured every time after immersion in C and D is shown in percent (%). (1st Example) Solvent 5 hours 10 hours 20 hours 40 hours 60 hours A 6.8% 7.1% 8.5% 12.7% 19.4% B 6.5% 6.7% 6. 9% 11.6% 16.3% C 0.3% 0.7% 1.6% 2.1% 2.3% D 0.4% 0.9% 1.8% 2.5% 2. 8% (conventional roller) Solvent 5 hours 10 hours 20 hours A 6.25% 9.3% 10.3% B 7.69% 11.5% 12.7% C 0.4% 0.6% 1 0.5% D 0.4% 0.5% 1.9% The increase rate of the second and third embodiments of the present invention is equal to or slightly higher than that of the first embodiment. there were.

Claims (1)

(57) [Claims] 1. A printing machine which heats a polyester for a polyurethane elastomer, injects and stirs a plasticizer, stirs and injects a curing agent, dehydrates under reduced pressure, injects it into a mold, heats it, and releases it after sulfurating. A method for producing a polyurethane roller for a printing press, comprising: a plasticizer containing diethyl phthalate; and a curing agent containing tolylene diisocyanate.