JPH0432759B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a compressible offset blanket, and more particularly to a method for manufacturing a compressible offset blanket having a compressible rubber layer made of porous rubber inside. . 2. Prior Art A known compressible offset blanket used in an offset printing process has an oil-resistant surface rubber layer 1 and a reinforcing fiber layer 2 on the lower surface of the surface rubber layer, or It is made up of a compressible layer 3 made of a porous material and a fiber backing layer 4 which are laminated one after another without intervening. In the deceptive compressible offset blanket, the means for forming the compressible layer 3 is disclosed in German Patent No.
A method of constructing with foamed rubber sponge as described in Publication No. 1165046 or Japanese Patent Publication No. 37-13110
As described in the above publication, a method has been proposed in which a nonwoven fabric is made of a cytoplasmic material impregnated with latex. Among the constituent materials of the above-mentioned compressible offset blanket, the compressible layer made of non-woven fabric has a weak elastic recovery force, which poses a practical difficulty in transmitting the necessary printing pressure to the oil-resistant surface rubber layer. It will be done. Naturally, compressible offset blankets with deceptively compressible layers are associated with major obstacles to practical application due to poor printing properties due to insufficient printing pressure. In addition, compressible offset blankets with a compressible layer made of foamed rubber sponge have a thickness of 0.1 mm to
Because it is difficult to form bubbles with a uniform diameter inside the ultra-thin compressible layer of approximately 1.0 mm, it is impossible to generate uniform printing pressure over the entire surface of the compressible offset blanket. Improvements were strongly requested. As a way to solve the problem of deception,
Japanese Patent Publication No. 52-7371 discloses a compressible offset in which the compressible layer is formed of a rubber elastic material containing microscopic hollow spheres (microcapsules) made from a soluble or crushable material such as a thermoplastic resin. - The method of manufacturing the blanket is described.
By adopting this method, the diameter of the pores formed inside the compressible rubber layer and the state of dispersion of the pores can be made fairly uniform, but the individual microcapsules may be slightly unevenly formed during vulcanization. Due to the expansion, the uniformity of pore distribution within the compressible rubber layer may be impaired. Another method is to vulcanize and mold a rubber sheet made of a rubber composition containing an appropriate amount of salt, and then immerse the rubber sheet in water to extract the salt, thereby encapsulating a large number of continuous pores. Techniques for molding compressible rubber layers are also known. however,
Compressible offset with deceptive porous rubber layer
Blankets are made with rubber glue, because during the "sizing operation" during the manufacturing process, the salt contained in the rubber glue causes corrosion of the bracket forming equipment such as doctor knives. It is necessary to apply anti-corrosion treatment such as coating the instruments and molding equipment components that come into contact with expensive corrosion-resistant materials such as Teflon resin, and to remove adhering rubber glue and clean them frequently. This results in inconveniences such as having to do so. Problems to be Solved by the Invention The present invention solves the nonuniformity of pore size and pore distribution in the manufacturing direction of the compressible layer using microcapsules, and also solves the problem of rust generation in the salt extraction method. Its main objective is to provide a method of manufacturing a compressible offset blanket that can solve the problem. Means for Solving the Problems In view of the purpose of deception, the present invention provides a compressible offset layer consisting of an oil-resistant surface rubber layer 11, a compressible rubber layer 12 and a fiber backing layer 13, which are sequentially laminated on the lower surface of the oil-resistant surface rubber layer 11. In the blanket manufacturing process,
An unvulcanized rubber composition in which water is dispersed and mixed is prepared as a material for forming the compressible rubber layer 12, and after layering,
Compressibility is achieved by irradiating the unvulcanized rubber composition with high-energy electromagnetic waves to create pores in the water particles at the same time as vulcanization, and using the expansion pressure to form fine independent pores in the compressible rubber layer 12. The gist of this paper is a method of manufacturing an offset blanket. Examples In carrying out the present invention, the method of dispersing and mixing water into an unvulcanized rubber composition is to mix a surfactant into the main rubber, knead water with a kneading roll machine, and prepare the resulting aqueous dispersion. (usually referred to as "water glue") into the base rubber, or blending an inorganic filler containing water of crystallization such as lime, barium sulfate, or magnesium hydroxide into the base rubber. It will be done. In addition, high-energy electromagnetic waves include
It is preferred to use an electron beam with an irradiation intensity of 20 Mrad. In other words, the irradiation intensity of the electron beam is
If less than 3 Mrad, compressible rubber layer 12
If it becomes impossible to form a structure with dispersed independent pores in the interior and the electron beam irradiation intensity exceeds 20 Mrad, the compressible rubber layer 12 and/or the compressible rubber layer 12 and the reinforcing fiber backing layer Inconveniences such as deterioration of the laminated structure with 13 occur. To explain the embodiment of the present invention in more detail, 20 to 60 parts by weight of the aqueous dispersion is blended with 100 parts by weight of the rubber main material, or
An unvulcanized rubber composition is prepared by blending an inorganic filler containing 20 to 60 parts by weight of water of crystallization, and the unvulcanized rubber composition (main rubber is NBR) is applied to a fiber backing layer. On one piece of plain woven fabric that makes up 13
After "sizing" the cloth to a thickness of 0.1 mm to 1.0 mm, the obtained rubberized cloth is introduced into a known high-frequency heating furnace, and simultaneously vulcanized and supported in the aqueous dispersion or inorganic filler. The water particles contained in the compressible rubber layer 12 are vaporized, and a dispersed structure of fine independent pores is formed in the compressible rubber layer 12 using the expansion pressure when the volume increases 273 times. After forming the porous compressible rubber layer 12 in this way, as illustrated in FIG. A second fiber backing layer 15 made of plain woven fabric is further laminated on the lower surface of the intermediate rubber layer 4. In addition, the compressible rubber layer 12
An oil-resistant surface rubber layer 11, which functions as a printing layer, is laminated on the upper surface of the substrate through a primer (adhesive layer, indicated by reference numeral 16) and a reinforcing cloth layer 17 made of plain woven cloth. When molding the above laminated structure, the compressible rubber layer 1
It is preferable that the thickness of No. 2 is adjusted within the range of 0.1 mm to 1.0 mm. If the thickness of the compressible rubber layer 12 is less than 0.1 mm, the oil-resistant surface rubber layer 11 will not be able to provide a cushioning effect that is practically satisfactory; If it exceeds this value, it becomes too soft and printing performance deteriorates. The overall thickness of the final compressible offset blanket is usually adjusted to a range of about 1.5 mm to 2.5 mm, and the thickness of the oil-resistant surface rubber layer 11 is
It is adjusted within the range of 0.2mm to 0.6mm. The laminated structure of the compressible offset blanket should not be construed as limited by the above illustrative explanation; it may be one in which only the fiber backing layer 13 is laminated on the lower surface of the compressible rubber layer 12, or a compressible rubber Various laminated structures can be selected, such as one in which two backing layers are laminated on the lower surface of the layer 12 and one reinforcing fabric layer is laminated on the upper surface of the compressible rubber layer 12. As a specific embodiment of the method of the present invention, the composition of the compressible rubber layer 12 is exemplified as shown in Table 1 below.

【table】

[Table] Effects of the Invention As can be understood from the above explanation, in the method of the present invention, an unvulcanized rubber composition in which water is dispersed and mixed is used as the material for forming the compressible rubber layer. It is possible to reliably prevent non-uniformity in pore size as observed in microcapsules. Therefore, in the offset printing process,
It is possible to effectively eliminate problems such as halftone dots (blurred outline), thickening (increase in diameter), and voids (occurrence of thin spots) caused by uneven printing pressure. The compressible rubber layer according to the present invention having countless fine independent pores also functions as a pressure absorbing member for the oil-resistant surface rubber layer, so the gear and
It is possible to avoid a problem in which the blanket is unable to absorb the "backlash" caused by the clearance and a striped shading pattern, so-called "shock", occurs on the printed surface. Furthermore, in the present invention, water with pore-forming ability is used instead of salt as the pore-forming material, so there is no need to apply anti-rust treatment to the sizing equipment and instruments, resulting in savings in equipment investment and It can also have a significant effect on extending the service life of structural devices.

[Brief explanation of drawings]

FIG. 1 is an enlarged longitudinal cross-sectional view of a compressible offset blanket according to the present invention, and FIG. 2 is an enlarged longitudinal cross-sectional view of a conventional offset blanket. 11...Oil-resistant surface rubber layer, 12...Compressible rubber layer, 13...Fibre backing layer.

Claims (1)

[Scope of Claims] 1. In the manufacturing process of a compressible offset blanket consisting of an oil-resistant surface rubber layer, a compressible rubber layer and a fiber backing layer sequentially laminated on the lower surface of the compressible rubber layer, An unvulcanized rubber composition in which water is dispersed and mixed as a forming material is prepared, and after layering, the unvulcanized rubber composition is irradiated with high-energy electromagnetic waves to vaporize the water particles and expand them at the same time as vulcanization. A compressible offset material that uses pressure to form fine pores within a compressible rubber layer.
Method of manufacturing blankets. 2. A patent in which the step of preparing an unvulcanized rubber composition into which water has been dispersed consists of a step of blending an aqueous dispersion, which consists of blending a surfactant with rubber and kneading water with a kneading roll machine. A method of manufacturing a compressible offset blanket according to claim 1. 3. The compressible offset blanket according to claim 1, wherein the step of preparing the unvulcanized rubber composition into which water is dispersed includes a step of blending an inorganic filler containing water of crystallization. Production method.