JPH07144489A - Manufacture of printing blanket - Google Patents

Abstract

PURPOSE:To obtain a printing blanket wherein rubber solution sticks directly close to a substrate layer, and coating is carried out uniformly with little irregularity by a method wherein rubber solution is continuously dropped from a gap of a head onto a substrate layer wherein an under layer of a front surface rubber is formed on a substrate formed by laminating a fabric base, an intermediate rubber layer, and a compressive layer. CONSTITUTION:A substrate layer 31 wherein an under layer of a front surface rubber 33 is formed on a substrate 32 prepared by laminating a fabric base 34, an intermediate rubber layer 35, and a compressive layer 36, is prepared. Then, by using a head composed of a head body and a tip part having a uniform gap in a direction crossing at right angles a carrying direction of a material to be coated provided to the tip of the head body, rubber solution is continuously made to flow down onto the substrate layer 31, a thin rubber layer is formed on a front and a rear surface of the substrate layer 31. Consequently, since film like rubber solution is stuck close directly to the substrate layer as it is, uniform coating with little irregularity can be applied and an irregularity of a shape wherein irregularity in thickness of a front face functional layer 37 is emphasized, is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printing blanket.

[0002]

2. Description of the Related Art Conventionally, as a printing blanket, as shown in FIG. 1, a support 4 composed of a base cloth 1, an intermediate rubber layer 2 and a compressible layer 3 and a surface rubber layer 5 arranged thereon. It is known to be composed.

The printing blanket having such a structure is manufactured as follows. (1) First, after forming the support 4, the surface rubber layer 5 is coated. Here, the surface rubber layer 5 is most commonly knife-coated with a rubber paste prepared by dissolving a rubber compound in a solvent. In other words, the support is coated vertically with the liquid material on the support layer between the doctor knife and the roll which are vertically arranged on the roll. Coat about 0.01 to 0.03 mm at a time and repeat until the required thickness is reached. Another method for forming the surface rubber layer is performed by rolling the rubber compound with a calendar roll and press-bonding this to a support (USP409).
3487).

(2) Next, the blanket coated with the surface rubber layer 5 is wound on a drum and vulcanized by heating. When the vulcanized blanket requires thickness accuracy or fine surface roughness, it is polished to obtain a finished product.

[0005]

However, the conventional printing blanket has the following problems. (1) The surface rubber layer of the printing blanket is generally 0.3.
~ 0.5 mm thick. The surface rubber layer may be a single layer structure made of the same type of rubber, or a plurality of rubber layers made of different materials may be laminated to give a special function.
For example, as shown in FIG. 2, the surface rubber layer 21 is replaced with a surface functional layer.
21a and the surface rubber lower layer 21b have a two-layer structure and the compression characteristics are controlled by changing the hardness of both, or the surface functional layer 21a has a special function, oil resistance, solvent resistance, UV curable ink resistance, In the case of imparting abrasion resistance, non-stickiness, lubricity, bending resistance, etc., and in addition, a special geometric shape may be imparted to the surface. In this case, no matter where the total thickness of the surface rubber layer is the same, at the same time,
If the thicknesses of the constituent layers are not equal everywhere, the function as the surface rubber will be different depending on the place. With this, the function as a blanket becomes uneven, and a stable printed matter cannot be obtained.

(2) In the conventional knife coating, the thickness of 0.01 to 0.03 mm is repeatedly applied at one time.
The coating thickness at one time is an average value, and even if the thickness of the object to be coated (support) is extremely small, the thickness applied to the thin part is thicker, and conversely The thicker part is applied thinner. Therefore, the coating thickness is small each time, but there is uneven thickness. This is because there is no possibility that there will be no thickness unevenness of the object to be coated (base layer). With knife coating, while correcting the thickness unevenness on the object having a slight thickness unevenness, The coating results in the coating having another form of non-uniform thickness. Knife coating is a repeat of this. In addition, special functions such as oil resistance, water resistance, and lubricity may be required for the back surface (woven fabric surface). This is accomplished by immersing the woven cloth in the respective treatment liquid and drying, which requires a woven cloth treating machine.

(3) On the other hand, although a thin coating can be applied by a roll coating method, a printing method or the like, it is difficult to form a uniform coating having a uniform thickness strictly. The roll coating method includes, for example, direct coating and reverse roll coating, but the coating liquid is adjusted to an arbitrary thickness on the roll and then pressure-transferred onto the object to be coated. When the coated layer is viewed strictly, stripes and other unevenness occur along the coating direction. The strength depends on the material of the coating liquid, the manufacturing method, the composition, etc., and is restricted by the material, so that it can be used only with a limited material.

The printing method includes a direct printing method and an offset printing method. In the direct printing method, the coating liquid is directly transferred from the plate of metal, resin, rubber, etc. to the object to be coated, but except for the direct method using the gravure plate, it is possible to eliminate the occurrence of streaks like roll coating. Can not. But,
Even in the gravure plate, the coating liquid must fill the very small dents, and the transfer liquid must have the corresponding transfer characteristics in order to transfer this to the object to be coated. This is the material of the coating liquid. It becomes a constraint of choice. In particular, a rubber-based material is difficult to obtain a transition characteristic due to its inherent elasticity. In the offset printing method, the coating liquid is once transferred from the plate to the rubber roller, and this is retransferred to the object to be coated. In this case, since it has the same action as the roll coating described above, the occurrence of streaks is inevitable.

The present invention has been made in view of the above circumstances, and a head gap is formed on a base layer in which a lower surface rubber layer is formed on a support formed by laminating a base cloth, an intermediate rubber layer and a compressible layer. Since the rubber solution directly adheres to the substrate layer as it is by continuously flowing down the rubber solution from above, it is possible to provide a method for producing a printing blanket capable of coating with extremely uniform and less unevenness.

[0010]

It is practically impossible from a work management point of view to coat a surface functional layer having a small thickness of, for example, 10 μm by knife coating with a uniform thickness. To this end, regardless of the thickness accuracy of the base layer, it is conceivable to form a film having a good thickness accuracy by another means and adhere the film to the base layer. However, the roll coating and printing methods cannot be used because of uneven streaks. It is easily conceivable to press-bond a sheet-shaped rubber compound rolled by a calender roll onto a support. However, in rolling with a calendar roll, for example, 100 μ
It is difficult to obtain a thin sheet having a thickness of m or less. Also,
One of the methods for forming the surface rubber of the blanket is a method in which the material is knife-coated on a release paper, pressure-bonded to a support, and then the release paper is removed (Japanese Patent Publication No. 62-1).
9316). However, the thickness unevenness of the coating layer occurs depending on the thickness unevenness of the release paper. The present inventors have conducted various studies on a processing method corresponding to forming a surface functional layer having a small thickness and no unevenness on the uppermost layer, and as a result, a method completely different from the conventional coating,
That is, after preparing a base layer having a surface rubber lower layer formed on a support body in which a base cloth, an intermediate rubber layer and a compressible layer are laminated, a head main body and an object to be coated provided at the tip of the head main body are prepared. Using a head having a tip portion having a uniform gap in the direction orthogonal to the transport direction, a rubber solution is continuously flown down from the gap of the head onto the base layer, and thin rubber is applied to the front and back surfaces of the base layer. It has been found that applying a thin uniform layer to the surface of the blanket substrate layer by forming the layer is very effective.

What is important in the present invention is that the rubber solution continuously flowing down has its shape determined by the surface tension of the front surface and the back surface, so that it is formed into a uniform film having extremely good thickness accuracy. By doing so, the rubber solution directly adheres directly to the article to be coated,
A very uniform and even coating is possible.

FIG. 3 shows a schematic cross-sectional view of a printing blanket formed according to the present invention. 31 in the figure is a support
A base layer consisting of 32 and a lower surface rubber layer 33 thereon. The support 32 includes a base cloth 34, an intermediate rubber layer 35, and a compressible layer 36. A surface functional layer 37 is formed on the base layer 31. In this invention, the continuously flowing rubber solution covers the surface of the base layer 31 composed of the support 32 and the surface rubber lower layer 33, and the surface forms a smooth free surface. Then, as a result of evaporation of the solvent, a smooth surface functional layer 37 is formed.

Here, as the material of the surface functional layer,
Depending on the intended function, one or more of the most suitable rubbers or resins can be used together. For example, nitrile rubber, chloroprene rubber, fluororubber, urethane rubber, acrylic rubber, silicone rubber, epichlorohydrin rubber,
Examples include natural rubber, acrylic resin, epoxy resin, urethane resin, polyester resin, polyamide resin, polyolefin resin, and polyether resin.

The required thickness of the surface functional layer differs depending on the purpose, such as a minimum thickness that does not cause functional deterioration due to abrasion during use, a minimum thickness that prevents penetration of a solvent, etc., but a maximum thickness of 2
It is 00 μm. In use, the mechanical load on the surface may be small and the thickness may be small, for example, 10 μm may be sufficient, such as non-adhesiveness or when a mirror surface is required. The maximum thickness per coating according to the present invention is 10 to 30 μm.
Then, by repeating this, the required thickness can be obtained.

[0015]

According to the present invention, the rubber solution is continuously flowed down from the gap of the head onto the base layer having the lower surface rubber layer formed on the support formed by laminating the base cloth, the intermediate rubber layer and the compressive layer. By doing so, the film-shaped rubber solution directly adheres to the substrate layer as it is, so that extremely uniform and less uneven coating is possible. In addition, there are various advantages such as the occurrence of unevenness in a shape in which the thickness unevenness of the surface functional layer is emphasized and expensive fluororubber can be used in a minimum amount. Further, it is possible to obtain a printing blanket useful for obtaining a surface functional layer having a thickness of 100 μm or less.

[0016]

Embodiments of the present invention will be described below.
FIG. 8 is a schematic view of the head according to the present invention. head
Reference numeral 81 denotes a head main body 83 having an opening 82 in the upper portion, and a tip end portion 85 attached to the front end of the head main body 83 and having a uniform gap 84 in the direction orthogonal to the transport direction of the workpiece. There is.

Example 1 Reference is made to FIGS. 4 and 8. However, the same members as those in FIG. 3 are denoted by the same reference numerals and the description thereof will be omitted.

First, as shown in FIG. 4, a base layer 31 comprising a support 32 and an NBR-based surface rubber lower layer 41.
Was formed, vulcanized and polished. Rz roughness of polished surface is 2 μm
Met. Subsequently, a rubber compound having the following composition, in which an inorganic filler that causes foreign matter, pinholes, etc. was not added, was prepared by using a normal kneading roll.

NBR (trade name: N230SV, made by Japan Synthetic Rubber) 100 parts by weight zinc white 5 parts by weight stearic acid 1.5 parts by weight Vulcanization accelerator (trade name: NOXCELLER CZ, manufactured by Ouchi Shinko Chemical Co., Ltd.) 1 part by weight Vulcanization accelerator (trade name: Nocceller TT, manufactured by Ouchi Shinko Kagaku Co., Ltd.) 0.5 parts by weight Sulfur ... 1.5 parts by weight DOP 10 parts by weight And 200 parts by weight of this compound with MEK. Two
A rubber solution was obtained by dissolving in a mixture of 00 parts by weight of xylol. Next, the gap 84 at the tip 85 of the head 81 shown in FIG.
At a flow rate of 0.4 liter / min / cm (flow rate of 1 liter / min of head width) at a flow rate of 0.6 mm, and the rubber solution is made to flow down in a film form, and passes under the blanket at a speed of 70 m / min. Let 30 minutes at 40 ℃, 60 ℃
After drying at 60 ° C. for 60 minutes, vulcanization at 150 ° C. for 10 minutes resulted in a film 42 having a thickness of 10 μm. This blanket had no foreign matter on the surface and had good ink familiarity, and high-definition image lines could be printed accurately and evenly.

(Embodiment 2) Referring to FIG. 5 and FIG. However, the same members as those in FIG. 3 and FIG. First, as shown in FIG. 5, a base layer 31 including a support 32 and a surface rubber lower layer 41 based on NBR is formed.
Vulcanized and polished. On the ground lower surface, the gap between the tip 85 of the head 81 shown in FIG. 8 is 0.5 mm, the flow rate is 0.4 liters / minute / cm, and Lord Huson's trade name: Chemlock 607 is used as a film as a primer. And was passed under the blanket at a speed of 80 m / min. This was dried at room temperature for 30 minutes to obtain a primer layer 51. On top of this, a rubber compound having the following composition was prepared with a usual kneading roll.

Fluorine rubber (trade name: Viton A, manufactured by DuPont) ... 100 parts by weight magnesium oxide ... 15 parts by weight carbon black (product name: Thermax N900, manufactured by Vanderbilt) ... 5 parts by weight hexamethylenediamine carbamate (trade name) : DIAC No. 1, manufactured by DuPont) 1.5 parts by weight This compound was dissolved in 680 parts by weight of MEK to obtain a fluororubber solution. Next, the gap 84 at the tip 85 of the head 81 shown in FIG. 8 is 0.8 mm, and the flow rate is 0.5 liter / min /
The fluororubber solution was coated on the primer at a blanket running speed of 80 m / min. This 5
After drying at 0 ° C. for 15 minutes, coating and drying were repeated once more. This was vulcanized at 150 ° C. for 30 minutes. The thickness of the obtained coating layer 52 was 35 μm. Subsequently, a UV dry type offset ink (PSW manufactured by Dainippon Ink and Chemicals, Inc.) was brought into contact with this for 72 hours at room temperature. As a result, it swelled by 0.01 mm, but the swelling amount did not change at any place. At the same time, the NBR blanket tested for comparison swelled by 0.06 mm.

(Embodiment 3) Referring to FIG. 6 and FIG. However, the same members as those in FIG. 3 and FIG. First, as shown in FIG. 6, a base layer 31 made of a support 32 and an NBR-based surface rubber lower layer 61 having a hardness of 50 degrees was formed, vulcanized, and polished. Next, 100 parts by weight of polyether-based polyurethane (trade name: Coronate C4090, made by Nippon Polyurethane), 4,4′-methylenebis- (2-chloroaniline) (trade name: Bisamine A, Wakayama Seika) 12.7 A hardness of 9 parts by weight was mixed at 80 ° C and diluted with 100 parts by weight of cyclohexanone at the same temperature.
A 0 degree urethane rubber compound was made to flow down in a film form at a gap of the head 81 of 1.0 mm and a flow rate of 0.4 l / min / cm on the polished surface of the blanket that was run at 70 m / min. Coated. This was dried at 90 ° C. for 60 minutes and then heated at 120 ° C. for 5 hours to be cured. The thickness of the obtained coating layer 62 was 30 μm. This blanket was not easily scratched on the surface, and uneven printing due to uneven hardness was not found.

(Embodiment 4) Referring to FIG. 7 and FIG. However, the same members as those in FIG. 3 and FIG. First, as shown in FIG. 7, a base layer 31 composed of a support 32 and an NBR-based surface rubber lower layer 71 having a hardness of 60 degrees was formed, vulcanized, and polished. Next, head a primer (trade name: Primer A, manufactured by Shin-Etsu Chemical Co., Ltd.) on it.
The film was made to flow down into a film with a gap of 81 being 0.5 mm and a flow rate of 0.4 l / min / cm for coating. The primer layer 72 was continuously dried for 30 minutes at room temperature. Next, a liquid obtained by diluting 100 parts by weight of silicone rubber (trade name: KE45RTV, manufactured by Shin-Etsu Chemical Co., Ltd.) with 500 parts by weight of toluene was used.
The film was made to flow down at a rate of min / cm and coated on it. This was left at room temperature for 3 days to dry and cure.

The thickness of the obtained coating layer 73 is 15 μm.
It was m. As a result of offset printing of this blanket with an ultraviolet drying type ink, it was possible to print without swelling trouble due to the ink.

The above embodiment has the following effects. (1) The substrate layer coated on the support to the lower layer of the surface rubber by the conventional knife coating usually has a thickness unevenness of 10 μm. When a 10 μm surface functional layer is applied onto this by knife coating, the film thickness becomes 10 to 20 μm. On the other hand, when the re-upper layer is formed by the method of the present invention, the film-like thickness unevenness is ± 1% of 10 μm, that is, 2 μm. Therefore, the thickness is 9-11 μm,
Greatly improves accuracy.

For example, in the case of a surface functional layer having good ink transferability but poor oil resistance with respect to a lower surface rubber layer having good oil resistance, the surface functional layer has uneven thickness due to swelling due to penetration of solvents from the surface. The unevenness of the shape is emphasized. However, this does not happen with the present invention.

(2) On the contrary, in the case of a combination of a fluorine rubber surface functional layer having a further excellent oil resistance on the NBR base oil resistant surface rubber lower layer, a UV curable ink having a strong penetrating power is obtained. On the other hand, swelling can be prevented with a thin fluororubber layer of about 30 μm. With this, expensive fluororubber can be kept to a minimum amount.

(3) When a hardness difference is provided between the surface functional layer and the lower surface rubber layer, for example, when the surface functional layer is made of wear-resistant rubber having a hardness higher than that of the lower surface rubber layer, the thickness of the surface functional layer is uneven. As a result, the compression characteristics fluctuate, and a uniform printed matter cannot be obtained. However, the present invention solves this problem.

(4) Other special functions given to the surface functional layer are abrasion resistance, non-adhesiveness, bending resistance, weather resistance, low friction coefficient, good ink transfer property, and fine image line without foreign matter. There is a printing surface, a smooth surface or a mirror surface suitable for realizing high fidelity of image lines.

(5) In this invention, unlike the other coating methods, there is no transfer step, and the film-like coating solution having a completely uniform thickness is directly laminated on the article to be coated. , A very uniform coating is possible.

(6) The coating layer according to the present invention formed on a flat surface has a smooth free surface. When the surface of the base layer is polished to a fine surface, scratches are eliminated depending on the coating layer applied thereon, and an extremely smooth and mirror-like surface is obtained. This is extremely effective for high-precision printing, paper dust is reduced, and the quality of printed matter is not deteriorated.

(7) On the contrary, in order to improve the peelability from the material to be printed, it is also effective when finishing to a rough surface. The roughened base layer has a matte shape and a large friction coefficient. When the coating according to the present invention is applied to this, the surface is glossy and has a small friction coefficient while maintaining the shape of the rough surface.
On this surface, there is little accumulation of ink, paper dust, etc., which is a drawback of the polished surface, and the running property of the material to be printed is stable.

(8) The back surface of the blanket is generally a woven fabric. If the cleaning oil or water comes into contact with the blanket during use, these penetrate into the woven fabric and swell. When the water and oil repellent agent is coated by the method according to the present invention, a woven fabric processing machine is not required, and a coating which is durable can be formed very easily.

(9) When the blanket is wound around the cylinder of the printing machine, if the back surface has a large coefficient of friction, the blanket cannot be evenly wound in the circumferential direction, resulting in partial slack and uneven printing. The method according to the present invention uses a silicone oil system,
Coating with a wax-type lubricant or the like enables extremely easy and effective treatment.

[0035]

As described above in detail, according to the present invention,
By flowing the rubber solution in the form of a film from the gap of the head onto the base layer having the lower surface rubber layer formed on the support formed by laminating the base cloth, the intermediate rubber layer and the compressible layer, Since it directly adheres directly to the base layer,
A coating that is extremely uniform and has little unevenness is possible, and no unevenness in the shape of the surface functional layer is emphasized, and more expensive fluororubber can be used in the minimum amount. Has the advantage of, especially 100μ
A method for producing a printing blanket useful for obtaining a thin sheet having a thickness of m or less can be provided.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a conventional printing blanket.

FIG. 2 is a schematic cross-sectional view of a conventional printing blanket having a two-layered surface rubber layer.

FIG. 3 is a schematic sectional view of a printing blanket according to the present invention.

FIG. 4 is a schematic sectional view of a printing blanket according to the first embodiment of the present invention.

FIG. 5 is a schematic sectional view of a printing blanket according to a second embodiment of the invention.

FIG. 6 is a schematic sectional view of a printing blanket according to a third embodiment of the invention.

FIG. 7 is a schematic sectional view of a printing blanket according to a fourth embodiment of the invention.

FIG. 8 is an explanatory diagram of a head used in the present invention.

[Explanation of symbols]

31 ... Base layer, 32 ... Support, 33, 41, 6
1, 71 ... Lower surface rubber layer, 34 ... Base cloth, 35 ...
Intermediate rubber layer, 36 ... Compressible layer, 37 ... Surface functional layer,
42 ... Film, 51, 72 ... Primer layer, 52, 62, 73 ...
Coating layer, 81 ... Head, 83 ... Head body, 84 ... Gap.

Claims (1)

[Claims] 1. A base layer having a surface rubber lower layer formed on a support comprising a base cloth, an intermediate rubber layer, and a compressive layer laminated, and then provided on the head main body and the tip of the head main body. Using a head having a tip portion having a uniform gap in a direction orthogonal to the conveyance direction of the workpiece, the rubber solution is continuously flown down from the gap of the head onto the base layer, and the front surface and the back surface of the base layer. A method for producing a printing blanket, which comprises forming a thin rubber layer on the surface.