JPH09300849A - Damping water-feed roller for offset printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the necessity of addition of alcohol or the like for the purpose of lowering the surface tension of damping water and improve the resistance to corrosion and resistance to wear by forming an oxide glass film on the outer peripheral face of a metal roller support and specifying the surface roughness of the film. SOLUTION: A continuous water supply device of an offset printer is provided with a water fountain roller 4 rotated by immersing its lower section in the water in a water tank 5, a damping water roller 3 rotated being in contact with the water fountain roller 4 and a water immersion roller 2 rotated being in contact with the damping water roller 3, and water adhered to the surface of the water immersion roller 2 is fed to a non-immersion section of a plate cylinder 1. In that case, the damping water roller 3 is provided with a metal roller support constituted of cast iron or the like and an oxide clay film formed on the outer peripheral face of the metal roller support and the surface roughness of the oxide glass film is set as 1.0μm or less. As the oxide glass film, it is suitable to use a glass tube or an enameled glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dampening water supply roller used as a water source roller and a water leveling roller of a continuous water supply device of an offset printing machine.

[0002]

2. Description of the Related Art Offset printing is a printing method that uses the property that ink (oiliness) repels water, and hydrophilic treatment is applied in advance to the parts of the plate cylinder where ink is not applied (non-image areas). Then, the water film carried from the water boat is attached to the hydrophilic portion by the water supply roller. The ink film is carried there by the ink roller, but since the oil-based ink repels water, the ink is applied only to the place where there is no water film on the plate surface.

In the offset printing, the print quality is determined by the thickness of the water film carried by the water supply roller. If the water film is too thick, water penetrates into the ink side and the outline of the halftone dot of the print is blurred. There was a problem that the phenomenon of ink disappearing inside the halftone dots occurred. Further, if the water film is too thin, the repulsion with the ink becomes insufficient, and there is a drawback that the ink adheres to the places that should not be attached and the printed matter is stained. Therefore, offset printing cannot be performed in a good state unless the water film has an appropriate amount of about several μm and is not uniform in the axial direction.

The conventional water supply roller is a metal roller whose surface is plated with hard chrome or is made of stainless steel, and is excellent in wear resistance and workability, but the surface in contact with water is better than metal. Therefore, the wettability with water is not sufficient, and therefore it is necessary to add alcohols such as isopropyl alcohol (IPA), which is harmful to the working environment, to water for the purpose of lowering the surface tension of water. there were.

Further, Japanese Patent Laid-Open No. 2-84395 discloses that
A ceramic sprayed layer composed of 100 to 0% by weight of Al ₂ O ₃ and 0 to 100% by weight of TiO ₂ is formed on the outer peripheral surface of the metal roller, and the ceramic sprayed layer has hydrophilic Si.
Disclosed is a dampening water supply roller characterized in that a sealing treatment is performed with an O ₂ -based inorganic sealing agent, and the surface roughness is reduced to 1.6 S or less by polishing.

[0006]

However, the ceramic sprayed layer is porous, and after spraying ceramics,
Although it is necessary to perform a sealing treatment with a SiO ₂ based inorganic sealing agent, the surface condition of the roller is unstable depending on the application technique of the SiO ₂ based inorganic sealing agent, and considering the durability. However, there is a problem that the characteristics of the ceramic sprayed layer itself cannot be utilized.

Therefore, the object of the present invention is to eliminate the need for adding alcohol or the like to reduce the surface tension of the dampening water, to have a good working environment and to have excellent corrosion resistance and wear resistance. It is an object of the present invention to provide a novel dampening water supply roller for a offset printing machine having a glass coating.

[0008]

That is, a dampening water supply roller for an offset printing machine according to the present invention (hereinafter, simply referred to as "water supply roller") has a metal roller support as an essential constituent member. Characterized by comprising an oxide glass vitreous coating provided on the outer peripheral surface of the metal roller support, and having a surface roughness Ra of 1.0 μm or less. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The water supply roller of the present invention is characterized in that an oxide glass vitreous coating formed from a glass tube or an enamel glass forming composition is provided on the outer peripheral surface of a metal roller support. is there. This oxide glassy coating is
Unlike the ceramic sprayed layer, it does not become porous, and it is not necessary to perform a sealing treatment with a SiO ₂ -based inorganic sealing agent after spraying the ceramics. In addition, this oxide glass vitreous film has extremely good wettability with water as compared with a metal roller plated with hard chrome and a roller provided with a ceramic sprayed layer subjected to sealing treatment. It has the feature.

In the water supply roller of the present invention, the method of forming the oxide glass vitreous coating on the metal roller support is not particularly limited, but it can be produced, for example, by the following method: The metal roller support is inserted into the oxide glass tube molded in the above shape and heat-fused to set the oxide glass coating on the outer peripheral surface of the metal roller support; An adhesive is applied to the outer peripheral surface of the metal oxide film, and then the metal roller support is inserted into an oxide glass tube that has been formed into a predetermined shape in advance, and the adhesive is cured to form an oxide glass film. Is placed on the outer peripheral surface of the metal roller; a so-called enamel glass-forming composition (mud), which is obtained by adding other inorganic materials to glass powder, is applied to the metal roller support, dried, and then fired. , Metal low The oxide glass film is placed on the outer circumferential surface of a metal roller carrier by heat sealing on the support; baked in advance enamel glass metallic roller carrier,
After that, the metal roller support is inserted into an oxide glass tube molded into a predetermined shape, heated and fused to set the oxide glass coating on the outer peripheral surface of the metal roller support.

Here, the oxide glass tube and enamel glass constituting the oxide glass coating of the water supply roller of the present invention have a coefficient of thermal expansion of a metal roller support (iron base = 130).
〜140 × 10 ^-7 ℃ ^-1 ), the coefficient of thermal expansion is 95
˜110 × 10 ⁻⁷ ° C. ⁻¹ (between 100 and 400 ° C.) and a composition having physical properties of a softening point of 500 to 720 ° C. are preferable, and examples of suitable compositions are described below, but a glass tube and enamel It should be understood that the composition of the glass forming composition is not limited to the following.

[0012]

[Table 1]

In the water supply roller of the present invention, the material of the metal roller support is not particularly limited, but may be made of iron or cast iron, for example.

Further, the thickness of the oxide glass film formed on the outer peripheral surface of the metal roller support is 0.5 to 2.5 m.
m, preferably 1.0 to 2.0 mm. Here, if the thickness of the oxide-based glass coating exceeds 2.5 mm, it is difficult to produce a glass coating of uniform thickness, and the residual compressive stress of the glass coating layer decreases and the strength becomes weak. If the thickness is less than 0.5 mm, the strength is weak and the glass coating layer is easily cracked, which is not preferable.

Further, it is essential that the water supply roller of the present invention has a surface roughness Ra of 1 μm or less. here,
When the surface roughness Ra exceeds 1 μm, the water film becomes nonuniform, which is not preferable. When the surface roughness Ra of the oxide-based glass film formed by the above method does not become 1 μm or less, the surface roughness can be adjusted within the above range by appropriately performing a polishing treatment. Here, the polishing treatment is not particularly limited, but, for example, a method of roughly finishing with a silicon carbide grindstone, then performing intermediate finishing with an alumina grindstone, and finally performing precision finishing with a diamond film abrasive Can be used.

[0016]

【Example】

Example 1 72 mol% SiO ₂ , R ₂ O (R = Na, K, Li) 10 mol%, MO (M = Ca, Ba, Mg) 10 mol%, Al ₂
Glass tube having a composition of O ₃ + B ₂ O ₃ 8 mol% (coefficient of thermal expansion = 95 × 10 ⁻⁷ ° C. ⁻¹ ; softening point 720 ° C .; size = outer diameter 8
2φmm, inner diameter 78φmm, length 580mm) metal roller (material = STKM-13A; thermal expansion coefficient = 135
× 10 ^-7 ℃ ^-1 Dimension = Outer diameter 76φmm, Length 580m
m), maintain the temperature at 850 ° C. for 1.0 hour, and then cool to room temperature to fuse the glass tube to the metal roller support to form an oxide glass film, and then to diamond. Both ends of the oxide glass film were cut and removed with a grindstone. Next, the surface of the oxide-based glass coating is roughened with a silicon carbide grindstone # 320, then intermediately finished with alumina grindstones # 1000 and # 2000, and finally precision-finished with a diamond film abrasive. A water supply roller of the present invention having a surface roughness Ra of 0.02 to 0.03 μm was obtained. The outer diameter of the obtained water supply roller was 78 mm, and the length was 515 mm.

The obtained water supply roller was incorporated into a dampening water roller (3) of a continuous water supply device of an offset printing machine having a roller arrangement as shown in FIG. 1, and a printability test was conducted under the following actual machine printing test conditions. Carried out. In addition, in the continuous water supply device shown in FIG. 1, the water adheres to the rotating rubber water source roller (4) whose lower part is immersed in the water in the water boat (5), and then the water adheres. The water moves and adheres to the surface of the dampening water roller (3) that rotates in contact with the water source roller (4), and further rotates in contact with the dampening water roller (3) that has water adhered. Water moves and adheres to the surface of the rubber watering roller (6), and finally the water adhering to the surface of the watering roller (3) rotates in contact with the watering roller (2). It is configured to be supplied to the non-image part of the plate cylinder (1).

Actual machine test conditions: Printing machine: Offset rotary printing machine Printing speed: 150 m / min Printing ink: Oil-based ink [Toyo Ink Co., Ltd.] Dampening water: Circulating cooling water (water temperature 10 ° C; no alcohol added) Paper: Fine paper (55 kg; width 10.5 inches) Test time: 1 hour

As a result, the water supply roller of the present invention was free from the entanglement of ink on the roller surface, as compared with the conventional hard chrome plated roller, and good performance was obtained. It was also found that when the number of rotations of the water source roller was the same, the amount of water rising was smaller than that of the hard chrome plating roller, the thickness of the water film was thin, and the uniformity was high.

Example 2 An epoxy adhesive was applied to the outer peripheral surface of a metal roller support (material = FCD-40 casting; thermal expansion coefficient = 130 × 10 ⁻⁷ ° C. ⁻¹ ; dimension = outer diameter 76 φmm, length 515 mm). 0.5 mm
Of SiO ₂ 55 mol%, R ₂ O (R
= Na, K, Li) 20 mol%, MO (M = Ca, Ba,
Mg) 10 mol%, Al ₂ O ₃ + B ₂ O ₃ 7 mol%, TiO ₂
Glass tube having a composition of 5 mol% and CoO + NiO3 mol% (coefficient of thermal expansion = 110 × 10 ⁻⁷ ° C. ⁻¹ ; softening point 50)
0 ° C; Dimension = Outer diameter 81φmm, Inner diameter 77φmm, Length 5
(15 mm) and the epoxy adhesive was cured to form an oxide glass coating on the outer peripheral surface of the metal roller. Next, the surface of the oxide glass film was polished with a diamond film abrasive to obtain a water supply roller of the present invention having a surface roughness Ra = 0.02 to 0.03 μm. The outer diameter of the obtained water supply roller was 78 mm, and the length was 515 mm. An actual machine printing test was performed on the obtained water supply roller in the same manner as in Example 1. As a result, the printing performance was as good as that of Example 1, but after the test was completed, when the water supply roller was handled, some peeling was observed on the end surface of the oxide glass film, and the water supply roller of Example 1 was found. It was judged that the mechanical impact performance was slightly inferior to that of.

Example 3 65 mol% SiO ₂ , R ₂ O (R = Na, K, Li) 18 mol%, MO (M = Ca, Ba, Mg) 6 mol%, Al ₂ O ₃
+ B ₂ O ₃ 5 mol%, TiO ₂ 3 mol% and CoO + Ni
Water, clay, and CMC were added to an enamel glass forming composition having a composition of O3 mol% to form a slurry, which was made into a metal roller support (material = STKM-13A; thermal expansion coefficient =
135 × 10 ^-7 ℃ ^-1 Dimension = Outer diameter 76φmm, Length 58
(0 mm) on the outer peripheral surface to a thickness of 0.3 to 0.5 mm,
After drying at a temperature of 20 ° C. for 3 hours and then baking at a temperature of 850 ° C. for 1.0 hour, the operation of repeating the operation six times was repeated six times to form an oxide glass film on the outer peripheral surface of the metal roller.
(Coefficient of thermal expansion ^{= 100 × 10 - 7 ℃ -1} ; thickness 1.8 to 2.2
mm) was formed. Next, after roughly finishing the surface of the oxide-based glass coating with the silicon carbide grindstone # 320, intermediate finishing with the alumina grindstones # 1000 and # 2000, and finally with precision finishing with the diamond film abrasive. A water supply roller of the present invention having a surface roughness Ra = 0.8 to 1.0 μm was obtained. The outer diameter of the obtained water supply roller was 78 mm, and the length was 515 mm. The water supply roller thus obtained was incorporated into a dampening water supply mechanism having a roller arrangement as shown in FIG. 1, and a printability test was carried out under actual machine printing test conditions shown in Table 2 below. As a result, the water supply roller of the present invention was free from the entanglement of ink on the roller surface, as compared with the conventional Cr-plated roller, and good performance was obtained. In this example, even if the surface of the oxide-based glass coating was polished, the surface roughness Ra was only 0.8 to 1.0 μm. Therefore, it is considered that there are some fine pores in the coating injection.

Next, products 1, 2 and 3 of the present invention, a conventional hard chrome-plated roller and JP-A-2-8439.
When the wettability of the roller prepared according to Japanese Patent Publication No. 5 to water was investigated by the contact angle, the invention product 1 was 7 degrees, the invention product 2 was 7 degrees, the invention product 3 was 8 degrees, and the hard chrome plated roller was 85 degrees. The roller of JP-A-2-84395 has a rotation angle of 43 degrees, which shows that the roller of the present invention has excellent wettability.

[0023]

EFFECTS OF THE INVENTION The water supply roller of the present invention comprises an oxide glass coating having a surface roughness Ra of 1.0 μm or less on the surface of the roller in contact with dampening water. Even if it does not exist, ink entanglement does not occur, and it is excellent in corrosion resistance and abrasion resistance.

[Brief description of drawings]

FIG. 1 is a schematic view of a continuous water supply device of an offset printing machine.

[Explanation of symbols]

 1 plate cylinder 2 watering roller 3 dampening water roller 4 Mizumoto roller 5 water boat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Akazawa 735 Shimotomi, Tokorozawa, Saitama Prefecture Ikebukuro Enamel Industry Co., Ltd.

Claims (3)

[Claims] 1. An oxide glass vitreous coating comprising a metal roller support and an oxide vitreous coating provided on an outer peripheral surface of the metal roller support as essential components. A dampening water supply roller for an offset printing machine, which has a surface roughness Ra of 1.0 μm or less. 2. The dampening water supply roller for an offset printing machine according to claim 1, wherein the metal roller support is made of iron or cast iron. 3. The dampening water supply roller for an offset printing machine according to claim 1, wherein the oxide glass vitreous coating is made of a glass tube or enamel glass.