JPS59188493A - Prevention of poisoning of oxidation catalyst for exhaust gas treatment in offset printing - Google Patents

Abstract

PURPOSE:To prolong the useful life of a catalyst used in a deodorizing device while maintaining the effect of an emulsion as a coating material, by using an emulsion comprising polyethylene or a fatty acid ester as a main constituent. CONSTITUTION:An emulsion comprising polyethylene or a fatty acid ester as a main constituent is used as a coating liquid. The emulsion is, for example, sprayed onto the surface of a paper by a spray gun 18. By this, a lubricating effect is imparted to the surface of the paper in a manner similar to that in the case of using an organosilicon compound, whereby the printing surface of the paper can be prevented from being contaminated due to friction between a roller and the paper, and paper alignment on a folding can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an offset printing method that prevents poisoning of a catalytic oxidation catalyst for exhaust gas treatment.As shown in FIG. It is printed in step 6 (multi-color printing is also acceptable) and dried in drying device 4. Next, the paper 1 is coated with a coating agent by a coating device 5 in order to prevent stains caused by rubbing and to improve paper alignment. The paper 1 is sent from a cutting and folding machine 6 to a binding machine 7. When the printed paper surface dries, high molecular compounds, resin waxes, high boiling point solvents, aldehydes, acrolein, and the like are contained in exhaust gas and discharged from the printed paper surface along with organic solvents. When these exhaust gases are released into the atmosphere, the solvents they contain not only cause air pollution but also become a source of bad odors. Therefore, various exhaust gas treatment methods are being implemented to prevent pollution. The exhaust gas is treated and rendered harmless by a catalytic combustion deodorizing device that uses a catalyst. There are two types of combustion deodorization methods; one is a direct combustion method and the other is a catalytic combustion method.

The combustion temperature of the catalytic combustion method is 20% lower than that of the direct combustion method.
Since it can be processed at a low temperature of 0 to 450°C, it has the advantage of low fuel consumption and low learning costs, but from an economic standpoint, it is essential to maintain a long catalyst life. Catalysts generally use catalysts in which precious metals such as platinum are supported on supports such as alumina, and have relatively high activity and durability compared to base metal catalysts such as manganese.However, precious metal catalysts Since it is expensive, if catalyst poisoning substances are included in the exhaust gas, the catalyst will deteriorate and its life will be shortened, making it uneconomical.For this reason, conventional methods have been used to treat catalyst poisoning substances such as dust and mist. , a method has been taken to prevent a decrease in catalyst activity by installing a removal device such as a filter. Conventionally, an emulsion containing organic silicone as a main component has been used as the coating liquid in the coating device. The coating liquid used is shown in Table-1.

Table 1 This is generally commercially available as an organic silicone emulsion, and its stock solution is usually used as an aqueous solution of 1 to 50 parts.

There are three types of coating devices: a brush type (Fig. 2), a roller type (Fig. 6), and a spray type (Fig. 4). In the brush method, a brushed roller 15 splashes the coating liquid onto a felt roller 16, and the coating liquid is applied from the felt roller to the printing paper surface. In the one-roller type, a coating liquid is attached to the surface of a metal roller 17 and applied to the printing paper. In one type of spray, a spray gun 18 sprays the coating liquid onto the paper surface.

As mentioned above, the purpose of installing this coating device is to create a sliding effect on the paper surface by applying the coating liquid, to prevent stains on the printed paper surface due to the friction between the roller and the paper, and to improve the alignment of the paper in the folding machine. do. Humidifying the printing paper also has the effect of preventing the generation of static electricity due to friction between the printing paper and the roller and improving paper alignment.

When an emulsion containing organic silicone as the main component is used as a coating liquid, the organic silicone is sucked into the dryer together with air from the openings, cooling exhaust gas, combustion air fan, etc. where the printing paper enters and exits the dryer, and is absorbed into the drying exhaust gas of the printing paper. It is entrained in the air and mixed into the exhaust gas deodorization equipment. It is difficult to remove such organic silicone with a filter, and methods have been devised to remove it using an adsorbent or the like. However, in these removal methods, when a large amount of catalyst poisoning substances such as organic silicones are contained at a high concentration, the removal equipment becomes complicated and equipment costs and operating costs are high. Furthermore, if the exhaust gas is at a high temperature, there is a limit to how much it can be treated with adsorbents or the like. The organic silicone mixed into the deodorizing device is burned on the catalyst of the deodorizing device along with other malodorous components. At this time, organic silicone is also catalytically burned, resulting in fine 5io
- covers the catalyst pores and reduces the activity of the catalyst, resulting in a decrease in deodorizing performance.

The present inventors completed the present invention as a result of various studies as a means to extend the life of the catalyst. By using an emulsion mainly composed of polyethylene or an emulsion mainly composed of fatty acid ester instead of an emulsion mainly composed of organic silicone, it is possible to maintain the effectiveness of the coating agent and extend the life of the catalyst in the deodorizing device. I found out how to make it longer.

The present invention can be applied to printing and coating systems equipped with a coating device, but is particularly effective for offset rotary printing systems.

Experimental examples and examples of the present invention will be described below.

Example 1　Table 2 shows the results of a suitability test conducted on several types of coating liquids K to replace emulsions containing organic silicone as a main component, which are conventionally used coating liquids.

From the results of this test, it was found that an emulsion containing polyethylene or fatty acid ester as a main component is effective as a coating liquid.

FIG. 5 compares the concentration of the coating liquid and the slip imparting effect (relative dynamic friction coefficient) between these coating liquids and an emulsion whose main component is organic silicone using coated paper. Emulsions containing polyethylene as a main component have a large slip-imparting effect even at low concentrations. Typical compositions of emulsions containing polyethylene and fatty acid ester as main components are shown in Table 6.

Surfactants other than those shown in Table 3 may be used as emulsifiers, such as sulfosuccinate type surfactants to improve wetting properties.

Example 1 The effects of using the coating liquid shown in Table 6 were compared with those of an emulsion containing organic silicone as a main component, and the results are shown in Table 4. As can be seen from this table, when a substitute is used, the activity of the catalyst in the deodorizing device used in the offset rotary printing system is less likely to decrease.

Claims (1)

[Claims] In an offset printing method consisting of a printing process, a drying process, a catalytic oxidation process of exhaust gas, and a coating process, the coating liquid used in the coating process is an emulsion mainly composed of polyethylene or an emulsion mainly composed of fatty acid ester. An offset printing method characterized by