Han Bangchun (Xuzhou Golden Crown Industrial Co., Ltd., Xuzhou, Jiangsu, 221009)

Abstract: Explain the production process of the paper-repellent and anti-fouling chemical treatment of paper-making blankets. The paper's anti-fouling, abrasion-resistant and self-cleaning properties are studied. improve.

Keywords: papermaking felt, chemical treatment, dirt repellent and wear resistance, self-cleaning performance, improved performance.

     With the rapid development of the paper industry, some wide-width, high-speed, high-line press paper machines have emerged. China's paper companies not only have grown rapidly in production scale, but also have been continuously updated in terms of technical equipment. Most of the newly constructed paper production lines Adopt the most advanced technical equipment in the world. According to statistics in 2003, there are about 16 paper machines in China with a width of more than 5M and a speed of more than 1000m / min. The paper types produced are coated paper, high-grade liner board paper, household paper, newsprint, and coated paper. Cloth whiteboard paper, corrugated paper, etc., adopt advanced new concept press forms such as large roll diameter high-impact press, shoe press, etc. The general linear pressure is about 300KN / M, and the maximum linear pressure can reach 1000KN / M.

     Statistics on paper and cardboard production capacity are as follows:

There have been 89 pulp and paper enterprises with a production capacity of over 100,000 tons per year; 33 pulp and paper companies with a production capacity of over 200,000 tons per year; and pulp and paper companies with a production capacity of over 300,000 tons per year. Reached 20; Pulp and paper enterprises with a production capacity of more than 500,000 tons / year have reached 8.

     However, this type of wide-width, high-speed, high-line press paper machine puts forward higher requirements on the matching dewatering equipment, especially the papermaking felt, which not only requires the papermaking felt to have good water filtration performance and dimensional stability Performance and abrasion resistance also require good resistance to high line pressure, elastic recovery, uniform leveling of the layer, stain repellency and self-cleaning performance. At present, the papermaking blankets that are matched with this type of papermaking machines basically rely entirely on imports. According to relevant information from the General Administration of Customs of China, the number of imported paper-making net blankets has increased significantly year by year. In 2003, the foreign exchange of imported paper-made carpets was 7.6 times that of 1998. From 1998 to 2003, the total foreign exchange for imported papermaking carpets reached 164.2 million US dollars. And this fact undoubtedly sounded a wake-up call for domestic paper-making carpet manufacturers.

     Most of the paper-making blanket companies in China started late, the technical level is relatively lagging, the innovation and development capacity is weak, and the upgrading of new products is slow. In recent years, in order to meet the higher demand for papermaking blankets in the papermaking industry, some papermaking blanket manufacturers have realized the seriousness of the problem and have successively invested a large amount of funds, introduced a large number of internationally advanced papermaking blanket production equipment and technology, and directly purchased international The first-class raw materials for paper-making blankets of first-class quality have intensified the technical transformation of equipment and obtained their own intellectual property rights on certain products and equipment. It has indeed achieved some effects in improving the basic performance of papermaking blankets such as high linear pressure resistance, water filtration performance, and dimensional stability. Individual papermaking blanket manufacturers that are at the forefront of product development have successively developed a large number of new-type papermaking blankets with high technological content, such as: 1 + 1 composite double-layer BOM papermaking blanket, 1 + 2 (2 + 1) composite three-layer BOM papermaking blanket, and large roller diameter Special papermaking blankets for presses, special papermaking blankets for shoe presses, etc. However, compared with the international advanced papermaking blankets, our products still have a large gap in service life, anti-staining self-cleaning performance, elastic recovery performance, etc. Can not meet the needs of high-speed, wide-format paper machines. In order to produce papermaking blankets suitable for high-speed papermaking machines, foreign papermaking blanket manufacturers not only have a deep research on the basic performance of products as of the end of the last century, but also have done a lot of work in the subsequent chemical treatment of papermaking blankets, and Some products with superior performance and high technical content have been developed and put on the market one after another. Practice has proved that after different chemical treatments, the performance of this type of papermaking felt is not only improved in terms of dirt repellency, abrasion resistance, and fuzzing resistance, but also softens and hardens the surface compared with the papermaking felt without chemical treatment. , Smooth and delicate, initial adaptability and other aspects have also been greatly improved. The perfection of this performance will help the papermaking blanket to meet the needs of high-speed, wide-width papermaking machines.

     China's research on chemically-treated paper-making blankets is in its infancy. Articles about this research are occasionally reported, but the actual products produced are rare.

     In order to keep pace with the progress of the international papermaking felt industry and meet the performance requirements of medium and high-speed papermaking machines for papermaking felts. We have developed a new type of chemically-treated paper-making blanket—stain-repellent and chemical-resistant paper-making blanket. This article only starts from the aspects of the production process of the stain-resistant and wear-resistant chemical treatment papermaking blanket, the test of the stain-resistant and wear-resistant performance, and the use of the product in actual production to improve the performance of the papermaking blanket and extend the papermaking blanket's performance. Explore the service life.

1 Principle of anti-fouling and anti-wear

1.1 Overview of pollution and wear resistance:

     Stain-repellent and chemical-resistant papermaking blankets use fluorochemical surfactants or silicon-containing epoxy resin coatings to chemically treat papermaking blankets. This chemical substance bonds with the polyester or nylon fibers of the blanket to make the wet paper The fine fibers, fillers and other contaminants generated during the dehydration process of the sheet are not easy to combine with the polyester fiber, so as to improve the anti-stain and anti-wear performance of the papermaking felt. The papermaking felt after chemical treatment of anti-staining can achieve two aspects of anti-staining performance: on the one hand, the fibers of the paper-making felt have good anti-staining properties, that is, the fillers, fine fibers, and glue in the slurry are not easy to stain Adsorbed on the surface of the fiber; on the other hand, the dirt absorbed in the blanket is easily washed away by clean water or detergent, thereby maintaining the carpet's good water drainage channel and elastic recovery performance. At the same time, it can improve the binding force between the fibers of the felt, effectively adjust the density of the surface of the felt, make it more suitable for the papermaking machine to make paper during the initial use, and effectively improve the shear stability of the papermaking felt. And strong, can be used in paper machines with higher line pressure and speed.

1.2 Analysis of the principle of dirt and wear resistance:

     Whether the dirt is easy to contaminate the fiber or easily detach from the fiber surface, in addition to the washing conditions and other related factors, it is mainly related to the critical tension of the fiber surface, that is to say, the fiber surface energy situation. If the interface energy of the oil surrounded by the fiber is E1, then:

E1 ＝ Afγfo ＋ Asγow

Where: Af-interface area between oil / fiber; As-interface area between oil and water remaining on the fiber; γfo-interfacial tension of oil / fiber; γow-interface of oil / water tension.

     When the oil is removed from the fiber, the interface energy E2 is:

E2 ＝ Afγfw ＋ Aoγow

In the formula: Ao——the area of tiny oil droplets in water; γfw——the interfacial tension of water / fiber.

     In the process of decontamination, when the role of decontamination is spontaneous, the energy after decontamination must be lower than the energy before decontamination, that is, the energy change before and after decontamination ΔE = E2-E1 <0, the above two formulas Substitute:

ΔE ＝ E2-E1 ＝ Af (γfw－γfo) ＋ γow (Ao-As)

     Assuming that the dirt removed from the fiber is spherical, Ao is less than As. If γfw and γow decrease, γfo increases, and γfw-γfo <0 can meet the requirements of the above formula.

     The size of γow depends on the type and concentration of water and the detergent used. In general, its value is small. For polar fiber, due to its strong interaction with water, the value of γfw is also small, and the value of γfo is large, which meets the requirements of the separation of dirt and fiber in the above analysis. For non-polar synthetic fibers, the interaction with water only has a dispersion force, so the γfo value is low, and the γfw value is high. Therefore, to make foreign matter easy to wash away, the fiber surface must have a low γfw value and a high γfo value. In other words, the introduction of new hydrophilic group genes or hydrophilic polymers for surface treatment on the surface of non-polar fibers can reduce the binding force between dirt and fibers, and improve the ability of fibers to remove dirt. The purpose to be achieved by carrying out the chemical treatment of anti-fouling and abrasion resistance.

2 Production of paper-repellent blankets with anti-fouling and wear-resistant chemical treatment

2.1 Production process:

 2.2 Production process parameters (taking 1300g / m2 1 + 1 composite double-layer BOM paper blanket as an example):

Mixed opening process, weaving process, needle punching process, etc. will not be repeated here, focusing on analysis of the chemical treatment process.

2.2.1 Chemical treatment process:

2.2.1.1 Process requirements:

This process requires that the chemical solution is dip-coated on the paper-making felt to be uniform and that the chemical components can fully bond with the fibers.

2.2.1.2 Chemical treatment system configuration:

     It is composed of chemical storage tank, infusion pump, high-level liquid storage tank, coating roller, vacuum box, return pipe, hot oil roller, pre-pressurization, etc. The chemicals are provided by the manufacturer, and the vacuum degree of the vacuum box is between 0.03 and 0.04 MPa. The total amount of coating chemicals is affected by factors such as operating speed, chemical concentration, gram weight of papermaking blankets, and coating roll coating fluid volume. Generally, blankets must be uniformly saturated with chemical solutions. Operating speed: 500 rpm. Hot roller heating temperature: 180 ～ 200 ℃, setting temperature: 210 ℃ ～ 220 ℃. Pre-pressure roller pressure: about 20KN / M.

2.2.1.3 Chemical treatment system configuration diagram: The chemical treatment system configuration diagram is as follows:

 2.2.2 Stereotype process:

     This process is mainly to make the bonding between the chemical composition and the PA fiber and PA heald at a certain temperature and a certain time, and to better bond the PA fiber of the papermaking felt under high temperature The combination makes the surface of the papermaking felt more smooth; meanwhile, the moisture content of the papermaking felt reaches about 10% for easy transportation and storage. This process requires the setting temperature to be uniform and stable, the running speed of the blanket to be stable, and the moisture control of the finished product before the machine is accurate. Temperature: 210 ℃ ～ 220 ℃; Operating speed: 500 rpm; Pre-pressurized pressure: 20KN / M; Product moisture: 10% ± 1.

3 Experimental methods

3.1 Test materials:

Simulated sludge (self-made).

Papermaking blankets: 1300GSM, 10cmx10cm size, (1 + 1) composite double-layer BOM papermaking blankets, one each after stain-repellent chemical treatment and non-chemically treated papermaking blanket.

3.2 Self-cleaning ability (easy to wash) test:

3.2.1 Simulated sewage preparation:

Take 5g of carbon black, 60g of cottonseed oil, 40g of paraffin, and 5L of tetrachloroethylene.

3.2.2 Contamination method:

Add a drop of stain (0.02ml) to two samples (one chemically treated and one chemically untreated), and then covered with a layer of cellophane, plus a 1.6kg weight, and remove and wash after 30 seconds.

3.2.3 Washing method:

Using 6g of soap powder at 1:50 and a temperature of 60 ° C, put two samples into the washing solution at the same time, and stir continuously with a glass rod for 10 minutes.

3.2.4 Rating:

The staining status of the two samples is rated according to GB251-1995 "Gray Sample Card for Evaluation of Staining" (level 1-5). The result is that the samples without chemical treatment reach level 2, and the samples with chemical treatment reach level 4.

3.3 Repellent (oil) test:

3.3.1 Test materials:

Motor oil.

Papermaking blankets: 1300GSM, 20cmx20cm size, (1 + 1) composite double-layer BOM papermaking blankets, one each after being stain-resistant and wear-resistant chemically treated and one without chemical treatment.

3.3.2 Oil staining method:

Weigh two samples (one chemically treated and one chemically untreated) respectively, then weigh them (W1), then inject 0.5L of engine oil, and leave it for 5 minutes. After wiping off the surface of the oil with a napkin, press with three layers of napkin 1.6kg, absorb oil for 30 seconds, then take out and weigh separately (W2). According to this, the oil absorption (W oil absorption) is obtained:

 3.3.3 Comparison: After weighing, the sample without chemical treatment absorbs 0.34g of oil, and the sample with chemical treatment absorbs 0.1g of oil. 3.4 Anti-hair removal and abrasion resistance test [i]: Abrasion resistance test equipment is used, the test technical parameters are in accordance with the test specifications, the number of wear resistance is read by an automatic counter, and the three arithmetic averages are taken out as the test result. Abrasion resistance tester; movement frequency: 180 times / min; pressure: 10-20kPa; abrasive: emery 220 #; specifications: 140mm × 220mm; load: 10N. 3.4.2 Test material: Paper-making blanket: 1300GSM, ø120mm size, (1 + 1) composite double-layer BOM paper-making blanket, four paper-making blankets each with stain-repellent chemical treatment and non-chemical treatment. 3.4.3 Test operation:

3.4.4 Comparison: The number of friction of the chemically treated sample is 23.9% higher than that of the sample without chemical treatment.

4 Analysis of experimental results

4.1 Self-cleaning ability (easy to wash) effect analysis: from the above self-cleaning ability experiment: through reasonable chemical treatment, the dirt of the paper-making blanket is easier to wash, indicating that after the dirt repellent and wear-resistant chemical treatment, the dirt and fiber The binding strength of the product is indeed reduced. Under the same washing conditions, the self-cleaning ability of the chemically treated paper-making felt is greatly improved, making it easier to wash.

4.2 Analysis of the effect of soil repellent: From the above-mentioned soil repellent test, it is concluded that the amount of oil adsorbed by the paper-making felt subjected to the chemical repellent treatment is significantly lower than that of the paper-making felt without chemical treatment. It shows that the paper-making felt after chemical treatment has a significantly reduced adsorption capacity for dirt and a significantly improved ability to reject dirt.

4.3 Analysis of anti-hair removal and abrasion resistance effects: The above test shows that the number of friction of the chemically treated felt is 23.9% higher than that of the sample without chemical treatment. It shows that the chemically-treated papermaking felt has significantly improved the bonding between fibers, and its anti-pilling performance and abrasion resistance have been significantly improved.

5 The effect of chemical treatment of papermaking blankets on paper machines

5.1 Paper machine: Tracking is performed on a 3200/500 stacked wire paper machine at a factory in Shandong. The speed of the paper machine: 450m / min; production of 200g / m2 white cardboard; pressing form: two-pass Φ1500mm large roll diameter pressing; linear pressure: 220KN / M.

5.2 Results of use:

5.3 Use result analysis:

It can be seen from the above use results that the service life of the chemically treated papermaking felt is significantly longer than that of the unchemically treated papermaking felt; the thickness of the upper and lower machines: because the chemically treated papermaking felt has a longer service life than the unchemically treated papermaking felt, There is not much difference in the corresponding thickness between the two, which can not fully explain the difference in elastic recovery between the two; from the corresponding changes in the weight of the upper and lower machines corresponding to the two, the change is not large. However, the analysis of the small samples of the old felt collected after getting off the machine shows that the clogged dirt in the paper-making felt after chemical treatment is significantly less than that of the paper-making felt without chemical treatment, and the surface wear and fuzzing state of the latter is significantly heavier than former. It can basically be concluded that the paper-made felt after chemical treatment has good performances in stain repellency and self-cleaning, and its improvement in wear resistance can also be fully demonstrated.

6

Conclusion Through the above analysis, we can draw the following conclusions:

1) Anti-staining chemical treatment papermaking felt is a process of further processing and treatment of papermaking felt, is a method to make the performance of papermaking felt more perfect.

2) Paper-making felts treated with anti-staining chemicals have anti-staining properties.

3) The paper-making blankets that have undergone anti-staining chemical treatment have good self-cleaning ability and are more convenient to wash under the same washing conditions.

4) Paper-making felts treated with anti-staining chemicals have good abrasion and fluff resistance.

5) Although no direct conclusions have been drawn on performances such as resistance to high-line pressure, elastic recovery, and adaptation to high vehicle speeds, the difference in service life has been able to explain to a certain extent: paper-making blankets that have been treated with chemical repellent and wear resistance In these aspects, the performance is higher than that of the papermaking blanket without chemical treatment. In the future, more tests will need to be done in this area with a view to drawing more reliable and reliable conclusions.

References: [1] Liu Jianyong Research on Anti-staining Finishing of Papermaking Blankets Industrial Textiles 2004. (10) [1] FZ / T01066 --- 1999 Determination of Stain Resistance of Coated Fabric