Development of printing water vulcanizate for printing

Abstract The physical and mechanical properties of the vulcanizate and its water resistance at room temperature were tested by using lignocellulose powder, pretreated cotton linter short fibers, and calcined kaolin and white carbon, respectively, as fillers. The results showed that the hardness, tensile stress and tensile strength of the vulcanizates were improved to some extent with the increase of the amount of the three fillers. The elongation at break and the elastic resilience were reduced. Among them, 1530 parts were added. High alumina soil NBR vulcanizates have the most obvious improvement in physical and mechanical properties, and the rebound resilience is reduced to a small extent, and can also improve the hydrophilicity and grinding and polishing performance of NBR; adding lignocellulosic and lint staple fibers to NBR vulcanization The reinforcing effect of glue is not obvious, and the water absorption rate is too large.

Key words nitrile rubber lignocellulosic powder lint short fiber calcined kaolin printing water roller

Printing water roller vulcanizates are required to have the properties of wear resistance, elasticity and good hydrophilicity, low swelling, etc., especially the ability of the roller surface to have a certain degree of adsorption of water, but it cannot be excessively expanded in the medium.

Lignocellulosic powder has the characteristics of light weight, light color and easy dispersion in rubber and is suitable for the preparation of high elasticity and low hardness products [1, 2]. Cotton linter short fiber is a fibrous fibration with a length of more than 40 mesh. After surface treatment, it helps to improve the interaction with the rubber matrix, and the long diameter is relatively small, and it is easy to disperse in the rubber. The surface of lignocellulosic powder and pretreated cotton linters contain a large number of polar groups and have a certain ability to absorb water. The calcined sorghum soil is an amorphous, loose structure with various active sites such as Si-O, Al-O, and some remaining -OH on the surface. It also has a certain ability to adsorb water, and has a large amount of filler and good dispersion in the rubber. High whiteness, low impurity content, etc.

This article chooses nitrile rubber as the matrix, adding appropriate amount of white carbon black as reinforcing agent, comparing the use of three types of fillers with certain water absorption, such as lignocellulose powder, cotton wool fiber and calcined sorghum soil, to the physical and mechanical properties of the vulcanizate. And the impact of water resistance, and introduced the grinding roller and the use of performance.

1 Experimental section

1.1 Raw materials NBR, Perbunan NT3445, produced by Bayer, Germany; Lignocellulosic powder E-140, supplied by Guangzhou Jinchangsheng Company; Pre-treated lint short fibers supplied by the short fiber plant of Fujin City, Heilongjiang; Calcined kaolin, AT-01, Maoming Vaseaux produces; other materials and additives commonly used in the rubber industry.

1.2 Major Equipment and Instruments XSK-160 Open-type Rubber Mixer and QLB-D400×400 Electrothermo Flat Press (Shanghai First Rubber Machinery Factory), P3555B2 Disc Type Vulcanizer (Beijing Huanfeng Chemical Machinery Experiment Factory), XL- 100 type tensile testing machine (Guangzhou Guangcai Experimental Negotiator Co., Ltd.), LX-A Shaw's Rubber Hardness Tester (Shanghai Liuzhong Measurement Factory), percent thickness gauge and analytical balance (Shanghai Liuling Instrument Factory).

1.3 Basic formula (mass, the same below)
NBR, 100; ZnO, 5.0; stearic acid, 1.5; antioxidant 2246, 2.0; sulfur S, 2.0; accelerator DM, 1.2; accelerator CZ, 0.7; precipitated silica, 15; DOP, 60; Sulphur powder, pretreated cotton linters, and calcined kaolin are variables.

1.4 Mixing and vulcanization tests are performed according to basic recipes and conventional processes. The mixture was mixed on an XSK-160 open mill and added in the order of raw rubber, active agent, sulfur, antioxidant, filler, and plasticizer. Finally, an accelerator was added. Thin pass and hit the triangle bag 6 times, relax roll 3mm, roll 5 times, out of the film. Then use P3555B2 disk type curing instrument to measure the vulcanization characteristics of the rubber at 160°C, and then vulcanize on the QLB-D400×400 hot plate vulcanizing machine [160°C×10MPa×(T90)].

1.5 Performance Test Tensile stress-strain properties are measured according to GB/T 528-1998 (Type I specimens, tensile speed 500 mm/min); tear properties are tested according to GB/T 529-1999 (right angle specimen, tensile speed 500 mm /min); Shore A hardness according to GB/T531-1999 test; volume change rate according to GB1690-1992 test; resilience by GB1681-1991 test.

2 Results and Discussion

2.1 Physical and mechanical properties of vulcanizates The physical and mechanical properties of vulcanizates are shown in Table 1.
Table 1 Effect of different fillers on physical and mechanical properties of NBR vulcanizates Sample No. 1 2 3 4 5 6 7
Filler dosage (parts)
Performance 0 Woody cellulose powder
5 10 Cotton linters
5 10 Calcined Kaolin
15 30
Shore A hardness, degree 32 36 41 38 43 36 38
100% Definite Stress, MPa 0.34 0.89 1.37 1.69 2.31 0.97 1.26
300% modulus, MPa 0.57 1.20 1.89 2.03 2.79 1.76 2.76
Tensile strength, MPa 3.96 4.65 4.21 4.78 4.66 5.15 6.82
Elongation at break, % 780 670 635 570 460 680 670
Breaking permanent deformation, % 18 25 36 28 38 20 25
Resilience, % 48 37 32 36 32 46 44

From Table 1, it can be seen that the lignocellulose powder, pretreated cotton linter short fibers and calcined kaolin can increase the NBR's tensile stress and hardness to varying degrees, and with the increase of the amount, the increase is more pronounced; Tensile strength also increased, but slightly decreased with larger amounts. Calcined kaolin clay significantly increased the strength and elongation properties of the vulcanizate, and the hardness and rebound resilience were not greatly reduced. This is because calcined kaolin is an amorphous structure with various active sites such as Si-O, Al-O, and partially-remaining -OH, making the calcined kaolin polar, which facilitates interaction with nitrile rubber. It may also be advantageous for the dispersion of white carbon black in nitrile rubber.

In contrast, the addition of lignocellulosic flour and cotton linters significantly increases the hardness, settling stress, permanent tearing, and rebound resilience of the vulcanizates. As fibrous materials, lignocellulose and lint staple fiber have more polar groups on the surface, and they form a more dense chemical cross-linking and physical adsorption with NBR, thereby greatly increasing the hardness and tensile stress of vulcanizates. However, as the elongation rate increases, this dense chemical cross-linking becomes a stress concentration point, which is not conducive to the dispersion tensile stress of the vulcanizate, and thus exhibits a lower tensile strength; also, due to the lignocellulose powder and Cotton linter short fiber powders are hard, anisotropic organic fillers that hinder the movement and elastic recovery of the rubber molecules in the vulcanizate, thereby reducing the rebound resilience and elongation at break of the vulcanizate and increasing the permanent deformation. , The tensile strength does not increase much.

2.2 Water resistance of vulcanizates

After three different amounts of fillers were soaked in normal-temperature water for 12h, 24h and 48h respectively, the volume change rate of NBR vulcanizates was as shown in Table 2.
Table 2 Effect of different fillers on the water resistance of NBR vulcanizates Sample No. 1 2 3 4 5 6 7
Filler dosage (parts)
Performance 0 Woody cellulose powder
5 10 Cotton linters
5 10 Calcined Kaolin
15 30
Soaking 12h volume change rate, % 0.33 0.50 0.52 0.53 0.57 0.72 0.89
Soak 24h volume change rate, % 0.54 0.56 1.70 1.98 2.47 1.08 1.32
Soak 48h volume change rate, % 0.55 1.87 3.00 3.44 5.91 1.55 2.02

As can be seen from Table 2, the volume of the vulcanizates with calcined kaolin, lignocellulosic powder, and pretreated lint short fibers soaked in water for a certain period of time increases to varying degrees, and the rate of change increases with the amount of filler used. The larger the pre-treated cotton linter short fibers, the more pronounced is the effect. This is mainly because the surface of lignocellulose and cotton linters contains a large number of polar groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, etc. It is easy to form a strong hydrogen bond with water, and calcined kaolin is an amorphous loose body. Although the kaolin particles on the surface of the vulcanized rubber are coated with rubber molecules, some of the bare particles still have a certain ability to absorb water, but due to the less -OH groups on the surface, the ability to adsorb water is not great.

2.3 Cots test results

The iron core was rusted and coated with a CHlok 205 adhesive. After drying, sample Nos. 1, 3, 5, and 7 were coated on the iron core, and the mixture was vulcanized with a canvas, and the vehicle was cooled after being cooled to room temperature. polishing. When the surface of the rubber roll was observed through a magnifying glass, the surfaces of the rubber rolls of Samples 1 and 7 were found to be relatively smooth, while the surfaces of the other two rubber rolls were slightly roughened. After immersing the sample of the rubber roll in tap water at room temperature for two hours, the surface of the sample 7 had small and uniform drops of water, while the surface of the other samples had large drops of water. This shows that calcined kaolin can improve the hydrophilicity of the vulcanizate and it is easy to polish.

3 Conclusion

In the scope of this experiment, the following conclusions are obtained:
(1) Lignocellulosic powder, pretreated cotton linter short fibers, and calcined kaolin have a certain reinforcing effect on 15 parts of white carbon black-filled nitrile rubber, which increases the hardness, tensile stress, and tensile strength of the vulcanizate. However, the elongation at break and resilience decreased.
(2) The addition of 15 to 30 parts of calcined kaolin can significantly improve the mechanical properties of vulcanizates compared to filling 5 to 10 parts of lignocellulosic powder and pre-treated cotton linters, and the rebound resilience is not greatly reduced.
(3) NBR vulcanizates with calcined kaolin clay have more suitable hydrophilicity and good roller polishing performance; and it can be used as an ideal filler for NBR printing water rollers in combination with appropriate amount of white carbon black.

Wang Zhiyuan Chen Fulin Yan Lan Zhou Yanhao (College of Materials and Energy, Guangdong University of Technology)
Reprinted from: Wenzhou Rubber Net