Domestic aprons have obvious limitations, including pure cotton aprons, chemical fiber aprons and wool aprons, which have poor spinnability. In the past, spinning mills had a single variety of textiles, and this apron had its own market. However, after China entered the WTO and entered the global economy, the spinning varieties of spinning mills became increasingly diversified, and the disadvantages of this apron became more and more obvious. First of all, it is time-consuming and laborious for textile mills to change spinning varieties and stop working to change aprons, which affects output; Secondly, due to the frequent replacement of aprons, the maturity of aprons will inevitably affect the yarn quality, resulting in worse evenness, increased CV value of evenness, and more coarse knots and details; Thirdly, apron has many varieties and specifications, which is difficult to manage and the production cost will increase. The above disadvantages will definitely affect the market competitiveness of textile enterprises. Therefore, it is imperative to design a kind of apron with strong versatility, wear resistance, long service life and good spinnability. Long-term production practice has proved that the friction coefficient (for various fibers and metals), elasticity and hardness of aprons are the main indexes to determine whether aprons can be used normally. Spinnability of apron refers to whether it can meet the needs of yarn quality. First of all, we should ensure the spinning quality, that is, on the basis of ensuring the normal spinning of aprons, we should achieve wear resistance, oil resistance and buckling resistance in order to obtain the longest service life. The disadvantage of apron in the past is that the above two conditions are separated, which makes the rubber formula of spinning different kinds of aprons different, which leads to that cotton aprons can only spin pure cotton and chemical fiber aprons can only spin chemical fiber. For example, 94 10 apron is used for spinning pure cotton, and 9 1 1O-3 apron is used for spinning chemical fiber. Most aprons used for spinning pure cotton are soft in design, and the hardness is between Shore .A65 and Shore A66, and the hardness is adjusted by plasticizer dibutyl ester. So this apron is soft and elastic at the beginning of use, but it is not rigid. The longer it is used, the harder the apron becomes with the migration and volatilization of plasticizer. Therefore, in the initial stage of use, the drafting effect is acceptable and the CV value of spinning evenness is ideal. But the longer the time, the worse the yarn evenness and the shorter the service life, because of its low strength and poor wear resistance. Spinning polyester cotton and chemical fiber aprons have high hardness, the hardness is Shore A74, the strength is 25% higher than that of pure cotton aprons, but the elasticity is insufficient, which is 33% lower than that of pure cotton aprons, which weakens the control ability of floating fibers, and the twisting and drafting effect is not ideal, and the details are mostly measured in kilometers. In order to enhance the winding resistance, antistatic agent is added to the rubber compound, which will make the apron hard and brittle. Therefore, in specific use, aprons are easy to be brittle, resulting in large cracks, leading to serious entanglement, increased broken ends and greatly shortened service life.
From the use of different types of aprons, it can be seen that effectively solving the contradiction between spinnability and service life is a major breakthrough in apron production technology.
Spinnability of 2 H2 1 1 apron
The development of rubber products is mainly the design of formula and process route. Through the optimal combination of materials and advanced equipment and technology, excellent products are produced. By testing and analyzing foreign aprons, digesting and absorbing advanced technology, H2 1 1 aprons were developed. H2 1 1 apron has strong spinnability, which can meet the production requirements of different raw materials, facilitate the production management of textile mills and reduce production costs. During the development of H2 1 1 aprons, the following aspects were studied emphatically.
(1) Selection of main materials. Similar polarity is the first condition for the mixing of two substances. The smaller the polarity difference between the two materials, the better the dissolution effect of dispersed phase. From the actual material selection, the polarity is similar and the solubility parameters are close. The solubility parameter of NBR is 9.6, while that of another polymer synthetic material is 9.57, which are very compatible. Moreover, this polymer synthetic material is completely different from the previous NBR-PVC resin and NBR-monochloroacetic acid resin systems, and its average molecular weight is obviously higher than that of ordinary plastics and close to rubber (see Table 2). Therefore, H2 1l apron has the characteristics of high elasticity and small permanent deformation under high strength compression.
2) Selection of auxiliaries. From the point of view of the flexibility, wear resistance, aging cracking and spinnability of the product, the above properties are realized by selecting new additives. At present, 75% of the new additives are imported into H2 1 1 aprons. If the plasticizer imported from Germany is selected, it has good compatibility with nitrile rubber, high molecular weight, difficult migration and volatilization, good cold and heat resistance, and gives the product excellent low-temperature flexibility and excellent antistatic effect. Figures 1 show the changes of the apron hardness of H2 1 1, 94 10 and 91/kloc-0-3 with time and temperature.
Figure 1 shows that the hardness of H2 1 1 aprons increases slightly with the extension of service time, while the hardness of 94 10 aprons and 9 165438-00 aprons increases greatly. With the increase of temperature, the hardness of H2 1 1 has little change, and it has strong adaptability to high temperature environment. The hardness of 94 10 and 9 1 10-3 aprons decreased obviously. Application effect of 3 H2 1 1 aprons.
H2 1 1 apron was tested in Wuxi Textile Machinery Testing Center for 20 months, and was applied to polyester cotton varieties and pure cotton varieties respectively.
3. Application of1in polyester cotton varieties
In order to test the spinnability of H2 1 1 aprons, H21/aprons were compared with other aprons when spinning key varieties of rice yarn. The results are shown in Table 3.
Judging from the application, H2 1 1 apron has smooth surface, good resilience and aging resistance, soft hand feeling and strong adaptability to temperature and relative humidity changes. The apron has strong spinnability, which is mainly manifested in the frequent changes of spinning varieties, and the good and stable yarn quality can be maintained without replacing H2 1 1 apron. At present, H2 1 1 apron is still in use and has been continuously tested for a longer time. 3.2 Application in pure cotton varieties
CJ 14.6 tex yarn is spun on FA506 spinning frame with H21/aprons. The yarn quality is shown in Table 4.
Under the same spindle and process conditions of A5 13C spinning frame, the spinning of H2 1 1 apron was compared with other aprons. The spinning variety is cJ 14.5 tex knitting yarn. See Table 5 for yarn quality.
The spinning test shows that H2 1 1 apron has good elasticity, good buckling resistance in operation, stable running speed, low slip rate and strong anti-winding ability. No abnormal fluctuation is found after long-term large-area use, and the yarn quality is ideal.
4 conclusion
H2 1 1 apron starts with spinnability. On the basis of meeting the requirements of yarn quality, the strength of apron is improved, the requirements of wear resistance, oil resistance and flex resistance are met, and the service life is prolonged. The life of ordinary aprons is only 6 ~ 8 months, while the life of H2 1 1 aprons reaches 12 months. After long-term tests, H2 1 1 apron can spin cotton, polyester cotton and wool yarn with good yarn quality.