Several common problems and solutions in waterproof and oil-proof finishing
With the development of the fabric industry, special functional finishing is increasingly recognized by people. Water and oil-proof finishing has been developing more and more rapidly in recent years. Organofluorine resin is a water- and oil-proof finishing agent with excellent performance. It is widely used in work clothes, high-end interior decorations, shoes and socks, bed sheets, luggage, etc. due to its high effectiveness, resistance to deterioration, and ease of use. Fabric products. However, many printing and dyeing manufacturers often encounter some problems when using organic fluorine water- and oil-repellent finishing agents, such as poor initial water-blocking performance, poor durability, water-blocking stains and streaks, and great color changes. etc. In response to the above problems, through many experiments and practices, we found the causes of the problems and put forward the main countermeasures to solve the problems.
Problem 1. Poor initial water repellency
1. Reason:
Through experiments, it is believed that there are only three main reasons for poor initial water repellency:
⑴ Finishing cloth: The scouring or coloring cloth is not cleaned sufficiently, and scouring agent, leveling agent, dispersant, penetrating agent and other auxiliaries remain on the cloth.
⑵Problems with working fluid, improper use concentration or change in concentration during finishing; or, working fluid is affected by mechanical stirring, temperature, mixing chemicals, etc., and its stability is affected. Another reason is that the working fluid preparation sequence is inappropriate and the pH value of the bath fluid is incorrect.
⑶ Due to the finishing conditions, the water blocking agent is not properly selected, or the drying and baking conditions are insufficient and uneven. The main countermeasures to solve the above problems can start from the following aspects
2. Main countermeasures
⑴. Before water-blocking finishing, the finishing cloth should be fully washed.
⑵Choose a water-blocking agent suitable for fiber finishing, and the newly prepared working fluid may be continuously replenished during finishing. Strengthen the temperature control of the finishing cloth, and the drying temperature does not exceed 130°C to avoid previous cross-linking. Avoid drying the hot cloth directly into the studio. Understand the compatibility of the water-repellent agent and prepare the working solution correctly according to the mixing sequence. The prepared working solution must be used within 24 hours.
⑶ The drying and baking temperatures should be uniform, and the baking temperature should not be too low, generally above 150°C.
Problem 2: Poor durability of water blocking agent
1. Reason:
⑴The finishing cloth is not washed enough.
⑵ The finishing conditions are particularly inconsistent with the baking conditions.
⑶The influence of cross-linking agent, resin and color fixing agent.
2. Main countermeasures;
⑴ Cloths colored with direct dyes or reactive dyes and then fixed must be washed thoroughly.
⑵Choose the appropriate cross-linking agent or resin and use it within the shelf life.
⑶Choose the appropriate water blocking agent and dosage to ensure durability.
Question 3: Water repellent stains
1. Reason:
⑴The working fluid has poor stability. This can be determined by observing the surface of the working fluid after high-speed stirring to see if there is scum on the roll.
⑵ Malignant bubbles may occur. This can be touched by hand. If it agglomerates and turns into scum, it is a malignant bubble.
2. Main countermeasures:
⑴ Pay attention to the temperature of the operating fluid not exceeding 35C.
⑵ When malignant bubbles are found, add stabilizer (isopropyl alcohol).
⑶Water blocking agent should be used within the shelf life.
Problem 4: Water-repellent streaks
1. Reason:
⑴The pre-treatment is uneven and the coloring is uneven.
⑵ Uneven rolling pressure causes uneven padding fluid.
⑶ The permeability of the working fluid is poor and the liquid flows down. This phenomenon is more common in fabrics with poor permeability such as high count, high density and thick fabrics.
2. Main countermeasures:
⑴ Ensure that all pre-treatment processes and coloring are uniform.
⑵ Use a uniform rolling car, and pay attention to cleaning the rolls and rolling grooves frequently.
⑶Choose a water-blocking agent with high permeability and a small amount of non-ionic penetrant.
Question 5: Color has changed a lot
1. Reason:
The main reason for the color change is the deepening effect of fluorine-containing resin. This is also a phenomenon that cannot be completely avoided during the water blocking finishing process. Discoloration is a normal phenomenon and usually becomes darker because a water-repellent film is formed on the surface, causing refraction, so the color looks darker.
2. Main countermeasures:
To solve the color change, you can confirm the degree of color change through preliminary tests, and then carry out color matching; when finishing, you can replenish the newly prepared working fluid in time (it is better to have an automatic liquid adding device) to prevent head and tail color differences.
The above is water blockingProblems that often occur during oil-proof finishing. We selected a variety of water-repellent and oil-repellent finishing agents for testing, and found that by adopting the above measures and selecting excellent water-repellent and oil-repellent finishing agents (such as Japan’s Meisei series water-repellent agents), the above problems were basically solved and the water-repellent and oil-repellent finishing agent was improved. Oil effect, high customer satisfaction rate for water-repellent orders. In short, choosing a suitable water-proof and oil-proof finishing agent will provide a good foundation for the water-proof and oil-proof finishing of the fabric; in the finishing process, the finishing cloth, working fluid and finishing conditions are necessary to obtain good water-proof and oil-proof effects. guarantee.
Problem 6: Bad hand feel
1. Reason
The main reason is that the water-blocking agent creates a water-blocking film on the surface of the fabric, which makes the fabric feel poor.
2. Main countermeasures:
⑴First of all, choose a water-blocking agent that can produce a soft feel. Each manufacturer has water-blocking agents that can produce different feels.
⑵ If the requirements are still not met, add some silicone softener and a small amount of surfactant. However, this will cause the water-draining performance of the water-blocking agent to decrease, and the more the amount is added, the more obvious it will be.
⑶ If it still doesn’t work, change the water repellent agent.
Question 7. Blistering
1reason
⑴Whether the water-repellent agent itself easily foams? Choose a water-repellent agent with low foaming.
⑵ Finish the remaining surfactants (dispersing/leveling agents, reducing soaping agents, etc.) and alkali on the fabric. Washing fabrics is key.
⑶ Matching softener and antistatic agent. Choose low-foaming type in full quantity.
2. Main countermeasures:
In addition to the above-mentioned countermeasures (1~3), it is planned to add an efficient and stable antifoaming agent with antifoaming properties to the working fluid.
Question 8. Roller sticking phenomenon
1. Reason
⑴ Continuously observe whether resin or viscous precipitation appears on the roller during the finishing process. If so, it can easily form water blocking spots.
⑵The stability of the water-blocking agent itself: Screen the water-blocking agent with high stability.
⑶Temperature: The water-blocking agent is an emulsion. Especially in summer, when the water temperature is high, the ambient temperature is high, and the temperature of the finishing fabric is also high, which continuously brings heat into the working fluid and causes the temperature of the working fluid to rise. At this time, the stability of the emulsion decreases, and fluorine resin is relatively simple. Separation (emulsification).
⑷pH: When the pH is higher than 7 and is alkaline, the stability of the water-blocking working fluid will decrease, and it is easy to break the emulsification and separate out and stick to the roller.
⑸ Mixing of dyes and auxiliaries: If the finishing fabric is not cleaned, the residual dyeing materials (mostly anions) will fall off into the working fluid and combine with the weak cationic water-repellent agent to cause the working fluid to be unstable.
⑹ Water quality: Only the filtered river water contains suspended solids or other substances depending on the season. When encountering weak cationic water-blocking agents, it is easy to combine or flocculate. It is strictly prohibited to use them when preparing working fluids.
⑺ Continuous roller extrusion and mechanical shearing: When the above problems (1-5) exist, the stability of the working fluid decreases. At this time, it is easier to break the emulsion and stick to the stick during continuous rolling mill extrusion.
⑻Using additives in the same bath: Pay attention to the ionicity of the added additives and whether the pH is opposite (for example, do not mix anionic acrylic resin and cationic water blocking agent). Melamine resin can be mixed with water-repellent agent, but be careful not to use it for a long time after preparation, because melamine resin will condense itself in the acidic water-repellent working fluid, especially at high temperatures, which is one of the factors that causes roller sticking.
2. Main countermeasures
⑴ Set up a condensation circulating water pipe in the rolling tank or add ice packs to cool down;
⑵Add acid to adjust the pH of the working solution to 5-6.
⑶ Finished fabrics should be thoroughly washed and contain almost no alkali, dyes or additives.
⑷Add additives to improve the heat resistance and mechanical shear resistance stability of the working fluid.
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