How to choose defoamer for textile auxiliary ?

How to choose defoamer for textile auxiliary ?

Introduction

 Large amount of foam is produced during the wet processing of textile dyeing and finishing because of the using textile auxiliaries, which affect the production operation, the production capacity go down, product quality would be degraded.  Therefore, it must remove the harm ful foam from the textile processing. By the way, it has been proved that adding defoamer is the best efficient way to eliminate foam in the textile processing.

The following are some of our experiences in the development and customer service and how to use defoamers for textile printing and dyeing?

Development of defoamer for textile

? The demand of defoamer for textile

(1) As end user of textile factory, usually evaluate the product quality by trial on the machine. So defoamer must meet:

--Viscosity should not be too high, and defoamer is easy to use, easy to control the addition amount, cost-effective, and fast defoaming.

--Has long-lasting anti-foaming, good dispersibility, no bleaching, no silicon spots, safe and non-toxic, and meets environmental protection requirements.

--Stable quality, and manufacturer can support technically.

On the other hand, it has been proved that the defoamer should has good dispersibility, high temperature resistance, acid and alkali resistance, electrolyte resistance, shear resistance, compatibility with various dyeing materials.

? Development of defoamer for textile

There are many kinds of defoamers, which are usually classified into silicon and non-silicon.

(1) Non-silicone defoamer: mostly single components, such as isooctyl alcohol, soap tablets, tributyl phosphate, kerosene and polyether. It is also possible to compound several ingredients to improve efficacy. The use of emulsifiers such as fatty acids and esters to emulsifie fatty alcohols, fatty acid amides, polyethers and mineral oils into aqueous emulsions is also a commonly used defoaming agent.

(2)  Silicone defoamer: We classify the silicone emulsion defoamer according to the emulsifying system and processing method:

-- Emulsifying system based on silicone oil and food grade emulsifier, produced by reverse phase processing method Defoamers are called S series defoamers.

-- Emulsification system based on modified polyether, silicone oil and food grade emulsifier, and defoaming agent produced by reverse phase processing method is called T series defoamer.

-- Emulsifying system based on polyether modified silicone oil, the defoaming agent produced by reverse phase processing method is called X/C series defoaming agent.

Dimethyl silicone oil, specific silica as the main defoaming component, a variety of nonionic surfactants as emulsifier, according to defoaming mechanism, compounding principle and emulsification technology, dimethyl silicone oil and specific silica The ratio of the ratio, the amount of the emulsifier, the amount of the thickener, the order of the addition, etc. to the performance of the product were studied to determine the optimum process conditions for the compounding. The antifoaming agent developed has good high temperature resistance, defoaming property and foam suppression. Sex and stability, and the equipment and production process are simple.

The raw materials used are: dimethyl silicone oil, liquid hydrocarbon oil, polyether modified silicone oil, silica, specific silica, emulsifier, Span-60, Tween-60, Span-8O, Tween-80, polyvinyl alcohol. Commercial products such as cetyl alcohol, stearyl alcohol, cellulose and sodium alginate. The silicone emulsion type defoamer manufacturing process is divided into 3 steps:

·  The preparation of a silicone paste. A certain amount of polydimethylsiloxane (hereinafter referred to as silicone oil) having different viscosity, activated silica, modifier and catalyst are stirred and reacted at 120 to 210 ° C for 2 to 4 hours, and after cooling, the main defoaming component is obtained. Formulated silicone paste. The emulsifier is added to dissolve in the oil phase, and the mixture is heated and stirred uniformly, that is, the self-emulsified defoamer compound is obtained. The selection and ratio of the main antifoam component polysiloxane, silica, modifier and catalyst are the key to the performance of the silicone emulsion defoamer.

·  Preparation of the initial emulsion. The emulsifier is dissolved in the oil phase, the thickener is dissolved in water, and the phase inversion method is carried out by adding water to the oil to control the emulsification temperature, time and stirring speed, and the initial emulsion is obtained after cooling.The emulsifier is dissolved in the oil phase, and the aqueous phase is added to the oil phase in the order of addition to obtain an emulsion having uniform particles and stable quality. Polysiloxanes are difficult to emulsify, so the correct choice of emulsifier is the key to emulsification. The chemical structure of the Span and Tween surfactants is similar to that of the emulsified dimethyl silicone oil, and the combination effect is good.

·  Compounding operation. Under stirring, an antifoaming agent, a foam suppressing synergist and an aqueous solution of a thickener are added. The preservative is emulsified in a primary emulsion by a high shear emulsifier for a certain period of time to obtain a product.Commonly used thickeners are polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, hydroxy cellulose and acrylic polymers, each having its own advantages and disadvantages, and should be selected for different emulsifying systems and application environments.

At present, several technical difficulties in the development of silicone emulsion defoamers are: the development of quick-breaking, anti-foaming and long-lasting silicone paste; the design and synthesis of low-foaming, non-foaming emulsion systems, especially modified silyl ether emulsifiers. Selection; emulsion particle size and stability control; high temperature, alkali resistant, easy to disperse emulsion system development.

? How to evaluate Textile defoamer

At present, there is no uniform standard for the performance test of textile printing and dyeing defoaming agents, that is, there is no national standard and no standard, and all enterprises are self-determined enterprises. The performance test method of textile printing and dyeing defoamer is the focus of defoamer developers, auxiliary companies and factory users. As the basis for the organization of production, sales and inspection, the industry consensus standards have yet to be formed. The following describes the performance test method of textile printing and dyeing defoaming agent, and hopes to play a certain role in promoting the standardization of auxiliary products in the industry.

3.1 Technical requirements for textile printing and defoaming agent

·  Appearance: The liquid antifoaming agent is a white to slightly yellow uniform emulsion liquid. The powdery solid antifoaming agent is a powder having a certain fluidity.

·  Physical and chemical indicators:

3.2 Test methods

·  Appearance: Visual inspection.

·  Determination of pH: Weigh 1g sample (accurate to 0.1mg) in a 100mL volumetric flask, dilute to the mark with water, shake well, and measure the pH value according to GB/T6368.

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·  Centrifugal stability: The defoaming agent was centrifuged on a centrifuge of 3000 r/min for 30 min, and the stratification was observed.

·  Stability: 2 g of defoamer sample was placed in a small test tube and diluted 10 times with water, immersed in boiling water for 1 hour, and its thermal stability was measured.

·  Non-volatile content: Weigh about 2g (accurate to 0.1mg) sample in the evaporating dish of clean constant weight W0, dry in the oven at 105 (±2) °C for 3h, then take it out and put it into the dryer. After cooling for 30 min, W2 was weighed. W2—W0 non-volatile content X%=×100W1—W0 where W0—glass evaporating dish weight, W1—sample and glass evaporating dish before baking, W2—sample and glass evaporating dish after baking weight, twice The difference between the parallel measurements should be ≤0.5%, and the average of the two parallel measurements is the test result. The drying method is suitable for most defoamers, but there are some exceptions. Sometimes the non-volatile content, also known as the solid content, in fact, the two are different, and the effective substance content can not be equal. As for some factories that use a sugar meter to detect solid content, there is no scientific reason. The sugar meter measures the refractive index and corresponds to a substance or a stable quality auxiliary product. The reading on the sugar meter is certain. It is used to identify the product or determine the quality stability of the product. It can be used. . 3.2.6 Defoaming and antifoaming performance: At present, the defoaming performance testing methods commonly used in domestic textile industry laboratories include shock shake flask method, ventilation bubbling method, Ross-Mile method and washing machine method. The defoaming performance can be expressed by defoaming efficiency, defoaming time and defoaming half life, and the defoaming performance curve drawn for the foaming system is more specific.

1) Determination by shaking shake flask method. Add 20 mL of aqueous solution of the tested foaming system (such as 1% sodium dodecylbenzene sulfonate solution) to a 100 mL stoppered cylinder at room temperature, shake it for 30 times, and then add a certain amount of defoaming solution. The stopwatch was started, the initial foam volume V0 was recorded, the foam volume was reduced by half (i.e., the defoaming half-life) and the foam volume V1 after 300 s, and the time required for the foam to completely disappear was recorded. After the foaming foam did not significantly decrease or oscillate for the first time for 45 min., the plug cylinder was again shaken 30 times, the instantaneous foam volume V2 was recorded, and the time required for the foam to completely disappear was recorded. Defoaming efficiency = (V0 - V1) / V0 × 100% inhibition efficiency = (V0 - V2) / V0 × 100% high defoaming efficiency, high foam suppression efficiency, short defoaming time, good defoaming effect. As the number of oscillations increases and the time required to add the defoamer increases, the time required for the foam to completely disappear is also longer.

2) Ventilation bubbling method: a gas at a certain flow rate is passed through a glass sand filter, and the filter plate contains a certain amount of test solution; the gas forms a foam in the container (scale cylinder) after passing through the filter plate. When the flow rate of the gas is fixed and the same instrument is used, the foam generation and destruction at the time of flow balance are in dynamic equilibrium, so this method includes both defoaming and suds suppressing properties.

For example, weigh 0.1g of the sample (accurate to 0.1mg), add 10ml of water and dilute well, then get the antifoaming agent dilution. Weigh 1.0g (accurate to 0.1mg) sodium dodecylbenzene sulfonate into a 1000ml beaker, add 400ml water and carefully stir until completely dissolved, then put the beaker into a constant temperature water bath, keep warm to a certain temperature, and then The bubbler bubble head was placed in the bottom of the solution in the beaker, and bubbling was started at 2 L/min. When the foam is to the mouth of the cup, the defoamer dilution is added quickly and evenly, and the stopwatch is started at the same time, and the time when the foam disappears to the liquid surface is recorded, and the foam is again raised to 600 ml, 800 ml, 1000 ml and the mouth of the cup. The time when the foam disappears to the liquid surface is the defoaming time, the defoaming time is short, and the defoaming effect is good. The time when the foam rose again to 800 ml was used as the foam suppression time, the time was long, and the foam suppression efficiency was high. 3) Ross-Mile foam method: In the production and laboratory, the “pour method” for measuring the foam performance conveniently and accurately is also the agitation method, and the instrument is “Roche foam meter”.

A small amount of test solution (50 ml) was placed in the thick tube, and 200 ml of the test solution was also placed in the foam pipette. Constant temperature water is introduced into the outer casing to allow the test to be carried out under specified temperature conditions. During the test, 200 ml of the test solution was freely flowed from the upper part of the thick tube, and foam was generated after impacting the bottom test solution. A certain amount of antifoaming agent was added to the prescribed foaming liquid, and the height of the foam generated when the defoaming agent was added to the foaming liquid and the defoaming agent was not added was measured by a Roche foaming apparatus. Generally, the foam height (mm) after 5 minutes of the test liquid flow is used as a measure of the foaming ability; but it is also often expressed by the time required for the initial foam height and the foam to break half (ie, the foam height is half of the initial height). Foaming and foam stability.

4) Washing machine method: In the production and laboratory, there is also a drum washing machine with heating to evaluate the foaming performance of the defoaming agent. The above four measurement methods are each focused on each other and can be determined according to the actual application process and the applicable environment.

·  Other performance:

--Defoamer dispersibility in water: Under stirring, 90 g of process water was slowly added to a beaker containing 10 g of defoamer, and gently shaken to observe its dispersion in water (excellent: rapid diffusion; medium: most of the dispersion was slow, and a small amount of flocculent The material is more difficult to disperse; poor: not easy to disperse, and the floc is difficult to disappear, the cup wall has oil).

-- High temperature resistance (high temperature and high pressure cooking test). Take a certain amount of defoamer YAT722 in a beaker, dilute it evenly with about 4 times of water, and cook in a pressure cooker. When the temperature rises to 130 °C, start timing, cook at constant temperature and constant pressure for 2 hours, cool down to room temperature. The sample was taken out to observe the high temperature and high pressure resistance (130±2 ° C, 2 h) performance and the presence or absence of delamination and oil droplets drifting out.

--Shear resistance (high shear resistance test). 100 mL of the sample was taken, diluted with water to 500 mL with stirring, heated to 85 ° C and 95 ° C, respectively, and sheared at 3000 rpm for 1 hr under a high speed shearing machine to stop shearing, and the oily condition was observed.

--Electrolyte resistance, acid and alkali resistance, compatibility and viscosity, etc., can be contracted according to the actual application process and applicable environment of the customer.

Selection of defoamer in different processes

4.1 High-efficiency fiber oil defoamer

In the production and use of fiber oils, there are usually foam problems. Since the oil component contains a plurality of surfactants and has a certain superfoaming property, a large amount of foam is generated during the compound production of the oil agent, resulting in an increase in the volume of the entire oil system, and the oil agent device cannot be produced at full capacity. At the same time, it also brings trouble to the packaging process. The problem caused by the foam during the use of the oil agent is even greater. The oil emulsion is more likely to foam when it is delivered, and the foam overflow not only causes waste of resources. Moreover, the working environment is polluted, and a large amount of foam surrounds the fiber crimping head, so that the heat of the crimping motor cannot be dissipated in time, causing damage to the motor.

In the oiling process of acrylic fiber production, a large amount of foam is generated due to the application of the oil agent. These foams can affect the quality of the product, reduce the production capacity, and even hinder the normal production of the product. Therefore, it is often suppressed and eliminated by using a bubble inhibitor. The silicon-containing polyether is used as a defoaming main agent with a mass fraction of 6% to 8%, and a suitable ether emulsified dispersant with a mass fraction of 8%-10% and a balance of petroleum hydrocarbon solvent to prepare a brazing oil defoaming agent. Its defoaming efficiency is over 70%. In the acrylic fiber factory spinning car asked for trial use, the defoamer water emulsion was added to the spinning oil tank, the foam suppressant has a long foam suppression time, fast defoaming speed, no foaming phenomenon, product stability, no drift Oil, high temperature resistance, low cost, etc., there is no foam wrap around the tow of the tow, and the production is normal.

4.2 Desiccant such as slurry, binder and flocking adhesive

If foam is generated in the slurry, it will cause great difficulty in the sizing operation, and the quality of the sizing is also affected. Therefore, in this case, a small amount of antifoaming agent is added to the slurry to suppress the generation of foam. The reasons for foaming of the slurry are physical foaming and chemical foaming. The reason for the physical foaming is that the stirring speed is too fast or the temperature rises too fast, high and low when the pulp is adjusted. The reason for the chemical foaming is that the protein content in the starch is high, and the inorganic salt in the water such as the acid carbonate Ca(HCO) 2 is also easy to foam after heating, and the partial alcoholysis type PVA has a high acetate content in the alkaline pulp. Foam is also produced, and the essence of their foaming is that the gas phase is dispersed in the liquid phase, and CO2 gas is selected. Silicone emulsion type defoamers are widely used in acrylate-based pastes.

In the process of using PVA dissolved in water, a large amount of foam will be generated. It is necessary to try to destroy the foam or prevent the generation of foam. By analyzing the cause of PVA dissolution in water, selecting a suitable defoaming method and selecting suitable defoaming method. The agent is added dropwise in the PVA sample, the PVA swelling process, and the PVA dissolution process to dissolve and defoam, which can solve the problem that the PVA dissolves in water to generate foam. Printing paste is a complex dispersion including: emulsions (adhesives, emulsified pastes), suspensions (coating syrups), inorganic salts (catalysts and reducing agents), and resins and water. Since the dispersion has a certain amount of surfactant, water, auxiliary agent, etc., a large amount of bubbles are generated when the flower cylinder is pressed during the printing process, so that the fabric produces white spots, spots, uneven flower colors, blurred colors, etc. Quality issues. In addition, the main component binder of the printing paste also generates a large amount of foam during the polymerization production process, which affects the effective capacity of the production container and causes production loss. Therefore, both processes must incorporate an effective defoamer, and silicone emulsion defoamers can achieve better results. The characteristics of the paint printing process require that the defoaming agent not only has excellent defoaming and antifoaming effect, but also has good compatibility with the printing paste, and can not affect the leveling property of the printing paste, otherwise it will affect the smoothness of the surface and produce "fish eyes". ", "shrinking holes" and other issues. The most effective way to measure the performance of a printing paste defoamer is the squeegee test. The emulsion type defoamer can meet the requirements of the printing paste.

In recent years, some domestic manufacturers have developed translucent micro-emulsified acrylate flocking glue. Non-silicone mineral oil-based defoamers affect product transparency, do not last long, and use is limited, while silicone emulsion defoamers have obvious advantages. 4.3 pre-treatment - low foaming scouring agent manufacturing

There are two ways to reduce the foaming of the scouring agent: one is to add a suds suppressor to the scouring agent to obtain a low foaming effect; the other is to use a low foaming surfactant component to obtain a low foaming effect. In recent years, due to the development of scouring agents and penetrants to high alkali resistance and the use of OP-10, domestic scouring agents are generally composed of sodium phosphate, SAS, small amounts of nonionic surfactants and defoamers. Based on the recipe. The price of isomeric alcohols in phosphate raw materials is soaring. Many factories turn to natural alcohols. The price of P2O5 is much lower than that of alcohols. Therefore, many factories use natural alcohol ethers in the synthesis of phosphate esters, and use P2O5 too high to produce scouring agents and infiltration. Not only does the agent have reduced penetration, but also more foam, and the cost of the defoamer cannot be increased, which poses a challenge to the defoamer.

The low-bubble scouring agent uses a defoaming agent to undergo rigorous experiments, and undergoes three experimental stages of compounding primary selection, storage stability and alkali stability. After the preliminary selection of the defoaming agent is added to the scouring agent base formula according to a certain amount, the appearance of the scouring agent should be observed whether there is bleaching oil, flocculation and precipitation, and the defoaming performance is measured. There is no obvious influence on the appearance of the scouring agent. The storage stability test can be carried out. The scouring agent with the quantitative antifoaming agent is stored at room temperature for two weeks, and then the presence or absence of bleaching oil, flocculation and precipitation is observed, and the defoaming performance is measured. Finally, the alkali stability was measured, and a scouring agent to which a quantitative antifoaming agent was added was added to 120 g/L of the lye in 1.5 g/L, heated to 85 ° C, and bubbled to measure the foam properties. At present, in many unit experiments, the scouring agent samples are also selected with the emulsifier OP-10 and sodium alkylbenzene sulfonate as the main component, which is very unrealistic.

4.4 Dyeing - Defoamer for high temperature overflow

In the case of high-temperature jet dyeing of polyester fabrics, in order to achieve levelness, the fabric must be run at high speed in the machine. If the foam is present, it is very easy to cause uneven dyeing and staining. To this end, some high temperature and shear resistant defoaming agents must be added to the dyeing solution to quickly eliminate the foam in a short time.

For the requirements of dyeing and finishing manufacturers, we developed and produced high concentration high temperature and strong alkali defoaming agent YAT722. After testing in the printing and dyeing processing industry, we found that the defoaming agent YAT722 is resistant to high temperature (130 ° C), strong alkali resistance, defoaming and foam suppression. At the same time, it has excellent self-emulsification performance, high shear resistance and no bleaching oil, and is especially suitable for high temperature overflow dyeing process in textile industry.

4.5 finishing - softener, film defoamer

In the finishing softener, the foam is reduced. First, in the preparation of the softener emulsion in the soft film (paste), an antifoaming agent is added to eliminate the foam or obtain a low foaming effect; and the second is to use a low foaming film (paste) to obtain a low foaming effect. Tests have shown that the softeners obtained by the former can maintain better low foaming properties, and the cost can be reduced by using a suitable antifoaming agent. The low foaming film (paste) is simply an antifoaming agent added before the film is prepared, and the antifoaming ability of the defoaming agent contained in the production and storage process is lowered.

5 how to use defoamer correctly

5.1 Factors to be considered when using defoamer

In actual operation, there are often too many foams to form a phenomenon of entanglement, blocking of the cylinder or cloth, and the addition of a defoaming agent can solve the problem. Defoamers are acid-resistant, alkali-resistant, and not resistant to high temperatures. Either of them contains silicone oil, which will break the emulsion in an unreasonable or certain environment to form silicone oil. Be careful when using it. If the dosage is less, the effect will not be achieved. If the dosage is too much, it will cause pollution. You should choose the best amount. The more silicone oil is used, the more it is recommended. The defoamer should be thoroughly diluted with a large amount of water during operation and filtered into the tank. Only the correct use can guarantee the quality and avoid oil spots.

Thousands of chemicals are available as defoamers either alone or in combination. Therefore, before choosing an antifoaming agent, you should seek expert advice. When using defoamers, a number of variables should also be considered, including regulatory requirements, product availability, production costs, and supplier services. Defoamer products should be properly formulated. In addition to foam inhibition, the impact on the product should be minimized in the use environment. In general, the smaller the amount of defoamer, the lower the effect on the product. Try to use non-foaming or low-foaming additives. The so-called non-foaming additives, in fact, suppliers have added defoamers before the sale. Use a suitable defoamer to make it cheap and of good quality.

5.2 Reasonable dilution of silicone defoamer

The silicone antifoam concentrate/emulsion must be pre-diluted with cold water (less than 30 ° C). Add cold water in the steps and stir thoroughly to avoid uneven distribution. If the hardness of the cold water is high, it will result in uneven dilution or agglomeration of the emulsion, both of which may cause the silicone to precipitate on the fabric or mechanical parts. A cellulose thickener thickener system is added to stabilize the diluted antifoam emulsion. If the diluted product is left for too long, it should also be added with a fungicide to prevent spoilage, especially in the hot season.

5.3 Avoid silicone formation on the fabric or deposit on the device

First, production trials and laboratory trials should be conducted to determine the minimum amount of defoamer needed to effectively inhibit foam. It is necessary to avoid excessive doses in order to achieve low cost and high performance.

Second, good process conditions such as temperature, pH, other raw materials and electrolyte concentrations, and shear forces should be ensured. The stability of the defoamer system should be tested in the laboratory under the above conditions before being put into production. Even after dilution, the defoamer cannot be added directly to the thermal processing.

When high temperature demulsification occurs when used improperly, it can also cause serious oil stains. Silicone oil stains are difficult to handle, and can only be removed with alkali and emulsifier. Generally, only special "silicone oil" or "de-oil" can be purchased for scrubbing. A larger area can be scoured with a net amount of silicone oil l0g / L plus an appropriate amount of caustic soda.

Our professional production of Lima defoamer not only guarantees the quality, but also has a team of textile printing and dyeing experts, which can provide customers with perfect after-sales service and timely and effective technical support. With a higher price/performance ratio. It has good dispersibility, high temperature resistance, acid and alkali resistance, electrolyte resistance, shear resistance, good compatibility with various dyeing materials, no bleaching oil, no silicon spot; safe and non-toxic, no alkylphenol ether (APEO) It meets the environmental requirements and is suitable for viscosity and concentration. It is easy to use and dilute, and can meet the needs of various processes and additives in the printing and dyeing industry.

In short, the performance of defoamers is the first consideration of printing and dyeing plants, and high-efficiency and stable defoamers can be accepted by the market.