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
Ø 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.
Ø 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.
Ø 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.
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