Outstanding Manufacturer of textile printing chemicals

as well as overall printing solutions provider

Keywords:

textile printing binder,textile pigment binder

adhesive for textile printing, adhesive for coating printing,

adhesive for pigment printing, pigment adhesive,

pigment printing adhesive, textile pigment printing adhesive

textile printing adhesive, textile coating adhesive

Discussion on the Types and Film Forming Mechanism of Adhesive for Textile Printing

The early adhesive for textile printing(here-in-after shorten as adhesive), in other name as textile printing binder or textile pigment binder, is some natural polymer plant glue or animal glue, although these substances have a certain adhesive force, but generally not washable, the product feels hard. The ideal adhesive requires that the film formed is colorless and transparent, and will not yellow after heating. The properties of the film are strong and elastic, strong adhesion, water washing and dry cleaning resistance, sun resistance and aging resistance; The processed fabric has soft film, good hand feel and no stickiness. But in fact, the daily use of adhesives can not all meet the above requirements. The application is generally based on the actual situation, sometimes several adhesives can be selected to be mixed, and the appropriate additives or additives can be selected to improve or adjust, in order to obtain better results.

1.Type of adhesive

Textile coating adhesives have developed to today, and have developed to the fourth generation of products. The first generation is non-cross-linked polymer film forming co-polymer, suitable for low temperature baking (100ºC); The second generation adhesive contains hydroxyl group, carboxyl group, amino group, cyanide group and other reactive groups, which can form covalent bond with hydroxyl group on fiber during heating, or react with additional cross-linking agent, so as to improve the application performance. The third generation of self-cross-linking adhesive added self-cross-linking monomer to the monomer, which improved the fastness of the printed fabric. The fourth-generation adhesive belongs to the low-temperature baking type, which can save about 90% energy and can be applied to the coating printing of fabrics that are not resistant to high temperature, but there are still some problems in cost and hand feel.

1.1 Score according to reaction performance

Commonly used adhesives can be divided into two categories according to their reaction properties.

1.1.1 Non-reactive adhesive

This type of adhesive does not react with either itself or with crosslinkers or fibers during the post-printing process. Non-reactive adhesives can be divided into the following categories.

1.1.1.1 Polyacrylate co-polymer

The commonly used adhesive is the copolymer of butyl acrylate and propylene cyanide, if butyl acrylate is used as a monomer to synthesize polypropylene butyl ester as a binder, the film is soft, the adhesion is good, the aging resistance is good, but the mechanical strength is not high, and easy to swelling; After the introduction of propylene cyanide in the molecular chain, the adhesive film feels hard, but the tensile strength, wear resistance and dry cleaning fastness of the film can be improved, and the co-polymer after their co-polymerization has the advantages of two components at the same time. For example, the glass transition temperature of polybutyl acrylate is about -56℃, and the glass transition temperature of polypropylene cyanide is about 104℃. Such a high glass transition temperature will cause the film to be very hard and not suitable for paint printing adhesives. The co-polymer of butyl acrylate containing 1l% acrylic cyanide has a glass transition temperature of about -25℃, and it still has a soft feel and other properties are better when used as an adhesive. This type of adhesive currently used has a variety of component ratios, the performance is not exactly the same, can be selected according to need.

1.1.1.2 Butadiene co-polymer

This kind of adhesive is mainly butadiene and styrene co-polymer, butadiene and propylene cyanide co-polymer, etc. With the change of copolymer components, the properties of co-polymer also change. When styrene components are introduced into the butadiene chain, the mechanical strength and elasticity of the copolymer are increased, while the softness is decreased. This can be seen from their glass transition temperature changes, for example, polybutadiene is about -85℃, polystyrene Tg is about 80 ~ 100℃, and butadiene and styrene ratio of 75:25 co-polymer Tg is about -60℃, between them both homo-polymers. Because the adhesive force of the styrene latex film is not good enough, some products also add a third monomer such as acrylic ester, acrylamide to improve, or mix some conjunctival substances with strong adhesive force to improve when printing.

1.1.1.3 Vinyl acetate co-polymer

Although polyvinyl acetate itself is a kind of adhesive, but not washable, hard performance, so it can not be used as a coating printing adhesive alone, if it is co-polymerized with other monomers, or modified, it can be used as a printing adhesive.

1.1.2 Reactive adhesive

Reactive adhesive is to introduce appropriate reactive groups in the molecular chain of the adhesive, so that the adhesive can be cross-linked or directly covalent with the fiber, forming a network structure, so that solvent resistance, heat resistance and elasticity

Greatly improved, friction fastness can also be improved. Binders containing reactive monomers mainly have the following categories.

1.1.2.1 Adhesive of amine monomer

A binder with an amino group in the molecule that reacts with an appropriate crosslinker to form a network structure.

1.1.2.2 Adhesive containing hydroxyl monomer

The amino group in the molecular chain can react with appropriate cross-linkers to form a network structure.

1.1.2.3 Adhesives that can cross-link themselves and react with fibers

Such adhesives contain self-cross-linking monomers such as methyl acrylate. The performance of the reactive adhesive varies with the properties of the monomer used and the co-polymerization ratio, for example, the glass transition temperature of ethyl acrylate and propylene cyanide co-polymer is about a -15 ~ 5℃, when ethyl acrylate is replaced by butyl acrylate, the glass transition temperature is about a -25 ~ 5℃, which is much lower than the former, and the corresponding tensile strength and heat resistance are correspondingly improved.

1.2 According to the dispersion in the water

According to the different dispersion state in water, there are roughly three types of paint printing adhesives, namely water-dispersed, oil, water and water/oil.

1.2.1 Water-dispersed adhesive

Such as alamine adhesive, film formation speed is fast, do not need high temperature baking.

1.2.2 Oil and water adhesive

Such as screen printing adhesive,like EM brand adhesive with item EM-453R and EM-F16A etc., which is characterized by simple preparation, easy to match color and convenient cleaning.

1.2.3 Water/oil adhesive

This kind of adhesive has the advantages of clear printing outline, good permeability, good feel, etc., but the pattern is poor in friction resistance, easy to burn, and organic solvents are used for cleaning, so it is rarely used in daily production.

2.Film forming mechanism of coating printing adhesive

2.1 Film forming process

In the film forming process of coating printing adhesive, it is basically a physical process in addition to the chemical process of the cross-linking agent and the self-cross-linking of the self-cross-linking adhesive. The physical state of the adhesive is different, and the film-forming mechanism is different.

2.1.1 Film forming process of water-dispersed adhesive

Alacmin adhesive is soluble in acetic acid and water, belongs to the water dispersion type, the polymer molecules are entangled with each other, the adhesive is dispersed in the state of the molecule in the solvent, with the evaporation of the solvent, the adhesive molecules further entangled with each other, thus forming a skin film. Film formation does not require too high temperature, as long as the solvent can be evaporated to form an ideal film, and the cross-linking agent also plays a cross-linking role in this process.

2.1.2 Film forming process of emulsion adhesive

The film forming mechanism of emulsion adhesive is relatively complicated. Because the polymer in the emulsion bonding is multi-molecular in the emulsion particles, the emulsion particles are dispersed in the water medium. Its film formation needs to go through the following three stages.

2.1.2.1 Evaporation of water

Adhesive As the water evaporates, the emulsion particles approach each other to form phase contact.

2.1.2.2 Deformation of emulsion particles

The capillary phenomenon occurs between the emulsion particles close to each other, the capillary pressure appears, and the capillary becomes thinner. The finer the capillary is, the greater the pressure is. When the capillary pressure is greater than the deformation resistance of the emulsion particles, the emulsion particles will be deformed.

2.1.2.3 Molecular diffusion film formation

The mutual diffusion of polymer molecules between emulsion particles deformed by capillary pressure causes the molecules to become entangled with each other, and the adjacent particles eventually become one, and finally form a dense and firm film.

2.2 The lowest temperature of film formation

The film formation of adhesive requires a minimum temperature, that is, the minimum film formation temperature MFT, which is affected by the composition of adhesive molecules and the structure of emulsion particles. When the temperature is lower than MFT, the emulsion particles lose their elasticity and have enough hardness to compete with the capillary pressure, which can not completely form a film and become a powder after complete drying. It is generally believed that the MFT of high polymers is similar to the glass transition temperature (Tg), so the formula for calculating the glass transition temperature of co-polymers is usually used to evaluate the minimum film forming temperature.

2.3 Minimum film forming time

In addition to the minimum film forming temperature, the emulsion adhesive has a minimum film forming time, which is the shortest time required for water evaporation and particle deformation, and its length mainly depends on the size of the emulsion particles, the external temperature and the water holding capacity of the emulsion particles. If the film forming speed of the emulsion adhesive is too fast, it is easy to lead to the plug of the net during printing. In this case, as long as a small amount of acrylic acid is added when the adhesive is synthesized, and the pH value of the emulsion is adjusted to the alkaline value when using ammonia water, it can play the role of holding water and delay the film forming speed.

3.Conclusion

The selection of different monomers to synthesize adhesives can get different functional products, these products both in solving the hand feel problem and washing, friction and other fastness problems, have more significant results, in the actual application process, according to the need to choose the right adhesive to ensure the production of relatively high quality products.