Views: 0 Author: Site Editor Publish Time: 2022-10-03 Origin: Site
The coating printing is to form a film on the surface of the fabric with the help of polymer polymer (adhesive), adheres to the fabric fiber without affinity and reactiveness, and then heats the coating color paste after heat treatment. , To give the fabric's various colors and patterns, which are suitable for all kinds of fiber and blended fabric printing; the coating prints are complete, easy to color, easy to adjust and control; The three -dimensional sense, the printing process is simple, the energy saves energy, and the production of wastewater is not produced, which greatly reduces the pollution of the printing and dyeing wastewater to the environment.
To this end, in the context of energy conservation and environmental protection, the development of textile coatings is getting better and better, so as to gradually replace the dye printing process with more sewage and high energy consumption. With the large -scale production of synthetic fibers and their blended fabrics, the application surface of the coating printing has continued to expand, and its ecological environmental protection performance has been continuously improved. The superiority of coatings printing is particularly prominent, which has become the mainstream of the development of textile printing at home and abroad.
1. The requirements of coating printing for adhesives
The coating printed color pulp is composed of coating color slurry (pigment color), polymer adhesive (film formula), printed thicker (printed carrier) and a small amount of additives. Because coating color slurry is solidified by a printing adhesive to a film and fiber, the performance of the adhesive plays an important role in the print; Indicates such as soap washing fastness, etc.) to a large extent depends on the quality and performance of the adhesive. Therefore, the development of textile coatings is directly related to the development of adhesives.
The conditions of high -quality coating printing adhesive:
(1) After the formation of the fabric is cured, it forms a tough and uniform skin film that is colorless, transparent, strong, and elastic;
(2) UV is resistant to ultraviolet rays, not yellowish, and aging;
(3) The skin film resistance, anti -folds, soft and non -sticky, not adsorbed non -colored substances;
(4) Cortical membrane -resistant organic solvents, not softening hair sticking;
(5) certain heat resistance and antifreeze;
(6) Good storage stability, the film formation cannot be too fast, the preparation of the printed color pulp is good, not condensed, printed paste, no roller/viscous sieve net printing;
(7) The compatibility of the stamp thickening agent is good, and the viscosity of the printed slurry is small.
2. The functional mechanism of the adhesive in the coating printing
The adhesive is the main ingredient of the coating printed color pulp, which is converged from various monomers. It sticks to the fabric through the action of film formation. Performance; Common adhesives are O/W Lotion, that is, the internal phase of the internal phase is a polymer particles, and the foreign minister is water. Under certain conditions, it can form a membrane on the fabric. The penetration and diffusion, the membrane deformation through the deformation of the emulsion particles; the film formation of the emulsion adhesive has the best film formation time. This time is the shortest time required for moisture evaporation and particle deformation; Make the coating color slurry sticking to the roller or blocking the sieve net without being conducive to printing, and even causing irreplaceable.
The minimum film temperature of different varieties of adhesive MFT (that is, the elastic polymer with elasticity in the emulsion particles can form a minimum temperature of a continuous film). This parameter is of great significance when the actual printing is higher than that of MFT. The soft polymer can be deformed by the capillary pressure; when it is lower than the MFT, the polymer has sufficient rigidity to resist the deformation caused by the capillary pressure of the capillary, which will not form a continuous membrane. It can be fixed at a lower temperature after printing.
3. Different monomers in the polymer different performance
After the adhesive is made of a film on the printing fabric, it has a certain mechanical rigidity, sufficient wear resistance, and must have a good adhesion for fiber. In addition, it is also related to the quality of the relative molecules. The performance reflected in the polymer of different monomers is also different.
4. Types and characteristics of adhesive
4.1 Adhesive type
There are many varieties and different properties. Generally, it can be divided into four categories. The solvent type adhesive and water dispersed adhesive are obtained through solution aggregation; the third category is made of emulsion -type adhesives and hot -melt -fused adhesives. According to the film formation component, it can be divided into acrylic adhesives, chloride rubber -type adhesives, and acetate ethyl acetate -type adhesives. Water -watery type (W/O) and water packaging (O/W); according to the temperature of the printing fabric, it is divided into low -temperature type, medium temperature roasted solid, and high -temperature roasting.
The development of coatings printing adhesive has undergone the update of several generations of products. From non -intersection, diplomatic connection, self -association to low -temperature binder, the second and third generations are suitable for medium -high temperature baking. Clean the baking intercourse at 140 ° C to 150 ° C, such as oxygenyl oxyded and hydroxylititride of oxyl acrylic, oxylceride, and hydroxylceride ether, which solves the problem of formaldehyde problem largely.
The communist of the diplomatic federation contains active groups such as hydroxyl, carboxyl, amino, and amide. During the heating process, it forms a covalent bond with the hydroxyl group on the fiber, or reacts with the cross -linked agent to improve the performance of the membrane and cooperate with emulsification Standard agent to improve the feel. There are many polymers of this type of polymer, such as acrylate and acrylite, ethyl acetate and other clusters. They have good adhesion, aging resistance, and their performance has changed greatly with the nature, dosage, and ratio of the ratio, such as Cryanide, acrylic methyl, acrylamide cluster, etc. of mesh adhesives.
Self -linked adhesives are mainly polymer clusters of acrylics. Lotion can introduce active monomers into the composition of adhesives; commonly used active monomers include hydroxyl acrylamide, hydroxyl (methyl base (methyl -based (methyl -based (methyl -based (methyl -based (methyl -based (methyl -based (methyl -based (methyl -based (methyl base ) Corrite, etherized hydroxymalhydrinamide, etc., which contain a certain number of cross -linking groups on the polymer molecular chain. During the heat treatment after printing The linear macromolecules form a mesh structure, which can improve the toughness of the skin film, so that the adhesive membrane will not bloating and washing resistance after the water is encountered, and the color fastness of the printed fabric is improved; The advantages of less, easy to feel, easy to migrate, good product and printed slurry stability, and good color fastness; good compatibility with synthetic thickening agent is more conducive to fabric printing such as blended and chemical fiber.
In the fourth -generation low -temperature adhesive, the active monomer of the crosslinker replaced the hydroxyl acyllamide that needs to be at high temperature cross -linking, or the monomer that can suck ultraviolet, infrared, and various radiation can be used. The agent achieves cross -linking at a lower temperature or under certain energy; in order to reduce costs, improve the water resistance, alkali, temperature resistance, pollution resistance and powder resistance of the adhesive, and the pyrics (ST) can be introduced. Replacement of commonly used methyl acrylic, but only ST can still not achieve the ideal effect; if the ethyl acetate (VAC) is used as a nucleus, the semi -continuous seed emulsion aggregation method can be obtained. The VAC/ST/BA nuclear shell structure emulsion adhesive is formed.
However, not all polymers can meet the requirements of coating printing in terms of feel, toughness, elasticity, transparency, mechanical strength, adhesion, especially printing performance, coloring fastness, and feel. The emulsion adhesive currently used in fabric coatings printed. According to its chemical structure, it mainly includes acrylics/pyrodinyl, butadiene, acrylite, acetate, and polyurethane; Lotion is the most common printing adhesive in China. The composition of well -known foreign adhesives include acrylics/acrylite cluster, acrylite butecin/acrylite/methyl acrocylite cluster, and styrene/butadiexyl. /Acrylic acid ester/etherized hydroxyl -alpha -aslidide cluster, etc.