Introduce Flocking Printing Technology And Fabric Knowledge

1、 Flocking fabric analysis

In order to carry out various printing on flocking cloth, it is necessary to have a comprehensive understanding of the structure and performance of flocking cloth.

Flocking cloth is a product that uses high-voltage electrostatic field to plant short fibers on the grey cloth, that is, printing adhesive on the surface of the substrate, and then using a certain voltage electrostatic field to vertically accelerate the short fibers to plant on the grey cloth coated with adhesive. Although its processing process is simple, it also involves the reasonable cooperation of electrochemical, fiber and mechanical technologies to ensure the best style of flocking products. The flocking cloth needs to be re printed, in which fluff, adhesive and fluff dyed dyestuff Your choice is critical.

1. Pile

From the perspective of flocking, the most commonly used fluff is viscose and nylon fiber. Viscose fiber is made from wood through certain chemical processing. The crystal area of the fiber is 30-40%, and the polymerization degree is about 250-500. Because the crystal area of viscose fiber is high, the dye is not easy to penetrate. Generally, it is difficult to obtain good blackness when dyeing black, so special dyes and dyeing methods must be used. At the same time, because of its low degree of polymerization, the fiber strength is far less than nylon. Generally, the dyes suitable for viscose fiber are direct, reactive, vulcanizing, etc. Naftol is also OK, but it is seldom used. Viscose does not soften and melt at high temperature, and it starts to change color at 260~300 ℃.

nylon fibre It is a high molecular material with organic diacid, diamine amino acid or propionamide as raw materials connected by amide bond. Nylon fiber has good elasticity, high strength, wear resistance and durability. It is a thermoplastic fiber, commonly used nylon 6 and nylon 66. Nylon fiber has good elasticity and luster, but nylon 66 will turn yellow at 150 ℃, become sticky and soft at 230 ℃, and melt at 250 ℃; Nylon 6 is softened at 180 ℃ and melted at 215 ℃. Therefore, in the process of wool dyeing, flocking and printing, it is necessary to find out what kind of fiber it is before selecting dyes and processes correctly according to its performance, so as to avoid unnecessary losses in the process.

2. Adhesive

The adhesive used for flocking plays an important role in the post dyeing processing industry. The commonly used adhesives are divided into diplomatic adhesive and self crosslinking adhesive. Diplomatic adhesive contains carboxyl group (- C00H) or amide group (- C-NH2), amino group (- NH3) and other groups that can cross link with the functional group of the external crosslinking agent in its molecule. When forming the film, it can react with the external glue to form a reticular skin film, so as to fix the villus on the base cloth.

Self crosslinking adhesive is a kind of adhesive that contains a group in the molecule that makes the molecular chain self crosslinking, such as hydroxymethyl (- CH2-OH), epoxy (- CH-CH2), and also has a hydroxymethyl acrylamide (CH2=CH-CONHCH2OH) or epoxy propyl methacrylate (CH2=C-COOCH2-CH-CH2) that can participate in copolymerization with other monomers to open the double bond and participate in the reaction.

At present, both of these adhesives are used in flocking. A certain amount of crosslinking agent and catalyst should be added to the diplomatic union adhesive when it is used, but it must be used immediately after the preparation, especially after the catalyst is added, it should not be left for too long, otherwise it will also cross link at room temperature and affect the use, which should be noted in the operation. The effective storage time of self crosslinking adhesive is relatively long. If a small amount of crosslinking agent is added during use, increasing the crosslinking depth will be more conducive to improving the flocking fastness.

What is the relationship between adhesive and flocking process and printing? Many factories devoted to flocking printing have some hair shedding due to the lack of matching processes. In addition to the fastness of the adhesive, the baking temperature and time of flocking are very important, that is, the adhesive must be fully cross-linked without damaging the fuzz. In general, there are several requirements for the selection of flocking adhesive:

1) The adhesive shall have a strong adhesion to grey cloth and fuzz and a soft feel.

2) The viscosity is moderate, and its chemical stability is good. It is suitable for scraping round screen without blocking the screen.

3) Washable and suitable for various clothing Index of fastness of used cloth.

4) Easy to operate, harmless to human body, it is a green environmental protection product.

3. Dyeing

Dyeing fluff is a very important link in flocking cloth. The color, physical and chemical indexes of dyed fluff must meet certain requirements.

From the perspective of flocking, the first thing to do is to meet the requirements of aligning the color light, and not recolor during the curing process after flocking. If printing is to be carried out after flocking, the dyed wool must be able to withstand the treatment of each process in the whole printing process, and the flocking cloth has good stability in steaming, hot water washing or soaping, as well as acid and alkali. If discharge printing is used, the dyes in the dyed fluff must not be resistant to reducing agents, which is very important for the selection of dyes during dyeing, otherwise the whiteness will be different each time. Even if the same printing process is used, different products will be obtained, so only some self selling products can be produced, and orders cannot be taken. This is a failure in flocking and printing. Generally speaking, the selection of dyeing dyes should meet the following requirements:

1) Color matching dyes have good compatibility and similar dyeing curves.

2) Various color fastness indexes of dyes meet customer requirements.

3) In discharge printing, the dyes used to dye fluff must not be resistant to reducing agents, and the whiteness should be good. Generally, semi discharge dyes cannot be used.

2、 Flocking cloth printing

For the re printing of flocking cloth, special printing such as pigment printing, foam printing, gold stamping printing, pearl printing, etc. has been quite extensive, and will not be detailed here. In this paper, the direct printing and drawing of vegetable flannelette with dyes are briefly introduced. {page_break}

Printing is a long process, which goes through the following processes:

The printed flocking cloth will be exposed to a series of processes such as chemical additives, high-temperature steaming, reduction washing, etc. The flocking cloth shall not be damaged in this process, which is the requirement for flocking cloth.

1. Direct printing:

According to the requirements of the pattern, different printing methods can be selected. Generally speaking, direct printing can be used to solve the problem, and discharge printing is not required, because discharge printing is more complex than direct printing, and its cost is relatively high. Direct printing of flocking cloth is generally carried out on flat screen or rotary screen printing machines.

2. Selection of dyes:

Viscose fluff can be carried out with direct dyes and reactive dyes printing 。 Direct dyes have simple process and complete color spectrum, but the color light is not bright enough and the color fastness is poor. At present, some direct dyes have good color fastness, but the price is high. Reactive dyes have complete color spectrum, good color brightness, and good color fastness. However, reactive dyes generally color under alkaline conditions, so improper process or operation will cause hair loss. Only a few reactive dyes are suitable for printing.

Nylon fluff has affinity for many dyes, and can be dyed directly, acidic, disperse and reactive. However, acid dyes, neutral dyes and a small amount of direct dyes are generally selected. There are also factories that use disperse dyes for light colors.

Therefore, each factory chooses according to its own different production conditions and customer requirements.

3. Process prescription:

4. Discharge printing:

Discharge printing of flocking cloth can be divided into white discharge and color discharge. White discharge is to use reducing agent to destroy the hair color group of the pattern part dyes on the flocking cloth and return the fuzz to its original appearance; Color discharge printing is to add reducing agent resistant dyes to the white discharge paste, so that the reducing agent can destroy the dye structure on the dyed fluff and reprint the required color to achieve the purpose of discharge printing. Here we only talk about discharge printing of nylon wool.

1) Dye selection

The color drawing dyes must be acid dyes or neutral dyes resistant to reducing agents.

2) Process prescription:

3、 Post finishing of flocked printed fabric

After steaming and washing (if the desizing is not clean after washing, the hand feeling of flocking printing will be poor, even if the softener is added, it will not help), the softener must be added, so that the fabric can get a better hand feel and sag. Softeners can be classified into large categories. At present, there are many kinds in the market, and even more numerous from manufacturers. It is really important to choose a good softener. At present, silicone softener, also called silicone oil, is widely used. It is suitable for viscose and nylon.

In a word, flocking printing has just started in China, making plain flocking cloth more colorful and dazzling. How to improve the output and quality of printed flocking cloth needs further discussion. A good processing method opens up a new field for the application of flocking cloth.

At present, the flocking process has expanded from the base fabric flocking to wool, plastic, wood, plate making, steel plate, non-woven fabric and other base materials, so its use has become more and more extensive, including decoration, cars, hotels, hall wallboards, clothing Clothes & Accessories And other fields have the footprints of flannelette.

With the development of high and new technology and the continuous development of new fibers, the source of fluff varieties has become increasingly widespread. For example, Modal fiber is a green fiber developed in recent years. It has strong wet strength and the wearability of viscose, and its cost is close to viscose fiber. If this kind of fiber fluff is applied to flocking, its abrasion resistance index will be greatly improved. Another example is Tencel's A100 fiber, which has both the water absorption of viscose fiber and the strength similar to polyester fiber. There are also some new blended synthetic fibers showing up. These new fibers will probably become new members of the flocking industry. With the continuous development of fluff, adhesive, flocking process and finishing process after printing and dyeing, flocking cloth will have a very broad prospect and far-reaching social benefits.