Characteristics And Production Technology Of Artificial Leather Release Paper

Artificial leather release paper is a special anti sticking paper. Its coating usually has concave convex pattern structure.

It is widely used in artificial leather and synthetic leather industry. As the carrier of synthetic leather and synthetic leather production, artificial leather release paper can copy the patterns stamped on it to synthetic leather and synthetic leather.

The demand paper for our country depends mainly on imports.

1 Characteristics of new artificial leather release paper

1.1 machine classification and its basic structure

The main classification methods for artificial leather release paper are as follows:

1 according to usage classification, it can be divided into PVC artificial leather paper and polyurethane leather paper.

Peroxy 2 can be classified into plane paper and embossed paper according to pattern classification.

Peroxide 3 according to glossiness classification can be divided into high gloss bright semi glossy semi dull extinction extinction type.

Peroxy 4 can be classified into silicon paper and non silicon paper according to the classification of coating materials.

Peroxide release paper is a coated paper, which is usually composed of paper base and off coating layer. Its basic structure is not much different from the ordinary coated paper. The main difference is that the coating has concave convex pattern structure.

1.2 machine application

In the process of producing artificial leather, the artificial leather paste resin is coated on the surface of the release paper, then dried, cross-linked and solidified, and then stripped off the release paper to obtain a smooth or concave pattern artificial leather release paper.

During this process, the oven temperature should be subjected to 160~210 degrees Celsius.

It mainly plays the role of embossing.

Unlike other production processes, it does not use pressed rollers to suppress the pattern of artificial leather. Generally, the release paper can be reused 6~10 times.

1.3 machine performance requirements

1.3.1 machine strength

The strength of peroxide release paper has great influence on the smooth operation of artificial leather production and the frequency of paper usage. Because the temperature of oven drying is higher when the leather paste resin is coated, the strength of the release paper must be sufficient in the repeated use, and the most important strength is tear strength.

When the split paper has a crack in the width direction, it must be able to bear certain tear load, and its surface strength requirement is higher. It requires that the heating surface is generally used for more than 6 times, and the curling surface does not produce the powder without damage.

Heat resistance of 1.3.2

The peroxide release paper must be used at a higher temperature. At this point, the release paper is near dry state. If its heat resistance is not good, it will tear down due to the decrease of strength after the high temperature production process, and it will also lead to the production interruption.

The difference of oven temperature between PVC and PU artificial leather process, so the release paper used for general PVC artificial leather is able to withstand the highest temperature of 240 C, while the release paper for polyurethane artificial leather requires the highest temperature of 150 C.

Solvent resistance of 1.3.3

Peroxide is often used in the production of synthetic leather, especially in the production process of PU leather. Organic solvents are often used in production process. The process requires that the release paper should not be affected by solvents, so that it is neither soluble nor swollen.

The commonly used solvents in artificial leather production are two armor.

Methyl formamide, methyl ethyl ketone toluene, xylene, ethyl acetate, etc.

Peel strength of 1.3.4 machine

The stripping strength of peroxide paper should be properly stripped.

If stripping is too difficult, it will affect the reuse times of paper. If peeling is too easy, it will cause pre stripping in the process of artificial leather production.

For difficult to peel type synthetic leather resin, the peel strength of the release paper is lower than that of the artificial leather resin.

1.3.5 machine is flexible.

Peroxy because of the small guide roller in the process of coating the artificial leather paste, the release paper must have some flexibility, which can improve the number of reusable paper and avoid the damage of the pattern on the paper.

Some of the quality indexes of artificial leather release paper at home and abroad are as follows:

The peroxide value is greater than or equal to 155g/m2, the tightness is less than 1.0g/cm3, the lateral tear degree is greater than 1.1N, the longitudinal tensile force is more than 100N, the peel strength is 20 to 25N/m, the gloss (flat sheet) is 3.5% to 85% (75 degrees), and the moisture is 4%.

2 production process of new artificial leather release paper

The production technology of the peroxide artificial leather release paper is mainly composed of three parts: the original paper type coating and the embossing.

2.1 machine base paper

The peroxide release paper has a higher requirement for the base paper, that is, the base of the paper. It not only requires high strength, but also has strict requirements for heat resistance, loose thickness and moisture content.

In terms of raw paper quantification, 125g/m2 is usually used for paper production. The technical difficulty lies in controlling the thickness and heat resistance of the base paper.

In terms of loosening thickness, softwood pulp and hardwood pulp are commonly used to control the heat resistance. The heat resistance agent is added to the slurry to enhance the heat resistance of the paper.

2.2 machine release coating

The coating of oxygen release coating can be divided into two main categories, namely silicon based coating layer and non silicon type coating layer.

Silicone release materials include silicone resin and alkyd resin modified silicone resin.

Non silicon release materials include chromium complex, methacrylic acid or fatty acid type polypropylene resin, polymethylolefin resin TPX and other special resin amino alkyd resin, epoxy resin and so on.

Different types of oxygen release coatings have different characteristics. For example, silicone resin coating has excellent peel and heat resistance. Chromium complex coating has poor solvent resistance, polypropylene coating has high gloss but poor heat resistance.

Different types of coating are also different in technology. Silicone coating is usually coated with roller or scraper, and the base paper must be primed first.

The main purpose of primer is to improve smoothness and resistance to penetration of silicone coatings.

Polypropylene resin and polymethylolefin resin coating is mainly made by extrusion coating. The raw paper used in the coating can not be primed. The other components in the coating are fed through the feeding trough of the extruder. These coating technologies involve the control of the strength of the coating peeling, which is also the technical difficulty.

This also involves the selection of the peel strength control agent and its effect on other properties of the coating.

2.3 machine embossing

The pattern on the oxygen release paper is usually pressed by the embossing rollers. The embossing technology can be divided into the conventional embossing process and the special embossing process.

The conventional embossing process is also divided into the traditional embossing roll pressing process and the use of the gear driven embossing and the pressure roller, that is, the roller is driven by the roll.

The special embossing process mainly refers to the concave coating embossing process, which is used to make clear and lifelike advanced paper.

At present, only the US Sappi Warren Company has adopted the off type coating used in this process as the embossing process of the electron beam curing resin.