Characteristics of Artificial Leather Release Paper and Its Production Technology

Artificial leather release paper is a special type of release paper, and its coating generally has a concave-convex pattern structure. It is widely used in artificial leather and synthetic leather industries as a carrier for synthetic leather and synthetic leather. Artificial leather release paper can copy the pattern embossed on it to artificial leather and synthetic leather. China's need for release paper mainly depends 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 the following:

1 It can be divided into polyvinyl chloride artificial leather paper and polyurethane leather paper according to the purpose

Peroxide 2 can be divided into flat paper and embossed paper according to the pattern classification

Peroxygen 3 According to the glossiness classification can be divided into high-light type bright semi-bright semi-extinction type extinction type super extinction type

Peroxygen 4 According to the coating material classification can be divided into silicon paper and non-silicon paper

Peroxide release paper is a type of coated paper. It is usually composed of a paper base layer and a release coating layer. Its basic structure is not much different from general coated paper. The main difference is that its coating surface has uneven patterns. structure.

1.2 Machine applications

In the production process of release paper-based artificial leather, the raw material of artificial leather paste resin is coated on the surface of release paper, dried, cross-linked and cured, and then peeled off from the release paper to be smooth or Embossed leather release paper. In this process, it is subjected to an oven temperature of about 160 to 210°C. Primarily plays the role of embossing. The difference with other production methods is that it does not use embossing rollers to suppress the pattern of artificial leather. In general, release paper can be reused 6 to 10 times.

1.3 machine performance requirements

1.3.1 Machine strength

The strength of peroxygen release paper has a great influence on the smooth operation of artificial leather production and the number of paper applications, because after the coating of leather paste resin, the temperature of drying into the oven is higher, so the release paper is Repeated use must have sufficient strength, the most important of which is tear strength. When the release paper has a gap in the width direction, it must be able to withstand a certain tearing load, and its surface strength is also required to be higher. It is required to use 6 or more times in the case of heating, without curling the surface, and not to lose powder and not be destroyed. .

1.3.2 Heat resistance

Peroxygen release papers are used at higher temperatures. At this time, release papers are almost dry. If they are not heat-resistant, they will tear due to the reduced strength after high-temperature production process, which will also lead to production. Interruption, so the release paper must have a higher heat resistance. In the PVC and PU artificial leather process, the oven temperature is different. Therefore, the release paper for general PVC artificial leather requires a maximum temperature of 240°C, while the release paper for polyurethane artificial leather requires a maximum temperature of 150°C.

1.3.3 Machine Solvent Resistance

Peroxide is often used in the production of artificial leather, especially in the production of PU leather. The process requires that the release paper should not be affected by the solvent, so as to be neither insoluble nor swellable. The commonly used solvents in the production of artificial leather include dimethylformamide, methyl ethyl ketone toluene, xylene and ethyl acetate.

1.3.4 machine peel strength

Peroxide release paper should have an appropriate peel strength. If the peeling is too difficult, it will affect the repeated use of the paper, if the peeling is too easy to cause pre-stripping during the production of artificial leather. For the hard-to-peel type artificial leather resin, the peel strength of the release paper is required to be lower, and for the peelable-type artificial leather resin, the peel strength is required to be higher.

1.3.5 machine a certain flexibility

Peroxide Because a small guide roller is used during the coating process of the artificial leather paste, the release paper must have a certain degree of flexibility, which can increase the number of repetitive use of the release paper, and can also avoid the pattern on the release paper being subjected to damage.

Some of the quality indicators for artificial leather release paper in the literature at home and abroad are as follows:

Peroxide basis weight ≥ 155g/m2, tightness ≤ 1.0g/cm3 transverse tear degree ≥ 1.1N Longitudinal tensile force ≥ 100N, peel strength 20-25N/m, gloss (flat sheet) 3.5%-85% (75°) , Moisture 4%.

2 New artificial leather release paper production process

Peroxide artificial leather release paper production process is mainly composed of three parts of original paper release coating and embossing.

2.1 Machine base paper

Peroxide release paper has higher requirements for base paper, ie, paper base layer, and not only is it required to have high strength but also has strict requirements in terms of heat-resistance bulk moisture and the like. In the quantitative determination of base paper, 125g/m2 or more paper is generally used. The technical difficulty lies in the control of the bulk and heat resistance of the base paper. In terms of bulkiness, softwood and hardwood pulps are generally used to control the need for heat resistance. A heat-resistant agent is added to the slurry to enhance the heat resistance of the paper.

2.2 Machine release coating

Peroxo release coatings can be divided into two major categories, namely silicone release coatings and non-silicone release coatings. Silicone release materials include silicone resins, alkyd resins for modified silicone resins, and the like. The non-silicone release materials include chromium complex methacrylic or fatty acid polypropylene resins, polymethylpentene resin TPX and other special resins aminoalkyd resins, epoxy resins, and the like.

Peroxide Different types of release coatings each have different characteristics. For example, silicone resin coatings have excellent release properties and heat resistance, chromium complex coatings have poor solvent resistance, and polypropylene coatings. Has a high gloss but poor heat resistance. Different types of release coatings have different technological processes. Silicone release coatings generally use roll or doctor blade coating methods, and require the use of a layer of primer on the base paper. The main purpose of the primer is to improve the smoothness and resistance to infiltration of silicon coatings. Polypropylene resin and polymethyl pentene resin coating are mainly applied by extrusion coating. The base paper used for the coating may not be primed. Other additives in the coating pass through the feed slot of the extrusion coater. Materials, these release coating technology processes are involved in the control of the peel strength of the coating, which is also its technical difficulties. This in turn involves the selection of a release force control agent and its effect on other properties of the release coating.

2.3 machine embossing

The pattern on the peroxo release paper is generally pressed with an embossing roll. The embossing process can be divided into a conventional embossing process and a special embossing process. The conventional embossing process is further divided into a traditional embossing roller embossing process and an embossing process in which a gear-driven embossing and pressure roller, that is, rollers, are driven synchronously. The special embossing process mainly refers to the concave coating embossing process. This process is used to produce high-grade release paper with a clear and realistic pattern. At present, only the US Sappi Warren Company adopts, the release coating used in this process is the embossing process of electron beam curing resin.