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The Analysis of Influencing Factors on SIS Type Hot Melt Pressure Sensitive Adhesive

2022-05-07 Page view : 14 views

Hot melt pressure sensitive adhesive (HMPSA) is a semi dry solid that is coated on the substrate when heated to molten state and has permanent viscosity after cooling. SIS hot melt pressure sensitive adhesive is generally made of SIS plasticizer and tackifying resin mixed in a certain proportion and melted at about 18 ℃. Its properties are mainly characterized by initial viscosity, holding viscosity and 180 ° peel strength. In addition, the softening point, slitting performance and melt viscosity of HMPSA are often concerned by users. Due to the diversity and particularity of the performance requirements of SIS products and HMPSA in the market, the technical parameters of SIS will have a certain impact on the properties of hot-melt pressure-sensitive adhesive. So let’s talk about the influence of SIS parameter changes on the performance of the new HMPSA.

SIS has good cohesion and excellent adhesion. It is an excellent main adhesive for preparing hot-melt pressure-sensitive adhesive. The compatibility between petroleum resin and sis is very good. Usually, two different types of SIS are blended to make pressure-sensitive adhesive. The hot melt pressure sensitive adhesive made of C5 resin as tackifying resin has high peeling force and holding viscosity, but poor initial viscosity.

1. How to increase the initial viscosity of SIS hot melt pressure sensitive adhesive?
Plasticizer is an essential component in the preparation of SIS hot-melt pressure-sensitive adhesive. It can improve the surface wettability of the pressure-sensitive adhesive to the adhered material. Improve adhesion and reduce costs. Plasticizer is a liquid with low viscosity at room temperature. When used in SIS hot-melt pressure-sensitive adhesive, it can significantly reduce the melting viscosity, which is conducive to coating construction, increase the pressure-sensitive viscosity and improve the initial viscosity. However, the plasticizer will also reduce the cohesive strength of the pressure-sensitive adhesive. When the amount is too much, it will lead to a significant decrease in viscosity and peel strength.

The commonly used plasticizers include naphthenic oil, white mineral oil, liquid paraffin, dibutyl phthalate (octyl) ester, etc., which have different effects on the properties of SIS hot-melt pressure-sensitive adhesive. Dibutyl (octyl) phthalate has very good initial viscosity, but its viscosity retention and peel strength are very poor; Naphthenic oil has good initial viscosity, long viscosity holding time and high peel strength. It is the plasticizer with the best comprehensive performance; The effect of white mineral oil and liquid paraffin as plasticizer is slightly worse than that of naphthenic oil.

Therefore, naphthenic oil is generally used as plasticizer when preparing SIS hot-melt pressure-sensitive adhesive. If composite plasticizer is selected, sometimes better results will be obtained.

2. Effect of plasticizer on properties of SIS hot melt pressure sensitive adhesive
Plasticizer is an essential component in the preparation of SIS hot-melt pressure-sensitive adhesive. It can improve the surface wettability of the pressure-sensitive adhesive to the adhered material. Improve adhesion and reduce costs. Plasticizer is a liquid with low viscosity at room temperature. When used in SIS hot-melt pressure-sensitive adhesive, it can significantly reduce the melting viscosity, which is conducive to coating construction, increase the pressure-sensitive viscosity and improve the initial viscosity. However, the plasticizer will also reduce the cohesive strength of the pressure-sensitive adhesive. When the amount is too much, it will lead to a significant decrease in viscosity and peel strength.

The commonly used plasticizers include naphthenic oil, white mineral oil, liquid paraffin, dibutyl phthalate (octyl) ester, etc., which have different effects on the properties of SIS hot-melt pressure-sensitive adhesive. Dibutyl (octyl) phthalate has very good initial viscosity, but its viscosity retention and peel strength are very poor; Naphthenic oil has good initial viscosity, long viscosity holding time and high peel strength. It is the plasticizer with the best comprehensive performance; The effect of white mineral oil and liquid paraffin as plasticizer is slightly worse than that of naphthenic oil.

Therefore, naphthenic oil is generally used as plasticizer when preparing SIS hot-melt pressure-sensitive adhesive. If composite plasticizer is selected, sometimes better results will be obtained.

With the increase of the amount of plasticizer, the initial viscosity of the prepared hot-melt pressure-sensitive adhesive becomes better and the 180 ° peel strength decreases significantly. This is because the plasticizer has poor compatibility with the hard segment of the elastomer and good compatibility with the rubber segment, which increases the volume of the rubber phase and increases the sensitivity to pressure; At the same time, due to the reduction of the force between molecules in the rubber phase, creep is easy to occur between the adhesive and the bonded material, resulting in the reduction of viscosity and 180 ° peel strength

3. Effect of SIS parameters on properties of hot melt pressure sensitive adhesive
Thermoplastic elastomer sis is a block copolymer of styrene and isoprene. Its molecular structure is similar to that of SBS. It is embedded by polystyrene segment (s) – polyisoprene segment (I) – polystyrene segment (s), so it is called sis. Its technical parameters mainly include SIS configuration, block ratio (s / I), molecular weight and diblock Si content. According to the coating online understanding, affected by the middle block polyisoprene side chain methyl group, SIS has good cohesion and bonding performance. At the same time, it also has the characteristics of low modulus, good elasticity, low melt viscosity, strong viscosity and good coating performance. Therefore, SIS is an excellent main material for preparing hot-melt pressure-sensitive adhesive (HMPSA), which has been widely used in the production of pressure-sensitive adhesive tape and label paper.

HMPSA refers to a semi dry solid that is coated on the substrate when heated to the molten state and has permanent viscosity after cooling. SIS hot melt pressure sensitive adhesive is generally made of SIS plasticizer and tackifying resin mixed in a certain proportion and melted at about 18 ℃. Its properties are mainly characterized by initial viscosity, holding viscosity and 180 ° peel strength. In addition, the softening point, slitting performance and melt viscosity of HMPSA are often concerned by users. Due to the diversity and particularity of the performance requirements of SIS products and HMPSA in the market, the technical parameters of SIS will have a certain impact on the properties of hot-melt pressure-sensitive adhesive.

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