The Difference Between PA and PU Coating

2021-03-26 22:08 CRD

Polyacrylate Coating Adhesive (PA)

Polyacrylate coating adhesive is one of the commonly used coating adhesives at present. It has the following advantages:

1. Resistant to sunlight and climate, with good fastness and not easy to yellow;

2. Good transparency and compatibility, which is great to produce colored coating products;

3. Good washability;

4. Strong adhesion;

5. Low cost.

The disadvantages as follows:

1. Poor elasticity, easy to wrinkle;

2. Poor surface finish;

3. Difficult to adjust the hand feel properly.

The original polyacrylate coating adhesive belongs to pure waterproof products. Through decades of development, the current varieties not only have functions such as waterproof, moisture permeability, and fire retardant, but also have the feature of energy saving in low temperature. The adhesive is generally formed by the copolymerization of hard components (such as polyacrylate methyl ester) and soft components (such as polyacrylate butyl ester). The main monomers of polyacrylate coating are acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, etc. In order to improve its waterproof performance, acrylamide and acrylonitrile can be added when necessary, and peroxide (such as potassium persulfate, etc.) is generally used as polymerization initiator.

Polyurethane coating adhesive (PU)

Polyurethane coating is the main type used currently, and its advantages are as follows:

1. The coating is soft and elastic;

2. The coating has good strength and can be used for very thin coating;

3. The coating is porous and has the properties of moisture permeability and ventilation;

4. With wear resistant, moisture resistant and dry cleaning resistant.

The disadvantages as follows:

1. High cost;

2. Poor weather resistance;

3. Hydrolyze in case of water, heat and alkali.

PU coating can be classified according to composition: polyester polyurethane; polyether polyurethane; aromatic isocyanate polyurethane; aliphatic isocyanate polyurethane. According to the medium used, it can be divided into two types of solvent and water-soluble.

It's difficult to distinguish between PA and PU white coating or PA and PU transparent glue from the appearance, but there are still differences between PA and PU: one is the hand feel, which of PU is smoother than PA, and the elasticity of PU is better than that of PA; the other is gloss: PU has bright gloss, but PA does not have this feature; the last is that PU has a good film touch feeling. In a word, PU is bright, elastic and has a sense of film, while PA does not have these. Of course, it's still hard to tell by ordinary novices.

By the way, I'll give you some small tips:

1. Press the textile with a rubber and lift it up. PA will stick up with the rubber, but PU can't.

2. Drip a few drops of toluene (if possible) on the coating surfaces of PA and PU textile separately, and then gently rub them with hands (do not touch toluene directly with hands), PA coating will fall off, but PU will not. The reason why it is divided into PA and PU is mainly based on the coating requirements of the needed fabrics. PA coating, also known as AC adhesive coating, namely acrylic coating, is the most common coating now. After coating, it can increase the hand feeling, windproof and drooping feeling.

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