What is the Water-based Polyurethane?

Water-based Polyurethane

What is the Water-based Polyurethane?

Waterborne polyurethane, also called water-borne polyurethane, is a new type of polyurethane system, which uses water instead of organic solvent as dispersion medium.

Based on raw materials and structures, it can be divided into polyurethane emulsion, vinyl polyurethane emulsion, polyisocyanate emulsion and closed polyurethane emulsion.

Based on molecular structure, it can be divided into linear molecular polyurethane emulsion (thermoplastic) and cross-linked polyurethane emulsion (thermosetting).

More approaches to classify types of water-based polyurethane

Types of water-based polyurethane

Water based Polyurethane has been developed and applied to lots of fields for decades. There are many kinds of water based polyurethane based on various preparation methods. In this article, we will share its main types.

Based on particle size and appearance:

Firstly, according to its particle size and appearance, water based polyurethane can be divided into three types, that is,

Polyurethane aqueous solution (particle size <0.001 micron, appearance transparent),

polyurethane aqueous dispersion (particle size: 0.001-0.1 micron, appearance translucent), polyurethane emulsion (particle size >0.1 micron, appearance white).

And among them, polyurethane aqueous dispersion and polyurethane emulsion are the most widely-used currently.

Secondly, According to the form of use.

Based on the use form:

Waterborne polyurethane adhesives can be divided into two types according to the use form: one component and two-component.

One component waterborne polyurethane adhesive can be used directly without crosslinking agent. If the required properties can not be obtained by using it alone, the crosslinking agent must be added; or the bonding performance can be improved by adding crosslinking agent to one component waterborne polyurethane. In these cases, the main agent and crosslinker of waterborne polyurethane constitute a two-component system.

According to the properties of hydrophilic groups:

Waterborne polyurethane can be divided into anionic type, cationic type and non-ionic type according to whether there are ionic groups in the side chain or main chain of polyurethane (whether it belongs to ionic bond polymer). Anionic and cationic waterborne polyurethane are also known as ionomer type waterborne polyurethane.

According to its materials:

According to the main types of oligomer polyols, they can be divided into polyether type, polyester type and polyolefin type.

Lastly but not the least, according to the overall structure of polyurethane resin.

Application of Waterborne Polyurethane

Waterborne polyurethane resin is widely used in coatings, adhesives and treatment agents.

Application 1: Adhesive

Like solvent based polyurethane adhesive, waterborne polyurethane adhesive has good bonding performance and wide adjustable range of film physical properties. It can be used as coating adhesive of various substrates and bonding of various substrates

1) Manufacturing of a variety of laminated products, including plywood, food packaging composite plastic film, fabric laminated products, laminated products of various thin-layer materials, such as laminated products of soft PVC plastic film or plastic sheet and other materials (such as wood, fabric, paper, leather, metal).

2) Preparation of flocking adhesive, artificial leather adhesive, glass fiber and other fiber bundle adhesives, ink adhesives.

3) Bonding of common materials, such as automobile interior decoration materials. When waterborne polyurethane is used as adhesive, it must be prepared to suit the construction conditions and substrate factors. Based on waterborne polyurethane, crosslinkers, thickeners, fillers, plasticizers, pigments, other types of waterborne resins and water can be added.

Another Application of Waterborne Polyurethane: Coating agent

1) Leather coating. Polyurethane material is flexible and wear-resistant, and can be used as coating and mending agent of natural leather and artificial leather. When anionic polyether waterborne polyurethane resin instead of acrylic resin emulsion is used as leather finishing agent to treat natural leather, it overcomes the shortcomings of acrylic resin which is hot, sticky and crisp. The finished leather is soft and plump and can be used to make shoes, clothing, leather bags, etc. Waterborne polyurethane resin can also be blended with acrylic resin.

2) Fabric coating. Waterborne polyurethane can be used as coating agent for a variety of fabrics, such as canvas, clothing fabrics, conveyor belt coating.

3) Fiber treatment agent. Cotton fiber and chemical fiber can be improved by immersion, dehydration and heat treatment through polyurethane emulsion dilute solution.

4) Plastic coating. Waterborne polyurethane can be used as surface coating of nylon and ABS.

5) Floor coating. Waterborne polyurethane can be used for the coating of gymnasium, indoor wood floor and concrete floor. It has good abrasion resistance, impact resistance and good gloss.

6) Coating of other materials, such as paper, automotive interior trim coating.

What are some good waterborne polyurethane recommended?

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