Coating agent and intercourse with water

Coating agent and intercourse with water,Waterborne wood paint are water-based isocyanate is to improve the performance of an important way, is an important factor of two-component waterborne wood paint chemical properties, is the most effective way to improve the comprehensive performance. Focus on the correct way to choose water crosslinking agent and how to use the fastest speed to determine the coating activation period.

As people of environmental protection consciousness gradually strengthened, low pollution and low toxicity of waterborne wood coatings gradually get the attention of people. Currently on the market sales of waterborne two-component coatings, chemical resistance, resistance to yellowing and fouling resistance has the very big enhancement, is getting closer and closer to people look forward to excellent film performance.

This is mainly because two components, water-based wood coatings by isocyanate crosslinking agent and water containing hydroxyl resin composition, film forming, crosslinking agent of - NCO and resin - OH chemical crosslinking, spatial reticulated structure to generate insoluble in water, may through the adjustment of the formula, it achieve comparable to those of solvent-based coating effect.

But in actual construction projects in the process of debugging and formula because of the differences of crosslinking agent choice and dosage is different, can cause the performance of the coating did not achieve the desired effect. Therefore, this article focuses on the correct way to choose water crosslinking agent and how to use the fastest speed to determine the coating activation period.

Select the appropriate water crosslinking agent. Water-based isocyanate crosslinking agent, is the original crosslinking agent on the basis of introducing hydrophilic group, so don't need high shear in the coating can achieve below 100 nm size, easy to mix with water hydroxyl resin. The size of the crosslinking agent hydrophilic ability, directly influences its reaction with water. In general, the better the hydrophilicity, the more likely it is to react with water. It's need to choose the proper crosslinking agent according to demand.

Water crosslinking agent and the choice of solvent has very big difference, mainly reflected in the - NCO will react with water and the neutralizing agent, thus affecting the construction performance and film performance. In main agent and crosslinking agent, viscosity will increase, as long as by adding the appropriate solvent polyurethane (pu) solution can solve this problem, but different waterborne polyurethane, due to join the solvent is water, water will consume part - NCO, resulting in falling film performance.




Chinese name: Diethyl toluene diamine(DETDA)

Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.

Density 1.022

Viscosity (20 ℃) ??mPa·ss290±10

Pour Point ℃-9

Boiling point of310°C

Flash Point°C161.1°C


So the key to choose a suitable water crosslinking agent is in construction to find a balance between performance and film performance. 1.2.1 water crosslinking agent activation period measurement of characterization of activation stage characteristics are there are two main indexes of NCO content of the construction process of coating and its viscosity changes. More isocyanate with water mixes hydroxyl resin, NCO content change within 5 h at first is to determine the stability of performance, determine the reasonable construction are the important factors of the construction process of the activation period.

In the initial 2 h, Bayhydurxp 2655 change is most obvious, Bayhydur 305 times, change is the smallest RHODOCOATWT 2102. Little change and the change of viscosity is Bayhydurxp 2655, 305 and 2102 RHODOCOATWT Bayhydur change is more noticeable.

Can be concluded from this, Bayhydurxp 2655 compared with the reaction of water, consume large amounts of - NCO but viscosity increase is not obvious. Bayhydur 305 and RHODOCOATWT 2102 and water is less side effects, and most of the - NCO and - OH reaction, resulting in the sharp rise in viscosity.

Each color can be used to determine the three parameters, namely the hue, lightness and saturation. Tone is characteristic of color difference between each other, determine the guang-yuan yu of chromatography and the wavelengths emitted by an object's surface to the human eye feeling, can be the difference between red, yellow, green, blue, purple etc. Characteristics.

Lightness, also known as the brightness, it is said the eigenvalues of the objects on the surface of light and shade degree change, by comparing the brightness of all sorts of color, color is bright and dark. Saturation, also known as chroma, it is said the surface color shades of characteristic value, the colour with bright and dark. Hue, lightness and saturation constitute a three-dimensional, with the three established scale, we will use a number to measure color.

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Diethyl toluene diamine(DETDA)  http://www.yaruichem.com