A33 Activity Adjustment and Practical Application UV Absorber Manufacturers

A-33 is a commonly used catalyst in the field of polyurethane foaming, which catalyzes the reaction between hydroxyl (-OH) and isocyanate (-NCO), water ( ) and isocyanate (-NCO). Generally speaking, it has two catalytic functions of “foaming” and “gelling”. 、

In practical application, due to many factors such as the density, size, shape, strength, apparent hardness and other physical properties of the finished product, there will be many requirements for “adjustment” in foam production. The main point is to require production: the starting should not be fast, and the demoulding and finalizing should not be slow.

A-33 is a solution of 1 part of “triethylenediamine” (abbreviated as TEDA) and 2 parts of “diol” (propylene glycol, ethylene glycol, diethylene glycol, propylene glycol). It is alkaline in itself, and it becomes more alkaline when dissolved in water.

TEDA can be fixed and shielded by adding small molecular acids to “acid-base neutralization” so that it can be mixed with black and white materials In the initial response, “bystanders are not allowed to intervene”. When the reaction heat of black and white materials reaches a certain temperature, the small molecular acid is separated from TEDA, which makes the latter “liberate” and restore its activity to participate in catalysis again.

Acidified A-33, we can call it “delayed A-33”.

Available small molecular acids include: hydrochloric acid in inorganic acids, etc., but it will bring hydrogen ions and other unstable factors that have a negative impact on the foaming reaction. Organic acids include acetic acid, formic acid, octanoic acid, oxalic acid, etc., because of the temperature requirement for “unshielding” (preferably about 50°C). According to the comparison test, formic acid is a good choice.

A-33
11 parts

Just after simple mixing and coagulation

, depending on the actual situation of the process formula Formic acid
1.5-3 servings

Adjusted into different alkaline delayed products, and then directly added to the formula.

① The basicity of delayed A-33 can be seen through the following steps:

Widely use a piece of PH test paper, drop a drop of catalyst, and then drop a drop of water to cover it. At this time, compare the discoloration area with the color comparison card, and you can make a rough judgment. Generally, it is advisable to control the pH value at 8~9;

② Reagent-grade formic acid is easy to use. Previously, some brothers used industrial formic acid, resulting in crystals in the delayed product;

③ The amount of delayed A-33 used is larger than the normal amount of A-33, 1 -2% is very common.

④The most obvious use effect is imitation wood products, which can prolong the whitening time without delaying the demoulding time, and the surface hardness of the products can be guaranteed;

⑤ High return Elastic, self-skinned molded products are also used in this way, and the effect is good;

⑥ Delayed A-33 can be partially used in manual foaming of block sponges to facilitate the operation of foamers;

>

⑦ It can also be done in spraying and pipe pouring, but the cost factor will affect the mood of use.

Tag:&nbsp&nbsp&nbspA-33&nbspDelay A-33&nbspCatalyst