Лако-красочные материалы — производство

Add premix 1 slowly to the premix 2, with good stining. Then add FC-134 (levelling agent, 3M) and defoamer, such as SE-2/H20 1/9 from Wacker, and stir well for at least 30 minutes. This formulation can be used as an exterior coating, having extreme water and moisture resistance.

NeoCryl A-1049-U is an anionic acrylic dispersion, 40 %nvc with a MFFT of 40°C. NeoCryl BT-21 is an acrylic dispersion, 40 %nvc. Sudranol 100 is a wax emulsion to improve water repellency. Steinapol SBDO-70 (Rewo) can be used as the wetting additive. For good film formation, a combination of coalescents and plasticisers are added.

Concrete flooring is often used in areas which have unusually heavy traffic. General requirements in such coatings (including other floors, such as wooden) are :

• fast hardness development (within 24 hrs)

• good wet abrasion resistance

• excellent blister resistance when exposed to water and detergents

• good wet adhesion

• minimum dirt pick-up.

Silica can be added as extender to increase wet abrasion resistance. Small amounts of aluminium oxide can also be used instead of silica with little effect on sheen. Because of the abrasive nature of aluminium oxide, it should be added at the end of the let down stage with just sufficient stirring for good wetting and dispersing. Pine oil may be used as plasticiser for improved odour characteristics. Epoxy ester emulsions, such as Araldite DP-624 (Ciba), may be added to improve resistance to cracking and lifting of the film under severe exterior conditions.

Typical formulations are given below.

(iii) Formulation for Floor Coating

Properties

Disperse the millbase to Hegman 7 and add the let down. Viscosity and pH are adjusted with ammonia. Rhoplex WL-91 (Rohm and Haas) is a hard polymer for good block resistance, 41.5 % nvc with a MFFT of 52°C. Plasticisers and coalescents are required for good film formation.

(iv) Floor Coating for Vinyl Composite Tiles

Properties

Rhoplex WL 91 Ex Rohm and Haas Co.

Add the components in the order shown using a low speed disperser with a gentle vortex. Adjust to pH 7.5 using ammonia prior to adding polymer emulsion. The material should be allowed to stand overnight before testing physical properties.

A low cost concrete sealer formulation imparting good gloss, wear, chemical and solvent resistance may be:

(v) Formulation for Low Cost Concrete Sealer

Properties

Add the components in the order shown, using a low speed disperser. Adjust pH to 7.5 using ammonia prior to adding emulsion polymer. The material should be allowed to stand overnight before testing physical properties.

Resins suitable for use in masonry and floor coatings include :

Neocryl A-633 Neocryl A-1049-U Neocryl XK-90 Rhoplex SS-521 Rhoplex AC-61

XI PLASTIC COATINGS

by Chris Langham LTSC

There are several reasons for coating plastic materials, some of which are ;

a) To provide resistance to mar, solvents, chemicals or dirt pick-up.

b) To act as barrier to plasticiser migration.

c) Act as substrate for further processing, e. g. vacuum metallizing.

d) Decoration to give colour and effects finishes.

e) Reduce costs by using cheaper or recycled materials.

Several problems face the plastic coating formulator. Solvent attack can cause crazing and etching of the surface. Some plastics are difficult for adhesion, which is influenced by the selection of the binder and solvent system as well as the surface condition. Further discussions are found in the thermoplastics chapter.

With their low solvent content, water-borne systems offer improved coverage of solvent sensitive substrates.

Some coating formulations suitable for plastics are given below: