Polyesters mould release agents

Plastic composites such as glass- or carbon-fibre reinforced materials are often based on polar epoxy or polyester resins, and are therefore compatible with the common adhesives as well as being readily bondable. Surface treatment is required simply to remove contaminants such as oils, dirt, and especially fluorocarbon mould release agents. The two main techniques used to achieve this are ... 

The remainder of this entry is concerned with external mould release agents for use with thermosetting resins, mainly in open mould and low throughput operations. In the case of large fibre glass polyester or epoxy... 

Release agents are required particularly when moulding thermosetting resins, such as polyester, epoxy and polyurethane laminates. 

Pulisol-9 (WIZ chemicals) is an effective solvent for cleaning moulds, metals, and similar articles. A blend of high activity and penetration solvents, which is neutral and evaporates slowly, it is a transparent liquid which can remove traces of polyurethanes, polyesters, epoxy and phenolic resins, as well as release agents, waxes, rubbers, and fats. The flash point is 31°C. The cleaner is used undiluted and applied with a cloth or brush, left to act for a few minutes and then wiped with a clean, absorbent cloth. For used moulds, more than one application may be necessary for new moulds, one application is sufficient. Protective gloves should be worn. 

Unsaturated polyester (Butanox M-60) mixed with 1.5% of Methyl Ethyl Ketone Peroxide (MEKP) as catalyst was selected as a resin for the current work. Treatedbetelnut fiber reinforced polyester (T-BFRP) composite was fabricated using hand lay-up technique. In composite preparation, a metal mould (100 x 100 x 12 mm) was fabricated. The inner walls of the mould were coated with a thin layer of wax as release agent. The first layer of the composite was built by pouring a thin layer of polyester. A prepared mat was placed carefully on the polyester layer. Steel roller was used to arrange the mat and eliminate trapped bubbles. This process was repeated until the composite block was built containing 13 layers of fiber mats and 14 layers of polyester. The prepared blocks were pressed at approximate pressure of 50 kPa in order to compress the fiber mats and to force out the air bubbles. The blocks were cured for 24 hr and then machined into specimens in the size of 10 x 10 x 20 mm. 

Another polymer used as a release agent in the glassfibre moulding industry is cellulose acetate, dissolved in acetone. PTFE and related fluorinated polymers can be sprayed on. Silicone release agents are effective with epoxy resins but not usually with unsaturated polyesters, except in hot press moulding. They are also ineffective with certain polyurethanes. 

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