About Us

About Us

TRUST and QUALITY in Paint and Chemical Industry with more than 40 years background… About Us Company Name (Original): Molimpeks Boya ve Yapi Kimyasallari Dis Ticaret Ltd. Sti. Company Name (English): Molimpeks Paint and Structural Chemicals Foreign Trade Limited Company Reg

Our Products

Our Products

Polyester Resin Vinyl Ester Resins Gelcoat Pigment Paste SMC BMC Auxiliary Products Polyester ResinsPigment PasteVinyl Ester ResinsSMC BMCGelcoatAuxiliary Products

Our Services

Our Services

Our Services (Molimpeks): Production of high quality unsaturated polyester resins, vinyl ester resins, gelcoats, and pigment pastes. [LaXXoPol] Production of furniture paints and varnishes with a production capacity of 60 thousand tons in production facilities equipped with the latest technology

Corporate supplier of specialized composite resins...

LaXXoPoL operates in 40 countries worldwide and has a strong sales network of both local and international companies we serve and collaborate with.

LaXXo Polyester

What is Polyester Resin?

What is Polyester Resin?

Polyester resin (more loosely referred to as ‘laminating resin’ or ‘fiberglass resin’) is a polymer. Simple to use and economical, it is a major component in many industries, from construction to aerospace. Offering incredible physical and chemical properties, it’s also

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Technical Information

Within the simplest terms, polyester resins are unsaturated polymers formed by the reaction of poly functional acids and poly functional alcohols. They are classified as Saturated and Unsaturated Polyester Resins based on their chemical structure. PET (Polyethyleneterephthalate) is a common example for saturated Polyester Resin. This material exhibits plastic behavior therefore can be heat formed.

Unsaturated polyester resins contain carbon-carbon double bond (C=C) in their structure hence, once cured, they form a cross-linked structure, which is not reversible. Such materials that form a cross-linked hard and tough structure are called “Thermoset” materials. Polyester resins are normally hard and brittle at room temperature if they are not dissolved in styrene. To make the resin usable and cross-linkable, it is dissolved in styrene monomer and then cured by adding peroxide. After the addition of peroxide, double bonds of styrene monomer react with the double bonds present in unsaturated polyester resin to form a strong, durable thermoset material.

There are many kinds of raw materials for polyester resin industry and the selection of poly functional alcohols and acids provide different variety of products. Some of the raw materials are very well known in the sector and they give their names to standart resins used in the composites industry.

Orthophthalic Polyester : Most of the polyester resins in the market are of orthophthalic base. They have average specifications and price/performance value. They can be used for general-purpose applications unless is specified.

Isophthalic Polyester : These types of resins contain isophthalic acid in their back bone. They are used generally for chemical resistance purposes. Isophthalic acid yields resins with high hydrolytic stability and chemical resistance. Isophthalic polyesters have higher mechanical and heat resistance compared to orthophthalic resins. Although there is no established rule, sometimes resins containing a small amount of isophthalic acid are also named and marketed as isophthalic resins. Boytek`s isophthalic polyesters are always 100% isophthalic and never blended with orthophthalic.

NPG Polyester : These resins contain Neopentyl Glycol as the glycol component and mostly combined with isophthalic acid to produce durable resins for gel coat production. NPG improves weatherability, UV and heat resistance properties of resins.

DCPD Polyester : DCPD is an interesting molecule that can be incorporated into the polyester resin backbone through different reaction mechanisms. When properly formulated and reacted, DCPD resins are used to produce low viscosity and low styrene content resins.

Polyester Resin :
Polyester resins typically contain around 35-45% styrene monomer which has a flash point of 32 °C. Therefore all sources of flame, sparks and static electricity must be avoided at all times. Smoking is strictly prohibited in areas where resins are used and adequate ventilation must be provided in order to eliminate styrene vapours. Empty drums of polyester resin must be handled with utmost care and should not be punched, cut or drilled.

Initiators (Peroxide) :
Peroxides should be used and stored with care since they can be easily decomposed. Storage temperature should not exceed supplier’s recommendation and their contact with metals and cobalt octoate must be avoided at all times.

Accelerator (Cobalt Octoate):
Cobalt octoate is highly flammable, because it contains solvents. Therefore, it must be stored in accordance with fire regulations. Cobalt octoate should not come into contact with peroxides.

Cleaning Solvents :
Most common cleaning solvent is Acetone. Since its flash point is -20°C, it is highly flammable. It should be used with maximum and proper attention and it should be kept in closed packaging. Even empty drums or buckets are flammable and they should not be stored under sunlight. Empty containers should not be punched, cut or drilled. Methylene chloride has been designated as a possible human carcinogen by many regulatory agencies and it should not be used as a cleaning agent.

Personal Protection:
Exposure to styrene vapor and other chemicals can occur in the workplace. In order to minimize the exposure risks, adequate precautions should be observed:

– Use mask, gloves and goggles,
– Adequate ventilation must be provided,
– All containers should be kept closed,
– Workshop temperature should not exceed 25°C,
– It is recommended to use closed mold operation where possible.

One of the challenges of hand lay-up process is to obtain the right resin/glass ratio in each application. In order to control the ratio, below methods can be followed;

  • Visual check
  • Weigh the resin and fiber before each application
  • Ignition test

1. Visual Check:

Visual check provides a good idea about the quality of lamination.

– A laminate that looks very glossy has too much resin.
– A laminate that looks whitish is too dry and resin starved.
– A good laminate should look clear and dull.

With visual check method, of course you will not be able to tell what the exact resin/fiber ratio is but you can tell if a part is too resin rich or too dry.

2. Weighing resin and fiber:

– Weigh the fiber first
– Calculate the weight of resin
– Weigh the resin

In this method, first ratio of resin/fiber should be decided. After that cut the fiber according to the mold surface. Weigh the fibers and divide the weight of fibers by the decided fiber ratio. Multiply this result by the resin ratio and you will obtain the required amount of resin.
For example;
If we want to produce a laminate with 30% fiber content using 6kg glass fiber;
6 kg / 0.3 = 20 kg 20 kg x 0.7 = 14 kg resin
To make sure the calculation is correct;
We produce a 20kg part using 6kg glass fiber and 14kg resin.
6 kg fiber / 20 = 0.3 (30% fiber)
14 kg resin / 20 = 0.7 (70% resin)

3. Ignition Test:

Cut a small specimen of cured laminate size 5cm by 5cm. Weigh the specimen and place it in oven at 700°C for 1-2 hours. By this way, all the resin and organic materials will burn out of the specimen and leave only the glass. Weigh the specimen again. Divide the second weight by the first weight to obtain glass fiber ratio. If the laminate contains gel coat or fillers, the results will not be accurate.

Before starting to build the mold, make sure that the pattern has a perfect surface. Since the surface quality of the mold will replicate the pattern, the surface of the pattern should be worked carefully, and the surface coating material should be checked for resistance against styrene. In case pattern and mold should be heated in oven together, the model material should be resistant to at least 50°C.

After making sure that the pattern is properly prepared, apply a mold release agent on the pattern surface. Then apply gel coat in several thin passes in order to avoid air entrapment in the gel coat film. Total thickness of the gel coat film must be between 600-800 microns. It is recommended to use specially formulated BRE 390 mold making gel coat. Keep initiator levels between 1 – 2.5% depending on workshop temperature.

After gel coat is cured, begin lamination. For lamination use LXP 390, zero-shrink mold making resin. The instructions below are valid for building a mold using LXP 910.

As the first layer of lamination, use glass veil followed by preferably a low gramage chopped strand mat. For excellent result, Owens Corning 225 gr / m2 M113 fiber is recommended, which helps minimize fiber print-through. After this step, keep laminating 4-5 layers of 450gr/m2 chopped strand mat at one go. It is of great importance that 4-5 layers are applied at once and if a thicker laminate is required another 4-5 layers should be applied at once. The lamination temperature should reach 50-60°C to prevent any shrinkage. The color of the laminate will change from brownish to white when curing is complete. Color change is an indicator of thorough cure.

Woven fibers cause non-homogenous resin-fiber distribution, which may result in deformation of the mold. Therefore, it is recommended to use only chopped strand mat for mold making. Another point of attention is to avoid accumulation of resin in the lower parts of the mold. Resin rich sections in these areas, may cause deformation due to high exotherm as well as cracks and low mechanical strength. In order to avoid these potential problems, a mold making resin must be thixotropic.

The mold must be supported and reinforced with metal profiles to reduce tension and stress on joint parts. The metal profiles should be assembled in the corners rather than along the mold and should be with two layers of 450 g/m2 chopped strand mat.

The choice of mold release agents for the mold break-in is very important. It is recommended to apply 4-5 layers of mold release wax followed by PVA to avoid possible sticking problems.

Viscosity is a fluid’s resistance to flow. The fluids that have less viscosity can flow easily (like water) while fluids with high viscosity can flow relatively more difficultly (like honey). The unit of viscosity is either “cp” or “mPa.s”. When defining the viscosity of a fluid, its temperature should always be mentioned because viscosity of fluids depends on the temperature. For example, the viscosity of a polyester resin at 20°C will always be higher than its viscosity at 25°C.

Thixotropy is the shear thinning property. Certain gels or fluids that are thick (viscous) under static conditions will flow (become thin, less viscous) easily when shaken, agitated, or otherwise stressed. For example, when a thixotropic polyester or gel coat is sprayed with spray gun, it is exposed to high pressure in the nozzle and its viscosity reduces, making it easy to spray. When the sprayed resin reaches the mold, it will stay on the mold and not run down because once it leaves the nozzle of the gun, the pressure is relieved and viscosity is recovered.

Gel time:
The period of time when the resin changes from a liquid to a non-flowing gel is called the “gel-time”, and is also the time available to work the resin once peroxide is added. Gel time varies with temperature as well as the amount of initiator and accelerator used.

Curing is a term in polymer chemistry that refers to the hardening of a polymer material by cross-linking of polymer chains after gel time.

Initiators are chemicals that cause the resin cure properly to achieve final properties. The choice of appropriate initiator is dependent on the application technique. Most commonly used initiator is MEK peroxide, which is added 10-25gr per 1kg of resin.

Accelerators are the chemicals that accelerate the decomposition of initiators thus helping the resin cure quicker. Generally metal salts are used as accelerators, Cobalt octoate being the most common one. It is mostly used in 6% solution with an addition ratio of 1.5-2gr per 1kg resin. IMPORTANT!!! Cobalt Octoate and MEK Peroxide must not be mixed or be in contact with each other. Mixing of these two materials causes violent reaction and possibly fire and explosion. Inhibitor: Inhibitors retard the gel and curing time of polyester resins. They are especially helpful to balance the gel time in warm environment.

  • - Stir the container slowly for 5 minutes before using.
  • - Do not over mix as this will cause loss of thixotropic properties. If the product is over mixed, let it rest for at least 4 hours to recover original properties.
  • - Apply the gel coat in several thin passes to avoid air entrapment, porosity and sagging.
  • - Recommended application thickness is 600-800 .
  • - It is recommended that the peroxide amount should remain between 1-2,5%.
  • - Before application check the temperatures of the gel coat, the mold and the shop. Do not apply gel coat if the temperature is lower than 18°C.
  1. If the temperature is low and faster gel and cure are required, some Cobalt may be added.
  2. Post added Cobalt (6% concentration) amount should be maximum 1gr per 1kg gel coat.

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Polyester Resins
Vinyl Ester Resins