Sale of Polyester Resin
Do you need polyester resin for boat construction or repair? The topRik marketplace offers resins for yachts from the world's best manufacturers of marine chemicals. Today you can buy a composition with crystalline fibers and other fillers, accelerators and modifiers. You don't have to look for catalysts since they are included in the kit.
If choosing or using polyester resin is a problem for you, topRik experts can help you. These are constantly practicing yachtsmen who know everything about repairing boats made of any material. Right now, get a free professional consultation through the quick contact form on the website or by phone. You can also send your questions to [email protected].
The vast majority of resins used in shipbuilding and yacht repair are unsaturated polyesters, which belong to the category of thermosetting resins. This means that they cure through a chemical reaction and cannot subsequently be reverted back to a liquid state by heat (as is possible with thermoplastic resins). Thermosetting resins are syrupy liquids of varying degrees of viscosity and have a number of specific properties. What are the characteristics of polyester resins have made them the most popular in the production of yachts and boats?
Advantages of Polyester Resin
The most widely used type of resin in fiberglass shipbuilding is still polyester. The physical and mechanical properties of polyester resins are somewhat worse than those of epoxy resins, and their chemical resistance is also lower. However, in relation to shipbuilding, all these factors do not play a decisive role - they are outweighed by the advantages of polyester resin compared to epoxy:
- comparative cheapness;
- possibility of rapid curing at room temperature;
- ease of manufacturing;
- moderate moisture resistance;
- chemical inertness;
- ease of use.
The long-term chemical resistance and durability of polyester resins are considered sufficient for most fiberglass boats.
This inexpensive boat resin has another property that is very important for finishing fiberglass yachts that typically sit in warm waters and hot sun. Unsaturated polyester resins are resistant to UV rays.
Important note: unlike epoxy, vinyl and urethane, most polyester resins create a tacky surface when cured. This ensures strong adhesion between the layers, followed by “cold” cross-linking at the molecular level.
Polyester resins can withstand temperatures of 80-240°C and hold reinforcing material perfectly due to their sticky surface layer even after drying.
Types of Polyester Resin
The simplest classification of polyester resins commonly used in fiberglass shipbuilding is their division into structural and finishing. Structural resins do not contain wax; air prevents them from curing. Air does not prevent finishing resins from curing because they contain wax. Structural resin must be used throughout the entire fiberglass yacht construction process, with the exception of the final layers when finishing polyester resins are used.
Types of polyester resin can also be classified according to their degree of flexibility. Depending on the application (hull, superstructures, decks), additives can be used to adjust the elasticity of the resin in the following parameters: rigid, semi-rigid, elastic. Usually this classification is used during the construction of yachts, but when repairing a boat it is also useful to take into account the degree of flexibility of the resin.
Most polyester resins are clear, viscous liquids, a solution of polyester in styrene (or other monomers). Styrene occupies up to 35-50% of the volume; it reduces the viscosity of the resin, making it fluid, suitable for casting or application to the surface with a brush or roller. Depending on the molecular weight and structure, polyester resins are divided into orthophthalic, isophthalic and vinyl ester.
Orthophthalic Resin
This is the most common type of resin in fiberglass shipbuilding, especially when it comes to amateur yacht building. Primarily due to their low cost, and also due to the fact that the characteristics that isophthalic and vinyl ester resins have are generally not needed by most boats.
Contains 35-45% styrene. Used where there are no increased requirements for heat resistance, corrosion resistance or mechanical strength.
Isophthalic Resin
On an isophthalic basis, a heat-resistant structural polyester resin is obtained with a styrene content of up to 42-50%. Occupies the middle and premium segment. Corrosion resistant, heat resistant. The maximum temperature of this type of polyester resin is up to 150-240°C.
Vinylester Resin
The styrene content in this one is 35%. Vinyl ester resins are characterized by tensile elasticity. This provides the laminate made on their basis with higher characteristics, which is important where it is not possible to avoid high loads (cyclic and vibration) at the design stage. Applications where such qualities can be at a premium are, for example, high-speed racing boats for the high seas.
In terms of chemical and corrosion resistance, vinyl ester resins outperform isophthalic resins and also retain their high mechanical properties at elevated temperatures - a quality that is very valuable when used in the aerospace industry. Their high chemical resistance is used in the making of fiberglass containers and in various industries.
FAQ
What is the difference between polyester and epoxy resin?
The two types of resins most commonly used for building and repairing fiberglass boats are epoxy and polyester. Epoxy resins have higher adhesive bond strength, they have less shrinkage, in the cured state they filter moisture less, resist abrasive wear better and have better physical and mechanical properties.
Unlike polyester resins with their small amount of catalyst, hardeners for epoxy resins make up a significant proportion of the working mixture. By changing combinations of resins and hardeners, epoxy compositions with a wide variety of properties can be obtained.
All these advantages of epoxy resins, however, do not cancel out their disadvantages when it comes to the production of fiberglass. First of all, this means a significant increase in costs. Epoxy resins require more careful handling, although this point can be challenged after studying the hazards of polyester resins, which can evaporate styrene during the curing process.
Epoxies polymerize more slowly, which slows down the production process (one of the main reasons why manufacturers avoid them), and they are more difficult to process, especially when made on a block.
Another problem with epoxy resins is their tendency to lose viscosity as temperature increases during exothermic curing. This creates difficulties when working with the resin on vertical and inclined surfaces and, coupled with the slow cure, makes laminating work in such conditions extremely tedious.
How to properly mix polyester resin with hardener?
First of all, it should be remembered that it is extremely undesirable to mix different groups of additives with each other, since it can even cause a combustion reaction. Different hardeners are used for resins with different bases.
To start the polymer hardening process, a resin, a hardener and a catalyst are needed. The temperature regime, proportions and order of introduction of the components must be observed. All this data is indicated by the manufacturer in the instructions for use.
First, gelatinization of the composition occurs, the composition becomes gel-like. Next is the rubber-like stage. And the final stage is complete solidification. When completely hardened, the composition acquires a stable state and takes on a solid form.
Can polyester resin be used to repair the underwater part of a boat?
To repair the bottom, you can use gelcoats - pigmented resins, usually elastic and semi-elastic. Because these are the compositions that are used in the construction of most mass-produced yachts. They are applied to the inner surface of the matrix and are the first step in the construction of a fiberglass hull. Gelcoats can be made from orthophthalic or isophthalic polyester resin.
What storage conditions are required for polyester resin?
Typically, polyester resin has a shelf life of only six months, although under proper storage conditions a year or even two is not out of the ordinary. The period can be extended even more if you store the resin in the refrigerator, but not by freezing. The resin should be stored in a cool, dry place away from direct sunlight and where the temperature does not exceed +20°C.
Is it possible to dye polyester resin?
There are two main types of paints used for fiberglass. They are both polymer (or plastic). One type needs air to harden, the other needs temperature and air. Air curing inks are usually polyesters and usually come in an all-in-one container. Catalyzed paints are called epoxies, they consist of two parts, normally equal in volume. Epoxies require a catalyst and, like polyester dyes, the correct temperature.
Any resin-based paint is quite suitable for fiberglass. Of course, it is better to use paint whose base matches the resin with which fiberglass is impregnated during manufacturing, so the materials bond better.
If you are painting a boat or other fiberglass object that will be exposed to extreme temperatures and water contact, it is highly recommended that you use epoxy resin paints, regardless of the resin used in the fiberglass material itself. Epoxy resin paint has greater durability, which is important when exposed to both fresh and salt water.
What tools and materials are needed to work with polyester resin?
The resin can be applied with a spray gun on the final and finishing layers, and gelcoat can be applied using the same method when molded in a matrix. But only yacht building professionals can do this accurately.
For the amateur boatbuilder, spraying resin during normal laminate installation has little practical value and is not recommended. In this case, it is better to use spatulas, brushes and rollers. The same applies to conventional repairs using compounds based on polyester resins.