Concentrol has a long experience in adhesives in aqueous dispersion and has dozens of product lines, each specialized for a specific use, characteristics and sector. The TACKTROL range comprises polymers obtained from radical processes of emulsion polymerization.
The research has led to the creation of a range of additives that vary the chemical and physical properties of adhesives to suit customer needs. Thus, the adhesives offered by Concentrol can vary the forge speed, the open time, the viscosity, the elasticity of the film, include fungicides, vary the wet bonding time or even include preservatives to prevent microbiological contamination.
Adhesives are classified according to their physicochemical characteristics: those that have a pre-existing polymer or those that the polymer forms at the time of assembly.
In most cases, water-dispersive adhesives are applied to one of the parts to be joined, and it is immediately attached to the second, which is free of adhesive.
The parts must be fixed by mechanical methods, to maximize the contact surface and keep the supports in position while the carrier evaporates, in this case water. Adhesion occurs once the water has completely evaporated.
Another type of adhesive is the traditional, solvent-based contact adhesive. They are applied in both pieces to be joined. After a certain time of ventilation and evaporation, which can vary for each solvent system, the pieces are joined by exerting a strong pressure between the two. The parts are immediately glued and can be subjected to stress.
Differences between adhesives in aqueous dispersion and solvent base
Solvent-based adhesives are the most common type of adhesive in some industries, due to their quick-drying and bonding properties. The use of a solvent-based adhesive gives manufacturers the peace of mind that the substrate will remain firmly attached to the film during the manufacturing process. However, there are financial, environmental and health and safety reasons why solvent-based adhesives are not always the best choice, especially for food contact products.
There are a number of disadvantages to using solvent-based adhesives:
- The cost of solvent-based adhesives is more expensive than water-based adhesives. This cost is also environmental, as volatile organic compounds (VOCs) are released into the atmosphere during the manufacturing and application process.
- Health and safety when handling these products. Legislation limits and regulates under what environments and conditions solvent-based adhesives may be used.
- Consumer safety: the presence of solvents in an adhesive makes it unsuitable for use in food packaging or clothing.
- Cleaning up. Solvent-based adhesive residues cannot be cleaned with water and a solvent-based solution must also be used.
- Solvent-based adhesives are flammable.
Water-based adhesives, on the other hand, have the following advantages:
- Can be applied with different systems: rollers, segmented rollers, injectors, probes, sprayer, brush or disc, among others.
- The cost of the solvent is more expensive than water, which means that the water-based adhesive will be cheaper than a solvent-based equivalent.
- Aqueous dispersion adhesives are stable over time.
- They give a uniform spread.
- They are good to handle.
- Water-based adhesive is environmentally friendly and has fewer environmental restrictions.
- It is not harmful to health because it does not contain solvents.
- Can be used in applications where the dry residue of the adhesive may be in contact with food.
- Wet adhesive adhesives can be used on a wide variety of substrates.
- They don’t smell much or at all.
It should be noted that water-based adhesives have some disadvantages such as slower drying than solvent-based adhesives, are susceptible to freezing, some include allergenic ingredients and have a lower water resistance than the same product in solvent base.
Concentrol develops four families of adhesive solutions: Water-based (CO), viscous (VOC), food grade (COF) and food grade viscous (COFV) adhesives.
Features of the solutions offered by Concentrol
Aqueous dispersion adhesives are generally known as white glue and are ready-to-use formulas. They do not require any treatment or dilution – unless specifically stated.
These products are easy to apply and handle and have an adjustable open time. That is, the maximum time that can elapse between applying to one substrate and bonding with the other part can be adjusted.
- The CO family consists of adhesives in aqueous dispersion with a viscosity that does not exceed 15,000 cps.
- The VOC family is made up of adhesives in aqueous dispersion with a viscosity higher than 15,000 cps.
- The COF family is made up of aqueous dispersion adhesives suitable for food contact and with a viscosity not exceeding 15,000 cps.
- The COFV family is made up of aqueous dispersion adhesives suitable for food contact with a viscosity higher than 15,000 cps.
Concentrol’s product lines
The TACKTROL range brings together all water-based adhesives. The typology is very varied; In addition to viscosity, Concentrol offers products with high re-wetting (such as envelope adhesives), with resistance to high or low temperatures, with a heat-sealable layer, heat-stable or with a higher solid content.
This versatility of products makes them suitable for a wide variety of sectors:
- Labelling sector
- Carrier bag sector
- Cardboard sector
- Card sector
- Graphic arts sector
- Hygiene sector
- Binding and carpentry sector
- Envelope sector
- Food sector
- Construction sector
Media and application systems
In order for the materials to bond together, generally one of the two supports must be porous to allow water to evaporate. The most common and generally easiest media are paper, card and cardboard. Plastics, foam, wood, and cork, among others, can also be glued together.
We can differentiate between two types of support or materials depending on their ability to join:
- Supports of easy bonding: they are supports with greater porosity, facilitate the drying of the adhesives and allow a penetration in the substrate to achieve an adhesion more physical than chemical. It penetrates through the pores and anchors to the substrate. These supports are: cardboard, corrugated cardboard, card or coated card, paper, cork and wood.
- The difficult-to-join supports are those that have lower porosity or do not have pores and their surface can be very apolar. Aqueous dispersions of polymers have chemical affinity to the polar surfaces. In these cases, it is advisable to pre-treat the substrate and know how to play properly with the recommended dispersions and additives.
The treatment prior to the application of the adhesive consists of the treatment in corona or plasma, which consists of applying a flame and a heat source, to induce the formation of polar groups on a surface to facilitate their adhesion.
Hard-to-adhere substrates are, among others, varnished surfaces, UV acrylics, acetates, cellophane, plastics (PVC, * PET, crown-treated PE, crown-treated PP…) or glass.
The application of adhesives can be manual. Viscose aqueous adhesives are applied in this way and are done with a sponge, spatula or brush, wetting the applicator with the adhesive directly from the container and applying to one of the two substrates to be bonded.
With roller or disc they can be applied with two variants. In a bottom-up application, the bucket with the adhesive is below a roller that is impregnated with the adhesive when rotating. In a top-down application, the bucket is above the roller and the adhesive is applied by gravity.
Concentrol’s adhesive can be applied by injection. Each sector uses the type of injector that suits it best (electric, pneumatic, with contact, without contact…). The viscosity of this product should be between 500 and 2,000 cps.
When the adhesive is transferred with feelers, a “metal finger” applies the adhesive to the holder.
The last method of application is the segmented roller, which can be top-down or bottom-up, has relief areas that provide glue and mark precisely where there is a need for adhesive
Customer-tailored solutions
Concentrol professionals advise on the choice of the product that meets the necessary characteristics of the customer and that vary depending on some variables:
- The type of material to be joined. It is important to know if it is a porous material or not. Moreover, it is important to know if the substrates can be treated or if they come treated.
- The form of application of the adhesive will give information on the necessary rheology of the adhesive. Each of the applications (manual, roller, injectors, probes, disc…) has the necessary viscosity requirements so that the adhesive flows well and there are no problems of splashing or dripping product.
- Pressure time, open time or hardening speed are data to be taken into account, as they can be altered with the addition of additives.
- The climatic conditions that the union must withstand can be very varied (high or low temperatures, resistance to freezing, resistance to moisture, waterproof…), and it is important to keep this in mind.
- The environmental gluing conditions of the site (high or low application temperatures, large differences between seasons, relative humidity of the environment…) alter the direct application of the glue, increasing or decreasing the viscosity,
- The regulations or requirements that an adhesive can meet are very varied. Some regulations, such as direct or indirect food contact, are different in each region.
