The UNICS Corporation answers queries regarding surface treatment and urethane coatings, in a Q&A format.

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Answering queries regarding surface treatment and urethane coatings

On this page, the UNICS Corporation answers frequently asked questions regarding surface treatment and urethane coatings, in a Q&A format. Please also take a look at the answers to questions regarding the company’s services.

Questions regarding urethane coatings

What types of urethane coating are there?

Broadly speaking, polyurethane is categorized according to its friction coefficient, the urethane rubber hardness, abrasion resistance, surface finish (based on the coating technique used), and its intended performance as an adhesive. There are also smaller sub-categories.

Polyurethane is regarded as a rubber coating because its performance as a coating is linked to the hardness of the rubber. In general, the softer the rubber, the greater the friction coefficient of the urethane coating. The harder the rubber, the lower the friction coefficient. There are two types of urethane rubber; JIS K6301 standard JIS A Type (0-100 degrees) and JIS K7215 ASTM D2240, and ISO R868 compliant Shore D type (0-100 degrees). The former tends to be more common.

If using a urethane rubber coating for purposes such as a sound insulation, or vibration or shock absorption, products with a lower rubber hardness of around 50-70 degrees are more suitable. For applications such as flooring, carrying surfaces on conveying equipment or sieving machines, products with greater abrasion resistance are more suitable, with an intermediate rubber hardness of 75-85 degrees. If urethane has a rubber hardness of 90 or greater, that generally means a lower friction coefficient, resulting in products that combine a degree of non-stick performance with abrasion resistance. In cases where greater non-stick performance is required, products can be improved by using additives such as Teflon (fluorine resin) or silicon.

The UNICS UNIRETHANE Series is available in a range of performance products to meet different needs, including outdoor weather resistant additives, conductive additives to combat static electricity, anti-accident additives to prevent factory fires from spreading, and bacterial additives.

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We’re looking for a urethane coating with a low friction coefficient like Teflon.

We recommend using our TEFTHANE Series. Polyurethane is characterized by the fact that it has a high friction coefficient. Although this can improve feeder efficiency, the friction coefficient of materials such as rubber prevents items from moving due to friction on both sides. In cases like that, it is better to use a Teflon coating with a low friction coefficient. As the coating is thinner (10-30μm) however, this has the disadvantage of accelerating abrasion.

It was to resolve issues such as these that we developed the TEFTHANE Series of urethane coatings, which combine the abrasion resistance of urethane with a low friction coefficient. This technique achieves the same level of abrasion resistance as other products, by mixing additives to lower the friction coefficient of urethane whilst maintaining the non-stick properties of Teflon coating, and is therefore suitable for a wide range of different applications.

If you wish to make rubber components non-stick for example, it is necessary to have both a low friction coefficient and abrasion resistance, because otherwise metal will scratch the surface of the rubber when it comes into contact with rubber components. The TEFTHANE Series can be highly effective in cases like this too.

*TEFTHANE is made through polymerization of fluorine resin and silicon resin with the polyurethane base materials. That means that coatings consist of modified urethane raw materials. Care is required with items that are incompatible with silicon resin and when cleaning marks off the surface of the coating. Please consult us before proceeding.

Is it possible to make a bowl from resin materials?

Leave it to us! We have commercial examples that we have installed previously. Resin materials are characterized by the fact that they are light, offer outstanding abrasion resistance and are resistant to marking from work items. The materials used would be MC Nylon or Duracon. The size would include a step of approximately φ200, or it would be a shallow bowl. It is difficult to produce a cylindrical bowl. Other factors to take into account are that it will take time to adjust for vibrations due to lower rigidity, and that the cost might increase slightly because all attachments will be screw mounted.

Resin materials can be used for part-feeder bowls for small parts, but extra thought will need to be put into the design to account for the issue of static electricity. An effective solution would be to use conductive MC Nylon. As MC Nylon has an exceptionally low friction coefficient however, please ensure that you check items with a low friction coefficient.

Please can you give us details of coatings for treating bowls so that they can be used with clothing or food products?

The raw materials used in urethane coatings are produced by manufacturers in accordance with food hygiene regulations and standards set out by public inspection bodies. As part of this process, measurements are taken to ensure that materials are not harmful to human health, including metal content (lead, cadmium, heavy metals, etc.) and ingestion of potassium permanganate. The same standards and inspection certificates are also applied to other plated or surface treated products, including materials such as rubber and plastic.

Compliance with these standards however only means that materials have been checked for suitability. Testing to determine whether surfaces have been disinfected or sterilized is separate. If using on cases, caps or other items for use with food, please rinse urethane surfaces repeatedly with a neutral detergent or cresol aqueous solution. It is prohibited to use neat alcohol in such cases.

Please can you give us details of how to clean and maintain bowls with urethane coatings?

Polyurethane offers no resistance to ethanol, methanol or thinner-based solvents. This means that it cannot be cleaned or wiped with commonly used ethyl alcohol. Instead, you can use a neutral detergent, cresol aqueous solution or a commercially available ethanol disinfectant at a concentration of around 75-80%. If you have to use 100% ethanol, we recommend opting for a nylon coating.

Urethane coated surfaces are also slightly porous. If marks get into the surface, it can alter the color and make cleaning difficult. If coatings are not cleaned thoroughly, it can cause a film to form. If coating parts that will come into direct contact with pharmaceuticals or food products, we therefore recommend a polyethylene or nylon coating instead of urethane.

Can urethane coatings be applied to items after heat treatment?

In general, polyurethane has a temperature limit of up to 80 degrees in continuous use, or up to 100 degrees for short periods. Although you are free to try applying coatings to items if they are lightweight and quickly dissipate heat, it is not usually feasible.

In such cases, we recommend applying a heat resistant sheet material, such as rubber binder sheet. If the item is exposed to oil and becomes hot, it would probably be best to use either a textured epoxy belt sheet or a fluorine heat resistant sheet material on the surface. Sheet materials such as these are attached using rubber epoxy adhesive, which can become detached due to temperature, oil or shock. When selecting an adhesive, please check for properties such as heat, shock and oil resistance.

Can urethane coatings be repaired in situ?

If you are using a two-component material that hardens at ambient temperature, repairs can be carried out in situ because there is no need to heat the area being repaired or use specialist equipment. This only applies to spot repairs however. If carrying out general machinery repairs, or coating or re-coating machinery or parts, it will be necessary to make preparations such as erecting a tent or using sheet curing to prevent coatings from splattering.

In the case of equipment exposed to oil or chemicals in particular, you will need to clean surfaces or apply a primer before proceeding. As treatment can be difficult, there is also a risk that it will affect the operation of other equipment in the surrounding area. In cases such as these, you may get a better result, in terms of delivery date, cost and quality, if you remove the relevant part and bring it to a coating plant for treatment, rather than carrying out repairs in situ.

If it is physically difficult to bring the item in to a plant to be worked on (e.g. sieving machines located inside mines, water wheels, tunnel walls, etc.), or if there is no risk of coating splattering, repairs may be carried out in situ. As indicated previously however, this will require considerable man-hours and preparation. Please also be aware that completion may be delayed by weather conditions, and that adjusting the finish may incur additional costs.

Questions regarding our services

Can we talk to you about exporting overseas?

Please get in touch. We have in-depth knowledge of overseas legislation and are constantly checking the latest information. Please don’t hesitate to contact us at any time, so that we can provide you with advice in line with your circumstances.

Please can you give us details of your delivery inspection standards?

Although we carry out pre-delivery checks in accordance with our own unique standards, delivery inspections are essentially carried out in line with QC process sheets submitted by the manufacturer.

Can you handle urgent delivery deadlines?

It depends on the circumstances, but we will do our utmost to meet your requirements wherever possible. Please get in touch to discuss your needs.

How do we go about requesting a quote?

Please send us drawings or a sketch containing the relevant dimensions. If you are in the vicinity of Osaka prefecture, a member of staff may be able to meet with you in person, depending on the terms of your request.

Do you have a price list available?

Unfortunately the services that we provide are priced differently depending on materials, man-hours and other such factors. Please contact us to request an individual quote.

What are your payment terms?

Payment is on the 5th of the month, two months after the completion date.

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