"Ws15" Spray Polyurethane Application Guide
发布时间： 2019-07-25 13:54 Author: Polyurethane foam machine Source: http: //motokone.com
Published: 2019-07-25 13:54
Each kind of grinding has its own particularity. Its unique properties determine its required coating hardness and thickness. In practice, please refer to the following rules:
1.0 If you are unsure or unable to test, please believe that the thicker the coating, the better.
2.0 Polyurethane wear is not exponential. If the coating is doubled, the service life of the coating may be 4 to 6 times the original coating.
3.0 The abrasion resistance of polyurethane coating in mud environment will be better than in dry friction environment. This is mainly due to the cooling water effect of the polyurethane coating on the mud. Because as a natural insulator, polyurethane retains the heat generated under dry friction conditions without releasing it.
4.0 Polyurethane protective coatings have a long history of handling and supporting smaller parts such as 6mm or smaller objects. However, the polyurethane material recently researched and developed by our company shows that its coating can also be used to carry and handle silica with a diameter of 355mm.
5.0 Polyurethane has a deflection ratio of 20%. Special attention should be paid to this point in the design of the application area with load requirements.
6.0 In terms of wear resistance, only rubber and polyurethane are comparable. Other materials such as polyurea, epoxy, vinyl, and other polymer coatings are not comparable to polyurethanes in their abrasion resistance.
Polyurethane has good overall chemical resistance and its performance is more outstanding under immersion conditions. In practice, please refer to the following rules:
1.0 The brittle crack point of pure polyurethane products is -56 ℃
2.0 The working thermal resistance of polyurethane varies greatly depending on the type selected. Aliphatic series such as BR-3S, NR-5S and NR-7S can withstand temperatures of up to 100 ℃. Our products NR-95HT products can withstand the temperature of contact objects such as hot asphalt can reach 173 ℃ to 225 ℃
3.0 Unless otherwise specified, all chemical resistance trend charts are based on ambient temperature. An acidic solution is much more corrosive at 70 ° C than at 21 ° C. In the case of polyurethane immersed in acidic materials, the temperature should not be higher than 60 ° C. For temperatures above the above, please consult Normanck.
4.0 The chemical resistance of polyurethanes is expressed by the PH value of 3-11. Testing is required when the pH value is between the boundaries, such as 2-3 or 11-12. It is not recommended to use this product in environments where the pH is below 2 or above 12.
5.0 Normank polyurethane coatings work better in water, saline, and desalinated water.
6.0 In most cases, the smoke emitted is more corrosive than the actual liquid, especially the liquid at the liquid-gas interface.
7.0 When polyurethane is in water, it will continue to cure after 18 hours of initial curing.
8.0 For areas under vacuum service, allow 7 days for the polyurethane coating to harden. This will give enough time for the polyurethane to bond to the matrix.
9.0 If in doubt about the performance of polyurethane coatings in a chemical environment, test, test and test. Polyurethane can be tested using a metal block that is completely encapsulated by a polyurethane coating and has a fixed thickness of polyurethane coating. One end of the metal block must have a hole at least 6 mm wide. After measuring the weight of the metal, insert the non-porous end of the metal block into the chemical environment and leave it for 7 days. Then remove the metal block and reweigh it. If the weight change range of the metal block is less than 5% (or equal to 5%), then 99% can be considered that the performance of polyurethane in this chemical substance environment is not a problem. At the same time, visually inspect the coating surface for irregularities.
1.0 Polyurethane as a natural insulator also has the potential to reduce noise. Softer coatings generally have better noise reduction effects than harder coatings.
2.0 For our company's BR-3S, a 0.5mm coating can reduce noise by 7 decibels and a 1mm thickness coating can reduce noise by 14 decibels. This effect has been proven in vibrating feeder hoppers.
1.0 Polyurethane is a natural insulator. The resistivity of cured polyurethane sheets with a thickness of typically 25 μm is as high as 400 to 700 volts. When the thickness of the polyurethane coating after spraying is 25 μm, the resistivity is as high as 13,000 volts.
2.0 Implantable antistatic materials can be used to reduce polyurethane resistivity.
Polyurethane materials deform but are not compressed. Just like stepping into a puddle, water will move to other places but its space will not shrink. Polyurethane material can withstand a large amount of deflection of 20%. A deflection of more than 20% can cause premature degradation of the polyurethane material. The higher the hardness of the polyurethane coating, the lower the amount of large deflection, and the lower the hardness, the higher the amount of deflection it can withstand. For example, a 25cm thick coating can achieve a large deformation value of 5cm, and for a coating thickness of 250μm, the deformation value can reach 50μm.
1.0 Polyurethane coating needs to determine the thickness of the coating itself according to the actual conditions of the load. Such as the size of the loaded material, the height of the material, the speed of the material, the degree of dryness and wetness, and the impact angle are all factors that affect the thickness of the coating. Our company can provide advice on coating thickness according to specific conditions, and please consult our company if necessary.
1.0 According to the classification of flame spread and smoke level specified in ASTM E-84, the flame spread rating of polyurethane is usually lower than 40, and the smoke volume is usually lower than 30.2.0. A flame retardant can be added to the polyurethane coating to improve its fire resistance. Both solvent-borne and 100% solid polyurethane spray products can be flame retardant added and in some cases are self-extinguishing.
Color maintenance ability
1.0 Without special design and manufacture, all polyurethane materials will yellow over time. Due to the amine component of the cured product range, Norman polyurethane will fade or turn yellow. However, we have produced BR-3SV products for spraying outdoor products or as topcoats for our amine hardened products to prevent discoloration.
2.0 All our polyurethane products can be sprayed with a top coat on the outer layer to maintain color stability. These top coats can be outdoor polyurethane paints or our own BR-3SV.
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