The glue structure for splice closure on the basis of polyurethane is popular in the different fields of the industry and in life. In construction polyurethane sealant can be used for closing up of internal and external joints. Material protects seams of designs from moisture hit, allowing to condense connections of elements.
The polyurethane sealant having the mass of useful properties provides reliability of various connections, is suitable for closing up of emptiness. Material is irreplaceable not only when sealing water pipes, but also puttying of slots of building constructions. The popularity of structure can be explained with property of elasticity and excellent coupling with surface that excludes material deformations.
Types of polyurethane sealant
Sealant polyurethane can be chosen two options: one-component and two-component. Material of the first type has the pastelike structure representing the polyurethane prepolymer having low molecular weight. Polymerization of single-component structure happens under the influence of water vapor right after opening.
Polyols and special hardeners before which mixing it is possible to store material long time are part of two-component polyurethane mix. If filling depth considerable, then occurs reduction of polymerization rate of mix. It can be explained with slow moisture penetration deeply.
Time of drying of single-component structure depends on temperature and air humidity. Per day material hardens on 2-3 mm. The period of full drying of two-component mix is on average equal 24 hours. It depends on ratio of components of material and air temperature.
Properties and range of application
Polyurethane sealant in the form of liquid mix is the expendable material applied in the course of performance of work on seal of various joints and seams having width no more than 3 cm. The structure on the basis of synthetic elastomer allows to pressurize reliably roof, it can be put between the fastened logs, to use for closing up of intertiled seams for arrangement of reinforced concrete constructions.
Mix on the basis of polyurethane is suitable for processing of seams of products from natural stone. It is impossible to apply for this purpose silicone sealant as the structure destroys stone. Polyurethane mix allows to create imperceptible joints. It is better to use material for designated purpose right after packing opening. To cause structure with layer no more than 0.5 cm. It allows to seal reliably covering and to save mix which basic purpose is as follows:
- Closing up of interpanel joints of facades of houses.
- Sealing of door assemblies and double-glazed windows.
- Processing of products from natural stone.
- Creation of strength connections of designs from metal.
- Waterproofing of joints at arrangement of roof.
Polyurethane sealant is not capable to change form and to shrink therefore it is irreplaceable when processing seams of metal goods. The property to transfer the increased vibration allows to apply mix in automotive industry. Other important characteristic of material is connected with resistance to influence of low and high temperatures. Sealant is highly elastic therefore it resists to abrasion, punctures, destructions. Use of polyurethane glue is widespread in the following spheres:
- shipbuilding;
- automotive industry;
- construction of buildings;
- sanitary works;
- arrangement of reservoirs.
Resistance of material to deformation is caused by availability of property of hardness. The rate has to be certain number of units that allows to make processing of various joints:
- 15 - closing up of seams between panels, roof joints, various corners;
- 25 - consolidation of joints of materials in the conditions of constant humidity;
- 40 - sealing of expansion seams in designs from reinforced concrete or glass;
- 50 - use for sealing of joints of metal designs;
- 60 - application in the sphere of automotive industry and in shipbuilding.
Sealant on the basis of polyurethane is suitable for pasting of metal, concrete, wooden and plastic parts, allows to create connections with high strength.
Advantages and shortcomings of polyurethane sealant
Polyurethane sealant, resistant to rust, has the high level of self-adhesion. The structure can be put in the winter at frost more than -50 °C. It does not contain solvents, does not emit toxic agents after drawing, has the long term of use, performs dye functions as it can be painted. Polyurethane sealant has the following advantages:
- fast drying;
- moisture-proofness;
- fast hardening;
- total absence of shrinkage;
- high level of elasticity and self-adhesion;
- resistance to influence of ultraviolet rays.
Polyurethane mix does not lose the functional and decorative qualities throughout long time. Storage life of material in packing has to make no more than 9 months. The single-component mixes packaged in buckets or tubas are most demanded.
Sealant on the basis of polyurethane consists of the substances capable to cause allergic reaction therefore rubber gloves are necessary for work with material. Mix should not get on open areas of skin as it contains the isocyanates or toxic substances emitting carbon dioxide in structure for closing up of joints at polymerization. For this reason thickness of the put layer of mix should be limited.
Material is better to apply on surfaces with humidity more than 9-10%. Before use of polyurethane glue for sealing it is important to check its adhesion to any given surface, having studied the instruction. Packing with structure has to be opened before performance of work at once, otherwise material will quickly lose the useful properties.
Mixes on the basis of polyurethane are unstable to influence of the high temperatures reaching +120 °C and more that reduces adhesive strength. Other lack of single-component structure consists in restriction on application temperature which should not be below -10 °C. Material properties is similar to characteristics of two-component structure which does not differ in respect of need of use prior to sealant polymerization.