RU2101315C1 - Nondrying plastic hermetic composition - Google Patents

Abstract

FIELD: building industry. SUBSTANCE: composition has, wt.-%: low-molecular polyethylene 60-80; phenol resin 10-20 and staple fiberglass 10-20 which were mixed at the required parts at increased temperature. Composition can contain additionally colophony or modified colophony, or gossypol resin at amount 25-100 wt.-% of phenol resin amount. Hermetic composition is based on available components involving the secondary raw. Composition is used for producing the protective hermetic compositions. EFFECT: improved quality of composition. 2 cl, 1 tbl

Description

 The invention relates to the creation of protective sealing compounds, in particular non-drying plastic sealants for industrial and civil construction.

 In connection with the development of modern technology and the emergence of new designs and products used in conditions of exposure to high and low temperatures, aggressive environments, the problem of compaction has become important. As sealing materials, sealing compounds are widely used. Since the main types of deformation that sealants experience under operating conditions are shear, tension, and compression, synthetic high-molecular rubbers and various oligomers, as well as plastic materials, serve as their basis.

 One of the most common types of sealing compounds is non-drying known sealants [1, 2, 3] These thermoplastic materials, depending on the temperature, are in a highly elastic or viscous-flowing state, are distinguished by their plastic or plastoelastic properties in working condition and are used to seal demountable or periodically dismantled compounds. They are made, as a rule, on the basis of high and low molecular weight compounds with low unsaturation or fully saturated (polyisobutylene, butyl rubber, ethylene-propylene rubber). These sealing compounds are characterized by high resistance to oxygen, the action of acids, alkalis, oxidizing agents, low gas and water permeability, and are widely used in technology. The composition of non-drying sealants as the main components include polymers, fillers and diluents.

 Known lining material PSG of high molecular weight polyisobutylene, carbon black (carbon black) and graphite, used in the technique of protecting equipment and building structures from corrosion [1] It may additionally contain other fillers talc, asbestos, as well as diluents (paraffins and paraffin oil). This material can withstand the effects of many aggressive chemicals at elevated temperatures.

To seal the joints in large-block concrete structures, a highly filled sealant composition is used, consisting of, by weight low molecular weight polyisobutylene 15-35; high molecular weight polyisobutylene 25-35; bitumen 100; neutral mineral oil 60; ground limestone 500-600; asbestos 80-90 [2]
The most convenient in operation and close to the invention is the UMS-50 mastic used in industrial and civil construction, consisting of PIB-118 polyisobutylene (5), neutral oil (20) and highly dispersed chalk (75) [3] Cold flow or creep at room or at elevated temperatures and low chemoresistance (to acidic media), since the acid-resistant chalk filler is used in the formulation.

 The invention proposes a developed plastic sealing composition of available hydrocarbon and technical raw materials, which is devoid of these drawbacks, i.e., is characterized by low cold flow at elevated temperatures and resistance to acidic and other environments. This goal is achieved by the fact that low molecular weight polyethylene, filler staple fiberglass, diluent phenolic resin (a byproduct of the production of phenol and acetone by the cumene method) in the following proportions, wt. low molecular weight polyethylene 60-80; phenolic resin 10-20; staple fiberglass 10-20. The optimization of the composition of the sealant composition was carried out according to four main indicators: ductility (penetration), chemical resistance and frost resistance, as well as stickiness.

 The novelty of the sealing composition is that in the proposed dispersed system, low molecular weight polyethylene plays the role of a plastic dispersion medium and at the same time due to the partial crystallization of the solid dispersed filler. The main filler is oily staple fiberglass (up to 3 cm long), which gives the sealant the necessary physical and mechanical properties. Phenolic resin, which combines well with low molecular weight polyethylene, plays the dual role of diluent and antioxidant, ensuring the stability of the sealant to oxygen. The absence of an acid-resistant component in the sealant determines its high chemical resistance, in particular to acidic environments. The optimum sealant composition is determined by the level of properties achieved. The content of staple fiberglass is 10-20 wt. with smaller quantities, a noticeable reinforcing effect of fiberglass does not appear, heat resistance decreases, and for large ones, incompatibility of system components and violation of monolithicity are observed. Phenolic resin, added in amounts outside the proposed range (100-20 wt.), Is either a weak diluent (low viscosity lowering effect, low frost resistance), or reduces the compatibility of the polymer matrix with the fiber, disrupting monolithization and reducing the physical and mechanical properties.

 The adhesion and adhesion of the sealant to various surfaces increases with the introduction of 25-100 rosin or gossypol resin to the phenolic resin. These additives have practically no effect on other properties.

Based on the combination of properties of the sealant, it is intended for use in the temperature range from minus 20 to plus 70 ^o and application at a temperature of 30-50 ^o . It can be used in contact with acidic and other environments.

Example 1. The sealing composition is prepared according to the following scheme. In the reactor with a thermostatic jacket and a mixing device, phenol resin is charged with bottoms in the production of phenol and acetone by the cumene method (TU 38.402-62-126-91), which represents a dark viscous mass. A product was used containing 38.9 cumilphenol, 29.7 alpha-methylstyrene dimers, 25.5 unidentified, 2.8 acetophenone and 3.1 (in total) phenol, isopropylbenzene and dimethylphenylcarbinol. The mixture is heated to 80-100 ^o C and with stirring, add the calculated amount of low molecular weight polyethylene by-product of the production of high pressure polyethylene (TU 6-05-1837-82, greasy or wax-like mass of light gray, mol. M. 1500-2000, temperature melting point 65-85 ^o C, melt viscosity 80-120 Pa • s). When the melt is homogeneous, the calculated amount of staple oiled glass fiber up to 3 cm long is introduced (soft waste in the production and textile processing of glass fabrics).

 After loading all the components, the mixture is mixed for 15 minutes and poured into a cylindrical form of polystyrene in a liquid state, where it is cooled to room temperature and compacted. After removing from the mold, samples of sealants in the form of cylindrical blocks are obtained, which are tested by known methods ("Adhesives and sealants". M. 1978, p.181-191). Although tests, as noted in many manuals, are not strictly regulated and are modified taking into account the nature of the samples, nevertheless they characterize the capabilities of the proposed sealing compounds. Note that instead of traditional water absorption, the equilibrium (maximum) swelling in dilute (10) hydrochloric acid was measured, and the stickiness was characterized by the temperature range in which it appeared.

Data on the composition and properties of the sealant according to the described example 1 are shown in the table. The data for other sealant compositions of the above three components are also given there (examples 2-5). In examples 6 and 7, an additive of rosin was used. We took pine extraction rosin (GOST 19113-84) or its modified form (TU 81-05-47-76), which are transparent glassy masses with a softening temperature of 60-75 ^o C and consisting mainly of resin and fatty acids with an acid number of 160 -170. It was added to the recipe last, after the distribution of fiberglass or simultaneously with it. In examples 8 and 9, an additive of gossypol resin was used for the secondary product of oil and fat production from cotton (TU 18 UzSSR 50-83), which is a viscous flowing dark mass, mol. m. 600-1000, specific gravity 0.99 kg / m ³ , acid number 50-70, consisting mainly of fatty and hydroxy fatty acids. Gossypol resin was introduced into the phenolic resin in the second place, i.e. before adding low molecular weight polyethylene.

The table shows that the maximum operating temperature range of the compositions is from minus 20 ^o (frost resistance) to 70 ^o (heat resistance), i.e. in this interval there is no creep or cold flow of the compositions. We note the presence of creep in the composition according to the prototype. Judging by the penetration values of the compositions, they are characterized by good plastic properties. All formulations are highly resistant to hydrochloric acid (slight swelling without weight loss), which was expected due to the absence of acid-resistant components in the formulation. Adhesion, indirectly characterizing adhesion, increases in the region of subzero temperatures with the additional introduction of rosin or gossypol resin into the sealant formulations.

 Given the above set of properties and the availability of the components used, the developed sealing composition is of interest for use in technology in the relevant climatic zones.

Claims (1)

 1. Non-drying plastic sealing composition comprising a polymer component, a filler and a diluent, characterized in that it contains low molecular weight polyethylene as a polymer component, staple fiber as a filler, and a phenolic resin as a diluent in the following ratio of components, wt. Low molecular weight polyethylene 60 80
Staple fiberglass 10 20
Phenolic resin 10 20
2. The composition according to p. 1, characterized in that it additionally contains rosin, or a modified rosin, or gossypol resin in an amount of 25 to 100 wt. from the content of phenolic resin.

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