RU2391362C2 - Polyurethane coating composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polyurethane composition used as a protective coating. The composition contains the following in pts. wt: 770 - polytetramethylene etherglycol with molecular weight of 1950, 200 - 4,4'-diphenylmethanediisocyanate, 80-100 - dimethylformamide, 36 - hydroxyl-containing compound, 100-120 - methylphosphite borate and 15-18 - glycidalmethacrylate. A prepolymer is synthesised first as an initial component by reacting polytetramethylene etherglycol and 4,4'-diphenylmethanediisocyanate in molar ratio OH:NCO-groups equal to 1:2.

EFFECT: composition has better complex properties, specifically high fire- and heat resistance and good physical and mechanical properties, eg high strength and extensibility.

2 cl, 2 tbl

Description

The invention relates to the field of producing flexible polyurethane compositions that can be used as protective coatings with increased fire, heat resistance and high physical and mechanical properties.

A known method for producing boron-containing polyurethanes and polyolefins, involving the use of spirocyclic esters of boric acid as combustion inhibitors, which are added to polymers or their by-products in an amount of 5-50% by weight of the polymer (Patent RU 2039764, class C08G 18/32, 1990) .

The disadvantages of the proposed compounds is that the enhancement of the inhibition of combustion is recommended by the addition of synergists, for example organic or inorganic phosphorus compounds, for example ammonium polyphosphate or phosphoric acid ester, or metal oxides, for example antimony oxide. As a result, imparting increased fire resistance to polyurethanes and polyolefins in this way is not accompanied by the preservation of their high physical and mechanical properties.

A known method for producing phosphorus-containing polyurethanes, which provides for the use of bis (oxymethyl) phosphinic acid as a polyurethane modifier (USSR Author's Certificate No. 560892, class C08G 18/10, 18/38).

However, the obtained polyurethane with increased fire resistance obtained by this method has low physical and mechanical properties and heat resistance. In addition, this method provides a complex composition of the reagents: the use of two immiscible solvents and an anionic emulsifier.

Closest to the proposed is a method for producing phosphorus-borne polyurethanes by reacting a prepolymer obtained on the basis of polytetramethylene ether glycol with a molecular weight of 1950 and 4,4′-diphenylmethanediisocyanate with a molar ratio of OH: NCO groups equal to 1: 2 with a hydroxylphosphorus-containing compound in which the compounds use phosphorus-containing polyols (Patent RU 2275388, class C08G 18/38, publ. 04/27/2006).

Increasing the fire resistance of polyurethane, this method as a whole slightly improves its physical and mechanical characteristics and does not increase heat resistance.

The objective of the invention is the creation of a polyurethane composition with an improved set of properties, namely with increased fire and heat resistance and high physical and mechanical characteristics.

The technical result of the invention is to obtain a polyurethane composition with high fire and heat resistance and high physical and mechanical properties.

The presented technical result is achieved in that the polyurethane composition containing a prepolymer obtained on the basis of polytetramethylene ether glycol with a molecular weight of 1950 and 4, 4'-diphenylmethanediisocyanate with a molar ratio of OH: NCO groups equal to 1: 2, dimethylformamide and hydroxyl-containing compound additionally contains borate methylphosphite and glycidyl methacrylate, in the following ratio of components of the composition, parts by weight:

polytetramethylene ether glycol - 770;

4,4′-diphenylmethanediisocyanate-200;

hydroxyl-containing compound - 36;

methyl phosphite borate - 100-120;

glycidyl methacrylate - 15-18;

dimethylformamide - 80-100.

In this case, 1,4-butanediolily 1,6-hexanediol is used as the hydroxyl-containing compound.

The introduction of methyl phosphite borate and glycidyl methacrylate into the proposed polyurethane composition under the conditions of preparation of the composition presented below leads to their interaction with the formation of a spatial polymer and the simultaneous formation of semi-interpenetrating networks in the form of a three-dimensional crosslinked framework in which the linear polyurethane is distributed in the interstitial spaces. As a result, possible interfacial interaction and supramolecular formations contribute to an increase in the strength properties of the material while maintaining its elasticity. An increase in packing density, which indicates an improvement in the regularity of the linear polymer-spatially crosslinked polymer system, also leads to an increase in the heat resistance of the polyurethane composition.

The presence of methyl phosphite and glycidyl methacrylate in the borate structure of phosphorus and boron atoms, which are combustion inhibitors, leads to an increase in the fire resistance of the entire polyurethane composition. Their increased content contributes to the achievement of maximum results without resorting to the use of large concentrations.

The quantitative ratio of the components in the considered polyurethane composition is optimized in such a way as to obtain a polyurethane composition with the claimed properties. A decrease in the content of methylphosphite borate and glycidyl methacrylate below the declared value does not lead to self-extinguishing of the polyurethane composition, and an increase leads to an undesirable deterioration of its physical and mechanical properties. This can probably be explained by the fact that with an increase in the content of newly introduced components, the rate of their interaction and, accordingly, the cure rate of the samples change. Moreover, the formation of the network structure occurs no longer in a liquid medium, but in a medium with a higher viscosity, which prevents the formation of a regular structure of semi-interpenetrating networks.

A polyurethane coating composition is prepared as follows. First, a prepolymer is synthesized as a starting material by reacting polytetramethylene ether glycol with a molecular weight of 1950 and 4,4'-diphenylmethanediisocyanate in a 1: 2 molar ratio. For this, polytetramethylene ether glycol and 4,4′-diphenylmethanediisocyanate are charged into a reactor heated to a temperature of 60 ° C. With stirring, increase the temperature of the reaction mass to 80 ° C. The process is continued at the same temperature for 30 minutes. Monitoring the progress of the reaction is carried out by increasing the viscosity of the reaction mass. The resulting prepolymer is cooled at room temperature to 60 ° C. The prepolymer synthesized by the interaction of polytetramethylene ether glycol and 4,4′-diphenylmethanediisocyanate in a 1: 2 molar ratio is an industrial intermediate (SKU-PFL-100).

A solution of the hydroxyl-containing compound (1,4-butanediol or 1,6-hexanediol) in dimethylformamide at a molar ratio of prepolymer: hydroxyl-containing compound equal to 1: 0.1 is introduced into the reactor containing the prepolymer using a separatory funnel, so that the entire volume dosed for 10 minutes. The temperature of the reaction mass is increased to 80 ° C and the synthesis is carried out for 30 minutes in an inert medium. Monitoring the progress of the reaction is carried out by increasing the viscosity of the reaction system and the content of NCO groups. The resulting polyurethane solution is cooled at room temperature to 30 ° C.

Next, the calculated amount of a solution of methylphosphite borate in dimethylformamide is added to the reactor and stirred until complete dissolution. Then, the calculated amount of a solution of glycidyl methacrylate in dimethylformamide is gradually added so that the temperature of the reaction mass does not exceed 30 ° C. In this case, the molar ratio of reagents is 1: 2, respectively. After adding the entire amount of glycidyl methacrylate, the reaction mass is stirred for 5 hours at a temperature of 50 ° C. Monitoring the progress of the reaction is carried out by changing the number of epoxy groups. The solution is then applied to a glass surface and thermostatted at 70 ° C for 12 hours, followed by evacuation to a film.

The structure of the obtained polyurethane composition is confirmed by the infrared spectrum (liquid paraffin), ν, cm ^-1 : 3400 (O-H), 2910 (СН3), 1740 (СО), 1650 (С = С), 1160 (Р = О) 1060 (P-O-C), 1336, 1456 (B (III) -O).

Tables 1 and 2 show the compositions of the various variants of the polyurethane compositions and their properties, respectively. Tests of the physical and mechanical properties of the samples were carried out in accordance with GOST 14236-81; fire resistance was estimated by the burning time (decay) and weight loss of the samples after exposure to an open flame source according to GOST 21207-81; heat resistance was estimated by the temperature of the loss of 50% of the mass of the samples according to thermogravimetric analysis on a Paulik-Paulik and Erdey derivatograph system (Hungary).

Analysis of the data presented in table 2 shows that the proposed polyurethane composition acquires increased heat resistance, strength while maintaining a high level of fire resistance and extensibility in comparison with the prototype.

Table 1 The compositions of the polyurethane compositions Name of components The number of components, parts by weight Example 1 Example 2 Example 3 Example 4 polytetramethylene ether glycol 770 770 770 770 4,4′-diphenylmethanediisocyanate 200 200 200 200 hydroxyl-containing compound: 1,4-butanediol 1,6-hexanediol 36 36 36 36 Methyl Phosphite Borate 80 one hundred 120 140 glycidyl methacrylate 12 fifteen eighteen 21 dimethylformamide 70 80 one hundred 110

table 2 Properties of polyurethane compositions The name of indicators Prototype (Patent RU2275388, example 1) Example Number one 2 3 four Density, g / cm ³ 1.15 1.28 1.37 1.45 1,56 Conditional Strength, MPa 53 54 65 63 52 Relative extension, % 830 832 840 848 825 Smoldering time, s four four 3 3 2 The loss of mass of the sample,% 3,1 3.0 2.5 2.2 2.0 Temperature loss 50% mass, ° C 380 410 435 460 453

Claims (2)

1. Polyurethane coating composition containing a prepolymer based on polytetramethylene ether glycol with a molecular weight of 1950 and 4,4'-diphenylmethanediisocyanate with a molar ratio of OH: NCO groups equal to 1: 2, dimethylformamide and hydroxyl-containing compound, characterized in that it is additionally contains methylphosphite borate and glycidyl methacrylate in the following ratio of components of the composition, parts by weight:
polytetramethylene ether glycol 770
4,4'-diphenylmethanediisocyanate 200
hydroxyl-containing compound 36
methyl phosphite borate 100-120
glycidyl methacrylate 15-18
dimethylformamide 80-100 2. The polyurethane composition according to claim 1, characterized in that 1,4-butanediol or 1,6-hexanediol is used as the hydroxyl-containing compound.