RU2052478C1 - Process for preparing polyether urethane for adhesion purposes - Google Patents

Abstract

FIELD: manufacture of glues. SUBSTANCE: polyether urethane for adhesion purposes is prepared by reacting crystallizable polyether with diisocyanate in a melt at a NCO/OH ratio of 1.1-1.4, subsequently dispersing it in an aqueous medium or cooling and mechanically grinding it and subsequently converting the dispersed or solid product into a high-molecular polymer due to reaction of the isocyanate groups with water. EFFECT: improved properties of the title product.

Description

 The invention relates to the field of production of polyester urethanes suitable for the manufacture of adhesives or other materials, and can be used in the chemical, automotive, engineering, light and other industries.

Known methods for producing polyurethanes by reacting polyesters with toluene diisocyanate in solution in the presence of a polymer with terminal isocyanate groups, which are further lengthened with water and / or low molecular weight diols to achieve a given solution viscosity. The molar ratio of NCO / OH groups is from 1.15 to 1.80 [1, 2]
The disadvantage of these methods is the need for solvents with a high degree of purification, multi-stage and long process time (in some cases, more than 140 hours).

There is also known a method for producing polyether urethanes (PES) in a melt by reacting a polyester component with a large excess of aromatic diisocyanates, followed by chain extension with ether glycol until the NCO groups disappear [3]
However, the method is characterized by a long duration and low technological effectiveness for industrial production, since after the stages of mixing the components and reaching the specified parameters of the intermediate product, the stage of pouring the melt into the intermediate heated containers for curing follows. After prolonged curing, the polymer is obtained in the form of blocks. Crushing such PES is fraught with great technical difficulties.

Closest to the invention, the technical essence is a method for producing adhesive polyester urethane by reacting a diisocyanate in a melt with crystallizing polyester, followed by cooling in an aqueous medium and grinding [4]
The known method is complicated in terms of technology and hardware design. In addition, special equipment and high energy costs are required at the final grinding stage.

 An object of the invention is to simplify the hardware design and process technology for the production of adhesive polyester urethane in the form of powders, granules.

 According to the invention, the interaction in the melt of the diisocyanate with crystallizable polyester is carried out at a molar ratio of NCO / OH groups of 1.1-1.4, and grinding at the time of cooling of the polymer in water or after it. Polyesters such as poly-1,4-butylene adipate (PBA), polyethylene butylene adipate, polycaprolactone can be used as crystallizable polyester. As the diisocyanate, aromatic and aliphatic diisocyanates, for example, toluene diisocyanate (TDI), 4,4-diphenylmethanediisocyanate, hexamethylene diisocyanate. The process is carried out both in the presence and in the absence of urethane formation catalysts.

 When dispersed in water, surface-active substances (surfactants) such as cellulose derivatives, copolymers of acrylic, methacrylic acids, etc. can be used.

To prepare the adhesive, the polyether urethane obtained according to the invention in the form of granules, a powder is dissolved in an organic solvent (ethyl acetate or a mixture of solvents) with a mass fraction of polymer of 20%. An isocyanate type hardener, for example, polyisocyanate B, can be introduced into the solution (TU 113-03-38-106-90 ) in an amount of 0.5-2.0%
Testing the properties of adhesive joints in laboratory conditions was carried out according to RD 17-66-157-89, and in production conditions when gluing shoe parts from various materials according to the technologies and regulatory documents in force at enterprises.

PRI me R 1. In a glass flask equipped with a propeller stirrer and a heating bath, 200 g (0.1 mol) of PBA mol. 2000 (wt. Fraction of water of not more than 0.04%) with 21.75 g (0.125 mol) TZHTS (65/35 mixture of isomers) at 80 ° ^C. The ratio of NCO / OH-group is equal to 1.25. The mixture was stirred at this temperature for 5 hours to obtain a product with a content of NCO-groups 0,95% The product was cooled ^to 75 ° C and added thereto 250 g of an aqueous surfactant solution. The mixture was stirred vigorously for 0.5 h at 75 ^C. The resulting suspension was cooled polyurethane powder, the powder was separated on a filter, washed with water and dried to constant weight in vacuo at 40-50 ^° C is obtained in virtually quantitative yield PES powder with the following characteristics: average particle size of 200 microns; intrinsic viscosity in dimethylformamide (DMF) 0.9 dl / g;
complete solubility in ethyl acetate.

Bonding strength in laboratory conditions, n / cm: initial 21.5 after 1 day. 31,0
(the gap is mixed).

 The bonding strength of a sole made of polyurethane with a top made of genuine leather after 1 day is 33.6 N / cm, the nature of the gap both in material and in the adhesive joint (mixed).

PRI me R 2. Analogously to example 1, from PVA and TDI with a ratio of CO / CH 1,4 receive a powdered polyurethane with the following characteristics: average particle size of 100 microns; intrinsic viscosity in LMF 0.5 dl / g;
complete solubility in ethyl acetate.

When gluing under laboratory conditions: initial bonding strength 26.8 N / cm; after 1 day 28.4 N / cm;
the nature of the gap is cohesive (by material).

 When gluing shoe parts made of PVC and genuine leather, the bonding strength is 40.1 N / cm (the nature of the gap is mixed).

PRI me R 3. Analogously to example 1 from polycaprolactone mol.m. 2000 and diphenylmethanediisocyanate with a ratio of NCO / OH groups of 1.1, a polyester urethane powder with the following characteristics is obtained: average particle size 300 microns; intrinsic viscosity in LMF 0.54 dl / g;
complete solubility in ethyl acetate.

Bonding strength in laboratory conditions: initial 26.0 N / cm after 1 day 41.8 N / cm
the nature of the gap is cohesive.

 The bonding strength of parts of shoes made of microporous rubber with genuine leather is 22 N / cm; the nature of the gap is mixed.

 PRI me R 4. Analogously to example 1 of the PBA mol.m. 2000 and TDI with a ratio of NCO / OH of 1.5 and below receive a highly viscous product that is difficult to disperse in water.

PRI me R 5. Analogously to example 1, from PVA and TDI with a ratio of NCO / OH of 1.5 and above receive a powdered polyurethane having an increased softening temperature. The use of PES as an adhesive under the current technology is difficult, because when using it necessary to increase the bonding temperature above 140 ° ^C.

PRI me R 6. In a 10-liter mixer with Z-shaped blades load PBA mol.m. 1950 and hexamethylene diisocyanate at a ratio of NCO / OH 1,2, and the reaction mixture was stirred at 80 ° ^C for 4.5 hours. The product was obtained with wt. the proportion of NCO-groups of 0.78% To it at 60 ^about With add the equal in weight to the starting reagents the amount of an aqueous solution of surfactant. The resulting mixture was stirred for 0.5 hours at ⁶⁰ ° C and then cooled to room temperature. The granules are separated on a filter, washed with water and dried to constant weight. Granular polyether urethane has the following characteristics: average granule size 5 mm; intrinsic viscosity in DMF 0.74 dl / g; complete solubility in ethyl acetate.

Bonding strength in laboratory conditions: initial 27.4 N / cm; after 1 day 52.3 N / cm;
the nature of the gap is cohesive.

 The bonding strength of PVC and synthetic leather shoe parts is 58.0 N / cm; the cohesive nature of the gap.

EXAMPLE Example 7 Continuous process for producing PES carried out in an apparatus equipped with two tanks, one of which is polyester at 60-70 ° ^C. These containers diisocyanate and a polyester with the catalyst dissolved therein is fed continuously metering pumps to a mixer where they are mixed at 60-70 ^{° C} for 10 seconds. Dosing pumps provide the necessary ratio of NCO / OH-groups, equal to, e.g., 1, 2. The reaction mixture was fed to a continuous displacement machine, where at 110 ± 6 ^{° C} it is in a period of 5 minutes. Mas. the proportion of NCO-groups in the product exiting the apparatus further 0.65-0.70% under pressure is fed into the dispersant, which also continuously fed to the aqueous surfactant solution was heated to 60 ° ^C. Mixing components produced in volumes close to 1 :1. The resulting dispersion is collected in a reactor with a working drive anchor agitator, where at 50-60 ^{° C} is maintained for an hour. After filling the reactor, the dispersion is poured into another similar reactor. Reactors periodically switch to loading and unloading the product. The mixture is then fed to a suction filter and the polymer is dried. Powdered PES has the following characteristics: particle size 50-200 microns; intrinsic viscosity in DMF 0.6-0.7 dl / g.

 Laboratory bonding strength: initial 19.0 N / cm; after 1 day 39.5 N / cm; the nature of the gap is mixed.

 The bonding strength of synthetic rubber soles with artificial leather upper is 38.4 N / cm, the gap is cohesive (by material).

 Fluctuations in the ratio of NCO / OH groups in the range of 1.15-1.30 do not affect the properties of the resulting PES.

PRI me R 8. Analogously to example 7, the composition after the mixer is fed to an endless conveyor, where it is poured through a switchgear into separate tapes 5-10 mm wide and 1-2 mm thick. The conveyor is fed to a heat chamber, wherein the product is at ¹²⁰ ° C for 2-3 min. Mas. the fraction of NCO groups in the mixture after the heat chamber is 0.60-0.65%. After leaving the heating zone, the conveyor with the product is fed into the cooling water bath. The hardened product belts are removed from the conveyor and fed to the chopper. Prepared low-molecular polymer having terminal NCO-groups in the form of flakes which, after exposure to air at 25 ± 5 ^{° C} and humidity 80 ± 10% for 1 day are converted into a polymer having an inherent viscosity in DMF of 0.8-0.9 dl / g.

Bonding strength in laboratory conditions: initial 20.5 N / cm; after 1 day 31.7 N / cm;
the nature of the gap is mixed.

 The bonding strength of PU soles with synthetic leather upper is 29.6 N / cm, the nature of the gap is mixed.

Claims (1)

 METHOD FOR PRODUCING ADHESIVE POLYEPHIRETHANE by reacting a diisocyanate in a melt with crystallizing polyester followed by cooling in an aqueous medium and grinding, characterized in that the reaction is carried out at a molar ratio of NCO / OH groups of 1.1 - 1.4, and grinding - in moment of cooling or after it.