JPS6315294B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a one-component urethane resin, and more particularly to a method for producing a one-component urethane resin that is easy to produce and has excellent physical properties in the resulting cured product by selecting a specific polyol. Conventionally, two-component polyurethane elastomers, which are obtained by reacting active hydrogen group-containing liquid diene polymers with organic polyisocyanate compounds as raw materials for urethane resins, have been used in many applications due to their excellent low-temperature properties and water resistance. used in the field. However, this two-component reactive urethane resin has a very fast curing reaction, and can be used to form sheets using various kneading machines and molding machines, or as a modifier for asphalt for road paving, coating agents, and adhesives. In the field of pharmaceuticals, etc., it is difficult to take sufficient time for molding and working, and furthermore, the physical properties of the cured product obtained are not sufficient. Therefore, in order to improve the physical properties of the cured product, attempts have been made to add low molecular weight compounds such as ethylene glycol and 1,4-butanediol, and although some improvement in physical properties has been achieved, This has not resulted in a fundamental solution. Therefore, as a further improvement, a moisture-curable one-component urethane resin, which is a liquid diene polymer containing isocyanate groups obtained by reacting a liquid diene polymer containing active hydrogen groups and an organic polyisocyanate compound, is known. It is being However, the cured products obtained by moisture curing one-component urethane resins do not have sufficient physical properties, especially elongation properties, and when used as adhesives, for example, they have the drawback of insufficient peel strength and lack of reliability. The present inventor has conducted extensive research into improving the physical properties of cured products of one-component urethane resins useful as adhesives, coating agents, asphalt, resin improvers, etc. Various studies were conducted on the effects of adding other polyols to the polymer. As a result, it has been found that when a specific polyol is used, a one-component urethane resin that eliminates the conventional drawbacks can be efficiently obtained. Furthermore, when the reaction is carried out in the presence of a plasticizer, the reaction can be carried out without any disadvantages even when the amount of free NCO in the reaction product is 5% by weight or less, and a one-component urethane resin with low viscosity can be obtained. Furthermore, it has been found that a cured product obtained from a one-component urethane resin containing a plasticizer has good physical properties, and has particularly excellent elongation properties. The present invention has been completely achieved based on these findings. That is, the present invention involves plasticizing (A) a liquid diene polymer containing active hydrogen groups, (B) a polyol with a molecular weight of 5 to 500 containing a hydroxyl group bonded to at least one secondary carbon, and (C) an organic polyisocyanate compound. The present invention provides a method for producing a one-component urethane resin, which is characterized in that the reaction is carried out in the presence of an agent. The active hydrogen group-containing liquid diene polymer (A) used in the present invention has an active hydroxyl group such as a hydroxyl group, an amino group, an imino group, a carboxyl group, or a mercapto group at the molecular end and has a number average molecular weight of 300 to 25,000, preferably Better is a liquid diene polymer with a weight of 500 to 10,000. These liquid diene polymers include diene polymers and diene copolymers having 4 to 12 carbon atoms, and copolymers of these diene monomers and α-olefinic addition polymerizable monomers having 2 to 22 carbon atoms. be. Specifically, butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-
Acrylonitrile copolymer, butadiene-2-
Examples include ethylhexyl acrylate copolymer and butadiene-n-octadecyl acrylate copolymer. These liquid diene polymers can be produced, for example, by subjecting a conjugated diene monomer to a heating reaction in the presence of hydrogen peroxide in a liquid reaction medium. The liquid diene polymer thus obtained contains an average of 1.7 to 3.0 hydroxyl groups as functional groups. The fine structure of these liquid diene polymers is not particularly limited, but when flexibility is desired, those having 50% or more of 1,4 bonds are used. Next, (B) used in the present invention has a molecular weight of 50 to 500 and contains a hydroxyl group bonded to at least one secondary carbon.
The polyols include 1,2-propylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-pentanediol, 2,
3-pentanediol, 2,5-hexanediol, 2,4-hexanediol, 2-ethyl-
Examples include 1,3-hexanediol, cyclohexanediol, glycerin, N,N-bis-2-hydroxypropylaniline, N,N'-bishydroxyisopropyl-2-methylpiperazine, ethylene oxide adduct of bisphenol A, etc. Can be done. As the polyol used in the present invention, a diol is usually used, and a diol having two hydroxyl groups bonded to a secondary carbon is more preferably used. In the present invention, polyols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,
If 6-hexanediol or the like is used, the reaction system will increase in viscosity and may solidify, making it impossible to achieve the object of the present invention. Also,
There is no particular restriction on the amount of the polyol with a molecular weight of 50 to 500 containing a hydroxyl group bonded to at least one secondary carbon. It is appropriately determined in consideration of the molecular weight and active hydrogen group content of the liquid diene polymer contained, and the molecular weight and hydroxyl group content of the polyol. However, usually (A):(B)=
It is used in a range of 8:2 to 2:8 (equivalent ratio). Next, examples of the organic polyisocyanate compound that reacts with the active hydrogen groups of (A) and (B) to obtain a one-component urethane resin include tolylene diisocyanate, diphenylmethane diisocyanate (MDI), and crude MDI. , liquid modified product of diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, cyclohexane phenylene diisocyanate, chlorophenylene diisocyanate, naphthalene-1,5-
Diisocyanate, xylylene-2,2'-diisocyanate, isopropylbenzene-2,4-diisocyanate, polymethylene polyphenyl isocyanate, triphenylmethane triisocyanate, isophorone diisocyanate, polypropylene glycol or triol and tolylene diisocyanate addition reaction product, trimethylolpropane Examples include addition reaction products of 1 mol and 3 mol of tolylene diisocyanate. Next, there are no particular restrictions on the plasticizer, and various kinds of plasticizers can be used, such as dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl phthalate.
Phthalic acid esters such as n-octyl phthalate, linear dibasic acid esters such as dioctyl adipate, dioctyl azelate, dioctyl sebacate, tri-2-ethylhexyl phosphate, fresyl phosphate, tricylenyl phosphate, etc. Examples include oils such as phosphoric acid esters, naphthenic oils, aroma oils, and alkyl aroma oils. The plasticizer used here may be selected appropriately depending on the use of the one-component urethane resin, taking into consideration heat resistance, cold resistance, chemical resistance, electrical properties, compatibility with other raw materials, etc. . The amount of plasticizer used here is not particularly limited, and is 5 to 70% by weight, preferably 20 to 70% by weight based on the one-component urethane resin.
It may be determined as appropriate within the range of 50% by weight, taking into consideration workability, usage, etc. Furthermore, in the production method of the present invention, a tertiary amine, metal salt, or organometallic compound may be used as a catalyst if necessary. The reaction to obtain the one-component urethane resin of the present invention is usually
The reaction is carried out at an NCO/active hydrogen group (equivalence ratio) of 1.6 or more, preferably 2.0 or more, under an inert atmosphere such as dry nitrogen, at a reaction temperature of 10 to 150°C, and a reaction time of 0.5 to 10 hours. If the equivalent ratio of the organic polyisocyanate compound is small, chain extension occurs due to the urethane reaction, which increases the molecular weight and increases the viscosity, which is undesirable.On the other hand, if it is too large, the organic polyisocyanate compound monomer remains, making it safe to use. Undesirable in terms of sex. The method of the present invention can be carried out essentially without a solvent, but if necessary, a solvent without active hydrogen groups may be used, such as ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, acetone, toluene. , xylene, tetrahydrofuran, dioxane, dimethylacetamide, etc. however,
When these solvents are used, there is a drawback that these solvents must be removed from the reaction product after producing the one-component urethane resin. but,
Use of these solvents has the advantage of lowering the viscosity of the reaction system and suppressing the increase in molecular weight due to the urethane reaction even if the NCO/active hydrogen group (equivalence ratio) is relatively small. As detailed above, the production method of the present invention provides good physical properties of the cured product obtained by moisture curing, suppresses thickening during production, and obtains a low-viscosity one-component urethane resin. Moreover, it has excellent stability during storage. In addition, since the reaction is carried out in the presence of a plasticizer, it is possible to obtain a one-component urethane resin with a lower viscosity, and the content of organic polyisocyanate compound monomer in the reaction product is reduced, making it safer. This makes it possible to obtain a preferred one-component urethane resin. The one-component urethane resin having isocyanate groups obtained by the method of the present invention can be easily applied alone or mixed with various solvents as necessary using a spray gun, brush, roll coater, flow coater, etc. The film can be cured by moisture in the air. Therefore, it can be suitably used for coating waterproofing materials, paints, anticorrosive coatings, and even breakage and shatterproof coatings for glass bottles, glass windows, and the like. The obtained film has excellent physical properties,
It has particularly preferable elongation. In addition, one-component urethane resin is not limited to use as a coating agent, but can be used in many other ways, such as as a modifier for asphalt and water-soluble resins, for molding sheets, and as an impregnating agent for porous materials such as textile products. Can be done. Moreover, since the one-component urethane resin obtained by the present invention has a low viscosity, it has the characteristic that it can be blended with a large amount of various fillers, and a cured product can be obtained at low cost. Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 7, Comparative Examples 1 to 5 Liquid polybutadiene, low molecular weight diol (OH ratio 1:1), and plasticizer (parts by weight) shown in Table 1 were charged into a reaction vessel, and the mixture was heated at 70°C under a reduced pressure of 1 mmHg. Dehydrated by heating for hours. Next, after adding a predetermined amount of an organic polyisocyanate compound and stirring for 2 hours,
The temperature was raised to 80°C, and the reaction was carried out under heating and stirring for 3 hours to obtain a one-component polyurethane resin. Table 1 shows the properties of the one-component polyurethane resin obtained. Further, the obtained one-component urethane resin was injected into a mold of 2 x 150 x 300 mm and humidity-cured for 14 days at 25°C and 60% humidity to obtain a cured product sheet. The physical properties of the obtained cured product sheet were measured according to JIS-K6301.
The results are shown in Table 1. Comparative Example 6 Hydroxyl group-containing liquid polybutadiene used in Examples
92.4 parts by weight, N,N-bis-2-hydroxypropylaniline 7.6 parts by weight, dioctyl phthalate
52.4 parts by weight, liquid modified MDI 22.3 parts by weight (NCO/
OH=1.05) and 0.5 parts by weight of di-n-butyltin dilaurate were cast according to the example, and then 120
It was cured under pressure at 70°C for 120 minutes and cured at 70°C for 15 hours to obtain a two-component cured urethane resin sheet. The physical properties of this sheet were measured as follows. Tensile 14.5Kg/ ^cm2 Elongation 235% Tear 8.7Kg/cm Hardness Shore A 46 JIS-D 11

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Claims (1)

[Claims] 1. (A) a liquid diene polymer containing active hydrogen groups, (B) a polyol with a molecular weight of 50 to 500 containing a hydroxyl group bonded to at least one secondary carbon, and (C) an organic polyisocyanate compound in the presence of a plasticizer. A method for producing a one-component urethane resin, which is characterized by reacting with.