JPH0348930B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to prepolymers used as intermediates in the production of polyurethanes, and in particular to polyurethane prepolymers using diphenylmethane diisocyanate. Conventional technology Polyurethane is a liquid or base material that can be easily applied regardless of the shape of the object, and after curing, it becomes an elastic body with excellent airtightness and water discharging properties, and is highly durable, so it is used in civil engineering. It is widely used in construction, ships, vehicles, and other general household items. In particular, when polyurethane is used as a joint material, sealant, adhesive, coating material, etc., it must be prepared in advance so that the elastic material after curing will have a constant quality, responding to a wide range of conditions on the site that are subject to severe changes. Use a prepolymerized isocyanate. Problems to be Solved by the Invention When producing this prepolymer, the equivalent ratio of isocyanate to polyol must be kept at 2.0 or less to allow the reaction to proceed sufficiently, and the content of remaining isocyanate groups must be kept at several weight percent or less. is necessary.
When diphenylmethane diisocyanate is used as the isocyanate, it takes a long time for the reaction to reach this state at room temperature, making it impractical. During the reaction, if the room temperature is raised to below 100°C, the reaction will proceed, but side reactions will occur and the biology of the elastic body will change after curing, causing problems. If a small amount of organic tin compound or organic lead compound is added as a catalyst, the reaction will be 80%
Although the process proceeds smoothly at temperatures below 0.degree. C., the resulting prepolymer lacks stability and increases viscosity and decreases the amount of isocyanate groups incorporated during storage, making it unusable. Means for Solving the Problems As a result of various studies aimed at solving these problems, the present inventors discovered that the addition of an organic zirconium compound was effective and arrived at the present invention. That is, the present invention reacts diphenylmethane diisocyanate and a polyol to produce a polyurethane prepolymer having an isocyanate group at the end, using the general formula (1) (R ₁ COO) ₄ Z _r ...(1) and /or general formula (2) (However, in general formulas (1) and (2), R ₁ and R ₂ represent an alkyl group or a phenyl group.) 0.0005-0.05 parts by weight of an organic zirconium compound represented by the following is added to 100 parts by weight of the prepolymer. This is a method for producing polyurethane prepolymers with excellent storage stability. Examples of the organic zirconium compounds represented by these general formulas include zirconium acetate, zirconium propionate, zirconium butyrate, zirconium 2-ethylbutanoate, zirconium 2-ethylhexanoate, zirconium octoate, and girconium acetylacetonate. In the present invention, the polymers used to produce the prepolymer include water, polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane, and pentaerythritol, ethylene oxide, propylene oxide,
It is a polyether polyol obtained by addition-compounding one or more alkylene oxides such as butylene oxide. In addition to the above, polyester polyols obtained by reacting polycarboxylic acids with bottom molecular weight polyols, polyester polyols obtained by polymerizing caprolactone, and higher fatty acid esters containing OH groups such as castor oil can also be used. Furthermore, a polymer polyol obtained by graft polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate to the above-mentioned known polyether polyol or polyester polyol, and 1.2
- or 1,4-polybutadiene polyols or hydrogenated products thereof can also be used. The average molecular weight of these polyols is usually between 200 and 10000, especially
300-7000 is preferred. If necessary, a base molecular polyhydric alcohol such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, hexanetriol, etc. may be mixed with the polyol. It can also be used as When producing prepolymers, polyols,
Polyhydric alcohol, a mixture of organic zirconium compounds, and diphenylmethane diisocyanate from 40 to
It is made into a prepolymer by reacting at 90℃. At that time, the equivalent ratio (NCO/
OH) is particularly preferably from 1.3 to 2.0, and the amount of free NCO groups contained in the prepolymer is from 0.5 to 5% by weight (hereinafter, % means % by weight). Furthermore, when producing the prepolymer, a plasticizer and a solvent may be added to adjust the viscosity. Examples of plasticizers include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dilauryl phthalate (DLP), butylbenzyl phthalate (BBP), dioctyl adipate (DOA), diisodecyl adipate (DIDA), and trioctyl phosphate (TOP). ), trischloroethyl phosulfate (TCEP), trisdichloropropyl phosphate (TDCPP), propylene glycol adipate polyester, butylene glycol adipate polyester, epoxy alkyl stearate, epoxidized soybean oil, etc., used alone or in combination. do. The amount used is preferably 5 to 100 parts per 100 parts by weight of the prepolymer (hereinafter "parts" indicate upper parts). Examples of solvents include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane, heptane and octane; petroleum solvents ranging from gasoline to kerosene fractions; esters such as ethyl acetate and butyl acetate; acetone, methyl ethyl ketone,
Ketones such as methyl isopropylcetone; ether esters such as cellosolve acetate and butyl cellosolve acetate are used. The prepolymer obtained according to the present invention is stable and can withstand long-term storage, and the cured elastomer exhibits constant physical properties. Therefore, if a one-component type or two-component type composition is made using this prepolymer, it can be used as a joint filler, a sealant, etc. with excellent storage stability, and therefore has extremely high utility value. Examples will be described below. Example 1 4,4'-diphenylmethane diisocyanate (manufactured by Mitsui Toatsu Chemical Co., Ltd.) and average molecular weight were placed in a separable flask equipped with a stirrer, a thermometer, and a nitrogen inlet tube.
Polypropylene glycol and average molecular weight of 2000
4000 polypropylene triol (manufactured by Mitsui Nisso Urethane Co., Ltd.) and diostylphthalate (manufactured by Kyowa Choussan Co., Ltd.) for viscosity control were added and reacted at 80° C. for 6 hours. Zirconium octoate (INTERSTAB CHEMICALS) to complete the reaction
Inc.) was added to 100 parts of prepolymer in an amount of 0.001 part, and the reaction was further continued for 1 hour to obtain terminal NCO groups.
Obtained a clear viscous liquid with 1.03% (theory
NCO%: 1.12). Example 2 0.001 part of the zirconium octoate of Example 1 was added to zirconium acetate (HARSHAW CHEMIC-
A clear viscous liquid having 1.05% of terminal NCO groups was obtained in the same manner as in Example 1, except that 0.01 part of AL CO.) was used. Comparative Example 1 0.001 part of the zirconium octoate of Example 1 was added to dibutyltin dilaurate (manufactured by Sankyoki Synthesis)
A transparent viscous liquid having 0.98% of terminal NCO groups was obtained in the same manner as in Example 1, except that the amount was changed to 0.001 part. Comparative Example 2 A transparent viscous liquid having 1.01% of terminal NCO groups was obtained in the same manner as in Example 1, except that 0.001 part of zirconium octoate in Example 1 was replaced with 0.00025 part of dibutyltin diurirate. Effect of the invention Prepolymer obtained as above at 60℃
Table 1 shows the NCO% and viscosity accelerated aging stability test results. From Table 1, it was found that when an organic zirconium compound is used as a reaction catalyst in producing a polyurethane prepolymer, a polyurethane prepolymer with excellent storage stability can be obtained. 【table】

Claims (1)

[Claims] 1. When producing a polyurethane prepolymer having an isocyanate group at the end by reacting diphenylmethane diisocyanate and a polyol, the general formula (1) (R ₁ COO) ₄ Z _r ...( 1) and/or general formula (2) (However, in general formulas (1) and (2), R ₁ and R ₂ represent an alkyl group or a phenyl group.) 0.0005 to 0.05 parts by weight of an organic zirconium compound represented by the following is added to 100 parts by weight of the prepolymer. A method for producing a polyurethane prepolymer with excellent storage stability.