Method for preparing non-toxic polyurethane curing agent with high solid content

A technology of polyurethane curing agent and high solid content, applied in polyurea/polyurethane adhesives, polyurea/polyurethane coatings, adhesives, etc. Good and other problems, achieve the effect of low free diisocyanate content, high efficiency and high solid content

Inactive Publication Date: 2010-06-02
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The invention aims at the shortcomings of the polyurethane curing agent obtained by the existing polyurethane curing agent preparation method, such as low solid content, high free diisocyanate content, hig...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] A preparation method of non-toxic polyurethane curing agent with high solid content: first add 100 kg of trimethylolpropane (TMP) and 10 kg of benzene into a dehydration kettle, heat to 130°C for 1 hour, and keep the temperature above 60°C. At 60°C, it was dropped into an excess of 780 kg of toluene diisocyanate (TDI). React at 40-50°C for 4 hours to obtain a polyurethane prepolymer, and add nitrogen protection during the dropwise addition. The polyurethane prepolymer is placed in an externally cooled thin film evaporator for primary separation at 130°C and 2000Pa, and for secondary separation at 185°C and 100Pa. Then the separated distillate is pumped into the dilute container with butyl acetate added in advance and heated to prepare a 75% solvent to obtain a polyurethane curing agent. After testing, the free TDI mass content is 0.15%, and the NCO content is 13.5%.

Embodiment 2

[0029] Add 100 kg of a mixture of toluene diisocyanate (TDI) and hexamethylene isocyanate (HDI) to the reactor in a mass ratio of 1:1, and the total amount of trimethylolpropane (TMP) is 2.3 according to the NCO / OH equivalent ratio. For metering, add TMP to a mixture of 2 kg of butyl acetate and 3 kg of xylene and heat it to 130 ° C. After dehydration in the dehydration tank, dropwise add TDI and HDI to the reaction tank, and react at 55 ° C for 4 hours to synthesize a solid content of 50%, polyurethane prepolymer with free diisocyanate content of 8.5%, add nitrogen protection during the dropping process. Place the polyurethane prepolymer in a thin film evaporator at 100°C and 2000Pa for primary separation, and at 189°C and 10Pa for secondary separation. Then the distillate after the secondary separation is pumped into the dilute container that adds solvent in advance, and is mixed with a 75% solvent at 60° C. to obtain a polyurethane curing agent, whose free TDI mass content ...

Embodiment 3

[0031] Adopt 190mol of hexamethylene diisocyanate (HDI) into the reactor, add 100mol of polypentylene glycol (the relative molecular weight is 1000, and the hydroxyl content is 3.3%) into the dehydration solvent cyclohexane for dehydration, and dropwise add it to the reactor. React at 120°C for 6 hours to synthesize a polyurethane prepolymer with a solid content of 50% and a free TDI content of 8.9%, and nitrogen protection is added during the dropping process. Place the polyurethane prepolymer in a thin-film evaporator for primary distillation at 180°C and 5000Pa, and carry out secondary distillation at 210 and 600Pa, and then use a pump to pump the distillate after secondary separation into the diluted distillate with pre-added solvent The container was prepared into 80% solvent at 140° C. to obtain a polyurethane curing agent, wherein the mass content of free diisocyanate monomer was 0.15%, and the NCO content was 7.9%.

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PUM

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Abstract

The invention discloses a method for preparing a non-toxic polyurethane curing agent with high solid content, which comprises the following steps of: 1, dehydrating a hydroxyl organic substance under the condition of a dehydration solvent and nitrogen protection, then dripping the hydroxyl organic substance into 10 to 100 percent of excessive diisocyanate monomer, and then reacting for 2 to 6 hours at the low temperature of between 30 and 90 DEG C to obtain a polyurethane prepolymer; 2, performing secondary separation on the polyurethane prepolymer obtained by the step one by adopting a film evaporator; and 3, pumping separated evaporation residues into a dilution container added with a solvent in advance by a pump, and stirring and diluting the obtained solution to obtain the curing agent. The method has the advantages of synthesizing the polyurethane prepolymer with uniform molecular weight distribution, low viscosity, good fluidity and suitability for separation, and not needing to add a separation assistant. The solid content of the polyurethane curing agent is between 60 and 85 percent, a NCO value is between 7.9 and 13.5 percent, and the content of free diisocyanate is between 0.15 and 0.5 percent.

Description

technical field [0001] The invention relates to a polyurethane curing agent for coatings and adhesives, in particular to a preparation method of a non-toxic polyurethane curing agent with high solid content. Background technique [0002] Polyurethane coatings have excellent performance and are one of the most widely used coating varieties. Polyurethane curing agent is an important part of polyurethane coatings. Polyurethane adhesives have similar properties. However, the residual diisocyanate in the polyurethane curing agent is a highly toxic substance, and the solvent used also pollutes the environment. According to modern environmental protection requirements, polyurethane curing agents must solve two problems: first, reduce the content of free diisocyanate monomers in polyurethane curing agents; second, increase the solid content of polyurethane curing agents to reduce the pollution of solvents to the environment. Therefore, it is of great significance to develop high-...

Claims

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Application Information

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IPC IPC(8): C08L75/04C08G18/82C08G18/10C09D175/04C09J175/04
Inventor 黄洪张心亚梅慈云陈焕钦
Owner SOUTH CHINA UNIV OF TECH
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