CN1116328C - Paint curing agent 4,2'-and 4,4'-diphenyl methane diisocyanate prepolymer and its prepn - Google Patents
Paint curing agent 4,2'-and 4,4'-diphenyl methane diisocyanate prepolymer and its prepn Download PDFInfo
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- CN1116328C CN1116328C CN 00127692 CN00127692A CN1116328C CN 1116328 C CN1116328 C CN 1116328C CN 00127692 CN00127692 CN 00127692 CN 00127692 A CN00127692 A CN 00127692A CN 1116328 C CN1116328 C CN 1116328C
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- diphenylmethane diisocyanate
- prepolymer
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- paint
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Abstract
The present invention relates to a paint curing agent 4, 2'-and 4, 4'-diphenyl methane diisocyanate prepolymer and a preparation method thereof. Trimethylol propane, acetate solvents and antioxidants are added into a reaction vessel for refluxing and dewatering at 130 DEG C to 150 DEG C, and melted 4, 2'-and 4, 4'-diphenyl methane diisocyanate mixtures are added to react for 1 hour at constant temperature of 40 DEG C after reaction liquid is cooled to 40 DEG C; the reaction is continuously carried out for 1 hour when temperature is raised to 80 DEG C to 90 DEG C, and products are discharged when cooled to 60 DEG C. The products are mainly used as curing agents for polyurethane paint, and the paint curing agent has the characteristics of no triphenyl solvents, low toxicity, etc.; when the paint curing agent is used for paint, a paint film has the advantages of high toughness and elasticity and strong abrasion resistance.
Description
The invention relates to a coating curing agent, in particular to a polyurethane coating curing agent 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer and a preparation method thereof.
At present, the most common production method of polyurethane curing agent at home and abroad is to react trimethylolpropane with Toluene Diisocyanate (TDI) to generate a prepolymer, and the schematic structure of the prepolymer is as follows:
during the production process of the prepolymer, unreacted toluene diisocyanate and excessive toluene diisocyanate residues exist, and the toluene diisocyanate has high gas phase toxicity and needs to be removed. The product at present internationally such as Desmodur L-75 of Germany, wherein the content of free toluene diisocyanate is below 0.5%, the corresponding domestic product such as 7110A, wherein the content of free toluene diisocyanate is more than 2%, the content of free monomer is more than 2% according to the European Community, the toxic mark should be marked, the biggest harm of Toluene Diisocyanate (TDI) to human body is its steam, TDI steam stimulates eye mucous membrane, has strong lacrimation effect, stimulates respiratory system after inhalation, causes dry cough and laryngalgia, and long-term inhalation of TDI steam causes headache, bronchitis and asthma, and can also react with protein of human body to generate denatured protein, thereby causing allergic reaction and dyspnea of human body. In order to solve the toxicity problem of free monomer toluene diisocyanate in the paint curing agent toluene diisocyanate prepolymer, the invention takes the mixture of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate (MDI) as raw material to prepare the paint curing agent prepolymer, because the vapor pressure of MDI is far lower than that of TDI, the toxicity of the prepolymer of the invention is lower (below 25 ℃, the vapor pressure of TDI is 3Pa, and the vapor pressure of MDI is less than 0.001 Pa). The prepolymers of the present invention are therefore less toxic.
The invention aims to prepare the prepolymer of the 4, 2 '-and 4, 4' -diphenylmethane diisocyanate by using the mixture of the 4, 2 '-and 4, 4' -diphenylmethane diisocyanate (MDI) as the raw material, and the prepolymer has the characteristics of good stability, low toxicity and the like, and the paint film has good toughness and elasticity and strong wear resistance after being painted.
The schematic unit structural formulas of the coating curing agent and the 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer are as follows:
the product indexes of the prepolymer are as follows (the following contents are all weight percentages):
(1) appearance: a colorless liquid;
(2) solid content: 45 +/-3%;
(3) NCO content: 10-15% (based on total solids);
(4) storage stability: for 1 year.
The preparation method comprises the following steps: adding trimethylolpropane, an acetate solvent and an antioxidant into a reaction kettle, stirring, performing reflux dehydration at 130-150 ℃, cooling a reaction liquid to 40 ℃ after dehydration is finished, adding a melted mixture of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate, stirring and preserving heat at 40 ℃ for reaction for 1 hour, then heating to 80-90 ℃, stirring and preserving heat for reaction for 1 hour, cooling to 60 ℃, and discharging to obtain 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymers, wherein the dosage of each reactant is as follows: (the following are all weight percentages):
trimethylolpropane: 10 to 20 percent of the total weight of the mixture,
4, 2 '-and 4, 4' -diphenyl
Methane diisocyanate mixture: 80 to 90 percent of the total weight of the mixture,
the weight ratio of the usage of the acetate solvent to the usage of the reactant is 1.2: 1,
the amount of the antioxidant is 0-5% of the amount of the reactant. The chemical reaction formula is as follows:
when two of the three hydroxyl groups in trimethylolpropane react with 4, 2 '-diphenylmethane diisocyanate and the other hydroxyl group reacts with 4, 4' -diphenylmethane diisocyanate to obtain a product of one structure, and when two of the three hydroxyl groups react with 4, 4 '-diphenylmethane diisocyanate and the other hydroxyl group reacts with 4, 2' -diphenylmethane diisocyanate to obtain a product of another structure, the product in the above chemical reaction formula is thus a mixture of the products of the two structures.
In the above-mentioned preparation steps, the purpose of reflux dehydration is to subject the reaction system to anhydrous or very little moisture to prevent the formation of hydrolysis of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate (MDI) monomer and derivatives thereof, since the hydrolysis product of MDI monomer is insoluble in the solvent and is insoluble in the solvent even when heated, and once formed, is difficult to remove.
In the preparation steps, the antioxidant is added into the reactants to ensure that the color of the product prepolymer is close to colorless, and the action mechanism is as follows:
by this reaction, the oxygen is prevented from deoxidizing urethane bonds and the active-NH generated during the hydrolysis of isocyanates2if-NH is formed2Is not instant by [ O]]Oxidized then-NH2Is reacted by isocyanate to form urea, which is a chemical bond with good stability, is not easy to be oxidized and is a colorless chemical bond, so that color and luster cannot be generated.
The composition of the 4, 2 '-and 4, 4' -diphenylmethane diisocyanate mixture of the invention is (by weight percent):
4, 2' -diphenylmethane diisocyanate: 40 to 60 percent of the total weight of the mixture,
4, 4' -diphenylmethane diisocyanate: 60 to 40 percent.
The acetate solvent in the invention is prepared by mixing one or more of ethyl acetate, butyl acetate and ethylene glycol ethyl ether acetate in any proportion.
Compared with the prior art, the invention has the following advantages: first, the toxicity is low. As the curing agent is prepared by using the mixture of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate (MDI) as a raw material, the vapor pressure of MDI is far lower than that of TDI at normal temperature, so that the prepolymer of the invention has lower toxicity. And secondly, the problem that MDI is solid at normal temperature and can be used by being liquefied when being used as a coating is solved. Compared with TDI type polyurethane curing agent, the MDI type coating curing agent has great improvement in color, toughness, elasticity and wear resistance after being formed into paint.
The product of the invention is mainly used as a polyurethane coating curing agent, has the characteristics of good stability, low gas phase toxicity and the like, has short curing time after paint forming, bright and full paint film, and has excellent adhesive force and chemical corrosion resistance.
The performance of the 4 '2-and 4, 4' -diphenylmethane diisocyanate (MDI) prepolymers of the present invention was compared with that of Toluene Diisocyanate (TDI) prepolymer as follows:
in order to better carry out the invention, the invention will now be further illustrated by reference to the following examples. The operation steps of the embodiment are as follows: adding trimethylolpropane, an acetate solvent and an antioxidant into a reaction kettle, stirring, performing reflux dehydration at 130-150 ℃, cooling a reaction liquid to 40 ℃ after dehydration is finished, adding a melted mixture of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate, stirring and preserving heat for reaction for 1 hour at 40 ℃, then heating to 80-90 ℃, stirring and preserving heat for reaction for 1 hour, cooling to 60 ℃, and discharging. Example 1 trimethylolpropane 10 g MDI-4590 g butyl acetate 100 g ethylene glycol ethyl ether acetate 20 g antioxidant Tinuvin-L6222 g MDI-45 is a mixture of 45% by weight of 4, 2 '-diphenylmethane diisocyanate and 55% by weight of 4, 4' -diphenylmethane diisocyanate. EXAMPLE 2 trimethylolpropane 15 g MDI-5085 g butyl acetate 100 gEthylene glycol monoethyl ether acetate 20 g antioxidant Tinuvin-L6220 g MDI-50 is a mixture of 50 wt% 4, 2 '-diphenylmethane diisocyanate and 50 wt% 4, 4' -diphenylmethane diisocyanate. EXAMPLE 3 trimethylolpropane 20 g MDI-6080 g butyl acetate100 g ethylene glycol monoethyl ether acetate 20 g antioxidant (PhO)3P5 g of MDI-60 is a mixture of 60% by weight of 4, 2 '-diphenylmethane diisocyanate and 40% by weight of 4, 4' -diphenylmethane diisocyanate. Application example 1
The properties of the paint film obtained from 50 g of the product of example 1 and 50 g of the hydroxyl-containing acrylic resin were as follows: drying at 25 ℃, surface drying time is 20min, and actual drying time is as follows: performance was tested after 7 days for 24 h:
impact, cm 50;
bending, mm 1.0;
adhesion, grade 1-2;
hardness, H3.
Application example 2
The properties of a coating film prepared by mixing 50 g of the product of example 2 with a hydroxyl-containing acrylic resin were as follows: drying at 25 ℃, surface drying time is 30min, and actual drying time is as follows: performance was tested after 7 days for 24 h:
impact, cm 50;
bending, mm 1.0;
adhesion, grade 1-2;
hardness, H3.
Claims (5)
1. A coating curing agent 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer characterized by: the schematic unit structural formula is as follows:
the product index of the prepolymer is as follows, the following contents are weight percentage,
(1) appearance: a colorless liquid;
(2) solid content: 45% +/-3%;
(3) NCO content: 10-15% by total solids;
(4) storage stability: for 1year.
2. A preparation method of a prepolymer of 4, 2 '-and 4, 4' -diphenylmethane diisocyanate of a coating curing agent is characterized by comprising the following steps: adding trimethylolpropane, an acetate solvent and an antioxidant into a reaction kettle, stirring, refluxing and dehydrating at 130-150 ℃, cooling a reaction liquid to 40 ℃ after dehydration is finished, adding a melted mixture of 4, 2 '-diphenylmethane diisocyanate and 4, 4' -diphenylmethane diisocyanate, stirring and preserving heat at 40 ℃ for reaction for 1 hour, then heating to 80-90 ℃, stirring and preserving heat for reaction for 1 hour, cooling to 60 ℃, and discharging to obtain a 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer, wherein the dosage of each reactant is calculated by weight percent as follows:
trimethylolpropane: 10 to 20 percent of the total weight of the composition,
4, 2 '-and 4, 4' -diphenyl
Methane diisocyanate mixture: 80 to 90 percent of the total weight of the steel,
the weight ratio of the usage of the acetate solvent to the usage of the reactant is 1.2: 1,
the dosage of the antioxidant is 0-5% of the dosage of the reactant.
3. The method for preparing 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer according to claim 2, wherein the composition of the mixture of 4, 2 '-and 4, 4' -diphenylmethane diisocyanates comprises, in weight percent:
4, 2' -diphenylmethane diisocyanate: 40% -60%;
4, 4' -diphenylmethane diisocyanate: 60 to 40 percent.
4. The method for preparing 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer according to claim 2, characterized in that: the antioxidant is triphenyl phosphite (PhO)3P。
5. The method for preparing 4, 2 '-and 4, 4' -diphenylmethane diisocyanate prepolymer according to claim 2, characterized in that: the acetate solvent is one or more of ethyl acetate, butyl acetate and ethylene glycol ethyl ether acetate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00127692 CN1116328C (en) | 2000-12-05 | 2000-12-05 | Paint curing agent 4,2'-and 4,4'-diphenyl methane diisocyanate prepolymer and its prepn |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00127692 CN1116328C (en) | 2000-12-05 | 2000-12-05 | Paint curing agent 4,2'-and 4,4'-diphenyl methane diisocyanate prepolymer and its prepn |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1357559A CN1357559A (en) | 2002-07-10 |
| CN1116328C true CN1116328C (en) | 2003-07-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 00127692 Expired - Fee Related CN1116328C (en) | 2000-12-05 | 2000-12-05 | Paint curing agent 4,2'-and 4,4'-diphenyl methane diisocyanate prepolymer and its prepn |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100340598C (en) * | 2006-04-27 | 2007-10-03 | 中国科学院广州化学研究所 | Water dispersible end capping diisocyanate cross-linking agent and its preparation method |
| CN100351297C (en) * | 2004-01-10 | 2007-11-28 | 广州秀珀化工有限公司 | Low free tolylene diisocynate polyurethane solidifying agent and its preparation method |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101230124B (en) * | 2007-01-27 | 2011-05-25 | 周建明 | Curing agent 4,4'-biphenyl methane diisocyanate prepolymer and preparation method thereof |
| CN101274977B (en) * | 2007-03-29 | 2011-05-25 | 周建明 | Curing agent 1,6- hexamethylene diisocyanate prepolymer and preparation thereof |
| CN101407571B (en) * | 2007-10-11 | 2010-12-08 | 周建明 | Curing agent toluene diisocyanate and 4,4'-methyl diphenylene diisocyanate mixing prepolymer and preparation thereof |
| CN101440149B (en) * | 2007-11-20 | 2010-06-30 | 周建明 | A curing agent 4,2'-and 4,4'-diphenylmethane diisocyanate prepolymer and a preparation method thereof |
| CN101402716B (en) * | 2008-05-31 | 2012-01-11 | 周建明 | Mixed prepolymer of solidifying agent methyl diphenylene diisocyanate and 1,6-hexamethylene diisocyanate and its preparation method |
| CN102352018B (en) * | 2011-08-30 | 2013-05-15 | 吴江市北厍盛源纺织品助剂厂 | Method for preparing diphenylmethane diisocyanate-trimethylolpropane (MDI-TMP) bridging agent |
| CN103145947A (en) * | 2013-02-25 | 2013-06-12 | 晋江市华福化工有限公司 | Novel environmental-friendly curing agent and preparation method for same |
-
2000
- 2000-12-05 CN CN 00127692 patent/CN1116328C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100351297C (en) * | 2004-01-10 | 2007-11-28 | 广州秀珀化工有限公司 | Low free tolylene diisocynate polyurethane solidifying agent and its preparation method |
| CN100340598C (en) * | 2006-04-27 | 2007-10-03 | 中国科学院广州化学研究所 | Water dispersible end capping diisocyanate cross-linking agent and its preparation method |
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| Publication number | Publication date |
|---|---|
| CN1357559A (en) | 2002-07-10 |
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