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Polyurethane coating crosslinking agent synthesis
2017-8-14 18:21:53
Polyurethane coating crosslinking agent synthesis
This paper describes the synthesis process of polyurethane crosslinking agent. The effects of TDI and TMP on the prepolymer performance were discussed.
Polyurethane crosslinking agent synthesis test show that the quality of TDI and TMP than in 5:1, the reaction temperature at 50 ℃, the reaction time of 5 h of the synthetic conditions, get the prepolymer of small molecular weight, low viscosity, flow needed low temperature, suitable for the separation of free TDI in the thin film evaporator, after the separation of polyurethane crosslinking agent colour and lustre is light, free TDI content and - NCO content in accordance with the design requirements.
In two-component polyurethane coatings, polyurethane crosslinking agent is one of the important components of polyurethane crosslinking agent was actually polyurethane prepolymer, which is composed of trimethylolpropane (TMP) and toluene diisocyanate (TDI) generated by addition reaction, - NCO group in prepolymer with polyester, polyether, etc.
The hydroxyl reaction on the resin is cross-linked. As a commonly used paint crosslinking agent, it can give a variety of excellent properties. Polyurethane coating has good appearance, high hardness, good corrosion resistance, good chemical resistance, etc. However, the residual free TDI in polyurethane crosslinking agent is very harmful to human body, so it is an important research topic to reduce the free TDI in polyurethane cross-linking agent.
In fact, there are two factors that influence tdi-tmp additive product quality, namely the early chemical reaction process and the separation process of free TDI. This work aims to the synthetic process of TDI - TMP adduct were discussed, synthetic quality crosslinking agent, and this work is carried out in a thin film evaporator post-processing, on the basis of the synthesis of crosslinking agent is suitable for the separation of free TDI in the thin film evaporator, finally got the good performance of polyurethane crosslinking agent.
Experimental raw materials. Toluene diisocyanate (TDI - 80/20) : industrial grade; Trimethyl-propane (TMP) : industrial grade; Butyl acetate: industrial grade.
Synthetic process. To set the specified temperature, the temperature of waterbath will weigh good TDI and butyl acetate to join to the four bottles, began to stir, to heat preservation in more than 60 ℃ after dehydration of TMP drops to the TDI, around 1 h add finished, then 4 h reaction, reaction process control reaction temperature at 50 ℃. Test viscosity, solid content, TDI content and - NCO content.
Chinese name: Diethyl toluene diamine(DETDA)
Chinese alias: aryl, aryl diethyl - aryl - methyl-p-phenylenediamine
English name: Benzenediamine, ar, ar-diethyl-ar-methyl-English aliases:Diethyltoluenediamine; ar, ar-Diethyl-ar-methylbenzenediamine;Diethylmethylbenzenediamine;
CAS No. :68479-98-1
EINECS No. :270 -877-4
Molecular formula: C11H18N2
Molecular Weight: 178.28
Boiling point: 310 ℃
Refractive index: 1.581
Flash Point: > 140 ℃
Inchi: InChI = 1/C11H18N2/c1-4-8-6-7 (3) 10 (12) 11 (13) 9 (8) 5-2/h6H ,4-5,12-13H2 ,1-3H3 density : 1.022
Risk Codes: R10; R35
RIDADR: UN 3082
Safety instructions: S2; S26; S39; S61
Packing Group: III
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
This paper describes the synthesis process of polyurethane crosslinking agent. The effects of TDI and TMP on the prepolymer performance were discussed.
Polyurethane crosslinking agent synthesis test show that the quality of TDI and TMP than in 5:1, the reaction temperature at 50 ℃, the reaction time of 5 h of the synthetic conditions, get the prepolymer of small molecular weight, low viscosity, flow needed low temperature, suitable for the separation of free TDI in the thin film evaporator, after the separation of polyurethane crosslinking agent colour and lustre is light, free TDI content and - NCO content in accordance with the design requirements.
In two-component polyurethane coatings, polyurethane crosslinking agent is one of the important components of polyurethane crosslinking agent was actually polyurethane prepolymer, which is composed of trimethylolpropane (TMP) and toluene diisocyanate (TDI) generated by addition reaction, - NCO group in prepolymer with polyester, polyether, etc.
The hydroxyl reaction on the resin is cross-linked. As a commonly used paint crosslinking agent, it can give a variety of excellent properties. Polyurethane coating has good appearance, high hardness, good corrosion resistance, good chemical resistance, etc. However, the residual free TDI in polyurethane crosslinking agent is very harmful to human body, so it is an important research topic to reduce the free TDI in polyurethane cross-linking agent.
In fact, there are two factors that influence tdi-tmp additive product quality, namely the early chemical reaction process and the separation process of free TDI. This work aims to the synthetic process of TDI - TMP adduct were discussed, synthetic quality crosslinking agent, and this work is carried out in a thin film evaporator post-processing, on the basis of the synthesis of crosslinking agent is suitable for the separation of free TDI in the thin film evaporator, finally got the good performance of polyurethane crosslinking agent.
Experimental raw materials. Toluene diisocyanate (TDI - 80/20) : industrial grade; Trimethyl-propane (TMP) : industrial grade; Butyl acetate: industrial grade.
Synthetic process. To set the specified temperature, the temperature of waterbath will weigh good TDI and butyl acetate to join to the four bottles, began to stir, to heat preservation in more than 60 ℃ after dehydration of TMP drops to the TDI, around 1 h add finished, then 4 h reaction, reaction process control reaction temperature at 50 ℃. Test viscosity, solid content, TDI content and - NCO content.
Chinese name: Diethyl toluene diamine(DETDA)
Chinese alias: aryl, aryl diethyl - aryl - methyl-p-phenylenediamine
English name: Benzenediamine, ar, ar-diethyl-ar-methyl-English aliases:Diethyltoluenediamine; ar, ar-Diethyl-ar-methylbenzenediamine;Diethylmethylbenzenediamine;
CAS No. :68479-98-1
EINECS No. :270 -877-4
Molecular formula: C11H18N2
Molecular Weight: 178.28
Boiling point: 310 ℃
Refractive index: 1.581
Flash Point: > 140 ℃
Inchi: InChI = 1/C11H18N2/c1-4-8-6-7 (3) 10 (12) 11 (13) 9 (8) 5-2/h6H ,4-5,12-13H2 ,1-3H3 density : 1.022
Risk Codes: R10; R35
RIDADR: UN 3082
Safety instructions: S2; S26; S39; S61
Packing Group: III
Hazard Class: 6.1
Test methods. The content of NCO was titration with dibutylamine hydrochloric acid. Determination of free TDI content by gas chromatography; The solid content was determined by GB/t1725-1979 (1989). The viscosity of crosslinking agent was determined by GB/T1723-1993 "paint viscosity measurement".
The influence of water in raw materials. TMP is white solid at room temperature, contact with air, easy to absorb water. Water molecules react with NCO groups to form polymers. Consume the same amount of isocyanate, one portion of water is equal to five TMP. Therefore, once the TMP contains water, it will seriously affect the quality of the product. The undehydrated TMP direct and TDI reaction were compared with the product of the dehydrated TMP and TDI reactions.
Water has a great influence on the viscosity of synthetic prepolymer, which is not conducive to the separation of free TDI in molecular distillation equipment. In addition, water also consumes the NCO group, reducing the NCO mass fraction. Therefore, it is necessary for TMP and solvent to dehydrate before feeding, which is an important link to ensure the excellent performance of products.
The effects of monomer ratio on the synthesis of polyurethane crosslinking agent. Polyurethane crosslinking agent synthesis process in China, usually does not consider the crosslinking agent in the post-processing of free TDI separation process, in order to minimize the crosslinking agent, the content of toxic free TDI in TDI and TMP control mostly in not on the premise of minimum ratio, gel that molar ratio of TDI and TMP in theory than the ratio of 3:1, mass ratio of 3.89:1 small change to design the formula.
This study has a thin film evaporator post-treatment technology of separating free TDI as backing, synthesis process and separation process, the combination of traditional thinking, so synthetic technology breakthrough of TDI with TMP ratio of bold attempt.
Test methods. The content of NCO was titration with dibutylamine hydrochloric acid. Determination of free TDI content by gas chromatography; The solid content was determined by GB/t1725-1979 (1989). The viscosity of crosslinking agent was determined by GB/T1723-1993 "paint viscosity measurement".
The influence of water in raw materials. TMP is white solid at room temperature, contact with air, easy to absorb water. Water molecules react with NCO groups to form polymers. Consume the same amount of isocyanate, one portion of water is equal to five TMP. Therefore, once the TMP contains water, it will seriously affect the quality of the product. The undehydrated TMP direct and TDI reaction were compared with the product of the dehydrated TMP and TDI reactions.
Water has a great influence on the viscosity of synthetic prepolymer, which is not conducive to the separation of free TDI in molecular distillation equipment. In addition, water also consumes the NCO group, reducing the NCO mass fraction. Therefore, it is necessary for TMP and solvent to dehydrate before feeding, which is an important link to ensure the excellent performance of products.
The effects of monomer ratio on the synthesis of polyurethane crosslinking agent. Polyurethane crosslinking agent synthesis process in China, usually does not consider the crosslinking agent in the post-processing of free TDI separation process, in order to minimize the crosslinking agent, the content of toxic free TDI in TDI and TMP control mostly in not on the premise of minimum ratio, gel that molar ratio of TDI and TMP in theory than the ratio of 3:1, mass ratio of 3.89:1 small change to design the formula.
This study has a thin film evaporator post-treatment technology of separating free TDI as backing, synthesis process and separation process, the combination of traditional thinking, so synthetic technology breakthrough of TDI with TMP ratio of bold attempt.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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