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Polyurethane coating agent for coating
2017-8-14 18:21:57
Polyurethane coating agent for coating
The effect of feeding method on the performance of the prepolymer. In the synthesis process of polyurethane crosslinking agent, there are many kinds of feeding ways, and different feeding ways have great influence on the products.
In this paper, 3 kinds of feeding methods are tested. The first one is a feeding, and the dehydrated TMP, TDI and butyl acetate are added to the reactor to react. The advantages of this method are simple process, saving equipment and shortening reaction time. However, during the process of feeding, the temperature in the reaction process is difficult to control. The product is not evenly distributed and the viscosity is large.
The second is to add the TMP of the solid to the TDI - acetate solution. Third is after dehydration of TMP temperature above 60 ℃ (to prevent precipitate TMP), under stirring the TMP solution drops to the TDI of butyl acetate solution (liquid reaction.
TDI was more than TMP, and 4 - NCO was more likely to react. And drip addition reaction process is easy to control, tend to be more idealistic, synthesis of uniform product molecular weight distribution, low viscosity, in the process of separating free TDI in the thin film evaporator operation stability. So choose the third type of adding material.
The influence of the solvent. The viscosity of different solvent systems is different in the same temperature and solid content. Early cyclohexanone is used as a solvent to complete the reaction, but the product has a deep color and is not suitable for use. In later studies, the effects of toluene and reaction temperature were used.
Temperature is an important factor in TDI - TMP. The higher the reaction temperature, the faster the reaction speed, the shorter the time needed to complete reaction, but the higher the reaction temperature, the more side effects, the greater the viscosity of product, all kinds of materials more easily oxidized, the deeper the color of the product, and the higher the reaction temperature, the activity of TDI molecules 2 - NCO group difference is smaller, so get a product of relative molecular mass distribution is uneven.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
The effect of feeding method on the performance of the prepolymer. In the synthesis process of polyurethane crosslinking agent, there are many kinds of feeding ways, and different feeding ways have great influence on the products.
In this paper, 3 kinds of feeding methods are tested. The first one is a feeding, and the dehydrated TMP, TDI and butyl acetate are added to the reactor to react. The advantages of this method are simple process, saving equipment and shortening reaction time. However, during the process of feeding, the temperature in the reaction process is difficult to control. The product is not evenly distributed and the viscosity is large.
The second is to add the TMP of the solid to the TDI - acetate solution. Third is after dehydration of TMP temperature above 60 ℃ (to prevent precipitate TMP), under stirring the TMP solution drops to the TDI of butyl acetate solution (liquid reaction.
TDI was more than TMP, and 4 - NCO was more likely to react. And drip addition reaction process is easy to control, tend to be more idealistic, synthesis of uniform product molecular weight distribution, low viscosity, in the process of separating free TDI in the thin film evaporator operation stability. So choose the third type of adding material.
The influence of the solvent. The viscosity of different solvent systems is different in the same temperature and solid content. Early cyclohexanone is used as a solvent to complete the reaction, but the product has a deep color and is not suitable for use. In later studies, the effects of toluene and reaction temperature were used.
Temperature is an important factor in TDI - TMP. The higher the reaction temperature, the faster the reaction speed, the shorter the time needed to complete reaction, but the higher the reaction temperature, the more side effects, the greater the viscosity of product, all kinds of materials more easily oxidized, the deeper the color of the product, and the higher the reaction temperature, the activity of TDI molecules 2 - NCO group difference is smaller, so get a product of relative molecular mass distribution is uneven.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.
On the other hand, the reaction is the exothermic reaction, the more energy the outside world gives, the more adverse the reaction control, the rapid increase of the reaction system and even the possibility of gelation. Therefore, the high temperature should be avoided in the synthesis reaction. Table 3 is the effect of temperature on product performance.
Temperature has great influence on the viscosity and color of the product, and the solid content, density and NCO value of the products have little influence. TMP easy exhalation when below 40 ℃, so the response should not be less than 40 ℃ low temperature. In this experiment, the traditional thinking of low temperature and high temperature reaction was broken, and the reaction time was increased with the reaction time at low temperature.
The results showed that the reaction can be not only, and tend to be ideal reaction, the reaction product of color shallow, relative molecular mass is small, low viscosity, flow needed low temperature, this product is suitable for the separation of free TDI in the thin film evaporator.
As a result, the synthetic reaction choice under the low temperature, longer reaction time to complete, control the reaction temperature 50 ℃, 1 h after add completely, then continue to 4 h reaction, the adduct directly on the film evaporator for the separation of free TDI, obtained excellent performance, non-toxic, crosslinking agent.
The mixture solvent of xylene and butyl acetate is better. In this study, single solvent butyl acetate is used because the single solvent has a single physical property, which is convenient for the separation of the aftertreatment and the recycle of solvent after separation.
A tdi-tmp prepolymer which is suitable for the separation of free TDI in thin film evaporator is synthesized with low molecular weight, low viscosity and low flow temperature. The research shows that the low temperature is favorable for the reaction to the ideal direction, and the product color is shallow. The more excess TDI is, the closer the reaction is to the ideal reaction. The TMP and solvent must be dehydrated, with a single butyl acetate solvent, which can be recycled after separation.
On the other hand, the reaction is the exothermic reaction, the more energy the outside world gives, the more adverse the reaction control, the rapid increase of the reaction system and even the possibility of gelation. Therefore, the high temperature should be avoided in the synthesis reaction. Table 3 is the effect of temperature on product performance.
Temperature has great influence on the viscosity and color of the product, and the solid content, density and NCO value of the products have little influence. TMP easy exhalation when below 40 ℃, so the response should not be less than 40 ℃ low temperature. In this experiment, the traditional thinking of low temperature and high temperature reaction was broken, and the reaction time was increased with the reaction time at low temperature.
The results showed that the reaction can be not only, and tend to be ideal reaction, the reaction product of color shallow, relative molecular mass is small, low viscosity, flow needed low temperature, this product is suitable for the separation of free TDI in the thin film evaporator.
As a result, the synthetic reaction choice under the low temperature, longer reaction time to complete, control the reaction temperature 50 ℃, 1 h after add completely, then continue to 4 h reaction, the adduct directly on the film evaporator for the separation of free TDI, obtained excellent performance, non-toxic, crosslinking agent.
The mixture solvent of xylene and butyl acetate is better. In this study, single solvent butyl acetate is used because the single solvent has a single physical property, which is convenient for the separation of the aftertreatment and the recycle of solvent after separation.
A tdi-tmp prepolymer which is suitable for the separation of free TDI in thin film evaporator is synthesized with low molecular weight, low viscosity and low flow temperature. The research shows that the low temperature is favorable for the reaction to the ideal direction, and the product color is shallow. The more excess TDI is, the closer the reaction is to the ideal reaction. The TMP and solvent must be dehydrated, with a single butyl acetate solvent, which can be recycled after separation.
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