Water content control method of active hydrogen component rubber compound for polyurethane coating layer

Abstract

The invention provides a method for controlling the water content of an active hydrogen component rubber compound for a polyurethane coating layer. The method comprises the following steps: weighing the active hydrogen component rubber compound without a diethanol amine network regulator, and carrying out vacuum kneading dehydration until the water content is below 400ppm; 3-hydroxyethyl-1, 3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1, 3-oxazolidine is added into the active hydrogen component rubber compound, vacuum kneading is carried out, and the water content of the active hydrogen component rubber compound is measured to be 200 ppm or below; according to the calculated addition amount of 3-hydroxyethyl-1, 3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1, 3-oxazolidine, according to the formula proportion of the active hydrogen component rubber compound for the original polyurethane coating layer, the correction amount of the diethanolamine network regulator is calculated, the diethanolamine network regulator is added, vacuum kneading is performed, and then discharging is performed. According to the method disclosed by the invention, the moisture in the high-viscosity active hydrogen component rubber compound can be quickly removed to be below 200ppm, and the composition of the active hydrogen component rubber compound formula is not changed.

Description

Technical Field

[0001] This invention belongs to the field of water content control technology, and relates to active hydrogen component compound rubber, specifically to a method for controlling the water content of active hydrogen component compound rubber for polyurethane coating layers. Background Technology

[0002] Polyurethane coatings offer advantages such as good propellant compatibility, high bonding strength, moderate viscosity, excellent low-temperature mechanical properties, and easy processing, making them widely used in the coating of various modified double-base propellant charges. The polyurethane coating compound consists of an isocyanate component (component A) and an active hydrogen component (component B). The isocyanate component is a prepolymer with terminal isocyanate groups, produced by the polymerization reaction of hydroxyl-terminated polyether polyols and diisocyanates. The active hydrogen component is composed of hydroxyl-terminated polyether polyols, diethanolamine network modifiers, and various solid fillers (including reinforcing fillers, ablation-resistant fillers, and smoke-suppressing fillers) in a specific ratio, premixed by mechanical stirring, and finely mixed using a three-roll mill. During the coating process, the isocyanate component and the active hydrogen component are mixed uniformly in a specific ratio, and the polyurethane coating is formed through casting, injection, and curing.

[0003] Although the curing of polyurethane coatings is primarily based on the chemical reaction between isocyanate groups and active hydrogen groups such as hydroxyl and amino groups, the influence of ambient humidity during the compounding process, as well as moisture introduced from raw materials such as hydroxyl-terminated polyether polyols, alkanolamine network modifiers, and solid fillers, causes the isocyanate groups to react with water simultaneously with the hydroxyl and amino groups, producing carbon dioxide gas. This results in structural defects such as bubbles, pinholes, and microbubbles easily forming inside and on the surface of the polyurethane coating, severely impacting the first-pass yield and work efficiency. Existing engineering practice has shown that only by controlling the water content in the polyurethane coating formulation below 200 ppm can a yield of over 90% be guaranteed.

[0004] Currently, common methods for controlling water content include: First, vacuum treatment or high-temperature treatment. This method is uneconomical, has low dehydration efficiency, and can only reduce the water content to 400-600 ppm. Furthermore, the water content of the active hydrogen component compound fluctuates significantly. Second, the use of molecular sieves, whose mechanism of action is physical adsorption, is not suitable for high-viscosity materials. Third, the use of monofunctional isocyanates. This method is expensive, toxic, and alters the polyurethane coating formulation, affecting its overall performance. Fourth, the use of oxazolidine chemical dehydrators. These react rapidly with water without producing carbon dioxide gas and can prevent the effects of moisture during construction. However, the substituted alkanolamine compounds produced by the reaction of commercially available oxazolidine dehydrators with water alter the formulation of the active hydrogen component compound used in polyurethane coatings, which is strictly prohibited for mass-produced, standardized explosive products. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for controlling the water content of active hydrogen component compound for polyurethane coating layers. This method solves the technical problem that existing water content control methods are difficult to apply to high-viscosity materials while maintaining the formulation composition of the active hydrogen component compound during water removal.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for controlling the water content of an active hydrogen component compound for polyurethane coating layers, the method comprising the following steps:

[0008] Step 1: Weigh the active hydrogen component compound without diethanolamine network modifier and place it in a vertical vacuum kneader. After heating, start the stirring shaft and vacuum system, and perform pretreatment by vacuum kneading and dehydration, controlling the speed of the kneading paddle.

[0009] Step 2: During the vacuum kneading and dehydration process in Step 1, take a sample to determine the water content of the active hydrogen component compound. If the water content of the active hydrogen component compound is ≤400ppm, stop the vacuum kneading; if the water content of the active hydrogen component compound is ≥400ppm, continue the vacuum kneading until the water content of the active hydrogen component compound is ≤400ppm.

[0010] Step 3: When the water content of the active hydrogen component compound in Step 2 is ≤400ppm, add the dehydrating agent 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine to the active hydrogen component compound, and perform vacuum kneading again.

[0011] Step four: After the vacuum kneading in step three is completed, take a sample and measure the water content of the obtained active hydrogen component compound. If the water content of the active hydrogen component compound drops below 200 ppm, stop the vacuum kneading.

[0012] Step 5: Based on the amount of 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine added in Step 3, and according to the formulation ratio of the active hydrogen component compound without diethanolamine network modifier in Step 1, calculate the correction amount of diethanolamine network modifier.

[0013] Step six: Add the corrected amount of diethanolamine network modifier from step five to the active hydrogen component compound that has had its water content reduced to below 200 ppm in step four, and then discharge the material after vacuum kneading.

[0014] The present invention also has the following technical features:

[0015] Preferably, in step one, the temperature rise refers to the temperature being raised to 80°C.

[0016] In step one, the kneading paddle rotates at a speed of 60–80 r / min.

[0017] Specifically, in step two, the method used to determine the water content of the active hydrogen component compound includes the following steps:

[0018] Step 201: Weigh the active hydrogen component compound with mass m1 and solid content y and the compound diluent with mass m2, respectively.

[0019] Step 202: Mix the active hydrogen component compound and compound diluent weighed in step 201 evenly in a sealed container, and let it stand and precipitate for 6-12 hours.

[0020] Step 203: After the precipitation treatment in step 202 is completed, that is, after the solid components have completely precipitated and the upper liquid has become clear and transparent, take the transparent upper liquid and determine the water content of the transparent upper liquid as x using the Karl Fischer coulomb method.

[0021] Step 204: The water content of the rubber compound diluent in step 201 is determined to be x2 using the Karl Fischer coulomb method.

[0022] Step 205: Calculate the water content x1 of the active hydrogen component compound in step 201 using the following formula.

[0023] Let the water content of the active hydrogen component compound in step 201 be x1. Then the relationship between m1, y, m2, x1, x2 and x is:

[0024]

[0025] In the formula:

[0026] m1 is the mass of the active hydrogen component compound rubber, in grams;

[0027] x1 represents the water content of the active hydrogen component compound, in ppm;

[0028] m2 represents the mass of the rubber compound thinner, in grams.

[0029] x2 represents the water content of the rubber compound diluent, in ppm;

[0030] y represents the solid content of the active hydrogen component compound, in %;

[0031] x represents the water content of the transparent upper layer of liquid, expressed in ppm.

[0032] The water content of the active hydrogen component compound in step 201 is:

[0033]

[0034] x1 represents the water content of the active hydrogen component compound, in ppm;

[0035] m1 is the mass of the active hydrogen component compound rubber, in grams;

[0036] y represents the solid content of the active hydrogen component compound, in %;

[0037] m2 represents the mass of the rubber compound thinner, in grams.

[0038] x represents the water content of the transparent upper layer of liquid, expressed in ppm.

[0039] x2 represents the water content of the rubber compound diluent, in ppm.

[0040] Specifically, in step three, when the dehydrating agent is 3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows:

[0041] Let the mass of the active hydrogen component compound be m; let the measured water content of the active hydrogen component compound be x1; then the mass of water in the active hydrogen component compound is mx1 / 1000000; the mass of 3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume mx1 / 1000000 of the water is M1mx1 / (1000000×18), where M1 is the relative molecular mass of 3-hydroxyethyl-1,3-oxazolidine, and the units of mass are all g, and the unit of water content is ppm.

[0042] Specifically, in step five, when 3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows:

[0043] In the formulation of the active hydrogen component compound without diethanolamine network modifier in step one, the mass of diethanolamine to be added is... The unit is g; the mass of diethanolamine produced by the hydrolysis of 3-hydroxyethyl-1,3-oxazolidine in step three is M3mx1 / (1000000×18), in g, where M3 is the relative molecular mass of diethanolamine; therefore, the correction amount for the diethanolamine network modifier is... The unit is g.

[0044] Specifically, in step three, when the dehydrating agent is 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows:

[0045] Let the mass of the active hydrogen component compound be m, and the water content of the active hydrogen component compound be x1; then the mass of water in the active hydrogen component compound is mx1 / 1000000; the mass of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume the water mass mx1 / 1000000 is M2mx1 / (1000000×18), where M2 is the relative molecular mass of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, and the units of mass are all g, and the units of water content are ppm.

[0046] Specifically, in step five, when 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows:

[0047] Let the mass of diethanolamine to be added in the active hydrogen component compound without diethanolamine network modifier in step one be M (in g); and the mass of diethanolamine produced by the hydrolysis of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine in step three be M3mx1 / (1000000×18) (in g), where M3 is the relative molecular mass of diethanolamine; then the correction amount of diethanolamine network modifier is M-M3mx / (1000000×18) (in g).

[0048] Specifically, in step three, the kneading temperature during vacuum kneading is 40–50°C, and the kneading time during vacuum kneading is 10 minutes.

[0049] Specifically, in step six, the kneading temperature during vacuum kneading is 40–50°C, and the kneading time during vacuum kneading is 30 minutes.

[0050] Compared with the prior art, the present invention has the following technical effects:

[0051] (I) The method of this invention uses 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent, and the hydrolysis products of both are diethanolamine and formaldehyde or isopropylformaldehyde. Diethanolamine is a network regulator in the active hydrogen component compounded collagen formulation, while formaldehyde or isopropylformaldehyde, as low-boiling-point substances, can be removed by vacuum kneading, thus maintaining the original composition of the active hydrogen component compounded rubber formulation. This method can achieve precise control of the water content of high-viscosity active hydrogen component compounded rubber without changing the composition of the active hydrogen component compounded collagen formulation.

[0052] (II) The method of the present invention involves vacuum kneading and dehydration of the active hydrogen component compound without the addition of diethanolamine network regulator, controlling the water content of the active hydrogen component compound to below 400 ppm, and then adding 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine dehydrating agent to the active hydrogen component compound. Water can be rapidly removed through the hydrolysis reaction of 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, controlling the water content of the active hydrogen component compound to below 200 ppm.

[0053] The specific content of the present invention will be further described in detail below with reference to the embodiments. Detailed Implementation

[0054] It should be noted that, unless otherwise specified, all equipment, systems, methods, and materials in this invention are based on existing technologies. For example, the vertical vacuum kneader is a known vertical vacuum kneader, the vacuum system is a known vacuum system, the kneading paddle is a known kneading paddle, the Karl Fischer coulomb process is a known Karl Fischer coulomb process, the active hydrogen component compound for polyurethane coating is a known active hydrogen component compound for polyurethane coating, 3-hydroxyethyl-1,3-oxazolidine is a known 3-hydroxyethyl-1,3-oxazolidine, 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine is a known 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, and diethanolamine is a known diethanolamine.

[0055] The technical concept of this invention is as follows: To rapidly remove moisture from the active hydrogen component compound without altering the polyurethane coating formulation, oxazolidine, whose hydrolysis product is identical to a component in the active hydrogen component compound collagen formulation, can be selected as a chemical dehydrating agent. Since oxazolidine is typically formed by the dehydration condensation of alkanolamines with aldehydes or ketones, its reversible hydrolysis reaction produces the corresponding alkanolamines, aldehydes, or ketones. This invention selects 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as the dehydrating agent, whose hydrolysis products are diethanolamine and formaldehyde or isopropylformaldehyde. Diethanolamine is a network regulator in the active hydrogen component compound collagen formulation, while formaldehyde or isopropylformaldehyde, as low-boiling-point substances, can be removed by vacuum kneading, maintaining the original active hydrogen component compound collagen formulation composition unchanged. The synthesis and hydrolysis mechanism of 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine are shown below:

[0056]

[0057] In this invention, the high viscosity of the high-viscosity active hydrogen component compound refers to a paste that exhibits no flowability at room temperature; room temperature refers to the ambient temperature during the production process, which is typically within the range of 20±10℃.

[0058] In this invention, the active hydrogen component compound refers to the active hydrogen component compound for polyurethane coating layers.

[0059] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0060] Example 1: (using 3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent)

[0061] This embodiment provides a method for controlling the water content of active hydrogen component compound for polyurethane coating layers, the method comprising the following steps:

[0062] Step 1: Weigh three different types of active hydrogen component rubber compounds (D01-ethyl compound, XJ-ethyl compound, and 105G-ethyl compound) without diethanolamine network modifier, and place them separately in a vertical vacuum kneader. The solid content of the active hydrogen component rubber compounds in each compound is 25%. Then, slowly heat the vertical vacuum kneader to 80°C and start the stirring shaft and vacuum system. Pre-treatment is carried out by vacuum kneading and dehydration. The kneading paddle speed is controlled at 80 r / min, and vacuum kneading is carried out at a kneading temperature of 80°C for 6-8 hours.

[0063] Step 2: During the vacuum kneading and dehydration process in Step 1, take a sample to determine the water content of the active hydrogen component compound. If the water content of the active hydrogen component compound is ≤400ppm, stop the vacuum kneading; if the water content of the active hydrogen component compound is ≥400ppm, continue the vacuum kneading until the water content of the active hydrogen component compound is ≤400ppm.

[0064] In step two, the method used to determine the water content of the active hydrogen component compound specifically includes the following steps:

[0065] Step 201: Accurately weigh the active hydrogen component compound with mass m1 and solid content y, and the compound diluent with mass m2.

[0066] Step 202: Mix the active hydrogen component compound and compound diluent weighed in step 201 evenly in a tightly sealed container, and let it stand and precipitate for 9 hours.

[0067] Step 203: After the precipitation treatment in step 202 is completed, that is, after the solid components have completely precipitated and the upper liquid has become clear and transparent, take the transparent upper liquid and determine the water content of the transparent upper liquid as x using the Karl Fischer coulomb method.

[0068] Step 204: The water content of the rubber compound diluent in step 201 is determined to be x2 using the Karl Fischer coulomb method.

[0069] Step 205: Calculate the water content x1 of the active hydrogen component compound in step 201 using the following formula.

[0070] Let the water content of the active hydrogen component compound in step 201 be x1. Then the relationship between m1, y, m2, x1, x2 and x is:

[0071]

[0072] In the formula:

[0073] m1 is the mass of the active hydrogen component compound rubber, in grams;

[0074] x1 represents the water content of the active hydrogen component compound, in ppm;

[0075] m2 represents the mass of the rubber compound thinner, in grams.

[0076] x2 represents the water content of the rubber compound diluent, in ppm;

[0077] y represents the solid content of the active hydrogen component compound, in %;

[0078] x represents the water content of the transparent upper layer of liquid, expressed in ppm.

[0079] The water content of the active hydrogen component compound in step 201 is:

[0080]

[0081] x1 represents the water content of the active hydrogen component compound, in ppm;

[0082] m1 is the mass of the active hydrogen component compound rubber, in grams;

[0083] y represents the solid content of the active hydrogen component compound, in %;

[0084] m2 represents the mass of the rubber compound thinner, in grams.

[0085] x represents the water content of the transparent upper layer of liquid, expressed in ppm.

[0086] x2 represents the water content of the rubber compound diluent, in ppm.

[0087] In this embodiment, anhydrous tetrahydrofuran is used as the diluent for the rubber compound.

[0088] Step 3: When the water content of the active hydrogen component compound in Step 2 is ≤400ppm, add the dehydrating agent 3-hydroxyethyl-1,3-oxazolidine to the active hydrogen component compound, and then perform vacuum kneading again for 10min at a kneading temperature of 45℃.

[0089] In step three, when the dehydrating agent is 3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows:

[0090] Let m be the mass (in g) of the active hydrogen component compound; let x1 be the measured water content (in ppm) of the active hydrogen component compound; then the mass (in g) of water in the active hydrogen component compound is mx1 / 1000000; the mass (in g) of 3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume mx1 / 1000000 of water is M1mx1 / (1000000×18), where M1 is the relative molecular mass of 3-hydroxyethyl-1,3-oxazolidine.

[0091] Step four: After the vacuum kneading in step three is completed for another 10 minutes, take a sample and measure the water content of the obtained active hydrogen component compound. If the water content of the active hydrogen component compound drops below 200 ppm, stop the vacuum kneading.

[0092] In this embodiment, the method used to determine the water content of the obtained active hydrogen component compound in step four is the same as the method used in step two.

[0093] Step 5: Based on the amount of 3-hydroxyethyl-1,3-oxazolidine added in Step 3, and according to the formulation ratio of the active hydrogen component compound without diethanolamine network modifier in Step 1, calculate the correction amount of diethanolamine network modifier.

[0094] In step five, when 3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows:

[0095] In the formulation of the active hydrogen component compound without diethanolamine network modifier in step one, the mass (in grams) of diethanolamine to be added is: The mass (in g) of diethanolamine produced by the hydrolysis of 3-hydroxyethyl-1,3-oxazolidine in step three is M3mx1 / (1000000×18), where M3 is the relative molecular mass of diethanolamine; therefore, the correction amount (in g) for the diethanolamine network modifier is:

[0096] Step 6: Add the modified amount of diethanolamine network modifier from Step 5 to the active hydrogen component compound that has had its water content reduced to below 200 ppm in Step 4. After vacuum kneading at a kneading temperature of 45°C for 30 minutes, discharge the material.

[0097] In this embodiment, the three different types of active hydrogen component compound rubbers without added diethanolamine network modifier are D01-ethyl compound rubber, XJ-ethyl compound rubber and 105G-ethyl compound rubber, which are known in the art.

[0098] In this embodiment, only the solid content of the active hydrogen component compound in step one is changed from 25% to 35% or 45%, and steps one through six are repeated.

[0099] In this embodiment, the active hydrogen component compound without diethanolamine network modifier in step one is the original formula.

[0100] In this embodiment, the active hydrogen component compound without the addition of diethanolamine network modifier is the sample, the solid content of the active hydrogen component compound without the addition of diethanolamine network modifier is the sample solid content, and the mass of the active hydrogen component compound without the addition of diethanolamine network modifier is the sample mass.

[0101] In this embodiment, the specific weighing, calculation and test results are shown in Tables 1 to 3.

[0102] Table 1. Water content control test using 3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent (solid content of all samples was 25%).

[0103]

[0104] Table 2. Water content control test using 3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent (solid content of all samples was 35%).

[0105]

[0106]

[0107] Table 3. Water content control test using 3-hydroxyethyl-1,3-oxazolidine as the dehydrating agent (solid content of all samples was 45%).

[0108]

[0109] The results in Tables 1 to 3 show that the water content control method in this embodiment, using 3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent, can accurately control the water content of active hydrogen component compounded rubber with different solid contents and high viscosity to below 200 ppm without changing the composition of the active hydrogen component compounded collagen formulation. The implementation effect is reliable and stable.

[0110] Example 2: (using 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent)

[0111] This embodiment provides a method for controlling the water content of active hydrogen component compound for polyurethane coating. The control method in this embodiment is basically the same as that in Embodiment 1, except that: in step three, the dehydrating agent is changed from 3-hydroxyethyl-1,3-oxazolidine to 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, and the amount of dehydrating agent added is different; in step five, the method is changed from based on the amount of 3-hydroxyethyl-1,3-oxazolidine added in step three to based on the amount of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine added in step three, and the correction amount of the calculated diethanolamine network modifier is different.

[0112] More preferably, in step three, when the dehydrating agent is 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows:

[0113] Let m be the mass (in g) of the active hydrogen component compound and x1 be the water content (in ppm) of the active hydrogen component compound. Then the mass (in g) of water in the active hydrogen component compound is mx1 / 1000000. The mass (in g) of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume mx1 / 1000000 of the water is M2mx1 / (1000000×18), where M2 is the relative molecular mass of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine.

[0114] More preferably, in step five, when 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows:

[0115] Let the mass (in grams) of diethanolamine to be added in the active hydrogen component compound without diethanolamine network modifier in step one be: The mass (in g) of diethanolamine produced by the hydrolysis of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine in step three is M3mx1 / (1000000×18), where M3 is the relative molecular mass of diethanolamine; therefore, the correction amount (in g) for the diethanolamine network modifier is:

[0116] In this embodiment, the three different types of active hydrogen component compound rubbers without added diethanolamine network modifier are D01-ethyl compound rubber, XJ-ethyl compound rubber and 105G-ethyl compound rubber, which are known in the art.

[0117] In this embodiment, only the solid content of the active hydrogen component compound in step one is changed from 25% to 35% or 45%, and steps one through six are repeated.

[0118] In this embodiment, anhydrous tetrahydrofuran is used as the diluent for the rubber compound.

[0119] In this embodiment, the active hydrogen component compound without diethanolamine network modifier in step one is the original formula.

[0120] In this embodiment, the active hydrogen component compound without the addition of diethanolamine network modifier is the sample, the solid content of the active hydrogen component compound without the addition of diethanolamine network modifier is the sample solid content, and the mass of the active hydrogen component compound without the addition of diethanolamine network modifier is the sample mass.

[0121] In this embodiment, the specific weighing, calculation, and test results are shown in Tables 4 to 6.

[0122] Table 4. Water content control test using 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent (solid content of all samples was 25%).

[0123]

[0124] Table 5. Water content control test using 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent (solid content of all samples was 35%).

[0125]

[0126]

[0127] Table 6. Water content control test using 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent (solid content of all samples was 45%).

[0128]

[0129] The results in Tables 4 to 6 show that the water content control method in this embodiment, using 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine as a dehydrating agent, can accurately control the water content of active hydrogen component compounded rubber with different solid contents and high viscosity to below 200 ppm without changing the composition of the active hydrogen component compounded collagen formulation. The implementation effect is reliable and stable.

Claims

1. A method for controlling the water content of an active hydrogen component compound for polyurethane coating layers, characterized in that, The method includes the following steps: Step 1: Weigh the active hydrogen component compound without diethanolamine network modifier and place it in a vertical vacuum kneader. After heating, start the stirring shaft and vacuum system to pre-treat the rubber by vacuum kneading and dehydration, and control the speed of the kneading paddle. Step 2: During the vacuum kneading and dehydration process in Step 1, take a sample to determine the water content of the active hydrogen component compound. If the water content of the active hydrogen component compound is ≤400ppm, stop the vacuum kneading; if the water content of the active hydrogen component compound is ≥400ppm, continue the vacuum kneading until the water content of the active hydrogen component compound is ≤400ppm. Step 3: When the water content of the active hydrogen component compound in Step 2 is ≤400ppm, add the dehydrating agent 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine to the active hydrogen component compound and perform vacuum kneading again. Step 4: After the vacuum kneading in Step 3 is completed, take a sample and measure the water content of the obtained active hydrogen component compound. If the water content of the active hydrogen component compound drops below 200 ppm, stop the vacuum kneading. Step 5: Based on the amount of 3-hydroxyethyl-1,3-oxazolidine or 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine added in Step 3, and according to the formulation ratio of the active hydrogen component compound without diethanolamine network modifier in Step 1, calculate the correction amount of diethanolamine network modifier. Step six: Add the corrected amount of diethanolamine network modifier from step five to the active hydrogen component compound that has had its water content reduced to below 200 ppm in step four, and then discharge the material after vacuum kneading.

2. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step one, the "after heating" refers to heating to 80°C; In step one, the kneading paddle rotates at a speed of 60–80 r / min.

3. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step two, the method used to determine the water content of the active hydrogen component compound specifically includes the following steps: Step 201: Weigh the active hydrogen component compound with mass m1 and solid content y and the compound diluent with mass m2 respectively. Step 202: Mix the active hydrogen component compound and compound diluent weighed in step 201 evenly in a sealed container, and let it stand and precipitate for 6 to 12 hours. Step 203: After the precipitation treatment in step 202 is completed, that is, after the solid components have completely precipitated and the upper liquid has become clear and transparent, take the transparent upper liquid and determine the water content of the transparent upper liquid as x using the Karl Fischer coulomb method. Step 204: The water content of the rubber compound diluent in step 201 is determined to be x2 using the Karl Fischer coulomb method. Step 205: Calculate the water content x1 of the active hydrogen component compound in step 201 using the following formula; Let the water content of the active hydrogen component compound in step 201 be x1. Then the relationship between m1, y, m2, x1, x2 and x is: In the formula: m1 is the mass of the active hydrogen component compound rubber, in grams; x1 represents the water content of the active hydrogen component compound, in ppm; m2 represents the mass of the rubber compound thinner, in grams. x2 represents the water content of the rubber compound diluent, in ppm; y represents the solid content of the active hydrogen component compound, in %; x represents the water content of the transparent upper layer of liquid, expressed in ppm. The water content of the active hydrogen component compound in step 201 is: x1 represents the water content of the active hydrogen component compound, in ppm; m1 is the mass of the active hydrogen component compound rubber, in grams; y represents the solid content of the active hydrogen component compound, in %; m2 represents the mass of the rubber compound thinner, in grams. x represents the water content of the transparent upper layer of liquid, expressed in ppm. x2 represents the water content of the rubber compound diluent, in ppm.

4. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step three, when the dehydrating agent is 3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows: Let the mass of the active hydrogen component compound be m; let the measured water content of the active hydrogen component compound be x1; then the mass of water in the active hydrogen component compound is mx1 / 1000000; the mass of 3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume mx1 / 1000000 of the water is M1mx1 / (1000000×18), where M1 is the relative molecular mass of 3-hydroxyethyl-1,3-oxazolidine, and the units of mass are all g, and the unit of water content is ppm.

5. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 4, characterized in that, In step five, when 3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows: In the formulation of the active hydrogen component compound without diethanolamine network modifier in step one, the mass of diethanolamine to be added is... The unit is g; the mass of diethanolamine produced by the hydrolysis of 3-hydroxyethyl-1,3-oxazolidine in step three is M3mx1 / (1000000×18), in g, where M3 is the relative molecular mass of diethanolamine; therefore, the correction amount for the diethanolamine network modifier is... The unit is g.

6. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step three, when the dehydrating agent is 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, the calculation method for the amount of dehydrating agent added is as follows: Let the mass of the active hydrogen component compound be m, and the water content of the active hydrogen component compound be x1; then the mass of water in the active hydrogen component compound is mx1 / 1000000; the mass of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine that needs to be added to consume the water mass mx1 / 1000000 is M2mx1 / (1000000×18), where M2 is the relative molecular mass of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine, and the units of mass are all g, and the units of water content are ppm.

7. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 6, characterized in that, In step five, when 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine is used, the calculation method for the correction amount of the corresponding diethanolamine network modifier is as follows: Let the mass of diethanolamine to be added in the active hydrogen component compound without diethanolamine network modifier in step one be [missing information]. The unit is g; the mass of diethanolamine produced by the hydrolysis of 2-isopropyl-3-hydroxyethyl-1,3-oxazolidine in step three is M3mx1 / (1000000×18), in g, where M3 is the relative molecular mass of diethanolamine; therefore, the correction amount for the diethanolamine network modifier is... The unit is g.

8. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step three, the kneading temperature during vacuum kneading is 40-50°C, and the kneading time during vacuum kneading is 10 minutes.

9. The method for controlling the water content of the active hydrogen component compound for polyurethane coating as described in claim 1, characterized in that, In step six, the kneading temperature during vacuum kneading is 40–50°C, and the kneading time during vacuum kneading is 30 minutes.

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