Method for removing aldehyde and acid from PVB (Polyvinyl Butyral) resin by washing

Abstract

The invention discloses a washing formaldehyde and acid removal method for PVB (Polyvinyl Butyral) resin. The washing formaldehyde and acid removal method comprises the following steps: step 1, measuring the content of butyraldehyde; 2, adding ammonia water or an ammonium bicarbonate solution; and step 3, washing with water, heating, and draining to remove butyraldehyde and ammonium salt. By adopting the method for removing aldehyde and acid by washing, excessive ammonia water or ammonium bicarbonate solution is easy to separate, the washing frequency can be reduced, and water is saved; common caustic soda is replaced, and generation and residues of sodium salt are avoided; excessive ammonia water or ammonium bicarbonate solution can greatly reduce the residual amount of butyraldehyde, and the residual amount of butyraldehyde accounts for 0.001% or below of the weight of a finished product; a detergent special for cleaning organic matters is introduced, the detergent is composed of a surfactant, other impurities such as acid salts are greatly removed, residual ammonium chloride can also be decomposed into hydrogen chloride gas and ammonia gas in the subsequent drying stage to be completely volatilized, and the product quality is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of PVB resin technology, specifically relating to a water washing method for removing formaldehyde and acid during the production process of PVB resin. Background Technology

[0002] PVB resin, also known as polyvinyl butyral resin, possesses excellent physical properties such as transparency, cold resistance, impact resistance, and UV resistance. It also exhibits good adhesion to raw materials such as metals, glass, ceramics, and wood. PVB resin can be used as a laminating material in safety glass, producing safety glass with good transparency, high impact strength, and strong weather resistance, widely used in the automotive and construction industries. Furthermore, PVB resin can be applied to coatings, ceramics, textiles, food packaging, papermaking, and other waterproof materials, showing a broad market prospect.

[0003] The PVB resin production process mainly includes four steps: dissolution, condensation, washing, and drying. Among them, the washing step is a key process that affects product quality. Because PVA undergoes a condensation reaction with butyraldehyde under acidic conditions, unreacted butyraldehyde will remain. This residual butyraldehyde is very easy to adhere to PVB resin particles and is difficult to remove. If the product contains a lot of residual butyraldehyde, it will cause the product to have a butyraldehyde odor and will easily lead to the degradation or cross-linking of PVB resin, affecting product quality. Among existing methods for removing butyraldehyde, the invention patent with publication number CN107880158B introduces the azeotropic methanol, but methanol volatilization is harmful to the human body, which is not ideal. In addition, the acid (usually hydrochloric acid) that is the catalyst for the condensation reaction cannot be completely removed by water washing and requires the addition of alkali for neutralization. However, the resulting sodium salt and other impurities will remain in the PVB resin particles. For example, the resin neutralization treatment disclosed in the invention patent with publication number CN106543927B requires the addition of caustic soda to adjust the pH value to 8-10, which will leave a certain amount of sodium salt, which may ultimately affect the optical properties and aging resistance of the product after film formation. Summary of the Invention

[0004] In response to the problems raised in the background technology, this invention studies and designs a water washing method for removing formaldehyde and acid from PVB resin. The purpose is to provide a method for removing butyraldehyde and hydrochloric acid during the production process of PVB resin, aiming to more thoroughly remove butyraldehyde residue and hydrochloric acid and improve the quality of PVB resin.

[0005] The technical solution of this invention: A method for removing formaldehyde and acid from PVB resin by water washing includes the following steps: Step 1: Determination of butyraldehyde content In the PVB resin production process, after the condensation reaction is completed, the liquid in the reaction material is discharged, and then the butyraldehyde content in the remaining solid material is measured. Step 2: Add ammonia or ammonium bicarbonate solution Based on the butyraldehyde content measured in step 1, ammonia or ammonium bicarbonate solution is added to the solid material described in step 1 and stirred evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and ammonium salts. 3.1 Add pure water containing ammonia to the mixture described in step 2, stir evenly, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add pure water containing detergent to the remaining solid material, stir evenly, then heat up, control the temperature of the liquid at 50-60℃, and keep it at the temperature for 20 minutes, then drain the liquid containing the remaining ammonium salts again. 3.3 Continue washing with pure water twice more to complete the water washing process for removing formaldehyde and acid.

[0006] Taking into account the softening point of PVB resin (62-65℃) and to ensure the washing effect, preferably, the weight ratio of ammonia or ammonium bicarbonate solution added in step 3 to butyraldehyde is 60:40.

[0007] Preferably, the concentration of the pure water containing the detergent in step 3 is 0.1-20%.

[0008] Preferably, the detergent in step 3 is one or more of detergent 105, detergent YR-301, detergent EAF, detergent 721, detergent 803, detergent 826 and detergent LS, all of which are composed of surfactants.

[0009] The beneficial effects of this invention are: Traditional PVB resin washing processes typically use large amounts of pure water at around 50°C to repeatedly wash the PVB resin, ultimately removing a significant amount of butyraldehyde and other impurities from the resin powder. This washing process usually consumes 30-50 tons of pure water per ton of product, resulting in a butyraldehyde residue of approximately 0.01% of the finished product weight. Small amounts of salts and other impurities also remain, affecting product quality. However, the formaldehyde and acid removal method of this invention easily separates excess ammonia or ammonium bicarbonate solution, reducing the number of washes and saving water. It replaces commonly used caustic soda, avoiding the formation and residue of sodium salts. Excess ammonia or ammonium bicarbonate solution can significantly reduce butyraldehyde residue, controlling it to below 0.001% of the finished product weight. The introduction of a specialized cleaning agent for organic matter, composed of surfactants, effectively removes large amounts of acids, salts, and other impurities. Residual ammonium chloride can also be decomposed into hydrogen chloride and ammonia gas and volatilized during the subsequent drying stage, significantly improving product quality. Detailed Implementation

[0010] The technical solution of the present invention will be described in detail below with reference to the embodiments. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0011] The following examples compare the effects of different washing methods. The reactants obtained after condensation during the production of PVB resin were obtained according to the following steps: Add 100g PVA and 1000mL of pure water to a three-necked flask, soak for half an hour, then gradually heat to 95℃ and maintain this temperature for 2 hours. Cool the dissolved solution to 15℃, add 12g hydrochloric acid, mix thoroughly, and then add 56g n-butyraldehyde dropwise over 20 minutes while stirring. After the addition is complete, maintain the temperature for 60 minutes. Begin heating, gradually increasing the temperature to 60℃ over 3 hours, and then maintain this temperature for 2 hours to obtain the condensed reaction mixture.

[0012] Comparative Example 1 After draining the liquid from the material following the condensation reaction, add 1L of pure water, stir well, then heat the liquid to 50℃ and keep it warm for 20 minutes before draining the liquid.

[0013] In this embodiment, the washing process was repeated 10 times with pure water, consuming a total of 10L of water.

[0014] The washed materials are dried to obtain the product. The product is then tested for residual butyraldehyde, which is approximately 0.0157%. The final water wash pH is 6.38.

[0015] Comparative Example 2 After draining the liquid from the material following the condensation reaction, add 1L of 0.02% NaOH solution, stir until homogeneous, then heat the liquid to 50℃ and maintain the temperature for 20 minutes before draining the liquid.

[0016] In this embodiment, the washing process was repeated 10 times with pure water, consuming a total of 10L of water.

[0017] The washed materials are dried to obtain the product. The product is then tested for residual butyraldehyde, which is approximately 0.0089%. The final water wash pH is 7.39.

[0018] Example 1 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities. 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent 105 to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water twice to complete the water washing process for formaldehyde and acid removal.

[0019] In this embodiment, the washing process is repeated four times (once in step 3.1, once in step 3.2, and twice in step 3.3), using 1L of water per wash, for a total water consumption of 4L. The washed material is then dried to obtain the product. Residual butyraldehyde was tested on the product, and the residual butyraldehyde was approximately 0.0006%. The final water wash pH was 7.14.

[0020] Example 2 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities. 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent YR-301 to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water twice to complete the water washing process for formaldehyde and acid removal.

[0021] In this embodiment, the material was washed four times, with 1L of water used each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. The product was tested for residual butyraldehyde, which was found to be approximately 0.0004%. The final water wash pH was 7.09.

[0022] Example 3 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonium bicarbonate solution (the weight ratio of ammonium bicarbonate solution to butyraldehyde is 60:40) to the solid material in step 1 and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities. 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent EAF to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water twice to complete the water washing process for formaldehyde and acid removal.

[0023] In this embodiment, the material was washed four times, with 1L of water used each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. The product was tested for residual butyraldehyde, and the residual butyraldehyde was approximately 0.0005%. The pH of the final wash was 7.12.

[0024] Example 4 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonium bicarbonate solution (the weight ratio of ammonium bicarbonate solution to butyraldehyde is 60:40) to the solid material in step 1 and stir evenly to obtain a mixture. Step 3: Wash with water, heat, and drain to remove butyraldehyde and other impurities. 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent 721 to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0025] In this embodiment, the material was washed four times, using 1L of water each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. Residual butyraldehyde was tested on the product, and the residual butyraldehyde was approximately 0.0005%. The final water wash pH was 7.09.

[0026] Example 5 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities: 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent 803 to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0027] In this embodiment, the material was washed four times, with 1L of water used each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. The product was tested for residual butyraldehyde, and the residual butyraldehyde was approximately 0.0006%. The pH of the final wash was 7.11.

[0028] Example 6 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities: 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent 826 to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0029] In this embodiment, the material was washed four times, with 1L of water used each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. The product was tested for residual butyraldehyde, and the residual butyraldehyde was approximately 0.0007%. The final water wash pH was 7.10.

[0030] Example 7 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities: 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent LS to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0031] In this embodiment, the material was washed four times, using 1L of water each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. Residual butyraldehyde was tested on the product, and the residual butyraldehyde was approximately 0.0005%. The final water wash pH was 7.09.

[0032] Example 7 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonium bicarbonate solution (the weight ratio of ammonium bicarbonate solution to butyraldehyde is 60:40) to the solid material in step 1 and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities: 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water containing detergent LS to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0033] In this embodiment, the material was washed four times, using 1L of water each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. Residual butyraldehyde was tested on the product, and the residual butyraldehyde was approximately 0.0005%. The final water wash pH was 7.09.

[0034] Example 8 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2: Add ammonia or ammonium bicarbonate solution Add ammonia water to the solid material from step 1 (the weight ratio of ammonia water to butyraldehyde is 60:40) and stir evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and other impurities: 3.1 Add 1L of pure water containing ammonia to the mixture in step 2, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add 1L of pure water to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes, then drain the liquid again. 3.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0035] In this embodiment, the material was washed four times, with 1L of water used each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. The product was tested for residual butyraldehyde, which was found to be approximately 0.0032%. The final water wash pH was 7.29.

[0036] Example 9 Step 1: Determination of butyraldehyde content After the condensation reaction, the liquid in the material was drained, and then the butyraldehyde content in the remaining solid material was measured. Step 2 2.1 Add 1L of pure water to the solid material in step 1, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid. 2.2 Add 1L of pure water containing detergent LS to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes, then drain the liquid again. 2.3 Continue rinsing with pure water for a total of 2 times to complete the water rinsing for formaldehyde and acid removal.

[0037] In this embodiment, the material was washed four times, using 1L of water each time, for a total water consumption of 4L. The washed material was then dried to obtain the product. Residual butyraldehyde was tested on the product, and the residual butyraldehyde was approximately 0.0040%. The final water wash pH was 6.79.

[0038] Table 1. Test results of materials after washing in Comparative Examples 1, 2, and Examples 1-9. As shown in Table 1, by comparing and analyzing the water consumption and material testing data after washing in the specific implementation process of Comparative Example 1, Comparative Example 2, and Examples 1 to 9, it can be concluded that the method of the present invention has good performance. Excess ammonia or ammonium bicarbonate solution is easily separated. Compared with the traditional method of about 8-10 washes, the number of washes can be reduced, water is saved, and the residual impurities in the product can be significantly reduced. The pH is more controllable. It replaces the commonly used caustic soda, avoiding the formation and residue of sodium salts. Excess ammonia or ammonium bicarbonate solution can significantly reduce the residual amount of butyraldehyde, which can be controlled to be below 0.001% of the finished product weight. The introduction of a cleaning agent specifically for cleaning organic matter, which is composed of surfactants, removes a large amount of acids, salts and other impurities. The residual ammonium chloride can also be decomposed into hydrogen chloride gas and ammonia gas and volatilized cleanly in the subsequent drying stage, which greatly improves the product quality.

[0039] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for removing formaldehyde and acid from PVB resin by water washing, characterized in that: Includes the following steps: Step 1: Determination of butyraldehyde content In the PVB resin production process, after the condensation reaction is completed, the liquid in the reaction material is discharged, and then the butyraldehyde content in the remaining solid material is measured. Step 2: Add ammonia or ammonium bicarbonate solution Based on the butyraldehyde content measured in step 1, ammonia or ammonium bicarbonate solution is added to the solid material described in step 1 and stirred evenly to obtain a mixture. Step 3: Wash with water and heat, then drain to remove butyraldehyde and ammonium salts. 3.1 Add pure water containing ammonia to the mixture described in step 2, stir evenly, then heat up, control the temperature of the liquid at 50-60℃, and keep it at this temperature for 20 minutes to evaporate the butyraldehyde, and then discharge the liquid containing ammonium salt. 3.2 Add pure water containing detergent to the remaining solid material, stir well, then heat up, control the temperature of the liquid at 50-60℃, and keep it warm for 20 minutes, then drain the liquid containing the remaining ammonium salts again. 3.3 Continue washing with pure water twice more to complete the water washing process for removing formaldehyde and acid.

2. The method for removing formaldehyde and acid from PVB resin by water washing as described in claim 1, characterized in that: In step 3, the weight ratio of ammonia or ammonium bicarbonate solution added to butyraldehyde is 60:

40.

3. The method for removing formaldehyde and acid from PVB resin by water washing as described in claim 1, characterized in that: In step 3, the concentration of the pure water containing the detergent is 0.1-20%.

4. The method for removing formaldehyde and acid from PVB resin by water washing as described in claim 1, characterized in that: In step 3, the detergent is one or more of detergent 105, detergent YR-301, detergent EAF, detergent 721, detergent 803, detergent 826 and detergent LS, all of which are composed of surfactants.

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