CN111763275B - Method for prolonging production period of polyvinyl alcohol with low alcoholysis degree - Google Patents
Method for prolonging production period of polyvinyl alcohol with low alcoholysis degree Download PDFInfo
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- CN111763275B CN111763275B CN202010715980.9A CN202010715980A CN111763275B CN 111763275 B CN111763275 B CN 111763275B CN 202010715980 A CN202010715980 A CN 202010715980A CN 111763275 B CN111763275 B CN 111763275B
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- alcoholysis
- polyvinyl alcohol
- alcoholysis degree
- low
- production
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- 238000006136 alcoholysis reaction Methods 0.000 title claims abstract description 59
- 239000004372 Polyvinyl alcohol Substances 0.000 title claims abstract description 48
- 229920002451 polyvinyl alcohol Polymers 0.000 title claims abstract description 48
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 25
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000007788 liquid Substances 0.000 claims abstract description 33
- 229920002689 polyvinyl acetate Polymers 0.000 claims abstract description 19
- 239000011118 polyvinyl acetate Substances 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 14
- 230000002035 prolonged effect Effects 0.000 claims abstract description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 45
- 239000000463 material Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 4
- 239000000243 solution Substances 0.000 description 16
- 230000000694 effects Effects 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 2
- ZCHPKWUIAASXPV-UHFFFAOYSA-N acetic acid;methanol Chemical compound OC.CC(O)=O ZCHPKWUIAASXPV-UHFFFAOYSA-N 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- -1 construction Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention discloses a method for prolonging the production cycle of polyvinyl alcohol with low alcoholysis degree, wherein the polyvinyl alcohol with low alcoholysis degree is obtained by carrying out alcoholysis, crushing, liquid removal and drying on a methanol solution of polyvinyl acetate, and the production cycle of the polyvinyl alcohol with low alcoholysis degree can be prolonged by improving an alcoholysis unit and/or a liquid removal unit. The method of the invention only needs to simply technically improve the original production line and is easy to implement; the method can greatly prolong the production period of the polyvinyl alcohol with low alcoholysis degree, improve the operating rate, reduce the production cost, realize stable production and easily realize the continuity of the production.
Description
Technical Field
The invention relates to the production of polyvinyl alcohol, in particular to a method for prolonging the production period of polyvinyl alcohol with low alcoholysis degree.
Background
Polyvinyl alcohol (PVA) is a polymer compound with a wide range of applications, and is used in textile, food, medicine, construction, wood processing, paper making, printing, agriculture, steel, polymer chemical industry, liquid crystal displays and other industries. The production process of PVA mainly comprises the following steps: firstly, refining and polymerizing Vinyl Acetate (VAC) to obtain a methanol solution of polyvinyl acetate (PVAC); then adding a methanol solution of polyvinyl acetate (PVAC) and a methanol solution of sodium hydroxide into a static mixer for fully mixing, and then feeding the mixture into a belt alcoholysis machine for alcoholysis to obtain solidified PVA; and finally, crushing the solidified PVA, squeezing to remove the liquid, drying and removing the solvent to obtain a finished product. The performance and the application of PVA are related to the alcoholysis degree of the PVA, and the alcoholysis degree is mainly realized by adjusting the addition amount of the alkali. The PVA with the alcoholysis degree lower than 94 percent is called PVA with low alcoholysis degree, has wide application in the aspect of non-fiber, has good biodegradability and can be used as a biodegradable material.
Because the reaction of the PVA with low alcoholysis degree is incomplete, waste liquor can be further separated out in the drying process in the dryer, the drying difficulty of the dryer is high, the effect is poor, the standard reaching rate of volatile matters is only about 80%, and the load (the maximum load is only 4.5 m) has to be reduced in production 3 H) to achieve the volatile index. Meanwhile, the dryer needs to be frequently stopped and cleaned, so that the production cycle of the PVA with low alcoholysis degree is about 15 days,
therefore, the existing alcoholysis method for obtaining PVA with low alcoholysis degree has short production period, reduced production capacity and increased overall production cost, which leads to reduced enterprise competitiveness. How to increase the production cycle of polyvinyl alcohol with low alcoholysis degree is a big problem which has to be faced by the PVA industry.
Disclosure of Invention
Based on the defects of the prior art, the invention provides a method for prolonging the production cycle of polyvinyl alcohol with low alcoholysis degree, aiming at reducing the number of times of parking and cleaning a dryer and prolonging the production cycle of polyvinyl alcohol products with low alcoholysis degree to about 45 days.
The invention adopts the following technical scheme for solving the technical problems:
the invention discloses a method for prolonging the production cycle of polyvinyl alcohol with low alcoholysis degree, which is obtained by carrying out alcoholysis, crushing, liquid removal and drying on a methanol solution of polyvinyl acetate, and is characterized in that: the production period of the polyvinyl alcohol with low alcoholysis degree is prolonged by improving an alcoholysis unit and/or a liquid removal unit.
Further, the improved method for the alcoholysis unit comprises the following steps: the completeness of alcoholysis reaction is improved by improving the mass concentration of the methanol solution of polyvinyl acetate and controlling alcoholysis technological parameters, so that the production cycle of polyvinyl alcohol with low alcoholysis degree is prolonged.
Further, after the alcoholysis unit is modified: the mass concentration of the methanol solution of the polyvinyl acetate is not lower than 35 percent; the sodium hydroxide solution used for alcoholysis is formed by mixing a methanol solution of sodium hydroxide and water, wherein the concentration of the sodium hydroxide is 60-90 g/L, and the mass concentration of the water is 30-40%; in alcoholysis, the molar ratio of the sodium hydroxide to the polyvinyl acetate is 0.011-0.014.
The specific mass concentration of the methanol solution of polyvinyl acetate is determined by the type of PVA to be produced. The PVA variety model consists of two parts of polymerization degree and alcoholysis degree, for example, in the variety model of 17-92 (L), 17 represents that the polymerization degree is 1700, 92 represents that the alcoholysis degree is 92%, and L represents that the product is in a sheet shape. Generally, the lower the degree of polymerization of the product, the higher the control of the mass concentration of the methanol solution of polyvinyl acetate, and vice versa, as shown in the following table:
| serial number | Variety and model | Concentration of |
| 1 | 04-88(L) | 51±1％ |
| 2 | 05-88(L) | 50±1％ |
| 3 | 13-88(L) | 39±1％ |
| 4 | 17-88(L) | 36±1％ |
| 5 | 17-92(L) | 36±1％ |
Further, the improved method of the liquid removal unit comprises the following steps: and (3) removing liquid from the crushed material through a screw extruder, and adding clear liquid to play a role in cleaning a filter screen to prevent blockage, so that the production period of the polyvinyl alcohol with low alcoholysis degree is prolonged.
Furthermore, the adding amount of the clear liquid is 900-1000L/h.
Further, the clear liquid is preferably condensed liquid obtained by condensing steam generated when the material after liquid removal is dried by a dryer (namely, a drying unit), so that the material can be fully recycled.
Compared with the prior art, the invention has the beneficial effects that:
1. the method can prolong the production cycle of the polyvinyl alcohol with low alcoholysis degree from about 15 days to about 45 days, improve the operating rate, reduce the production cost, and have stable production and easy realization of continuous production.
2. In the method of the invention: by adjusting alcoholysis process parameters, the mixing effect of materials can be ensured, the materials can be well formed by reaction on a belt alcoholysis machine and can smoothly pass through a crushing and screw extruder, and meanwhile, the amount of waste liquid separated out from a drying unit is effectively reduced, and the drying difficulty is reduced; by adding the clear liquid while the crushed material is subjected to liquid removal in the screw extruder, the blockage of a filter screen is effectively avoided, and the cleaning period of the screw extruder and a dryer is shortened.
3. The method is suitable for polyvinyl alcohol with different low alcoholysis degrees, and can meet the requirements of different varieties.
4. The method of the invention does not affect the indexes of the PVA product such as volatile matter, sodium acetate, methanol content and the like.
5. The method provided by the invention has the advantages that the used raw materials and equipment are conventional raw materials and equipment, the original production line can be simply technically improved and the process is adjusted, the method is safe, environment-friendly and pollution-free, and the policy and the guideline of national green, safe and environment-friendly are met.
Detailed Description
The following examples are given for the detailed implementation and the specific operation procedures, but the scope of the present invention is not limited to the following examples.
Example 1: production of PVA17-92 products
Mixing a methanol solution of sodium hydroxide with pure water to obtain a sodium hydroxide solution with the concentration of 80g/L and the mass concentration of 39% of water; then the mixture and 35.2 mass percent polyvinyl acetate methanol solution are sent into a mixer together, the molar ratio of sodium hydroxide to polyvinyl acetate is 0.011-0.012, the mixture is fully and evenly mixed and then sent into a belt alcoholysis machine, alcoholysis reaction is carried out for 40 minutes at the reaction temperature of 45 +/-2 ℃, blocky polyvinyl alcohol is generated, and mother solution is separated out.
Blocky polyvinyl alcohol enters a screw extruder for liquid removal after being crushed, the rotating speed of the extruder is changed by adjusting the power supply frequency of the extruder motor to control the liquid removal effect, and meanwhile, clear liquid (condensate after steam condensation generated when materials after liquid removal are dried through a dryer) is added into the screw extruder at the adding amount of 900L/h, so that the filter screen is cleaned to prevent blockage.
Drying and heat treating the polyvinyl alcohol after liquid removal to obtain a polyvinyl alcohol PVA17-92 product.
The normal production cycle for this product was 45 days.
The quality indexes of the produced products are comprehensively analyzed and displayed: the main quality indexes are not influenced, and the using effect of a client is not influenced.
Example 2: production of PVA17-88 products
Mixing a methanol solution of sodium hydroxide with pure water to obtain a sodium hydroxide solution with the concentration of 60g/L and the mass concentration of 32% of water; then the mixture and 35.5 mass percent polyvinyl acetate methanol solution are sent into a mixer together, the molar ratio of sodium hydroxide to polyvinyl acetate is 0.013-0.014, the mixture is fully and evenly mixed and then sent into a belt alcoholysis machine, alcoholysis reaction is carried out for 45 minutes at the reaction temperature of 45 +/-2 ℃, block polyvinyl alcohol is generated, and mother liquor is separated out.
Blocky polyvinyl alcohol enters a screw extruder for liquid removal after being crushed, the rotating speed of the extruder is changed by adjusting the power supply frequency of a motor of the extruder to control the liquid removal effect, and meanwhile, clear liquid (condensate after steam condensation generated when materials after liquid removal are dried through a dryer) is added into the screw extruder at the adding amount of 1000L/h, so that the filter screen is cleaned to prevent blockage.
Drying and heat treating the deliquored polyvinyl alcohol to obtain a polyvinyl alcohol PVA17-88 product.
The normal production cycle for producing the product in this embodiment is 40 days, and since the lower the alcoholysis degree of the PVA product, the higher the reaction imperfection degree is, the more the waste liquid is precipitated in the drying process of the dryer, the more the skinning of the dryer is caused, the greater the drying difficulty is, the worse the effect is, and the shorter the production cycle becomes, the production cycle of the 17-88 variety is relatively shorter than that of the 17-92 variety. However, through the improvement of the embodiment, the production cycle of PVA17-88 products is greatly improved compared with the prior art.
The quality indexes of the produced products are comprehensively analyzed and displayed: the main quality indexes are not influenced, and the using effect of a client is not influenced.
The above description is only exemplary of the present invention and should not be taken as limiting the invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (2)
1. A method for prolonging the production cycle of polyvinyl alcohol with low alcoholysis degree, wherein the polyvinyl alcohol with low alcoholysis degree is obtained by carrying out alcoholysis, crushing, liquid removal and drying on a methanol solution of polyvinyl acetate, and is characterized in that: the production period of the polyvinyl alcohol with low alcoholysis degree is prolonged by improving the alcoholysis unit and the liquid removal unit;
the improved method for the alcoholysis unit comprises: the completeness of alcoholysis reaction is improved by improving the mass concentration of the methanol solution of polyvinyl acetate and controlling alcoholysis process parameters, so that the production cycle of polyvinyl alcohol with low alcoholysis degree is prolonged; after the alcoholysis unit is improved: the mass concentration of the methanol solution of the polyvinyl acetate is not lower than 35 percent; the sodium hydroxide solution used for alcoholysis is formed by mixing a methanol solution of sodium hydroxide and water, wherein the concentration of the sodium hydroxide is 60-90 g/L, and the mass concentration of the water is 30-40%; during alcoholysis, the molar ratio of the sodium hydroxide to the polyvinyl acetate is 0.011-0.014;
the improved method of the liquid removal unit comprises the following steps: while removing liquid from the crushed material through a screw extruder, adding clear liquid to play a role in cleaning a filter screen to prevent blockage, thereby prolonging the production period of the polyvinyl alcohol with low alcoholysis degree; the clear liquid is condensed liquid after the steam generated by the drying unit is condensed.
2. The method of claim 1, wherein the production cycle time of the polyvinyl alcohol with low alcoholysis degree is prolonged by: the adding amount of the clear liquid is 900-1000L/h.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010715980.9A CN111763275B (en) | 2020-07-23 | 2020-07-23 | Method for prolonging production period of polyvinyl alcohol with low alcoholysis degree |
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| CN202010715980.9A CN111763275B (en) | 2020-07-23 | 2020-07-23 | Method for prolonging production period of polyvinyl alcohol with low alcoholysis degree |
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| CN111763275A CN111763275A (en) | 2020-10-13 |
| CN111763275B true CN111763275B (en) | 2023-03-28 |
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| CN114426692B (en) * | 2020-10-15 | 2024-02-09 | 中国石油化工股份有限公司 | Forming method of polyvinyl alcohol solid with ultralow alcoholysis degree |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4338405A (en) * | 1980-12-12 | 1982-07-06 | E. I. Du Pont De Nemours And Company | Process for continuous controlled alcoholysis of polyvinyl acetate |
| CN1330090A (en) * | 2001-08-01 | 2002-01-09 | 青岛化工学院 | Process for preparing polyvinyl alcohol with low alcoholysis level |
| CN101575391A (en) * | 2009-06-11 | 2009-11-11 | 安徽皖维高新材料股份有限公司 | Polyvinyl alcohol with low degree of polymerization and alcoholysis method thereof |
| CN104558319A (en) * | 2013-10-22 | 2015-04-29 | 中国石油化工集团公司 | Method for improving forming of low-viscosity polyvinyl alcohol |
| CN107474163A (en) * | 2017-08-24 | 2017-12-15 | 安徽皖维高新材料股份有限公司 | A kind of alcoholysis method of polyvinyl alcohol with low alcoholysis level |
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2020
- 2020-07-23 CN CN202010715980.9A patent/CN111763275B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4338405A (en) * | 1980-12-12 | 1982-07-06 | E. I. Du Pont De Nemours And Company | Process for continuous controlled alcoholysis of polyvinyl acetate |
| CN1330090A (en) * | 2001-08-01 | 2002-01-09 | 青岛化工学院 | Process for preparing polyvinyl alcohol with low alcoholysis level |
| CN101575391A (en) * | 2009-06-11 | 2009-11-11 | 安徽皖维高新材料股份有限公司 | Polyvinyl alcohol with low degree of polymerization and alcoholysis method thereof |
| CN104558319A (en) * | 2013-10-22 | 2015-04-29 | 中国石油化工集团公司 | Method for improving forming of low-viscosity polyvinyl alcohol |
| CN107474163A (en) * | 2017-08-24 | 2017-12-15 | 安徽皖维高新材料股份有限公司 | A kind of alcoholysis method of polyvinyl alcohol with low alcoholysis level |
Non-Patent Citations (1)
| Title |
|---|
| 醇解度PVA的压榨设备选用探讨;王小明;《化工管理》;20140216(第6期);77-78 * |
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Denomination of invention: A method for prolonging the production cycle of low alcohol solubility polyvinyl alcohol Effective date of registration: 20231120 Granted publication date: 20230328 Pledgee: Industrial and Commercial Bank of China Limited Chaohu sub branch Pledgor: ANHUI WANWEI UPDATED HIGH-TECH MATERIAL INDUSTRY Co.,Ltd. Registration number: Y2023980066338 |