CN106854255B - Modified polyvinyl alcohol and preparation method thereof - Google Patents
Modified polyvinyl alcohol and preparation method thereof Download PDFInfo
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Abstract
A modified polyvinyl alcohol having the formula:
x, y and z are integers, x is more than 1 and less than or equal to 500, y is more than 1 and less than or equal to 2000, z is more than 1 and less than or equal to 200, y is more than x, and y is more than z; in the formula R1Is oxygen atom or-CO-or- (CH-OH) -; r2Is alkyl, alkoxy or hydroxy-terminated alkyl. The invention has less monomer copolymerization participation and moderate reaction speed, and the prepared vinyl acetate-branched vinyl copolymer has the conversion rate of 40-80 percent, the alcoholysis product alcoholysis degree of 98-99.8 mol percent, the crystallinity of less than 20 percent, the melting point of 160-195 ℃ and the viscosity of 3.0-25.0 mPa.s (20 ℃,4 percent aqueous solution), can be melt-processed and has good processing performance.
Description
Technical Field
The invention relates to modified polyvinyl alcohol and a preparation method thereof, belonging to the field of polymer chemistry.
Background
Polyvinyl alcohol (PVA) is a polar, nontoxic and crystalline polymer with good biocompatibility, and is widely applied to the fields of coatings, adhesives, dispersants, chemical fibers, films, packaging materials, biomedical materials and the like. The PVA has regular molecular chain structure and contains a large amount of polar groups, namely hydroxyl groups, and intramolecular or intermolecular hydrogen bonds are easily formed between adjacent hydroxyl groups, so that the melting temperature is between 220 and 240 ℃, the melting temperature is close to the decomposition temperature, the thermoplastic processing is difficult, and the application range of the polyvinyl alcohol is greatly limited.
In order to solve the problem that the traditional polyvinyl alcohol is difficult to be subjected to thermoplastic processing, a great deal of research is carried out on the modification technology of the PVA at home and abroad, and the development of a novel PVA product with a high added value becomes a hot point of the research at home and abroad, copolymerization modification is an important method for improving the thermoplastic processing of the polyvinyl alcohol, wherein a vinyl monomer is the most common copolymerization modification monomer, the modification vinyl monomer is introduced into a polyvinyl alcohol molecular chain, the regular arrangement of molecules is hindered, and the crystallinity is reduced, so that the melting temperature of the modified polyvinyl alcohol is greatly reduced, but the water solubility of the modified polyvinyl alcohol is greatly limited, the patent CN 99126427.4 reports that vinyl acetate, a α -olefin monomer or vinyl ether monomer (6-13 mol%) with the carbon number less than 4 and a monomer (0.02-0.15 mol%) capable of generating branched carboxylic acid and lactone are copolymerized, a copolymerization product can be subjected to alcoholysis to obtain the modified polyvinyl alcohol with the melting point of 160-230 ℃, but the used comonomer amount is larger, and the patent CN102603954 adopts a long-chain branched carboxylic acid vinyl ester and vinyl acetate copolymer to obtain the polyvinyl alcohol which can be subjected to melt processing at a narrow window, but the melting temperature of the polyvinyl alcohol is 190.
Disclosure of Invention
The invention aims to provide modified polyvinyl alcohol, which has a small amount of monomer participating in copolymerization and a large window for melt processing.
Another object of the present invention is to provide a process for producing the above-mentioned modified polyvinyl alcohol, which is simple and easy to carry out.
The purpose of the invention is realized as follows:
a modified polyvinyl alcohol having the formula:
x, y and z are integers, x is more than 1 and less than or equal to 500, y is more than 1 and less than or equal to 2000, z is more than 1 and less than or equal to 200, y is more than x, and y is more than z; in the formula R1Is oxygen atom or-CO-or- (CH-OH) -; r2Is alkyl, alkoxy or hydroxy-terminated alkyl.
In order to lower the crystallinity and melting point of the modified polyvinyl alcohol, R2Preferably C1-C6 alkyl, C1-C4 alkoxy or C1-C6 hydroxyalkyl.
R is as defined above2More preferably C1-C4 alkyl, most preferably methyl, ethyl or butyl.
The alkoxy group is more preferably an alkoxy group having 1 to 3 carbon atoms, and most preferably a methoxy group, an ethoxy group or a propoxy group.
The above-mentioned hydroxyalkyl group is more preferably an alkyl group having 1 to 4 carbon atoms, and most preferably a hydroxymethyl group, a hydroxyethyl group or a hydroxybutyl group.
The modified polyvinyl alcohol is melt-processable and has a melting point of 160-195 ℃, a crystallinity of 0-20%, a viscosity of 3.0-25.0 mPa.s (20 ℃, 4% aqueous solution), and an alcoholysis degree of more than 98 mol%.
The preparation method of the modified polyvinyl alcohol adopts vinyl acetate monomer and branched vinyl monomer as raw materials, and the vinyl acetate monomer and the branched vinyl monomer are copolymerized under the action of an initiating system, and the obtained copolymer is saponified and alcoholyzed to prepare the modified polyvinyl alcohol; the branched vinyl monomer is a vinyl alcohol ether monomer, a vinyl carbonate monomer or an acrylate monomer.
The vinyl alcohol ether monomer is one or more of vinyl methyl ether, vinyl ethyl ether, vinyl n-propyl ether, vinyl isopropyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl tert-butyl ether, vinyl cyclohexyl ether, 4-hydroxybutyl vinyl ether and ethylene glycol monoallyl ether.
The vinyl carbonate monomer is one or a combination of more of vinyl ethyl carbonate, vinyl ethylene carbonate and 3, 4-diacetoxy-1-butylene.
The acrylic ester monomer is selected from one or a combination of methyl acrylate, ethyl acrylate and butyl acrylate.
The copolymerization mode of the preparation method can adopt emulsion polymerization, solution polymerization or suspension polymerization, and preferably adopts free radical solution polymerization. The feeding mode of the monomer component in the copolymerization is not strictly limited, and any method such as one-time feeding, batch feeding, continuous feeding and the like can be selected according to actual conditions.
The copolymerization solution in the above-mentioned preparation method may be an alcoholic solvent, particularly an alcohol having 1 to 4 carbon atoms such as methanol, ethanol, propanol, n-butanol and t-butanol, or a mixed solvent of the above-mentioned two alcohols, or a mixed solvent containing the above-mentioned alcohol as a main component, and methanol is particularly preferable.
The copolymerization initiator of the preparation method can be selected from azo initiators, peroxide initiators, redox initiators and the like; among them, a composite initiation system is preferable, and a composite system of an azo initiator and a peroxide initiator is preferable. Wherein the azo initiator can be azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobis (2-methylbutyronitrile), etc.; the peroxide initiator can be inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and the like, or organic peroxides including benzoyl peroxide, alkyl peroxide esters, peroxycarbonate esters and the like. Benzoyl peroxides such as benzoyl peroxide, benzoyl t-butyl peroxide, methyl ethyl ketone peroxide, diisobutyl peroxide, etc.; alkyl peroxide esters such as pivaloyl peroxyneodecanoate, pivaloyl peroxypivalate, and tert-butyl peroxyacetate; peroxycarbonates such as bis (4-tert-butylcyclohexyl) peroxydicarbonate, dibutyl peroxydicarbonate, and the like.
The initiator of the invention is preferably a combination of an azo initiator and more than one peroxy initiator, such as azobisisobutyronitrile/benzoyl peroxide, azobisisobutyronitrile/peroxycarbonate, azobisisobutyronitrile/alkyl peroxycarbonate, more preferably azobisisobutyronitrile/alkyl peroxycarbonate, most preferably azobisisobutyronitrile/alkyl peroxycarbonate.
When the product obtained by solution copolymerization is used for alcoholysis in the preparation process, no special requirement exists, the catalyst can be known alkaline catalysts such as sodium hydroxide and potassium hydroxide, and the dosage of the catalyst, the alcoholysis mode, the solvent for alcoholysis and the like are determined according to actual conditions.
In particular, the present invention relates to a method for producing,
a method for preparing polyvinyl alcohol capable of being melt-processed is characterized by comprising the following steps:
the vinyl acetate-branched ethylene random copolymer is prepared by taking 20-100 parts by weight of alcohols as a solvent, 40-150 parts by weight of a vinyl acetate monomer, 0.005-1 part by weight of an initiator and 3-8 parts by weight of a branched vinyl monomer as raw materials and reacting at 25-80 ℃ for 2-7 hours.
10-20 parts by weight of vinyl acetate-branched ethylene random copolymer is added into an alcoholysis solution composed of 80-90 parts by weight of methanol and 0.05-1 part by weight of catalyst alkali, and alcoholysis reaction is carried out at the temperature of 40-60 ℃ for 2-3 hours to obtain the modified polyvinyl alcohol capable of being melt processed.
The polyvinyl alcohol copolymer prepared by the preparation method has good melt processability. The inventor finds that the modified polyvinyl alcohol with the melting point of 160-195 ℃ can be prepared only by controlling the proportion of each reaction raw material and the reaction time well.
More specifically, the present invention relates to a method for producing,
a method for preparing polyvinyl alcohol capable of being melt-processed is characterized by comprising the following steps:
(1) initial charge
Preferably 30-100 parts of methanol, 40-120 parts of vinyl acetate monomer, 0.04-0.5 part of initiator and 4-7 parts of branched vinyl monomer, adding the branched vinyl monomer into a reaction system in a step-by-step feeding manner for 0.5-2 h, slowly heating to 40-70 ℃, polymerizing for 3-6 h, and adding 0.08-2 parts of polymerization inhibitor after the reaction is finished.
(2) Blow out the incomplete sheet
And (3) raising the external temperature to 70-90 ℃, and removing unreacted monomers in the reaction product to obtain the resin solution of the polyvinyl acetate copolymer.
(3) Dissolving and saponifying
Preparing the resin solution of the vinyl acetate-branched vinyl random copolymer into a solution with the mass fraction of 15-30% by using methanol, and adding alkali liquor for alcoholysis to obtain a product of the modified polyvinyl alcohol copolymer; the alkali liquor is a methanol solution of NaOH, the concentration of solute NaOH is 50g/L, and the molar ratio of the alkali liquor to the vinyl acetate-branched vinyl random copolymer is 0.02-0.05: 1.
The polymerization inhibitor is selected from one or more of sorbic acid, hydroquinone and thiourea.
The invention has the following beneficial effects:
the invention introduces a unit with weaker acting force into a PVA molecular chain through copolymerization reaction, changes the structure and regularity of the PVA molecular chain, and weakens the acting force among PVA molecules, thereby reducing the melting point and improving the thermoplastic processing performance of the PVA. The modified polyvinyl alcohol provided by the invention has the advantages that the monomer copolymerization participation amount is small, the reaction speed is moderate, the conversion rate of the prepared vinyl acetate-branched vinyl copolymer is 40-80%, the alcoholysis degree of the alcoholysis product is 98-99.8 mol%, the crystallinity is less than 20%, the melting point is 160-195 ℃, the viscosity is 3.0-25.0 mPa.s (20 ℃, 4% aqueous solution), the modified polyvinyl alcohol can be processed by melting, and the processability is good. Meanwhile, the preparation method of the modified polyvinyl alcohol is simple and is convenient for industrial production.
Drawings
FIG. 1 is an infrared spectrum of a modified polyvinyl alcohol prepared according to a preferred embodiment of the present invention
FIG. 2 shows a common PVAC and a modified PVAC1H-NMR spectrum
FIG. 3 shows a view of a conventional PVA and a modified PVA1H-NMR spectrum
Examples
In order to make the objects and technical solutions of the present invention clearer, preferred embodiments of the present invention are described in detail below. It is to be noted that: the following examples are intended to illustrate the invention further and are not to be construed as limiting the scope of the invention. The invention is not limited to the embodiments described above, but rather, many modifications and variations may be made by one skilled in the art without departing from the scope of the invention.
Example 1
A preparation method of modified polyvinyl alcohol capable of being melt-processed comprises the following steps:
(1) initial charge
Putting 45 parts of methanol, 55 parts of vinyl acetate monomer and 0.2 part of composite initiator (AIBN: benzoyl peroxide: 2:5) into a reactor; and adding 4 parts of vinyl ethylene carbonate monomer into the reaction system in a one-step feeding mode for 1.5 hours, slowly heating to 63 ℃, polymerizing for 5 hours, and adding 0.6 part of sorbic acid after the reaction is finished.
(2) Blow out the incomplete sheet
And raising the external temperature to 85 ℃, and removing unreacted monomers in the reaction product to obtain the resin solution of the polyvinyl acetate copolymer.
(3) Dissolving and saponifying
Preparing the resin solution of the vinyl acetate-branched vinyl random copolymer into a solution with the mass fraction of 20% by using methanol, and adding alkali liquor for alcoholysis to obtain a product of the modified polyvinyl alcohol copolymer; the alkali liquor is a methanol solution of NaOH, the concentration of solute NaOH is 50g/L, and the molar ratio of the alkali liquor to the vinyl acetate-branched vinyl random copolymer is 0.03: 1.
Product performance parameters: the conversion rate is 70%, the alcoholysis product alcoholysis degree is 99.1 mol%, the crystallinity is 16.5%, the melting point is 185.3 ℃, the viscosity is 4.7 mPa.s, and the resin has good processability.
Infrared qualitative analysis
Firstly, a sample is ground together with potassium bromide powder after being dried, and FT-IR spectrum analysis is carried out after tabletting. The measurements were carried out using a Bruke Nicolet model 560 fourier transform infrared spectrometer, see fig. 1.
According to FIG. 1, the IR spectrum is represented by 3413cm-1(-OH peak;) 2939cm-1, 2860cm-1, 1449cm-1 and 1333cm-1(-CH, -CH2 methine and methylene peaks); 1645cm-1 (water adsorption peak); 1096cm-1(-C-O carbon oxygen single bond peak); characteristic peaks such as 850cm-1 (skeleton peak of modified PVA molecule) and the like show that the product is modified PVA with high alcoholysis degree.
Measurement of polymerization degree
The modified PVA obtained in example 1 was measured for polymerization degree according to GB 12010.9-89, and the polymerization degree of the PVA was 500, that is, x + y + z was 500.
Determination of the degree of alcoholysis
The alcoholysis degree of the alcohol is tested according to the method of GB 120010.5-89:
the calculation formula is as follows:
ac-in the formula represents residual acetate, and can be calculated according to the method of GB 12010.5-89, the final calculated alcoholysis degree of the product is 99.01%, and (y +2z)/(x + y +2z) ═ 0.9901.
The molecular structure of the resin was analyzed by Bruker AV II-400MHz NMR for the PVAc solution without modified monomer and the PVAc solution with modified monomer, as shown in FIG. 2.
According to fig. 2, the nuclear magnetic data of the PVAc solution without modified monomer and the PVAc with modified monomer are represented as:
1.75 ppm: a methylene proton; 1.913-2.126 ppm: a methyl proton; 4.058-4.206 ppm and 4.635-4.909 ppm: side chain methylene protons of a modified part in a molecular chain are 5.243-5.336 ppm: methine protons and a modified portion of the side chain methine protons.
The PVA without the modified monomer and the PVA with the modified monomer are treated by adopting deuterated dimethyl sulfoxide as a solvent, and the molecular structure of the resin is analyzed by adopting a Bruker AV II-400MHz nuclear magnetic resonance instrument, which is shown in figure 3.
According to FIG. 3, the nuclear magnetic data of the unmodified monomer PVA and the modified monomer PVA are shown as follows:
1.2-1.5 ppm: a methylene proton; 1.8 ppm: a methine proton; 3.5 ppm: methylene protons of primary hydroxyl groups; 3.88 ppm: a methine proton; 4.15-4.7 ppm: a hydroxyl group; 4.2 ppm: the hydroxyl group of the diol. The obtained comonomer contains double bonds and two ester bond structures, and the modified PVAc contains glycol bonds after alcoholysis. The modified product obtained was calculated from the H-NMR chart to have a modified unit content of 7% (molar ratio), so that z/(x + y + z): 0.07.
As can be seen from fig. 1, 2 and 3, the molecular structural formula of the modified PVA is:
x, y and z are integers, x is more than 1 and less than or equal to 500, y is more than 1 and less than or equal to 2000, z is more than 1 and less than or equal to 200, y is more than x, and y is more than z; calculated from the degree of polymerization, degree of alcoholysis and nuclear magnetic analysis, x is 5, y is 488, and z is 7.
Measurement of melting point and crystallinity:
the melting behavior of a sample is tested by adopting a DSC204 differential scanning calorimeter of German Nachi company, 5-10 mg of a dried sample is accurately weighed and placed in a stainless steel crucible, and the sample is heated to 210 ℃ from 40 ℃ at the speed of 30 ℃/min in a nitrogen atmosphere, so that the heat history is eliminated. Then the temperature is reduced to 40 ℃ at the speed of 10 ℃/min, then the temperature is increased to 230 ℃ at the speed of 10 ℃/min, and the temperature change curve of HAVOH is recorded. The sample crystallinity was calculated as follows:
degree of crystallinity:
wherein, Δ HcIs the melting enthalpy of the sample, is the melting enthalpy of 100% crystalline PVA, and is known from literature
DSC measurement was carried out on the modified PVA sample in the above-mentioned manner, and the Tm was 185.3 ℃ and Δ H was measuredc＝5.48cal·g-1Calculated crystallinity was 16.5%.
Measurement of viscosity
After drying the sample, a 4% aqueous solution was prepared accurately, and after completely dissolving the sample, the sample was placed in a thermostatic water bath at 25 ℃ and kept at a constant temperature for 30 minutes, and then the viscosity of the solution was measured with a Brookfield Ld rotational viscometer ( spindle # 0, 20 rpm).
The viscosity of the modified PVA measured in this manner was 4.7 mPas.
Example 2
The parameters were selected as shown in Table 1 below, and the other operation was the same as in example 1.
Note: a1: vinyl isobutyl ether; a2: vinyl tert-butyl ether; a3: vinyl ethylene carbonate; a4: butyl acrylate; a5: vinyl cyclohexyl ether;
a6: ethylene glycol monoallyl ether; a7: butyl acrylate, ethyl acrylate 3: 1; a8 vinyl isobutyl ether, vinyl tert-butyl ether 2: 1; a9: 3, 4-diacetoxy-1-butene; a10: vinyl ethylene carbonate vinyl ethyl carbonate ═ 1: 2
As can be seen from the schemes in groups 1 to 16 in the table I, the scheme in group 3 is relatively excellent, namely a methanol system, a composite initiator (AIBN: tert-butyl peroxyacetate ═ 1:3), the reaction temperature is 65 ℃, the reaction time is 5 hours, the conversion rate can be controlled at about 70%, the modified PVA obtained by alcoholysis has moderate crystallinity and melting point, and the sample is soluble in water; if the branched modified monomer is not added, and other conditions are the same as the following group 15, the conversion rate is higher and can reach 95%, and the obtained PVA is insoluble in water, has higher crystallinity and melting point and is not beneficial to melt processing; if other conditions are the same as those in group 14 and AIBN is adopted, the conversion rate is lower by about 50 percent, and the crystallinity is slightly higher; if the other conditions are the same as those in group 16, tert-butyl peroxyacetate is adopted, the reaction speed is high, the 4-hour conversion rate can reach about 80%, the crystallinity and the melting point of the PVA are high, and part of samples are insoluble.
Claims (44)
1. A modified polyvinyl alcohol having the formula:
x, y and z are integers, x is more than 1 and less than or equal to 500, y is more than 1 and less than or equal to 2000, z is more than 1 and less than or equal to 200, y is more than x, and y is more than z; wherein R1 is oxygen atom or-CO-; r2 is alkyl, alkoxy or hydroxy-terminated alkyl.
2. The modified polyvinyl alcohol of claim 1, wherein: the alkyl in R2 is C1-C6 alkyl; the alkoxy is C1-C4 alkoxy; the terminal hydroxyalkyl is a terminal hydroxyalkyl of C1-C6.
3. The modified polyvinyl alcohol of claim 1, wherein: the alkyl in R2 is C1-C4 alkyl; the alkoxy is C1-C3 alkoxy; the terminal hydroxyalkyl is a terminal hydroxyalkyl of C1-C4.
4. The modified polyvinyl alcohol of any one of claims 1 to 3, wherein: the alkyl group in R2 is methyl, ethyl or butyl; the alkoxy is methoxy, ethoxy or propoxy; the hydroxyl-terminated alkyl is hydroxymethyl, hydroxyethyl or hydroxybutyl.
5. A process for the preparation of polyvinyl alcohol according to any one of claims 1 to 3, wherein:
vinyl acetate monomer and branched vinyl monomer are adopted as raw materials, copolymerization is carried out under the action of an initiation system, and saponification and alcoholysis are carried out on the obtained copolymer to prepare the modified polyvinyl alcohol; the branched vinyl monomer is a vinyl alcohol ether monomer, a vinyl carbonate monomer or an acrylate monomer.
6. The method for producing polyvinyl alcohol according to claim 4, wherein:
vinyl acetate monomer and branched vinyl monomer are adopted as raw materials, copolymerization is carried out under the action of an initiation system, and saponification and alcoholysis are carried out on the obtained copolymer to prepare the modified polyvinyl alcohol; the branched vinyl monomer is a vinyl alcohol ether monomer, a vinyl carbonate monomer or an acrylate monomer.
7. The method of claim 5, wherein: the vinyl alcohol ether monomer is selected from one or a combination of more of vinyl methyl ether, vinyl ethyl ether, vinyl n-propyl ether, vinyl isopropyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl tert-butyl ether, vinyl cyclohexyl ether, 4-hydroxybutyl vinyl ether and ethylene glycol monoallyl ether; the vinyl carbonate monomer is selected from one or a combination of more of vinyl ethyl carbonate, vinyl ethylene carbonate and 3, 4-diacetyloxy-1-butylene; the acrylic ester monomer is selected from one or a combination of methyl acrylate, ethyl acrylate and butyl acrylate.
8. The method of claim 6, wherein: the vinyl alcohol ether monomer is selected from one or a combination of more of vinyl methyl ether, vinyl ethyl ether, vinyl n-propyl ether, vinyl isopropyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl tert-butyl ether, vinyl cyclohexyl ether, 4-hydroxybutyl vinyl ether and ethylene glycol monoallyl ether; the vinyl carbonate monomer is selected from one or a combination of more of vinyl ethyl carbonate, vinyl ethylene carbonate and 3, 4-diacetyloxy-1-butylene; the acrylic ester monomer is selected from one or a combination of methyl acrylate, ethyl acrylate and butyl acrylate.
9. The method of claim 5, wherein: the copolymerization solution of the preparation method adopts one or a combination of methanol, ethanol, propanol, n-butanol and tert-butanol.
10. The method of claim 6, wherein: the copolymerization solution of the preparation method adopts one or a combination of methanol, ethanol, propanol, n-butanol and tert-butanol.
11. The method of claim 5, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
12. The method of claim 6, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
13. The method of claim 7, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
14. The method of claim 8, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
15. The method of claim 9, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
16. The method of claim 10, wherein: the initiation system is a composite initiation system of azo initiator and peroxide initiator.
17. The method of claim 11, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
18. The method of claim 12, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
19. The method of claim 13, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
20. The method of claim 14, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
21. The method of claim 15, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
22. The method of claim 16, wherein: the azo initiator can be one or a combination of a plurality of azodiisobutyronitriles, azodiisoheptonitrile, azodiisobutyronitrile dimethyl ester and azodi (2-methylbutyronitrile).
23. The method of claim 11, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
24. The method of claim 12, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
25. The method of claim 13, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
26. The method of claim 14, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
27. The method of claim 15, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
28. The method of claim 16, wherein: the peroxide initiator is inorganic peroxide or organic peroxide; the inorganic peroxide is one or a combination of more of hydrogen peroxide, ammonium persulfate and potassium persulfate; the organic peroxide is benzoyl peroxide, alkyl ester peroxide and carbonate peroxide; the benzoyl peroxide is one or a combination of benzoyl peroxide, benzoyl peroxide tert-butyl ester, methyl ethyl ketone peroxide and diisobutyryl peroxide; the alkyl ester peroxide is one or a combination of more of neopentyl ester peroxyneodecanoate, neopentyl ester peroxypivalate and tert-butyl peroxyacetate; the peroxycarbonate is one or a combination of more of peroxydicarbonate bis (4-tert-butylcyclohexyl) and peroxydicarbonate dibutyl.
29. The method of claim 11, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
30. The method of claim 12, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
31. The method of claim 13, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
32. The method of claim 14, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
33. The method of claim 15, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
34. The method of claim 16, wherein: the composite initiation system is formed by compounding an azo initiator and more than one peroxy initiator.
35. The method of claim 29, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
36. The method of claim 30, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
37. The method of claim 31, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
38. The method of claim 32, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
39. The method of claim 33, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
40. The method of claim 34, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
41. The method of claim 35, wherein: the composite initiation system is azodiisobutyronitrile/benzoyl peroxide, azodiisobutyronitrile/peroxycarbonate, azodiisobutyronitrile/peroxyalkyl ester.
42. The method according to claim 5, wherein the method comprises the steps of:
taking 20-100 parts by weight of alcohols as a solvent, 40-150 parts by weight of a vinyl acetate monomer, 0.005-1 part by weight of an initiator and 3-8 parts by weight of a branched vinyl monomer as raw materials, and reacting at 25-80 ℃ for 2-7 hours to prepare a vinyl acetate-branched ethylene random copolymer;
10-20 parts by weight of vinyl acetate-branched ethylene random copolymer is added into an alcoholysis solution composed of 80-90 parts by weight of methanol and 0.05-1 part by weight of catalyst alkali, and alcoholysis reaction is carried out at the temperature of 40-60 ℃ for 2-3 hours to obtain the modified polyvinyl alcohol capable of being melt processed.
43. The method according to claim 7, wherein the method comprises the steps of:
taking 20-100 parts by weight of alcohols as a solvent, 40-150 parts by weight of a vinyl acetate monomer, 0.005-1 part by weight of an initiator and 3-8 parts by weight of a branched vinyl monomer as raw materials, and reacting at 25-80 ℃ for 2-7 hours to prepare a vinyl acetate-branched ethylene random copolymer;
10-20 parts by weight of vinyl acetate-branched ethylene random copolymer is added into an alcoholysis solution composed of 80-90 parts by weight of methanol and 0.05-1 part by weight of catalyst alkali, and alcoholysis reaction is carried out at the temperature of 40-60 ℃ for 2-3 hours to obtain the modified polyvinyl alcohol capable of being melt processed.
44. The method of claim 8, wherein the method comprises:
(1) initial charge
30-100 parts of methanol, 40-120 parts of vinyl acetate monomer, 0.04-0.5 part of initiator and 4-7 parts of branched vinyl monomer, adding the branched vinyl monomer into a reaction system by adopting a step-by-step feeding mode for 0.5-2 hours, slowly heating to 40-70 ℃, polymerizing for 3-6 hours, and adding 0.08-2 parts of polymerization inhibitor after the reaction is finished, wherein the polymerization inhibitor is selected from one or a combination of more of sorbic acid, hydroquinone and thiourea;
(2) blow out the incomplete sheet
Raising the external temperature to 70-90 ℃, and removing unreacted monomers in the reaction product to obtain a resin solution of the polyvinyl acetate copolymer;
(3) dissolving and saponifying
Preparing the resin solution of the vinyl acetate-branched vinyl random copolymer into a solution with the mass fraction of 15-30% by using methanol, and adding alkali liquor for alcoholysis to obtain a product of the modified polyvinyl alcohol copolymer; the alkali liquor is a methanol solution of NaOH, the concentration of solute NaOH is 50g/L, and the molar ratio of the alkali liquor to the vinyl acetate-branched vinyl random copolymer is 0.02-0.05: 1.
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| CN108084321A (en) * | 2017-12-26 | 2018-05-29 | 广州和诚新材料科技有限公司 | A kind of modified polyvinylalcohol and preparation method thereof |
| CN108164634A (en) * | 2017-12-26 | 2018-06-15 | 广州和诚新材料科技有限公司 | Modified polyvinylalcohol and preparation method thereof |
| JP7132255B2 (en) * | 2018-02-19 | 2022-09-06 | 株式会社クラレ | Particles containing modified polyvinyl alcohol |
| CN113637098B (en) * | 2021-08-13 | 2024-03-29 | 温州医科大学 | Modified polyvinyl alcohol and preparation method and application thereof |
| CN115991845A (en) * | 2021-10-20 | 2023-04-21 | 中国石油化工股份有限公司 | Low-temperature instant polyvinyl alcohol and preparation method thereof |
| CN114014969B (en) * | 2021-11-15 | 2023-08-11 | 上海华峰新材料研发科技有限公司 | Water-soluble polymer and preparation method and application thereof |
| CN115651112A (en) * | 2022-08-13 | 2023-01-31 | 北京化工大学 | EVOH material with high hydroxyl content, preparation method and application |
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| CN102603954A (en) * | 2012-02-17 | 2012-07-25 | 四川大学 | Modified polyvinyl alcohol capable of being processed by melting and preparation method of modified polyvinyl alcohol |
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| CN102603954A (en) * | 2012-02-17 | 2012-07-25 | 四川大学 | Modified polyvinyl alcohol capable of being processed by melting and preparation method of modified polyvinyl alcohol |
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