Vinyl acetate copolymer, method for preparing the same, and use thereof

Abstract

The application provides a vinyl acetate copolymer and a preparation method and application thereof, and belongs to the technical field of polymer material preparation. The application introduces active groups such as hydroxyl groups, epoxy groups or amine groups into the polymerization molecular chain of polyvinyl acetate through a copolymerization mode, and prepares the vinyl acetate copolymer by adjusting and controlling the feeding proportion, feeding mode, reaction temperature and time, heating rate and the like. When the vinyl acetate copolymer is used as an adhesive, the active groups such as hydroxyl groups, epoxy groups and amine groups on the polymerization molecular chain can directly react with various curing agents, so that the performance of the vinyl acetate adhesive is improved, and the performance is particularly outstanding in terms of heat resistance, bonding strength and environmental protection. Meanwhile, the introduction of the active groups into the polymerization molecular chain can also reduce the additional addition of other materials containing hydroxyl groups, so that the vinyl acetate copolymer adhesive of the application has better material compatibility, and the application space of the adhesive is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material preparation, and particularly relates to a vinyl acetate copolymer and a preparation method and application thereof. BACKGROUND

[0002] Polyvinyl acetate is generally used as an emulsion type product as an adhesive, such as white latex, which is a non-toxic, odorless, non-flammable and non-explosive, environmentally friendly adhesive type that does not pollute the environment during use. As a water-based adhesive, polyvinyl acetate emulsion has the disadvantages of slow curing speed and poor water resistance, which greatly limits its application.

[0003] The curing mechanism of polyvinyl acetate emulsion adhesive has the following two ways: one is that the polyvinyl acetate adhesive in the form of emulsion is cured by film formation after the evaporation of water, and the added boric acid and other curing agents are actually additives for promoting the flocculation of polyvinyl acetate particles in the emulsion to form a film, and are not a chemical reaction type cross-linking mechanism. The other is to add a curing agent such as isocyanate for curing, and the curing mechanism of isocyanate itself is to react and cross-link with hydroxyl or amino groups to cure, and there is no group in the polymer molecular chain of polyvinyl acetate emulsion that can react with isocyanate. In fact, the curing of the curing agent such as isocyanate is achieved by reacting with the hydroxyl groups in the water or dispersant in the polyvinyl acetate emulsion.

[0004] In order to realize the reaction of polyvinyl acetate emulsion with the curing agent to form cross-linking, the copolymerization method is often used to make the polymer molecular chain in the polyvinyl acetate emulsion contain groups that can react with the curing agent. For example, patent CN101067013A discloses a polyvinyl acetate graft copolymer and a free radical / positive ion conversion polymerization method, which is to directly modify partially hydrolyzed polyvinyl acetate to obtain active hydroxyl groups to facilitate graft copolymerization. The partially hydrolyzed polyvinyl acetate used in this method is prepared by acid hydrolysis, which is relatively slow compared with alkaline hydrolysis, and the hydrolysis process is complex and difficult to control. Patent CN101121768A discloses a polyvinyl acetate copolymer emulsion, which is prepared by adding water-resistant monomer vinyl versatate during emulsion polymerization to modify vinyl acetate. This method can improve water resistance to some extent, but the glass transition temperature of vinyl versatate is less than -10 ℃, which leads to soft polyvinyl acetate film and significantly reduces the rigidity of the board in the field of artificial board. Patent CN111876099A discloses a preparation method of a formaldehyde-free strong water-resistant polyvinyl acetate wood adhesive, which uses acrylic ester monomer for copolymerization and polyvinyl alcohol as a dispersant. The wood adhesive is prepared by using 1% nitrogen propylene as a cross-linking agent, which realizes formaldehyde-free wood adhesive for splicing boards, but the performance is not significantly improved.

[0005] In summary, the polyvinyl acetate is used as an adhesive at present, either by film forming, or by the reaction of a curing agent and a dispersant / solvent with hydroxyl groups in water, or by introducing monomers such as acrylate monomers which require special curing agents to initiate crosslinking for copolymerization, none of the above methods realizes crosslinking with the polyvinyl acetate polymer body, and the environmental protection effect is not good. SUMMARY

[0006] In view of the above problems of the prior art, the present application provides a vinyl acetate copolymer, a preparation method and application thereof, which introduces active groups such as hydroxyl groups, epoxy groups or amine groups into the polymerization molecular chain of polyvinyl acetate by copolymerization, so that the curing agent can directly react with the polyvinyl acetate polymer body to produce chain extension or crosslinking, the curing speed is improved, the water resistance of polyvinyl acetate is enhanced, and the application range of polyvinyl acetate adhesives is expanded.

[0007] To achieve the above object, the specific technical scheme of the present application is as follows:

[0008] The present application provides a preparation method of a vinyl acetate copolymer, comprising the following steps:

[0009] (1) uniformly mix raw materials including 100% of the feeding amount of a solvent, 5%-50% of the feeding amount of vinyl acetate, 0-100% of the feeding amount of a comonomer, 5%-50% of the feeding amount of an initiator, and 0-100% of the feeding amount of a chain regulator; wherein the comonomer is an alkenyl monomer containing at least one functional group of a hydroxyl group, an epoxy group and an amino group;

[0010] (2) raise the temperature of the raw materials to a temperature I, and start timing after the temperature reaches the temperature I; the raw materials are reacted for 15-120 min, and the temperature is controlled to be a temperature II at the 15-120 min; the temperature II is increased by 5-45℃ based on the temperature I;

[0011] (3) drop the remaining vinyl acetate, comonomer, initiator and chain regulator into the reaction system, and control the temperature to be raised to a temperature III at the same time; the temperature III is increased by 0-60℃ based on the temperature II;

[0012] (4) after the dropping is completed, continue to react at the temperature III for a period of time, and gradually reduce the rotation speed;

[0013] (5) after the reaction is completed, cool down, discharge, and obtain the vinyl acetate copolymer.

[0014] The application introduces active groups such as hydroxyl, epoxy or amine group into the polymerization molecular chain of polyvinyl acetate by copolymerization to prepare a vinyl acetate copolymer. When the vinyl acetate copolymer is used as an adhesive, the active groups such as hydroxyl, epoxy or amine group on the polymerization molecular chain can directly react with various curing agents, thereby improving the performance of the vinyl acetate adhesive, especially in the aspects of heat resistance, bonding strength and environmental protection. Meanwhile, the introduction of the active groups into the polymerization molecular chain can also reduce the additional addition of other materials containing hydroxyl groups, so that the vinyl acetate copolymer adhesive of the application has better material compatibility. However, the introduction of the active groups such as hydroxyl, epoxy or amine group into the polymerization molecular chain often has differences in the properties of the polymerization monomers, and there are multiple reaction steps, which further leads to relatively difficult process control. Therefore, in the preparation process, the feeding ratio, feeding mode, reaction temperature and time and heating rate are adjusted to control the rate of polymerization reaction, so as to prepare the vinyl acetate copolymer with different viscosities and good comprehensive performance, and realize the wide application of the vinyl acetate copolymer resin in the field of adhesives. In addition, by adjusting the amount of the comonomer, the vinyl acetate copolymer with different functionalities can be prepared, which further expands the application space of the adhesive.

[0015] Preferably, the weight ratio of the solvent, vinyl acetate, comonomer, initiator and chain regulator is (5-200):100:(2.5-50):(0.05-0.5):(0-5).

[0016] Preferably, in step (2), the temperature I is 30-120 ℃.

[0017] Preferably, in step (3), the dropping time is 1-12 h.

[0018] Preferably, in step (4), after the dropping is completed, the reaction is continued at temperature III for 1-6 h.

[0019] Preferably, in step (5), the temperature is lowered to 40-60 ℃ for discharging.

[0020] Preferably, in step (5), after the discharging, the obtained mixture is subjected to solvent removal at 40-90 ℃ and a vacuum degree of 0.025-0.1 MPa, and then is crushed or granulated to obtain the finished vinyl acetate copolymer.

[0021] Preferably, the co-monomer includes, but is not limited to, at least one of hydroxyethyl acrylate (2-HEA), hydroxybutyl acrylate (4-HBA), hydroxypropyl acrylate (HPA), hydroxypentyl acrylate, hydroxyisopentyl acrylate, hydroxyethyl methacrylate (HEMA), hydroxybutyl methacrylate (2-HPBA), hydroxypropyl methacrylate (HPMA), hydroxypentyl methacrylate, hydroxyphenyl acrylate, hydroxyphenyl methacrylate, hydroxy-t-butyl methacrylate, trimethylolpropane monoacrylate, hydroxyethyl methacrylate phosphate, hydroxyethyl capro lactone acrylate, 4-hydroxycyclohexyl methacrylate, N-hydroxymethyl acrylamide (NMA), acrylamide, N-butoxymethyl (meth)acrylamide, ethyl-3-aminobutenoate, 3-aminopropenoate, epoxy acrylate, epoxy methacrylate, bisphenol A epoxy acrylate, 3,4-epoxycyclohexylmethyl isobutenoate, epoxy propylene oleyl acrylate.

[0022] Preferably, the solvent includes, but is not limited to, at least one of isopropyl alcohol, methanol, ethanol, n-butanol, acetone, ethyl acetate, methyl acetate, butyl acetate, benzene, toluene, chloroform, carbon tetrachloride.

[0023] Preferably, the initiator includes, but is not limited to, at least one of azobisisobutyronitrile (AIBN), azobisisoheptyl nitrile (ABVN), benzoyl peroxide (BPO), di(3,5,6-trimethylhexanoyl) peroxide, t-butyl peroxypivalate, cumyl phenylperoxypivalate, t-butyl peroxypivalate, di(2-ethylhexyl) peroxydicarbonate, dimethyl azobisbutyrate, azoisobutyrylformamide, t-butyl benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-t-butyl peroxide.

[0024] Preferably, the chain regulator includes, but is not limited to, a chain transfer agent and / or a chain extender; wherein the chain transfer agent includes, but is not limited to, at least one of dimercaptoethanol, methyl mercaptan, ethyl mercaptan, acetaldehyde, dodecyl mercaptan, carbon tetrachloride, dichloromethane, n-butyl mercaptan, octyl mercaptan; the chain extender includes, but is not limited to, at least one of ethylenediamine (EDA), N-isopropylethylenediamine (IPEDA), triethylenetetramine (TETA), diethylenetriamine (DETA), diphenylmethane diisocyanate (MDI), dimethylthiolutidine diamine (DMTDA), 1,4-butanediol (BDO), neopentyl glycol (NPG), sorbitol, diethylene glycol (DEG), triethylene glycol, trimethylolpropane (TMP), diethylaminoethanol (DEAE), N,N-dihydroxy(diisopropyl)aniline (HPA).

[0025] The present application also provides a vinyl acetate copolymer prepared by the method.

[0026] The application also provides application of the vinyl acetate copolymer in the field of adhesives.

[0027] Compared with the prior art, the application has the advantages that:

[0028] The vinyl acetate copolymer obtained by copolymerization of the alkenyl monomer with hydroxyl, epoxy, amino and other active groups and vinyl acetate has a stronger functional group in the bulk polymerization molecular chain, is more likely to directly react with various curing agents, improves the comprehensive performance of the vinyl acetate adhesive, realizes the wide application of the vinyl acetate copolymer resin in the field of adhesives, and further expands the application field of the adhesive by regulating the amount of the copolymerization monomer. Specifically, the application of the vinyl acetate copolymer in the PUR (moisture-curing reaction type polyurethane hot melt adhesive) adhesive has the following advantages:

[0029] (1) Improved compatibility and chemical crosslinking with PUR

[0030] The hydroxyl, epoxy, amino and other active groups introduced in the vinyl acetate copolymer can chemically react with the isocyanate groups (-NCO) in the PUR to form stable urethane bonds. The chemical crosslinking significantly improves the compatibility of the vinyl acetate copolymer with the PUR, enhances the interfacial bonding force of the two, and thus improves the bonding strength and durability of the overall adhesive. For example, in a composite material, the vinyl acetate copolymer of the application as an intermediate layer can effectively bridge the PUR and the substrate, reducing the interfacial defects.

[0031] (2) Improved thermal stability and hydrolysis resistance

[0032] The vinyl acetate copolymer of the application can optimize the thermal performance of the vinyl acetate copolymer adhesive, specifically, the glass transition temperature (Tg) of the vinyl acetate copolymer emulsion adhesive is reduced, and the thermal stability is improved, which is due to the three-dimensional network structure formed by the crosslinking of the hydroxyl, epoxy, amino and other active groups with the PUR, reducing the creep and degradation at high temperature. In addition, the crosslinking structure generated by the reaction of the hydroxyl, epoxy, amino and other active groups with the PUR can also enhance the hydrolysis resistance, reduce the influence of environmental humidity on the adhesive layer, and is suitable for applications in humid or high-temperature environments.

[0033] (3) Optimized mechanical properties

[0034] The vinyl acetate copolymer of the present application can improve the flexibility and impact resistance of the adhesive by adjusting the ratio of soft and hard segments. For example, when the vinyl acetate copolymer is grafted with polyurethane derivative macromonomer, the increase of the comonomer reduces the rigidity of the system, making the adhesive layer have better ductility while maintaining high peel strength. This property is particularly suitable for scenarios that require resistance to repeated stress, such as automotive interiors or electronic component packaging.

[0035] (4) Reducing the viscosity of the system and improving the processing performance

[0036] The vinyl acetate copolymer of the present application has good hydrophilicity and dispersibility, which can reduce the viscosity of the PUR adhesive in the high-temperature molten state and improve the uniformity of the coating and spraying process. This property is particularly important in automated production lines, which can improve production efficiency and reduce energy consumption.

[0037] (5) Environmental friendliness and multifunctionality

[0038] The vinyl acetate copolymer of the present application, as a component of water-based adhesive, can reduce the VOCs emission of traditional solvent-based adhesives, which meets the environmental protection trend. At the same time, its composite system with PUR can balance high bonding strength and low curing temperature, which is suitable for fields with strict requirements on environmental protection and process conditions, such as furniture manufacturing and electronic packaging. DETAILED DESCRIPTION

[0039] The technical solutions of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] The present application provides a preparation method of a vinyl acetate copolymer, comprising the following steps:

[0041] (1) uniformly mix raw materials including 100% of the feeding amount of solvent, 5%-50% of the feeding amount of vinyl acetate, 0-100% of the feeding amount of comonomer, 5%-50% of the feeding amount of initiator, and 0-100% of the feeding amount of chain regulator; wherein the comonomer is an alkenyl monomer containing at least one functional group of hydroxyl, epoxy, and amino;

[0042] (2) raise the material temperature to temperature I, and start timing after the temperature reaches temperature I. React the raw materials for 15-120 min, while controlling the material temperature to be temperature II at the 15-120 min; the temperature II is: 5-45℃ higher than temperature I;

[0043] (3) the rest of the vinyl acetate, comonomer, initiator, chain regulator are added dropwise into the reaction system, and the temperature of the material is controlled to increase to temperature III at the same time of dropping; the temperature III is: increased by 0-60 ℃ on the basis of temperature II;

[0044] (4) after the dropping is completed, continue to react at temperature III for a period of time, and gradually reduce the rotating speed;

[0045] (5) after the reaction is completed, reduce the temperature, discharge, and obtain the vinyl acetate copolymer.

[0046] In some examples, the weight ratio of the solvent, vinyl acetate, comonomer, initiator, chain regulator is (5-200): 100: (2.5-50): (0.05-0.5): (0-5).

[0047] In some examples, in step (2), the temperature I is 30-120 ℃.

[0048] In some examples, in step (3), the dropping time is 1-12 h.

[0049] In some examples, in step (4), after the dropping is completed, continue to react at temperature III for 1-6 h.

[0050] In some examples, in step (5), the temperature is reduced to 40-60 ℃ for discharging.

[0051] In some examples, in step (5), after discharging, the obtained mixture is subjected to solvent removal at 40-90 ℃ and 0.025-0.1 MPa vacuum degree, and is crushed or granulated to obtain the finished product of the vinyl acetate copolymer.

[0052] In some examples, the comonomer includes but is not limited to at least one of hydroxyethyl acrylate (2-HEA), hydroxybutyl acrylate (4-HBA), hydroxypropyl acrylate (HPA), hydroxyamyl acrylate, hydroxyisopentyl acrylate, hydroxyethyl methacrylate (HEMA), hydroxybutyl methacrylate (2-HPBA), hydroxypropyl methacrylate (HPMA), hydroxyamyl methacrylate, hydroxyphenyl acrylate, hydroxyphenyl methacrylate, hydroxy-t-butyl methacrylate, trimethylolpropane monoacrylate, hydroxyethyl methacrylate phosphate, hydroxyethyl caprolactone acrylate, 4-hydroxycyclohexyl methacrylate, N-hydroxymethyl acrylamide (NMA), acrylamide, N-butoxymethyl (meth) acrylamide, ethyl-3-aminobutenoate, 3-aminopropenoate, epoxy acrylate, epoxy methacrylate, bisphenol A epoxy acrylate, 3,4-epoxycyclohexylmethyl methacrylate, epoxy propylene oleic acid ester.

[0053] In some examples, the solvent includes, but is not limited to, at least one of isopropyl alcohol, methanol, ethanol, n-butyl alcohol, acetone, ethyl acetate, methyl acetate, butyl acetate, benzene, toluene, chloroform, carbon tetrachloride.

[0054] In some examples, the initiator includes, but is not limited to, at least one of azobisisobutyronitrile (AIBN), azobisisoheptyl nitrile (ABVN), benzoyl peroxide (BPO), di(3,5,6-trimethylhexanoyl) peroxide, tert-butyl peroxypivalate, cumyl phenylperoxide, tert-butyl peroxypivalate, di(2-ethylhexyl) peroxydicarbonate, dimethyl azobis isobutyrate, azobis isobutyryl cyanamide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-tert-butyl peroxide.

[0055] In some examples, the chain regulator includes, but is not limited to, at least one of a chain transfer agent and / or a chain extender; wherein the chain transfer agent includes, but is not limited to, at least one of dimercaptoethanol, methyl mercaptan, ethyl mercaptan, acetaldehyde, dodecyl mercaptan, carbon tetrachloride, dichloromethane, n-butyl mercaptan, octyl mercaptan; and the chain extender includes, but is not limited to, at least one of ethylenediamine (EDA), N-isopropyl ethylenediamine (IPEDA), triethylenetetramine (TETA), diethylenetriamine (DETA), diphenylmethane diisocyanate (MDI), dimethylthio toluene diamine (DMTDA), 1,4-butanediol (BDO), neopentyl glycol (NPG), sorbitol, diethylene glycol (DEG), triethylene glycol, trimethylolpropane (TMP), diethylaminoethanol (DEAE), N,N-dihydroxy(diisopropyl)aniline (HPA).

[0056] In the following specific examples, the raw materials or reagents used are commercially available unless otherwise specified.

[0057] Example 1

[0058] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:1.

[0059] The preparation method comprises the following steps:

[0060] (a) Start the stirring of the already deoxygenated reactor, and add 100% of the amount of isopropyl alcohol, 15% of the amount of vinyl acetate, 0% of the amount of hydroxybutyl acrylate, 15% of the amount of azobisisobutyronitrile, and 15% of the amount of mercaptoethanol into the closed polymerization reactor;

[0061] (b) the temperature of the material is raised to 63°C under stirring, and the reaction of the raw materials is started after the temperature reaches 63°C, and the temperature is controlled to be 75°C at the 17th minute (the temperature is maintained at 75°C for the remaining 13 minutes) ;

[0062] (c) the remaining vinyl acetate, butyl hydroxy acrylate, azobisisobutyronitrile and mercaptoethanol are added to the reaction system at a constant speed, and the temperature of the material is raised to 84°C at the same time, and the dropping time is controlled to be 4 hours; and the temperature of the material is stabilized at 84°C after the temperature reaches 84°C;

[0063] (d) after the dropping is completed, the reaction is continued at 84°C for 4 hours, and the rotating speed is gradually reduced to 150 rpm;

[0064] (e) after the reaction is completed, the temperature is reduced to 50°C, and the material is discharged;

[0065] (f) after the solvent is removed at 85°C and a vacuum degree of 0.1 MPa, the vinyl acetate copolymer product is obtained by crushing.

[0066] The obtained vinyl acetate copolymer product is tested for conversion rate, 120°C melt viscosity, GPC value, K value and hydroxyl functionality, and the test results are shown in Table 1.

[0067] Example 2

[0068] A vinyl acetate copolymer, the weight ratio of the raw material solvent, vinyl acetate, comonomer, initiator and chain regulator is 20:100:6.25:0.2:2.5.

[0069] The preparation method comprises the following steps:

[0070] (a) the stirring of the deoxygenated reaction kettle is started, and 100% of the isopropyl alcohol, 15% of the vinyl acetate, 0% of the butyl hydroxy acrylate, 15% of the azobisisobutyronitrile and 15% of the mercaptoethanol are added to the closed polymerization reaction kettle;

[0071] (b) the temperature of the material is raised to 62.4°C under stirring, and the reaction of the raw materials is started after the temperature reaches 62.4°C, and the temperature is controlled to be 75°C at the 17th minute (the temperature is maintained at 75°C for the remaining 13 minutes) ;

[0072] (c) the remaining vinyl acetate, butyl hydroxy acrylate, azobisisobutyronitrile and mercaptoethanol are added to the reaction system at a constant speed, and the temperature of the material is raised to 84°C at the same time, and the dropping time is controlled to be 4 hours; and the temperature of the material is stabilized at 84°C after the temperature reaches 84°C;

[0073] (d) after the completion of dropping, continue to react at 84 ℃ for 4 h, and gradually reduce the rotation speed to 150 rpm;

[0074] (e) after the reaction is completed, cool down to 50 ℃ to discharge;

[0075] (f) after removing the solvent at 85 ℃ and 0.1 MPa vacuum degree, crush to obtain the finished product of vinyl acetate copolymer.

[0076] The finished product of vinyl acetate copolymer is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality test, and the test results are shown in Table 1.

[0077] Example 3

[0078] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator is 20:100:15:0.175:1.

[0079] The preparation method comprises the following steps:

[0080] (a) start stirring the reaction kettle which has been deoxygenated, and add 100% of the isopropyl alcohol, 15% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 15% of the azobisisobutyronitrile, and 15% of the mercaptoethanol into the closed polymerization reaction kettle;

[0081] (b) under stirring, warm the material to 63 ℃, and start timing after the temperature reaches 63 ℃, and the raw materials are reacted for 30 min, while the material temperature is controlled to be 75 ℃ at the 27th min (and the material temperature is maintained at 75 ℃ for the remaining 3 min to react);

[0082] (c) uniformly drop the remaining vinyl acetate, butyl hydroxy acrylate, azobisisobutyronitrile, and mercaptoethanol into the reaction system, and start controlling the material temperature to be warmed to 84 ℃ at the same time, and the dropping time is controlled to be 4 h; and after the material temperature reaches 84 ℃, the material temperature in the dropping process is stabilized to be 84 ℃;

[0083] (d) after the completion of dropping, continue to react at 84 ℃ for 4 h, and gradually reduce the rotation speed to 150 rpm;

[0084] (e) after the reaction is completed, cool down to 50 ℃ to discharge;

[0085] (f) after removing the solvent at 88 ℃ and 0.06 MPa vacuum degree, crush to obtain the finished product of vinyl acetate copolymer.

[0086] The finished product of vinyl acetate copolymer is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality test, and the test results are shown in Table 1.

[0087] Example 4

[0088] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:9.25:0.175:1.

[0089] The preparation method comprises the following steps:

[0090] (a) open the stirring of the oxygen removal reactor, add 100% of the isopropyl alcohol, 15% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 15% of the azobisisobutyronitrile, and 15% of the mercaptoethanol into the closed polymerization reactor;

[0091] (b) under stirring, the temperature is raised to 63 ℃, and when the temperature reaches 63 ℃, the timer starts, and the raw materials are reacted for 30 min, while the temperature is controlled to be 73 ℃ at the 27th min (the remaining 3 min, the temperature is maintained at 73 ℃ for reaction) ;

[0092] (c) the remaining vinyl acetate, butyl hydroxyacrylate, azobisisobutyronitrile, and mercaptoethanol are added to the reaction system at a constant speed, and at the same time, the temperature is controlled to be raised to 84 ℃, and the dropping time is controlled to be 4 h; after the temperature reaches 84 ℃, the temperature of the dropping process is stabilized at 84 ℃;

[0093] (d) after the dropping is completed, continue to react at 84 ℃ for 4 h, and gradually reduce the rotating speed to 150 rpm;

[0094] (e) after the reaction is completed, the temperature is lowered to 50 ℃, and the material is discharged;

[0095] (f) after removing the solvent at 85 ℃ and 0.1 MPa vacuum degree, crushing to obtain the vinyl acetate copolymer product.

[0096] The obtained vinyl acetate copolymer product is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0097] Example 5

[0098] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:1.

[0099] The preparation method comprises the following steps:

[0100] (a) Start stirring of the already deoxygenated reactor, add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxy butyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reactor;

[0101] (b) Stir the material to a temperature of 63°C, and then start timing when the temperature reaches 63°C. React the material for 60 minutes while controlling the temperature to be 75°C at the 60 minute mark (when the temperature reaches 75°C, proceed to the next step);

[0102] (c) Add the remaining vinyl acetate, hydroxy butyl acrylate, azobisisobutyronitrile, and mercaptoethanol to the reaction system at a constant rate while controlling the temperature to increase to 84°C. The temperature should be stable at 84°C after the temperature reaches 84°C;

[0103] (d) After the addition is complete, continue to react at 84°C for 4 hours while gradually reducing the stirring speed to 150 rpm;

[0104] (e) After the reaction is complete, cool the material to 50°C and discharge the material;

[0105] (f) After removing the solvent at 85°C and 0.1 MPa vacuum, crush the material to obtain the final vinyl acetate copolymer product.

[0106] Test the conversion rate, 120°C melt viscosity, GPC value, K value, and hydroxyl functionality of the final vinyl acetate copolymer product. The test results are shown in Table 1.

[0107] Example 6

[0108] A vinyl acetate copolymer has a weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator of 20:100:18:0.175:1.

[0109] The preparation method includes the following steps:

[0110] (a) Start stirring of the already deoxygenated reactor, add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxy butyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reactor;

[0111] (b) Stir the material to a temperature of 63°C, and then start timing when the temperature reaches 63°C. React the material for 45 minutes while controlling the temperature to be 73°C at the 30 minute mark (for the remaining 15 minutes, maintain the temperature at 73°C to react);

[0112] (c) the remaining vinyl acetate, hydroxybutyl acrylate, azobisisobutyronitrile, mercaptoethanol are added to the reaction system at a constant speed, and at the same time the temperature is controlled to rise to 84 ℃, and the dropping time is controlled to be 4 h; after the temperature reaches 84 ℃, the temperature in the dropping process is stabilized at 84 ℃;

[0113] (d) after the dropping is completed, continue to react at 84 ℃ for 4 h, and gradually reduce the rotating speed to 150 rpm;

[0114] (e) after the reaction is completed, cool to 50 ℃ and discharge;

[0115] (f) after the solvent is removed at 85 ℃ and 0.1 MPa vacuum, crush to obtain the vinyl acetate copolymer product.

[0116] The obtained vinyl acetate copolymer product is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality tests, and the test results are shown in Table 1.

[0117] Example 7

[0118] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:2.

[0119] The preparation method comprises the following steps:

[0120] (a) start the stirring of the already deoxygenated reaction kettle, and add 100% of the isopropyl alcohol, 12% of the vinyl acetate, 0% of the hydroxybutyl acrylate, 12% of the azobisisobutyronitrile, and 24% of the mercaptoethanol into the closed polymerization reaction kettle;

[0121] (b) under stirring, the temperature is raised to 62 ℃, and after the temperature reaches 62 ℃, the timer is started, and the raw materials are reacted for 30 min, while the temperature is controlled to be 73 ℃ at the 17th min (the remaining 13 min, the temperature is maintained at 73 ℃ for reaction);

[0122] (c) the remaining vinyl acetate, hydroxybutyl acrylate, benzoyl peroxide, and mercaptoethanol are added to the reaction system at a constant speed, and at the same time the temperature is controlled to rise to 86 ℃, and the dropping time is controlled to be 4 h; after the temperature reaches 86 ℃, the temperature in the dropping process is stabilized at 86 ℃;

[0123] (d) after the dropping is completed, continue to react at 86 ℃ for 4 h, and gradually reduce the rotating speed to 150 rpm;

[0124] (e) after the reaction is completed, cool to 50 ℃ and discharge;

[0125] (f) after removing the solvent at 70 ℃, 0.05 MPa vacuum, crushing to obtain the vinyl acetate copolymer product.

[0126] The obtained vinyl acetate copolymer product is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0127] Example 8

[0128] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:10:0.125:0.

[0129] The preparation method comprises the following steps:

[0130] (a) Start stirring the reaction kettle which has been deoxygenated, and add 100% of the isopropyl alcohol, 12% of the vinyl acetate, 5% of the hydroxybutyl acrylate, and 12% of the azobisisobutyronitrile into the sealed polymerization reaction kettle;

[0131] (b) While stirring, raise the temperature of the material to 63 ℃, and start timing when the temperature reaches 63 ℃. React the raw materials for 45 min, and control the temperature of the material to be 75 ℃ at the 25th min (for the remaining 20 min, maintain the temperature of the material at 75 ℃ for reaction);

[0132] (c) Uniformly add the remaining vinyl acetate, hydroxybutyl acrylate, and azobisisobutyronitrile to the reaction system, and start controlling the temperature of the material to be raised to 84 ℃ at the same time. The dropping time is controlled to be 4 h; and after the temperature of the material reaches 84 ℃, stabilize the temperature of the material to be 84 ℃ during the dropping process;

[0133] (d) After the dropping is completed, continue to react at 84 ℃ for 3 h, and gradually reduce the rotation speed to 50 rpm;

[0134] (e) After the reaction is completed, cool to 50 ℃ to discharge the material;

[0135] (f) after removing the solvent at 85 ℃, 0.1 MPa vacuum, crushing to obtain the vinyl acetate copolymer product.

[0136] The obtained vinyl acetate copolymer product is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0137] Example 9

[0138] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:1.

[0139] The preparation method comprises the following steps:

[0140] (a) Start stirring of the oxygen-removed reaction kettle, and add 100% of the feeding amount of methanol, 15% of the feeding amount of vinyl acetate, 0% of the feeding amount of hydroxy butyl acrylate, 15% of the feeding amount of azobisisobutyronitrile and 15% of the feeding amount of mercaptoethanol into the closed polymerization reaction kettle;

[0141] (b) The temperature is increased to 63 DEG C under stirring, and the reaction is started to be recorded at 63 DEG C, and the raw materials are reacted for 45 min, and the temperature is controlled to be 75 DEG C at the 30th min (and the temperature is maintained at 75 DEG C for the remaining 15 min);

[0142] (c) The remaining vinyl acetate, hydroxy butyl acrylate, azobisisobutyronitrile and mercaptoethanol are added into the reaction system at a constant speed, and the temperature is controlled to be increased to 80 DEG C at the same time, and the dropping time is controlled to be 6 h; and after the temperature reaches 80 DEG C, the temperature of the dropping process is stabilized at 80 DEG C;

[0143] (d) After the dropping is completed, the reaction is continued at 80 DEG C for 4 h, and the rotating speed is gradually reduced to 50 rpm;

[0144] (e) After the reaction is completed, the temperature is decreased to 50 DEG C to discharge the materials;

[0145] (f) After the solvent is removed at 68 DEG C and 0.06 MPa vacuum degree, the vinyl acetate copolymer product is obtained by crushing.

[0146] The obtained vinyl acetate copolymer product is tested in terms of conversion rate, 120 DEG C melt viscosity, GPC value, K value and hydroxyl functionality, and the test results are shown in Table 1.

[0147] Example 10

[0148] A vinyl acetate copolymer, and the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator and chain regulator is 20:100:8.15:0.175:1.

[0149] The preparation method comprises the following steps:

[0150] (a) Start stirring of the oxygen-removed reaction kettle, and add 100% of the feeding amount of methanol, 15% of the feeding amount of vinyl acetate, 0% of the feeding amount of hydroxy butyl acrylate, 15% of the feeding amount of azobisisobutyronitrile and 15% of the feeding amount of mercaptoethanol into the closed polymerization reaction kettle;

[0151] (b) the temperature of the material is raised to 62°C under stirring, and after the temperature reaches 62°C, the reaction of the raw materials is started and controlled for 30 minutes, and at the 22nd minute, the temperature of the material is controlled to be 73°C (for the remaining 8 minutes, the temperature of the material is maintained at 73°C for reaction);

[0152] (c) the remaining vinyl acetate, butyl hydroxy acrylate and azobisisobutyronitrile are added to the reaction system at a constant speed, and at the same time, the temperature of the material is controlled to be raised to 84°C, and the dropping time is controlled to be 4 hours; after the temperature of the material reaches 84°C, the temperature of the material in the dropping process is stabilized at 84°C;

[0153] (d) after the dropping is completed, the reaction is continued at 84°C for 4 hours, and the rotating speed is gradually reduced to 50 rpm;

[0154] (e) after the reaction is completed, the temperature is lowered to 50°C for discharging;

[0155] (f) after the solvent is removed at 85°C and a vacuum degree of 0.06 MPa, the vinyl acetate copolymer product is obtained by crushing.

[0156] The obtained vinyl acetate copolymer product is tested for conversion rate, 120°C melt viscosity, GPC value, K value and hydroxyl functionality, and the test results are shown in Table 1.

[0157] Example 11

[0158] A vinyl acetate copolymer, the weight ratio of the raw material solvent, vinyl acetate, comonomer, initiator and chain regulator is 25:100:8.175:0.15:1.8.

[0159] The preparation method comprises the following steps:

[0160] (a) the stirring of the deoxygenated reaction kettle is started, and 100% of the isopropyl alcohol, 15% of the vinyl acetate, 0% of the butyl hydroxy acrylate, 15% of the azobisisobutyronitrile and 25% of the dodecyl mercaptan are added to the closed polymerization reaction kettle;

[0161] (b) the temperature of the material is raised to 62°C under stirring, and after the temperature reaches 62°C, the reaction of the raw materials is started and controlled for 30 minutes, and at the 30th minute, the temperature of the material is controlled to be 73°C (after the temperature of the material reaches 73°C, the next step is performed);

[0162] (c) the remaining vinyl acetate, butyl hydroxy acrylate, azobisisobutyronitrile and dodecyl mercaptan are added to the reaction system at a constant speed, and at the same time, the temperature of the material is controlled to be raised to 84°C, and the dropping time is controlled to be 8 hours; after the temperature of the material reaches 84°C, the temperature of the material in the dropping process is stabilized at 84°C;

[0163] (d) after the completion of dropping, continue to react at 84 ℃ for 4 h, and gradually reduce the rotation speed to 50 rpm;

[0164] (e) after the reaction is completed, cool down to 50 ℃ to discharge;

[0165] (f) after removing the solvent at 85 ℃ and 0.08 MPa vacuum degree, crush to obtain the finished product of vinyl acetate copolymer.

[0166] The finished product of vinyl acetate copolymer is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality test, and the test results are shown in Table 1.

[0167] Example 12

[0168] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator is 20:100:8.175:0.175:1.

[0169] The preparation method comprises the following steps:

[0170] (a) start stirring the reaction kettle which has been deoxygenated, and add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the 3-amino acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reaction kettle;

[0171] (b) under stirring, warm the material to 63 ℃, and start timing after the temperature reaches 63 ℃, and the raw materials are reacted for 30 min, while the material temperature is controlled to be 73 ℃ at the 30th min (the material temperature reaches 73 ℃, and the next step is performed);

[0172] (c) drop the remaining vinyl acetate, 3-amino acrylate, azobisisobutyronitrile, and mercaptoethanol into the reaction system at a constant speed, and start controlling the material temperature to be warmed to 84 ℃ at the same time, and the dropping time is controlled to be 4 h; after the material temperature reaches 84 ℃, the material temperature in the dropping process is stabilized to be 84 ℃;

[0173] (d) after the completion of dropping, continue to react at 84 ℃ for 4 h, and gradually reduce the rotation speed to 150 rpm;

[0174] (e) after the reaction is completed, cool down to 50 ℃ to discharge;

[0175] (f) after removing the solvent at 85 ℃ and 0.1 MPa vacuum degree, crush to obtain the finished product of vinyl acetate copolymer.

[0176] The finished product of vinyl acetate copolymer is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality test, and the test results are shown in Table 1.

[0177] Example 13

[0178] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.2:1.

[0179] The preparation method comprises the following steps:

[0180] (a) open the stirring of the oxygen removal reactor, add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the epoxy acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reactor;

[0181] (b) under stirring, the temperature is raised to 63 ℃, and when the temperature reaches 63 ℃, the timer starts, and the raw materials are reacted for 30 min, while the temperature is controlled to be 75 ℃ at the 25th min (the remaining 5 min, the temperature is maintained at 75 ℃ for reaction);

[0182] (c) the remaining vinyl acetate, epoxy acrylate, azobisisobutyronitrile, and mercaptoethanol are added to the reaction system at a constant speed, and at the same time, the temperature is controlled to be raised to 84 ℃, and the dropping time is controlled to be 4 h; after the temperature reaches 84 ℃, the temperature of the dropping process is stabilized at 84 ℃;

[0183] (d) after the dropping is completed, continue to react at 84 ℃ for 4 h, and gradually reduce the rotating speed to 150 rpm;

[0184] (e) after the reaction is completed, the temperature is lowered to 50 ℃, and the material is discharged;

[0185] (f) after removing the solvent at 85 ℃ and 0.1 MPa vacuum degree, crushing to obtain the vinyl acetate copolymer finished product.

[0186] The obtained vinyl acetate copolymer finished product is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0187] Example 14

[0188] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.2:1.

[0189] The preparation method comprises the following steps:

[0190] (a) Start stirring of the already deoxygenated reactor, add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reactor;

[0191] (b) Stir the material to a temperature of 63°C, and then start timing when the temperature reaches 63°C. React the material for 30 minutes while controlling the temperature to 75°C at the 30 minute mark (when the temperature reaches 75°C, proceed to the next step);

[0192] (c) Add the remaining vinyl acetate, hydroxyethyl acrylate, azobisisobutyronitrile, and mercaptoethanol to the reaction system at a constant rate. At the same time, start controlling the temperature to rise to 84°C. The addition time is controlled to be 4 hours. When the temperature reaches 84°C, stabilize the temperature of the material to 84°C;

[0193] (d) After the addition is complete, continue to react at 84°C for 4 hours, and gradually reduce the rotation speed to 150 rpm;

[0194] (e) After the reaction is complete, cool to 50°C and discharge the material;

[0195] (f) After removing the solvent at 85°C and a vacuum of 0.1 MPa, crush to obtain the finished vinyl acetate copolymer product.

[0196] Test the conversion rate, 120°C melt viscosity, GPC value, K value, and hydroxyl functionality of the obtained vinyl acetate copolymer product. The test results are shown in Table 1.

[0197] Example 15

[0198] A vinyl acetate copolymer, the weight ratio of the raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator is 20:100:8.15:0.15:1.

[0199] The preparation method comprises the following steps:

[0200] (a) Start stirring of the already deoxygenated reactor, add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reactor;

[0201] (b) Stir the material to a temperature of 63°C, and then start timing when the temperature reaches 63°C. React the material for 30 minutes while controlling the temperature to 75°C at the 30 minute mark (when the temperature reaches 75°C, proceed to the next step);

[0202] (c) the remaining vinyl acetate, hydroxyethyl acrylate, azobisisobutyronitrile are added to the reaction system at a constant speed, and at the same time the temperature is controlled to rise to 78°C, and the dropping time is controlled to be 6 hours; after the temperature reaches 78°C, the temperature in the dropping process is stabilized at 78°C;

[0203] (d) after the dropping is completed, continue to react at 78°C for 6 hours, and gradually reduce the speed to 150 rpm;

[0204] (e) after the reaction is completed, cool to 50°C and discharge;

[0205] (f) after removing the solvent at 85°C and 0.1 MPa vacuum, crushing to obtain the finished product of vinyl acetate copolymer.

[0206] The finished product of vinyl acetate copolymer is tested for conversion rate, 120°C melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0207] Example 16

[0208] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 10:100:8.15:0.175:1.

[0209] The preparation method comprises the following steps:

[0210] (a) start the stirring of the already deoxygenated reaction kettle, and add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the closed polymerization reaction kettle;

[0211] (b) under stirring, the temperature is raised to 63°C, and after the temperature reaches 63°C, the timer is started, and the raw materials are reacted for 30 minutes, while controlling the temperature to be 75°C at the 30th minute (the temperature reaches 75°C, and the next step is performed);

[0212] (c) the remaining vinyl acetate, hydroxyethyl acrylate, azobisisobutyronitrile, and mercaptoethanol are added to the reaction system at a constant speed, and at the same time the temperature is controlled to rise to 78°C, and the dropping time is controlled to be 4 hours; after the temperature reaches 78°C, the temperature in the dropping process is stabilized at 78°C;

[0213] (d) after the dropping is completed, continue to react at 78°C for 4 hours, and gradually reduce the speed to 150 rpm;

[0214] (e) after the reaction is completed, cool to 50°C and discharge;

[0215] (f) after removing the solvent at 85 ℃, 0.08 MPa vacuum degree, crushing to obtain the finished product of vinyl acetate copolymer.

[0216] The finished product of vinyl acetate copolymer is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0217] Example 17

[0218] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:1.

[0219] The preparation method comprises the following steps:

[0220] (a) Start stirring the reaction kettle which has been deoxygenated, and add 100% of the isopropyl alcohol, 14% of the vinyl acetate, 0% of the hydroxyethyl acrylate, 14% of the azobisisobutyronitrile, and 14% of the mercaptoethanol into the sealed polymerization reaction kettle;

[0221] (b) While stirring, raise the temperature of the material to 63 ℃, and start timing when the temperature reaches 63 ℃. React the raw materials for 30 min, and control the temperature of the material to be 75 ℃ at the 30th min (the temperature of the material reaches 75 ℃, and the next step is performed);

[0222] (c) Add the remaining vinyl acetate, hydroxyethyl acrylate, azobisisobutyronitrile, and mercaptoethanol to the reaction system at a constant speed, and start controlling the temperature of the material to be raised to 84 ℃ at the same time. The dropping time is controlled to be 4 h; and after the temperature of the material reaches 84 ℃, the temperature of the material during the dropping process is stabilized at 84 ℃;

[0223] (d) After the dropping is completed, continue to react at 84 ℃ for 2 h, and gradually reduce the rotation speed to 150 rpm;

[0224] (e) After the reaction is completed, cool to 50 ℃, and discharge the material;

[0225] (f) after removing the solvent at 85 ℃, 0.1 MPa vacuum degree, crushing to obtain the finished product of vinyl acetate copolymer.

[0226] The finished product of vinyl acetate copolymer is tested for conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality, and the test results are shown in Table 1.

[0227] Example 18

[0228] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, chain regulator is 20:100:8.15:0.175:1.

[0229] The preparation method comprises the following steps:

[0230] (a) Start stirring of the oxygen-removed reaction kettle, and add 100% of the feeding amount of isopropyl alcohol, 14% of the feeding amount of vinyl acetate, 0% of the feeding amount of hydroxy ethyl acrylate, 14% of the feeding amount of azobisisobutyronitrile, and 100% of the feeding amount of mercaptoethanol into the polymerization reaction kettle;

[0231] (b) Warm the material to 63 DEG C under stirring, and start timing when the temperature reaches 63 DEG C; the raw materials are reacted for 30 min, and the material temperature is controlled to be 75 DEG C at the 30th min (the material temperature reaches 75 DEG C, and the next step is performed);

[0232] (c) Uniformly add the remaining vinyl acetate, hydroxy ethyl acrylate and azobisisobutyronitrile into the reaction system, and start controlling the material temperature to be warmed to 84 DEG C at the same time; the dropping time is controlled to be 6 h; and when the material temperature reaches 84 DEG C, the material temperature in the dropping process is stabilized to be 84 DEG C;

[0233] (d) After the dropping is completed, the reaction is continued at 84 DEG C for 4 h, and the rotating speed is gradually reduced to 150 rpm;

[0234] (e) After the reaction is completed, the temperature is reduced to 50 DEG C, and the material is discharged;

[0235] (f) After the solvent is removed at 85 DEG C and 0.1 MPa vacuum degree, the vinyl acetate copolymer product is obtained by crushing.

[0236] The obtained vinyl acetate copolymer product is tested in terms of conversion rate, 120 DEG C melt viscosity, GPC value, K value and hydroxyl functionality, and the test results are shown in Table 1.

[0237] Comparative Example 1

[0238] A vinyl acetate copolymer, and the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator and chain regulator is 20:100:8.15:0.175:1.

[0239] The preparation method comprises the following steps:

[0240] (a) Start stirring of the oxygen-removed reaction kettle, and add 100% of the feeding amount of isopropyl alcohol, 14% of the feeding amount of vinyl acetate, 0% of the feeding amount of hydroxy ethyl acrylate, 14% of the feeding amount of azobisisobutyronitrile, and 100% of the feeding amount of mercaptoethanol into the polymerization reaction kettle;

[0241] (b) Warm the material to 63 DEG C under stirring, and start timing when the temperature reaches 63 DEG C; the raw materials are reacted for 30 min, and the material temperature is controlled to be 75 DEG C at the 30th min (the material temperature reaches 75 DEG C, and the next step is performed);

[0242] (c) the remaining vinyl acetate, butyl hydroxy acrylate, azobisisobutyronitrile and mercaptoethanol are added to the reaction system at a constant speed, and at the same time, the temperature is controlled to rise to 80°C, and the dropping time is controlled to be 6 h; after the temperature reaches 80°C, the temperature in the dropping process is stabilized at 80°C;

[0243] (d) after the dropping is completed, the reaction is continued at 80°C for 4 h, and the rotating speed is gradually reduced to 50 rpm;

[0244] (e) after the reaction is completed, the temperature is reduced to 50°C to discharge the material;

[0245] (f) after the solvent is removed at 68°C and a vacuum degree of 0.06 MPa, the product of vinyl acetate copolymer is obtained by crushing.

[0246] The product of vinyl acetate copolymer is tested for conversion rate, 120°C melt viscosity, GPC value, K value and hydroxyl functionality, and the test results are shown in Table 1.

[0247] Comparative Example 2

[0248] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator and chain regulator is 20:100:0:0.175:1.

[0249] The preparation method comprises the following steps:

[0250] (a) the stirring of the already deoxygenated reaction kettle is started, and 100% of the methanol, 15% of the vinyl acetate, 15% of the azobisisobutyronitrile and 15% of the mercaptoethanol are added to the closed polymerization reaction kettle;

[0251] (b) the temperature is raised to 63°C under stirring, and after the temperature reaches 63°C, the timer is started, and the raw materials are reacted for 45 min, and at the same time, the temperature is controlled to be 75°C at the 30th min (and the temperature is maintained at 75°C for the remaining 15 min to react);

[0252] (c) the remaining vinyl acetate, azobisisobutyronitrile and mercaptoethanol are added to the reaction system at a constant speed, and at the same time, the temperature is controlled to rise to 80°C, and the dropping time is controlled to be 6 h; after the temperature reaches 80°C, the temperature in the dropping process is stabilized at 80°C;

[0253] (d) after the dropping is completed, the reaction is continued at 80°C for 4 h, and the rotating speed is gradually reduced to 50 rpm;

[0254] (e) after the reaction is completed, the temperature is reduced to 50°C to discharge the material;

[0255] (f) crushing after removing the solvent at 68 ℃ and 0.06 MPa vacuum to obtain the vinyl acetate copolymer product.

[0256] The obtained vinyl acetate copolymer product is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality tests, and the test results are shown in Table 1.

[0257] Comparative Example 3

[0258] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator being 20:100:8.15:0.175:1.

[0259] The preparation method comprises the following steps:

[0260] (a) Start stirring the reaction kettle which has been deoxygenated, and add 100% of the methanol, 100% of the vinyl acetate, 0% of the hydroxybutyl acrylate, 15% of the azobisisobutyronitrile, and 15% of the mercaptoethanol into the sealed polymerization reaction kettle;

[0261] (b) While stirring, raise the temperature of the material to 63 ℃, and start timing when the temperature reaches 63 ℃. React the raw materials for 45 min, while controlling the temperature of the material to be 75 ℃ at the 30th min (and maintaining the temperature of the material at 75 ℃ for the remaining 15 min);

[0262] (c) Uniformly add the remaining hydroxybutyl acrylate, azobisisobutyronitrile, and mercaptoethanol to the reaction system, and start controlling the temperature of the material to be raised to 80 ℃ at the same time. The dropping time is controlled to be 6 h; and after the temperature of the material reaches 80 ℃, stabilize the temperature of the material to be 80 ℃ during the dropping process;

[0263] (d) After the dropping is completed, continue to react at 80 ℃ for 4 h, and gradually reduce the rotation speed to 50 rpm;

[0264] (e) After the reaction is completed, cool down to 50 ℃ to discharge the material;

[0265] (f) crushing after removing the solvent at 68 ℃ and 0.06 MPa vacuum to obtain the vinyl acetate copolymer product.

[0266] The obtained vinyl acetate copolymer product is subjected to conversion rate, 120 ℃ melt viscosity, GPC value, K value, and hydroxyl functionality tests, and the test results are shown in Table 1.

[0267] Comparative Example 4

[0268] A vinyl acetate copolymer, the weight ratio of raw material solvent, vinyl acetate, comonomer, initiator, and chain regulator being 20:100:8.15:0.175:1.

[0269] The preparation method comprises the following steps:

[0270] (a) open the stirring of the oxygen removal reactor, and add 100% of the methanol, 15% of the vinyl acetate, 0% of the hydroxy butyl acrylate, 100% of the azobisisobutyronitrile, and 15% of the mercaptoethanol into the closed polymerization reactor;

[0271] (b) the temperature is increased to 63 DEG C under stirring, and the timer is started when the temperature reaches 63 DEG C, and the raw materials are reacted for 45 min, and the temperature is controlled to be 75 DEG C at the 30th min (and the temperature is maintained at 75 DEG C for the remaining 15 min);

[0272] (c) the remaining vinyl acetate, hydroxy butyl acrylate and mercaptoethanol are added to the reaction system at a constant speed, and the temperature is controlled to be increased to 80 DEG C at the same time, and the dropping time is controlled to be 6 h; after the temperature reaches 80 DEG C, the temperature of the dropping process is stabilized at 80 DEG C;

[0273] (d) after the dropping is completed, the reaction is continued at 80 DEG C for 4 h, and the rotating speed is gradually reduced to 50 rpm;

[0274] (e) after the reaction is completed, the temperature is reduced to 50 DEG C, and the material is discharged;

[0275] (f) after the solvent is removed at 68 DEG C and 0.06 MPa vacuum degree, the vinyl acetate copolymer product is obtained by crushing.

[0276] The obtained vinyl acetate copolymer product is subjected to conversion rate, 120 DEG C melt viscosity, GPC value, K value and hydroxyl functionality test, and the test results are shown in Table 1.

[0277] Table 1: test results of vinyl acetate copolymer performance

[0278]

[0279] As shown in Table 1, by adjusting the feeding ratio, feeding mode, reaction temperature and time and temperature increasing rate, the vinyl acetate copolymer with different viscosity numbers is prepared, and the vinyl acetate copolymer resin can be widely applied in the field of adhesives; in addition, by adjusting the amount of the comonomer, the vinyl acetate copolymer with different functionalities is prepared, and the application space of the adhesive is further widened.

[0280] The application test of the P2 standard shaving board adhesive of the vinyl acetate copolymer of some embodiments is carried out, and the test results are shown in Table 2.

[0281] Table 2: application test results of the vinyl acetate copolymer

[0282]

[0283] As shown in Table 2, the vinyl acetate copolymer with different molecular weight, viscosity and functionality prepared by regulating the polymerization process shows excellent performance in static bending strength, elastic modulus, water absorption expansion rate and the like in the flake board adhesive.

[0284] To sum up, the active groups such as hydroxyl, epoxy or amine are introduced into the polymerization molecular chain of polyvinyl acetate by the way of copolymerization, and the vinyl acetate copolymer with different viscosity and good comprehensive performance is prepared by regulating the feeding ratio, feeding mode, reaction temperature and time, heating rate and the like, so that the vinyl acetate copolymer resin can be widely applied in the field of adhesive; in addition, the vinyl acetate copolymer with different functionality is prepared by regulating the amount of the comonomer, so as to further broaden the application space of the adhesive.

[0285] The above specific embodiments describe the implementation of the present application in detail, but the present application is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concepts of the present application, the technical solutions of the present application can be modified and changed in many ways, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A method for preparing a vinyl acetate copolymer, characterized in that, Includes the following steps: (1) Mix the raw materials, including 100% solvent, 5%-50% vinyl acetate, 0-100% comonomer, 5%-50% initiator, and 0-100% chain regulator, evenly; wherein the comonomer is an alkenyl monomer containing at least one functional group of hydroxyl, epoxy, and amino groups; the weight ratio of the solvent, vinyl acetate, comonomer, initiator, and chain regulator is (5-200):100:(2.5-50):(0.05-0.5):(0-5); (2) Heat the material to temperature I. Start timing after the temperature reaches temperature I and react the raw material for 30-60 min. At the same time, control the material temperature to temperature II during the 30-60 min period. Temperature I is 62-63 ℃, and temperature II is 10-12.6 ℃ higher than temperature I. (3) Add the remaining vinyl acetate, comonomer, initiator and chain regulator dropwise to the reaction system while controlling the temperature of the material to rise to temperature III; temperature III is: 9-12 °C higher than temperature II; (4) After the addition is complete, continue the reaction at temperature III for a period of time and gradually reduce the rotation speed; (5) After the reaction is complete, the temperature is lowered and the material is discharged to obtain vinyl acetate copolymer.

2. The method for preparing a vinyl acetate copolymer according to claim 1, characterized in that, The comonomer is selected from at least one of hydroxyethyl acrylate, hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxypentyl acrylate, hydroxyisoamyl acrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, hydroxypropyl methacrylate, hydroxypentyl methacrylate, hydroxyphenyl acrylate, hydroxyphenyl methacrylate, tert-butyl hydroxymethyl acrylate, trimethylolpropane acrylate, hydroxyethyl methacrylate phosphate, hydroxyethyl caprolactone acrylate, 4-hydroxycyclohexyl methacrylate, N-hydroxymethylacrylamide, acrylamide, N-butoxymethyl (methyl)acrylamide, 3-aminoacrylate, epoxy acrylate, epoxy methacrylate, bisphenol A epoxy acrylate, and 3,4-epoxycyclohexyl methyl isobutylene acrylate.

3. The method for preparing a vinyl acetate copolymer according to claim 1, characterized in that, In step (4), after the addition is complete, continue the reaction at temperature III for 1-6 h.

4. The method for preparing a vinyl acetate copolymer according to claim 1, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, di(3,5,6-trimethylhexanoyl peroxide), tert-butyl perpentanoate, cumyl peroxide, tert-butyl peroxide, di(2-ethylhexyl) dicarbonate, dimethyl azobisisobutyronitrile, azoisobutyl cyanoformamide, benzoyl tert-butyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, and di-tert-butyl peroxide.

5. The method for preparing a vinyl acetate copolymer according to claim 1, characterized in that, The chain regulator is a chain transfer agent, which is selected from at least one of dimercaptoethanol, methanethiol, ethanethiol, acetaldehyde, dodecyl mercaptan, carbon tetrachloride, dichloromethane, n-butanethiol, and octylthiol.

6. The method for preparing a vinyl acetate copolymer according to claim 1, characterized in that, The solvent is selected from at least one of isopropanol, methanol, ethanol, n-butanol, acetone, ethyl acetate, methyl acetate, butyl acetate, benzene, toluene, chloroform, and carbon tetrachloride.

7. A vinyl acetate copolymer prepared by the method according to any one of claims 1-6.

8. The use of the vinyl acetate copolymer of claim 7 in the field of adhesives.

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