阅读说明：本技术 用于制造低分子量丙烯酸类树脂的方法 (Process for producing low molecular weight acrylic resin ) 是由 金雨渊 崔埈满 金章淳 徐光洙 于 2019-01-11 设计创作，主要内容包括：本发明涉及用于制造低分子量丙烯酸类树脂的方法,并且更具体地,涉及通过在无溶剂丙烯酸类组合物在包括反应部的连续流反应器中连续聚合期间使具有螺旋搅拌器的反应部的温度保持在特定温度来制造具有高转化率和低多分散指数的低分子量丙烯酸类树脂的方法。(The present invention relates to a method for manufacturing a low molecular weight acrylic resin, and more particularly, to a method for manufacturing a low molecular weight acrylic resin having a high conversion rate and a low polydispersity index by maintaining the temperature of a reaction part having a helical agitator at a specific temperature during continuous polymerization of a solvent-free acrylic composition in a continuous flow reactor including the reaction part.)

1. A method for manufacturing a low molecular weight acrylic resin by continuously polymerizing a solvent-free acrylic composition comprising one or more (meth) acrylate-based monomers and a thermal initiator in a continuous flow reactor comprising a reaction section having a helical agitator, a feed section, and a discharge section, the method comprising:

feeding the solvent-free acrylic composition to the reaction section through the feeding section;

forming a low molecular weight acrylic resin having a weight average molecular weight of 20,000g/mol or more and 150,000g/mol or less by maintaining the temperature of the reaction part at 70 ℃ or more and 150 ℃ or less and continuously polymerizing the solvent-free acrylic composition; and

discharging the low molecular weight acrylic resin through the discharge portion.

2. The method of claim 1, wherein the solvent-free acrylic composition is fed to the reaction section at a feed rate of 30 mL/min or more and 200 mL/min or less.

3. The method of claim 1, wherein the thermal initiator is included at a content of 0.1 parts by weight or more and 1 part by weight or less with respect to 100 parts by weight of the (meth) acrylate-based monomer.

4. The method of claim 1, wherein the solvent-free acrylic composition does not comprise any molecular weight regulator.

5. The process of claim 1, wherein the reaction section has a length to diameter ratio of from 14:1 to 28: 1.

6. The method of claim 1, wherein a separation distance between adjacent stirring blades of the helical stirrer is 10mm or more and 20mm or less.

7. The method according to claim 1, wherein the shortest distance from the distal end of the stirring blade to the stirring shaft in the helical stirrer is 5mm or more and 10mm or less.

8. The method of claim 1, wherein the reaction portion is comprised of a front end portion and a back end portion, and

the low-molecular-weight acrylic resin is formed by maintaining the temperature of the front end portion at 100 ℃ or more and 150 ℃ or less, maintaining the temperature of the rear end portion at 70 ℃ or more and 110 ℃ or less, and continuously polymerizing the solvent-free acrylic composition.

9. The method of claim 1, wherein the forming of the low molecular weight acrylic resin is performed for 1 hour or more and 2 hours or less.

10. The method according to claim 1, wherein the forming of the low-molecular-weight acrylic resin is performed while maintaining an internal pressure of the reaction part at 5 bar or less.

11. The process of claim 1, wherein the conversion of the low molecular weight acrylic resin is 70% or more and 99% or less as measured according to the following general equation 1:

[ general equation 1]

C＝B/A×100

Wherein, a means the weight (g) of the low molecular weight acrylic resin, B means the weight (g) of the dried low molecular weight acrylic resin, and C means the conversion (%).

Technical Field

The specification claims priority and benefit of korean patent application No. 10-2018-0004026, filed on 11.1.2018 with the korean intellectual property office, the entire contents of which are incorporated herein by reference. The present invention relates to a method for producing a low molecular weight acrylic resin. In particular, the present invention relates to a method for producing a low molecular weight acrylic resin by continuously polymerizing a solvent-free acrylic composition.

Background

The various optical members may be attached to the display device by an adhesive film. The adhesive film is required to maintain adhesive characteristics for a long time even if the display device is exposed to an external environment. Therefore, studies for improving the adhesive characteristics, particularly the adhesive durability, of the adhesive film have been actively conducted. In particular, a method of securing the adhesive characteristics of an adhesive film by including a low molecular weight acrylic resin has been focused during the production of the adhesive film.

In the related art, a method of manufacturing a low molecular weight acrylic resin by using a batch reactor using a solution containing an acrylic monomer, a reaction solvent, a chain extender, and the like has been used.

However, the method using the batch reactor has a problem in that a defect of the adhesive film is caused due to the use of the acrylic resin produced in a state of remaining the reaction solvent and the chain extender. In addition, the process using the batch reactor involves safety problems such as decomposition or explosion of reactants due to heat generation during the polymerization process.

Therefore, there is a need to study a method for producing an acrylic resin capable of solving the above-mentioned problems by a method instead of using a batch reactor.

[ Prior art documents ]

[ patent document ]

Japanese patent application laid-open No. JP 2001-521948A

Disclosure of Invention

Technical problem

The present invention relates to a process for the manufacture of low molecular weight acrylic resins by continuous polymerization of a solvent-free acrylic composition in a continuous flow reactor.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned may be clearly understood by those skilled in the art from the following description.

Technical scheme

An exemplary embodiment of the present invention provides a method for manufacturing a low molecular weight acrylic resin by continuously polymerizing a solvent-free acrylic composition comprising one or more (meth) acrylate-based monomers and a thermal initiator in a continuous flow reactor comprising a reaction part having a helical agitator, a feeding part, and a discharging part, the method comprising: feeding a solvent-free acrylic composition to a reaction section through a feeding section; forming a low molecular weight acrylic resin having a weight average molecular weight of 20,000 to 150,000g/mol by maintaining the temperature of the reaction part at 70 to 150 ℃ and continuously polymerizing the composition; and discharging the low molecular weight acrylic resin through the discharge portion.

Advantageous effects

The method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention may prevent a phenomenon in which the quality of the low molecular weight acrylic resin is deteriorated due to the residual solvent by using a solvent-free acrylic composition.

The method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention is advantageous in that the formed low molecular weight acrylic resin can be easily discharged by minimizing the amount of residual reactants in the reactor.

The method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention can prevent the problem of the acrylic resin varying with time due to the use of a molecular weight modifier, since a separate molecular weight modifier is not used.

The method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention is advantageous in that a low molecular weight acrylic resin can be stably manufactured because a continuous polymerization reactor is used.

Drawings

Fig. 1 is a view showing a cross section of a continuous flow reactor used in a manufacturing method according to an exemplary embodiment of the present invention.

Detailed Description

In the present specification, when a portion "includes" one constituent element, unless specifically described otherwise, it is not intended to exclude another constituent element, but is intended to also include another constituent element.

In the present specification, the unit "parts by weight" means a weight ratio between the respective components.

In the present specification, "a and/or B" means "a and B, or a or B".

In the present specification, the term "monomer" may mean a material capable of additionally forming a covalent bond by using a series of the same or different molecules under polymer-forming reaction conditions.

In the present specification, the term "(meth) acrylate" means "methacrylate" or "acrylate".

In the present specification, the "weight average molecular weight" of a compound can be calculated by using the molecular weight and molecular weight distribution of the compound. Specifically, a sample specimen in which the concentration of the compound was 1 wt% was prepared by putting Tetrahydrofuran (THF) and the compound into a 1ml glass vial, a standard specimen (polystyrene) and the sample specimen were filtered through a filter (pore size of 0.45mm), and then the elution time of the sample specimen was compared with the calibration curve of the standard specimen by injecting the specimen into a GPC syringe, thereby obtaining the molecular weight and the molecular weight distribution of the compound. In this case, Infinity II1260 (manufactured by Agilent inc.) may be used as the measuring device, and the flow rate and the column temperature may be set to 1.00 mL/min and 40.0 ℃.

In the present specification, the term "polydispersity Index (PDI)" is a ratio of a weight average molecular weight to a number average molecular weight as a value in terms of polystyrene measured by GPC, and means a value obtained by dividing the weight average molecular weight by the number average molecular weight.

In the present specification, the term "alkyl group" means a functional group containing hydrocarbons bonded in a chain and/or branched form, and specifically, means a functional group containing 1 to 20 carbon atoms and bonded in a chain and/or branched form.

In the present specification, the term "cycloalkyl group" may mean a functional group containing a hydrocarbon bonded in a cyclic form, specifically, may mean a functional group containing a hydrocarbon having 3 to 20 carbon atoms and bonded in a cyclic form, and more specifically, may mean a functional group containing a carbocyclic ring structure in which an unsaturated bond is not present in the functional group and containing a monocyclic or polycyclic ring having 3 to 20 carbon atoms.

In the present specification, the term "spacing distance between adjacent stirring blades" means a pitch of the stirring blades, specifically, means a shortest distance from one end of one stirring blade to one end of another stirring blade disposed adjacent to the stirring blade.

In the present specification, the term "the shortest distance from the distal end to the stirring shaft in the helical stirrer" means the length of a perpendicular line from an imaginary line of the distal end of the stirring shaft (which is parallel to the stirring shaft) to the surface of the stirring shaft.

In the present specification, the term "length of the reaction portion" means the longest distance from one end of the reaction portion to the other end thereof in the axial direction. Further, the term "diameter of the reaction portion" means the longest distance from one end of the reaction portion to the other end thereof in the radial direction.

In the present specification, the term "continuous polymerization" may mean that the monomer is polymerized in the above-mentioned continuous flow reactor with continuous flow of the fluid.

An exemplary embodiment of the present invention provides a method for manufacturing a low molecular weight acrylic resin by continuously polymerizing a solvent-free acrylic composition comprising one or more (meth) acrylate-based monomers and a thermal initiator in a continuous flow reactor comprising a reaction part having a helical agitator, a feeding part, and a discharging part, the method comprising: feeding a solvent-free acrylic composition to a reaction section through a feeding section; forming a low molecular weight acrylic resin having a weight average molecular weight of 20,000 to 150,000g/mol by maintaining the temperature of the reaction part at 70 to 150 ℃ and continuously polymerizing the composition; and discharging the low molecular weight acrylic resin through the discharge portion.

Hereinafter, a method for manufacturing a low molecular weight acrylic resin according to an exemplary embodiment of the present invention will be described in detail with reference to fig. 1.

Fig. 1 is a view showing a cross section of a continuous flow reactor used in a manufacturing method according to an exemplary embodiment of the present invention.

The continuous flow reactor 10 used in the manufacturing method according to an exemplary embodiment of the present invention includes a reaction part 100, a feeding part 200, and a discharging part 300, and the reaction part, the feeding part, and the discharging part may be continuously connected to one another. Further, the reaction part 100 includes a helical stirrer 101, and the helical stirrer 101 may include a stirring shaft 102 connected from one end of the reaction part to the other end thereof, and a plurality of stirring blades 103 are provided along the outer circumference of the stirring shaft. The plurality of stirring blades may be disposed to be spaced apart from each other, and may be disposed in a form of being wound around the stirring shaft. Further, the continuous flow reactor 10 may be disposed in a thermostat 400. Further, the temperature of the reaction part 100 may be adjusted according to the temperature of the heat medium fed through the heat medium feeding part 401 of the thermostat and discharged along the heat medium discharging part 402 thereof. That is, the temperature of the reaction part 100 may be maintained within a predetermined range by feeding the heat medium having a temperature within a predetermined range to the heat medium feeding part 401 and discharging the fed heat medium through the heat medium discharging part 402. Meanwhile, the heat medium may mean a fluid used as a heat transfer medium in the related art, and may be freely selected among known materials as long as the heat medium may be used to maintain the temperature range of the reaction part 100 described below.

According to an exemplary embodiment of the present description, an end of the stirring blade may be spaced apart from an inner wall of the reaction part, and particularly, the end of the stirring blade may not be in contact with the inner wall of the reaction part. Therefore, it is possible to prevent the problem that the inner wall of the reaction part is damaged by the stirring blade during the stirring by the helical stirrer.

According to an exemplary embodiment of the invention, the continuous flow reactor may be formed of stainless steel (SUS). Therefore, the heat energy supplied through the external heating medium can be efficiently transferred to the continuous flow reactor.

An exemplary embodiment of the present invention includes feeding a solvent-free acrylic composition to the reaction part 100 through the feeding part 200.

According to an exemplary embodiment of the present invention, when the solvent-free acrylic composition is fed into the reaction part, the solvent-free acrylic composition may be fed at a feed flow rate of 30 mL/min to 200 mL/min. When the feed flow rate of the solvent-free acrylic composition is within the above range, the continuous polymerization reaction from the solvent-free acrylic composition to the low-molecular-weight acrylic resin can be smoothly performed.

Furthermore, according to an exemplary embodiment of the present invention, the fluid behavior of the solvent-free acrylic composition fed into the continuous flow reactor may be turbulent. That is, the composition of the components contained in the solvent-free acrylic composition may not vary based on the radial direction of the continuous flow reactor, and may vary based on the axial direction of the continuous flow reactor.

According to an exemplary embodiment of the present invention, the solvent-free acrylic composition comprises one or more (meth) acrylate-based monomers and a thermal initiator.

According to an exemplary embodiment of the present invention, the (meth) acrylate-based monomer may include at least one of: an alkyl group-containing (meth) acrylate-based monomer, a cycloalkyl group-containing (meth) acrylate-based monomer, and a polar functional group-containing (meth) acrylate-based monomer. That is, the low molecular weight acrylic resin can be produced by polymerizing at least one acrylic monomer.

According to an exemplary embodiment of the present invention, the alkyl group-containing (meth) acrylate-based monomer may be a (meth) acrylate-based monomer in which an alkyl group is bonded to a (meth) acrylate-based monomer. In addition, the cycloalkyl group-containing (meth) acrylate-based monomer may be a (meth) acrylate-based monomer in which a cycloalkyl group is bonded to a (meth) acrylate-based monomer. In addition, the polar functional group-containing (meth) acrylate-based monomer may be a (meth) acrylate-based monomer in which a polar functional group is bonded to a (meth) acrylate-based monomer.

According to an exemplary embodiment of the present invention, the alkyl group-containing (meth) acrylate-based monomer may include at least one of: methacrylic acid esters, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, and isooctyl (meth) acrylate.

According to an exemplary embodiment of the present invention, the cycloalkyl-containing (meth) acrylate-based monomer may include at least one of the following: cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), isobornyl methyl (meth) acrylate and 3,3, 5-trimethylcyclohexyl acrylate (TMCHA).

According to an exemplary embodiment of the present invention, the polar functional group-containing (meth) acrylate-based monomer may include at least one of: a hydroxyl group-containing (meth) acrylate-based monomer, a carboxyl group-containing (meth) acrylate-based monomer, and a nitrogen-containing (meth) acrylate-based monomer.

Specifically, the hydroxyl group-containing (meth) acrylate-based monomer may include at least one of: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, and 2-hydroxypropylene glycol (meth) acrylate.

In addition, the carboxyl group-containing (meth) acrylate-based monomer may include at least one of: acrylic acid, methacrylic acid, 2-carboxyethylacrylic acid, 3-carboxypropylacrylic acid, 2- (meth) acryloxyacetic acid, 3- (meth) acryloxypropionic acid, 4- (meth) acryloxybutyric acid and acrylic acid dimer.

According to an exemplary embodiment of the present invention, the nitrogen-containing (meth) acrylate-based monomer may include at least one of: 2-isocyanatoethyl (meth) acrylate, 3-isocyanatopropyl (meth) acrylate, 4-isocyanatobutyl (meth) acrylate, and (meth) acrylamide.

According to an exemplary embodiment of the present invention, the solvent-free acrylic composition may include a thermal initiator to initiate polymerization of one or more (meth) acrylate-based monomers included in the solvent-free acrylic composition to the low molecular weight acrylic resin. The thermal initiator is an initiator that initiates crosslinking by heating, and may include, for example, at least one selected from an azo-based thermal initiator and a peroxy-based thermal initiator.

According to an exemplary embodiment of the present invention, the azo-based thermal initiator may be 2,2 ' -azobis (2-methylbutyronitrile) [ V-59, Wako Pure Chemical Industries, Ltd. ], 2 ' -azobis (isobutyronitrile) [ V-60, Wako Pure Chemical Industries, Ltd. ], 2 ' -azobis (2, 4-dimethylvaleronitrile) [ V-65, Wako Pure Chemical Industries, Ltd. ], 4-azobis (4-cyanovaleric acid), 1 ' -azobis (cyclohexanecarbonitrile), 2 ' -azobis (4-methoxy-2, 4-dimethylvaleronitrile) [ V-70, Wako Pure Chemical Industries, Ltd. ] and the like.

According to an exemplary embodiment of the present invention, the thermal initiator may be included in an amount of 0.1 parts by weight to 1 part by weight, relative to 100 parts by weight of the (meth) acrylate-based monomer. Specifically, the content of the thermal initiator may be 0.2 to 1 part by weight, 0.2 to 0.7 part by weight, 0.2 to 0.5 part by weight, 0.5 to 0.7 part by weight, 0.3 to 0.5 part by weight, 0.3 to 1 part by weight, 0.7 to 1 part by weight, 0.5 to 1 part by weight, or 0.2 to 0.3 part by weight, relative to 100 parts by weight of the (meth) acrylate-based monomer.

When the content of the thermal initiator is within the above range, the polymerization reaction of the (meth) acrylate-based monomer may be initiated, and the weight average molecular weight range of the acrylic resin may be secured by preventing excessive polymerization.

According to an exemplary embodiment of the present invention, the solvent-free acrylic composition means that it does not contain a separate solvent required for polymerization. That is, the low molecular weight acrylic resin can be produced by bulk polymerization of the solvent-free acrylic composition instead of solution polymerization of the solvent-free acrylic composition. The solvent is a solvent required for polymerization, and may mean a solvent well known in the art that can be used for manufacturing acrylic resins. The acrylic composition may not contain a separate solvent, thereby preventing the quality of the low molecular weight acrylic resin from being deteriorated due to the residual solvent.

According to an exemplary embodiment of the present invention, the solvent-free acrylic composition may not comprise any molecular weight regulator. Meanwhile, the molecular weight regulator may mean a material that increases or decreases the molecular weight of the polymerization product without affecting the polymerization rate. When the solvent-free acrylic composition does not contain any molecular weight regulator, the problem of the acrylic resin changing with time can be prevented.

The method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention is advantageous in that, when a solvent-free acrylic composition not containing any molecular weight regulator is used, it is possible to solve the problem of curing (gelling) of the acrylic resin, the problem of difficulty in handling the low molecular weight acrylic resin during the process, and the problem of a reduction in polymerization conversion due to the acrylic resin remaining in the reactor. The fact that the molecular weight regulator is substantially not included may mean a case where the molecular weight regulator is included in an amount of less than 1 ppm.

Since the solvent-free acrylic composition according to an exemplary embodiment of the present invention does not contain any molecular weight regulator, the low molecular weight acrylic resin may not contain a residue derived from the molecular weight regulator.

An exemplary embodiment of the present invention includes forming a low molecular weight acrylic resin having a weight average molecular weight of 20,000 to 150,000g/mol by maintaining the temperature of the reaction part 100 at 70 to 150 ℃ and continuously polymerizing the composition.

According to an exemplary embodiment of the present invention, the formation of the low molecular weight acrylic resin is performed while maintaining the temperature of the reaction part at 70 ℃ to 150 ℃. Specifically, the formation of the low molecular weight acrylic resin may be performed while maintaining the temperature of the reaction part at 70 ℃ to 130 ℃, 70 ℃ to 120 ℃, 80 ℃ to 150 ℃, 80 ℃ to 130 ℃, 80 ℃ to 120 ℃, 90 ℃ to 150 ℃, 90 ℃ to 130 ℃ or 90 ℃ to 120 ℃. When the temperature of the reaction part is within the above range, the continuous polymerization of the solvent-free acrylic composition to the low molecular weight acrylic resin can be smoothly performed. Specifically, when the temperature of the reaction portion is lower than the above range, there may occur a problem that the amount of the solvent-free acrylic composition remaining in the reaction portion increases. Further, when the temperature of the reaction part is higher than the above range, there may be a problem that the solvent-free acrylic composition is excessively polymerized, and as a result, the acrylic resin remains in the reaction part in a cured state, and there may occur a problem that the reaction part explodes due to the temperature rise of the reaction part.

According to an exemplary embodiment of the present invention, the ratio of the length to the diameter of the reaction part may be 14:1 to 28: 1. When the ratio of the length to the diameter of the reaction part is within the above range, the temperature in the reaction part can be easily controlled, and the solvent-free acrylic composition fed may not remain in the reaction part. Therefore, the solvent-free acrylic composition can be sufficiently polymerized into a low molecular weight acrylic resin.

According to an exemplary embodiment of the present invention, as the stirring shaft 102 of the helical stirrer 101 included in the reaction part 100 rotates, a plurality of stirring blades included in the helical stirrer rotate, so that the solvent-free acrylic composition fed to the reaction part may be mixed, and thus, the low molecular weight acrylic resin may be continuously polymerized.

According to an exemplary embodiment of the present invention, a spaced distance between adjacent stirring blades of the helical stirrer (hereinafter, a pitch of the stirring blades) may be 10mm to 20 mm. In addition, according to an exemplary embodiment of the present invention, the shortest distance from the distal end of the stirring blade to the stirring shaft in the helical stirrer may be 5mm to 10 mm.

When the pitch of the stirring blades and the shortest distance from the distal end to the stirring shaft in the helical stirrer satisfy the above ranges, the continuous polymerization reaction of the solvent-free acrylic composition to the low molecular weight acrylic resin can be smoothly performed. In particular, the heat generation of the continuous polymerization reaction of the solvent-free acrylic composition to the low molecular weight acrylic resin may be easily controlled, and the low molecular weight acrylic resin may be manufactured to have a weight average molecular weight, a conversion rate, and a polydispersity index range according to an exemplary embodiment of the present invention.

According to an exemplary embodiment of the present invention, the formation of the low molecular weight acrylic resin may be performed while maintaining the stirring rate of the helical stirrer at 50rpm to 150 rpm. Meanwhile, the stirring rate means the number of rotations per unit time (unit: minute) of the stirring blade included in the helical stirrer. When the stirring rate is within the above range, the continuous polymerization to the low molecular weight acrylic resin can be smoothly performed, and the produced low molecular weight acrylic resin can be sufficiently discharged without accumulating in the reactor.

According to an exemplary embodiment of the present invention, the formation of the low molecular weight acrylic resin may be performed for 1 hour to 2 hours. That is, the time for continuous polymerization reaction from the solvent-free acrylic composition to the low molecular weight acrylic resin may be 1 hour to 2 hours. When the time of the continuous polymerization reaction is within the above range, the low molecular weight acrylic resin can be smoothly formed to prevent a phenomenon in which the low molecular weight acrylic resin is cured (gelled) due to uncontrolled heat generation of the low molecular weight acrylic resin and to ensure stability of the resulting continuous polymerization reaction.

According to an exemplary embodiment of the present invention, the formation of the low molecular weight acrylic resin may be performed while maintaining the internal pressure of the reaction section at 5 bar or less, specifically greater than 0 bar and 5 bar or less, 1 bar to 5 bar, 1.5 bar to 4.5 bar, 1.5 bar to 4 bar, 1.5 bar to 3 bar, or 1.5 bar to 2 bar. When the internal pressure of the reaction part is within the above range, the continuous polymerization reaction of the low molecular weight acrylic composition to the low molecular weight acrylic resin can be stably performed.

According to an exemplary embodiment of the present invention, the reaction part may be composed of a front end part and a rear end part. Meanwhile, in the present specification, the front end portion means a portion from one end of the reaction portion to a midpoint of the reaction portion in the axial direction, and the rear end portion means a portion from the midpoint of the reaction portion to the other end of the reaction portion in the axial direction.

According to an exemplary embodiment of the present invention, the formation of the low molecular weight acrylic resin may continuously polymerize the solvent-free acrylic composition while keeping the temperatures of the front end portion and the rear end portion at the same temperature or different temperatures. Specifically, the formation of the low molecular weight acrylic resin may continuously polymerize the composition while maintaining the temperature of the front end portion at 100 ℃ to 150 ℃ and the temperature of the rear end portion at 70 ℃ to 110 ℃. When the front end portion and the rear end portion of the reaction portion are maintained at a specific temperature, the continuous polymerization reaction of the low molecular weight acrylic composition to the low molecular weight acrylic resin can be stably performed. Meanwhile, the temperature of the leading end portion may be adjusted according to the temperature of the heat medium fed through the first heat medium feed portion of the first thermostat and discharged along the first heat medium discharge portion thereof, and the temperature of the trailing end portion may be adjusted according to the temperature of the heat medium fed through the second heat medium feed portion of the second thermostat and discharged along the second heat medium discharge portion thereof.

According to an exemplary embodiment of the present invention, the pitch of the stirring blades of the respective helical stirrers of the front end portion and the rear end portion, and the shortest distance from the distal ends of the stirring blades to the stirring shaft in the helical stirrers may be the same as or different from each other. Specifically, the pitch of the stirring blades of the respective helical stirrers of the front end portion and the rear end portion may independently be 10mm to 20 mm. In addition, the shortest distance from the distal end of the stirring blade to the stirring shaft of the front end portion and the rear end portion in the helical stirrer may be independently 5mm to 10 mm.

An exemplary embodiment of the present invention includes discharging the low molecular weight acrylic resin through the discharging part 300.

According to an exemplary embodiment of the present invention, the low molecular weight acrylic resin produced in the reaction section of the continuous flow reactor may be obtained by discharging through the discharge section of the continuous flow reactor. Further, when the low molecular weight acrylic resin is not discharged, the formed low molecular weight acrylic resin may remain inside the continuous flow reactor. Therefore, there may arise problems that the internal pressure of the continuous flow reactor increases, with the result that the polymerization stability of the low molecular weight acrylic resin deteriorates, and the productivity of the low molecular weight acrylic resin decreases.

According to an exemplary embodiment of the present invention, the flow rate of the solvent-free acrylic composition fed to the feeding part of the continuous flow reactor and the flow rate of the low molecular weight acrylic resin discharged from the discharging part of the continuous flow reactor may be the same as each other. That is, according to an exemplary embodiment of the present invention, the discharge of the low molecular weight acrylic resin may discharge the formed acrylic resin at a discharge flow rate of 30 mL/min to 200 mL/min through the discharge portion.

Further, in this case, the continuous flow reactor may be kept in a steady state. That is, in the method for producing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention, the production rate of the low molecular weight acrylic resin does not change with time.

Hereinafter, the low molecular weight acrylic resin produced according to the production method will be described in more detail.

According to an exemplary embodiment of the present invention, the low molecular weight acrylic resin may include a (meth) acrylate-based monomer as a monomer unit. That is, during the process of forming the (meth) acrylate-based monomer into the low molecular weight acrylic resin, the (meth) acrylate-based monomer may be included as a repeating unit in the low molecular weight acrylic resin.

According to an exemplary embodiment of the present invention, the weight average molecular weight of the acrylic resin may be 20,000g/mol to 150,000 g/mol. Specifically, the weight average molecular weight of the acrylic resin may be 25,000 to 150,000g/mol, 25,000 to 130,000g/mol, 35,000 to 13,000g/mol, 45,000 to 150,000g/mol, 45,000 to 130,000g/mol, 25,000 to 35,000g/mol, or 25,000 to 34,000 g/mol. Since the low molecular weight acrylic resin has a weight average molecular weight within the above range, when the low molecular weight acrylic resin is included in the adhesive composition, excellent attachment strength may be exhibited, and the low molecular weight acrylic resin may be applied to various optical materials.

According to an exemplary embodiment of the present invention, the polydispersity index of the low molecular weight acrylic resin may be 5 or less, specifically, 2 to 5, 2 to 3.5, 2.5 to 5, 2.5 to 3.5, 2.9 to 3.3, or 2.9 to 3.1. The fact that the low molecular weight acrylic resin has a polydispersity index within the above range may mean that heat is uniformly transferred during a continuous polymerization process to the low molecular weight acrylic resin.

According to an exemplary embodiment of the present invention, the conversion of the low molecular weight acrylic resin measured according to the following general equation 1 may be 70% to 99%, specifically 70% to 90%, and more specifically 70% to 80%, 70% to 79%, 71% to 79%, 83.5% to 85%, or 84% to 85%.

[ general equation 1]

C＝B/A×100

In general equation 1, a means the weight (g) of the low molecular weight acrylic resin, B means the weight (g) of the dried low molecular weight acrylic resin, and C means the conversion (%).

According to an exemplary embodiment of the present invention, a dried low molecular weight acrylic resin may be obtained by drying a low molecular weight acrylic resin at a temperature of about 150 ℃ for a time of about 50 minutes.

The fact that the low-molecular-weight acrylic resin has a conversion ratio within the above range may mean that the solvent-free acrylic composition fed rarely remains in the reaction part, and most of the solvent-free acrylic composition is continuously polymerized into the low-molecular-weight acrylic resin.

Another exemplary embodiment of the present invention provides a low molecular weight acrylic resin manufactured according to the manufacturing method.

According to an exemplary embodiment of the present invention, the low molecular weight acrylic resin may be the same as the above-described low molecular weight acrylic resin.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to examples for specifically describing the present invention. However, the embodiments according to the present invention may be modified in various forms, and it should not be construed that the scope of the present invention is limited to the embodiments described below. The embodiments of the present description are provided to more fully explain the present invention to those of ordinary skill in the art.

[ example 1]

A continuous flow reactor was prepared which comprised a reaction section composed of a front end section (length: 500mm) having a helical agitator and a rear end section (length: 500mm) having a helical agitator, a feeding section provided at one end of the reaction section, and a discharging section provided at the other end of the reaction section. The pitch of the stirring blades of the front-end helical stirrer was 10mm, and the shortest distance from the distal ends of the stirring blades to the stirring shaft was 5 mm. Further, the pitch of the stirring blade of the rear-end helical stirrer was 20mm, and the shortest distance from the distal end of the stirring blade to the stirring shaft was 10 mm.

The continuous flow reactor is disposed such that a front end portion of the continuous flow reactor is disposed in a first thermostat including a first heating medium feed and a first heating medium discharge, and a rear end portion of the continuous flow reactor is disposed in a second thermostat including a second heating medium feed and a second heating medium discharge.

Preparing a solvent-free acrylic composition comprising 0.2 parts by weight of an azo-based thermal initiator [2, 2' -azobis (2, 4-dimethylvaleronitrile ], relative to a total of 100 parts by weight of 52 parts by weight of 2-ethylhexyl acrylate (2-EHA), 38 parts by weight of isobornyl acrylate (IBOA), and 10 parts by weight of hydroxyethyl acrylate (HEA); v-65, Wako Pure Chemical Industries, Ltd.

The temperature of the leading end portion was maintained at 105 c by circulating the silicone oil as the heat medium through the first heat medium feeding portion and the first heat medium discharging portion of the first thermostat. Further, the temperature of the rear end portion was maintained at 105 ℃ by circulating the silicone oil as the heat medium through the second heat medium feeding portion and the second heat medium discharging portion of the second thermostat.

Next, the solvent-free acrylic composition was fed to the reaction section at a flow rate of 200 mL/min through the feeding section of the continuous flow reactor.

The low molecular weight acrylic resin was formed by adjusting the stirring rate of the helical stirrer in the reaction part to 50rpm to 150rpm and performing bulk continuous polymerization for 1 hour. Next, a low molecular weight acrylic resin was produced by discharging the formed low molecular weight acrylic resin at the same flow rate as the feed flow rate through the discharge section of the continuous flow reactor.

[ example 2]

A low-molecular weight acrylic resin was produced in the same manner as in example 1, except that the content of the thermal initiator was adjusted to 0.5 part by weight, and that the bulk continuous polymerization was allowed to proceed for 1 hour 5 minutes.

[ example 3]

A low-molecular weight acrylic resin was produced in the same manner as in example 1, except that the content of the thermal initiator was adjusted to 1 part by weight, and the bulk continuous polymerization was allowed to proceed for 1 hour 15 minutes.

[ example 4]

A low-molecular weight acrylic resin was produced in the same manner as in example 1, except that the content of the thermal initiator was adjusted to 0.3 part by weight.

[ example 5]

A low-molecular weight acrylic resin was produced in the same manner as in example 1, except that the content of the thermal initiator was adjusted to 0.5 part by weight, the pitch of the stirring blade at the rear end portion was 10mm, the shortest distance from the distal end of the stirring blade to the stirring shaft was 5mm, and the bulk continuous polymerization was allowed to proceed for 1 hour 20 minutes.

[ example 6]

A low-molecular weight acrylic resin was produced in the same manner as in example 5, except that the temperature of the rear end portion was maintained at 70 ℃ by circulating the silicone oil as the heat medium through the second heat medium feed portion and the second heat medium discharge portion of the second thermostat, and the bulk continuous polymerization was carried out for 2 hours.

[ example 7]

A low-molecular-weight acrylic resin was produced in the same manner as in example 6, except that the content of the thermal initiator was adjusted to 0.7 part by weight.

Comparative example 1

52 parts by weight of 2-ethylhexyl acrylate (2-EHA), 38 parts by weight of isobornyl acrylate (IBOA), and 10 parts by weight of hydroxyethyl acrylate (HEA) were introduced into a batch glass reactor, air in the reactor was removed by introducing nitrogen gas into the reactor for 1 hour, and then the reactor temperature was increased by using a water circulation heater. Further, when the reactor temperature reached 40 ℃ to 80 ℃, by introducing 0.2 parts by weight of an azo-based thermal initiator [2, 2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile ], relative to 100 parts by weight in total of 2-ethylhexyl acrylate (2-EHA), isobornyl acrylate (IBOA), and hydroxyethyl acrylate (HEA); v-70, Wako Pure Chemical Industries, Ltd. ] causes polymerization in a batch glass reactor.

However, in this case, since the temperature of the reactor is higher than 140 ℃, the polymerization reaction is forcibly terminated and a low molecular weight acrylic resin cannot be obtained.

Comparative example 2

A continuous flow reactor is prepared which includes a reaction section without a separate helical agitator, a feed section disposed at one end of the reaction section, and a discharge section disposed at the other end of the reaction section.

The continuous flow reactor is provided in a thermostat including a heat medium feed and a heat medium discharge.

Preparing a solvent-free acrylic composition comprising 0.2 parts by weight of an azo-based thermal initiator [2, 2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile ], relative to a total of 100 parts by weight of 52 parts by weight of 2-ethylhexyl acrylate (2-EHA), 38 parts by weight of isobornyl acrylate (IBOA), and 10 parts by weight of hydroxyethyl acrylate (HEA); v-70, Wako Pure Chemical Industries, Ltd.

The heating medium of 105 c is circulated through the heating medium feed and discharge parts of the thermostat. Next, the solvent-free acrylic composition was fed to the reaction section through the feeding section of the continuous flow reactor.

The temperature of the reaction part was maintained at 105 ℃ and a low molecular weight acrylic resin was formed. Next, a low molecular weight acrylic resin is produced by discharging the low molecular weight acrylic resin through the discharge portion of the continuous flow reactor.

Comparative example 3

A solvent-type acrylic composition comprising 0.06 parts by weight of a photopolymerization initiator (Irgacure 184, CIBA), 0.12 parts by weight of a molecular weight modifier (isooctylthioglycolate), and 30 parts by weight of an ethyl acetate solvent, relative to 100 parts by weight in total of 52 parts by weight of 2-ethylhexyl acrylate (2-EHA), 38 parts by weight of isobornyl acrylate (IBOA), and 10 parts by weight of hydroxyethyl acrylate (HEA), was prepared.

Low molecular weight acrylic resins were produced by introducing a solvent-based acrylic composition into a batch glass reactor and irradiating the composition with light using a metal halide lamp for 5 hours.

Comparative example 4

52 parts by weight of 2-ethylhexyl acrylate (2-EHA), 38 parts by weight of isobornyl acrylate (IBOA), and 10 parts by weight of hydroxyethyl acrylate (HEA) were introduced into a batch glass reactor, air in the reactor was removed by introducing nitrogen gas into the reactor for 1 hour, and then the reactor temperature was increased by using a water circulation heater. Further, when the reactor temperature reached 40 ℃ to 80 ℃, by introducing 0.002 parts by weight of azo-based thermal initiator [2, 2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile), relative to 100 parts by weight in total of 2-ethylhexyl acrylate (2-EHA), isobornyl acrylate (IBOA), and hydroxyethyl acrylate (HEA); v-70, Wako Pure Chemical Industries, Ltd. ] and 0.12 part by weight of a molecular weight modifier (dodecylmercaptan) to cause polymerization in a batch glass reactor to produce a low molecular weight acrylic resin.

[ Experimental example 1] measurement of weight average molecular weight and polydispersity index

Samples in which the concentration of the low molecular weight acrylic resin was 1 wt% were produced by dissolving each of the low molecular weight acrylic resins according to examples 1 to 7 and comparative examples 2 to 4 in a tetrahydrofuran solvent.

The weight average molecular weight and polydispersity index of the samples were measured by using GPC (Agilent 1260) and are shown in table 1 below.

Experimental example 2 measurement of conversion

Samples were produced by collecting 0.1g (a) of each of the low molecular weight acrylic resins according to examples 1 to 7 and comparative examples 2 to 4.

The weight (B) of the sample after drying in an oven at 150 ℃ for 50 minutes was measured, and the conversion was calculated according to general equation 1 and is shown in table 1 below.

[ Table 1]

From table 1, it can be confirmed that the method for manufacturing a low molecular weight acrylic resin according to examples 1 to 7 can manufacture a low molecular weight acrylic resin having a weight average molecular weight of 20,000g/mol to 150,000g/mol at a high conversion rate. In particular, it was confirmed that the low molecular weight acrylic resins according to examples 6 and 7 in which the temperatures of the front end portion and the rear end portion were variously adjusted had a small weight average molecular weight and an excellent conversion rate.

Meanwhile, since the reactor temperature was increased to 140 ℃ or more according to the method of comparative example 1 using a batch glass reactor, the polymerization reaction was forcibly terminated due to a safety problem, and in this case, it was confirmed that the low molecular weight acrylic resin could not be produced.

It was confirmed that according to the production method in comparative example 2 using a continuous flow reactor not including a helical agitator, a low molecular weight body could be produced, but the conversion of the produced low molecular weight acrylic resin was about 65% and did not reach the range according to the exemplary embodiment of the present invention. In addition, it can be seen that the low molecular weight acrylic resin formed according to the polymerization method in comparative example 2 was not sufficiently discharged from the reaction part. Further, there is a problem in that the polymerization method in comparative example 2 is not suitable for a mass production process because polymerization stability is deteriorated and pressure is rapidly increased during polymerization for a long time.

In the case of comparative example 3 in which a low molecular weight resin was produced by photopolymerizing a solvent-type acrylic composition containing a molecular weight modifier in a batch glass reactor, there was a problem in that a separate process of removing the solvent and the molecular weight modifier was required. Further, in the case of comparative example 3, there is a problem that comparative example 3 is not suitable for a mass production process due to a long reaction time.

In the case of comparative example 4 in which a low molecular weight resin was produced by photopolymerizing a solvent-free acrylic composition containing a molecular weight modifier in a batch glass reactor, there was a problem in that comparative example 4 had a low conversion rate because the reaction heat was not smoothly controlled.

In conclusion, it can be seen that the method for manufacturing a low molecular weight acrylic resin according to one exemplary embodiment of the present invention can stably manufacture a low molecular weight acrylic resin having a high conversion rate and a low polydispersity index and having a weight average molecular weight of 20,000 to 150,000g/mol even in the case of a short reaction time. Further, it can be seen that since the solvent-free acrylic composition is used, the quality of the low molecular weight acrylic resin can be prevented from being deteriorated due to the residual solvent.

[ description of reference numerals ]

10: continuous flow reactor

100: reaction part

101: spiral stirrer

102: stirring shaft

103: stirring paddle

200: feeding part

300: discharge part

400: thermostat device

401: heating medium feeding part

402: heat medium discharging part