JP2007177217A - Method for producing acrylic copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an acrylic copolymer easily controlling its molecular weight and molecular weight distribution, and enabling the introduction of a specific functional group at the terminal of the acrylic copolymer. <P>SOLUTION: This method for producing the acrylic copolymer is provided by performing a radical copolymerization of an acrylic monomer by using an organic peroxide as a polymerization initiator in the presence of a compound having ≥2 hindered amino groups in one molecule. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel polymerization method of an acrylic copolymer. The acrylic copolymer produced by the present invention is suitably used in fields such as coating materials, pressure-sensitive adhesives, and sealing agents that require specific excellent functions such as tackiness, uniformity and weather resistance, and film-forming properties. It is what is done.

  Radical polymerization is an industrially important production technique and is widely used for the production of vinyl polymers. However, in radical polymerization, the stability of polymer growth terminal radicals is poor, so as the polymerization rate increases, the molecular weight distribution becomes polydisperse, and many low molecular weight polymers are produced, resulting in the chemical resistance and heat resistance of the polymer. It adversely affects physical and chemical properties such as sex.

  In addition, radical polymerization is an unstable growth radical, so that it can be used to produce more highly functional block copolymers and graft copolymers, and specific useful functionalities such as hydroxyl groups and carboxyl groups at the polymer ends. It is difficult to introduce a group, further narrow the molecular weight distribution and suppress the formation of a low molecular weight polymer. This is even more difficult when an acrylic monomer that tends to cause a disproportionation termination reaction is used as a raw material monomer.

  In radical polymerization, a polymer growth terminal radical is obtained from a reaction between a radical and a monomer, and the radical is generally generated by a decomposition reaction of an initiator. As typical initiators, azo compounds and organic peroxides are widely used. Organic peroxides have various structures and are decomposed at different temperatures, and the optimum one is used according to the purpose. There are many patents related to radical polymerization using organic peroxides (see Patent Document 1).

  In order to control radical polymerization of acrylic monomers and enable living radical polymerization, acrylic monomers in the presence of specific alkoxyamine compounds or nitroxide radical compounds, and in the presence of styrene or styrene derivatives, essential There has been proposed a method for producing a polymer radical polymer that can be radically polymerized to enable living radical polymerization. Furthermore, in the presence of a specific nitroxide compound, when a methacrylic acid ester and an acrylic acid ester are selected as monomer components, a polymer capable of living radical polymerization having an alkoxyamine group at the terminal is generated. (See Patent Document 2).

  In the above proposal, there are limitations on the acrylic monomers that can be applied, and not only the polymerization temperature is high, but also the polymerization rate is extremely slow, and many problems remain to be applied in practice.

  There has been proposed a method of graft copolymerizing an acrylic monomer in the presence of a nitrooxy radical compound using a vinyl polymer obtained by copolymerizing a vinyl monomer having an alkoxyamine group as a backbone polymer (Patent Document 3). , See Patent Document 4).

The above proposed technique is presumed to be useful as one technique for producing a block copolymer or a graft copolymer. However, the proposed technique has a very slow polymerization rate, resulting in high manufacturing costs. As a polymer produced by radical polymerization that requires versatility, there are great disadvantages.
Japanese Patent Laid-Open No. 11-60636 JP 2003-268046 A JP 2004-331817 A JP 2001-64308 A

  Disclosed is a method for producing an acrylic copolymer, in which the molecular weight and molecular weight distribution can be easily controlled and a useful specific functional group can be introduced at the end of the acrylic copolymer.

  In order to solve the above-mentioned problems, an acrylic copolymer that radically copolymerizes an acrylic monomer using an organic peroxide as a polymerization initiator in the presence of a compound having two or more hindered amino groups in the molecule. I found a method for manufacturing coalescence.

  More preferably, it is a method for producing an acrylic copolymer in which an acrylic monomer is radically copolymerized in the presence of a reaction product of a compound having two or more hindered amino groups in one molecule and an organic peroxide. is there.

  The manufacturing method of the acrylic copolymer of this invention is used for manufacture of an acrylic copolymer suitable for uses, such as an adhesive agent, a coating material, a sealing agent, and a photosensitive resist.

  In the method for producing an acrylic copolymer of the present invention, the molecular weight and molecular weight distribution can be easily controlled, and a useful specific functional group can be introduced at the end of the acrylic copolymer. The production method of the present invention shows a behavior in which the molecular weight of the acrylic copolymer increases as the polymerization of the acrylic monomer proceeds, and the control of the molecular weight and molecular weight becomes easy.

  As is well known, the behavior in which the number average molecular weight of an acrylic copolymer increases with the progress of polymerization of an acrylic monomer is called living radical polymerizability (Reference: “Radical Polymerization Handbook”, supervised by Mikiharu Koike, Takeshi Endo, NT Issued by S Co. (1999), p102 to p152).

  According to the method for producing an acrylic copolymer of the present invention, the number average molecular weight of the acrylic copolymer increases with the progress of polymerization of the acrylic monomer (increase in the polymerization rate), and the molecular weight and molecular weight distribution can be controlled. It becomes easy. From this, the acrylic copolymer polymer terminal in radical polymerization is living (active terminal), and it may be possible to introduce a useful specific functional group to the acrylic copolymer terminal.

  The present invention is a method for producing an acrylic copolymer in which an acrylic monomer is radically copolymerized using an organic peroxide as a polymerization initiator in the presence of a compound having two or more hindered amino groups in one molecule. . More preferably, the present invention provides an acrylic copolymer that radically copolymerizes an acrylic monomer in the presence of a reaction product of a compound having two or more hindered amino groups in one molecule and an organic peroxide. It is a manufacturing method.

  Examples of the compound having two or more hindered amino groups in one molecule in the present invention include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro (4,5) decane-2,4-dione, decane Diacid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-pepyridinyl) ester, and 2- (2,2,6,6-tetramethyl-4-hydroxy) piperidi Nyloxyethyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidinyl-methacrylate, 2,2,6,6-tetramethyl-4-piperidinyl-methacrylate, 1- (4-biphenyl) Le benzyloxy) -2,2,6,6-tetramethyl-4-hydroxy - radically copolymerizable hindered group-containing compound such as piperidine copolymerized acrylic copolymer and the like are exemplified. These compounds having two or more hindered amino groups in one molecule may be used alone or as a mixture of two or more.

  Among these compounds having two or more hindered amino groups in one molecule, from the viewpoint of radical polymerization control and polymerization rate, and (functional) functional groups such as hydroxyl groups and carboxyl groups at both ends. In order to produce the acrylic copolymer having, for example, a compound represented by the following structural formula is preferably used.

(R1 and R2 are alkyl groups having 1 to 12 carbon atoms, alkylphenyl groups, and phenylalkyl groups, and n represents an integer of 2 to 12).

  Furthermore, compounds represented by the following structural formula are preferably used.

(Here, R1 and R2 are a hydrogen atom or a methyl group, or an alkyloxy group having 1 to 12 carbon atoms, and n represents an integer of 6 to 12)
As a compound having two or more hindered amino groups in one molecule having the above structural formula, bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) decanedioate Compounds having an amino ether bond such as ester, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and the like Illustrated.

  Furthermore, in order to produce a graft copolymer efficiently, for example, 2- (2,2,6,6-tetramethyl-4-hydroxy) piperidinyloxyethyl methacrylate represented by the following structural formula

(R3 represents a hydrogen atom or a methyl group, R4 represents an alkyl group having 1 to 4 carbon atoms, an alkylphenyl group, and R5 represents a hydroxyl group or an acetamino group), 1- (4-vinyl represented by the following structural formula Benzyloxy) -2,2,6,6-tetramethyl-4-hydroxy-piperidine

(R6 represents a hydroxyl group or an acetamino group, and R7 represents an alkyl group having 1 to 6 carbon atoms.)
An acrylic copolymer obtained by copolymerizing a compound is preferably used.

  Furthermore, 2- (2,2,6,6-tetramethyl-4-hydroxy) piperidinyloxyethyl methacrylate and 1- (4-vinylbenzyloxy) -2,2,6,6-tetramethyl-4 An acrylic copolymer obtained by copolymerizing hydroxy-piperidine is preferably used.

In the present invention, a compound having two hindered groups per molecule, with respect to the acrylic monomers 1 mol, ^{preferably, 1 × 10 -5 ~8 × 10} 0 mol, more preferably, 2 It is desirable to use × 10 ^{−3 to} 5 × 10 ⁻¹ mol.

  The compound having two or more hindered amino groups in one molecule is preferably 0.002 to 20.0% by weight, more preferably 0, based on 100 parts by weight of the total copolymerized acrylic monomer. It is desirable to use 0.005 to 15.0% by weight, more preferably 0.02 to 12.0% by weight.

  When the amount of the compound having two or more hindered amino groups in one molecule is less than 0.002% by weight relative to a total of 100 parts by weight of the acrylic monomer, the polymerization rate is hardly increased, The production of the acrylic copolymer requires a long time and tends to lose practicality.

  When the amount of the compound having two or more hindered amino groups in one molecule exceeds 20.0% by weight based on 100 parts by weight of the acrylic monomer, In some cases, coloring may be observed, which may cause a problem in practical use.

  On the other hand, 3 molecules in one molecule such as an acrylic copolymer copolymerized with a hindered amino group-containing compound such as 2- (2,2,6,6-tetramethyl-4-hydroxy) piperidinyloxyethyl methacrylate. The compound having one or more hindered amino groups is preferably used in an amount of 0.02 to 100% by weight, more preferably 5.0 to 85% by weight based on 100 parts by weight of the acrylic monomer. Is desirable.

  When the amount of the compound having 3 or more hindered amino groups in one molecule is less than 0.02% by weight based on 100 parts by weight of the acrylic monomer, the living radical polymerization property of the polymerization May become dilute, making it impossible to produce an acrylic copolymer with controlled molecular weight distribution and terminal functional groups. When a compound having 3 or more hindered amino groups in one molecule exceeds 100% by weight based on 100 parts by weight of the acrylic monomer, it tends to cause gelation during polymerization. There are cases where polymerization control is difficult.

  In the present invention, the acrylic copolymer is produced by radical polymerization using an organic peroxide as a polymerization initiator.

  Organic peroxides include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, cumene hydroperoxide, t-butyl hydroperoxide, methylcyclohexanone peroxide, disuccinic Examples include acid peroxide and acetylacetone peroxide. The organic peroxide may be used alone or as a mixture of two or more.

  Further, in the present invention, as an organic peroxide for introducing a useful hydroxyl group or carboxyl group at the end of the acrylic copolymer, two or more active hydrogen atoms are contained in a molecule such as methylcyclohexanone peroxide or disuccinic acid peroxide. The compound which has can be used preferably.

  In the present invention, it is preferable that at least one of organic peroxides having the following structure is used in the molecule, which is recommended in terms of shortening the production time, lowering the polymerization temperature, and improving the living radical polymerizability. Is done.

(Here, it represents an alkyl group, a phenyl group, or a hydroxyalkyl group.)

(Here, R6 is a phenyl group, which may have a substituent.)
Preferred organic peroxides represented by the above structural formula include benzoyl peroxide, t-butylperoxybenzoate, bis (t-butylperoxy) isophthalate, and the like.

The organic peroxide is preferably 1 × 10 ⁻⁴ mol to 5.0 mol, more preferably 5 × 10 ⁻⁴ mol, relative to 1 mol of the compound having two or more hindered amino groups in one molecule. It is desirable to use ~ 3.0 mol.

When the amount of the organic peroxide used is 1 × 10 ⁻⁴ mol to 5.0 mol with respect to 1 mol of the compound having two or more hindered amino groups in one molecule, the polymerization efficiency is good. It has a sufficient molecular weight, has a living radical polymerization property of polymerization, and tends to produce less low molecular weight polymer.

  In the present invention, the molecular weight of the acrylic copolymer preferably increases as the polymerization of the acrylic monomer proceeds. In the present invention, the acrylic copolymer preferably has living radical polymerizability. In the present invention, the living radical polymerizability is a property showing a behavior in which the molecular weight of the acrylic copolymer increases with the progress of polymerization of the acrylic monomer (increase in the polymerization rate) in the process of manufacturing the acrylic copolymer. .

  In the present invention, acrylic monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid. (Fluoro) of (meth) acrylic acid such as n-butyl acid, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, benzyl methacrylate, 2-trifluoroethyl methacrylate ) Alkyl ester (a), acrylic acid, methacrylic acid, maleic acid, maleic anhydride, carboxyl group-containing acrylic monomer having a carboxyl group in the molecule (b), acrylic acid 2-hydroxyethyl, acrylic acid 2- Hydro Hydroxyl group-containing acrylics with hydroxyl groups in the molecule such as propyl, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, mono (meth) acrylate of glycerin Monomer (c), acrylic monomer (d) having an epoxy group in the molecule such as glycidyl methacrylate, methyl glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, allyl acrylate, allyl methacrylate, etc. Silane group containing hydrolyzable silyl group in the molecule such as allyl group-containing acrylic monomer (e), γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, etc. Acrylic monomer f), UV-absorbing acrylic monomers (g) having a benzotriazole-based UV-absorbing group such as 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole, and the like are exemplified. . These other acrylic monomers may be used alone or as a mixture of two or more.

  Further, if necessary, a vinyl compound capable of radical polymerization such as styrene, α-methylstyrene, acrylonitrile, vinyl acetate and the like can be used in combination. These vinyl compounds are desirably used in an amount not exceeding 80% by weight based on the acrylic monomer.

  The radical polymerization of the acrylic monomer is preferably carried out under an inert gas atmosphere at a polymerization temperature of preferably 50 to 150 ° C, more preferably 70 to 135 ° C, and even more preferably 80 to 120 ° C. When the polymerization temperature is less than 50 ° C., the polymerization rate is slow, so that the polymerization rate is difficult to increase, and the production efficiency may be deteriorated. When the polymerization temperature exceeds 150 ° C., the chain transfer reaction during radical polymerization cannot be ignored, and the living property of the polymerization tends to be impaired.

  In the present invention, the radical polymerization of the acrylic monomer is preferably carried out in a polymerization system substituted with an inert gas such as nitrogen gas, argon gas or helium gas. At this time, the oxygen concentration of the polymerization system is preferably 5 vol% or less, more preferably 2 vol% or less, and still more preferably 0.5 vol% or less. When the oxygen concentration in the polymerization system exceeds 5 vol%, the radical polymerization reaction is affected by the oxygen in the system and may not proceed sufficiently. That is, the polymerization rate is remarkably slowed, and a polymer having a low polymerization degree may be produced in many cases due to polymerization termination or telomerization by oxygen, and the living property of the polymerization tends to be impaired.

  In the present invention, the oxygen concentration in the polymerization system was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of New Cosmos Electric Co., Ltd.).

  In the present invention, the radical polymerization of the acrylic monomer is preferably toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, n-butyl alcohol, hexane, heptane, propylene glycol monomethyl ether, propylene. It is carried out using an organic solvent such as glycol monomethyl ether acetate, dipropylene glycol monobutyl ether, γ-butyrolactone, dibutyl phthalate, di-2-ethylhexanoate phthalate, benzyl benzoate, polypropylene glycol, polytetramethylene glycol and the like as a medium.

  In the present invention, an organic solvent having a small chain transfer constant such as ethyl acetate or n-propyl acetate is preferably used as the organic solvent.

  As the polymerization method, any method such as solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization carried out using water as a medium can be applied.

  Bulk polymerization and solution polymerization are recommended because of ease of polymerization control and ease of polymer purification. In the case of solution polymerization, the organic solvent to be used is not particularly limited as long as the monomer is dissolved.

  Below, an example of the preferable aspect of this invention is shown.

  A polymerization solvent (for example, ethyl acetate / n-propyl acetate (= 80/20 weight ratio) is charged into a flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, a stirrer, an acrylic monomer supply port, and a constant flow pump. Nitrogen gas is introduced into the bottom of the flask and bubbling is performed, and the oxygen concentration in the flask is reduced to 0.5 vol% or less while measuring the oxygen concentration in the flask with an oxygen concentration meter “XO-326ALA”. Continue bubbling until

  After confirming that the oxygen concentration in the flask is 0.5 vol% or less, a compound having two or more hindered amino groups in one molecule (for example, bis (2,2,6,6-tetramethyl- A predetermined amount of 4-piperidinyl) sebacate) is charged and dissolved to be uniform. Next, an organic peroxide, for example, benzoyl peroxide, is charged in an amount twice as much as that of bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and the temperature rise is started.

  The temperature is raised to 80 ° C. over 30 minutes, and then maintained at 80 ° C.

  An acrylic monomer, for example, a mixed monomer of butyl acrylate / cyclohexyl acrylate / 4-hydroxybutyl acrylate (= 77/20/3 weight ratio) is dropped into the flask via a constant flow pump in 2 hours. .

  Thereafter, sampling is performed, and the polymerization rate and the number average molecular weight are measured. When the polymerization rate reaches 1.0, the polymerization is completed, and the mixture is cooled to produce the acrylic resin of the present invention.

  Details of the present invention will be described below with reference to Examples and Comparative Examples.

  In the following Examples and Comparative Examples, the number average molecular weight (hereinafter also referred to as Mn) and the weight average molecular weight (hereinafter also referred to as Mw) were calculated in terms of standard polymethyl methacrylate using GPC and using an RI detector. . The heating residue (%) (hereinafter also referred to as NV) was measured according to JIS K 5601 (2005). The acid value (mgKOH) (hereinafter also referred to as AV) was measured according to JIS K 5407 (2005). Further, the polymerization rate (%) was calculated based on the heating residue measured according to JIS K 5601 (2005).

  In the present invention, the oxygen concentration in the polymerization system was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of New Cosmos Electric Co., Ltd.).

  Further, the composition ratio was a weight ratio unless otherwise specified.

Example 1
A 1 L four-necked flask (hereinafter also referred to as a polymerization apparatus) equipped with a thermometer and a stirrer is purged with nitrogen gas. The oxygen concentration was measured by “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.) and confirmed to be less than 2 vol%. 200 g (1.563 mol) of n-butyl acrylate (hereinafter also referred to as BA), 0.4 g of t-butylperoxy-benzoate (hereinafter also referred to as PO-1), bis (2,2,6) decanedioate , 6-Tetramethyl-1- (octyloxy) -4-pepyridinyl) ester (molecular weight 737) (hereinafter also referred to as HA-A1) 5.76 g (0.00782 mol) was charged, and dry nitrogen gas was bubbled for 30 minutes. The polymerization system was purged with inert gas. Hereinafter, during the polymerization, dry nitrogen gas was blown in all steps.

  The polymerization system was heated to 110 ° C. to initiate polymerization. FIG. 1 shows the relationship between the polymerization rate of BA during polymerization and Mn of the copolymer. The produced polybutyl acrylate had Mn of 25334 and Mw of 40534.

  100 g of 2-hydroxyethyl methacrylate (molecular weight 130) (hereinafter also referred to as HEMA) was further added to this system, and polymerization was continued. FIG. 2 shows the relationship between the polymerization rate of HEMA during polymerization and Mn of the copolymer. The produced polybutyl acrylate / 2-hydroxyethyl methacrylate copolymer had Mn of 51065 and Mw of 102130.

  From FIG. 1 and FIG. 2, it was confirmed that the main polymerization proceeds by living radical polymerization.

Example 2
The polymerization apparatus was purged with nitrogen gas. The oxygen concentration was measured with “XO-326ALA” (oxygen concentration meter of New Cosmos Electric Co., Ltd.) and confirmed to be less than 2 vol%. N-Butyl acrylate (BA) 196 g (1.531 mol), 2-hydroxyethylacrylamide 4 g (0.0348 mol) (hereinafter also referred to as HEAA), disuccinic acid peroxide (hereinafter also referred to as PO-2) 0.625 g, decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-pepyridinyl) ester (HA-A1) 1.20 g (0.00391 mol) were charged, 30 The polymerization system was purged with inert gas by bubbling dry nitrogen gas for a minute. Hereinafter, during the polymerization, dry nitrogen gas was blown in all steps.

  The polymerization system was heated to 93 ° C. to initiate polymerization. FIG. 3 shows the relationship between the polymerization rate during polymerization and Mn of the copolymer. The produced polybutyl acrylate / 2-hydroxyethylacrylamide copolymer had Mn of 121605, Mw of 218889, and an acid value of 1.20 mgKOH.

Example 3
In Example 2, the amount of decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-pepyridinyl) ester (HA-A1) was 3.00 g (0.00407 mol). A copolymer was produced in the same manner as in Example 2 except for changing to. FIG. 4 shows the relationship between the polymerization rate during polymerization and Mn of the copolymer. Mn of the manufactured polybutyl acrylate / 2-hydroxyethyl acrylamide copolymer was 49133, Mw was 78613, and the acid value was 1.22 mgKOH.

Example 4
The polymerization apparatus was purged with nitrogen gas. The oxygen concentration was measured with “XO-326ALA” (oxygen concentration meter of New Cosmos Electric Co., Ltd.) and confirmed to be less than 2 vol%. BA 200 g (1.563 mol), PO-1 0.4 g, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (molecular weight 481) (hereinafter referred to as HA-A2) 3.00 g ( 0.00624 mol) was charged, and dry nitrogen gas was bubbled in for 30 minutes while bubbling to replace the polymerization system with inert gas. Hereinafter, during the polymerization, dry nitrogen gas was blown in all steps.

  The polymerization system was heated to 110 ° C. to initiate polymerization. FIG. 5 shows the relationship between the polymerization rate during polymerization and Mn of the copolymer. Mn of the manufactured polybutyl acrylate was 32067 and Mw was 73754.

  From FIG. 5, it was confirmed that the main polymerization proceeds by living radical polymerization.

Example 5
While injecting nitrogen gas into the polymerization apparatus (on the way, the oxygen concentration was measured with “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.) and confirmed to be less than 2 vol%.) Ethyl acetate ( (Hereinafter also referred to as EAC) 360 g was charged and heated to 80 ° C. In another beaker, 228 g of cyclohexyl methacrylate (hereinafter also referred to as CHMA), 120 g of cyclohexyl acrylate (hereinafter also referred to as CHA), 32 g of 2-hydroxyethyl methacrylate (hereinafter also referred to as HEMA), 2- (2,2,6 , 6-tetramethyl-4-hydroxy) piperidinyloxyethyl methacrylate (hereinafter referred to as HA-B1) 20 g, t-butylperoxy-2-ethylhexanoate (hereinafter referred to as PO-3) 4. 0 g (hereinafter referred to as “mixed liquid 1”) was charged and mixed uniformly. The mixed liquid 1 is dropped into the polymerization apparatus through a constant flow pump at a constant flow rate for 180 minutes. One hour after the completion of the dropwise addition of the mixed liquid 1, 20 g of ethyl acetate (EAC), 0.2 g of t-butylperoxy-2-ethylhexanoate (PO-3), and 20 g of EAC after 1 hour, t- 0.2 g of butyl peroxy-2-ethylhexanoate (PO-3) was added and the polymerization reaction was continued at 80 ° C. for 2 hours to produce an acrylic copolymer. The acrylic copolymer had a heating residue of 50.5%, Mw 58000, and Mn 26400.

  While blowing nitrogen gas into the polymerization apparatus, 160 g of toluene (hereinafter also referred to as TOL) and 400 g of the acrylic copolymer are charged and heated to 100 ° C. MMA 80g, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole (hereinafter also referred to as R-UVA) 120g, t-butylperoxy-2-ethylhexanoate (PO- 3) 0.4g was added and the polymerization reaction was performed for 5 hours. After 3 hours, 20 g of toluene (TOL) and 0.01 g of t-butylperoxy-2-ethylhexanoate (PO-3), and after 1 hour, 20 g of toluene (TOL) and t-butylperoxy-2-ethyl 0.01 g of hexanoate (PO-3) was added, and the polymerization reaction was further continued at 100 ° C. for 2 hours to produce an acrylic copolymer.

  The acrylic resin composition had a milky appearance and was a stable liquid without separation and precipitation over time. And the heating residue was 50.5%, Mw121000, and Mn60500. As a result of UV absorption observation by GPC, a molecular weight distribution due to 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (R-UVA) copolymerization is observed on the high molecular weight side, Mw212000, Mn121100, and Mw / Mn1.75.

Example 6
400 g of ethyl acetate / n-propyl acetate (= 80/20) was charged into a 2 L flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, a stirring device, an acrylic monomer supply port, and a constant flow rate pump, and stirring was started. . Nitrogen gas was blown into the bottom of the flask and bubbling was performed for 30 minutes. It was confirmed with an oxygen concentration meter “XO-326ALA” that the oxygen concentration was 0.5 vol% or less. Thereafter, bubbling of nitrogen gas was continued during acrylic resin production.

  Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate was charged to the flask in an amount of 0.2% by weight of the acrylic monomer mixture and completely dissolved. Subsequently, benzoyl peroxide was charged in a 2-fold mol of (2,2,6,6-tetramethyl-4-piperidyl) sebacate and completely dissolved.

  The temperature increase was started and the temperature was increased to 80 ° C. in 30 minutes. Thereafter, the temperature was maintained at 80 ° C. during the production of the acrylic resin.

  An acrylic monomer mixture of n-butyl acrylate / cyclohexyl acrylate / 4-hydroxybutyl acrylate (= 75/20/5) was dropped into the flask in 2 hours.

  Sampling was started with 0 hour as the end of dropping, and the polymerization rate (hereinafter also referred to as Conv) and the number average molecular weight (hereinafter also referred to as Mn) were measured. The results are shown in FIG. From FIG. 6, it was found that the main polymerization reaction proceeds by living radical polymerization, and a high molecular weight acrylic polymer can be easily produced.

  The acrylic resin composition had a heating residue of 50.2%, a number average molecular weight (Mn) of 266,000, a weight average molecular weight (Mw) of 391,000, and Mw / Mn = 1.50.

Comparative Example 1
The polymerization apparatus was purged with nitrogen gas. 200 g (1.563 mol) of n-butyl acrylate (BA) and 1.0 g of PO-1 were charged, and blown while bubbling dry nitrogen gas for 30 minutes to replace the polymerization system with inert gas. Hereinafter, during the polymerization, dry nitrogen gas was blown in all steps.

  The polymerization system was heated to 110 ° C. to initiate polymerization. FIG. 7 shows the relationship between the polymerization rate during polymerization and Mn of the copolymer. Mn of the manufactured polybutyl acrylate was 33221 and Mw was 81999.

  As is clear from FIG. 7, the progress of living radical polymerization could not be confirmed in a system in which a compound having two or more hindered amino groups does not exist in one molecule.

Comparative Example 2
The polymerization apparatus was purged with nitrogen gas. 200 g (1.563 mol) of n-butyl acrylate (BA) and 1.2 g of PO-1 were charged, and the polymerization system was purged with inert gas while bubbling dry nitrogen gas for 30 minutes. Hereinafter, during the polymerization, dry nitrogen gas was blown in all steps.

  The polymerization system was heated to 110 ° C. to initiate polymerization. The produced polybutyl acrylate had Mn of 30,000 and Mw of 78,000.

  100 g of 2-hydroxyethyl methacrylate (molecular weight 130) (hereinafter also referred to as HEMA) was further added to this system, and polymerization was continued for 3 hours. There was no change in the molecular weight value of the copolymer before and after the addition of HEMA, and no increase in molecular weight as shown in the examples was observed.

  From the above results, it was not possible to confirm the progress of living radical polymerization in a system in which a compound having two or more hindered amino groups is not present in one molecule.

The relationship between the polymerization rate of n-butyl acrylate (BA) and the molecular weight increase behavior of an acrylic copolymer is shown. The relationship between the polymerization rate of 2-hydroxyethyl methacrylate (HEMA) and the molecular weight increase behavior of an acrylic copolymer is shown. The relationship between the polymerization progress of an acrylic copolymer and the molecular weight increase behavior is shown. The relationship between the polymerization progress of an acrylic copolymer and the molecular weight increase behavior is shown. The relationship between the polymerization progress of an acrylic copolymer and the molecular weight increase behavior is shown. The relationship between polymerization progress and molecular weight behavior of an acrylic copolymer is shown. The relationship between polymerization progress and molecular weight behavior of an acrylic copolymer is shown.

Claims (6)

   A process for producing an acrylic copolymer, wherein an acrylic monomer is radically polymerized using an organic peroxide as a polymerization initiator in the presence of a compound having two or more hindered amino groups in one molecule.   The acrylic copolymer according to claim 1, wherein the acrylic monomer is radically copolymerized in the presence of a reaction product of a compound having two or more hindered amino groups in one molecule and an organic peroxide. Method. The method for producing an acrylic copolymer according to claim 1 or 2, wherein the compound having two or more hindered amino groups in one molecule is represented by the following formula.

(Here, R1 and R2 are a hydrogen atom or a methyl group, or an alkyloxy group having 1 to 12 carbon atoms, and n represents an integer of 6 to 12) The method for producing an acrylic copolymer according to any one of claims 1 to 3, wherein the organic peroxide has a structure represented by the following formula.

(Here, it represents an alkyl group, a phenyl group, or a hydroxyalkyl group.) The method for producing an acrylic copolymer according to any one of claims 1 to 3, wherein the organic peroxide has a structure represented by the following formula.

(Here, R6 is a phenyl group, which may have a substituent.)   The method for producing an acrylic copolymer according to claim 1, wherein radical polymerization is carried out in an organic medium solution.

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