KR100787347B1 - Method of preparation for acryl syrup by controlling thermal polymerization in bulk polymerization - Google Patents

Abstract

 The present invention relates to a method for producing an acrylic syrup, and more specifically, using a 0.001 to 0.1 parts by weight of a thermal polymerization initiator having a half-life temperature of 80 ° C. or less, and 0.001 to 5 parts by weight of a chain transfer agent, based on 100 parts by weight of an acrylic ester monomer. By the bulk polymerization, but before or after the highest reaction temperature relates to a method for producing an acrylic syrup, characterized in that by injecting oxygen, for example, air to prevent thermal polymerization.

According to the present invention, by terminating the reaction effectively without using an additive including an anti-polymerizing agent for the completion of the reaction, the selection and selection of applicable initiators can be widened, thereby eliminating difficulties in handling and storage when using low temperature initiation. After the initiator disappears, it prevents unnecessary additional reaction by thermal polymerization at high temperature and controls the reaction to prepare an acrylic syrup which is easy to control conversion and molecular weight and has a relatively narrow molecular weight distribution. It is effective in providing a method for producing a stable acrylic syrup even in the production of industrial scale.

Acrylic syrup, block polymerization, thermal polymerization, air, low temperature initiator, maximum reaction temperature

Description

METHODS OF PREPARATION FOR ACRYL SYRUP BY CONTROLLING THERMAL POLYMERIZATION IN BULK POLYMERIZATION}

The present invention relates to a method for producing an acrylic syrup, and more particularly, to effectively terminate the reaction without using an additive including an polymerization inhibitor and the like to block unnecessary progress of the reaction to prepare an acrylic syrup that is easy to control conversion and molecular weight In addition, the present invention relates to a method for producing acrylic syrup that is stable even at industrial scale production by eliminating the danger of runaway reaction.

Since acrylic resin composition is excellent in transparency and hardened | cured material is easy to adjust adhesive force with respect to various base materials, use in various aspects, such as an adhesive sheet and an adhesive, is expanded.

Polymerization methods of acrylic resins disclosed in the prior art include solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like. Among them, solution polymerization, emulsion polymerization, and suspension polymerization containing solvents other than the raw material monomers during the preparation are difficult to remove the residues, which makes it difficult to apply physical properties when applied to various applications. Therefore, current technology is tending to produce acrylic syrup by bulk polymerization, which is polymerized without the presence of solvent to exclude the influence of resin residues and is advantageous in applying physical properties.

However, the bulk polymerization without using a solvent is difficult to control the heat of reaction, and the viscosity increases rapidly as the reaction proceeds, so that the reaction runaway is likely unless the reaction is terminated by a suitable method at a desired time. This risk, although at the laboratory scale, is easy to control temperature and the termination of the reaction, large scale manufacturing equipment has many limitations and risks in industrial production due to the reduction of heat transfer capacity per unit volume and the reduction of heat removal capacity due to high viscosity.

In order to overcome the difficulties of temperature control, a report has been proposed in which the form of the reactor is improved by changing the form of a semi-batch, continuous, or plug flow. Japanese Laid-Open Patent Publication No. 40-3701, Japanese Laid-Open Patent Publication No. Hei 11-255828 and Japanese Laid-Open Patent Publication No. 2000-159816 disclose such a method using a continuous polymerization method and performing polymerization at a high temperature. However, the polymerization in such a continuous reactor is a very useful method under the assumption that the mixing and residence time of the reaction liquid in the reactor is ideally constant. And gelation of some long-term retention reaction solution.

Conventional techniques proposed for the completion of the reaction and the prevention of runaway are described in Japanese Patent Laid-Open, such as a method of adding a polymerization inhibitor at the end of the reaction by slowing down the reaction temperature such as lowering the reaction temperature and a method of quenching by adding a monomer. Publication No. 9-67495.

However, the method of adding the polymerization inhibitor after the low temperature reaction, such as in the case of most bulk polymerizations, does not change the initial reaction rate at a slow rate, but when the reaction proceeds over a certain conversion rate, the rapid increase in the reaction rate due to the increase in the radical concentration and the resulting viscosity It is difficult to always obtain a certain level of conversion and viscosity by accurately predicting the end of the reaction due to the sudden rise. This difficulty is high enough to reach a high molecular weight (Mw) 100,000 or more, the viscosity reaches thousands to tens of thousands of cP is difficult to smoothly mix the polymerization inhibitor is difficult to expect the effect of the rapid termination of the reaction.

The method of quenching by the addition of monomer is used for the reaction proceeding at a relatively high temperature, and the reaction is terminated after dropping the reaction temperature to a level where the activity of the initiator is weak by injecting a monomer of room temperature or low temperature at the end of the reaction. However, since most of these methods use an initiator with a relatively high half-life temperature, it is possible to reduce the activity of the initiator by the addition of a low temperature monomer, but it is not completely decomposed, so the addition of a polymerization inhibitor is required. Otherwise, storage stability Adversely affects.

In addition, in order for the completion of the reaction by the monomer addition to be fully effective, the addition of a monomer or a low temperature monomer sufficient to sufficiently reduce the reaction liquid temperature after the monomer input below the active temperature of the initiator is required. Will result.

Recently, a method of initiating mass polymerization of an initiator which has not left a residual initiator and does not require the addition of a polymerization inhibitor has been proposed. Japanese Laid-Open Patent Publication No. 2000-313704 discloses a method in which an initiator having a low half-life temperature is used to decompose the initiator at high speed during the reaction so that a separate polymerization inhibitor is not required. This method utilizes self-heating at a reaction temperature of 20 to 80 ° C., using an amount within the range of 0.0001 to 0.5 parts by weight of a polymerization initiator having a half-life temperature of 41 ° C. or less for 10 hours, and the maximum reaction temperature of the reactants is in the range of 100 to 140 ° C. It is a method for producing an acrylic syrup having a polymerization rate of 15 to 50%. Since this type of polymerization uses self-heating, a very rapid increase in the concentration of radicals must be accompanied at the beginning of the reaction to achieve the desired purpose. It is reported that the radical concentration increased rapidly at the beginning of the reaction, and then the reaction can be stably terminated without adding the polymerization inhibitor by consuming all the initiator at high temperature after the rapid increase in the conversion rate and the maximum reaction temperature.

However, this technique overlooks the fact that the reaction proceeds by thermal polymerization without an initiator at a high temperature, which is characteristic of most bulk polymerizations, and thus, a method of fundamentally preventing unwanted reactions by thermal polymerization after initiator consumption. This did not happen. The incompleteness of this technique has resulted in limited use of low temperature initiators with low 10-hour half-life temperatures available and technical limitations that limit the maximum reaction temperature in the range of 100 to 140 ° C.

Although in the present technology, in order to prevent thermal polymerization, about 25% of monomer was added to quench the reaction temperature by the method of quenching the reaction temperature below 100 ° C. In this case, as described above, the concentration of the final solid content was lowered. In addition, when the amount of monomer input is not small enough to quench enough to control the thermal polymerization sufficiently, the introduced monomer causes the risk of reaction runaway due to the increase of unreacted raw materials.

In order to solve the problems of the prior art as described above, the present invention provides an acrylic syrup that is easy to control the conversion rate and molecular weight by blocking the progress of the unnecessary reaction by effectively terminating the reaction without using an additive including an polymerization inhibitor and the like, Furthermore, it aims at providing the manufacturing method of the acrylic syrup which is stable even in industrial scale production by eliminating the danger by reaction runaway.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention provides a method for producing an acrylic syrup containing an acrylic alkyl ester as a main component,

Inert polymerization, including 0.0001 to 0.1 parts by weight of a thermal polymerization initiator having a half-life temperature of 80 ° C. or less and 0.001 to 5 parts by weight of a chain transfer agent with respect to 100 parts by weight of an acrylic ester monomer, containing oxygen before or after the maximum reaction temperature. It provides a method for producing an acrylic syrup characterized in that the injection of a gas, for example air, to prevent thermal polymerization.

In the preparation of acrylic syrup by initiator disappearing mass polymerization, the present inventors can introduce a method of terminating the reaction by injecting air at the end of the reaction to control the progress of unnecessary reaction by high temperature thermal polymerization after the initiator disappears. After confirming this, the present invention was completed. The application of the present invention broadens the range of initiators that can be applied to the initiator disappearing bulk polymerization, eliminating the difficulties in handling and storage when using low-temperature initiators, and by controlling the high-temperature thermal polymerization after the disappearance of the initiators, And it was easy to design a molecular weight and to prepare a relatively narrow molecular weight distribution of the acrylic syrup, and further could fundamentally eliminate the risk of runaway due to the failure of reaction control.

Hereinafter, the present invention will be described in detail.

The present invention provides a bulk polymerization of a reaction composition composed of an acrylic ester monomer, a polymerization initiator, and a chain transfer agent, but has a highest reaction temperature point with rapid decomposition and termination of the polymerization initiator within a short time by using exothermic heat of the reaction system after the polymerization initiation. In order to prevent the progress of further reaction by thermal polymerization at a high temperature, a method of producing an acrylic syrup which controls the reaction by injecting an inert gas containing oxygen, for example, air.

The acrylic ester monomer is not particularly limited, and monomers generally used in the production of acrylic syrups may be used. As such an acrylic ester monomer, a copolymer of an acrylic ester monomer having an alkyl group having 1 to 12 carbon atoms and a polar acrylic ester monomer copolymerizable with the monomer may be used.

Examples of the acrylic ester monomer having an alkyl group having 1 to 12 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and iso Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, etc. can be used individually or in mixture of 2 or more types.

The polar acrylic ester monomer copolymerizable with the acrylic ester monomer has a function of imparting cohesive force to the pressure-sensitive adhesive and improving adhesion, and monomers containing carboxyl groups such as (meth) acrylic acid, maleic acid, and fumaric acid, and hydroxy (meth) acryl Monomers containing hydroxy groups such as acrylate and hydroxy (meth) methyl acrylate, monomers containing nitrogen such as acrylamide, N-vinyl pyrrolidone and N-vinyl caprolactam, and the like Can be used.

The use rate of the acrylic ester monomer and the polar acrylic ester monomer is not particularly limited, and it is generally used at a ratio of 0.5 to 2.0 parts by weight of the polar acrylic ester monomer with respect to 100 parts by weight of the acrylic ester monomer.

The copolymer of the acrylic ester monomer having an alkyl group having 1 to 12 carbon atoms and the polar acrylic ester monomer may be copolymerized by further including a styrene monomer such as styrene and benzoyl (meth) acrylate as the third unsaturated monomer.

The polymerization initiator is preferably a polymerization initiator having a half-life temperature of 80 ° C or less for a thermal polymerization initiator, and more preferably 70 ° C or less. The present invention solves difficulties in handling and storage when using a low-temperature initiator by widening the choice of the initiator applicable to the bulk polymerization of acrylic syrup by using a polymerization initiator having a half-life temperature of 80 ° C. or lower for 10 hours. .

As the polymerization initiator, azobis 2-methylbutyronitrile (2,2'-Azobis [2-methylbutyronitrile]), azobis isobutyronitrile (2,2'-Azobis [isobutyronitrile]), azobis 2 , 4-dimethylbareronitrile (2,2'-Azobis [2,4-dimethylvaleronitrile]), or azobis 4-methoxy 2,4-dimethyl vareronitrile (2,2'-Azobis [4- azo initiators such as methoxy-2,4-dimethylvaleronitrile] or methylbutyl peroxyneodecanoate (1,1,3,3-Tetramethybutyl peroxyneodecanoate), dibutylcyclohexyl peroxydicarbonate (Di [4- tert-butylcyclohexyl] peroxydicarbonate, Diethylhexyl peroxycarbonate, tert-Butyl peroxyneodecanoate, dibutyl peroxydicarbonate, dicetyl Dicetyl peroxydicarbonate, Dimyristyl peroxydicarbona te), methylbutyl peroxypivalate (1,1,3,3-Tetramethylbutyl peroxypivalate), butyl peroxyneheptanoate, tert-Amyl peroxypivalate, butyl peroxypivalate Peroxide-based initiators such as tert-Butyl peroxypivalate, dilauroyl peroxide, dydecanoyl peroxide, or dibenzoyl peroxide, or the like. It can mix and use 2 or more types.

The polymerization initiator is preferably used in 0.0001 to 0.1 parts by weight based on 100 parts by weight of the acrylic ester monomer. If the content is less than 0.0001 parts by weight, the amount of the initiator is too small, there is a problem that the reaction does not proceed, if it exceeds 0.1 parts by weight there is a problem that the gel is excessively generated by the progress of the reaction.

The chain transfer agent is used for molecular weight control, and alkyl mercaps such as ethyl mercaptan, butyl mercaptan, hexyl mercaptan, dodecyl mercaptan, and dodecyl mercaptan. Thiophenols such as carbons, phenyl mercaptan, or benzyl mercaptan, thioglycolic acid, 3-Mercapto propionic acid, or thiosalicylic acid Hydroxyl group-containing mercaptans such as carboxyl group-containing mercaptans, mercapto ethanol, or mercapto propanediol (3-Mercapto-1,2-propanediol), and the like, or pentaerythritol Also mercaptans having two or more of the above functional groups in combination, such as tetrakis mercapto propionate (Pentaerythritol tertrakis [3-mercapto] propionate) Can.

The chain transfer agent may be used in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the acrylic ester monomer. If the content is less than 0.001 parts by weight, there is a problem that the polymerization of the polymer proceeds rapidly because the molecular weight of the polymer is too large. When the content is more than 5 parts by weight, the polymerization rate is slowed and the molecular weight is too low. .

The bulk polymerization of the reactant including the acrylic ester monomer, the polymerization initiator and the chain transfer agent is selected to a temperature 10 to 20 ° C. higher than the 10 hour half-life temperature of the initiator using the reaction temperature for rapid consumption of the initiator to initiate the reaction. The reaction temperature is preferably 30 to 100 ° C, more preferably 40 to 80 ° C. If the reaction temperature is less than 30 ℃ reaction rate is too slow or difficult to form radicals, if it exceeds 100 ℃ exothermic temperature is so high that the reaction must be terminated before obtaining the desired conversion rate There is a problem.

After the initiation reaction, the temperature of the reactant rapidly rises within a few minutes to reach the maximum reaction temperature due to self-heating of the reaction system by the consumption of the initiator without the need for heating or cooling. The maximum reaction temperature varies depending on the type of initiator used, and the higher the temperature of the 10-hour half life, the higher the maximum reaction temperature.

Air is injected into an inert gas containing oxygen before or after reaching the maximum reaction temperature to prevent thermal polymerization. The present invention is characterized in that the reaction rate is controlled or effectively terminated within a short time by injecting air, thereby preventing thermal polymerization and controlling the conversion rate. However, the present invention does not have a practical limit on the maximum exothermic temperature. In order to have a viscosity, the maximum reaction temperature is preferably in the temperature range of 110 to 160 ° C.

The air injection is preferably carried out within a few minutes after the maximum reaction temperature is reached, and may be injected before the maximum reaction temperature is reached if the maximum reaction temperature is too high or a continuous temperature rise is observed.

The air injection temperature is preferably 110 to 160 ℃, the highest reaction temperature range, more preferably 120 to 150 ℃ temperature range. If the temperature is less than 110 ℃ there is a problem that the conversion and viscosity is too low due to the rapid termination of the reaction, if the temperature exceeds 160 ℃ the viscosity of the reaction solution is too high agitation efficiency is lowered, there is a problem that effective reaction control is difficult.

 The air injection may be adjusted to a desired level by controlling the content of the air to be injected.

Acrylic syrup prepared by the above production method of the present invention is an acrylic syrup partially polymerized at a solid content concentration of 10 to 60%.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Example 1

480 g of 2-ethylhexyl acrylate (2-EHA), 20 g of acrylic acid (AA), dodecyl mercaptan in a 4-neck 1 liter glass reactor equipped with a stirrer, nitrogen gas inlet, air inlet, temperature sensor and condenser 0.05 g of (n-DDM) was added thereto, and the reaction temperature was raised to 65 ° C. under sufficient mixing while removing dissolved oxygen for 30 minutes using a nitrogen stream. 10 hours of half-life temperature of 51 ° C, 0.03 g of azobis 2,4-dimethylvaleronitrile (2,2-Azobis [2,4-dimethylvaleronitrile]) was dissolved in a small amount of ethyl acetate, and dissolved oxygen was added to the initiator. The reaction was initiated. At this time, the temperature of the reactor jacket was continuously maintained at 70 ° C., which was a reaction temperature. The reaction proceeded at a rapid rate and the reaction temperature rose to a maximum temperature of 135 ° C. in 5 minutes. After reaching the highest reaction temperature, the reaction was terminated by injecting air into the reaction solution at a rate of 500 ml / min. Thereafter, the reaction temperature was lowered to 30 minutes after the start of the reaction without any cooling operation. After the air injection, the reaction temperature dropped rapidly and there was no exothermic or runaway phenomenon. Solid content concentration of the obtained partially polymerized acrylic syrup was 50.4%, viscosity was 54,000 centipoise (cP), weight average molecular weight was 400,000, molecular weight distribution was 4.5.

Example 2

0.025 g of azobis 2,4-dimethylvaleronitrile having a reaction temperature of 80 ° C. in Example 1 and a half-life temperature of 65 ° C. as an initiator. Except that was used in the same manner as in Example 1.

The reaction proceeded at a rapid rate and in 5 minutes the reaction temperature reached 145 ° C. After that, the rate of temperature increase decreased but a steady temperature increase was observed. When the reaction temperature reached 147 ° C., air was injected into the reaction solution at a rate of 500 ml / min to terminate the reaction. Thereafter, the reaction temperature was decreased to 40 minutes after the start of the reaction without any cooling operation. After the air injection, the reaction temperature dropped rapidly and there was no exothermic or runaway phenomenon. Solid content concentration of the obtained partially polymerized acrylic syrup was 57%, viscosity was 72,000 centipoise (cP), molecular weight 350,000, molecular weight distribution was 4.8.

Example 3

Except that the reaction was terminated by injecting air when the reaction temperature reached 135 ℃ in Example 2 was carried out in the same manner as in Example 2.

After the air injection, the reaction solution temperature was rapidly lowered without any cooling operation, and the reaction solution temperature was lowered to the reaction start temperature 27 minutes after the start of the reaction. Solid content concentration of the obtained partially polymerized acrylic syrup was 37%, viscosity was 32,000 centipoise (cP), molecular weight 370,000, molecular weight distribution was 3.7.

Comparative Example 1

Except that the reaction control by air injection after reaching the highest reaction temperature in Example 1 was carried out in the same manner as in Example 1.

After reaching the maximum temperature of the reaction, it took 55 minutes to proceed to thermal reaction and cooled to the reaction start temperature. The solid content of the partially polymerized acrylic syrup was 58.3%, the viscosity was 98,000 centipoise (cP), and the molecular weight was 450,000, the molecular weight distribution was wide at 5.4.

Comparative Example 2

Except that the reaction control by air injection in Example 2 was carried out in the same manner as in Example 2.

The reaction temperature continued to rise and exceeded 160 ° C., and the temperature of the reactants reached 175 ° C. so that the reaction could not be controlled any more and there was a risk of runaway reaction.

Comparative Example 3

100 g of a monomer mixture of 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA) at room temperature in order to terminate the reaction when the reaction temperature reaches 150 ° C without performing reaction control by air injection in Example 2 Was carried out in the same manner as in Example 2 except for terminating the reaction.

After the addition of the monomer, the reaction temperature was temporarily lowered to 120 ℃, but after the reaction temperature gradually increased, the reaction temperature reached 127 ℃ 20 minutes after the addition of the monomer, after which the viscosity increased so that continuous reaction temperature was not increased and stirring was impossible. In order to prevent reaction runaway, an excessive polymerization inhibitor was added to force the reaction to be terminated.

As described above, according to the present invention, in the bulk polymerization of acrylic syrup, by injecting air into an inert gas containing oxygen without using an additive including an polymerization inhibitor or the like to terminate the reaction, The wider selection of applicable initiators eliminates difficulties in handling and storage when using low-temperature initiators, prevents the progress of unnecessary reactions by thermal polymerization at high temperatures after the disappearance of the initiators, and controls the reactions to control the conversion of the polymer and It is easy to control the molecular weight and relatively narrow in molecular weight distribution to produce an acrylic syrup, and furthermore, by eliminating the risk of runaway reaction, there is an effect of providing a stable method of producing acrylic syrup even on industrial scale production.

Although described in detail above with reference to the specific embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such variations and modifications belong to the appended claims. It is also natural.

Claims (4)

In the manufacturing method of the acrylic syrup which has an acrylic alkyl ester as a main component, Inert polymerization, including 0.0001 to 0.1 parts by weight of a thermal polymerization initiator having a half-life temperature of 80 ° C. or less and 0.001 to 5 parts by weight of a chain transfer agent with respect to 100 parts by weight of an acrylic ester monomer, containing oxygen before or after the maximum reaction temperature. Method of producing an acrylic syrup, characterized in that the injection of gas to prevent thermal polymerization. The method of claim 1, The bulk polymerization is a method of producing an acrylic syrup, characterized in that the reaction temperature is started in the range of 30 to 100 ℃, after the initiation reaction reaches a maximum reaction temperature by the reaction by self-heating. The method of claim 1, The maximum reaction temperature for injecting the air is a method of producing an acrylic syrup, characterized in that 110 to 160 ℃. The method of claim 1, The acrylic syrup is a method of producing an acrylic syrup, characterized in that the partial concentration of the solid content of 10 to 60%.