KR20150051502A - Preparation Method for thermal stable Acryl resin composition - Google Patents

Abstract

The present invention relates to a manufacturing method of an acrylic resin composition with good heat stability and, more specifically, a manufacturing method of an acrylic resin composition with good heat stability in which acrylic resin used as light guide plate in TVs and personal computers is manufactured in a continuous mass polymerization and accordingly has good heat decomposition property and heat resistance property under injection molding conditions like high temperatures.

Description

[0001] The present invention relates to a method for producing an acrylic resin composition having excellent heat stability,

More particularly, the present invention relates to a process for producing an acrylic resin composition having excellent heat stability, and more specifically, to an acrylic resin used as a light guide plate in an optical apparatus such as a TV, a notebook computer, And a method for producing an acrylic resin composition having heat resistance.

BACKGROUND ART [0002] Acrylic resins containing methyl methacrylate as a main component have excellent optical properties and weatherability and are mainly applied to optical devices such as TVs and notebooks as light guide plates. The light guide plate to be applied to an optical apparatus is generally manufactured by extrusion and injection molding.

Generally, a method for producing an acrylic polymer includes continuous polymerization in which a raw material monomer and an initiator of a resin composition are continuously supplied to a reaction tank and polymerized. Such a continuous polymerization method is known as a solution polymerization using a solvent and a continuous mass polymerization method without using a solvent.

In general, the continuous solution polymerization method is low in productivity and inefficient by using a solvent. The continuous mass polymerization method has an advantage that a polymerization reaction proceeds without using a solvent and therefore a polymerization product can be produced efficiently. However, in the case of continuous bulk polymerization, there is a problem that the quality of the polymerization composition deteriorates when the inner surface of the reactor is cooled for the heat removal of the reaction system because the viscosity of the reactant is higher than the continuous solution polymerization because no solvent is used. Thus, Japanese Patent Application Laid-Open No. 07-126308 (Patent Document 1) proposes a method in which continuous bulk polymerization is carried out in a fully mixed-type reaction tank in an adiabatic state in which the reactor does not have a gaseous phase, According to Japanese Patent Application Laid-Open No. 2006-104282 (Patent Document 2), there is proposed a continuous polymerization apparatus for controlling the supply amount of raw material monomer and the supply amount of the polymerization initiator so that the temperature in the reaction tank is kept at the same temperature as the set temperature on the outer surface of the reaction tank . Further, according to Japanese Patent Laid-Open No. 2013-127048 (Patent Document 3), a continuous polymerization apparatus in which two independent reactors are provided in order to provide an acrylic resin composition having high thermal stability has been devised.

Japanese Patent Application Laid-Open No. 07-126308 (Japanese Patent) Japanese Patent Application Laid-Open No. 2006-104282 (Japanese Patent) Japanese Patent Laid-Open No. 2013-127048 (Japanese Patent)

Recently, when an acrylic resin composition is used as a light guide plate of an optical instrument through injection molding, the demand for an acrylic resin composition having high fluidity and excellent heat stability and heat resistance at high temperature is remarkably increased due to thinning and enlargement of a light guide plate. However, the conventional continuous polymerization apparatuses (Patent Documents 1 and 2) have found that it is insufficient to cope with such a demand. In the continuous polymerization apparatus claimed in Patent Document 3, a cooling apparatus is provided between two independent reactors to ensure adiabatic polymerization. Due to the temperature difference between the wall surface and the central portion of the tubular cooling apparatus that transports the high-viscosity polymer syrup, There is a problem in transportation due to the difference in viscosity of the syrup, and installation of two independent reactors is not considered to be cost-effective. It is an object of the present invention to provide a process for the production of high-molecular-weight alkoxysilanes by using an initiator in which alkoxy radicals generated in the primary decomposition of the polymerization initiator at lower polymerization temperatures are present in the alkyl radicals having low energy states by the beta season, And a method for producing an acrylic resin composition.

In order to solve the above-mentioned problems, the present invention provides a method for producing a polymer containing methacrylate, which comprises reacting a polymerization initiator selected from the group consisting of polyacyl peroxide, tertiary amyl peroxy 2-ethyl hexanoate, 1,1,3,3-tetra Methylbutylperoxy 2-ethylhexanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate is used as a polymerization initiator in the production of an acrylic polymer, .

In the method for producing an acrylic polymer according to an embodiment of the present invention, 0.01 to 1 part by weight of the higher alcohols C10 to C25 may be contained per 100 parts by weight of the monomer during the polymerization.

In the method for producing an acrylic polymer according to an embodiment of the present invention, the polymerization temperature during polymerization is 120 to 180 °, the concentration of the polymerization initiator is 0.01 to 0.1% by weight based on 100% by weight of the acrylic monomer, And the concentration may be 0.1 to 0.5 wt%.

In the process for preparing an acrylic polymer according to an embodiment of the present invention, the chain transfer agent may be selected from the group consisting of isopropyl mercaptan, normal butyl mercaptan tertiary butyl mercaptan, At least one of normal amyl mercaptan, normal-ocytyl mercaptane may be selected.

According to the method for producing an acrylic resin composition of the present invention, it is possible to produce an acrylic resin composition which does not increase the residence time only by the primary polymerization reaction, has a low weight loss rate (%) at 300 ° C and is excellent in heat resistance.

The present inventors have found that it is very important to use an effective initiator and a low polymerization temperature in order to provide an acrylic resin composition having excellent thermal stability using a continuous polymerization apparatus.

In addition, although the cause of the present invention is not clearly known, it has been found that a polymer having a high heat resistance can be obtained when 0.01 to 1 part by weight of C10 or higher alcohols, for example, C10 to C25 higher alcohols are added to 100 parts by weight of the monomer Thereby completing the present invention.

The present invention will be described in detail below. In general, the polymerization temperature influences the steric structure of the polymer. In the case of acrylic polymers, especially polymethylmethacrylate (PMMA) represented by the following formula (1), they have three steric structures depending on the arrangement of methyl groups and ester groups in the polymer chain.

[Chemical Formula 1]

(In the above formula (1), n is an integer selected from 50 to 50,000.)

In the present invention, however, it has been found that a polymer having a high heat resistance can be produced by using a low-temperature decomposition initiator, more preferably by mixing a low-temperature decomposition initiator and a higher alcohol.

In general, in the case of radical polymerization using an acrylic monomer, the selection of the initiator is generally selected in consideration of the half life of the initiator at the polymerization temperature. The amount of the polymerization initiator is set according to other conditions such as the polymerization temperature, the desired polymerization rate, and the average residence time. The lower the polymerization temperature and the shorter the average residence time, the more the initiator amount tends to increase to achieve the desired polymerization rate. However, the more the amount of the polymerization initiator is, the more unstable ends of the polymer composed of the unsaturated bonds become, which tends to deteriorate the thermal stability of the resin composition.

The present inventors have found that by using an appropriate initiator in which the alkoxy radicals generated in the primary decomposition of the initiator are present in a more stable alkyl radical by beta dissociation to ensure thermal stability at relatively low polymerization temperatures, Which is excellent in heat stability, and which has excellent thermal stability.

The present inventors have also found that by using an appropriate initiator and a higher alcohol in the presence of a more stable alkyl radical in the alkoxy radical resulting from the primary decomposition of the initiator in order to ensure thermal stability at a relatively low polymerization temperature, To thereby produce an acrylic resin composition excellent in thermal stability without increasing residence time.

Hereinafter, the present invention will be described in detail.

The continuous polymerization apparatus of the present invention refers to a device that includes one reaction tank and can perform continuous bulk polymerization in a reaction tank. That is, there is a method of continuously supplying a reactor for stirring bulk polymerization of an acrylic monomer, a stirring means for uniformly mixing reactants in a reactor, a methyl methacrylate, an alkyl acrylate, a polymerization initiator, a molecular weight regulator, A portion for continuously discharging the reactants including the methacrylic polymer in the reactor from the reactor, a defrosting extruder for recovering unreacted monomers from the discharged reactants and forming pellets of the acrylic polymer.

The acrylic monomer used in the present invention is 80 to 100% by weight of methacrylate and 0 to 20% by weight of acrylate. Accordingly, in the present invention, the acrylic monomer is a generic term of an acrylic monomer mixture in which from 100% by weight of methacrylate to 80% by weight or more but less than 100% by weight of methacrylate and from 0% by weight or more to 20% by weight or less of acrylate.

When the proportion of the methacrylate in the acrylic monomer is less than 80% by weight, there is a problem that the heat resistance is lowered. Preferably, an acrylic polymer having 90 to 95% by weight of methacrylate and 5 to 10% by weight of acrylate is used to obtain an acrylic polymer having excellent heat stability and thermal decomposition stability.

The acrylic monomer used for copolymerization with methacrylate is acrylic ester having 1 to 8 carbon atoms in acrylic acid, and the alkyl group may be a normal, isomeric or cycloalkyl group. Specific examples of the acrylic acid ester used in the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate pentyl acrylate, 2-ethylhexyl acrylate and cyclohexyl acrylate. These may be used singly or in combination of two or more May be used at the same time.

Preferably, methyl acrylate, ethyl acrylate, butyl acrylate and especially methyl acrylate are excellent in heat resistance.

In general, the lower the polymerization temperature, the higher the syndiotacticity among the three-dimensional structures of the acrylic polymer, and thus the heat resistance and the thermal decomposition stability are excellent. However, when the polymerization temperature is low, the polymerization conversion rate is low, and a large amount of initiator must be added to compensate for the polymerization conversion.

The polymerization temperature used in the present invention is a temperature at which the syndiotacticity of the acrylic polymer is 45 to 55%, preferably about 120 to 180 ° C. Preferably, the temperature is such that the syndiotacticity is from 47 to 50%, preferably from 140 to 150 ° C. When the syndiotacticity is less than 45%, heat resistance and thermal stability are not sufficient. When the proportion is more than 55%, the acrylic polymer has an excessively high glass transition temperature, which lowers the injection processability and is easily broken during injection molding of the thin film light guide plate.

Therefore, the present invention finds that by using a specific low-temperature decomposition initiator, that is, by using an initiator having a diacylperoxide and a tertiary alkyl peroxyester structure, a polymer having a well-regulated three-dimensional structure with excellent heat resistance can be obtained Thereby completing the present invention. Since the radicals generated in the first initiation reaction do not have an alkoxy radical form, diacyl peroxide has excellent thermal decomposition stability in the case of an acrylic polymer. Also, in the case of the initiator of the tertiary alkyl peroxyester structure, an alkoxy radical is generated by the first-order initiation reaction, but the alkyl radical is changed to an alkyl radical excellent in thermal decomposition stability due to beta separation faster than the case where the number of carbon atoms contained in the alkoxy radical is large When an acrylic polymer is obtained by an alkyl radical, the thermal decomposition stability is excellent. The polymerization initiator used in the present invention is an initiator in the form of diacylperoxide and tertiary alkyl peroxyester in the form of an initiator having a 10-hour half-life temperature of 55 to 85 占 폚. Diacyl peroxides initiators such as diallyl peroxide, dide decanoyl peroxide and the like, and tertiary alkyl peroxyesters may be more advantageously converted to alkyl radicals by alkoxy radicals generated in the primary decomposition of the initiator, Amyl peroxy 2-ethyl hexanoate, 1,1,3,3-tetramethyl butyl peroxy 2-ethyl hexanoate, 1,1,3,3-tetramethyl butyl peroxyneodecanoate, and the like . These initiators may be used alone or in combination of two or more.

The amount of the initiator used in the present invention may be from 0.01 to 0.1% by weight based on 100% by weight of the acrylic monomer. More preferably, it is effective to use 0.015 to 0.05 wt%. When the content of the initiator is less than 0.01% by weight, the reaction rate is low and it takes a long time to obtain the conversion of the desired acrylic monomer. When the content of the initiator is 0.05% by weight or more, the double bond at the end of the acrylic polymer increases, have.

Further, by using a specific low-temperature decomposition initiator and a higher alcohol at the same time in the present invention, it is possible to obtain a polymer having a higher heat resistance even though the cause can not be known. That is, by using an initiator having a diacyl peroxide and a tertiary alkyl peroxyester structure, it has been found that a polymer having a well-regulated three-dimensional structure with excellent heat resistance can be obtained, thereby completing the present invention.

In the present invention, it has been found that a polymer having a high heat resistance can be obtained by adding 0.01 to 1 part by weight of a higher alcohol having C10 or higher, for example, C10 to C25 higher alcohols to 100 parts by weight of the monomer, Completed. Examples of the higher alcohol include stearyl alcohol and cetyl alcohol.

In the present invention, it is not necessary to use a chain transfer agent, but it may be used for the purpose of improving strength, durability and moldability. The chain transfer agent used in the present invention may be used in an amount of 1,000 to 5,000 ppm based on 100% by weight of the monomer used. More preferably about 3,000 to 4,000 ppm, is advantageous for securing moldability and mechanical strength for injection molding.

As the chain transfer agent usable in the present invention, n-butylmale chargan, n-octylmercaptan, n-dodecylmercaptan and the like can be used. Of these, n-octylmercaptan is excellent in thermal decomposition stability. UV stabilizers and lubricants for improving moldability can also be used to increase weatherability as required.

The invention can be better understood by the following examples, which are for the purpose of illustrating the invention.

Property measurement

[Thermal Stability]

The weight change was measured using a TG-DTA apparatus (Perkin Alma pyris 6 TGA) while raising the temperature from 50 ° C to 500 ° C at a nitrogen flow rate of 20 ml / min and a heating rate of 2 ° C / min. The weight reduction ratio (weight%) between 260 and 300 degrees was calculated at a temperature of 50 占 폚 based on the weight difference between the pellets remaining at 500 占 폚 based on the weight of the pellet as 100% by weight. The smaller the weight reduction ratio, the better the thermal stability.

[Heat resistance]

Using a DSC apparatus (Perkin Almer pyris 6 DSC), the temperature was raised to 200 ° C at a rate of 20 ° C / min at a flow rate of 20 ml / min, cooled to room temperature and then heated to 200 ° C at 20 ° C / The temperature (Tg) is obtained. The higher the glass transition temperature, the better the heat resistance.

[MFR]

The pellets obtained by the bulk polymerization were measured for fluidity according to the standard of ASTM D1238.

[Moldability]

The pellets obtained by bulk polymerization were continuously supplied to a molding machine set at a predetermined cylinder temperature by a hopper, and injection molding was carried out, thereby producing a molded body. After the cylinder temperature was stabilized, the molding conditions were continuously sampled for 10 samples. The silver line incidence was measured at three different temperatures. The lower the incidence of silver line, the better the stability of pyrolysis.

Mold: 100mm x 100mm x 3mm

Molding machine: Hydraulic injection machine (LG Siltron LGH170D)

Cylinder temperature: 295, 300, 305 degrees

Injection pressure: 170 kgf / cm2

Mold temperature: 50 degrees

[Example 1]

0.95% by weight of n-octylmercaptan and 0.1% by weight of stearyl alcohol were mixed with 100 parts by weight of a monomer mixture of 95.5% by weight of methacrylate and 4.5% by weight of methyl acrylate to prepare a raw material monomer mixture 1. Amyl peroxy 2-ethylhexanoate and 0.35% by weight of n-octylmercaptan were mixed with 95.5% by weight of methacrylate and 4.5% by weight of methyl acrylate to prepare a polymerization initiator mixture 2. The polymerizable monomer mixture 1 and the polymerization initiator mixture 2 were supplied to the reaction tank at a flow rate ratio of 95: 5 so that the average residence time was 37 minutes. As in the reaction conditions shown in Table 1 below, the polymerization temperature in the reactor was 140 ° C, and the temperature of the jacket surrounding the reactor wall was also maintained at 140 ° C to carry out continuous bulk polymerization in an adiabatic state substantially free from heat. The polymerization solution passed through the reaction tank was heated at 200 ° C in a preheater and discharged, and the monomer was recovered in a defrosted extruder and an acrylic polymer was obtained as pellets. The obtained acrylic polymer pellets were measured for heat resistance using DSC, pyrolysis stability using TGA, and incidence of hidden lines through injection molding.

[Example 2]

Except that the polymerization initiator was changed to 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate.

[Example 3]

The procedure of Example 1 was repeated with the polymerization conditions described in Table 1, except that stearyl alcohol was not used in Example 1.

[Comparative Example 1]

Except that 1,1-di (tertiarybutylperoxy) cyclohexane was used as a polymerization initiator and the polymerization temperature was 175 占 폚 and bulk polymerization was carried out.

[Comparative Example 2]

The polymerization was carried out in the same manner as in Comparative Example 1 under the polymerization conditions shown in Table 1, except that the polymerization temperature was 155 캜.

[Table 1] Polymerization conditions

Polymerization conversion, fluidity, thermal decomposition stability (weight loss rate of 260-300 ° C) and glass transition temperature are shown in Table 2 below.

[Table 2]

Table 3 below shows the incidence of bad line failures in the above Examples and Comparative Examples.

[Table 3]

As shown in Tables 2 to 3, it was confirmed that when an acrylic polymer was produced by the method claimed in the present patent, an acrylic polymer excellent in heat resistance and thermal decomposition stability could be produced while maintaining excellent processability.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is clear that the present invention can be suitably modified and applied in the same manner. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (4)

A method for producing a polymer containing methacrylate, which comprises reacting a polymerization initiator selected from the group consisting of polyacyl peroxide, tertiary amyl peroxy 2-ethyl hexanoate, 1,1,3,3-tetramethyl butyl peroxy 2-ethyl hexanoate , 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the like. The method for producing an acrylic polymer is characterized in that polymerization is carried out using at least one initiator selected from the group consisting of 1,1,3,3-tetramethylbutyl peroxyneodecanoate.
The method of claim 1, wherein
Wherein the polymerization is carried out in the presence of 0.01 to 1 part by weight of the higher alcohol of C10 to C25 per 100 parts by weight of the monomer during the polymerization.
The method according to claim 1,
Wherein the polymerization temperature is in the range of 120 to 180 °, the concentration of the polymerization initiator is 0.01 to 0.1% by weight based on 100% by weight of the acrylic monomer, and the concentration of the chain transfer agent is 0.1 to 0.5% by weight
The method of claim 3,
Examples of the chain transfer agent include isopropyl mercaptan, normal butyl mercaptan, tertiary butyl mercaptan, normal amyl mercaptan, n-octyl mercaptan, normal-ocytyl mercaptane). < / RTI >