KR100689635B1 - Acrylate Copolymer - Google Patents

Abstract

The present invention relates to a method for preparing a methacryl resin suspension polymer having improved light transmittance and stable processing thermal stability, and using at least one initiator as an initiator in suspension polymerization with methyl methacrylate alone or with at least one comonomer, It is characterized by polymerization using a chain transfer agent and a crosslinking agent.

High heat resistance, high permeability, acrylic polymer

Description

High heat resistance, high permeability acrylic suspension polymer

The present invention relates to an acrylic resin having high heat resistance and high permeability, and to a suspension polymerization composition of polymethyl methacrylate (PMMA) which is a polymer of methyl methacrylate (MMA).

Polymethyl methacrylate is a resin which is polymerized by methyl methacrylate alone or prepared by a suspension polymerization process using methyl methacrylate and another kind of acrylate monomer as a comonomer.

Polymethyl methacrylate is a typical transparent resin that is used in various fields that require transparency because of excellent transparency and weather resistance and excellent mechanical properties. In particular, the recent growth of the display industry has attracted great attention as demand for such transparent materials is greatly increased. In particular, polymethyl methacrylate is widely used as a material for various optical fields such as a light guide plate, which is a liquid crystal display backlight material, and a front plate of a mobile phone, because it has a transmittance superior to any material in light transmittance. By the way, these high light transmittance polymethyl methacrylate is mainly produced by the bulk polymerization method, the optical properties of the polymethyl methacrylate produced by the general suspension polymerization is a large number of additives compared to that produced by the bulk polymerization method It is known to fall somewhat. Therefore, the polymethyl methacrylate used in the optical material field is mostly used by the bulk polymerization method, but the bulk polymerization process has a large investment cost and difficulty in the process compared to the suspension process. However, the suspension process is easy to control the reaction heat, and the investment cost is low, making the production more economically useful.

In particular, in the light guide plate manufactured by injection molding of the light guide plate, polymethyl methacrylate prepared by suspension polymerization has a disadvantage in that processing stability is significantly lower than that of a product due to bulk polymerization due to deterioration of physical properties due to a decrease in molecular weight. For this reason, the polymethyl methacrylate for injection for light-guide plate use is the situation where the Japanese product manufactured by the mass polymerization method is employ | adopted.

In general, thermal decomposition of a resin occurs by thermal history during thermal processing such as extrusion, injection molding, etc., which is known as one of important factors to lower the optical and mechanical properties of the resin. Due to this thermal history, polymethyl methacrylate for injection use is more easily influenced by suspension polymerization products than bulk polymerization products, and thus has limitations in being used for optical rather than general use.

An object of the present invention is to provide a method for producing a methacryl resin having excellent light transmittance and stable processing heat stability and a polymer thereof.

In addition, an object of the present invention is to provide an acrylic polymer having high heat resistance and high permeability prepared by suspension polymerization.

The present invention relates to an acrylic resin having high heat resistance and high permeability, and to a composition of a methacryl resin suspension polymer having improved light transmittance and stable processing thermal stability.

The composition of the present invention is methyl methacrylate alone or methyl methacrylate 80 to 99.9% by weight in the suspension polymerization of methyl methacrylate alone or a polymer of at least 80 parts by weight of methyl methacrylate relative to 100 parts by weight of the monomer mixture And 0.01 to 1, preferably 0.05 to 0.2 parts by weight, using one or more initiators, based on 100 parts by weight of the monomer mixture consisting of 0.1 to 20% by weight of comonomer, preferably 3 to 15% by weight, The chain transfer agent is characterized in that the suspension polymerization using 0.01 to 1.0, preferably 0.1 to 0.5 parts by weight and the crosslinking agent to 0.01 to 2.0, preferably 0.02 to 1.0 parts by weight.

In the present invention, the comonomer is preferably an alkyl acrylate or acrylate consisting of 2 to 8 carbons.

The polymerization initiator used in the present invention is characterized by using a half-life of 60 hours or less for 10 hours, when using such an initiator does not occur yellowing phenomenon can be prepared an optical transparent resin having excellent light transmittance. . As the initiator, for example, 2,2'-azobis2,4-dimethyl-valeronitrile (2,2'-Azobis (2,4-dimethyl-valronitrile)), 2,2'-azobis 4-methoxy-2,4-dimethyl valeronitrile ((2,2'-Azobis (4-methoxy-2,4-dimethyl valeronitrile)), α, α'-bis neodecanoyl peroxy diisopropyl benzene (α, α'-bis (neodecanoyl peroxy) diisopropyl benzene), isobutyryl peroxide, cumyl peroxyneodecanoate, di-normal-propyl peroxy dicarbonate (Di-normal -propyl peroxy dicarbonate), Diisopropyl peroxy dicarbonate, 1,1,3,3, -tetramethylbutyl peroxy neodecanoate (1,1,3,3, -tetramethylbuthyl peroxyneodecanoate) 1-cyclohexyl-1-methylethyl peroxyneodecanoate, Di-2-ethoxyethyl peroxy dicarbonate, di- 2-ethoxyhex Di-2-ethoxyhexyl dicarbonate, tertary-hexyl peroxyneodecanoate, Dimethoxybutyl peroxy dicarbonate, bis 3-methyl-3methoxy Butyl peroxy dicarbonate (Bis (3-methyl-3-methoxybutyl) peroxy dicarbonate), tertiary-butyl peroxyneodecanoate, tertiary-hexylperoxypivalate , Tertiary-butylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide (3,5,5-trimethylhexanoyl peroxide) and the like can be used.

It is also possible to use a high temperature initiator having a half life of 10 hours at 70 ° C or more as the initiator.

In the present invention, a chain transfer agent was used for molecular weight control and thermal stability improvement of polymethylmethacrylate. The molecular weight can be controlled by the amount of the initiator, but when the polymerization reaction is stopped by the chain transfer agent, the end of the chain becomes the second carbon structure, and when the chain transfer agent is not used, the end of the chain having a double bond by disproportionation is not used. Since the bond strength is stronger than that, it has a more stable structure against heat, thereby improving the optical properties of the methyl methacrylate resin.

Suitable chain transfer transfer agents are alkyl mercaptans having 1 to 12 carbon atoms in the alkyl group and one thiol functional group, or polythiol mercaptans having two or more thiol functional groups.

Alkyl mercaptans include isopropyl mercaptan, normal butyl mercaptan, tertiary butyl mercaptan, normal-amyl mercaptan, and normal-octyl Normal-octyl mercaptan, normal-dodecyl mercaptan and the like can be used.

Polythiol mercaptan can be represented by the formula (1),

[Formula 1]

(HS-Y) n-X

Wherein HS is a thiol functional group, n is an integer of 2 to 6, X is a central group, Y is a bonding group, and preferred central group X is at least glycerol, sorbitol, pentaerythritol ( pentaerythritol, di-pentaerythritol, tri-pentaerythritol, tri-methylolethane, tri-methylolpropane, pentahydroxypentane, tree And one selected from tri-quinoyl and inositol, and the bonding group Y is an alkylate having 2 to 5 carbon atoms.)

Suitable examples of such polythiol mercaptans include trimethylolethane tris (3-mercaptopropionate) and pentaerythritol tetra (pentaerythritol tetra). 3-mercaptopropionate)), pentaerythritol tetrathioglycolate, trimethylolethane trithioglycolate, trimethylolpropane tris (3-mercaptopropionate tris (3-mercaptopropionate) ), Trimethylol propane triglycolate.

However, when a large amount of chain transfer agent is added, the length of the chain becomes too short, which causes a decrease in mechanical properties. Therefore, to maintain the role of the chain transfer agent, while trying to devise a new method in order not to lower the mechanical properties, as a result of using a crosslinking agent.

The crosslinking agent used in the present invention may use a conventional multifunctional crosslinking agent which can be used as an oil-soluble crosslinking agent. Divinyl benzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1 Choose from 1,3-butylene glycol dimethacrylate, aryl methacrylate and 1,3-butylene glycol diacrylate It is preferable to use at least 1 type by 0.01-2.0 weight part, Preferably it uses 0.02-1.0 weight part.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the Examples are provided to illustrate the present invention and the present invention is not limited thereto.

Example 1

With respect to 100 parts by weight of the monomer mixture consisting of 95% by weight of methyl methacrylate and 5% by weight of methyl acrylate, 2,2'-azobis 2,4-dimethyl-valeronitrile (2,2'-Azobis ( 2,4-dimethyl-valeronitrile) 0.1 part by weight, 200 parts by weight of water, 0.9 parts by weight of a polymer (Degussa, Rohagit Smv) which neutralized a copolymer of methyl methacrylate-methacrylic acid with NaOH as a suspending agent 0.15 parts by weight of sodium dihydrogen phosphate and disodium hydrogen phosphate were added at a weight ratio of 2: 1. Normal-octylmercaptan was added 0.3 parts by weight to 100 parts by weight of the monomer mixture as a chain transfer agent. 0.025 parts by weight of ethylene glycol dimethacrylate (EDGMA) was used as a crosslinking agent, the reaction was carried out at a reaction temperature of 65 ° C. for 60 minutes, and further polymerization was performed at 120 ° C. for 15 minutes to remove residual monomers.

The polymerized beads were washed with a dehydrator and dried in a drier for 24 hours. Molecular weight was measured by gel permeation chromatography (GPC) using polymethyl methacrylate as a standard sample.

The glass transition and pyrolysis temperatures were measured using a Pyris 6 differential scanning thermal analyzer (DSC) and a thermogravimetric analyzer (TGA).

The transmittance was measured by total light transmittance by extruding suspension polymerized beads into pellets and extruding them into 150 mm specimens.

Example 2

The polymerization was carried out under the same conditions as those of Example 1, using 0.3 parts by weight of normal octyl mercaptan and 0.05 parts by weight of ethylene glycol dimethacrylate as the chain transfer agent with respect to 100 parts by weight of the monomer mixture.

 Example 3

 The polymerization was carried out in the same manner as in Example 1, except that 0.3 parts by weight of normal octyl mercaptan and 0.15 parts by weight of ethylene glycol dimethacrylate were used as a chain transfer agent in 100 parts by weight of the monomer mixture.

 Example 4

 The polymerization was carried out in the same manner as in Example 1, except that 90 parts by weight of methyl methacrylate and 10 parts by weight of methyl acrylate were used based on 100 parts by weight of the monomer mixture.

Example 5

The polymerization was carried out in the same manner as in Example 4, except that 0.3 parts by weight of normal octyl mercaptan and 0.15 parts by weight of ethylene glycol dimethacrylate were used as a chain transfer agent in 100 parts by weight of the monomer mixture.

Example 6

In Example 4, polymerization was carried out in the same manner as in Example 4, except that 0.35 part by weight of normal octyl mercaptan and 0.025 part by weight of ethylene glycol dimethacrylate were used as the chain transfer agent.

Example 7

In Example 1, polymerization was carried out in the same manner as in Example 1 except that 0.4 part by weight of normal octyl mercaptan and 0.15 part by weight of ethylene glycol dimethacrylate were used as the chain transfer agent.

The results are shown in Table 1.

Comparative Example 1

2,2'-azobis 2,4-dimethyl-valeronitrile [(2,2'-Azobis) as an initiator based on 100 parts by weight of a monomer mixture composed of 96% by weight of methyl methacrylate and 4% by weight of methyl acrylate (2,4-dimethyl-valeronitrile)] (ADVN) 0.1 part by weight, 200 parts by weight of water, a polymer obtained by neutralizing the copolymer of methyl methacrylate-methacrylic acid with NaOH (Degussa, Rohagit Smv) 0.9 as a suspending agent. A total of 0.15 parts by weight of sodium dihydrogen phosphate and disodium hydrogen phosphate were added in a weight ratio of 2: 1 by weight and a buffer salt, 0.3 parts by weight of normaloctyl mercaptan, based on 100 parts by weight of the monomer mixture, as a chain transfer agent. The reaction was carried out at a reaction temperature of 65 ° C. for 60 minutes and further polymerization was performed at 120 ° C. for 15 minutes to remove residual monomer.

The polymerized beads were washed with a dehydrator and dried in a drier for 24 hours.

Comparative Example 2

The polymerization was carried out in the same manner as in Example 1, except that 0.025 parts by weight of pentaerythritol was used as the crosslinking agent in Example 1. The results are shown in Table 1.

Table 1

Note: The decomposition temperature is defined based on the vertex of the derivative in the TGA decomposition curve.

As shown in Table 1, the embodiment according to the present invention has a decomposition temperature of 375 ° C. or more, a transmittance of 89% or more, and a molecular weight of 90,000 or more to obtain a very high molecular weight, thereby improving mechanical properties. At the same time.

In particular, it is possible to produce a polymer having heat resistance by improving optical properties and decomposition temperature.

The present invention provides a method for producing a methyl methacrylic resin suspension polymer which is excellent in thermal stability and optical properties compared to the prior art and can obtain a high molecular weight polymer to improve mechanical properties.

Claims (9)

Half-life at 60 ° C. or less, based on 100 parts by weight of a methyl methacrylate alone or a monomer mixture composed of 80 to 99.9% by weight of methyl methacrylate and 0.1 to 20% by weight of alkyl acrylate or acrylate consisting of 2 to 8 carbons 0.01 to 1.0 parts by weight of a low temperature initiator, 10 to 0.01 parts by weight of a chain transfer agent, and 0.01 to 2.0 parts by weight of a crosslinking agent, and have a thermal decomposition temperature of 375 ° C or higher, a number average molecular weight of 90,000 or more, and a transmittance of 89% or more. A high heat resistant high permeability acrylic suspension polymer prepared by suspension polymerization. delete delete delete The method of claim 1, As the chain transfer agent, a high heat-resistant high-temperature agent comprising alkyl mercaptan having 1 to 12 carbon atoms in the alkyl group and having one thiol functional group or polythiol mercaptan having two or more thiol functional groups is used. Permeable Acrylic Suspension Polymer. The method of claim 5, The polyvinyl meraptan is trimethylolethane tris (3-mercaptopropionate), trimethylolethane tris (3-mercaptopropionate), pentaerythritol tetra (3-mercaptopropionate) (pentaerythritol tetra (3-mercaptopropionate) ), Pentaerythritol tetrathioglycolate, trimethylolethane trithioglycolate, trimethylolpropane tris (3-mercaptopropionate), trimethyl A high heat resistant high permeability acrylic suspension polymer, characterized in that any one or more selected from all propane triglycolate (trimethylpropane trithioglycolate). The method according to any one of claims 1, 5 and 6, The crosslinking agent is divinyl benzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate And aryl methacrylate and 1,3-butylene glycol diacrylate. A high heat resistant high permeability acrylic suspension polymer, characterized by using at least one selected from the group. A light guide plate manufactured using the polymer of claim 7. An LCD backlight manufactured using the light guide plate of claim 8.