JP2011252098A - Method of manufacturing methacrylic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of high productivity, which can obtain a methacrylic resin having high heat resistance by a short polymerization time.SOLUTION: The method of manufacturing a methacrylic resin comprises curing a polymerizable mixture which includes: a monomer mixture which comprises a methyl methacrylate monomer or methyl methacrylate as a principal component; and a methyl methacrylate polymer in which tacticity in a methyl methacrylate unit chain is at least 80 by a triad expression (%rr), on a condition of a temperature of at most 40°C and an active energy ray irradiation strength of 1-30 mW/cm.

Description

  The present invention relates to a method for producing a methacrylic resin.

  In addition to features such as ease of processing, ease of handling, light weight, and low cost, methacrylic resin has high transparency and low birefringence, so it can be used in optical applications such as protective films for liquid crystal displays and mobile phone front plates. Widely used as a material.

  In addition, with the recent thinning of the housing, not only miniaturization or thinning of members but also more excellent functions and performance are required.

  In response to such demands, various properties such as high strength, heat resistance, and weather resistance are important for methacrylic resins in addition to the conventional light transmittance. For example, a light guide plate used in an edge light type thin liquid crystal display requires high heat resistance because it is strongly influenced by heat from an LED lamp as a light source.

  It is known that a methyl methacrylate polymer, which is a typical methacrylic resin, is superior in heat resistance as the tacticity increases.

  One method for obtaining a methyl methacrylate polymer having high tacticity is an anionic polymerization method or a coordinated anionic polymerization method, but these methods require expensive organometallic compounds as polymerization initiators. There is a problem that the cost becomes high. In addition, the polymers obtained by these methods are easily colored by the remaining organometallic compound, which may be a fatal defect for a methacrylic resin characterized by transparency.

  As another method for obtaining a methyl methacrylate polymer having high tacticity, for example, Patent Document 1 discloses that an isotactic methyl methacrylate polymer is dissolved in a monomer mainly composed of methyl methacrylate. A method for producing a methacrylic polymer, characterized in that radical polymerization of the syrup prepared in a non-solvent at 50 ° C. or lower is proposed, and it is disclosed that a methacrylic polymer having high heat resistance can be obtained.

  Further, Patent Document 2 discloses a polymer containing a syndiotactic poly (methyl methacrylate) chain unit having a syndiotacticity of 76 or more in triplet representation (% rr), and a single monomer mainly composed of methyl methacrylate. A syndiotactic poly (methacrylic acid) comprising at least a step of polymerizing a polymerizable composition having a SVI value of 1.3 or more according to JIS K 7117 in the presence of a polymerization initiator at 85 ° C. or less. A method for polymerizing a polymer containing a methyl) chain unit has been proposed, and it is disclosed that a methacrylic polymer having high heat resistance can be obtained.

  However, the methods according to Patent Document 1 and Patent Document 2 have a problem that the polymerization time is long and the productivity is low.

JP-A-8-301937 JP 2001-89528 A

  An object of the present invention is to provide a production method for obtaining a methacrylic resin having high heat resistance in a short polymerization time.

In the present invention, methyl methacrylate monomer or a monomer mixture containing methyl methacrylate as a main component (hereinafter referred to as “the present monomer component”), and tacticity in the methyl methacrylate unit chain are expressed in triads (% rr) A polymerizable mixture containing a methyl methacrylate polymer (hereinafter referred to as “the present methyl methacrylate polymer”) having a molecular weight of 80 or more is 40 ° C. or less and the active energy ray irradiation intensity is 1 to 30 mW / cm ² . The gist is a method for producing a methacrylic resin cured under conditions.

  Since the methacrylic resin having high heat resistance can be produced at low cost according to the present invention, it can be suitably used for in-vehicle applications such as automobiles and various applications such as light guide plates.

This monomer component

The present monomer component in the present invention is a methyl methacrylate monomer or a monomer mixture mainly composed of methyl methacrylate. This monomer component is a monomer containing 50 to 100% by mass of methyl methacrylate and 0 to 50% by mass of another monomer copolymerizable with methyl methacrylate (hereinafter referred to as “other monomer”). It is preferably a monomer or a monomer mixture.

  Examples of other monomers include methyl acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) I-butyl acrylate, t-butyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth) (Meth) acrylic acid esters such as 2-ethylhexyl acrylate, 2-hydroxyethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoroethyl (meth) acrylate, and pentafluoroethyl (meth) acrylate Aromatic vinyl compounds such as styrene and α-methylstyrene; acrylonitrile, methacrylo Vinyl cyanides such as tolyl; maleimide compounds such as phenylmaleimide and cyclohexylmaleimide; unsaturated carboxylic acid anhydrides such as maleic anhydride; alicyclic olefin derivatives such as dicyclopentadiene and norbornene; and polyalkylene glycol di (meth) Examples thereof include monomers having two or more double bonds in the molecule, such as acrylic ester, allyl (meth) acrylate, and divinylbenzene. These can be used alone or in combination of two or more.

  In the present invention, “(meth) acrylic acid” means “acrylic acid” or “methacrylic acid”.

Other monomers include methyl acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate in terms of solubility in methyl methacrylate and polymerizability. N-butyl (meth) acrylate, i-butyl (meth) acrylate and t-butyl (meth) acrylate are preferred.

This methyl methacrylate polymer

The methyl methacrylate polymer in the present invention has a methyl methacrylate unit chain tacticity of 80 or more in triad display (% rr). By setting the tacticity of the present methyl methacrylate polymer to 80 or more, the tacticity of the resulting methacrylic resin can be increased, and high heat resistance tends to be obtained.

  Examples of the methyl methacrylate polymer include a homopolymer of methyl methacrylate and a copolymer containing methyl methacrylate units.

  When the methyl methacrylate polymer is a copolymer, examples of the raw material for constituting other monomer units other than the methyl methacrylate unit in the methyl methacrylate polymer include, for example, the monomer The monomer similar to the other monomer in a component is mentioned.

  As content of the methyl methacrylate unit in the copolymer containing a methyl methacrylate unit, 20 mass% or more is preferable and 50 mass% or more is more preferable at the heat resistant point of the methacryl resin obtained.

  The methyl methacrylate polymer is preferably polymethyl methacrylate, which is a homopolymer of methyl methacrylate.

  Examples of the method for producing the present methyl methacrylate polymer include an anionic polymerization method disclosed in JP-A-3-26312, JP-B-6-89054, JP-A-10-182659, or a low-temperature radical. A polymerization method is mentioned. In the case of the anionic polymerization method, the polymerization temperature is preferably −100 ° C. or higher. The polymerization temperature is preferably 100 ° C. or lower, more preferably 50 ° C. or lower, and further preferably 0 ° C. or lower.

The mass average molecular weight (hereinafter referred to as “Mw”) in terms of polystyrene in the gel permeation chromatography method of the methyl methacrylate polymer is preferably 50,000 to 150,000. When Mw is 50,000 or more, the resulting methacrylic resin tends to have good heat resistance. Moreover, when Mw is 150,000 or less, the viscosity of the polymerizable mixture described later does not become too high, and good productivity tends to be maintained.

Polymerizable mixture

The polymerizable mixture in the present invention contains the present monomer component and the present methyl methacrylate polymer.

  Moreover, an active energy ray polymerization initiator can be contained in the polymerizable mixture.

  As content of this methyl methacrylate polymer in a polymeric mixture, 10-20 mass parts is preferable with respect to a total of 100 mass parts of this monomer component and this methyl methacrylate polymer, and 12-18. Part by mass is more preferable. The content of the methyl methacrylate polymer in the polymerizable mixture is 20 parts by mass or less, and the methyl methacrylate polymer tends to be easily dissolved in the monomer component. Further, when the content of the present methyl methacrylate polymer in the polymerizable mixture is 10 parts by mass or more, the methacrylic resin obtained has high tacticity and tends to have good heat resistance.

  In the present invention, the polymerizable mixture may contain various compounds such as a thermal polymerization initiator, an antioxidant, an ultraviolet absorber, a dye / pigment, and a release agent, if necessary.

  Examples of the active energy ray polymerization initiator used in the present invention include acetophenone-based or benzophenone-based active energy ray polymerization initiators.

  Specific examples of the active energy ray polymerization initiator include 1-hydroxy-cyclohexyl-phenyl ketone (for example, Irgacure 184 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd.), 2-hydroxy-2-methyl-1- Examples include phenylpropan-1-one (for example, Darocur 1173 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd.) and benzoin ethyl ether (for example, Seikol BEE (trade name) manufactured by Seiko Chemical Co., Ltd.).

The addition amount of the active energy ray polymerization initiator is preferably 0.001 to 3 parts by mass, and preferably 0.005 to 0.5 parts by mass with respect to 100 parts by mass in total of the monomer component and the methyl methacrylate polymer. Part is more preferred. When the addition amount of the active energy ray polymerization initiator is 0.001 part by mass or more, the active energy ray irradiation time tends to show good curability in a short time of about 1 hour. Moreover, when the addition amount of the active energy ray polymerization initiator is 3 parts by mass or less, the molecular weight of the obtained methacrylic resin can be made appropriate, and yellowing of the methacrylic resin tends to be suppressed.

Methacrylic resin

In the present invention, the methacrylic resin can be obtained by irradiating the polymerizable mixture with an active energy ray and curing it. The shape of the resulting methacrylic resin is not particularly limited. For example, a polymerizable layer that is a layered material is formed from the polymerizable mixture and cured to obtain a sheet-like material.

  When forming the polymerizable layer, for example, a method of forming the polymerizable layer is obtained by sealing between the end portions of the two opposing glass plates or between the opposing metal plate and the end portions of the glass plate with a sealing material. And a method of forming the mixture by pouring a polymerizable mixture into a mold.

  Further, as a method for forming a continuous polymerizable layer, for example, a polymerizable mixture is placed in a mold formed between an endless belt to be transferred and an active energy ray-permeable film continuously supplied facing the endless belt. Continuous polymerization on the surface of the substrate by supplying a polymerizable mixture between the method of supplying and forming a continuous polymerizable layer, or a rotating roll and a substrate such as an active energy ray transmissive film continuously supplied A method of forming a conductive layer.

  The thickness of the polymerizable layer is preferably 5 mm or less from the viewpoint that the polymerizable layer can be uniformly polymerized.

In the present invention, the polymerizable mixture is cured under conditions of 40 ° C. or lower and an active energy ray irradiation intensity of 1 to 30 mW / cm ² .

  The polymerization temperature at which the polymerizable mixture is cured by irradiation with active energy rays is 40 ° C. or less in view of the heat resistance of the resulting methacrylic resin. The polymerization temperature is preferably 10 ° C. or higher in terms of short-time polymerization.

  Examples of active energy rays include X-rays, ultraviolet rays, and electron beams.

  Examples of the ultraviolet lamp include a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, a germicidal lamp, a black light, and an ultraviolet LED.

The irradiation intensity of the active energy ray is 1 to 30 mW / cm ² . By setting the irradiation intensity of the active energy ray to 1 mW / cm ² or more, polymerization in a short time of about 1 hour or less is possible, and a methacrylic resin can be obtained at low cost. Moreover, the molecular weight of the methacrylic resin obtained by making the irradiation intensity | strength of an active energy ray into 30 mW / cm < ² > or less can be made appropriate, and yellowing of a methacrylic resin can also be suppressed.

  The Mw of the methacrylic resin is preferably 100,000 or more from the viewpoint of heat resistance.

Hereinafter, the present invention will be described with reference to examples. In the following, “part” and “%” indicate “part by mass” and “% by mass”, respectively. Further, the tacticity of the methyl methacrylate polymer and the methacrylic resin in the methyl methacrylate unit chain, and the Mw and glass transition temperature (hereinafter referred to as “Tg”) of the methacrylic resin were measured and evaluated by the following methods.
(1) Tacticity Using a proton nuclear magnetic resonance spectrum measuring apparatus (manufactured by Varian UNITY, trade name: INOVA500), spectra were measured using deuterated dimethyl sulfoxide as a solvent. The measurement temperature was 120 ° C., and the number of integrations was 10,000.

The obtained spectra, calculate the tacticity of a methyl methacrylate unit chain using integrated intensity of the peak derived from alpha-CH ₃ group, shown in triad display (% rr).
(2) Mw
Mw was measured using gel permeation chromatography (trade name: HPLC-8220GPC, manufactured by Tosoh Corporation) and tetrahydrofuran as an eluent.

Separation column consists of two TSK-GEL SUPER HM-H (6.0 mmφ × 150 mm) manufactured by Tosoh Corporation, with a flow rate of 0.6 ml / min, a detector as a differential refractometer, and a measurement temperature of 40 ° C. and injection. The volume was 10 μl. A polystyrene standard calibration curve was used to determine Mw.
(3) Tg
Using a differential scanning calorimeter (trade name: DSC6220, manufactured by SII), the temperature was raised from room temperature to 200 ° C. at a rate of 20 ° C./min, and then cooled to −50 ° C. at the same rate. Later, the temperature was raised again at a rate of 20 ° C./min to obtain Tg, and the heat resistance was evaluated.
[Production Example 1] Production of methyl methacrylate polymer (1) To 900 ml of toluene, 100 ml of methyl methacrylate and 1.7 g of organic samarium complex [(BHT) ₂ Sm (II) (thf) ₃ ] were mixed, and -78 Polymerization was carried out at 6 ° C for 6 hours. The obtained polymer was reprecipitated with a reprecipitation solvent having a composition of 90% methanol and 10% 0.1N hydrochloric acid, and vacuum dried at 80 ° C. for a whole day and night to obtain a methyl methacrylate polymer (1). . The tacticity in the methyl methacrylate unit chain of the methyl methacrylate polymer (1) was 89.2, and Mw was 125,000. The organic samarium complex [(BHT) ₂ Sm (II) (thf) ₃ ] is synthesized from (BHT) ₂ Sm (II) (thf) ₄ described in Example 1 of JP-A-10-182659. Obtained by the same method as the method. Here, BHF represents 2,6-di-t-butyl-4-methylphenoxide, and thf represents tetrahydrofuran.
[Production Example 2] Production of methyl methacrylate polymer (2) JP-A-2003-327605, except that the monomer composition was 99.5 mass% methyl methacrylate and 0.5 mass% methyl acrylate. A methyl methacrylate polymer (2) was obtained in the same manner as described in the publication. The tacticity in the methyl methacrylate unit chain of the methyl methacrylate polymer (2) was 58, and the Mw was 97,000.
[Example 1]
In 85 parts of methyl methacrylate, 15 parts of the methyl methacrylate polymer (1) was heated and dissolved with stirring at 80 ° C. for 30 minutes to obtain a liquid (syrup).

  100 parts of the resulting syrup is blended with 0.5 part of Irgacure 184 (Ciba Specialty Chemicals Co., Ltd. 1-hydroxy-cyclohexyl-phenyl ketone, trade name) as an active energy ray polymerization initiator to prepare a polymerizable mixture. Adjusted and allowed to cool to room temperature.

After injecting the above polymerizable mixture into a 3 mmφ × 300 mm ampoule tube, the ampoule tube is placed in a hot water bath adjusted to 35 ° C., and a chemical lamp (trade name: FL30S-BL lamp, manufactured by Toshiba Corporation) is used. And polymerized at 35 ° C. for 1 hour at an irradiation intensity of 1 mW / cm ² .

Then, after the ampoule tube was cooled to room temperature, the methacrylic resin was taken out from the ampoule tube, dissolved in acetone, and reprecipitated with 10 times equivalent of n-hexane. The obtained methacrylic resin was vacuum-dried at 60 ° C. all day and night, and the tacticity, Mw and Tg in the methyl methacrylate unit chain were evaluated. The obtained results are shown in Table 1.
[Example 2]
Polymerization is carried out in the same manner as in Example 1 except that 0.1 part of an active energy ray polymerization initiator is added and the temperature in the hot water bath is adjusted to 20 ° C. to obtain a methacrylic resin. The results are shown in Table 1.
[Example 3]
Polymerization was carried out in the same manner as in Example 1 except that the amount of methyl methacrylate polymer (1) added was 10 parts and the temperature in the hot water bath was adjusted to 20 ° C. to obtain a methacrylic resin. It was. The results are shown in Table 1.
[Comparative Example 1]
Polymerization was carried out in the same manner as in Example 1 except that methyl methacrylate polymer (1) was not added, 100 parts of methyl methacrylate monomer was used, and the temperature in the hot water bath was adjusted to 25 ° C. To obtain a methacrylic resin. The results are shown in Table 1.
[Comparative Example 2]
Polymerization was performed in the same manner as in Example 1 except that the methyl methacrylate polymer (2) was used and the temperature in the hot water bath was adjusted to 30 ° C. to obtain a methacrylic resin. The results are shown in Table 1.
[Comparative Example 3]
Polymerization was performed in the same manner as in Example 1 except that the temperature in the hot water bath was adjusted to 56 ° C. to obtain a methacrylic resin. The results are shown in Table 1.
[Comparative Example 4]
Instead of the active energy ray polymerization initiator, 0.5 part of an azo polymerization initiator (trade name: V-70, manufactured by Wako Pure Chemical Industries, Ltd.) is added, and heat is used instead of photopolymerization at a temperature of 25 ° C. Polymerization was performed in the same manner as in Example 1 except that the polymerization was performed to obtain a methacrylic resin. The results are shown in Table 1.

（表中のＩｒｇ１８４は、イルガキュア１８４を表す。）
表１から明らかなように、本発明により耐熱性に優れるメタクリル樹脂が短時間で得られることがわかる。

(Irg184 in the table represents Irgacure 184.)
As is apparent from Table 1, it can be seen that a methacrylic resin excellent in heat resistance can be obtained in a short time according to the present invention.

On the other hand, as in Comparative Example 1, when a methacrylic resin was obtained without a methyl methacrylate polymer having a tacticity of 80 or more, a methacrylic resin having high heat resistance could not be obtained. Further, as in Comparative Example 2, a methacrylic resin having high heat resistance was not obtained even when a methyl methacrylate polymer having low tacticity was used. Moreover, the heat resistance of the methacrylic resin obtained at a high polymerization temperature as in Comparative Example 3 was also low. Further, as in Comparative Example 4, when the thermal polymerization was performed, the polymerization time required 24 hours, and the productivity was low.

Claims (2)

Polymerization comprising a methyl methacrylate monomer or a monomer mixture containing methyl methacrylate as a main component, and a methyl methacrylate polymer having a tacticity in a methyl methacrylate unit chain of 80 or more in terms of triad (% rr) The manufacturing method of the methacryl resin which hardens an ionic mixture on 40 degrees C or less and active energy ray irradiation intensity | strength 1-30 mW / cm < ² > conditions.   The content of the methyl methacrylate polymer in which the tacticity in the methyl methacrylate unit chain in the polymerizable mixture is 80 or more in triad (% rr) is mainly composed of methyl methacrylate monomer or methyl methacrylate. 10 to 20 parts by mass with respect to a total of 100 parts by mass of the monomer mixture and methyl methacrylate polymer having a tacticity in the methyl methacrylate unit chain of 80 or more in triad display (% rr). A method for producing the methacrylic resin according to 1.