TWI646139B - Method for manufacturing sheet-shaped formed body - Google Patents

Abstract

The present invention provides a plate-shaped molded body obtained by molding a methacrylic resin composition, and having a yellowness index (YI) of 200 mm in optical path length of 10 or less, wherein the methacrylic resin composition is A methacrylic resin containing 50 to 90% by mass of a structural unit derived from methyl methacrylate, and 10 to 50% by mass of a structural unit derived from an alicyclic hydrocarbon methacrylate, and the methacrylic alicyclic The content of the formula hydrocarbon ester is 1.0% by mass or less. The present invention also provides a light guide plate composed of the plate-shaped formed body.

Description

Method for manufacturing plate-shaped formed body

The present invention relates to a plate-shaped formed body. More specifically, the present invention relates to a thin, large-area plate-shaped molded body having less coloring, high transparency, low haze, high impact resistance, low saturated water absorption, small dimensional change, and good appearance.

The methacrylic resin is excellent in transparency, light resistance, and surface hardness. By molding a methacrylic resin composition containing the methacrylic resin, various optical members such as a light guide plate and a lens can be obtained.

The demand for a light-weight and large-area liquid crystal display device is high, and in response to this, optical members are also required to be thinner and larger. However, if the optical member is reduced in thickness and area, it is easy to cause dimensional changes due to slight moisture and heat. Optical characteristics change with this size change. With the improvement in the image quality of display devices, high precision is required for optical characteristics such as refractive index and retardation. Therefore, a methacrylic resin composition as a raw material of an optical member is strongly required to have high transparency, low hygroscopicity, high heat resistance, small dimensional change, high impact resistance, good moldability, and the like.

As a resin material for an optical member, for example, an optical resin material is known, which will contain 5% by weight or more of (meth) acrylic acid The polymerizable composition of the acid tricyclodecyl ester is polymerized (refer to patent document 1). When this optical resin material is molded at a high molding temperature, the obtained molded body is easily colored. If this optical resin material is injection-molded at a low temperature of 230 to 260 ° C, the molded body is hardly colored. However, when molding is performed at a low temperature, the productivity of the formed body is low, and the residual stress in the formed body is easy to occur, so that it is easy to cause dimensional changes due to heat.

Prior art literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. 61-73705

Non-patent literature

Non-Patent Document 1 Technical Information of Japan Oil Co., Ltd. "Hydrogen Capture Capability and Initiator Efficiency of Organic Peroxides" (produced in April 2003)

The object of the present invention is to provide a thin, large-area plate-shaped molded body with less coloring, high transparency, low haze, low saturated water absorption, small dimensional change, and good appearance.

As a result of struggling research to achieve the above-mentioned purpose, the invention including the following aspects has finally been completed.

[1] A plate-shaped formed body composed of a methacrylic resin composition, and having a yellowness index (YI) of 200 mm or less in optical path length of 10 or less, wherein the methacrylic resin composition contains 50 to 50% 90 quality The amount of the methacrylic resin derived from the structural unit derived from methyl methacrylate, the structural unit derived from the alicyclic hydrocarbon methacrylate derived from 10 to 50% by mass, and the content of the alicyclic hydrocarbon methacrylate It is 1.0% by mass or less.

[2] The plate-shaped formed body according to [1], wherein the methacrylic tree The total content of the following components of the fat composition is 0.3% by mass or less: a dimer or trimer made of methyl methacrylate, a dimer or trimer made of acrylate, or methacrylic acid Dimer or trimer composed of alicyclic hydrocarbon ester, dimer composed of methyl methacrylate and acrylate, and composed of methyl methacrylate and alicyclic hydrocarbon methacrylate Dimer, dimer composed of acrylate and alicyclic methacrylate, terpolymer composed of two methyl methacrylate and one acrylate, and one methyl methacrylate and A trimer composed of two acrylates, a terpolymer composed of two methyl methacrylates and an alicyclic methacrylate, a terpolymer composed of one methyl methacrylate and two methacrylates Terpolymer composed of cyclic hydrocarbon esters, terpolymer composed of two acrylates and an alicyclic methacrylic acid ester, composed of one acrylate and two alicyclic methacrylic acid esters Terpolymer, and methyl methacrylate, propylene A terpolymer of an acid ester and an alicyclic methacrylate.

[3] The plate-shaped formed body according to [1] or [2], wherein the alicyclic methacrylate is a tricyclic methacrylate [5.2.1.0 ^2,6 ] dicyclopentanyl methacrylate Or isoamyl methacrylate.

[4] The plate-shaped formed body according to any one of [1] to [3], wherein the ratio of the resin flow length to the thickness is 380 or more.

[5] The plate-shaped formed body according to any one of [1] to [4], in which the transmittance of light having a wavelength of 435 nm at a light path length of 3 mm is 90% or more.

[6] A light guide plate composed of a plate-shaped formed body according to any one of [1] to [5].

[7] A method for producing a plate-shaped formed body, which is the method for producing a plate-shaped formed body according to any one of [1] to [5], which comprises: (I) starting a polymerizable monomer and polymerization The agent and the chain transfer agent are continuously supplied to the reactor; (II) a part of the polymerizable monomers are subjected to radical block polymerization in the reactor to obtain a resin mixture, the resin mixture contains: 50 to 90% by mass of a source Methacrylic resin from structural units of methyl methacrylate and structural units derived from alicyclic methacrylic acid esters of 10 to 50% by mass, unreacted polymerizable monomers, and polymerizable monomers The dimer or trimer constituted; (III) the resin mixture is continuously conveyed from the reactor to a biaxial extruder equipped with a vent hole; (IV) in the biaxial extruder, unreacted The polymerizable monomer and the dimer or trimer composed of the polymerizable monomer are removed from the resin mixture to obtain a methacrylic resin composition, and the methacrylic resin composition is extruded in a strand shape; ( V) Pellets are obtained by cutting the methacrylic resin composition extruded in a strand shape with a granulator. The methacrylic resin composition; (Vl) heating the melt pelletized and methacrylic resin composition to be molded.

The plate-shaped formed body of the present invention has less coloration, high transparency, low haze value, low saturated water absorption, and small dimensional change. The plate-shaped molded body of the present invention is suitable for optical members such as a thin and large-area light guide plate.

The reason why the plate-shaped molded body of the present invention exhibits the effects described above is considered to be as follows. Most cycloaliphatic methacrylates represented by tricyclodecyl methacrylate have high boiling points. In a devolatilization extrusion process used in continuous block polymerization as a general method for producing a methacrylic resin, the alicyclic methacrylic acid ester cannot be sufficiently removed and easily remains in the methacrylic resin. If a large amount of this compound remains in the methacrylic resin, it is considered that the plate-like molded body is colored, and the dimensional change is increased. In addition, gas is generated during injection molding, and it is considered that the surfaces of the molding die and the plate-shaped molded body are stained. Since the plate-shaped molded body of the present invention is composed of a methacrylic resin composition having a small amount of methacrylic alicyclic hydrocarbon ester, it is estimated that the above-mentioned defects should not occur.

1‧‧‧note

2‧‧‧ runner

3‧‧‧ Gate

4‧‧‧ resin flow length

11‧‧‧MMA slot

12‧‧‧MA slot

13‧‧‧n-OM slot

14‧‧‧ starter MMA solution tank

18‧‧‧ Nitrogen Mixer

21‧‧‧ Reactor

22‧‧‧Heating heat exchanger

23‧‧‧ Extruder with vent hole

P‧‧‧ pellets resin composition

FIG. 1 is a diagram showing a resin flow length in an injection molding die.

Fig. 2 is a diagram showing an example of a device used in the manufacturing method of the present invention.

[Form for Implementing Invention]

The plate-shaped forming system of the present invention is composed of a methacrylic resin group Made of objects.

The methacrylic resin composition includes a structural unit derived from methyl methacrylate (hereinafter also referred to as monomer (I).) And an alicyclic hydrocarbon methacrylate (hereinafter also referred to as monomer ( II).)) Is a methacrylic resin.

Examples of the monomer (II) include: monocyclic aliphatic hydrocarbon esters of methacrylic acid such as cyclohexyl methacrylate, cyclopentyl methacrylate, and cycloheptyl methacrylate; and 2-northylene methacrylate Ester, 2-methyl-2-norbornyl methacrylate, 2-ethyl-2-norbornyl methacrylate, 2-isomethyl methacrylate, 2-methyl methacrylate 2-isoamyl ester, 2-ethyl-2-isoamyl methacrylate, 8-tricyclo [5.2.1.0 ^2,6 ] decyl methacrylate, 8-methyl methacrylate- 8-tricyclo [5.2.1.0 ^2,6 ] decyl ester, methacrylic acid-8-ethyl-8-tricyclo [5.2.1.0 ^2,6 ] decyl ester, 2-adamantyl methacrylate, formazan 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, 2-phenoxy methacrylate, methyl Polycyclic aliphatic hydrocarbon esters of methacrylic acid such as 2-methyl-2-phenoxy acrylate and 2-ethyl-2-phenoxy methacrylate. Among these, a polycyclic aliphatic hydrocarbon methacrylate is preferred, and a tricyclic [5.2.1.0 ^2,6 ] decyl methacrylate (alias: tricyclic methacrylate [5.2.1.0 ^{2, 6} ] dicyclopentanyl methacrylate) or 2-isoamyl methacrylate (isoamyl methacrylate).

The methacrylic resin used in the present invention does not damage To the extent that the effect of the present invention is adversely affected, the monomer (I) and the monomer (II) may be included. A structural unit other than a monomer (hereinafter also referred to as a monomer (III).). Examples of the monomer (III) include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, secondary butyl acrylate, tertiary butyl acrylate, Amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, cyclohexyl acrylate, norbornene acrylate, isoamyl acrylate, Acrylic esters such as benzyl acrylate, phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-ethoxyethyl acrylate, propylene acrylate, allyl acrylate, phenyl acrylate, etc .; methyl Ethyl acrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, secondary butyl methacrylate, tertiary butyl methacrylate, methyl Amyl acrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, dodecyl methacrylate, phenyl methacrylate, etc. Other than methyl methacrylate Acrylates; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, maleic acid, and itaconic acid; olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-octene; butene Diene, isoprene, laurylene and other conjugated diene; styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene and other aromatic vinyl compounds; acrylamide, methyl Acrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinylpyridine, ketene, vinyl chloride, vinylidene chloride, vinylidene fluoride, and the like. Among these, from the viewpoint of improving transparency, an acrylate is preferred, and an alkyl acrylate having 1 to 6 carbon atoms is more preferred.

The methacrylic resin used in the present invention is derived from The content of the structural unit of the monomer (I) is usually 50 to 90% by mass, preferably 60 to 88% by mass, more preferably 70 to 86% by mass, and still more preferably 74 to 86% by mass.

In the methacrylic resin used in the present invention, the content of the structural unit derived from the monomer (II) is usually 10 to 50% by mass, preferably 11 to 35% by mass, and more preferably 12 to 20% by mass. .

In the methacrylic resin used in the present invention, the content of the structural unit derived from the monomer (III) is preferably 15% by mass or less, more preferably 10% by mass or less, and still more preferably 2 to 6% by mass.

The weight of the methacrylic resin used in the present invention is The average molecular weight is preferably 35,000 to 100,000, more preferably 40,000 to 90,000, even more preferably 45,000 to 80,000, and most preferably 60,000 to 80,000. If the weight average molecular weight is less than 35,000, the impact resistance and toughness of a plate-shaped formed body made of a methacrylic resin composition tends to be insufficient. If it is more than 100,000, the methacrylic resin composition is formed. Sex has a tendency to become inadequate.

If the methacrylic resin used in the present invention is considered The balance of various physical property values such as flowability, impact resistance, and glass transition temperature is preferably composed of 74 to 86% by mass of structural units derived from monomer (I), and 12 to 20% by mass of monomers derived from monomer (II). ) And 2 to 6% by mass of the structural unit derived from the monomer (III), and the weight average molecular weight is 60,000 to 80,000.

The weight of the methacrylic resin used in the present invention is Ratio of average molecular weight to number average molecular weight (weight average molecular weight / number Weight-average molecular weight: This ratio is also described below as the molecular weight distribution. ) Is preferably 1.7 to 2.6, more preferably 1.7 to 2.3, and even more preferably 1.7 to 2.0. If the molecular weight distribution of the methacrylic resin is small, the moldability of the methacrylic resin composition tends to decrease. If the molecular weight distribution is large, the impact resistance of a plate-shaped molded body obtained from a resin composition tends to decrease, and it tends to become brittle.

The weight average molecular weight and the number average molecular weight are molecular weights measured by GPC (gel permeation chromatography) in terms of standard polystyrene. The weight average molecular weight, number average molecular weight, and molecular weight distribution of the methacrylic resin can be controlled by adjusting the types and amounts of the polymerization initiator and the chain transfer agent.

The methacrylic resin used in the present invention, and its glass The transfer temperature is preferably 100 to 140 ° C, more preferably 105 to 135 ° C, and even more preferably 110 to 130 ° C. If the glass transition temperature is low, heat resistance and the like tend to decrease. If the glass transition temperature is high, the moldability and the like tend to decrease.

In the methacrylic resin composition used in the present invention The amount of the methacrylic resin contained is preferably 97% by mass or more, more preferably 98% by mass or more, and still more preferably 99% by mass or more with respect to the entire methacrylic resin composition.

The methacrylic resin composition used in the present invention, The content of the methacrylic alicyclic hydrocarbon ester is 1.0% by mass or less, preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and still more preferably 0.4% by mass or less. When the content of the alicyclic hydrocarbon methacrylate is in the above range, the yellowness index of the plate-shaped formed body of the present invention is small, and it is difficult to produce silver streaks. It has poor appearance with surface stains, etc. It is not easy to contaminate the mold with gas during continuous molding, and it is not easy to generate unique odor. The content of the alicyclic hydrocarbon methacrylate can be quantified by gas chromatography.

The methacrylic resin composition used in the present invention, The total content of the following components is preferably 0.3% by mass or less, more preferably 0.25% by mass or less, and still more preferably 0.2% by mass or less: a dimer or trimer composed of methyl methacrylate, or acrylic acid Dimer or trimer composed of ester, dimer or trimer composed of alicyclic hydrocarbon methacrylate, dimer composed of methyl methacrylate and acrylic ester, Dimer composed of methyl methacrylate and alicyclic hydrocarbon methacrylate, dimer composed of acrylate and alicyclic hydrocarbon methacrylate, two methyl methacrylate and one acrylic acid Terpolymer composed of esters, terpolymer composed of one methyl methacrylate and two acrylates, terpolymer composed of two methyl methacrylates and an alicyclic methacrylate Terpolymer consisting of one methyl methacrylate and two alicyclic hydrocarbon methacrylates, terpolymer consisting of two acrylates and one alicyclic hydrocarbon methacrylate, One acrylate and two alicyclic methacrylates The terpolymer formed is a terpolymer composed of methyl methacrylate, acrylate and alicyclic methacrylate. The smaller the total content of such dimers or trimers, the more remarkable the characteristics of the plate-shaped formed body of the present invention. In addition, the aforementioned dimers and trimers are compounds composed of structural units derived from the same or different 2 or 3 monomers, which are generated by stopping the reaction (recombination, disproportionation) and the like of radical polymerization. . Such dimers and trimers can be quantified by gas chromatography.

The composition of the methacrylic resin used in the present invention The melt flow rate of the material under the conditions of 230 ° C and a load of 3.8 kg is preferably 5 to 35 g / 10 minutes, more preferably 8 to 30 g / 10 minutes, and even more preferably 10 to 25 g / 10 minutes. The melt flow rate is a value of the melt mass flow rate measured in accordance with JIS K7210.

The methacrylic resin composition used in the present invention, From the viewpoint of suppressing the dimensional change of the plate-shaped formed body of the present invention obtained therefrom, the saturated water absorption is preferably 1.6% by mass or less, and more preferably 1.4% by mass or less. In addition, in this specification, the saturated water absorption is measured by measuring the mass of the plate-shaped formed body after being left for 300 hours under the conditions of a temperature of 60 ° C. and a humidity of 90% relative to the plate-shaped formed body subjected to vacuum drying for more than 3 days The value of the rate of increase in mass.

The methacrylic resin composition used in the present invention, The monomer (I), the monomer (II), and the monomer (III) of optional components (hereinafter, these are collectively referred to as "polymerizable monomers") are polymerized to produce a methacrylic resin. It is obtained by adjusting the content of the alicyclic hydrocarbon methacrylate and the content of the aforementioned dimer or trimer as needed. The amount of the monomer (I) used in the polymerization is preferably 50 to 90% by mass, and the amount of the monomer (II) used in the polymerization is preferably 10 to 50% by mass.

Monomer (I) and Monomer (II) as raw materials of methacrylic resin And the monomer (III) of any component, the yellowness index thereof is preferably 2 or less, and more preferably 1 or less. If the yellowness index of the polymerizable monomer is small, when the obtained methacrylic resin composition is molded, it is easy to obtain a plate-shaped molded body with little coloring at high production efficiency. In addition, the yellowness index is a colorimeter made by Nippon Denshoku Industries Co., Ltd. ZE-2000 is a yellowness value calculated based on the value measured in accordance with JIS Z8722 and calculated in accordance with JIS K7373.

The polymerization of the polymerizable monomer is preferably performed by a block polymerization method. More preferably, it is performed by a radical block polymerization method. From the viewpoint of productivity, a continuous block polymerization method is preferred. In addition, although the suspension polymerization method can reduce the amount of residual monomers in the resin, the yellowness index becomes large due to the influence of impurities such as stabilizers and dispersants. In the cell casting polymerization method, not only a plate-shaped formed body with few residual monomers cannot be obtained, but also a thin and large-area plate-shaped formed body is difficult to obtain, and its plate thickness accuracy and yellowness index are low. It is difficult to use as an optical member such as a light guide plate.

Polymerization reaction A polymerization initiator is added to start. By adding a chain transfer agent to the polymerizable monomer as needed, the weight average molecular weight, number average molecular weight, and molecular weight distribution of the obtained methacrylic resin can be adjusted.

The amount of dissolved oxygen of the polymerizable monomer is preferably 10 ppm or less. It is more preferably 5 ppm or less, even more preferably 4 ppm or less, and particularly preferably 3 ppm or less. When the amount of dissolved oxygen is within such a range, the polymerization reaction proceeds smoothly, and a plate-shaped molded body without silver streaks or coloring is easily obtained.

The polymerization initiator used in the polymerization of the polymerizable monomer is only It is not particularly limited as long as it generates reactive radicals. Examples include: tert-hexyl peroxyisopropyl monocarbonate, tert-hexyl peroxy-2-ethylhexanoate, peroxy-2-ethylhexanoic acid-1,1,3,3-tetra Methyl butyl, tert-butyl peroxyisobutyrate, tert-hexyl peroxyisobutyrate, tert-butyl peroxyneodecanate, tert-hexyl peroxynedecanoate, peroxyneodecanoate -1,1,3,3-tetramethyl Butyl ester, 1,1-bis (tertiary hexaperoxy) cyclohexane, benzamidine peroxide, -3,5,5-trimethylhexamidine peroxide, dodecyl peroxide, 2,2 ' -Azobis (2-methylpropionitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2-methylpropionate), and the like. Among these, the polymerization initiator is preferably one having a half-life temperature of 60 to 140 ° C, and more preferably 80 to 120 ° C. In the case of using a block polymerization method for the polymerization reaction, the polymerization initiator preferably has a hydrogen-capturing ability of 20% or less, more preferably 10% or less, and even more preferably 5% or less. Specifically, preferred are tert-hexyl peroxy-2-ethylhexanoate, 1,1-bis (tertiary hexaperoxy) cyclohexane, and 2,2'-azobis (2-methyl Methyl propionate). These polymerization initiators may be used individually by 1 type, and may use 2 or more types together. The amount of use of the polymerization initiator, the method of addition, and the like may be appropriately set depending on the purpose, and are not particularly limited. For example, the amount of the polymerization initiator used in the block polymerization method is preferably 0.0001 to 0.02 parts by mass, and more preferably 0.001 to 0.01 parts by mass relative to 100 parts by mass of the polymerizable monomer.

Also, the ability to capture hydrogen can be determined by the manufacturer of the polymerization initiator. Technical documents (for example, Non-Patent Document 1) are known. In addition, it can be measured by a radical capture method using an α-methylstyrene dimer, that is, an α-methylstyrene dimer capture method. This measurement is generally performed as follows. First, in the coexistence of an α-methylstyrene dimer as a radical trapping agent and cyclohexane, the polymerization initiator is cleaved to generate radical fragments. Among the generated free radical fragments, the free radical fragments having low hydrogen-capturing ability are added to the double bond of the α-methylstyrene dimer and captured. On the other hand, radical fragments with high hydrogen-capturing ability capture hydrogen from cyclohexane to generate cyclohexyl radical, which is added to the double bond of α-methylstyrene dimer and captured, A cyclohexane capture product was formed. Then, the ratio (mole fraction) of free radical fragments with high hydrogen-capturing capacity to the theoretical amount of free radical fragments generated by quantifying cyclohexane or cyclohexane capture products was determined as Capturing hydrogen.

Chain transfer used for polymerization of polymerizable monomers Examples of the agent include n-octyl mercaptan, n-dodecane mercaptan, tertiary dodecane mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, and ethylene glycol dithiopropane. Acid ester, butanediol dithioglycolate, butanediol dithiopropionate, hexanediol dithioglycolate, hexanediol dithiopropionate, trimethylolpropane ginseng (β-sulfur Propionate), neopentyl alcohol, thiopropionate, and other alkyl mercaptans; α-methylstyrene dimer; terpinolene. Among these, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecane mercaptan are preferred. These chain transfer agents can be used individually by 1 type or in combination of 2 or more types. The amount of the chain transfer agent used for the polymerization is preferably 0.1 to 1 part by mass, more preferably 0.2 to 0.8 part by mass, and still more preferably 0.3 to 0.6 part by mass, relative to 100 parts by mass of the polymerizable monomer.

Block polymerization of polymerizable monomers can also be performed in batch reactions. It is preferably carried out in a continuous flow type reaction apparatus. The continuous flow type reaction device supplies the reaction raw material to the reactor at a certain flow rate, and discharges the liquid containing the reaction product obtained from the reactor at a certain flow rate, so that the supply of the reaction raw material and the discharge of the liquid containing the reaction product are balanced, and Apparatus for continuous reaction. As a reactor used in a continuous flow type reaction device, there are a tank type reactor capable of performing a reaction in a state close to complete mixing and a tube type reactor capable of performing a reaction in a state close to plug flow. One or more of these reactors can be used. Can be used in combination of two or more different reactors. For example, in order to obtain the methacrylic resin used in the present invention, the reaction can be performed in a continuous flow-type tank reactor from the initial stage to the intermediate stage of the reaction, and the final stage of the reaction can be performed in a continuous-flow tubular reactor. The reactor may also have a stirrer, which can be selected according to the style of the reactor, but examples include: Maxblend stirrer, stirrer with grid-shaped blades rotating around a vertical rotation axis arranged in the center, propeller stirrer, screw Mixer, static mixer, etc. In a continuous flow-type tank reactor, a Maxblend type agitator is preferable from the viewpoint of uniform mixing.

A particularly suitable device for the block polymerization of polymerizable monomers is a device having at least one continuous flow-through tank-type reactor. Multiple continuous-flow tank reactors can be connected in series or in parallel. When a continuous-flow tank reactor is used, the amount supplied to the reactor is balanced with the amount discharged from the reactor so that the amount of liquid in the reactor is substantially constant. The amount of liquid in the reactor is preferably 1/4 to 3/4, and more preferably 1/3 to 2/3 with respect to the volume of the reactor.

In a continuous flow reaction, the monomer (I), the monomer (II), and the monomer (III) of any component, a polymerization initiator, and a chain transfer agent may be mixed together, and then the mixture may be supplied to the reactor. The monomer (I), the monomer (II), and the monomer (III) of an arbitrary component, a polymerization initiator, and a chain transfer agent were separately supplied to the reactor. In the present invention, a method of mixing the whole and then supplying the mixture to the reactor is preferred.

The monomer (I), the monomer (II) and the monomer (III) of any component, the polymerization initiator and the chain transfer agent are preferably mixed in an inert gas ring such as nitrogen. Environment. In addition, in order to smoothly perform the continuous flow reaction operation, it is preferable to continuously pass through the tube from the tank storing, for example, methyl methacrylate, alicyclic methacrylate, polymerization initiator, and chain transfer agent, respectively, to continuously Ground is supplied to a mixer provided in the front stage of the reactor and mixed, and the mixture is continuously flowed to the reactor. The mixer is preferably equipped with a mixer such as a static mixer.

The temperature during the polymerization is preferably 100 to 160 ° C, and more preferably 110 ~ 150 ℃. If the temperature during the polymerization reaction is within such a range, it is easy to adjust the yellowness index and the melt flow rate of the plate-shaped formed body to the aforementioned ranges.

The polymerization reaction time is preferably 0.5 to 4 hours, and more preferably 1 to 3 hours. In the case of a continuous flow reactor, the polymerization reaction time is the average residence time in the reactor. If the polymerization reaction time is too short, the required amount of the polymerization initiator will increase. As the polymerization initiator is increased, the control of the polymerization reaction becomes difficult, and the control of the molecular weight tends to become difficult. On the other hand, if the polymerization reaction time is too long, it takes some time for the reaction to reach a stable state, and the productivity tends to decrease. The polymerization is preferably performed in an inert gas environment such as nitrogen.

The polymerization conversion rate of the polymerizable monomer is preferably 30 to 80 mass %, More preferably 40 to 70% by mass, and even more preferably 50 to 65% by mass. If the polymerization conversion rate is within such a range, it is easy to adjust the yellowness index and the melt flow rate of the plate-shaped formed body to a preferable range. If the polymerization conversion rate is too high, there is a tendency that a large stirring power is required due to an increase in viscosity. If the polymerization conversion rate is too low, devolatilization is likely to be insufficient, and when the obtained methacrylic resin composition is molded, there is a tendency that appearance defects such as silver streaks are caused in the plate-shaped molded body.

By the above-mentioned polymerization, a methacrylic acid-containing tree can be obtained Grease, unreacted polymerizable monomer, and a resin mixture of a dimer or trimer composed of a polymerizable monomer. After the polymerization is completed, if necessary, the unreacted polymerizable monomer, the dimer or trimer composed of the polymerizable monomer, and the solvent are removed. The removal method is not particularly limited, and it is preferably heat devolatilization. Examples of the devolatilization method include equilibrium flash and adiabatic flash. In particular, adiabatic flash evaporation is preferably performed at a temperature of 210 to 300 ° C, more preferably 220 to 280 ° C, and even more preferably 230 to 260 ° C. If it is less than 210 ° C, it may take some time for devolatilization, and devolatilization may be insufficient. When the devolatilization is insufficient, appearance defects such as silver streaks are caused on the plate-shaped formed body. Conversely, if it is higher than 300 ° C, not only the formation of the aforementioned dimer and trimer will increase, but also the amount of terminal double bonds will increase, and it will be difficult to ensure thermal stability.

The above-mentioned adiabatic flash evaporation is at the current pressure of the resin melt. The force is preferably 1.5 to 3.0 MPa, and more preferably 2.0 to 2.5 MPa. If it is less than 1.5 MPa, flash evaporation is insufficient, and there is a tendency that residual monomers increase. Conversely, if it is greater than 3.0 MPa, it tends to be difficult to stabilize production.

After adiabatic flash evaporation, the polymer is obtained by extruding the polymer with a screw extruder. To resin composition. The screw extruder preferably has at least one vacuum exhaust hole or an open exhaust hole on the downstream side than the polymer inflow portion. The pressure in the vacuum exhaust hole is preferably 30 Torr or less, more preferably 15 Torr or less, still more preferably 9 Torr or less, and most preferably 6 Torr or less. When the pressure of the vacuum exhaust hole is in the above range, the degassing efficiency is good, and residual monomers can be reduced.

The screw of the above-mentioned screw extruder is preferably a biaxial screw of the same direction Pole. Compared with the uniaxial case, because of the shear energy given to the resin Large, the degree of surface renewal is large, can be efficiently degassed, and residual monomers can be reduced. The screw structure preferably has a kneading section of 5% or more of the total length of the screw. Examples of the kneading segment include a rotor segment, a forward feeding kneading disk, a reverse feeding kneading disk, and a mixing gear.

The cylinder heating temperature of the screw extruder is preferably 220 to 300 ° C, more preferably 230 to 290 ° C, and even more preferably 240 to 280 ° C. If it is lower than 220 ° C, devolatilization is likely to be insufficient, and the residual monomer tends to increase. Conversely, if it is higher than 300 ° C, there is a tendency that residual monomers increase due to depolymerization of the main chain of the methacrylic resin; impurities other than the residual monomer increase due to side chain detachment; , Burning, etc. to color the methacrylic resin composition.

Volatile components can be removed in an extruder equipped with vent holes. In order to make full use of the advantages of the continuous flow type reaction, it is preferable to continuously convey the resin mixture continuously discharged from the polymerization reactor to an extruder equipped with a vent hole. An extruder provided with a vent hole generally has: a reaction product supply port capable of supplying a reaction product containing a polymer and a volatile component; a polymer discharge port capable of discharging a polymer separated from the reaction product; at least one The vent hole can discharge the volatile components separated from the reaction product; the screw is used to transport the reaction product from the reaction product supply port to the polymer discharge port while kneading the reaction product. The exhaust hole 27 at the side closer to the polymer discharge port than the reaction product supply port is called the front exhaust hole, and the exhaust hole 26 at the side farther from the polymer discharge port than the reaction product supply port is called rear exhaust hole. In the present invention, it is preferred to use an extruder equipped with a vent hole, and discharge it before the position closest to the polymer discharge port. The pores are also close to the polymer discharge port side, and an additive input port is provided. The extruder is preferably depressurized first, and the supplied reaction product is preferably flash-evaporated than the reaction product supply port. Then, the volatile components were evaporated while being conveyed by a screw. The evaporated volatile components are discharged from the exhaust holes. The extruder includes a single-shaft extruder and a twin-shaft extruder, and a twin-shaft extruder is preferred. The extruder is usually divided into a feed zone, a compression zone, a metering zone and a mixing zone. The screw suitable for these areas can be selected appropriately. In the mixing zone, screw rods having various shapes, such as irregularities, grooves, and needles, such as a Dulmage type, a rotor type, and a flute mixing type, can be appropriately combined for use.

The methacrylic resin composition of the present invention may include the same. He adds various additives as needed. Additives can be added, for example, from the additive inlet of the aforementioned extruder. Examples of the additives include thermal stabilizers, antioxidants, thermal degradation inhibitors, ultraviolet absorbers, light stabilizers, lubricants, release agents, inorganic fillers, inorganic or organic fibers, mineral oil softeners, and polymers Processing aids, antistatic agents, flame retardants, dyes, colorants, matting agents, light diffusing agents, impact modifiers, phosphors, adhesives, tackifiers, plasticizers, foaming agents Wait. The content of the additive is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less. If the content of the additive is too large, appearance defects such as silver streaks may be caused in the plate-shaped formed body.

Antioxidants are used in the presence of oxygen to prevent The effect of oxidative degradation of resin. Examples thereof include phosphorus-based antioxidants, hindered phenol-based antioxidants, and thioether-based antioxidants. These antioxidants can be used individually by 1 type or in combination of 2 or more types. among them, From the viewpoint of preventing the deterioration of optical characteristics due to coloration, a combination of a phosphorus-based antioxidant and a hindered phenol-based antioxidant or a combination of a thioether-based antioxidant and a hindered phenol-based antioxidant is more preferred.

Combined with phosphorus-based antioxidants (or thioether-based antioxidants) and In the case of hindered phenol-based antioxidants, the ratio is not particularly limited, but the quality of phosphorus-based antioxidants (or thioether-based antioxidants) / hindered phenol-based antioxidants is preferably 1/5 to 2/1, and more preferably 1 / 2 ~ 1/1.

Examples of the phosphorus-based antioxidant include phosphorous acid-2,2- Methylene bis (4,6-di (tertiary butyl) phenyl) octyl ester (manufactured by ADEKA, trade name: ADK STAB HP-10), Phosphite (2,4-bis (tertiary butyl) Phenyl ester) (manufactured by Ciba Specialty Chemicals, trade name: IRUGAFOS168), 3,9-bis (2,6-bis (tributyl) -4-methylphenoxy) -2,4,8,10 -Tetraoxa-3,9-diphosphospiro [5.5] undecane (made by ADEKA, trade name: ADK STAB PEP-36) and the like.

Examples of hindered phenolic antioxidants include neopentyl Alcohol [3- (3,5-bis (tributyl) -4-hydroxyphenyl) propionate] (Ciba Specialty Chemicals, product name IRGANOX1010), 3- (3,5-bis (tri Octyl butyl) -4-hydroxyphenyl) propanoate (manufactured by Ciba Specialty Chemicals, trade name IRGANOX 1076) and the like.

Examples of the thioether-based antioxidant include: 2,2-bis [(3- Dodecylthio-1-oxopropoxy) methyl] propane-1,3-diylbis (3-dodecylthiopropionate) (manufactured by ADEKA, trade name: ADK STAB AO-412S), 3 3'-thiodipropionate di (tridecyl) ester (manufactured by ADEKA, trade name: ADK STAB AO-503) and the like.

Thermal degradation inhibitors can be trapped in A compound that prevents the thermal degradation of resin by polymer free radicals generated when exposed to high heat in a state. For example, acrylic acid-2-tertiarybutyl-6- (3'-tertiarybutyl-5'-methylhydroxybenzyl) -4-methylphenyl ester (manufactured by Sumitomo Chemical Co., Ltd., trade name) Sumilizer GM), acrylic acid-2,4-bis (tertiary pentyl) -6- [3 ', 5'-bis (tertiary pentyl) -2'-hydroxy-α-methylbenzyl] phenyl ester (Manufactured by Sumitomo Chemical Co., Ltd. under the trade name Sumilizer GS).

The ultraviolet absorber is a compound having an ability to absorb ultraviolet rays. Examples include: benzophenones, benzotriazoles, tris Type, benzoate type, salicylate type, cyanoacrylate type, oxaloaniline type, malonate type, formazan type and the like. These can be used individually by 1 type or in combination of 2 or more types. Among these, benzotriazoles and anilines are preferred.

Examples of benzotriazoles include: 2- (2H-benzotriazole Azol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (Ciba Specialty Chemicals, trade name TINUVIN329), 2- (2H-benzotriazol-2-yl ) -4,6-bis (1-methyl-1-phenylethyl) phenol (produced by Ciba Specialty Chemicals, trade name TINUVIN234), and the like.

Examples of the anilines include 2-ethyl-2'-ethoxyoxabenzidine (manufactured by Clariant Japan, trade name: Sanduvor VSU), and the like.

Among these ultraviolet absorbers, benzotriazoles are particularly preferred from the viewpoint of suppressing deterioration of the resin due to ultraviolet radiation.

The light stabilizer refers to a compound having a function of capturing free radicals generated mainly by photo-induced oxidation. Examples include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

The mold release agent has the ability to easily release the plate-shaped formed body from the mold. Functional compounds. Examples thereof include higher alcohols such as cetyl alcohol and stearyl alcohol; and higher fatty acid glycerides such as glyceryl monooctadecanoate and glyceryl dioctadecanoate. Among these, it is preferable to use a higher alcohol and a monofatty acid glyceride together. When using higher alcohols and mono-fatty acid glycerides in combination, the ratio is not particularly limited, but the quality of higher alcohols / mono-fatty acid glycerides is preferably 2.5 / 1 to 3.5 / 1, and more preferably 2.8 / 1 to 3.2 / 1.

Polymer processing aid is composed of methacrylic resin A compound that exhibits effects in thickness accuracy and thin film formation when an object is formed. Polymer processing aids can usually be produced by emulsion polymerization. The polymer processing aid is preferably a polymer particle having a particle diameter of 0.05 to 0.5 μm. The polymer particle may be a single-layer particle composed of a polymer having a single composition ratio and a single limiting viscosity, or a multilayer particle composed of two or more polymers having different composition ratios or limiting viscosity. Among them, preferred are particles having a two-layer structure having a polymer layer having a low limiting viscosity in the inner layer and a polymer layer having a high limiting viscosity of 5 dl / g or more in the outer layer. The limiting viscosity of the polymer processing aid is preferably 3 to 6 dl / g. If the limiting viscosity is too small, the effect of improving formability is low. If the limiting viscosity is too large, the melt fluidity of the methacrylic resin composition is liable to be reduced.

Examples of impact modifiers include propylene Core-shell type modifiers of acid-based rubber or diene-based rubber as a core layer component; modifiers containing a plurality of rubber particles, and the like.

As the organic pigment, a compound having a function of converting ultraviolet rays that damage the resin into visible light is preferably used.

Examples of the light diffusing agent and matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, and barium sulfate.

Examples of the phosphor include a fluorescent pigment, a fluorescent dye, a fluorescent white dye, a fluorescent whitening agent, and a fluorescent bleach.

Mineral oil softeners are used to improve fluidity during forming processes. Examples thereof include paraffin-based oils and naphthenic oils.

Examples of the inorganic filler include calcium carbonate, talc, carbon black, titanium oxide, silicon dioxide, clay, barium sulfate, and magnesium carbonate. Examples of the fibrous filler include glass fibers and carbon fibers.

In addition, the methacrylic resin composition used in the present invention can be mixed with a polymer other than the above-mentioned methacrylic resin used in the present invention as long as the effect of the present invention is not impaired. Examples of such other polymers include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionic polymers; poly Styrene resins such as styrene, styrene-maleic anhydride copolymer, high impact polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin; methyl methacrylate- Styrene copolymer; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polyamides such as nylon 6, nylon 66, and polyamide elastomers; polycarbonate, poly Vinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacetal, polyvinylidene fluoride, polyurethane, modified polyphenylene ether, polyphenylene sulfide, polysilicon Oxygen modified resins; acrylic rubber, silicone rubber; SEPS, SEBS, SIS and other styrene-based thermoplastic elastomers; IR, EPR, EPDM and other olefin-based rubbers.

After removing unreacted polymerizable monomer and polymerizable monomer Dimer or trimer methacrylic resin composition can be made into pellets, granules, powder, etc. in order to improve convenience during storage, transportation, and molding. The pellets can be obtained, for example, by extruding the methacrylic resin composition into strands in the extruder described above, and cutting the extruded methacrylic resin composition into strands by a pelletizer.

The plate-shaped formed body of the present invention can be formed by injection molding (embedded into Forming method, two-color forming method, pressure forming method, core-blowing forming method, sandwich injection forming method, etc.), compression forming, extrusion forming, vacuum forming, blow molding, blow molding, calendering, etc. The methacrylic resin composition is obtained by heat-melting. It is preferable to use a pellet-like methacrylic resin composition at the time of heat melt molding.

The methacrylic resin composition is preferably dried before molding dry. Examples of the drying method include a hot air drying method, a dehumidifying drying method, a reduced-pressure drying method, and a low-oxygen drying method. If the water content is reduced by drying before forming, it is possible to reduce formation defects such as silver streaks.

Also, it is preferable to remove from the methacrylic resin pellets before molding. To cut defective products and resin powder. Cutting bad products are long resin sheets etc. obtained after cutting the stocks. The resin powder is powder generated by cutting chips or pellets rubbing each other when cutting strands. A method of removing the defective cutting product and the resin powder is not particularly limited. Examples thereof include a centrifugal separation method and a sieving method.

In addition, the methacrylic resin composition In the case of a hopper of a shaper, it is preferable to maintain the temperature of the methacrylic resin composition or the methacrylic resin pellets at, for example, 70 ° C or higher. If raised When the temperature is conveyed, the generation of resin powder caused by moisture absorption and friction between the pellets during transportation can be suppressed.

Resin flow length versus thickness of the plate-shaped formed body of the present invention The better is 380 or more. The thickness of the plate-shaped formed body of the present invention is preferably 1 mm or less.

The resin flow length is the gate of the injection molding die. The distance from the inner wall of the mold furthest from the gate. The resin flow length for the thin film gate is the distance between the foot of the vertical line extending from the installation part of the injection gate of the injection mold (the intersection with the gate) and the inner wall of the mold furthest from the intersection. (See Figure 1).

The gate of the mold used to obtain the plate-shaped formed body of the present invention is preferably a film gate. The film gate is cut with a cutter, and surface-treated with a trimming machine. In a mold for obtaining a light guide plate used in a liquid crystal display device, a gate is preferably provided on an end surface without a predetermined light source.

The yellowness index (YI) of the plate-shaped formed body of the present invention having a light path length of 200 mm is 10 or less, preferably 8 or less, and more preferably 6 or less. The yellowness index is a value calculated based on JIS K7373 using a colorimeter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd. based on a value measured in accordance with JIS Z8722.

When the plate-shaped formed body of the present invention has a light path length of 3 mm, the transmittance to a wavelength of 435 nm is preferably 90% or more, more preferably 90.5% or more, and still more preferably 91% or more.

Examples of the use of the plate-shaped formed body of the present invention include signboard components such as advertising towers, booth signs, wall pillar signs, door and window signboards, roof signboards, etc .; display windows, partitions, and shop displays Products; fluorescent lighting covers, mood lighting covers, lampshades, ceiling lights, wall lamps, chandeliers, etc .; interior decorations such as pendants, mirrors; doors, vaults, safety window glass, compartments, staircase panels, balconies Panels, construction parts for roofs of leisure buildings, etc .; windshields for aircraft, sunshades for pilots, motorcycles, windscreens for motorcycles, sunshades for buses, side sunshades for automobiles, rear sunshades, Parts related to transportation equipment such as head wings and head light covers; electronic equipment parts such as audio and video signs, stereo enclosures, TV covers, vending machine display covers; medical equipment parts such as thermal insulation boxes and X-ray machine parts; machinery Machine-related parts such as housings, instrument covers, experimental devices, rulers, keyboards, viewing windows, etc .; LCD protective plates, light guide plates, light guide films, Fresnel lenses, lenticular lenses, front panels for various displays, diffusers and other optical related Parts; road signs, navigation boards, curved mirrors, sound-proof walls and other transportation-related supplies; surface materials for automotive interiors, surface materials for mobile phones, sign films, etc. Thin film components; cover materials for washing machines, control panels, top panels for electric cookers, and other household appliance parts; other greenhouses, large sinks, aquariums, clock panels, bathtubs, public toilets, table mats, game accessories, toys, welding Face protection cover, etc. Among them, the plate-shaped formed body of the present invention is suitable for a light guide plate and a front panel of various displays.

The plate-shaped molded body of the present invention is used as a planar light source element When one of the light guide plates is used, it is also possible to form a concave-convex shape for light guide on the back surface of the plate by a well-known method such as welding, bonding, coating, printing, injection molding, and processing using laser light. The light incident from the end surface of the plate can be reflected, refracted, etc. in the uneven shape, and can be emitted to the front of the plate. Examples of the uneven shape include a perfect circle or an oval Round dot-like patterns, such as rectangular or V-groove linear patterns, hemispherical lens-like irregularities, grain patterns, etc. These concave-convex shapes cannot be absolutely defined due to the optimal structure of the size and thickness of the light guide plate, but they are preferably 1 to 600 μm wide, 2 to 1200 μm long, 1 to 500 μm high or deep, and the interval between adjacent concave and convex shapes is 2 ~ 10000μm. If the concave-convex shape is too large, it will be visually recognized, and the quality of the display will be lowered. If it is too small, the processing will be difficult, resulting in lower productivity. In addition, if the interval between the adjacent uneven shapes is narrower than 2 μm, it is difficult to independently form adjacent unevenness, which is liable to cause molding defects. If it is wider than 10000 μm, the number of uneven portions cannot be increased. Since the concave-convex part has a function of emitting light, the limitation of the number of the concave-convex part will limit the proportion of light that is effectively emitted from the light incident from the end face of the light guide plate, that is, the light utilization rate is restricted. These concave-convex shapes may be the same shape in a light guide plate, or may be combined to form different shapes, or patterns of the same shape but different sizes may be arranged. In addition, the interval and size of the unevenness can also be adjusted according to the distance of the light source disposed adjacent to the end surface of the light guide plate.

In addition, it can replace the formation of uneven shapes and reverse the white color. The radiation material is printed on the back of the light guide plate. The size of the white reflective material is preferably 500 μm to 5000 μm. If it is smaller than 500 μm, it is difficult to print a white reflective material by conventional screen printing or the like. If it is larger than 5000 μm, the white reflective material will be recognized even when viewed through a diffusion sheet or the like, resulting in a deterioration in display quality. The interval between the reflective materials is preferably 1000 to 5000 μm. If the interval is narrower than 1000 μm, defects such as overlapping of adjacent white reflective materials may occur in screen printing or the like. If it is wider than 5000 μm, even when viewed through a diffusion sheet or the like, The dark parts between the white reflective materials will still be recognized, resulting in poor display quality. In addition, the interval and size of the white reflective material can also be adjusted according to the distance of the light sources arranged adjacent to the end surface of the light guide plate. In addition, it is possible to form a ridge or a circular arc-shaped linear convex portion on the light emitting surface (front surface of the light guide plate) of the light guide plate in the same manner. When used as a backlight, a reflective sheet may be appropriately arranged on the back side of the light guide plate, and a diffusion sheet and / or a cymbal sheet may be appropriately arranged on the front side of the light guide plate.

The molded article of the present invention can be used as a front panel for various displays. panel. Such a front panel can be obtained by a general molding method such as heat-melt extrusion molding or injection molding of a resin composition.

The display device using the front panel is not particularly limited, and examples thereof include large display devices such as large-screen televisions and advertising displays; small and medium display devices such as mobile phones and smart phones.

In addition, the front panel is not limited to a flat shape, and may have a curved shape. The curved surface shape may be a shape curved in one direction, or may be a shape curved in multiple directions. In order for the front panel to have a curved shape, the plate-shaped molded body may have flexible characteristics, or may be formed in advance into a desired curved shape.

In addition, the molded article of the present invention can also be applied by spraying or dipping. It is used for the above-mentioned various applications in a state where the surface is hard-coated by a method such as coating. Due to the hard coating, the pencil hardness on the surface becomes high and it is not easy to be damaged. In addition to hard coating, functional layers such as an anti-glare layer and an anti-reflection layer, a layer that blocks electromagnetic waves, ultraviolet rays, and near-infrared rays can also be provided.

The molded article of the present invention can be laminated with another functional film or functional sheet through an adhesive layer or an adhesive layer, or can be laminated by film insert molding. Examples of the functional film and the functional sheet include a light guide plate and a diffusion plate, an explosion-proof film, and a transparent conductive film.

[Example]

Examples and comparative examples are provided below to explain the present invention more specifically. However, the present invention is not limited to the following examples.

The polymer physical properties of the methacrylic resin compositions obtained in the examples and comparative examples and the properties of the plate-shaped formed bodies were measured by the following methods.

(Polymerization conversion rate, residual volatile components)

A gas chromatograph GC-14A manufactured by Shimadzu Corporation was mounted with INERT CAP 1 (df = 0.4 μm, 0.25 mm ID × 60 m) manufactured by GL Sciences Inc. as a column, and analyzed based on the following analysis conditions. Figure it out.

<Analysis conditions>

Injection temperature: 250 ℃

Detector temperature: 250 ℃

String temperature conditions:

Initial temperature: 60 ° C

Initial temperature holding time: 5 minutes

Heating rate: 10 ° C / min

Maximum temperature: 250 ℃

Maximum temperature holding time: 10 minutes

(Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn))

The weight-average molecular weight (Mw) and molecular weight distribution are determined by GPC (gel permeation chromatography).

． Device: GPC device "HLC-8320" manufactured by Tosoh Co., Ltd.

． Separation column: "TSKgelGMHXL" and "G4000HXL" made by Tosoh Corporation

． Eluent: Tetrahydrofuran

． Dissolution flow: 0.35ml / min

． Column temperature: 40 ℃

． Detection method: Differential refractive index (RI)

(Melting Flow Rate)

The melt flow rate of the methacrylic resin composition obtained in Examples and Comparative Examples was measured in accordance with JIS K7210 under the conditions of 230 ° C., a load of 3.8 kg, and 10 minutes.

(Saturated water absorption)

Using an injection molding machine (SE-180DU-HP, manufactured by Sumitomo Heavy Industries Co., Ltd.), pelletized methacrylic resin was composed of a cylinder temperature of 280 ° C, a mold temperature of 75 ° C, and a molding cycle of 1 minute. The object was injection-molded to obtain a test piece having a length of 290 mm, a width of 100 mm, and a thickness of 2 mm. The test piece was vacuum-dried under conditions of a temperature of 50 ° C and 5 mmHg for 3 days, and the mass W ₀ of the test piece when it was completely dried was measured. Thereafter, the completely dried test piece was left for 300 hours under the conditions of a temperature of 60 ° C and a humidity of 90%. Thereafter, the mass W _{1 of the} test piece was measured. The saturated water absorption (%) is calculated by the following formula.

Saturated water absorption (%) = (W ₁ -W ₀ ) / W ₀ × 100

(Appearance of plate-shaped molded body)

The appearance of the plate-shaped formed bodies produced in the examples and comparative examples was observed with the naked eye. Evaluation was made by the presence or absence of appearance defects such as surface stains and breakage.

A: Good

B: The surface is stained

C: Damaged

(Yellowness Index)

The yellowness index of the polymerizable monomers used in the examples and comparative examples was calculated based on the values measured in accordance with JIS Z-8722 and the polymerizable monomers used in the examples and comparative examples using a colorimeter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

A test piece having a length of 200 mm was cut from each of the plate-shaped formed bodies prepared in the examples and comparative examples, and was measured based on JIS Z-8722 using a colorimeter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd. Based on JIS K7373, the yellowness index of the 200 mm optical path length of these test pieces was calculated.

(Transmittance)

A test piece having a light path length of 200 mm and a test piece having a light path length of 3 mm were cut from the plate-shaped formed bodies prepared in the examples and comparative examples, respectively. When light having a wavelength of 435 nm was measured at a light path length of 200 mm and a light path length of 3 mm, The transmittance.

(Size change rate)

The plate-shaped formed bodies produced in the examples and comparative examples were placed in a thermostat at 60 ° C. and left in the air for 4 hours. The plate-shaped molded body was taken out from the thermostat, and the dimension in the longitudinal direction was measured. The dimension change rate was calculated from the dimension (205 mm) in the longitudinal direction before being placed in the thermostat.

(Impact resistance of plate-shaped formed body)

Using an injection molding machine (SE-180DU-HP, manufactured by Sumitomo Heavy Industries, Ltd.), the conditions of the cylinder temperature were 230 ° C, the mold temperature was 65 ° C, and the molding cycle was 0.5 minutes. The obtained pellet-like methacrylic resin composition was injection-molded or cut out from the plate-shaped formed body obtained in Comparative Example 8 to produce test pieces having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. No cuts were measured according to ISO179-1 The strength of Chapi shock.

In the following, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate (dicyclopentanyl methacrylate) is designated as TCDMA, isopropyl methacrylate is designated as IBXMA, methyl methacrylate is designated as MMA, acrylic acid The methyl ester is labeled MA, the n-octyl mercaptan is labeled n-OM, and 2,2'-azobis (2-methylpropionitrile) is labeled AIBN.

Example 1

In an autoclave equipped with a mixer and a collecting tube, 78 parts by mass of MMA, 20 parts by mass of TCDMA, and 2 parts by mass of MA were added to prepare a monomer mixture. The yellowness index of the monomer mixture was 0.9. To the monomer mixture, 0.006 parts by mass of a polymerization initiator (AIBN, hydrogen-capturing capacity: 1%, 1-hour half-life temperature: 83 ° C) and 0.37 parts by mass of a chain transfer agent (n-OM) were added to dissolve, A raw material liquid was obtained. Nitrogen was used to expel oxygen from the manufacturing facility.

This raw material liquid was supplied from the autoclave at a constant flow rate to a continuous-flow tank-type reactor controlled at a temperature of 140 ° C., and the average residence time was 120 minutes to perform block polymerization. The reaction liquid was separated and taken out by the collection tube of the reactor, and when measured by gas chromatography, the polymerization conversion rate was 57% by mass.

The liquid discharged from the reactor was heated to 250 ° C. A constant flow rate was supplied to a biaxial extruder controlled at 260 ° C. In this biaxial extruder, the volatile components containing unreacted monomers as main components are separated and removed, and the resin components are extruded in a strand shape. This strand was cut with a granulator to obtain a pelletized methacrylic resin composition. The residual TCDMA is 0.4% by mass. The polymer properties of the obtained pelletized methacrylic resin composition were measured.

Use of injection molding machine (Sumitomo Heavy Industries, Ltd. (SE-180DU-HP, manufactured by the company), the above-mentioned pellet-shaped methacrylic resin composition was injection-molded under the conditions of a cylinder temperature of 280 ° C, a mold temperature of 75 ° C, and a molding cycle of 1 minute, and was made into a length of 205mm, a width of 160mm, A plate-shaped molded body having a thickness of 0.5 mm. The ratio of the resin flow length (190 mm) to the thickness was 380.

The characteristics of the obtained plate-shaped molded body were evaluated. The results are shown in Table 1.

Example 2

Except changing the amount of MMA to 73 parts by mass, the amount of TCDMA to 23 parts by mass, the amount of MA to 4 parts by mass, the amount of n-OM to 0.33 parts by mass, and the resin manufacturing conditions to the values shown in Table 1, In the same manner as in Example 1, a pelletized methacrylic resin composition was obtained. The polymer properties of the obtained pelletized methacrylic resin composition were measured in the same manner as in Example 1. Then, it carried out similarly to Example 1, and produced the plate-shaped molded object, and evaluated the characteristic. These results are shown in Table 1.

Example 3

A pellet was obtained in the same manner as in Example 1 except that the amount of MMA was changed to 83 parts by mass, the amount of TCDMA was changed to 15 parts by mass, the amount of MA was changed to 2 parts by mass, and the amount of n-OM was changed to 0.38 parts by mass. A methacrylic resin composition. The polymer properties of the obtained pelletized methacrylic resin composition were measured in the same manner as in Example 1. Then, it carried out similarly to Example 1, and produced the plate-shaped molded object, and evaluated the characteristic. These results are shown in Table 1.

Example 4

A pelletized methacrylic resin composition was obtained in the same manner as in Example 1 except that TCDMA was changed to IBXMA and the amount of n-OM was changed to 0.36 parts by mass. The polymer properties of the obtained pelletized methacrylic resin composition were measured in the same manner as in Example 1. Then, it carried out similarly to Example 1, and produced the plate-shaped molded object, and evaluated the characteristic. These results are shown in Table 1.

Comparative Examples 1 to 4

A pelletized methacrylic resin composition was obtained in the same manner as in Example 1 except that the synthesis conditions and resin production conditions shown in Tables 1 and 2 were changed. The polymer physical properties of these pelletized methacrylic resin compositions were measured in the same manner as in Example 1. Then, it formed similarly to Example 1, and measured characteristics. These results are shown in Tables 1 and 2.

Comparative Example 5

A pelletized methacrylic resin composition was obtained in the same manner as in Example 1 except that the synthesis conditions and resin production conditions shown in Table 2 were changed.

The pelletized methacrylic resin composition was fed to a biaxial extruder controlled at 270 ° C at a constant rate. In this biaxial extruder, volatile components containing unreacted monomers as main components are separated and removed, and resin components are extruded in a strand shape. This strand was cut with a granulator to obtain a pelletized methacrylic resin composition (re-granulated). The remaining TCDMA is 0.7% by mass. The polymer physical properties of the re-granulated methacrylic resin composition were measured in the same manner as in Example 1. Then, a plate-shaped molded body was produced in the same manner as in Example 1, and the characteristics were measured. These results are shown in Table 2.

Comparative Example 6

A pelletized methacrylic resin composition was obtained in the same manner as in Example 1 except that the synthesis conditions and resin production conditions shown in Table 2 were changed.

A solution of 20 parts by mass of the pelletized methacrylic resin composition and 80 parts by mass of toluene was prepared, and the solution was poured into a large amount of methanol to reprecipitate to obtain a powdered methacrylic resin composition.

This powdered methacrylic resin composition was fed to a uniaxial extruder controlled at 230 ° C. at a constant speed, and the extruded strands were cut with a pelletizer to obtain pelletized methacrylic resin compositions ( Regranulation). The remaining TCDMA is 0.2% by mass. The polymer physical properties of the re-granulated methacrylic resin composition were measured in the same manner as in Example 1. Then, a plate-shaped molded body was produced in the same manner as in Example 1, and the characteristics were measured. These results are shown in Table 2.

Comparative Example 7

83 parts by mass of MMA, 15 parts by mass of TCDMA, and 2 parts by mass of MA were added to prepare a monomer mixture. The yellowness index of the monomer mixture was 0.9. 0.1 parts by mass of a polymerization initiator (AIBN, hydrogen-capturing capacity: 1%, 1-hour half-life temperature: 83 ° C) and 0.4 parts by mass of a chain transfer agent (n-OM) were added to the monomer mixture to dissolve To obtain a raw material liquid.

100 parts by mass of ion-exchanged water, 0.03 parts by mass of sodium sulfate, and 0.46 parts by mass of a suspension dispersant were mixed to obtain a mixed solution. In a pressure-resistant polymerization tank, 420 parts by mass of the mixed solution and 210 parts by mass of the raw material solution were added, and the temperature was adjusted to 70 ° C. while stirring in a nitrogen atmosphere, and a polymerization reaction was started. After the start of the polymerization reaction, the temperature was raised to 90 ° C. after 3 hours had elapsed, and stirring was continued for 1 hour to obtain a dispersion liquid in which beads-like fine particles were dispersed.

The obtained dispersion was filtered, and the fine particles were washed with ion-exchanged water, and then dried at 80 ° C. under a reduced pressure of 100 Pa for 4 hours to obtain a bead copolymer.

The obtained copolymer was supplied to a uniaxial extruder controlled at 230 ° C., and volatile components such as unreacted monomers were separated and removed, and then the resin component was extruded to form strands. This strand was cut with a granulator to obtain a pelletized methacrylic resin composition. Then, a plate-shaped molded body was produced in the same manner as in Example 1, and the characteristics were measured. These results are shown in Table 2.

Comparative Example 8

73 parts by mass of MMA, 25 parts by mass of TCDMA, and 2 parts by mass of MA were added to prepare a monomer mixture. The yellowness index of the monomer mixture was 0.9. 0.1 parts by mass of a polymerization initiator is added to the monomer mixture (AIBN, hydrogen-capturing capacity: 1%, 1-hour half-life temperature: 83 ° C.), and dissolved to obtain a raw material liquid.

This raw material solution was poured into a glass tank composed of two water-repellent glass plates (thickness 10 mm, 30 cm x 30 cm) and a vinyl chloride resin gasket, and degassed at 760 mmHg for 3 minutes. Polymerize in this glass tank at 70 ° C for 2 hours, and then polymerize at 120 ° C for 2 hours. After removing the glass plate to make a plate-shaped formed body with a thickness of 0.5 mm, the plate-shaped formed body is broken when taken out, and the plate Low thickness accuracy.

Plate-shaped formed bodies having a thickness of 2 mm and 4 mm were produced under the same polymerization conditions as above, and the obtained plate-shaped formed bodies were cut into test pieces for evaluating light transmittance of 290 mm in length, 100 mm in width, and 2 mm in thickness, and impact resistance. The test piece for property evaluation of 80 mm in length, 10 mm in width, and 4 mm in thickness was evaluated for polymer physical properties and characteristics of the plate-shaped molded body. The obtained plate-like formed body was very high-molecular-weight and did not dissolve in the solvent, and only swelled. Therefore, the molecular weight cannot be measured. The weight average molecular weight is estimated to be 1 million g / mol or more. These results are shown in Table 2.

As shown in the above results, the plate-shaped formed body of the present invention has less coloration, high transparency, low haze value, low saturated water absorption, small dimensional change, and good appearance.

Claims (6)

A method for producing a plate-shaped formed body, comprising: (I) continuously supplying a polymerizable monomer, a polymerization initiator, and a chain transfer agent to a reactor; and (II) supplying a part of the polymerizable monomer in the reactor A radical mixture is polymerized to obtain a resin mixture containing 50 to 90% by mass of a structural unit derived from methyl methacrylate and 10 to 50% by mass of an alicyclic hydrocarbon methacrylate derived Structural units of methacrylic resin, unreacted polymerizable monomer, and dimer or trimer composed of polymerizable monomer; (III) continuously conveying the resin mixture from the reactor to the A vented biaxial extruder; (IV) removing unreacted polymerizable monomers and dimers or trimers composed of polymerizable monomers from the resin mixture in the biaxial extruder A methacrylic resin composition was obtained, and the methacrylic resin composition was extruded in a strand shape; (V) The methacrylic resin composition extruded in the strand shape was cut by a pelletizer to obtain pellets Granular methacrylic resin composition; (VI) heating and melting the pellets Based acrylic resin composition and molding; the plate-shaped molding system is composed of a methacrylic resin composition, and the yellowness index (YI) of a 200 mm optical path length is 10 or less, wherein the methacrylic resin composition contains 50 to 90% by mass of structural units derived from methyl methacrylate, 10 to 50% by mass of methacrylic resin derived from structural units of alicyclic methacrylic acid esters, and methacrylic alicyclic hydrocarbons The content of the ester is 1.0% by mass or less. The method for producing a plate-shaped molded body according to claim 1, wherein the methacrylic resin composition comprises a dimer or trimer composed of methyl methacrylate, a dimer or trimer composed of acrylate Polymer, dimer or trimer composed of alicyclic hydrocarbon methacrylate, dimer composed of methyl methacrylate and acrylate, methyl methacrylate and methacrylate Dimer composed of cyclic hydrocarbon ester, dimer composed of acrylate and alicyclic methacrylate, terpolymer composed of two methyl methacrylate and one acrylate, composed of A terpolymer composed of one methyl methacrylate and two acrylates, a terpolymer composed of two methyl methacrylates and an alicyclic methacrylate, and one methyl methacrylate Terpolymer composed of two methacrylic alicyclic hydrocarbon esters, terpolymer composed of two acrylates and one methacrylic cycloaliphatic hydrocarbon ester, composed of one acrylate and two methacrylic acid Terpolymer composed of alicyclic hydrocarbon esters, and The total content of the terpolymer composed of methyl methacrylate, acrylate and alicyclic methacrylate is 0.3% by mass or less. For example, the method for producing a plate-shaped formed body according to claim 1, wherein the alicyclic methacrylate is a tricyclic [5.2.1.0 ^2,6 ] dec-8-yl methacrylate or methacrylic acid Isoamyl ester. For example, the method for manufacturing a plate-shaped molded body according to claim 1, wherein the ratio of the resin flow length to the thickness of the plate-shaped molding system is 380 or more. For example, the method for manufacturing a plate-shaped formed body according to claim 1, wherein the plate-shaped forming system has a transmittance of light having a wavelength of 435 nm at a light path length of 3 mm, which is more than 90%. The method for manufacturing a plate-shaped formed body as claimed in claim 1, wherein the plate-shaped formed body is a light guide plate.