JP2014111240A - Method of producing plastic sheet, plastic sheet obtained by the same and plastic substrate for display comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing plastic sheets that enables their mass production without impairing characteristics of plastic sheet materials, plastic sheets obtained by the same, and plastic substrates for displays comprising the same.SOLUTION: In a cleaning step (i), plastic sheet materials 6 are cleaned using cleaning fluid composed of aqueous solution containing 50-99 wt.% of glycol ether.

Description

  The present invention relates to a method for producing a plastic sheet by washing a plastic sheet material obtained by curing a curable composition, and more specifically, it is possible to reliably prevent foreign matters such as resin stains generated in the production process of the plastic material. The present invention relates to a method capable of producing a high-quality plastic sheet in a mass production system.

  Conventionally, many substrates made of glass are used as substrates for displays. For example, a glass substrate having a thickness of about 0.5 to 1 mm is widely used for a cover window, a touch panel, a liquid crystal display, an organic electroluminescence (EL) display, a backlight, and the like.

  Such a glass substrate is excellent not only in optical performance such as light transmittance, but also in thermomechanical characteristics, processing characteristics such as adhesion between the printed layer and the inorganic film, and appearance quality such as scratch resistance. However, there is a limit to meeting demands for weight reduction and safety improvement, and in recent years, the use of plastic substrates made of plastic has been considered.

  In such a plastic substrate, in order to satisfy various characteristics such as optical performance equivalent to that of a glass substrate, an improvement of the plastic material itself has been proposed. For example, Patent Document 1 has an alicyclic structure. It is disclosed that a cured product of a photocurable composition comprising a polyfunctional urethane (meth) acrylate and a polyfunctional (meth) acrylate having an alicyclic structure becomes a resin molded product having high pencil hardness. Patent Document 2 discloses a photocurable composition comprising a monofunctional (meth) acrylate having an alicyclic structure, a polyfunctional urethane (meth) acrylate having an alicyclic structure, and a (meth) acrylate having an alicyclic structure. It is disclosed that the cured product becomes a resin molded product excellent in optical properties and thermomechanical properties. Furthermore, Patent Document 3 discloses a polyfunctional urethane having a molecular weight of 200 to 2000 (meta) having a specific alicyclic skeleton bifunctional (meth) acrylate compound, a specific aliphatic tetrafunctional (meth) acrylate compound, and an alicyclic skeleton. It is disclosed that a photocurable resin composition comprising an acrylate-based compound becomes a resin molded article having excellent optical properties and thermomechanical properties. On the other hand, a method for reducing surface defects (surface contamination) when formed on a plastic sheet is also studied. For example, in Patent Document 4, photocuring of a photocurable resin composition is performed in two stages. It is disclosed.

JP 2006-193596 A JP 2007-204736 A JP 2007-056180 A Japanese Patent Laid-Open No. 10-058465

  However, even if various properties of the plastic material itself are improved, there is still a problem in forming a plastic sheet material from these materials and further forming a plastic sheet that can be used for a display plastic substrate. That is, when plastic sheet materials are made from these materials, plastic-specific stains on the surface (unreacted monomers and oligomers adhering during sheet material handling, melts and volatile components adhering during laser cutting) Will occur. Such dirt peculiar to plastic deteriorates various functions of the plastic substrate for display. Therefore, it is required to clean the plastic sheet material, remove the dirt, and complete a clean plastic sheet.

  Such surface stains generated in the plastic sheet material are generally cleaned using an organic solvent. For example, cleaning is performed by using an alcohol solvent, a halogen-based solvent, an aromatic solvent, or the like and using a technique such as brushing, showering, dipping, or rinsing. However, since these organic solvents have a low flash point and are often dangerous materials in the Fire Service Act, it is necessary to make the cleaning equipment explosion-proof, increasing the production cost of plastic sheets and mass production. The sex is greatly reduced.

  The present invention is a breakthrough made by overcoming such a conventional technique, and cleans the surface of the plastic sheet, which is peculiar to plastic, without using an organic solvent. It is completed as a sheet. That is, the present invention provides a method capable of producing a clean plastic sheet in a mass production system without impairing various properties of the plastic sheet material, and a plastic sheet obtained thereby and a plastic substrate for a display comprising the same. For that purpose.

However, as a result of intensive studies by the present inventors, the plastic sheet material was cleaned with an aqueous solution containing a large amount of glycol ether so as to clean the plastic sheet material without damaging various properties of the plastic sheet material. The present invention has been completed by discovering that an excellent plastic sheet can be produced with high productivity.
That is, this invention makes the 1st summary the manufacturing method of the plastic sheet which wash | cleans the plastic sheet material which consists of cured resin using the washing | cleaning liquid which consists of the aqueous solution which contains 50 to 99 weight% of glycol ethers.

  A plastic sheet manufactured by the manufacturing method according to the first aspect is a second aspect, and a display plastic substrate made of the plastic sheet according to the second aspect is a third aspect.

  According to the method for producing a plastic sheet of the present invention, a plastic sheet material made of a cured resin is washed with a washing solution made of an aqueous solution containing 50 to 99% by weight of glycol ether to obtain a plastic sheet. It is not necessary to use an organic solvent to clean the plastic sheet material in the sheet manufacturing process, which eliminates the need for explosion-proof production facilities, and it is possible to achieve both reduction in manufacturing costs for plastic sheets and improvement in mass productivity. .

  When an aqueous solution having a KB value (Kauri / Butanol value) of 200 or more is used as the cleaning liquid, the oil and dirt on the surface of the plastic sheet material is easily dissolved in the cleaning liquid, and thus the cleaning power can be further increased.

  Further, when the plastic sheet material is washed in a state tilted by 5 to 50 ° with respect to the horizontal plane, the washing performance is improved, the washing liquid can be collected smoothly, and the washing liquid can be easily reused.

  When the plastic sheet material is cleaned by brushing using a cleaning liquid, cleaning can be performed in a shorter time, and the manufacturing efficiency of the plastic sheet can be increased.

  Furthermore, after rinsing with a cleaning liquid, rinsing with an aqueous solution containing 10 to 60% by weight of alcohol can further remove surface impurities and obtain a high-quality plastic sheet. it can.

  Further, when the aqueous solution used for rinsing contains at least one of ethyl alcohol and isopropyl alcohol, the volatilization rate of the aqueous solution is increased, and moisture can be quickly removed from the surface of the plastic sheet obtained by washing.

  Furthermore, if the plastic sheet material is laser-cut, the cut surface is sharp and smooth, so that it can be suitably used as a plastic substrate for display. In addition, since the melt and volatile components generated during laser cutting are effectively removed, it is possible to obtain a plastic sheet that can more effectively exhibit various properties of the plastic sheet material.

  And when the plastic sheet material is a resin molded body obtained by curing a photocurable composition containing a polyfunctional (meth) acrylate and a photopolymerization initiator, the plastic sheet has excellent characteristics comparable to a glass substrate. Can be obtained.

  In addition, the plastic sheet produced by the production method of the first aspect can effectively exhibit various properties of the plastic sheet material, is excellent in mass productivity, and has good cost performance.

  Furthermore, the plastic substrate for display made of the plastic sheet according to the second aspect can effectively exhibit various properties of the plastic sheet material, is excellent in mass productivity, and has good cost performance.

It is explanatory drawing which shows the outline of the manufacturing method of the plastic sheet of this invention.

  Next, an embodiment for carrying out the present invention will be described.

FIG. 1 shows an embodiment of a method for producing a plastic sheet of the present invention. In this embodiment, the steps (a) to (h) of preparing the photocurable composition 4 and forming the plastic sheet material 6 from the photocurable composition 4 and the cleaning step of cleaning the plastic sheet material 6 ( i), the plastic sheet 8 is obtained. The greatest feature of the present invention is that, in the cleaning step (i), the plastic sheet material 6 is cleaned using a cleaning liquid composed of an aqueous solution containing 50 to 99% by weight of glycol ether.
Each of these steps will be described in turn below.

[Steps (a) to (h) for forming a plastic sheet material]
In this embodiment, the process of forming the plastic sheet material 6 includes a process (a) of preparing the glass plate 1 and a spacer 2 on the glass plate 1 as shown in FIGS. (B) for preparing the mold 3 by arranging the mold, a casting process (c) for injecting the photocurable composition 4 into the molding space by raising the mold 3 vertically, and ultraviolet rays (UV light) An irradiation step (d) in which the photocurable composition 4 is cured by irradiating 5 to form a plastic sheet material 6; a demolding step (e) in which the two glass plates 1 are separated to expose the plastic sheet material 6; A product peeling step (f) for peeling the plastic sheet material 6 from the glass plate 1, a post-processing step (g) for performing post-processing such as annealing on the plastic sheet material 6, and molding the plastic sheet material 6 to a predetermined size. Cutting process (h) To have.

  In the cutting step (h), the end of the obtained plastic sheet material 6 is cut, or a predetermined portion is cut to obtain a plurality of plastic sheet materials 6 from one plastic sheet material 6, This is performed in order to obtain a plastic sheet material 6 having a predetermined dimension. The plastic sheet material 6 can be cut by, for example, laser processing, NC processing, or the like. Especially, the thing by laser processing is preferable from the point that cutting efficiency is good and a cut surface can be made smooth. In the case where the plastic sheet material 6 is obtained with high accuracy, this cutting step (h) may not be provided.

  The plastic sheet material 6 can be obtained from the photocurable composition 4 by passing through the steps (a) to (h).

  Examples of the photocurable composition 4 include photocurable compositions such as (meth) acrylic compositions, epoxy resin compositions, and thiol / ene addition systems. Among these, a polyfunctional (meth) acrylate and a photopolymerization initiator are preferable because a (meth) acrylic composition is preferable because it has excellent optical properties when molded into a plastic sheet, and the surface hardness can be further increased. A (meth) acrylic composition comprising:

  Moreover, it is preferable to make the photocurable composition 4 contain polyfunctional urethane (meth) acrylate. That is, a plastic sheet having high surface hardness and high heat resistance can be obtained by containing polyfunctional urethane (meth) acrylate. In addition, a urethane bond structure derived from urethane (meth) acrylate is formed in the sheet, the sheet has appropriate toughness due to the hydrogen bond, and the plastic sheet has a high flexural modulus and high strength. it can.

  Such a polyfunctional urethane (meth) acrylate is obtained by reacting a polyisocyanate compound with a hydroxyl group-containing (meth) acrylate, and examples of the polyisocyanate include aromatic, aliphatic, and alicyclic compounds. Polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, Trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-bis ( (Sosocyanatomethyl) polyisocyanate such as cyclohexane, phenylene diisocyanate, lysine diisocyanate, lysine triisocyanate, naphthalene diisocyanate, or the like, trimer compound or multimer compound of these polyisocyanates, burette type polyisocyanate, water dispersion type polyisocyanate ( For example, “Aquanate 100”, “Aquanate 110”, “Aquanate 200”, “Aquanate 210”, etc., manufactured by Nippon Polyurethane Industry Co., Ltd.), or the reaction products of these polyisocyanates and polyols. These can be used alone or in combination of two or more. Among these, alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane are preferable in that the water absorption of the plastic sheet can be reduced.

  In the present invention, “(meth) acrylate” is a general term for acrylate and methacrylate, and “(meth) acryl” is a general term for acrylic and methacrylic. “Polyfunctional” means having two or more (meth) acryloyl groups in the molecule.

  In this embodiment, the photocurable composition 4 is used as the material of the plastic sheet material 6, but is not limited thereto, and is not limited to (meth) acrylic resin composition, epoxy resin composition, allyl type. Thermosetting resin compositions such as a resin composition, a styrene resin composition, an amide resin composition, an imide resin composition, a urethane resin composition, and a thiourethane resin composition can also be used. However, it is preferable to use the photocurable composition 4 in terms of excellent optical characteristics and mass productivity.

  And in this embodiment, although the process of forming the plastic sheet material 6 has each process of said (a)-(h), it is not restricted to this, The plastic sheet which has a desired shape and characteristic Any material can be used as long as the material 6 can be obtained. Moreover, you may use what is marketed as such a plastic sheet material 6. FIG. Although the thickness of the plastic sheet material 6 varies depending on the use, it is generally 0.05 to 5 mm. In particular, for example, when used for a display substrate, it is preferably 0.05 to 3 mm. More preferably, it is 1-2 mm, More preferably, it is 0.2-1 mm. This is because if it is too thin, the rigidity as a display substrate tends to be insufficient, and if it is too thick, it tends to be difficult to make the display lighter and thinner.

  Moreover, although the surface hardness of the said plastic sheet material 6 changes with uses, it is preferable that it usually has a pencil hardness of 3H or more, and when using it for a display substrate, for example, it should have a pencil hardness of 3H or more. Is preferable, more preferably 4H or more, and still more preferably 5H or more. In order to set the surface hardness of the plastic sheet material 6 within the above range, the type of the curable composition and the composition of the components may be adjusted as appropriate. For example, as the polyfunctional (meth) acrylate, 3-6 functional What is necessary is just to use a thing.

  And although the bending elastic modulus of the said plastic sheet material 6 changes with uses, it is 2 GPa or more normally, It is preferable that it is 3-5 GPa, for example, when using for a display board | substrate among others, More preferably, 3 .5-4 GPa. If the bending elastic modulus is too low, the plastic sheet material 6 tends to bend and become difficult to convey in the cleaning step (i) described later. If it is too high, the plastic sheet material 6 tends to break during conveyance. is there. In order to set the bending elastic modulus of the plastic sheet material 6 within the above range, the kind of the curable composition and the composition of the components may be adjusted as appropriate. For example, as the polyfunctional (meth) acrylate, 3-6 functional What is necessary is just to use a thing. For example, when the (meth) acrylate is monofunctional, the flexural modulus tends to decrease because the cross-linked structure in the sheet is insufficient. Therefore, the flexural modulus is too high and tends to break.

  Further, the plastic sheet material 6 generally has a total light transmittance of 80% or more. Among them, considering that the manufactured plastic sheet 8 is used as a display plastic substrate, the total light transmittance is 80% or more. It is preferably 85% or more, more preferably 90% or more.

[About the cleaning process (i) for cleaning plastic sheet materials]
Next, a process of cleaning the plastic sheet material 6 (cleaning process (i)) and obtaining the plastic sheet 8 will be described. This process includes unreacted monomers and oligomers adhering to the surface during the handling of the plastic sheet material 6, residues generated in the cutting step (h), or melts and volatile components generated by laser cutting. In order to remove water, the surface of the plastic sheet material 6 is washed with a washing liquid composed of an aqueous solution containing 50 to 99% by weight of glycol ether, which is the greatest feature of the present invention.

  In this embodiment, first, the plastic sheet material 6 produced above is brushed with a rotating brush 7 (material: nylon) using a predetermined cleaning liquid, and then contains 10 to 60% by weight of alcohol. Rinsing (not shown) using an aqueous solution is performed. Specifically, the plastic sheet material 6 is conveyed and brushed so as to pass between two rotating brushes 7 containing a cleaning liquid, and then rinsed with an aqueous solution containing alcohol over the entire plastic sheet material 6. It is carried out.

  The cleaning liquid is an aqueous solution containing 50 to 99% by weight of glycol ether. By containing a large amount of glycol ether in this way, in particular, melts and volatile components generated by laser melt cutting are easily dissolved. Can be removed. Moreover, since this cleaning liquid is a non-flammable liquid with no flash point detected, no special explosion-proof equipment is required. Furthermore, the toxicity to the human body, such as acute toxicity, is low, and the burden on the environment is small compared to halogenated solvents. As described above, the content of glycol ether in the cleaning liquid is 50 to 99% by weight, preferably 70 to 98% by weight, more preferably 80 to 97% by weight, and still more preferably 90 to 96% by weight. . If the content of glycol ether is too small, the detergency tends to be inferior. Conversely, if the content is too large, the flash point tends to be detected.

  Examples of such glycol ethers include ethylene glycol monomethyl ether (bp 124 ° C., flash point 39 ° C., Class 4 2 stones), ethylene glycol dimethyl ether, ethylene glycol monoethyl ether (bp 135 ° C., flash point 43 ° C., Class 4 2 Stone), ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol dipropyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monohexyl ether, ethylene glycol dihexyl ether, ethylene glycol ethyl methyl ether, ethylene glycol propyl Methyl ether, ethylene glycol butyl methyl ether, ethylene glycol hexyl methyl ether, ethylene glycol pro Ruethyl ether, ethylene glycol butyl ethyl ether, ethylene glycol hexyl ethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monopropyl ether, diethylene glycol dipropyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, Diethylene glycol monohexyl ether, diethylene glycol dihexyl ether, diethylene glycol ethyl methyl ether, diethylene glycol propyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol hexyl methyl ether Diethylene glycol propyl ethyl ether, diethylene glycol butyl ethyl ether, diethylene glycol hexyl ethyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monoethyl ether, triethylene glycol diethyl ether, triethylene glycol monopropyl ether, triethylene Glycol dipropyl ether, triethylene glycol monobutyl ether, triethylene glycol dibutyl ether, triethylene glycol monohexyl ether, triethylene glycol dihexyl ether, triethylene glycol ethyl methyl ether, triethylene glycol propyl methyl ether, triethylene glycol butyl ether Tylmethyl ether, triethylene glycol hexyl methyl ether, triethylene glycol propyl ethyl ether, triethylene glycol butyl ethyl ether, ethylene glycol hexyl ethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol monoethyl ether, tetra Ethylene glycol diethyl ether, tetraethylene glycol monopropyl ether, tetraethylene glycol dipropyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol dibutyl ether, tetraethylene glycol monohexyl ether, tetraethylene glycol dihexyl ether, tetraethylene glycol ethyl Chill ether, tetraethylene glycol propyl methyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol hexyl methyl ether, tetraethylene glycol propyl ethyl ether, tetraethylene glycol butyl ethyl ether, tetraethylene glycol hexyl ethyl ether, propylene glycol monomethyl ether, propylene Glycol dimethyl ether, propylene glycol monoethyl ether (bp 135 ° C, flash point 43 ° C, Class 4 2 stones), propylene glycol diethyl ether, propylene glycol monopropyl ether, propylene glycol dipropyl ether, propylene glycol monobutyl ether, propylene glycol dibutyl ether, Propylene glycol Hexyl ether, propylene glycol dihexyl ether, propylene glycol ethyl methyl ether, propylene glycol propyl methyl ether, propylene glycol butyl methyl ether, propylene glycol hexyl methyl ether, propylene glycol propyl ethyl ether, propylene glycol butyl ethyl ether, propylene glycol hexyl ethyl ether, Dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol dipropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol Recall dibutyl ether, dipropylene glycol monohexyl ether, dipropylene glycol dihexyl ether, dipropylene glycol ethyl methyl ether, dipropylene glycol propyl methyl ether, dipropylene glycol butyl methyl ether, dipropylene glycol hexyl methyl ether, dipropylene glycol propyl ethyl Ether, dipropylene glycol butyl ethyl ether, dipropylene glycol hexyl ethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol diethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol Rudipropyl ether, tripropylene glycol monobutyl ether, tripropylene glycol dibutyl ether, tripropylene glycol monohexyl ether, tripropylene glycol dihexyl ether, tripropylene glycol ethyl methyl ether, tripropylene glycol propyl methyl ether, tripropylene glycol butyl methyl ether, Tripropylene glycol hexyl methyl ether, tripropylene glycol propyl ethyl ether, tripropylene glycol butyl ethyl ether, tripropylene glycol hexyl ethyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol monoethyl ether, Trapropylene glycol diethyl ether, tetrapropylene glycol monopropyl ether, tetrapropylene glycol dipropyl ether, tetrapropylene glycol monobutyl ether, tetrapropylene glycol dibutyl ether, tetrapropylene glycol monohexyl ether, tetrapropylene glycol dihexyl ether, tetrapropylene glycol ethyl methyl Ether, tetrapropylene glycol propyl methyl ether, tetrapropylene glycol butyl methyl ether, tetrapropylene glycol hexyl methyl ether, tetrapropylene glycol propyl ethyl ether, tetrapropylene glycol butyl ethyl ether, tetrapropylene glycol hexyl ethyl ether, etc. Among these, from the viewpoint of vapor pressure, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, propylene glycol monopropyl ether, and tripropylene glycol monobutyl ether are preferably used.

  And although the said washing | cleaning liquid may contain auxiliary components, such as a dispersing agent and another washing | cleaning component, it is preferable that it is an aqueous solution whose KB value is 200 or more from the point which a cleaning power increases, More preferably, 300 More preferably, the aqueous solution is 400 or more. In addition, KB value here is based on ASTM D1133, and is a dripping amount in which white turbidity is produced (cauli gum is deposited) when a detergent is dropped on 20 g of a standard kauri / butanol solution at 25 ° C., Generally, the higher this value, the greater the ability to dissolve fats and oils. When the dropped cleaning agent is 400 mL or more, the KB value is ∞.

  Next, the aqueous solution used for the rinsing contains 10 to 60% by weight of alcohol. By containing an appropriate amount of alcohol in this way, impurities on the surface of the plastic sheet material 6 can be effectively removed. In addition, it contains non-hazardous substances in the Fire Service Law by containing more than 40% by weight of water. And the toxicity to the human body, such as acute toxicity, is low, and the burden on the environment is also small. The alcohol content of this aqueous solution is 10 to 60% by weight, preferably 30 to 58% by weight, more preferably 40 to 57% by weight, and still more preferably 50 to 56% by weight. This is because if the alcohol content is too low, the cleaning power tends to decrease, and if it is too high, it becomes a dangerous substance in the Fire Service Law.

  Examples of the alcohol contained in the aqueous solution used for rinsing include ethyl alcohol, normal propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, and the like. It is preferable to use 2 to 6 alcohols because of excellent cleaning ability. In particular, ethyl alcohol, propyl alcohol, and a mixture thereof are preferable in terms of good drying properties after washing.

  The aqueous solution used for rinsing may contain auxiliary components such as a dispersant and other cleaning components, but the boiling point is preferably 100 ° C. or lower, more preferably 90 ° C. or lower, from the viewpoint of improving the drying property. More preferably, it is 80 degrees C or less.

  And in this washing | cleaning process (i), it is preferable to carry out the conveyance of the plastic sheet material 6 in the state inclined 5-50 degrees with respect to the horizontal surface. As a result, the cleaning solution used for cleaning and the aqueous solution used for rinsing flow smoothly along the surface of the plastic sheet material 6, improving the cleaning power and facilitating the recovery of these liquids. is there. If the recovered liquid is reused, further cost reduction can be realized.

  Further, the plastic sheet 8 obtained after washing may be removed by blowing away the moisture on the surface using an air knife or the like (not shown). By quickly blowing off the moisture, it is possible to prevent the surface from being stained and the obtained plastic sheets 8 can be stacked and stored in a clean state.

  In the above embodiment, the plastic sheet material 6 is brushed by the rotating brush 7 using a predetermined cleaning liquid, and then rinsed using an aqueous solution containing alcohol, but contains alcohol. Rinsing using pure water or the like may be performed instead of the aqueous solution. Further, when the plastic sheet material 6 is sufficiently cleaned with the cleaning liquid, the rinsing itself may not be performed. However, when rinsing is performed using an aqueous solution containing alcohol, even if there is a residue attached in the form of an oil film on the surface of the plastic sheet material 6, it can be removed cleanly, and the degree of cleaning is further increased, which is preferable. .

  Further, in the above embodiment, in the cleaning using the cleaning liquid, the rotating brush 7 made of nylon is used, but in addition to this, resistance to cleaning liquids such as polyvinyl alcohol and Teflon (registered trademark) is used. Can be used as a material. The rotating brush 7 is used as the brush, but a general brush may be used or the brush itself may not be used. That is, instead of brushing, showering, rinsing, dipping, etc. may be performed instead. However, it is preferable to perform brushing using the rotating brush 7 from the viewpoint of efficient cleaning.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to a following example, unless the summary is exceeded. In the examples, “parts” and “%” mean a weight basis. Moreover, about each physical property of pencil hardness, a bending elastic modulus, and light transmittance, it measured as follows and calculated the average value.

〔Pencil hardness〕
Five test pieces (50 × 50 mm) for measuring physical properties were prepared, and pencil hardness was measured in accordance with JIS K-5600.

(Bending elastic modulus)
Five test pieces (25 × 10 mm) for measuring physical properties were prepared, and each bending elastic modulus (GPa) was measured with an autograph (manufactured by Shimadzu Corporation, AG-5kNE: distance between supporting points 20 mm, 0.5 mm / min). Was measured.

(Light transmittance)
Five test pieces (50 × 50 mm) for measuring physical properties were prepared, and the total light transmittance (%) was measured with a haze meter (NDH-2000, manufactured by Nippon Denshoku Co., Ltd.).

<Example 1>
[Steps (a) to (h) for forming a plastic sheet material]
Six functional urethane acrylates (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UV7600B) 10 are formed on a mold 3 having two optical polishing glasses 1 of 560 × 660 × 8 mm size facing each other and a silicon plate having a thickness of 0.7 mm as a spacer 2. Parts, 90 parts of bis (hydroxymethyl) tricyclo [5.2.1.02,6] decanedimethacrylate (manufactured by Shin-Nakamura Chemical Co., DCP), 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals Co., Ltd., Irgacure 184) 1 Part of the photocurable composition 4 was injected at 23 ° C. The mold 3 was placed horizontally and conveyed by a conveyor, and a metal halide lamp was used to irradiate ultraviolet rays 5 with a light amount of 10 J / cm ² from both sides to obtain a plastic sheet material 6. The plastic sheet material 6 was heated (annealed) in a vacuum oven at 200 ° C. for 2 hours. Thereafter, the plastic sheet material 6 was laser-cut to obtain a plastic sheet material 6 (pencil hardness 5H, bending elastic modulus 4 GPa, light transmittance 92%) having a length of 550 mm, a width of 650 mm, and a thickness of 0.7 mm.

[Washing process to clean plastic sheet material (i)]
While the obtained plastic sheet material 6 was conveyed one by one with a conveying roll in a state inclined by 20 ° with respect to the horizontal plane, a cleaning liquid (KB value ∞) composed of 95% diethylene glycol monobutyl ether and 5% water was included 2 By passing between the rotating brushes 7, the both sides of the plastic sheet material 6 are brushed and cleaned, and then 47% ethyl alcohol, 5.3% normal propyl alcohol, 2.7% isopropyl alcohol, and 45% water. The plastic sheet 8 was manufactured by performing the rinse which sprays the aqueous solution which consists of to both surfaces of the plastic sheet material 6. FIG. Thereafter, moisture was quickly blown off from both surfaces of the plastic sheet 8 using an air knife and dried. The brush portion of the rotating brush 7 was made of nylon, and the conveying speed of the plastic sheet material 6 was 1 m / min.

<Example 2>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that a cleaning liquid (KB value ∞) composed of 70% diethylene glycol monobutyl ether and 30% water was used for the cleaning in the cleaning step (i).

<Example 3>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that a cleaning liquid (KB value ∞) composed of 95% diethylene glycol dibutyl ether and 5% water was used for cleaning in the cleaning step (i).

<Example 4>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that a cleaning liquid (KB value ∞) composed of 95% propylene glycol monopropyl ether and 5% water was used for the cleaning in the cleaning step (i).

<Example 5>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that a cleaning liquid (KB value ∞) composed of 95% diethylene glycol monohexyl ether and 5% water was used for the cleaning in the cleaning step (i).

<Example 6>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that an aqueous solution composed of 55% isopropyl alcohol and 45% water was used for rinsing in the washing step (i).

<Example 7>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that a commercially available acrylic plate (pencil hardness 3H, flexural modulus 3GPa, light transmittance 92%) was used as the plastic sheet material 6.

<Example 8>
In the cleaning step (i), the plastic sheet material 6 is immersed one by one in a cleaning liquid composed of 95% diethylene glycol monobutyl ether and 5% water, and subjected to dip cleaning for 3 minutes, and then the plastic sheet material 6 is cleaned. The plastic sheet 8 was obtained in the same manner as in Example 1 except that both surfaces were rinsed by spraying pure water.

<Example 9>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that in the cleaning step (i), the plastic sheet material 6 was transported by a transport roll in a state parallel to the horizontal plane.

<Example 10>
A plastic sheet 8 was obtained in the same manner as in Example 1 except that rinsing was not performed in the washing step (i).

<Comparative Example 1>
A plastic sheet was obtained in the same manner as in Example 1 except that a cleaning liquid (KB value 300) composed of an aqueous solution containing 20% polyoxyethylene alkyl ether surfactant was used for the cleaning in the cleaning step (i).

  100 plastic sheets of Examples 1 to 10 and Comparative Example 1 were sequentially manufactured. The appearance of each of the 100th plastic sheets produced was observed and evaluated based on the following criteria. The results are shown in Table 1 below. The reason why the appearance of the 100th plastic sheet was observed was that the cleaning solution used for cleaning and the aqueous solution used for rinsing were reused to confirm the durability of these.

[Appearance observation]
Under a white fluorescent lamp (2000 Lux), the surface of the plastic sheet was visually observed for dirt and scratches. Then, the case where no dirt or scratch was observed was evaluated as ◯, the case where it was slightly recognized was evaluated as Δ, and the case where it was clearly recognized at first glance was evaluated as ×.

  As shown in Table 1 above, the plastic sheets of Examples 1 to 10 are well-stained, and scars are hardly recognized, so that the various functions of the plastic sheet material can be exhibited without loss. On the other hand, the plastic sheet of Comparative Example 1 was inferior as a product, although no scratches were observed, but the dirt remained.

  The plastic sheet obtained by the present invention can be advantageously used for various optical materials and electronic materials. For example, adhesive sheet, protective sheet, touch panel, liquid crystal substrate, organic / inorganic EL substrate, PDP substrate, electronic paper substrate, light guide plate, retardation plate, optical filter, various display members, optical disk substrate, etc. It can be used for storage / recording applications, energy applications such as thin film battery substrates and solar cell substrates, optical communication applications such as optical waveguides, and functional films / sheets and various optical films / sheets. In addition to optical materials and electronic materials, it can also be used for lighting materials, automotive materials, building materials, medical materials, stationery, and the like.

DESCRIPTION OF SYMBOLS 1 Glass plate 2 Spacer 3 Mold 4 Photocurable composition 5 Ultraviolet ray 6 Plastic sheet material 7 Rotating brush 8 Plastic sheet i Cleaning process

Claims (10)

  A method for producing a plastic sheet, comprising: washing a plastic sheet material made of a cured resin with a cleaning liquid comprising an aqueous solution containing 50 to 99% by weight of glycol ether.   The method for producing a plastic sheet according to claim 1, wherein an aqueous solution having a KB value (Kauri / Butanol value) of 200 or more is used as the cleaning liquid.   The method for producing a plastic sheet according to claim 1 or 2, wherein the plastic sheet material is washed in a state inclined by 5 to 50 ° with respect to a horizontal plane.   The method for producing a plastic sheet according to any one of claims 1 to 3, wherein the plastic sheet material is cleaned by brushing using a cleaning liquid.   The method for producing a plastic sheet according to any one of claims 1 to 4, wherein rinsing is performed using an aqueous solution containing 10 to 60% by weight of alcohol after washing with a washing solution.   The method for producing a plastic sheet according to claim 5, wherein the aqueous solution used for rinsing contains at least one of ethyl alcohol and isopropyl alcohol.   The method for producing a plastic sheet according to any one of claims 1 to 6, wherein the plastic sheet material is laser-cut.   The plastic sheet material is a resin molded body obtained by curing a photocurable composition containing a polyfunctional (meth) acrylate and a photopolymerization initiator, according to any one of claims 1 to 7. The manufacturing method of the plastic sheet of description.   A plastic sheet produced by the production method according to claim 1.   A plastic substrate for display comprising the plastic sheet according to claim 9.

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