CN110356025B - Method for manufacturing polarizing plate - Google Patents
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- CN110356025B CN110356025B CN201910270641.1A CN201910270641A CN110356025B CN 110356025 B CN110356025 B CN 110356025B CN 201910270641 A CN201910270641 A CN 201910270641A CN 110356025 B CN110356025 B CN 110356025B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/00634—Production of filters
- B29D11/00644—Production of filters polarizing
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Abstract
The present application provides a method for manufacturing a polarizing plate, which can obtain a polarizing plate having excellent optical characteristics. A method for manufacturing a polarizing plate, which comprises subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step and a stretching step, and then sequentially subjecting the film to a cleaning step and a drying step, wherein the drying step comprises: a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm or more and 1N/mm or less in a conveying direction of the polyvinyl alcohol film, wherein the polyvinyl alcohol film satisfies the following condition, that is, formula (1), when a total stretch ratio after the washing step is defined as x and a total stretch ratio after the drying step is defined as y: y is more than or equal to 0.7x +1.77 (in formula (1), x is more than 5.6, and y is less than 7.).
Description
Technical Field
The present invention relates to a method for manufacturing a polarizing plate.
Background
Conventionally, a dyed (dichroic material-containing) polyvinyl alcohol film has been used as a polarizing plate used for various image display devices such as liquid crystal display devices and organic EL display devices, in order to achieve both high transmittance and high polarization degree. The polarizing plate is manufactured as follows: the polyvinyl alcohol film is subjected to various treatments such as swelling, dyeing, crosslinking, and stretching in a bath, then subjected to a cleaning treatment, and then dried. The polarizing plate is generally used in the form of a polarizing film having a protective film such as triacetyl cellulose bonded to one or both surfaces thereof using an adhesive.
As a method for producing such a polarizing plate, for example, a method for controlling the moisture content of a polyvinyl alcohol film in a drying step is known (patent document 1), and a method for producing a polarizing plate having a step for drying while restricting the width direction of a polyvinyl alcohol film in a drying step is also known (patent document 2).
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2009-163202
Patent document 2: japanese laid-open patent publication No. 2014-146035
Disclosure of Invention
Problems to be solved by the invention
Although the polarizing plate disclosed in the above patent document has good optical characteristics, in the market, a polarizing plate having higher optical characteristics is required in accordance with the improvement in performance of an image display device having a polarizing plate.
In view of the above circumstances, an object of the present invention is to provide a method for producing a polarizing plate, which can obtain a polarizing plate having excellent optical characteristics.
Means for solving the problems
That is, the present invention relates to a method for producing a polarizing plate, which comprises subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step, and a stretching step, and then sequentially subjecting the polyvinyl alcohol film to a cleaning step and a drying step, wherein the drying step comprises: a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm or more and 1N/mm or less in a conveying direction of the polyvinyl alcohol film, wherein the polyvinyl alcohol film satisfies the following condition, that is, formula (1), when a total stretch ratio after the washing step is defined as x and a total stretch ratio after the drying step is defined as y: y is more than or equal to 0.7x +1.77 (in formula (1), x is more than 5.6, and y is less than 7).
Effects of the invention
The mechanism of action of the effect of the method for producing a polarizing plate of the present invention is not clearly understood in detail, but can be estimated as follows. However, the present invention may be practiced without limitation to the mechanism of action to break \37320.
The method for producing a polarizing plate of the present invention is a method for producing a polarizing plate, wherein the drying step includes a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm or more and 1N/mm or less in a conveying direction of the polyvinyl alcohol film, and the polyvinyl alcohol film satisfies formula (1) when a total stretch ratio after the washing step is defined as x and a total stretch ratio after the drying step is defined as y: y is not less than 0.7x +1.77 (in formula (1), x is not less than 5.6 and y is not more than 7). In the method for producing a polarizing plate, as in the above-mentioned patent document 2, an operation of applying tension in the width direction and the longitudinal direction (carrying direction) of the polyvinyl alcohol film in the drying step is known, but in the method for producing a polarizing plate of the present invention, it was found that the orientation of the polarizing plate is improved and the optical properties of the obtained polarizing plate are improved by drying while applying a certain amount of tension in the carrying direction of the polyvinyl alcohol film. In particular, in the method for producing a polarizing plate, when the total stretch ratio (x) after the washing step and the total stretch ratio (y) after the drying step satisfy the relationship of the formula (1), the orientation is further improved, and thus a polarizing plate having excellent optical characteristics can be obtained.
Drawings
Fig. 1 is a schematic diagram showing a method of manufacturing a polarizing plate of the present invention.
Detailed Description
< method for producing polarizing plate >
The method for producing a polarizing plate of the present invention is a method for producing a polarizing plate, which comprises subjecting a polyvinyl alcohol film to an optional swelling step, and after at least a dyeing step, a crosslinking step, and a stretching step, sequentially subjecting the film to a washing step and a drying step, wherein the drying step comprises: a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm or more and 1N/mm or less in a conveying direction of the polyvinyl alcohol film, wherein the polyvinyl alcohol film satisfies, when a total stretch ratio after the washing step is defined as x and a total stretch ratio after the drying step is defined as y: formula (1): y is not less than 0.7x +1.77 (in formula (1), x is not less than 5.6 and y is not more than 7.).
The concept of the method for manufacturing a polarizing plate of the present invention is illustrated by fig. 1. In fig. 1, a polyvinyl alcohol (PVA) film (raw material PVA film) F is arranged in a roll shape on the left side of the drawing, and is conveyed in the right direction of the drawing by a feed roller 8. The polyvinyl alcohol (PVA) film F is usually subjected to a swelling step in the swelling treatment tank 1, a dyeing step in the dyeing treatment tank 2, a crosslinking step in the crosslinking treatment tank 3, a stretching step in the stretching treatment tank 4, a cleaning step in the cleaning treatment tank 5, and a drying step in the drying treatment section 6, and the obtained polarizing plate F1 is collected in a roll form.
The polyvinyl alcohol (PVA) film may be a film having light transmittance in the visible light region and having a dichroic substance such as iodine or a dichroic dye dispersed and adsorbed therein, without any particular limitation. The PVA film to be used as a material is preferably about 10 to 300. Mu.m, more preferably about 20 to 100. Mu.m, and preferably about 100 to 5000mm in width.
Examples of the material of the polyvinyl alcohol film include polyvinyl alcohol and derivatives thereof. Examples of the derivative of the polyvinyl alcohol include: polyvinyl formal, polyvinyl acetal; and compounds modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, and acrylamides. The average polymerization degree of the polyvinyl alcohol is preferably about 100 to 10,000, more preferably about 1,000 to 10,000, and still more preferably about 2,000 to 4,500. The saponification degree of the polyvinyl alcohol is preferably about 80 to 100 mol%, and more preferably about 95 to 99.95 mol%. The average polymerization degree and the saponification degree can be determined in accordance with JIS K6726.
The polyvinyl alcohol film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as glycerin, diglycerin, triglycerol, ethylene glycol, propylene glycol, and polyethylene glycol, and condensates thereof. The amount of the additive is not particularly limited, but is preferably about 20% by weight or less in the polyvinyl alcohol film.
As shown in fig. 1, the feed roller 8 and the first to sixth pinch rollers (10, 20, 30, 40, 50, 60) are disposed before and after the treatment tank (treatment section) in each step. The feed roller 8 and the first to sixth pinch rollers (10, 20, 30, 40, 50, 60) convey a polyvinyl alcohol (PVA) film, and the first to fifth pinch rollers (10, 20, 30, 40, 50) also perform a liquid removal treatment of the treatment liquid used in each treatment tank.
The feed roller 8 and the first to sixth pinch rollers may be configured to include drive rollers (02, 12, 22, 32, 42, 52, 62) rotationally driven in conjunction with a motor (not shown) and driven rollers (01, 11, 21, 31, 41, 51, 61) rotationally driven in conjunction with the drive rollers. In fig. 1, the positional relationship between the driving roller and the driven roller may be reversed, or both rollers may be configured as driving rollers. The feed roller 8 and 2 rollers (a pair of rollers) of the first to sixth pinch rollers may be disposed in a horizontal direction, a vertical direction, or an inclined direction at a predetermined angle as long as they are of a type in which the polyvinyl alcohol (PVA) film is conveyed and the liquid removing treatment is performed.
The drying step of the method for producing a polarizing plate of the present invention includes: and drying the polyvinyl alcohol film while applying a tension of 0.1N/mm to 1N/mm in a conveying direction of the polyvinyl alcohol film. The tension is preferably 0.15N/mm or more, and more preferably 0.2N/mm or more, from the viewpoint of improving the optical characteristics of the polarizing plate. Further, in order to achieve the conveyance stability during stretching, it is preferably 0.8N/mm or less, more preferably 0.7N/mm or less, and still more preferably 0.6N/mm or less. As shown in fig. 1, the tension can be detected by a controller, not shown, provided in the guide roll 7, and can be set by adjusting the speed of the circumferential speed of the fifth pinch roll (50) and the speed of the circumferential speed of the sixth pinch roll (60). In general, in order to increase the tension, the circumferential speed of the sixth pinch roll (60) may be controlled to be faster than the circumferential speed of the fifth pinch roll (50). The peripheral speed can be detected by an encoder connected to a servo motor, and the peripheral speed of each roller described later can be detected in the same manner.
In the method for producing a polarizing plate of the present invention, when the total stretching ratio after the washing step is defined as x (unit: times) and the total stretching ratio after the drying step is defined as y (unit: times), the polyvinyl alcohol-based film satisfies formula (1): y is not less than 0.7x +1.77 (in formula (1), x is not less than 5.6 and y is not more than 7.). When the polyvinyl alcohol film satisfies the above relational expression, the orientation of the polarizing plate is improved, and thus the optical properties of the obtained polarizing plate are improved. The total stretch ratio (x) after the cleaning step is preferably 5.7 or more, and more preferably 5.8 or more, from the viewpoint of improving the optical properties of the polarizing plate. From the viewpoint of conveyance stability during stretching, the total stretching magnification (y) after the drying step is preferably 6.8 or less, and more preferably 6.6 or less. The total stretch ratio (x) after the cleaning step can be calculated from the peripheral speed ratio (winding peripheral speed/feeding peripheral speed) between the feeding peripheral speed of the feed roller 8 and the winding peripheral speed of the fifth pinch roller (50), and the total stretch ratio (y) after the drying step can be calculated from the peripheral speed ratio (winding peripheral speed/feeding peripheral speed) between the feeding peripheral speed of the feed roller 8 and the winding peripheral speed of the sixth pinch roller (60). In addition, in the drying step, since the polyvinyl alcohol film is also subjected to a force of shrinking in the conveyance direction due to evaporation of water, even if a constant tension is applied to the polyvinyl alcohol film, the total stretching magnification (y) after the drying step may be smaller than the total stretching magnification (x) after the cleaning step.
In the method for producing a polarizing plate of the present invention, the polyvinyl alcohol film preferably satisfies formula (2): y.ltoreq.0.7x +1.94 (in formula (2), x and y are the same as in formula (1) above), and more preferably satisfies formula (3): y is less than or equal to 0.7x +1.84 (in the formula (3), x and y are the same as those in the formula (1)).
The draw ratio in the swelling step can be calculated from the ratio of the delivery peripheral speed of the feed roller 8 to the winding peripheral speed of the first pinch roller 10 (winding peripheral speed/delivery peripheral speed). The draw ratio in the dyeing step can be calculated from the ratio of the delivery circumferential speed of the first pinch roll (10) to the winding circumferential speed of the second pinch roll (20) (winding circumferential speed/delivery circumferential speed). The draw ratio in the crosslinking step can be calculated from the ratio of the delivery peripheral speed of the second pinch roll (20) to the winding peripheral speed of the third pinch roll (30) (winding peripheral speed/delivery peripheral speed). The draw ratio in the drawing step can be calculated from the ratio of the delivery peripheral speed of the third pinch roll (30) to the winding peripheral speed of the fourth pinch roll (40) (winding peripheral speed/delivery peripheral speed). When the number of the pinch rollers disposed between the processing tanks (processing units) is 1, the winding peripheral speed and the feeding peripheral speed of the pinch rollers are the same value.
The stretching ratio in the swelling step is preferably about 1.5 to 3.0 times, and more preferably about 1.8 to 2.6 times. The stretch ratio in the dyeing step is preferably about 1.1 to 2.0 times, and more preferably about 1.1 to 1.6 times. The stretching ratio in the crosslinking step is preferably about 1.1 to 1.7 times, and more preferably about 1.1 to 1.4 times. The stretching ratio in the stretching step is preferably about 1.2 to 1.9 times, and more preferably about 1.5 to 1.9 times.
Hereinafter, each treatment bath and the like in each treatment step will be described.
The swelling step is an optional step in the method for producing a polarizing plate of the present invention, and is a treatment step of immersing the polyvinyl alcohol film in a swelling bath, and can remove dirt, an anti-blocking agent, and the like on the surface of the polyvinyl alcohol film, and can suppress uneven dyeing by swelling the polyvinyl alcohol film. The swelling bath generally uses a medium containing water as a main component, such as water, distilled water, or pure water. The swelling bath may be added with a surfactant, an alcohol, or the like as appropriate according to a conventional method.
The temperature of the swelling bath is preferably about 10 to 60 ℃, and more preferably about 15 to 45 ℃. The swelling degree of the polyvinyl alcohol film is affected by the temperature of the swelling bath, and therefore the immersion time in the swelling bath is not generally determined, but is preferably about 5 to 300 seconds, and more preferably about 10 to 200 seconds. The swelling step may be performed only 1 time, or may be performed twice or more as necessary.
The dyeing step is a treatment step of immersing the polyvinyl alcohol film in a dyeing bath (iodine solution), and the polyvinyl alcohol film may be aligned by adsorbing a dichroic substance such as iodine or a dichroic dye to the polyvinyl alcohol film. The iodine solution is preferably an aqueous iodine solution containing an iodide as iodine and a dissolution assistant. The iodide includes potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among them, potassium iodide is suitable from the viewpoint of controlling the content of the potassium in the polarizing plate.
The concentration of iodine in the dyeing bath is preferably about 0.01 to 1 wt%, more preferably about 0.02 to 0.5 wt%. The concentration of the iodide in the dyeing bath is preferably about 0.01 to 10% by weight, and more preferably about 0.05 to 5% by weight.
The temperature of the dyeing bath is preferably about 10 to 50 ℃, and more preferably about 15 to 45 ℃. The degree of dyeing of the polyvinyl alcohol film is affected by the temperature of the dyeing bath, and therefore the immersion time in the dyeing bath is not generally defined, but is preferably about 10 to 300 seconds, and more preferably about 20 to 240 seconds. The dyeing step may be performed only 1 time, or may be performed two or more times as needed.
The crosslinking step is a treatment step of immersing the polyvinyl alcohol film dyed in the dyeing step in a treatment bath (crosslinking bath) containing a boron compound, and the polyvinyl alcohol film is crosslinked with the boron compound so that iodine molecules or dye molecules can be adsorbed to the crosslinked structure. Examples of the boron compound include boric acid, borate, and borax. The crosslinking bath is usually an aqueous solution, but may be a mixed solution of water and an organic solvent miscible with water, for example. In addition, from the viewpoint of controlling the content of potassium in the polarizing plate, the crosslinking bath preferably contains potassium iodide.
The concentration of the boron compound in the crosslinking bath is preferably about 1 to 15 wt%, more preferably about 1.5 to 10 wt%, and still more preferably about 2 to 5 wt%. When potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, and more preferably about 1.5 to 10% by weight.
The temperature of the crosslinking bath is preferably about 20 to 70 ℃, and more preferably about 30 to 60 ℃. The degree of crosslinking of the polyvinyl alcohol film is affected by the temperature of the crosslinking bath, and therefore the immersion time in the crosslinking bath is not generally determined, but is preferably about 5 to 300 seconds, and more preferably about 10 to 200 seconds. The crosslinking step may be performed only 1 time, or may be performed twice or more as necessary.
The stretching step is a treatment step of stretching the polyvinyl alcohol film at a predetermined magnification in at least one direction. In general, a polyvinyl alcohol film is uniaxially stretched in the transport direction (longitudinal direction). The method of stretching is not particularly limited, and any of wet stretching and dry stretching may be employed. The stretching step may be performed only 1 time, or may be performed twice or more as necessary. The stretching step may be performed at any stage in the production of the polarizing plate.
In the wet stretching method, a solvent such as water or a mixed solution of an organic solvent miscible with water and water is usually used as the treatment bath (stretching bath). From the viewpoint of controlling the content of potassium in the polarizing plate, the stretching bath preferably contains potassium iodide. When potassium iodide is used in the stretching bath, the concentration of potassium iodide in the stretching bath is preferably about 1 to 15% by weight, and more preferably about 2 to 10% by weight. In addition, in order to increase the degree of crosslinking, the treatment bath (stretching bath) may contain the boron compound, and in this case, the concentration of the boron compound in the stretching bath is preferably about 1 to 15% by weight, and more preferably about 1.5 to 10% by weight.
The temperature of the stretching bath is preferably about 25 to 80 ℃, and more preferably about 40 to 75 ℃. The degree of stretching of the polyvinyl alcohol film is affected by the temperature of the stretching bath, and therefore the immersion time in the stretching bath is not generally defined, but is preferably about 10 to 800 seconds, and more preferably about 30 to 500 seconds. The stretching treatment in the wet stretching method may be performed together with any 1 or more treatment steps among the swelling step, the dyeing step, the crosslinking step, and the washing step.
Examples of the dry stretching method include an inter-roll stretching method, a hot-roll stretching method, and a compression-stretching method.
The cleaning step is a treatment step of immersing the polyvinyl alcohol film in a cleaning bath, and foreign matter remaining on the surface of the polyvinyl alcohol film or the like can be removed. The cleaning bath usually uses a medium containing water as a main component, such as water, distilled water, or pure water. In addition, from the viewpoint of controlling the content of potassium in the polarizing plate, potassium iodide is preferably used in the cleaning bath, and in this case, the concentration of potassium iodide in the cleaning bath is preferably about 1 to 10% by weight, more preferably about 2 to 4% by weight, and further preferably about 1.6 to 3.8% by weight.
The temperature of the cleaning bath is preferably about 5 to 50 ℃, more preferably about 10 to 40 ℃, and still more preferably about 15 to 30 ℃. The degree of cleaning of the polyvinyl alcohol film is affected by the temperature of the cleaning bath, and therefore the immersion time in the cleaning bath cannot be determined generally, but is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and still more preferably about 3 to 20 seconds. The swelling step may be performed only 1 time, or may be performed two or more times as needed.
The drying step includes a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm to 1N/mm in a carrying direction of the polyvinyl alcohol film, and is a step of drying the polyvinyl alcohol film washed in the washing step to obtain a polarizing plate, and the polarizing plate having a desired moisture content is obtained by drying. The drying is carried out by any suitable method, and examples thereof include natural drying, air-blowing drying, and heat drying. The polarizing plate preferably has a water content of about 12 to 25 wt%, more preferably about 13 to 20 wt%. The moisture content of the polarizing plate was calculated from the following equation based on the initial weight of the sample cut out to a size of 100mm square and the dry weight after drying at 120 ℃ for 2 hours.
Water percentage (% by weight) = { (initial weight-dry weight)/initial weight } × 100
The drying temperature is preferably about 20 to 150 ℃, and more preferably about 25 to 100 ℃. The drying time is not generally defined because the degree of drying of the polarizing plate is affected by the drying temperature, but is preferably about 30 to 600 seconds, and more preferably about 60 to 300 seconds. The drying step may be performed only 1 time, or may be performed twice or more as necessary.
The thickness of the polarizing plate is preferably about 1 to 30 μm, and more preferably about 5 to 25 μm. In particular, in order to obtain a polarizing plate having a thickness of 10 μm or less, methods for producing a thin polarizing plate disclosed in jp 2009-098653 a, jp 2013-238640 a, and the like, in which a polyvinyl alcohol film formed on a thermoplastic resin substrate is used as a laminate of the polyvinyl alcohol films, can be applied.
< polarizing film >
The obtained polarizing plate is generally used in the form of a polarizing film by attaching a transparent protective film on at least one side thereof according to a conventional method. The transparent protective film is not particularly limited, and various transparent protective films conventionally used for polarizing films can be used. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, water barrier property, isotropy, and the like can be used. Examples of the thermoplastic resin include cellulose ester resins such as triacetylcellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins such as nylon and aromatic polyamide, polyimide resins, polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers, (meth) acrylic resins, cyclic polyolefin resins having a ring system or a norbornene structure (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.
When the transparent protective films are bonded to both surfaces of the polarizing plate, the transparent protective films may be the same or different.
The transparent protective film may be a retardation plate having a retardation of 40nm or more in the front direction and/or 80nm or more in the thickness direction. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as a transparent protective film, and therefore, the thickness can be reduced.
Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, and a retardation plate in which an oriented layer of a liquid crystal polymer is supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. The phase plate may be bonded to a transparent protective film having no retardation.
The transparent protective film may be subjected to a surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.
The surface of the transparent protective film to which the polarizing plate is not attached may be subjected to hard coat treatment, antireflection treatment, treatment for the purpose of preventing adhesion, diffusion, or antiglare. The hard coat treatment, the treatment for the purpose of antireflection, anti-sticking, diffusion layer, or antiglare, and the like may be provided as a transparent protective film itself, or may be provided as a separate optical layer from the transparent protective film.
The transparent protective film may contain an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, an antistatic agent, a pigment, a coloring agent, and the like, as optional appropriate additives.
In order to bond the polarizing plate and the transparent protective film, an adhesive is generally used. Examples of the adhesive include an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex adhesive, and an aqueous polyester. The adhesive is usually used in the form of an aqueous adhesive, and usually contains 0.5 to 60% by weight of a solid content. Examples of the adhesive include an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like in addition to the above. The adhesive may contain a metal compound filler.
The adhesive may be applied to either the transparent protective film or the polarizing plate, or to both of them. After the bonding, a drying step is performed to form an adhesive layer including a coating dry layer. The polarizing plate and the transparent protective film may be bonded to each other by a roll laminator or the like. After the drying step, ultraviolet rays and electron beams may be irradiated as necessary. The thickness of the adhesive layer is not particularly limited, but is preferably about 30 to 5000nm, and more preferably about 100 to 1000 nm.
Examples
The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
< example 1 >
< production of polarizing plate >
A polyvinyl alcohol film having a polymerization degree of 2,400, a saponification degree of 99.9 mol%, a thickness of 45 μm and a width of 3390mm was prepared. The polyvinyl alcohol film was subjected to the following steps by the production method shown in fig. 1. Specifically, the polyvinyl alcohol film was immersed in a swelling bath (water bath) at 27 ℃ for 70 seconds to swell the film, and was stretched in the conveyance direction so that the stretching ratio in the swelling step was 2.210 times (swelling step). Next, the obtained polyvinyl alcohol film was immersed in a dyeing bath (aqueous solution having an iodine concentration of 8 wt%) at 30 ℃ for 45 seconds to be dyed, and was stretched in the carrying direction so that the stretching ratio in the dyeing step was 1.176 times (dyeing step). Next, the dyed polyvinyl alcohol film was immersed in a crosslinking bath (aqueous solution having a boric acid concentration of 4 wt% and a potassium iodide concentration of 3 wt%) at 40 ℃ for 43 seconds, and stretched in the conveyance direction so that the stretching ratio in the crosslinking step was 1.296 times (crosslinking step). Then, the obtained polyvinyl alcohol film was immersed in a stretching bath (aqueous solution having a boric acid concentration of 3 wt% and a potassium iodide concentration of 5 wt%) at 60 ℃ for 31 seconds, and stretched in the carrying direction so that the stretching ratio in the stretching step was 1.786 times (stretching step). Then, the obtained polyvinyl alcohol film was immersed in a cleaning bath (aqueous solution having a potassium iodide concentration of 5.5 wt%) at 27 ℃ for 10 seconds, and was stretched in the carrying direction so that the total stretching ratio (x) after the cleaning step was 6.020 times (cleaning step). The washed polyvinyl alcohol film was dried at 55 ℃ for 1 minute while applying a tension of 0.29N/mm in the carrying direction, and a polarizing plate was produced so that the total stretching ratio (y) after the drying step was 6.075 times in the carrying direction. The thickness of the polarizing plate was 17 μm, and the moisture percentage of the polarizing plate was 15 wt%.
The respective stretching ratios and the total stretching ratio can be calculated from the peripheral speed ratios (winding peripheral speed/feeding peripheral speed) at the feed roller and the pinch roller, as described above. The peripheral speed can be set to 3 decimal places, and in the system, when the peripheral speed deviates from the set value of the peripheral speed, an encoder connected with a servo motor made by Mitsubishi motor can sense the abnormality.
< production of polarizing film >
The adhesive was prepared by mixing 12 parts by weight of the radical polymerizable compound (a), 35 parts by weight of the radical polymerizable compound (b), 40 parts by weight of the radical polymerizable compound (c), 10 parts by weight of the oligomer compound (d), 2 parts by weight of the photopolymerization initiator (e), and 1 part by weight of the photosensitizer (f), and stirring the mixture at 50 ℃ for 1 hour to obtain an active energy ray-curable adhesive. The above active energy ray-curable adhesive was applied to each of the bonding surfaces of a first transparent protective film (acrylic film, manufactured by Toyo Steel plate Co., ltd.) and a second transparent protective film (COP film, manufactured by Nippon Raynaud Co., ltd., trade name "ZEONOR") so as to have a thickness of 0.7 μm using an MCD applicator (manufactured by Fuji machine Co., ltd.) (unit shape: honeycomb, gravure roll number: 1000 pieces/inch, rotation speed: 140%/line speed (Japanese: per: 12521\\\/1245231speed), and the resultant was bonded to both surfaces of the above polarizing plate X by a roll machine. Then, the above visible light rays were irradiated from the side (both sides) of the transparent protective film to be bonded with an active energy ray irradiation apparatus to both sides thereof, and the active energy ray-curable adhesive was cured, followed by hot air drying at 70 ℃ for 3 minutes, to obtain a polarizing film having transparent protective films on both sides of the polarizing plate.
The radical polymerizable compound (a) is HEAA (hydroxyethyl acrylamide), manufactured by KJ CHEMICALS; the radical polymerizable compound (b) is ACMO (acryloyl morpholine), manufactured by KJ CHEMICALS corporation; the radical polymerizable compound (c) is Light-Acrylate 1,9ND-A (1, 9-nonanediol diacrylate), available from Kyoeisha chemical Co., ltd; the oligomer compound (d) is ARUFON UG-4010 (epoxy-modified acrylic oligomer) manufactured by Toyo Synthesis; the photopolymerization initiator (e) is Omnirad 907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), IGM Resins B.V. Co., ltd; the photosensitizer (f) is KAYACURE DETX-S (2, 4-diethylthioxanthone), manufactured by Nippon Chemicals.
[ evaluation of optical Properties of polarizing film ]
The polarizing film obtained above was measured for the monomer transmittance (Ts) and the degree of polarization (P). The above-mentioned monomer transmittance and degree of polarization can be measured by using a spectrophotometer (manufactured by japan spectrophotometers, product name "V7100"). As a specific method for measuring the degree of polarization, the parallel transmittance (H) of the polarizing plate can be measured 0 ) And orthogonal transmittance (H) 90 ) And using the formula: degree of polarization (%) = { (H) 0 －H 90 )/(H 0 +H 90 )} 1/2 X 100 was determined. The above parallel transmittance (H) 0 ) Comprises the following steps: the transmittance of a parallel laminated polarizing plate prepared by stacking 2 identical polarizing plates so that their absorption axes are parallel to each other. Further, the above orthogonal transmittance (H) 90 ) Comprises the following steps: the transmittance of an orthogonal laminated polarizing plate prepared by stacking 2 identical polarizing plates so that the absorption axes thereof are orthogonal to each other. The transmittance thereof was a Y value obtained by performing visibility correction using a 2-degree field of view (C light source) according to JIS Z8701-1982. Further, the orthogonal transmittance (%) at a wavelength of 410nm was also measured at the same time. The results are shown in Table 1.
The monomer transmittance is preferably 40% or more, more preferably 43% or more, and further preferably 43.1% or more. The polarization degree is preferably 90% or more, more preferably 95% or more, further preferably 99% or more, further preferably 99.9% or more, and further preferably 99.99% or more. The orthogonal transmittance at a wavelength of 410nm is preferably 0.1% or less, more preferably 0.06% or less, and still more preferably 0.05% or less.
< production of polarizing plate and production of polarizing film >
< examples 2 to 14 and comparative examples 1 to 4 >
A polarizing plate was produced and a polarizing film was produced in the same manner as in example 1, except that the stretching ratio in the stretching step, the total stretching ratio (x) after the washing step, the total stretching ratio (y) after the drying step, and the tension in the drying step were adjusted to values shown in tables 1 and 2. The immersion time and the drying time in each treatment liquid are slightly different from those in example 1 due to the influence of the stretching ratio and the total stretching ratio.
The polarizing films of examples 2 to 14 and comparative examples 1 to 4 obtained in the above were used to perform the evaluation in [ evaluation of optical properties of polarizing film ] described above. The results are shown in tables 1 and 2.
[ Table 1]
[ Table 2]
The polarizing films of examples are more excellent in optical properties because the polarizing films of examples tend to have a higher monomer transmittance (%) and a lower orthogonal transmittance (%) at a wavelength of 410nm than those of comparative examples by comparing the monomer transmittance (%) and the orthogonal transmittance (%) at a wavelength of 410nm of the polarizing films obtained in the above examples with those of comparative examples. In particular, when the polarizing films of examples and comparative examples having the same degree of monomer transmittance (%) were compared, it was found that the orthogonal transmittance (%) at a wavelength of 410nm was lower in the polarizing film of examples, and thus it was found that the optical characteristics were more excellent.
In addition, the polarizing films of the examples have a tendency to have higher monomer transmittance (%) and higher polarization (%) than those of the polarizing films of the comparative examples, and thus are more excellent in optical properties, as compared with the polarizing films of the comparative examples in terms of monomer transmittance (%) and polarization (%). In particular, when the polarizing films of examples and comparative examples having the same degree of monomer transmittance (%) were compared, it was found that the degree of polarization (%) of the polarizing film of the example was higher, and the optical properties were more excellent.
Description of the symbols
F polyvinyl alcohol (PVA) film
F1 Polarizing plate
1. Swelling treatment tank
2. Dyeing treatment tank
3. Cross-linking treatment tank
4. Stretching treatment tank
5. Cleaning treatment tank
6. Drying treatment part
7. Guide roller
8. Feed roller
01. 11, 21, 31, 41, 51, 61 driven roller
02. 12, 22, 32, 42, 52, 62 drive roller
10. First pinch roll
20. Second pinch roll
30. Third pinch roll
40. Fourth pinch roll
50. Fifth pinch roll
60. Sixth pinch roll
Claims (4)
1. A method for producing a polarizing film comprising a polarizing plate and a transparent protective film laminated on at least one surface of the polarizing plate, wherein the polarizing plate is obtained by subjecting a polyvinyl alcohol film to at least a swelling step, a dyeing step, a crosslinking step and a stretching step, and then successively subjecting the film to a washing step and a drying step,
the drying process includes: a step of drying the polyvinyl alcohol film while applying a tension of 0.1N/mm to 1N/mm in the direction of conveyance of the polyvinyl alcohol film, and
wherein the stretching ratio of the swelling step is 1.5 to 3.0 times, the stretching ratio of the dyeing step is 1.1 to 2.0 times, the stretching ratio of the crosslinking step is 1.1 to 1.7 times, the stretching ratio of the stretching step is 1.5 to 1.9 times, and the polyvinyl alcohol film satisfies the following conditions when the total stretching ratio after the washing step is defined as x and the total stretching ratio after the drying step is defined as y:
formula (1): y is more than or equal to 0.7x +1.77
In the formula (1), x is 5.6 or more and y is 7 or less,
the polarizing film has a monomer transmittance of 43.1% or more.
2. The method for manufacturing a polarizing film according to claim 1,
in the formula (1), y is 6.3 or less.
3. The method for manufacturing a polarizing film according to claim 1 or 2,
the polyvinyl alcohol film satisfies the following conditions:
formula (2): y is less than or equal to 0.7x +1.94
In the formula (2), x and y are the same as those in the formula (1).
4. The method for manufacturing a polarizing film according to claim 1 or 2,
the degree of polymerization of the polyvinyl alcohol film is 2,000 or more.
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| JP2019-015628 | 2019-01-31 | ||
| JP2019015628A JP7058230B2 (en) | 2018-04-09 | 2019-01-31 | How to manufacture a extruder |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101004464A (en) * | 2006-01-17 | 2007-07-25 | 达信科技股份有限公司 | Polarized light film, polarized light plate, and fabricating method |
| KR100932049B1 (en) * | 2008-08-22 | 2009-12-15 | 주식회사 에이스 디지텍 | Manufacturing method for polarizing film |
| CN102257413A (en) * | 2008-12-18 | 2011-11-23 | 可乐丽股份有限公司 | Method for producing polarizing film |
| CN102401915A (en) * | 2010-09-16 | 2012-04-04 | 住友化学株式会社 | Anti-dazzle Thin Film And Liquid Crystal Display Device |
| CN103059486A (en) * | 2012-12-03 | 2013-04-24 | 云南云天化股份有限公司 | Manufacturing method of water-resistant polyvinyl alcohol film |
| JP2017106969A (en) * | 2015-12-07 | 2017-06-15 | 住友化学株式会社 | Method for manufacturing polarizing film |
| CN107003464A (en) * | 2014-12-12 | 2017-08-01 | 住友化学株式会社 | The manufacture method and polarizing coating of polarizing coating |
| CN107614578A (en) * | 2015-06-24 | 2018-01-19 | 日本合成化学工业株式会社 | The manufacture method and light polarizing film of polyvinyl alcohol film, polyvinyl alcohol film |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6897916B2 (en) * | 2001-09-11 | 2005-05-24 | Nitto Denko Corporation | Polarizing plate, optical element, and liquid crystal display |
-
2019
- 2019-04-04 CN CN201910270641.1A patent/CN110356025B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101004464A (en) * | 2006-01-17 | 2007-07-25 | 达信科技股份有限公司 | Polarized light film, polarized light plate, and fabricating method |
| KR100932049B1 (en) * | 2008-08-22 | 2009-12-15 | 주식회사 에이스 디지텍 | Manufacturing method for polarizing film |
| CN102257413A (en) * | 2008-12-18 | 2011-11-23 | 可乐丽股份有限公司 | Method for producing polarizing film |
| CN102401915A (en) * | 2010-09-16 | 2012-04-04 | 住友化学株式会社 | Anti-dazzle Thin Film And Liquid Crystal Display Device |
| CN103059486A (en) * | 2012-12-03 | 2013-04-24 | 云南云天化股份有限公司 | Manufacturing method of water-resistant polyvinyl alcohol film |
| CN107003464A (en) * | 2014-12-12 | 2017-08-01 | 住友化学株式会社 | The manufacture method and polarizing coating of polarizing coating |
| CN107614578A (en) * | 2015-06-24 | 2018-01-19 | 日本合成化学工业株式会社 | The manufacture method and light polarizing film of polyvinyl alcohol film, polyvinyl alcohol film |
| JP2017106969A (en) * | 2015-12-07 | 2017-06-15 | 住友化学株式会社 | Method for manufacturing polarizing film |
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