JP2012066196A - Coater and coating film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coater which can reduce stagnation of a coating liquid within a coating liquid pan, eliminate the possibility of precipitation and flocculation of fine particles and pigments contained in the coating liquid and disperse resins and solvents contained in the coating liquid and facilitates cleaning of the inside of the coating liquid pan, a transfer roll and a circulation system for the coating liquid.SOLUTION: The coater is for applying a coating liquid to a continuously running belt-like substrate and includes a coating liquid pan storing the coating liquid, a transfer roll transferring the coating liquid to the substrate, an ultrasonic oscillator generating electric oscillation signals, ultrasonic vibrators arranged on the outside walls of the side and bottom walls of the coating liquid pan and converting the electric oscillation signals into mechanical vibrations, coating liquid supplying piping arranged on the bottom surface of the coating liquid pan, coating liquid discharging piping arranged in the side wall of the coating liquid pan and a coating liquid circulation section which circulates the coating liquid by discharging the coating liquid in the coating liquid pan from the coating liquid discharging piping out of the coating liquid pan and supplying the coating liquid from the coating liquid supplying piping.

Description

  The present invention relates to a coating apparatus that uses rolls such as a gravure coater, a micro gravure coater, and a bar coater, and more specifically, prevents precipitation and aggregation of a coating liquid in a coating liquid pan such as an ink pan, and further includes a resin contained in the coating liquid. The present invention also relates to a coating apparatus having an ultrasonic vibrator and an ultrasonic transmitter that disperse a solvent and a solvent and facilitate cleaning of a coating liquid circulation system.

  Conventionally, roll coaters, gravure coaters, and the like have been used as applicators that use rolls, particularly as a method for applying a coating solution to a strip-shaped substrate that is continuously running. Such a coater is a system in which a coating liquid is drawn up from an ink pan by a roll and transferred to a substrate. However, if the coating liquid contains fine particles such as alumina or silica or contains a pigment, these are coated. When the specific gravity is higher than that of the resin or solvent in the liquid, it may also agglomerate, so that it settles in a portion that tends to stay in the ink pan, for example, an edge portion or the bottom of the ink pan. When this happens, the composition of the coating liquid changes, and the physical properties change over time. For example, in an AG (anti-glare) film, the optical characteristics and the appearance are different from those in the initial stage due to changes in the optical characteristics such as noise and gloss.

  Therefore, as a method for solving the above-mentioned problems, the dispersed and mixed coating liquid is supplied to a first sedimentation tank having a funnel part and a collection part on the bottom wall, and is allowed to stand and aggregates and sediments in the first sedimentation tank. And removing the agglomerates and sediment in the second sedimentation tank before gravure printing by supplying the coating liquid to the second sedimentation tank having a funnel part and a collection part on the bottom wall and allowing it to stand. A technique is disclosed in which a coating liquid from which agglomerates and sediments have been removed in advance by stirring is stirred by rotation of a gravure roll to prevent reagglomeration of the filler that occurs over time (Patent Document 1).

JP 2008-16313 A

  However, by repeating the removal in the two settling tanks as described above, the initial composition changes and various characteristics are changed. In particular, in a coating liquid that tends to settle or agglomerate, it becomes prominent and it becomes difficult to manage properties. In addition, there is a problem that the cost increases due to an increase in the number of processes by repeating the above removal step.

  The present invention was made to solve such a conventional problem, and while reducing the retention of the coating liquid in the coating liquid pan, it eliminates the sedimentation and aggregation of fine particles and pigments contained in the coating liquid, It is another object of the present invention to provide a coating apparatus that can disperse a resin, a solvent, and the like contained in a coating liquid, and facilitates cleaning of a coating liquid pan, a transfer roll, and a coating liquid circulation system.

In order to achieve the above object, the invention described in claim 1 is an apparatus for applying a coating liquid to a continuously running belt-like substrate,
A coating liquid pan for storing the coating liquid;
A transfer roll for transferring the coating liquid to a substrate;
An ultrasonic oscillator that generates an electrical vibration signal;
An ultrasonic vibrator installed on the outer wall of the side wall and the bottom wall of the coating pan, and converting an electric vibration signal into mechanical vibration;
A coating liquid supply pipe provided on the bottom surface of the coating liquid pan;
A coating liquid discharge pipe provided on the side surface of the liquid pan;
A coating liquid circulation unit that circulates the coating liquid by discharging the coating liquid in the coating liquid pan from the coating liquid discharge pipe to the outside of the coating liquid pan and supplying the coating liquid from the coating liquid supply pipe; It is the coating device characterized by these.

  A second aspect of the present invention is the coating apparatus according to the first aspect, wherein the ultrasonic oscillator comprises an oscillator for low-frequency ultrasonic waves and high-frequency ultrasonic waves.

  A third aspect of the present invention is the coating apparatus according to the first aspect, wherein the ultrasonic transducer is installed over the entire length of the transfer roll in the axial direction or partially.

  According to a fourth aspect of the present invention, the coating liquid circulation unit sucks the coating liquid stored in the coating liquid tank and stores the coating liquid discharged through the coating liquid discharge pipe, and the coating liquid. The coating apparatus according to claim 1, further comprising a liquid feeding pump that feeds liquid from a supply pipe to the liquid pan.

  A fifth aspect of the present invention is the coating apparatus according to the first or fourth aspect, wherein a filter is provided in a flow path connecting the liquid feeding pump and the coating liquid supply pipe.

  A sixth aspect of the present invention is a method for forming a coating film, comprising: applying a coating liquid onto a continuously running substrate using the coating apparatus according to any one of the first to fifth aspects; It is.

  The invention of claim 7 is the coating film forming method according to claim 6, wherein the coating liquid is a coating liquid in which particles are dispersed.

  In the coating apparatus of the present invention, by applying ultrasonic waves to the cleaning liquid with an ultrasonic oscillator that oscillates low-frequency ultrasonic waves and high-frequency ultrasonic waves, dirt on the inner wall of the liquid pan, sediment on the bottom of the liquid pan, and dirt on the transfer roll Is dispersed to make it easy to drop, and the cleaning liquid in the coating liquid pan is circulated by the coating liquid circulation section. In addition, by applying ultrasonic waves to the coating liquid with an ultrasonic oscillator, it is possible to disperse fine particles and pigments that tend to settle or aggregate. Therefore, according to the present invention, in addition to washing the liquid pan and the transfer roll, it is possible to reduce the retention of the coating liquid in the pan, and to eliminate sedimentation and aggregation of particles and pigments contained in the coating liquid. In addition, a resin or a solvent contained in the coating liquid can also be dispersed.

It is a schematic plan view which shows one Embodiment of the coating device which concerns on this invention. It is a schematic sectional drawing in alignment with the AA of FIG. It is a schematic sectional drawing in alignment with the BB line of FIG. It is a bottom view of FIG. It is the schematic which shows the form of one Example of the manufacturing apparatus of the coating material provided with the coating device of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view showing an example when the coating apparatus according to the present invention is applied to a gravure coater, FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. 1, and FIG. FIG. 4 is a bottom view of FIG. 1, illustrating a schematic cross section along line B. The coating apparatus shown in this embodiment includes a coating liquid pan (ink pan) 1 for storing a coating liquid, a transfer roll 5 for transferring the coating liquid to a substrate, and an electric vibration signal as shown in FIGS. And an ultrasonic transducer (not shown), ultrasonic transducers 3a, 3b, and 3c, a coating liquid supply pipe 12, a coating liquid discharge pipe 13, and a coating liquid circulation unit. 6 is an impression roll.

  The coating liquid pan 1 stores the coating liquid 4 containing particles and pigments that easily settle or aggregate, and is longer than the axial length of the gravure roll 5 as shown in FIGS. 1 to 3. It has a rectangular tray shape with an open top surface having a width greater than 5 diameters. The tray-shaped coating liquid pan 1 has a bottom wall and a side wall that stands up from the periphery of the bottom wall. As shown in FIGS. 2 and 3, a coating liquid supply pipe 12 is provided at the center in the width direction of the bottom wall of the coating liquid pan 1 over the entire length in the longitudinal direction of the coating liquid pan 1. Further, ultrasonic transducers 3a, 3b, and 3c are installed over the entire length in the longitudinal direction or partially on the outer walls of the side wall and the bottom wall. As shown in FIG. 3, the bottom wall of the liquid pan 1 is configured with an inclined surface that is inclined obliquely downward toward the coating liquid supply pipe 12. As shown in FIGS. 1 to 3, a plurality of coating liquid discharge pipes 13 are provided on the side wall of the liquid pan 1.

  As shown in FIG. 4, the ultrasonic transducer is arranged so as to extend over the entire length (3a) in the longitudinal direction of the side walls (3b, 3c) and the bottom wall of the coating liquid pan 1, and is subjected to ultrasonic vibration. By applying low-frequency and high-frequency ultrasonic vibrations to the coating liquid 4 by a child, the coating liquid 4 containing fine particles and pigments that easily settle or aggregate is dispersed to disperse particles and pigments, as well as resins and solvents. It is like that. In addition, dirt and sediment in the coating liquid pan 1 and dirt on the gravure roll 5 can be removed.

  As shown in FIGS. 1 to 3, the gravure roll 5 faces the coating liquid pan 1 from the upper surface of the coating liquid pan 1, and a part of the outer peripheral surface of the gravure roll 5 is coated in the coating liquid pan 1. It is disposed along the longitudinal direction of the coating liquid pan 1 so as to be immersed in the liquid 4 and is rotatably supported by a support bracket (not shown). In addition, an impression roll 6 that presses the belt-like base material 8 against the outer peripheral surface of the gravure roll 5 is disposed in parallel with the gravure roll 5 and is rotatably supported by a support bracket (not shown). Yes. In FIGS. 1 and 2, reference numeral 7 denotes a doctor that scrapes off excess coating liquid 4 attached to the outer peripheral surface of the gravure roll 5.

  The coating liquid circulation unit is for circulating the coating liquid 4 in the coating liquid pan 1 through the plurality of coating liquid supply pipes 12 and the coating liquid discharge pipes 13, and includes a plurality of coating liquid supply ports 12 and the coating liquid discharge ports 13. Between. As shown in FIG. 1, the coating liquid circulation unit includes a coating liquid tank 9 having a plurality of coating liquid supply ports 12 connected to the liquid pan 1 and receiving the coating liquid 4 discharged from the coating liquid pan 1, and a coating liquid A liquid feeding pump 10 that sucks the coating liquid 4 received in the tank 9 and supplies it from the coating liquid supply pipe 12 to the liquid pan 1, and a flow connecting the discharge side of the liquid feeding pump 10 and the coating liquid supply pipe 12. It is comprised from the filter 11 provided in the path.

  In the coating apparatus configured as described above, an extra coating other than the coating liquid 4 filled in the cell engraved on the surface of the gravure roll 5 in the coating liquid pan 1 by the reverse gravure method as shown in FIG. The coating liquid is scraped off by a doctor 7, and is transferred from the coating liquid circulation section through the coating liquid supply pipe 12 in a coating system in which the gravure roll 5 and the impression roll 6 are rotated in the direction of the arrow shown in FIG. The applied coating liquid 4 fills the coating liquid pan 1. As shown in FIG. 3, the coating liquid 4 supplied to the coating liquid pan 1 from the coating liquid supply pipe 12 fills the inside of the coating liquid pan 1, and a part of the coating liquid 4 is scraped up by the gravure roll 5. The excess coating liquid 4 is scraped off and transferred to the substrate 8 by the impression roll 6. The excess coating liquid 4 in the coating liquid pan 1 is discharged from a plurality of coating liquid discharge pipes 13 to the coating liquid tank 9 and stored.

  In the present embodiment, a diaphragm pump without a sliding portion can be used as the liquid feeding pump 9. After the coating liquid 4 supplied by the liquid feeding pump 9 is filtered by the filter 11, the liquid level in the coating liquid pan 1 gradually rises by continuing to be supplied from the coating liquid supply pipe 12 to the coating liquid pan 1. Further, since the coating liquid 4 is continuously vibrated by the ultrasonic vibrator, the coating liquid 4 containing particles, resin and solvent fills the coating liquid pan 1 while being stirred. A part of the uniformly dispersed coating liquid 4 is transferred to the base material 8 by the gravure roll 5, doctor 7 and impression roll 6. The coating liquid 4 discharged from the coating liquid discharge pipe 13 is returned to the coating liquid tank 9 through the pipe, and is supplied again into the coating liquid pan 1 by the liquid feeding pump 10.

  The ultrasonic oscillator 2 in the present embodiment is a low-frequency ultrasonic oscillator of, for example, 15 to 50 kHz for removing the resin component, and a high frequency of, for example, 0.3 to 1 MHz for removing micron-order fine particles and pigments. An ultrasonic oscillator is provided, and an ultrasonic oscillator having a frequency suitable for the characteristics of the coating liquid may be used. In addition, depending on the properties of the coating liquid 4 such as the coating liquid 4 having a high viscosity or thixotropy when the amount applied to the substrate 8 is large, the coating liquid 4 does not need to be discharged or is difficult to discharge. In No. 4, the transferred amount may be supplied without using the coating liquid discharge pipe 13. Further, the coating method is not limited to the reverse gravure method, but can be applied to various roll applicators such as a roll coater and a micro gravure capable of storing the coating liquid 4 like the coating liquid pan 1.

The ultrasonic transducers 3a, 3b, 3c used in the present embodiment are roughly divided into single crystals (quartz, lithium niobate, etc.), magnetism (barium titanate, PZT, etc.), polymer materials (polyvinylidene fluoride). The ultrasonic vibrator used here is a piezoelectric vibrator type, and types of piezoelectric materials include piezoelectric ceramics (BaTiO ₃ , PZT, PbTiO ₃ ), piezoelectric thin films (ZnO), and piezoelectric polymers. Use a film or the like. In addition, depending on the characteristics of the material, it is not always necessary to vibrate, and it does not affect the applied surface when the applied surface changes. You may vibrate only at times.

  According to the coating apparatus shown in this embodiment, the ultrasonic vibrators 3a, 3b, 3c for dispersing fine particles and pigments contained in the coating liquid 4 in the coating liquid 1 to prevent sedimentation and aggregation. The coating liquid 4 supplied from the coating liquid supply port 12 fills the coating liquid pan 1 and is ultrasonically vibrated by the ultrasonic vibrators 3a, 3b, and 3c provided on the side wall and the bottom wall. The coating liquid 4 that has risen further while being added is discharged through a plurality of coating liquid discharge pipes 13 and returned to the coating liquid tank 9. The inner coating liquid 5 is always in a fluid state, and as a result, the retention of the coating liquid in the coating liquid pan 1 can be reduced, and the sedimentation and aggregation of particles and pigments contained in the coating liquid are eliminated. Resins and solvents contained in the coating liquid can also be dispersed.

  Further, when the gravure roll 5 and the coating liquid pan 1, the coating liquid supply pipe 12, the coating liquid tank 9, the liquid feeding pump 10, and the coating liquid discharge pipe 13 are cleaned, the cleaning liquid supplied from the coating liquid supply pipe 12 is the coating liquid. Fill in bread 1. Then, after the coating liquid pan 1 is filled with a certain amount of the cleaning liquid, the ultrasonic vibrators 3a, 3b, and 3c give the cleaning liquid two types of ultrasonic vibrations of low frequency and high frequency, thereby generating cavitation in the cleaning liquid. The gravure roll 5 is washed, and at the same time, the inside of the coating liquid pan 1 is washed. Again, the cleaning liquid is supplied from the coating liquid supply pipe 4 to the coating liquid pan 1 and circulated, so that the gravure roll 5, the coating liquid pan 1, and the coating liquid circulating liquid can be cleaned.

  In addition, in the coating device of this invention, it is not limited to the gravure coater using the gravure roll shown in FIGS. 1-4, What is necessary is just the coating device which uses a roll. For example, the present invention can be applied to a coating apparatus using a roll such as a micro gravure coater or a bar coater.

  By using the coating apparatus of the present invention as described above, it is possible to apply a coating liquid to a continuously running web-like substrate, and to produce a coated product having a coating film on the substrate. In particular, it can be used when a coating film is formed using a coating liquid containing particles or pigments to produce a coated product. Examples of the particles include light diffusing particles and AG particles.

  Examples of the coated material include an AG film in which a coating liquid containing a binder matrix-forming material, particles, and a solvent is formed on a substrate, and an AG layer having irregularities on the surface is formed by the particles. The AG film is provided on the outermost surface on the viewer side of a display such as a liquid crystal display device, and prevents reflection of external light incident on the display surface. When an AG film is produced by forming an AG layer having surface irregularities on a web-like substrate using a coating liquid containing particles, the amount per unit volume of particles in the AG layer and the amount of particles The optical performance such as haze and gloss varies greatly depending on the dispersion state. By using the coating apparatus of the present invention, when the AG layer is formed on the continuously running substrate, the change in the coating solution over time can be suppressed by the sedimentation and aggregation of particles contained in the coating solution, and the stability AG film can be manufactured.

  Hereinafter, the case where an AG film is manufactured as a coated material will be described. When forming the AG film, it is formed by, for example, applying a coating liquid containing a binder matrix forming material and particles on a web substrate and irradiating with UV. The AG layer has a structure in which particles are dispersed in a binder matrix, and irregularities are formed on the surface by the particles.

  FIG. 5 is a schematic view showing an embodiment of an apparatus for producing a coated product (AG film) provided with the coating apparatus of the present invention. The manufacturing apparatus shown in FIG. 5 includes a base material unwinding portion 14 for continuously running a base material on which a web-like base material 8 is wound in a roll shape, and a plurality of base materials 8 that support the base material 8 so as to be continuously run. A coating apparatus comprising a backup roll 15, a coating liquid pan 1, a gravure roll 5, an impression roll 6, a drying apparatus 16 for drying the coating liquid 4 applied to the substrate 8, a curing apparatus 17 for curing the coating film after drying, And the winding-up part 18 which winds up the base material 8 after drying and hardening a coating liquid in roll shape is provided. The substrate 8 that is continuously run passes through the coating device, and then passes through the drying device 16 and the ionizing radiation irradiation device 17, whereby a coated material (AG film) is manufactured.

  Moreover, the coating material by the coating device of this invention can mention the antireflection film provided with an antireflection layer as a functional layer as a coating film. In forming the antireflection layer, it can be formed using a coating liquid containing a binder matrix forming material and low refractive particles. Moreover, in the coating apparatus of this invention, the antistatic film provided with an antistatic layer can be mention | raise | lifted as a coating film. When forming the antistatic layer, it can be formed using a coating liquid containing a binder matrix forming material and conductive particles. In addition, the coated product of the present invention may have a plurality of functional layers such as an AG layer and an antireflection layer, and an antireflection layer and an AG layer as a coating film. The layer should just be formed by the coating method of this invention. Further, a single layer may have a plurality of functions such as an AG layer having antistatic performance.

Next, examples of the present invention will be described.
(Example) 85 parts by weight of an acrylic monomer (pentaerythritol triacrylate) as an ultraviolet curable resin as a binder matrix forming material, 5 parts by weight of Irgacure 184 (manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator, and toluene 100 as a solvent A coating liquid was prepared in which 10 parts by weight of silica particles having an average particle diameter of 5 μm were dispersed while mixing parts by weight. In addition, a triacetyl cellulose (hereinafter referred to as TAC) film having a film thickness of 80 μm was prepared as a web-like substrate to be coated. The coating apparatus shown in FIG. 5 including the coating apparatus shown in FIG. 1 is used to apply the coating liquid onto the continuously running TAC film, and after the coating, the TAC film is passed through a drying apparatus and an ultraviolet irradiation apparatus, thereby the TAC film. An AG layer having a thickness of 5 μm was formed thereon to produce an AG film. At this time, a TAC film having a total length of 1000 m was continuously run to continuously produce an AG film.
(Comparative example)
The same coating liquid as in Example 1 was prepared. The coating apparatus shown in FIG. 4 having the coating apparatus shown in FIG. 1 is used to apply the coating liquid onto the continuously running TAC film, and after the application, the TAC film is passed through a drying furnace and an ultraviolet irradiation device, thereby the TAC film. An AG layer having a thickness of 5 μm was formed thereon to produce an AG film. At this time, a TAC film having a total length of 1000 m was continuously run to continuously produce an AG film.

  About each AG film obtained by the Example and the comparative example, the thing immediately after manufacture start and the thing just before completion | finish of manufacture were extracted. The anti-glare performance of the AG film immediately after the start of manufacture and the AG film immediately before the end of manufacture were confirmed by reflecting the image of the fluorescent lamp on the AG film in a room with a fluorescent lamp. In the example, no difference in antiglare performance was confirmed between the AG film immediately after the start of manufacture and the AG film immediately before the end of manufacture. On the other hand, in the comparative example, a difference in anti-glare performance was confirmed between the AG film immediately after the start of manufacture and the AG film immediately before the end of manufacture, and it is presumed that the state of the coating liquid changed during the manufacture of the AG film. .

  As described above, according to the coating apparatus of the present invention, the retention of the coating liquid in the coating liquid pan is reduced, and the sedimentation and aggregation of fine particles and pigments contained in the coating liquid are eliminated, and further the resin contained in the coating liquid. As a result, the initial composition does not change, and as a result, a coating having stable characteristics can be obtained. It is possible to reduce costs due to an increase in the number of processes by repeating the step of removing substances and aggregates.

DESCRIPTION OF SYMBOLS 1 ... Coating liquid pan 2 ... Ultrasonic oscillator 3a ... Ultrasonic vibrator 3b ... Ultrasonic vibrator 3c ... Ultrasonic vibrator 4 ... Coating liquid 5 ... Gravure roll 6 ... Impression roll 7 ... Doctor 8 ... Base material 9 ... Coating Liquid tank 10 ... Liquid feed pump 11 ... Filter 12 ... Coating liquid supply pipe 13 ... Coating liquid discharge pipe 14 ... Substrate unwinding section 15 ... Backup roll 16 ... Drying device 17 ... Ionizing radiation irradiation apparatus 18 ... Winding section

Claims (7)

An apparatus for applying a coating liquid to a belt-like substrate that is continuously running,
A coating liquid pan for storing the coating liquid;
A transfer roll for transferring the coating liquid to a substrate;
An ultrasonic oscillator that generates an electrical vibration signal;
An ultrasonic vibrator installed on the outer wall of the side wall and the bottom wall of the coating pan, and converting an electric vibration signal into mechanical vibration;
A coating liquid supply pipe provided on the bottom surface of the coating liquid pan;
A coating liquid discharge pipe provided on the side surface of the liquid pan;
A coating liquid circulation unit that circulates the coating liquid by discharging the coating liquid in the coating liquid pan from the coating liquid discharge pipe to the outside of the coating liquid pan and supplying the coating liquid from the coating liquid supply pipe; An applicator characterized by.   The coating apparatus according to claim 1, wherein the ultrasonic oscillator includes an oscillator for low-frequency ultrasonic waves and high-frequency ultrasonic waves.   The coating apparatus according to claim 1, wherein the ultrasonic vibrator is installed over the entire axial length of the transfer roll or partially.   The coating liquid circulation unit sucks the coating liquid stored in the coating liquid tank and stores the coating liquid discharged through the coating liquid discharge pipe, and from the coating liquid supply pipe to the liquid pan. The coating apparatus according to claim 1, further comprising a liquid feeding pump for feeding the liquid.   The coating apparatus according to claim 1 or 4, wherein a filter is provided in a flow path connecting the liquid feeding pump and the coating liquid supply pipe.   A coating film forming method comprising applying a coating liquid onto a continuously running substrate by using the coating apparatus according to claim 1 to form a coating film.   The coating film forming method according to claim 6, wherein the coating liquid is a coating liquid in which particles are dispersed.

Images