JPS6034769A - Process for coating on travelling web - Google Patents

Abstract

PURPOSE:To perform coating on travelling web with remarkably thin thickness of coated layer and with high uniformity, and with controlled thickness by allowing an end of a clothlike member to contact with travelling web and supplying liquid having 0.01-10mu particle size from a jet nozzle to the clothlike member. CONSTITUTION:Web 12 is travelled and liquid drops having 0.01-10mu particle size are supplied to a clothlike member 10 from a jet nozzle N. The liquid drops arrived at the clothlike member 10 are impregnated into the clothlike member 10, flow down to the lower end of the clothlike member 10 and are transferred to the surface of the web 12. Ink jet printer of printing device of computor, etc. can be used for the jet nozzle. The ink in the ink chamber 3 is pressurized by a pump 7, and is dispersed in the form of drops from the nozzle 4 by inputting a high-frequency driving signal to an electrostrictive oscillator 6. In this state, the liquid drops are deflected by a charge electrode 8 and a deflecting electrode 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of coating a running web.

Methods using a doctor knife coater, various roll coaters, etc. are known as methods of applying liquid to a running long flexible web, but with these methods, it is difficult to apply the liquid uniformly and thinly with high precision. be. Furthermore, these methods have the disadvantage that they cannot be applied when the web is made of a material that is easily deformed or damaged.

Incidentally, in recent years, inkjet printers have been developed as printing devices for computers and the like. This gives vibration to the electrostrictive vibrator built into the printer head,
The structure is such that ink particles are ejected from a nozzle, charged by a charging electrode, and the direction of flight of the charged ink particles is controlled by a deflection electrode to reach the base paper. Since droplets of fine particles such as lOμ are applied to the printing surface, the thickness of ink adhesion can be significantly reduced.

The object of the present invention is to provide a method by which a liquid can be thinly and uniformly applied to a running web by using such a jet nozzle.

- That is, in the coating method for a running web according to the present invention, one end of a shaped member is brought into contact with a running web, and a liquid is applied to the shaped member from a jet nozzle with a particle size of 0.01 to 10 μm.
This method is characterized by supplying the liquid as droplets.

The present invention will be explained below with reference to the drawings.

In the present invention, an inkjet printer developed as a printing device for computers and the like can be used as the jet nozzle, and FIG. 1 shows an example thereof.

In FIG. 1, 1 is a casing, 2 is a head body attached to the casing, 3 is an ink chamber, 4 is a nozzle, 5 is a diaphragm, 6 is an electrostrictive vibrator, 7 is a pump, 8 is a charging electrode, 9
is a deflection electrode.

When the ink in the ink chamber 3 is pressurized by the pump 7 and a high-frequency drive signal is applied to the electrostrictive vibrator 6, ink drops are ejected from the nozzle 4, and these droplets are applied to the charging electrode 8 and the deflection electrode 9. be biased by

In the present invention, the droplet deflection required in the present invention is a monotonous one in which the width of the web is reciprocated horizontally and linearly, and the head itself can also be reciprocated horizontally and linearly in place of the electric field deflection described above. Therefore, charging electrodes and deflection electrodes can be omitted.

The hole diameter of the nozzle is 40 to 200 microns, and the droplet diameter in this case is usually 0.01 to 10 microns.

The amount of liquid sprayed per nozzle is 0.5 to 5 ml per minute, but it can be adjusted to a smaller amount by electrical control means such as pulsing the injection time, and by using multiple nozzles. The amount of application can be increased.

FIG. 2 shows a coating device used in the present invention.

In FIG. 2, reference numeral 10 denotes a shape member, 11 a means for suspending the shape member, and 12 a long flexible web, which runs in contact with the lower end of the shape member 10. N is the jet nozzle described above.

To carry out the present invention, the web 12 is run, and the jet nozzle N applies the liquid to the shaped member 10 with a particle diameter of 0.01.
It may be supplied in the form of droplets of ~10μ. The droplets that have reached the shaped member 10 are impregnated into the shaped member 10, flow down, reach the lower end of the shaped member 1o, and transfer to the surface of the web 12. Since the droplets are evened out in the shaped member 10, there is no density of the liquid even if the distribution of the liquid on the web surface is evaluated in units of droplet diameter, and therefore uniformity of application can be achieved with high precision. .

In the present invention, the shaped member acts to spread the attached droplets and uniformly supply the liquid to the web. Therefore, in order to promote the above-mentioned diffusion, it is desirable to use a self-priming material that exhibits capillary action.

Examples of the material used in the present invention include gauze, synthetic fiber cloth, tricot woven cloth, etc., and materials thereof include organic fibers such as polyester fibers and acrylic fibers, natural fibers such as cotton, silk, and linen, Examples include glass fiber.

In addition, as a material member, the apparent density is 0.6 or less (normal lower limit is 0.25, preferably 0.3)2
00% or more, water absorption (according to RXSP No. 51A1) is 50 mm or more in 10 minutes, water absorption rate is within 10 seconds, thickness is 200 μ or more (normal upper limit is 1 mm), preferably about 300 μ to 500 μ. used.

The above water absorption rate is as follows: prepare 5 samples of 10QWXIOI and pour pure water at a temperature of 27°C ± 2°C from a buret for 20
Drop 5 drops of Q, l ml each from a height of The value was calculated by repeating this five times for each sample and taking the average value.

Further, the shape member is usually rectangular, and this member is formed on the edge that contacts the web, preferably in a direction substantially perpendicular to the longitudinal direction of the web and in a substantially linear manner.

Although a mechanism for adjusting the contact length t of the shaped member with the web is not shown in FIG. 2, this can be easily done by using a known device such as a pick-up unit or a stretcher unit. It can be done.

Conditions to be kept in mind for the liquid applied according to the present invention are:
It must not produce fine particles or precipitates that would clog the jet nozzle, and it must flow down uniformly within or on the surface of the material.

The viscosity is usually 0.5 to 20 centipoise, preferably 1 to 10 centipoise. In addition, it is desirable to use a liquid that is difficult to volatilize even if it becomes droplets, and therefore a liquid that is nonvolatile at room temperature (for example, a liquid with a vapor pressure of 1 mmHg to 150
It is preferable to use a solution or a solution.

Specifically, monomers, oligomers, polymers alone or solutions thereof, solutions of inorganic compounds, acids, alkalis, salts, etc. can be mentioned.

Examples of the solvent constituting the solution include water, alcohol, hydrocarbon, halogenated hydrocarbon, ketone, and ester.

Moreover, various emulsions and suspensions can also be used as the coating liquid.

The running speed of the web is usually 0.1~lom/min, and the amount of liquid jetted from the jet nozzle is usually 0.5~lom/min.
5+nl, so if the web width is 1 mm and the web speed is 1 m/min, the coating thickness of the liquid can be 0.5 to 5 μm.

The example member was a polyester tricot woven fabric with a water absorption rate of 60 mm and a water absorption rate of 140%, the liquid was latex with a viscosity of 3 centipoise, and the jet nozzle device had a spray amount of 1.
Piezoelectric element type jet nozzle (driving signal:
130KHz) were used. Then, a polyester film with a width of 250 mm was brought into contact with the shaped member with a contact length lQim, and the jet nozzle was moved for 30 m in the width direction of the film.
It was moved back and forth at a speed of times/minute. After the coating film was dried, the thickness of the coating film was measured, and the average thickness was 1.5 μm, and the thickness variation was within ±0.1 μm.

As described above, according to the present invention, since the liquid is supplied to the self-priming member in the form of fine particles with a particle size of 0.01 to 10 μm, the amount of liquid supplied per unit length of the web can be reduced. can be applied in a small amount and the coating thickness can be reduced. Moreover, since the liquid droplets are sufficiently leveled while the liquid flows down the shaped member, the coating thickness can be made uniform. Therefore, according to the present invention, it is possible to apply the liquid extremely thinly and uniformly to the running web. Further, since the jet nozzle jet amount and droplet diameter can be adjusted by human power and input frequency to the electrostrictive vibrator, and the response speed in coating adjustment is fast, coating film thickness can be controlled with high precision.

Therefore, the present invention is useful, for example, when coating a backside treatment agent on the backside of an adhesive tape support.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a jet nozzle used in the present invention, and FIG. 2 is an explanatory diagram showing a coating device used in the present invention. N is a jet nozzle, lo is a shaped member, and 12 is a web.

Claims (2)

[Claims] (1) Bringing one end of the shaped member into contact with the running web,
Liquid is applied to the shaped member from a jet nozzle with a particle size of 0.01.
A method for coating a running web, characterized in that it is supplied as droplets of ~lOμ. (2) The method for coating a traveling web according to claim 1, wherein the shaped member is self-priming.