JPS5830365A - Coating apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to coating processing of continuous paper webs, and more particularly, to avoiding the formation of large coating puddles and achieving low solids content and low viscosity at high running speeds. The present invention relates to a processing device that can perform coating using the following methods.

In paper manufacturing, it is known to apply starch solutions to continuous paper webs in order to impart appropriate paper strength to the finished paper sheet. During said processing, the paper is coated with starch on both sides so as to properly impregnate the web.

Starch processing equipment has traditionally required the presence of a starch bath or reservoir in the nip between two rolls prior to coating the web. One conventional device has 2
There are several press rolls, and the web passes between two smooth rolls with a receiving nip between the rolls supporting a starch bath. The web passes through the center of the tank, so that
Both sides of the web are simultaneously impregnated with starch. The problem that arises with the above technology is that the paper
If the starch flows at a high speed of more than 2000 feet (57 minutes), a turbulent flow will occur in the starch reservoir, and the coating solution will tend to flow out of the nip, resulting in uneven coating. With two press rolls there is no means to control the turbulent flow in the starch bath (uneven coating would result in breakage of the coot nibs).

Another device that uses a tank is a gated press roll, which includes a series of smooth contact rolls that rotate with respect to each other. A relatively large applicator roll in the center defines a nip through which the continuous sheet web passes. A pair of relatively small metered or gated application rolls guide each large application roll, the gate rolls defining a nip spaced from the application roll supporting the starch bath. A starch coating is conveyed from the tank along rolls and applied to both sides of the web as it passes through the nip between large rolls. The gate press roll has an operating speed of 1200 meters/
(4,000 feet/minute) or higher, but typically a starch with a high viscosity is required to provide starch film strength through the nip of the gate roll. Due to the large amount of solids required for viscosity, starch impregnation in the gate press rolls is minimal. Optimal solids impregnation requires low solids and low viscosity solutions. High starch solids result in high concentrations of starch adhering to the outer surface of the web, resulting in undesirable web qualities such as sheet tack and cohesion. Furthermore, because starch impregnation is limited, the internal bond strength of sheets processed with gated press rolls is generally not improved compared to sheets processed with two press rolls.

The present invention is directed to a coating apparatus that eliminates the need for the formation of a starch bath and is capable of high speed starch impregnating coating processing of webs.

The continuous paper web passes through a nip between two applicator rolls.

The coating device serves to pre-meter a uniform starch coating at each squeeze roll upstream of the nip.

The coating is approximately equal to the maximum amount that can be absorbed by the web at the nip. As a result, starch reservoirs are not formed. The coating equipment for each press roll includes a starch applicator, such as a feed or applicator roll means, for supplying an excess amount of starch onto the press roll surface, and an adjustable doctor for metering the starch coating onto the roll surface. It consists of a blade means.

Each press roll then passes a uniform starch coating from the male means to a nip which receives the paper web. This causes a starch coating to adhere to the web just before the nip of the rolls. The excess amount of starch initially adhering to the surface of the press roll is 10 to 40 times the amount of starch measured on the applicator roll. The coating equipment is capable of passing the web through the applicator nip at high speeds with uniform coating. Additionally, the apparatus of the present invention operates with low solids and low viscosity starches to reliably and effectively impregnate the web.

Although the present invention is described herein for use in starching a single paper web, the apparatus of the present invention has wide application in coating paper webs or coat nibs.

FIG. 1 shows a large starch vat (two press sizing roll apparatus 00 for treating a continuous paper web with one starch) in a manner known in the art.

The tank Ge has two rolls α3. (Supported in a nip between
Web speeds above 1 minute) have been found to be limited. The turbulent flow will cause the starch coating to be jettisoned from the nip, resulting in sheet web breakage. Using a low viscosity starch reduces turbulence, but requires evaporation of large amounts of water during the subsequent web drying process. Additionally, low viscosity amounts of starch on the web cannot be effectively controlled by nip pressure. Also, the amount of coating on the web will increase the speed of the machine. Therefore, the method of controlling the starch coverage on the web is low solids (4
~6%) starch bath solution was used.

In FIG. 2, a conventional gate roll mill for starch processing is shown. The paper web 0 passes between press rolls (2), the valley rolls being coated with starch by each gate roll device.

Both gate roll devices are identical and only the required roll will be discussed. Two adjacent gates or metering rolls (c) support a starch vat (c) in its nip. The outer gate roll (c) rotates at a speed of about 40% of the sheet web speed in order to apply starch to the intermediate gut roll (c) for passing through the metering roll and press roll (a). On the other hand, the intermediate roll (a) rotates at a speed of about 60% of the sheet speed.

The starch coating formed by the press rolls passes through the nip (c) formed between the press rolls. The starch sticks to one side of the paper web. The gate roll pressing device is 4,
Starch processing can be performed at paper web speeds in excess of 1,000 feet/minute. However, only the surface coating is done with the high viscosity starch solutions normally used in gate press rolls. The viscosity is very low.

It is difficult to support the starch tank with gate rolls. Therefore, the starch solution of conventional gate press rolls has a solids content of no more than approximately 10%.

Insufficient starch impregnation results in lower internal bond strength in the sheet produced by the above method than in the sheet produced by two press sizing rolls.

According to the invention, two squeeze rolls are provided,
A continuous paper web H (Figs. 3 and 4) passes between two smooth coating or squeezing rolls 01), which form a nip 6 at the web inscription point. . Each doctor blade device ■, 0υ is adjacent to each roll, and the blade member CI, G3 extends diagonally toward the outer surface of the roll.
9) The blade holding housing (G) is tilted downward to adjustably hold the blade. The doctor blade device ■, (c) uses a straight and diagonally cut blade (c) t091 (Fig. 5), and this blade is used to measure the coating thickness (F) on the roll downstream of the blade. , the rotation can be adjusted by the required angle relative to the coating roll. The blade (g), o9) may be made of metal such as steel. However, the blade should be made of a material such as Teflon, and the Teflon should be
), softer than 6 seconds.

The application roll is preferably made of hard rubber (0 to 50 P&J) or corrugated with hard rubber. Although the blade wears out quickly, its replacement is simple and easy.

The straight blade M (Figs. 3 and 4) is preferably made adjustable by flexible air bladder means (4), the air bladder selectively positioning the doctor blade. Such air tubes loaded with doctor blades are known in the art.

Representative examples of 2.3 are described in US Pat. No. 3,529,315 and US Pat. No. 3,778,861.

Each press roll'at)p (3) is coated with starch solution (6) facing upstream of the coating metering blade.The starch adhering to each press roll is weighed. The coating is approximately 10 to 40 times the amount of starch coating passing through the web introduction nip (c).A solution enclosure or reservoir is therefore formed upstream of the blade tip.

Preferably, the thickness F) of the treated coating on the valley coating roll is set to be slightly less than the maximum amount that can be absorbed by each side of the web. In this way, nip 0
In (2), starch reservoirs are not substantially formed. Since the device of the present invention does not require starch, the roll (31)
, oa between which the web 0η can pass downwardly or downwardly.

In Fig. 3, the starch application means is a coating roll device, which has five types, and the coating roll-10 extends between opposing large-sized press rolls 31) and 3"2), and contains various types of starch. The coating roll is a large roll (pl), which functions to supply and coat starch to the outer surface of Iu@.

On the other hand, as shown in FIG. 4, the supplied starch adheres to each large press roll 0υ, OeJ: by the supply source. The supply source supplies pressurized solution from supply nozzle means (c). The starch solution is pumped through the conduit means into each supply line by a pump (P), such as a variable positive displacement pump. Pump means supply starch solution from respective reservoirs or tank means (5]) containing feed solutions.

Instead of the straight blade device shown in the embodiment of FIGS. 3-5, the film applicator of the present invention, as shown in FIG. A doctor blade device that can be elastically deformed may also be used. The deformable metering blade device is disclosed in commonly filed and abandoned U.S. Patent Application No. 482
, 302 (filed on June 24, 1974),
It is also described in British Patent No. 1,424,150. By way of illustration, the applicator roll 00 mechanism described above serves to coat each press roll 00, although other source means may be used.

The elastically deformable blade device (3) is disposed downstream of the coating roll (3). The device is deformable and includes a blade holder frame (5υ) for supporting a steel doctor blade.

One end of the blade is buried and fixed at the bottom of the machine frame.

The other end of the blade extends outside the machine frame without being restrained.

The frame (5), l is pivotable about a pivot by suitable actuating means, for example as shown by a hydraulic cylinder. The cylinder is a link connecting to the lower end of the frame. It's on pin GO.

The blade is initially arranged in a straight line without deformation, as shown in the machine frame in Figure 6 (the rightmost imaginary line of the five swords).The outward extension of the link (a) is Rotate the machine frame!〃 to the operating position.The free end of the blade is stationary at point (P), and the blade Q5 is curved into a concave arc or curve by the intermediate engagement part cut into the blade along with the apex Q5 barrel. (11) As shown in FIG. 7, an example of the axis of the blade 6 and the holder frame, the top surface 6 of the blade is substantially tangential to the pressure roll 02) at point (p). It is desirable to set it so that it faces 1-
stomach. With the above settings, the metered coating changes as the deformation load on the blade changes, as shown by the movement of the blade between the imaginary line position and the solid line position in Figures 6 and 7. However, uniformity and accuracy are guaranteed.

The smoothness and uniformity of the coating film (F) is maintained by maintaining a flat blade top surface G in tangential engagement with one squeeze roll. The thickness of the coating film (F) is controlled by adjusting the load on the leading blade or the degree of deformation of the blade by rotating the holder frame (51).

Appropriate starch impregnation is required to improve sheet internal strength. The main factors controlling starch impregnation are
These are the solid amount and viscosity of starch.

Both low solids content and low viscosity are necessary for optimal starch impregnation of the web. In conventional distillers, starch is characterized by low viscosity and low solids content (ie, about 6 parts). (12) The precision metering device of the present invention provides low solids content (100 m/min) when processing sheet webs traveling at speeds in the range of approximately 300-1500 m7 (100-5000 feet/min). %, preferably about 5%), low viscosity starches can be used.

Although the embodiments disclosed above have shown apparatus suitable for simultaneously processing both sides of the web, it is also within the contemplation of the present invention to process corrugated surfaces.

Although various minor modifications may be envisioned by those skilled in the art, it is intended that all such modifications as may reasonably be made within the skill of the art be practiced within the scope of the invention. I want to be understood.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a known two roll press apparatus in which a paper web passes through a starch tank; FIG. FIG. 3 is a schematic side view of a known Gutrol press apparatus in which the starch passes as a coating onto two press rolls; FIG. 4 is a schematic side view of the device; FIG. The figures are Figures 3 and 4.
FIG. 6 is a partially schematic side view showing the arrangement of the blade tops together with the pressure rolls of the reservoir used in the illustrated embodiment; FIG. FIG. 7 is a partially schematic side view of the embodiment showing the arrangement of each squeeze roll and a desired blade top for use in the embodiment of FIG. 6. 10... Pressed glue roll device, 11... Paper web, 12
...Starch tank, 13.14.. Roll, 20.. Gate roll pressing device, 21.22.. Pressing roll, 23.
24...Gate (weighing) 0-le, 25...Starch tank,
26...Nip, 31, 32...-Press roll, 33...
27', 34.35...Doctor blade, 3'6, 37.
・Blade holding housing, 38° 39・・Blade, 40.41・
-Air bag, 42.43... Starch application means, 44.
45... Application roll, 46. 47... Tank, 48. 49... Nozzle, 50... Doctor blade device, 51... Machine frame, 52
...Doctor blade, 53...Machine frame, 54.9 axis, 55...
Cylinder, 56・O link pin, 570-top surface, 58・
・Top of the platform.

Claims (1)

[Claims] (1) a two-roll squeeze defined by two rolls into which the web is received; a nip between said rolls into which the web is introduced to pass through said two-roll squeeze; starch application means for at least one roll for applying a starch solution to the roll surface;
and a small amount (cooperating with at least one of the rolls) to meter starch onto the face of each roll in a generally uniform starch coating through the two rolls so as to impregnate the web; and doctor blade means in which droplet formation is eliminated in said nip. Apparatus for applying starch in solution to a paper sheet web VC for impregnating the web.