US2221780A - Vat dyeing and apparatus therefor - Google Patents

Description

N v-19.1940- J. E. CONRAD Em 2221x180 VAT DYEING AND APPARATUS THEREFOR Filed March 10, 1939 2 Sheets-Sheet 1 FIG. I

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JOHN E. CONRAD. WILLIAM ROLLIN KEEN.

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' Novl 19, 1940. 1 CONRAD ETAL 7 2,221,780

VAT DYEING AND APPARATUS THEREFOR .Filed March 10, 19 39 2 Sheets-Sheet 2 FIG. I[[

INVENTORS.

JOHN E. CONRAD. WILLIAM I2OLLIN KEEN.

Patented Nov. 19, 1940 2,221,780 I VAT DYEING AND APPARATUS THEREFOR John E; Conrad, Bala-Cynwyd, and William Rollin Keen, Drexel Hill, Pa., assignors to Collins & Aikman Corporation, Philadelphia, Pa.,"a corporation of Delaware Application March 10, 1939, Serial No. 261,024

12 Claims.

This invention relates to a process and apparatus for dyeing textile fibers in fabricated forms or otherwise, with vat colors or dyes. As will be understood, vat dyes are derivatives of anthraquinone, indigo, thio-indigo and carbazole.

More specifically, this invention is directed to a process of vat dyeing in which variations in shade are substantially eliminated in a givenrun .of cloth, regardless of the length of material run.

Vat colors are highly water insoluble and when used to dye textile fiber, such as cotton, wool, mohair, synthetic .fibers and the like, must be rendered water soluble. The usual method employed consists of reducing the vat dye with sodium hydrosulfite so that the vat colors become soluble in an aqueous alkaline liquid. Vat dyes, in the reduced state, are usually unstable. This is particularly true of anthraquinone vat colors and more specially of most anthraquinone blues. The dye liquor, after reduction and when ready for application to textile fibers, consists of dyestufi, reducing agent and an alkali. This dye liquor is generally termed a vat. Various other assistants, such as penetrants, may be added if desired.

Many of these vat colors, when maintained in the reduced form for a period of time, undergo a progressive weakening in strength and/or a progressive shade change. Several features, including solubility of the reduced dyestufi, temperature of the liquor, amount of alkali present,

structure of the dyestuif, salting out of the color, and complete destruction of the dye through over-reduction, may be responsible, either singly or in combination, for this weakening or shade change. A simple test will serve to illustrate this fact.

Prepare a gallon of dye liquor of oz. of Du Ponts Ponsol Blue BCL, 1 oz. of sodium hydroxide, 1 oz. of sodium hydrosulfite and suflicient water to bring the composition to one gallon, by dissolving the caustic (sodium hydroxide) in the water, stirring in the dye, straining and bringing the temperature to 140 F., and then gently sprinkling in the reducing agent, sodium hydrosulfite. Allow to stand for 15 minutes and remove one quart. cotton skein at 130 F. and dye in the well known manner for minutes. Remove the skein, rinse and develop in any well known suitable manner. After the stock has stood one hour, remove another quart of dye and treat a second cotton skein in this quart as before. Repeat at the end of two hours, and at four hours. Skein #1 will be a good bright blue. Skein #2 will be Introduce into this quart a I weaker, duller and redder than Skein #1. Skein #3 will be still weaker, duller and redder, and Skein #4 will not be dyed, which indicates that the dye has practically been destroyed after standing for four-hours in the reduced state.

Similar color changes will take place, but not necessarily to such a pronounced degree, with Du Ponts Ponsol Blues BFS, CLX, GD (Colour Index 1113), BCS (Colour Index 1114), Ponsol Brown AR (Colour Index 1151) Ponsol'Brilliant 10 particularly l5 variations in shade and reduction in strength in 20 a dye run by providing a manner of preparing the dye liquor during a controlled and definite length of time immediately prior to and concurrently with the dyeing operation. We may accomplish this result by adding the hydrosulfite or other reducing agent in a dry state as the dye flows to the pad box, or we may introduce the hydrosulfite in an aqueous solution with or without a small amount of caustic, in a similar manner. of dye wasted is materially reduced and the time the dye is in the leuco state is substantially constant throughout a given run of the material.

An object of this invention is to provide an ap- According to our improvements, the amount paratus and method for dyeing, in which varias5 tions in shade are substantially eliminated.

A further object of this invention is to provide an apparatus and a method for dyeing with vat colors, in which each unit volume of dye is in the reduced state substantially the same length of time. v

A further object of this invention f'is to provide a method and apparatus for dye g; vat colors, in which the reducing agent is intr, duced by proportional feed apparatus as the'dye is flowing to the bath.

A further object of this inventiton is to provide a method and apparatus of isolating a quantity of dyestufi reducing agent and an alkali within the apparatus immediately prior to the dye run and of starting the dye run after a predetermined time.

Further objects and advantages will be manifest in the following description and accompanying drawings, in which:

Figure I is a somewhat diagrammatic view of an apparatus in which the reducing agent is added in the dry state to the stock.

Figure II is a detailed view of a modification embodying provision for the introduction of reducing agent in the form of an aqueous solution.

Figure III is a modification, similar to Figure I, characterized in that the mixing chamber is exposed to atmosphere.

Referring, for purposes of illustrating our invention, to the drawings in which like parts in. the modifications are indicated with base and prime reference numerals. Figure I discloses a supply reservoir I0 into which the dye, dispersed in water, may be strained. A convenient supply will be 350 gallons in the supply reservoir prior to the reduction of any portion of the dye. Reservoir i0 is equipped with a high-speed motor agitator II which is driven from any convenient source of power. The flow of stock will be through feed pipe I 2, control valve l3, feed pipe l6, valve I I, mixing coil l9, feed pipe 22, control valve 23 to pad box 28. The mixing coil I9 is approximately 3 inches in diameter and has a capacity of 15 gallons. Mixing coil I9 is positioned within a container 20 which contains water 2| for maintaining the temperature of the liquor in the coil at 130 F. During dyeing, the supply reservoir l0, mixing coil is and the liquor 21 in the pad box 28, are maintained at 130 F. by known heating units (not shown).

Our process, as illustrated in Figure I, is carried out as follows:

When the reservoir 'has a supply and the valves l3, l1 and 23 are closed, valve I3 is opened to fill coil IS with stock maintained at 130 F. in the reservoir I0. A typical stock mixture is:

Duponts Ponsol Blue BFS gms 500 Duponts Ponsol Brown VRS gms 1500 Duponts Ponsol Flavone GCS gms 200 Sodium 'Hydroxide lbs 27 Water (suflicient to bring total to) gals 350 As the coil I9 is being filled, proportional feeder. ll slowly adds 20 oz. of dry sodium hydrosulfite concentrate to the system vented at [5. The

temperature of the water 2| around the coil l9 is raised to maintain the temperature inside the coil l9 at 130 F. as measured by thermometer l8.

After 10 minutes has elapsed from the time valve I3 was opened, valve 23 is opened and the flow through the system is regulated at 1 gallons per minute from the supply reservoil to the pad box 28. Proportional feeder l4 concurrently delivers l oz. of dry reducing agent per minute. Cloth 3 I, in the form of a web, weighing pound per lineal yard, passes through the pad box 28, guided by rollers 24, 25 and 26 and carries moisture (based on dry weight) as it leaves the nip rolls 29 and 30. A flow of 1 gallons per minute through the system will keep the liquor level in the pad box 28 constant .for a cloth speed of 25 lineal yards per minute. Under these conditions, each unit volume of color will be in contact with the reducing agent for approximately ten minutes prior to the time it enters the pad box, and any shade change of the dye due to its contact with the reducing agent will be constant. Ten minutes contact of the stoclggd reducing agent will result in substantially co lete reduction. The proportional rage of flow of the stock and reducing agent is of course maintained constant throughout a dye run.

The pad box may be of any desired construction, but in general it should be made as small as possible with a minimum of exposure of the bath to atmosphere. The time of immersion-will depend on the type of fabric being dyed.

The proportional feeder I4 is of any approved construction and, except for a pin hole vent IS in the funnel shaped portion IS, the system at the point of introduction of the hydrosulfite is closed to atmosphere.

Figure II illustrates a modification in which the hydrosulfite 42, with or without a small amount of sodium hydroxide in aqueous solution, is proportionately added from tank 43 to the system at l5" through feed line 40 by gear pump 4|. It is usually desirable to add a small amount of sodium hydroxide for purposes of stabilization.

Figure III illustrates a modification which differs from Figure I in that the reducing agent is added directly to a mixing chamber exposed to atmosphere. In this case, the feed line i2 may enter through the bottom of container 50 and the stock and reducing agent 5| will be reduced as it passes down around baille plates 52 into the feed line 22'.

It will thus be seen that the above described embodiments of our invention disclose processes and apparatus in which each unit volume of dyestuif will remain in the mixing chamber a substantially definite length of time and that shade change during a dye run willbe eliminated.

Having described our invention, we claim:

1. In a process of dyeing with vat colors, the steps which comprise preparing a liquor supply containing a suspension of unreduced dyestuff, drawing ofl a portion of said liquor and suspended dyestufi into a system connecting the prepared liquor and a dye bath, isolating said portion and reducing it, establishing a regulated flow of the liquor from the prepared liquor supply to the dye bath through the system and continuously and proportionately introducing additional reducing agent into the system as the liquor flows through the system to the dye bath.

2. In a process in accordance with claim 1 in which the time required to pass through the system is substantially equal to the time the drawnofi portion is isolated.

3. In a process of dyeing with vat colors, the steps which include preparing a liquor supply containing a suspension of unreduced dyestufi, establishing a regulated fiow of the liquor from the liquor supply through a system connecting the liquor supply to a dye bath, and concurrently with the flow introducing proportionate amounts of reducing agent to the connecting system as the liquor flows to the dye bath, whereby the dye is substantially in the reduced state when it reaches the dye bath.

4. In a process in accordance with claim 3 in which the time of flow of a given unit of liquor to the dye bath, from its point of contact with the reducing agent, is substantially equal to the time required to reduce the dyestufi.

5. In a process in accordance with claim 3, characterized in that there is no interruption of fiowfrom the supply to the dyebath.

6. In an apparatus for dyeing with vat colors, a supply tank,. a dye bath, an interconnecting system from the supply tank to the dye bath comprising an in-take for a reducing agent, said system having a capacity between the intake and the dye bath sufficient to hold an amount of dyestufi necessary to dye a length of fabric run during the time it takes to substantially reduce the dyestuff within the system.

'7. In a dyeing apparatus for dyeing with vat dye, a stock reservoir, a mixing chamber, a dye bath, a feed line from said reservoir leading to the mixing chamber, an inlet in the feed line between the reservoir and the mixing chamber and means for proportionately adding a reducing agent through the inlet as the stock moves to the mixing chamber in its passage to the dye bath. I

8. In an apparatus in accordance with .claim '7, characterized in that the mixing chamber is a closed coil which blends smoothly with its feed and discharge connections.

9. In a dyeing apparatus in accordance with claim 7, characterized in that the inlet in the feed line and the mixing chamber are open to atmosphere and that the mixing chamber comprises baille plates over which. the dyestuil and reducing agent flows and mingles.

10. In a process of dyeing with vat colors, the steps which include preparing a liquor supply containing a suspension of unreduced dye stuffs, establishing a regulated flow of the liquor from the liquor supply through a system. connecting the liquor supply to a dye bath, and concurrently with the flow continuously introducing proportionate amounts or reducing agent to the liquor in the connecting system as the liquor flows to the dye bath whereby the dye is substantially in .the reduced state when it reaches the dye bath.

11. In a process including dyeing in a dye bath with vat dye, the steps which include preparing a dye liquor stock supply, establishing a flow 01' the dye liquor from the stock supply to the dye bath; introducing a reducing agent between the stock supply and the dye bath and substantially completely reducing the dyestufi during its flow from the stock supply to the dye bath.

'12, In a process including dyeing in a dye bath withvat dye, the steps which include preparing a dye liquor stock supply, establishing a flow of the dye liquor from the stock supply to the dye bath, proportionately feeding and combining dyestufi, caustic and a reducing agent to initlate and substantially complete the reduction of the dyestuil between the stock supply and the dye bath.

JOHN E. CONRAD. WILLIAM ROLLIN KEEN.

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