US3066046A

US3066046A - Web conditioning

Info

Publication number: US3066046A
Application number: US77423A
Authority: US
Inventors: Richard R Walton
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-12-21
Filing date: 1960-12-21
Publication date: 1962-11-27
Anticipated expiration: 1979-11-27

Description

Nbv. 27, 1962 R. R. WALTON WEB CONDITIONING Filed Dec. 21, 1960 United States Patent" Onice .3,06I6 64s I II IWEB coNnrr lorqmc Richard R. wanna, 10 w. Hill Place, Boston, Mass. Filed Dec. 21, 1960, Ser. No. 77,423 Claims. cl. 117''-111) This invention relates to the uniform metering of small amounts of moisture into absorbent webs such as paper and knitted, woven and unwoven textiles, includin'g particularly flattened circularly knitted tubes. Em- Bodirnents of the invention are also useful for imparting much higherliqnid concentrations to webs.

1 Selected textile and paper Webs can be physically altered by creping, compacting and similar physical operations to' obtain desired combinations of web characteristics including compactness, absorbency, elasticity and filt ering power. While the degree of each of the desired characteristics obtained depends on the kind of web selected, and the nature of the particular physical operation, a furtherimportant factor is the condition of the web fibers at the time of the operation. As an example, if a given paper web has a moisture content in the range of 50-100 percent (as compared to the dry weight of the web), while it can be creped, such may only be achieved at a substantial loss in porosity. On the other hand, creping such a Web at normal ambient moisture conditions, while perhaps improving absorbency and porosity, has no substantial effect upon its elasticity and compactmess. This is not surprising when the conditions of the fibers in such webs are considered. At ambient conditions the fibers contain around 5 percent moisture and are, therefore, quite dry and spring-like, and tend to spring back to their original shape after dry creping; at high moisturelevels the fibers haye little or no dimensional stability and slight physical forces drastically compress the web structure.

I There are intermediate moisture conditions, for example at around percent total moisture for commercial grades of kraft paper, at which web fibers are at a plasticity threshold and can be creped to achieve moderate elasticity and compression of the web structure while the fibers have sufficient strength and resiliency so that desired levels of web characteristics such as porosity are obtained. I I I p I I I While these moisture dependent changes in fiber behavior have long been appreciated, there has been no general commercial use of creping, (5 s., of absorbent webs with fibers at the threshold of plasticity and at similai low moisture levels due to the lack of a suitable method and apparatus for" uniformly and controllably irnparting small amounts of moisture to the webs. I

For highly absorbent webs, momentary contact with any source of excess liquid gives an immediate saturation to 100 percent and r'nore, and uniformcontrolled liquid amounts cannot practicably be removed thereafter; For moderately absorbent webs, when an excess of moisture is applied, and then an attempt is' made to dry or doctor off the liquid, it is generally impracticable to get down to low uniform concentrations. The web characteristics to be obtained by physical altering of such webs are undesirablylimited, and many paper webs in these categories have such high plasticity and low wet strength that Iran dling of the wetted' webs, if feasible at all; is at least very difficult. v 1

Even for webs having lower absorption rates, operation at the threshold of plasticity has not been ensured be cause of the inherent inaccuracies and variabilities in the known methods for imparting moisture. For example, due to lack of ameans for uniform moisture metering, a S'afety fa'ctOr of excess moisture has been necessary to ensure that all the fibers in the web receive at least enough moisture to become plastic. Because of the excess inois: ture, the optimum. of the desired characteristics often cannot be reached: After the creping or other physical operation, an extended drying step has been needed to remove the moisture. I I I I I I I A principal objective of this invention is, therefore, to provide a method and apparatus for accurately impart: ing uniform controlled small amounts of moistureto absorbent webs includingthose which arevery highly absorbent, and providing for selectably varying the co ncentration of moisture imparted commensurate withthe type of web involved, the amount of ambient moisture in the web, and the condition of the web desired to be obtained. I I I I.

Water has heretofore been applied to Webs by hard rolls having etched or knurled surfaces in concentrations fixed principally by the degree of roughness of the roll surface. It is not possible; withou t the effort and expense of substituting one such roll for another, adequate; ly to control the amount of liquid which, can be applied to a web to obtain a selectable range of low concentrations. Due to continued contact with the web and the nature of the surroundings, fine particles of duS ,-,.ab'so'rbent lint and the like become imbedded and buildup in the surface of such hard surfaced rolls, which disrup'ts accurate control and causes substantial unevenness in the amount of water which is carried and imparted to the web. Additionally, where such rolls are, for instance; of steel; traces of oil often occur on the surface which prevent wetting and disrupt drastically the uniformity with which water can be carried and imparted by the roll The instant invention eliminates these problems. It provides a method and apparatus'whichachieves selectable variation in the amount of water imparted during operation without stopping and obviates both the need to have on hand numerous etchedrolls and the work in-i volved in changing them. Additionally, the metering roll of this invention is uniquely self-cleaning, and dust and lint are not a problem. I I I Particular embodiments of the invention include a singleapparatus for imparting saturating amounts of liquid as well as controlled low concentrations of moisture and an apparatus for conditioning both sides of a relatively thick web such as knitted goods. I

I The invention, while including the important conditioning of webs preliminary tocreping and compacting, .i-s not strictly limited thereto in its broadest aspects. Forinstance, the invention comp-rehends the accurate rehydra' tion of absorbent webs which have been unduly dried by previous subjection to heat or vacuum. I

Inthe drawings:

FIG. l is a perspective of a preferred embodiment of the apparatus thr'eaded and adjusted to accurately me: ter low" concentration moisture into a web; v

FIG: 2 is a somewhat magnified diagrammatic rep' e sentation in plan of a portion of the metering surface member of FIG. 1;-

FIGS. 3 and 4 are still further magnified plan and sectional diagrammatic views, respectively, depicting the metering surface member; I I

FIG. 5 is apartially broken away, diagrammatic sec-H. tional end view of the apparatus of FIG. ,.l, exaggeratedis new the effect upon the meteringsurface of selected adj u'stine'iitsthat caus I eont riling and the imparting e' rolls to engage the metering roll with substantial a portion the ter of nip where pre FIG. 7

meter ing surface member; and

Patented Nov. 27, 1962 I FIG. 8 is an end view of a preferred embodiment particularly adapted for conditioning knitted and woven textile webs through both sides.

Referring to FIG. 1, the apparatus comprises a stationary frame 18 upon which is rotatably mounted a metering roll 20, driven by chain 23 and provided with a metering surface member 40 hereafter more fully described. Roll 20 provides a surface shown as steel, suitable for applying pressure to a resilient metering surface member. Similarly, a dense rubber cylinder can be employed.

A controlling roll 22 having a generally smooth surface is freely rotatably mounted on a support arm 27, and the arm is pivotally secured to frame 18 to carry roll 22 into nip relation at 21 with the metering roll 20. The pivoted arm 27 together with pneumatic jack 26 provides for adjusting the pressure with which roll 22 engages the metering roll. This jack is adapted to vary accurately the force applied between the rolls by controlled variation of pneumatic pressure applied to it, like jacks 36 hereafter described, and similar jacks on the opposite side of the apparatus (not shown). A vat 24 mounted on frame 18 below roll 22 is adapted to furnish liquid to the meteringsurface 40 by immersing a lower portion of roll 22, which upon rotation carries a film of the liquid to metering surface member 40, the surface of the roll 22 being adsorbent to the liquid, e.g., of a smoothly ground dense rubber surface. The water may contain slight amounts of additives to improve wetting. Thus, in addition to the prime function of controlling the amount of water carried by the metering roll to the web, hereafter explained, roll 22 cooperates with the vat to provide an initial flooding supply to the metering roll. With the arrangement shown in FIGS. 1 and where the metering roll 20 is engaged by the upper surface of roll 22, excess liquid at the meniscus 54 tends to flow downward, away from the nip, counter to the movement of roll 22. This promotes stable, uniform flooding of the metering roll member 40 over a wide range of operating conditions, including substantial roll speeds.

An imparting roll 28 is rotatably mounted in a nip relation at 29 with the metering roll on support arm 37 pivotally secured to the frame. The nip is adapted to receive a web 32 for conditioning at low moisture concentration levels. Controllable pneumatic jack 36 secured at one end to the frame and the other to the support arm 37 controls the pressure with which roll 28 causes engagement of web 32 with the metering roll. The surface of roll 28 can be polished stainless steel (or as will be seen in the embodiment of FIG. 8, according to the invention, for knit goods it may be another metering roll). This roll serves to vary the ratio of amount of liquid imparted to the web to the total amount of liquid carried from nip 21 by the metering roll.

The metering surface member 40 of metering roll 20, according to the invention, comprises a multiplicity of adsorbent surface elements having a limited absorbency, if any, arranged to provide an even distribution of small resiliently deformable capillaries closely arranged throughout the outer surface. I have found that a freshly rough ground rubber roll provides such capillaries, but pressures applied thereto soon cause inoperative glazing of the roll surface. According to the invention, fibers are employed to define the surface elements, together with a resilient material such as rubber which extends at least partially around the fibers in an intimate relation therewith so that the capillaries are resiliently deformable over a range by pressure applied to the surface over a corresponding range. While this resilient material can be in the form of a coating over the fibers, a substantial resilient material thickness under the surface elements is useful to absorb to a slight degree the nip pressure so that the rangeof resilient deformation of the capillary structure is extended over a somewhat wider range of total nip 4 pressures. Where the roll 20 is dense rubber, the backing can be integral therewith.

The capillaries are limited by the intimate rubber or similar resilient material, providing only a limited capacity for capillary retention of water.

According to the invention it is important that there be a great many capillaries per square inch in the surface, uniformly distributed, for only by this is the threshold of plasticity in the web fibers or other desired low moisture content uniformly reached.

Referring to the diagrammatic plan representation of FIG. 2 and the highly magnified, diagrammatic views of FIGS. 3 and 4, the surface member 40 has a particularly large number of evenly distributed tiny capillaries defined by adsorbent, textile threads comprised of essentially nonabsorbent fibers 4-2 crossing in a weave, here fifty ends in each weave direction. This is bonded intimately with a rubber backing 44 so that the rubber extends into the interstices of the bonded textile underface, covering that side of the fibers and effectively resiliently supporting the textile at both the crossings and the valleys. The resilient character of the woven threads and intimate rubber backing provides resiliently deformable capillaries, and the intimate resilient material limits the total water retentive capacity of the member. This provides an outer capillary surface which when flooded retains an even distribution of water. This surface reacts to displace and remove water with a predictable and controllable degree with pressure dependent deformation of the capillaries by the controlled nip towards which the capillaries move. The textile fibers provide a surface which will wear well and will not glaze or otherwise lose its water pick-up capacity.

To provide the essentially nonabsorbent character of the capillary structure, fiber components of my metering surface member where they are not wholly impermeably coated or impregnated as with rubber, must be of nonabsorbent composition or, if absorbent, the aggregative absorbency of the fibers must be limited. Thus Where a woven textile comprised of exposed absorbent fibers, the textile weave must be very tight and the threads thereof highly twisted providing a relatively hard finish, which cooperates with the intimate impermeable backing to prevent entry of large quantities of water into the fibers. I have found that an aggregative absorbency of any substantial degree such as occurs with an exposed surface of knitted or normally woven cotton material is unsuitable as uncontrollably large amounts of moisture are transmitted to highly absorbent rolls, being conditioned even with the use of extreme nip pressures, and the surface mats down. Hence, it is critical to my invention as applied to conditioning absorbent 'webs that any metering surface absorbency must be of a limited character in accordance with the above.

With reference particularly to FIGS. 1 and 5, the operation of this invention is as follows:

A web 32 which may be paper, knitted, woven or unwoven textile or the like is fed through nip 29. Controlling roll 22 driven by movement of metering roll 20 delivers a smooth film of liquid 50 to the metering nip 21. This liquid forms a flooding meniscus 54 at the nip, and the capillaries 40a are fully flooded. The flooded resiliently deformable capillaries at 4011 are narrowed as they approach the line of centers of the two rolls in a predictable amount dependent upon controlled nip pressure, and excess water is forced from the capillaries back into the meniscus. Referring to FIG. 6, controlled small evenly distributed amounts of water are carried by the narrowed capillaries represented diagrammatically at 46 to the line of centers and beyond. Similarly, the amount of pressure of the web 32 against the metering roll 22 exerted by roll 28 predictably deforms the capillaries and the web fibers contact the water in the capillaries as the capillaries are deformed. As the ultimate size of each tiny capillary in the metering surface available intimately bonded to each textile layer. 54 is bonded to themetering roll 20. The resilient rubber the textile as shown diagrammatically at 58. rubber coating seals the textile fibers from the water, the

for carrying liquid is defined by the amount of pressure applied to the metering surface, the concentration of liquidleft in the metering surface member and-the conpressure exerted by roll 28 determines to fine degree the ratio of liquid imparted to the web to that remaining in the capillaries as they move away from web contact.

Referring to FIG. 7, a preferred metering roll surface member 50 comprises a rubberizedsandwich of two

textile layers

52, 54 in 'which a resilient rubber core 56 is Textile layer backing 56 while performing similarly to backing 44 of FIG. 4, also extends over the outer surface in the form of a coating which conforms in detail to the pattern of As the great number of fibers in the woven textile themselves can be absorbent because the capillaries are wholly rubber lined so that resiliency is assured.

The repeated resilient deformation and return'of these metering surfaces in addition to the controlled meter ing metering feature serves a further important function. The

metering surface is often exposed to lint and dust, which i if allowed to remain, would obstruct the control and would adversely affect the evenness of distribution of liquid to the web. But lint and dust particles cannot accumulate here because, due to the continued flexing of I the metering surface, they are not allowed to reside. Particles are urged outwards by the pressure deformations pacted or creped product will be systematically observed, and should there be an indication that the condition of plasticity of the web is not quite right, appropr-iate adjustments of the pneumatic jacks or similar pressure controllers will be made.

The apparatus of the embodiment of FIG. 1 is also adapted to impart higher concentrations of liquids to substrates. The nip 21 between the rolls and 22 of the embodiment of FIG. 1 is accessible from both sides, Ipermitting a substrate to be threaded therethrough, whereby virtually the entire film of liquid picked up by roll 2'2 can be imparted to the substrate.

Also, an idler 70* is positioned in the liquid supply vat 24, spaced apart from roll 22, and a substrate can be led over this idler, through the liquid under roll 22 and out again, whereby both sides of the substrate are exposed to the liquid in the vat.

Referring to the embodiment of FIG. 8, accurately controlled, low concentrations of moisture are applied to both sides of a knitted textile web 68 which can be a double thickness, flattened circularly, knitted tube or the like by two opposed, "relatively adjustable metering systems wherein the surface of each of opposed metering rolls 7% and 72 operate similarly to metering surface member heretofore described, and each also serves as an imparting pressure roll to the other, cooperating to promote fine control of liquid application, controlled by the relative positioning of the two.

It will be understood that the range of low concentrations of liquid metered onto substrates can be varied by heating the liquid and by adding chemical wetting agents. The metering surface can be flooded by direct spraying or immersion preceding the contact with the controlling surface in an embodiment employing certain of the teachings of the invention.

A variety of liquid solutions and suspensions 'canbe controllably and uniformly applied to webs with *the moisture metering'apparatusincluding for instance liquids containing clays, starches and resins.

It is sometimes helpful to apply steam to a web preliminary to moisture metering (e.g., to facilitatespreading of knitted goods) and to apply steam after metering.

A web can be passed through a nip of squeeze rolls after metering for Working liquid into web structure.

Numerous of the particular details of the invention can be modified within its spirit and scope.

What is claimed is:

l. A moisture metering apparatus comprising a continuous metering surface member of resilient and fluid adsorptive material of 'no more than limited'aggregative absorbency having a multiplicity of evenly distributed outwardly disposed resiliently deformable capillariesgenerally defined by "evenly distributed fibers disposed throughout the surface thereof, and'an intimate resilient nona'osorbent materialengaging at least partially'around the fibers in an intimate relation therewith, said metering surface member being mounted for movement with a hard pressure exerting member through a web contact zone at which a web'can be trained againstsaidrneterin'g surface member to impart moisture thereto, a'wat er supply for furnishing water to a flooding Zone apart from said web contact zone for flooding said metering surface member, a controlling surfacemember disposedbetween said flooding Zone and said web contact zone transverse to the direction of movement of said metering surface member and engaged thereupon for compressing said member against the pressure exerting member moving with said web, and adjustment means adapted foreontrolled variation of the pressure exerted by said controlling surface member uponsaid metering'sufface member to control the amount of water carried by the latter to said Web contact zone.

2. The moisture metering'apparatus of claim 1 wherein said fibers are coated generally throughout with readsorbent surface member mounted for moving contact with said metering surface member, and said water supply is adapted to provide water to said controlling surface member whereby water thus applied is carried to and floods said metering surface member.

6. The moisture metering apparatus of claim 1 wherein an adjustable imparting pressure means is-disposed at said 'web contact zone, adapted to'controllably valry the pressure of contact of said web against said metering surface member. p

7. The apparatus of claim 6 wherein said adjustable impart-ing pressure means comprises a hard continuous surface member adapted for moving engagement with said web at said Web contact zone, and an adjustment means for controlled variation of the pressure between said metering surface member and said continuous surfaced member to vary pressure of engagement against said metering surface of the web to controllably vary the concentration of moisture imparted to said Web.

8. The apparatus of claim 7 wherein said continuous surface member comprises a second metering surface member adapted to be provided with a controlled amount of fluid, whereby low concentrations of moisture can be applied to opposite surfaces of a web simultaneously.

9. A moisture meter-ing apparatus comprising a rotatably mounted horizontal metering roll, a rotatably mounted controlling roll in nip relation therewith, means for adjusting the relative pressure between said metering roll and said controlling roll, and liquid supply means for furnishing liquid to flood the surface of said metering roll with liquid preceding pressure contact of said metering roll with said controlling roll, said metering roll having an outer cylindrical adsorbent surface of no more than limited aggregative absorbency comprised of a large number of evenly distributed outwardly disposed resiliently deformable capillaries, defined by closely disposed fibers provided with resilient, nonabsorbent material in intimate relation therewith and said metering roll having a hard inner body of substantially the same diameter as said outer surface, said controlling roll having a generally smooth nonabsorbent hard cylindrical outer surface, and said metering roll being adapted to be engaged by a moving web at a liquid-imparting zone spaced beyond said controlling roll.

10. The metering apparatus of claim 9 wherein the outer surface of said metering roll comprises rubber im pregnated textile, the outer surface of which is defined by fibers of said textile.

11. The apparatus of claim 9 wherein said controlling roll surface is liquid adsorbent and wherein said liquid supply means comprises a means for applying liquid to said controlling roll surface at a point spaced from engagement of said controlling roll against said metering roll, whereby mutual movement of said rolls causes liquid to be carried to and flood the surface of said metering roll in a meniscus defined at the nip engagement of said rolls.

12. The apparatus of claim 9 wherein the nip between said controlling roll and said metering roll is accessible from both sides, said apparatus being thereby adapted to receive a web threaded through said nip to impart liquid thereto.

13. The apparatus of claim 12 wherein said liquid supply means comprises a vat filled with liquid disposed to immerse lower portion of said controlling roll, said apparatus being provided with means for training a web through said vat to impart liquid on both sides thereto.

14. The metering apparatus of claim 9 including an adjustable imparting pressure means adapted to controllably vary the pressure of the engaged web against said metering roll.

15. The apparatus of claim 14 wherein said adjustable imparting pressure means comprises a hard pressure roll mounted in a nip relation with said metering roll and an adustable means for controllably varying said nip pressure whereby said apparatus is adapted for fine control of low-liquid concentrations imparted to webs passing between said metering roll and said imparting pressure roll.

16. A wide-range water metering apparatus comprising a rotatably mounted metering roll, a rotatably mounted controllingdiooding roll disposed below said metering roll in a nip relation therewith accessible from both sides thereof, and a rotatably mounted imparting pressure roll disposed above said metering roll in an accessible nip relation therewith, a liquid vat disposed below said controlling-flooding roll adapted to apply liquid to the lower surfaces of said controlling-flooding roll and provide clearance at the opposite sides of said roll to receive a submerged web trained under said controlling-flooding roll, a first and a second adjustment means adapted to controllably vary the pressure between said controlling-flooding roll and said metering roll and between said metering roll and said imparting pressure roll respectively, said controlling-flooding roll having an adsorbent generally smooth surface, said metering roll having an adsorbent, resilient surface of no more than limited aggregative absorbency comprised of a large number of evenly distributed, open resiliently deformable capillaries, said pressure roll having a generally smooth surface, said apparatus being thereby adapted to impart accurately controlled low concentrations of liquid to said web when said web moves in the nip between said imparting pressure roll and said metering roll, and adapted to impart higher concentrations of liquid when the web moves in the nip between said metering roll and said controlling-flooding roll, and in said vat below said controlling-flooding roll.

17. A conditioning step preliminary to a physical operation on a highly absorbent web comprising controllably filling a multiplicity of closely disposed uniformly distributed resilient capillaries having a pressure limitable moisture retentive capacity in a continuous metering surface member by flooding said capillaries with water and then through a selectably controlled hard pressure member in pressure applying relation to said metering surface member on each side limiting the capillary retentive capacity thereof and removing excess liquid therefrom by resilient deformation of said capillaries thereby selectively regulating the amount of liquid carried away and thereafter engaging said web against a portion of said controllably filled metering surface moving therewith.

18. The method of claim 17 wherein said capillaries are controllably filled by first being flooded, and then engaged by a roll member at a nip which controllably resiliently deforms the capillaries, removing a controlled amount of liquid therefrom.

19. A method of controllably increasing the plasticity of fibers in a web comprising flooding, with a liquid consisting essentially of water, a continuous metering surface which has an adsorbent, essentially nonabsorbent resilient surface at which generally evenly distributed fibers define a multiplicity of evenly distributed, outwardly disposed, close together, resiliently deformable capillaries, the capillaries providing an effective liquid retentive area such, in relation to the total area of the metering surface, as to provide uniform application of liquid, pressing said flooded surface with controlled pressure in a nip defined by hard members leaving a predetermined amount of liquid in each of the capillaries, and directly engaging the web against said thus treated metering surface.

20. The method as claimed in claim 19 in which the web is pressed with controlled pressure against the metering surface by a nip defined by hard members.

References Cited in the file of this patent UNITED STATES PATENTS 581,056 Bodkin Apr. 20, 1897 1,903,038 Fujii Mar. 28, 1933 2,243,604 Parkinson May 27, 1941 2,531,036 Goettsch Nov. 21, 1950 2,681,636 Fridolph June 22, 1954

Claims

17. A CONDITIONING STEP PRELIMINARY TO A PHYSICAL OPERATION ON A HIGHLY ABSORBENT WEB COMPRISING CONTROLLABLY FILLING A MULTIPLICITY OF CLOSELY DISPOSED UNIFORMLY DIDTRIBUTED RESILIENT CAPILLARIES HAVING A PRESSURE LIMITABLE MOISTURE RETENTIVE CAPACIITY IN A CONTINUOUS METERING SURFACE MEMBER BY FLOODING SAID CAPILLARIES WITH WATER AND THEN THROUGH A SELECTABLY CONTROLLED HARD PRESSURE MEMBER IN PRESSURE APPLYING RELATION TO SAID METERING SURFACE MEMBER ON EACH SIDE LIMITING THE CAPILLARY RETENTIVE CA-