US 3732136 A
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Description (OCR text may contain errors)
D. s. LORD 11;
PROCESS AND APPARATUS FOR BACKING TUFTED CARPET May 1973 Filed March 17, 1971 java/a J. Zara INVENTQR.
e3 5. --"-'Va$' United States Patent O 3,732,136 PROCESS AND APPARATUS FOR BACKING TUFTED CARPET Donald S. Lord, Columbus, Ohio, assignor to Ashland Oil, Inc., Ashland, Ky. Filed Mar. 17, 1971, Ser. No. 125,317 Int. Cl. B32b 31/16; D05c /00 US. Cl. 156--72 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to tufted carpets and in particular to improved methods and apparatus for applying backing to tufted carpets.
Tufted carpets are composite structures in which the yarn forming the pile, i.e., the surface of the carpet, is needled through a base fabric whereby the base of each tuft extends through the base fabric and is visible on the bottom surface. Tufted carpets are generally of two types, the first being the type commonly known as a nap carpet where the yarn loops are formed by needling or punching a continuous yarn just through the base fabric, thus forming the base of the carpet, while the tops of the loops are generally /1 inch to 1% inches long, thus forming the wearing surface of the carpet. The second type of tufted carpet, commonly known as a shag carpet, has the same base the nap carpet but the tops of the loops have been split or the tips of the loops have been cut off. The surface of the shag carpet is thus formed by the open ends of numerous U-shaped pieces of yarnthe base of the U being embedded in the base fabric.
The loops of yarn are needled through and embedded in the base fabric (the combination of which is the raw tufted carpet) thus forming the tuft base, which must be secured to the base fabric to prevent the loops from being pulled out of the base fabric. The tuft bases are generally secured by applying an adhesive to the back of the raw tufted carpet to bond the tuft bases to the base fabric. A backing material is usually also applied to the back of the raw tufted carpet and bonded thereto with the same adhesive that bonds the yarn to the base fabric. The application of the backing material further secures the loops of yarn since the loops of yarn are then bonded by the adhesive to the backing material as well as the base fabric.
The yarn used in forming the pile of a tufted carpet can be made of any type of fiber known in the art to be useful for tufted carpets, e.g., nylon, acrylics, wool, cotton, rayon and the like.
The base fabric may be of any type known in the art and may be woven, e.g., woven jute, woven slit polypropylene film, burlap, and the like, or may be non-woven fabric, e.g., needle punched, non-woven polypropylene web. Likewise, the backing material may be of any type known in the art, e.g., woven jute, woven slit polypropylene film, burlap, foam materials such as polyurethane foams or blown vinyl foam, and non-woven fabrics such as needle punched, non-woven polypropylene web.
The adhesive used to securel bond the yarn loops in the base of the carpet may be latex, which has been the conventional adhesive for several years; thermoplastic, polymeric adhesives (commonly known as hot melt 3,732,136 Patented May 8, 1973 adhesives), such as described in US. Pat. No. 3,390,035 issued to Sands; or thermosetting adhesives, such as conventional urethanes, blocked polyurethanes and styrenebutadiene material containing a vulcanizing agent.
In backing a tufted carpet there are two main things which must be accomplished. First, the individual yarn loops or tufts must be bonded securely enough to the base fabric and the backing material so that the loops cannot be pulled out of the base fabric under severe carpet usage. This is a problem in both nap and shag carpets but is particularly a problem with the nap type carpet because the longer loops comprising the surface of the carpet may be hooked, for example by sharp protrusions on carpet cleaning machines or by shoe-heel nails, and pulled out of the base fabric. While shag type carpets do not present this problem to such a degree, the individual U-shaped yarn tufts must nevertheless be attached securely enough to the base fabric to withstand the pull of carpet cleaning and shampooing machines. Second, the individual filaments that make up the yarn must be securely bonded in the base of the carpet. If the individual filaments in each yarn tuft are not bonded in the base of the carpet, pilling and frizzing of the carpet will occur due to the individual filaments Working partway out of the yarn. Of course, the filaments may even come completely out of the yarn resulting in the carpet fuzzing or linting. While this is a problem in all tufted carpets, it is particularly a problem in the shag type carpet due to the fact that each U-shaped yarn tuft is made up of many U-shaped filaments twisted to form the yarn. The adhesive may coat the surface of each yarn tuft and securely bond the tuft as a whole in the base, but leave the filaments located at the core of the yarn tuft unbonded and free to move or slide within the yarn tuft. Thus, those unbonded filaments are, especially in the shag type carpet, eventually displaced and extend from the surface of the carpet causing pilling and frizzing or completely separated from the surface of the carpet causing fuzzing and linting.
Generally the yarn loops or tufts will be securely bonded in the base of the carpet when good bundle wrap is obtained with the adhesive. Likewise, the individual filaments will be securely bonded when good bundle penetration is obtained with the adhesive. The bundle wrap and penetration obtained with the adhesive depend to some extent, of course, on the properties of the adhesive but depend primarily upon the apparatus used and the manner in which the adhesive and backing material are applied to the back of the raw tufted carpet.
THE PRIOR ART In general, backing a tufted carpet involves the steps of applying the adhesive, applying the backing material and curing or setting the adhesive. The nature of the last step depends upon the type of adhesive used: latex requires extended and careful drying at elevated temperatures; hot melt adhesives require cooling; and thermosetting adhesives require heating followed by cooling. The backing material is usually applied by pressing the back ing material to the back of the raw tufted carpet after the adhesive has been applied.
With respect to preventing the above problems of tuft pull-out and movement or loss of filaments, the step of applying the adhesive is the most important. The prior art methods and apparatus for applying the adhesive do not provide adequate bundle wrap and peneration by the adhesive to prevent those problems, particularly when the adhesive contains a high level of filler material. One corn mon prior art method, illustrated in US. Pat. No. 3,414,- 458 issued to Lacy, involves passing the back of the raw tufted carpet in contact with a roller, the bottom of which is running in liquid adhesive. The roller picks up a film of adhesive at the bottom and deposits it on the carpet at the top. The carpet is then usually passed over a doctor blade which spreads the adhesive evenly before the backing material is applied. This method is sometimes modified to utilize adhesive in pellet form by using a heated roller. The adhesive pellets will stick to the surface of the roller and melt, thus forming a film on the roller before the point of contact with the carpet. Another method well known in the prior art involves inverting the raw tufted carpet and applying the liquid adhesive to the back of the carpet and spreading the adhesive evenly with a doctor blade before applying the backing material. This method is sometimes reversed in that the adhesive is applied to the backing material which is in turn applied to the back of the raw tufted carpet. This method is sometimes further modified when using thermoplastic or thermosetting adhesive by distributing flakes of the adhesive on the back of the carpet or on the backing material, passing it through a heating zone to melt the adheive, then pressing the carpet and backing material together.
All of these and other known methods of applying the adhesive in backing tufted carpets have been found ineffective in producing sufficient bundle wrap and bundle penetration by the adhesive to prevent tuft pull-out and movement or loss of filaments.
SUMMARY OF THE INVENTION It has been found that improved bonding of the tufts in the base fabric and of the filaments in the yarn tufts is obtained by applying the action of one or more vibrating or reciprocating doctor blades at a point between where the adhesive is applied to the back of the raw tufted carpet and where the backing material is applied. A single doctor blade may be used and may be vibrated or reciprocated in any desired direction and speed. Alternatively two or more doctor blades may be used and each may be vibrated or reciprocated independently or in synchronization with one or more of the others.
In a preferred aspect of this invention two doctor blades are used and are reciprocated in a lateral direction across the back of the carpet with little or no vertical movement. The two doctor blades are synchronized and move in pposite directions at all times. The advantages of this preferred aspect include (a) the elimination of vibration from the carpet backing machine as a whole, which vibrating or reciprocating the doctor blade(s) might cause and (b) the elimination of movement (lateral or vertical) of the carpet itself which otherwise might be caused by the movement of the doctor blade (s).
Another preferred aspect of this invention involves using two reciprocating doctors blades and breaking the raw tufted carpet between the points of contact of the doctor blades, i.e., the back of the raw tufted carpet is placed in a convex configuration between the doctor blades.
The above invention is useful with any of several methods of applying the adhesive. In particular the adhesive may be applied at a point ahead of the doctor (blade(s) by breaking the raw tufted carpet and applying the adhesive at that point. Alternatively, the adhesive may be extruded onto the carpet while it is fiat or into the back of the raw tufted carpet, i.e., by placing the face of the extrusion head adjacent to the carpet passing by the head the adhesive emerging from the extrusion head is forced into the back of raw tufted carpet and down to the base fabric. In the latter, the adhesive surrounds and penetrates the base of each tuft extending through the base fabric. The adhesive is usually extruded as continual, individual small streams, which may be extruded between the rows of tuft bases. In addition the velocity of the adhesive as it leaves the extrusion head may be greater than the velocity of the carpet passing the head, thus more efiiciently forcing the adhesive into the back of the raw tufted carpet.
It has been found that the very best bonding is obtained when the adhesive extrusion methods described in the above paragraph are combined with either or both of the above described uses of vibrating or reciprocating doctor blades.
DESCRIPTION OF THE INVENTION AND DRAWINGS The broad concepts of the present invention may be better understood by reference to the drawing which i1- lustrate some specific configurations which may be used to practice the invention.
FIG. 1 illustrates the method and apparatus wherein the vibrating or reciprocating doctor blade may be used. FIG. 1 also illustrates applying the adhesive where the carpet is broken. The raw tufted carpet 2 is advanced from roll 1 past breaker roller 3 where the adhesive is applied applicator 4 from adhesive reservoir 5. The carpet with the adhesive on the back thereof then passes the vibrating or reciprocating doctor blade 7, which spreads and evenly distributes the adhesive and forces the adhesive into and between the tufts. The doctor blade may be vibrated or reciprocated in any direction but is most conveniently reciprocated in a direction perpendicular to the direction the carpet is moving. The doctor blade may also be moved in a circular, elliptical or other motion in essentially the same plane as the carpet. The use of support roller 6 is usually desirable to increase the effectiveness of the vibrating or reciprocating doctor blade. The backing material 8, advanced from roll 9, is contacted with the back of the raw tufted carpet and the adhesive thereon at roller 10. The backed carpet 11 then passes rollers 12 which press the backed carpet to assure good contact of the backing material, raw tufted carpet back and adhesive. The carpet is then passed through treating zone 13, where the adhesive is cured or set by heating or cooling, depending on the type of adhesive, and finally wound on roll 14.
FIG. 2 illustrates a preferred aspect of this invention which involves the use of two doctor blades and breaking the carpet between the two doctor blades. The raw tufted carpet 41 fed from roll 42 is passed over roller 43, then under and adjacent to extruder head 44. The adhesive from reservoir 46 is forced by extruder through extruder head 44 into the back of the raw tufted carpet 41 as it passes by the extruder head. The carpet then passes doctor blades 60 and breaker bar 61 and rollers 48 at which point backing material 49 fed from roll 50 is applied to the carpet. The backed carpet 51 then passes through treating zone 52 where the adhesive is cured or set and finally to take-up roll 53. Doctor blades are preferably reciprocated in a direction perpendicular to the direction the carpet is moving and reciprocated in opposite directions to each other. Breaker bar 61 (which may be a roller if preferred) and the two doctor blades are positioned so that the carpet is forced to follow an arcuate path. Preferably, an accumulation or roll of adhesive will exist just ahead of each doctor blade. This roll of adhesive is particularly helpful ahead of the second doctor blade because at that point the tufts are spread and the adhesive can penetrate better to give improved bundle wrap and penetration.
FIG. 2A is a section view of FIG. 2 and illustrates a particular method of applying the adhesive usefully in the present invention. In FIG. 2A the adhesive 62 is forced by extruder screw 61 of extruder 45 through head 44 and out the numerous orifices 63 thus forming ribbons 64 of adhesive. The raw tufted carpet 41 is a nap type carpet (moving away from the viewer in this section view) formed of a non-woven base fabric 65, such as needle punched, non-woven polypropylene web, and yarn 66 which has been needled or punched through the base fabric 65 to form the tuft bases 67. The single yarn 66 shown in FIG. 2A is but one of many traversing the width of carpet 41 and forming rows of tuft bases 67 down the length of carpet 41. Extruder head 44 is positioned so that the tips of tuft bases 67 just lightly brush the base of the head and positioned such that adhesive ribbons 64 are deposited between the rows of tuft bases. This is accomplished by using an extruder head having orifices 6'3 spaced the same distance apart as are the tuft bases 67. While extruder 45 should preferably be a continual extruder, i.e., produce an unbroken stream of adhesive from head 44, a pulsating extruder could be used provided it delivered sufiicient adhesive to the carpet back. The extruder head may be of any suitable configuration known in the prior art that produces a film, ribbons, strips, wedges, etc., of adhesive. In general, the velocity of the adhesive, illustrated as v in FIG. 2A, may be equal to or greater than the velocity of the raw tufted carpet, illustrated as v in FIG. 2. The velocity, v of' the carpet 41 normally ranges from about 12 ft./min. to about 50 ft./min., or higher, with the preferred velocity being from about 20 ft./min. to about 40 ft./min. In a backing operation tufted carpets are usually processed at about 15 to 30 ft./ min. The velocity of the adhesive, 1 leaving orifice 63 may range from 1.0 to about times the velocity of the carpet 41. Preferably the adhesive velocity, v,,, should range from about 1.5 to about 3 times the carpet velocity, V and usually about 1.5 to about 2.5 times.
At the point of breaking the carpet (roller 3 and bar 61 in the drawing) the radius of curvature of the back of the raw tufted carpet should be small enough to provide a spreading apart of the tuft bases extending through the base fabric. The adhesive can thereby flow more easily between the tufts and flow more easily around the tufts down to and onto the base fabric, which produces the superior tuft bonding. As illustrated in the drawing, during processing the carpet is inherently straightened immediately following the breaking. When the carpet is straightened the tuft bases move closer together or back to their normal relative spacing after being spread apart by the breaking. When the tuft bases move closer together as the carpet is straightened the adhesive surrounding the tuft bases is compressed and forced into, i.e., penetrates, the yarn at the tuft base. This penetration by the adhesive of the yarn produces the superior filament bonding in the tuft base. In general, sufiicient tuft base separation is obtained when the carpet is broken along a radius of curvature of up to about 4 inches or greater, depending upon the type of carpet. Preferably the radius of curvature should be less than about 3 inches and most preferably less than about 2 inches.
It will ofcourse be clear to one of ordinary skill in the art that various means may be used to break the carpet. While the drawing illustrates a breaker roller, a breaker bar or other configuration could be used. It is further pointed out that it is not necessary that there be a support such as a roller or bar under the carpet at the point of breaking. The carpet may, for example, be broken by forcing the carpet to loop or buckle, producing a profile similar to the letter omega (S2), thus producing the desired breaking without a support at the point of breaking.
In general, a convenient angle of breaking (angle A in FIG. 1) will be somewhere in the neighborhood of 90. However, the angle may be as large an angle as a particular apparatus is capable of producing (180 or even greater, e.g., in the case of the unsupported breaking referred to in the preceding paragraph) or may be as small an angle as will produce the length of tuft separation necessary for proper adhesive flow and penetration. Preferably the angle of breaking should range from about 30 to about 150 and most preferably from about 4'5" to about 135.
It will also be clear to one of ordinary skill in the art that the adhesive applicator in FIGS. 1 and 2 may be of any type, e.g., force feed or gravity flow, which is capable of supplying the required amount of adhesive to the carpet back in an evenly distributed manner.
If an adhesive extruder similar to that of 44 in FIG. 2 is used, it should be noted that the position of the head is important, i.e., it should be adjacent to the back of the passing raw tufted carpet. If the head is some distance from the back of the passing carpet, the extruded adhesive will simply be deposited on the surface of the back of the carpet rather than being forced into and around the tuft bases and down to the base fabric. The extruder head may be positioned in such a manner that it is in heavy contact with and actually exerts pressure on the passing carpet. Although the head may be positioned in this manner it is, however, generally undesirable because the abrasive action of the back of the rawtufted carpet rubbing across the extruder head will wear off the surface of the head. The best position for the head is such that face of the head is just adjacent to the back of the carpet, i.e., the passing carpet should just lightly brush the face of the head.
The amount of adhesive applied to the carpet depends on the type and composition of the adhesive, the type and weight of the carpet, the type of backing material and the method of applying the adhesive. The amount of adhesive applied should be sufiicient to provide adequate bundle wrap and bundle penetration for good tuft and filament bonding in the carpet back. Generally, adhesives are applied to tufted carpets in amounts ranging from about 15 oz./yd. to about 30 oz./yd. or higher, When practicing the present invention, any amount in the above range may be used, but about 20 oz./yd. is usually used, depending on the strength of the bonding desired. The adhesives may of course contain fillers of either the extending or pigmenting kind well known in the art. Common extending fillers are barium sulfate, calcium carbonate, talc, clay, silica, walnut shell flour and the like. Common pigmenting fillers are calcium carbonate, clay, silica and the like. Fillers are generally present in a filter-to-adhesive weight ratio of from 0 to 4:1, depending again on the type of adhesive. The adhesive may also contain other additives well known in the art, such as antioxidants, plasticizers, viscosity adjusting agents and the like.
Curing or setting the adhesive may be accomplished in the treating zone (13 or 52 in the drawing) in any manner known in the art for the particular adhesive used. Latex adhesives are normally cured by moderate prolonged heating to remove the water content. Thermoplastic adhesives are usually set by simple cooling, while thermoset adhesives require an initial heating (to crosslink or polymerize the resin) followed by cooling.
The doctor blade(s) may be cooled, e.g., by air or water; left at ambient temperature; or heated, e.g., by steam, electricity or flame. The temperature of the doctor blade will depend on the adhesive used and the result desired, as will be apparent to one skilled in the art. For example, when a thermoplastic adhesive is used the doctor blades are usually heated to keep the adhesive fluid until the backing material is applied. The doctor blade(s) used in this invention may be of any shape or configuration but it is preferred that the doctor blade(s) have a rounded leading edge which will tend to force the adhesive into the tuft bases. They may have other characteristics which aid in working or forcing the adhesive into and around the tuft bases. For example, the edge of the doctor blade(s) in contact with the carpet back may be serrated or have grooves therein. Such designs on the surface of the edge of the doctor blade(s) help move the tuft bases as the doctor blade(s) are vibrated or reciprocated thereby better forcing the adhesive into and around the tuft bases.
As indicated above the doctor blade(s) may be vibrated or reciprocated in any fashion desirable. However, it is convenient to move the doctor blade(s) in the same plane as the carpet, such as circular or elliptical motion. In some instances some vertical movement may also be beneficial in obtaining the desired penetration of the ad- 7 hesive. The most convenient motion is a simple reciprocating motion perpendicular to the direction the carpet moves; and the mechanical apparatus providing this reciprocating motion is usually the most economical. The length of the stroke made by the doctor blade(s) is usually between A; inch and /2 inch but may be more or less depending on the particular carpet, adhesive and blade configuration and motion used. Normally, when the simple reciprocating motion is used the blades are moved about inch in each direction.
The speed with which the blade or blades are moved will depend on the type of carpet, the number of tuft rows per running foot of carpet, and the speed at which the carpet is passed under the doctor blade(s). It is usually desirable that each row of tufts receive at least one stroke with each doctor blade. Two or more strokes per tuft row by each blade usually provides even better penetration of the adhesive. Each doctor blade may be reciprocated at about 500 to 1200 cycles per minute (c.p.m.), depending on the above factors. For example a carpet having tuft rows per foot processed at 40 ft./min. under 2 doctor blades reciprocating at 800 c.p.m. will provide 2 strokes per blade on each tuft row for a total of 4- strokes per tuft row. (While each cycle of the blade produces two strokes, allowance is made for one half of the strokes falling between tuft rows.)
As noted above, a particularly preferred aspect of this invention is breaking the carpet between the points of contact of two vibrating or reciprocating doctor blades. This aspect is illustrated by breaker bar 61 in FIG. 2. Breaking the carpet at this point may be accomplished by a bar or roller. A bar for this use may be rounded, but it has been found that a bar having square corners or a rounded front side and a square back corner gives better breaking of the carpet allowing better penetration of the adhesive. This preferred aspect gives particularly good results when an excess or roll of fluid adhesive is maintained just ahead of the second doctor blade.
While all the figures in the drawing illustrate the raw tufted carpet being fed from a roll, it will be clear to one skilled in the art that the carpet may be fed in numerous ways, e.g., in individual flat sections or directly from the tufting operation, thus eliminating the need for intermediate storage of the raw tufted carpet. Likewise, the carpet may be pre-treated or post-treated in any manner necessary for the particular carpet involved, e.g., preor postsizing such as in a tenter frame, steam conditioning to preserve or enhance dyeing ch'aracteristics, and the like.
The following examples illustrate specific embodiments of the broad invention.
Example -I The apparatus illustrated in FIG. 1 is used in this example. The apparatus is adapted to hold raw tufted carpet supply roll 1 of a size feet in width and 100 feet in length. Breaker roller 3 is 2 inches in diameter thus providing a radius of curvature for the back of the carpet across the breaker roller of approximately 1 /2 inches (including the thickness of the carpet). Angle A is 90 and applicator 4 is a gravity flow type which applies a film of adhesive. Doctor blade 7 is slidably mounted so that it may move perpendicular to the direction the carpet is moving and so that it may be adjusted vertically to apply any desired pressure on the carpet. A drive mechanism is provided to reciprocate the doctor blade at the rate of 600 cycles per minute along a stroke of one-fourth inch. In this particular arrangement the doctor blade moves only in the lateral direction with very little or no movement in the vertical or longitudinal directions. Rollers 12 press the backing material to the adhesive coated carpet back. Treating zone 13 is a chamber 120 feet in length of variable intensity infra-red lights. Take-up roll 14 is driven by a variable speed electric motor to provide for any processing speed desired and to keep the backed carpet taut through the treating zone 13.
The carpet is a nap carpet composed of a burlap base fabric weighing about 16 oz./yd. and tufted with about 30 oz./yd. of bulked continuous filament nylon carpet yarn which is needled into the base fabric at 8 needles per inch across the width of the base fabric and about 7 stitches per running inch of base fabric. The nap or tuft loops extend A; inch above the base fabric and the tuft bases extend /a inch below the base fabric.
The backing material is also burlap weighing about 16 oz./yd.
The adhesive is a standard self-curing latex composition comprising:
Carboxyl modified butadiene/styrene copolymer latex Tetrasodium pyrophosphate (dispersing agent) 0.25 Calcium carbonate (extender) 200 Sodium polyacrylate (thickener) 0.8 Water The adhesive has a viscosity of about 8000 centipoises at room temperature and is applied at a level of 25 oz./ yd. The carpet is processed at between 15 and 30 ft./min. and dried at a temperature of C.
This example produces a tufted carpet requiring on the average a pull of 12 to 14 pounds to pull one of the tuft loops out of the base fabric, evidencing excellent bundle wrap by the adhesive.
Example II Parts (wt.)
Ethylene copolymer 14.0
Microcrystalline petroleum wax, M.P. '170 F. 17.4
Rosin 383 Barium sulfate filler 30.0 Stabilizer (Ionol G-685; 2,4,6-tritertiary-butylphenol) 0.3
The ethylene copolymer is a 67:33 copolymer of ethylene and vinyl acetate having an inherent viscosity of 0.78 (0.26% in toluene at 86 F.), a melt index of 26 (ASTM-D-l238-57T), and a softening point of 243 F. (ring and ball). This adhesive has a viscosity of about 3000 centipoises at 335 F.
The adhesive is applied to the carpet back at 335 F. at a level of 20 oz./yd. The doctor blades are reciprocated at 800 c.p.s. on a stroke of one-fourth inch. The carpet is processed at a speed of 30 ft./sec. and cooled to a temperature of 85 F. by forced air cooling in 52 before being wound on take-up roll 53.
This example produces a tufted carpet requiring a pull of 26 pounds to pull one of the tuft loops out of the base fabric.
What is claimed is:
1. In a process for backing tufted carpet which comprises:
applying adhesive to the back of raw tufted carpet;
applying backing material to the adhesive-bearing side of the raw tufted carpet; and
treating the backed tufted carpet to set the adhesive;
the improvement comprising:
forcing the adhesive into or around the tuft bases by applying the action of a vibrating or reciprocating doctor blade.
2. A process according to claim 1 wherein the doctor blade moves essentially parallel to the back of the raw tufted carpet.
3. A process according to claim 2 wherein the doctor blade is reciprocated in a direction essentially perpendicular to the direction in which the raw tufted carpet moves.
4. A process according to claim 3 wherein the doctor blade is reciprocated at a speed sufficient to apply at least one stroke of the doctor blade to each row of tuft bases in the raw tufted carpet.
5. In a process for backing tufted carpet which comprises:
applying adhesive to the back of raw tufted carpet;
applying backing material to the adhesive-bearing side of the raw tufted carpet; and
treating the baked tufted carpet to set the adhesive;
the improvement comprising:
forcing the adhesive into or around the tuft bases by applying the action of two vibrating or reciprocating doctor blades.
6. A process according to claim 5 wherein the doctor blades are moved in opposite directions to each other.
7. A process according to claim 6 wherein each doctor blade is reciprocated at a speed sufficient to apply at least one stroke of that doctor blade to each row of tuft bases in the raw tufted carpet.
8. In an apparatus for backing raw tufted carpet comprising:
a carpet receiving opening extending the length of the apparatus;
means for advancing the carpet through the opening;
means in the first part of the opening for applying adhesive to the back of the raw tufted carpet passing through the opening;
means in the latter part of the opening for applying backing material to the adhesive-bearing side of the passing carpet; and
means for treating the backed tufted carpet to set the adhesive;
the improvement comprising:
means in the intermediate part of the opening capable of contacting the back of the raw tufted carpet and imparting motion to the tuft bases of the passing carpet and forcing the adhesive into or around the tuft bases.
9. Apparatus according to claim 8 wherein the means in the intermediate part of the opening for imparting motion to the tuft bases comprises a vibrating or reciprocating doctor blade.
10. Apparatus according to claim 8 wherein the means in the intermediate part of the opening for imparting motion to the tuft bases comprises two vibrating or re ciprocating doctor blades.
11. Apparatus according to claim 10 wherein the doctor blades are slidably mounted and are movable in opposite directions to each other.
12. Apparatus according to claim 11 wherein the means in the intermediate part of the opening further comprises a means for breaking the carpet between the two doctor blades whereby the adhesive-bearing side of the row tufted carpet is placed in a convex configuration between the two doctor blades.
References Cited UNITED STATES PATENTS 3,150,023 9/1964 Penman 156-73 WILLIAM A. POWELL, Primary Examiner U.S. Cl. X.R.