IL24826A - Synthetic carpet backing - Google Patents

Description

Synthetic carpet backing CHBMCELL (1963) LIMITED C? 23745 The present invention relates to a fabric which is particularly suitable as a backing for floor coverings, for example tufted carpets or rugs and to articles having such a backing.

The tufted carpets , etce to which the invention relates are of the type manufactured by threading pile yarns through a base fabric or primary backing to form pile loops„ The backing is then coated with a latex to bind the pile in place. In a typical manufacturing process the primary backing is fed by means of spiked feed rolls through a multiple-needle tufting machineo A row of needles, carrying the pile yarn, pass through the backing by shifting the warp and filling yarns of the backing. As the needles are withdrawn from the backing, looper members serve to hold the inserted yarns, thereby forming pile loops which project beyond the face of the backing. The roll of floor covering so tufted is then transferred to the latexing machine<, A commercial latex is coated on the back of the covering by means of a doctor roll in a continuous process, the coated covering then being carried under tension on a pin tenter through the hot drying oven. The latex is cured and dried in the oven for a certain length of timee When the floor covering emerges from the o e ^ the selvag© is trimmed to produce the finished ar icle Carpet p&ttsras aro usually d©signed for a definite width of the carpet0 When similar carpets are laid side by side, as for instance in a wall~to~wall installation, the repetition and continuity of the pattern is necessar „ For this and other reasons of customer acceptance, the finished carpet must be within a close tolerance of its required width, or provision must be made at the tufting stage for the extension or shrinkage drying process. With known backings, it is generally difficult to exactly predict these dimensional changes that will occur.

The nature of the primary backing used in the floor covering also has a significant bearing on the wear and handling qualities of the finished carpet and on the efficiency of its manufacturing process.

Yarns of woven synthetic backings, for example the ones woven with a flat ribbon in both warp and weft have a great tendency to slip and fray while being fed in the tufting machine, and when tension is applied by the pin tenter in the drying oven, or when the selvage of the backing or the carpet is being trimmed. Some backings have been found to be easily damaged in transit or punched under the impact of the tufting needles. Needle deflection and shifting of filling yarns is generally excessive during tufting, which results in confused patterns and pulled out loops » Carpets made with some synthetic backings shrink in width while the latex is cured in the drying oven, the shrinkage being dependent on the oven temperature and duration of dwell of the carpet in the ovem This shrinkage is particularly serious when the flow of the carpet through the drying oven is stopped for any length of ime, which occurs frequently in the manufacturing processo In the light of what has been said above, the present invention provides an improved primary backing fabric for tufted floor coverings and improved floor coverings made therewith.

The applicants' backing has bulk and body, strength and cleanliness, inhibits shrinkage of the carpet width-wise during manufacture, and gives dimensional stability to the finished carpet under varying humidity and room temperature conditions. The applicants' primary backing fabric does not slip nor fray excessively either in the fabric or in the carpet, thus facilitating the manufacturing operations, while giving a durable and stable product having fine handle and appearance. It is substantially uniform in thickness per unit of area.

More specifically, the applicants* backing is a woven fabric in which the warp is made up of substantially twist-less flat synthetic resin monofilament yarns and the filling of low twist continuous synthetic resin multifilament preferably crimped or crimpable (on being relaxed and heated) yarns. The warp and filling yarns may be woven by known textile processes. The applicants' combination of warp and filling yarns produces a backing of high tensile strength, excellent bulk and body and does not freely heat shrink in the width direction curing the manufacturing process. The continuous multifilament filling yarns are interlocked with the flat monofilament warp yams in such a way as to reduce slippage or fraying of the yarn in the backing fabric as well as in the carpet. The filling yarns allow the tufting needles to pass through them without cutting or displacing them. This improves pattern definition and loop anchorage. The tufting process is clean, quiet and efficient.

The crimped bulky multifilament yarn (which is usually substantially circular in cross section) in the filling also provides support for the pile, from its root to a oertain height, against lateral crush.

The invention will be further described in conjunction with the attached drawings illustrating a preferred floor covering and in which:- Figure 1 is an exaggerated schematic plan view of a carpet backing according to the invention.

Figure 2 is a vertical cross section through a carpet having a backing constructed according to the invention.

The fabric of Figure 1 is made up of monofilament warp threads 1 which are flat strips of polypropylene preferably extruded individually as compared with strips cut from a wider band. The filling yarns 2 are low twist continuous multifilament polypropylene crimped yarns. In the carpet of Figure 2, pile loop yarns 4, are looped through the backing in the normal manner. The conventional latex backing is shown as 3.

Figure 2 represents the ideal case where the needle passes through the filling yarns 2, splitting them in half, one half on one side of the loop and the other half on the other side of the loop. This provides strong anchorage. It should be explained that the drawings are exaggerated. In practice, it is preferable that the weave be close with little or no spacing between the respective warp ends. The finished carpet is characterized by substantial absence of displacement of the filling yarns, i.e. the filling yarns remain in substantially the position they were placed in when the backing was woven.

The warp monofilaments 1 are displaced in the backing by the bulky filling yarns 2 so that the former are corrugated transversely with the filling yarns engaging in the corrugations to limit their movement warpwise.

The layer 3 is formed of commercial latex of a type which can easily wet the backing and penetrate the interstices of the warp and filling yarns. Normally, latex does not stick to polypropylene. However, it must wet the fabric and penetrate the interstices in order to avoid peeling and flaking. For good loop anchorage, the latex must adhere to the pile yarns.

In the application of the latex, an oven temperature between 250°F. to 350°F. may be employed. A preferred range of temperature is from 300°Fo to 330°F. Keeping in mind the time-temperature relationship for the curing of the latex, the carpet may stay in the oven for different lengths of time depending on the temperature used. The carpet usually stays in the oven for fifteen minutes, although stops in the oven are sometimes as long as one hour and a half, in which case the heat is shut off, so that the oven temperature falls slowly.

The filling yarns are interlocked with the warp yarns because of their crimp and because they are somewhat cylindrical and thus indent the warp yarns to provide, in the warp yarns, bridges over the filling yarns. In other words, there are bridging parts and underpassing parts in both warp and filling yams. The bulkiness of the filling yarns accentuates these bridges in the warp yarns so as to prevent the filling yarns from moving lengthwise of the warp yarns. On the other hand, the warp yarns, having relatively large bearing surfaces can slip more freely weftwise over the filling yarns.

The construction has advantages in the tufting process. The tufting needles can pass through the filling yarns because of their fixed position warpwise and their multifilament construction.

Since the warp yams are overfilled (there are substantially no interstices) their tendency to shift is reduced and the tendency of the needles to pierce them is enhanced.

Preferred warp is made from flat fiber grade polypropylene monofilament withouttwist and has the following characteristics. The width of the monofilament may be from about OoOlO to about 0.50 of an inch with a preferred range from about 0.030 to about 0.250 of an inch. The thickness of the monofilament may range from about 0.0005 to about 0.010 of an inch. A preferred range is from about 0.001 to about 0.004 of an inch. Sometimes monofilaments are also specified in denier measurements. In this case, the denier would range from about 500 to about 5000 denier, with a preferred range of about 800 to about 1500. A typical denier is 1100. These figures are given merely as illustrative. Individually extruded filaments are desirable as compared with those formed by slitting a film. Filaments cut from a film by slitting usually have rough edges and fibrillation which causes difficulty in the weaving. When the warp ends have to pass through the heddles in the loom, roughness can cause tangling.

The preferred filling yarns are continuous multifilament fiber grade polypropylene yarns, textured either by helical crimping or by other crimping methods or treated so that they will crimp when heated in the form of a floor covering into which they are woven. A typical preferred yarn has a helical crimp ranging from 8 to 30 crimps per inch (preferably 10 to 15 crimps per inch). The crimp should be heat-set at a temperature ranging between 100°C. to 150°C, preferably 130°C. to 140°C. for a period of time ranging from two minutes to one hour.

The twist level is desirably below one turn per inch although a higher twist may be used in modified backings. Lower twist level below one turn per inch is preferred so that the tufting needles can easily pass through the filling yarns of the fabric without shifting the yams. Twist-level depends on the type of fabric desired. Denier range covered is from 500 to 6000 with a preferred range of 800 to 2000. Typical denier used is 1600. The number of picks per inch used in the weaving of a fabric would to some extent depend on the denier of the filling yarn. High denier would require fewer picks and low denier would require more picks to produce a comparable fabric. The filling yarns are lubricated, for one example with about 2% glycerol monostearate as lubricant. Other lubricants may be employed but the lubricant should be non-migratory and should not be prone to soiling.

The preferred synthetic resin for the warp and filling has been given as polypropylene« The applicant prefers to use isotactic polypropylene of commercial fiber grade and of reduced specific viscosity between 1.4 to 5, although ranges from 2.2 to 3»3 are more common and may be used. The approximate melt indices will range from 50 to 1.0 and 10 to 2.5 respectively. The viscosity figure is the reduced specific viscosity of polypropylene resin of 0.1 concentration of decaline at 135°C« Polypropylene mixed with heat stabilizers may be used in natural white colour or be mixed with commercially available pigments to obtain any other desired colour or combination of colourso While the preferred synthetic resin for the warp or filling or both has been defined as polypropylene, other linear polymers may be employed for one or both, as for example polyethylene, nylon, polyacetal polyesters, cellulosic resins, vinyl resins or other synthetic resins that have the mechanical characteristics effective for the purposes defined, as will be understood by those skilled in the arte Carpets or rugs are usually made in 12 feet finished widtho Jute-backed carpets are tufted eleven feet, tea inches and extended in the latexing and drying oven to a finished width of twelve fee o Carpets made from known synthetic backings polypropylene backing must be tufted twelve feet wide to get a twelve feet wide carpet.

Various fabric constructions may be used. A preferred construction is a simple weave as shown. Various combinations of ends times picks may be employed. Preferred fibers have ten to eighteen ends per inch and eight to fifteen picks per inch. Polypropylene backings shrink in both length and width. But, shrinkage in length is not of concern since it can be counteracted, if desired, by varying the number of stitches per inch at the tufting machine.

Because of the high strength, low density and low cost of polypropylene fibers, the backings produced with them are competitive with conventional materials and have the following advantages over them. Pirning and weaving with continuous multifilament filling yarns is relatively easier. Backings so produced are lighter in weight and more convenient to handle.

A smoother handle is obtained by calendering such backings at a sufficiently high temperature although such a step is not necessary for normal carpet end use. Such backings do not require pre-shrinking nor heat-setting and therefore retain their original strength, form and lustre.

A carpet made in accordance with the invention using polypropylene does not shrink in width after it has been tufted and while it is being latexed and dried. The finished carpet is dimensionally stable under varying humidity and room temperature conditions in storage or in use. The textured multifilament yarn filling does not slip nor fray and allows the tufting needles to pass through easily, giving better pattern definition. The backing has greater bulk, body, strength and cleanliness.

Carpets or rugs produced from such a carpet backing have a high crush resistance and greater dimensional stability. Said carpets or rugs are easier to stretch and install. Carpets or rugs made with such backings can be shampooed without fear or staining or puckering and curling. Any type of loop yarns used in commercial carpets may be used in combination with the backings of the invention.

The invention will be exemplified in the following examples, illustrative of a floor covering according to the invention. These examples show, of course, only preferred aspects of the invention and should not be taken in a limiting sense· Example I Plat polypropylene monofilament yarn 0.0025 of an inch thick by 0.100 of an inch wide and approximately 1100 denier was produced using stabilized isotactic polypropylene resin of reduced specific viscosity 3.2. Yarn properties weres Denier 1100 Tenacity 4.5 grams per denier Elongation {%) 21.0 A continuous multifilament helically crimped yarn was prepared using the same resin as above, 1600 denier, 75 filaments crimped by a process described in Canadian Patent Application Serial Number 907,998, filed July 24, 1964, J.DoL. Tessier. A processing lubricant (glycerol monostearate) to the extent of 2% was applied. The yarn properties weres Denier 1600 Tenacity 3.5 grams per denier Elongation ( ) 15.1 A warp of 234-0 ends was prepared with the monofilament yarn using 15 ends per inch to produce a fabric 156 inches wide. The multifilament yarn was used as filling with ten picks per inch of fabric* Simple open weave was used. Some properties of the fabric were: Fabric width 152 inches Weight of fabric 4.5 oz/yd Breaking strength per inch Warp 146 pounds Weft 104 pounds Breaking Elongation (%) Warp 21.0 Weft 84.0 Thickness of fabric 0.040 of an inch A twelve feet wide carpet was tufted on the above backing using a standard commercial tufting machine where the needles were spaced five-thirtyseconds of an inch apart along the width of the carpet. Properties of the carpet after tufting and before latexing were.

Stitches per inch 8.15 Pile Weight 2.60 pounds Loop pull strength 0.83 pounds Breaking strength per inch Warp 109 pounds Weft 80 pounds Width of carpet Eleven feet, eleven and one-half inches The tufted carpet produced in the above process was then latexed with a latex of etyrene-butadiene rubber extended with a calcium carbonate filler. The amount of latex applied was 18 oz. per square yard of carpet. The latexed carpet was stretched out on a pin tenter to twelve feet, four inches and carried two passes through a twenty yard long drying oven.

After the carpet came off the pin tenter it was again passed through the oven for the third time, this time under relaxed condition. All this was done in a continuous process so that the carpet had no time to cool between passes. The oven temperature was maintained at 330°.?. The carpet travelled at the rate of four yards a minute.

After the carpet came out of the oven, the selvage was trimmed from both sides. A twelve feet wide finished carpet was thus obtained. Some properties of the finished carpet were as follows: Weight per square yard 4.1 pounds Loop pull strength 10.0 pounds Breaking Strength per inch Warp 149 pounds Weft 105 pounds A sample of this oarpet 36 inches by 26 inches was drenched with hot water and left to dry. W en dried, the carpet had no visible puckering and had shown no change in dimensions.

Example II The flat polypropylene monofilament yarn of Example I was used to make a warp of 2184 ends, 14 ends per inch.

A continuous multifilament yarn was melt-extruded using the same resin as in Example I. A processing lubricant (glycerol monostearate) in an amount of about 2%, was applied. This yam was then crimped on a false twist crimping machine to give ten for one hour in a relaxed condition* The resulting yarn had the following properties: Denier 1500/75 Tenacity 1.4 grams per denier Elongation (%) 23.0 Tenacity at yield 0.6 grams per denier Elongation ( ) at yield 3 Elastic recovery from 10$ elongation 9 Modulus 20 grams/denier This continuous multifilament yarn was used as filling with 13 picks per inch of fabric. A simple weave was used. The fabric had a width of 152 inches, a weight of 5oz/yd and a breaking strength/inch in the warp of 148 pounds and in the weft of 59 pounds. The fabric had complete elastic recovery when stretched only in weft direction by 5 of its original length. A carpet was made using this fabric. It was tufted, latexed and dried in the same manner as described in Example I. The finished carpet showed no shrinkage in width during drying operation, and it had high loop pull strength of 12 pounds.

A sample of this carpet 36 inches by 36 inches was drenched with 80°Co hot water and left to dry. When dried, the carpet had no visible puckering and did not change in dimensions. In comparative pile crush tests, the carpet made with crimped filling yarn showed 16 improvement over one of otherwise similar characteristics made with jute backing.

Example III The flat polypropylene monofilament warp of Example II was used. A 3700/75 denier continuous multifilament yarn was twisted with 1 tpi Z twist. The twisted yam was stretched at room temperature by 3· 5 x stretch ratio at low input stretching speed of 25 feet per minute. The resulting yarn has the capacity of crimping automatically when relaxed as occurs in the weaving process. This crimp can be enhanced, if desired, by subsequently heating as done in the finishing of the carpet.

This potentially crimpable yarn had the following properties: Denier 1100/75 Tenacity 3-0 grams per denier Elongation (#) 30 % shrinkage at 135 C. for 15 minutes 70 The above yarn was used as filling with 11 picks per inch of fabric. Simple weave was used. The fabric had a width of 152 inches, a weight of 4.0 oz/yd , a breaking strength inch in the warp of 145 pounds and in the weft of 85 pounds. The percent shrinkage of the fabric at 135°C for 15 minutes (relaxed) was in the warp of 30$ and in the weft of 28%.

A carpet was tufted, latexed and dried as in Example I. The finished carpet shrank in the drying oven by 10% in the width direction and 6% in the length direction.

Claims (17)

HAVINO WOW PARTICULARLY OeSORIBEO AKO ASCERTAINED THE NATURE OP 0: R SAID INVENTION AND IN WHAT MANNER THE SAME ID TO ΘΕΕ PERFORMED, WE DECLARE THAT CLAIM IS; WHAT WE CLAIM IS:

1. A backing for a floor covering, comprising, a woven fabric made up of respectively crossing warp ends and filling ends, the warp ends being substantially uniform flat synthetic resin continuous monofilaments, the filling ends being bulky uniform low twist synthetic resin continuous multifilament yarns, the warp being overfilled to substantially eliminate spacing, the filling ends being substantially regularly spaced apart, the warp and weft ends being deformed transversely to the plane of the backing by displacement by the crossing ends to provide in the ends at the crossings arched mutually engaging catching portions thereby to inhibit displacement of the respective warp and filling ends lengthwise of each other.

2. A backing for a floor covering, as claimed in claim 1, in which the yarns are crimped,

3. A backing for a floor covering, as claimed in claim 1, in which the filling ends are yarns treated so that they will crimp on being heated.

4. · A backing for a floor oovering, as claimed in claim 1 or olaim 2 or claim 3, in which the filling ends are of polypropylene.

5. A backing for a floor covering, ae claimed in any of claims 1 to 4, in which the warp ende are of polypropylene.

6. 0 A tufted pile fabric comprising a backing as claimed in any preceding claim and rows of pile extendin through the backing material and piercing the bulky filling ends thereby to provide added support for the pile.

7. A tufted pile fabric, as claimed in claim 6, in which the warp ends are of polypropylene.

8. A tufted pile fabric, as claimed in claim 6 or claim 7 in which the filling ends are of polypropylene.

9. O A method of making a backing for a floor covering, comprising the steps of weaving together warp ends of substantially uniform flat synthetic resin continuous monofilaments and filling ends of bulky uniform low twist synthetic resin continuous multifilament yarns, in such a manner that the warp is overfilled substantially to eliminate spacing and that the filling ends are substantially regularly spaced apart, the warp and weft ends being deformed transversely to the plane of the backing by displacement by the crossing ends.

10. A method as claimed in claim 9 in which the warp ends are of polypropylene »

11. A method as claimed in claim 9 or claim 10 in which the filling ends are of polypropylene.

12. A method of making a tufted pile fabric, comprising, the steps of making a backing as claimed in any of claims 9 to 11 and tufting pile through the said fabric to pierce the bulky filling ends.

13. A method of making a tufted pile fabric, comprising selecting as a backing a woven fabric made up of respectively crossing warp ends and filling ends, the warp ends being substantially uniform flat synthetic resin continuous monofilaments, the filling ends being bulky uniform low twist synthetic resin continuous multifilament crimped yarns or yarns treated so that they will crimp on being heated and in which the warp is overfilled to substantially eliminate spacing and the filling ends are substantially regularly spaced apart, and the warp and weft ends are deformed transversely to the plane of the backing by displacement by the crossing ends to provide in the ends at the crossings arched mutually engaging catching portions, and tufting pile through said fabric to pierce the bulky filling ends,

14. A method as claimed in Claim 12 or Claim 13 in which the warp ends are of polypropylene.

15. A method as claimed in any of claims 12, 13 or 14 in which the filling ends are of polypropylene.

16. A backing for a floor covering substantially as described herein with reference to the accompanying drawings.

17. A tufted pile fabric substantially as described herein with reference to Figure 2 of the accompanying drawings. 18o A method of making a backing for a floor covering substantially as described herein with reference to the accompanying drawings. 19, A method of making a tufted as described herein with reference to DATED THIS 17™ DAY OF DECEMBER 1965.