JPH0340140B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a primary base fabric for tufted carpets (hereinafter abbreviated as base fabric) with improved tufting properties. More specifically, the present invention relates to a base fabric for tufted carpets, which is made of a polypropylene fabric and has improved tufting properties. Tufted carpets are made by using jute cloth (which is hardly used at present), recent polypropylene tape yarn fabrics, polypropylene split yarn fabrics, or needle-punched synthetic cotton etc. on these polypropylene fabrics. Non-woven synthetic fibers manufactured by the spunbond method and the like are used. Tufted carpets are manufactured by using a tufting machine to pierce these base fabrics with surface threads (pile yarn) in the form of tufts (pile) to create what is called pile fabric, and then attaching and fixing this pile fabric to the backing. Ru. In the process of making tuffed carpet, there are two types: the pile is left in a loop shape, and the tip of the loop is cut and opened, and these are called the loop type and the cut type (first and second types).
(Refer to the diagram) Whether it is a loop type or a cut type, the pile will fall out if left as is, so apply adhesive to the back of the base fabric to fix the pile. Furthermore, a backing is applied to hide the back side of the tufting and add thickness to the ground to increase the value of the carpet. This backing material is called a secondary base fabric and is distinguished from the primary base fabric described above. As the secondary base fabric, jute fabric, various synthetic fabrics, etc. are used. In some cases, foamed rubber, urethane resin, etc. are used to serve both as an adhesive for fixing the pile and as a backing base fabric. The spacing between piles planted in the base fabric during the tufting process is determined by the tufting machine. The spacing between the needles measured in the horizontal direction of the carpet (width direction of the machine) is called the gauge, and for tuft machines there are 5/32 inch, 1/8 inch, and 1/1 inch.
There are gauges such as 0 inch, 5/64 inch, 5/16 inch, and 3/16 inch. This gauge determines the lateral spacing of the piles. The density of the pile in the vertical direction of the carpet (the tufting direction of the machine) is called the stitch, which indicates how many needles are inserted in one inch to create the pile. The following properties are generally required for the base fabric of tufted carpets. (1) Low penetration resistance to tufting needles. (2) The distribution of penetration resistance values on the base fabric must be uniform. (3) After tufting, the pile should not come out from the base fabric until the backing is completed. In other words, it must have what is called an appropriate pile gripping force. (4) It should have enough stiffness to prevent wrinkles during tufting, and should not deform even when subjected to a small amount of stress or heat. When a tufting needle makes a pile, it must penetrate the base fabric, but the smaller the penetration resistance and the more uniform the distribution of resistance values, the more the height of the pile will be constant and the arrangement will be orderly, giving a good pile fabric. Naturally, it is necessary to have enough gripping force to sufficiently hold the pile that has been driven. The base fabric is twisted and rolled up during tufting. Also, in the process of applying adhesive and backing, the paper is similarly rolled up, twisted and rolled up, and heat is also applied for drying. Therefore, it is required to have sufficient strength and stability against heat to withstand these processes. In general, non-woven fabrics have thin fibers piled up in irregular directions at a uniform density, so the penetration resistance to tufting needles is small and the distribution is uniform (the needles do not penetrate the thin fibers). (penetrating the space between fibers)
(See Figures 3 and 4). On the other hand, the constituent fibers of a polypropylene woven base fabric are thicker than those of a nonwoven fabric. Therefore, the needle sometimes penetrates the constituent fibers and sometimes penetrates the space, and there is a difference in penetration resistance between the two (see FIGS. 5 and 6). On the other hand, non-woven fabrics have a small pile gripping force and their constituent fibers are weak, so the so-called stiffness of the fabric is weak. In contrast, the woven base fabric has strong gripping force and stiffness. In other words, nonwoven fabrics are excellent in (1) and (2), which are the required characteristics of base fabrics, while woven fabrics are excellent in (3),
It can be said that item (4) is excellent. In recent years, as tufted carpets have become finer gauge - tufting machines with narrower needle spacing are being used and the number of stitches has increased - the needles have become thinner and the fineness of the fibers that make up the pile yarns (surface yarns) has also increased. It's getting thinner, including. In this case, the characteristics in items (1) and (2) are even more required. As already mentioned, the polypropylene woven fabric has some weaknesses in characteristics (1) and (2). To improve this, there are two ways to lower the penetration resistance: (a) applying an oil finish; (b) reducing the fineness of the fibers that make up the fabric (increasing the degree of splitting in the case of split yarns); and making the distribution of penetration resistance uniform. In order to achieve this, (c) a method of increasing the density of the woven structure, these methods are used alone or in combination. Although each of these methods is effective, they have their own limitations in terms of economy and other characteristics of the base fabric. That is, in method (a), the cost increases as the amount of oil adhered increases, and depending on the type of oil, it is necessary to consider the effect of the oil on the dyeing solution during dyeing of pile fabric. (B)
In this method, there is a possibility that the stiffness of the base fabric will decrease, the strength will decrease, and the base fabric will tear due to the fine denier, and there is a limit to the decrease in fineness. In method (c), in order to create a weaving structure that corresponds to the pile density, as the pile density increases, the fineness of the tape yarn decreases and the weaving structure must become denser, so the high weaving cost of the tape yarn is the basis. Affects cloth cost. Further, even if the fineness of the tape yarn is reduced, the problem of increased penetration resistance due to the denser structure arises. The present inventors studied the above-mentioned problems with the polypropylene tape yarn woven fabric base fabric, and by using foamed stretched tape yarn, that is, a stretched tape yarn containing air bubbles, as the base fabric material, it is close to non-woven fabric (1) (2) It has been found that it is possible to economically produce a woven base fabric having the following properties. Since the air bubbles in the foamed stretched tape yarn form elongated ellipsoidal spaces resulting from the stretching and are present in large numbers, there is a high probability that the tufting needle will penetrate the air bubbles, and therefore the penetration resistance will be small. The decrease in strength will be smaller. In addition, the distribution of penetration resistance values becomes uniform, thereby improving warp lines, weft steps, insect bites, and ripples in the pile fabric obtained by tufting it onto the base fabric. Furthermore, since the air bubbles remain as elongated ellipsoids, tearing of the tape in the fiber axis direction, which normally occurs in stretched tapes around needle penetration points, is less likely to occur, and the strength of the base fabric is less likely to deteriorate due to tufting. These also mean that the amount of finishing oil deposited can be reduced. Furthermore, unlike monofilament polymers, foamed stretched tape yarn has a structure with thickness and width, so it is easy to weave, and the woven base fabric retains the stiffness required in the tufting process. becomes. In this way, expanded stretched tape yarn can be said to be an ideal material as a base fabric material. Foamed stretched tape yarn is produced by mixing polypropylene resin with a foaming agent with a decomposition temperature of 180 to 250°C as listed below, metal soap, lubricant such as low molecular weight polyethylene, and powder, and using a conventional reusable film manufacturing equipment or flat film manufacturing equipment. It can be made using a conventional stretching device. Examples of the blowing agent include azodicarbonamide, P-toluenesulfonyl semicarbazide, and trihydrazinotriazine. The suitability of foamed stretched tape yarn as a base fabric material is determined by the bubble inclusion rate. The bubble inclusion rate is determined by the structure of the tufted carpet (gauge/number of stitches, pile height, pile yarn form, material) and base fabric structure (tape yarn fineness, thickness, width, and weaving structure). If the encapsulation ratio is too small, the characteristics of the foamed drawn tape yarn will not be obtained, and if it is too large, the yarn will be stiff and have low strength. As shown in the examples below, the inclusion rate is generally suitable to be 0.95 to 20%. Here, the inclusion rate is calculated by the following formula. Encapsulation rate = (1-ρ ₂ /ρ ₁ )×100 (%) where ρ ₁ : True specific gravity of polypropylene (usually 0.91) ρ ₂ : Bulk specific gravity of foamed tape yarn (underwater displacement method (JISK-7112-1977 5) Regarding the texture of the woven base fabric, the texture of the base fabric is determined according to the specifications of the tuft, but from the standpoint of productivity (weavability) of the base fabric, it depends on the weft density (density of the weft yarns). Productivity decreases inversely, but weft density (density of weft yarns) does not affect productivity of the base fabric much. Because of this, the latitude density has traditionally been 18~
A relatively high density such as 28 pieces/inch is used. In this case, since the warp threads of the tufting needle are thin, the tufting needle penetrates between the warp threads with almost no needle deflection. In other words, it can be said that the relative penetration resistance of the warp threads is uniform. Therefore, improvements in the base fabric can be achieved primarily by replacing the weft yarns with foamed drawn tape yarns. On the other hand, although the warp density has little effect on the productivity of the base fabric, it is preferable to have a smaller warp density from the viewpoint of workability and other aspects. In this case, the fineness of the tape must be increased in order to maintain the strength of the base fabric, but in that case the tufting needles will have to penetrate the warp, so the improvement of the base fabric is to change the warp to foam-stretched tape yarn. It can also be done by Of course, both of the above improvements can be achieved by replacing both the warp and weft with foamed drawn tape yarns. However, if both the warp and weft are made of foamed yarn, the stiffness of the base fabric will become a little weak. Therefore, either one
Particularly good is one in which only the weft is made of foamed stretched tape yarn. The properties of the base fabric woven from the foamed stretched tape yarn will be explained in more detail in the following examples. In the evaluation of Examples, "pile surface finish" is an evaluation of defects that occur during tufting. There are various types of defects, such as those caused by the tufting machine, the pile material, and the base fabric, but the following four points are representative of those caused by the base fabric. (1) Warp threads: These are warp-like cracks that occur on the pile surface due to excessive gripping force (especially when the weave of the warp threads is large) and needle runout. If the warp is a foamed drawn tape yarn, this will mainly prevent needle runout and be improved, but if the warp is unfoamed but the weft is foamed, the distribution of penetration resistance will be uniform in the horizontal direction as well. An effect occurs (possibly due to the weft becoming flexible) and is improved. (2) Weft row... Mechanically, this is caused by poor feeding and pulling of the base fabric during tufting, and for the base fabric, it is due to an interference pattern that occurs in the weft direction due to an imbalance between the base fabric density (number of weft threads) and the number of stitches. It is a stage like this. When foamed stretched tape yarn is used for the warp and weft (particularly the weft), the distribution of penetration resistance in the warp direction becomes uniform, resulting in a significant improvement.
When foamed stretched tape yarns are used for the wefts, the number of wefts can be reduced compared to conventional wefts depending on the tuft specifications. (3) Insect eating: This is a phenomenon in which the pile partially collapses or becomes low due to the thickness of the pile yarn, uneven twisting, and uneven gripping force of the base fabric. In the case of a base fabric using foamed stretched tape yarns, the needle penetration resistance is low, the necessary gripping force is provided, and the distribution thereof is uniform, resulting in a significant improvement. (4) Ripples: This is a phenomenon similar to latitudinal steps, but a wave-like curved pattern appears due to the imbalance between the base fabric density and the number of stitches. In the case of foamed drawn tape yarn, the appropriate range of the number of wefts per unit number of stitches is wider than that of unfoamed drawn tape yarn, resulting in an improvement similar to that of weft rows. This is especially effective for patterned items where there is a concern that the pattern may come loose. In addition, the strength remaining rate was calculated using the following formula. Strength remaining rate = Strength of base fabric after tufting / Strength of base fabric before tufting ×
100 [%] The pile surface finish was ranked as follows. ◎ Almost no defects ○ Only a few defects △ Many defects Example 1, Comparative Example 1 A foamed yarn with a bubble inclusion rate of 5% was produced by forming a film using a T-die and then hot stretching it. A 1/10 inch gauge pile fabric was made using nylon pile yarn on a base fabric using this foamed stretched tape yarn as the weft. As a comparative example, a nylon pile fabric was made under the same conditions on a base fabric using normal drawn tape yarns in both warp and weft. Table 1 shows each specification condition and evaluation of pile fabric.

【table】

[Table] As can be seen from the evaluation in Table 1, by using the foam base fabric, the finish of the pile surface is greatly improved compared to when a normal flat yarn base fabric is used. It is also clear that the strength retention rate in the latitudinal direction is large and that it can be used satisfactorily. Example 2, Comparative Example 2 A tuft test was conducted in the same manner as in the previous example using a foamed stretched tape yarn with an inclusion rate of 10%. Second result
Shown in the table.

[Table] As is clear from Table 2, the present invention improves the finish of the pile surface. Furthermore, it can be seen that there is little decrease in strength due to tufting and it can be used satisfactorily. Example 3, Comparative Example 3 A test similar to Example 1 was conducted using a foamed stretched tape yarn with an inclusion rate of 8% as the base fabric. Comparative Example 3 is an example using an unfoamed drawn tape yarn corresponding to Example 3. The results are shown in Table 3.

[Table] As is clear from Table 3, the finish of the pile surface was greatly improved by using the foam base fabric. It is also clear that the strength retention rate is high and that it can withstand use sufficiently. Example 4 Stretched tape yarns with various encapsulation ratios were produced, and base fabrics made by using these yarns as weft yarns and base fabrics after tufting were evaluated. The test conditions in this case are as follows. Base fabric: Warp 400d stretched tape yarn (unfoamed)
24 pieces/inch Weft 600D foam stretched tape yarn 18 pieces/inch Tufting conditions: Cut type Pile length 4
m/m gauge 1/10 inch stitch 14 Results are shown in Table 4

【table】

[Table] From this result, the finish of the pile surface is not improved when the inclusion rate is around 0.5%, but when it is 1 to 10%, there is sufficient stiffness and the finish of the pile surface is improved. When the inclusion rate exceeds 10%, the base fabric becomes stiff, but up to 20% it can still be used in practical use and the pile surface has a good finish. However, when the inclusion rate exceeds 20%, the stiffness of the base fabric becomes extremely weak, wrinkles occur during tufting, and the finish of the pile surface is poor, making it unusable. Example 5 A tuft test was conducted using a foamed stretched tape yarn for the weft, a foamed stretched tape yarn and an unfoamed stretched tape yarn for the warp, and varying the density. The tufting conditions and results are shown in Table 5.

[Table] Supplementing Table 5, when the warp density is 24/inch, the tufting needles penetrate between the warp threads, but since the warp threads are thin, there is almost no needle runout, and therefore the pile density The pile surface is also uniform and the finish of the pile surface is good. As the warp density decreases, the warp threads become thicker and the width of needle runout becomes wider, resulting in uneven pile density and poor finish on the pile surface. When foamed stretched tape yarn is used, the tufting needle penetrates the yarn, so there is no needle runout and the pile surface has a good finish.

[Brief explanation of drawings]

Figures 1 and 2 are schematic cross-sectional views of tufted carpets made using conventional or inventive primary base fabrics (Figure 1 shows a loop type carpet, and Figure 2 shows a cut type carpet). ), Fig. 3 is a surface schematic diagram of a non-woven primary base fabric, Fig. 4 is a longitudinal cross-sectional view of a non-woven primary base fabric tufted with pile yarn, and Fig. 5 is a schematic diagram of the surface of a non-woven primary base fabric tufted with pile yarn. The plan view and FIG. 6 show a vertical cross-sectional view of a fabric base fabric tufted with pile yarn. In these drawings, the numbers represent the following: 1: loop type pile yarn, 1': cut type pile yarn, 2: primary base fabric, 3: latex, 4: secondary base fabric, 21: non-woven primary base fabric, 22: woven primary base fabric, 221: Warp, 22
2: Weft.

Claims (1)

[Scope of Claims] 1. A primary base fabric for tufted carpets woven from expanded polypropylene tape yarn having ellipsoidal cells and an inner cell ratio of 0.95 to 20%. 2. The primary base fabric for tufted carpets according to item 1, which is woven using ordinary stretched tape yarns as warp yarns and the foamed drawn polypropylene tape yarns described in item 1 as weft yarns. 3. The primary base fabric for tufted carpet according to item 1, which is woven using the foamed drawn polypropylene tape yarn described in item 1 for both the weft and warp.