JP2008007911A - Drier canvas for making paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drier canvas which maintains the advantages of a conventional drier canvas in which warps form a pair of front and back symmetrical constructions and a weft layer is a single layer, solves problems such as the warp fraying in selvage portions, the insufficient impregnation of a resin for imparting functions, difficult joint-joining works, and the breakage of warps due to high pressure washing water, and can improve drying efficiency in a high air ventilation degree. <P>SOLUTION: Circular or elliptic cross-sectional monofilaments are used as warps 10, 11, and spaces a are disposed in entangles portions with wefts 12, 14 so that the front side warp does not contact with the back side warp. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a papermaking dryer canvas used in a dry part of a papermaking machine, and more particularly to an improvement in a papermaking dryer canvas in which warps are composed of a pair of front and back symmetrical structures and a weft layer is a single layer.

  Papermaking dryer canvases (hereinafter referred to as canvases) are required to have various physical properties and functions such as suitable surface properties and appropriate air permeability, in addition to dimensional stability, running stability, moist heat resistance and heat resistance. In addition, a so-called warp loop joint is often used for the joints provided at both ends in the longitudinal direction (warp direction) of the canvas, in which the warp is folded back to form a loop and then the remaining warp is bound into the main body structure. In this case, it is necessary to design the fabric in consideration of the loop production efficiency and the strength and surface property of the joint part. It is necessary to take measures against ear damage and fraying due to contact with the hair.

  In recent years, with the trend toward higher productivity and higher speed of paper machines, the usage environment of canvas has become more severe, and a longer service life has been required than ever before.

  For example, a single run system in which wet paper is run with a canvas placed on only one side (for example, the upper part) of a paper machine, or a dryer cylinder on a single side of the upper or lower side of the paper machine. Wide-range and high-speed paper machines such as single-row dryers are widely used, and in this case, the wet speed increases as the canvas travels due to the difference in peripheral speed caused by the canvas thickness. In some cases, the tension applied to the paper is repeatedly tensioned and loosened to adversely affect the wet paper, and severe paper breakage may occur. For this reason, it is indispensable that the canvas is thin, particularly in the high-speed single run method, the bell run method, and the shim run method.

  In addition, the number of papermaking that requires a high quality level, such as high-quality paper and coating base paper, is increasing. In response, canvas has a high density of monofilament yarns with a flat cross-sectional shape for warp yarns, and long warp yarns. A floating structure is used, and the paper contact surface is smoothed to ensure good surface properties.

  On the other hand, changes in additives due to an increase in waste paper raw material usage in response to demands for resource saving and raw material cost changes are due to adhesive substances (such as gum pitch) contained in raw materials, and the size of paper paste As a result of the increase in liquid and coating chemicals, inorganic substances such as aluminum hydroxide and talc, etc., as a result, it becomes dirty and adheres to the canvas, resulting in paper sheet defects and significantly reduced canvas breathability. As a result, the drying capacity is lowered, and the canvas body is gradually worn and damaged. Therefore, there is an increasing need for improving the antifouling property, suitable cleaning properties, wear resistance and ease of maintenance of the canvas.

  In such a background, Patent Documents 1 and 2 are known as canvases in which the thickness of the canvas body is reduced and the surface smoothness is improved by using a flat cross-sectional monofilament yarn for the warp.

  In Patent Documents 1 and 2, the cross-sectional dimension ratio (hereinafter referred to as flatness) of warp yarns 10 and 11 shown in FIG. 4 is 2: 1 to 4: 1 (“cross-sectional width direction dimension: cross-sectional thickness direction dimension”). Paper base fabrics and woven belts for paper machines (hereinafter both referred to as canvases) using flat monofilaments (flat monofilament warps 20 as shown in FIG. 6). In this canvas, yarns 12 and 14 of two sizes, large and small, are alternately arranged to form a woven structure as shown in FIG. This canvas has a structure in which warp knuckles that are entangled with small wefts do not appear on the surface.

Since these canvases use a monofilament yarn having a wide cross section with high flatness for the warp and float it for a long time, increasing the density of the warp makes the paper contact surface very smooth. Further, when the joint is a warp loop joint, there is no factor of “twist or torsion moment”, and “a series of vertically stitched annular threads” is obtained, and a high-quality joint that closely resembles the structure of the main body is obtained. In addition, this structure is composed of warp yarns exposed only on the front surface side and warp yarns exposed only on the back surface side. For example, even if one surface of the canvas is worn and warp cutting is expanded in the canvas width direction, The warp of the surface remains, and as a canvas, it does not lead to full breakage, and the risk of a serious accident is considered to be extremely low. While having these advantages, it is possible to reduce the thickness of the canvas by using a single weft layer, so there are many parts that meet the papermaking needs described above, and the adoption of this canvas has increased. ing.
JP-T-5-509134 Japanese National Patent Publication No. 10-505138

  However, when the canvas of the above-mentioned patent document is adopted in various papermaking environments, problems due to its structure have come to the surface.

  The first problem is fraying of the warp of the canvas ear. In general, a synthetic fiber canvas is used to weld warps and wefts with a heated iron along the outermost warp of the ears to prevent fraying of the warp at the ears, and then bond the 2-5 cm width of the part over the entire length. A treatment to reinforce by coating the resin as the agent. In the resin coating, the flat yarn of the warp overlaps with the upper and lower parts and the part entangled with the weft has a woven structure in which each surface comes into contact, so the resin penetration into the part is bad, and the resin coating process is reversed. There is no choice but to cope with the increase in the number of processes, and it is still difficult to achieve complete penetration.

  As a second problem, the cause is common to the first problem in that functional resin is not sufficiently applied to the canvas body. In some cases, canvas may be subjected to additional processing to apply and infiltrate the body with functional resin such as antifouling, entanglement adhesion reinforcement, antistatic, etc. by dipping or kissing processing method. Due to this, there was a problem that the internal penetration did not occur, the processing man-hours were forced to increase, and the imparted resin function could not be sufficiently exhibited.

  As a third problem, the flat yarn configuration and structure are unsuitable as a canvas configuration having high air permeability. The canvas is a type of canvas in which warps with high flatness are arranged at high density and finished into a low air permeability type to exhibit high surface properties. In general, a basic structure having a wide air permeability adjustment range is ideal in the design of a canvas. However, especially when the canvas structure is intended to increase the air permeability, the warp flat yarn has a wide width so that it is adjacent. The gap between the warp and the weft will be greatly expanded. If it becomes such a form, even if ventilation | gas_flowing amount itself can be enlarged, a warp flat part will enlarge the permeation | transmission resistance of air (steam), and will disturb the flow of air (steam). In addition, the area that contacts the wet paper on the surface side of the canvas has a flat area because of the flat surface, and the paper contact area does not dissipate wet paper moisture on the dryer cylinder. For this reason, there was a problem that it was not preferable in terms of drying efficiency of wet paper.

  Furthermore, especially when the space between the wefts is widened, the span length for supporting the warp yarns becomes long, and in the contact pressure to the wet paper, only the portion of the weft yarn having the larger fineness, which becomes the fulcrum of the warp length floating portion, increases. On the other hand, there is a problem that the contact pressure becomes low or disappears due to insufficient rigidity due to the flat yarn at the center portion of the span, and uneven contact pressure occurs.

  The fourth problem is that there are many contaminants transferred to the wet paper. Since the contact area between the wet paper and the canvas is very wide due to the flat yarn configuration, dirt such as dirt substances contained in the raw materials and chemicals and scales in the travel route are likely to adhere to the canvas. When the dirt adheres to the canvas, there is a problem that it is easily transferred to the wet paper.

  As a fifth problem, there is a difficulty in joint joining work. When the warp loops of both ends are meshed and the common core wire is inserted, since the cross section of the loop is a flat shape, the insertion friction of the core wire is large. In particular, in the case of a wide canvas, the resistance increases too much during the insertion, which takes time and effort. In addition, in the case of a high air permeability type structure with a gap between the warp yarns, the loop interval is wide, and in actual work, the tip of the core wire hits the side of the loop or protrudes outside the loop, making the insertion work smooth There was a problem that could not be done.

  A sixth problem is that warp cracking occurs during ultra-high pressure cleaning. The canvas is subjected to high-pressure washing with jet water in order to remove contaminants in a relatively short period, but the washing pressure is often increased particularly in the above-described papermaking process in which the tendency to increase contaminants is strong. Flat warp monofilament yarns receive high-pressure water on a flat surface, and when the flatness is high and the yarn thickness is thin, there is a problem that cracking phenomenon such as tearing in the length direction often occurs due to inability to withstand washing pressure. .

  As described above, the canvases of Patent Documents 1 and 2, which are said to have a thin main body and have particularly good surface properties and meet recent papermaking needs, also have many weak points. The present invention provides a novel canvas that eliminates these weak points and can meet a wide range of papermaking needs in recent years.

  As a result of studies conducted by the inventors of the present invention to achieve the above-described prior art canvas, in the canvases of Patent Documents 1 and 2, the warp yarn has a cross-sectional shape without a straight portion, that is, a circular or elliptical shape. I came to the conclusion that if it can be achieved, it can be achieved. In other words, the ear reinforcement resin and the resin for imparting functionality to the main body can sufficiently penetrate between the front and back side warps and between the warps and wefts in one processing, especially in the ear reinforcement resin processing The warp and weft yarns are wrapped in resin one by one, and the anchor effect can be sufficiently exerted to remarkably improve the degree of reinforcement.

Further advantages of the canvas of the present invention are listed as follows.
-Since the surface of the warp is a curved surface, the resistance to air (steam) passage is smaller than that of a canvas using a flat yarn, and the flow is improved, and the drying efficiency is improved.
-Since the area in contact with the wet paper is reduced, the evaporated water is easily dissipated, and the drying efficiency is higher even with the same air permeability as that of the conventional canvas.
The point that the area that comes into contact with the wet paper becomes smaller is another effect that the area for transferring the contaminants attached to the canvas to the wet paper becomes smaller, and this also serves as a countermeasure against the wet paper.
-When a canvas with high air permeability is used, even when the weft interval is increased, the contact pressure unevenness to the wet paper does not easily occur and the surface property can be maintained.
・ Since the surface of the warp that becomes the warp loop is a curved surface, not only can the insertion resistance during joint joining be eliminated, it also has a shape that guides the tip of the core wire.
-Even if it continues to receive high-pressure washing water, the exposed warp surface is a curved surface and a certain thickness is secured at the center, so there is no risk of warp cracking in combination with the water pressure dispersion effect.

  As described above, it was considered that the present problems were solved and the subject of the present application could be achieved.

  Thus, trial fabrication was performed, but a stable woven structure in which monofilament yarns having a circular cross section used for warp could be stacked on the front and back sides could not be obtained. As a result of the investigation, it has been found that the warp on the surface side or the back surface side in the structure cannot be stably placed on the inner warp entangled with the weft having the smaller fineness. For this reason, warp yarns that float for a long time on the front side or the back side are shifted in the fabric width direction, or warp yarns that overlap on the inside and outside of the fabric cross each other. As a result, poor formation due to warp misalignment occurred on the entire surface of the fabric, resulting in a surface condition that could not be used as a canvas.

  The inventors have further studied the cause and repeated test weaving. As a result, in the structure, even when a monofilament yarn having a circular or elliptical cross section is used as the warp, the warp on the front side and the back side are close to each other. We succeeded in obtaining a structure that can be stably aligned vertically.

  As described in claim 1, the configuration is a weft monolayer fabric in which two types of wefts of large and small fineness wefts having different finenesses are alternately arranged one by one, and exposed on the surface of the fabric. The surface side warp that is not exposed on the back side of the fabric and the back side warp that is exposed on the back side of the fabric and not exposed on the fabric surface form a double warp that is double in the direction perpendicular to the front and back surfaces of the fabric. After entanglement with the wefts, the front side and the back side are floated by a total of three large fine wefts and one small fine weft, and the small fineness weft entanglement position is set to a predetermined number of warps in the fabric width direction. In a papermaking dryer canvas that is arranged while being alternately shifted in units, a monofilament yarn having a circular cross section is used for both the front and back warp yarns in at least a part of the width direction of the fabric, and the small fine weft yarns are interposed Two sandwiched between A gap (for example, “a” in FIGS. 1, 2B, and 3B) is interposed from a partner side warp that interlaces a portion where the surface side and back side warp is floated between the large fine wefts with an intermediate small fine weft. It is characterized by being separated.

  Here, the “fineness” is represented by “tex” in the case of a filament yarn, and “count” in the case of a spun yarn, and indicates a weight per unit length by a numerical value. In the case of monofilament yarn, if the cross-sectional shape is circular, it is a diameter, if it is an elliptical cross-section, the long and short diameters, and the flat cross section such as a square cross-section is a direct dimension such as the long and short sides or the width and thickness dimensions It may be expressed as

  The invention of claim 2 is the invention of claim 1, wherein monofilament yarns having a circular cross section are used as the large fine weft and the small fine weft, and the total value of the diameter of the warp and the diameter of the small fine weft is the large value. It is smaller than the diameter of the fine weft, the size of the woven crimp of the large fine weft is not more than 10% of the diameter of the weft, and the size of the woven crimp of the small fine weft is not less than the diameter of the weft. .

  Here, the size of the woven crimp is represented by a dimension from the top of the “mountain” to the bottom of the “valley” in the corrugation of the valley formed in the entangled portion of the yarn. In this specification, the dimension between the peaks and valleys in the center line of the yarn is defined as “the size of the woven crimp” (dimension “b” in FIG. 5).

  Further, the invention of claim 3 is a paper making dryer canvas using a monofilament warp having an elliptical cross section instead of a monofilament warp having a circular cross section on the front side and the back side of the paper making dryer canvas of claim 1. .

  The invention of claim 4 is the invention of claim 3, wherein monofilament yarns having a circular cross section are used as the large fine wefts and small fine wefts, and the elliptical minor axis of the monofilament warp having the elliptical cross section and the small fine wefts. The total value of the diameters is made smaller than the diameter of the high-definition weft, the size of the woven crimp of the large-fineness weft is 10% or less of the diameter of the weft, and the size of the woven crimp of the small-fineness weft is the diameter of the weft It is characterized by the above.

  The invention of claim 5 is characterized in that, in the inventions of claims 1 to 4, the front side warp and the back side warp are made of different materials.

  The invention of claim 6 is characterized in that, in the inventions of claims 1 to 5, two warps are aligned in parallel to the fabric surface.

  The invention of claim 7 is the invention of claims 1, 5-6, wherein a multifilament yarn or a spun yarn is used as the small-fineness weft, and the size of the woven crimp of the large-fineness weft is the woven fabric of the weft cross section. The size is 10% or less of the dimension in the thickness direction, and the size of the woven crimp of the small fine weft is not less than the apparent diameter of the weft.

  Here, the “apparent diameter” is a converted diameter when the yarn is assumed to be a monofilament yarn having a circular cross section, and is a value that can be calculated based on the fineness or count of the yarn and the specific gravity. The multifilament yarn is generally referred to by those skilled in the art, for example, in the form of a bundle of dozens or more of fine filaments of about 0.5 to 50 decitex, and in terms of the diameter of the yarn cross section, it is thinner than about 0.1 mmφ. A bundle of several to several tens of monofilament yarns and a form in which they are twisted are also included.

  The invention of claim 8 is the invention of claims 1 and 5-6, wherein a monofilament yarn having a flat cross section is used as the small fine weft, and the size of the woven crimp of the large fine weft is determined by the fabric thickness of the weft cross section. The size of the weft crimp is not more than 10% of the dimension in the length direction, and the size of the woven crimp of the small fine weft is not less than the dimension in the fabric thickness direction of the weft cross section.

  The invention of claim 9 is the invention of claims 1 to 8, in which the paper making dryer canvas of claim 1 is configured on both sides or one side of the fabric width direction, and the surface of the other fabric portions is the surface. A monofilament yarn having a flat cross section is used for both the side and back side warps.

  When the joint is a warp loop seam, the loop is not twisted or twisted, and is aligned vertically, so that a high-quality seam that extends the surface property of the main body is obtained. Further, even if one surface of the canvas is worn and warp cutting is expanded in the canvas width direction, the canvas does not completely break. Furthermore, high quality and precise surface properties can be obtained by arranging warps at high density. While maintaining the advantages of the conventional configuration, the ear reinforcement resin processing and the functional resin processing can be performed easily and sufficiently, and the high air permeability and the air (steam) flow are not disturbed. The flow path becomes wider and the wet paper can be efficiently dried. In addition, the transfer of contamination to the wet paper is reduced, the core wire insertion work at the time of joint joining is facilitated, and a canvas that can sufficiently withstand the jet water washing without being broken is obtained.

  The canvas of the present application uses a monofilament yarn having a straight portion in its cross-sectional shape, that is, a circular or elliptical shape, in at least a part in the width direction. The explanation is based on the assumption that monofilament yarn with a cross-section is used. Prototypes that have led to the present invention have also been implemented with this assumed configuration.

  First, a canvas fabric structure, for example, in a paper machine including a single-row dryer cylinder, it is desirable that the canvas is thin, so that the monofilament yarn having a circular or elliptical cross section is likely to be thick. Is considered to be used for warp, it is desirable that the weft layer is a single layer.

  However, as described above, if a structure using a circular cross-section yarn or an elliptical cross-section yarn as the warp in the structure cannot be stably realized, use as a canvas structure must be abandoned.

  Therefore, when the cause of the formation failure due to the warp misalignment was investigated, the circular or elliptical cross-sectional yarn used for the front side warp and the back side warp that are close to each other on the front and back sides does not have a flat part on the yarn surface. In this state, point warping or line contact is caused, and the inner warp that is in contact with the long-floating side warp is pressed, and the tissue balance is lost and the warp is shifted in the canvas width direction. This deviation was various and not constant, such as when the front side warp was shifted, when the back side warp was shifted, or when both warps were shifted.

  The warp yarns must be linearly aligned over the entire length at a pitch defined in the width direction of the fabric. Particularly when a monofilament yarn having a circular or elliptical cross section is used as the warp yarn in this structure, the pair of front and back surfaces described above are used. The warp yarn must be structured so that stresses that affect each other do not work.

  From this investigation, in order to obtain a woven fabric having no warp deviation, it is conceivable to separate the warp yarns on the front side and the back side so as not to come into contact with each other, or to secure the position of each warp. Therefore, first, a combination of finenesses was considered so that the front side warp and the back side warp were separated from each other over the entire length, and the space was surely taken so that they would not come into contact with each other in the proximity part, that is, the entangled part with the small fineness weft.

  First, it is preferable that the dimension in the fabric thickness direction of the cross section of the front side warp and the back side warp is substantially the same. Thereby, the front-and-back balance of the fabric structure can be maintained, and the voids in the present invention can be easily secured. Furthermore, when we use multifilament yarns, spun yarns, and monofilament yarns with a circular cross-section that are harder to crimp than flat-filament monofilament yarns as weft yarns, the sum of the diameters of the warp yarns and the weft yarns with the smaller fineness is the largest. It has been found that it is necessary to make the diameter smaller than the diameter of the weft.

  That is, if this condition is not satisfied, the inner warp entangled with the small fine wefts will protrude from either side of the front and back with the gap portion filled, and if both the front and back sides need to be smooth surfaces, It becomes impossible to maintain the smooth surface.

  Next, with respect to a method for ensuring the position fixing of the warp, it is presumed that the warp can be more reliably fixed if a sufficient crimp is applied to the weft after preventing the warp from contacting each other as described above. In order to sufficiently crimp the weft, a soft material such as a material having a small initial elastic modulus may be selected for the weft.

  However, if the high-definition weft is made of a soft material, the long floating position of the front side warp sinks toward the inner side of the fabric, the front and back warps come into contact, and the front side warp presses the back side warp. For this reason, it has been found that it is better to generate only a large amount of crimps only in the small fine wefts and not to crimp the large fine wefts. Even when a high-definition weft is crimped as a result, a hard material such as a material having a large initial elastic modulus is used for a high-definition weft so that at least the crimp does not exceed 10% of the dimension in the fabric thickness direction of the large-fineness weft. Decided to select.

  A soft material or a hard material can be easily obtained by adjusting the yarn composition. Further, as a soft material, a multifilament yarn, a spun yarn, and a flat yarn having a small thickness have been confirmed, and can be suitably used.

  Further, it was also found that when the size of the crimp of the small-fineness weft is not less than the dimension of the yarn cross section in the fabric thickness direction, the void portion can be formed particularly stably. If the size of the crimp is less than the dimension value of the yarn in the fabric thickness direction, depending on the fineness and firmness of the warp, it becomes gradually difficult to fix the warp at a regular pitch, and the warp misalignment is likely to occur. Become.

  The weaving was attempted by changing the warp yarn size from a monofilament yarn with a circular cross section to a monofilament yarn with an oval cross section after making the size of the crimp of the small fineness weft more than the dimension in the thickness direction of the fabric. It was also found that the canvas configuration initially assumed by the conditions was feasible.

  In this way, by providing a gap between the front side warp and the back side warp adjacent parts without contacting both warps, the pair of front and back warps is stable even in a position perpendicular to the fabric front and back. Thus, the canvas structure of the present invention can be manufactured.

  In this configuration, the pair of surface side warp and back layer side warp are separated over the entire length, but this is a structure on the main body structure, and in the joint part for creating the above-mentioned warp seam loop, Of these, one warp is bound into the other warp tissue system and the respective warp tips are butted against each other.

  FIG. 1 shows a conceptual diagram of a longitudinal section of the canvas of the present invention. AA is a vertical cut line including the center of the large fine weft, and BB is a vertical cut line including the center of the small fine weft. A conceptual cross-sectional view along each cutting line is shown in FIGS. 2 (A) and 2 (B). The small fineness weft is positioned above or below the axis ZZ at the center of the fabric thickness. This is because the weft 12 having the smaller fineness is relatively easily crimped by the entanglement with the warps 10 and 11, and is pushed out to the side opposite to the warp entanglement side.

  2A and 2B are conceptual diagrams of a cross section in the canvas width direction, and AA and BB are as described above. The small fineness weft 12 is greatly crimped, and the large fineness weft 14 is hardly crimped even at the entangled portion of the warp. As a result, a certain gap portion a can be ensured at a location where the front and back warps are close to each other.

  FIG. 4 is a conceptual diagram of a cross section in the canvas length direction of the prior art included in the above-mentioned patent document, but there is no gap in the portion where the front and back warp yarns are close to each other, that is, between the warp yarns in complete contact. Even if stress is generated, the warp surface does not occur because the surface of the warp is flat and the surface comes into contact between the inner and outer warps and stabilizes. Therefore, in this case, there is no need to consider securing the gap.

  Next, it was proved by the trial weaving that it is possible to use a plurality of aligned yarns as warp yarns as long as the conditions for providing a gap in the proximity between the pair of warp yarns are prepared.

  FIGS. 3A and 3B are conceptual cross-sectional views in the canvas width direction when two circular cross-sectional yarns are aligned and used as warp yarns 10 and 11. Even when warp yarns are aligned in parallel to the fabric surface, a space a is secured as in the case of using single yarns without alignment in FIGS. 2A and 2B, and a stable canvas. It turned out that it can be made into a structure.

  With such an arrangement of warp warps, the number of crimps of wefts can be reduced, the warp density can be increased, surface properties can be improved, and low permeability of the canvas can be easily achieved. Further, when a multifilament yarn, a spun yarn, or a wide flat yarn is used as the small-fine weft, the canvas can be further reduced in air permeability. Therefore, the canvas can be designed with a wide air permeability adjustment range.

  As shown in FIG. 1, in the canvas structure using the front side warp exposed on the fabric surface and not exposed on the fabric back surface and the back side warp exposed on the fabric back surface and not exposed on the fabric surface, the material of the front side warp and the back side warp By changing the above, a canvas having different functions on both sides can be obtained. For example, when polyphenylene sulfide is selected as the material for the front side and polyester is selected for the back side, it is possible to arrange an appropriate amount of fibers that are highly functional but expensive as in the former material.

  Further, as described above, the configuration of the present invention is effective for reinforcing the resin at the ear portion of the canvas. If the paper making process requires extremely smooth surface properties and the ears must be sufficiently reinforced, only a part of the entire width including the ears is used. A monofilament warp 20 having a flat cross section as shown in FIG. 6 may be used at the center of the canvas in contact with the wet paper. It should be noted that the reinforcement of the ear part may be necessary only for one side ear part and the both side ear part, but when only one side ear part may be reinforced, the other ear part warp has a circular cross section, an elliptical cross section, It may be a monofilament yarn having any cross-sectional shape of a flat cross section.

Table 1 shows five examples of the configuration of the present invention. Numerical data below the density is a numerical value after weaving and applying a predetermined heat set. All yarn materials used are polyester.


(Note 1) Thick weft: large fine weft, thin weft: small fine weft (Note 2) The warp density is indicated as “× 2” because it has a front side and a back side.
(Note 3) When the warp is a double-drawn yarn, “(× 2)” is indicated.
(Note 4) Air permeability conforms to Method A (Fragile Form Method) of JIS L 1096 General Textile Test Method.

Comparative example

Table 2 shows five comparative examples of the present invention. Numerical data below the density is a numerical value after weaving and applying a predetermined heat set. All yarn materials used are polyester. In any example, the woven structure is the structure described in Patent Document 1 described in the present specification (see FIG. 4). Comparative Examples 1 to 3 are examples in which the warp is a monofilament yarn having a flat cross section, and Comparative Examples 4 to 5 are the initial trial production stage of the present invention, where the front side warp and the back side warp are in contact with each other (gap portion length a = 0), which is an example in which the warp arrangement is disturbed and the surface texture is poor.


(Note 1) Thick weft: large fine weft, thin weft: small fine weft (Note 2) The warp density is indicated as “× 2” because it has a front side and a back side.
(Note 3) Air permeability conforms to JIS L 1096 General Textile Test Method A Method (Fragile Form Method).

Comparison of surface properties (Example 3 and Comparative Example 1)
Next, FIG. 7 shows the results of collecting transfer marks on the canvas surfaces of Example 3 and Comparative Example 1 having substantially the same air permeability in order to evaluate the paper contact state on the canvas surface. The method and procedure for collecting the transfer mark is as follows.
1) Place the pressure measurement film on the surface of the test sample of the dryer canvas,
2) The test sample and the film are sandwiched between jigs attached to the above-mentioned universal material testing machine,
3) Pressurize to color the pressure sensitive part of the film,
4) Collect the transfer mark on the surface of the dryer canvas.
The pressure measurement film was manufactured by Fuji Photo Film, Fuji Prescale (LLW), and was pressurized for 30 seconds under 2.3 MPa.

  In the case of this comparative test, each transfer point of the transfer mark is a long floating portion of the warp. According to this result, in Example 3, the transfer points of the two warp yarns aligned are combined by the transfer pressure. However, it is uniformly transferred as a whole and is uniformly dispersed.

  On the other hand, the transfer point of Comparative Example 1 is marked strongly at the portion of the long float portion of the warp that intersects the weft with the higher fineness, and the center of the long float portion has a thin mark and uneven contact pressure. It can be confirmed that a large amount of is generated.

  When the cross section of the warp is circular or elliptical as in Example 3, the shape increases in thickness toward the center of the cross section, and thus when supported at two fulcrums rather than a thin flat yarn Tends to have high bending rigidity. For this reason, in Example 3, it can be inferred that the entire long floating portion is uniformly transferred.

This tendency of difference in transfer marks is also observed in a canvas having a permeability of 10,000 cc / min · cm ^2. When designing such a high permeability canvas, a monofilament yarn having a circular or elliptical cross section is used as a warp. This superiority was also demonstrated in terms of surface properties.

The conceptual sectional view of the length direction section of the dryer canvas for papermaking concerning the present invention. AA sectional drawing of FIG. BB sectional drawing of FIG. Sectional drawing similar to FIG. 2A in the modification of the dryer canvas for papermaking which concerns on this invention. Sectional drawing similar to FIG. 2B in the modification of the dryer canvas for papermaking which concerns on this invention. The conceptual cross section of the length direction cross section of the conventional dryer canvas for papermaking. Fig. 3 is a cross-sectional view of the weft crimp of the weft crimp in the yarn length direction. An exemplary cross-sectional view of a flat yarn. The transfer mark of the canvas of Example 3. The transfer mark of the canvas of the comparative example 1.

Explanation of symbols

10 Front-side warp 11 Back-side warp 12 Small fine weft 14 Large fine weft

Claims (9)

  A weft monolayer fabric in which two types of wefts, large and small wefts of different fineness, are alternately arranged one by one, on the surface side warp that is exposed on the fabric surface and not on the fabric back surface, and on the fabric back surface The back side warp that is exposed and not exposed on the fabric surface forms a double warp that is doubled in the vertical direction on the front and back surfaces of the fabric, and after the double warp is entangled with the small-fine weft, the front side and the back side respectively. In a dryer canvas for papermaking, which floats for a total of three large fine weft yarns and one small fine weft yarn, and is arranged while alternately shifting the small fine weft entanglement positions by a predetermined number of warps in the fabric width direction. A monofilament yarn having a circular cross section is used for both the front side and the back side in at least a part of the fabric width direction, and the front side and the two sides of the large fine wefts sandwiched between the small fine wefts Back side Papermaking drier canvas, characterized in that the yarn has moved away by interposing the air gap from the other side warp confounding portions in the middle of the small fineness weft long float.   A monofilament yarn having a circular cross section is used for the large fine weft and the small fine weft, the total value of the diameter of the warp and the small fine weft is smaller than the diameter of the large fine weft, and the weaving crimp of the large fine weft 2. The dryer canvas for papermaking according to claim 1, wherein the size is set to 10% or less of the weft diameter, and the size of the woven crimp of the small-fine weft is set to the weft diameter or more.   A paper making dryer canvas using a monofilament warp having an elliptical cross section instead of the monofilament warp having a circular cross section on the front and back sides of the paper making dryer canvas according to claim 1.   A monofilament yarn having a circular cross section is used for the large fine weft and the small fine weft, and the total value of the ellipse minor axis of the monofilament warp having the elliptical cross section and the diameter of the small fine weft is smaller than the diameter of the large fine weft, 4. The papermaking machine according to claim 3, wherein the size of the woven crimp of the large fineness weft is 10% or less of the weft diameter, and the size of the woven crimp of the small fineness weft is not less than the weft diameter. Dryer canvas.   The paper dryer drier canvas according to any one of claims 1 to 4, wherein the front side warp and the back side warp are made of different materials.   The paper warp dryer dryer according to any one of claims 1 to 5, wherein the warp yarns are two aligned in parallel to the fabric surface.   A multifilament yarn or spun yarn is used as the small fine weft, and the size of the woven crimp of the large fine weft is 10% or less of the dimension in the fabric thickness direction of the weft cross section, and the size of the woven crimp of the small fine weft The paper making dryer canvas according to any one of claims 1 and 5 to 6, wherein the diameter is equal to or larger than the apparent diameter of the weft.   A monofilament yarn having a flat cross section is used as the small fine weft, the size of the woven crimp of the large fine weft is 10% or less of the dimension in the fabric thickness direction of the weft cross section, and the size of the woven crimp of the small fine weft is The paper dryer drier canvas according to any one of claims 1 to 5, wherein the weft cross-sectional dimension is not less than the dimension in the fabric thickness direction.   The structure of the paper making dryer canvas according to claim 1 is used on both sides or one side of the fabric width direction, and monofilament yarns having a flat cross section are used for both the front and back warps in the other fabric portions. The paper making dryer canvas according to any one of claims 1 to 8.