Flow pass material for ro

Abstract

To secure and provide a flow pass material for RO having many flow passages more than a warp knitting or a round knitting single unit.SOLUTION: A flow passage material for RO of the present invention is formed by using a double unit round knitting texture.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an RO flow path material using a double knit circular knit fabric. [Background technology]

[0002] Traditionally, the flow path material for RO modules has mainly been warp knitted fabric. In recent years, the demand for RO modules has increased due to water shortages, and there is a demand for more efficient production of flow channel materials to reduce costs. While several hundred warp threads are required to manufacture warp knitted fabrics, circular knitting can be made with just a few dozen threads, and if circular knitting could be developed that functions as a flow channel material in the same way as warp knitted fabrics, it would lead to a significant improvement in productivity. However, because circular knitted fabrics have a greater degree of freedom in both the warp and weft directions than warp knitted fabrics, it is difficult to control the density and thickness, and so there has not been much thought given to using it as a flow path material. Furthermore, in the course of developing RO flow channel materials, it became clear that circular knitting was superior to warp knitting in terms of securing space. With warp knitting, the flow channels (air space) are limited to the grooves, but with circular knitting, due to its structure, there is also air space within the ridges (ridges), so more space can be secured than with warp knitting. Therefore, the development of circular knitted channel material is expected to improve water production efficiency compared to the use of warp knitted channel material, and is thought to contribute to efficient production as well as obtaining the cheapest possible water, making it a major measure to prepare for the worsening water shortage.

[0003] By the way, a prior document regarding a circular knitted fabric channel material is Patent Document 1. The channel material in Patent Document 1 is characterized by an alternating arrangement of linear grooves and linear ridges, and the ridges are not considered as channels. In addition, a sinker knitting machine (single knit knitting machine) is used, which makes it difficult to secure a large space. Similarly, the flow path material in Patent Document 2 also uses a single knit, making it difficult to secure a large space. It is possible to consider using the ridges of circular single knit fabric as flow paths, but in order to use the ridges as flow paths, the height of the ridges needs to be increased. Simply making the ridges higher would result in them collapsing when high pressure is applied, making them unusable as flow paths. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2007 / 114069 [Patent Document 2] JP 2009-74214 A Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the problems associated with the above-mentioned conventional techniques, an object of the present invention is to secure and provide a flow path material for RO having more flow paths (spaces) than warp knitting or circular single knitting. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention has any one of the following configurations. (1) RO flow channel material made of double knit circular fabric. (2) The RO flow path material according to (1), having a void ratio calculated by the following formula of 55% or more and 90% or less. Void ratio = (1-1cm of double knit circular knit fabric) 3 (Volume per unit) x 100 1cm 3 The volume per unit is 1cm 3 This is the total weight of the double knit circular knit fabric divided by the specific gravity of the resin fiber used. (3) The RO flow path material according to (1) or (2), which has a thickness of 100 to 400 μm. (4) The circular knit fabric according to any one of (1) to (3), wherein the double knit circular knit fabric has a structure of smooth (interlock), mock rody, ponte roma, rib (one by one rib), or Milano rib. (5) The RO flow path material according to any one of (1) to (4), wherein the knitting yarn constituting the double knit circular knit fabric is a synthetic fiber. (6) The RO flow path material according to (5) above, wherein the synthetic fiber is a core-sheath structure yarn having a high melting point component as the core and a low melting point component as the sheath, a mixed yarn using a high melting point component yarn and a low melting point component yarn, or a cross-knitted yarn. (7) The RO flow path material according to (5) or (6), wherein the synthetic fiber is polyester. (8) The circular knitted fabric according to (7) above, wherein the polyester fibers have a total fineness of 10 to 180 dtex. (9) The RO flow path material according to any one of (1) to (8), having a wale (number of stitches in the width direction) density of 35 to 80 / 2.54 cm. (10) The RO flow path material according to any one of (1) to (9), which is obtained by heat-setting the double knit circular knitted fabric. (11) An RO module incorporating the RO flow path material according to any one of (1) to (10) above. Effect of the Invention

[0007] According to the present invention, an RO flow path material having more flow paths than warp knitting or circular single knitting can be secured and provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic plan view of an RO flow path material of the present invention. [Diagram 2] FIG. 2 is an enlarged side view of the RO flow path material of FIG. [Diagram 3] FIG. 3 is a schematic diagram of an RO element using the RO flow path material of FIG. [Figure 4] FIG. 4 is a schematic diagram of an RO element using conventional circular single knit flowpath material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The RO (reverse osmosis membrane) flow path material according to the present invention is made of a double knit circular knit fabric. FIG. 1 is a schematic plan view of the RO flow path material 1 according to the present invention, and FIG. 2 is an enlarged side view of the RO flow path material 1. The RO flow path material 1 has a structure in which columnar protrusions 11a and 11b protrude regularly from both sides of the ground texture 10. Since the RO flow path material 1 according to the present invention is a double knit circular knit fabric, it has a structure in which the protrusions 11a protrude from one side of the ground texture 10 and the protrusions 11b protrude from the other side. FIG. 3 is a schematic diagram of an RO element 100 using the RO flow path material 1 of FIG. 1. The RO element 100 has a structure in which the RO flow path material 1 is sandwiched between reverse osmosis membranes 20 from both sides. The RO flow path material 1 has protrusions 11a and 11b on both sides, and the spaces other than the protrusions 11a and 11b on both sides of the ground texture 10 can be used as flow paths.

[0010] FIG. 4 is a schematic diagram of an RO element 100A using a conventional circular knit single knit flow channel material. The circular knit single knit flow channel material has a structure in which multiple linear peaks 11A protrude from one side of the ground fabric 10A. The structure of an RO element using a warp knit flow channel material is substantially the same as that of the RO element 100A. When a circular knit single knit or warp knit is used as the knitted fabric, in order to obtain a high void ratio, it is considered to increase the height of the peaks 11A or increase the interval between the peaks 11A. However, simply increasing the height of the peaks 11A or increasing the interval between the peaks 11A may result in insufficient pressure resistance. In addition, warp knitting and circular knitting single knit have a structure in which the ridges 11A are formed only on one side, and the reverse osmosis membrane is supported linearly by the ridges 11A, and the flow path is mainly limited to the grooves between the ridges 11A, whereas the double knit circular knit fabric used in the present invention has a structure in which the protrusions 11a and 11b are formed on both sides, and the reverse osmosis membrane is supported by the apexes of the protrusions 11a and 11b, making it easier to ensure flow path space, and by appropriately designing the distance between the protrusions 11a (or 11b), it is possible to prevent the reverse osmosis membrane from collapsing and further increase the amount of water produced. Furthermore, circular knitting single knits are structurally thin, so it is difficult to create flow path space, and in order to achieve the same thickness as double knit circular knit fabrics, it is necessary to increase the fineness, but if the fineness is increased, the mesh will not be dense, and there is a concern that the mesh will open, causing problems such as the collapse of the reverse osmosis membrane. In addition, double knit circular knit fabrics have the advantages of being less prone to curling than single knit fabrics, having high tensile tear strength, and a higher void ratio. In particular, increasing the void ratio can be said to enable a greater water flow rate with the same thickness.

[0011] The RO flow path material of the present invention preferably has a void ratio of 55% or more and 90% or less. If the void ratio is less than 55%, the flow path (space) to be secured may be insufficient, and if it exceeds 90%, it becomes difficult to maintain the strength of the knitted fabric. The void ratio is a value calculated by the following formula. Void ratio = (1-1cm of double knit circular knit fabric) 3 (Volume per unit) x 100 1cm 3 The volume per unit is 1cm3 This is the total weight of the double knit circular knit fabric divided by the specific gravity of the resin fiber used.

[0012] The thickness of the RO flow path material of the present invention is preferably 100 to 400 μm. If it is too thin, the pressure resistance as a flow path material is insufficient, and if it is too thick, it is difficult to incorporate it into an RO module.

[0013] The double knit circular knit fabric used in the RO flow path material of the present invention may have any of smooth (also called interlock), mock rody, punch roma, rib (also called one-by-one rib), Milano rib, etc. The yarn constituting the double knit circular knit fabric used in the RO flow path material of the present invention is preferably made of a synthetic fiber, since most synthetic fibers are water-insoluble.

[0014] Examples of fibers constituting the double knit circular knit fabric of the present invention include polyamide fibers such as nylon 6 and nylon 66, polyester fibers, polyacrylonitrile fibers, polyolefin fibers such as polyethylene and polypropylene, polyvinyl chloride fibers, and fibers using biodegradable resins such as polylactic acid. Polyester fibers are preferably used because they have sufficient strength to prevent thread breakage during manufacturing processes such as knitting and post-processing, and they do not leach out much during extraction. Polyester fibers are basically polycondensates of polycarboxylic acids and polyalcohols, and specific examples include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyhydroxybutyrate, polycaprolactone, polylactic acid, and polybutylene succinate, but are not limited to these polyesters. In addition, the cross-sectional shape of the single fiber unit is not specified, and various irregular cross-sectional yarns such as round, triangular, eight-lobed, flat, and Y-shaped can be used. In addition, core-sheath or side-by-side composite yarns or mixed yarns made of different types of polymers, for example, polymers with different viscosities, can also be used. Furthermore, false twist textured yarns obtained by subjecting these raw yarns to false twist texture may also be used.

[0015] In the above synthetic fibers, it is preferable to use a core-sheath structure yarn with a high melting point component as the core and a low melting point component as the sheath, or to mix or cross-knit using a high melting point component yarn and a low melting point component yarn. The reason for this is that after knitting, the low melting point component is heat-set to melt once and penetrate between the high melting point components, and when cooled and solidified, it becomes a monofilament, which gives rigidity to the fabric, makes it difficult to be crushed by the RO operating pressure, and ensures a stable flow path.

[0016] The total fineness of the knitting yarn used in the double knit circular knit fabric is desirably 10 to 180 Dtex. If it is less than 10 Dtex, it is difficult to maintain the strength of the knitted fabric, and if it exceeds 180 Dtex, it is difficult to ensure a flow path. The total fineness of the knitting yarn is preferably 20 to 90 Dtex, and more preferably 30 to 80 Dtex. The knitting yarn is preferably a multifilament, and a part of the warp or weft may be replaced with nanofilament.

[0017] The wale density of double knit circular fabric is preferably 35 / 2.54cm or more and 80 / 2.54cm or less. If the wale density is less than 35 / 2.54cm, the RO flow path material will be too sparse, making it difficult to maintain the strength of the knitted fabric, and the pitch of the protrusions supporting the reverse osmosis membrane will be wide, raising concerns about the reverse osmosis membrane sagging. On the other hand, if the wale density exceeds 80 / 2.54cm, the knitting yarn will be thin and the fabric will be thin, similarly making it difficult to maintain the strength of the knitted fabric. In addition, the course density is preferably 25 / 2.54 cm or more and 65 / 2.54 cm or less. The RO flow path material of the present invention can be made into an RO module by stacking the RO membrane and a flow path material on the feed water side, such as a mesh, and incorporating the rolled up material into a cylindrical case. It can be used as an RO module that supports the water pressure on the RO membrane from the permeate side of the membrane, has a large amount of flow path space for the filtered liquid to flow, and can obtain a sufficient amount of water flow. EXAMPLES

[0018] Examples and Comparative Examples of the present invention will now be described in detail, but the present invention is not limited thereto. Each measurement item was measured and evaluated by the following methods. (1) Wales and courses: Measured with a densitometer. (2) Thickness: Measured with a micrometer. (3) Weight: Measured using an electronic scale. (4) Space ratio: Void ratio = (1-1cm of double knit circular knit fabric) 3 (Volume per volume) x 100 1cm 3 The volume per unit is 1cm 3 This is the total weight of the double knit circular knit fabric divided by the specific gravity of the resin fiber used. (5) Amount of permeated water: RO membrane (Flux=1.3m during standard measurement 3 / m 2 The raw water side flow passage material mesh and the permeate side flow passage material of the present invention were layered and rolled into a cylindrical shape to prepare an RO module with a diameter of 50 mm and a length of 300 mm. Flux (m2) at a constant operating pressure was measured using purified water at 25°C that had been previously filtered through a reverse osmosis membrane. 3 / (m 2 ·d)) was measured. (6) Evaluation of RO membrane drop In the flow test, RO membranes that showed little sagging were marked with an O, and those that showed a lot of sagging were marked with an X.

[0019] [Example 1] Polyester filaments of 56T, consisting of a core of high melting point polyester (melting point: 255°C) and a sheath of low melting point polyester (melting point: 229°C), were knitted in a 42-gauge smooth (interlock) weave and heat-set at 245°C to obtain a double-knit circular knit fabric with 43.5 threads / 2.54 cm, 65 threads / 2.54 cm wale, 208 μm wall thickness, and void ratio of 63.4%. This double-knit circular knit fabric was used as the RO flow path material and incorporated into a cylindrical case together with an RO membrane and a mesh-like feed water side flow path material. In a water flow test after assembly, the RO module adequately supported the water pressure applied to the RO membrane from the permeation side of the membrane, and cross-sectional observation after the water flow test showed that the RO membrane did not sag much and flow path space was secured, with a permeation rate of 4.8 (m) under an operating pressure of 8 MPa. 3 / (m 2 ·d)) Abundant water flow was obtained.

[0020] [Example 2] Two polyester filaments, one with only a low melting point of 22T (melting point: 229°C) and the other with only a high melting point of 22T (melting point: 255°C), were knitted together in a 40-gauge mock rody weave and heat-set at 245°C to obtain a double-knit circular fabric with 65 courses / 2.54 cm, 59 wales / 2.54 cm, a wall thickness of 195 μm, and a void ratio of 70.4%. In a water flow test after assembly, the RO module incorporating this double-knit circular fabric showed little sagging of the RO membrane, ensuring sufficient flow path space, and a permeate rate of 4.7 (m) at an operating pressure of 8 MPa. 3 / (m 2 ·d)) Abundant water flow was obtained.

[0021] [Example 3] A 40-gauge smooth (interlocked structure) was knitted from 56T core polyester filaments with a high melting point (melting point: 255°C) and sheath with a low melting point (melting point: 229°C) and set at 245°C to obtain a double-knit circular fabric with 47 courses / 2.54 cm, 65 wales / 2.54 cm, a wall thickness of 214 μm, and a void ratio of 63.6%. The RO module incorporating this double-knit circular fabric showed minimal RO membrane sagging in a flow test after assembly, and had a permeation rate of 4.8 (m) at an operating pressure of 8 MPa. 3 / (m2 ·d)) Abundant water flow was obtained.

[0022] [Comparative Example 1] The 56T core was made of polyester filaments with a high melting point (melting point: 255°C) and a low melting point (melting point: 229°C) sheath, knitted in a 36-gauge tricot weave and set at 245°C to obtain a warp-knitted fabric with 53 courses / 2.54 cm, 59 wales / 2.54 cm, a wall thickness of 203 μm, and a void ratio of 48.1%. The RO module incorporating this warp-knitted fabric showed little sagging of the RO membrane in a water flow test after assembly, but the void ratio was insufficient, and the water flow rate was 3.1 (m 3 ) at an operating pressure of 8 MPa. 3 / (m 2 ·d)), which was slightly lower than in Examples 1 to 3.

[0023] [Comparative Example 2] A 46-gauge plain weave was knitted from 56T core polyester filaments with a high melting point (melting point: 255°C) and sheath polyester filaments with a low melting point (melting point: 229°C) and set at 245°C to obtain a single-knit circular knit fabric with 110 threads / 2.54 cm, 65 wales / 2.54 cm, a wall thickness of 150 μm, and a void ratio of 60.3%. The RO module incorporating this single-knit circular knit fabric showed a large drop in the RO membrane in a water flow test after assembly, and the water flow rate was 3.2 (m 3 ) at an operating pressure of 8 MPa. 3 / (m 2 ·d)), which was slightly lower than in Examples 1 to 3.

[0024] [Comparative Example 3] A 46-gauge plain weave was knitted from 110T core polyester filaments with a high melting point (melting point: 255°C) and sheath polyester filaments with a low melting point (melting point: 229°C) and set at 245°C to obtain a single-knit circular knit fabric with 72 courses / 2.54 cm, 65 wales / 2.54 cm, a wall thickness of 222 μm, and a void ratio of 52.6%. The RO module incorporating this single-knit circular knit fabric showed a lot of RO membrane sagging in the water flow test after assembly, and the void ratio was also insufficient, resulting in a water flow rate of 2.0 (m 2 ) at an operating pressure of 8 MPa. 3 / (m 2 ·d)), which was less than in Examples 1 to 3.

[0025] The configurations and results of the above-described examples and comparative examples are summarized in Table 1. [Table 1] [Explanation of symbols]

[0026] 1 Channel material for RO 10, 10A ground organization 11a, 11b protrusion 11A Mountain 20 Reverse osmosis membrane 100, 100A RO element

Claims

1. A flow path material for RO using a double knit circular knit fabric having columnar protrusions on both sides of the base fabric.

2. The RO flow path material according to claim 1, wherein the void ratio calculated by the following formula is 55% or more and 90% or less. Space ratio = (1 - 1 cm of double knit circular knit fabric) ３ (Volume per unit) x 100 1 cm ３ The volume per 1 cm ３ This is the total weight of the double knit circular knit fabric divided by the specific gravity of the resin fiber used.

3. The RO flow path material according to claim 1 or 2, having a thickness of 100 to 400 μm.

4. 3. The RO channel material according to claim 1, wherein the double knit circular knit fabric has a structure selected from the group consisting of smooth (interlock), mock rody, punch roma, rib (one-by-one rib), and Milano rib.

5. 3. The RO channel material according to claim 1, wherein the knitting yarn constituting the double knit circular knit fabric is a synthetic fiber.

6. The RO channel material according to claim 5, characterized in that the synthetic fiber is a core-sheath structure yarn having a high melting point component as the core and a low melting point component as the sheath, a mixed yarn using a high melting point component yarn and a low melting point component yarn, or a cross-knitted yarn.

7. The RO flow path material according to claim 5, wherein the synthetic fiber is polyester.

8. The RO flow path material according to claim 7, wherein the polyester fibers have a total fineness of 10 to 180 Dtex.

9. 3. The RO channel material according to claim 1, wherein the wale density (the number of stitches in the width direction) is 35 / 2.54 cm or more and 80 / 2.54 cm or less.

10. The RO channel material according to claim 6, which is obtained by heat-setting the double knit circular knit fabric.

11. An RO module incorporating the RO flow path material according to claim 1 or 2.

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