Papermaking felt

Abstract

To provide a papermaking felt that can suitably enjoy the benefits of resin processing while improving penetration characteristics in paper machines.SOLUTION: A papermaking felt 1 of the present invention is coated with a polyurethane resin 19 and is also provided with a softener. A weight ratio of the softener to the polyurethane resin (softener adhesion amount per unit area of felt / polyurethane resin adhesion amount per unit area of felt) falls within the range of 0.024 to 0.090.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a papermaking felt for use in the press part of a papermaking machine. [Background technology]

[0002] Papermaking felts are used in the press part of a papermaking machine when wet paper is pressed between a pair of press rolls to squeeze out water from the wet paper and smooth its surface by passing the wet paper between the press rolls together with the wet paper. The most widely used papermaking felts are woven fabrics made by crossing warp and weft threads, non-woven fabrics made by pulling threads together without weaving, or polymer films or sheets that have been made breathable by perforating or foaming, either alone or in combination to form a base fabric, with batt fibers laminated on both sides of this base fabric. In addition, in order to improve the quality of paper produced and to further improve productivity by increasing the papermaking speed, papermaking felts are required to have better properties such as water drainage, surface smoothness, anti-hair removal, anti-staining, etc. In order to meet these requirements, papermaking felts that have been subjected to resin processing have been widely used in recent years. Resin processing is carried out, for example, by impregnating papermaking felt with one or more types of resin (mainly polyurethane resin) dispersed in water or the like. Resin processing has the advantage of improving various properties of papermaking felt, such as water squeezing ability, initial compatibility, and compression resistance. However, resin processing increases the bending rigidity of the papermaking felt, making it harder, which has the disadvantage that it can easily become difficult to put into a papermaking machine (hereinafter referred to as "put-in-place" for short). For this reason, for example, Patent Document 1 discloses a method of performing a surface treatment on papermaking felt after resin processing by applying a softening agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2017-150101 Summary of the Invention [Problem to be solved by the invention]

[0004] By subjecting the papermaking felt to a surface treatment that applies a softener, the flexibility of the felt is improved, i.e., the felt becomes softer, which improves the ease of insertion into a papermaking machine. As the amount of softener applied increases, the felt becomes even softer, which further improves the ease of insertion into a papermaking machine. However, as the amount of softener applied to papermaking felt increases, the durability of the resin applied in the resin treatment decreases and the resin becomes more likely to fall off from the papermaking felt, resulting in the problem that it becomes difficult to obtain the benefits of the resin treatment.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a papermaking felt that can improve ease of insertion into a papermaking machine while favorably enjoying the benefits of resin processing. [Means for solving the problem]

[0006] The inventors have conducted repeated tests to satisfy the demands for improving ease of insertion into a papermaking machine and durability of the resin, and have found that by adding a softener so that the weight ratio to the resin (polyurethane resin) falls within a specified range, the bending rigidity of the papermaking felt is reduced, improving ease of insertion, and the benefits of resin processing can be advantageously enjoyed. The present invention is as follows. 1. A papermaking felt coated with polyurethane resin and containing a softener, A papermaking felt, wherein the weight ratio of the softener to the polyurethane resin (weight of softener / weight of polyurethane resin) is in the range of 0.024 to 0.090. 2. The papermaking felt according to claim 1, wherein the softening agent contains a surfactant. 3. The papermaking felt according to claim 2, wherein the surfactant is a nonionic surfactant. 4. A base fabric layer and a surface batt layer disposed on the papermaking surface side of the base fabric layer, 4. The papermaking felt according to claim 1, wherein the surface batt layer comprises a surface layer portion containing fibers to which the polyurethane resin is bonded, and the softener is applied to the surface layer portion. Effect of the Invention

[0007] According to the papermaking felt of the present invention, it is possible to improve the ease of insertion into a papermaking machine while favorably enjoying the benefits of resin processing. [Brief description of the drawings]

[0008] The present invention will be further described in the following detailed description by way of non-limiting examples of exemplary embodiments according to the invention and with reference to the several drawings mentioned, in which like reference numerals refer to like parts throughout the several views of the drawings. [Figure 1] FIG. 2 is a schematic diagram showing another example of the cross-sectional structure of the papermaking felt of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing a measuring device for measuring a weft bending stiffness value. [Diagram 3] 1 is a graph showing the relationship between the weight ratio of a softener to a polyurethane resin, and the resin remaining rate and the weft bending change rate of the papermaking felt obtained in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The matters shown herein are for illustrative purposes and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this respect, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some forms of the present invention may be actually embodied.

[0010] [1] Papermaking felt The present invention relates to a papermaking felt having a polyurethane resin applied thereto and a softener added thereto, in which the weight ratio of the softener to the polyurethane resin (weight of softener / weight of polyurethane resin) is in the range of 0.02 to 0.09. In the papermaking felt of the present invention, the weight ratio of the softener to the polyurethane resin can further be set in the range of 0.03 to 0.09.

[0011] The papermaking felt of the present invention may have a configuration as shown in FIG. That is, as shown in FIG. 1, the papermaking felt 1 comprises a base fabric layer 11, a front batt layer 13 arranged on the papermaking surface side of the base fabric layer 11 (the upper surface side in FIG. 1), and a back batt layer 15 arranged on the running surface side of the base fabric layer 11 (the lower surface side in FIG. 1). The surface batt layer 13 comprises fibers bonded with polyurethane resin 19. In this surface batt layer 13, the side facing the base fabric layer 11 on the inside is an inner layer portion 13A, and the side facing the papermaking surface on the outside is a surface layer portion 13B. A softener (not shown) is provided in a dispersed state mainly inside surface layer portion 13B. The papermaking felt 1 is formed as an integrated whole by intertwining layers such as a base fabric layer 11, a front batt layer 13, and a back batt layer 15 in the lamination direction.

[0012] The papermaking felt 1 may have a configuration in which the back batt layer 15 is omitted, for example. Furthermore, the surface batt layer 13 of the papermaking felt 1 may have a multi-layer structure, for example, having two layers, an inner layer portion 13A and a surface layer portion 13B. When the surface batt layer 13 has a multi-layer structure, an additional batt layer can be provided between the inner layer portion 13A and the surface layer portion 13B.

[0013] (1) Base fabric layer The fabric layer may be derived from a fabric used in papermaking felt, and is usually made of thread. Examples of the thread material include polyamide resins such as nylon 6, nylon 66, nylon 610, and nylon 612; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; and synthetic resins such as polyolefin resins such as polyethylene and polypropylene, as well as cotton, wool, and silk. Among these examples, polyamide resin is particularly preferred as the material for the yarn constituting the base fabric layer, from the viewpoint of being able to produce a papermaking felt having excellent abrasion resistance, compression recovery, impact resistance, and the like.

[0014] The yarn may be in the form of a monofilament, a multifilament, a spun yarn, or a processed yarn such as a textured yarn, a bulky yarn, or a stretch yarn that has been subjected to a crimping process or a bulking process, or further may be a twisted yarn obtained by twisting these yarns together. The cross-sectional shape of the thread may be circular, approximately elliptical, polygonal, approximately star-shaped, approximately rectangular, or the like. The yarn may be a hollow yarn.

[0015] The diameter of the thread is not particularly limited. When the thread is in the form of a monofilament, the diameter is preferably 0.10 mm to 0.60 mm, and more preferably 0.20 mm to 0.50 mm. When the yarn is in the form of a multifilament, the fineness of the monofilaments constituting the multifilament is usually 3 dtex to 1,000 dtex, and preferably 5 dtex to 600 dtex. When the yarn is in the form of a multifilament, the number of filaments in the multifilament is usually 2 to 300, and preferably 2 to 100.

[0016] The fabric layer may be made up of one type of yarn or two or more types of yarn. The yarns constituting the base fabric layer may have an appropriate material, shape, diameter, etc. according to the strength, porosity, breathability, pressure uniformity, and other properties of the papermaking felt.

[0017] The structure of the base fabric layer is not particularly limited, and may be either a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, the fabric may be a multi-woven base fabric consisting of at least two layers formed by weaving two or more warp threads and two or more weft threads, or a fabric formed by stacking multiple different types of base fabrics. The fabric layer may have a structure in which the yarns are arranged in the warp direction, the weft direction or an oblique direction. The base fabric layer may be a polymer film or sheet that has been subjected to a perforation process, foaming process, or the like.

[0018] The thickness of the base fabric layer is not particularly limited, and is preferably 0.2 mm to 3.5 mm, and more preferably 0.4 mm to 2.0 mm. The basis weight of the base fabric layer is not particularly limited, but is preferably 150 g / m 2 ~1500g / m 2 , more preferably 250 g / m 2 ~1200g / m 2 It can be said that: The thickness and basis weight of the fabric layer are appropriately set depending on the strength, porosity, air permeability, and fabric mark prevention properties of the papermaking felt. The thickness and basis weight of the base fabric layer are the thickness and basis weight of the single layer in the case of a single-layer structure, and the sum of the thicknesses and basis weights of the individual layers in the case of a multi-layer structure.

[0019] (2) Surface batt layer The surface batt layer is a layer composed of fibers (hereinafter also referred to as "surface batt fibers"), which is arranged on the papermaking surface side of the base fabric layer and has the function of transporting the wet paper while maintaining the surface smoothness during papermaking. The structure of the surface batt layer is not particularly limited, and may be either a single-layer structure or a multi-layer structure.

[0020] Examples of materials for the surface batt fiber include polyamide resins such as nylon 6, nylon 66, nylon 610, and nylon 612; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; and synthetic resins such as polyolefin resins such as polyethylene and polypropylene, as well as cotton, wool, and silk. Among these, polyamide resin is preferred as the material for the surface batt fiber from the viewpoints of abrasion resistance, compression recovery, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, and the like.

[0021] The fineness of the surface batt fiber is usually 0.1 dtex to 100 dtex. When the surface batt layer has a multi-layer structure, the fineness of the surface batt fibers may be the same or different in, for example, inner layer portion 13A and surface layer portion 13B shown in FIG. Typically, the fineness of the surface batt fibers contained in the inner layer portion 13A can be 3 dtex to 150 dtex, and the fineness of the surface batt fibers contained in the surface layer portion 13B can be 0.1 dtex to 100 dtex.

[0022] The surface batt layer has a basis weight of preferably 100 g / m2 as a whole, whether it is a single-layer structure or a multi-layer structure. 2 ~1,500g / m 2 , more preferably 300 g / m 2 ~1,200g / m 2 , more preferably 400 g / m 2 ~1,000g / m 2 It is. The fineness of the surface batt fibers and the basis weight of the surface batt layer are appropriately set depending on the strength, porosity, and air permeability of the papermaking felt, as well as the surface properties of the surface batt layer.

[0023] (3) Back batt layer The papermaking felt of the present invention may further include a back batt layer 15 on the running surface side of the base fabric layer 11 opposite the front batt layer 13 (see FIG. 1). The back batt layer is a layer composed of fibers (hereinafter also referred to as "back batt fibers"), and has the effect of improving the durability of the papermaking felt by protecting the base fabric layer from abrasion.

[0024] The material for the back batt fibers is not particularly limited, and like the front batt fibers, can be polyamide resins such as nylon 6, nylon 66, nylon 610, nylon 612, etc.; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, etc.; polyolefin resins such as polyethylene, polypropylene, etc.; synthetic resins, cotton, wool, silk, etc. The fineness of the back batt fiber is usually 3 dtex to 150 dtex. The weight of the back batt layer is usually 50g / m 2 ~500g / m 2 It is.

[0025] (4) Polyurethane resin The papermaking felt of the present invention is coated with a polyurethane resin. This polyurethane resin is applied to the papermaking felt to control the air permeability (water squeezing) in the cross-sectional direction of the papermaking felt within an appropriate range and to impart an appropriate hardness to the surface layer, thereby improving the water squeezing ability, initial conformability, compression resistance, etc. In other words, by applying resin processing to the fibers of the papermaking felt, the papermaking felt can enjoy the benefits of improved water squeezing ability, initial conformability, compression resistance, etc. As a specific example, as shown in FIG. 1, a papermaking felt 1 includes fibers 17 bound with polyurethane resin 19 in an inner layer portion 13A and a surface layer portion 13B of a surface batt layer 13.

[0026] The polyurethane resin may be bonded to the fibers in either a manner in which the polyurethane resin adheres to the fibers or a manner in which the polyurethane resin bonds the fibers together. In addition, the polyurethane resin can be used to bond fibers together in either of two ways: the polyurethane resin bonds together fibers extending in perpendicular or intersecting directions at their intersections, or the polyurethane resin that has penetrated between multiple fibers bonds the fibers together.

[0027] The fibers bound with the polyurethane resin are not necessarily limited to the form contained in the inner layer portion 13A and the surface layer portion 13B of the surface batt layer 13 as exemplified in FIG. In other words, if the papermaking felt 1 is coated with polyurethane resin, the fibers bonded with the polyurethane resin can be contained only in the surface layer portion 13B of the surface batt layer 13, or can be contained in both the surface batt layer 13 and the base fabric layer 11.

[0028] The polyurethane resin is synthesized by using polyol (hydroxyl group) and isocyanate-based compound (isocyanate group) as main raw materials. The types of polyol and isocyanate-based compound used as the main raw materials are not particularly limited. Examples of the polyol include polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, etc., and any of these may be used. Examples of the isocyanate compound include aromatic isocyanate compounds, aliphatic isocyanate compounds, and alicyclic isocyanate compounds, and any of these may be used. The polyurethane resin may be a resin synthesized only from the above-mentioned main raw materials, or a resin synthesized from a mixture of the main raw materials and secondary raw materials such as catalysts and crosslinking agents, and additives such as colorants and stabilizers.

[0029] Papermaking felt is obtained by subjecting a base fabric layer, a surface batt layer, and other components, which have been integrated together by interlacing or the like, to a resin treatment in which a polyurethane resin is applied to the base fabric. Hereinafter, in the papermaking felt, the felt formed from an integrated body of a base fabric layer, a surface batt layer, etc., and which has not been subjected to resin processing or softening processing, in other words, the felt which has not been coated with polyurethane resin and has not been given a softener, will be referred to as "felt raw material". In addition, felt that is made by only resin-processing a raw felt roll and not softening it is called "resin-processed felt".

[0030] The type of polyurethane resin used in the resin processing is not particularly limited, and any of foams such as soft polyurethane foam and hard polyurethane foam, and non-foams such as thermoplastic elastomers, thermosetting elastomers, and paints can be used. The state of the polyurethane resin used for resin processing is not particularly limited, but is usually liquid. The method for obtaining the liquid polyurethane resin is not particularly limited, and any known method can be applied, but in particular, water-based polyurethane emulsions and water-based polyurethane dispersions obtained by dispersing polyurethane resin in water have the advantage that they can be easily resin-processed onto raw felt rolls.

[0031] (5) Fabric softener The papermaking felt of the present invention is obtained by adding a softening agent to a resin-processed felt. The softening agent is added for the purpose of improving the flexibility of the papermaking felt, thereby making it easier to insert the papermaking felt into a papermaking machine.

[0032] Specifically, in the papermaking felt 1 shown in FIG. 1, the softener is applied to the surface layer portion 13B including fibers to which the polyurethane resin 19 is bonded, although this is not specifically shown. This surface layer portion 13B enjoys the benefits of being coated with polyurethane resin 19, and is given appropriate flexibility by the addition of a softening agent.

[0033] The softener may be applied in any of the following forms: the softener is adsorbed or attached only to the fibers; the softener is adsorbed or attached to the fibers and the resin of the fibers to which the polyurethane resin is bonded; or the softener penetrates into the gaps between the fibers. In addition, the softener is not necessarily limited to being applied only to the surface layer of the surface batt layer. As long as the softener is applied to the papermaking felt, the softener may be applied to the surface layer and inner layer of the surface batt layer, or to the surface batt layer and base fabric layer.

[0034] The softening agent used may generally contain a surfactant. That is, the surfactant has a hydrophilic group and a lipophilic group, and by adsorbing the hydrophilic group to the fiber with the lipophilic group facing outward, the lipophilic group acts like a lubricant, reducing the frictional resistance between the fibers and improving slippage, thereby improving the flexibility of the papermaking felt. The surfactant is not particularly limited, and one or more surfactants selected from ionic surfactants such as anionic surfactants, cationic surfactants, and amphoteric surfactants, and nonionic surfactants can be used. Among these surfactants, nonionic surfactants have hydrophilic groups (hydroxyl groups or ether bonds) that do not dissociate into ions in an aqueous solution, and since they do not ionize, they are less susceptible to the effects of water hardness and electrolytes, and can be used in combination with ionic surfactants, and therefore are preferred as surfactants to be contained in fabric softeners.

[0035] The softener may be a softener consisting of only a surfactant (preferably a nonionic surfactant), or may be a softener consisting of a surfactant (preferably a nonionic surfactant) to which an additive has been added. The additives are not particularly limited, and additives used in known softeners, such as antistatic agents and colorants, can be used.

[0036] The additive may be a resin of the same type as the fiber material used in the felt roll. It is preferable that the resin of the same type is further provided with a hydrophilic group. For example, when the fiber material used in the felt roll is a polyamide resin, the additive may be a polyamide resin provided with a hydrophilic group. When a resin of the same type is used as an additive, the resin of the same type has a high affinity with the fibers used in the raw felt roll, and therefore can form a coating on the surface of the fibers. Furthermore, when the same resin is endowed with a hydrophilic group, it can act as an intermediary for adsorbing a surfactant onto the surface of the fibers used in the felt material. For this reason, when a resin of the same type as the fiber used in the raw felt roll, especially a resin of the same type to which a hydrophilic group has been added, is used as an additive, the flexibility of the papermaking felt can be improved, and the hydrophilicity is increased, making it easier for water to penetrate the fibers, making it easier to remove dirt, and improving the dirt resistance of the papermaking felt.

[0037] (6) Composition and physical properties [Weight ratio] In the papermaking felt, the weight ratio of the softener to the polyurethane resin is in the range of 0.024 to 0.090. In this case, the papermaking felt can improve the ease of insertion into a papermaking machine and the durability of the polyurethane resin. The weight ratio is preferably in the range of 0.035 to 0.080, and more preferably in the range of 0.050 to 0.070. The weight ratio is calculated by dividing the amount of polyurethane resin applied to the papermaking felt by the weight of the polyurethane resin Wp (g / m 2 ), and the amount of softener applied to the papermaking felt (basis weight) is expressed as the weight of the softener Ws (g / m 2 ) and the value obtained using the weight ratio = Ws / Wp formula.

[0038] [Amount of resin applied] The coating weight (Wp) of the polyurethane resin (hereinafter abbreviated as "resin coating weight (Wp)") is not particularly limited, and is appropriately set according to the performance required for the papermaking felt, such as water drainage, initial compatibility, and compression resistance. The resin coating weight (Wp) is the weight of polyurethane resin coated on the papermaking felt (g / m 2 ) is measured. Specifically, the resin coating weight (Wp) is preferably 10 g / m 2 ~100g / m 2 , more preferably 20 g / m 2 ~90g / m 2 It can be said that:

[0039] [Softener amount] The amount of softener applied (Ws) (hereinafter abbreviated as "amount of softener applied (Ws)") is not particularly limited, and is appropriately set depending on performance such as the ease of insertion of the papermaking felt into a papermaking machine, the durability of the polyurethane resin, etc. The amount of softener applied (Ws) is the weight of the solid content of the softener applied to the papermaking felt (g / m 2 ) is measured. Specifically, the amount of softener applied (Ws) is preferably 2 g / m 2 ~10g / m 2 , more preferably 2.5 g / m 2 ~8.5g / m 2 , and more preferably 3 g / m 2 ~6.5g / m 2 It can be said that:

[0040] [Resin residual rate] The ability of papermaking felt to resist resin release can be expressed in terms of the resin remaining rate (%). That is, during papermaking, the surface (surface batt layer) of the papermaking felt is directly subjected to external mechanical forces such as repeated compression, showering, suction, etc. When the papermaking felt is subjected to external mechanical forces, the resin (polyurethane resin in this application) applied to the papermaking felt deteriorates over time and peels off from the fibers, causing the resin to be detached, and it may become impossible to enjoy the benefits of the resin processing. In other words, when used in a papermaking felt, if the resin is prone to detachment during use in a papermaking machine, it is difficult to fully enjoy the benefits of the resin processing, whereas if the resin is not prone to detachment, it is possible to optimally enjoy the benefits of the resin processing.

[0041] The resin residual rate (%) is a value indicating the performance of the papermaking felt against the detachment of the resin, in other words, the durability of the resin with respect to detachment from the papermaking felt. Specifically, the resin residual rate (%) in this application is a value obtained by carrying out a durability test described later on the papermaking felt and measuring the amount of the polyurethane resin remaining in the papermaking felt. In detail, the above-mentioned resin coating weight (Wp) and the resin shedding weight (W L1 ;g / m 2 ) and the formula is: (Wp-W L1 The value calculated from [(Wp-Wp)] × 100 is the resin remaining rate (%). L1 ) / Wp〕×100). In addition, the amount of resin falling off (W L1 ;g / m 2 ) is the weight (weight per unit area; g / m2) of papermaking felt before durability testing. 2 ) and weight after durability test (basis weight: g / m 2 ) is measured and the weight change before and after the durability test is calculated (W L1 = weight after durability test - weight before durability test).

[0042] The resin residual rate (%) is not particularly limited, and is appropriately set so as to obtain the benefits of the resin processing in a suitable manner according to the ease of insertion into a paper machine required of the papermaking felt. Specifically, the lower limit of the resin residual rate (%) is preferably 80% or more, more preferably 82% or more, and even more preferably 84% or more. Usually, the upper limit of the resin residual rate (%) is 100%.

[0043] [Lateral bending rate] The ease of insertion of papermaking felt into a papermaking machine can be expressed by the weft bending change rate (%). That is, when a softener is added to a papermaking felt, the flexibility of the felt is improved and the bending stiffness (g / cm) is decreased. When the change in the bending stiffness (g / cm) is large, the flexibility is greatly improved and the threading ability is improved. When the change in the bending stiffness (g / cm) is small, the flexibility is not improved and the threading ability is reduced. Therefore, the rate of change between the bending stiffness (g / cm) of the papermaking felt before the application of the softener and the bending stiffness (g / cm) of the papermaking felt after the application of the softener, that is, the bending change rate (%), can be used to express the insertion ability as follows: when the bending change rate (%) is high, the insertion ability is high, and when the bending change rate (%) is low, the insertion ability is low. The above-mentioned bending stiffness value (g / cm) is measured using a measuring device (see Figure 2) to measure the bending stiffness value (g / cm) in the weft direction of the papermaking felt, i.e., the weft bending stiffness value (g / cm).

[0044] Here, the measurement of the weft bending stiffness value (g / cm) will be described in detail. As shown in Fig. 2, the measuring device for weft bending stiffness has a load meter 21 for measuring bending stiffness and a base 22 for placing the measurement target 1 (paper felt or felt roll). The load meter 21 measures the load applied from the paper felt 1 placed below, and specifically, a "handheld digital force gauge DFG-50R (product name)" manufactured by Nidec-Shimpo Corporation is used.

[0045] The papermaking felt 1 for which the weft bending stiffness value is measured is folded in half in the weft direction so that the surface on which the surface batt layer is provided is the front surface, with the warp direction or flow direction being the warp direction (MD direction in the figure), and the direction perpendicular to the warp direction being the weft direction (CMD direction in the figure). During measurement, the distance between the load meter 21 and the base 22 is set to 3 cm, and the papermaking felt 1 is placed between them in a state where it is folded in half in the weft direction. Then, the load meter 21 is lowered until the distance between the load meter 21 and the base 22 is 1 cm, and the load meter 21 is pressed against the papermaking felt 1. The load measured by the load meter 21 at this time is taken as the weft bending stiffness value (g / cm) of the papermaking felt 1.

[0046] The weft bending change rate (%) is the measured weft bending stiffness of the raw felt roll F 0 (g / cm), and the measured weft bending stiffness of the resin-treated felt or paper-making felt is F 1 (g / cm), the weft bending change rate (%) = (F 1 / F 0 ) × 100. The weft bending change rate (%) is not particularly limited, and is appropriately set so as to improve the ease of insertion into a papermaking machine within a range in which the advantages of the resin treatment applied to the papermaking felt can be enjoyed. Usually, the upper limit of the weft bending change rate (%) can be set to preferably 115% or less, more preferably 110% or less, and further preferably 105% or less. If the weft bending change rate (%) is less than 100%, the weft bending rigidity will be lower than that of a non-resin-treated raw felt fabric, making it difficult to obtain the benefits of the resin treatment.

[0047] [2] Manufacturing method of papermaking felt The method for producing papermaking felt includes a resin processing step in which polyurethane resin is applied to a raw felt roll to obtain a resin-processed felt, and a softening step in which a softener is applied to the resin-processed felt to obtain the papermaking felt. Each step will be described below.

[0048] (1) Resin processing process The resin processing step is a step in which polyurethane resin is applied to the raw felt to obtain resin-processed felt. Specifically, the resin processing is carried out by applying or impregnating a dispersion obtained by dispersing polyurethane resin in water (hereinafter referred to as "aqueous dispersion") onto or onto a felt roll, drying it, heating it, and bonding the polyurethane resin to the fibers of the felt roll.

[0049] The raw felt fabric comprises a base fabric layer and a first fiber layer which serves as a front batt layer, and may, if necessary, comprise a second fiber layer which serves as a back batt layer on the opposite side of the first fiber layer. The raw felt fabric is preferably an integrated product in which the base fabric layer, the first fiber layer, etc. are entangled by needling or the like.

[0050] The explanation of “(1) Fabric layer” in “(1) Papermaking felt” above applies to the fabric layer. The first fiber layer may be either a single-layer type or a multi-layer type, and the explanation of "(2) Surface batt layer" in "(1) Papermaking felt" above applies. In addition, the fineness of the fibers constituting the outermost layer of the first fiber layer in the case of a single-layer type and the fineness of the fibers constituting the outermost layer in the case of a multi-layer type are both preferably 0.1 to 100 dtex, more preferably 0.3 to 70 dtex, even more preferably 1 to 50 dtex, and particularly preferably 2 to 30 dtex, since this improves the retention of polyurethane resin particles after application of the aqueous dispersion. When the felt raw material has a second fiber layer, the explanation of “(3) Back batt layer” in “(1) Papermaking felt” above applies to the second fiber layer.

[0051] The form of the aqueous dispersion may be an emulsion or the like, but is preferably a dispersion in which the polyurethane resin is dispersed in water, since this makes it easier to control the thickness of the binding portion (surface layer portion 13B) containing the polyurethane resin. The aqueous dispersion may consist of only the polyurethane resin, or may further contain additives.

[0052] In the resin finishing step, the method for applying the aqueous dispersion to the surface of the raw felt roll is not particularly limited, and spray coating, roll coating, etc. can be used. The amount of the aqueous dispersion to be applied is appropriately selected depending on the solid content and viscosity of the aqueous dispersion, and is not particularly limited.

[0053] In the resin processing step, the felt roll coated with the aqueous dispersion is dried by heat treatment to remove water, which is the main medium of the aqueous dispersion, and the polyurethane resin contained in the aqueous dispersion is adhered to the fibers of the first fiber layer. The heating temperature in the heat treatment can be preferably 100°C to 170°C, and more preferably 120°C to 150°C.

[0054] (2) Softening process The softening treatment step is a step in which a softening agent is applied to the resin-processed felt to obtain papermaking felt. Specifically, the softening treatment process is carried out by applying or impregnating the resin-processed felt with a softener solution (hereinafter referred to as the "treatment liquid") obtained by diluting the original softener liquid with water, and then drying the resin-processed felt to impart the softener to the resin-processed felt.

[0055] In the softening treatment step, the softener can be used as it is, but from the viewpoint of ease of application or impregnation to the resin-processed felt, it is preferable to use a treatment liquid obtained by diluting the undiluted softener with water. The treatment liquid may consist of only a softener and water, or may further contain additives. The concentration of the softener contained in the treatment liquid is not particularly limited, and can be appropriately set depending on the viscosity of the softener, etc.

[0056] In the softening treatment step, the method for applying or impregnating the resin-processed felt with the treatment liquid is not particularly limited, and spray coating, roll coating, etc. can be applied. The amount of the treatment liquid to be applied or impregnated can be appropriately selected depending on the concentration and weight ratio of the softener.

[0057] In the softening treatment step, the resin-processed felt coated or impregnated with the treatment liquid is dried, and the softening agent contained in the treatment liquid is absorbed into the fibers to produce papermaking felt. The method for drying the resin-processed felt is not particularly limited as long as it can remove water, which is the main medium of the treatment liquid. In this drying, the drying temperature, pressure, etc. are not particularly limited. EXAMPLES

[0058] The present invention will now be described in detail with reference to examples. [Manufacturing of felt rolls] A woven fabric (weight: 273 g / m2) was obtained by weaving a single layer structure using twisted monofilament yarn (nylon 6, fiber diameter: 0.2 mm) and single monofilament yarn (nylon 6, fiber diameter: 0.25 mm). 2 ) was used as the first fabric layer. A fabric (weight: 583 g / m2) was woven in a double weave using a single monofilament yarn (nylon 6.10, fiber diameter: 0.4 mm) and a single monofilament yarn (nylon 6, fiber diameter: 0.4 mm). 2 ) was used as the second fabric layer. The above-mentioned first fabric layer and second fabric layer were laminated in the thickness direction, with the first fabric layer side serving as the papermaking surface and the second fabric layer side serving as the running surface to obtain a fabric (fabric layer).

[0059] On the paper-making side of the above-mentioned base fabric (base fabric layer), staple fiber (nylon 66, average fineness: 51 dtex) was applied to the inner layer side at a basis weight of 570 g / m 2 The surface layer is made of staple fiber (nylon 66, average fineness: 31 dtex) with a basis weight of 234 g / m 2 The first fibrous layer was formed. Furthermore, on the running surface side of the above-mentioned base fabric (base fabric layer), staple fiber (nylon 66, average fineness: 51 dtex) was used in a basis weight of 190 g / m 2 This formed a second fibrous layer.

[0060] The above-mentioned base fabric (base fabric layer), first fiber layer, and second fiber layer were entangled and integrated by needle punching, and further pressed to produce a felt roll in which the base fabric layer, front batt layer, and back batt layer were integrated. A bending stiffness test was carried out on the obtained raw felt sheet, and the weft bending stiffness value was 1362.3 g / cm (see the "raw felt sheet" section in Table 1).

[0061] [Resin processing process] The aqueous polyurethane dispersion solution was adjusted so that the solid content concentration was 8 mass % to obtain an aqueous dispersion. The above-mentioned felt roll was set in a finishing machine, and the aqueous dispersion was sprayed on the paper-making side (surface batt layer side) of the felt roll in an amount (weight per unit area) of 1000 g / m. 2 The raw felt was then dried at 130°C, and then heated by blowing hot air at 150°C onto it to melt the polyurethane resin, thereby obtaining a resin-processed felt in which the polyurethane resin was bound to the fibers of the surface layer of the surface batt layer. This resin-treated felt has a polyurethane resin coating weight (Wp) of 80g / m 2 (See the "Experimental Example 0" in Table 1).

[0062] [Softening process] A nonionic surfactant ("Innobesol NY-30" (trade name) manufactured by Lion Specialty Chemicals) was used as a stock solution, which was diluted with water so that the stock solution concentration became 5% by mass, to obtain a treatment solution. The above-mentioned resin-treated felt (Experimental Example 0) was set in a finishing machine, and the treatment liquid was sprayed onto the paper-making surface side (surface batt layer side) of the resin-treated felt (Experimental Example 0) in a predetermined amount. The amount of the treatment liquid sprayed was appropriately changed and adjusted in each experimental example so that the amount of softener applied (basis weight) was the value of Experimental Examples 1 to 8 shown in Table 1. Thereafter, the resin-processed felt sprayed with the treatment liquid was dried at 130° C. to obtain papermaking felts coated with polyurethane resin and imparted with a softener (Experimental Examples 1 to 8). For the obtained papermaking felts (Experimental Examples 1 to 8), the resin coating weight (Wp) was 80 g / m 2 The amount of softener applied (Ws) was as shown in Table 1. For the papermaking felts of Experimental Examples 1 to 8, the weight ratio of softener to polyurethane resin (softener amount (Ws) / resin amount (Wp)) was calculated from the resin amount (Wp) and the softener amount (Ws), and is shown in Table 1.

[0063] [Durability test] The resin-processed felt (Experimental Example 0) and the paper-making felt (Experimental Examples 1 to 8) were each cut to a length of 0.34 m and a width of 0.14 m, and sewn together into an endless belt shape with a total length of 5 m after connection, to obtain test samples for Experimental Examples 0 and 1 to 8. These test samples were attached to a press roll tester, and durability tests were conducted on the durability of the polyurethane resin.

[0064] The press roll test machine is designed to press (compress) the test sample between a top roll and a bottom roll once per revolution during the durability test. The press roll tester is structured so that a test sample is run through a plurality of rolls attached to the tester so that the surface of the test sample is bent both outward and inward. Furthermore, the press roll tester has a structure including a high-pressure needle-type sliding shower and a suction box.

[0065] The durability test was carried out by running the test sample at a running speed of 150 m / min and a press line pressure of 45 kN / m until the test sample had been pressed 46,500 times. In addition, the durability test was performed by sliding a high-pressure needle shower over the papermaking side of the test sample (the papermaking side of the papermaking felt) to spray water onto the papermaking side, and running the test sample while sucking up the water from the papermaking side of the test sample with a suction box.

[0066] The weight of the test sample before the durability test (basis weight: g / m2 ) and weight after durability test (basis weight: g / m 2 The weight difference before and after the durability test was calculated as the amount of resin that had fallen off (W L1 ;g / m 2 ) was calculated as This resin loss amount (W L1 ;g / m 2 ) and the above-mentioned resin coating weight (Wp; g / m 2 ) and the remaining resin amount of the test sample after the durability test (Wp 1 ;g / m 2 ) was calculated, and the resin coating weight (Wp; g / m 2 Residual resin amount (Wp 1 ;g / m 2 ) ratio [(Wp 1 The resin remaining rate (%) was calculated from the formula: For the test samples of Experimental Example 0 and Experimental Examples 1 to 8, the amount of resin falling off (W L1 ;g / m 2 ) and the resin remaining rate (%) are shown in Table 1.

[0067] [Bending stiffness test] Test samples measuring 10 cm length x 10 cm width were cut out from three locations on each of the felt raw rolls, resin-processed felt (Experimental Example 0), and papermaking felt (Experimental Examples 1 to 8), to obtain three test samples each for the felt raw rolls, Experimental Example 0, and Experimental Examples 1 to 8. The weft bending stiffness values ​​(g / cm) of all three test samples, namely, the raw felt roll, experimental example 0, and experimental examples 1 to 8, were measured using the measuring device shown in FIG. 2, and the average values ​​were calculated. The average values ​​were used as the weft bending stiffness values ​​(g / cm) of the raw felt roll, experimental example 0, and experimental examples 1 to 8. Then, the weft bending change rate (%) was calculated based on the weft bending rigidity values ​​(g / cm) of the raw felt and Experimental Example 0 and Experimental Examples 1 to 8. This weft bending change rate (%) was calculated by multiplying the weft bending rigidity values ​​(g / cm) of Experimental Example 0 and Experimental Examples 1 to 8 by F 1 The weft bending stiffness value (g / cm) of the felt roll is F 0 Then, the weft bending change rate (%) = (F 1 / F 0 ) × 100. Table 1 shows the weft bending stiffness (g / cm) and the weft bending change rate (%) for the raw felt fabric and the test samples of Experimental Example 0 and Experimental Examples 1 to 8.

[0068] [Table 1]

[0069] [Results / Discussion] FIG. 3 is a graph showing the relationship between the weight ratio shown in Table 1, the resin remaining rate (%), and the weft bending change rate (%) for Experimental Example 0 (resin-processed felt) and Experimental Examples 1 to 8 (papermaking felt). As shown in the graph of Fig. 3 and Table 1, the weft bending rigidity value (g / cm) of Experimental Example 0, which was not applied with a softener, was higher than Experimental Examples 1 to 8, and its weft bending change rate (%) was 129.4%. And, for Experimental Examples 1 to 8, which were applied with a softener, the weft bending change rate (%) decreased as the weight ratio increased, that is, as the amount of softener applied (Ws) increased. Meanwhile, regarding the resin residual rate (%), the resin residual rate of Experimental Example 0, which was not given a softener, was 81.8%, but the resin residual rate of Experimental Example 1, which was given a softener so that the weight ratio was 0.019, was 88.4%, which was a greater increase than that of Experimental Example 0. In other words, Experimental Example 1 was able to enjoy the benefits of the resin processing to a greater extent than Experimental Example 0, which was not given a softener. Furthermore, following Experimental Example 1, the resin residual rate (%) was also 88.0%, 87.8%, and 84.6% in Experimental Examples 2, 3, and 4, which were higher than 81.8% in Experimental Example 0. From the graph in Fig. 3, it can be seen that the resin residual rate (%) only decreased very slightly in Experimental Examples 1 to 3 even when the weight ratio was increased to 0.019, 0.040, and 0.060, and that a tendency for it to decrease significantly was seen from Experimental Example 4 onwards, where the weight ratio was set to 0.080 or more. That is, the weft bending change rate (%) decreases as the amount of softener applied (Ws) increases, and the application property can be improved. On the other hand, when the weight ratio of the amount of softener applied to the amount of resin applied is within a certain range, the resin remaining rate (%) increases more than that of the resin-processed felt without softener applied, which shows that the merits of resin processing can be fully enjoyed.

[0070] The range of weight ratios for improving the resin residual rate (%) will be considered. For the papermaking felts of Experimental Examples 1 to 8, the resin residual rate (%) was set to the standard value of 81.8% for Experimental Example 0, and the weft bending change rate (%) was set to the standard value of 110%, which is 10% higher than the original felt roll of 100%. The weft bending change rate (%) standard value of 110% is more than 10% lower than the 129.4% for Experimental Example 0 to which no softener was added. Then, those with a resin residual rate (%) of 81.8% or more (standard value) and a weft bending change rate (%) of 110% or less (standard value) were rated as "Good", as this indicates that the benefits of resin processing can be optimally enjoyed and that ease of loading into the papermaking machine has been improved, and all other items were rated as "NG". The results of the evaluation are shown in Table 1.

[0071] Experimental Examples 2 to 4 were rated "Good," with the resin residual rate (%) exceeding the standard value of 81.8%, allowing the benefits of resin processing to be enjoyed to the fullest, and the weft bending change rate (%) being below the standard value of 110%, indicating good ease of insertion into the papermaking machine. In Experimental Example 1, the resin residual rate (%) was 88.4%, exceeding the standard value of 81.8%, and the benefits of resin processing were enjoyed. However, the weft bending change rate (%) was 129.4%, exceeding the standard value of 110% for judging it as "Good", and there were some problems with the ease of loading into the papermaking machine. In Experimental Examples 5 to 8, the resin remaining rate (%) was less than the reference value of 81.8%, and the resin was easily removed, so it was found that no benefit could be obtained from the resin processing.

[0072] Regarding the weight ratio, if the upper limit of the weft bending change rate (%) at which the threading ability is not affected is set to the above-mentioned reference value of 110%, the weight ratio value is 0.024 or more as shown in the graph of FIG. Regarding the weight ratio, the resin residual rate (%) was set to a standard value of 81.8% for Experimental Example 0, and when the lower limit of the resin residual rate (%) was set to 81.8% or more from the viewpoint of improving the durability of the resin, the weight ratio value was 0.090 or less from the graph in FIG. 3. Therefore, it was found that the weight ratio in the present invention is in the range of 0.024 to 0.090 from the viewpoints of improving ease of feeding into a paper machine and suitably enjoying the benefits of resin processing. [Industrial Applicability]

[0073] The papermaking felt of the present invention is suitably used as a papermaking press felt for use in the press part of a papermaking machine, and has excellent water squeezing properties, and can be used in the manufacturing process of various types of paper, including paper that requires a large amount of water to be squeezed out, such as paperboard. [Explanation of symbols]

[0074] 1: papermaking felt, 11: base fabric layer, 13: surface batt layer, 13A: inner layer portion, 13B: surface layer portion, 15: back batt layer, 17: surface batt fiber, 19: polyurethane resin.

Claims

1. This papermaking felt is characterized in that a softener is added to a resin-processed felt coated with a polyurethane resin in a weight ratio (basis weight of softener / basis weight of polyurethane resin) of 0.024 to 0.090 relative to the polyurethane resin.

2. 2. The papermaking felt according to claim 1, wherein the softening agent comprises a surfactant.

3. 3. The papermaking felt according to claim 2, wherein the surfactant is a nonionic surfactant.

4. A base fabric layer and a surface batt layer disposed on the papermaking surface side of the base fabric layer, 4. The papermaking felt according to claim 1, wherein the surface batt layer comprises a surface layer portion containing fibers to which the polyurethane resin is bonded, and the softener is applied to the surface layer portion.

5. The papermaking felt described in any one of claims 1 to 4, wherein the resin residual rate, which indicates the performance of resisting resin detachment, is 81.8% or more and 100% or less, and the weft bending change rate, which indicates the ease of insertion into a papermaking machine, is 100% or more and 110% or less.

6. The papermaking felt described in any one of claims 1 to 4, wherein the resin residual rate, which indicates the performance of resisting resin detachment, is 84% ​​or more and 100% or less, and the weft bending change rate, which indicates the ease of insertion into a papermaking machine, is 100% or more and 105% or less.

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