JP2012154015A - Papermaking press felt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a papermaking press felt, in which the basic functions are well balanced, which does not have any wet paper web transfer deficiencies due to meandering, or the like, in which free space of a felt, where the effect of the press pressure and the hydraulic pressure is scarcely conveyed to the wet paper web, is set to the suitable amount for the initial warming-up period from the start of use so that the initial warming-up period is shortened, and in which water squeezing does not deteriorate due to premature decline of water permeability and due to the inability to maintain compressibility by excessive compaction and accumulation of dirt.SOLUTION: There is provided a papermaking press felt, having a reinforcing fiber substrate 1, and an obverse batt fiber layer 2 disposed on a wet paper carrying side of the reinforcing fiber substrate and a reverse batt fiber layer 3 disposed on a press roll side. At least one of the obverse batt fiber layer 2 and the reverse batt fiber layer 3 includes a fused fiber, and a water absorbing resin 4 is contained in the felt.

Description

The present invention is used by laminating wet paper, and a papermaking felt (hereinafter simply referred to as “felt”) used to squeeze water in wet paper with a pair of rotating rolls or rolls and shoes of a paper machine. ”).
More specifically, the present invention relates to a papermaking felt that can improve the wettability of wet paper including the initial familiarity period until reaching the maximum speed at which stable production is possible with a paper machine.

  In the paper making process, in order to squeeze water from wet paper, a paper machine has conventionally been provided with a wire part, a press part, and a dryer part. These wire part, press part, and dryer part are arranged in this order along the conveyance direction of the wet paper. The wet paper is conveyed while being successively delivered to the paper making tools arranged in the wire part, the press part, and the dryer part, and is squeezed, and finally dried in the dryer part.

  In each of these parts, a papermaking tool corresponding to the dewatering function is used. The press device arranged in the press part includes a plurality of press devices arranged in series along the wet paper transport direction.

  Each press device is an endless felt, or a felt that is connected endlessly on a paper machine to endlessly, and a press that is vertically opposed to sandwich a part of each felt. A pair of rolls (that is, a roll press) or a roll and a shoe (that is, a shoe press), and wet paper conveyed by a felt traveling in the same direction at substantially the same speed, together with the felt, By pressing with a roll or a roll and a shoe, the felt is continuously absorbed by the felt while squeezing the moisture from the wet paper.

  In addition, in such a paper machine, a paper machine having a roll press mechanism in which a press device that presses a part of the felt holding the wet paper between the roll and the roll is provided in the press part, the wet paper There is a paper machine having a shoe press mechanism in which a press device that presses a part of the sandwiched felt between a roll and a shoe is provided in a press part.

  The felt is composed of a reinforcing fiber base material and a bat fiber layer, and the bat fiber layer is disposed only on both the wet paper placement side and the press roll side of the base material or on the wet paper placement side. At this time, the bat fiber layer is configured by entanglement and integration of the bat fiber with the reinforcing fiber base material by needle punching. The basic function of the felt plays the role of squeezing water from the wet paper (water squeezing), increasing the smoothness of the wet paper, and transporting the wet paper.

  In particular, the function of dehydrating water from the wet paper in the felt function is regarded as important. By passing pressure from a pair of rolls or rolls and shoes, water is transferred from the wet paper to the felt, In order to discharge water out of the system, it is important to maintain water permeability and compressibility by appropriately securing the space volume in the felt.

  The appropriate space volume is the space volume when the operation speed of the paper machine is stabilized. Fast and stable operation speed is important from the standpoint of production volume, and this period is called the initial familiarity period. Although the initial acclimatization period varies depending on the operating conditions of the paper machine, it generally takes 1 to 2 days and 5 days at the longest. In particular, in a wet paper web transport system such as a Nordlow straight through type represented by a tandem Nipcoflex paper machine, it is necessary to increase the operation speed and shorten the initial familiarity period.

  From this point of view, various types of felt have been developed. For example, as a known technique, after the felt is finished, a measure is taken to increase the density by applying pressure in post-processing to reduce the thickness of the felt. In order to increase the pressurizing effect, the felt may be in contact with a roll heated by a heat medium. As an action mechanism, the space volume formed in the felt is reduced, and the pressurizing force received by the press part is easily transmitted to the wet paper.

  Patent Document 1 (Japanese Patent Publication No. 2005-524002) describes a method of polishing the surface after processing with a polymer substance on the felt surface side to make it compact. Since the paper felt with such a structure is made compact from the beginning, it leads to shortening the initial familiarization period of the paper machine.

  However, in the felt for papermaking using the polymer of polyurethane, polycarbonate urethane, polyacrylate, acrylic resin, epoxy resin, phenol resin or a mixture thereof of Patent Document 1, it can be made compact by the adhesive force / coagulation force of the polymer, It gave rigidity to the entire felt. If the rigidity increases too much, compression / recovery behavior under the press will be suppressed, and sufficient wet paper squeezing capacity will not be obtained. Also, when placed on a paper machine, it will be difficult to handle between narrow rolls. Therefore, there was also a problem in terms of ease of installation.

  Patent Document 2 (JP-A-2-127585) describes a production method in which a felt resin is coated with a foamed resin and dried and solidified. In the felt having such a structure, the felt surface having a porous contact region made of foamed resin removes water from the wet paper.

  However, the felt described in Patent Document 2 can receive the water that the porous part is squeezed from the wet paper when it is new, but it gradually includes the foamed part when it receives direct pressure from the repeated press roll. It is made compact. When the foamed resin layer is made compact, water permeability is lowered, dirt from the wet paper is accumulated, moisture in the wet paper cannot be received, and water squeezing is reduced.

  In Patent Document 3 (Japanese Patent Laid-Open No. 2005-146443) using a similar foamed resin, a foam gel is formed between the wet paper web contact layers above the felt base material (wall structure). A manufacturing method is proposed. The felt having such a structure improves the smoothness of the wet paper surface by improving the pressure dispersibility to prevent the base fabric mark.

  However, the felt described in Patent Document 3 has the same problem as Patent Document 2, although the gel foam layer does not directly contact the press roll.

  In the felt described in Patent Document 4 (Japanese Patent Application Laid-Open No. 56-53297), it is expected that the initial acclimatization period is shortened due to the hydrophilicity of the fiber of the sodium acrylate / acrylamide copolymer.

  However, the felt described in Patent Document 4 has a problem that the durability of squeezing is inferior because the durability of the fiber of the sodium acrylate / acrylamide copolymer is low. In addition, there is a problem that fibers with low durability fall off from the felt and adhere to the paper, causing trouble during printing.

  Patent Document 5 has a base, a wet paper side batt fiber layer, and a back side batt fiber layer, the wet paper side batt fiber layer is included in a polymer elastic material, and the back side batt fiber layer is A papermaking felt containing molten fiber is disclosed.

  However, since the polymer elastic material described in Patent Document 5 is an emulsion of a polymer material such as a urethane emulsion or a vinyl acetate emulsion, a polymer of a mixture thereof is used for a papermaking felt, Although the felt was made compact by the adhesive force and setting force of the polymer, it gave rigidity to the entire felt. When the felt stiffness is increased, the compressibility and recoverability of the paper machine under the press are suppressed, so that the wet paper squeezing ability is impaired, and when the paper felt is placed in the paper machine, When inserting felt between narrow rolls by hand, there is a problem that it becomes difficult to insert the felt due to the rigidity of the felt.

  Furthermore, in the felt described in Patent Document 5, since the back side batt fiber layer further contains molten fiber, the back side batt fiber layer can be formed into a high-density flexible layer, and the rewetting suppression effect of the felt can be reduced. Although it can be used as a papermaking felt, it has not been able to achieve a felt that can maintain its space volume appropriately, maintain water permeability and compressibility for a long period of time, and reduce the initial familiarization period of papermaking felts compared to conventional products. It was.

JP 2005-524002 Gazette Japanese Patent Laid-Open No. 2-127585 JP 2005-146443 A JP-A-56-53297 JP 2009-127135 A

  Although the felt of such a known technique shortens the initial familiarization period, the thickness of the felt is reduced from the beginning to reduce the space in the felt. There was a problem that it reached quickly and the wet paper was sufficiently squeezed for a short period.

  Therefore, an object of the present invention is to solve the conflicting problems of shortening the initial familiarization period and ensuring a stable use period.

  Specifically, by including a water-absorbing resin and molten fiber in the press felt for papermaking, the space volume in the felt, which has a poor effect of transmitting pressure and water pressure to the wet paper to be squeezed, has been familiarized from the beginning of use. Providing a press felt for papermaking that shortens the familiarity period by making it an appropriate amount of space, and does not cause poor water expression due to early deterioration of water permeability due to accumulation of dirt or excessive compactness and insufficient compressibility. And

  By including a water-absorbing resin in the papermaking felt, after the water-absorbing resin absorbs water, the space volume in the felt is appropriately secured, and when the molten fiber is melted by heat processing, the molten fiber itself The present invention has been completed by finding that there is sustained compressibility by forming a strong fiber network by welding with vat fibers other than molten fibers or water-absorbing resin. In order to solve the above-mentioned problems, the present invention includes a felt for papermaking composed of a reinforcing fiber base and at least a wet paper stack-side butt layer, wherein the felt contains a water absorbent resin and a molten fiber. It is characterized by.

  The invention of claim 1 is a papermaking press comprising a reinforcing fiber base, a front bat fiber layer disposed on the wet paper web of the reinforcing fiber base, and a back bat fiber layer disposed on the press roll side. In the felt, at least one of the front bat fiber layer and the back bat fiber layer contains 0.5 to 30% by weight of molten fiber with respect to the weight of the papermaking press felt. Is characterized in that a water-absorbing resin having a water absorption ratio of 1.05 to 10 times is dispersed and adhered in an amount of 0.5 to 20% by weight with respect to the weight of the papermaking press felt. Is to provide.

  The invention according to claim 2 is a core in which the molten fiber is composed of a core component made of a high molecular weight polyamide having an absolute viscosity of 80 mPa · s or more, and a sheath component made of polyamide having a lower melting point than the core component. The press felt for papermaking according to claim 1, wherein the press felt is a sheath type composite fiber.

  In the felt for papermaking of the present invention, the water-absorbing resin absorbs water, thereby reducing the space volume in the felt having a poor effect of transmitting pressure and water pressure to the wet paper and shortening the initial acclimatization period. In addition, the flexibility and durability of the resin swollen with water and the strong fiber network formed by the molten fibers maintain the compressibility, so that the water squeezability can be maintained and the elastic sustainability is improved as shown in the examples. It can be made.

FIG. 1 shows a state in which a water-absorbing resin stays in a front bat fiber layer and a molten fiber is arranged in at least one of the front bat fiber phase or the back bat fiber layer in a papermaking press felt. FIG. FIG. 2 shows a papermaking press felt in which a water-absorbing resin is present from the front bat fiber layer to the back bat fiber layer, and the molten fiber is arranged in at least one of the front bat fiber phase or the back bat fiber layer. FIG.

An example of the papermaking felt of the present invention is shown in the figure. In addition, this invention is not restricted to what is shown in the specific example described in this drawing.
The press felt for papermaking of the present invention illustrated in FIGS. 1 and 2 includes a reinforcing fiber base 1, a front bat fiber layer 2 disposed on a wet paper web (front side) of the reinforcing fiber base, and the reinforcing 1 includes a back bat fiber layer 3 disposed on the press roll side (back side) of the fiber substrate, FIG. 1 shows a state in which the water absorbent resin 4 stays in the front bat fiber layer 2, and FIG. The state of reaching from the front bat fiber layer to the back bat fiber layer 3 is shown. And the state where the molten fiber has been arrange | positioned is shown in at least one of the front bat fiber layer 2 and the back bat fiber layer 3, respectively.

Generally, a papermaking felt has a configuration in which a reinforcing fiber base material is sandwiched between bat layers. The reinforcing fiber base is generally a woven fabric obtained by weaving warps and wefts with a loom.
The material of the warp and weft base and vat are polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polyamide (nylon 6, nylon 66, nylon 610, nylon 612, etc.), polyphenylene sulfide, polyvinylidene fluoride, polypropylene, aramid. , Polyether ether ketone, polytetrafluoroethylene, polyethylene, polyvinyl chloride, cotton, wool, metal and the like.

  The water-absorbing resin has a water absorption ratio of 1.05 to 10 times, and those belonging to natural polymers and those belonging to synthetic polymers can be used alone or in combination.

  As a water-absorbing resin belonging to natural polymers, in the case of starch, those obtained by adding a monomer to starch, or those obtained by crosslinking by irradiation with ionizing radiation, such monomers include acrylonitrile, acrylic acid, acrylamide. Commonly known compounds such as methyl methacrylate, vinyl acetate, vinyl sulfonic acid, dimethylaminoethyl methacrylate, sodium monochloroacetate, sodium polyacrylate, epichlorohydrin, styrene sulfonic acid and the like can be used.

  Cellulose-based water-absorbing resins include those obtained by addition reaction of monomers with CMC, or those obtained by crosslinking by irradiation with ionizing rays. Examples of the monomers include acrylonitrile, sodium monochloroacetate, sodium polyacrylate, epichlorohydrin, styrene sulfone. Acids can be used.

  As the polysaccharide water-absorbing resin, it is possible to use a cross-linked product by placing hyaluronic acid or agarose on a polyvalent ion such as boron or aluminum, or by irradiating with ionizing radiation.

  In the PVA system, those belonging to the synthetic polymer water-absorbing resin include those obtained by addition reaction of monomers, and those obtained by crosslinking by irradiation with ionizing rays. As the monomer, acrylic acid, sodium polyacrylate, or the like can be used.

  Examples of the acrylic water-absorbing resin include the following. Acrylamide copolymer (sodium acrylate, acrylic acid, vinyl alcohol, isopropylacrylamide, methylenebisacrylamide, etc. as copolymer monomers) Acrylic acid copolymer (sodium acrylate, acrylonitrile, etc. as copolymer monomers) Methylenebis Acrylamide copolymers (such as methacrylic acid and isopropyl acrylamide as copolymer monomers), methylenebisacrylamide copolymers (such as methacrylic acid and isopropyl acrylamide as copolymer monomers), or cross-linked sodium polyacrylate by ionizing radiation irradiation. In addition, an NC gel prepared by preparing an acrylamide derivative (NIPA, DMAA) monomer with an inorganic component (hectorite) can also be used.

  In urethane-based water-absorbing resins, polyols may be modified by mixing polyisocyanate with polyhydric alcohols, or a hydrophilic polyol in which ethylene oxide and propylene oxide are added and polymerized, and mixed with polyol. As such, a product obtained by mixing a water-absorbing resin such as starch or PVA in a polyol and reacting it with an isocyanate can be used. Among these, those obtained by reacting a polyisocyanate with a hydrophilic polyol obtained by addition polymerization of ethylene oxide (EO) and propylene oxide (PO) are preferable.

  Examples of the polyisocyanate include aromatic, aliphatic, and alicyclic polyisocyanates, such as tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, and naphthalene. Diisocyanate (NDI), hexamethylene diisocyanate and mixtures thereof can be used.

  The polyol is an aromatic hydrophilic polyol obtained by addition polymerization of EO or PO with an aromatic polyhydric alcohol. As the aromatic polyhydric alcohol, 4,4'-dihydroxyphenylsulfone, resorcin, and 1,4-bishydroxyethoxybenzene are preferable. Among them, a polyether polyol in which the content of oxyethylene groups accounts for 40 to 100% of the weight in polyoxyalkylene, and the content of oxypropylene groups is 0 to 30% of the weight in polyoxyalkylene, and has a molecular weight Is preferably obtained by reacting a polyether polyol having a molecular weight of 1000 or less.

  The shape of the water-absorbing resin contained in the bat layer of the papermaking felt is not particularly limited, whether it is a particle or a dispersed film. However, a film that forms a continuous film layer like a sheet after water absorption is not preferable because it impedes water permeability.

The water absorption magnification is measured by the following method.
(1) The weight of the sample (water absorbent resin) when dried at 105 ° C. for 1 hour is measured to the nearest 0.01 g, and this is defined as M ₁ .
(2) An appropriate amount (for example, 100 g) of the sample is put in a non-woven bag, and the non-woven bag is completely immersed in an immersion liquid composed of a sufficient amount of pure water at 20 ° C. ± 2 ° C.
(3) The non-woven bag containing the sample is taken out of the dipping solution every hour for dipping, and is put into a rotary dehydrator (Kumagaya Riki Kogyo sheet former: trade name).
(4) The rotational speed of the sheet former is set to a predetermined speed of 1500 m / min. When the set speed is reached (after 12 seconds), dehydration is performed for a predetermined time (5 minutes).
(5) After dehydration is continued for 5 minutes, the brake is applied to stop centrifugal dehydration. The total weight of the non-woven bag and sample after dehydration is measured to the nearest 0.01 g.
(6) Thereafter, the above (3) Repeat (5), the total weight of the sample and the nonwoven fabric bag when it is no longer the weight gain is defined as M _2.
(7) the only non-woven bag was immersed in pure water, the weight of the measured nonwoven bag by (3) from (5) is defined as S _1,
Formula: Water absorption magnification = (M ₂ −S ₁ ) ÷ M ₁
The value obtained by the above is taken as the water absorption magnification.
The water absorption ratio is preferably 1.05 to 10 times.

  The position at which these water-absorbing resins are contained in the papermaking felt is not particularly limited, but is preferably between the reinforcing fiber base and the wet paper web-side bat layer (front bat fiber layer). . Specifically, only the wet paper web-side butt layer, from the wet paper web-side bat layer to the press roll side bat layer (back bat fiber layer), from the wet paper web-side bat layer to the reinforcing fiber substrate, press There are combinations from the roll side batt layer to the substrate reinforcing fiber substrate.

  As a means for incorporating the water-absorbing resin into the felt, an aqueous dispersion in which water-absorbing resin particles are dispersed in an aqueous solution is applied to the felt by a method such as coating / impregnation, spray spraying, blade coating or the like.

  In order to hold the water-absorbent resin firmly on the felt, a crosslinking agent is used as necessary, and dispersed in the aqueous dispersion and coated, and then subjected to a crosslinking reaction by heating or emitting an electron beam. Examples of such crosslinking agents include polyethylene glycol mono (meth) acrylate, N-methylol (meth) acrylamide, glycidyl (meth) acrylate, polyethylene glycol di (meth) acrylate, N, N-methylenebis (meth) acrylamide, and the like. Examples include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, di- or polyglycidyl ethers of aliphatic polyhydric alcohols, and the like, and mixtures thereof. Moreover, 1 type (s) or 2 or more types can be used for a crosslinking agent.

  A preferable space volume other than the fibers formed in the papermaking felt is to maintain a constant volume from the initial familiarity period to the maximum speed region where the operation speed can be stably produced and to the end of use. Therefore, in view of the operating conditions of the paper machine and the amount of dewatered wet paper, it is preferable to control the rate at which the absorbed resin is removed from the felt.

  The amount of the crosslinking agent used is determined by the reactive group equivalent of the water-absorbent resin (isocyanate group in the urethane water-absorbing resin) and the reactive group (active hydrogen group) equivalent of the crosslinking agent. At that time, in order to control the durability performance after crosslinking, it is adjusted with an appropriate equivalent ratio (-NCO / -H). Specifically, an equivalent ratio of 0.7 to 1.5 is preferable.

  As a raw material of the molten fiber, it is possible to use a whole melt type fiber composed of a single component or a non-total melt type composite fiber (conjugate fiber) composed of two or more components. In the composite fiber, a parallel type or a core-sheath type can be preferably used. Specifically, fibers containing polyethylene (PE), polypropylene (PP), polyester, polyethylene terephthalate (PET), polyamide (PA), copolymerized polyamide, and the like as components are preferable. In the present invention, a core-sheath type composite fiber is particularly preferably used which is a composite fiber composed of two components, in which the core component is polyamide and the sheath component is copolymerized polyamide.

  The polyamide used for the core component of the core-sheath composite fiber is preferably polyamide 6, polyamide 66, polyamide 46, polyamide 610, polyamide 612, or the like. Specifically, polymerization of ε-caprolactam (polyamide 6), polycondensation of hexamethylenediamine and adipate (polyamide 66), polycondensation of 1,4-diaminobutane and adipate (polyamide 46), hexamethylenediamine and sebacine Polyamides obtained by polycondensation such as polycondensation of acid salts (polyamide 610) and polycondensation of hexamethylenediamine and dodecanedioic acid (polyamide 612) are preferred, and the melting point by DSC (differential scanning calorimetry) is 200. Mention may be made of aliphatic polyamides that are at or above ° C.

  As the polyamide used for the sheath component of the core-sheath composite fiber, a polyamide having a lower melting point than that of the core component is used. As polyamides preferably used for the sheath component, polyamide 6/12, polyamide 6/610, polyamide 66/6, polyamide 66/12, polyamide 66/610, etc. binary copolymer polyamide, polyamide 6/66/12, polyamide Mention may be made of terpolymer polyamides such as 6/66/610. It is well known that the melting point of these copolymer polyamides varies depending on the composition (% by weight of copolymer component), but the copolymer polyamides usable in the present invention have a melting point of 180 ° C. or less. Can be particularly preferably used.

  Further, the core-sheath type composite fiber comprises a core component made of a high molecular weight polyamide having an absolute viscosity of 80 mPa · s or more, and a sheath component made of polyamide having a lower melting point than the core component. It is preferably a fiber.

  Here, the absolute viscosity of 80 mPa · s or more is an absolute viscosity measured at a temperature of 25 ° C. by dissolving polyamide in 100 ml of 0.5 g / 95% sulfuric acid, and can be measured with a vibration viscometer. .

  The molten fiber is obtained by blending the short fibers (staple fibers) of the molten fibers with the general short fibers (staple fibers) constituting the front bat fiber layer and the back bat fiber layer to form a bat raw material. This is a fiber body in which a felt is formed by entanglement and integration with a material by needle punching, and then a part of the molten fiber is melted by heat treatment to be fused with a general short fiber inside the bat layer. Here, the general short fibers are polyamide 6, polyamide 66, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), engineering polyamide (polyamide 11, polyamide 12, polyamide), which are usually used as the material for the butt layer of papermaking felt. 612), aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, cotton, wool and the like.

  The preferred amount of the molten fiber used is 0.5 to 30% by weight based on the weight of the papermaking press felt. Since there is little fiber weld formation, the space volume in the felt cannot be properly secured, and the water permeability and compressibility cannot be maintained over a long period of time, resulting in poor felt durability. Further, if the amount of the molten fiber used is more than 30% by weight based on the weight of the felt, the rigidity of the felt becomes high and the thickness deformation resistance cannot be reduced. Is difficult to increase, and the recoverability after pressurization may be lowered.

  The position where the molten fiber is disposed in the papermaking press felt may be such that the molten fiber is disposed in at least one of the front bat fiber layer 2 and the back bat fiber layer 4. That is, the molten fiber may coexist with the water absorbent resin in the batt layer. In the present invention, in order to provide a felt that can secure an appropriate amount of space for the initial familiarity from the initial use of the felt and shorten the felt familiarization period within about 4 days, By combining and adjusting the blending amount and the amount of water-absorbing resin well combined, the thickness deformation resistance of the felt is reduced, and when pressed with a press roll or shoe press, the pressure density tends to increase, and after pressurization In addition, it is possible to produce a felt that can maintain water permeability and compressibility for a long period of time without causing accumulation of dirt and excessive flattening.

  The method of attaching a water-absorbing resin to the short fibers that make up the batt fibers (general short fibers and short fibers of molten fibers) is to apply a solvent dispersion of a polymer elastic body to the felt surface, spray spray, blade coating, etc. Then, it is applied and impregnated by the following means, and then heat treated and dried to adhere. At this time, a part of the binder fiber is melted at the same time, and general short fibers, molten fibers, and polymer elastic bodies are fused in the vat fiber layer.

Hereinafter, the present invention will be described with reference to examples and comparative examples. The present invention is not limited to these examples.
Examples 1-9, Comparative Examples 1-3
The basic structure of the papermaking felt used in this example and the comparative example is as follows.
Reinforcing fiber substrate (twisted polyamide monofilament, plain weave): basis weight 750 g / m ²
Batt fiber layer: A blended cotton fiber in which polyamide 6 staple fibers of 17 dtex and molten fibers were blended in the blending amounts shown in Table 1 was used.
Melt fiber: High molecular weight polyamide 6 (absolute viscosity at 25 ° C., 85 mPa · s, melting point 220 ° C.) as the core material and copolymer polyamide 6/12 (melting point 140 ° C.) as the sheath material, Core-sheath type composite fiber having a volume ratio of 1: 1 Reinforcing fiber base on wet paper web (front bat fiber layer): basis weight 500 g / m ²
Press roll side of the reinforcing fiber base (back bat fiber layer): basis weight 250 g / m ²
After a bat fiber on the back side and a bat fiber on the front side are laminated on the reinforcing fiber base material and entangled and integrated by needling to form a felt, the water absorbent resin composition shown in Table 1 is applied to the surface bat side of the felt. And dried at 105 ° C. for 60 minutes and then cured (heat cured) at 140 ° C. for 30 minutes.

  The papermaking felts obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to the following running test conditions; 1000 m / min, roll pressurization 100 kN / m, 100 hours, and the paper pressing felt water squeezing and elasticity Sustainability and water sustainability were evaluated.

Squeezing test; high-speed press tester squeezing test conditions: pressurization 100 kN / m, paper making speed 1000 m / min wet paper content before press; 70%
Pre-press wet paper moisture content = (pre-press wet paper weight−dry paper weight) ÷ pre-press wet paper weight × 100
Wet paper moisture content after pressing = (wet paper weight after pressing−dry paper weight) ÷ wet paper weight after pressing × 100
The lower the wet paper moisture content after press, the better the water squeezing felt. In the paper industry, even if the wet paper moisture content after press is 1%, the heat energy in the drying process of the paper after press. It has a great influence on the quantity.

Compression test; felt thickness before high-speed press tester press; T ₀
Felt thickness under press; T ₁ (100 kN / m)
Felt thickness after pressing; T ₂
Compression rate (%) = (T ₀ −T ₁ ) ÷ T ₀ × 100
Thickness retention (%) = (T ₂ ÷ T ₀ ) × 100

Drainage test; drainage tester drainage value; pressure 20 MPa. Time required for 5 liters of water to flow from a side without a metal plate at a water pressure of 3 MPa from a side without a metal plate by placing a metal plate on one side of a 120 mmφ felt sample.
The shorter this time, the better the water permeability.
Drainage retention rate (%) = drainage value before running test ÷ drainage value after running test x 100
The results are shown in Table 2.

  Table 2 shows that the smaller the value of the wet paper moisture content after pressing, the better the water squeezing, and the larger the value of the compression ratio during pressing and the thickness retention before and after pressing, the better the elastic sustainability. In the papermaking felts of Examples 1 to 9, it can be seen that the squeezing property and the elastic sustainability are improved by the swelling of the water-absorbing resin contained therein. Moreover, although the felt for papermaking of Examples 1-9 has shown the value with a high drainage persistence rate, this is obstruct | occluded the excess space at the time of a new article with a water absorbing resin, and resin is gradually used with use. This is because the proper water permeability is exhibited from the beginning to the end of use by dropping off. Moreover, when the molten fiber is welded to the water-absorbent resin and the bat fiber, it is possible to obtain a papermaking press felt that is less likely to drop off the bat fiber and has excellent hair removal resistance.

    The present invention can improve the water squeezability of wet paper for the entire period of use, including the initial familiarization period, until reaching the maximum speed at which stable production of the paper machine can be achieved, and the installation in the paper machine is as usual. A papermaking press felt that can be loaded can be obtained, which is practically useful in the paper industry.

DESCRIPTION OF SYMBOLS 1 ... Base material 1a ... Warp (MD yarn)
1b Weft (CMD yarn)
2 ... front bat fiber layer 3 ... back bat fiber layer 4 ... water-absorbent resin layer

Claims (2)

  In the press felt for papermaking, comprising a reinforcing fiber substrate, a front bat fiber layer disposed on the wet paper web mounting side of the reinforcing fiber substrate, and a back bat fiber layer disposed on the press roll side. At least one of the layer and the back bat fiber layer contains 0.5 to 30% by weight of molten fiber with respect to the weight of the papermaking press felt, and the front bat fiber layer has a water absorption ratio of 1. A press felt for papermaking, characterized in that a water-absorbing resin having a ratio of 05 to 10 times is dispersed and adhered in an amount of 0.5 to 20% by weight based on the weight of the press felt for papermaking.   The molten fiber is a core-sheath type composite fiber composed of a core component made of high molecular weight polyamide having an absolute viscosity of 80 mPa · s or more and a sheath component made of polyamide having a lower melting point than the core component. The press felt for papermaking according to claim 1, wherein:

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