JP2022151155A - Papermaking felt - Google Patents

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

The present invention relates to a papermaking felt used in the press part of a paper machine.

In the press part of a paper machine, when the wet paper is pressurized between a pair of press rolls and water is squeezed out, the felt is passed through the press rolls together with the wet paper. Used to smooth surfaces.
Felts for papermaking include woven fabrics woven by crossing warp and weft, non-woven fabrics formed by arranging threads without weaving, and polymer films and sheets made breathable by perforating or foaming. etc. are used singly or in combination as a base fabric, and batt fibers are laminated on both sides of this base fabric.
In addition, papermaking felt is required to improve the quality of paper to be manufactured and to further improve productivity by increasing the speed of papermaking. There is a demand for more excellent properties such as the following. In order to satisfy this demand, in recent years, paper-making felts that have undergone resin processing have been widely used.
Resin processing is performed, for example, by imparting one or more types of resin (mainly polyurethane resin) dispersed in water or the like to papermaking felt by a method such as impregnation. Resin processing has the advantage of improving various properties such as water squeezing, initial conformability, and compression resistance of the felt for papermaking.
However, since resin processing increases the flexural rigidity of the papermaking felt and hardens the papermaking felt, it causes difficulty in inserting into the paper machine (hereinafter also referred to as "insertability" for short). It also has disadvantages such as ease of use.
For this reason, for example, Patent Literature 1 discloses a method of applying a softening agent to a papermaking felt after resin processing for surface treatment.

JP 2017-150101

By applying a softening agent to the surface of the felt, the softness of the papermaking felt is improved, that is, it becomes softer. Therefore, it is possible to further improve the ease of insertion into the paper machine.
However, as the amount of softening agent applied to paper felt increases, the durability of the resin imparted by resin processing decreases, and the resin tends to fall out of the felt. A problem arises that it is difficult to obtain.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a papermaking felt which can be easily installed in a paper machine and which can preferably enjoy the merits of resin processing. .

The inventors of the present invention have repeatedly conducted tests in order to meet the demands for improved insertion into the paper machine and improved durability of the resin. It has been found that by imparting the flexural rigidity of the felt for papermaking, the flexural rigidity is lowered and the insertability is improved.
The present invention is as follows.
1. A papermaking felt coated with a polyurethane resin and provided with a softener,
A papermaking felt, characterized in that the weight ratio of said softening agent to said polyurethane resin (weight of softening agent/weight of polyurethane resin) is in the range of 0.024 to 0.090.
2. The papermaking felt according to claim 1, wherein said softening agent comprises a surfactant.
3. The papermaking felt according to claim 2, wherein the surfactant is a nonionic surfactant.
4. A base fabric layer and a front batt layer disposed on the paper-making side of the base fabric layer,
The papermaking felt according to any one of claims 1 to 3, wherein the front batt layer includes a surface layer portion containing fibers bound with the polyurethane resin, and the softener is applied to the surface layer portion. .

According to the papermaking felt of the present invention, it is possible to preferably enjoy the merits of resin processing while improving the ease of insertion into a paper machine.

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 mentioned drawings, wherein like reference numerals indicate Similar parts are shown throughout the several figures.
FIG. 4 is a schematic diagram showing another example of the cross-sectional structure of the papermaking felt of the present invention. FIG. 3 is an explanatory diagram showing a measuring device for measuring a weft bending stiffness value; 1 is a graph showing the relationship between the weight ratio of a softening agent to a polyurethane resin, the resin residual ratio, and the weft bending change ratio of the felt for papermaking obtained in Examples.

The material presented herein is intended to be illustrative and illustrative of the embodiments of the invention and is the description that most effectively and readily understands the principles and conceptual features of the invention. It is described for the purpose of providing what is believed to be In this regard, no attempt is made to show structural details of the invention beyond that which is necessary for a fundamental understanding of the invention, and the description in conjunction with the drawings may illustrate some aspects of the invention. It will be clear to those skilled in the art how it is actually implemented.

[1] Papermaking felt The present invention provides a papermaking felt coated with a polyurethane resin and to which a softening agent is added, wherein the weight ratio of the softening agent to the polyurethane resin (weight of softening agent/weight of polyurethane resin) weight) is in the range of 0.02 to 0.09.
Further, in the papermaking felt of the present invention, the weight ratio of the softener to the polyurethane resin may be in the range of 0.03 to 0.09.

The papermaking felt of the present invention can have, for example, the configuration shown in FIG.
That is, as shown in FIG. 1, the papermaking felt 1 includes a base fabric layer 11, a front batt layer 13 disposed on the papermaking surface side of the base fabric layer 11 (upper surface side in FIG. 1), and a base fabric layer. 11 and a back batt layer 15 disposed on the running surface side (lower surface side in FIG. 1).
The front batt layer 13 comprises fibers bound with a polyurethane resin 19 . When the front batt layer 13 has an inner layer portion 13A on the inner side of the base fabric layer 11 and a surface layer portion 13B on the outer side of the paper manufacturing surface, a softening agent (not shown) is dispersed mainly inside the surface layer portion 13B. given in the state.
The papermaking felt 1 is integrated as a whole by entangling each layer such as the base fabric layer 11, the front batt layer 13, the back batt layer 15, etc. in the stacking direction.

Note that the papermaking felt 1 may have a configuration in which the back batt layer 15 is omitted, for example.
Further, the front batt layer 13 of the papermaking felt 1 can have a multi-layer structure such as having two layers of an inner layer portion 13A and a surface layer portion 13B.
When the front batt layer 13 has a multilayer structure, an additional batt layer may be provided between the inner layer portion 13A and the surface layer portion 13B.

(1) Base fabric layer The base fabric layer can be derived from the base fabric used for the felt for papermaking, and can usually be made of threads.
Yarn materials include polyamide resins such as nylon 6, nylon 66, nylon 610 and nylon 612; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; synthetic resins such as polyolefin resins such as polyethylene and polypropylene; cotton, wool, silk, etc. can be exemplified.
Among the exemplified materials, the polyamide resin is particularly preferable as a material for the thread constituting the base fabric layer from the viewpoint that the papermaking felt can be made excellent in abrasion resistance, compression recovery, impact resistance, and the like.

Yarn forms include monofilament, multifilament, spun yarn, crimped, bulky textured yarn, bulky yarn, stretch yarn, etc., and twisted yarn made by twisting these yarns. can be
The cross-sectional shape of the thread may be circular, substantially elliptical, polygonal, substantially star-shaped, substantially rectangular, or the like.
A hollow fiber can also be used as the thread.

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

The number of yarns constituting the base fabric layer may be one, or two or more.
The threads forming the base fabric layer may have an appropriate material, shape, diameter, etc., according to the strength, porosity, air permeability, pressure uniformity, and other properties of the papermaking felt.

The structure of the base fabric layer is not particularly limited, and may be either a single layer structure or a multilayer structure.
In the case of a multi-layer structure, it consists of a multi-woven base fabric consisting of at least two layers formed by weaving at least two warps and two or more wefts, and a plurality of different types of base fabrics are laminated. It can be a thing, etc.
Moreover, the structure of the base fabric layer can have a structure in which threads are arranged in the warp direction, the weft direction, or the oblique direction.
The base fabric layer can also be a polymer film or sheet subjected to perforation processing, foaming processing, or the like.

The thickness of the base fabric layer is not particularly limited, and can be preferably 0.2 mm to 3.5 mm, more preferably 0.4 mm to 2.0 mm.
The basis weight of the base fabric layer is not particularly limited, and can be preferably 150 g/m ² to 1500 g/m ² , more preferably 250 g/m ² to 1200 g/m ² .
The thickness and basis weight of the base fabric layer are appropriately set according to the strength, porosity and air permeability of the papermaking felt, and the properties such as the mark prevention property of the base fabric.
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 thickness and basis weight of each layer in the case of a multi-layer structure.

(2) Front batt layer The front batt layer is a layer composed of fibers (hereinafter also referred to as "front batt fibers"), and is disposed on the paper-making side of the base fabric layer. It has the effect of conveying while maintaining smoothness.
The structure of the front batt layer is not particularly limited, and may be either a single layer structure or a multilayer structure.

Materials for the front 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; synthetic resins such as polyolefin resins such as polyethylene and polypropylene; Silk etc. can be illustrated.
Among the exemplified materials, polyamide resin is preferable as the material for the front batt fiber from the viewpoint of abrasion resistance, compression recovery, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, and the like.

The fineness of the front batt fibers is usually 0.1 dtex to 100 dtex.
When the front batt layer has a multi-layer structure, the fineness of the front batt fibers can be the same or different between the inner layer portion 13A and the surface layer portion 13B shown in FIG. 1, for example.
Generally, the fineness of the front batt fibers contained in the inner layer portion 13A can be 3 dtex to 150 dtex, and the fineness of the front batt fibers contained in the surface layer portion 13B can be 0.1 dtex to 100 dtex.

The basis weight of the front batt layer is preferably 100 g/m ² to 1,500 g/m ² , more preferably 300 g/m ² to 1,200 g/m 2 as a whole, regardless of whether it has a single-layer structure or a multi-layer structure. m ² , more preferably 400 g/m ² to 1,000 g/m ² .
The fineness of the front batt fiber and the basis weight of the front batt layer are appropriately set according to the properties such as the strength, porosity and air permeability of the papermaking felt and the surface property of the front batt layer.

(3) Back batt layer The papermaking felt of the present invention can further include a back batt layer 15 on the running surface side of the base fabric layer 11 opposite to 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 protecting the base fabric layer from abrasion, thereby improving the durability as a papermaking felt.

The material of the back batt fiber is not particularly limited, and like the front batt fiber, polyamide resins such as nylon 6, nylon 66, nylon 610, and nylon 612; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Synthetic resin such as polyolefin resin, cotton, wool, silk, and the like can be used.
The fineness of the back batt fibers is usually 3 dtex to 150 dtex.
The basis weight of the back batt layer is usually 50 g/m ² to 500 g/m ² .

(4) Polyurethane resin The papermaking felt of the present invention is coated with a polyurethane resin.
This polyurethane resin controls the air permeability (water squeezing) in the cross-sectional direction of the papermaking felt to an appropriate range, and by imparting an appropriate hardness to the surface layer, it improves the water squeezing of the papermaking felt and the initial conformability. It is applied for the purpose of improving compression resistance, etc. In other words, the papermaking felt can enjoy benefits such as improved water squeezability, improved initial conformability, and improved compression resistance by being subjected to resin processing in which the fibers are coated with a polyurethane resin.
As a specific example, as shown in FIG. 1, the papermaking felt 1 includes fibers 17 bound with a polyurethane resin 19 in the inner layer portion 13A and the surface layer portion 13B of the front batt layer 13 .

The form of binding of the polyurethane resin to the fibers can be either a form in which the polyurethane resin adheres to the fibers or a form in which the fibers are joined together by the polyurethane resin.
In addition, the form in which the polyurethane resin joins the fibers together is the form in which the polyurethane resin knots the fibers extending in the orthogonal or intersecting direction at the intersection of each other, and the polyurethane resin that has entered between the plurality of fibers connects the fibers. Any form of adhesion is possible.

The fibers to which the polyurethane resin is bound are not necessarily limited to being included in the inner layer portion 13A and the surface layer portion 13B of the front batt layer 13, as illustrated in FIG.
That is, if the papermaking felt 1 is coated with a polyurethane resin, the fibers bound with the polyurethane resin are included only in the surface layer portion 13B of the front batt layer 13, or the front batt layer 13 and a form included in the base fabric layer 11 .

A polyurethane resin is synthesized using a polyol (hydroxyl group) and an isocyanate compound (isocyanate group) as main raw materials. The types of polyols and isocyanate compounds used as main raw materials are not particularly limited.
Examples of polyols include polyester-based polyols, polyether-based polyols, polycarbonate-based polyols, polyolefin-based polyols, and the like, and any of them may be used. Examples of isocyanate compounds include aromatic isocyanate compounds, aliphatic isocyanate compounds, and alicyclic isocyanate compounds, any of which may be used.
The polyurethane resin can be a resin synthesized only from the main raw material described above, or a mixture obtained by mixing the main raw material with auxiliary raw materials such as catalysts and cross-linking agents, and additives such as colorants and stabilizers. A resin synthesized from can also be used.

A papermaking felt is obtained by using a base fabric layer, a front batt layer, etc., which are integrated by being entangled or the like, as a base fabric, and applying resin processing to coat the base fabric layer with a polyurethane resin.
Hereafter, in the felt for papermaking, the felt is formed from an integrated material such as a base fabric layer and a front batt layer, and is not subjected to resin processing or softening processing. A felt that has not been lapped is referred to as a "raw felt".
Moreover, the felt which is only subjected to resin processing on the original felt fabric and is not subjected to softening processing is referred to as "resin-processed felt".

The type of polyurethane resin used for resin processing is not particularly limited, and any of foams such as flexible polyurethane foams and rigid polyurethane foams, and non-foams such as thermoplastic elastomers, thermosetting elastomers and paints can be used. be able to.
The state of the polyurethane resin used for resin processing is not particularly limited, but is usually liquid. The method for obtaining the liquefied polyurethane resin is not particularly limited, and known methods can be applied. It has the advantage that it is easy to resin-process the felt material.

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

Specifically, in the papermaking felt 1 shown in FIG. 1, the softener is applied to the surface layer portion 13B including fibers bound with the polyurethane resin 19, although not shown.
The surface layer portion 13B is provided with appropriate flexibility by applying a softening agent while enjoying the merit of being coated with the polyurethane resin 19 .

The mode of application of the softening agent includes a mode in which the softening agent is adsorbed or attached only to the fiber, a mode in which the softening agent is adsorbed or attached to the resin and the fiber of the fiber to which the polyurethane resin is bound, and a mode in which the softening agent is adsorbed or attached to the gap between the fibers. It can also be in any form in which an agent is entrapped.
Further, the softening agent is not necessarily limited to the form in which it is applied only to the surface layer of the front batt layer. and the inner layer portion, or may be applied to the front batt layer and the base fabric layer.

As the softening agent, a softening agent containing a surfactant can usually be used.
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 becomes a so-called lubricating oil. It works like , weakening the frictional resistance between fibers and improving the slippage, thereby improving the flexibility of the felt for papermaking.
The surfactant is not particularly limited, and one or two selected from ionic surfactants such as anionic surfactants, cationic surfactants, and amphoteric surfactants, and nonionic surfactants. The above can be used.
Among these surfactants, nonionic surfactants have hydrophilic groups (hydroxyl groups and ether bonds) that do not dissociate into ions in an aqueous solution, and do not ionize, so they are less susceptible to water hardness and electrolytes. Since it can be used together with an ionic surfactant, it is preferable as a surfactant contained in a softening agent.

The softening agent may be a softening agent consisting only of a surfactant (preferably a nonionic surfactant), or a softening agent made by adding an additive to a surfactant (preferably a nonionic surfactant). It may be an agent.
Additives are not particularly limited, and additives used in known softeners such as antistatic agents and coloring agents can be used.

Further, as the additive, a resin of the same type as the fiber material used for the felt material can be used. This resin of the same type is preferably further provided with a hydrophilic group. For example, when the fiber material used for the felt material is a polyamide resin, the additive may be a polyamide resin having a hydrophilic group.
When the same type of resin is used as the additive, the same type of resin has a high affinity with the fibers used in the felt material, so that a film can be formed on the surface of the fibers.
Further, when a hydrophilic group is added to the resin of the same type, it can serve as a mediator for adsorbing the surfactant to the surface of the fiber used in the felt material.
For this reason, when using the same resin as the fiber used in the felt material, especially the same resin with a hydrophilic group, as an additive, the flexibility of the papermaking felt can be improved. The increased hydrophilicity makes it easier for water to permeate the fibers, making it easier to remove stains and improving the antifouling properties of the felt for papermaking.

(6) Composition and physical properties [weight ratio]
In papermaking felts, the weight ratio of softener to polyurethane resin ranges from 0.024 to 0.090. In this case, the papermaking felt can improve the durability of the polyurethane resin while improving the insertability into the paper machine.
Also, the weight ratio is preferably in the range of 0.035 to 0.080, more preferably in the range of 0.050 to 0.070.
For the weight ratio, the coating amount (basis weight) of the polyurethane resin applied to the papermaking felt is defined as the weight Wp (g/m ² ) of the polyurethane resin, and the applied amount (basis weight) of the softener applied to the papermaking felt is Amount) is the weight of the softener Ws (g/m ² ), and the value is obtained by the formula of weight ratio=Ws/Wp.

[Resin coating amount]
The coating amount (Wp) of the polyurethane resin (hereinafter abbreviated as "resin coating amount (Wp)") is not particularly limited, and the water squeezability, initial conformability, compression resistance, etc. required for the papermaking felt. It is appropriately set according to the performance.
The resin coating weight (Wp) is obtained by measuring the basis weight (g/m ² ) of the polyurethane resin coated on the papermaking felt.
Specifically, the resin coating weight (Wp) can be preferably 10 g/m ² to 100 g/m ² , more preferably 20 g/m ² to 90 g/m ² .

[Amount of softening agent applied]
The amount of softener applied (Ws) (hereinafter abbreviated as "softener applied amount (Ws)") is not particularly limited, and the amount of papermaking felt to be inserted into a paper machine, the durability of polyurethane resin, etc. It is appropriately set according to the performance.
The softening agent application amount (Ws) is obtained by measuring the basis weight (g/m ² ) of the solid content of the softening agent applied to the papermaking felt.
Specifically, the softening agent application amount (Ws) is preferably 2 g/m ² to 10 g/m ² , more preferably 2.5 g/m ² to 8.5 g/m ² , still more preferably 3 g/m ² to It can be 6.5 g/m ² .

[resin residual rate]
The ability of the papermaking felt to resist detachment of the resin can be represented by the resin residual rate (%).
That is, during papermaking, a papermaking felt is directly subjected to external mechanical forces such as repeated compression, showering, and suction on its surface (front batt layer). When a paper felt is subjected to mechanical external force, the resin (polyurethane resin in this application) applied to the felt deteriorates over time and peels off from the fibers, causing the resin to detach. may not be able to enjoy
In other words, it is difficult to fully enjoy the merits of resin processing for paper felts that tend to detach resin as they are used in paper machines, and those that do not easily detach resin can benefit from resin processing. can be suitably enjoyed.

The resin residual ratio (%) is a value indicating the ability of the papermaking felt to resist detachment of the resin, in other words, the durability of the resin with respect to detachment from the papermaking felt. Specifically, the resin residual ratio (%) in the present application is a value obtained by subjecting a papermaking felt to a durability test described later and measuring the amount of residual polyurethane resin in the papermaking felt.
Specifically, a value calculated from the formula: [(Wp−W _L1 )/Wp]×100 using the above-described resin coating amount (Wp) and resin dropout amount (W _L1 ; g/m ² ). is the residual resin ratio (%) (resin residual ratio (%)=[(Wp−W _L1 )/Wp]×100).
In addition, the resin dropout amount ( _WL1 ; g/m ² ) is the weight of the papermaking felt before the durability test (basis weight; g/m ² ) and the weight after the durability test (basis weight; g/m ² ) is measured, and the amount of change in weight before and after the durability test is calculated (W _L1 =weight after durability test−weight before durability test).

The resin residual ratio (%) is not particularly limited, and is appropriately set according to the paper machine insertability required for the papermaking felt so that the merits of resin processing can be favorably received.
Specifically, the lower limit of the residual resin ratio (%) is preferably 80% or higher, more preferably 82% or higher, and even more preferably 84% or higher. Normally, the upper limit of the resin residual rate (%) is 100%.

[Weft bending change rate]
The papermaking felt can be expressed by the rate of change in weft bending (%) with regard to the insertability into a paper machine.
That is, the papermaking felt to which the softening agent is added changes so that the bending stiffness value (g/cm) decreases as the flexibility improves, and the change in the bending stiffness value (g/cm) When it is large, the flexibility is greatly improved, and the hookability is improved.
Therefore, the rate of change between the bending stiffness value (g/cm) of the papermaking felt before applying the softening agent and the bending stiffness value (g/cm) of the papermaking felt after applying the softening agent, In other words, depending on the bending change rate (%), if the bending change rate (%) is high, the penetration is high, and if the bending change rate (%) is low, the penetration is low. can be represented.
The above-mentioned bending stiffness value (g/cm) was measured using a measuring device (see FIG. 2). ) shall be measured.

Here, the measurement of the weft bending stiffness value (g/cm) will be described in detail.
As shown in FIG. 2, the device for measuring the weft bending stiffness value has a load meter 21 for measuring the bending stiffness value, and a pedestal 22 on which the measurement object 1 (papermaking felt or felt material) is placed. The load meter 21 measures the load applied from the papermaking felt 1 disposed below, and specifically, "Handheld Digital Force Gauge DFG-50R (trade name)" manufactured by Nidec-Shimpo Corporation. is used.

The papermaking felt 1 whose weft bending stiffness value is to be measured has the warp direction or the machine direction as the warp direction (MD direction in the figure), and the direction perpendicular to the warp direction as the weft direction (CMD direction in the figure). With the surface on which the front batt layer is provided as the surface, it is folded in half in the weft direction so that the surface faces inward.
At the time of 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 while being folded in half in the weft direction. Then, the load meter 21 is lowered until the distance from the pedestal 22 becomes 1 cm, and the load meter 21 is pressed against the papermaking felt 1 . Weft bending stiffness value (g/cm).

The weft bending change rate (%) is obtained by taking the measured weft bending rigidity value of the felt material as F ₀ (g / cm) and the measured weft bending rigidity value of the resin-processed felt or papermaking felt as F ₁ (g / cm), and the rate of change in weft bending (%)=(F ₁ /F ₀ )×100.
The rate of change in weft bending (%) is not particularly limited, and is appropriately set so as to improve the insertability into a paper machine within a range in which the papermaking felt can enjoy the merits of resin processing.
Generally, the upper limit of the rate of change in weft bending (%) is preferably 115% or less, more preferably 110% or less, and even more preferably 105% or less.
If the rate of change in weft bending (%) is less than 100%, the weft bending rigidity value is lower than that of the felt material that is not resin-treated, so that it is difficult to enjoy the benefits of resin treatment.

[2] Manufacturing method of papermaking felt The manufacturing method of papermaking felt consists of a resin processing step in which a polyurethane resin is applied to a felt raw fabric to obtain a resin-processed felt, and a softening agent is applied to the resin-processed felt for papermaking. and a softening process for obtaining felt.
Each step will be described below.

(1) Resin processing step The resin processing step is a step of applying a polyurethane resin to a felt raw fabric to obtain a resin processed felt.
Specifically, resin processing involves applying or impregnating a felt material with a dispersion obtained by dispersing a polyurethane resin in water (hereinafter referred to as "aqueous dispersion"), drying, heating, and removing the felt material. It is carried out by binding polyurethane resin to the opposite fibers.

The felt raw fabric includes a base fabric layer and a first fiber layer that serves as a front batt layer, and if necessary, a second fiber layer that serves as a back batt layer is provided on the opposite side of the first fiber layer. good too.
The felt raw fabric is preferably an integrated product in which the base fabric layer, the first fiber layer, and the like are entangled by needling or the like.

For the base fabric layer, the description of "(1) base fabric layer" in the above-mentioned "[1] papermaking felt" is applied.
The first fiber layer may be either a single-layer type or a multi-layer type, and the description of "(2) Front batt layer" in the above-mentioned "[1] Felt for papermaking" is applied. In the first fiber layer, both the fineness of the fibers in the case of a single layer type and the fineness of the fibers constituting the outermost layer in the case of a multi-layered type are obtained by applying the polyurethane resin after applying the aqueous dispersion. It is preferably from 0.1 to 100 dtex, more preferably from 0.3 to 70 dtex, even more preferably from 1 to 50 dtex, and particularly preferably from 2 to 30 dtex, because the retention of the particles is improved.
When the felt material has the second fiber layer, the description of "(3) Back batt layer" in the above-mentioned "[1] Felt for papermaking" is applied to the second fiber layer.

The form of the aqueous dispersion may be an emulsion or the like. However, since the thickness of the binding portion (surface layer portion 13B) containing the polyurethane resin can be easily controlled, it is preferred that the dispersion be a dispersion in which the polyurethane resin is dispersed in water. is preferred.
The aqueous dispersion may consist of only the polyurethane resin, or may further contain additives.

In the resin processing step, the method of applying the aqueous dispersion to the surface of the felt material is not particularly limited, and spray coating, roll coating, or the like can be applied.
The amount of the aqueous dispersion to be applied is appropriately selected depending on the solid content concentration, viscosity, etc. of the aqueous dispersion, and is not particularly limited.

In the resin processing step, the felt raw fabric coated with the water dispersion is dried by heat treatment to remove water, which is the main medium of the water dispersion, and the polyurethane resin contained in the water dispersion becomes the first fiber layer. attached to the fibers of
The heating temperature in the heat treatment is preferably 100°C to 170°C, more preferably 120°C to 150°C.

(2) Softening process The softening process is a process of applying a softening agent to the resin-processed felt to obtain a papermaking felt.
Specifically, in the softening process, a softening agent solution (hereinafter referred to as "treatment liquid") obtained by diluting the undiluted softening agent with water is applied or impregnated on the resin-processed felt, dried, and It is carried out by applying a softening agent to the resin-processed felt.

In the softening process, the softening agent can be used as it is, but from the viewpoint of ease of application or impregnation to the resin-processed felt, a treatment liquid obtained by diluting the undiluted softening agent with water is used. preferably.
The treatment liquid may consist of only a softening agent and water, or may further contain additives.
The concentration of the softening agent contained in the treatment liquid is not particularly limited, and can be appropriately set according to the viscosity of the softening agent and the like.

In the softening process, the method of coating or impregnating the resin-processed felt with the treatment liquid is not particularly limited, and spray coating, roll coating, or the like can be applied.
The amount of the treatment liquid to be applied or impregnated can be appropriately selected according to the concentration and weight ratio of the softener.

In the softening process, the resin-finished felt coated or impregnated with the treatment liquid is dried, and the softening agent contained in the treatment liquid is adsorbed on the fibers. It is considered to be felt for papermaking.
A method for drying the resin-processed felt is not particularly limited as long as it removes water, which is the main medium of the treatment liquid. In this drying, drying temperature, pressure and the like are not particularly limited.

EXAMPLES The present invention will be specifically described below with reference to examples.
[Manufacturing of original felt fabric]
A woven fabric (basis weight: 273 g) obtained by weaving a monofilament twisted yarn (nylon 6, fiber diameter: 0.2 mm) and a monofilament single yarn (nylon 6, fiber diameter: 0.25 mm) in a single weave structure. /m ² ) was used as the first base fabric layer.
Monofilament single yarn (nylon 6/10, fiber diameter: 0.4 mm) and monofilament single yarn (nylon 6, fiber diameter: 0.4 mm) are used to weave in a double weave structure. amount; 583 g/m ² ) was used as the second base fabric layer.
The first base fabric layer and the second base fabric layer are superimposed in the thickness direction, the first base fabric layer side is the papermaking surface side, the second base fabric layer side is the running surface side, and the base fabric ( A base fabric layer) was obtained.

On the paper-making side of the above-mentioned base fabric (base fabric layer), the staple fiber (nylon 66, ^average fineness: Fineness: 31 dtex) was arranged at a basis weight of 234 g/m ² to form the first fiber layer.
Further, staple fibers (nylon 66, average fineness: 51 dtex) were placed at a basis weight of 190 g/m ² on the running surface side of the base fabric (base fabric layer) to form a second fiber layer.

The base fabric (base fabric layer), the first fiber layer, and the second fiber layer are entangled and integrated by needle punching, and further pressed to form the base fabric layer, the front batt layer, and the back. A felt raw fabric was produced in which the batt layer was integrated.
A flexural rigidity test was performed on the obtained felt material, and the weft bending rigidity value was 1362.3 g/cm (see "Felt material" in Table 1).

[Resin processing process]
An aqueous polyurethane dispersion solution was adjusted to have a solid content concentration of 8% by mass to obtain an aqueous dispersion.
The above-described felt material is set in a finishing machine, and the water dispersion is sprayed on the paper-making surface side (front batt layer side) of the felt material so that the application amount (basis weight) is 1000 g / m ² . did. After that, the felt raw fabric is dried at 130°C, and then hot air is blown at 150°C to melt the polyurethane resin, thereby producing a resin-processed felt in which the polyurethane resin is bound to the fibers of the surface layer of the front batt layer. Obtained.
This resin-processed felt had a polyurethane resin coating weight (Wp) of 80 g/m ² (see "Experimental Example 0" in Table 1).

[Softening process]
A nonionic surfactant ("Inobesol NY-30" (trade name) manufactured by Lion Specialty Chemicals) is used as a stock solution, diluted with water so that the concentration of the stock solution is 5% by mass, and adjusted to obtain a treatment solution. rice field.
The above-described resin-processed felt (Experimental Example 0) was set in a finishing machine, and the treatment liquid was applied to the paper-making side (front batt layer side) of the resin-processed felt (Experimental Example 0) in a predetermined amount. sprayed on.
The application amount of the treatment liquid was appropriately changed and adjusted for each Experimental Example so that the applied amount of the softener (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 a papermaking felt (Experimental Examples 1 to 8) coated with a polyurethane resin and provided with a softening agent.
The resulting felts for papermaking (Experimental Examples 1 to 8) had a resin coating amount (Wp) of 80 g/m ² and a softening agent application amount (Ws) of the values shown in Table 1.
Regarding the papermaking felts of Experimental Examples 1 to 8, the weight ratio of the softener to the polyurethane resin (softener application amount (Ws) / resin application amount) was calculated from the resin application amount (Wp) and the softener application amount (Ws). (Wp)) was calculated and shown in Table 1.

〔An endurance test〕
The resin-processed felt (Experimental example 0) and the paper-making felt (Experimental examples 1 to 8) were cut into lengths of 0.34 m and widths of 0.14 m, respectively, and formed into an endless belt with a total length of 5 m after connection. to obtain test samples of Experimental Examples 0 and 1-8. These test samples were attached to a press roll tester, and a durability test was conducted on the durability of the polyurethane resin.

The press roll tester is designed to press (compress) the test sample between the top and bottom rolls once per revolution during the durability test.
In addition, the press roll tester has a structure in which a test sample is run so that the surface of the test sample is bent both outward and inward by a plurality of rolls attached to the tester.
Furthermore, the press roll tester has a structure having a high-pressure needle-type sliding shower and a suction box.

The endurance 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 number of times of pressing reached 46,500.
In the durability test, a high-pressure needle-type shower was slid on the paper-making side of the test sample (the paper-making side of the paper-making felt), water was sprayed on the paper-making side, and the test sample was dried with a suction box. The test sample was run while sucking moisture from the paper-making surface side.

For the test sample, the weight before the durability test (basis weight; g/m ² ) and the weight after the durability test (basis weight; g/m ² ) were measured, and the difference in weight before and after the durability test was the amount of resin falling off ( W _L1 ; g/m ² ).
Based on the amount of resin dropped (W _L1 ; g/m ² ) and the amount of resin applied (Wp; g/m ² ), the remaining amount of resin (Wp ₁ ; g/m ² ) of the test sample after the durability test ), and the ratio of the resin residual amount (Wp ₁ ; g/m ² ) to the resin coating amount (Wp; g/m ² ) [(Wp ₁ /Wp) × 100], the resin residual rate (%) Calculated.
Table 1 shows the amount of resin dropped (W _L1 ; g/m ² ) and the resin residual rate (%) for the test samples of Experimental Example 0 and Experimental Examples 1 to 8.

[Bending stiffness test]
From the felt raw fabric, the resin-processed felt (Experimental example 0), and the papermaking felt (Experimental examples 1 to 8), three test samples were cut out from each with a length of 10 cm and a width of 10 cm. Three test samples each of Experimental Example 0 and Experimental Examples 1 to 8 were obtained.
Three test samples each of the felt raw fabric, Experimental Example 0, and Experimental Examples 1 to 8 were measured for weft bending stiffness values (g/cm) for all three using the measuring device shown in FIG. An average value was obtained, and the average value was used as the weft bending rigidity value (g/cm) of the felt material, Experimental Examples 0 and 1 to 8.
Then, the rate of change in weft bending (%) was obtained based on the weft bending rigidity values (g/cm) of the felt material, Experimental Examples 0 and 1 to 8. The rate of change in weft bending (%) is determined by taking the weft bending rigidity value (g/cm) of Experimental Examples ₀ and ₁ to 8 as F1 and the weft bending rigidity value (g/cm) of the original felt fabric as F0. , the weft bending change rate (%)=(F ₁ /F ₀ )×100.
Table 1 shows the weft bending stiffness value (g/cm) and the weft bending rate of change (%) of the felt material and the test samples of Experimental Examples 0 and 1 to 8.

[Results/Discussion]
FIG. 3 shows the weight ratios shown in Table 1, the resin residual rate (%), and the weft bending change rate (%) for Experimental Example 0 (resin-processed felt) and Experimental Examples 1 to 8 (papermaking felt). is a graph showing the relationship between
As shown in the graph of FIG. 3 and Table 1, the weft bending stiffness value (g/cm) of Experimental Example 0, to which no softening agent is applied, is higher than Experimental Examples 1 to 8, and the weft bending change rate (%) was 129.4%. In Experimental Examples 1 to 8, in which the softening agent was applied, the weft bending change rate (%) decreased as the weight ratio increased, that is, as the softening agent application amount (Ws) increased.
On the other hand, with respect to the resin residual rate (%), the resin residual rate of Experimental Example 0, in which no softener was applied, was 81.8%, but the softener was applied so that the weight ratio was 0.019. In Experimental Example 1, the resin residual rate was 88.4%, which was much higher than in Experimental Example 0. That is, Experimental Example 1 was able to enjoy the merits of resin processing more favorably than Experimental Example 0, in which no softening agent was applied.
Furthermore, the resin residual rate (%) was 88.0%, 87.8%, 84.6% in Experimental Examples 2, 3, and 4 following Experimental Example 1, and 81.8% in Experimental Example 0. higher than From the graph of FIG. 3, the residual resin ratio (%) of Experimental Examples 1 to 3 decreased only slightly even when the weight ratio increased to 0.019, 0.040, and 0.060. From Experimental Example 4 onwards where the ratio was set to 0.080 or more, there was a tendency to greatly decrease.
That is, the rate of change in weft bending (%) decreases as the softening agent application amount (Ws) increases, thereby improving the insertability. On the other hand, when the weight ratio, which is the amount of softener applied to the amount of resin applied, was within a certain range, the resin residual rate (%) was further increased than the resin-processed felt to which no softener was applied. It was shown that the benefits of

The range of the weight ratio for improving the resin residual ratio (%) will be considered.
Regarding the papermaking felts of Experimental Examples 1 to 8, the resin residual rate (%) was set to 81.8% of Experimental Example 0 as a reference value, and the weft bending change rate (%) was 100% for the felt raw fabric. The reference value is 110%, which is 10% higher than the above. Note that the reference value of 110% for the rate of change in weft bending (%) is 10% or more lower than 129.4% in Experimental Example 0 to which no softening agent is applied.
Then, those having a resin residual rate (%) of 81.8% or more, which is a reference value, and a weft bending change rate (%) of 110% or less, which is a reference value, can preferably enjoy the merits of resin processing, and "Good" was given to those with improved insertability into the paper machine, and "NG" was given to the other cases.
The evaluation results are shown in Table 1.

In Experimental Examples 2 to 4, the evaluation is "Good", and the resin residual rate (%) exceeds the reference value of 81.8%, so the merits of resin processing can be preferably enjoyed. Since the rate of change in bending (%) was 110% or less, which is the reference value, the insertion into the paper machine was also good.
In Experimental Example 1, the resin residual rate (%) was 88.4%, exceeding the reference value of 81.8%, and the merits of resin processing could be enjoyed. However, the rate of change in weft bending (%) was 129.4%, which exceeded the reference value of 110% for judging "Good", and there was a slight difficulty in inserting into a paper machine.
In Experimental Examples 5 to 8, the residual resin ratio (%) was less than the standard value of 81.8%, and the resin easily fell off, so it was found that the merits of resin processing could not be obtained.

Regarding the weight ratio, when the upper limit of the rate of change in weft bending (%) that does not cause difficulty in loading is 110% or less, which is the above-mentioned reference value, the value of the weight ratio is 0.024 or more from the graph in FIG. there were.
Regarding the weight ratio, the resin residual rate (%) is set to 81.8% of Experimental Example 0 as a reference value, and from the viewpoint of improving the durability of the resin, the lower limit of the resin residual rate (%) is set to 81.8. % or more, the value of the weight ratio was 0.090 or less from the graph of FIG.
Therefore, it was found that the weight ratio in the present invention is in the range of 0.024 to 0.090 from the viewpoint of improving the insertion into the paper machine and favorably receiving the merits of resin processing.

INDUSTRIAL APPLICABILITY The papermaking felt of the present invention is suitably used as a papermaking press felt used in the press part of a paper machine. can be used in

1: Felt for papermaking, 11: Base fabric layer, 13: Front batt layer, 13A: Inner layer, 13B: Surface layer, 15: Back batt layer, 17: Front batt fiber, 19: Polyurethane resin.

Claims (4)

A papermaking felt coated with a polyurethane resin and provided with a softener,
A papermaking felt, wherein a weight ratio of the softening agent to the polyurethane resin (weight ratio of the softening agent/weight of the polyurethane resin) is in the range of 0.024 to 0.090. The papermaking felt according to claim 1, wherein said softening agent comprises a surfactant. The papermaking felt according to claim 2, wherein the surfactant is a nonionic surfactant. A base fabric layer and a front batt layer disposed on the paper-making side of the base fabric layer,
The papermaking felt according to any one of claims 1 to 3, wherein the front batt layer includes a surface layer portion containing fibers bound with the polyurethane resin, and the softener is applied to the surface layer portion. .

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