KR102203415B1 - Method for manufacturing wet nonwoven fabric without sticking phenomenon of calender roll - Google Patents

Abstract

The present invention relates to a method for manufacturing a high-strength wet non-woven fabric, and more specifically, to a method for manufacturing a wet non-woven fabric without a sticking phenomenon in which a non-woven fabric sticks to a surface of a calendar roll. The present invention relates to a method for manufacturing a wet non-woven fabric which is manufactured by calendaring a paper at constant temperature and pressure with the calendar roll after manufacturing the paper by mixing binder fibers with different types of synthetic fibers. The calendar roll comprises: a step of performing tie coating with a material of forming pores on a surface of a steel cylinder roll which forms 1-5 hard nips; and a step of performing non-adhesive coating on the tie coating with a liquid fluorine contained resin.

Description

TECHNICAL FIELD [Method for manufacturing wet nonwoven fabric without sticking phenomenon of calender roll}

The present invention relates to a method for manufacturing a high-strength wet non-woven fabric, and in particular, to a method for producing a wet non-woven fabric characterized in that there is no sticking phenomenon in which non-woven fibers adhere to the surface of a calender roll.

Wet-laid nonwoven fabrics made with paper machines are used as filter media in various types of filters such as automobile oil filters, gas turbine intake filters, and industrial dust collector filters. In particular, a gas turbine intake filter using a pulse jet cleaning method or a wet nonwoven fabric used in an industrial dust collector filter needs high bursting strength and stiffness.

This high-strength wet-type nonwoven fabric is made by mixing a binder fiber serving as an adhesive with other synthetic fibers to make paper and then pressing at high temperature and high pressure using a calender. Synthetic fibers used in the manufacture of wet nonwoven fabrics are short fibers with a length of 3 to 36 mm, so they are easily separated from other fibers due to lack of bonding between fibers and have the property of creating fuzz.

As the binder fiber serving as an adhesive for the wet nonwoven fabric, a sheath-core type bicomponent fiber is usually used. The sheath portion having a lower melting point than the core portion is made of polyethylene, polypropylene, and modified polyester, which are polymers having a low melting point. Because of the low melting point of the sheath part, the wet nonwoven fabric using the binder fiber is made into a high strength wet nonwoven fabric by performing thermal calendering at a relatively low temperature to bond the binder fiber with other synthetic fibers.

Conventional wet nonwoven calendering has been performed using a Teflon-coated calender roll coated with powder Teflon on the surface of a steel cylinder roll or a calender roll having a Teflon tape attached to the steel cylinder surface. However, in the case of the Teflon film coating, the coated film is easily peeled off due to the pressure of the calender roll and torsion by the wet nonwoven fabric, and a sticking phenomenon in which the binder fibers of the wet nonwoven fabric adhere to the peeled area occurred, making continuous work difficult. In addition, in the case of a calender in which Teflon tape is attached to the calender roll, the Teflon tape is not hard and the wet nonwoven fabric cannot be strongly compressed, making it impossible to make a wet nonwoven fabric of the desired thickness, or too strong for the calender roll with Teflon tape attached to reduce the thickness. When pressure is applied, a sticking phenomenon in which the binder fibers contained in the wet nonwoven fabric gradually adhere to the surface of the Teflon tape occurred, and eventually, there was a problem that continuous operation was not possible.

Therefore, in order to make a high-strength wet nonwoven fabric used as a filter media in a gas turbine intake filter or an industrial dust collector filter, it is necessary to develop a calender device capable of continuous work without sticking of binder fibers and a method of manufacturing a wet nonwoven fabric using the same.

The present invention is to solve the sticking phenomenon in the conventional wet nonwoven calendering treatment, the present invention is to form a number of pores on the surface of a steel cylinder roll forming 1 to 5 hard nips An object thereof is to provide a method of manufacturing a high-strength wet-type nonwoven fabric through a calender roll coated with tungsten and non-adhesively coated with a liquid fluororesin on the tie-coated surface.

The present invention has the following features to achieve the above object.

The present invention is a method for producing a wet nonwoven fabric prepared by mixing a binder fiber with synthetic fibers of different types to prepare paper paper and then calendering with a calender roll at a constant temperature and pressure, wherein the calender roll comprises 1 to 5 hard nips. Performing tie coating with a material forming pores on the surface of the steel cylinder roll to be formed; And performing a non-adhesive coating with a liquid fluororesin on the tie coating.

Here, in the step of performing the tie coating, pores are formed of tungsten or tungsten oxide.

In addition, the step in which the non-stick coating is performed is a non-stick coating with polytetrafluoroethylene (PTFE).

In addition, in the step of performing the non-adhesive coating, the non-adhesive coating layer has a thickness of 200 μm or less.

The calender roll manufactured according to the present invention has a high hardness on the surface of the calender roll, and the fluororesin is completely bonded with the tungsten tie coating, so there is no sticking of the binder fibers used in the manufacture of the wet nonwoven fabric, and it is non-adhesive due to the production of the wet nonwoven fabric. Since the coating is not easily worn, continuous production is possible, and the surface of the wet nonwoven fabric made is smooth and has sufficient strength.

1 is a flow chart showing the manufacturing process of the high-strength wet nonwoven fabric according to the present invention.
2 is a flow chart showing a calender roll coating process according to an embodiment of the present invention.
3 is an electron microscope enlarged image of 250 times of the high-strength wet nonwoven fabric subjected to calendering according to the present invention.
4 is a flow chart showing a calender roll coating process according to another embodiment of the present invention.
5 is a view showing a form of a calender roll coating according to another embodiment of the present invention.

In order to explain the present invention, operational advantages of the present invention, and objects achieved by the implementation of the present invention, the following will illustrate a preferred embodiment of the present invention and look at it with reference.

First, terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention, and expressions in the singular may include a plurality of expressions unless clearly different meanings in context. In addition, in the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other It is to be understood that the presence or addition of features, numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being excluded.

In describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a flow chart showing the manufacturing process of the high-strength wet nonwoven fabric according to the present invention, Figure 2 is a flow chart showing a calender roll coating process according to an embodiment of the present invention, Figure 3 is a calendering treatment according to the present invention This is a magnified image of 250 times the electron microscope of a high-strength wet nonwoven fabric.

Referring to the drawings, the high-strength wet nonwoven fabric manufacturing process according to the present invention is largely composed of a step (S10) of manufacturing a wet nonwoven fabric using a paper machine and a step (S20) of performing calendering of the wet nonwoven fabric by a calender roll. .

The wet nonwoven fabric used in the present invention is made by a paper machine (S10). High-strength wet nonwoven fabrics are made of polyester (PET) fibers that make nonwovens with good stiffness. When making a wet nonwoven fabric from synthetic fibers such as polyester, physical web bonding is required with a binder fiber that acts like an adhesive. This is because polyester fibers, unlike wood fibers, do not have functional groups that can chemically or physically bond with each other.

As the polyester binder fiber, a sheath-core type bi-component fiber is usually used. Because of the low melting point of the sheath portion, the wet nonwoven fabric using the binder fiber is made into a high strength wet nonwoven fabric by performing thermal calendering at a relatively low temperature to bond the binder fiber with other synthetic fibers (S20).

Binder fibers have adhesive-like properties and play a role in bonding synthetic fibers to each other, but they also cause sticking to stick to mechanical devices such as calender rolls. When the binder fibers start to cause sticking, the fibers are peeled off from the wet nonwoven web and fibers are accumulated in the sticking area, so that the calendering operation must be stopped.

Therefore, it is necessary to prevent sticking of the binder fibers on the surface of the calender roll.

In order to prevent the binder fibers from adhering to the surface of the calender roll as described above, in one embodiment of the present invention, a double coating step is performed. First, the surface of the calender roll made of steel is firstly tie coated (S110). , Secondly, a non-stick coating is applied (S120).

Here, the tie coating serves to strongly bind the surface of the calender roll and the non-adhesive coating layer. In one embodiment of the present invention, such a non-adhesive coating is performed with Teflon. If a non-adhesive coating such as Teflon is directly coated on the surface of a steel calender roll without a tie coating layer, pores between the calender roll surface and the Teflon coating layer Is formed, and the pores gradually expand to create a large non-adhesive area such as a blister.

If the non-adhesive surface of the Teflon coating layer is not adhered to the surface of the calender roll, this area is very vulnerable to impact and is easily peeled off. Tie coating is required to prevent the formation of pores on the surface of the calender roll.

Tungsten, tungsten oxide, ceramic composition, carbide, molybdenum, and the like may be coated on the tie coating by a known method such as plasma spraying. These tie coatings must have a certain hardness, and in order to achieve a strong bond with the non-adhesive coating layer, the surface must be rough and have a lot of pores.

If the tie coating layer has pores, the non-stick coating penetrates not only the surface of the tie coating layer but also into the pores of the tie coating layer, and the non-stick coating leads to a strong bond with the tie coating layer. Any material having all of the above properties can be used for tie coating, but among them, tungsten, tungsten oxide and ceramic compositions are advantageous, and more preferably tungsten or tungsten oxide is more suitable in terms of hardness and pore formation. .

A fluororesin such as Teflon is used for non-stick coating. That is, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), ethylene-tetrafluoroethylene (ETFE), ethylene. Ethylene-Chlorotrifluoroethylene (ECTFE), polyvinylidene fluoride (PVDF), or the like may be used.

PTFE has the highest operating temperature of 290℃ for the fluororesin layer, and has an extremely low coefficient of friction, which is particularly advantageous for non-stick coatings that work at high temperatures. FEP is an improved type of PTFE and has a lower heat resistance than PTFE, so 200℃ is the maximum operating temperature. FEP has excellent non-adhesiveness because it forms a non-porous film through the sintering process.

The maximum use temperature of PFA is 260℃, has excellent chemical resistance, and is advantageous in forming a 1300㎛ thick film. The continuous use temperature of ETFE is 150℃ and the coating thickness can be increased to 2500㎛. The continuous use temperature of ECTFE is 140℃, and a coating layer with excellent durability can be made. PVDF is a difluorinated resin and is widely used in applications such as injection, extrusion, and molding.

In the calendering of wet nonwoven fabric, the calendering temperature varies depending on the melting point of the binder fiber used, but heating of 200°C or higher is often required. Therefore, polytetrafluoroethylene (PTFE), which has a high operating temperature of 290°C and has an extremely low coefficient of friction, is more advantageous for non-adhesive coating to prevent sticking of binder fibers.

A liquid PTFE resin is used for the coating of PTFE. The PTFE particles contained in the liquid PTFE resin have a size of 0.1 to 5㎛. PTFE particles are applied to the tie-coating layer and coated by a method that sufficiently penetrates the tungsten pores, and then stabilized the coating layer through natural or hot air drying, and then heated at a temperature of 350°C or higher, more preferably 400°C or higher. It is hardened through the firing process.

In addition, it is rather advantageous that the thickness of the non-adhesive coating layer applied on the tie-coated surface is not thick. When the thickness of the non-stick coating becomes thick, separation from the tie-coated surface occurs rather easily. Therefore, the thickness of the non-adhesive coating surface is preferably 500 μm or less. More preferably, it is 200 micrometers or less.

Calendering of a wet nonwoven fabric requires strong compression of the wet nonwoven fabric, so a calender roll coated with a resin or wound with a covering is not suitable. Therefore, it is preferable that the base surface material of the calender roll is made of steel.

In the case of a steel calender roll, it is possible to calender wet nonwoven fabric with 2 balls 1 nip. However, in the case of finishing the calender with 1 nip, deformation of the calender roll or damage to the non-adhesive coating layer may easily occur due to too strong pressure and impact.

Therefore, in the first step calendering, it is more preferable to perform pre-calendering in which the wet nonwoven fabric is heated and compressed at a relatively low temperature, and additionally, the second step calendering is completed in the second step. Therefore, 1 to 5 nips are required for the calendering of the wet nonwoven fabric.

As described above, the calender device made by the present invention and the wet nonwoven fabric calendered with it have sufficient strength and smooth surface required by the gas turbine intake filter and industrial dust collector filter, and no sticking phenomenon occurs during the calendering process. Continuous work is possible.

Manufacture of nonwoven fabric

The wet nonwoven fabric calendered according to the present invention was compared with a comparative example made by another method. The wet non-woven fabric used in the examples is an uncalendered Extia 1000 fabric manufactured by Alstrom Korea Co., Ltd. In the embodiment, a calender device capable of performing two-step calendering according to the present invention was used. The first stage calender roll consists of 2 balls and 1 nip, and the second stage calender roll consists of 3 balls and 2 nips. In the first stage, a pre-calender was performed at a calender roll temperature of 100 to 150°C, and in the second stage, the main calender was performed at 170 to 200°C.

In the comparative example, a wet non-woven fabric made in a manner different from the present invention was used to increase the strength by heat-treating the wet non-woven fabric without sticking the binder fibers used in the production of the wet non-woven fabric. That is, in Comparative Example 1, a wet nonwoven fabric was passed between belt presses coated with silicone using a flatbed device, heated to a temperature of 180°C, and pressure was applied to perform calender treatment. In Comparative Example 2, the temperature of the hard chromium plating roll was adjusted to 120 using a 2-ball 1-nip calender consisting of a heatable hard chromium-plated roll and a resin roll coated with polyurethane resin as the lower roll. Heated to °C, the wet nonwoven fabric front and back were alternately calendered twice.

Among these measurements, the basis weight was determined by TAPPI test method T402 (Grammage of paper and paperboard), the thickness was determined by ISO standard ISO 534 (2011) (Paper and board-Determination of thickness, density and specific volume), and the air permeability was ASTM D737. (Standard Test method for Air Permeability of Textile Fabrics), burst strength according to ISO standard ISO 2758 (2014) (Paper-Determination of burst strength), stiffness according to ASTM D1388-18 (Standard Test Method for Stiffness of fabrics) Was measured by

In the case of the comparative example using the flat bed, there is a limit to compressing the wet nonwoven fabric by pressing with a belt press, so that the desired thickness of 0.55 to 0.65 mm could not be obtained. The thickness of the wet nonwoven fabric was not sufficiently lowered and the density was not increased, so the bursting strength and stiffness were also low.

In the case of Comparative Example 2 using a hard chromium plating roll, the thickness was too low due to two calendering. In addition, both sides of the wet nonwoven fabric could not be heated at the same time as pressing, so this also did not obtain the desired strength. In addition, since the melt and adhesion of the binder fiber in the middle part of the wet nonwoven fabric was insufficient, separation into two layers easily occurred.

Figure 4 is a flow chart showing a calender roll coating process according to another embodiment of the present invention, Figure 5 is a view showing a state of forming a calender roll coating according to another embodiment of the present invention.

Referring to the drawings, in the calender roll coating process according to the present embodiment, in the above-described embodiment, a tie coating is performed on the surface of the calender roll 100 (S110), and a non-adhesive coating layer such as Teflon is formed on the tie coating layer. In step S120, the PEEK polymer coating layer is partially formed.

Here, the PEEK polymer is a polyether ether ketone polymer, along with 6 major special engineering, with polyphenylene sulfide (PPS), polysulfone (PSU), polyimide (PI), polyaromatic ester (PAR) and liquid crystal polymer (LCP). It is named one of the plastics.

PEEK provides excellent mechanical properties, for example, high temperature resistance of 260°C, good self-lubrication, corrosion resistance, flame resistance, peel resistance, abrasion resistance and radiation resistance.

In particular, PEEK has excellent strength and can reinforce the durability of the calender roll 100 according to the present invention.

In the present invention, it is intended to improve the durability of the calender roll surface layer by partially forming such a PEEK polymer coating layer on the non-adhesive coating layer.

To this end, the coating process of the calender roll 100 according to the present embodiment includes the step of performing tie coating (S110), the step of forming a non-adhesive coating layer 20 such as Teflon on the tie coating layer 10 (S120), and , The step of laminating the separator 30 on the non-adhesive coating layer 20 (S130), and the step of forming a plurality of grooves 40 on the separator 30 and the non-adhesive coating layer 20 (S140) And, PEEK polymer is added to the groove portion 40 to form a PEEK coating layer 50 (S150), and a step 160 of removing the separator 30.

Here, the separator 30 is to prevent the PEEK polymer from being formed on the non-adhesive coating layer 20, and after removing the separator 30 (S160), the PEEK coating layer 50 that partially protrudes is the same as the non-adhesive coating layer 20 It is desirable to remove it so that it has a height of that.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment described above. That is, a person having ordinary knowledge in the technical field to which the present invention pertains can make a number of changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are Equivalents should be regarded as falling within the scope of the present invention.

10: tie coating layer 20: non-adhesive coating layer
30: separator 40: groove
50: PEEK coating layer 100: calender roll

Claims (4)

In the manufacturing method of a wet nonwoven fabric manufactured by mixing a binder fiber with a synthetic fiber of a different type to prepare paper paper and then calendering it at a constant temperature and pressure with a calender roll
The calender roll
A step of performing tie coating with a material forming pores on the surface of a cylinder roll made of steel forming 1 to 5 hard nips;
Including; non-adhesive coating is performed on the tie coating with a liquid fluororesin,
Laminating a separator on the non-adhesive coating layer on which the non-adhesive coating has been performed, forming a plurality of grooves on the separator and the non-adhesive coating layer, and PEEK polymer is added to the groove to form a PEEK coating layer. A method for manufacturing a wet nonwoven fabric without sticking of a calender roll, further comprising a step of removing the separator.
The method of claim 1,
The step of performing the tie coating
A method for manufacturing a wet nonwoven fabric without sticking of a calender roll, characterized in that pores are formed from tungsten or tungsten oxide.
The method of claim 1,
The step of performing the non-adhesive coating is a method for manufacturing a wet nonwoven fabric without sticking of a calender roll, characterized in that the non-adhesive coating is performed with polytetrafluoroethylene (PTFE).
The method of claim 1,
The step of performing the non-stick coating
A method for producing a wet nonwoven fabric without sticking of a calender roll, characterized in that the non-adhesive coating layer has a thickness of 200 μm or less.

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