WO2019230836A1

WO2019230836A1 - Wall material nonwoven fabric and method of manufacturing same

Info

Publication number: WO2019230836A1
Application number: PCT/JP2019/021384
Authority: WO
Inventors: 松浦　博幸; 仁溝上; 羽根　亮一
Original assignee: 東レ株式会社
Priority date: 2018-05-31
Filing date: 2019-05-29
Publication date: 2019-12-05
Also published as: JP7160094B2; TW202012741A; CN112204193A; JPWO2019230836A1

Abstract

A wall material nonwoven fabric according to an embodiment of the present invention comprises fiber mainly composed of a thermoplastic resin and is characterized in that, on the surface of the nonwoven fabric, fibers are fused together at intersections of the fibers and are separated from each other at locations other than the intersections, and in that at least one side of the sheet has a surface roughness SMD obtained by the KES method of 1.2 μm or less and a vertical tear strength per basis weight of 0.50 N/(g/m²) or more.

Description

Non-woven fabric for wall covering and manufacturing method thereof

The present invention relates to a non-woven fabric for wall coverings installed on a wall surface or ceiling of a building and a method for manufacturing the same.

Among the conventional wall covering materials, the most frequently used one is a laminate of sheets made of polyvinyl chloride resin on paper or the like. The wall covering material using polyvinyl chloride is an excellent material in terms of price, workability, and printing characteristics, but has a serious problem in disposal after use.

Therefore, in recent years, wall covering materials having various biodegradability have been proposed with an increase in environmental orientation. For example, a non-woven fabric for wall coverings comprising a melt blown nonwoven fabric composed of biodegradable fibers laminated and integrated on at least one surface of a spunbond nonwoven fabric composed of biodegradable fibers. There is disclosed a wall covering material characterized in that all of the constituent materials are polylactic acid resins (see Patent Document 1).

On the other hand, a non-embossed product and a non-woven fabric for wallpaper having excellent rigidity and surface smoothness have also been proposed (see Patent Document 2).

Furthermore, a non-woven fabric for wallpaper backing has been proposed that has good dimensional stability, has low peel strength when peeling the wallpaper from the wall surface, has excellent peel characteristics, and has printability and coating suitability (see Patent Document 3). ).

Japanese Unexamined Patent Publication No. 2004-270081 Japanese Unexamined Patent Publication No. 2007-284859 Japanese Unexamined Patent Publication No. 2016-141922

However, the technology disclosed in Patent Document 1 is embossing, and when the problem is inferior in printability or the melt blown layer is applied to the wall side, the melt blown nonwoven fabric is torn and remains on the wall when peeled off, which is very useful for cleaning work. There is a problem that it takes time and effort.

Further, the technology disclosed in Patent Document 2 does not emboss, but is a non-woven fabric having a high packing density and high rigidity, inferior in unevenness to the wall, poor workability, and easy to peel off from the wall surface. There is a problem.

Furthermore, since the technology disclosed in Patent Document 3 is a paper-made nonwoven fabric, the tear tearing strength is weak, and when it is peeled off from the wall surface, there is a problem that it is inferior in workability.

Therefore, an object of the present invention is to provide a non-woven fabric for wall covering material that is excellent in resin processability and workability.

As a result of intensive studies to achieve the above object, the present inventors have found a non-woven fabric that is suitable for wall covering, has less fuzzing, and has excellent resin processability and workability, and a method for producing the same.

That is, the present invention is to solve the above problems, and the nonwoven fabric for wall covering material according to an embodiment of the present invention is a nonwoven fabric composed of fibers mainly composed of a thermoplastic resin, and the nonwoven fabric described above. On the surface of the sheet, the fibers are fused at the intersection of the fibers, and the fibers other than the intersection are separated from each other. Further, the surface roughness SMD of at least one side of the sheet by the KES method is 1. The vertical tear strength per unit weight is 0.50 N / (g / m ² ) or more.

According to a preferred embodiment of the nonwoven fabric for wall covering of the present invention, the weight of the nonwoven fabric for wall covering is 80 g / m ² or more and 130 g / m ² or less, and the thickness of the nonwoven fabric for wall covering is 0.00. It is 18 mm or more and 0.31 mm or less, and the air permeability of the nonwoven fabric for wall covering material is 30 cc / cm ² / sec or more and 60 cc / cm ² / sec or less.

According to a preferred aspect of the non-woven fabric for wall covering material of the present invention, the non-woven fabric is a spunbonded non-woven fabric made of long fibers.

In the method for producing a nonwoven fabric for wall covering material according to an embodiment of the present invention, a pair heated to a low temperature of 30 ° C. or higher and 120 ° C. or lower with respect to the melting point of the lowest melting point thermoplastic resin constituting the surface of the fiber. After the thermocompression bonding with the flat roll at a linear pressure of 500 N / cm or more and 1100 N / cm or less, the film is continuously brought into contact with the flat roll for a predetermined time.

According to the present invention, a nonwoven fabric composed of fibers mainly composed of a thermoplastic resin, the intersections of the surface fibers on at least one surface of the nonwoven fabric are all fused, and at least the surface roughness of the sheet on one surface by the KES method. SMD is 1.2 μm or less, and the vertical tear strength per unit weight is 0.50 N / (g / m ² ) or more, so that the non-woven fabric for wall coverings has less fuzz and is excellent in resin processability and workability. Can be obtained.

It is the schematic which shows the heat processing of the fiber web by a flat roll.

The nonwoven fabric for wall covering material according to one embodiment of the present invention is a nonwoven fabric composed of fibers mainly composed of a thermoplastic resin, and all the intersections of the surface fibers on at least one surface of the nonwoven fabric are fused, and at least It is a non-woven fabric for wall coverings having a surface roughness SMD of 1.2 μm or less by a KES method (Kawabata Evaluation System) on one side of the sheet and a vertical tear strength per unit weight of 0.50 N / (g / m ² ) or more .
The details are shown below.

(Thermoplastic resin)
It is important that the non-woven fabric for wall covering material of one embodiment of the present invention is a non-woven fabric composed of fibers mainly composed of a thermoplastic resin.

Examples of the thermoplastic resin include polyesters, polyamides, polyolefins, and mixtures and copolymers thereof. Of these, polyester is preferred because it is more excellent in durability such as mechanical strength, heat resistance, water resistance and chemical resistance.

Polyester consists of an acid component and an alcohol component. Examples of the acid component include aromatic carboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanecarboxylic acid. As the alcohol component, ethylene glycol, diethylene glycol, polyethylene glycol, or the like can be used.

Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, and copolymers thereof.

In the nonwoven fabric for wall covering according to one embodiment of the present invention, a crystal nucleating agent, a matting agent, a lubricant, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent and the like may be added. Especially when thermocompression molding of long fiber nonwoven fabrics, metal oxides such as titanium oxide have the effect of improving the adhesion of long fiber nonwoven fabrics by increasing the thermal conductivity, and the mold release property between the thermocompression roll and web. It is preferable to add an aliphatic bisamide such as ethylenebisstearic acid amide and / or an alkyl-substituted aliphatic monoamide, which has an effect of improving the adhesion stability by increasing the number. These various additives may be present in the thermoplastic continuous fiber, or may be present on the surface of the thermoplastic continuous fiber.

(Fiber mainly composed of thermoplastic resin)
Further, the fiber mainly composed of the thermoplastic resin in the present invention is preferably a composite fiber in which a low melting point polymer having a melting point lower than the melting point of the high melting point polymer is arranged around the high melting point polymer. .

By using such a composite fiber, the thermoplastic continuous fiber can be firmly bonded in the nonwoven fabric by thermocompression bonding, and surface smoothness can be obtained. Further, as a nonwoven fabric used for suppressing fuzz and for wall covering materials The mechanical strength can be improved.

Further, by using such a composite fiber, the number of adhesion points in the nonwoven fabric is increased as compared to those obtained by mixing fibers having different melting points in addition to the strong adhesion between the filaments constituting the nonwoven fabric. Moreover, the dimensional stability and durability as a nonwoven fabric for wall covering materials are also improved.

Here, the main component is a component occupying 50% by mass or more of the components of the composite fiber.

The difference in melting point between the high melting point polymer and the low melting point polymer is preferably 10 ° C. or higher and 140 ° C. or lower. Desirable thermal adhesiveness can be obtained by setting the difference in melting point to 10 ° C. or higher, more preferably 20 ° C. or higher, and further preferably 30 ° C. or higher. In addition, by controlling the temperature to 140 ° C. or lower, more preferably 120 ° C. or lower, and further preferably 100 ° C. or lower, it is possible to prevent the low melting point polymer component from fusing to the thermocompression-bonding roll during thermocompression bonding, thereby reducing productivity. Can do.

In addition, the melting point of the high melting point polymer in the composite fiber is preferably 160 ° C. or higher and 320 ° C. or lower. By setting the temperature to 160 ° C. or higher, more preferably 170 ° C. or higher, and further preferably 180 ° C. or higher, the shape stability is excellent even in a processing step where heat is applied. Moreover, it suppresses that productivity is reduced by consuming a great deal of heat energy for melting at the time of producing the long-fiber nonwoven fabric by setting it to 320 ° C. or less, more preferably 300 ° C. or less, and even more preferably 280 ° C. or less. Can do.

On the other hand, the melting point of the low-melting polymer in the composite fiber is preferably 150 ° C. or more and 310 ° C. or less after ensuring the difference in melting point between the high-melting polymer and the low-melting polymer. By setting the temperature to 150 ° C. or higher, more preferably 160 ° C. or higher, and more preferably 170 ° C. or higher, the shape stability is excellent even in a processing step in which heat is applied. Moreover, it is 310 degrees C or less, More preferably, it is 290 degrees C or less, More preferably, it suppresses that a heat energy for melting at the time of long-fiber nonwoven fabric manufacture is consumed greatly, and productivity falls. Can do.

Specific examples of the combination of the high melting point polymer and the low melting point polymer (high melting point polymer / low melting point polymer) include polyethylene terephthalate / polybutylene terephthalate, polyethylene terephthalate / polytrimethylene terephthalate, polyethylene terephthalate / polylactic acid, Examples thereof include polyethylene terephthalate / copolymerized polyethylene terephthalate. As a copolymerization component of copolymerized polyethylene terephthalate, isophthalic acid or the like is preferable.

In the present invention, the value measured as follows is adopted as the melting point of the thermoplastic resin.

(1) Using a differential scanning calorimeter, measurement is performed once under the following conditions. As the differential scanning calorimeter, “Q100” manufactured by TA Instruments is used.
・ Measurement atmosphere: Nitrogen flow (150ml / min)
・ Temperature range: 30-350 ℃
・ Temperature increase rate: 20 ° C./min ・ Sample amount: 5 mg

(2) The average value of the endothermic peak apex temperatures is calculated as the melting point of the measurement object. However, when a plurality of endothermic peaks exist in the resin before fiber formation, the peak apex temperature on the highest temperature side is set. Moreover, when making a fiber into a measuring object, it measures similarly and estimates melting | fusing point of each component from several endothermic peaks. At that time, the endothermic peak due to the composite fiber is the endothermic peak on the highest temperature side (A) and the endothermic peak that appears on the side with the shorter elapsed time (the side on which the peak appears earlier), next to the endothermic peak on the highest temperature side. It is a peak group showing a high peak (endothermic peak (B)), and the endothermic peak (A) indicates the melting point of the high melting point polymer, whereas the endothermic peak (B) has a low melting point weight. It indicates the melting point of the coalescence.

The proportion of the low melting point polymer in the composite fiber is preferably 10% by mass or more and 70% by mass or less in the composite fiber. Desirable thermal adhesiveness can be obtained by setting the content to 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. Moreover, 70 mass% or less, More preferably, it is 60 mass% or less, More preferably, it can suppress that fusion | bonding advances too much and tearing strength falls by setting it as 50 mass% or less.

Examples of the composite form of such a composite fiber include a concentric core-sheath type, an eccentric core-sheath type, and a sea-island type. Among these, a concentric core-sheath type, particularly an embodiment in which a low-melting-point polymer is a sheath component is preferable in that the fibers can be firmly bonded to each other by thermocompression bonding.

Also, examples of the cross-sectional shape of the fiber mainly composed of a thermoplastic resin include a circular shape, a flat shape, a polygonal shape, a multi-leaf shape such as an X shape and a Y shape, and a hollow shape. In the case of adopting a deformed cross-sectional shape in the composite fiber as described above, it is preferable that the low melting point polymer component is present in the vicinity of the outer peripheral portion of the fiber cross-section so that it can contribute to thermocompression bonding.

The fibers mainly composed of the thermoplastic resin according to the present invention preferably have an average single fiber diameter of 10 μm to 24 μm. By setting the average single fiber diameter to preferably 10 μm or more, more preferably 11 μm or more, and further preferably 12 μm or more, a nonwoven fabric excellent in basis weight uniformity and mechanical strength can be obtained.

On the other hand, when the average single fiber diameter is preferably 24 μm or less, more preferably 23 μm or less, and even more preferably 22 μm or less, the resin can be prevented from excessive permeation in post-processing such as resin impregnation.

In the present invention, the average single fiber diameter (μm) of the fiber mainly composed of the thermoplastic resin is a value calculated by the following procedure.

(1) Ten small piece samples (100 × 100 mm) are taken at random from the nonwoven fabric for wall covering material.
(2) Take a surface photograph of 500 times or more and 3000 times or less with a microscope, and measure the diameter of 100 single fibers, 10 from each sample.
(3) The average single fiber diameter (μm) is calculated by rounding the arithmetic average value of the 100 measured values to the first decimal place.

(Nonwoven fabric for wall coverings)
In the nonwoven fabric for wall covering material according to an embodiment of the present invention, on the surface of the nonwoven fabric, the fibers are fused at the intersection of the fibers, and the fibers other than the intersection are separated from each other. is important. That the fibers are separated from each other means that the fibers are not fused. By virtue of such a state, that is, the fibers are not excessively fused to form a film-like portion, air permeability suitable as a non-woven fabric for wall covering material can be ensured. In addition, even after heat fusion, except for the intersection of the fibers, the fibers are not melted to form a film, and the shape of the fiber is maintained, so that it can withstand long-term use as wallpaper. Excellent strength. Furthermore, since fusing is performed only at the intersections, fuzz of the nonwoven fabric can be suppressed, and a nonwoven fabric for wall covering material having excellent printability can be obtained.

In the present invention, the presence or absence of fusion between fibers other than the intersections on the surface of the nonwoven fabric for wall covering material is evaluated as follows.
(1) Ten small piece samples (100 × 100 mm) are taken at random from the nonwoven fabric for wall covering material.
(2) The surface of each sample is photographed with a microscope at a magnification of 500 to 3000 times.
(3) In the above micrograph, all the fibers are observed, two or more fibers are fused at a portion other than the intersection, and the fibers are not separated from each other, forming a film-like portion. The thing shall have fusion of fibers other than an intersection.

It is important that the nonwoven fabric for wall covering of one embodiment of the present invention has a surface roughness SMD of 1.2 μm or less by the KES method on one side of the sheet.

The surface roughness SMD by the KES method on one side of the sheet is 1.2 μm or less, preferably 1.1 μm or less, and more preferably 1.0 μm or less. , Design properties can be improved.

The surface roughness SMD by the KES method is achieved by not providing unevenness by embossing, and can be controlled by appropriately adjusting the conditions for processing the fiber web with a pair of flat rolls.

In the present invention, the surface roughness SMD by the KES method adopts a value measured as follows.

(1) Three test pieces having a width of 200 mm × 200 mm are collected from the nonwoven fabric at equal intervals in the width direction of the nonwoven fabric.
(2) A test piece is set on a sample stage with a load of 400 g.
(3) The surface of the test piece is scanned with a contact for measuring surface roughness (material: φ0.5 mm piano wire, contact length: 5 mm) applied with a load of 10 gf, and the average deviation of the uneven shape on the surface is measured. To do.
(4) The above measurement is carried out in the longitudinal direction (longitudinal direction of the nonwoven fabric) and the lateral direction (width direction of the nonwoven fabric) of all the test pieces, and the average deviation of these 6 points is averaged to obtain the second decimal place. Is rounded off to obtain the surface roughness SMD (μm).

In the nonwoven fabric for wall covering material of one embodiment of the present invention, it is important that the vertical tear strength per unit weight is 0.50 N / (g / m ² ) or more. By setting the vertical tear strength per unit weight to 0.50 N / (g / m ² ) or more, preferably 0.60 N / (g / m ² ) or more, more preferably 0.70 N / (g / m ² ). When used as wallpaper, it has excellent mechanical strength, and it is excellent not only in durability after construction but also in workability because it is not easily broken when peeled off by reattachment or the like.

In addition, the above-mentioned vertical tear strength is 6.4 “tear strength” of JIS L1913: 2010 “General nonwoven fabric test method” using a low-speed extension type tensile tester (for example, “RTG-1250” manufactured by Baldwin). a) In accordance with the trapezoid method, values measured as follows shall be adopted.

(1) Ten specimens having a length of 150 mm and a width of 75 mm are collected in the transverse direction of the nonwoven fabric (width direction of the nonwoven fabric).
(2) Mark the test piece with an isosceles trapezoid, and make a 15 mm notch in the middle of the short side of the mark at right angles to the short side.
(3) The test piece is attached to the gripper along the mark by tightening the short side of the trapezoid and loosening the long side with a constant speed extension type tensile tester with a grip interval of 25 mm.
(4) Under the condition of a tensile speed of 100 ± 10 mm / min, the maximum load (N) at the time of tearing is taken as the tear strength (N), and an average value of 10 points is calculated.
(5) Divide the calculated tear strength (N) by the basis weight (g / m ² ) and round off to the first decimal place.

The nonwoven fabric for wall covering material of one embodiment of the present invention preferably has a basis weight of 80 g / m ² or more and 130 g / m ² or less. By making the basis weight of the nonwoven fabric preferably 130 g / m ² or less, more preferably 125 g / m ² or less, and even more preferably 120 g / m ² or less, the texture of the nonwoven fabric is hard to prevent it from peeling off from the wall during construction. It is possible to obtain a non-woven fabric excellent in unevenness to the wall.

On the other hand, by setting the basis weight of the nonwoven fabric to preferably 80 g / m ² or more, more preferably 85 g / m ² or more, and further preferably 90 g / m ² or more, the texture of the nonwoven fabric is not too soft and has sufficient whiteness. A nonwoven fabric excellent in concealability can be obtained.

In addition, in this invention, the fabric weight of a laminated nonwoven fabric shall employ | adopt the value measured by the following procedures based on JIS L1913: 2010 "6.2 mass per unit area."

(1) Three test pieces of 25 cm × 25 cm are collected per 1 m width of the sample.
(2) Weigh each mass (g) in the standard state.
(3) The average value is expressed in terms of mass per 1 m ² (g / m ² ).

In the nonwoven fabric for wall covering material of one embodiment of the present invention, the thickness of the nonwoven fabric is preferably 0.18 mm or more and 0.31 mm or less. By setting the thickness of the nonwoven fabric to 0.31 mm or less, more preferably 0.30 mm or less, and even more preferably 0.29 mm or less, there is no fuzz and the surface is smooth. be able to.

On the other hand, the thickness of the nonwoven fabric is 0.18 mm or more, more preferably 0.19 mm or more, and even more preferably 0.20 mm or more. Excellent design properties can be improved.

In addition, in this invention, the thickness (mm) of a nonwoven fabric shall employ | adopt the value measured by the following procedures according to "5.1" of JISL1906: 2000.

(1) A pressurizer having a diameter of 10 mm is used, and a thickness of 10 points per 1 m is measured in units of 0.01 mm at equal intervals in the width direction of the nonwoven fabric with a load of 10 kPa.
(2) Round the fourth decimal place of the average value of the above 10 points.

The nonwoven fabric for wall covering material of one embodiment of the present invention preferably has an air permeability of 30 cc / cm ² / second or more and 60 cc / cm ² / second or less.

By setting the air flow rate of the nonwoven fabric to 60 cc / cm ² / second or less, more preferably 55 cc / cm ² / second or less, and even more preferably 50 cc / cm ² / second or less, Excessive penetration can be prevented.

On the other hand, the surface of the nonwoven fabric is not formed into a film by setting the air flow rate of the nonwoven fabric to 30 cc / cm ² / second or more, more preferably 35 cc / cm ² / second or more, and further preferably 40 cc / cm ² / second or more. Since the surface is smooth, the printability is excellent and the design property can be enhanced.

In the present invention, the value measured by the following procedure in accordance with “6.8.1 Frazier method” of JIS L1913: 2010 is adopted as the air permeability of the nonwoven fabric.

(1) 10 test pieces of 15 cm × 15 cm are cut out from the nonwoven fabric.
(2) Measurement is performed on a test piece at a pressure of 125 Pa of a barometer.
(3) The average value obtained is calculated by rounding off the first decimal place.

(Method for producing non-woven fabric for wall coverings)
Next, the manufacturing method of the nonwoven fabric for wall covering materials of one embodiment of this invention is demonstrated.

Examples of the method for producing the wall covering nonwoven fabric according to one embodiment of the present invention include a spunbond method, a flash spinning method, a wet method, a card method, and an airlaid method.

Among these, a spunbond nonwoven fabric produced by the spunbond method is an example of a preferred embodiment. Spunbond nonwoven fabric, which is a long-fiber nonwoven fabric composed of thermoplastic filaments, has excellent productivity and can suppress fuzz that tends to occur when using a short-fiber nonwoven fabric when used as a nonwoven fabric for wallpaper. In particular, it is possible to prevent the occurrence of defective bonding and processing defects. In addition, the spunbonded nonwoven fabric is preferably used from the viewpoint that it is excellent in mechanical strength and can be used to obtain a processed product having excellent durability when used as a nonwoven fabric for wall covering materials.

In the present invention, when a composite fiber such as a core-sheath type is used as the fiber constituting the nonwoven fabric, a normal composite method can be adopted for manufacturing the composite fiber.

After the thermoplastic polymer is melt extruded from the spinneret, it is pulled and drawn by an ejector to form a thermoplastic continuous filament, which is sent out from the nozzle, charged and opened, and then deposited on the moving collection surface to form a fiber web Is done.

At this time, the nozzle is continuously swung at a predetermined angle of 15 degrees or more, more preferably 20 degrees or more, and further preferably 25 degrees or more to the left and right with respect to the web traveling direction. The filament passes through the continuously oscillating nozzle and is then charged and opened by the charging means to form a fiber web, so that bundle fibers are reduced and the web has a large inclination with respect to the longitudinal direction. More specifically, the filament has a fiber orientation degree of 35 degrees to 70 degrees. As a result, the surface area of the fiber per unit weight is increased, and the fabric weight uniformity is improved when the nonwoven fabric is formed, and the vertical tear strength is improved.

In addition, the rocking angle of the nozzle is 60 degrees or less, more preferably 55 degrees or less, and further preferably 50 degrees or less with respect to the web traveling direction, so that the fiber web is deposited on the moving collection surface. When forming, it is possible to suppress the occurrence of defects such as web curling.

The charging method of the thermoplastic continuous filament is not limited at all, but charging by a corona discharge method or charging by frictional charging with a metal is preferable.

The above-mentioned fiber web is pressed with one flat roll, and then pressed against one flat roll for a predetermined time to smooth one side, thereby forming a nonwoven fabric for wall covering.

The smoothing treatment by the flat roll is not limited as long as the flat roll is brought into contact with the fiber web, but heat treatment is preferably performed in which the flat roll heated to a predetermined temperature is brought into contact with the fiber web.

The surface temperature of the flat roll in this heat treatment is preferably 30 ° C. or more and 120 ° C. or less lower than the melting point of the polymer having the lowest melting point constituting the filament existing on the surface of the fiber web, and 40 ° C. or more and 110 ° More preferably, the temperature is lower by 50 ° C. or less, and most preferably by 50 ° C. or more and 100 ° C. or less. That is, when this melting point is (Tm), the surface temperature of the flat roll is preferably (Tm-30) ° C. or higher and (Tm-120) ° C. or lower, and (Tm-40) ° C. or higher (Tm-110). ) ° C. or lower, more preferably (Tm-50) ° C. or higher and (Tm-100) ° C. or lower.

When the surface temperature of the flat roll is lower than (Tm−120) ° C., the heat treatment of the fiber web becomes insufficient, and the target sheet thickness cannot be obtained, the adhesion becomes insufficient, and the surface smoothness Is not preferable. On the other hand, when the surface temperature of the flat roll is higher than (Tm-30) ° C., the heat treatment becomes too strong, and the constituent fibers in the surface layer portion are in a fused state, so that sufficient mechanical strength cannot be obtained.

Also, the time for heat treatment by bringing the flat roll into contact with the fiber web is preferably in the range of 0.01 seconds to 10 seconds. If the time for heat treatment is 0.01 seconds or more, the heat treatment effect of the nonwoven fabric can be sufficiently obtained, the heat treatment is not excessively strong, and sufficient mechanical strength can be obtained. If the heat treatment time is 10 seconds or less, the heat treatment will not be too strong, and the tear strength will not be reduced. A more preferable heat treatment time is 0.02 seconds or more and 9 seconds or less, and a more preferable heat treatment time is 0.03 seconds or more and 8 seconds or less.

In the method for producing a nonwoven fabric for wall covering material according to an embodiment of the present invention, the smoothing treatment using the flat roll is performed by heating and press-contacting the fiber web with a pair of flat rolls in order to smooth one side of the sheet. Most preferably, the nonwoven fabric is continuously brought into contact with one of the flat rolls from the heat-pressing portion. That is, a method of performing heat treatment by forming a nonwoven fabric by heating and press-contacting a fiber web with a pair of flat rolls at a heat-pressing portion, and continuously contacting one side of the nonwoven fabric with one flat roll from the heat-pressing portion is important. .

The method of contacting with the above flat roll is not limited to a specific method as long as it can be continuously brought into contact with one flat roll from the heating and press-contacting portion and heat-treated. A method in which a fiber web is heated and pressed between a pair of flat rolls at a heating and pressing portion and then brought into contact with one flat roll at a contact portion having a predetermined length. For example, as shown in FIG. A method of winding the fiber web around the flat roll in an S shape (or an inverted S shape) may be used.

The linear pressure when the fiber web is pressed by a pair of flat rolls is preferably in the range of 500 N / cm to 1100 N / cm, more preferably in the range of 510 N / cm to 1090 N / cm. When the linear pressure is 500 N / cm or more, a linear pressure sufficient for sheet formation can be obtained. When the linear pressure is 1100 N / cm or less, the adhesion between the fibers does not become too strong, and therefore the tear strength of the obtained nonwoven fabric does not decrease.

Further, it is preferable that the contact with the continuous flat roll from the heat-welded part of the nonwoven fabric is performed in a state where a tension of 5 N / m or more and 200 N / m or less is applied in the running direction of the nonwoven fabric. A tension of 5 N / m or more is preferable because the tendency of the nonwoven fabric to be wound around the flat roll is reduced. If the tension is 200 N / m or less, the nonwoven fabric is less likely to be cut, which is a preferred direction. A more preferable tension range is 8 N / m or more and 180 N / m or less.

Furthermore, when the non-woven fabric is continuously brought into contact with the flat roll from the heat-pressing portion, the contact distance is preferably in the range of 40 cm to 250 cm. When the contact distance is 40 cm or more, the smoothing effect is sufficient, and a nonwoven fabric excellent in printing processability is obtained. When the contact distance is 250 cm or less, the heat treatment becomes too strong and the tear strength does not decrease. A more preferable contact distance is in the range of 50 cm to 200 cm.

Next, the non-woven fabric for wall covering material according to one embodiment of the present invention and a method for producing the same will be specifically described based on Examples. In the measurement of each physical property, those not specifically described are those measured based on the above method.

[Measuring method]
(1) Intrinsic viscosity (IV):
The intrinsic viscosity (IV) of the polyethylene terephthalate resin was measured by the following method. 8 g of a sample was dissolved in 100 ml of orthochlorophenol, and the relative viscosity η _r was determined by the following formula using an Ostwald viscometer at a temperature of 25 ° C.
Η _r = η / η ₀ = (t × d) / (t ₀ × d ₀ )
(Where η is the viscosity of the polymer solution, η ₀ is the viscosity of the orthochlorophenol, t is the drop time of the solution (seconds), d is the density of the solution (g / cm ³ ), t ₀ is the orthochlorophenol Drop time (seconds), d ₀ represents the density (g / cm ³ ) of orthochlorophenol, respectively.
Next, the intrinsic viscosity (IV) was calculated from the above relative viscosity η _r by the following formula.
Intrinsic viscosity (IV) = 0.0242 η _r +0.2634

(2) Melting point (° C):
The melting point of the thermoplastic resin used was measured under the above conditions using a differential scanning calorimeter (TA Instruments Q100), and the average value of the endothermic peak apex temperatures was calculated as the melting point of the measurement object.

(3) Surface roughness SMD (μm) of wall covering nonwoven fabric by KES method:
The surface roughness of the uncollected net surface was measured using a KES-FB4-AUTO-A automated surface tester manufactured by Kato Tech.

(4) Tear strength of nonwoven fabric for wall covering (N):
“RTG-1250” manufactured by Baldwin was used as a low-speed extension type tensile tester.

(5) Aeration rate of non-woven fabric for wall covering material (cc / cm ² / sec):
For the air flow test, an air permeability tester FX3300 manufactured by Textex was used.

[Example 1]
(Fiber web)
A composite fiber composed of a core component and a sheath component was used as a fiber mainly composed of a thermoplastic resin. Below, it shows about the used thermoplastic resin.
Core component (high melting point long fiber): an intrinsic viscosity (IV) of 0.65, a melting point of 260 ° C., and a polyethylene terephthalate resin containing 0.3% by mass of titanium oxide dried to a moisture content of 50 ppm or less.
Sheath component (low melting long fiber): intrinsic viscosity (IV) 0.66, isophthalic acid copolymerization rate 10 mol%, melting point 230 ° C., and copolymer polyethylene terephthalate resin containing 0.2% by mass of titanium oxide Dried to 50 ppm or less.

The core component was melted at 295 ° C. and the sheath component was melted at 280 ° C., and the composite ratio of core / sheath was 80/20 in mass ratio to form a concentric core-sheath type with a circular cross section. After spinning, spinning with an air soccer at a spinning speed of 4300 m / min was made into a thermoplastic continuous filament. Then, this filament is passed through a nozzle that swings at 36 degrees to the left and right with respect to the web traveling direction, and the filament collides with a metal collision plate installed at the nozzle outlet to charge and open the fiber by friction charging. It was collected as a fiber web on a moving net conveyor. The moving speed of the net conveyor was adjusted so that the collected fiber web had a basis weight of 90 g / m ² .

(Thermo-compression bonding)
The fiber web is thermocompression-bonded with a pair of upper and lower flat rolls at a flat roll surface temperature of 160 ° C. and a linear pressure of 588 kg / cm, and the pressure-bonded sheet is continuously transferred from the heating pressure contact portion to the surface of one flat roll. Contact was made for 2.9 seconds over 120 cm.

By the above treatment, a spunbonded nonwoven fabric having a fiber diameter of 14 μm and a basis weight of 90 g / m ² was obtained.
The obtained non-woven fabric for wall covering material has an air permeability of 50 cc / cm ² / sec, a thickness of 0.20 mm, a smooth surface roughness SMD of 0.75 μm, and a vertical tear strength per unit weight of 0.96 N / It was (g / m ² ), and the portion where the fibers other than the intersection were fused to the surface to form a film (film) was not seen.

[Example 2]
In Example 1, the fiber web was obtained by the same method as Example 1 except having adjusted the moving speed of the net conveyor so that a fabric weight might be 100 g / m < ² >. The fiber web is thermocompression bonded with a pair of upper and lower flat rolls at a flat roll surface temperature of 160 ° C. and a linear pressure of 588 N / cm, and the pressure-bonded sheet is continuously transferred from the heating pressure contact portion to the surface of one flat roll. Contact was made over 120 cm for 3.2 seconds.

The obtained nonwoven fabric for wall covering of Example 2 has an air permeability of 45 cc / cm ² / sec, a thickness of 0.23 mm, a smooth surface roughness SMD of 0.80 μm, and a vertical tear strength per unit area. The portion was 0.88 N / (g / m ² ), and a portion where fibers other than the intersections were fused on the surface to form a film (film shape) was not seen.

[Example 3]
In Example 1, the fiber web was obtained by the same method as Example 1 except having adjusted the moving speed of the net conveyor so that a fabric weight might be 110 g / m < ² >. The fiber web is thermocompression bonded with a pair of upper and lower flat rolls at a flat roll surface temperature of 160 ° C. and a linear pressure of 588 N / cm, and the pressure-bonded sheet is continuously transferred from the heating pressure contact portion to the surface of one flat roll. Contact was made over 120 cm for 3.5 seconds.

The obtained nonwoven fabric for wall covering of Example 3 has an air permeability of 41 cc / cm ² / sec, a thickness of 0.26 mm, a smooth surface roughness SMD of 0.84 μm, and a vertical tear strength per unit area. The portion was 0.87 N / (g / m ² ), and a portion in which fibers other than the intersections were fused on the surface to form a film (film shape) was not seen.

[Comparative Example 1]
A fiber web was obtained in the same manner as in Example 1. The fiber web was thermocompression bonded with a pair of upper and lower flat rolls at a flat roll surface temperature of 180 ° C. and a linear pressure of 588 N / cm.
By the above treatment, a spunbonded nonwoven fabric having a fiber diameter of 14 μm and a basis weight of 90 g / m ² was obtained.
The obtained non-woven fabric for wall covering material has an air permeability of ² cc / cm ² / sec, a thickness of 0.11 mm, a smooth surface roughness SMD of 0.98 μm, and a vertical tear strength per unit weight of 0.06 N / (G / m ² ), and a portion where fibers other than the intersection were fused to form a film (film) was observed.

[Comparative Example 2]
A fiber web was obtained in the same manner as in Example 1. The fiber web is thermocompression bonded with a pair of upper and lower flat rolls at a flat roll surface temperature of 160 ° C. and a linear pressure of 60 kg / cm, and the pressure-bonded sheet is continuously transferred from the heating pressure contact portion to the surface of one flat roll. After contacting for 120 seconds over 120 cm, partial thermocompression bonding with an embossing roll was performed to obtain a spunbonded nonwoven fabric having a fiber diameter of 14 μm and a basis weight of 90 g / m ² . The obtained non-woven fabric for wall covering has an air permeability of 50 cc / cm ² / sec, a thickness of 0.32 mm, a smooth surface roughness SMD of 2.32 μm, and a vertical tear strength per unit area of 0.99 N / It was (g / m ² ), and a portion where fibers other than the intersection were fused to form a film (film shape) was not seen.

<Summary>
As shown in Table 1, the nonwoven fabric is composed of fibers mainly composed of a thermoplastic resin, and the fibers are fused at the intersection of the fibers on the surface of the nonwoven fabric, and other than the intersection Fibers are spaced apart from each other, and at least the surface roughness SMD of the sheet on one side by the KES method is 1.2 μm or less, and the vertical tear strength per unit weight is 0.50 N / (g / m ² ) or more. By doing so, the nonwoven fabric for wall covering materials excellent in resin workability and workability was obtained.

On the other hand, as shown in Table 1, the non-woven fabric for wall covering material of Comparative Example 1 had a smooth surface roughness SMD by the KES method, but the fibers other than the intersections were fused to form a film. As a result, the vertical tear strength per unit weight was low and the mechanical strength was inferior.
The nonwoven fabric for wall covering material of Comparative Example 2 had a high vertical tear strength per unit area and an excellent mechanical strength, but was inferior to the surface roughness of the smooth surface.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on May 31, 2018 (Japanese Patent Application No. 2018-104587), which is incorporated by reference in its entirety.

The nonwoven fabric for wall covering material according to one embodiment of the present invention has less fuzz and is excellent in resin processability and workability, and particularly in a wide range of fields including nonwoven fabrics installed on the walls and ceilings of buildings. Can be suitably used.

1: Fiber web 2: Heat-bonding part 3: Non-woven fabric and flat roll contact part 4a: Upper roll 4b: Lower roll 5: Arrow indicating the traveling direction of the fiber web

Claims

A nonwoven fabric composed of fibers mainly composed of a thermoplastic resin, wherein the fibers are fused at the intersection of the fibers on the surface of the nonwoven fabric, and the fibers other than the intersection are separated from each other. Furthermore, the nonwoven fabric for wall coverings has a surface roughness SMD of at least 1.2 μm or less per sheet and a vertical tear strength per unit area of 0.50 N / (g / m 2 ) or more.
The basis weight of the nonwoven fabric for wall covering is 80 g / m 2 or more and 130 g / m 2 or less, the thickness of the nonwoven fabric for wall covering is 0.18 mm or more and 0.31 mm or less, and the wall covering The non-woven fabric for wall covering according to claim 1, wherein the air permeability of the non-woven fabric is 30 cc / cm 2 / sec or more and 60 cc / cm 2 / sec or less.
The non-woven fabric for wall covering according to claim 1 or 2, wherein the non-woven fabric is a spunbonded non-woven fabric made of long fibers.
Thermocompression bonding at a linear pressure of 500 N / cm to 1100 N / cm with a pair of flat rolls heated to a low temperature of 30 ° C. or higher and 120 ° C. or lower with respect to the melting point of the lowest melting point thermoplastic resin constituting the surface of the fiber The method for producing a non-woven fabric for wall covering according to any one of claims 1 to 3, further comprising a step of continuously contacting the flat roll for a predetermined time after the step.