KR102484011B1 - Wet-laid non-woven fabric, Sound absorbing composite and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to a wet-laid nonwoven fabric, a sound-absorbing composite material using the same, and a method for manufacturing the same, and more specifically, a wet-laid nonwoven fabric manufactured using specific fibers without binder fibers, and the sound-absorbing composite material using the same has excellent isotropic properties and pore characteristics Since this is even, mechanical properties such as modulus and tensile strength, sound absorption, sound insulation and light weight are excellent, and thus it can be used as a sound absorbing material for interior and exterior materials of various means of transportation, electronic products, buildings and interiors.

Description

Wet-laid non-woven fabric, sound absorbing composite including the same, and manufacturing method thereof {Wet-laid non-woven fabric, Sound absorbing composite and Manufacturing method thereof}

The present invention relates to applied products such as a wet-laid nonwoven fabric manufactured without binder fibers using specific fibers and a sound-absorbing composite using the same, and a manufacturing method thereof, and also relates to applied products thereof.

The types of noise sources such as vacuum cleaners, dishwashers, washing machines, air conditioners, air purifiers, computers, projectors, etc. are becoming more diverse, and accordingly, noise pollution problems are becoming more and more serious. Therefore, in this modern life, efforts are being made to block or reduce noise generated from various noise sources, and in overseas advanced countries, legal regulations to regulate the level of noise between floors and households of multi-family houses such as apartments are becoming increasingly strict. .

In addition, with the recent improvement in the emotional quality of consumers, the improvement of NVH (noise, vibration, harshness) performance of automobiles is a requirement of the times, and the demand for NVH-related parts is rapidly increasing. Typical noises entering the interior of various transport aircraft are engine noise generated by the engine and transmitted through the vehicle body or air, and friction noise between wheels and the ground. In order to suppress these noises, engine covers and hood insulation are used. The application of sound absorbing and insulating materials to parts such as underbody covers that require a large area is expanding.

There are two ways to improve noise: improving sound absorption performance and improving sound insulation performance. Sound absorption means that the generated sound energy is transmitted through the internal path of the material and converted into thermal energy to be extinguished. It is reflected and blocked by the shield.

Felt, sponge, polyurethane foam, etc. are mainly used as conventional sound absorbing and insulating materials. In addition, sound absorbing materials impregnated with thermoplastic resin or thermosetting resin such as compressed fiber, glass fiber, rock wool, or regenerated fiber can be listed. can However, most of the sound absorbing materials described above do not have sufficient sound insulation performance, and most of the sound absorbing materials contain components harmful to the human body. In addition, felt-type fiber materials currently used in various interior and exterior materials for transportation are manufactured in a physically intertwined state with binder fibers using a dry non-woven fabric manufacturing process. This is determined and the manufacturing process is complicated, so there is a problem of low economic feasibility.

In recent years, regulations on eco-friendliness and recycling are gradually being strengthened in each country, so the use rate of fiber sound-absorbing materials based on thermoplastic resins is increasing. In addition, fuel efficiency regulations of vehicles are gradually intensifying in order to reduce carbon dioxide. Since fuel efficiency can be improved by reducing the weight of parts, it is necessary to develop a lightweight sound absorbing material with improved performance.

Accordingly, research and development on a sound absorbing material that is harmless to the human body and has an excellent sound absorbing function that can effectively absorb and reduce noise while reducing its thickness has been actively conducted.

As a conventionally researched and developed sound absorbing material, a sound absorbing material in the form of a web containing 10% by weight or more of general short fibers having a diameter of 10 μm or more crimped into general meltblown fibers has been disclosed (U.S. Patent Publication No. 1954-433600). A sound-absorbing material and heat-retaining material in the form of a web containing bulky fibers crimped into melt-blown fibers has been disclosed. In addition to not providing a sufficient sound absorbing effect, there is a problem in that the thickness of the sound absorbing material should be greatly increased in order to provide a sufficient sound absorbing effect.

In addition, a sound absorbing material, which is a three-dimensional nonwoven fabric web formed by melt-blown ultrafine fibers, has been disclosed. However, the three-dimensional nonwoven fabric web has a large porosity and is not dense in structure, so it lacks durability. In order to provide the 3D nonwoven web, the thickness of the 3D nonwoven web should be greatly increased, and manufacturing of the 3D nonwoven web as described above is difficult, resulting in a significant increase in manufacturing cost. In addition to this, a sound absorbing material is disclosed which is characterized by containing staple fibers capable of being fused by heat to meltblown fibers in order to impart three-dimensional stability, but such a sound absorbing material still has a problem in that it lacks sound insulation performance. In addition, a sound absorbing material using a honeycomb structure having a plurality of spaces together with meltblown fibers has been disclosed, but such a sound absorbing material has a problem in that its use is limited due to insufficient soundproofing performance and lack of flexibility.

Korean Patent Publication No. 10-2011-0122566 (published on November 10, 2011) Korean Patent Publication No. 10-2010-0015043 (published on February 12, 2010)

As a result of efforts to manufacture a new sound-absorbing material, the present invention intends to provide a wet-laid nonwoven fabric that can be manufactured with only single fibers without binder fibers by using fibers of a core-sheath structure having a specific ratio and specific physical properties. It is intended to provide a sound-absorbing composite material having excellent sound absorption and sound insulation properties and a method for manufacturing the same.

In order to solve the above problems, the present invention relates to a wet-laid nonwoven fabric including a fiber-reinforced resin-integrated short cut fiber of a core-sheath structure.

As a preferred embodiment of the present invention, the short cut fiber may have an average fineness of 1 to 5 denier and an average fiber length of 1.5 mm to 15 mm.

As a preferred embodiment of the present invention, the core (or core portion) of the short cut fiber includes polyethylene terephthalate (PET) having an intrinsic viscosity of 0.65 to 0.80, and the sheath (or sheath portion) is polyethylene having an intrinsic viscosity of 0.60 to 0.66 terephthalate.

As a preferred embodiment of the present invention, PET of the core (or core part) of the short cut fiber may have a melting point of 250 ° C to 260 ° C, and PET of the sheath may have a melting point of 210 ° C to 240 ° C.

As a preferred embodiment of the present invention, the cross-sectional area ratio of the core and sheath of the short cut fiber may be 58 to 92: 8 to 42.

As a preferred embodiment of the present invention, the short cut fiber may have strength of 3.0 to 5.4 g/d and elongation of 25% to 55%.

As a preferred embodiment of the present invention, the PET of the cis is a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 86 to 90: 10 to 14; and diol; may include a PET polymer polymerized in a molar ratio of 1:0.95 to 1.

As a preferred embodiment of the present invention, the high molecular weight PET of the core may include a PET polymer polymerized with terephthalic acid and diol in a molar ratio of 1:0.95 to 1, followed by solid-state polymerization at 190 ° C. to 220 ° C. under a nitrogen atmosphere. there is.

As a preferred embodiment of the present invention, the wet-laid nonwoven fabric of the present invention may have an average surface density of 30 to 150 g/m ² .

Another object of the present invention relates to a sound-absorbing composite using various types of wet-laid nonwoven fabrics described above.

As a preferred embodiment of the present invention, the sound-absorbing composite of the present invention has a multi-layer structure in which the wet-laid nonwoven fabric is laminated in 3 to 30 layers.

As a preferred embodiment of the present invention, the sound-absorbing composite of the present invention may have an average surface density of 1,000 to 1.500 g/m ² .

As a preferred embodiment of the present invention, the sound-absorbing composite material of the present invention may have a tensile strength of 160 to 350 Mpa when the average surface density of the sound-absorbing composite material is 1,200 g/m ² .

As a preferred embodiment of the present invention, the sound-absorbing composite of the present invention has an average surface density of 1,200 g / m ² of the sound-absorbing composite, when measuring the sound absorption coefficient in accordance with the alpha cabin method of ISO R 354, at 1,000 Hz It may have a sound absorption coefficient of 0.52 or more, a sound absorption coefficient of 0.61 or more at 2,000 Hz, a sound absorption coefficient of 0.74 or more at 3,150 Hz, and a sound absorption coefficient of 0.88 or more at 5,000 Hz.

As a preferred embodiment of the present invention, the sound-absorbing composite of the present invention has a transmission loss at 1,000 Hz when measuring transmission loss using APAMAT-II (Autoneum) equipment when the average surface density of the sound-absorbing composite is 1,200 g / m ² 23 to 24 dB, the transmission loss at 2,000 Hz is 24 to 26 dB, the transmission loss at 3,150 Hz is 34 to 37 dB, and the transmission loss at 5,000 Hz may be 42 to 45 dB.

Another object of the present invention relates to a method for producing the sound-absorbing composite, comprising: a first step of preparing core-sheath polyethylene terephthalate (PET) short fibers; A second step of producing a sub-tow by stretching and heat-treating the PET short fibers; A third step of cutting the sub-tow into 1.5 mm to 12 mm to produce fiber-reinforced resin-integrated short-cut fibers; Step 4 of adding an acrylic binder to the dispersion in which the short cut fibers are dispersed in water, stirring and mixing to form a web in a paper machine, and then drying to prepare a wet nonwoven fabric; and 5 steps of stacking the wet-laid nonwoven fabric in 3 to 30 layers and then integrating the compressed and wet-laid nonwoven fabric through a hot press process to manufacture a sound-absorbing composite material.

As a preferred embodiment of the present invention, the core-sheath PET short fiber in the first step may be manufactured by composite spinning so that the high molecular weight PET resin becomes the core part and the low melting point PET resin becomes the sheath part. .

As a preferred embodiment of the present invention, the dispersion contains 0.02 to 0.2% by weight of short cut fibers and the balance of water, and the acrylic binder is 5 to 10 parts by weight of acrylic binder based on 100 parts by weight of short cut fibers in the dispersion. can be added to

As a preferred embodiment of the present invention, the composite spinning is performed under conditions of 280 ° C. to 300 ° C. and winding speed of 800 to 1,200 m / min, so that the cross-sectional area ratio of the core part and the sheath part is 58-92: 8-42 PET short fibers. may have been manufactured.

As a preferred embodiment of the present invention, the low-melting PET resin is a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 86 to 90: 10 to 14; and diol; may include a PET polymer polymerized with a molar ratio of 1:0.95 to 1.

As a preferred embodiment of the present invention, the high molecular weight PET resin is obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:0.95 to 1, and then solid phase polymerization at 190 ° C to 220 ° C and nitrogen atmosphere. May contain polymers.

As a preferred embodiment of the present invention, the high molecular weight PET has a melting point of 250 ° C to 260 ° C and an intrinsic viscosity of 0.65 to 0.80, and the low melting point PET has a melting point of 210 ° C to 240 ° C and an intrinsic viscosity of 0.60 to 0.66. can have

As a preferred embodiment of the present invention, the stretching of the second step may be performed by stretching the PET short fibers 2.5 to 4 times at 75 ° C to 85 ° C.

As a preferred embodiment of the present invention, the two-step heat treatment may be performed at 140 ° C to 170 ° C.

As a preferred embodiment of the present invention, the five-step hot press process may be performed at 210 °C to 280 °C and 80 to 120 ton/cm ² .

Another object of the present invention can be applied to automotive interior and/or exterior materials, sound absorbing materials for electronic and electrical devices such as refrigerators and air conditioners, and sound absorbing materials for construction using the sound absorbing composite described above.

Unlike dry nonwoven fabrics that undergo a carding process, the nonwoven fabric of the present invention is a wet nonwoven fabric that has a simple manufacturing process and maximizes economic feasibility because it does not require binder fibers. Since the pore characteristics are even, mechanical properties such as modulus and tensile strength, sound absorption, sound insulation, and light weight are excellent. The sound-absorbing composite material of the present invention is applied to interior and exterior sound-absorbing materials for vehicles, airplanes, ships, etc., sound-absorbing materials for electronic parts such as mobile phones, laptop computers, computers, TVs, refrigerators, and air conditioners, and sound-absorbing materials for interior materials for buildings. suitable for doing

1 and 2 are SEM measurement pictures of the cut surfaces of the sound-absorbing fiber assembly prepared in Example 1.

Hereinafter, the present invention will be described in more detail.

In the present invention, after preparing a sub-tow with a specific core-sheath polyethylene terephthalate (PET) short fiber, it is shortened into a fiber, and then the short-cut fiber is wet-laid through a wet process to prepare a wet-laid nonwoven fabric. Then, the wet-laid nonwoven fabric is compressed to produce a sound-absorbing composite material.

Describing the method for manufacturing the sound-absorbing composite of the present invention in more detail, a first step of preparing core-sheath polyethylene terephthalate (PET) short fibers; A second step of producing a sub-tow by stretching and heat-treating the PET short fibers; A third step of cutting the sub-tow into 1.5 mm to 12 mm to produce fiber-reinforced resin-integrated short-cut fibers; Step 4 of adding an acrylic binder to the dispersion in which the short-cut fibers are dispersed in water, then performing conjugate spinning to form a web and drying to prepare a wet-laid nonwoven fabric; and a fifth step of stacking the wet-laid nonwoven fabric in multiple layers and then integrating the compressed and wet-laid nonwoven fabric through a hot press process.

In addition, a sixth step of molding the compressed and integrated wet-laid nonwoven fabric into a specific shape may be further included.

In the first step, the core-sheath PET short fiber is composed of a high molecular weight PET resin in the core part and low melting point PET fiber in the sheath part.

The low-melting PET resin is a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 86 to 90:10 to 14, preferably 87 to 88:12 to 13; and diol; in a molar ratio of 1:0.95 to 1, preferably, the mixture and the diol are polymerized in a molar ratio of 1:0.97 to 1. At this time, if the molar ratio of isophthalic acid is less than 10, there may be problems in the press and molding process due to a decrease in adhesiveness and a decrease in melting point difference with the core part, and if the molar ratio of isophthalic acid exceeds 14, crystallinity disappears and the melting point Therefore, there may be a problem in that the shape stability of the final molded product is lowered in a heat-resistant environment.

The low-melting PET resin prepared by polymerization has a melting point of 210 ° C to 240 ° C and an intrinsic viscosity (IV) of 0.60 to 0.66, preferably a melting point of 220 ° C to 235 ° C and an intrinsic viscosity (IV) of 0.61 to 0.65. there is. At this time, if the melting point of the low-melting PET resin is less than 210 ° C, the shape stability of the fiber in a heat-resistant environment may decrease, and if the melting point of the low-melting PET resin exceeds 240 ° C, the melting point difference between the core and the high molecular weight PET decreases. There may be problems in the pressing and forming process.

In addition, the high molecular weight PET resin is a PET resin obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:0.95 to 1, followed by solid state polymerization at 190° C. to 220° C. under a nitrogen atmosphere. And, the high molecular weight PET resin has a melting point of 250 ° C to 260 ° C and an intrinsic viscosity (IV) of 0.65 to 0.80, preferably a melting point of 255 ° C to 259 ° C and an intrinsic viscosity (IV) of 0.69 to 0.75. At this time, if the high molecular weight PET resin has an intrinsic viscosity (IV) of less than 0.65, there may be a problem of strength deterioration, and if the intrinsic viscosity (IV) exceeds 0.80, spinning and stretching workability may be difficult.

In addition, the core-sheath PET short fibers of the first step are prepared by spinning the high molecular weight PET resin and the low melting point PET resin at a spinning temperature of 280 ° C to 300 ° C and a winding speed of 500 to 1,200 m / min, preferably at a spinning temperature of 285 ° C. ~ 295 ℃ and winding speed 600 ~ 1,150 m / min under conditions of composite spinning, the core and sheath have a cross-sectional area ratio of 58 to 92: 8 to 42, preferably a cross-sectional area ratio of 65 to 90: 10 to 35 Produces PET short fibers. At this time, if the cross-sectional area ratio of the sheath is less than 8, there may be a problem of poor adhesion (or bonding force) between fibers in the wet-laid nonwoven fabric prepared using this, and if the cross-sectional area ratio of the sheath exceeds 42, there may be a problem of poor sound absorption.

In addition, when the spinning temperature is less than 280 ° C, there may be problems in that pack internal pressure increases and spinning workability decreases, and when the spinning temperature exceeds 300 ° C, physical properties may deteriorate. In addition, if the winding speed is less than 500 m / min, elongation may increase and the physical properties of the final molded product may deteriorate, and if the winding speed exceeds 1,200 m / min, the unstretched sub-tow may be a can ( CAN) may have a problem of deterioration in stretching workability due to non-uniformity of the laminated form.

In the present invention, the stretching of the second step may be performed through a general method used in the art, and preferably, the PET short fiber is 2.5 to 4 times under 75 ℃ to 85 ℃, preferably 3.0 to 3.5 times. It can be done by stretching it twice. At this time, if the stretching ratio is less than 2.5 times, the elongation may increase and the physical properties of the final molded product may deteriorate, and if the stretching ratio exceeds 4.0 times, thread breakage may occur, resulting in reduced stretching workability and product yield. .

In addition, the two-step heat treatment is a process of heat-setting the stretched fiber, and a general method used in the art can be used. For example, after putting the stretched fiber into an oven, 140 ° C. to 170 ° C. Under ℃, preferably at 145 ℃ ~ 160 ℃ can be carried out for 10 to 20 minutes. At this time, if the heat treatment temperature is less than 140 ℃, there may be a problem that the shrinkage rate of the short cut fiber increases in the molding process, and if it exceeds 170 ℃, due to the decrease in the physical properties of the short cut fiber, the dispersibility during wet-laid processing Since there may be a problem of deterioration, it is preferable to perform heat treatment at the above temperature.

In addition, the three-step fiber-reinforced resin-integrated short cut fiber may have a strength of 3.0 to 5.4 g / d and an elongation of 25% to 55%, preferably a strength of 3.5 to 5.4 g / d and an elongation of 35% to 50%, more preferably Preferably, the strength may be 3.8 to 5.0 g/d and the elongation may be 37% to 50%.

In the present invention, step 4 is a process for producing a wet-laid nonwoven fabric using the fiber-reinforced resin-integrated short cut fibers prepared in step 3, and the short-cut fibers have an average fineness of 1 to 5 denier and an average fiber length of 1.5 mm to 15 mm, preferably Preferably, it may have an average fineness of 1 to 3 denier and an average fiber length of 4 mm to 14 mm, more preferably an average fineness of 1 to 2.5 denier and an average fiber length of 6 mm to 12 mm.

After adding an acrylic binder to the dispersion in which the short-cut fibers are dispersed in water, a web is formed by performing conjugate spinning, and then drying is performed to prepare a wet-laid nonwoven fabric. At this time, composite spinning and drying may be performed through a general method used in the art.

And, the dispersion may include 0.01 to 0.1% by weight of the short cut fiber and the remaining amount of water. Then, based on 100 parts by weight of the short cut fiber, 5 to 10 parts by weight of an acrylic binder is added to the dispersion, and then composite spinning is performed.

The wet-laid nonwoven fabric thus prepared may have an average surface density of 30 to 150 g/m ² , preferably 50 to 130 g/m ² , and more preferably 60 to 120 g/m ² , in FIGS. 1 and 2 As can be seen in the SEM measurement photograph of the cut surface of the wet-laid non-woven fabric, it is possible to manufacture a wet-laid non-woven fabric formed of only single core-sheath fibers without using heterogeneous binder fibers.

In the present invention, step 5 is a process of manufacturing a sound-absorbing composite from the wet-laid nonwoven fabric prepared in step 4, and the wet-laid nonwoven fabric has 3 to 30 layers, preferably 5 to 25 layers, more preferably 7 to 20 layers This is a process of manufacturing a sound-absorbing composite by integrating the compressed and wet-laid nonwoven fabric through a hot press process after stacking them in layers.

The hot press process may be performed at 210°C to 280°C and 80 to 120 ton/cm ² pressure, preferably at 215°C to 250°C and 90 to 110 ton/cm ² pressure, wherein the temperature is 210°C. If it is less than 280 ° C., the bonding strength between the laminated wet nonwoven fabrics may decrease, and if it exceeds 280 ° C., the bonding area between the short cut fibers may increase, resulting in a decrease in the pore structure and consequently a decrease in sound absorption performance and appearance quality. In addition, when the pressure is less than 80 ton/cm ² , the average surface density of the sound-absorbing composite may be low, resulting in poor sound-absorbing performance, and even when the pressure exceeds 120 ton/cm ² , there is no significant effect on improving the sound-absorbing performance. It is preferable to perform the hot press process within

The sound-absorbing composite produced by performing the hot press process may have an average surface density of 1,000 to 1,500 g/m ² , preferably an average surface density of 1,050 to 1,400 g/m ² , and more preferably 1,100 to 1,350 g/m ² . At this time, if the average surface density of the sound-absorbing composite is less than 1,000 g/m ² , mechanical properties may be poor, and if it exceeds 1,500 g/m ² , the sound-absorbing performance may deteriorate. It is preferable to have an average surface density within the above range.

Since the sound-absorbing composite material of the present invention has excellent isotropy and even pore characteristics, it has excellent mechanical properties such as modulus and tensile strength, and has a tensile strength of 160 to 350 Mpa, preferably 170 to 250 MPa, and more preferably 180 to 220 MPa. It may have a tensile strength of MPa.

In addition, when the sound-absorbing composite of the present invention has an average surface density of 1,200 g / m ² , when the sound absorption coefficient is measured according to the alpha cabin method of ISO R 354, it is 0.52 or more at 1,000 Hz, preferably 0.52 to 0.54 , has a sound absorption coefficient of 0.61 or more, preferably 0.61 to 0.63 at 2,000 Hz. In addition, the sound absorption coefficient may be 0.74 or more at 3,150 Hz, preferably 0.74 to 0.78, and the sound absorption coefficient at 5,000 Hz, which is a high frequency band, may be 0.88 or more, preferably 0.88 to 0.92.

In addition, the sound-absorbing composite of the present invention has a transmission loss of 23 to 24 dB at 1,000 Hz and transmittance at 2,000 Hz when measuring transmission loss using APAMAT-II (Autoneum Co.) equipment when the average surface density is 1,200 g / m ² The loss is 24 ~ 26 dB, the transmission loss is 34 ~ 37 dB at 3,150 Hz, and the transmission loss is 42 ~ 45 dB at 5,000 Hz.

Step 6 is a process of molding (or processing) to suit the intended use, and molding (or processing) can be performed by a general method used in the art.

In the sound-absorbing composite material of the present invention, a cover layer (or support layer) may be further formed to serve as a cover.

Hereinafter, the present invention will be described in more detail through examples, but the following examples are not intended to limit the scope of the present invention, which should be interpreted to aid understanding of the present invention.

[ Example ]

preparation example One : for sis low melting point Manufacture of PET resin

After preparing a mixture in which 88 mol% of terephthalic acid and 12 mol% of isophthalic acid were mixed as an acid component, 100 mol% of ethylene glycol was used as the mixture and the diol component to obtain the mixture (acid component) and the diol component in a molar ratio of 1: After mixing with 1, a polymerization reaction was performed to prepare a low melting point PET resin, and its physical properties are shown in Table 1 below.

comparative preparation example One : for sis low melting point Manufacture of PET resin

A low-melting PET resin was prepared in the same manner as in Preparation Example 1, but a mixture of 78 mol% of terephthalic acid and 22 mol% of isophthalic acid was mixed 1:1 with ethylene glycol and then polymerized to prepare a low-melting PET resin.

preparation example 2: Preparation of high molecular weight PET resin for core

After mixing terephthalic acid as an acid component with ethylene glycol as a diol in a molar ratio of 1:0.98, solid phase polymerization was performed at 200 ° C. under a nitrogen atmosphere to prepare a high molecular weight PET resin, and its physical properties are shown in Table 1 below.

comparative preparation example 2: for core high molecular weight PET profit

A PET resin (Toray Chemical Co., Ltd.) having a melting point of 265° C. and an intrinsic viscosity (IV) of 0.84 was prepared.

division melting point Intrinsic Viscosity (IV) Preparation Example 1 (cis) 230℃ 0.65 Comparative preparation example 1 (cis) 205℃ 0.59 Preparation Example 2 (Core) 258℃ 0.75 Comparative preparation example 2 (core) 260℃ 0.82

Example 1: Manufacture of wet-laid nonwoven fabric

The low melting point PET resin of Preparation Example 1 and the high molecular weight PET resin of Preparation Example 2 were composite-spun at a spinning temperature of 295 ° C. and a take-up speed of 1,000 m/min using a composite spinneret to prepare sheath-core short fibers. At this time, composite spinning was performed so that the core portion and the sheath portion of the short fibers had a cross-sectional area ratio of 75:25.

Next, the conjugate-spun sheath-core short fibers were stretched 3.3 times at 79°C.

Next, the elongated short fibers were put into an oven, and then subjected to final heat treatment at 150° C. to prepare a sub-tow, and then cut to 12 mm to produce fiber-reinforced resin-integrated short cut fibers.

The manufactured fiber-reinforced resin-integrated short cut fiber had an average fineness of 1.5 denier, an average fiber length of 12 mm, a strength of 4.1 g/d, and an elongation of 40%.

Next, a dispersion was prepared by dispersing the fiber-reinforced resin-integrated short cut fibers in water at a concentration of 0.08% by weight. Next, 7 parts by weight of an acrylic binder was added to the dispersion based on 100 parts by weight of the shortcomb fibers. Next, the dispersion was stirred and mixed to form a web in a paper machine. Next, the formed web was dried to prepare a wet nonwoven fabric having an average surface density of 100 g/m ² .

Example 2 - Examples 3

A wet-laid nonwoven fabric was prepared under the same conditions as in Example 1, but the composite spinning machine Example 2 Composite spinning was performed so that the core and sheath of short fibers had a cross-sectional area ratio of 90: 10, and in Example 3, composite spinning was performed so that the core and sheath of short fibers had a cross-sectional area ratio of 60: 40 to obtain a fiber-reinforced resin. After the integral short cut fibers were prepared, wet-laid nonwoven fabrics were respectively prepared using them.

comparative example One

A short cut fiber was prepared by composite spinning a PET resin having a melting point of 255 ° C using a single spinneret at a spinning temperature of 295 ° C and a take-up speed of 1,000 m / min.

The sheath-core short fibers were stretched 3.3 times at 79°C.

Next, after putting the stretched short fibers into an oven, a sub-tow is prepared by final heat treatment at 150 ° C., and then cut into 12 mm to short-cut fibers (average fineness of 1.5 denier, average fiber length). 12 mm) was prepared.

Separately, as a binder fiber, a short cut fiber having an average fineness of 2 denier and a fiber length of 12 mm prepared using a general 110 ° C. PET resin was prepared.

Next, after mixing 70% by weight of the short cut fibers and 30% by weight of the binder fibers, a wet process was performed in the same manner as in Example 1 to prepare a wet-laid nonwoven fabric.

Example 4~ Example 6 and comparative example 2~ comparative example 5

Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, but short-cut fibers having the composition and physical properties shown in Table 2 were prepared, and then wet-laid nonwoven fabrics were prepared using them, respectively, Examples 4 to 5 and Comparative Examples 2 to 5 were performed respectively.

comparative example 6~ comparative example 7

A wet-laid nonwoven fabric was prepared under the same conditions as in Example 1, but in Comparative Example 6, short-cut fibers and wet-laid nonwoven fabric were prepared using the low-melting PET resin of Comparative Preparation Example 1 instead of the low-melting point PET of Preparation Example 1, Comparative Example 7 Instead of the high molecular weight PET resin of Preparation Example 2, the high molecular weight PET resin of Comparative Preparation Example 2 was used to prepare short cut fibers and wet-laid nonwoven fabrics.

division short cut fiber cross-sectional area ratio
(core: sheath) short cut fiber
average fineness short cut fiber
average fiber length
(mm) short cut fiber
robbery
(1 g/d) short cut fiber
Shinto
(%) binder fiber
existence and nonexistence Example One 75:25 1.5 denier 12mm 4.1 g/d 40% × Example 2 90:10 1.5 denier 12mm 4.2 g/d 39% × Example 3 60:40 1.5 denier 12mm 3.8g/d 42% × Example 4 75:25 1.5 denier 8mm 4.1 g/d 40% × Example 5 75:25 1.5 denier 4mm 4.1 g/d 40% × Example 6 75:25 3.0 denier 12mm 4.2 g/d 39% × comparative example One - 2 denier 12mm 4.1 g/d 40% ○ comparative example 2 95:5 1.5 denier 12mm 4.4 g/d 38% × comparative example 3 55:45 1.5 denier 12mm 3.8g/d 41% × comparative example 4 75:25 1.5 denier 18mm 4.1 g/d 40% × comparative example 5 75:25 6.0 denier 12mm 3.9 g/d 41% × comparative example 6 75:25 1.5 denier 12mm 4.0g/d 40% × comparative example 7 75:25 1.5 denier 12mm 4.8 g/d 25% ×

Looking at the measurement results of Table 2, the short cut fibers of Examples 1 to 6 showed excellent results in terms of strength and elongation.

However, in the case of Comparative Example 2 in which the cross-sectional area ratio of the sheath portion was less than 8, there was a problem of poor adhesion between fibers in the wet-laid nonwoven fabric.

And, in the case of Comparative Example 4 in which the average fiber length of the short-cut fibers was 18 mm, there was a problem in that the appearance and physical properties of the wet-laid nonwoven fabric were deteriorated due to poor dispersibility of the fibers, and the average fineness of the short-cut fibers exceeded 5.0 denier. In the case of Comparative Example 5, there was a problem in that the dispersibility of the fiber was poor and the appearance quality was lowered and the number of fibers per unit weight was reduced, so the sound absorption performance was lowered.

In the case of Comparative Example 7 using a high molecular weight PET resin having an intrinsic viscosity of more than 0.8, the strength of the shot fiber was excellent, but the elongation was low, resulting in poor drawing workability and web spinning workability during fiber production.

On the other hand, the short cut fibers and wet-laid nonwoven fabrics prepared in Comparative Examples 3 and 6 had good inter-fiber adhesion and shape stability.

Experimental Example One : SEM measurement

A portion of the wet-laid nonwoven fabric prepared in Example 1 was cut and the inside of the nonwoven fabric was measured with a scanning electron microscope (SEM, manufacturer JEOL, trade name JSM 840), and the results are shown in FIGS. 1 and 2.

Looking at Figures 1 and 2, it can be seen that the fibers constituting the nonwoven fabric are composed of single fibers, micropores are formed, and the fibers are bonded through thermal fusion.

manufacturing example One : sound absorption Manufacturing of composites

After laminating 12 wet-laid nonwoven fabrics of Example 1, a hot press process was performed at a temperature of 230° C. and a pressure of 100 ton/cm ² to prepare a sound-absorbing composite material having an average surface density of 1,200 g/m ² .

manufacturing example 2 to 6 and Comparative Manufacturing Example 1 to 6

In the same manner as in Preparation Example 1, sound-absorbing composites were prepared using the wet-laid nonwoven fabrics of Examples 2 to 6 and Comparative Examples 1 to 6, respectively.

Experimental example 2: Tensile strength, sound absorption coefficient by frequency (Hz) and transmission loss (dB) measurement experiment

Samples were prepared using each of the sound-absorbing composites prepared in Examples and Comparative Examples.

At this time, the tensile strength was prepared as 100 mm × 20 mm × 10 mm (width × length × height), the sound absorption measurement was prepared as 1.2m × 1.0m (width × length), and the transmission loss (dB) was 0.84m × 0.84 Samples were prepared by cutting into m (width × length).

In addition, the tensile strength, frequency-specific (Hz) sound absorption coefficient and transmission loss of the sample were measured in the following manner, and the results are shown in Table 3 below.

(1) Load at Tensile Strength, MPa ) measurement

Tensile strength was measured 10 times under the conditions of a tensile speed of 500 mm/min, Road-Cell 2 kN, and Grib 5 kN, and then the average value was determined as the tensile strength.

(2) Measurement of sound absorption coefficient by frequency

In order to measure the sound absorption coefficient, three specimens each of which are applicable to the ISO R 354 and Alpha Cabin methods were prepared, and the sound absorption coefficient was measured after being left for 30 minutes at an external temperature of 0 ° C and 25 ° C. The average value of the measured sound absorption coefficient is shown in Table 2 . Instron ^R was used as the measuring equipment.

(3) Measurement of transmission loss (dB) per frequency

Transmission loss was measured using APAMAT-II (Autoneum Co.) equipment.

division tensile strength
( MPa ) Sound absorption coefficient by frequency (Hz) Transmission loss (dB) per frequency (Hz) 1000
Hz 2000
Hz 3150
Hz 5000
0Hz 1000
Hz 2000
Hz 3150
Hz 5000
Hz Preparation Example 1 220 0.54 0.63 0.75 0.90 23.6 24.9 35.7 44.2 Preparation Example 2 296 0.52 0.62 0.76 0.89 23.8 24.7 35.6 44.9 Preparation Example 3 240 0.53 0.64 0.78 0.91 23.6 24.8 35.3 44.0 Production Example 4 211 0.56 0.67 0.80 0.94 23.4 24.5 34.8 43.1 Preparation Example 5 221 0.53 0.63 0.74 0.89 23.7 25.1 36.2 44.4 Preparation Example 6 180 0.52 0.64 0.74 0.92 24.0 24.7 36.0 43.7 Comparative Manufacturing Example 1 125 0.42 0.53 0.71 0.81 18.2 21.6 30.4 39.7 Comparative Manufacturing Example 2 85 0.50 0.53 0.72 0.80 17.2 20.4 29.7 35.3 Comparative Preparation Example 3 232 0.40 0.58 0.74 0.85 25.2 26.8 36.3 43.8 Comparative Preparation Example 4 201 0.54 0.66 0.70 0.76 21.1 25.2 34.9 46.0 Comparative Manufacturing Example 5 180 0.48 0.58 0.65 0.83 24.5 22.6 32.1 42.0 Comparative Preparation Example 6 156 0.52 0.60 0.69 0.75 23.4 22.2 35.1 41.4

In the case of Comparative Preparation Example 1, when compared to Preparation Example, overall sound absorption coefficient and permeability coefficient showed low results.

And, Comparative Preparation Example 2 had a problem in that the bonding area between the fibers was small, and the physical properties of the nonwoven fabric and the molded article were lowered, so the sound absorption performance was lowered and the tensile strength was greatly lowered.

In addition, the sound absorbing material of Comparative Preparation Example 3 made of short-cut fibers having a cross-sectional area ratio of the sheath portion exceeding 42 showed poor sound absorbing performance in the 1000 Hz frequency band.

In addition, the sound-absorbing composite of Comparative Preparation Example 4 made of short-cut fibers having an average fiber length of 18 mm has poor appearance quality due to deterioration in dispersibility and an increase in the thickness of the composite, so that the sound absorption performance is good in the low frequency band of 1000 to 2000 Hz. Due to the decrease in the number of fibers per unit weight, there was a problem of poor sound absorption performance in the high frequency band. Due to this problem, there was a problem that the sound absorption performance was remarkably lowered.

And, in the case of Comparative Preparation Example 6 using a low-melting PET resin having a melting point of less than 210 ° C, the strength and elongation of the short-cut fiber were adequate, but the shape stability was poor when the wet-laid nonwoven fabric was produced with the short-cut fiber. As a result, the overall sound absorption performance was poor. It is judged that the tensile strength showed a low result.

Through the above Examples and Experimental Examples, it was confirmed that the sound-absorbing composite material of the present invention had excellent tensile strength while having excellent sound-absorbing ability in a low frequency band as well as a high frequency band.

The present invention can be applied to materials requiring sound absorption, for example, interior materials and exterior materials of transportation means, electronic product parts such as mobile phones, laptop computers, computers, and TVs, and interior materials for construction. It can also be applied to required automotive parts.

Claims (18)

A wet-laid non-woven fabric used in the manufacture of a multi-layered sound-absorbing composite in which wet-laid non-woven fabrics are stacked in 3 to 30 layers,
The wet-laid nonwoven fabric is composed of fiber-reinforced resin-integrated short cut fibers having an average fineness of 1 to 5 denier and an average fiber length of 1.5 mm to 15 mm,
The short-cut fiber is a fiber of a core-sheath structure in which the cross-sectional area ratio of the core and sheath is 58 to 92: 8 to 42, and the core includes polyethylene terephthalate (PET) having an intrinsic viscosity of 0.65 to 0.80, and the sheath ) Is a wet-laid nonwoven fabric comprising polyethylene terephthalate (PET) having an intrinsic viscosity of 0.60 to 0.66.
The wet-laid nonwoven fabric according to claim 1, wherein the core PET has a melting point of 250 ° C to 260 ° C, and the sheath PET has a melting point of 210 ° C to 240 ° C.
The wet-laid nonwoven fabric according to claim 1, wherein the short cut fiber has a strength of 3.0 to 5.4 g/d and an elongation of 25% to 55%.
delete According to claim 1, wherein the PET of the sheath is a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 86 to 90: 10 to 14; and diol; a wet-laid nonwoven fabric comprising a polymer polymerized with 1:0.95 to 1 molar ratio.
The wet-laid non-woven fabric according to claim 1, wherein the wet-laid non-woven fabric has an average surface density of 30 to 150 g/m ² .
delete delete Claims 1 to 3, 5 and 6, wherein any one of wet-laid nonwoven fabrics selected from 3 to 30 layers has a multi-layered structure and an average surface density of 1,000 to 1.500 g / m ² It is a sound-absorbing composite,
When the average surface density of the sound-absorbing composite is 1,200 g / m ² , the tensile strength is 160 to 350 Mpa,
When the sound absorption coefficient is measured in accordance with the alpha cabin method of ISO R 354, the sound absorption coefficient is 0.52 or more at 1,000 Hz and the sound absorption coefficient is 0.61 or more at 2,000 Hz.
The method of claim 9, when the average surface density of the sound-absorbing composite is 1,200 g / m ² , when the sound absorption coefficient is measured in accordance with the alpha cabin method of ISO R 354, the sound absorption coefficient is 0.74 or more at 3,150 Hz, and 5,000 A sound-absorbing composite, characterized in that the sound absorption coefficient at Hz is 0.88 or more.
The method of claim 9, when the average surface density of the sound-absorbing composite is 1,200 g / m ² , when measuring the transmission loss, the transmission loss is 23 to 24 dB at 1,000 Hz, and the transmission loss is 24 to 26 dB at 2,000 Hz, 3,150 A sound-absorbing composite characterized by a transmission loss of 34 to 37 dB at Hz and a transmission loss of 42 to 45 dB at 5,000 Hz.
A first step of preparing core-sheath polyethylene terephthalate (PET) short fibers;
A second step of producing a sub-tow by stretching and heat-treating the PET short fibers;
A third step of cutting the sub-tow into 1.5 mm to 15 mm to produce fiber-reinforced resin-integrated short-cut fibers;
A fourth step of adding an acrylic binder to the dispersion in which the short cut fibers are dispersed in water, stirring and mixing the same to form a web in a paper machine, and then drying to prepare a wet nonwoven fabric; and
Step 5 of integrating the wet-laid non-woven fabric and compressing it through a hot press process after stacking the wet-laid non-woven fabric in 3 to 30 layers;
Method for producing a sound-absorbing composite comprising a.
The method of claim 12, wherein the dispersion contains 0.02 to 0.2% by weight of short cut fibers and the balance of water,
The method for producing a sound-absorbing composite, characterized in that the acrylic binder is added to the dispersion in an amount of 5 to 10 parts by weight based on 100 parts by weight of the short cut fibers.
The method of claim 12, wherein the hot press process is performed at 210°C to 280°C and under a pressure of 80 to 120 ton/cm ² .
The method of claim 12, wherein the stretching in the second step stretches the PET short fibers 2.5 to 4 times,
The heat treatment is a method for producing a sound-absorbing composite, characterized in that carried out under 140 ℃ ~ 170 ℃.
The method of claim 12, wherein the first step is to manufacture a core-sheath PET short fiber by composite spinning so that the high molecular weight PET resin becomes the core part and the low melting point PET resin becomes the sheath part,
The composite spinning is performed under conditions of a spinning temperature of 280 ° C to 300 ° C and a winding speed of 500 to 1,200 m / min to produce a PET short fiber having a cross-sectional area ratio of 58 to 92: 8 to 42 of the core and sheath Method for producing a sound-absorbing composite.
The method of claim 16, wherein the low-melting PET resin is a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 86 to 90:10 to 14; and a diol; a PET polymer polymerized in a molar ratio of 1:0.95 to 1;
The high molecular weight PET resin is polymerized with terephthalic acid and diol in a molar ratio of 1:0.95 to 1, and then solid-phase polymerized at 190 ° C to 220 ° C under a nitrogen atmosphere Manufacturing a sound-absorbing composite, characterized in that it comprises a PET polymer method.
The method of claim 16, wherein the high molecular weight PET resin has a melting point of 250 ° C. to 260 ° C. and an intrinsic viscosity of 0.65 to 0.80, and the low melting point PET resin has a melting point of 210 ° C. to 240 ° C. and an intrinsic viscosity of 0.60 to 0.66. Method for producing a sound-absorbing composite, characterized in that having.

Images