TWI773835B - Chopped fibers for compression moldings, compression moldings using the same, and methods for producing the same - Google Patents

Abstract

The present invention relates to a chopped fiber for compression moldings and a method for producing the same, and more particularly, to fibers and/or powders and the like composed of components different from those of the chopped fibers of the present invention. Fiber aggregates and/or compression moldings that are excellent in adhesive strength and compatibility, and have good sound absorption, sound dispersibility, moisture absorption, and water dispersibility.

Description

Chopped fibers for compression moldings, compression moldings using the same, and the same Preparation

The present invention relates to chopped fibers that can provide applied products excellent in mechanical properties and good in sound and moisture absorption, a method for producing the above-mentioned chopped fibers in high yield, a compression molded product prepared using the above-mentioned chopped fibers, and a method of the above-mentioned compression molded product. Preparation.

In general, application products of fiber aggregates such as nonwovens have been used for various purposes, such as hygiene, medical, agricultural or industrial purposes, etc. In particular, in the case of nonwovens used for industrial purposes, tensile strength is very Important factor. In order to meet these requirements and obtain products with high tensile strength, methods of increasing the weight per unit area for production are generally used. However, in the case of increasing the weight for production as described above, since the thickness of the product also increases at the same time, there is a problem that it is difficult to apply to a product requiring both small thickness and toughness.

Therefore, by mixing and blending inorganic fibers such as glass fibers, carbon fibers, etc. with other fibers, the insufficient mechanical properties of the application products using fiber aggregates are compensated, so as to have mechanical properties similar to or higher than those of plastic products. Fiber reinforced composite materials such as CFRP, GFRP, etc. are manufactured and sold. However, in the case of such a fiber-reinforced composite material, there is a problem that glass fibers, carbon fibers, and the like are detached from the product and scattered during the processing process to contaminate the working environment. Also, it has been reported that inorganic fibers such as glass fibers cause lung cancer, and thus recently, demands for developing products having physical properties equivalent to or higher than those using glass fibers without using glass fibers are increasing.

Also, in order to prevent the detachment of inorganic fibers, fiber-reinforced composite materials are used to form a cover layer on the processed product. At present, active efforts have been made to prevent inorganic fibers from In addition to the simple cladding effect of dimensional detachment, cladding materials with various properties and functionalities are also studied.

Also, the types of noise sources such as vacuum cleaners, dishwashers, washing machines, air conditioners, air purifiers, computers, projectors, etc. have become more diverse, and as a result, the problem of noise pollution has become increasingly serious. Therefore, efforts to prevent or reduce the noise generated by the above-mentioned various noise sources in modern life continue, and in developed countries, laws and regulations for regulating the level of inter-floor noise and inter-dwelling noise in common dwellings such as condominiums are becoming more and more strict.

And, recently, improvement of NVH (Noise, Vibration, Harshness) performance of transport aircraft such as automobiles and trains has become a demand of the times due to improvement in the emotional quality of consumers, and the demand for NVH-related parts is rapidly increasing. Typical noises introduced into various transport cabins are the engine noise generated by the engine and transmitted through the body or the air and the friction noise between the wheels and the ground. In order to suppress such noises, engine covers and insulating covers are used. Recently, due to the need for The application of sound-absorbing and sound-insulating materials is expanding for large-area parts, etc.

As the sound-absorbing and sound-insulating materials conventionally used in the past, mainly used felt (felt), sponge, urethane foam, etc., in addition to the thermoplastic resin or thermosetting resin impregnated into compressed fiber, glass fiber, rock wool or Sound-absorbing material obtained from recycled fibers. However, most of the above-mentioned sound absorbing materials have insufficient sound insulating properties, and most of the sound absorbing materials contain components that are harmful to the human body. Also, at present, felt-type fiber materials used for various transportation internal and external materials are manufactured in a state of being physically intertwined with binder fibers by using a dry-laid nonwoven fabric manufacturing process, the problem of such dry-laid nonwoven fabrics However, the shape of the product is determined by the molding process, and the manufacturing process is complicated, resulting in poor economic efficiency.

In recent years, regulations in various countries regarding environmental friendliness and recyclability have been gradually strengthened, and thus the use ratio of thermoplastic resin-based fibrous absorbent materials tends to increase. And, in order to reduce carbon dioxide, regulations on vehicle fuel efficiency are becoming more and more stringent. Since improvements in fuel efficiency can be achieved by reducing the weight of components, there is a need to develop lightweight sound absorbing materials with improved properties.

Therefore, research and development of sound absorbing materials that are harmless to the human body, reduce thickness, effectively absorb and reduce noise, and have an excellent sound absorbing function have been actively conducted.

As a sound-absorbing material that has been researched and developed in the past, a sound-absorbing material is disclosed. The sound-absorbing material contains 10% by weight or more of ordinary short fibers with a diameter of 10 μm or more in general meltblown fibers, and has a net shape. (US Published Patent No. 1954-433600). In addition, a double-layer sound absorbing material for automobiles has been invented. The sound absorbing material is composed of a first sound absorbing layer and a second sound absorbing layer with different area densities, but there are problems of insufficient weight reduction and poor formability. .

Also, a sound-absorbing material has been disclosed as a three-dimensional nonwoven web made by melt-blown microfibers, but due to its large porosity, the three-dimensional nonwoven web is not dense in its organizational structure, so durability is insufficient, and further, Due to the characteristics of the three-dimensional nonwoven fibrous web, in order to provide a sufficient sound absorption effect, not only the thickness of the above-mentioned three-dimensional nonwoven fibrous web needs to be significantly increased, but also the manufacturing of the three-dimensionally constituted nonwoven fibrous web as described above is complicated, resulting in manufacturing costs A significant increase. In addition to this, a sound-absorbing material has been disclosed, which is formed by including staple fibers that can be welded by heating in melt-blown fibers to impart dimensional stability, but this sound-absorbing material still has sound insulation properties. insufficient problem. In addition, a sound-absorbing material using a honeycomb structure having a plurality of spaces and melt-blown fibers at the same time has been disclosed, but the sound-absorbing material has insufficient sound insulation performance and its use is greatly limited due to the lack of flexibility .

(Prior Art Literature)

(patent literature)

(Patent Document 1) Korean Granted Patent No. 10-0899613 (Grant Date: 2009.5.20)

(Patent Document 2) Korean Granted Patent No. 10-1304879 (Grant Date: 2013.09.02)

The present invention has been developed to solve the above-mentioned problems, and an object of the present invention is to provide chopped fibers that can provide application products having excellent mechanical properties and good sound absorption, sound dispersibility, moisture absorption, and water dispersibility, and A method for producing the above-mentioned chopped fiber with high commerciality is provided.

Furthermore, even if glass fibers are not used, the fiber aggregate composed of the above-mentioned chopped fibers having a fiber length of three denier and a short fiber length can be processed into a compression molded product having excellent elasticity due to a sufficient bonding force. , which can replace existing products using glass fibers and other inorganic fibers.

In order to achieve the above object, the chopped fiber for compression molding of the present invention is characterized by comprising a polymer obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:1 to 1.25.

In a preferred embodiment of the present invention, the intrinsic viscosity of the polyethylene terephthalate resin used for the chopped fibers of the compression molding of the present invention may be 0.64-0.80 dl/g and the melting point may be 250-250 dl/g. 260°C.

In a preferred embodiment of the present invention, the average fineness of the chopped fibers for the compression molding of the present invention may be 0.5~5de and the average fiber length may be 1~20mm.

In a preferred embodiment of the present invention, the tenacity of the chopped fibers for the compression molding of the present invention may be 3.5-7.0 g/d and the elongation may be 20-50%.

In a preferred embodiment of the present invention, the surface of the chopped fibers for compression moldings of the present invention may be modified with a hydrophilic modifier or a hydrophobic modifier.

In a preferred embodiment of the present invention, all or part of the surface of the chopped fibers for compression moldings of the present invention may include a hydrophilic coating or a hydrophobic coating.

In a preferred embodiment of the present invention, the dry heat shrinkage rate of the chopped fibers for the compression molding of the present invention may be 2-6%.

Another object of the present invention is to relate to the above-mentioned preparation method of chopped fibers for compression moldings, the above-mentioned method may include: step 1, the polyethylene terephthalate resin made of polyethylene terephthalate The ethylene dicarboxylate core is melted and spun, and then cooled to prepare an undrawn tow; and step 2, the above-mentioned undrawn tow is stretched and heat-treated to length under hot water and steam conditions, Then cut.

In a preferred embodiment of the present invention, the above-mentioned polyterephthalene in step 1 The ethylene formate resin may include a polymer obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:1 to 1.25.

In a preferred embodiment of the present invention, the melting in the above step 1 can be performed at 270-300°C.

In a preferred embodiment of the present invention, the spinning in the above step 1 may be performed under the conditions of a spinning temperature of 275-295° C. and a winding speed of 700-1,300 m/min.

In a preferred embodiment of the present invention, the stretching in step 2 may be performed by stretching the unstretched sub-filament bundle to 2 to 4 times at a temperature of 70 to 90°C.

In a preferred embodiment of the present invention, the above-mentioned fixed-length heat treatment can be performed at 160-220°C.

In a preferred embodiment of the present invention, the above-mentioned heat treatment to length can be performed by using a hot drum or a heating roller.

In a preferred embodiment of the present invention, in the cutting in step 2, the heat-fixed sub-filament bundles may be cut, so that the sub-filament bundles become chopped fibers with an average fiber length of 1-20 mm.

Still another object of the present invention is to provide a fiber aggregate composition for use in producing a fiber aggregate using the chopped fibers for compression moldings of the present invention described above.

In a preferred embodiment of the present invention, the fiber aggregate composition of the present invention may include: a dispersion liquid containing the aforementioned chopped fibers, chopped binder fibers and water in various shapes as described above; and a binder resin .

In a preferred embodiment of the present invention, the dispersion may include 0.02-2 wt % of the chopped fibers, 0.001-1 wt % of the chopped binder fibers, and the balance of water.

In a preferred embodiment of the present invention, the chopped staple fiber may be a sheath-core adhesive fiber in which a plurality of the chopped fibers are partially bonded.

In a preferred embodiment of the present invention, the average fineness of the chopped binder fibers can be 1-12de and the average fiber length can be 3-30mm.

In a preferred embodiment of the present invention, the sheath part of the sheath-core binder fiber may include polypropylene resin with a melting point of 155-185° C., and the core part may include an intrinsic viscosity of 0.65-0.80 dl/g and a melting point of 250-260 °C polyethylene terephthalate resin.

In a preferred embodiment of the present invention, the content of the binder resin may be 5 to 20 parts by weight relative to 100 parts by weight of the total amount of chopped fibers and chopped binder fibers.

In a preferred embodiment of the present invention, the above-mentioned adhesive resin may include an acrylic adhesive resin.

Still another object of the present invention is to provide a compression molded product comprising a compressed product obtained by compressing a single-layer or multi-layer stack of wet-laid nonwoven fabrics, wherein the wet-laid non-woven fabric is subjected to compression. Web nonwoven fabrics are prepared by drying a fabric that will be obtained in a paper machine with the fiber aggregate composition described above.

In a preferred embodiment of the present invention, the above-mentioned stacked body may further include a wet-laid nonwoven fabric comprising fibers of a different kind from the fibers constituting the above-mentioned wet-laid nonwoven fabric.

In a preferred embodiment of the present invention, when the thickness of the compression-molded product of the present invention is 2 mm, the average areal density of the compression-molded product can be 1,050-1,420 g/m ² .

In a preferred embodiment of the present invention, when the thickness of the compression molding of the present invention is 2 mm and the average areal density is 1,150-1,250 g/m ² , the tensile strength of the compression molding may be 19-25 Mpa.

In a preferred embodiment of the present invention, when the thickness of the compression molding of the present invention is 2mm and the average areal density is 1,150~1,250g/ ^m2 , if the sound absorption coefficient is measured based on the alpha cabin method of ISO R 354, then The sound absorption coefficient at 1,000 Hz may be 0.52~0.68, and the sound absorption coefficient at 2,000 Hz may be 0.55~0.75.

In a preferred embodiment of the present invention, when the thickness of the compression molding of the present invention is 2mm and the average areal density is 1,150~1,250g/ ^m2 , if the sound absorption coefficient is measured based on the alpha cabin method of ISO R 354, then The sound absorption coefficient at 3,150 Hz may be 0.65~0.85, and the sound absorption coefficient at 5,000 Hz may be 0.80~0.95.

In a preferred embodiment of the present invention, when the thickness of the compression molding of the present invention is 2 mm and the average areal density is 1,150-1,250 g/m ² , the penetration loss at 1,000 Hz can be 23.5-25.5 dB, The penetration loss at 2,000Hz may be 24.5~27.8dB, the penetration loss at 3,150Hz may be 32.0~40.0dB, and the penetration loss at 5,000Hz may be 40.0~50.0dB.

Another object of the present invention is to relate to the preparation method of the above-mentioned compression molding, and the above-mentioned method comprises: step 1, mixing the chopped fibers, chopped staple fibers and water of the present invention as described above to prepare a dispersion liquid; step 2 , mixing the above-mentioned dispersion liquid and the binder resin to prepare a mixed liquid; Step 3, using the above-mentioned mixed liquid in a paper machine to prepare a fabric; Step 4, drying the above-mentioned fabric to prepare a wet-laid nonwoven fabric; Step 5 step 6, cold-compressing the heat-treated stack; and step 7, drying the cold-compression.

In a preferred embodiment of the present invention, the drying in the above step 4 can be performed at 160-190°C.

In a preferred embodiment of the present invention, the heat treatment in the above step 6 may be performed at 180-220° C. for 1-2 minutes.

Still another object of the present invention is an application product of the above-mentioned compression-molded product, that is, a fiber-reinforced composite material, a sound-absorbing and insulating material, a sanitary material and/or a heat-insulating material using the above-described compression-molded product.

In a preferred embodiment of the present invention, the above-mentioned fiber-reinforced composite material and/or sound-absorbing and insulating material can be applied to the interior and exterior materials of transport aircraft, such as electrical and electronic equipment such as refrigerators and air conditioners.

The chopped fiber of the present invention is controlled to have a low shrinkage rate, so that the rate of dimensional change is small during the molding process of the fiber aggregate, and can thereby exhibit stable process passability and high commerciality. Also, fibers composed of components different from the chopped fiber components of the present invention and/or powders composed of different components are excellent in adhesion and compatibility, good in processability, and suitable for application in Application products of fiber aggregates and compression moldings having sound absorbency, sound dispersibility, moisture absorbability, water dispersibility, and the like are required.

FIG. 1 is a photograph of chopped fibers prepared in Example 1. FIG.

FIG. 2 is an optical microscope measurement photograph of the cross section of the chopped fiber prepared in Example 1. FIG.

Next, the conjugated fiber of the present invention will be described in more detail.

The chopped fibers used in the compression molding of the present invention (hereinafter referred to as chopped fibers) include polyethylene terephthalate resin, and the intrinsic viscosity of the polyethylene terephthalate resin is 0.65 to 0.80 dl/g and the melting point is 250~260°C, preferably, the intrinsic viscosity is 0.65~0.75 dl/g and the melting point is 252~256°C. At this time, if the intrinsic viscosity is less than 0.65 dl/g, there may be problems that spinning workability is poor and physical properties are lowered. The temperature is controlled high, so there is a problem that the manufacturing cost increases.

Furthermore, the polyethylene terephthalate resin may be a polymer obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:1 to 1.25.

Moreover, the chopped fibers of the present invention may have an average fineness of 0.5~5de and an average fiber length of 1~20mm, preferably, the average fineness may be 1~3de and the average fiber length may be 5~15mm. In this case, if the average fineness of the chopped fibers is less than 1de, there may be a problem that the yield and the physical properties of the fiber aggregates decrease, and if the average fineness is more than 5de, the number of chopped fibers constituting the fiber aggregates per unit weight decreases. , and the bonding factor between fibers is reduced, so there may be problems of reduced physical properties and poor appearance. In addition, if the average fiber length of the chopped fibers is less than 5 mm, there may be a problem that the adhesion between fibers is reduced, and if the average fiber length is more than 20 mm, the dispersibility is reduced, resulting in deterioration of the appearance and physical properties of the fiber aggregates. As a result, The physical properties of the final molded product are also degraded.

Also, the chopped fibers of the present invention can be modified by a hydrophilic modifier or a hydrophobic modifier. Functionality can be imparted by changing the name of the surface of the fiber by a functional agent, or by forming a hydrophilic coating or a hydrophobic coating on all or part of the surface of the fiber to impart functionality. More specifically, by imparting functionality as described above, adhesion and compatibility with fibers composed of other components and/or powder composed of other components can be further improved.

The tenacity of the chopped fiber of the present invention as described above may be 3.5-7.0 g/d and the elongation may be 20-50%, preferably, the tenacity may be 4.0-6.0 g/d and the elongation may be 25 ~40%.

In addition, the dry heat shrinkage of the chopped fibers of the present invention may be 2 to 6%, preferably 2 to 5%.

The chopped fiber of the present invention as described above can be prepared by performing a process comprising the following steps: Step 1, a polyethylene terephthalate chip made of a polyethylene terephthalate resin is melted and spinning, and then preparing an undrawn tow by cooling; and in step 2, the above-mentioned undrawn tow is drawn and heat-treated to length under hot water and steam conditions, and then cut.

The characteristics and kinds of the above-mentioned polyethylene terephthalate resin in Step 1 are the same as those described above.

The melting in step 1 may be performed at 270-300°C, preferably, may be performed at 285-295°C.

Spinning in step 1 can be carried out at a spinning temperature of 275-295°C and a winding speed of 700-1,300 m/min, preferably, at a spinning temperature of 280-290°C and a winding speed of Under the condition of 800~1,200m/min. At this time, if the spinning temperature is lower than 275°C, the internal pressure of the pack may increase and the spinning workability may decrease. If the spinning temperature is higher than 295°C, the polyethylene terephthalate resin will Intrinsic viscosity decreases, resulting in reduced physical properties of chopped fibers. In addition, if the winding speed is less than 700 m/min, there may be a problem that the physical properties of the chopped fibers and/or the application products using the chopped fibers are decreased due to the decrease in the stability of the undrawn split tow and the increase in the elongation. , if the winding speed is more than 1,300 m/min, there may be a problem that the drawing workability is lowered due to the uneven stacking of the undrawn sub-tows on the can.

The stretching in step 2 can be performed by a conventional stretching method in the art, preferably, the unstretched sub-filament bundle can be stretched at a temperature of 70-100° C. The stretched tow is stretched to 2.5 to 4 times at a temperature of 70 to 90° C., preferably, to 2.8 to 3.8 times. At this time, if the draw ratio is less than 2.5 times, the physical properties of the application product using the conjugated fiber will decrease due to the increase in elongation. If the draw ratio is more than 4 times, the problem of thread breakage may occur. stretch within the range.

The heat treatment to length in step 2 is a process for improving the stability of the split tow before crimping, which can be performed by using a plurality of heated drums or heated rolls. For a specific example, heat treatment can be performed by contacting the sub-filament bundles on the surface of the hot drum for about 5 to 30 seconds, so as to increase the crystallinity of the sub-filament bundles, thereby increasing the shrinkage rate and elastic modulus.

Moreover, the cutting is performed according to the processed product using the cut fiber of the present invention by a conventional cutting method in the art so that the fiber has a suitable fiber length, and the average fiber length of the fiber can be cut in the range of 1~20mm. Preferably, the cutting may be performed so that the average fiber length of the fibers is in the range of 2 to 15 mm.

By the above production method, as described above, the chopped fibers of the present invention having an average fineness of 0.5 to 5 de and an average fiber length of 1 to 20 mm can be produced.

Also, the surface of the chopped fibers of the present invention prepared by the above method can be changed with a hydrophilic modifier or a hydrophobic modifier, or a hydrophilic coating or a hydrophobic coating can be formed on all or part of the surface of the fiber.

Fiber aggregates such as nonwoven fabrics and the like can be prepared by using the conjugate fibers of the present invention as described above. At this time, the above-mentioned non-woven fabric may be a wet-laid non-woven fabric or an air-laid non-woven fabric, preferably, it may be a wet-laid non-woven fabric. The above-mentioned composition for preparing a fiber aggregate includes: a dispersion liquid comprising chopped fibers, chopped binder fibers and water; and a binder resin.

Among them, the above-mentioned chopped fibers are as described above.

Moreover, the chopped strand binder fiber may be a sheath-core binder fiber in which a plurality of the above-mentioned chopped strand fibers are partially bonded.

Moreover, the sheath part of the above-mentioned chopped binder fibers may include polypropylene resin with a melting point of 155-185 °C, preferably, may include polypropylene resin with a melting point of 160-175 °C, more Preferably, a polypropylene resin with a melting point of 160-170° C. may be included. At this time, if the melting point of the sheath portion is higher than 185° C., when the chopped binder fiber is used to prepare a nonwoven fabric as a fiber aggregate, the sheath portion is not dissolved in the drying process, resulting in contact with the chopped fibers. Adhesion is reduced, the detachment of chopped fibers cannot be prevented, and the mechanical properties of the produced compression molding are reduced. Further, when the melting point of the sheath portion is lower than 155°C, the sheath portion is excessively dissolved in the drying step, and on the contrary, the mechanical properties and/or the sound-absorbing and sound-absorbing properties of the compression-molded article are lowered.

Also, the core portion of the chopped binder fiber includes a polyethylene terephthalate resin having an intrinsic viscosity of 0.65 to 0.80 dl/g and a melting point of 250 to 260° C., preferably, using a resin having the same The physical properties and composition of the cut fiber polyethylene terephthalate resin are the same as the physical properties and composition of the polyethylene terephthalate resin.

It is preferable to use chopped binder fibers having an average fineness of 1 to 12 de and an average fiber length of 3 to 30 mm in terms of maintaining an appropriate binder function for the chopped fibers and improving the tensile strength and sound absorption and sound insulation properties of the compression molded product. , preferably, use chopped bond fibers with an average fineness of 1~6de and an average fiber length of 3~25mm, more preferably, use chopped bond fibers with an average fineness of 1~4de and an average fiber length of 3~18mm fiber.

The dispersion liquid as the fiber aggregate composition may include 0.02 to 2 wt % of the above chopped fibers, 0.001 to 1 wt % of the above chopped binder fibers, and the balance of water, and preferably, may include 0.02 to 1.5 wt % of the chopped fibers, 0.01 to 0.8% by weight of the chopped binder fibers, and the balance of water. At this time, if the content of chopped fibers is less than 0.02% by weight, the fabric cannot be smoothly formed by the paper machine because the content is too small. Wet-laid nonwovens exhibit increased chopped fibers and reduced processability. Moreover, if the content of the chopped binder fibers is less than 0.001% by weight, the binding force between the chopped fibers is reduced due to the use of too small amount of the chopped binder fibers, resulting in a decrease in the mechanical properties of the compression molding. If the content of the binder fiber exceeds 1% by weight, the sound absorption and sound insulation properties are lowered, so it is preferably used within the above content range.

Also, in the components of the composition, the content of the above-mentioned binder resin may be 5 to 20 parts by weight relative to 100 parts by weight of the total of chopped fibers and chopped binder fibers in the dispersion liquid, preferably , can be 5 to 15 parts by weight, more preferably, can be 5 to 10 parts by weight. At this time, if the amount of the binder resin used is less than 5 parts by weight, it may be difficult to ensure sufficient compression molding. As for the tensile strength, when the amount of the binder resin used exceeds 20 parts by weight, even if the tensile strength is high, there is a possibility that the flexibility of the compression-molded product is deteriorated, and the sound-absorbing and sound-absorbing properties may be reduced.

Also, the binder resin may be a conventional binder resin in the art, preferably, may be an acrylic binder resin.

Next, the production method of the compression molded article of the present invention will be described.

The compression-formed product of the present invention may include a compressed product obtained by compressing a single-layer or multi-layer stack of wet-laid nonwoven fabrics that will be processed in a paper machine by The fabric obtained by using the above-mentioned fiber aggregate composition is prepared by drying. The above-mentioned stack may further include a wet-laid nonwoven fabric comprising fibers of a different kind from the fibers constituting the above-mentioned wet-laid nonwoven fabric.

The compression molding of the present invention as described above can be prepared by carrying out a process comprising the following steps: step 1, mixing chopped fibers, chopped binder fibers and water to prepare a dispersion; step 2, mixing the above dispersion and The binder resin is mixed to prepare a mixed solution; step 3, the above-mentioned mixed solution is used in a paper machine to prepare a fabric; step 4, the above-mentioned fabric is dried to prepare a wet-laid nonwoven fabric; The laid nonwoven fabrics are stacked into a multi-layer stack, and then heat-treated; and step 6, cold-compressing the heat-treated stack.

The composition, composition ratio and characteristics of the composition of the above-mentioned dispersion liquid in Step 1 and the composition, composition ratio and characteristics of the dispersion liquid and the binder resin used for the mixed liquid in Step 2 are as described above.

The paper machine in step 3 can be used using conventional methods in the art.

The drying in step 4 is performed for the fabric of step 3 at 160~190°C, preferably at a temperature higher than the melting point of the polypropylene resin used for the sheath portion of the chopped binder resin.

Moreover, in step 5, the wet-laid nonwoven fabric prepared as described above is stacked or intervened in 2 or more layers, preferably, 5 to 20 layers, more preferably, about 5 to 15 layers to prepare a stack, and then The heat treatment is performed at 180-220° C. for 1-2 minutes, preferably, the heat-treatment is performed at 190-210° C. for 1-2 minutes.

Also, in step 6, the stack of step 5 may be cold-compressed by a conventional method in the art to prepare a compression molding.

When the thickness of the compression molding of the present invention prepared as described above is 2 mm, the average areal density may be 1,050 to 1,420 g/m ² , preferably 1,100 to 1,350 g/m ² , and more preferably, may be 1,120~1,300g/m ² .

And, when the thickness of the compression molded product of the present invention is 2 mm and the average areal density is 1,150 to 1,250 g/m ² , when measured based on ASMT D638, under the condition that the relative humidity is 50% and the temperature is 23° C., the The tensile strength may be 19~25Mpa, preferably, the tensile strength may be 19.5~24Mpa, more preferably, 20~23.5Mpa.

Also, when the thickness of the compression molded product of the present invention is 2 mm and the average areal density is 1,150 to 1,250 g/m ² , when measured based on ASMT D790, under a relative humidity of 50% and a temperature of 23° C., bending The strength can be 7.5~12Mpa and the flexural modulus can be 450~600Mpa, preferably, the flexural strength can be 8~11Mpa and the flexural modulus can be 470~580Mpa, more preferably, the flexural strength can be 8.5~10.5Mpa and the bending The elastic modulus can be 490~560Mpa.

Furthermore, when the thickness of the compression molded product of the present invention is 2 mm and the average areal density is 1,150 to 1,250 g/m ² , if the sound absorption coefficient is measured based on the alpha cabin method of ISO R 354, the sound absorption coefficient at 1,000 Hz is It may be 0.52~0.68, preferably, it may be 0.54~0.67, and more preferably, it may be 0.55~0.65. And, the sound absorption coefficient at 2,000 Hz may be 0.55~0.75, preferably, 0.56~0.74, and more preferably, 0.59~0.74. And, the sound absorption coefficient at 3,150 Hz may be 0.65~0.85, preferably, 0.68~0.80, and more preferably, 0.70~0.80. And, the sound absorption coefficient at 5,000 Hz may be 0.80~0.95, preferably, 0.82~0.94, and more preferably, 0.85~0.93.

Also, when the thickness of the compression molded product of the present invention is 2 mm and the average areal density is 1,150 to 1,250 g/m ² , the penetration loss at 1,000 Hz may be 23.5 to 25.5 dB, preferably, 23.8 to 25.2 dB, more preferably, may be 24.0~24.8dB. And, the penetration loss at 2,000 Hz may be 24.5~27.8dB, preferably, 25.0~27.5dB, and more preferably, 25.0~27.0. And, the penetration loss at 3,150 Hz may be 32.0-40.0 dB, preferably, 34.0-39.0 dB, and more preferably, 34.5-38.0 dB. The penetration loss at 5,000 Hz may be 40.0-50.0 dB, preferably, 43.0-49.0 dB, and more preferably, 45.0-48.5 dB.

The compression molded product of the present invention as described above can be applied to a cover layer of a processed product using a fiber-reinforced composite material containing inorganic fibers.

Furthermore, fiber aggregates and/or compression moldings using the chopped fibers of the present invention have excellent mechanical properties and sound absorption, sound dispersibility, moisture absorption, and water dispersibility, and thus can be applied to the interior and exterior of buildings Materials, civil engineering materials, interior and exterior materials of transport units such as aircraft and ships, hygiene materials such as diapers, sanitary napkins and masks, filters such as air filters and liquid filters, etc.

Hereinafter, the present invention will be described in more detail with reference to examples, however, the following examples should not be construed to limit the scope of the present invention and should be construed to facilitate understanding of the present invention.

[Example]

Example 1-1: Preparation of Chopped Fibers for Compression Molding

Prepare a polyethylene terephthalate chip made of a polyethylene terephthalate resin including terephthalic acid and glycol as a diol in a molar ratio of 1:1.2, the above polyethylene terephthalate The intrinsic viscosity of the ethylene dicarboxylate chip was 0.65 dl/g and the melting point was 255°C.

Next, the above-mentioned polyethylene terephthalate chips were put into a spinning nozzle and melted at 290°C, and then spinning was performed at a spinning temperature of 285°C and a winding speed of 1,000 m/min, After the winding process, it is loaded into a can.

After aging the undrawn split tow loaded in the can for 8 hours or more, stabilization was performed to prepare the can number in such a way that the overall fineness was 2 million denier.

Next, the above-mentioned undrawn split tow was stretched 3.15 times in hot water at 80°C, and heat treatment was performed at 180°C for 20 seconds using a hot drum. In the process of fixed-length heat treatment, the tension of the hot drum was adjusted to 0.97 times in the first and third regions of a total of 4 regions, and the tension of the hot drum was adjusted to 1.0 times in the remaining regions, and finally the poly ethylene terephthalate chopped Fiber shrinkage.

Next, cutting was performed to prepare chopped fibers for compression moldings having an average fineness of 1.5 denier (de) and an average fiber length of 12 mm, at which time the tenacity was 5.1 g/d and the elongation was 35%. Also, the dry heat shrinkage rate was 2.8%. The prepared chopped fibers are shown in FIG. 1 , and a cross-sectional scanning electron microscope (SEM) measurement photograph of the chopped fibers is shown in FIG. 2 .

Examples 1-2 to 1-6 and Comparative Examples 1-1 to 1-6

Except for changing the kind of polyethylene terephthalate chips or the fineness and fiber length of the chopped fibers as shown in Table 1 below, each chopped fiber was prepared in the same manner as in the above-mentioned Example 1-1 to perform Examples 1-2 to 1-6 and Comparative Examples 1-1 to 1-6.

In Table 1 below, as for the tenacity and elongation, based on the method described in JIS L1013:2010, under the conditions of a sample length of 100 mm and a tensile speed of 50 mm/min, a universal puller manufactured by Instron Co., Ltd. was used. Tensile test equipment was used to make 10 measurements for each grade, and tenacity (g/denier) and elongation (%) were measured by the average value.

Referring to the experimental results in Table 1 above, in the case of Examples 1-1~1-6, the toughness is 5.5~6.1g/d, the elongation is 38~46%, and the dry heat shrinkage rate is 4.9~5.1%, From this, it can be seen that it has suitable physical properties. On the contrary, in the case of Comparative Example 1-1 with an average fineness of more than 5.0 de, there was a problem that the elongation was more than 50%, and in the short-cut fibers of Comparative Example 1-2 with an average fineness of less than 0.5 de In the case of the chopped fibers of Comparative Examples 1-5 made of low polyethylene terephthalate chips, there was a problem that the dry heat shrinkage ratio was more than 6%.

In the case of Comparative Preparation Example 1-2 having an average fineness of more than 0.5de and Comparative Example 1-6 made of polyethylene terephthalate chips having an intrinsic viscosity of more than 0.80 dl/g, when the chopped fibers were prepared , the spinning cannot be carried out smoothly.

Example 2-1: Preparation of chopped binder fibers

A polyethylene terephthalate resin having an intrinsic viscosity of 0.65 dl/g and a melting point of 255° C. was prepared as in the above-mentioned fiber material.

Then, a polypropylene chip was prepared, in which a polypropylene resin having an enthalpy of 94 J/g and a melting point of 165° C. required for dissolving crystals in a differential thermal analysis (DSC) analysis was prepared as a chip.

Next, the above-mentioned polyethylene terephthalate chips were melted at 290° C., and the polypropylene chips were melted at 260° C., and then the above-mentioned two chips were put into a composite spinning nozzle for spinning, and cooled to make Sheath-core undrawn tow.

At this time, after composite spinning was performed under the conditions of a spinning temperature of 275° C. and a winding speed of 950 m/min, it was loaded into a tank through a winding process.

Next, after stretching the above-mentioned undrawn split tow by 3.2 times at 85°C, a heat treatment to length was performed at 170°C for 20 seconds using a hot drum.

Next, cutting was performed to prepare a sheath-core type chopped binder fiber for an adhesive having an average fineness of 2 denier and an average fiber length of 12 mm, and at this time, the tenacity was 4.3 g/d and the elongation was 50%. Also, the cross-sectional area ratio of the sheath to the core is 1:1, wherein the sheath is made of polypropylene resin, The core is composed of polyethylene terephthalate resin.

Examples 2-2 to 2-3 and Comparative Examples 2-1 to 2-4

Each chopped binder fiber was prepared in the same manner as in Example 2-1 above, except that the core component and the sheath component were changed as shown in Table 2 below, to carry out Examples 2-2 to 2-3 and Comparative Example 2-1~2-4.

Preparation Example 1: Preparation of Compression Molded Product

Next, the low-shrinkage polyethylene terephthalate chopped fibers of Example 1-1 and the polypropylene/polyethylene terephthalate chopped fibers of Example 2-1 were weighed at 0.04 wt. % concentration in water to prepare dispersions. Next, in the dispersion liquid, 7 parts by weight of an acrylic binder was added with respect to 100 parts by weight of chopped fibers. The above dispersion is then agitated and mixed to form a fabric on a paper machine. Next, the formed fabric was dried at 180° C. to prepare a wet-laid nonwoven fabric having an average areal density of 100 g/m ² .

Next, the above nonwoven fabrics were stacked in 10 sheets, heat-treated at 200° C. for 90 seconds, and cold-compressed to prepare a compression molded product (average thickness: 2 mm) having an average areal density of 1,200 g/m ² .

Preparation Examples 2 to 8 and Comparative Preparation Examples 1 to 8: Preparation of Compression Molded Products

Each compression molded article was prepared in the same manner as in Preparation Example 1 above except that the chopped strands or chopped binder fibers were changed as shown in Table 3 below, to carry out Preparation Examples 2 to 8 and Comparative Preparation Examples 1 to 10, respectively.

Experimental Example: Measurement of Physical Properties of Compression Molded Products

The flexural elastic modulus, flexural strength, tensile strength, sound absorption performance, sound insulation performance and vibration damping performance of the compression molded articles prepared in the above-mentioned preparation examples and comparative preparation examples were measured, The results are shown in Tables 5 and 6 below.

(1) Measurement method of flexural modulus and flexural strength

Flexural modulus and flexural strength were measured according to ASMT D790 at a relative humidity of 50% and a temperature of 23°C.

(2) Tensile Strength (Load at Tensile Strength, MPa)

Compression moldings having a width of 100 mm, a length of 20 mm, and a height of 10 mm were prepared, and then the tensile strength was measured according to ASMT D638 under the conditions of a relative humidity of 50% and a temperature of 23°C.

(3) Measurement of sound absorption coefficient according to frequency

In order to measure the sound absorption coefficient, 3 sheets of compression moldings (1.2m x 1.0m (width x length)) were prepared in the form of samples that could be applied to the Alpha Cabin method of ISO R 354, respectively, at external temperatures of 0°C and 25°C Let stand for 30 minutes, and then measure the sound absorption coefficient. The measuring equipment used Instron R (Instron R).

(4) Measurement of penetration loss (dB) according to frequency

Each sample was prepared by cutting the compression molding into a size of 0.84 m in width and 0.84 m in length, and the penetration loss was measured using an APAMAT-II (Autoneum Corporation) apparatus.

(5) Evaluation of productivity, workability and operability

Yield was evaluated according to the method of evaluating the yield of the final product judged to be good compared with the amount of input raw material, and workability and operability were evaluated according to the method of calculating the frequency of measures due to occurrence of wire breakage per hour. In addition, the evaluation results are shown as ⊚>◯>Δ in a favorable order by the comprehensive evaluation.

Referring to the experimental results in Tables 4 to 6 above, it can be confirmed that the compression molded articles of Preparation Examples 1 to 8 have excellent mechanical properties, sound absorption properties, and sound insulation properties as a whole.

In contrast to this, Comparative Preparation Example 1 using the chopped fibers of Comparative Example 1-1 had a problem in that the tensile strength was lowered compared to Preparation Example 1.

In addition, in the case of Comparative Preparation Example 2 using the chopped fibers of Comparative Examples 1 to 3, the wet-laid nonwoven fabric manufacturing defect rate was too high due to poor dispersibility of the chopped fibers, so that a compression molded product could not be prepared.

In addition, Comparative Preparation Example 3 using the chopped fibers of Comparative Examples 1-4 and Comparative Preparation Example 4 using the chopped fibers of Comparative Examples 1-5 had a problem that the mechanical properties as a whole were inferior to those of the Preparation Examples.

Furthermore, in the case of Comparative Preparation Examples 5 to 6 using the binder fibers of Comparative Examples 2-1 to 2-2, the mechanical properties of the compression molded product were inferior, and Comparative Preparation Examples prepared using the binder fibers of Comparative Example 3 7. There is a problem that the sound absorption performance at high frequencies is low. In addition, in the case of Comparative Preparation Example 7 using the binder fibers of Comparative Example 4, the fibers were too long and the binder fibers were aggregated and the dispersibility was poor, so the defective rate of the wet-laid nonwoven fabric was high.

From the above-mentioned examples and experimental examples, it was confirmed that a compression molded product having excellent mechanical properties and sound and moisture absorption properties can be produced by using the chopped fibers of the present invention. The above-mentioned compression molded product of the present invention as described above can be applied to products such as interior and exterior materials of conveyors such as automobiles, sound absorbing and insulating materials used in electrical and electronic products, water absorbing materials used in sanitary materials, and the like.

Claims (14)

A chopped fiber for compression molding, wherein the chopped fiber is used for preparing a compression molding, characterized in that it includes polyethylene terephthalate resin, and the polyethylene terephthalate resin includes A polymer obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:1 to 1.25, the polyethylene terephthalate resin has an intrinsic viscosity of 0.64 to 0.80 dl/g and a melting point of 250 to 260 ℃, the average fineness of the above chopped fibers is 0.5~5de, the average fiber length is 1~20mm, the tenacity is 3.5~7g/d, the elongation is 20~50% and the dry heat shrinkage rate is 2~6%. The chopped fibers for compression moldings described in claim 1, wherein the surfaces of the chopped fibers are modified with a hydrophilic modifier or a hydrophobic modifier. The chopped fibers for compression moldings according to claim 1, wherein the whole or part of the surfaces of the chopped fibers include a hydrophilic coating or a hydrophobic coating. A method for preparing chopped fibers for compression molding, comprising: step 1, preparing polyethylene terephthalate with an intrinsic viscosity of 0.65-0.80 dl/g and a melting point of 250-260° C. The polyethylene terephthalate core made of resin is melted and spun, and then undrawn tow is prepared by cooling; and step 2, the above-mentioned undrawn tow is carried out under hot water and steam conditions. Drawing and heat treatment to length, and then cutting, the above polyethylene terephthalate resin includes a polymer obtained by polymerizing terephthalic acid and diol in a molar ratio of 1:1 to 1.25, The average fineness of the prepared chopped fibers is 0.5~5de, the average fiber length is 1~20mm, the tenacity is 3.5~7g/d, the elongation is 20~50% and the dry heat shrinkage rate is 2~6%. The method for producing chopped fibers for compression moldings as described in claim 4, wherein the drawing in step 2 is performed by dividing the undrawn into strands at a temperature of 70 to 90° C. Stretch to 2 to 4 times. A fiber aggregate composition, characterized in that it comprises: a dispersion liquid comprising chopped fibers, chopped binder fibers and water as described in any one of items 1 to 3 of the patent application scope; and a binder resin , the content of the above-mentioned binder resin is 5 to 20 parts by weight relative to the total amount of chopped fibers and chopped binder fibers in 100 parts by weight. The fiber aggregate composition according to claim 6, wherein the dispersion contains 0.02 to 2 wt % of the chopped fibers, 0.001 to 1 wt % of the chopped binder fibers, and 100 wt % the remaining water in the dispersion. A compression molded product, characterized in that it includes a compressed product obtained by compressing a single-layer or multi-layer stack of wet-laid non-woven fabrics, the wet-laid non-woven fabrics being used in papermaking by compressing them. It is prepared by drying in the machine the fabric obtained by using the fiber aggregate composition as described in claim 6. A preparation method of compression molding, is characterized in that, comprises: Step 1, mix the chopped fibers, chopped binder fibers and water as described in any one of the claims 1 to 3 of the patent application scope to prepare a dispersion; Step 2, mix the above dispersion and binder resin step 3, use the above mixed solution in a paper machine to prepare fabric; step 4, dry the above fabric to prepare a wet-laid nonwoven fabric; step 5, prepare the above-mentioned wet-laid nonwoven fabric A multi-layered stack is stacked and then heat-treated; step 6, cold compression is performed on the heat-treated stack; and step 7, the cold compression is dried. The method for producing a compression molded product according to claim 9, wherein the drying in the above-mentioned step 4 is performed at 160-190°C, and the heat treatment in the above-mentioned step 6 is performed at 180-220°C 1~2 minutes. The method for producing a compression molded product according to claim 9, characterized in that, when the thickness of the cold compressed product dried in the above step 7 is 2 mm, the average areal density is 1,050 to 1,420 g/m ² . A fiber-reinforced composite material is characterized by comprising the compression molding as described in item 8 of the patent application scope. A car interior and exterior material, characterized in that it comprises as applied The compression-molded article described in Item 8 of the patent scope. A sound absorbing and insulating material is characterized by comprising the compression molding as described in item 8 of the patent application scope.

Images