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  Spunbonded nonwoven fabricsUSPTO Application #: 20080038980Title: Spunbonded nonwoven fabrics Abstract: The present invention pertains to (A) a spunbonded nonwoven fabric consisting of continuous fibers containing aromatic polyester (melting point: Tm1) and aromatic copolyester (a melting point: Tm2=150 degrees centigrade to (Tm1-20 degrees centigrade)) in an amount of 1 to 15% by weight with respect to the aromatic polyester, wherein the elongation rate of the nonwoven fabric is 20% or more and 100% or less, and the load of elongation of 5% is 1.2 N/50 mm or less per g/m2 weight, (B) the spunbonded nonwoven fabric according to the above (A), wherein the aromatic polyester is polybutylene terephthalate, and (C) the spunbonded nonwoven fabric according to the above (A) or (B), wherein the starting temperature of endotherm of an endothermic peak representing the melting point in a temperature raising process of a differential scanning calorimeter is 140 degrees centigrade or higher. The present invention proposes a spunbonded nonwoven fabric which has an excellent low modulus, retains a high elongating property, and has particularly excellent moldability and followability, and also has excellent dimensional stability after molding, and suitable for a backing ground fabric of automobile interior materials. (end of abstract) Agent: Fish & Richardson P.C. - Minneapolis, MN, US Inventors: Shigeki Tanaka, Masataka Adachi, Toshiya Yamamoto USPTO Applicaton #: 20080038980 - Class: 442361 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080038980. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001]The present invention relates to a polyester spunbonded nonwoven fabric having a low modulus and an excellent elongating properties, and for more detail, to a polyester spunbonded nonwoven fabric which has excellent moldabilities and followability as well as excellent dimensional stabilities after molding, and is suitable for a backing ground fabric for automobile interior materials. Furthermore, the present invention relates to a polyester spunbonded nonwoven fabric which is suitable for a backing ground fabric for door trims. BACKGROUND OF THE INVENTION [0002]As a backing ground fabric for automobile interior materials, knits such as hosiery and tricot, textures such as shirting, and nonwoven fabrics such as spunbond, and short-fiber nonwoven fabric are widely used. In such applications of automobile interior materials, not only design of itself but also luxury touch-feeling has been desired in recent years. Therefore, it is strongly required to soften the surface layer of the interior materials. When a surface layer of an interior material is softened, the elongating properties and followability of a backing ground fabric have large effects on the finish of the surface layer, namely the appearance of itself through a cushion layer, and therefore the requirements for the functions of a backing ground fabric have become higher as the surfaces are getting softened. Particularly, since door trim sections among the materials for automobile interior often have large projections and depressions, and their deformations during molding are to be large, it is difficult to keep the high qualities of the interior materials for them. On the other hand, since the door trim section is a portion which is frequently visible to consumers and with which consumers often touch directly, the door trim section requires particularly high technologies and qualities. As a backing ground fabric satisfying such requirements, a polyamide long-fiber nonwoven fabric having a low modulus and high elongating properties, i.e., having good moldability is proposed (See, for example, Patent Document 1). However, such a nonwoven fabric has a relatively low modulus and a high elongating properties, but it has insufficient dimensional stability after molding; and therefore, it is difficult to maintain its form, and there is a problem that sagging (a phenomenon in which the form changes after molding) is produced and this results in some degradation of its quality after molding. [0003]Patent Document 1: Japanese Laid-open Patent Publication No.2003-113569 [0004]Thus, a nonwoven fabric having a low modulus and an excellent high elongating properties is disclosed, but a nonwoven fabric suitable for a backing ground fabric of automobile interior materials such as door trims, which has particularly excellent moldability and followability, and also has excellent dimensional stability after molding, has not been obtained yet. DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention [0005]The present invention has been invented against the background of the problems of the prior arts, and is to propose a spunbonded nonwoven fabric which has a low modulus, a high elongation retaining property, and has excellent moldability and followability, and also has excellent dimensional stability after molding, particularly suitable for a backing ground fabric of automobile interior materials. Means for Solving the Problem [0006]The present inventors made earnest investigations in order to solve the above-mentioned problems, and consequently they have completed the present invention. That is, the present invention pertains to: (1) a spunbonded nonwoven fabric consisting of continuous fibers containing aromatic polyester (a melting point: Tm1) and aromatic copolymerized polyester (melting point: Tm2=150 degrees centigrade to (Tm1-20 degrees centigrade)) in an amount of 1 to 15% by weight with respect to the aromatic polyester, wherein the elongation rate of the nonwoven fabric is from 20% or more to 100% or less, and the load of elongation of 5% is 1.2 N/50 mm or less per g/m.sup.2 weight; (2) the spunbonded nonwoven fabric described in the above (1), wherein the starting temperature of endotherm of an endothermic peak, pointing the melting point in a temperature raising process of a differential scanning calorimeter, is 140 degrees centigrade or higher; (3) a spunbonded nonwoven fabric consisting of continuous fibers, which contains an aromatic polyester unit in an amount of 80% by mol or more, and in which the starting temperature of endotherm of an endothermic peak, pointing the melting point in the temperature raising process of the differential scanning calorimeter, is from 160 to 260 degrees centigrade, wherein the elongation rate of the nonwoven fabric is from 40% or more to 100% or less when the nonwoven fabric is heated and to be at 120 degrees centigrade, and the load of elongation of 5% is 0.2 N/50 mm or less per g/m.sup.2 weight, (4) the spunbonded nonwoven fabric described in any one of the above (1) to (3), wherein an aromatic polyester is polybutylene terephthalate or polytrimethylene terephthalate; or (5) the spunbonded nonwoven fabric described in any one of the above (1) to (4), having a laminated structure in which the respective layers have different densities each other. EFFECT OF THE INVENTION [0007]The spunbonded nonwoven fabric of the present invention can provide a polyester spunbonded nonwoven fabric at a low price, wherein the polyester spunbonded nonwoven fabric has a low modulus, retains high elongating properties, and has excellent moldability and followability, and also has excellent dimensional stability after molding, particularly suitable for a backing ground fabric of automobile interior materials. More specifically, since the spunbonded nonwoven fabric of the present invention is mainly made of polybutylene terephthalate, polytrimethylene terephthalate or so, that has high crystallinity, good thermal stability and a slightly low modulus, in order to improve the thermal formability of itself; by setting a low thermoforming temperature, it can be provided at a low price as a polyester spunbonded nonwoven fabric which has an excellent low modulus, retains a high elongating property, and has particularly excellent moldability and followability, and also has excellent dimensional stability after molding, particularly suitable for door trims in which deformation is larger among backing ground fabrics of automobile interior materials. BEST MODE FOR CARRYING OUT THE INVENTION [0008]Hereinafter, the present invention will be described in more detail. [0009]A composition of a fiber composing the nonwoven fabric of the present invention is preferably aromatic polyester (a melting point: Tm1) containing 1 to 15% by weight of aromatic copolyester (a melting point: Tm2=150 degrees centigrade to (Tm1-20 degrees centigrade)). [0010]An aromatic polyester referred to in the invention is preferably a polyester using an aromatic dicarboxylic acid and a diol, such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, polybutylene naphthalate and polycyclohexylenedimethyl terephthalate. [0011]The nonwoven fabric of the present invention preferably has a melting point of a temperature at which the other materials do not deteriorate because it is to be combined with the other materials to be used for automobile interior materials, and in the case this melting point is too high compared to those of the other materials, it is not preferred since there is a possibility that the deterioration of the other materials tends to occur. And, when the nonwoven fabric is deformed and fluidized at not enough high temperature for combining, it is not preferred since the requirements for heat resistance are not enough for. In view of these points, as the example of the most preferred embodiment of the present invention, a polyester, that has a melting point (hereinafter, abbreviated as Tm) of 220 degrees centigrade to 250 degrees centigrade at which the thermoforming property is good and the heat resistance is retained, can be listed. [0012]Further, in order to achieve the object of the present invention, it is desired to have high crystallinity and a slightly low modulus. As a material satisfying all these requirements, polybutylene terephthalate (hereinafter, abbreviated as PBT: Tm1; 228 degrees centigrade) and polybutylene naphthalate (hereinafter, abbreviated as PBN: Tm1; 243 degrees centigrade) are recommended. [0013]A melting point (hereinafter, abbreviated as a Tm2) of aromatic copolyester used in the present invention is preferably 150 degrees centigrade to (Tm1-20 degrees centigrade). When the Tm2 is less than 150 degrees centigrade, it is not preferred because the heat resistance in forming a nonwoven fabric is less, and when the Tm2 is more than (Tm1-20 degrees centigrade), it is not preferred because the adhesion among the fibers is hard to improve. The Tm2 is particularly preferably 155 degrees centigrade to (Tm1-30 degrees centigrade), and furthermore preferably 160 degrees centigrade to (Tm1-40 degrees centigrade). [0014]Aromatic copolyesters of the invention means polyesters formed by copolymerizing aromatic polyesters exemplified as described above with other third component, and, for instance, as the examples of other third component, copolyesters obtained by copolymerization of third components as an acid component such as isophthalic acid, adipic acid, sebacic acid and glutaric acid, and also as a diol component such as diethylene glycol, neopentyl glycol, butane diol/ ethylene glycol. It is possible to obtain a polyester spunbonded nonwoven fabric having flexibility and a strong bonding force because of the following reason by using these copolymerization compounds. [0015]The reason of including the above-mentioned copolymerized aromatic polyester having a melting point Tm2 in the above-mentioned aromatic polyester having a melting point Tm1 of the present invention is as follows. That is, melted polyester passes through a fiber spinning orifice in a state in which the copolymerized aromatic polyester is dispersed well in a matrix of the melted aromatic polyester, and it is assumed that at the contacting interface of the melted polyester before exiting the orifice, the copolymerization between the copolyester and the aromatic polyester proceeds, and if the amount of copolymerized aromatic polyester to be added is small, this copolymerization is completed in a relatively short time and a copolymer is dispersed in the matrix. Then, when the melted polyester is subjected to a large searing force in the fiber spinning orifice, it is assumed that the copolymer having a low meltviscosity is rejected toward the surface of the fiber spinning orifice wall to form a sheath-core structure. [0016]For this reason, an aromatic polyester and a copolymerized aromatic polyester may be a resin blend (two or more species of polymers are charged in the form of resin and these polymers are mixed in an extruder and the resulting mixture is extruded to be spun), or the copolyester and the aromatic polyester may be copolymerized by kneading and the like in advance before charging resins. [0017]Thus, spun fiber is taken off in web form onto a net while being cooled close to a solidification point, but then in the fiber containing copolymerized polyester, a bonding force at the interface between the fibers in contact with each other is enhanced, and even though the web is subsequently embossed, the strength of the nonwoven fabric is very improved. According to this result, it is conceivable that spun fiber may attain a sheath-core structure and, therefore such an effect as a thermobonding fiber may be developed. Continue reading... Full patent description for Spunbonded nonwoven fabrics Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Spunbonded nonwoven fabrics patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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