Non-woven fabric for automotive interior skin material and preparation thereof

Description

Technical field

The present invention relates to a non-woven fabric for automotive interior materials and a method for manufacturng the same by performing alkaline etching on the non-woven fabric in a regular pattern, along with pre-treatment processes, such as various coatings and printings on the surfaces of the non- woven fabric.

Prior art

The interior skin materials for automobiles are manufactured primarily by plastic sheets, woven fabrics and non-woven fabrics. The plastic sheets have an excellent moldability, but are poor in tactile feeling. In addition, the woven fabrics have a luxurious external appearance and an excellent moldability owing to a low modulus, but the woven fabrics are expensive because they must be used by laminating a PU foam on a back surface thereof due to small thickness. To solve these problems, the non-woven fabrics have been developed and used for interior materials for automobiles.

The non-woven fabrics are a type of fiber, which are manufactured by spreading a fiber of a regular thickness and length thinly and broadly by a carding process, instead of using warps and wefts like cloth, subsequently laminating the fiber in several layers, and combining the laminated layers by physical bonding, such as needling punching or water entanglement, or by chemical means, such as coating. Accordingly, the non-woven fabrics are widely used for the interior materials for automobiles which are molded in a regular shape by a mold because they have a good productivity with low costs compared to the woven fabrics, and have an excellent elongation in various directions. Such non-woven fabrics for interior materials for automobiles are typically manufactured by a needle punching process or a water entanglement method. In addition, the non-woven fabrics are currently used after coating a binder on a surface or a back surface of the non-woven fabric to impart functionalities, or printing desired patterns or colors on the surface of the non- woven fabric to diversify the external appearances.

However, the non-woven fabrics are good in tactile feeling, but relatively poor in external appearance compared to the woven fabrics. In contrast, if the surfaces of the non-woven fabrics are processed to improve the external appearance thereof, the modulus is significantly increased so that the moldability is degraded. Accordingly, the non-woven fabrics are not suitable for the interior materials for automobiles which need a variety of appearances and an excellent moldability. In addition, as the driving speed of automobiles gets speedier due to the improvement of the engines of automobiles, the sound absorbing properties of the interior materials must be improved to provide a comfortable driving environment during a high-speed drive, but the sound absorbing properties are reduced if the non-woven fabrics have a smooth surface like most of the interior skin materials. Meanwhile, a method of forming various patterns on a woven fabric by an etching method was proposed, but it was available only by an etching method using a laser etching apparatus (see Korean Patent Registration No. 10- 0771071 ). However, a wet etching method using an alkaline solution, such as NaOH, is simple, quick, and easy to control the processing. Moreover, the apparatuses and chemicals used are low in price and it may be helpfully used for a large amount of work. Accordingly, there is a need in the art for a method for acquiring various appearances while using the wet etching method.

To meet such a need, the inventors of the present invention have manufactured the interior skin materials for automobiles with various external appearances, good abrasion resistance and good moldability by performing pre-treatment processes, such as coating or printing the non-woven fabric, independently of the etching process, to form various external appearances. In addition, after such pre-treatment processes, subsequent alkaline etching on the non-woven fabric has apparently enhanced the sound absorbing properties of the interior materials for automobiles.

Disclosure of the invention

The present invention is to solve the afore-mentioned problems, and provide a method for manufacturing a non-woven fabric for interior materials for automobiles by performing an alkaline etching process in a regular shape together with various pre-treatment processes such as coating or printing processes on the surfaces of the non-woven fabric. As such, the present invention can provide a non-woven fabric with an improved abrasion resistance and external appearance as well as an improved moldability and sound absorption properties. To achieve the above object, the present invention provides a method for manufacturing a non-woven fabric by printing a surface or a back surface of the non-woven fabric and then performing an alkaline etching process on the surfaces of the non-woven fabric.

In accordance with said method, it is preferable to coat the surface or the back surface of the non-woven fabric before the printing process.

In accordance with said method, it is more preferable to perform an alkaline etching of non-woven fabric after the printing process, the coating process, or a combination thereof repeatedly.

In accordance with said method, it is preferable that the non-woven fabric comprises fiber layers of greater than 2 and more than 5.

In accordance with said method, the coating process is performed by using a binder comprising at least one selected from the group consisting of acryl, styrene, polyvinylchloride, polyvinyl alcohol, polyester, ethylenevinylchloride, ethylenevinylacetate and polyurethane.

In accordance with said method, it is preferable that the alkaline etching process is performed with respect to greater than 50% to less than 90% of a surface area of the non-woven fabric.

In accordance with said method, it is preferable that the alkaline etching process is performed by using any one selected from the group consisting of NaOH, KOH, RbOH and CsOH, and more preferably by using NaOH.

In accordance with said method, it is preferable that the fiber layers of the non- woven fabric comprise polyester of 50-100wt.%. In addition, the present invention provides a non-woven fabric for interior materials for automobiles manufactured by said method.

The present invention is explained in detail below.

The present invention relates to a method for manufacturing a non-woven fabric for interior materials for automobiles characterized by performing an alkaline etching process on a surface of the non-woven fabric in a desired pattern so that the color of the etching processed non-woven fabric itself can appear, and printing the surface or the back surface of the non-woven fabric before the etching process.

The etching process is used to melt a surface of a fiber in a regular pattern so that a unique three-dimensional appearance may show up. Since the surface of the fiber is melted in a regular shape and depth with a strong alkaline material, the etching process is suitable for the non-woven fabric with a thick fiber layer compared to thin textile fabrics. In addition, since the textile fabrics are woven with warps and wefts, the warps or the wefts are cut during the etching process, and, thus, the strength of the textile fabrics is significantly lowered. However, since the non-woven fabric is entangled with a large number of fiber strands, even if any portion thereof is damaged by processes, neither the tensile strength nor the abrasion strength is seriously deteriorated. Accordingly, the etching process is a suitable method for manufacturing the non-woven fabric.

The present invention uses an alkaline material for the etching process to form three-dimensional patterns on the surface of the non-woven fabric in a regular shape and depth so that three-dimensional structures are formed on the surface of the non-woven fabric, whereby the sound absorbing properties are significantly improved compared to the non-woven fabric of the same weight. In addition, the surface of the non-woven fabric is melted in a regular shape and depth to remarkably reduce a high tensile elongation and a modulus of the non- woven fabric, thereby enhancing the moldability of the non-woven fabric.

However, if only the etching process is performed, since the regular patterns formed by the melting of the surface of the fiber exhibit the same color as the non-woven fabric, it is difficult to obtain various shapes. Therefore, to solve this problem, various external appearances were obtained by performing the printing process before the etching process, and a larger variety was obtained by performing an additional coating process before the printing process. In addition, as a coating layer or a printing layer was added by such a pre- treatment process, the abrasion strength and the dimensional stability was increased, and as a surface area was increased, the sound absorbing properties were improved. Fig. 6 shows an example obtained by performing a combination of various pre-treatment processes.

The present invention forms a non-woven fabric with at least two fiber layers of different colors so that such different colors may appear on the respective fiber layers in a sequential manner, thereby obtaining a non-woven fabric for interior materials with various patterns and colors.

The non-woven fabric is a type of fiber, which is not woven by warps and wefts like cloth, but instead manufactured by spreading a fiber of a regular thickness and length thinly and broadly by a carding process and then laminating the fiber one after another in several layers at a desired weight and width by a web forming machine. Accordingly, since more than five carding machines and web forming machines must be installed to obtain more than five fiber layers with different colors, an excessive investment cost is incurred and thus it is economically unfeasible. Thus, it is preferable that said fiber layers are greater than two layers and less than five layers. The printing or coating process may be performed as a pre-treatment process before etching process. The printing or coating process may be performed, either alone or in combination thereof, on the surface or the back surface of the non-woven fabric. The printing process means to print the surface of the non- woven fabric with a desired pattern or color. The printing process may be performed by a rotary screen method, a flat screen method, or an offset method. In addition, if the coating process is additionally performed before the printing process, more varied external appearances can be obtained compared to performing only the printing process, by allowing various colors different from the color of the non-woven fabric itself to be exhibited.

Advantageous Effects are the following:

The present invention performs printing and coating processes at least two times in a short time to form a variety of patterns on the surface of the non- woven fabric at a low cost, thereby imparting a three-dimensional effect and improving design properties. Due to such pre-treatment processes, the present invention enhances the abrasion resistance, obtains various external appearances, improves the tensile elongation by the etching process, and significantly improves the moldability by reducing the modulus. Accordingly, the present invention solves the problem of the prior art that the conventional coating or printing process reduces the moldability by forming various external appearances. Furthermore, the present invention increases the surface area of the non-woven fabric by the etching process to significantly enhance the sound absorbing properties. In other words, such various external appearances are obtained by the printing or coating process, and the improvements in the physical properties, such as the sound absorbing properties and the moldability, are achieved by the etching process. Accordingly, the present invention can provide a non-woven fabric for interior materials for automobiles with a variety of functions which are recently needed for the interior skin materials for automobiles.

Short description of the drawing

Fig. 1 illustrates the principle of an alkaline etching process,

Fig. 2 illustrates the steps of the alkaline etching process after coating the surface of the non-woven fabric, whereas (1 ) shows a cross-section of the surface coating,

(2) shows alkaline printing,

(3) shows a cross-section after separation,

(4) shows surface coating,

(5) shows alkaline printing, (6) shows a surface after separation,

Fig. 3 illustrates the steps of the alkaline etching process after printing the surface of the non-woven fabric, whereas (1 ) shows a cross-section of surface print, (2) shows alkaline printing,

(3) shows a cross-section after separation,

(4) shows surface print,

(5) shows alkaline printing,

(6) shows a surface after separation,

Fig. 4 illustrates the steps of the alkaline etching process after printing the surface of a two-layered structure of the non-woven fabric, whereas

(1 ) shows a cross-section of the two-layered structure of the non- woven fabric, (2) shows alkaline printing,

(3) shows a cross-section after separation,

(4) shows a surface of the two-layered structure of the non-woven fabric, (5) shows a surface after separation,

Fig. 5 illustrates the step of the alkaline etching process after coating the back surface of the non-woven fabric, whereas

(1 ) shows a cross-section of the back surface coating of the non- woven fabric,

(2) shows alkaline printing,

(3) shows a cross-section after separation,

(4) shows a surface of the back surface coating of the non-woven fabric, (5) shows alkaline printing,

(6) shows a surface after separation,

Fig. 6 illustrates the shape of the surface of the non-woven fabric after various pre-treatment of the non-woven fabric, (a) shows the results wherein coating and printing of different colors are simultaneously performed on the surface of the non-woven fabric, (b) shows the results wherein coating is simultaneously performed on the surface of the non-woven fabric comprising fiber layers each having a different color, (c) shows the results wherein coating of different colors is simultaneously performed on the surface and the back surface of the non-woven fabric, (d) shows the results wherein printing is simultaneously performed on the surface of the non-woven fabric comprising fiber layers each having a different color, (e) shows the results wherein printing and coating of different colors are simultaneously performed on the surface and the back surface of the non-woven fabric, (f) shows the results wherein coating is simultaneously performed on the back surface of the non-woven fabric comprising fiber layers each having a different color, (g) shows the results where coating and printing are simultaneously performed on the surface of the non- woven fabric comprising fiber layers each having a different color, (h) shows the results wherein coating and printing of different colors are performed on the surface of the non-woven fabric, and coating is simultaneously performed on the back surface thereof, (i) shows the results wherein coating is performed on the surface and the back surface of the non-woven fabric comprising fiber layers each having a different color, (j) shows the results wherein printing is performed on the surface of the non-woven fabric comprising fiber layers each having a different color, and coating is performed on the back surface thereof simultaneously,

Fig. 7 illustrates the shapes of the non-woven fabric for interior materials manufactured in accordance with the present invention at each process, (a) shows the surface of the non-woven fabric, (b) shows the printed surface of the non-woven fabric, and (c) shows the surface of the non-woven fabric which was subject to the alkaline etching process after printing,

Fig. 8 illustrates an example wherein the alkaline etching processed non-woven fabric for interior materials is used for a ceiling material of automobiles,

Fig. 9 illustrates the steps of the coating process, whereas

(1 ) shows a binder, (2) shows a first roller, (3) shows a second roller,

(4) shows a gauge,

Fig. 10 illustrates the steps of the printing process, and

Fig. 11 is a graph illustrating the comparison of the absorption coefficient

(« ) of the non-woven fabric for interior materials, with respect to the frequency bandwidths before and after the alkaline etching process. The red color represents the non-woven fabric after the alkaline etching process, and the blue color represents the non- woven fabric before the alkaline etching process.

Embodiments of the invention

The present invention is described in detail below by means of exemplary embodiments, but the embodiments are purely illustrative, and are not to be interpreted as limiting the scope of the present invention.

The non-woven fabric for interior materials in accordance with the present invention is manufactured by pre-treatment processes, such as printing or coating processes, and the etching process.

Embodiment 1 : Coating Process

The processes of a chemical coating (or binder coating) of the present invention is shown in Fig. 9.

The coating apparatus comprises a pair of rollers, and one or both surfaces of the non-woven fabric may be coated by at least one coating apparatus. If the non-woven fabric passes through between the pair of rollers which are rotating in opposite directions based on the central axis, a binder is added to a surface on which one roller and the non-woven fabric are adjacent to each other, so that the surface of the non-woven fabric is coated with the binder. ACRYSOL 890, Acrylic Emulsion DK-6800 DK Chem or EW-100S SKI PET RESIN, available from DKC, is used as the binder.

At this time, the surface of the non-woven fabric contacting the two rollers may be the same (front surface coating), or may be different (back surface coating). In addition, if the front surface coating and the back surface coating is performed simultaneously, a double surface coating is possible. That is, the double surface coating can be made by performing the back surface coating by a pair of rollers, drying the coated back surface, subjecting the dried non-woven fabric to the front surface coating by another pair of rollers, and drying the non- woven fabric again. In other words, the back surface coating is performed in such a manner that the non-woven fabric passes through a first roller, the opposite surface of the surface adjacent to the first roller passes through the second roller, and the binder is introduced between the second roller and the surface adjacent to the non-woven fabric. The foam binder is 50-500 g/l, a coating amount is 5-50 gsm, and the gauge distance between the two rollers of the coating apparatus is OT- 5T.

Embodiment 2: Printing Process

The printing process using a rotary screen method uses a printing unit in which a rotary screen contacts a guide roll (Fig. 10). As the non-woven fabric passes through between a rotary screen roll (a in Fig. 10) and a guide roll (b in Fig. 10) of a first-color printing unit, a color binder (e in Fig. 10) exhausted through a binder provider (c in Fig. 10) installed within the rotary screen roll is pressed by a squeeze bar (d in Fig. 10) so that a portion thereof is discharged out of the external surface of the rotary screen, whereby patterns are formed on the surface of the non-woven fabric. Since the squeeze bar is positioned within the scope of magnetic field of a magnet (an electromagnet) (f in Fig. 10), a predetermined amount of color binder is discharged by the squeeze bar to the outside of the rotary screen in a predetermined position, thereby allowing for printing. At this time, the resolution of a print pattern can be controlled by adjusting the magnetic field intensity of the magnet to 3- 8 kgf. If the magnetic field intensity of the magnet is high, the pattern is dark and vivid, and if the magnetic field intensity thereof is low, the pattern is printed faintly.

A printing unit (second-color printing unit) of the same type as said printing unit is additionally installed at the side, and if the non-woven fabric passes through the first-color printing unit and successively moves to the second-color printing unit, additional patterns are formed. As such, different external appearances are obtained through at least two times of successive processing, and the non- woven fabric is printed with a desired color by mixing the binder with a dye and an inorganic pigment at an amount of 1-10wt.% with respect to a total weight of the binder. Foron Black RD-3G 300 (available from Clariant, Swiss), or Foron Dark Blue RD-2RE 300 (available from Clariant, Swiss), is used for said dye, and RYUDYE-W BLACK RS CONE, RYUDYE-W NAVY BLUE FFTR, RYUDYE-W RED FFGR, RYUDYE-W YELLOW FF3R or RYUDYE-W BROWN FFR (manufactured by DIC, Japan) is used for said inorganic pigment.

The guide roll is formed of a soft material, such as rubber or silicon, so as to reduce a thickness deviation of the non-woven fabric, whereby the surface of the non-woven fabric is printed in a regular thickness. In addition, an open area, in which a print screen is open in a regular pattern so that the binder is escaped to be printed, is about 40-90% of the surface area of the non-woven fabric.

A dye in the form of fine powder is dispersed in water in a substantially colloid state by a dispersing agent to prepare a disperse dye, and the dye is dissolved in the fiber to be dyed on the fiber.

As above, through at least two times of successive printing process, the non- woven fabric is printed with different patterns and colors in accordance with a mixing ratio of the dye and the pigment, whereby various external appearances are obtained.

Embodiment 3: Alkaline etching Process

An alkaline etching process is performed on the surface of the non-woven fabric formed of polyester of 100 wt.%. The alkaline etching process is performed by adding a strong alkaline material, NaOH, on the surface of fiber to melt the fiber in a regular shape and depth. After printing the surface of the non-woven fabric with an alkaline material, the printing solution and the melted portion of the non-woven fabric are separated.

The moldability and the sound absorption properties of the non-woven fabric for interior material manufactured as above were measured.

Embodiment 4: Comparison of Moldability

To confirm the effect of the alkaline etching process on the moldability of the non-woven fabric, the modulus was compared before and after the etching process.

Table 1

In table 1 above, the term "25% modulus" is an important physical property to evaluate the moldability, which means a force required to extend a predetermined length of the non-woven fabric by 25%. Thus, the moldability is better as the value is lower. As shown in Table 1 above, the modulus of the non-woven fabric has been significantly lowered after the etching process than before. In particular, the modulus in the longitudinal direction has been decreased by 30% than it was before the etching process.

Embodiment 5: Comparison of Sound Absorbing Properties

To verify the effect of the etching process on the sound absorbing properties of the non-woven fabric, the sound absorption properties were compared for the respective frequency bandwidths before and after the etching process. The sound absorbing properties of the etching processed non-woven fabric are excellent throughout all the frequency bandwidths than they were before the etching process, and in particular it was confirmed that the sound absorbing properties were remarkably improved in the frequency bandwidths of greater than 1000 Hz (Fig. 11 ). The present invention may be used for interior skin materials for automobiles, and for materials for shoes which is characterized by being manufactured by molding skin materials and a substrate simultaneously for consistent quality and for mass production.