KR20090072273A - Decoration sheet having good scratch-resistance, anti-finger print and soft skin feeling and method for preparing the same - Google Patents

Abstract

An ornamental sheet having anti-finger print property and scratch resistance and a manufacturing method thereof are provided to implement deluxe feeling with soft feel, and to offer excellent scratch resistance. An ornamental sheet having anti-finger print property and scratch resistance comprises surface layer(1) including cross-linkable resin particles of which average diameter is 1 - 10 mum, an inorganic particle or their mixture, and a transparent base layer(2). The surface layer is comprised of a resin composition including the cross-linkable resin particles of which average diameter is 1 - 10 mum, the inorganic particle(3) or the their mixture including a compound 10 - 100 weight% and transparent resin 0 - 90 weight%. The resin composition further includes light diffuser 0 ~ 10 weight%. The transparent base layer has thickness of 3 -20 mm.

Description

Decorative sheet having good scratch-resistance, anti-finger print and soft skin feeling and method for preparing the same

1 is a side cross-sectional view of a decorative sheet of the present invention.

2 is an optical micrograph of the surface state of the decorative sheet prepared in Example 1 of the present invention.

3 is an optical micrograph of the surface state of the decorative sheet prepared in Comparative Example 1 of the present invention.

4 is an optical micrograph of the surface state of the decorative sheet prepared in Comparative Example 4 of the present invention.

5 is a photograph comparing the decorative sheet prepared in Example 1 of the present invention and the general confetti, and is a photograph showing that the color of the back surface of the decorative sheet is softly and deeply reflected.

Brief description of the main symbols in the drawing

1: Surface layer 2: Transparent base material layer

3: spherical crosslinkable resin or inorganic particle 4: colored paper

5: decorative sheet of the present invention

Field of invention

The present invention relates to a decorative sheet having a soft touch on the surface and excellent in stain resistance and scratch resistance. More specifically, the present invention integrates a surface layer containing a crosslinkable resin, inorganic particles, or a mixture thereof with a transparent substrate layer, and has a soft touch on the surface, and is excellent in stain resistance and scratch resistance and has a deep back surface. The present invention relates to a decorative sheet and a method of manufacturing the same, which can realize a luxurious feeling due to the soft and light effect.

Background of the Invention

Recently, decorative sheets, which are increasingly used as building interior finishing materials or exterior materials for home appliances, are being differentiated and advanced according to consumer preferences.

These materials have a feature that requires a variety of physical properties because the use is not particularly limited.

For example, scratching and fingerprint contamination by users should not damage the initial product feel. In addition, when viewed with the naked eye, there is a characteristic that requires a soft touch as well as a luxurious feeling.

Therefore, the inventors of the present invention mix the crosslinkable resin, the inorganic particles, or a mixture thereof and the light diffusing agent in a proportion to the transparent resin to form a surface layer in order to form a product having all of the above characteristics and integrate it with the transparent base layer. It is to develop a decorative sheet that can produce a high-quality feeling due to the soft touch surface, excellent stain resistance and scratch resistance, and the back surface is softly reflected.

An object of the present invention is to provide a decorative sheet excellent in antifouling and scratch resistance and a method for producing the same.

Another object of the present invention is to provide a decorative sheet having a soft touch on the surface and a method of manufacturing the same.

Still another object of the present invention is to provide a decorative sheet and a method of manufacturing the same, which can realize a luxurious feeling due to the effect that the backside is softly reflected.

The above object of the present invention can be achieved by the following description. Hereinafter, the content of the present invention will be described in detail.

Summary of the Invention

The present invention relates to a decorative sheet having excellent anti-fouling resistance and scratch resistance, which is composed of a surface layer and a transparent base layer comprising crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 µm.

In one embodiment of the invention, the surface layer is formed comprising 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 ㎛ and 0 to 90% by weight transparent resin .

The present invention provides a method for producing the decorative sheet. In one embodiment, a surface layer comprising 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof, an average particle diameter of 1 to 10 μm, 0 to 90% by weight of a transparent resin, and 0 to 10% by weight of an optical acid. The master batch composition and the pellet for transparent substrate layer may be supplied to a die for coextrusion, respectively, and coextruded to a surface layer thickness of 0.06 to 1 mm and a transparent substrate layer thickness of 3 to 20 mm.

In another embodiment of the present invention, 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 μm, 0 to 90% by weight of a transparent resin, and 0 to 10% by weight of an optical powder Extruding the master batch composition for the surface layer to prepare a film having a thickness of 0.06 to 1 mm; And adhering to the film a film for a transparent substrate layer having a thickness of 3 to 20 mm selected from the group consisting of methacryl resin, polycarbonate resin, styrene resin, polyester resin, and combinations thereof.

Hereinafter, the content of the present invention will be described in detail below.

Detailed Description of the Invention

The decorative sheet of the present invention comprises a surface layer and a transparent base layer containing crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 µm.

In one embodiment of the present invention, the surface layer may be formed of only crosslinkable resin particles, inorganic particles or a mixture thereof.

In another embodiment of the present invention, the surface layer may be formed of a composition in which a transparent resin is mixed with a crosslinkable resin particle, an inorganic particle, or a mixture thereof as a binder. In another embodiment of the present invention, the surface layer is formed from a resin composition in which crosslinkable resin particles, inorganic particles or a mixture thereof, a transparent resin, and a light diffusing agent are mixed.

In one embodiment, the resin composition includes 10 to 100% by weight of crosslinkable resin particles, inorganic particles or a mixture thereof, 0 to 90% by weight of a transparent resin, and 0 to 10% by weight of a light diffusing agent.

In another embodiment, the resin composition includes 20 to 90% by weight of crosslinkable resin particles, inorganic particles or a mixture thereof, 10 to 80% by weight of a transparent resin, and 0 to 10% by weight of a light diffusing agent.

In yet another embodiment, the resin composition includes 30 to 80 wt% of the crosslinkable resin particles, inorganic particles or a mixture thereof, 20 to 70 wt% of the transparent resin, and 0 to 10 wt% of the light diffusing agent.

When the crosslinkable resin particles, inorganic particles, or mixtures thereof are used in an amount less than 10% by weight, sufficient amount of spherical particles do not exist in the surface layer, so it may be difficult to secure scratch resistance, and it may be difficult to realize a soft feeling. Can be.

The crosslinkable particles, inorganic particles or mixtures thereof used in the present invention preferably have a diameter ranging from 1 μm to 10 μm. If the particle size is less than 1 μm, the surface may not be smooth and give a soft feeling. If the particle size is larger than 10 μm, the surface feel may be rough and insufficient to implement the effect of the present invention to have a soft feeling. In addition, the crosslinkable particles, inorganic particles, or a mixture thereof may preferably have a hardness of 4H or higher pencil hardness.

The shape of the crosslinkable particles, inorganic particles or mixtures thereof is not particularly limited, but preferably has a spherical shape.

The crosslinkable particles use crosslinked resin particles. If spherical particles of a general synthetic resin that is not crosslinked are used, the scratch resistance of the surface layer may not be sufficiently high, and thus may be insufficient to implement the effects of the present invention.

The crosslinkable resin may be a (meth) acrylic resin, a styrene resin, a silicone resin, or the like, but is not necessarily limited thereto. These may be used alone or in combination of two or more thereof, and copolymerized forms thereof may also be used. Since the acrylic crosslinkable particles may not only have a high surface hardness of 4H or more, but also have excellent miscibility with the transparent substrate layer, the acrylic crosslinkable particles are most preferable in terms of easy control of physical properties and favorable yellowing due to long-term use.

The inorganic particles may be used, such as silica, alumina, natural stone powder, but are not necessarily limited thereto. These can be used individually or in mixture of 2 or more types.

In addition, particles in the form of organic-inorganic hybrids may also be used.

In addition, in the present invention, the color of the back surface is softly reflected and a haze is applied to the surface layer in order to realize a luxurious feeling. Preferably, the turbidity of the surface layer is 30% or more based on JIS K 7136, more preferably 30% to 90%, even more preferably 50 to 80%, and most preferably 60 to 75%.

In the present invention, the turbidity of the surface layer is controlled by the content and size of the spherical particles, the refractive index difference between the spherical particles and the transparent resin, the thickness of the surface layer, the type and the amount of the light diffusing agent.

If not to form a separate surface layer on the transparent substrate layer, to form a fine scratch on the surface, such as sand blasting (FIG. 4), or to provide turbidity by using a crimping or chemical corrosion using a roller with fine unevenness, etc. In this case, the turbidity is significantly reduced by the contact of water or oil with the surface, so that the effect of the present invention is not realized.

In addition, when the turbidity of the transparent substrate layer is increased by a method of controlling the turbidity of the surface layer, it is not preferable because the depth of the visible color of the back surface is reduced. It is also possible to prepare a product of various colors by mixing a variety of dyes and the like in a range that has little effect on the turbidity of the transparent substrate layer.

The surface layer of the present invention may optionally further comprise a light diffusing agent. The light diffusing agent is used to impart the haze of the surface layer. When turbidity is imparted to the surface layer, the color of the back surface is softly reflected and a luxurious feeling can be realized. If the refractive index difference between the crosslinkable particles and the transparent resin is sufficiently large, the turbidity of the level to be implemented in the present invention may be used. However, when the difference in refractive index between the spherical crosslinkable particles and the transparent resin is almost the same, a light diffusing agent should be used, and the amount of the light diffusing agent is preferably in the range of 0 to 10% by weight in the surface layer. In one embodiment of the invention the light diffusing agent is used at 0.1 to 7% by weight. In other embodiments of the present invention can be used at 0.15 to 6% by weight. When used in excess of 10% by weight, the surface texture by the light diffusing agent may be reduced, which is not preferable. Therefore, as long as the refractive index difference from the transparent resin is 0.05 or more light diffusing agent, any of those conventionally used in the technical field to which the present invention belongs may be used.

The transparent resin used for the surface layer in the present invention constitutes a continuous phase in the surface layer and is used as a binder. The transparent resin may be a (meth) acrylic resin, polycarbonate resin, styrene resin, polyester resin, and the like, but is not necessarily limited thereto. These can be used individually or in mixture of 2 or more types. The transparent resin is not necessarily the same material as that used for the transparent substrate layer, but it is preferable to use the same material as much as possible in order to prevent problems due to the formation of unnecessary interfaces. In addition, the transparency of the transparent resin preferably has a total light transmittance of 90% or more at a thickness of 5 mm.

In one embodiment of the present invention, the surface layer of the transparent resin forms a continuous phase, wherein the crosslinkable particles, inorganic particles or a mixture thereof having a diameter ranging from 1 μm to 10 μm form a dispersed phase. The dispersed phase is preferably present evenly distributed in the continuous phase.

As the transparent resin used in the transparent substrate layer in the present invention, (meth) acrylic resin, polycarbonate resin, styrene resin, polyester resin, or the like may be used, but is not necessarily limited thereto. These can be used individually or in mixture of 2 or more types. In addition, the transparency of the transparent resin used in the transparent substrate layer preferably has a total light transmittance of 90% or more at a thickness of 5 mm.

In addition to the transparent resin, the transparent substrate layer of the present invention may prepare a product of various colors by mixing various colors of dyes or coloring agents. In addition, the transparent base layer preferably does not contain a light diffusing agent.

In the present invention, the thickness of the transparent substrate layer is 3 to 20 mm, preferably 5 to 10 mm, and more preferably 7 to 8.5 mm. When the thickness of the transparent substrate layer is less than 3 mm, the depth of the soft color of the back surface may be reduced.

In another aspect of the present invention, a method for producing the decorative sheet is provided. In the present invention, the surface layer may be prepared by mixing the respective compositions in advance to prepare in the form of a master batch or film, or proceed simultaneously with the process of integrating with the transparent substrate layer. That is, the surface layer composition prepared in the form of a master batch and the transparent resin forming the transparent substrate layer may be prepared by a method of coextrusion, or may be prepared by simultaneously mixing the surface layer composition in the process of coextrusion.

In one embodiment, the decorative sheet of the present invention comprises 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 μm, 0 to 90% by weight of transparent resin and 0 to 10 optical powders. The master batch composition for the surface layer and the transparent substrate layer pellets containing the weight% are supplied to the die for the coextrusion, respectively, and coextruded to the surface layer thickness of 0.06 to 1 mm and the transparent substrate layer thickness of 3 to 20 mm.

In another embodiment, the decorative sheet of the present invention is 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 ㎛, 0 to 90% by weight transparent resin and 0 to optical powder Extruding the master batch composition for the surface layer comprising 10% by weight to prepare a film having a thickness of 0.06 to 1 mm; And it is prepared by adhering the film for 3 to 20 mm thick transparent substrate layer selected from the group consisting of methacryl resin, polycarbonate resin, styrene resin, polyester resin and combinations thereof to the film. When the surface layer manufactured in the form of a film is adhered to the transparent substrate layer, thermal fusion or an adhesive may be used.

In view of quality stability and productivity of the product, a method of coextrusion with a transparent resin that produces the surface layer in a master batch form to form a transparent substrate layer is preferable.

The decorative sheet prepared according to the present invention does not lower the turbidity of the surface layer compared to before contacting by water or oil components to the surface layer by 10 or more, pencil hardness is 4H or more excellent in stain resistance and scratch resistance. In addition, the back is deeply and subtlely reflected to create a luxurious feel. Therefore, it can be applied as a top plate of various counters, such as a vanity table top, a reception desk of a bank and a general store, an inner wall material of a product store, an exterior material of a home appliance, and the like.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

Example 1

59 wt% of polymethyl methacrylate, 40 wt% of crosslinked polymethylmethacrylate particles having an average particle diameter of 4 μm, and 1 wt% of a silicon-based light diffusing agent having a refractive index of 1.43 were mixed to prepare a masterbatch composition for a surface layer.

The composition was fed to a coextrusion die at a flow rate of 10 kg / hr using a 5 mm diameter subextruder, and the polymethyl methacrylate pellets were fed at a flow rate of 800 kg / hr using a 150 mm diameter main extruder. A decorative sheet having a thickness of 8 mm was formed by feeding the die for coextrusion into a surface layer having a thickness of 0.1 mm and a transparent base layer having a thickness of 7.9 mm. The surface feel, turbidity, scratch resistance, anti-fouling property, and color depth of the prepared sheet were measured by the following physical property measurement method. The results are shown in Table 1, and the surface state of the decorative sheet was observed with an optical microscope. A photograph is shown in FIG. 2, and a photograph comparing the decorative sheet and the general confetti is shown in FIG. 5.

Example 2

59.6 wt% of polymethyl methacrylate, 40 wt% of crosslinked polymethylmethacrylate particles having an average particle diameter of 4 μm, and 0.4 wt% of a silicon-based light diffusing agent having a refractive index of 1.43 were mixed to prepare a masterbatch composition for a surface layer.

The prepared masterbatch composition alone was made into a 0.2 mm thick film, and an unsaturated polyester resin (Aekyung Chemical TP145) and methyl ethyl ketone peroxide were used as an adhesive on the surface of a separately prepared 8 mm thick polymethyl methacrylate sheet. After applying the mixture thinly, the prepared surface layer film was roll-pressed and bonded to cure the adhesive to complete the adhesion to prepare a decorative sheet product. The surface feel, turbidity, scratch resistance, anti-fouling resistance, and color depth of the prepared sheet were measured by the following physical property measurement methods, and the results are shown in Table 1.

Example 3

59.5% by weight of polymethyl methacrylate, 40% by weight of crosslinked polymethylmethacrylate particles having an average particle diameter of 4 µm, and 0.5% by weight of a silicon-based light diffusing agent having a refractive index of 1.43 were mixed to prepare a masterbatch composition for a surface layer.

The surface layer composition was supplied to the die for co-extrusion at a flow rate of 20 kg / hr using a sub-extruder, and the pellet for transparent base material was supplied to the die for co-extrusion at a flow rate of 800 kg / hr using a main extruder to 0.2 mm in thickness. A decorative sheet having a thickness of 8 mm formed of a surface layer of and a transparent substrate layer of 7.8 mm was prepared. The surface feel, turbidity, scratch resistance, anti-fouling resistance, and color depth of the prepared sheet were measured by the following physical property measurement methods, and the results are shown in Table 1.

Example 4

58 wt% of polymethyl methacrylate, 40 wt% of crosslinked polymethylmethacrylate particles having an average particle diameter of 4 μm, and 2 wt% of a silicon-based light diffusing agent having a refractive index of 1.43 were mixed to prepare a masterbatch composition for a surface layer.

The surface layer composition was supplied to the die for coextrusion at a flow rate of 6 kg / hr using a sub-extruder, and the pellet for transparent base material was supplied to the die for coextrusion at a flow rate of 800 kg / hr using a main extruder, and the thickness was 0.06 mm. A decorative sheet having a thickness of 8 mm formed of a surface layer of and a transparent substrate layer of 7.94 mm was prepared. The surface feel, turbidity, scratch resistance, anti-fouling resistance, and color depth of the prepared sheet were measured by the following physical property measurement methods, and the results are shown in Table 1.

Comparative Example 1

A decorative sheet was prepared in the same manner as in Example 1, except that 40 wt% of a crosslinked polymethylmethacrylate particle having an average particle diameter of 40 μm was used to prepare the surface layer composition. The surface feel, turbidity, scratch resistance, anti-fouling property, and color depth of the prepared sheet were measured by the following physical property measurement method, and the results are shown in Table 1, and the surface state of the decorative sheet was observed by an optical microscope. 3 is shown in FIG.

Comparative Example 2

A decorative sheet was manufactured in the same manner as in Example 1, except that 5 wt% of crosslinked polymethylmethacrylate particles having an average particle diameter of 4 μm were used to prepare the surface layer composition. The surface feel, turbidity, scratch resistance, anti-fouling resistance, and color depth of the prepared sheet were measured by the following physical property measurement methods, and the results are shown in Table 1.

Comparative Example 3

A decorative sheet was manufactured in the same manner as in Example 1, except that a flow rate of the sub-extruder was 5 kg / hr to form a surface layer of 0.05 mm.

Comparative Example 4

# 80 to 120 grit of silica particles were sandblasted at a pressure of 2.5 kg / cm 2 to form a fine scratch on the surface of the transparent sheet, which was prepared using only the transparent substrate layer, to prepare a decorative sheet. The surface feel, turbidity, scratch resistance, antifouling property, and color depth of the prepared sheet were measured by the following physical property measurement methods, and the results are shown in Table 1, and the surface state of the decorative sheet was observed with an optical microscope. The photo was shown in FIG.

Comparative Example 5

The flow rate of the main extruder was 190 kg / hr, and a decorative sheet was prepared in the same manner as in Example 1 except that the thickness of the product was 2 mm, formed of a 0.1 mm thick surface layer and a 1.9 mm transparent substrate layer.

Comparative Example 6

A decorative sheet was manufactured in the same manner as in Example 1, except that the light diffusing agent was mixed with the transparent base layer resin in an amount of 0.01% by weight without using a light diffusing agent in preparing the master batch composition for the surface layer.

The decorative sheets prepared by the above Examples and Comparative Examples are shown in Table 1 by measuring the physical properties by the following method.

1) Tactile: The evaluation team was composed of 20 people, and lightly touched the surface of the product with a fingertip to rub the perceived feeling into three categories: "smooth", "soft" and "rough", resulting in a feeling of more than 18 people empathizing Adopted.

2) Haze (%): The haze meter was measured according to JIS K 7136.

3) Scratch resistance: The pencil hardness value was measured according to JIS K 5400.

4) Anti-fouling property: After measuring the turbidity of the product, glycerol was applied to the surface, and the turbidity was re-measured again under the same conditions to record the change in turbidity. The smaller the change in turbidity, the better the antifouling property.

5) Depth of color: The evaluation stage was configured as in the tactile measurement method, and the surface layer film prepared in Example was placed on the colored paper to reflect the presence of depth.

TABLE 1

As shown in Table 1, Comparative Example 1 using a large spherical particles was found to have a rough surface feel. Comparative Example 2 having a low content of the spherical particles contained in the surface layer was confirmed that the scratch resistance is not significantly reduced and sufficient surface properties do not appear. In addition, if a surface layer having a sufficient thickness is not formed in the same surface layer composition as in Comparative Example 3, a sufficient level of turbidity does not appear, and in the case of forming a fine scratch on the physical surface as in Comparative Example 4, sufficient scratch resistance is achieved. In addition, it was observed that fingerprint contamination was not good. When the thickness of the transparent substrate layer was too thin as in Comparative Example 5, or when turbidity was imparted to the transparent substrate layer instead of the surface layer as in Comparative Example 6, it was observed that the depth of the back color did not appear sufficiently. . On the other hand, as can be seen in Figure 5, in the case of the decorative sheet prepared in Example 1 is given a soft touch on the surface, it can be seen that the scratch resistance and fingerprint contamination resistance is improved and the depth of the back color is felt.

The present invention has the effect of providing a decorative sheet and a method for producing the same, which has a soft touch on the surface and excellent anti-fouling resistance and scratch resistance, and the effect that the surface and the opposite surface are softly reflected in depth.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (11)

A surface layer comprising crosslinkable resin particles, inorganic particles or a mixture thereof having an average particle diameter of 1 to 10 µm; And Transparent substrate layer; Decorative sheet excellent in anti-fouling and scratch resistance. According to claim 1, wherein the surface layer is made of a resin composition comprising 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof having an average particle diameter of 1 to 10 ㎛ and 0 to 90% by weight of a transparent resin Decorative sheet excellent in anti-fouling and scratch resistance. The decorative sheet of claim 2, wherein the resin composition further comprises a light diffusing agent greater than 0 wt% and 10 wt% or less. The decorative sheet of claim 3, wherein the light diffusing agent has a refractive index difference of 0.05 or more from the transparent resin. The decorative sheet of claim 1, wherein the transparent substrate layer has a thickness of 3 to 20 mm. The method of claim 1, wherein the crosslinkable resin particles are selected from the group consisting of (meth) acrylic resins, styrene resins, silicone resins, and mixtures thereof; The inorganic particles are decorative sheets excellent in anti-stain and scratch resistance, characterized in that selected from the group consisting of silica, alumina, natural stone powder and mixtures thereof. The anti-fouling agent according to claim 1, wherein the transparent base layer is a resin layer selected from the group consisting of (meth) acrylic resins, polycarbonate resins, styrene resins, polyester resins, and combinations thereof. Decorative sheet with excellent scratch resistance. The antifouling and scratch resistance of claim 2, wherein the transparent resin is selected from the group consisting of (meth) acrylic resins, polycarbonate resins, styrene resins, polyester resins, and combinations thereof. This excellent decorative sheet. The decorative sheet having excellent anti-fouling resistance and scratch resistance according to claim 1, wherein the surface layer has a turbidity of 30 to 90% according to JIS K 7136. A master batch composition for a surface layer comprising 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof, an average particle diameter of 1 to 10 μm, 0 to 90% by weight of a transparent resin, and 0 to 10% by weight of an optical acid; A method for producing a decorative sheet excellent in anti-stain and scratch resistance, wherein the pellets for the transparent base material layer are respectively supplied to the die for co-extrusion and co-extruded to the surface layer thickness of 0.06 to 1 mm and the transparent base material thickness 3 to 20 mm. . A master batch composition for surface layer comprising 10 to 100% by weight of crosslinkable resin particles, inorganic particles or mixtures thereof, an average particle diameter of 1 to 10 μm, 0 to 90% by weight of a transparent resin and 0 to 10% by weight of an optical acid Extrusion to produce a film of thickness 0.06-1 mm; And Adhering a film for a transparent substrate layer having a thickness of 3 to 20 mm selected from the group consisting of methacryl resin, polycarbonate resin, styrene resin, polyester resin, and combinations thereof to the film; Method for producing a decorative sheet excellent in stain-resistant and scratch resistance, characterized in that consisting of a step.

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