KR102589088B1 - Surface treatment agent and sheet for protecting paint films of automobiles using the same - Google Patents

Abstract

There is provided a surface treatment agent comprising a linear silicon compound and a cyclic silazane, and comprising the linear silicon compound to the cyclic silazane in a weight ratio of 70 to 95:5 to 30.

Description

Surface treatment agent and automobile paint protection sheet using the same {SURFACE TREATMENT AGENT AND SHEET FOR PROTECTING PAINT FILMS OF AUTOMOBILES USING THE SAME}

The present invention relates to a surface treatment agent and a sheet for protecting automobile paint films using the same.

Automotive paint surfaces are exposed to various external contaminants, and it is important to have high weather resistance and resistance to contamination from various contaminant sources. A protective sheet is generally applied to protect the painted surface of a car, and the protective sheet has a basic structure of coating layer/base material/adhesive layer.

The coating layer of the protective sheet is generally made of urethane resin, and in addition to contamination resistance, the coating layer basically requires physical properties such as self-healing, crack resistance, weather resistance, and constructability. In this way, in order to simultaneously optimize multiple properties in one layer, a decrease in fouling resistance is inevitable.

The purpose of the present invention is to provide a surface treatment agent that provides excellent stain resistance and wear resistance.

Another object of the present invention is to provide an automobile paint film protection sheet including an outermost protective layer containing a water-cured product of the surface treatment agent.

The objects of the present invention are not limited to the objects mentioned above, and other objects and advantages of the present invention that are not mentioned can be understood by the following description and will be more clearly understood by the examples of the present invention. Additionally, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

It is possible to provide a surface treatment agent comprising a linear silicon compound and a cyclic silazane according to the present invention, and comprising the linear silicon compound to the cyclic silazane in a weight ratio of 70 to 95:5 to 30.

Additionally, an outermost protective layer containing a cured product of the surface treatment agent according to the present invention; coating layer; And a sheet for protecting an automobile paint film including a base layer can be provided.

The surface treatment agent according to the present invention can provide excellent stain resistance and wear resistance while maintaining the physical properties of the coating layer at a certain level.

In addition, the automobile paint protection sheet according to the present invention can exhibit excellent self-restoring properties, crack resistance, and elongation, as well as improved wear resistance and contamination resistance.

It can also be done according to the present invention.

In addition to the above-described effects, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

Figure 1 schematically shows a cross section of a sheet according to an embodiment of the present invention.
Figure 2 schematically shows a cross section of a sheet according to an embodiment of the present invention.

The above-mentioned objects, features, and advantages will be described in detail later with reference to the attached drawings, so that those skilled in the art will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, identical reference numerals are used to indicate identical or similar components.

Hereinafter, the “top (or bottom)” of a component or the arrangement of any component on the “top (or bottom)” of a component means that any component is placed in contact with the top (or bottom) of the component. Additionally, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Below, surface treatment agents according to some embodiments of the present invention will be described.

In one embodiment of the present invention, a surface treatment agent is provided that includes a linear silicon compound and a cyclic silazane, and the linear silicon compound to the cyclic silazane in a weight ratio of 70 to 95:5 to 30.

A protective sheet is generally applied to protect the painted surface of a car, and the protective sheet has a basic structure of coating layer/base material/adhesive layer. In addition to contamination resistance, the coating layer basically requires physical properties such as self-healing, crack resistance, elongation, weather resistance, and constructability. In this way, in order to simultaneously optimize multiple properties in one layer, a decrease in fouling resistance is inevitable.

The surface treatment agent is applied on the coating layer of the automobile paint protection sheet, and uses different reaction rates and different reaction mechanisms of the cyclic and linear compounds, and silazane and siloxane, while maintaining the physical properties of the coating layer at a certain level. , along with this, contamination resistance and wear resistance, which are in a trade-off relationship, can be improved at the same time.

The surface treatment agent includes cyclic silazanes. The cyclic silazanes can react at a high rate during curing to form an initial cross-linked structure in the matrix, and can improve durability by increasing curing density. In addition, the cyclic silazane has excellent heat resistance and can provide a dense structure even at high temperatures. In addition, when applied to the surface of the coating layer of an automobile paint protection sheet, it adheres stably and exhibits excellent hardness, scratch resistance, and improved stain resistance.

The cyclic silazane may have the structure of Formula 1 below.

[Formula 1]

In Formula 1, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , ^R9 , R ¹⁰ , R ¹¹ and R ¹² may be the same or different from each other and are hydrogen; or _a ^hydrocarbon of C _{1 to C 20} ^{which may} be substituted with ―CN, -NR is selected from the group, and R ^x is hydrogen or C ₁ ~ C ₅ It is selected from a hydrocarbon group, and n is an integer from 0 to 10.

The cyclic silazane contains three or more N atoms in the ring, so that the reaction rate and hardness can be appropriately adjusted and adhesion to the coating layer and scratch resistance can be improved.

And, for example, the cyclic silazane is in Formula 1, R ³ , ^R6 , R ⁹ , and R ¹² may be a C ₁ to C ₂₀ hydrocarbon group substituted with an acrylic group. For example, R ³ above, ^R6 , R ⁹ , and R ¹² may be ethyl acrylate. And, n may be 0.

The surface treatment agent can react at a faster rate because it contains cyclic silazanes having the above structure, and can provide stronger hardness when applied to the coating layer.

The surface treatment agent may include about 1 part by weight to about 30 parts by weight of the cyclic silazane based on 100 parts by weight of the surface treatment agent. If the content of the cyclic silazane is less than the above range, hardness may not be achieved on the surface, and if it exceeds the above range, there may be a problem of not being able to obtain the desired appearance due to too fast a reaction speed.

The cyclic silazanes may include cyclic fluorinated silazanes. For example, the cyclic fluorine-based silazane may refer to a compound having fluorine as a substituent in Chemical Formula 1. The surface treatment agent contains the cyclic fluorine-based silazane and can easily provide softness and flexibility along with a dense cross-linked structure. In addition, the cyclic fluorine-based silazane can more stably attach the surface treatment agent to the coating layer, and can provide improved contamination resistance by suppressing contaminants from getting wet on the surface due to improved water repellency. The cyclic silazane may include about 1 part by weight to about 50 parts by weight of the cyclic fluorinated silazane, based on 100 parts by weight of the cyclic silazane.

Additionally, the surface treatment agent includes a linear silicon compound, and the linear silicon compound may affect the cured structure by crosslinking at a relatively slow rate compared to cyclic silazane. Additionally, the linear silicon compound can provide elasticity and improve crack resistance. The linear silicon compound may include one compound selected from the group consisting of linear polysiloxane, linear polysilazane, and combinations thereof.

The linear polysiloxane may have the structure of Formula 2 below.

[Formula 2]

In Formula 2, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different from each other, and may be selected from siloxane, alkyl, allyl, aryl, alkoxy, amino, hydroxyl, hydrogen, mercapto or cyano, and n is an integer from 0 to about 100,000. And, P ₁ and P ₂ may be the same or different from each other and may be alkyl, allyl, hydroxyl, hydrogen, amino, acetoxy, alkoxy, enoxy, epoxy or oxime.

Specifically, the linear polysiloxane may be a hydroxy-terminated polysiloxane having the structure of Formula 3 below.

[Formula 3]

In Formula 3, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different from each other, and are preferably C _1-6 alkyl, and n may be an integer from 1 to 30,000.

For example, the linear polysiloxane may be hydroxy-terminated polydimethylsiloxane (PDMS) having the structure of Formula 4 below.

[Formula 4]

In Formula 4, n may be an integer from about 1 to about 30,000.

The weight average molecular weight of the linear polysiloxane may be about 500 g/mol to about 100,000 g/mol. If the weight average molecular weight of the linear polysiloxane is less than the above range, there may be a problem of poor wear resistance and contamination resistance, and if it exceeds the above range, there may be a problem of not being able to form a neat thin film coating on the painted surface or film surface. The linear polysiloxane can prevent the spread of contaminants by crosslinking during curing.

The linear polysilazane may be derived from a linear silazane compound having the structure of Formula 5 below.

[Formula 5]

In Formula 5, each R is independently methyl or ethyl, x is about 20 to about 50 mass% of the entire compound, y is about 20 to about 80 mass% of the entire compound, and z is It may be about 0 to about 40 mass% of the total compound.

The weight average molecular weight of the linear polysilazane may be about 500 g/mol to about 100,000 g/mol. If the weight average molecular weight of the linear polysilazane is less than the above range, there may be a problem of limiting the required physical properties, and if it exceeds the above range, there may be a problem in realizing the appearance.

The linear silicon compound may include linear polysilazane to provide elasticity. In addition, linear polysilazane can move to the surface when cured, and can exhibit excellent effects in terms of durability and weather resistance by forming a silazane layer on the surface.

The linear silicon compound may include the linear polysiloxane to the linear polysilazane in a weight ratio of about 10 to 80:20 to 90. If the content of linear polysilazane is less than the above range, properties such as wear resistance may be reduced, and if the content of linear polysilazane exceeds the above range, contamination resistance may be reduced, and the appearance may be impaired due to a rapid reaction on the surface. There may be difficulties with constructability.

The surface treatment agent contains the linear silicon compound to the cyclic silazane in a weight ratio of 70 to 95:5 to 30, so that it can maintain the physical properties of the coating layer at a certain level and provide excellent stain resistance and wear resistance. .

Specifically, the cyclic silazane of the surface treatment agent crosslinks at a fast reaction rate to form an initial crosslinked structure in the matrix, and the linear silicon compound forms another crosslinked structure between the crosslinked structures to increase curing density. Contamination resistance can be improved. In addition, the linear silicon compound may be included at a certain level to provide softness and thus exhibit improved wear resistance.

Specifically, if the content of the cyclic silazane is less than the above range, it is difficult to implement sufficient physical properties, and if the content of the cyclic silazane exceeds the above range, the reaction rate is too fast and the coating layer hardens immediately after application to the surface. Bar construction is difficult and hardness control can be difficult. Additionally, there may be a problem of cracks easily occurring due to a difference in elongation with the coating layer at the bottom.

The surface treatment agent may further include polyfluoroanthracene. The polyfluoroanthracene can provide improved physical properties by being entangled between the linear silicon compound and the dense cross-linked structure formed by the cyclic silazane. For example, the surface treatment agent further includes the polyfluoroanthracene, so that water repellency can be maintained well above a certain level even after long-term use. The polyfluoroanthracene may be included in an amount of about 1 part by weight to about 30 parts by weight based on 100 parts by weight of the surface treatment agent.

The surface treatment agent includes a petroleum-based solvent as a solvent, so that the surface treatment agent can easily be wetted into the lower coating layer and be evenly distributed on the surface during buffing. For example, the surface treatment agent may include a petroleum-based solvent selected from the group consisting of synthetic isoparaffin (Exxon mobil), xylene, toluene, and combinations thereof.

The surface treatment agent may further include a catalyst to better control the reaction rate between the linear silicon compound and the cyclic silazane. The catalyst may be included in an amount of about 0.01 parts by weight to about 1 part by weight based on 100 parts by weight of the surface treatment agent.

The viscosity of the surface treatment agent may be about 50 cps to about 200 cps at 25°C. By having a viscosity within the above range, the surface treatment agent can exhibit excellent workability by appropriately controlling the reaction rate and solvent evaporation rate when applied to the lower coating layer. Specifically, if the viscosity is below the above range, the surface treatment agent flows down immediately when applied on the coating layer, and the solvent, etc. evaporates quickly, making it difficult to secure sufficient curing time. In addition, when the viscosity exceeds the above range, application is generally carried out after sufficiently applying the surface treatment agent to the sponge, but there is a problem in that uniform application is difficult due to the slow absorption rate.

Another embodiment of the present invention includes an outermost protective layer containing a cured product of the surface treatment agent; coating layer; And it provides a sheet for protecting an automobile paint film including a base layer.

Figure 1 schematically shows a cross section of the automobile paint film protection sheet 100 according to an embodiment of the present invention. In Figure 1, the sheet 100 includes a base layer 10, a coating layer 20, and an outermost protective layer 30.

When the surface treatment agent is exposed to moisture, it immediately undergoes a crosslinking reaction and hardens. No separate heat is required for the curing reaction. For example, the surface treatment agent reacts with hydroxy groups on the surface of the lower coating layer and/or with hydroxy groups in the air to form the outermost protective layer 30.

At this time, the thickness of the outermost protective layer may be about 0.01㎛ to about 20㎛. If the thickness of the outermost protective layer is less than the above range, problems may occur with long-term durability and there is a limit to withstanding wear, and if it exceeds the above range, the surface of the outermost protective layer becomes hard and changes depending on temperature. There may be a problem of cracks occurring due to differences in shrinkage rate with the lower layer.

The water contact angle of the outermost protective layer may be about 70° to about 150°. By having a water contact angle in the above range, the outermost protective layer can exhibit excellent anti-fouling properties as well as excellent wear resistance and self-restoring properties. If the water contact angle is less than the above range, there is a problem that contaminants easily adhere and do not fall off. If it exceeds the above range, it is difficult to balance other physical properties, and in order to have a water contact angle in the above range, a large amount of fluorine-based compounds are required, which is uneconomical. There is a real problem.

When evaluating contamination resistance according to 'DIN EN 12720: 1997-10, 1B', the outermost protective layer may have a contamination level of 4 or more against four or more arbitrarily selected contaminants. Specifically, after exposing the outermost protective layer to four or more types of contaminants arbitrarily selected from name pens, oil-based marker pens, ink, mustard, etc., the degree of damage to the surface was visually checked to determine grade 1 (severe damage) to grade 5 (change). graded as none). As a result, it was confirmed that the outermost protective layer had a contamination level ranging from grade 4 (minor change in gloss or color) to grade 5, specifically grade 5. From this, it can be seen that the outermost protective layer according to the present invention has excellent contamination resistance.

The base layer 10 serves as a support, and the base layer is not particularly limited as long as it is a base material used in industry, for example, polyvinyl chloride, polycarbonate, polystyrene, polyamide, polyethylene terephthalate, thermoplastic poly. It may include at least one selected from the group consisting of urethane and combinations thereof. For example, the base layer may include more economical polyvinyl chloride, and the base layer 10 may have a thickness of about 50 ㎛ to about 300 ㎛.

In addition, the coating layer 20 may include a urethane resin, and the coating layer 20 may have a thickness of about 10 ㎛ to about 300 ㎛.

The automotive paint film protection sheet may have an elongation at break of about 100% to about 400% according to the conditions of ASTM D638-95. By having an elongation in the above range, the sheet can provide excellent constructability to products that require stretch construction. Therefore, it can be suitable for use as interior and exterior materials for buildings that require curved molding, surface protective layers for furniture, doors, and chassis, and exterior materials for automobiles with curves, such as automobile tuning films .

Figure 2 schematically shows a cross section of a sheet 200 according to an embodiment of the present invention. Referring to FIG. 2, the sheet 200 includes a base layer 10, a coating layer 20 formed on one side of the base layer 10, and an outermost protective layer 30 formed on one side of the coating layer 20, An adhesive 40 and a release paper 50 may be further included on another side of the base layer 10.

The sheet 200 can be used by removing the release paper and attaching it to the interior and exterior materials of a building, the interior and exterior materials of an automobile, or the surface of various plastic products to be protected from damage due to mechanical, physical, or chemical influences from the outside.

After preparing the surface treatment agent, the sheet can form a film coating on the surface by spreading or spraying it on the top of the coating layer, or applying it by other appropriate means. A single coating will usually be sufficient, but additional coatings may be applied if necessary. Other application methods may include spraying (e.g. via aerosol or pump propelling), spreading, brushing, dipping and rolling.

After being applied to the surface of the coating layer, the surface treatment agent is cured by exposure to moisture at ambient temperature. The curing can usually occur within 30 minutes. Accordingly, graffiti or other wear marks formed on the outermost protective layer of the automobile paint protection sheet can be easily removed by wiping or other conventional methods.

The sheet may be applied as an automobile exterior material, for example, an automobile paint protection film or wrapping film.

(Example)

Example 1

A surface treatment agent containing a linear silicon compound containing linear polysiloxane (DTP-3601) and linear polysilazane (Durazane 2000 series) at a weight ratio of 60:40, cyclic silazane (Duravance RF-1501) and polyfluoroanthracene. was manufactured. At this time, based on 100 parts by weight of the surface treatment agent, 20 parts by weight of the cyclic silazane and 10 parts by weight of polyfluoroanthracene were included, and the linear silicon compound and the cyclic silazane were mixed at a weight ratio of 70:30.

The surface treatment agent was applied/dried on a sheet in which a polyvinyl chloride base layer with a thickness of 90 μm and a urethane resin coating layer with a thickness of 10 μm were laminated to prepare a car gambling protection sheet including an outermost protective layer. At this time, the thickness of the outermost protective layer was 0.5 ㎛.

Example 2:

A car gambling protection sheet was manufactured in the same manner as in Example 1, except that the linear silicon compound and the cyclic silazane were mixed at a weight ratio of 80:20 based on 100 parts by weight of the surface treatment agent.

Example 3:

A car gambling protection sheet was manufactured in the same manner as in Example 1, except that the linear silicon compound and the cyclic silazane were mixed at a weight ratio of 95:5 based on 100 parts by weight of the surface treatment agent.

Comparative Example 1:

A car gambling protection sheet was manufactured in the same manner as in Example 1, except that the linear silicon compound and the cyclic silazane were mixed at a weight ratio of 60:40 based on 100 parts by weight of the surface treatment agent.

Comparative Example 2:

A car gambling protection sheet was manufactured in the same manner as in Example 1, except that the linear silicon compound and the cyclic silazane were mixed at a weight ratio of 99:1 based on 100 parts by weight of the surface treatment agent.

evaluation

Experimental Example 1: Contamination resistance

The sheets of the examples and comparative examples were immersed in 5wt% HCl, 5wt% base NaOH, ethanol, gasoline, diesel, and engine oil, respectively, or marked with a permanent marker, and after 24 hours, they were adhered to the standard 'DIN EN 12720: 1997-10'. , 1B or higher, the contamination resistance of the surface of the hard coating layer was measured, and the grade was measured according to the evaluation criteria described later and listed in Table 1 below.

The evaluation criteria are based on 1) to 6) below.

1) Grade 5 - No visible change

2) Grade 4: There is a slight change in gloss or color.

3) Grade 3: There is a slight change in gloss or color without change in the hard coating layer.

4) Grade 2: There is a significant change in gloss or color that can be observed with the naked eye without a change in the hard coating layer.

5) Grade 1: The hard coating layer is damaged and there is a significant change in gloss or color.

6) Not evaluated: The hard coating layer is peeled off or destroyed.

Experimental Example 2: Self-healing

After the sheets of the examples and comparative examples were scratched three times on the surface of the wire brush, scratches were observed on the surface of the sheet. Check with the naked eye, and use a timer to measure the time it takes for scratches on the sheet to disappear and the sheet to return to its original state at room temperature. The results are listed in Table 1 below .

Experimental Example 3: Elongation at break (%)

Regarding the sheets of the above examples and comparative examples, dogbone samples were collected using mold No. 1 of KSM3507, and using Zwick Roell's Z 1000 model UTM equipment, according to ASTM D638-95, 300 mm/min, distance between gauges 40 mm. Elongation at break was measured under the following conditions. The results are listed in Table 1 below.

Classification papadan
elongation rate Staining resistance self-healing
(min) HCl NaOH ethanol Gasoline diesel engine oil Permanent Marker Example 1 132 5 5 5 5 5 5 5 Within 10 minutes Example 2 156 5 5 5 5 5 5 5 Within 8 minutes Example 3 177 5 5 5 5 5 5 4 Within 5 minutes Comparative Example 1 92 5 4 5 5 5 5 3 Within 15 minutes Comparative Example 2 220 5 5 3 5 5 5 2 Within 4 minutes

Experimental Example 4: Crack resistance

After cutting the sheets of the examples and comparative examples into a size of 4 × 20 cm, the film was applied to the painted surface by extending the film by 20% and 30% compared to the length before stretching (20 cm). After construction, a high-temperature oven was used and left at 80°C and 90°C for 30 minutes each to check whether cracks occurred on the surface.

<Evaluation criteria>

O: No cracks:

X: crack occurs

The results are listed in Table 2.

80℃ 90℃ 20% 30% 20% 30% Example 1 O O O O Example 2 O O O O Example 3 O O O O Comparative Example 1 O O O X Comparative Example 2 O O O O

Experimental Example 5: Wear resistance

Examples and Comparative Examples In order to confirm changes in surface properties due to repetitive friction and wear of the sheet surface, wear resistance was measured using the Martindale method. The test principle is that the surface of the outermost protective layer of a circular test piece installed in a test piece holder is subjected to an abrasive action on the surface of the wearer by performing a translational movement according to the trajectory of the Lissajous figure under a specified load (1N). The abrasion test was conducted 500 times at a time. After each test, the surface was checked for water repellency using a water droplet and a name pen, and the abrasion test was performed an additional 500 times. The number of wears at the point when water repellency decreased was measured, and the results are listed in Table 3.

Number of wear water repellency Example 1 15,000 maintain Example 2 15,000 maintain Example 3 15,000 maintain Comparative Example 1 15,000 maintain Comparative example 2 3,500 X

As shown in the table above, the Example shows excellent effects in all staining resistance, self-healing properties, elongation at break, crack resistance, and abrasion resistance, while Comparative Example 1 is poor in some staining resistance tests, and has poor elongation at break and It can be confirmed that self-healing and crack resistance do not show any physical properties, and that Comparative Example 2 is less effective in some stain resistance tests and has significantly lower wear resistance.

As described above, the present invention has been described with reference to the illustrative drawings, but the present invention is not limited to the embodiments and drawings disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can occur. In addition, although the operational effects according to the configuration of the present invention were not explicitly described and explained while explaining the embodiments of the present invention above, it is natural that the predictable effects due to the configuration should also be recognized.

100, 200: car gambling protection sheet
10: Base layer
20: Coating layer
30: Outermost protective layer
40: adhesive
40: Release paper

Claims (12)

Includes linear silicon compounds and cyclic silazanes,
Comprising the linear silicon compound to the cyclic silazane in a weight ratio of 70 to 95:5 to 30.
Surface treatment agent.
According to paragraph 1,
The linear silicon compound includes linear polysiloxane to linear polysilazane in a weight ratio of 10 to 80:20 to 90.
Surface treatment agent.
According to paragraph 1,
The cyclic silazane has the structure of formula 1 below:
Surface treatment agent:
[Formula 1]


In Formula 1, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , ^R9 , R ¹⁰ , R ¹¹ and R ¹² may be the same or different from each other and are hydrogen; or a ^hydrocarbon group of C ¹ _to C ₂₀ that _{may be} substituted with -CN ^, -NR is selected from the group consisting of, and R ^x is hydrogen or C ₁ to C ₅ It is selected from a hydrocarbon group, and n is an integer from 0 to 10.
According to paragraph 1,
Comprising 1 to 30 parts by weight of the cyclic silazane, compared to 100 parts by weight of the surface treatment agent.
Surface treatment agent.
According to paragraph 1,
The cyclic silazanes include cyclic fluorinated silazanes.
Surface treatment agent.
According to paragraph 1,
Further containing polyfluoroanthracene
Surface treatment agent.
According to paragraph 1,
Viscosity of 50 cps to 200 cps at 25°C
Surface treatment agent.
An outermost protective layer comprising a cured product of the surface treatment agent according to any one of claims 1 to 7;
coating layer; and
containing a base layer
Car paint protection sheet.
According to clause 8,
The thickness of the outermost protective layer is 0.01㎛ to 20㎛
Car paint protection sheet.
According to clause 8,
Elongation at break of 100% to 400% according to the conditions of ASTM D638-95
Car paint protection sheet.
According to clause 8,
The water contact angle of the outermost protective layer is 70° to 150°.
Car paint protection sheet.
According to clause 8,
'When evaluating contamination resistance according to DIN EN 12720: 1997-10, 1B, the contamination level for four or more randomly selected contaminants is grade 4 or higher.
Car paint protection sheet.

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