KR20210078399A - Sheet for protecting paint films of automobiles and method for preparing thereof - Google Patents

Abstract

Provided is a sheet for protecting a vehicle coating, including a base layer and a coating layer, wherein the coating layer includes a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit. The present invention has improved scratch resistance.

Description

Automobile coating film protection sheet and manufacturing method thereof {SHEET FOR PROTECTING PAINT FILMS OF AUTOMOBILES AND METHOD FOR PREPARING THEREOF}

The present invention relates to a sheet for protecting an automobile coating film and a method for manufacturing the same.

Automotive painted surfaces are exposed to various external contamination, and it is important to have high weather resistance and contamination resistance from various pollutants. In addition, cracks, film tearing, etc., should not occur in the coating of the automobile painted surface during curved and stretched construction. In addition, when damage occurs, such as a scratch caused by an external impact, etc. on the coating layer, the damage is gradually healed by itself or self-healing property (SELF-HEALING) is also required.

On the other hand, in the case of the existing coating layer exhibiting self-healing properties, there is a problem that the mechanical properties of the coating layer, such as hardness or coating film strength, are not sufficient. In addition, in the case of a coating layer having excellent stain resistance, there is a problem in that crack resistance and the like are lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet for protecting a car paint film having improved scratch resistance with excellent self-healing properties while simultaneously satisfying stain resistance and crack resistance.

It is also an object of the present invention to provide a method for manufacturing the above-mentioned automotive coating film protection sheet.

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

It includes a base layer and a coating layer according to the present invention, wherein the coating layer can provide a sheet for protecting an automobile coating film comprising a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit.

Also preparing a coating composition comprising a compound containing a secondary amine group according to the present invention, a polyol and a polyisocyanate; and applying and curing the coating composition on the base layer to prepare a coating layer comprising a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit; have.

The automotive coating film protective sheet according to the present invention can exhibit improved crack resistance, self-healing properties and scratch resistance that are in a trade-off relationship with excellent stain resistance at the same time.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 schematically shows a cross-section of a sheet according to an embodiment of the present invention.
2 schematically shows a cross-section of a sheet according to another embodiment of the present invention.
3 is a photograph of an experiment in order to evaluate the self-healing properties of the sheet of the present invention.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains 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 a known technology 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 accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

In the following, that an arbitrary component is disposed on the "upper (or lower)" of a component or "upper (or below)" of a component means that any component is disposed in contact with the upper surface (or lower surface) of the component. Furthermore, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Hereinafter, a sheet for car gambling protection according to some embodiments of the present invention will be described.

In one embodiment of the present invention, there is provided a sheet for protecting an automobile paint film comprising a base layer and a coating layer, wherein the coating layer includes a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit.

The automobile paint surface, that is, the automobile paint film, is exposed to various external contamination, and it is important to have high weather resistance and contamination resistance from various pollutants. In addition, crack resistance is required so that phenomena such as cracks and film tearing do not occur in the coating of automobile painted surfaces during curved and stretched construction. In addition, when damage occurs, such as a scratch caused by an external impact, etc. on the coating layer, the damage is gradually healed by itself or self-healing property (SELF-HEALING) is also required. The automotive coating film protective sheet can exhibit excellent scratch resistance at the same time with excellent stain resistance and improved crack resistance and improved self-healing properties in a trade-off relationship.

1 schematically shows a cross-section of the automotive coating film protection sheet 100 according to an embodiment of the present invention. In FIG. 1 , the sheet 100 includes a base layer 10 and a coating layer 20 .

The coating layer 20 includes a polyureaurethane polymer including a urea repeating unit and a urethane repeating unit. In general, the coating layer of the automobile paint protection sheet includes polyurethane including urethane repeating units. Conventional polyurethane does not have sufficient bonding strength in the coating layer, so the stain resistance is low, and when the glass transition temperature is increased to improve stain resistance, there is a problem in that the crack resistance is lowered. On the other hand, the coating layer contains a polyurea urethane polymer containing a urea repeating unit and a urethane repeating unit, and has excellent scratch resistance with improved crack resistance and improved self-healing properties, along with excellent stain resistance due to high bonding strength and appropriate glass transition temperature. can be displayed simultaneously.

The urea repeating unit may be formed by polymerization and curing reaction of a compound containing a secondary amine group and polyisocyanate. When the urea repeating unit is formed using a compound containing a primary amine group, it is difficult to perform the coating process itself because the pot life is too short, and it is difficult to make a coating layer having a uniform thickness. In addition, there may be problems in that it is difficult to construct a coating layer for car paint protection, the elongation is not sufficient, and the crack resistance is lowered. On the other hand, the polyurea urethane polymer includes a urea structural unit formed using a compound containing a secondary amine group, and is strong by controlling the reaction time and curing density of the compound containing the secondary amine group and polyisocyanate, etc. It can form a bonding structure and exhibit excellent stain resistance, hardness and stability during construction. And, the polyurea urethane polymer of the coating layer includes a urea structural unit formed using the compound containing the secondary amine group, and exhibits excellent crack resistance at a certain elongation, along with excellent stain resistance, and excellent self-healing properties. It can show scratch resistance.

In addition, the polyurea urethane polymer of the coating layer may include a urea structural unit formed using the compound containing the secondary amine group and exhibit excellent bonding strength with the base layer, for example, a polyvinyl chloride layer. Accordingly, it is possible to exhibit improved stain resistance due to excellent curing density inside the coating layer and excellent bonding strength with the substrate layer, and improved physical properties due to excellent adhesion to the substrate layer.

The compound containing the secondary amine group may have a structure of Formula 1 below.

[Formula 1]

In Formula 1, A is a substituted or unsubstituted linear or branched alkylene group having 4 to 10 carbon atoms, or includes a substituted or unsubstituted cycloalkylene group having 6 to 20 carbon atoms, and R ¹ to R ⁴ are independent of each other A substituted or unsubstituted C ₁ -C ₁₀ alkoxy group, ^{an ester group having -COOR 7} , a substituted or unsubstituted C ₁ -C ₁₀ aliphatic or alicyclic alkyl group, or a substituted or unsubstituted C ₆ -C ₂₀ aryl group is selected from the group consisting of, and R ⁷ may be selected from the group consisting of a substituted or unsubstituted C ₁ -C ₁₀ aliphatic or alicyclic alkyl group or a substituted or unsubstituted C ₆ -C ₂₀ aryl group.

For example, A may be a substituted or unsubstituted straight-chain alkylene group having 5 to 7 carbon atoms or a substituted or unsubstituted biscycloalkylene group having 12 to 15 carbon atoms, and R ¹ to R ⁴ are -COOR ⁷ ester group, and R ⁷ may be a substituted or unsubstituted C ₁ -C ₅ aliphatic alkyl group.

The compound containing the secondary amine group may have an appropriate length between the secondary amine groups together with the two secondary amine groups, thereby performing polymerization and curing reaction of the polyisocyanate to form an appropriate urea repeating unit. . Accordingly, it is possible to control the structure and cure density of the polyureaurethane polymer included in the coating layer, have an appropriate glass transition temperature and exhibit excellent stain resistance, and improved crack resistance, self-healing properties and scratch resistance at the same time.

The compound containing the secondary amine group may have a structure of Formula 2 below.

[Formula 2]

In the above formula, R ¹ to R ⁴ are each independently a C ₁ to C ₁₀ alkoxy group, an ester group having ^{-COOR 7} _{, a C 1} to C ₁₀ aliphatic or alicyclic alkyl group, or a C ₆ to C ₂₀ aryl group consisting of selected from the group, R ⁵ and R ⁶ are each independently selected from hydrogen, or a C ₁ to C ₅ aliphatic alkyl group, wherein R ⁷ is a C ₁ to C ₁₀ aliphatic or alicyclic alkyl group or C ₆ to C ₂₀ It is selected from the group consisting of an aryl group, and may be an integer of n=0 to 5.

For example, R ¹ to R ⁴ are each an ester group having ^{-COOR 7 , R 5} and R ⁶ are each independently hydrogen, or a substituted or unsubstituted C ₁ to C ₃ aliphatic alkyl group, and the R ⁷ is a substituted or unsubstituted C ₁ to C ₅ aliphatic alkyl group, and n=1 to 3 may be present.

The compound containing the secondary amine group controls the structure and curing density of the polyureaurethane polymer by having a structure and an appropriate length of an alicyclic hydrocarbon between the secondary amine groups, together with two secondary amine groups. It has an appropriate glass transition temperature, has excellent stain resistance, and can exhibit excellent scratch resistance with improved crack resistance and self-healing properties at the same time.

Specifically, the compound containing the secondary amine group may be a monomer having a molecular weight of about 100 g/mol to about 1000 g/mol along with the chemical formula of the structure. or a monomer having a molecular weight of about 100 g/mol to about 600 g/mol. The polyurea urethane polymer includes a urea repeating unit formed from the compound containing the secondary amine group, and can simultaneously exhibit excellent scratch resistance with excellent stain resistance, improved crack resistance and improved self-healing properties.

In addition, the viscosity of the compound containing the secondary amine group may be from about 50 mpa·sec to about 3,000 mpa·sec at 25°C. The viscosity may be measured using a Brookfield viscometer. The polyureaurethane polymer may be mixed with polyisocyanate with excellent compatibility by using a compound containing the secondary amine group having a viscosity in the above range, and reaction efficiency may be appropriately controlled.

The urethane repeating unit may be formed by polymerization and curing reaction of polyol and polyisocyanate.

The polyisocyanate may form a crosslinking reaction through a urea reaction with an amine group of the compound containing the secondary amine group, and the polyisocyanate may form a crosslinking reaction through a urethane reaction with a hydroxyl group of the polyol. Accordingly, the coating layer including the urea repeating unit and the polyurea urethane polymer including the urethane repeating unit may be formed.

The polyisocyanate is at least one selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylene diisocyanate (XDI, xyelne diisocyanate), and combinations thereof. may include The hexamethylene diisocyanate-based polyisocyanate may be divided into a bifunctional type, a trifunctional type and a hexafunctional type according to the number of functional groups. For example, the coating layer can control the curing density by using the trifunctional hexamethylene diisocyanate-based polyisocyanate, and provide excellent self-healing properties, scratch resistance and stain resistance. The trifunctional hexamethylene diisocyanate-based polyisocyanate may be divided into a biuret type, a trimer type (isocyanurate type), and an adduct type according to a structure. For example, the coating layer contains the softest hexamethylene diisocyanate (HDI)-based trimer-type trifunctional polyisocyanate to control the curing rate and adjust the hardness to a desired level, thereby providing excellent elongation. Also, it is possible to provide excellent weather resistance by adjusting the self-recovery performance. Therefore, it may be suitable for use as an exterior material for automobiles.

The amine group of the compound containing the secondary amine group to the isocyanate group (NCO) of the polyisocyanate may be reacted in an equivalent ratio of about 1: 1.2 to about 1.2:1. The polyurea urethane polymer can control the curing density of the coating layer by controlling the equivalent ratio of amine groups to isocyanate groups (NCO), and accordingly, physical properties such as excellent scratch resistance with stain resistance, crack resistance and improved self-healing properties of the coating layer This can be adjusted. For example, if the isocyanate group exceeds the above range, the pot life may be shortened in the compounding process due to polyisocyanate remaining unreacted, and poor appearance may appear due to surface migration when left at an external high temperature due to unreacted curing agent. have. And, when the content of the isocyanate group is less than the above range, the urea repeating unit is not sufficiently formed, and the glass transition temperature is lowered due to insufficient curing density, thereby lowering the curing density, thereby reducing stain resistance and crack resistance.

The polyol may include one selected from the group consisting of polyester-based polyols, lactone-based polyols, polycarbonate-based polyols, polyether-based polyols, and combinations thereof. For example, the polyol may be a polyester-based polyol, and physical properties such as hydrolysis resistance and low-temperature flexibility may be imparted thereto. For example, the polyol may be an acrylate-grafted polyester-based polyol copolymer. The acrylate-grafted polyester 　 polyol copolymer has a (meth) acrylate monomer in the acrylic group of caprolactone-modified hydroxyalkyl (meth) acrylate formed by ring-opening addition polymerization of hydroxyalkyl (meth) acrylate and caprolactone. It may be prepared by graft polymerization. The glass transition temperature of the polyureaurethane polymer may be raised to a certain level by increasing the content of the (meth)acrylate monomer. The polyurea urethane polymer is derived from an acrylate-grafted polyester 　 polyol 　 copolymer to uniformly impart scratch resistance with excellent self-healing power along with superior stain resistance, chemical resistance and abrasion resistance throughout the base layer.

The weight ratio of the urea repeating unit: the urethane repeating unit may be about 6: 4 to about 9: 1. For example, the polyurea urethane polymer may include the urea repeating unit and the urethane repeating unit in a weight ratio of about 7:3 to about 9:1. The repeating unit may be measured using nuclear magnetic resonance (NMR).

The polyurea urethane polymer may appropriately control binding force, curing density, elongation, and the like by adjusting the urea repeating unit and the urethane repeating unit to a content within the above range. Specifically, when the weight ratio of the urethane repeating unit is less than the above range, the glass transition temperature is high, but there is a problem in that physical properties such as stain resistance and scratch resistance are inferior. In addition, when the urethane repeating unit exceeds the above range, the glass transition temperature is lowered, and dust accumulates well due to the tack of the coating layer surface, the stain resistance is lowered, and the coating layer is too soft to cause deep scratches. There may be problems that occur a lot and remain unrecovered even after time passes. Since the physical properties as described above meet the requirements of the automotive exterior material, it is suitable as the automotive coating film protective sheet.

The glass transition temperature (Tg) of the coating layer may be about 35 ℃ to about 60 ℃. The glass transition temperature may be measured using a differential scanning calorimetry (DSC). Specifically, it was measured under the condition that the temperature was increased from -40°C to 90°C at a rate of 10°C per minute. The coating layer includes the polyurea urethane polymer including the urea repeating unit and the urethane repeating unit, and the glass transition temperature may be the glass transition temperature of the polyurea urethane polymer occupying 90% or more of the coating layer. When the glass transition temperature is less than the above range, stain resistance is lowered, scratch resistance and crack resistance are deteriorated, and when the glass transition temperature is higher than the above range, stain resistance is lowered for a name pen, etc., and there may be a problem of poor scratch resistance. .

The water contact angle of the coating layer may be about 60° to about 80°. In general, the coating layer includes a compound including silicon (Si) in the coating composition to impart stain resistance, wherein the coating layer exhibits high hydrophobicity exceeding the above range. However, contaminants tend to bind well to a compound containing silicon (Si) and do not easily fall off, so there is a problem in that pollution resistance is rather deteriorated in the long term.

The coating layer does not contain a compound including silicon (Si) and has an appropriate water contact angle within the above range, so that dust or contaminants can be washed away well by water. For example, when the water contact angle of the coating layer exceeds the above range, there may be a problem in that the degree of adhesion of contaminants is rather increased and it is difficult to wash off. And, by having an appropriate water contact angle in the above range, the coating layer may also have an appropriate curing density. Accordingly, it is possible to exhibit excellent crack resistance and self-healing properties together with excellent stain resistance. The water contact angle is measured by dropping a drop of distilled water on the specimen, expanding the droplet form with a microscope equipped with a contact angle measuring instrument (KRUSS, Germany, DSA100), and measuring the angle formed with the surface of the specimen at the critical points at the left and right ends can be saved by

The thickness of the coating layer may be about 3㎛ to about 30㎛. For example, it may be about 10 μm to about 30 μm. The coating layer has a thickness in the above range, and can simultaneously exhibit excellent scratch resistance with improved crack resistance and improved self-healing properties along with excellent stain resistance.

In general, if the thickness of the coating layer is thick, the self-healing performance increases, but the crack resistance decreases. Crack resistance is related to constructability. For example, when constructing a curved surface, it is stretched to a certain level (about 2 to 30%), and if the coating layer is hard or thick, cracks occur on the surface of the coating layer after a certain time after bending and at a certain temperature. Problems can arise.

Therefore, proper coating layer thickness and hardness must be adjusted to optimize physical properties such as scratch resistance with constructability (crack prevention), stain resistance and self-healing performance.

That is, when the coating layer is soft, self-healing properties and crack prevention performance are excellent, and when the coating layer is hard, stain resistance is excellent. As described above, since various physical properties are complementary, it is necessary to appropriately match the degree of rigidity to be implemented.

The coating layer can simultaneously implement improved crack resistance, self-healing properties and scratch resistance, along with excellent stain resistance, which is complementary in this aspect in the thickness range of the coating layer described above.

In one embodiment of the present invention, it includes a base layer and a coating layer, wherein the coating layer contains a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit, and 23° C. on the surface of the coating layer of 1 inch X 21 cm, Under a load of 100 g, copper wool is reciprocated three times at a rate of 60 times/min to form scratches, and when left in an oven at 60° C. for 1 hour, scratches having a length of 5 mm or more remaining on the surface of the coating layer Provided is a sheet for protecting an automobile coating film having a number of 5 or less.

The automotive coating film protective sheet having the above-described characteristics may exhibit excellent self-healing properties at a rather high temperature of about 50° C. to about 80° C., and thus, it is possible to reduce the number of scratches remaining on the sheet. Specifically, under the above conditions, the number of scratches having a length of 5 mm or more remaining on the surface of the coating layer is 5 or less, indicating excellent self-healing properties. When the scratches formed on the coating layer of the automotive paint film protective sheet have a length of 5 mm or more, the scratches are easily identified with the naked eye, and there may be a problem of lowering the exterior quality of the vehicle. And, when the number of scratches of the above size exceeds 5 under the above conditions, the life of the vehicle is shortened due to a rapid increase in the number of scratches caused by external shocks occurring during vehicle use, and the appearance quality is reduced, and the scratch portion discoloration of PVC forming the base layer may be accelerated. On the other hand, under the above conditions, the number of scratches having a length of 5 mm or more remaining on the surface of the coating layer is 5 or less, and scratches do not increase rapidly even after long-term use in a state exposed to external contamination and impact. , it does not discolor, so it is possible to maintain excellent appearance quality beyond a certain level.

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 the automobile 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. Since polyvinyl chloride has low physical properties such as elasticity and self-healing properties, the physical properties of the coating layer laminated on the substrate layer are particularly important. For example, if a coating layer using a resin having a glass transition temperature in a range similar to that of the present invention is laminated on an upper portion of a base layer comprising polyvinyl chloride, and a scratch is generated by applying an external impact, a scratch is applied to the base layer. Even if it occurs or time passes, the scratch may not be reduced or disappear at all, and the weather resistance may be deteriorated.

The coating layer of the automotive paint film protective sheet includes a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit, and has excellent bonding strength in relation to the base layer including polyvinyl chloride, excellent stain resistance, improved Excellent scratch resistance can be exhibited at the same time with crack resistance and improved self-healing properties. The base layer 10 may have a thickness of about 50 μm to about 300 μm.

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 and a coating layer 20 formed on one surface of the base layer 10 , and an adhesive 30 on another surface of the base layer 10 . and a release paper 40 . In addition, an adhesive layer may be further included between the base layer 10 and the coating layer 20 .

The sheet 200 may be used by attaching the release paper to the surface of the interior or exterior material of an automobile to be protected from damage caused by mechanical, physical, and chemical influences from the outside.

Another embodiment of the present invention comprises the steps of preparing a coating composition comprising a compound containing a secondary amine group, a polyol and a polyisocyanate; and applying and curing the coating composition on the base layer to prepare a coating layer comprising a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit;

As described above by the manufacturing method, it is possible to manufacture a sheet for protecting an automobile coating film, which can simultaneously exhibit excellent scratch resistance with improved crack resistance and improved self-healing properties along with excellent stain resistance. Except as specifically described below, it is the same as described above.

The automotive coating film protective sheet may be prepared by preparing a coating composition including a compound containing a secondary amine group, a polyol, and a polyisocyanate, applying it on a base layer, and thermosetting to form a coating layer.

The step of preparing a coating composition including a compound containing a secondary amine group, a polyol, and a polyisocyanate includes a first composition containing a compound containing a secondary amine group and a polyisocyanate, and a second composition containing a polyol and a polyisocyanate preparing a composition; and preparing a coating composition comprising a mixture of the first composition and the second composition.

In general, since the urea reaction of the compound containing the secondary amine group and the polyisocyanate is faster than the urethane reaction, there may be a problem in that the viscosity of the composition is difficult to control and construction is difficult when simple mixing is performed. In the method for manufacturing the automotive coating film protective sheet, the first composition and the second composition are separately prepared, and then mixed, the ratio of the urea repeating unit and the urethane repeating unit included in the polyurea urethane polymer, the poly The glass transition temperature of the urea urethane polymer can be easily controlled. In this case, the first composition and the second composition may be mixed in a weight ratio of 6: 4 to 9: 1.

In general, it may be difficult to manufacture a sheet by the above manufacturing method depending on the substrate layer. For example, when the base layer includes polyvinyl chloride, it may not be possible to directly coat and cure the coating composition on the base layer due to the weak solvent resistance and weak heat resistance of polyvinyl chloride. In this case, a transfer film is prepared by coating and curing a coating composition on a film such as polyethylene terephthalate (PET), and the transfer film is transferred onto a polyvinyl chloride film. However, since this method requires a separate process for manufacturing the transfer film, there may be problems in that the process efficiency is lowered and the manufacturing cost is increased.

The coating composition may further include a solvent, for example, the solvent is xylene, cocosol, cyclohexanone, ethyl acetate, butyl acetate, butyl cellosolve, methyl isobutyl ketone, isopropyl alcohol, and combinations thereof. It may include one selected from the group consisting of. The coating composition may include the solvent in consideration of the material of the base layer on which the coating layer is to be formed, and provide excellent coating properties and adhesion to the base layer. For example, the coating composition may include butyl cellosolve as a solvent to prevent the base layer from swelling by the solvent, and provide excellent coating properties and adhesion to the base layer.

Specifically, when the base layer includes polyvinyl chloride, the polyvinyl chloride is swollen by a solvent such as toluene and methyl ethyl ketone contained in the coating layer, so that physical properties such as elongation at break and curing density of the sheet can be reduced. . There may be a method of reducing the swelling time of the substrate layer through harsh drying conditions, but it may cause problems in the appearance of the product, and in the case of a substrate weak to heat, problems such as deterioration of substrate properties or discoloration may occur.

The coating composition, including the solvent, can impart significantly improved elongation at break and excellent appearance quality to the base layer, particularly in the base layer including polyvinyl chloride. And, since the coating composition can be directly coated on the base layer and heat-cured, the manufacturing process can be economical.

In addition, the coating composition may further include one additive selected from the group consisting of a UV stabilizer, a reaction retarder, and a combination thereof.

With respect to the base layer, the coating layer, that is, the glass transition temperature of the polyurea urethane polymer is about 35° C. to 60° C., and it is economical to directly apply and thermoset the polyvinyl chloride base layer to prepare a sheet.

In the step of applying the coating composition to the upper portion of the substrate layer, the coating composition may include from about 20% by weight to about 60% by weight of the solid content, specifically, from about 30% by weight to about 50% by weight. When the content of the solid content satisfies the above range, the coating composition may secure excellent coatability, and may be uniformly applied on the substrate layer.

The method of applying the coating composition may, for example, be performed by a gravure coating method under conditions of maintaining the content range of the solid content, and appropriate thickness control may be possible by applying according to the conditions and methods. Specifically, the coating composition can be coated by adjusting the mesh size of the gravure roll.

A coating layer may be prepared by thermosetting the coating composition applied on the base layer. Specifically, after the coating composition is applied to the upper portion of the base layer, the coating composition may be cured by direct thermal curing thereof. The coating composition can be heat-curable while being applied on the base layer, and even when the base layer includes polyvinyl chloride, a coating layer having a strong bonding force can be prepared without damaging the base layer.

Specifically, in the step of preparing the coating layer, the coating composition applied on top of the base layer may be cured by the action of the thermosetting agent even at room temperature, and may be prepared by drying at about 100° C. to about 150° C. . Since the coating composition is manufactured by thermosetting at a temperature in the above range, it is possible to form a coating layer having strong bonding strength and appropriate curing density without damaging all kinds of the base layer, and excellent self-healing properties, crack resistance, and chipping resistance. It is possible to realize resistance to contamination and contamination.

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

Examples and comparative examples of the present invention will be described below. The following examples are only examples of the present invention, and the present invention is not limited to the following examples.

(Example)

Example 1

A compound containing a secondary amine group (molecular weight = 550 g/mol, R ¹ to R ⁴ =-COOC ₂ H ₅ in Formula 2, n = 1, and viscosity at 25 ° C = 900 to 1300 mpa sec) and hexamethylenedi A first composition was prepared by mixing an isocyanate-based trimer-type trifunctional polyisocyanate and a diluent solvent. Then, a second composition was prepared by mixing a polyester-based polyol grafted with methyl methacrylate, a hexamethylene diisocyanate-based trimer-type trifunctional polyisocyanate, and a diluent solvent. Thereafter, the first composition and the second composition were mixed in a weight ratio of 9:1 to prepare a coating composition containing 30% by weight of solid content. Then, the coating composition was applied by gravure coating to a thickness of about 40 μm on the polyvinyl chloride base layer, and then heat-cured in an oven at 130° C. for 2 minutes and 30 seconds. A coating layer including a urethane polymer was prepared. At this time, the weight ratio of the urea repeating unit: the urethane repeating unit of the polyureaurethane polymer included in the coating layer was 9:1, and the glass transition temperature (Tg) was 58°C. Accordingly, a sheet for protecting an automobile coating film including a coating layer having a thickness of about 12 μm on the polyvinyl chloride base layer was prepared.

Example 2

A coating composition is prepared by mixing the first composition and the second composition in a weight ratio of 8:2, and the weight ratio of the urea repeating unit: the urethane repeating unit of the polyureaurethane polymer included in the coating layer is 8:2, A sheet was prepared in the same manner as in Example 1, except that the glass transition temperature (Tg) was set to 55°C.

Example 3

A coating composition is prepared by mixing the first composition and the second composition in a weight ratio of 7:3, and the urea repeating unit of the polyurea urethane polymer included in the coating layer: the weight ratio of the urethane repeating unit is 7:3, A sheet was prepared in the same manner as in Example 1, except that the glass transition temperature (Tg) was set to 45°C.

Example 4

A coating composition is prepared by mixing the first composition and the second composition in a weight ratio of 5:5, and the weight ratio of the urea repeating unit of the polyureaurethane polymer included in the coating layer: the urethane repeating unit is 5:5, A sheet was prepared in the same manner as in Example 1, except that the glass transition temperature (Tg) was set to 34°C.

Example 5

A coating composition is prepared by mixing the first composition and the second composition in a weight ratio of 9.5:0.5, and the urea repeating unit of the polyureaurethane polymer included in the coating layer: the weight ratio of the urethane repeating unit is 9.5:0.5, A sheet was prepared in the same manner as in Example 1, except that the glass transition temperature (Tg) was set to 61 °C.

evaluation

Experimental Example 1: Contamination resistance test for carbon black (βE)

The example sheet was applied to a white painted plate substrate so that the coating layer was on the top. Then, carbon black was evenly applied on the sheet using cotton, and then the surface of the sheet was wiped using a detergent in running water. Thereafter, ΔE of the surface of the sheet was measured using a colorimeter (CM-5), and grades were measured according to the evaluation criteria in Table 1, and are described in Table 3 below. In this case, the lower the grade, the better the stain resistance.

The evaluation criteria are as follows.

rank Grade 1 2nd grade 3rd grade 4th grade △E One 2 4 8 or more

Experimental Example 2: Staining resistance test for name pen ( Δ E)

The example sheet was constructed on a glass substrate (50 mm X 100 mm X 1 mm). Then, the sheet was left at 50° C. for 30 minutes and then left at room temperature for 30 minutes again. Thereafter, 40 mm X 40 mm was marked on the specimen with a name pen (Monami Corporation, name pen), and the surface was washed with ethanol after 1 hour. Thereafter, ΔE of the surface of the sheet was measured using a colorimeter (CM-5), and grades were measured according to the evaluation criteria in Table 2, and the results are shown in Table 3.

rank Grade 1 2nd grade 3rd grade 4th grade △E 3 or less 5 or less 7 or less 9 or less

Experimental Example 3: Residual number of severe scratches (self-healing)

Figure 3 shows an experimental photograph for evaluating the self-healing properties of the sheet of Example. The Example sheet was cut to a size of 3.3 cm (horizontal) X 21 cm (length) to make a specimen and fixed to an abrasion-resistant tester (steel Wool tester, COAD 105, Ocean Science) so that the coating layer 20 was on the top. And, at room temperature (23 ℃), copper wool (Copper wool, Rogue River Tools, 1lb roll, Fine grade, diameter: 100±20㎛) (50) is fixed to an abrasion tester and balanced using a counterweight After adjusting, a 100g weight was installed. In this way, under 100 g load, set at a speed of 60 times/min, and reciprocate 3 times in the direction 60 of both ends (top and bottom) of the sheet with the abrasion resistance tester (diameter: 1 inch), 1 inch (horizontal) A scratch was formed on the surface of the specimen coating layer of X 21 cm (length). Thereafter, the specimen was left in an oven at 60° C. for 1 hour. Then, the number of scratches having a length of 5 mm or more remaining on the coating layer of the specimen was visually confirmed, and the results are shown in Table 3 below.

Experimental Example 1
(Carbon Black Pollution Resistance) Experimental Example 2
(Name pen stain resistance) Experimental Example 3
(Number of remaining scratches) Example 1 Grade 1 Grade 1 2 Example 2 Grade 1 Grade 1 3 Example 3 Grade 1 Grade 1 2 Example 4 3rd grade 2nd grade 14 Example 5 Grade 1 3rd grade 8

Experimental Example 4: Crack resistance (90 ℃ / 30 minutes)

After cutting the sheet of the above embodiment to a size of 4Х20 cm, the sheet is stretched by 25%, 30%, and 35% by 25%, 30% and 35% of the length before stretching (20 cm) on the painted surface. After construction, using a high-temperature oven, it was checked whether cracks occurred on the surface after leaving it at 90° C. for 30 minutes each. And, the results are shown in Table 4 below.

<Evaluation criteria>

O: No cracks:

X: crack

90℃ 25% 30% 35% Example 1 O O O Example 2 O O O Example 3 O O O Example 4 O O X Example 5 O O O

It can be seen that the automotive coating film protection sheet of the above embodiment exhibits excellent physical properties. Example 5 showed poor stain resistance against the name pen, but showed stain resistance against carbon black. Example 4 did not have sufficient self-restoration property than Example 5, so the number of residual scratches was large, and cracks occurred up to the PVC layer, but the stain resistance was better for the name pen than for carbon black. In particular, it can be confirmed that Examples 1 to 3 exhibit excellent stain resistance to both carbon black and name pens. And, the sheets of Examples 1 to 3 have remarkable self-healing properties, and the number of scratches having a length of 5 mm or more remaining on the surface of the coating layer is 5 or less, specifically, 3 or less. It was confirmed that cracking properties were exhibited. As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, although the effects of the configuration of the present invention are not explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

100, 200: car gambling protective sheet
10: base layer
20: coating layer
30: adhesive
40: Lee Hyungji
50: copper wool
60: movement direction

Claims (13)

comprising a base layer and a coating layer,
The coating layer comprises a polyurea urethane polymer including a urea repeating unit and a urethane repeating unit
Automotive paint film protection sheet.
According to claim 1,
The urea repeating unit is formed by polymerization and curing reaction of a compound containing a secondary amine group and polyisocyanate,
The urethane repeating unit is formed by polymerization and curing reaction of polyol and polyisocyanate.
Automotive paint film protection sheet.
3. The method of claim 2,
The compound containing the secondary amine group has a structure of the following formula (1)
Automotive paint film protection sheet:

[Formula 1]

In Formula 1, A is a substituted or unsubstituted linear or branched alkylene group having 4 to 10 carbon atoms, or includes a substituted or unsubstituted cycloalkylene group having 6 to 20 carbon atoms, and R ¹ to R ⁴ are independent of each other A substituted or unsubstituted C ₁ -C ₁₀ alkoxy group, ^{an ester group having -COOR 7} , a substituted or unsubstituted C ₁ -C ₁₀ aliphatic or alicyclic alkyl group, or a substituted or unsubstituted C ₆ -C ₂₀ aryl group It is selected from the group consisting of, and R ⁷ is selected from the group consisting of a substituted or unsubstituted C ₁ -C ₁₀ aliphatic or alicyclic alkyl group or a substituted or unsubstituted C ₆ -C ₂₀ aryl group.
3. The method of claim 2,
The compound containing the secondary amine group has a structure of the following formula (2)
Automotive paint film protection sheet:

[Formula 2]

In the above formula, R ¹ to R ⁴ are each independently a C ₁ to C ₁₀ alkoxy group, an ester group having ^{-COOR 7} _{, a C 1} to C ₁₀ aliphatic or alicyclic alkyl group, or a C ₆ to C ₂₀ aryl group consisting of selected from the group, R ⁵ and R ⁶ are each independently selected from hydrogen, or a C ₁ to C ₅ aliphatic alkyl group, wherein R ⁷ is a C ₁ to C ₁₀ aliphatic or alicyclic alkyl group or C ₆ to C ₂₀ It is selected from the group consisting of an aryl group, and n = an integer of 0 to 5.
3. The method of claim 2,
The viscosity of the compound containing the secondary amine group is 50 mpa · sec to 3,000 mpa · sec at 25 ℃
Automotive paint film protection sheet.
3. The method of claim 2,
The amine group of the compound containing the secondary amine group to the isocyanate group (NCO) of the polyisocyanate react in an equivalent ratio of 1: 1.2 to 1.2:1.
Automotive paint film protection sheet.
3. The method of claim 2,
The polyol includes one selected from the group consisting of polyester-based polyols, lactone-based polyols, polycarbonate-based polyols, polyether-based polyols, and combinations thereof
Automotive paint film protection sheet.
According to claim 1,
The weight ratio of the urea repeating unit: the urethane repeating unit is 6: 4 to 9: 1
Automotive paint film protection sheet.
According to claim 1,
The glass transition temperature (Tg) of the coating layer is 35 ℃ to 60 ℃
Automotive paint film protection sheet.
According to claim 1,
The water contact angle of the coating layer is 60 ° to 80 °
Automotive paint film protection sheet.
According to claim 1,
The thickness of the coating layer is 3㎛ to 30㎛
Automotive paint film protection sheet.
comprising a base layer and a coating layer,
The coating layer comprises a polyurea urethane polymer comprising a urea repeating unit and a urethane repeating unit,
When the surface of the coating layer of 1 inch X 21 cm was formed with scratches by reciprocating copper wool 3 times at a rate of 60 times/min at 23°C and a load of 100g, and left in an oven at 60°C for 1 hour , the number of scratches having a length of 5 mm or more remaining on the surface of the coating layer is 5 or less
Automotive paint film protection sheet.
preparing a coating composition comprising a compound containing a secondary amine group, a polyol, and a polyisocyanate; and
Preparing a coating layer comprising a polyurea urethane polymer comprising a urea repeating unit and a urethane repeating unit by applying and curing the coating composition on the base layer;
A method of manufacturing a sheet for car coating protection.

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