KR102149955B1 - Uv curable coating composition with excellent yellowing resistance and the deco sheet and method for manufacturing the same - Google Patents

Abstract

Disclosed is a UV curable coating composition having excellent yellowing resistance.
The coating composition according to the present invention comprises a urethane acrylate resin formed by polymerizing isocyanate and polyol including a chain structure by a polyurethane bond; Acrylate monomers; Photoinitiators; UV curable silicone additives; And a solvent; characterized in that it contains.

Description

UV curable coating composition with excellent yellowing resistance, decoration sheet using the same, and manufacturing method thereof {UV CURABLE COATING COMPOSITION WITH EXCELLENT YELLOWING RESISTANCE AND THE DECO SHEET AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a UV-curable coating composition, a decor sheet using the same, and a method of manufacturing the same, and more particularly, to a coating composition capable of improving the yellowing resistance of the cured coating.

The UV curable coating composition is used as a variety of interior decoration sheets, and provides excellent scratch resistance and abrasion resistance. However, when the UV-curable coating composition is exposed to ultraviolet rays for a long period of time, yellowing occurs in the coating film, and thus the entire or part of the decor sheet is discolored.

In order to overcome this, there have been attempts to improve the yellowing resistance by using additives such as UV stabilizers, but there is a limit to improving the yellowing resistance due to the limitation of the color or amount of the additive itself.

As a background technology related to the present invention, there is Korean Patent Publication No. 10-0868149 (registered on November 4, 2008), and the document discloses an excellent yellowing-resistant and flame-retardant polycarbonate resin composition.

An object of the present invention is to provide a UV curable coating composition having excellent light resistance (yellowing resistance), and a decor sheet using the same.

Another object of the present invention is to provide a method of manufacturing the decor sheet.

The coating composition according to the present invention for achieving one of the above objects comprises: a urethane acrylate resin formed by polymerizing an isocyanate and a polyol including a chain structure by a polyurethane bond; Acrylate monomers; Photoinitiators; UV curable silicone additives; And a solvent; characterized in that it contains.

The acrylate monomer may include at least one of an acrylate monomer having a bifunctional group, an acrylate monomer having a trifunctional group, and an acrylate monomer having a tetrafunctional group.

The composition comprises 10 to 40% by weight of a urethane acrylate resin; 10 to 74% by weight of acrylate monomer; 1 to 10% by weight of a photoinitiator; 1 to 20% by weight of a silicone additive; And 5 to 20% by weight of a solvent.

The composition may further contain 1 to 10% by weight of a UV stabilizer.

The urethane acrylate resin may have a weight average molecular weight of 6000 to 10000.

The urethane acrylate resin may have a viscosity of 30000 to 500,000 cps.

The photoinitiator may be at least one selected from the group consisting of benzophenone-based, benzoin-ether-based, benzyl ketal-based, acetophenone-based, and anthraquinone-based.

The solvent may be at least one selected from the group consisting of ketone-based, amide-based, and halogenated alkyl-based solvents.

The decor sheet according to the present invention for achieving the above one object includes a base film comprising PETG (Polyethylene Terephthalate Glycol); And a coating layer formed on one surface of the base film and formed from a coating composition comprising a urethane acrylate resin, an acrylate monomer, a photoinitiator, an ultraviolet curable silicone additive, and a solvent.

The thickness of the coating layer is preferably 5 ~ 20㎛.

The manufacturing method of the decor sheet according to the present invention for achieving the above one object is a coating composition comprising a urethane acrylate resin, an acrylate monomer, a photoinitiator, an ultraviolet curable silicone additive and a solvent on a base film comprising PETG. After applying, drying to form a coating layer; And curing the coating layer using a UV curing machine, wherein the curing is performed in a nitrogen (N ₂ ) atmosphere.

It may further include a step of aging for 10 to 25 hours at 25 to 80 ℃ after the curing step.

The coating composition according to the present invention may impart yellowing resistance and hardness to a decor sheet by using a urethane acrylate resin formed by polymerizing an isocyanate and a polyol having a chain structure. In addition, it is possible to improve the light resistance of the initial appearance of the cured coating film by optimizing the mixing ratio of the urethane acrylate resin and the acrylate monomer for dilution in the coating composition.

1 is a cross-sectional view showing a decor sheet according to the present invention.
2 is a flow chart showing a method of manufacturing a decor sheet according to the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have it, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

Hereinafter, a UV curable coating composition having excellent yellowing resistance according to a preferred embodiment of the present invention, a decor sheet using the same, and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a decor sheet according to the present invention.

Referring to FIG. 1, the decor sheet includes a base film 120 including PETG; And a coating layer 110 comprising a coating composition.

The thickness of the coating layer is preferably 5 ~ 20㎛. When the thickness of the coating layer is less than 5 μm, the thickness is too thin, and the hardness of the entire coating film may be reduced. Conversely, when the thickness of the coating layer exceeds 20 μm, only the thickness may be increased without any further effect, and adhesion between the base film and the coating layer may decrease.

The coating composition used for the coating layer 110 includes a urethane acrylate resin formed by polymerizing isocyanate and polyol having a chain structure through a polyurethane bond; Acrylate monomers; Photoinitiators; UV curable silicone additives; And a solvent;

The urethane acrylate resin is formed by polymerizing a polyol and an isocyanate containing a chain structure (aliphatic) by a polyurethane bond.

The isocyanate includes an aliphatic isocyanate and an aromatic isocyanate, and in the present invention, it is preferable to include an aliphatic isocyanate that does not contain a double bond. Aromatic isocyanate has a problem that causes yellowing because the double bond structure is transferred by ultraviolet rays to form a quinone structure chromophore. The quinone-structured chromophore refers to a structure such as parabenzoquinone or quinone diimine type having a conjugate double bond.

Aliphatic isocyanates have a structure without double bonds and can provide yellowing resistance, and hexamethylene diisocyanate (HMDI), dimer acid diisocyanate, lysine disocyanate, and isophorone diisocyanate (Isophorone diisocyanate, IPDI), for example. In particular, it is preferable to use HMDI which imparts no yellowing in terms of weather resistance. Commercially available products include TSA-100, TSS-100, TSE-100, and TKA-100, but are not limited thereto.

As the polyol, acrylic polyol, polyolefin polyol, castor oil-based polyol, and the like may be used, and the polyol provides excellent reactivity control and moldability.

The urethane acrylate resin may include a bisphenol A (BPA) functional group having easy hardness control or an ethylene oxide (EO) functional group having excellent flexibility control. For example, the urethane acrylate resin of the present invention contains BPA, EO, and PTMG (polytetramethylene ether glycol) in the main chain, and UV curing such as 2-hydroxyethyl acrylate (2-HEA) at both ends of the main chain is It may contain possible functional groups.

When a urethane acrylate resin formed by polymerization of a polyurethane bond is used for the coating layer, the crosslinking density and hardness of the coating film can be increased, and excellent yellowing resistance can be obtained.

It is preferable that the urethane acrylate resin contains 10 to 40% by weight based on the total weight% of the composition.

When the addition amount of the resin is less than 10% by weight, the effect of hardness and yellowing resistance may be insufficient, and when the addition amount exceeds 40% by weight, the viscosity increases due to the addition of a large amount, so that not only the coating property but also the yellowing resistance effect is reduced. Can be.

The urethane acrylate resin may have a weight average molecular weight of 6000 to 10000.

When the weight average molecular weight is less than 6000, the flexibility and yellowing resistance of the urethane acrylate resin in the coating layer after curing cannot be exhibited. Conversely, when the weight average molecular weight exceeds 10000, the hardness may decrease.

The urethane acrylate resin may have a viscosity of 30000 to 500,000 cps. When the viscosity of the resin is less than 30000 cps, the viscosity is low and workability and productivity are lowered, and when the viscosity exceeds 50000 cps, the viscosity increases, so that not only workability but also adhesion between the coating layer and the sheet may be deteriorated.

The acrylate monomer may be used to dilute the resin, and may include at least one of an acrylate monomer having a bifunctional group, an acrylate monomer having a trifunctional group, and an acrylate monomer having a tetrafunctional group. .

For example, examples of the acrylate monomer including the bifunctional group include 1,6-hexanediol diacrylate (HDDA), polyethyleneglycol diacrylate (PEGDA), and the like. Examples of the acrylate monomers containing the tri- to 4-functional groups include pentaerytritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETA), and the like.

It is preferable that the monomer contains 10 to 74% by weight, based on the total weight% of the composition.

When the amount of the acrylate monomer added is less than 10% by weight, the viscosity may increase and the adhesion may decrease. Conversely, when the amount of addition exceeds 74% by weight, the UV curing time may be lengthened, resulting in a decrease in productivity.

The photoinitiator may be a conventional polymerization initiator that is active by ultraviolet rays, but may be selectively used in consideration of curability.

Examples of the polymerization initiator include compounds such as benzophenone, benzoin ether, benzyl ketal, acetophenone and anthraquinone, and these may be used alone or in combination.

The composition may contain 1 to 10% by weight of a photoinitiator based on the total weight% of the composition. When the amount of the photoinitiator is less than 1% by weight, the curing time may increase during the UV curing process, resulting in decreased productivity or wrinkles on the surface of the cured coating film. If it exceeds 10% by weight, storage stability of the coating layer and adhesion between the base film and the coating layer may be deteriorated.

The silicone additive can improve the leveling property of the surface of the coating layer, and examples include liquid type polydimethylsiloxane (PDMS), acrylic silicone, and the like. When the additive is added in an amount of less than 1% by weight based on the total weight% of the composition, the effect of addition is insufficient. Conversely, when it exceeds 20% by weight, the curing time in the curing step is lengthened and physical properties may be deteriorated.

The solvent may be used for viscosity control, and it is preferable to add 5 to 20% by weight based on the total weight% of the composition.

The solvent may be at least one selected from the group consisting of ketone, amide, and halogenated alkyl.

Examples of ketone solvents include methyl ethyl ketone, acetone, and methyl isobutyl ketone, and it is preferable to use methyl ethyl ketone, acetone, and isophorone in consideration of effects such as excellent UV curing properties and yellowing resistance.

Examples of the amide solvent include aliphatic amide solvents such as dimethylformamide and N,N-dimethylacetamide, or alicyclic amide solvents such as N-methyl-2-pyrrolidone, and have the effect of yellowing resistance. Considering it is preferable to use dimethylformamide.

As the halogenated alkyl-based solvent, there are organic solvents such as fluorine-based, chlorine-based, and bromine-based, and in consideration of excellent ultraviolet curing properties, it is preferable to use a chlorine-based organic solvent.

The composition may further contain 1 to 10% by weight of a UV stabilizer.

The UV stabilizer serves to supplement the yellowing resistance effect of the coating layer. When the coating layer is exposed to light for a long time, the UV stabilizer absorbs the ultraviolet region and prevents yellowing. As UV stabilizers, benzotriazole, triazine, etc. may be used, and HALS stabilizing free radicals, which are the main causes of yellowing, may be mixed and used. When the UV stabilizer is added in less than 1% by weight based on the total weight% of the composition, the effect of addition is insufficient. Conversely, when it exceeds 10% by weight, the curing time in the curing step is lengthened and physical properties may be deteriorated.

The manufacturing method of the decor sheet according to the present invention includes a coating layer forming step (S210) and a coating layer curing step (S220).

First, in the coating layer forming step (S210), after the coating composition is applied on a base film including PETG, it may be dried at 40 to 60° C. for 1 to 2 minutes.

As described above, the coating composition may include a urethane acrylate resin, an acrylate monomer, a photo initiator, an ultraviolet curable silicone additive, and a solvent. The coating layer may be formed by adjusting the thickness of the coating layer using Mayer bars having different wire sizes, and may be formed by gravure coating or slot die coating.

Next, in the coating layer curing step (S220), the coating layer may be cured by irradiating ultraviolet rays of 300 to 500 mJ/cm ² using a UV curing machine. In the curing step, in order to remove oxygen, it may be performed in a nitrogen (N ₂ ) gas atmosphere, which is an inert gas having low reactivity.

The decor sheet may further include a step of aging for 10 to 25 hours at 25 to 80° C. after the curing step (S220) in consideration of the properties of physical properties.

The aging step is a step for increasing the surface strength of the coating layer and stabilizing the properties of physical properties. The aging is preferably carried out at 25 ~ 80 ℃. If it is less than 25°C, the effect is insufficient due to low temperature, and if it exceeds 80°C, cracks may occur due to high temperature.

As described above, the coating composition according to the present invention can provide light resistance and hardness of the initial appearance by optimizing the mixing ratio of the urethane acrylate resin and the acrylate monomer for dilution without adding a separate filler.

As described above, specific examples of the UV-curable coating composition having excellent yellowing resistance, a decor sheet using the same, and a method of manufacturing the same are as follows.

1. Preparation of Deco Sheet Specimen

[Table 1]

Example 1

A coating composition was prepared by uniformly mixing 6.7% by weight of dimethylformamide as a solvent in the composition of [Table 1].

The manufacturing process of the urethane acrylate resin is as follows.

-A molten polyol was added to a reaction vessel at approximately 40° C. and stirred, and a predetermined amount of aliphatic isocyanate HMDI was added while paying attention to heat generation. Next, after raising the temperature to about 10° C., the mixture was stirred for 30 minutes to prepare a urethane acrylate resin.

Thereafter, as shown in FIG. 1, the prepared coating composition was applied to one surface of the base film in a Meyer bar method, dried at 50° C. for 1 minute, and then a 15 μm-thick coating layer was formed.

Thereafter, the coating layer was cured by irradiating UV of 400 mJ/cm ² on the coating layer in a nitrogen atmosphere, and then aged at 60° C. for about 20 hours to prepare a decorative sheet.

Example 2

A deco sheet was prepared under the same conditions as in Example 1, except that the coating composition was mixed and used as shown in Table 1 and the UV stabilizer contained 5% by weight.

Comparative Example 1

A deco sheet was manufactured under the same conditions as in Example 1, except that the coating composition was mixed and used as shown in [Table 1].

Comparative Example 2

A deco sheet was manufactured under the same conditions as in Example 1, except that the coating composition was mixed and used as shown in [Table 1].

Comparative Example 3

The coating composition was mixed and used as shown in [Table 1], and a decor sheet was manufactured under the same conditions as in Example 1, except that the curing was performed in an oxygen atmosphere.

2. Physical property evaluation method and results

The following physical properties were evaluated for the decor sheets of Examples 1 to 2 and Comparative Examples 1 to 3, and the results are shown in [Table 2].

1) Initial appearance (color)

Minolta CM-5 (△b ^* ) was evaluated, the color change during coating was based on △b ^* <0.25.

2) yellowing

It was evaluated with QUV (351 lamp, 408h, ΔE) & Minolta CM-5, and the overall color change was observed by exposure to UV light of 351 nm wavelength for 400 hours. ΔE=1.2 was used as a standard.

3) adhesion

It was measured according to ASTM D 3002, 3559 standards. Specifically, cut the coated surface to 100×100 using the BYK Cross Cut Tester. After attaching Permacel tape to the grid-shaped coating surface, observe the surface condition after removing. It is measured by counting the number of remaining cells out of 100 cells.

4) hardness

(ISO 4586-2) The hardness of the coating layer surface was measured using an Erichsen scratch tester.

[Table 2]

In the case of Examples 1 to 2, by mixing the acrylate monomer and the urethane acrylate resin in an optimal ratio, excellent results were obtained in all of the yellowing resistance, adhesion, hardness, and the like. In particular, Example 2 containing a UV stabilizer has better yellowing resistance than Example 1.

In Comparative Examples 1 and 2, since the content of the resin was out of the reference value, results were relatively poor in hardness and the like. In Comparative Example 1, the viscosity of the entire composition was increased due to the addition amount of 64.4% resin, resulting in deterioration in flowability, and difficulty in handling the coating solution. In Comparative Example 3, as hardening was performed in an oxygen atmosphere instead of a nitrogen atmosphere, yellowing of the decor sheet occurred, and the hardness value was low.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above embodiments, but may be manufactured in various different forms, and those having ordinary knowledge in the technical field to which the present invention pertains. It will be understood that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.

110: coating layer
120: base film
S210: coating layer formation step
S220: coating layer curing step

Claims (12)

10 to 40% by weight of a urethane acrylate resin formed by polymerizing an isocyanate and a polyol containing a chain structure by a polyurethane bond;
10 to 74% by weight of an acrylate monomer for diluting the urethane acrylate resin;
1 to 10% by weight of a photoinitiator;
1 to 20% by weight of an ultraviolet curable silicone additive; And
Including 5 to 20% by weight of a solvent containing at least one of aliphatic amide solvent, alicyclic amide solvent, fluorine solvent, chlorine solvent, and bromine solvent,
Further comprising 1 to 10% by weight of a UV stabilizer containing at least one of benzotriazole, triazine, HALS,
The urethane acrylate resin has a weight average molecular weight of 6000 to 10000 and a viscosity of 30000 to 500,000 cps,
The acrylate monomer is a coating composition comprising an acrylate monomer having a bifunctional group, an acrylate monomer having a trifunctional group, and an acrylate monomer having a tetrafunctional group.
delete delete delete delete delete The method of claim 1,
The photoinitiator is a coating composition, characterized in that at least one selected from the group consisting of benzophenone-based, benzoin ether-based, benzyl ketal-based, acetophenone-based, and anthraquinone-based.
delete A base film containing PETG (Polyethylene Terephthalate Glycol); And
Includes; a coating layer formed on one side of the base film and formed from a coating composition,
The coating composition includes 10 to 40% by weight of a urethane acrylate resin, 10 to 74% by weight of an acrylate monomer for diluting the urethane acrylate resin, 1 to 10% by weight of a photoinitiator, 1 to 20% by weight of an ultraviolet curable silicone additive, and Including 5 to 20% by weight of a solvent, further comprising 1 to 10% by weight of a UV stabilizer,
The solvent includes at least one of an aliphatic amide solvent, an alicyclic amide solvent, a fluorine solvent, a chlorine solvent, and a bromine solvent,
The UV stabilizer includes at least one of benzotriazole, triazine, and HALS,
The urethane acrylate resin has a weight average molecular weight of 6000 to 10000 and a viscosity of 30000 to 500,000 cps,
The acrylate monomer is a decor sheet comprising an acrylate monomer having a bifunctional group, an acrylate monomer having a trifunctional group, and an acrylate monomer having a tetrafunctional group.
The method of claim 9,
Deco sheet, characterized in that the thickness of the coating layer is 5 ~ 20㎛.
After applying the coating composition on the base film containing PETG, drying to form a coating layer; And
Curing the coating layer using a UV curing machine; Including,
The coating composition includes 10 to 40% by weight of a urethane acrylate resin, 10 to 74% by weight of an acrylate monomer for diluting the urethane acrylate resin, 1 to 10% by weight of a photoinitiator, 1 to 20% by weight of an ultraviolet curable silicone additive, and Including 5 to 20% by weight of a solvent, and further comprising 1 to 10% by weight of a UV stabilizer,
The solvent includes at least one of an aliphatic amide solvent, an alicyclic amide solvent, a fluorine solvent, a chlorine solvent, and a bromine solvent,
The UV stabilizer includes at least one of benzotriazole, triazine, and HALS,
The urethane acrylate resin has a weight average molecular weight of 6000 to 10000 and a viscosity of 30000 to 500,000 cps,
The acrylate monomer includes an acrylate monomer having a bifunctional group, an acrylate monomer having a trifunctional group, and an acrylate monomer having a tetrafunctional group,
The curing is performed in a nitrogen (N ₂ ) atmosphere,
After the curing step, the step of aging for 10 to 25 hours at 25 to 80 ℃; Method for producing a decorative sheet, characterized in that it further comprises.

delete

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