KR20170105664A - 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 with excellent yellowing resistance. The coating composition according to the present invention comprises: a urethane acrylate resin formed by polymerizing an isocyanate having a chained structure and a polyol in combination with a polyurethane; an acrylate monomer; a photoinitiator; an ultraviolet curable silicone additive; and a solvent.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a UV curable coating composition which is excellent in yellowing resistance, a decorative sheet using the UV curable coating composition,

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

UV curable coating compositions are used in a variety of interior decor sheet and provide excellent scratch resistance and abrasion resistance. However, when the UV curable coating composition is exposed to ultraviolet rays for a long period of time, a yellowing phenomenon occurs in the coating film, so that the entire or part of the decor sheet is discolored.

To overcome this problem, attempts have been made to improve the yellowing resistance by using additives such as UV stabilizers. However, there is a limit to improve the yellowing resistance due to the limit of the additive itself or the amount of the additive.

A background art related to the present invention is Korean Registered Patent No. 10-0868149 (registered on November 4, 2008), which discloses an excellent vulcanized and flame-retardant polycarbonate resin composition.

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

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

In order to accomplish the above object, a coating composition according to the present invention comprises a urethane acrylate resin formed by polymerizing an isocyanate and a polyol having a chain structure with a polyurethane bond; Acrylate monomers; Photoinitiators; An ultraviolet curable silicone additive; And a solvent.

The acrylate monomer may include at least one of an acrylate monomer having two functional groups, an acrylate monomer having three functional groups and an acrylate monomer having four functional groups.

Said composition comprising 10 to 40% by weight of a urethane acrylate resin; 10 to 74% by weight of an 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 comprise 1 to 10% by weight of a UV stabilizer.

The urethane acrylate resin may have a weight average molecular weight of 6,000 to 10,000.

The urethane acrylate resin may have a viscosity of 30000 to 50000 cps.

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

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

According to an aspect of the present invention, there is provided a decorative sheet comprising: 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 to 20 占 퐉.

In order to accomplish the above object, the present invention provides a method for producing a decorative sheet, which comprises applying a coating composition comprising a urethane acrylate resin, an acrylate monomer, a photoinitiator, an ultraviolet curable silicone additive and a solvent onto a base film comprising PETG Coating and 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.

Aging the cured product at 25 to 80 ° C for 10 to 25 hours after the curing step.

The coating composition according to the present invention can impart decolorization resistance and hardness to a decor sheet by using a urethane acrylate resin formed by polymerizing an isocyanate containing a chain structure with a polyol. In addition, it is possible to improve the light fastness of the initial appearance of the cured coating film by optimizing the mixing ratio of the urethane acrylate resin and the diluting acrylate monomer to the coating composition.

1 is a sectional view showing a decor sheet according to the present invention.
2 is a flowchart showing a method of manufacturing a decor sheet according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a UV-curable coating composition having excellent yellowing resistance according to a preferred embodiment of the present invention, a decorative sheet using the same, and a method for producing the same will be described in detail with reference to the accompanying drawings.

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

Referring to Figure 1, the decor sheet comprises a substrate film 120 comprising PETG; And a coating layer 110 comprising a coating composition.

The thickness of the coating layer is preferably 5 to 20 占 퐉. When the thickness of the coating layer is less than 5 mu m, the thickness is too thin, and the hardness of the entire coating film may be lowered. Conversely, when the thickness of the coating layer exceeds 20 占 퐉, the thickness can be increased only without further effect, and the adhesion force between the base film and the coating layer may be lowered.

The coating composition used for the coating layer 110 may include a urethane acrylate resin formed by polymerizing an isocyanate and a polyol having a chain structure with a polyurethane bond; Acrylate monomers; Photoinitiators; An ultraviolet curable silicone additive; And a solvent.

Urethane acrylate resins are formed by polymerizing an isocyanate (isocynate) containing a polyol and a chain-like structure (aliphatic) with a polyurethane bond.

The isocyanate includes an aliphatic isocyanate and an aromatic isocyanate. In the present invention, it is preferable to include an aliphatic isocyanate having no double bond. The aromatic isocyanate has a problem of causing yellowing because the double bond structure is transferred by ultraviolet rays to form quinone structure chromophore. The quinone structure chromophore means a structure such as a parabenquoquinone having a conjugate double bond, a quinone diimine type, and the like.

The aliphatic isocyanate may have a structure without a double bond and may impart a vulcanization resistance and may be selected from hexamethylene diisocyanate (HMDI), dimer acid disocyanate, lysine disocyanate, isophorone diisocyanate (Isophorone diisocyanate, IPDI). In particular, it is preferable to use HMDI which imparts non-yellowing resistance in terms of weatherability. Commercially available products include, but are not limited to, TSA-100, TSS-100, TSE-100, and TKA-100.

The polyol may be an acrylic polyol, a polyolefin polyol, a castor oil based polyol or the like, and the polyol provides excellent reactivity control and moldability.

The urethane acrylate resin may include a bisphenol A (BPA) functional group which is easy to control hardness or an EO (ethylene oxide) functional group which is excellent in 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) And may contain possible functional groups.

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

The urethane acrylate resin preferably comprises 10 to 40% by weight based on the total weight% of the composition.

If the addition amount of the resin is less than 10 wt%, the effect of hardness and yellowing resistance may be insufficient. When the addition amount exceeds 40 wt%, the viscosity increases due to the addition of a large amount, .

The urethane acrylate resin may have a weight average molecular weight of 6,000 to 10,000.

When the weight average molecular weight is less than 6,000, flexibility and vulcanization resistance of the urethane acrylate resin in the coating layer after curing can not be exerted. Conversely, when the weight average molecular weight exceeds 10,000, the hardness may be lowered.

The urethane acrylate resin may have a viscosity of 30000 to 50000 cps. When the viscosity of the resin is less than 30,000 cps, the viscosity and the workability and productivity are lowered. When the viscosity exceeds 50000 cps, the viscosity of the resin is increased, so that not only the workability but also the adhesion between the coating layer and the sheet may be deteriorated.

The acrylate monomer may be used for diluting the resin, and may include at least one of an acrylate monomer having two functional groups, an acrylate monomer having three functional groups and an acrylate monomer having four functional groups .

For example, the acrylate monomer containing the bifunctional group includes 1,6-hexanediol diacrylate (HDDA), polyethyleneglycol diacrylate (PEGDA), and the like. Examples of the acrylate monomer having 3 to 4 functional groups include pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA) and pentaerythritol tetraacrylate (PETA).

The monomer preferably comprises 10 to 74% by weight based on the total weight% of the composition.

If the addition amount of the acrylate monomer is less than 10% by weight, the viscosity may be increased and the adhesion may be lowered. On the other hand, if the addition amount exceeds 74% by weight, the UV curing time may be prolonged and the productivity may be lowered.

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

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

The composition may comprise from 1 to 10% by weight of a photoinitiator, based on the total weight percent of the composition. If the addition amount of the photoinitiator is less than 1% by weight, the curing time may be increased during the UV curing process, resulting in lower productivity or wrinkles on the surface of the cured coating film. If it exceeds 10% by weight, the storage stability of the coating layer and the adhesion of 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 thereof 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 the addition is insufficient. On the other hand, if it exceeds 20% by weight, the curing time in the curing step becomes longer and the physical properties may be lowered.

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 one or more selected from the group consisting of ketone-based, amide-based, and halogenated alkyl-based solvents.

Examples of the ketone-based solvent include methyl ethyl ketone, acetone, methyl isobutyl ketone and the like, and methyl ethyl ketone, acetone, and isophorone are preferably used in consideration of the effects of excellent ultraviolet curing property and vulcanization resistance.

Examples of the amide-based solvent include aliphatic amide solvents such as dimethylformamide and N, N-dimethylacetamide, and alicyclic amide solvents such as N-methyl-2-pyrrolidone. 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 ones. It is preferable to use a chlorine-based organic solvent in consideration of excellent ultraviolet curing properties.

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

The UV stabilizer plays a role in supplementing the anti-yellowing effect of the coating layer. When the coating layer is exposed to light for a long time, the UV stabilizer absorbs ultraviolet light to prevent yellowing. As the UV stabilizer, benzotriazole, triazine and the like may be used, and HALS stabilizing free radical which is a main cause of yellowing can be mixed and used. When the UV stabilizer is added in an amount of less than 1% by weight based on the total weight% of the composition, the effect of the addition is insufficient. On the other hand, if it exceeds 10% by weight, the curing time in the curing step becomes long, and the physical properties may be lowered.

The method for manufacturing a 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), the coating composition may be coated on a base film containing PETG, followed by drying at 40 to 60 ° C for 1 to 2 minutes.

The coating composition may comprise a urethane acrylate resin, an acrylate monomer, a photoinitiator, an ultraviolet curable silicone additive, and a solvent, as described above. The coating layer may be formed by controlling the thickness of the coating layer using a Mayer bar having a different wire size, and may be formed by a gravure coating method or a slot die coating method.

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

The decor sheet may further include aging at 25 to 80 DEG C for 10 to 25 hours after the curing step (S220), taking into account the properties of the material.

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

As described above, the coating composition according to the present invention can optimize the blending ratio of the urethane acrylate resin and the diluting acrylate monomer to impart lightfastness and hardness of the initial appearance without adding a separate filler.

The UV-curable coating composition having excellent yellowing resistance as described above, the decorative sheet using the same, and the method for producing the same are described below.

1. Preparation of Deco Sheet Sample

[Table 1]

Example 1

6.7% by weight of dimethylformamide as a solvent was uniformly mixed with the composition of Table 1 to prepare a coating composition.

The process for producing the urethane acrylate resin is as follows.

- A polyol in a molten state was charged into a reaction vessel at about 40 ° C and stirred, and a predetermined amount of HMDI, which is an aliphatic isocyanate, was added while paying attention to heat generation. Next, the temperature was raised by about 10 캜, and the mixture was stirred for 30 minutes to prepare a urethane acrylate resin.

Then, as shown in FIG. 1, the prepared coating composition was coated on one side of the base film by a Meyer bar method and dried at 50 ° C. for 1 minute to form a coating layer having a thickness of 15 μm.

Thereafter, the coating layer was irradiated with UV at 400 mJ / cm ² in a nitrogen atmosphere to cure the coating layer, followed by aging at 60 ° C for about 20 hours to prepare a deco sheet.

Example 2

The coating composition was prepared in the same manner as in Example 1, except that 5% by weight of the UV stabilizer was used in combination with [Table 1].

Comparative Example 1

A decorative sheet was prepared under the same conditions as in Example 1, except that the coating composition was used as shown in [Table 1].

Comparative Example 2

A decorative sheet was prepared under the same conditions as in Example 1, except that the coating composition was used as shown in [Table 1].

Comparative Example 3

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

2. Property evaluation method and result

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

1) Initial appearance (color)

Minolta CM-5 (Δb ^* ), and the color change upon coating was based on Δb ^* <0.25.

2) Sulfur degeneration

The evaluation was performed with QUV (351 lamp, 408h, DELTA E) & Minolta CM-5, and exposure to UV light having a wavelength of 351 nm for 400 hours to observe the overall color change. And ΔE = 1.2.

3) Adhesiveness

ASTM D 3002, 3559 measurement standard. Specifically, cut the coated surface with 100 × 100 using BYK Cross Cut Tester. Attach the permacel tape to the grid-like coated surface and observe the surface condition after removal. Count the number of cells remaining among 100 cells.

4) Hardness

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

[Table 1]

In the case of Examples 1 and 2, excellent results were obtained in all of the vulcanization resistance, adhesion, hardness and the like by blending the acrylate monomer and the urethane acrylate resin at an optimum ratio. In particular, Example 2 containing a UV stabilizer is superior in vulcanization resistance to Example 1.

In Comparative Examples 1 and 2, since the content of the resin was out of the standard value, the result was relatively poor in hardness and the like. In Comparative Example 1, the addition amount of the 64.4% resin increased the viscosity of the entire composition, which deteriorated the flowability and made it difficult to treat the coating liquid. In Comparative Example 3, yellowing of the decorative sheet occurred and the numerical value of hardness was low in that the curing was performed in an oxygen atmosphere instead of a nitrogen atmosphere.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

110: Coating layer
120: substrate film
S210: Coating layer formation step
S220: coating layer curing step

Claims (12)

A urethane acrylate resin formed by polymerizing an isocyanate and a polyol having a chain structure with a polyurethane bond;
Acrylate monomers;
Photoinitiators;
An ultraviolet curable silicone additive; And
&Lt; / RTI &gt; and a solvent.
The method according to claim 1,
Wherein the acrylate monomer comprises 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 method according to claim 1,
Said composition comprising 10 to 40% by weight of a urethane acrylate resin; 10 to 74% by weight of an 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 method of claim 3,
Wherein said composition further comprises 1 to 10% by weight of a UV stabilizer.
The method according to claim 1,
Wherein the urethane acrylate resin has a weight average molecular weight of 6,000 to 10,000.
The method according to claim 1,
Wherein the urethane acrylate resin has a viscosity of 30,000 to 50,000 cps.
The method according to claim 1,
Wherein the photoinitiator is at least one selected from the group consisting of benzophenone, benzoin ether, benzyl ketal, acetophenone, and anthraquinone.
The method according to claim 1,
Wherein the solvent is at least one selected from the group consisting of ketone-based, amide-based, and halogenated alkyl-based solvents.
A base film comprising PETG (Polyethylene Terephthalate Glycol); And
A coating layer formed on one side of the substrate 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.
10. The method of claim 9,
Wherein the thickness of the coating layer is 5 to 20 占 퐉.
Applying a coating composition comprising a urethane acrylate resin, an acrylate monomer, a photoinitiator, an ultraviolet curable silicone additive, and a solvent onto a base film comprising PETG, followed by drying to form a coating layer; And
And curing the coating layer using a UV curing machine,
The curing method of producing a decor sheet, characterized in that is carried out in a nitrogen (N ₂₎ atmosphere.
12. The method of claim 11,
Aging the mixture at 25 to 80 DEG C for 10 to 25 hours after the curing step.

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