KR100447935B1 - Water based Components for Over Printing Varnish - Google Patents

Abstract

The present invention relates to an aqueous OPV (Over Printing Varnish) coating composition, and more particularly, to include a water-disperse copolymer polyester, acrylic copolymer, styrene copolymer, water-disperse glycidyl methacrylate copolymer, The present invention relates to an aqueous OPV coating composition exhibiting excellent coating properties and adhesion on paper, and excellent surface gloss, heat resistance, moisture permeability, and blocking resistance.

Description

Water based Components for Over Printing Varnish

The present invention relates to an aqueous OPV (Over Printing Varnish) coating composition, and more particularly, to include a water-disperse copolymer polyester, acrylic copolymer, styrene copolymer, water-disperse glycidyl methacrylate copolymer, The present invention relates to an aqueous OPV coating composition exhibiting excellent coating properties and adhesion on paper, and excellent surface gloss, heat resistance, moisture permeability, and blocking resistance.

Packaging refers to the technology and construction of suitable materials or containers on the goods in order to protect their value and condition in the transport and storage of the goods, and to the protection, integrity and convenience. Selecting and using appropriate packaging materials is necessary because it requires sales promotion, information and commu- nication, and environmentally-friendly.

Among these packaging materials, OPV is coated on the outer surface of various containers using paper, and is widely used for packaging of industrial products, cosmetics, or food. In particular, OPV used in food packaging containers should consist of ingredients that do not harm the human body.

Conventional techniques related to barrier coating or over coating compositions used in the packaging industry are as follows.

U.S. Patent No. 4,129,547 cures urea formaldehyde and low molecular weight polyhydric alcohols, and uses water-soluble emulsions of polyamides, polystyrenes, polyesters, and polyvinylidene as in U.S. Patent No. 4,804,573, for example using water-soluble polymers. Cold seals were performed, and US Pat. Nos. 5,008,144 and 5,035,946 used a varnish of water soluble polyethylene oxide. There is also a mixture of alkyl acrylate monomers acting as plasticizers, curing agents and water-soluble acrylic acids, as in US Pat. No. 5,616,364, and oxazolines or oxazines as in US Pat. Nos. 6,663,885 and 6,084,023. There is a composition using the contained methacrylate and UV curable overprinting composition which is 100% solids as in US Pat. No. 6,096,384. The coating and coating on the outer surface of the packaging container provides functional beauty and protects the contents. Emphasis was placed on non-stick properties.

As mentioned above, OPV is generally divided into oil-based using a polar organic solvent as a solvent, water-based aqueous and UV-curable 100% solids.

The conventional OPV coating composition using polystyrene or vinyl acetate uses a polar organic solvent such as toluene as a solvent, so that the organic solvent evaporates during the work, causing a change in viscosity resulting in uneven coating, and the working environment is exposed to a polar organic solvent. When the polar organic solvent is used in the packaging material, the health of the worker is impaired, and the residual solvent which may harm the human body is absorbed by the human body, thereby deteriorating the health. In contrast, aqueous OPV has several advantages over other types of OPV in terms of conservation of the environment, resource saving, improvement of working environment, and safety hygiene. Poor coating workability is poor, and water with a large latent heat of evaporation is difficult to volatilize, and thus flow is easily generated during drying. In addition, there is a problem that the water resistance is insufficient because the influence on the moisture in the atmosphere after the film is formed.

As a water-resistant complementary technique of the OPV composition using a conventional polyester, there is an example of curing polyester and melamine made by using less than 30% volatile solvent and polyhydric alcohol in US Patent No. 4,040,995. In US Pat. No. 4,054,614, there is an example where the side chain hydroxy group is cured with phthalic hydride after reacting pentaerythrol, a polyhydric alcohol, with an acid, thereby improving chemical resistance, hardness, and flexibility. In addition, in US Pat. No. 4,181,638, there is an example of forming a coating film by curing with a thermosetting agent using a polyester having a hydroxyl group in the side chain. However, the above patents have a problem in forming a film that is too strong according to the curing conditions to be used in a flexible substrate.

Accordingly, the present inventors have developed an aqueous OPV coating composition excellent in high gloss and water resistance by improving the above problems.

In particular, OPV required for food packaging is important for safety and hygiene. When used as food packaging bags and snack packaging materials, it does not harm any human body by removing residual solvents that are harmful to humans. Therefore, polar organic solvents such as toluene are released during coating. It should be removed to improve the working environment and have good wettability and dryness for the cardboard. It is also intended to meet the following performance required as an overprinting coating composition.

① Good coating workability, there should be no pinhole, brushing, catering, misting thread, etc., and there should be little viscosity increase during coating.

② It should be dry and have no blocking.

③ Good adhesion to the material (paper), so there should be no scratches, cracks or falling off during the process.

④ Do not bleed or discolor the ink, or create blemishes, separations, embossing, etc.

⑤ When used for food packaging, it should not give smell to foreign food or impair the taste of food.

⑥ The coated film should have less yellowing and gloss.

⑦ The storage stability of the coating composition should be good.

⑧ It must be economical.

In order to satisfy the above properties, water-disperse copolyester having excellent film forming ability is used, and an acrylic copolymer and styrene copolymer in the form of emulsion are added thereto to provide excellent coating property and adhesion on the substrate paper, and also wear resistance, The present invention has been completed by developing a composition having excellent surface gloss, heat resistance, durability, weather resistance, and the like.

Accordingly, an object of the present invention is to provide an aqueous OPV coating composition having excellent high gloss and water resistance composed of a water-dispersed copolymer, an acrylic copolymer, a styrene copolymer, and a water-soluble glycidyl methacrylate copolymer.

The present invention features an aqueous OPV coating composition composed of a water-disperse copolyester, an acrylic copolymer, a styrene copolymer, and a water-disperse glycidyl methacrylate copolymer.

Referring to the present invention in more detail as follows.

In order to achieve the object of the present invention as described above, a water-dispersed polyester is used as a binder of an aqueous composition which can maintain a suitable viscosity for coating and can maintain good coatability and gloss and water resistance after coating. The general thermoplastic polyester starts with stretching the polyethylene terephthalate (PET) film produced by the polycondensation reaction of a divalent or higher alcohol and a divalent or higher carboxylic acid, and shows its strength. The biaxially stretched film has transparency and impact. It has been widely used as a representative packaging film with excellent bending and dimensional stability, and the demand for PET bottles for drinking water is expanding. However, in the case of unstretched, there is a problem in moldability, impact resistance, and heat resistance, so that the present invention uses a blend of an acrylic copolymer and a styrene copolymer in the form of an aqueous dispersion or an emulsion to compensate for this.

The water dispersion copolymer polyester used for this invention has a structure as follows.

In Formula 1, M is a group derived from a neutralizing agent, x, y, m and n represent the composition ratio of each monomer, x and y are each in the range of 0.1 to 0.6, m + n = 1 .

The aqueous dispersion can be made in the form of a water-soluble or semi-soluble semi-dispersed solution using a neutralizing agent and water after most of them dissolve the resin synthesized using a water-soluble solvent as a solvent. When a large amount of hydrophilic groups are present in the polymer skeleton, the water resistance of the dry coating becomes very weak. Therefore, the water-dispersed copolyester of the present invention is a low molecular weight basic neutralizing agent, which greatly improves the dissociation polarity of the hydrophilic ions, thereby making it a relatively small amount of hydrophilic group. Solubilization is possible and the neutralizing agent is evaporated in the film formation process to form a film with excellent water resistance. Metal salts such as lithium, potassium, sodium and the like can also be used as neutralizing agents, but remain dry in the film even after drying, making the water resistance very weak. Accordingly, the low molecular weight basic neutralizers include ammonia, morpholine, dimethylamine, dimethyl ethylamine, triethylamine, N, N-dimethylamino ethanol, 2-amino-2-methyl propanol, monoethanol amine, diethanol amine , Diethylmethanol amine and triethanol amine are used to neutralize the water dispersion copolymer polyester. After blending the water-dispersed copolymer polyester having the molecular weight of 5,000 to 8,000 with the above structure of 10,000 to 15,000 in a predetermined ratio, and mixing and coating with the selected emulsion-type acrylic copolymer and styrene copolymer, it is dried and calendered. It is possible to form a film having good light.

In addition, in order to complement the physical properties of the water-dispersed copolymer polyester of the present invention, a good compatibility with the water-dispersed copolymer polyester is an acrylic copolymer, acrylonitrile, methyl methacrylate, ethyl having an appropriate molecular weight Emulsion-based homopolymers or copolymers based on methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate and butyl acrylate can be variously applied. The acrylic polymer homopolymer physical properties used in the present invention are summarized in Table 1 below.

The physical properties according to the molecular weight of the acrylic copolymer used for aqueousization were as shown in Table 2 below.

The acrylic copolymer used in the present invention can be represented by the following formula (2). At this time, the content of the acrylic copolymer used should be at least the minimum amount of blending well without phase separation with the water-dispersed copolymer polyester, it is preferable to use 1 to 45 parts by weight based on 100 parts by weight of the solid content of the water-dispersed copolymer polyester.

In Formula 2, R and R 'is a hydrogen atom or CH ₃ , R "is a hydrogen atom, CH ₂ CH ₃ or (CH ₂ ) ₃ CH _3dlrh , m, n represents the composition ratio of each monomer m + n = 1

As the styrene copolymer used in the present invention, α-methyl styrene and styrene-based emulsion-type homopolymers or copolymers can be used. In this case, since the content of the styrene copolymer should be at least the minimum amount that is well blended without phase separation with the water-dispersed copolymer, 1 to 45 parts by weight is preferable with respect to 100 parts by weight of the solid content of the water-dispersed copolymer.

In order to obtain better gloss, the aqueous OPV is coated and then calendered as necessary. Calendering is a means mainly applied for the purpose of improving the surface quality by improving not only the uniformity of thickness but also the smoothness and gloss of the surface. Although calendaring improves coating surface properties such as smoothness and gloss, optical properties such as transparency and stiffness and some strength properties may be worsened depending on the conditions. Therefore, during hot calendering, the coating layer should be fused to form a leveling, so that the adhesion to the cardboard should be excellent, and the film against heat fusion should not age or stick to the calendering plate. For good release force without tacky against hot calender surfaces, the coating of the aqueous overcoating layer must be strengthened. To this end, a water-dispersible glycidyl methacrylate copolymer represented by the following formula (3) is a material having a crosslinkable functional group capable of forming a partially interpenetrating polymer network structure between the water-dispersible copolymer polyester and the acrylic copolymer. When used, interpenetrating network structures can be created to compensate for the heat resistance of the coated surface.

In Formula 3, m and n represent the composition ratio of each monomer, m + n = 1, n is in the range of 0.1 to 0.2.

At this time, the content of the water-soluble epoxy resin used should be more than the minimum amount to prevent the coating surface from sticking due to the calendering roll heat. Therefore, excessive use of the water-soluble epoxy resin degrades the flexibility of the film, causing cracks and deteriorating physical properties. 1-35 weight part is preferable with respect to 100 weight part of solid content of a dispersion copolymer polyester.

In addition to such compositions, alcohols, waxes and the like can be used as additives.

Environmental issues and workability Ethanol, isopropyl alcohol, butanol, ethylene glycol, isopropyl glycol, ethyl glycol, butyl glycol, propylene glycol, 1-methoxy-2-propanol, 1 Alcohol solvents such as ethoxy-2propanol, 1-propoxy-2-propanol, and 1-butoxy-2-propanol within 3 to 10 parts by weight based on 100 parts by weight of solids of the water-dispersed copolyester. Can be used.

In addition, waxes may be used to increase release and water resistance to the surface. Waxes are broadly classified into natural waxes, synthetic waxes and compounded waxes. Wax is a flexible and glossy material. It is a solid or semi-solid polymer organic compound. It is classified into ester wax and hydrocarbon wax in chemical composition. Copper and plant waxes contain fatty acid esters of higher monohydric or dihydric alcohols that are insoluble in water. These waxes are more stable than fats and are less likely to hydrolyze and do not erode to oxygen or bacteria in the air. These properties cover the surface of copper and plants to inhibit evaporation of water and to insulate them. Most waxes contain the air absorbed during cooling, but if the amount of air in the wax is large, turbidity occurs, mechanical strength is lowered, oxidation occurs, smells, or causes coloration. Due to its poor properties, the emulsion particles are re-agglomerated, so that they do not change into particles larger than the coating thickness and make the coating surface rough. It provides water resistance and increases gloss. At this time, it is preferable to use 1-5 weight part of wax content with respect to 100 weight part of solid content of water-dispersion copolymer polyester.

On the other hand, during surface defects of the coating surface, the surface to be coated has foreign substances such as water, oil, silicone, etc., resulting in cratering (a phenomenon in which irregularities such as craters are formed on the coated surface), fisheye, pinhole, and orange peel phenomenon. It is preferable to use 1 to 3 parts by weight of the mixture of the surfactant with respect to 100 parts by weight of the solids of the water-dispersed copolyester in order to remove or reduce the viscosity and to promote excellent gloss and smoothness of the high coating surface.

Hereinafter, the present invention will be described in detail based on the following examples, but the present invention is not limited thereto.

Example 1

The following composition was coated on a basis weight 350 g / m ² cardboard using a bar coater and then dried in an oven (90 ° C., 30 seconds) to give a coating amount of about 10 g / m ² .

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

7.5 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

8.5 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Water Disperse Glycidyl Methacrylate Copolymer

[Japan Carbide, G118, 40% solids] 8.5 parts by weight

Isopropyl alcohol 6.5 parts by weight

Water Disperse Wax [USA Johnson JW-26, Solid 25%] 1.2 parts by weight

Example 2

Coating was carried out in the same manner as in Example 1 except that the coating composition of the coating layer was carried out as follows.

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

5.5 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

5.5 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Water Disperse Glycidyl Methacrylate Copolymer

[Japan Carbide Co., G118, 40% solids] 5.6 parts by weight

Example 3

Coating was carried out in the same manner as in Example 1 except that the coating composition of the coating layer was carried out as follows.

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

14.3 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

14.3 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Water Disperse Glycidyl Methacrylate Copolymer

[Japan Carbide Company G118, 40% solids] 14.3 parts by weight

Comparative Example 1

The following composition was coated on a basis weight 350 g / m ² cardboard using a bar coater and then dried in an oven (90 ° C., 30 seconds) to give a coating amount of about 10 g / m ² .

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

7.5 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

8.5 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Isopropyl alcohol 6.5 parts by weight

Water Disperse Wax [USA Johnson JW-26, Solid 25%] 1.2 parts by weight

Comparative Example 2

Coating was carried out in the same manner as in Comparative Example 1 except that the coating composition of the coating layer was carried out as follows.

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

5.5 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

5.5 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Comparative Example 3

Coating was carried out in the same manner as in Comparative Example 1 except that the coating composition of the coating layer was carried out as follows.

100 parts by weight of water-dispersed copolymer polyester [SK Chemical EW 312, solid content 30%]

14.3 parts by weight of acrylic copolymer [Samyoung Ink KP430 KS, solid content 28%]

14.3 parts by weight of styrene copolymer [Hanhwa Petrochemical HG-80, solid content 30%]

Comparative Example 4

Coating was carried out in the same manner as in Comparative Example 1 except that the coating composition of the coating layer was carried out as follows.

Polystyrene 30% by weight

Toluene 69 wt%

Antifoam 1 wt%

The evaluation of the coating amount, glossiness, moisture permeability, and adhesion according to Examples 1 to 3 and Comparative Examples 1 to 4 is summarized in Table 3 below.

Test Example

[Measurement of physical properties]

1. Glossiness

Comparative Example 4 calendering at a pressure of 150 kgf / m ² at 100 ℃, the rest of the Examples and Comparative Examples was measured by Tri microgross 160 [Sheen] 10 times to measure the gloss of 60 ° 10 average Compared to.

2. Breathability (KS A 1013)

The amount of moisture absorbed for 24 hours per 1 m ² by using anhydrous calcium chloride as an absorbent and placing it in a constant temperature and humidity device with a humidity of 90 ± 2% and a temperature of 40 ± 1 ℃. The water vapor transmission rate was measured in terms of.

3. Adhesion Measurement

100 squares were formed in a 2.5 cm square on the coated substrate and attached to a tape and measured by the number of squares removed after peeling.

4. Blocking resistance measurement (KS A 1024)

This is to check the degree of tearing of the coating layer by the pressure, temperature and humidity of the coated surface, and to test the problems that may occur when the packages are stacked after packaging. After contacting the coated and non-coated surfaces for 24 hours at a humidity of 75%, a temperature of 40 ± 1 ℃, a weight of 45 × 30 mm 500 g, and a pressure of 10 kgf / m ² , each surface is torn when the contact surface is removed. The degree of visual evaluation was visually evaluated and evaluated in three steps.

There is no blocking (◎) There is some blocking (△) There is blocking (×)

As described above, in the case of the embodiment where the coating film was cured using a water-dispersible glycidyl methacrylate copolymer as a result of calendering at a pressure of 150 kgf / m ² at 70 ° C. when the coating was made constant. In the case of Comparative Example (1, 2, 3) in which the coating film was not hardened while the gloss was high, it was found that the heat resistance of the film was reduced, and the film was aged due to high temperature calendering and the gloss was degraded. Since the glass ion of the polystyrene itself of Comparative Example 4 was 100 ° C., the gloss was alive without any influence in the calendering process. In addition, the present invention was found to have a property that can maintain excellent gloss even when calendering at a lower temperature than conventional oil-based products.

In the case of moisture permeability, the physical properties of the coating surface were densified in Examples 1 to 3 in which the coating film was cured, and the moisture permeability was much lower than that of Comparative Examples 1 to 3.

In the case of the adhesive force, the Example has high flexibility and shows excellent adhesiveness, but as shown in Comparative Example 4, it was found that the flexural adhesive strength was lowered due to the stiffness of the polymer itself.

In the case of blocking resistance, it was found that the examples had no blocking.

In Comparative Example 4, however, the moisture permeability and blocking resistance were excellent, but there is a problem in that harmful organic solvents such as toluene not only contaminate the environment but also harm the health by being absorbed by the human body. It has coating adhesiveness and gloss, moisture permeability and blocking resistance, and has advantages of environmental preservation and harmlessness to human body.

As described above, the coating composition according to the present invention has the excellent film forming ability and glossiness of the water-dispersible copolymer polyester as a partial crosslinking reaction property of the acrylic polymer of the various emulsion forms and the water-soluble glycidyl methacrylate copolymer. Therefore, a composition can be provided on the paper which is the substrate and has excellent coating property and adhesion, and excellent surface gloss, heat resistance, moisture permeability and blocking property. In addition, it preserves the environment, such as improving the workplace and has an advantage in terms of safety hygiene.

Claims (5)

Next 100 parts by weight of water-dispersed copolymer polyester having a structure as in Formula 1, 1 to 45 parts by weight of the acrylic copolymer, 1 to 45 parts by weight of a styrene copolymer, and 1 to 35 parts by weight of the water-dispersed glycidyl methacrylate copolymer represented by the following formula (3) Aqueous OPV (Over Printing Varnish) coating composition, characterized in that it contains: [Formula 1] In Formula 1, M is a group derived from a neutralizing agent, x, y, m and n represent the composition ratio of each monomer, x and y are each in the range of 0.1 to 0.6, m + n = 1 ; [Formula 3] In Formula 3, m and n represent the composition ratio of each monomer, m + n = 1, n is in the range of 0.1 to 0.2. delete The method of claim 1, wherein M is ammonia, morpholine, dimethylamine, dimethyl ethylamine, triethylamine, N, N-dimethylamino ethanol, 2-amino-2-methyl propanol, monoethanol amine, diethanol amine, Aqueous OPV coating composition, characterized in that a group derived from a basic neutralizing agent selected from diethylmethanol amine, triethanol amine. The composition of claim 1, wherein the composition comprises ethanol, isopropyl alcohol, butanol, ethylene glycol, isopropyl glycol, ethyl glycol, butyl glycol, propylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2 propanol, Aqueous OPV coating, characterized in that 3 to 10 parts by weight of a solvent of an alcohol system selected from 1-propoxy-2-propanol and 1-butoxy-2-propanol is added to 100 parts by weight of solids of the water-dispersed copolyester. Composition. The aqueous OPV coating composition according to claim 1, wherein 1-5 parts by weight of a water-dispersible wax is added to the composition with respect to 100 parts by weight of solids of the water-dispersed copolymer.