KR19980037054A - Water-soluble coating solution for synthetic paper with excellent printability and products coated with it - Google Patents

Abstract

The present invention relates to a water-soluble coating solution for synthetic paper having excellent printability and a product coated with the same, more specifically, one or more pigments selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, the pigments A water-soluble coating liquid consisting of a binder consisting of 10 to 40 parts by weight of styrene-butadiene rubber latex, 1 to 4 parts by weight of starch, and 1 to 10 parts by weight of polyvinyl alcohol, water and other additives, and the coating solution of the polyolefin film It relates to a synthetic paper coated with a thickness of 2 to 30㎛ on one side or both sides. Even if the coating solution is directly coated on the film without the bottom coating, it is possible to prepare a synthetic paper having excellent adhesive strength of the coating layer and good printability after drying. In addition, productivity can be improved by simplifying the coating process.

Description

Water-soluble coating solution for synthetic paper with excellent printability and products coated with it

The present invention relates to a water-soluble coating solution for synthetic paper having excellent printability and a product coated therewith, and more particularly, to a water-soluble coating solution for synthetic paper having good adhesive strength and good printability.

In general, a method of coating a surface is mainly used to prepare a printable plastic film, particularly a polyolefin film (hereinafter referred to as synthetic paper), and the synthetic paper has a smooth plastic film layer (base film) and printability and It is composed of a coating layer surface-treated with a water-soluble coating liquid to improve the handwriting.

The main raw material of the plastic film layer may be polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), or polyvinyl chloride (PVC) as a reusable thermoplastic resin. The plastic film layer is a transparent or translucent film, and in the case of the translucent film, the filler is calcium carbonate, titanium dioxide, silica, zinc oxide, magnesium oxide, talc, mica, clay, etc. as a filler. May be used alone or in combination. The manufacturing method of the base film includes a calendering method, a T-die Forming method and an Inflation Forming method. Is selected.

On the other hand, the coating liquid used to prepare synthetic paper selects water solubility which is easy to handle and has an advantage in terms of safety. Synthetic paper with excellent printability coated with water-soluble coating solution controls the thickness and physical properties of the base film layer, thus making labels, business cards, maps, posters, cards, nameplates, tickets, freight tickets, toys, stationery, daily necessities, food and medicine It can be used as various packaging materials.

However, in the related art, when the coating solution is water-soluble, a lower coating (primer) layer is mainly formed on the base film because of poor interface adhesion between the base film layer and the coating layer, and then two or three coatings are formed to form the coating layer. . Examples of the lower coating liquid include polyvinylidene chloride (PVDC) coating liquid (Japanese Patent Laid-Open No. 6-264368), acrylic coating and PVDC coating liquid (Japanese Laid-Open Patent Publication No. 5-17606), and unsaturated polyester coating liquid (Japanese Lap. Japanese Patent Application Laid-Open No. 5-339897), or an acrylamide-based, acrylonitrile-based, and polyvinylidene-based coating solution (Japanese Patent Laid-Open No. 6-79964, European Patent No. 0529110A1, and Japanese Patent Laid-Open No. 5-148376). .

In other words, when the coating liquid used for imparting printability and handwriting is water-soluble, which is environmentally friendly, especially when the base film layer of synthetic paper is very non-polar, such as polyolefin film, the adhesion between the base film layer and the coating layer is poor. (Primer) and top coating on it to improve the adhesive strength of the coating layer. However, this two or three coating method has several disadvantages such as reducing the productivity of the product and raising the price.

Therefore, an object of the present invention is to provide a water-soluble coating solution having a high adhesive strength of the coating layer after drying even if the water-soluble coating solution is directly coated without a bottom coating process.

Another object of the present invention to provide a synthetic paper having excellent printability using the coating solution.

The coating solution of the present invention for achieving the above object is a water-soluble coating solution for synthetic paper, one or more pigments selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, styrene- based on 100 parts by weight of the pigment It consists of a binder consisting of 10 to 40 parts by weight of butadiene rubber latex, 1 to 4 parts by weight of starch, and 1 to 10 parts by weight of polyvinyl alcohol, water and other additives.

Synthetic paper of the present invention for achieving another object of the present invention one or more pigments selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, styrene-butadiene rubber latex 10 with respect to 100 parts by weight of the pigment A water-soluble coating solution composed of a binder comprising 40 parts by weight, 1 to 4 parts by weight of starch, and 1 to 10 parts by weight of polyvinyl alcohol, water and other additives was coated on a thickness of 2 to 30 μm on one or both sides of the polyolefin film. Is done.

Looking at the present invention in more detail as follows.

Synthetic paper according to the present invention is composed of a smooth plastic film layer and a coating layer surface-treated with a water-soluble coating liquid to improve the printability and writeability thereon.

In the present invention, the plastic film is a polyolefin film which is expected to be utilized in particular in terms of the environment. Preferred examples of the resin include 40 to 70% by weight of PP, 10 to 40% by weight of PE and maleic anhydride graft polypropylene. It consists of-5 weight%, and a filler (pigment) consists of 5 to 35 weight% of calcium carbonate, and 5 to 20 weight% of titanium dioxide. The thickness of the film is adjusted to 60 to 300 µm to suit the desired use. The composition components and ranges are preferred embodiments for applying the coating solution according to the present invention described below, and can be modified by those skilled in the art.

In the coating layer according to the present invention, various pigments are used as in the manufacture of a base film to improve printability, and polymer materials of emulsion type and water-soluble type are used as binders. In addition, various additives such as dispersants, antistatic agents, lubricants, and insolubilizers for improving water resistance may be included.

As a pigment usable in the present invention, one or more selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, the amount of the pigment is preferably 10 to 70% by weight based on the coating liquid.

The binder used in the preparation of the water-soluble coating solution of the present invention used styrene-butadiene rubber (SBR) latex and starch (Starch) that can be used generally. However, using only the binder does not smoothly coat the polyolefin film, and the interfacial adhesive strength with the film layer is not good. Therefore, using the polyvinyl alcohol (PVA) together to improve the problem. The amount of the styrene-butadiene rubber latex is 10 to 40 parts by weight of the pigment, the amount of the starch is 1 to 4 parts by weight based on 100 parts by weight of the pigment, and the amount of the PVA is 1 to 10 parts by weight of the pigment A weight part is preferable, More preferably, it is 1-4 weight part. In this case, if the amount is less than 1 part by weight, the effect is not great, and if it exceeds 10 parts by weight, the coating liquid may have a high viscosity and may not be smoothly coated, thereby reducing productivity and reducing the stability of the coating liquid. In addition, the PVA is 90 mol% or less, the saponification is not very high, the viscosity is preferably 3 to 40 cps (4% aqueous solution, 20 ℃). In the case of a plastic film, unlike paper, the coating liquid component does not penetrate into the base film layer at all, so physical adhesion of the base film and the coating liquid component is very important. Therefore, when the degree of saponification is high and the hydrophilic component is strong in the PVA molecule, it is not particularly in close contact with the non-polar polyolefin film. Said PVA can be used individually or in mixture of 2 or more within the said conditions. In addition, when the viscosity is less than 3 cps (4% aqueous solution, 20 ℃), the use effect is not great, and if the viscosity exceeds 40 cps (4% aqueous solution, 20 ℃), the viscosity of the coating liquid is high, so only a small amount can be used.

In addition to the above components, the coating solution of the present invention may contain a small amount of other additives used in conventional water-soluble topcoat agents. For example, dispersants such as Na-polyacrylate, antistatic agents such as quaternary alkylammonium, glidants such as calcium stearate, insolubilizers such as ammonium-zirconium carbonate, and / or antifoaming agents such as alkylamide glycerine trialkylate Etc. may be included. Their amount can be changed without being limited within the usual range. The coating solution is adjusted by adding water so that the concentration of the final solid content is 20 to 80% by weight. At this time, if the viscosity is less than 20% by weight is too low and the printability after coating is not good, if the content exceeds 80% by weight there is a disadvantage that the viscosity is not too high smooth coating.

On the other hand, when the base film of synthetic paper is polyolefin such as PP or PE, the surface tension is about 30 to 32 dyne / cm, which is very non-polar, so that printability and writing property are not good, and thus pigment coating is required. In this case, when the coating solution is prepared and used with environmentally friendly water-soluble, the coating is not smoothly performed in the coating operation, and the interface adhesion of the coating layer is not good after drying. However, the water-soluble coating liquid according to the present invention having the above-described composition is smoothly coated only by the top coating on the polyolefin film prepared by the calendering method, and after drying, it is possible to prepare a synthetic paper having very good interfacial adhesion between the base film and the coating layer. The coating solution may be coated on one side or both sides of the base film, the thickness of the coating layer after drying is preferably 2 ~ 30㎛ and may be thicker.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples.

Examples 1-2 and Comparative Example 1

The raw material of the film is resin: PP (H900F, Hyundai Petrochemical) 54% by weight, PE (HDPE 6590, Hanwha General Chemical) 10% by weight, Maleic Anhydride Graft Polypropylene (Exxelor PO1015, Exxon) 5% by weight The filler consists of 20% by weight calcium carbonate, 10% by weight titanium dioxide and 1% by weight of other additives (typically silica, lubricants, antioxidants and light stabilizers). They are melt mixed uniformly in an extruder and passed through a calendering roll at a temperature of 200 ° C. or higher to produce films. At this time, the width of the calendering roll, the gap between the rolls in the nip, and the speed of the take-off roll are adjusted to adjust the thickness of the film to 100 μm, and then the corona discharge treatment is used for the synthetic paper base film (F-1). ).

Synthetic paper is composed of a base film layer and a pigment coating layer, the surface of the polyolefin film prepared by coating the water-soluble coating solution of Table 1 on one side with a bar coater (Bar Coater) and dried for 2 minutes at 70 ℃. The coating thickness is adjusted to 10㎛ after drying.

Composition of coating solution Unit: parts by weight (phr) Raw material Comparative Example 1 Example 1 Example 2 Dispersant (Na-polyacrylate) Styrene-butadiene rubber latex (50% aqueous solution) Starch clay calcium carbonate defoaming agent Polinol P-17A (polyvinyl alcohol) 0.5phr35.02.070.030.00.20.50.5 0.5phr35.02.070.030.00.20.51.5 0.5phr35.02.070.030.00.20.53.0

In Table 1, the manufacturer and product name of each component are as follows.

Dispersant (Na-polyacrylate): Kosant A-40, Jeongwoo Fine Chemical

Styrene-butadiene rubber latex (50% aqueous solution): SBR-Latex KL-207, Kumho Petrochemical

Starch: Nylgum A-85, Avebe

Clay: ASP NC, Engelhard

Calcium Carbonate: Carbital-90, ECC

Antifoam: Alkyl Amide Glycerine Trialkylate, Jeongwoo Fine Chemical

Lubricant: Supercote-550, Jeongwoo Fine Chemical

On the other hand, in Table 1, Polinol P-17A has a saponification degree of 87.5 ± 1.5 mol%, and a viscosity (4% aqueous solution, 20 ° C.) of PVA of Oriental Chemical. The concentration of the coating solution according to Examples 1 and 2 and Comparative Example 1 was adjusted using water so that the total solid content was 40% by weight.

Examples 3-4 and Comparative Example 2

The raw material of the film is composed of 49% by weight of PP, 25% by weight of PE, 25% by weight of calcium carbonate and 1% by weight of other additives (silica, lubricant, antioxidant and light stabilizer). As in Example 1, they are uniformly melt mixed in an extruder and passed through a calendering roll at a temperature of 200 ° C. or higher to produce films. The thickness of the film was adjusted to 200 μm and subjected to corona discharge to prepare a synthetic paper base film (F-2).

The coating solution of Table 2 was coated on the prepared polyolefin film with a bar coater and dried at 70 ° C. for 1 minute, followed by coating the back surface and drying at 70 ° C. for 2 minutes. The coating thickness is adjusted so that both sides are 10 탆 each after drying.

Composition of coating solution Unit: parts by weight Raw material Comparative Example 2 Example 3 Example 4 Dispersant (Na-polyacrylate) styrene-butadiene rubber latex (50% aqueous solution) starch clay calcium carbonate titanium dioxide antifoaming agent S / E LA-18GP (PVA) 1.035.02.055.025.020.00.20.50.5 1.035.02.055.025.020.00.20.51.5 1.035.02.055.025.020.00.20.53.0

In Table 2, S / E LA-18GP is PVA of ShinEtsu, and the saponification degree is 84.56 mol%, the viscosity (4% aqueous solution, 20 ° C.) is 2.8 cps, and the other components are the same as in Table 1. The concentration of the coating solution according to Examples 3 to 4 and Comparative Example 2 is adjusted using water so that the total solid content is 50% by weight.

Comparative Examples 3 to 5

The following coating solution was coated on the polyolefin film prepared in Example 1 and dried at 70 ° C. for 2 minutes. The coating thickness is adjusted to 10㎛ after drying.

Preparation of Coating Liquid

Instead of PVA Polinol P-17A in the coating solution composition used in Example 1, Polinol F-17A of Dongyang Chemistry with saponification degree of 98.75 ± 0.75mol% and viscosity (4% aqueous solution, 20 ° C) of 28.0 ± 3.0cps was used. To prepare coating liquids of Comparative Examples 3 to 5. At this time, using water, the concentration of the coating liquid as in Examples 1 to 2 and Comparative Example 1 is adjusted so that the total solid content is 40% by weight.

Comparative Example 6

The following coating solution was coated on the polyolefin film prepared in Example 1 and dried at 70 ° C. for 2 minutes. The coating thickness is adjusted to 10㎛ after drying.

Preparation of Coating Liquid

The coating solution was prepared without adding Polinol P-17A, which is PVA, in the coating solution composition used in Example 1. At this time, the concentration is adjusted so that the total solid content is 50% by weight.

Each synthetic paper sample was prepared, and the results of the coating properties (coating smoothness) of the prepared coating solution and the interfacial adhesion of the coating layer after drying are shown in Table 3 below.

Results for Examples and Comparative Examples Example / Comparative Example Base film Coating Interface adhesion Comparative Example 1 Example 1 Example 2 F-1F-1F-1 ○○○ △ ○○ Comparative Example 2 Example 3 Example 4 F-2F-2F-2 ○○○ △ ○○ Comparative Example 3 Comparative Example 4 Comparative Example 5 F-1F-1F-1 × △△ × △△ Comparative Example 6 F-1 × ×

※ The coating properties were measured by the appearance observation such as the formation of pinholes during coating and after coating drying. The interfacial adhesion was measured according to ASTM D3359-92a. ○ is good, △ is medium and × is bad.

As a result of testing the interfacial adhesion of the coating layer on the VIF-90 of Wang emulsification and WP-110 and WP-160 of the one-ocular spinning, the synthetic paper prepared in Examples 2 and 4 can be confirmed that the synthetic paper of the present invention is excellent. there was. In addition, when comparing the printability of the art paper (commercial paper) commercially available synthetic paper of the present invention, as shown in Table 4 below, the wax picking (Wax Picking) and wet picking (Wet Picking) related to the interfacial adhesion of the coating layer ) Better than art papers and printability was good.

Comparison of printability of synthetic paper and art paper of the present invention Sample test item Example 2 Art paper (A) Example 4 Art paper (B) Coating amount g / m ² 9.7 15.0 11.5 13.0 Printability Printing gloss 1 color - - 92.0 81.5 2 colors - - 91.7 85.0 Wax picking 14 Max 14 ↑ 10 - - Wet Picking 5-point method - - 4.4 4.2 Cultivation 2.5 4.5 3.8 4.2 Ink Set 3.5 3.0 3.9 4.2 K & N ink repair property % 12.1 13.6 6.4 20.0 Croda Ink Repair 51.8 29.2 22.3 37.5

※ The definition of each test item is as follows.

Coating amount: Weighing before and after coating; A paper with a coating amount of 15.0 g is A and the coating amount is

13.0g art paper divided into B

Print Gloss: Gloss Meter at 60。

Wax Picking: Melt wax with different viscosities, apply it to synthetic paper, solidify, and then tear it off

Is a figure of wax; 14 resin

Wet Picking: The degree of water resistance of the coating layer when the synthetic paper is wet and printed.

Peculiarity: The degree to which synthetic paper gets wet and the ink gets printed when printing

Ink set: Stick the base film immediately after printing and print it again

Measured by the amount of croissants

Ink repair: Wipe the ink off the surface after 2 minutes

Measure the amount (KK and Croda are kinds of ink)

As mentioned above, in the case of plastic films, in particular polyolefin films, the surfaces are very nonpolar and generally have poor printability, handwriting and antistatic properties. Therefore, the coating is carried out by surface treatment. When the coating agent used is water-soluble, the adhesive strength of the coating layer is poor after drying, and in general, first, a pigment coating is performed after treating a lower coating agent that provides an adhesive function. However, the coating solution according to the present invention can produce a synthetic paper having excellent adhesive strength and good printability of the coating layer after drying, even if directly coated on the film without the bottom coating as shown in Tables 3 and 4. In addition, the coating process has a beneficial effect on productivity improvement.

Claims (10)

In the aqueous coating solution for synthetic paper, one or more pigments selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, 10 to 40 parts by weight of styrene-butadiene rubber latex per 100 parts by weight of the pigment, starch 1 A water-soluble coating solution for synthetic paper having excellent printability, comprising:-4 parts by weight, and a binder comprising 1 to 10 parts by weight of polyvinyl alcohol, water, and other additives. The water-soluble coating solution for synthetic paper having excellent printability according to claim 1, wherein the saponification degree of the polyvinyl alcohol is 90 mol% or less and the viscosity is 3 to 40 cps (4% aqueous solution, 20 ° C). The water-soluble coating solution for synthetic paper having excellent printability according to claim 1, wherein the coating liquid has a pigment content of 10 to 70% by weight and a total solid content of 20 to 80% by weight. The water-soluble coating solution for synthetic paper having excellent printability according to claim 1, wherein the other additives are dispersants, antistatic agents, lubricants and / or insoluble solvents. One or more pigments selected from the group consisting of clay, calcium carbonate, titanium dioxide, silica and talc, 10 to 40 parts by weight of styrene-butadiene rubber latex, 1 to 4 parts by weight of starch, and poly A synthetic paper, characterized in that the water-soluble coating solution consisting of a binder, water and other additives consisting of 1 to 10 parts by weight of vinyl alcohol is coated on one or both sides of the polyolefin film to a thickness of 2 to 30㎛. The synthetic paper according to claim 5, wherein the saponification degree of the polyvinyl alcohol is 90 mol% or less and the viscosity is 3 to 40 cps (4% aqueous solution, 20 ° C). The synthetic paper according to claim 5, wherein the coating liquid has a pigment content of 10 to 70% by weight and a total solid content of 20 to 80% by weight. The method of claim 5, wherein the polyolefin film is 40 to 70% by weight polypropylene, 10 to 40% by weight polyethylene, 0 to 5% by weight maleic anhydride graft polypropylene, 5 to 35% by weight calcium carbonate and titanium dioxide Synthetic paper, characterized in that consisting of 5 to 20% by weight. The synthetic paper according to claim 8, wherein the film has a thickness of 60 to 300 µm. The synthetic paper according to claim 8, wherein the film is a film prepared by melt-mixing uniformly in an extruder and passing a calendering roll at a temperature of 200 ° C or higher.