CN118308904A - Coating white cardboard capable of preventing ink set-off and preparation method thereof - Google Patents

Abstract

The invention provides an ink-set-proof coated white cardboard and a preparation method thereof, wherein the coated white cardboard comprises white cardboard, a first coating and a second coating which are sequentially compounded on the surface of the white cardboard; in the first coating and the second coating, polyvinyl acetate latex (PVAC latex) is used, the PVAC latex has high glass transition temperature, strong film tension and good air permeability after film formation; in addition, the second coating uses light calcium carbonate with fine particle size, has small particle size and regular needle-shaped structure, has narrower and uniform particle size distribution and poor covering property; the specific surface area is large, and the oil absorption value is high; the surface structure of the coating is improved, the porosity and the micropore number of the surface of the coating are increased, the ink absorption rate and the ink adhesion are improved, the flowability of the ink is reduced, and the smear problem in the two-dimensional code printing process is prevented.

Description

Coating white cardboard capable of preventing ink set-off and preparation method thereof

Technical Field

The invention belongs to the technical field of papermaking coating, and particularly relates to an ink-set-proof coated white cardboard and a preparation method thereof.

Background

The coated white cardboard is a porous printing material composed of a fiber network and coating pores, and is widely applied to the outer package of products such as cosmetics, daily necessities, cigarettes and wines as high-grade printing paper. With the increasing demand of packaging printing, higher demands are also put on the performance of the coated white cardboard, for example, the coated white cardboard needs to have good smoothness, folding endurance, glossiness, ink absorbency and the like, and also needs to have good printing printability.

Many factors influencing the quality of the white cardboard are included, such as base paper, paint, coating technology and the like, wherein the characteristics of various components in the paint improve the appearance and physical and chemical characteristics of the paper, and directly influence the performances of the paper, such as gloss, appearance definition, bacteria resistance, wear resistance, printing adaptability and the like. During printing, the ink used for printing is transferred from the plate surface to the paper surface, and the ink absorption capacity is called as a very important index of the coated printing paper, and determines the penetration amount and penetration rate of the ink after being printed on the paper surface. Many print failures are often caused by the fact that the ink absorption capacity of the paper is not compatible with the printing conditions used. The paper has too strong ink absorption capacity, which can lead to matt marks and even chalking; too weak an ink absorption capacity of the paper can slow down the drying speed of the ink, resulting in smearing on the back.

Disclosure of Invention

The invention aims to provide an ink-smear-resistant coated white cardboard and a preparation method thereof.

The invention provides an ink-set-proof coated white cardboard, which comprises white cardboard base paper, and a first coating and a second coating which are sequentially compounded on the surface of the white cardboard base paper;

the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight:

Heavy calcium carbonate: 85-95 parts; kaolin: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part;

The second coating is prepared from a second coating, and the second coating comprises the following components in parts by weight:

Heavy calcium carbonate: 60-70 parts of kaolin: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part.

Preferably, the light calcium carbonate has an average particle diameter of 0.3 to 0.5 μm, a particle ratio of particles having a particle diameter of 2 μm or less of 99%, and a rod-like structure, and an aspect ratio of (3 to 20): 1, the specific surface area is less than 12m ²/g.

Preferably, the particle size of the light calcium carbonate is 0.1-1 mu m, and the oil absorption value is 60-90 mL/100g.

Preferably, the particle size of the polyvinyl acetate latex is 280-320 nm, and the particle size of the styrene-acrylic latex is 120-140 nm.

Preferably, the white cardboard raw paper comprises a bottom layer, a core layer and a surface layer, wherein the surface layer is contacted with the first coating layer.

The invention provides a preparation method of the ink-set-proof coated white cardboard, which comprises the following steps:

a) Sequentially coating the surface of the white cardboard base paper with the first coating and the second coating, and drying to obtain a semi-finished product;

b) And carrying out soft calendering and curling on the semi-finished product to obtain the coated white cardboard.

Preferably, the first coating is prepared according to the following steps:

Stirring part of heavy calcium carbonate in water at a rotating speed of 300-500 rpm, adding sodium hydroxide solution, a dispersing agent and a defoaming agent, increasing the stirring rotating speed to 600-800 rpm, continuously adding the rest of heavy calcium carbonate and calcined china clay, stirring for 180-240 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring rotating speed to 900-1200 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 140-160 s, and adding a water-resistant agent, stirring for 480-600 s to obtain the first coating.

Preferably, the solid content of the first coating is 60-70%, and the coating amount of the first coating is 11.5-12.5 g/m ².

Preferably, the second coating is prepared according to the following steps:

Stirring part of heavy calcium carbonate in water at a rotating speed of 300-500 rpm, adding sodium hydroxide solution, a dispersing agent and a defoaming agent, continuously adding the rest of heavy calcium carbonate, high-gloss porcelain clay and light calcium carbonate, increasing the stirring rotating speed to 600-800 rpm, stirring for 150-180 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring rotating speed to 900-1200 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 150-240 s, adding a water-resistant agent, and stirring for 480-600 s to obtain the second coating.

Preferably, the solid content of the second coating is 60-70%, and the coating weight of the second coating is 8-9 g/m ².

The invention provides an ink-set-proof coated white cardboard, which comprises white cardboard, a first coating and a second coating, wherein the first coating and the second coating are sequentially compounded on the surface of the white cardboard; the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight: heavy calcium carbonate: 85-95 parts; calcining porcelain clay: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part; the second coating is prepared from a second coating, and the second coating comprises the following components in parts by weight: heavy calcium carbonate: 60-70 parts of high-gloss porcelain clay: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part. The invention firstly carries out two-pass coating on the surface of the white cardboard, the finished paper surface is fine and smooth, the printing effect is good, the printing requirement is met, and meanwhile, the finished paper has good air permeability, thereby being beneficial to the absorption of water-based ink. In the first coating and the second coating, polyvinyl acetate latex (PVAC latex) is used, the PVAC latex has high glass transition temperature, strong film tension and good air permeability after film formation; in addition, the second coating uses light calcium carbonate with fine particle size, has small particle size and regular needle-shaped structure, has narrower and uniform particle size distribution and poor covering property; the specific surface area is large, and the oil absorption value is high; the surface structure of the coating is improved, the porosity and the micropore number of the surface of the coating are increased, the ink absorption rate and the ink adhesion are improved, the flowability of the ink is reduced, and the problem of smearing in the printing process, especially in the two-dimensional code printing process is prevented.

According to the invention, the developed coating packaging paper is used for liquid flexography of two-dimensional codes, the ink absorption speed of water-based ink can be reduced to 112mm, and the ink absorption speed of the water-based ink is reduced to 130mm in a common formula. The novel coating pigment and the novel coating adhesive are selected, the paper surface of the finished paper is fine, the coating has good openness, and the requirement on rapid absorption of the water-based ink can be met. The coating packaging paper developed by the project has a special coating structure and a plurality of capillary pore structures, meets the requirement of quick ink absorption of the flexo coating, and improves the ink absorption rate of paper, thereby improving the ink drying speed and preventing the paper surface from being smeared. The paint adhesive, the coating amount and the drying speed are reasonably controlled, the speed of paper to ink is optimized, the printing glossiness is ensured, and the chalking phenomenon is prevented; but also improves the drying speed of the ink and prevents the paper from being smeared.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is an SEM image of light calcium carbonate used in the examples of the present invention;

FIG. 2 is a graph showing the particle size distribution of light calcium carbonate used in example 1 of the present invention.

Detailed Description

The invention provides an ink-set-proof coated white cardboard, which comprises white cardboard, a first coating and a second coating, wherein the first coating and the second coating are sequentially compounded on the surface of white cardboard base paper;

the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight:

Heavy calcium carbonate: 85-95 parts; kaolin: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part;

The second coating is prepared from a second coating, and the second coating comprises the following components in parts by weight:

Heavy calcium carbonate: 60-70 parts of kaolin: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part.

In the invention, the white cardboard base paper comprises a bottom layer, a core layer and a surface layer which are sequentially contacted, wherein the surface pulp, the core pulp and the bottom pulp are respectively prepared, streamed to a net part for molding, and are obtained after squeezing, pre-baking, sizing, post-baking and hard calendaring. The preparation process of the white cardboard base paper can adopt the preparation process of the white cardboard commonly used in the field, and can also adopt the commercial goods of the white cardboard base paper.

In the invention, the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight:

Heavy calcium carbonate: 85-95 parts; calcining porcelain clay: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part.

In the present invention, the heavy calcium carbonate is preferably calcium carbonate C60, that is, calcium carbonate particles having a particle diameter of < 2 μm account for 60%, and the weight part of the heavy calcium carbonate is preferably 85 to 95 parts, more preferably 88 to 90 parts, such as 85 parts, 86 parts, 87 parts, 88 parts, 89 parts, 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the kaolin is preferably calcined kaolin, the moisture content of the calcined kaolin is not more than 0.5%, the particle size (< 2 μm) is not less than 40% (laser method), the particle size (< 2 μm) is not less than 83% (sedimentation method), the average particle size is preferably 0.6.+ -. 0.1 μm, the whiteness (R457) is not less than 92%, the pH (10% solid content) is 5 to 7.5, the sieve residue (325 mesh) is not more than 0.01%, the weight portion of the calcined kaolin is preferably 5 to 15 parts, more preferably 8 to 12 parts, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, preferably a range value in which any of the above values is an upper limit or a lower limit.

In the present invention, the weight part of the sodium carboxymethyl cellulose is preferably 0.1 to 1 part, more preferably 0.3 to 0.8 part, such as 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the particle size of the styrene-acrylic latex (SA latex) is preferably 120 to 140nm, more preferably 130 to 135nm; the styrene-acrylic latex preferably has a weight part of 5 to 10 parts, more preferably 6 to 8 parts, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and preferably has a value in a range of any of the above values as an upper limit or a lower limit.

In the present invention, the particle diameter of the polyvinyl acetate latex (PVAC latex) is preferably 280 to 320nm, more preferably 290 to 300nm; the polyvinyl acetate latex is preferably 5 to 10 parts by weight, more preferably 6 to 8 parts by weight, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and preferably has a value in a range of any of the above values as an upper limit or a lower limit.

The invention uses the polyvinyl acetate latex with larger particle size to replace part of styrene-acrylic latex, and the glass transition temperature of the polyvinyl acetate latex is high (about 37 ℃), which is favorable for improving the moldability of the coating, has good air permeability and quick drying, improves the surface structure of the coating, and improves the printing quality.

In the present invention, the dispersant is preferably a polycarboxylate dispersant; the dispersant is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.4 parts by weight, such as 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, and preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the antifoaming agent is preferably a mineral oil type antifoaming agent; the weight part of the defoaming agent is preferably 0.05 to 0.5 part, more preferably 0.1 to 0.4 part, such as 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, preferably a range value having any of the above values as an upper limit or a lower limit.

In the invention, the water repellent agent is preferably a zirconium potassium carbonate water repellent agent; the water repellent agent is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.4 parts by weight, such as 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the thickness of the precoating layer is preferably 11 to 13. Mu.m.

In the invention, the top coating is prepared from a second coating, and the second coating comprises the following components in parts by weight:

Heavy calcium carbonate: 60-70 parts of kaolin: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part.

In the present invention, the heavy calcium carbonate is preferably calcium carbonate C98, i.e., calcium carbonate particles having a particle diameter of < 2 μm account for 98%, and the weight part of the heavy calcium carbonate is preferably 60 to 70 parts, more preferably 62 to 68 parts, such as 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 8 parts, 69 parts, 70 parts, preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the light calcium carbonate preferably has an average particle diameter of 0.3 to 0.5. Mu.m, a particle ratio of particles having a particle diameter of 2 μm or less of 99%, and a rod-like structure having an aspect ratio of (3 to 20): 1, the specific surface area is less than 12m ²/g; the particle size of the light calcium carbonate is 0.1-1 mu m, and the oil absorption value is preferably 60-90 mL/100g, more preferably 70-80 mL/100g. The invention uses the light calcium carbonate to replace part of heavy calcium carbonate, and has large specific surface area and higher oil absorption value; the surface structure of the coating is improved, the porosity and the micropore number of the surface of the coating are increased, the air permeability is good, the ink absorption rate and the ink adhesion are improved, the flowability of the ink is reduced, and the smear problem in the two-dimensional code printing process is prevented.

In the present invention, the weight part of the light calcium carbonate is preferably 10 to 25 parts, more preferably 15 to 20 parts, such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, and preferably a range value in which any of the above values is an upper limit or a lower limit. The weight part is too low to achieve the improvement effect; too high a weight fraction affects the water retention of the coating and the rheology of the coating becomes poor.

The kaolin is preferably high-gloss kaolin, the high-gloss kaolin is fine porcelain clay with a top coating grade, the moisture is less than or equal to 1.5%, the whiteness is 86+/-1%, the pH (28% solid content) is 6-8, the viscosity (70% solid content, 2# rotor, 25 ℃) is less than or equal to 450 mPa.s, the particle size (< 2 mu m) is more than or equal to 40% (laser method), the particle size (< 2 mu m) is more than or equal to 96% (sedimentation method), the screen residue (325 meshes) is less than or equal to 0.005%, and the loss on ignition (950-1000 ℃) is less than or equal to 15%. The weight part of the highlight kaolin is preferably 5 to 20 parts, more preferably 10 to 15 parts, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, and preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the weight part of the sodium carboxymethyl cellulose is preferably 0.05 to 0.5 part, more preferably 0.1 to 0.4 part, such as 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the particle size of the styrene-acrylic latex (SA latex) is preferably 120 to 140nm, more preferably 130 to 135nm; the styrene-acrylic latex preferably has a weight part of 5 to 10 parts, more preferably 6 to 8 parts, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and preferably has a value in a range of any of the above values as an upper limit or a lower limit.

In the present invention, the particle diameter of the polyvinyl acetate latex (PVAC latex) is preferably 280 to 320nm, more preferably 290 to 300nm; the polyvinyl acetate latex is preferably 5 to 10 parts by weight, more preferably 6 to 8 parts by weight, such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and preferably has a value in a range of any of the above values as an upper limit or a lower limit.

The invention uses the polyvinyl acetate latex with larger particle size to replace part of styrene-acrylic latex, and the glass transition temperature of the polyvinyl acetate latex is high (about 37 ℃), which is favorable for improving the moldability of the coating, has good air permeability and quick drying, improves the surface structure of the coating, and improves the printing quality.

In the present invention, the dispersant is preferably a polycarboxylate dispersant; the dispersant is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.4 parts by weight, such as 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, and preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the antifoaming agent is preferably a mineral oil type antifoaming agent; the weight part of the defoaming agent is preferably 0.05 to 0.5 part, more preferably 0.1 to 0.4 part, such as 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, preferably a range value having any of the above values as an upper limit or a lower limit.

In the invention, the water repellent agent is preferably a zirconium potassium carbonate water repellent agent; the water repellent agent is preferably 0.1 to 1 part by weight, more preferably 0.3 to 0.8 part by weight, such as 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight, 0.6 part by weight, 0.7 part by weight, 0.8 part by weight, 0.9 part by weight, 1 part by weight, and preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the thickness of the second coating layer is preferably 8 to 9 μm.

The invention also provides a preparation method of the coating white cardboard with the ink smear prevention function, which comprises the following steps:

a) Sequentially coating the surface of the white cardboard base paper with the first coating and the second coating, and drying to obtain a semi-finished product;

b) And carrying out soft calendering and curling on the semi-finished product to obtain the coated white cardboard.

According to the invention, the first coating is coated on the front surface of the white cardboard base paper, namely the surface layer of the white cardboard base paper, and then the second coating is coated on the surface of the first coating, and 2-pass coating is adopted, so that the finished paper surface is fine, the printing effect is good, the printing requirement is met, and meanwhile, the finished paper has good air permeability, and the absorption of water-based ink is facilitated.

In the present invention, the sources of the white cardboard raw paper are consistent, and the present invention is not repeated here.

In the invention, the first coating is prepared according to the following steps:

Stirring part of heavy calcium carbonate in water at a rotation speed of 300-500 rpm, preferably 350-450 rpm, adding sodium hydroxide solution, dispersing agent and defoaming agent, increasing the stirring rotation speed to 600-800 rpm, preferably 650-750 rpm, continuously adding the rest of heavy calcium carbonate and calcined china clay, stirring for 180-240 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring rotation speed to 900-1200 rpm, preferably 1000-1100 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 140-160 s, adding a water-resistant agent, and stirring for 480-600 s to obtain the first coating.

In the present invention, the types and amounts of the heavy calcium carbonate, the calcined china clay, the sodium carboxymethyl cellulose, the styrene-acrylic latex, the polyvinyl acetate latex, the dispersant, the defoamer and the water-repellent agent are the same as those of the heavy calcium carbonate, the calcined china clay, the sodium carboxymethyl cellulose, the styrene-acrylic latex, the polyvinyl acetate latex, the dispersant, the defoamer and the water-repellent agent contained in the first coating layer, and the present invention is not repeated herein.

In the present invention, the weight part of the "part of heavy calcium carbonate" in the first coating layer is preferably 55 to 65 parts, more preferably 60 parts, and the weight part of the "remaining part of heavy calcium carbonate" is preferably 20 to 45 parts, more preferably 25 to 35 parts.

The invention prepares the first coating under the stirring condition, and gradually increases the stirring rotation speed under the stirring condition with lower rotation speed at first, and finally prepares the first coating with certain solid content.

In the present invention, the solid content of the first coating material is preferably 60 to 70%, more preferably 63 to 68%, and the coating amount of the first coating material is preferably 11.5 to 12.5g/m ², more preferably 11.8 to 12.0g/m ².

In the invention, the second coating is prepared according to the following steps:

Stirring part of heavy calcium carbonate in water at a rotation speed of 300-500 rpm, preferably 350-450 rpm, adding sodium hydroxide solution, dispersing agent and defoaming agent, continuously adding the rest of heavy calcium carbonate, high-gloss porcelain clay and light calcium carbonate, submitting to stirring at a rotation speed of 600-800 rpm, preferably 650-750 rpm, stirring for 150-180 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring speed to 900-1200 rpm, preferably 1000-1100 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 150-240 s, adding a water-repellent agent, and stirring for 480-600 s to obtain the second coating.

In the present invention, the types and amounts of the heavy calcium carbonate, the light calcium carbonate, the high-gloss porcelain clay, the sodium carboxymethyl cellulose, the styrene-acrylic latex, the polyvinyl acetate latex, the dispersing agent, the defoaming agent and the water-repellent agent are the same as those of the heavy calcium carbonate, the calcined porcelain clay, the sodium carboxymethyl cellulose, the styrene-acrylic latex, the polyvinyl acetate latex, the dispersing agent, the defoaming agent and the water-repellent agent contained in the second coating layer, and the present invention is not repeated herein.

In the present invention, the weight part of the "part of heavy calcium carbonate" in the second coating layer is preferably 35 to 45 parts, more preferably 40 parts, and the weight part of the "remaining part of heavy calcium carbonate" is preferably 15 to 35 parts, more preferably 20 to 30 parts.

In the present invention, the solid content of the second coating material is preferably 60 to 70%, more preferably 63 to 68%, and the coating amount of the second coating material is preferably 8 to 9g/m ², more preferably 8 to 8.5g/m ².

After the two coating processes are completed, the semi-finished product is obtained by drying the coating process.

In the present invention, the drying is preferably hot air oven drying and infrared drying, both of which are drying methods commonly used in the art, and the present invention is not limited thereto.

After drying, the semi-finished product is subjected to soft calendaring, a state regulating cylinder regulates water to enter coiling, and the coated white cardboard is obtained.

In the present invention, the soft calendering, moisture conditioning and crimping are all common steps in the papermaking process in the art, and the present invention is not described in detail herein.

The invention provides an ink-set-proof coated white cardboard, which comprises white cardboard, a first coating and a second coating, wherein the first coating and the second coating are sequentially compounded on the surface of the white cardboard; the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight: heavy calcium carbonate: 85-95 parts; kaolin: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part; the second coating is prepared from a second coating, and the second coating comprises the following components in parts by weight: heavy calcium carbonate: 60-70 parts of kaolin: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part. The invention firstly carries out two-pass coating on the surface of the white cardboard, the finished paper surface is fine and smooth, the printing effect is good, the printing requirement is met, and meanwhile, the finished paper has good air permeability, thereby being beneficial to the absorption of water-based ink. In the first coating and the second coating, polyvinyl acetate latex (PVAC latex) is used, the PVAC latex has high glass transition temperature, strong film tension and good air permeability after film formation; in addition, the second coating uses light calcium carbonate with fine particle size, has small particle size and regular needle-shaped structure, has narrower and uniform particle size distribution and poor covering property; the specific surface area is large, and the oil absorption value is high; the surface structure of the coating is improved, the porosity and the micropore number of the surface of the coating are increased, the ink absorption rate and the ink adhesion are improved, the flowability of the ink is reduced, and the smear problem in the two-dimensional code printing process is prevented.

According to the invention, the developed coating packaging paper is used for liquid flexography of two-dimensional codes, the ink absorption speed of water-based ink can be reduced to 112mm, and the ink absorption speed of the water-based ink is reduced to 130mm in a common formula. The novel coating pigment and the novel coating adhesive are selected, the paper surface of the finished paper is fine, the coating has good openness, and the requirement on rapid absorption of the water-based ink can be met. The coating packaging paper developed by the project has a special coating structure and a plurality of capillary pore structures, meets the requirement of quick ink absorption of the flexo coating, and improves the ink absorption rate of paper, thereby improving the ink drying speed and preventing the paper surface from being smeared. The paint adhesive, the coating amount and the drying speed are reasonably controlled, the speed of paper to ink is optimized, the printing glossiness is ensured, and the chalking phenomenon is prevented; but also improves the drying speed of the ink and prevents the paper from being smeared.

In order to further illustrate the present invention, the following examples are provided to describe a coated white cardboard with anti-ink set-off and a method for preparing the same in detail, but the present invention is not to be construed as being limited to the scope of the present invention.

In the following examples, light calcium carbonate having an average particle diameter of 0.3 to 0.5 μm and a particle ratio of not more than 2 μm was used in an amount of 99%, and having a rod-like structure with an aspect ratio of (3 to 20): 1, the specific surface area is less than 12m ²/g.

Comparative example 1

The paint used for the first coating comprises the following components in parts by weight: 88 parts of precoated calcium carbonate (C60), 12 parts of calcined china clay, 18 parts of SA latex, 0.4 part of CMC (sodium carboxymethylcellulose), 0.1 part of dispersing agent, 0.1 part of defoamer, 0.4 part of water repellent agent and the balance of water.

The preparation method comprises the following steps: 60 parts of precoated calcium carbonate is added into water, stirring is started at a lower speed of 400rpm, and after uniform stirring, naOH solution with the mass concentration of 10% is added, and dispersing agent and defoaming agent are slowly added; increasing the stirring speed to 700rpm, continuously adding 28 parts of precoated calcium carbonate, adding calcined china clay and stirring for 180 seconds; CMC is added and stirred for 1 minute; increasing the stirring speed to 1000rpm; adding SA latex and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the first coating with the solid content of 65.6%.

The coating used for the second coating comprises the following components in parts by weight: 85 parts of surface-coated calcium carbonate (C98), 15 parts of high-gloss porcelain clay, 18.5 parts of SA latex, 0.2 part of sodium carboxymethylcellulose CMC, 0.1 part of dispersing agent, 0.15 part of defoamer, 0.5 part of water repellent agent and the balance of water.

The preparation method comprises the following steps: adding 60 parts of surface-coated calcium carbonate into water, starting stirring at a lower speed of 400rpm, adding NaOH solution with the mass concentration of 10%, slowly adding a dispersing agent and a defoaming agent, continuously adding 25 parts of surface-coated calcium carbonate and 15 parts of high-gloss porcelain clay, improving the stirring speed to 700rpm, and stirring for 150 seconds; continuously adding CMC and stirring for 1 minute; adding SA latex and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the second coating with the solid content of 66.2%.

Respectively carrying out pulp mixing, flow-sending on the surface pulp, the core pulp and the bottom pulp to a net part for molding, and carrying out squeezing, pre-drying, sizing, post-drying and hard calendering to obtain base paper;

The primary coating and the secondary coating are respectively carried out on the front surface of the base paper for 2 times.

Drying after coating is completed, wherein the drying adopts a hot air box drying technology and an infrared drying technology

And (5) carrying out soft calendaring after drying, and regulating moisture by a state regulating cylinder to enter coiling to obtain the coated white cardboard.

The amount of paint used for the pre-coat and top coat was 11.8g/m ²、8.1g/m², respectively.

Comparative example 2

The paint used for the first coating comprises the following components in parts by weight: 88 parts of precoated calcium carbonate (C60), 12 parts of calcined china clay, 9 parts of SA latex, 9 parts of PVAC latex, 0.4 part of CMC (sodium carboxymethylcellulose), 0.1 part of dispersing agent, 0.1 part of defoaming agent, 0.4 part of water repellent agent and the balance of water.

The preparation method comprises the following steps: 60 parts of precoated calcium carbonate is added into water, stirring is started at a lower speed of 400rpm, and after uniform stirring, naOH solution with the mass concentration of 10% is added, and dispersing agent and defoaming agent are slowly added; increasing the stirring speed to 700rpm, continuously adding 28 parts of precoated calcium carbonate, adding 12 parts of calcined china clay, and stirring for 180 seconds; CMC is added and stirred for 1 minute; increasing the stirring speed to 1000rpm; adding SA latex and PVAC latex, and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the first coating with the solid content of 65.6%.

The coating used for the second coating comprises the following components in parts by weight: 85 parts of surface-coated calcium carbonate (C98), 15 parts of high-gloss porcelain clay, 18.5 parts of SA latex, 0.2 part of sodium carboxymethylcellulose CMC, 0.1 part of dispersing agent, 0.15 part of defoamer, 0.5 part of water repellent agent and the balance of water.

The preparation method comprises the following steps: adding 60 parts of surface-coated calcium carbonate into water, starting stirring at a lower speed of 400rpm, adding NaOH solution with the mass concentration of 10%, slowly adding a dispersing agent and a defoaming agent, continuously adding 25 parts of surface-coated calcium carbonate and 15 parts of high-gloss porcelain clay, improving the stirring speed to 700rpm, and stirring for 150 seconds; continuously adding CMC and stirring for 1 minute; adding SA latex and PVAC latex, and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the second coating with the solid content of 66.2%.

Respectively carrying out pulp mixing, flow-sending on the surface pulp, the core pulp and the bottom pulp to a net part for molding, and carrying out squeezing, pre-drying, sizing, post-drying and hard calendering to obtain base paper;

The primary coating and the secondary coating are respectively carried out on the front surface of the base paper for 2 times.

Drying after coating is completed, wherein the drying adopts a hot air box drying technology and an infrared drying technology

And (5) carrying out soft calendaring after drying, and regulating moisture by a state regulating cylinder to enter coiling to obtain the coated white cardboard.

The amount of paint used for the pre-coat and top coat was 11.8g/m ²、8.1g/m², respectively.

Example 1

The paint used for the first coating comprises the following components in parts by weight: 88 parts of precoated calcium carbonate (C60), 12 parts of calcined china clay, 9 parts of SA latex, 9 parts of PVAC latex, 0.4 part of CMC (sodium carboxymethylcellulose), 0.1 part of dispersing agent, 0.1 part of defoaming agent, 0.4 part of water repellent agent and the balance of water.

The preparation method comprises the following steps: 60 parts of precoated calcium carbonate is added into water, stirring is started at a lower speed of 400rpm, and after uniform stirring, naOH solution with the concentration of 10% is added, and dispersing agent and defoaming agent are slowly added; increasing the stirring speed to 700rpm, continuously adding 28 parts of precoated calcium carbonate, adding 12 parts of calcined china clay, and stirring for 180 seconds; CMC is added and stirred for 1 minute; increasing the stirring speed to 1000rpm; adding SA latex and PVAC latex, and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the first coating with the solid content of 65.5%.

The coating used for the second coating comprises the following components in parts by weight: 65 parts of top-coated calcium carbonate (C98), 20 parts of light calcium carbonate, 15 parts of high-gloss porcelain clay, 9 parts of SA latex, 9.5 parts of PVAC latex, 0.2 part of CMC (sodium carboxymethylcellulose), 0.1 part of dispersing agent, 0.15 part of defoaming agent, 0.5 part of water repellent and the balance of water.

The preparation method comprises the following steps: adding 40 parts of top-coated calcium carbonate and light calcium carbonate into water, starting stirring at a lower speed of 400rpm, adding a 10% NaOH solution, slowly adding a dispersing agent and a defoaming agent after stirring uniformly, continuously adding 25 parts of top-coated calcium carbonate, 15 parts of high-gloss porcelain clay and 20 parts of light calcium carbonate, improving the stirring speed to 700rpm, and stirring for 150 seconds; continuously adding CMC and stirring for 1 minute; adding SA latex and PVAC latex, and stirring for 150 seconds; adding a water repellent agent, and stirring for 480 seconds to obtain the second coating with the solid content of 66.1%.

Respectively carrying out pulp mixing, flow-sending on the surface pulp, the core pulp and the bottom pulp to a net part for molding, and carrying out squeezing, pre-drying, sizing, post-drying and hard calendering to obtain base paper;

The primary coating and the secondary coating are respectively carried out on the front surface of the base paper for 2 times.

Drying after coating is completed, wherein the drying adopts a hot air box drying technology and an infrared drying technology

And (5) carrying out soft calendaring after drying, and regulating moisture by a state regulating cylinder to enter coiling to obtain the coated white cardboard.

The amount of paint used for the pre-coat and top coat was 11.8g/m ²、8.1g/m², respectively.

The first paint and the second paint prepared in example 1 and comparative examples 1 to 2 were subjected to performance test, and the water retention value was measured using an AA GWR 250 paint water retention meter, and the results are shown in table 1,

TABLE 1 detection of Performance index of coatings in examples 1-3 of the present invention

As can be seen from Table 1, the water retention values of both the first coating material and the second coating material of example 1 of the present invention were significantly increased as compared to the comparative example.

The air permeability of the coated white cardboard in the test examples and comparative examples was measured according to GB/T458-2008 determination of air permeability of paper and cardboard, and the ink absorption rate of the coated white cardboard in the examples and comparative examples was measured using a printability tester IGT AIC 2-5. The results are shown in Table 2.

TABLE 2 physical indicators of coated white cardboard prepared in examples 1 to 3 of the present invention

As can be seen from Table 2, the air permeability of the coated white cardboard prepared in the example of the present invention is improved, and the ink absorbing capacity is improved (the larger the ink absorbing rate detection value is, the slower the ink absorbing rate/capacity is, the smaller the ink absorbing rate detection value is, the faster the ink absorbing rate/capacity is.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The coating white cardboard comprises white cardboard base paper, and a first coating and a second coating which are sequentially compounded on the surface of the white cardboard base paper;

the first coating is prepared from a first coating, and the first coating comprises the following components in parts by weight:

Heavy calcium carbonate: 85-95 parts; kaolin: 5-15 parts of sodium carboxymethyl cellulose: 0.1 to 1 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.05 to 0.5 part;

The second coating is prepared from a second coating, and the second coating comprises the following components in parts by weight:

Heavy calcium carbonate: 60-70 parts of kaolin: 5-20 parts of sodium carboxymethyl cellulose: 0.05 to 0.5 part of styrene-acrylic latex: 5-10 parts of polyvinyl acetate latex: 5-10 parts of light calcium carbonate: 10-25 parts of dispersing agent: 0.05 to 0.5 part of defoamer: 0.05 to 0.5 part of water repellent agent: 0.1 to 1 part.

2. The coated white cardboard of claim 1, wherein the light calcium carbonate has an average particle diameter of 0.3 to 0.5 μm, a particle ratio of 99% of particles having a particle diameter of 2 μm or less, and has a rod-like structure with an aspect ratio of (3 to 20): 1, the specific surface area is less than 12m ²/g.

3. The coated white cardboard of claim 2, wherein the light calcium carbonate has an oil absorption value of 60-90 mL/100g.

4. The coated white cardboard of claim 1, wherein the polyvinyl acetate latex has a particle size of 280 to 320nm and the styrene-acrylic latex has a particle size of 120 to 140nm.

5. The coated white cardboard of claim 1, wherein the white cardboard base comprises a bottom layer, a core layer, and a face layer, the face layer being in contact with the first coating layer.

6. The method for preparing the coated white cardboard with the ink set-off prevention function according to claim 1, comprising the following steps:

a) Sequentially coating the surface of the white cardboard base paper with the first coating and the second coating, and drying to obtain a semi-finished product;

b) And carrying out soft calendering and curling on the semi-finished product to obtain the coated white cardboard.

7. The method of claim 6, wherein the first coating is prepared by:

Stirring part of heavy calcium carbonate in water at a rotating speed of 300-500 rpm, adding sodium hydroxide solution, a dispersing agent and a defoaming agent, increasing the stirring rotating speed to 600-800 rpm, continuously adding the rest of heavy calcium carbonate and calcined china clay, stirring for 180-240 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring rotating speed to 900-1200 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 140-160 s, adding a water-resisting agent, and stirring for 480-600 s to obtain the first coating.

8. The method according to claim 7, wherein the solid content of the first coating material is 60 to 70%, and the coating amount of the first coating material is 11.5 to 12.5g/m ².

9. The method of claim 6, wherein the second coating is prepared by:

Stirring part of heavy calcium carbonate in water at a rotating speed of 300-500 rpm, adding sodium hydroxide solution, a dispersing agent and a defoaming agent, continuously adding the rest of heavy calcium carbonate, high-gloss porcelain clay and light calcium carbonate, increasing the stirring rotating speed to 600-800 rpm, stirring for 150-180 s, adding sodium carboxymethyl cellulose, stirring for 1-5 min, increasing the stirring rotating speed to 900-1200 rpm, adding styrene-acrylic latex and polyvinyl acetate latex, stirring for 150-240 s, adding a water-resistant agent, and stirring for 480-600 s to obtain the second coating.

10. The method according to claim 6, wherein the second coating material has a solid content of 60 to 70% and a coating amount of 8 to 9g/m ².