An environmentally friendly thermoformed double-sided coated whiteboard paper and its preparation process

Abstract

This invention discloses an environmentally friendly double-sided coated whiteboard paper and its preparation process, comprising the following steps: S1, the coated whiteboard paper is provided with a double-sided coating layer, and the surface of the coating layer on the front side has a region enriched with micron-sized calcium carbonate particles; S2, the double-sided coated whiteboard paper with micron-sized calcium carbonate particles enriched on the surface is printed; S3, blister oil is coated; a single layer of water-based blister oil is applied to the surface of the double-sided coated whiteboard paper with the micron-sized calcium carbonate particle enrichment region and then dried; S4, a thermostatic plastic film is blister-formed to obtain the environmentally friendly double-sided coated whiteboard paper. This invention constructs a rough coating layer by distributing calcium carbonate, and effectively promotes the distribution of blister oil and adhesive in the coating by controlling the difference in the degree of calcium carbonate enrichment along the thickness direction of the coating layer, thereby improving the bonding strength between the blister oil and the coated paper. 。

Description

Technical Field

[0001] This invention relates to the field of thermoformed coated whiteboard paper technology, and in particular to an environmentally friendly thermoformed double-sided coated whiteboard paper and its preparation process. Background Technology

[0002] When packaging and printing companies produce paper blister packaging, they only provide blister paper to customers. The customers then fill the blister packs with the product and use a blister packing machine to heat-seal the blister packs to complete the entire packaging process. The most common quality defect in this type of product is poor blister packaging.

[0003] The invention patent with authorization announcement number CN103993500B discloses a special coated whiteboard paper for blister packaging and its preparation process. The coated whiteboard paper produced through the above embodiments, when the blister packaging is torn open, the interface is damaged at 1 / 2-1 / 3 of the paper layer thickness. The plastic film adheres the paper fibers, resulting in a high success rate of blister packaging. The coating should have a certain porosity to ensure appropriate absorption of blister packaging oil. When the paper absorbs the blister packaging oil well, the oil easily penetrates into the paper structure, resulting in a better blister packaging effect. Conversely, if the paperboard has weak absorption, the ink dries more frequently on the paper surface during printing. When blister packaging oil is applied, it is difficult for the oil to penetrate into the paperboard. In this case, during blister packaging, the blister film picks up the oil film or blister packaging oil on the coating surface, and it is difficult to adhere to the paperboard itself. When the strength of the coating on the whiteboard paper and the bonding strength between the coating and the paper surface are insufficient, more than two-thirds of the paper surface can be torn when the blister pack is removed. However, due to the poor blister packing effect, the damage interface often does not occur between the inner layers of the coated paper. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly method for preparing double-sided coated blister paper. This invention constructs a rough coating layer by distributing calcium carbonate in a specific configuration. By controlling the difference in the enrichment degree of calcium carbonate along the thickness direction of the coating layer, the distribution of blister oil and adhesive in the coating is effectively promoted, thereby improving the bonding strength between the blister oil and the coated paper.

[0005] To solve this technical problem, the technical solution of the present invention is: a preparation process for environmentally friendly thermoforming double-sided coated whiteboard paper, comprising the following steps:

[0006] S1. The coated whiteboard paper has a double-sided coating layer, which includes a base layer and a top layer, wherein the top layer includes a front base layer and a front top layer.

[0007] The surface of the front coating has areas where micron-sized calcium carbonate particles are enriched.

[0008] S2. Double-sided coated whiteboard paper with micron-sized calcium carbonate particles enriched on the printing surface;

[0009] First, inject the I GT standard offset printing ink into the I GT high-speed ink distribution device using an ink syringe with an accuracy of 0.01 ml. The ink is then injected into the ink distribution roller in three separate injections.

[0010] S3, Apply blister coating oil;

[0011] The water-based blister oil, diluted with water and ethanol, was applied in a single layer to the surface of double-sided coated whiteboard paper with micron-sized calcium carbonate particles and then dried.

[0012] S4. Vacuum-formed heat-sensitive plastic film, resulting in environmentally friendly double-sided coated whiteboard paper.

[0013] The pigments in the preferred front coating also include calcium carbonate;

[0014] Calcium carbonate includes precipitated calcium carbonate formed in the slurry during the mixing process and calcium carbonate particles of micron size that participate in the mixing process.

[0015] The micron-sized calcium carbonate particles involved in the mixing include micron-sized calcium carbonate dispersed in the coating slurry and micron-sized calcium carbonate particles that are vibrated and dispersed on the wet front surface coating after the slurry is applied.

[0016] After drying, a micron-sized calcium carbonate particle enrichment area is formed on one side of the shallow coating layer on the front side of the double-sided coated whiteboard paper.

[0017] This invention involves the stepwise addition of micron-sized and nano-sized calcium carbonate particles to the coating surface between coating and drying / calendering. Simultaneously, it establishes a regular stacking of pigment particles within the coating, with nano-calcium carbonate particles filling the gaps between the micron-sized particles to form a more uniform coating structure. This controls the distribution of styrene-butadiene latex, improving printing quality and reducing coating defects. The specific implementation process is as follows: After coating, the invention uses vibratory dispersion of micron-sized calcium carbonate particles on the wet front-side coating surface to create a gradation of nano-calcium carbonate particles and micron-sized calcium carbonate particles. This establishes a regular stacking of pigment particles within the coating, with the nano-calcium carbonate particles filling the gaps between the micron-sized particles to form a more uniform coating structure. By changing the addition order and using a gradation of calcium carbonate particles of different sizes, the invention achieves micron-sized calcium carbonate particles on the coating surface, effectively altering the aggregated structure of the styrene-butadiene latex on the front-side coating. Simultaneously, the in-situ generated nano-calcium carbonate particles in the slurry effectively inhibit the migration and aggregation of styrene-butadiene latex during the drying process. The spherical nano-calcium carbonate particles increase the viscosity of the coating, thereby slowing down the movement of latex particles and helping to prevent their migration and aggregation during drying. Furthermore, the addition of spherical nano-calcium carbonate particles may improve the stability of the coating and reduce potential problems during drying, such as orange peel effect or uneven coating. This invention, by grading the pigment particles, influences porosity formation and adjusts ink absorption properties, contributing to a smooth paper surface, improved printing quality, and reduced coating defects. This invention adds calcium carbonate particles in batches during the coating process. After coating, the addition of micron-sized calcium carbonate introduces a certain interface between the micron-sized calcium carbonate particles and the coating slurry on the coating surface. During the drying process, the calcium carbonate in the top-side coating... The accumulation of calcium micron particles in the shallow layer results in more large pores compared to other areas distributed along the thickness direction towards the surface of the coated paper. This facilitates rapid ink absorption and penetration into the front coating, which is beneficial for subsequent printing. Furthermore, the enrichment of micron-sized calcium carbonate particles in the shallow layer increases the porosity of the shallow layer, enhancing ink absorption performance. It also inhibits the aggregation of styrene-butadiene latex on the coating surface, regulates the distribution of the adhesive, and effectively improves the surface strength of the resulting coated white board paper. The preparation process of this invention also improves coating efficiency and the smoothness of the coating on the resulting double-sided coated white board paper.

[0018] The preferred method is to use micron-sized calcium carbonate particles that are vibrated and dispersed on the surface of a moistened front coating, with polyethylene glycol adsorbed on their surface.

[0019] The preferred method for preparing micron-sized calcium carbonate particles with polyethylene glycol adsorbed on their surface is as follows:

[0020] Polyethylene glycol was dispersed in an aqueous solution, and micron-sized calcium carbonate particles were added to the polyethylene glycol aqueous dispersion. The dispersion was allowed to stand for 30 to 60 minutes, and the polyethylene glycol was adsorbed onto the surface of the micron-sized calcium carbonate particles.

[0021] The mass ratio of polyethylene glycol to micron-sized calcium carbonate particles is (0.1 to 0.2):1.

[0022] This invention utilizes polyethylene glycol, a polar oligomer, adsorbed onto the surface of micron-sized calcium carbonate particles. The polyethylene glycol molecule contains ether oxygen groups (-O-) and hydroxyl groups (-OH), which can form hydrogen bonds or van der Waals forces with the polar groups on the calcium carbonate surface to achieve directional adsorption. The vibrationally dispersed micron-sized calcium carbonate particles on the wetted surface of the coating effectively avoid surface tension changes that cause pinholes due to aggregation of these particles at the shallow surface of the coating. Simultaneously, due to its good water solubility, the polar groups in polyethylene glycol's molecular structure interact with the surface of styrene-butadiene latex particles, reducing surface tension and thus improving dispersibility, further inhibiting the aggregation of styrene-butadiene latex.

[0023] The preferred printing process parameters in S2 are as follows:

[0024] The printing thickness is 2.4μm, and the total ink volume required is 0.1cm. 3 ;

[0025] Apply ink evenly for 10 seconds to ensure uniform distribution of ink on the ink roller; then remove the clean printing roller and apply ink for 5 seconds.

[0026] The printing pressure of the IGT paper brush compatibility tester was set to 625N and the printing speed to 0.2m / s. The ink on the printing roller was transferred to the surface of the double-sided coated white board paper with micron-sized calcium carbonate particles.

[0027] Preferably, the coating material of the front surface layer comprises the following substances in parts by weight:

[0028]

[0029]

[0030] The pigment is calculated in parts by weight of 100, including 30 parts kaolin and 70 parts calcium carbonate;

[0031] The 70 parts of calcium carbonate comprise 10 to 15 parts of precipitated calcium carbonate particles and 15 to 20 parts of micron-sized calcium carbonate particles that are vibrated and dispersed on the wet front surface of the coating after the slurry is applied. The remainder consists of micron-sized calcium carbonate particles directly dispersed in the coating slurry. In this invention, the precipitated calcium carbonate particles include spherical nano-calcium carbonate particles and spherical micron-sized calcium carbonate particles. The spherical nano-calcium carbonate particles not only effectively promote the dispersion of calcium carbonate in the coating, but also, especially, effectively disperse between the micron-sized calcium carbonate nano-particles and kaolin particles, thus promoting the dispersion of the ink. In this invention, spherical calcium carbonate particles generated in situ in the slurry and micron-sized calcium carbonate particles distributed on the shallow surface of the coating layer form an orderly distribution. This improves the regularity of pigment particle distribution in the resulting coating layer, rather than randomness or uniformity. In particular, the vibration-dispersed micron-sized calcium carbonate particles are evenly and controllably distributed on the shallow surface of the resulting coated white cardboard, resulting in a uniform and consistent surface. The shallow surface of the front coating layer obtained by this invention, due to the uniform dispersion of micron-sized calcium carbonate particles, facilitates the formation of large pores for ink absorption and penetration, thereby accelerating ink absorption. It also facilitates the penetration of water-based blister oil along the gaps formed by the pigment particles into the coating layer and the coated paper, enhancing the strong adhesion between the blister shell and the front coating layer and the coated paper.

[0032] The preferred method for preparing the front surface coating includes the following steps:

[0033] S11. Dissolve sodium tripolyphosphate and sodium carboxymethyl cellulose in a 0.2 mol / L calcium chloride aqueous solution and stir until homogeneous;

[0034] S12. Add sodium carbonate solution of equal molar amount to calcium chloride aqueous solution to the mixture obtained in S11 to obtain spherical calcium carbonate particles, wherein the precipitated calcium carbonate includes micron-sized precipitated calcium carbonate particles and nano-sized precipitated calcium carbonate particles.

[0035] S13. Mix polyvinyl alcohol, kaolin, and defoamer evenly according to the stated mass fractions;

[0036] S14. Add deionized water to adjust the solid content of the resulting coating to obtain the target coating.

[0037] This invention controls the amount of sodium carboxymethyl cellulose and sodium tripolyphosphate, wherein sodium carboxymethyl cellulose chelates calcium ions to form uniform micron-sized spherical particles; sodium tripolyphosphate promotes the precipitation of calcium carbonate into spherical nano-calcium carbonate particles, thereby achieving a gradation of micron-sized and nano-sized particles and introducing nano-sized spherical calcium carbonate particles into the slurry.

[0038] Preferably, the concentration of sodium carboxymethyl cellulose in S11 is 0.5 g / L to 0.75 g / L, and the concentration of sodium tripolyphosphate is 0.75 g / L to 1.0 g / L. This invention controls the gradation of spherical calcium carbonate and the viscosity of the resulting slurry by controlling the amounts of sodium carboxymethyl cellulose and sodium tripolyphosphate.

[0039] The preferred drying process conditions in step S3 are as follows:

[0040] The drying temperature is 75℃, and the speed of the drying belt is 2.5cm / s.

[0041] Another objective of this invention is to provide an environmentally friendly double-sided coated whiteboard paper for blister packaging. This invention effectively strengthens the connection between the blister shell and the coated whiteboard paper by controlling the distribution of calcium carbonate and styrene-butadiene latex, while ensuring that the coated whiteboard paper is suitable for coating with water-based blister oil.

[0042] To solve this technical problem, the technical solution of the present invention is: the environmentally friendly thermoforming double-sided coated whiteboard paper prepared by the above-mentioned preparation process.

[0043] By adopting the above technical solution, the beneficial effects of the present invention are:

[0044] This invention features a region rich in micron-sized calcium carbonate particles distributed on the shallow surface of the front coating of double-sided coated whiteboard paper. This promotes the penetration of printing ink and blister oil into the coating and coated paper due to the presence of these micron-sized calcium carbonate particles, resulting in an environmentally friendly double-sided coated whiteboard paper that is easy to blister form. The invention enriches the front coating layer with micron-sized calcium carbonate particles, creating larger channels and ensuring that the resulting front coating has uniform micron-sized calcium carbonate particles. This front coating of the resulting double-sided coated whiteboard paper not only avoids the impact of styrene-butadiene latex aggregation on the wetting of ink and water-based blister oil, but also effectively improves the bonding strength between the blister shell and the coated whiteboard paper. Attached Figure Description

[0045] Figure 1 This invention relates to a cross-sectional structural diagram of an environmentally friendly thermoforming double-sided coated whiteboard paper coated with a front-side coating slurry containing unvibrated F-CaCO3 particles.

[0046] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0047] Figure 3 yes Figure 2 A schematic diagram showing the state in which F-CaCO3 particles are evenly distributed at position A.

[0048] In the picture:

[0049] Bottom layer 100; Top layer 200; Coated base paper 300; Front low coating 210; Front top coating 220; Kaolin 1; Calcium carbonate particles 2; D-CaCO3 particles 21; Nano precipitated calcium carbonate particles 211; Micron precipitated calcium carbonate particles 212; F-CaCO3 particles 22; H-CaCO3 particles 23. Detailed Implementation

[0050] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0051] Example 1

[0052] This embodiment discloses a preparation process for environmentally friendly thermoformed double-sided coated whiteboard paper, including the following steps:

[0053] S1. The coating base paper 300 of the coated whiteboard paper is provided with a double-sided coating layer. The double-sided coating layer includes a bottom layer 100 and a top layer 200. The top layer 200 includes a front bottom coating layer 210 and a front top coating layer 220. The surface of the front top coating layer has a region that forms micron-sized calcium carbonate particles.

[0054] The method for preparing the front surface coating in this embodiment includes the following steps:

[0055] S11. Dissolve sodium tripolyphosphate and sodium carboxymethyl cellulose in a 0.2 mol / L calcium chloride aqueous solution and stir until homogeneous;

[0056] The concentrations of sodium carboxymethyl cellulose and sodium tripolyphosphate in S11 are detailed in Table 1.

[0057] S12. Add sodium carbonate solution of equal molar amount to calcium chloride aqueous solution to the mixture obtained in S11 to obtain spherical calcium carbonate particles, wherein the precipitated calcium carbonate includes micron-sized precipitated calcium carbonate particles and nano-sized precipitated calcium carbonate particles.

[0058] S13. Mix polyvinyl alcohol, kaolin, and defoamer evenly according to the stated mass fractions;

[0059] S14. Add deionized water to adjust the solid content of the resulting coating to obtain the target coating.

[0060] S2. Double-sided coated whiteboard paper with micron-sized calcium carbonate particles enriched on the printing surface;

[0061] First, inject the I GT standard offset printing ink into the I GT high-speed ink distribution device using an ink syringe with an accuracy of 0.01 ml. The ink is then injected into the ink distribution roller in three separate injections.

[0062] The printing process parameters in S2 are as follows:

[0063] The printing thickness is 2.4μm, and the total ink volume required is 0.1cm. 3 ;

[0064] Apply ink evenly for 10 seconds to ensure uniform distribution of ink on the ink roller; then remove the clean printing roller and apply ink for 5 seconds.

[0065] The printing pressure of the IGT paper brush compatibility tester was set to 625N and the printing speed to 0.2m / s. The ink on the printing roller was transferred to the surface of the double-sided coated white board paper with micron-sized calcium carbonate particles.

[0066] S3, Apply blister coating oil;

[0067] The water-based blister oil, diluted with water and ethanol, was applied in a single layer to the surface of double-sided coated whiteboard paper with micron-sized calcium carbonate particles and then dried.

[0068] The drying process conditions in step S3 are as follows:

[0069] The drying temperature is 75℃, and the speed of the drying belt is 2.5cm / s.

[0070] S4. Vacuum-formed heat-sensitive plastic film, resulting in environmentally friendly double-sided coated whiteboard paper.

[0071] The process parameters for vacuum forming in S4 are as follows:

[0072] The heat sealing time is 1.2 seconds, the upper heat sealing temperature is 150°C, the lower heat sealing temperature is 120°C, and the heat sealing pressure is 7 MPa.

[0073] In this embodiment, the pigment in the front surface coating also includes calcium carbonate;

[0074] Calcium carbonate includes precipitated calcium carbonate formed in the slurry during the mixing process and calcium carbonate particles of micron size that participate in the mixing process.

[0075] The micron-sized calcium carbonate particles involved in the mixing include micron-sized calcium carbonate dispersed in the coating slurry and micron-sized calcium carbonate particles that are vibrated and dispersed on the wet front surface coating after the slurry is applied.

[0076] After drying, a micron-sized calcium carbonate particle enrichment area is formed on one side of the shallow coating layer on the front side of the double-sided coated whiteboard paper.

[0077] The composition, mass fraction, and target viscosity of the coating material for the front surface coating described in this embodiment are shown in Table 1.

[0078] The pigment is calculated in parts by weight of 100, including 30 parts kaolin and 70 parts calcium carbonate;

[0079] Among them, 70 parts of calcium carbonate include precipitated calcium carbonate particles (D-CaCO3), micron-sized calcium carbonate particles directly dispersed in the coating slurry (H-CaCO3), and micron-sized calcium carbonate particles (F-CaCO3) that are vibrated and dispersed on the surface of the wet front coating after the slurry is applied. The specific dosage is shown in Table 1.

[0080] In this embodiment, the micron-sized calcium carbonate particles vibrating and dispersed on the surface of the moistened front coating are adsorbed with polyethylene glycol (PEG400). The preparation method of the micron-sized calcium carbonate particles with adsorbed polyethylene glycol in this embodiment is as follows:

[0081] Polyethylene glycol was dispersed in an aqueous solution, and micron-sized calcium carbonate particles were added to the polyethylene glycol aqueous dispersion. The mixture was allowed to stand for 60 minutes to disperse, and the polyethylene glycol was adsorbed onto the surface of the micron-sized calcium carbonate particles.

[0082] The mass ratios of polyethylene glycol and micron-sized calcium carbonate particles are shown in Table 1.

[0083] The coating material of the front undercoat in this embodiment includes the following substances in parts by weight:

[0084]

[0085] In this embodiment, the water-resistant agent is polyamide resin, and the lubricant is modified oxidized polyethylene polymer.

[0086] This embodiment also discloses a preparation process for the double-sided coated whiteboard paper proposed in this invention, including the following steps:

[0087] A1. Apply a top coat to coated paper with a moisture content below 90%; the top coat coating amount is 10g / m². 2 ;

[0088] A2. Apply a back coating layer to the coated paper that has passed through A2; the coating weight of the back coating layer is 1.5 g / m². 2 ;

[0089] A3. Apply a topcoat layer to the surface of the base coating layer on the front side of the coated paper. The topcoat layer coating amount is 25 g / m². 2 ;

[0090] A4. After coating, micron-sized calcium carbonate particles are vibrated and dispersed in the moist coating of the front coating layer, dried, and calendered to obtain the target double-sided coated whiteboard paper.

[0091] The drying process parameters in step A4 are: drying temperature 50℃.

[0092] Example 2

[0093] The differences between this embodiment and Embodiment 1 are detailed in Table 1.

[0094] Example 3

[0095] The differences between this embodiment and Embodiment 1 are detailed in Table 1.

[0096] Example 4

[0097] The differences between this embodiment and Embodiment 1 are detailed in Table 1.

[0098] Example 5

[0099] The differences between this embodiment and Embodiment 1 are detailed in Table 1.

[0100] Comparative Example

[0101] This comparative example proposes a double-sided coated whiteboard paper, including coated paper and two-sided coatings, the two-sided coatings including a front base coating, a back coating and a front surface coating;

[0102] The pigments in the front coating also include calcium carbonate. The mass ratio of kaolin and calcium carbonate is 30:70, with 100 parts by mass. The micron-sized calcium carbonate particles in this comparative example are commercially available calcium carbonate with specific parameters of D50≤12μm and purity≥98%.

[0103] The coating material of the front surface layer comprises the following substances in parts by weight:

[0104]

[0105] The method for preparing the front surface coating in this embodiment includes the following steps:

[0106] The above components were stirred at a constant speed of 800 r / min for 45 min. Deionized water was added to adjust the solid content of the resulting coating to 60% and the viscosity to 11670 mPa·s, thus obtaining the target coating.

[0107] The front undercoat used in this comparative example is the same as in Example 1.

[0108] The preparation process of the double-sided coated whiteboard paper in this comparative example, and the coating and drying process parameters are the same as in Example 1.

[0109] The vacuum forming process for the double-sided coated whiteboard paper obtained in this comparative example is the same as in Example 1.

[0110] Table 1. Composition and dosage of the front surface coating in Examples 1 to 5 and the comparative examples.

[0111]

[0112] The whiteness, porosity, ink absorption performance, and thermoforming peel strength of the double-sided coated whiteboard paper obtained in Examples 1 to 5 and the comparative example were tested. The porosity was measured using the following method:

[0113] The porosity of the coating was determined using the silicone oil penetration method. Silicone oil penetrated into the coating pores, and excess silicone oil on the surface was wiped off after 2 minutes. The mass of the samples before and after penetration was measured to determine the mass of silicone oil absorbed by the coating. Then, based on the content and density of each component in the coating, the volume of absorbed silicone oil and the total volume of the coating were calculated. The calculation method for the coating porosity is shown below:

[0114] φ = Vimb / Vb * 100%; where φ is the coating porosity, Vimb is the volume of silicone oil absorbed, and m 3 Vb is the volume of the coating, in meters. 3 .

[0115] The method for determining the peel strength of thermoforming is as follows:

[0116] The peel strength of blister packaging refers to the force (i.e., standard load) required to tear the heat-sealed blister packaging. The blister whiteboard paper prepared in Examples 1 to 5 and the comparative example was cut into strips with a length of 10 mm and a width of 15 mm.

[0117] Set the tensile speed to 300 mm / min on the electronic tensile testing machine and measure and record the peel strength.

[0118] Detailed test data are shown in Table 2.

[0119] Table 2 shows the properties of double-sided coated whiteboard paper before and after thermoforming in Examples 1 to 5 and comparative examples.

[0120]

[0121] As shown in Tables 1 and 2, compared to the comparative example where micron-sized lightweight calcium carbonate particles were directly mixed into the slurry, the micron-sized calcium carbonate and kaolin, as micron-sized pigments, are relatively randomly distributed in the coating, exhibiting a random and uniform distribution along the thickness direction of the front-side coating. This means the distribution channels for printing inks and water-based blister packing oil are also uniform from top to bottom. The styrene-butadiene latex, acting as an adhesive, aggregates during the coating drying process, partially blocking the channels at the shallow surface of the front-side coating. This results in lower porosity, ink absorption, and blister packing peel strength compared to the products obtained in Examples 1 to 5. This invention, by controlling the gradation and distribution of calcium carbonate particles, effectively improves ink absorption and porosity, while also influencing the distribution of the styrene-butadiene latex as an adhesive, thereby enhancing the surface strength of the resulting coated whiteboard paper.

[0122] The difference in the amount of F-CaCO3 particles adsorbed with polyethylene glycol in Examples 1 to 5 resulted in different enrichment of calcium carbonate in the shallow layer of the front coating, different aggregation of styrene-butadiene latex, and different distribution of large pores. This led to changes in the whiteness, porosity, ink absorbency, and blister peel strength of the resulting double-sided coated whiteboard paper. F-CaCO3 is micron-sized lightweight calcium carbonate dispersed in a slurry with relatively low solid content through vibration. With the enrichment of F-CaCO3 particles, the shallow layer of the front coating has uniform and regular pigment, and the whiteness of the front of the resulting double-sided coated whiteboard paper is also improved. Furthermore, the adsorption of polyethylene glycol by F-CaCO3 particles inhibits the aggregation of styrene-butadiene latex, thereby promoting a relatively non-aggregated distribution of styrene-butadiene latex in the front coating. This ensures continuous pores for printing inks and water-based blister inks, while retaining relatively large pores or voids in the shallow layer. This allows for sufficient penetration of inks and water-based blister inks, ensuring penetration depth and balancing whiteness and blister peel strength.

Claims

1. A preparation process for an environmentally friendly thermoformed double-sided coated whiteboard paper, characterized in that: Includes the following steps: S1. The coated whiteboard paper is provided with a double-sided coating layer. The double-sided coating layer includes a base layer and a top layer. The top layer includes a front base coating layer and a front top coating layer. The surface of the front top coating layer has a region where micron-sized calcium carbonate particles are enriched. S2. Double-sided coated whiteboard paper with micron-sized calcium carbonate particles enriched on the printing surface; First, inject the IGT standard offset printing ink into the IGT high-speed ink distribution device using an ink syringe with an accuracy of 0.01ml. The ink is then injected into the ink distribution roller in three separate injections. S3, Apply blister coating oil; The water-based blister oil, diluted with water and ethanol, was applied in a single layer to the surface of double-sided coated whiteboard paper with micron-sized calcium carbonate particles and then dried. S4. Vacuum-formed heat-sensitive plastic film, resulting in environmentally friendly double-sided coated whiteboard paper; The pigments in the front coating also include calcium carbonate; Calcium carbonate includes precipitated calcium carbonate formed in the slurry during the mixing process and calcium carbonate particles of micron size that participate in the mixing process. The micron-sized calcium carbonate particles involved in the mixing include micron-sized calcium carbonate dispersed in the coating slurry and micron-sized calcium carbonate particles that are vibrated and dispersed on the wet front surface coating after the slurry is applied. After drying, a micron-sized calcium carbonate particle enrichment area is formed on one side of the shallow coating layer on the front side of the double-sided coated whiteboard paper.

2. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 1, characterized in that: Micron-sized calcium carbonate particles dispersed on the surface of the moistened front coating adsorbed polyethylene glycol.

3. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 2, characterized in that: The preparation method of micron-sized calcium carbonate particles with polyethylene glycol adsorbed on the surface is as follows: Polyethylene glycol was dispersed in an aqueous solution, and micron-sized calcium carbonate particles were added to the polyethylene glycol aqueous dispersion. The dispersion was allowed to stand for 30 to 60 minutes, and the polyethylene glycol was adsorbed onto the surface of the micron-sized calcium carbonate particles. The mass ratio of polyethylene glycol to micron-sized calcium carbonate particles is (0.1 to 0.2):

1.

4. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 1, characterized in that: The printing process parameters in S2 are as follows: The printing thickness is 2.4μm, and the total ink volume required is 0.1cm. 3 ; Apply ink evenly for 10 seconds to ensure uniform distribution of ink on the ink roller; then remove the clean printing roller and apply ink for 5 seconds. The printing pressure of the IGT paper brush compatibility tester was set to 625N and the printing speed to 0.2m / s. The ink on the printing roller was transferred to the surface of the double-sided coated white board paper with micron-sized calcium carbonate particles.

5. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 1, characterized in that: The coating material of the front surface layer comprises the following substances in parts by weight: The coating material of the front surface layer comprises the following substances in parts by weight: 100 parts pigment; 15 to 20 parts of styrene-butadiene latex; 2 to 4 parts polyvinyl alcohol; 0.1 to 0.5 parts of defoamer; The pigment is calculated in parts by weight of 100, including 30 parts kaolin and 70 parts calcium carbonate; The 70 parts of calcium carbonate include 10 to 15 parts of precipitated calcium carbonate particles and 15 to 20 parts of micron-sized calcium carbonate particles that are vibrated and dispersed on the wet front surface coating after the slurry is applied. The remainder consists of micron-sized calcium carbonate particles that are directly dispersed in the coating slurry.

6. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 5, characterized in that: The method for preparing the front surface coating includes the following steps: S11. Dissolve sodium tripolyphosphate and sodium carboxymethyl cellulose in a 0.2 mol / L calcium chloride aqueous solution and stir until homogeneous; S12. Add sodium carbonate solution of equal molar amount to calcium chloride aqueous solution to the mixture obtained in S11 to obtain spherical calcium carbonate particles, wherein the precipitated calcium carbonate includes micron-sized precipitated calcium carbonate particles and nano-sized precipitated calcium carbonate particles. S13. Mix polyvinyl alcohol, kaolin, and defoamer evenly according to the stated mass fractions; S14. Add deionized water to adjust the solid content of the resulting coating to obtain the target coating.

7. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 6, characterized in that: The concentration of sodium carboxymethyl cellulose in S11 is 0.5 g / L to 0.75 g / L, and the concentration of sodium tripolyphosphate is 0.75 g / L to 1.0 g / L.

8. The preparation process of an environmentally friendly thermoformed double-sided coated whiteboard paper as described in claim 1, characterized in that: The drying process conditions in step S3 are as follows: The drying temperature is 75℃, and the speed of the drying belt is 2.5cm / s.

9. An environmentally friendly thermoformed double-sided coated whiteboard paper prepared by the preparation process according to any one of claims 1 to 8.

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