Environment-friendly easy-to-uncover paper cover and preparation method thereof

Abstract

The invention relates to the technical field of food packaging, in particular to an environment-friendly easy-to-uncover paper cover and a preparation method thereof.The environment-friendly easy-to-uncover paper cover sequentially comprises a heat sealing coating, a waterproof coating, a paper base layer and a reinforcing coating, and the heat sealing coating comprises, by mass, 60-70 parts of water-based polyolefin dispersoid and 30-40 parts of acrylic ester; the waterproof coating comprises the following components in parts by mass: 10-30 parts of a waterproof agent and 70-90 parts of an ethanol aqueous solution, and the volume fraction of the ethanol aqueous solution is 50%; the reinforced coating is prepared from the following components in parts by mass: 30 to 40 parts of calcium carbonate, 35 to 50 parts of kaolin, 1 to 2 parts of a water-retaining agent, 12 to 15 parts of styrene-butadiene latex, 5 to 8 parts of water and 0.1 to 0.2 part of pigment. The environment-friendly easy-to-uncover paper cover is not prone to being affected with damp and upwarping and can be recycled through a recycling and repulping process, and the sealing fastness is controllable through the combination of the waterproof coating and the heat sealing coating.

Description

Technical Field

[0001] The invention relates to the technical field of food packaging, and in particular to an environmentally friendly easy-to-peel paper cover and a preparation method thereof. Background Art

[0002] The caps in traditional food packaging are usually made of multi-layer plastic film composite processing and cannot be recycled. When recyclable paper caps are used for sealing, single-piece paper caps are easily affected by environmental humidity, causing deformation and warping, and cannot be successfully produced on large-scale equipment.

[0003] For example, the national invention patent application with application number 202410189420 discloses an easy-to-peel film and a preparation method thereof, wherein the base layer is a polyethylene terephthalate film or a biaxially oriented polypropylene film, and the heat-sealing layer is formed by an ethylene-vinyl acetate copolymer. The easy-to-peel film is a composite of multiple layers of plastic films and cannot be recycled.

[0004] The sealing of existing food packaging is basically achieved by melting the low melting point EVA (ethylene-vinyl acetate copolymer) resin in the inner layer of the cap to seal with the container below. In order to achieve a better sealing effect, a thicker EVA resin layer is often required, and the coating amount is generally 20-40g / m 2 . Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the existing food packaging cover body cannot be recycled and the heat-sealing layer is relatively thick as described in the above background technology. An environmentally friendly easy-to-peel paper cover and a preparation method thereof are proposed. The environmentally friendly easy-to-peel paper cover uses paper as a base layer, and a waterproof coating and a reinforcing coating are coated on the surface to prevent the paper cover from warping and enhance performance. A relatively thin heat-sealing coating is coated on the surface of the waterproof coating to achieve an easy-to-peel effect and controllable sealing strength.

[0006] The technical solution adopted by the present invention to solve the technical problem is: an environmentally friendly easy-to-peel paper cover, which comprises a heat-sealing coating, a waterproof coating, a paper base layer and a reinforcing coating in sequence.

[0007] The heat-sealing coating comprises 60-70 parts by mass of an aqueous polyolefin dispersion and 30-40 parts by mass of an acrylate;

[0008] The waterproof coating comprises 10-30 parts of waterproofing agent and 70-90 parts of ethanol aqueous solution by mass, and the volume fraction of the ethanol aqueous solution is 50%;

[0009] The reinforcing coating comprises the following components by weight: 30-40 parts of calcium carbonate, 35-50 parts of kaolin, 1-2 parts of water retaining agent, 12-15 parts of styrene-butadiene latex, 5-8 parts of water and 0.1-0.2 parts of pigment.

[0010] Preferably, the heat-seal coating comprises 63-68 parts of aqueous polyolefin dispersion and 33-48 parts of acrylate by weight, more preferably 65 parts of aqueous polyolefin dispersion and 35 parts of acrylate;

[0011] The waterproof coating comprises 20 parts of waterproofing agent and 80 parts of ethanol aqueous solution by mass, and the volume fraction of the ethanol aqueous solution is 50%;

[0012] The reinforcing coating comprises the following components by weight: 40 parts of calcium carbonate, 37.5 parts of kaolin, 1 part of water retaining agent, 15 parts of styrene-butadiene latex, 6.4 parts of water, and 0.1 part of pigment.

[0013] In the above technical scheme, a waterproof coating is added to the heat-sealing side of the paper base layer to control the water absorption of the surface of the paper base layer, so as to prevent the paper base layer from curling up due to moisture, and to ensure that when the heat-sealing coating is applied, the amount of the heat-sealing coating that penetrates into the fibers of the paper base layer is controlled, and the fastness between the paper base layer and the heat-sealing layer is controlled, so as to achieve the sealing strength between the paper cover and the sealed container, and ensure that the sealing is ensured while achieving the effect of easy opening without causing the paper cover or the paper of the sealed container to be torn; the environmentally friendly easy-to-open paper cover of the present invention can adapt to the sealing requirements between different products by adjusting the grammage of the heat-sealing coating.

[0014] Furthermore, the paper base layer is prepared by mixing plant fiber pulp and chemical wood pulp, and the mass ratio of the plant fiber pulp to the chemical wood pulp is (70-80): (20-30).

[0015] Preferably, the mass ratio of the plant fiber pulp to the chemical wood pulp is 73:27.

[0016] In the above technical solution, the cover made of fiber pulp and wood pulp can be reused through a recycling and repulping process, which is more in line with the concept of environmental protection; the use of the above ratio is conducive to synergizing the waterproof coating, controlling the amount of heat-sealing coating penetrating into paper fibers, and controlling the sealing strength.

[0017] Furthermore, the coating amount of the reinforcing coating is 25-35 g / m 2 The coating amount of the waterproof coating is 0.5-3g / m 2 The coating amount of the heat seal coating is 3-8g / m 2 .

[0018] Furthermore, the water retaining agent is sodium carboxymethyl cellulose.

[0019] Furthermore, the waterproofing agent is selected from acrylic latex or styrene acrylic latex.

[0020] In the above technical solution, the waterproofing agent is preferably styrene acrylic latex, which not only has a waterproofing effect, but also can balance the tension on both sides of the paper base layer, and provides a pre-coating treatment for the fastness and cover-opening strength of the subsequent heat-sealing coating.

[0021] Furthermore, the heat sealing temperature of the heat sealing coating is 120-140°C, and the heat sealing pressure is 0.5-7kg / cm 2 , heat sealing time is 0.02-1.0S.

[0022] A method for preparing the environmentally friendly easy-to-peel paper cover as described above, the method comprising the following steps:

[0023] S1. Mix the raw materials of the reinforcing coating and the waterproof coating respectively and apply them on both sides of the paper base;

[0024] S3. Add acrylate to the stirred aqueous polyolefin dispersion, continue stirring for 30-60 minutes, let stand to defoam, and apply it on the surface of the waterproof coating to obtain an environmentally friendly easy-to-peel paper cover.

[0025] Furthermore, in step S1, the reinforcing coating is coated on the surface of the paper base layer twice.

[0026] Furthermore, the coating amount of the first reinforcement coating material is 15-20g / m 2 The coating amount of the second reinforcement coating material is 10-15g / m 2 .

[0027] As a preferred method, the coating amount of the first reinforcement coating material is 18 g / m 2 The coating amount of the second reinforcement coating material is 12g / m 2

[0028] In the above technical solution, the surface gaps and depressions of the pulp-paper base layer are filled in by the first coating, and the second coating increases the flatness and smoothness of the surface of the paper base layer, which greatly improves the surface printing effect of the paper cover.

[0029] Furthermore, the grammage of the paper base layer is 60-130 g / m 2 .

[0030] The beneficial effects of the present invention are:

[0031] 1. The problem of paper cover warping is solved by applying a waterproof coating on the surface of the paper base, ensuring that the paper cover is not affected by changes in humidity in the production environment during the sealing process.

[0032] 2. Use paper base to replace plastic film to realize the recycling and re-pulping of paper cover. The scraps in the production of paper cover or the paper cover pieces recovered after use can be directly put into the cardboard recycling system for pulping and papermaking.

[0033] 3. The sealing strength can be controlled by adjusting the coating amount of the heat-sealing coating and the waterproof coating. Paper covers with different proportions can be designed according to the final practical scenarios of the product to meet different terminal needs and achieve a combination of easy-to-open and sealing properties of the paper cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0035] Figure 1 It is a structural schematic diagram of the present invention.

[0036] Illustration: 1. Reinforcement coating, 2. Paper base layer, 3. Waterproof coating, 4. Heat-sealing coating. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] The present invention is now further described in conjunction with specific examples. The following examples are only for explaining the present invention, but do not constitute a limitation of the present invention. The test samples and test processes used in the following examples include the following (if the specific experimental conditions are not indicated in the examples, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, if not otherwise specified, can all be obtained from commercial channels).

[0040] Example 1

[0041] An environmentally friendly easy-to-peel paper cover, which is composed of a heat-sealing coating 4, a waterproof coating 3, a paper base layer 2 and a reinforcing coating 1 from top to bottom. The specific steps of the preparation method are as follows:

[0042] S1. Mix the raw materials of the waterproof coating evenly and apply them on one side of the paper base layer. Mix the raw materials of the reinforcement coating evenly and apply them on the other side of the paper base layer twice.

[0043] S2. Add acrylate to the stirred aqueous polyolefin dispersion, continue stirring for 30 minutes, let stand to defoam, and apply it on the surface of the waterproof coating to obtain an environmentally friendly easy-to-peel paper cover.

[0044] The raw materials of the reinforcing coating consist of the following components by mass fraction: 30 parts of calcium carbonate, 37.5 parts of kaolin, 1 part of sodium carboxymethyl cellulose, 15 parts of styrene-butadiene latex, 6.4 parts of water and 0.1 parts of pigment.

[0045] Calculated by mass fraction, the raw materials of the waterproof coating consist of the following components: 20 parts of styrene acrylic latex and 80 parts of ethanol aqueous solution, and the volume fraction of the ethanol aqueous solution is 50%.

[0046] The raw materials of the heat seal coating consist of the following components by mass fraction: 35 parts of acrylate and 65 parts of aqueous polyolefin dispersion.

[0047] The raw materials of the paper base layer consist of the following components by mass fraction: 73 parts of plant fiber pulp and 27 parts of chemical wood pulp.

[0048] The weight of the paper base is 90g / m 2 The first reinforcement coating amount is 18g / m 2 The second reinforcement coating is 12g / m 2 , the coating amount of heat seal coating is 3g / m 2 , the coating amount of the waterproof coating is 0.5g / m 2 .

[0049] Example 2

[0050] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 3 g / m 2 , the coating amount of the waterproof coating is 2g / m 2 .

[0051] Example 3

[0052] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 3 g / m 2 , the coating amount of the waterproof coating is 3g / m 2 .

[0053] Comparative Example 1

[0054] A paper cover, which is composed of a heat-sealing coating, a paper base layer and a reinforcing coating from top to bottom. The specific steps of the preparation method are as follows:

[0055] S1. Mix the raw materials of the enhanced coating evenly and apply them on one side of the paper base twice;

[0056] S2. Add acrylate to the stirred aqueous polyolefin dispersion, continue stirring for 30 minutes, let stand to defoam, and apply it on the other side of the paper base to obtain a paper cover.

[0057] The raw materials of the reinforcing coating consist of the following components by mass fraction: 30 parts of calcium carbonate, 37.5 parts of kaolin, 1 part of sodium carboxymethyl cellulose, 15 parts of styrene-butadiene latex, 6.4 parts of water and 0.1 parts of pigment.

[0058] The raw materials of the heat seal coating consist of the following components by mass fraction: 35 parts of acrylate and 65 parts of aqueous polyolefin dispersion.

[0059] The raw materials of the paper base layer consist of the following components by mass fraction: 73 parts of plant fiber pulp and 27 parts of chemical wood pulp.

[0060] The weight of the paper base is 90g / m 2 The first reinforcement coating amount is 18g / m 2 The second reinforcement coating is 12g / m 2 , the coating amount of heat seal coating is 3g / m 2 .

[0061] Example 4

[0062] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 6 g / m 2 , the coating amount of the waterproof coating is 0.5g / m 2 .

[0063] Example 5

[0064] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 6 g / m 2 , the coating amount of the waterproof coating is 2g / m 2 .

[0065] Example 6

[0066] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 6 g / m 2 , the coating amount of the waterproof coating is 3g / m 2 .

[0067] Comparative Example 2

[0068] A paper cover, whose composition and preparation method are the same as those of comparative example 1, except that the coating amount of the heat seal coating is 6 g / m 2 .

[0069] Example 7

[0070] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 8 g / m 2 , the coating amount of the waterproof coating is 0.5g / m 2 .

[0071] Example 8

[0072] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 8 g / m 2 , the coating amount of the waterproof coating is 2g / m 2 .

[0073] Example 9

[0074] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those in Example 1, except that the coating amount of the heat-sealing coating is 8 g / m 2 , the coating amount of the waterproof coating is 3g / m 2 .

[0075] Comparative Example 3

[0076] A paper cover, whose composition and preparation method are the same as those of comparative example 1, except that the coating amount of the heat seal coating is 8 g / m 2 .

[0077] Comparative Example 4

[0078] An environmentally friendly easy-to-peel paper cover, which is composed of a heat-sealing coating, a waterproof coating, a paper base layer and a reinforcing coating from top to bottom. The specific steps of the preparation method are as follows:

[0079] S1. Mix the raw materials of the enhanced coating evenly and apply them on one side of the paper base twice;

[0080] S2. Apply a waterproof coating on the other side of the paper base layer, and apply a heat-sealing coating on the surface of the waterproof coating.

[0081] The heat-seal coating is ethylene vinyl acetate copolymer and the waterproof coating is polyethylene.

[0082] The raw materials of the reinforcing coating consist of the following components by mass fraction: 30 parts of calcium carbonate, 37.5 parts of kaolin, 1 part of sodium carboxymethyl cellulose, 15 parts of styrene-butadiene latex, 6.4 parts of water and 0.1 parts of pigment.

[0083] The weight of the paper base is 90g / m 2 The first reinforcement coating amount is 18g / m 2 The second reinforcement coating is 12g / m 2 , the coating weight of heat seal coating is 30g / m 2 , the coating amount of the waterproof coating is 20g / m 2 .

[0084] Comparative Example 5

[0085] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those of comparative example 4, except that the coating amount of the heat-sealing coating is 20 g / m 2 , the coating amount of waterproof coating is 30g / m 2 .

[0086] Example 10

[0087] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those of Example 1, except that: the raw materials of the heat-sealing coating are composed of the following components by mass fraction: 30 parts of acrylate and 70 parts of aqueous polyolefin dispersion.

[0088] Embodiment 11

[0089] An environmentally friendly easy-to-peel paper cover, whose composition and preparation method are the same as those of Example 1, except that: the raw materials of the heat-sealing coating are composed of the following components by mass fraction: 40 parts of acrylate and 60 parts of aqueous polyolefin dispersion.

[0090] The environmentally friendly easy-to-peel paper covers and paper covers prepared in Examples 1-9 and Comparative Examples 1-5 were combined with conventional paper cups for heat sealing, and the initial tearing force and integrity of the cover were tested. The heat sealing pressure was 5 kg / cm 2 , the heat sealing time is 0.3S, and the test results are shown in Table 1.

[0091] The above-mentioned method for detecting the tearing force of the cover is: using a tensile peeling tester, the fixed end tightens the environmentally friendly easy-to-peel paper cover and one end of the paper cover, the sensing end tightens the environmentally friendly easy-to-peel paper cover and the other end of the paper cover, and the parameters are set to a chuck spacing of 150mm and a test speed of 20mm / min.

[0092] Table 1 Environmentally friendly easy-to-peel paper covers prepared in Examples 1-9 and Comparative Examples 1-5 and test results of paper covers

[0093]

[0094]

[0095] It can be seen from Comparative Example 1 and Examples 1-3, Comparative Example 2 and Examples 4-6, and Comparative Example 3 and Examples 7-9 in Table 1 that the tearing force for opening the cover can be changed by controlling the coating amount of the waterproof coating, and the tearing force for opening the cover can be reduced by increasing the coating amount of the waterproof coating, thereby achieving the purpose of easy opening, and the increase of the waterproof coating allows the entire cover to be completely opened without damage.

[0096] From the comparison between Comparative Examples 4 and 5 and Examples 1-9, it can be seen that the use of ethylene vinyl acetate copolymer as a heat seal coating requires coating of 30 g / m 2 The peeling force can reach 12.1N, while the present invention uses styrene acrylic latex as the heat seal coating only needs 3-8g / m 2 The coating amount can achieve the sealing effect and the easy-to-peel effect.

[0097] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0098] The above is a detailed introduction to an environmentally friendly easy-to-peel paper cover and a preparation method thereof provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An environmentally friendly easy-to-peel paper cover, characterized in that: The environmentally friendly easy-to-peel paper cover comprises a heat-sealing coating, a waterproof coating, a paper base layer and a reinforcing coating in sequence. The heat-sealing coating comprises 60-70 parts by mass of an aqueous polyolefin dispersion and 30-40 parts by mass of an acrylate; The waterproof coating comprises 10-30 parts of waterproofing agent and 70-90 parts of ethanol aqueous solution by mass, and the volume fraction of the ethanol aqueous solution is 50%; The reinforcing coating comprises the following components by weight: 30-40 parts of calcium carbonate, 35-50 parts of kaolin, 1-2 parts of water retaining agent, 12-15 parts of styrene-butadiene latex, 5-8 parts of water and 0.1-0.2 parts of pigment.

2. The environmentally friendly easy-to-peel paper cover according to claim 1, characterized in that: The paper base layer is prepared by mixing plant fiber pulp and chemical wood pulp, and the mass ratio of the plant fiber pulp to the chemical wood pulp is (70-80): (20-30).

3. The environmentally friendly easy-to-peel paper cover according to claim 1, characterized in that: The coating amount of the reinforcing coating is 25-35g / m 2 The coating amount of the waterproof coating is 0.5-3g / m 2 The coating amount of the heat seal coating is 3-8g / m 2 .

4. The environmentally friendly easy-to-peel paper cover according to claim 1, characterized in that: The water retaining agent is carboxymethyl cellulose sodium salt.

5. The environmentally friendly easy-to-peel paper cover according to claim 1, characterized in that: The waterproofing agent is selected from acrylic latex or styrene acrylic latex.

6. The environmentally friendly easy-to-peel paper cover according to claim 1, characterized in that: The heat sealing temperature of the heat sealing coating is 120-140°C, and the heat sealing pressure is 0.5-7kg / cm 2 , heat sealing time is 0.02-1S.

7. A method for preparing the environmentally friendly easy-peel paper cover according to claim 1, characterized in that: The preparation method comprises the following steps: S1. Mix the raw materials of the reinforcing coating and the waterproof coating respectively and apply them on both sides of the paper base; S3. Add acrylate to the stirred aqueous polyolefin dispersion, continue stirring for 30-60 minutes, let stand to defoam, and apply it on the surface of the waterproof coating to obtain an environmentally friendly easy-to-peel paper cover.

8. The preparation method according to claim 7, characterized in that: In step S1, the reinforcing coating is coated on the surface of the paper base layer twice.

9. The preparation method according to claim 8, characterized in that: The coating amount of the first reinforcement coating material is 15-20g / m 2 The coating amount of the second reinforcement coating material is 10-15g / m 2 .

10. The preparation method according to claim 7, characterized in that: The grammage of the paper base layer is 60-130 g / m 2 .

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