Method for preparing packaging paper bag

Abstract

The invention discloses a method for preparing a packaging paper bag, belonging to the technical field of packaging material preparation, and comprising the following steps: (1) preparing a methyl methacrylate polymerization system and a polyurethane polymerization system respectively and mixing them; (2) using carboxylated nano-silicon dioxide as a raw material, sequentially grafting an alkyl chain and a siloxane chain to obtain modified silicon dioxide; (3) mixing the modified silicon dioxide with the mixed polymerization system and then spraying the mixture on a base paper to obtain the packaging paper bag; the packaging paper bag of the invention has good waterproof and oil-proof properties, and the coating has good flexibility and wear resistance, which can meet the application of the packaging paper bag in various fields.

Description

Technical Field

[0001] The invention relates to the technical field of packaging material preparation, and in particular to a method for preparing a packaging paper bag. Background Art

[0002] Packaging paper bags have the characteristics of wide raw material sources, easy processing, easy degradation and recycling, etc. They are increasingly welcomed by consumers and the market in the packaging field, and have considerable and sustainable development potential in the future. As a packaging material, the fibers in the paper give it a certain strength and structure, and the chemical additives applied in the slurry or coated on the surface can help improve the final printability, mechanical strength and barrier properties of the paper packaging to air, moisture, grease, etc., so as to improve its packaging effect and quality. However, paper is mainly composed of natural plant fibers, and hydrophilic cellulose and hemicellulose are its main chemical components. There are a large number of hydroxyl groups in the molecular structure, which makes the paper structure loose and porous, and has a certain liquid absorption. Therefore, compared with other packaging materials, paper packaging materials have weaker barrier properties to air, water, grease, etc. Therefore, in order to meet the functionality of the paper packaging materials themselves, various modifications and finishing are often required, such as waterproof and oil-proof functions.

[0003] The waterproof and oil-proofing of existing packaging paper materials are mostly carried out separately, so there are not many paper packaging materials with both waterproof and oil-proof functions, which limits their application in certain packaging fields. At the same time, some existing waterproof and oil-proof treatments usually have problems such as weak waterproof and oil-proof performance, mismatch between the coating and the paper base, easy falling off, and poor wear resistance. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for preparing a packaging paper bag.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A method for preparing a packaging paper bag comprises the following steps:

[0007] (1) Weighing methyl methacrylate and dissolving it in an acetone solvent, adding a crosslinking agent and an initiator, and mixing them thoroughly to obtain a solution A; weighing 1,1,1-tri(hydroxymethyl)-propane and dispersing it in a toluene solvent by stirring, adding polytetrahydrofuran, stirring and mixing, and then adding diisocyanate to obtain a solution B; slowly adding the solution A to the solution B under stirring conditions, stirring and mixing thoroughly until uniform, adding an organic tin catalyst, heating to 50-70° C. in a dark environment, and stirring and keeping the temperature for 12-24 hours to obtain a first coating;

[0008] (2) Weigh carboxylated nano-silica and disperse it in tetrahydrofuran solvent, add long-chain diol, adjust the pH value to 1-3, and react at 40-50°C with stirring for 2-8 hours. After the reaction is completed, separate the precipitate, wash it, and disperse it in chloroform solvent. After nitrogen is passed to deoxygenate, add poly(dimethylsiloxane) chloride under protective atmosphere, and react at 30-50°C with stirring for 24-48 hours. After the reaction is completed, separate the precipitate, wash it, and dry it to obtain modified nano-silica;

[0009] (3) The modified nano-silicon dioxide is dispersed in the first coating, sprayed on the base paper after degassing, and dried to obtain the product.

[0010] In some preferred embodiments, the crosslinking agent is trimethylolpropane trimethacrylate.

[0011] In some preferred embodiments, the initiator is azobisisobutyronitrile or dibenzoyl peroxide.

[0012] In some preferred embodiments, the diisocyanate is one or more of toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, and m-xylylene diisocyanate.

[0013] In some preferred embodiments, the mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100: (0.01-0.02): (0.005-0.01).

[0014] In some preferred embodiments, the mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and the diisocyanate is (2-2.5):10:(6.5-7.2).

[0015] In some preferred embodiments, the mass ratio of the solid content of the solution A to the solid content of the solution B and the organic tin catalyst is 1:(1.5-2.2):(0.004-0.01).

[0016] In some preferred embodiments, the mass ratio of the carboxylated nano-silica to the long-chain diol and the poly(dimethylsiloxane) chloride is 1:(0.8-1.3):(0.46-0.82).

[0017] In some preferred embodiments, the main chain of the long-chain diol contains at least 6 carbon atoms and the terminal groups are two hydroxyl groups.

[0018] In some preferred embodiments, the solid content of the first coating is 20-35wt%, the mass volume ratio of the modified nano-silicon dioxide to the first coating is 0.05-0.2g / mL, and the spraying amount of the base paper is 2-25mL / m 2 .

[0019] The beneficial effects of the present invention are:

[0020] In view of the problems in the prior art that the waterproof and oil-proof packaging paper bags have weak waterproof and oil-proof performance and the coating does not match the paper substrate, the present invention provides a method for preparing a packaging paper bag, wherein the packaging paper bag has good waterproof and oil-proof performance, and the coating has good flexibility and wear resistance, which can meet the application of the packaging paper bag in various fields; specifically, the present invention uses hard polymethyl methacrylate to compound soft polyurethane to form a soft and hard alternating interpenetrating polymer network structure, reduces the rigidity of the coating, improves the matching with the paper substrate, gives the coating good flexibility and wear resistance, and also reduces the penetration of water and oil; at the same time, the present invention uses carboxylated nano-silica as a raw material, and sequentially grafts alkyl chains and siloxane chains, which act as synergists to improve the waterproof and oil-proof performance of the coating. DETAILED DESCRIPTION

[0021] The present invention is further described in conjunction with the following examples. Example 1

[0022] A method for preparing a packaging paper bag comprises the following steps:

[0023] (1) Weigh methyl methacrylate and dissolve it in acetone solvent, add a crosslinker and an initiator, and mix thoroughly to obtain solution A; weigh 1,1,1-tri(hydroxymethyl)-propane and disperse it in toluene solvent by stirring thoroughly, add polytetrahydrofuran (molecular weight 1500), stir and mix, and then add toluene-2,6-diisocyanate to obtain solution B, slowly add the solution A to the solution B under stirring conditions, stir and mix thoroughly until uniform, add dibutyltin dilaurate as a catalyst, heat to 55° C. under light-proof conditions, and stir and keep warm for 14 hours to obtain a first coating, wherein the solid content of the first coating is 28wt%;

[0024] The cross-linking agent is trimethylolpropane trimethacrylate;

[0025] The initiator is azobisisobutyronitrile;

[0026] The mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100:0.015:0.007;

[0027] The mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and toluene-2,6-diisocyanate is 2.2:10:6.8;

[0028] The mass ratio of the solid content of the solution A to the solid content of the solution B and the dibutyltin dilaurate is 1:1.8:0.006;

[0029] (2) Weigh carboxylated nano-silica (diameter 50 nm) and disperse it in tetrahydrofuran solvent, add 1,10-decanediol, adjust the pH value to below 3, and react at 45°C with stirring for 6 hours. After the reaction is completed, separate the precipitate, wash it and disperse it in chloroform solvent, add poly(dimethylsiloxane) chloride (CAS No.: 67923-13-1) under protective atmosphere after nitrogen deoxygenation, and react at 40°C with stirring for 30 hours. After the reaction is completed, separate the precipitate, wash it and dry it to obtain modified nano-silica;

[0030] The mass ratio of the carboxylated nano-silica to the 1,10-decanediol and the poly(dimethylsiloxane) chloride is 1:0.9:0.58;

[0031] (3) dispersing the modified nano-silicon dioxide in the first coating, spraying the coating on a base paper after degassing, and drying the coating;

[0032] The mass volume ratio of the modified nano-silicon dioxide to the first coating is 0.12 g / mL, and the spraying amount of the base paper is 5 mL / m 2 . Example 2

[0033] A method for preparing a packaging paper bag comprises the following steps:

[0034] (1) Weigh 1,1,1-tri(hydroxymethyl)-propane and disperse it in toluene solvent with sufficient stirring, add polytetrahydrofuran (molecular weight 1500), stir and mix, then add toluene-2,6-diisocyanate to obtain solution B, add dibutyltin dilaurate as a catalyst, heat to 55°C in a dark environment and stir for 14 hours to obtain a first coating, wherein the solid content of the first coating is 28wt%;

[0035] The mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and toluene-2,6-diisocyanate is 2.2:10:6.8;

[0036] The mass ratio of the solid content of the solution B to the dibutyltin dilaurate is 1.8:0.006;

[0037] (2) Weigh carboxylated nano-silica (diameter 50 nm) and disperse it in tetrahydrofuran solvent, add 1,10-decanediol, adjust the pH value to below 3, and react at 45°C with stirring for 6 hours. After the reaction is completed, separate the precipitate, wash it and disperse it in chloroform solvent, add poly(dimethylsiloxane) chloride (CAS No.: 67923-13-1) under protective atmosphere after nitrogen deoxygenation, and react at 40°C with stirring for 30 hours. After the reaction is completed, separate the precipitate, wash it and dry it to obtain modified nano-silica;

[0038] The mass ratio of the carboxylated nano-silica to the 1,10-decanediol and the poly(dimethylsiloxane) chloride is 1:0.9:0.58;

[0039] (3) dispersing the modified nano-silicon dioxide in the first coating, spraying the coating on a base paper after degassing, and drying the coating;

[0040] The mass volume ratio of the modified nano-silicon dioxide to the first coating is 0.12 g / mL, and the spraying amount of the base paper is 5 mL / m 2 . Example 3

[0041] A method for preparing a packaging paper bag comprises the following steps:

[0042] (1) Weighing methyl methacrylate and dissolving it in acetone solvent, adding a crosslinking agent and an initiator, and mixing them thoroughly to obtain a solution A; obtaining a first coating, wherein the solid content of the first coating is 28 wt %;

[0043] The cross-linking agent is trimethylolpropane trimethacrylate;

[0044] The initiator is azobisisobutyronitrile;

[0045] The mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100:0.015:0.007;

[0046] (2) Weigh carboxylated nano-silica (diameter 50 nm) and disperse it in tetrahydrofuran solvent, add 1,10-decanediol, adjust the pH value to below 3, and react at 45°C with stirring for 6 hours. After the reaction is completed, separate the precipitate, wash it and disperse it in chloroform solvent, add poly(dimethylsiloxane) chloride (CAS No.: 67923-13-1) under protective atmosphere after nitrogen deoxygenation, and react at 40°C with stirring for 30 hours. After the reaction is completed, separate the precipitate, wash it and dry it to obtain modified nano-silica;

[0047] The mass ratio of the carboxylated nano-silica to the 1,10-decanediol and the poly(dimethylsiloxane) chloride is 1:0.9:0.58;

[0048] (3) dispersing the modified nano-silicon dioxide in the first coating, spraying the coating on a base paper after degassing, and drying the coating;

[0049] The mass volume ratio of the modified nano-silicon dioxide to the first coating is 0.12 g / mL, and the spraying amount of the base paper is 5 mL / m 2 . Example 4

[0050] A method for preparing a packaging paper bag comprises the following steps:

[0051] (1) Weigh methyl methacrylate and dissolve it in acetone solvent, add a crosslinker and an initiator, and mix thoroughly to obtain solution A; weigh 1,1,1-tri(hydroxymethyl)-propane and disperse it in toluene solvent by stirring thoroughly, add polytetrahydrofuran (molecular weight 1500), stir and mix, and then add toluene-2,6-diisocyanate to obtain solution B, slowly add the solution A to the solution B under stirring conditions, stir and mix thoroughly until uniform, add dibutyltin dilaurate as a catalyst, heat to 55° C. under light-proof conditions, and stir and keep warm for 14 hours to obtain a first coating, wherein the solid content of the first coating is 28wt%;

[0052] The cross-linking agent is trimethylolpropane trimethacrylate;

[0053] The initiator is azobisisobutyronitrile;

[0054] The mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100:0.015:0.007;

[0055] The mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and toluene-2,6-diisocyanate is 2.2:10:6.8;

[0056] The mass ratio of the solid content of the solution A to the solid content of the solution B and the dibutyltin dilaurate is 1:1.8:0.006;

[0057] (2) The first coating is sprayed on a base paper after degassing, and then dried. Example 5

[0058] A method for preparing a packaging paper bag comprises the following steps:

[0059] (1) Weigh methyl methacrylate and dissolve it in acetone solvent, add a crosslinker and an initiator, and mix thoroughly to obtain solution A; weigh 1,1,1-tri(hydroxymethyl)-propane and disperse it in toluene solvent by stirring thoroughly, add polytetrahydrofuran (molecular weight 1500), stir and mix, and then add toluene-2,6-diisocyanate to obtain solution B, slowly add the solution A to the solution B under stirring conditions, stir and mix thoroughly until uniform, add dibutyltin dilaurate as a catalyst, heat to 55° C. under light-proof conditions, and stir and keep warm for 14 hours to obtain a first coating, wherein the solid content of the first coating is 28wt%;

[0060] The cross-linking agent is trimethylolpropane trimethacrylate;

[0061] The initiator is azobisisobutyronitrile;

[0062] The mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100:0.015:0.007;

[0063] The mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and toluene-2,6-diisocyanate is 2.2:10:6.8;

[0064] The mass ratio of the solid content of the solution A to the solid content of the solution B and the dibutyltin dilaurate is 1:1.8:0.006;

[0065] (2) dispersing nano silicon dioxide in the first coating, spraying the coating on the base paper after degassing, and drying the coating;

[0066] The mass volume ratio of the nano-silicon dioxide to the first coating is 0.12 g / mL, and the spraying amount of the base paper is 5 mL / m 2 .

[0067] The waterproof and oil-proof properties of the sprayed surface of the packaging paper bag described in Examples 1-5 before and after friction were measured, and the contact angle of water droplets on the sprayed surface of the packaging paper bag was observed using a DSA20 video tension contact angle tester, with deionized water and toluene used as test solutions, respectively. The friction was specifically to select 1500-mesh sandpaper, and to wear the coating for a distance of 350 mm at a load of 200g, for a total of 5 times; at the same time, the folding endurance was also tested (refer to GB / T 457-2008, fold 30 times, and observe the coating condition); the test results are shown in the following table.

[0068]

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a packaging paper bag, characterized in that: The following steps are involved: (1) Weighing methyl methacrylate and dissolving it in an acetone solvent, adding a crosslinking agent and an initiator, and mixing them thoroughly to obtain a solution A; weighing 1,1,1-tri(hydroxymethyl)-propane and dispersing it in a toluene solvent by stirring, adding polytetrahydrofuran, stirring and mixing, and then adding diisocyanate to obtain a solution B; slowly adding the solution A to the solution B under stirring conditions, stirring and mixing thoroughly until uniform, adding an organic tin catalyst, heating to 50-70° C. in a dark environment, and stirring and keeping the temperature for 12-24 hours to obtain a first coating; (2) Weigh carboxylated nano-silica and disperse it in tetrahydrofuran solvent, add long-chain diol, adjust the pH value to 1-3, and react at 40-50°C with stirring for 2-8 hours. After the reaction is completed, separate the precipitate, wash it, and disperse it in chloroform solvent. After nitrogen is passed to deoxygenate, add poly(dimethylsiloxane) chloride under protective atmosphere, and react at 30-50°C with stirring for 24-48 hours. After the reaction is completed, separate the precipitate, wash it, and dry it to obtain modified nano-silica; (3) The modified nano-silicon dioxide is dispersed in the first coating, sprayed on the base paper after degassing, and dried to obtain the product.

2. The method for preparing a packaging paper bag according to claim 1, characterized in that: The crosslinking agent is trimethylolpropane trimethacrylate.

3. The method for preparing a packaging paper bag according to claim 1, characterized in that: The initiator is azobisisobutyronitrile or dibenzoyl peroxide.

4. The method for preparing a packaging paper bag according to claim 1, characterized in that: The diisocyanate is one or more of toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, and m-xylylene diisocyanate.

5. The method for preparing a packaging paper bag according to claim 1, characterized in that: The mass ratio of the methyl methacrylate to the crosslinking agent and the initiator is 100: (0.01-0.02): (0.005-0.01).

6. The method for preparing a packaging paper bag according to claim 1, characterized in that: The mass ratio of the 1,1,1-tris(hydroxymethyl)-propane to the polytetrahydrofuran and the diisocyanate is (2-2.5):10:(6.5-7.2).

7. The method for preparing a packaging paper bag according to claim 1, characterized in that: The mass ratio of the solid content of the solution A to the solid content of the solution B and the organic tin catalyst is 1:(1.5-2.2):(0.004-0.01).

8. The method for preparing a packaging paper bag according to claim 1, characterized in that: The mass ratio of the carboxylated nano-silica to the long-chain diol and the poly(dimethylsiloxane) chloride is 1:(0.8-1.3):(0.46-0.82).

9. The method for preparing a packaging paper bag according to claim 1, characterized in that: The main chain of the long-chain diol contains at least 6 carbon atoms and the terminal groups are two hydroxyl groups.

10. The method for preparing a packaging paper bag according to claim 1, characterized in that: The solid content of the first coating is 20-35wt%, the mass volume ratio of the modified nano-silicon dioxide to the first coating is 0.05-0.2g / mL, and the spraying amount of the base paper is 2-25mL / m 2 .

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