Preparation method and application of polymethylacrylic acid fluoride-free oil-proof paper base

Abstract

The invention relates to the technical field of oil-proof materials, in particular to a preparation method and application of a polymethylacrylic acid fluoride-free oil-proof paper base. Comprising the following steps: uniformly mixing a methacrylate monomer, an initiator, an emulsifier and a cross-linking agent under an anaerobic condition, so that the methacrylate monomer is subjected to an emulsion polymerization reaction, and the polymethacrylate oil-proofing agent is obtained, the preparation method comprises the following steps: uniformly mixing a polymethacrylate oil-proof agent with paper pulp, pulping, carrying out suction filtration, dehydrating, and carrying out dry pressing molding to obtain the polyacrylic acid fluoride-free oil-proof paper base. The fluoride-free oil-proof agent is directly added into the paper pulp, an additional coating device is omitted, and the production cost is effectively reduced. The polymethylacrylic acid fluoride-free oil-proof paper base prepared by the invention is applied to bagasse paper-based molded tableware, and has good water and oil resistance, and the oil-proof effect can achieve the effect of no permeation at the temperature of 85 DEG C.

Description

Technical Field

[0001] The invention relates to the technical field of oil-proof materials, and in particular to a preparation method and application of a polymethacrylic acid fluorine-free oil-proof paper base. Background Art

[0002] Pulp molded tableware uses plant pulp or wood pulp such as bagasse, corn stalks, and reeds as the main raw materials, which fully improves the utilization rate of crops, is low-priced, recyclable, and easily degradable. However, due to the large number of loose pores inside the paper-based material itself, it does not have good waterproof and oil-proof properties, which greatly limits its application. In order to make paper-based materials more widely used, their waterproof and oil-proof properties must be improved.

[0003] To improve this property, pulp molded tableware can be coated with an oil-proof film on the surface of the tableware to achieve a waterproof and oil-proof effect, while making the surface of the tableware smoother. However, the oil-proof film coating of this treatment method may be uneven, especially on tableware with complex shapes, and it is easy to wear during use. After the surface is worn, the tableware will lose its oil resistance. In addition, since the coating process is after the pulp molded tableware is formed, additional equipment and steps are required, which will significantly increase the production cost.

[0004] At present, oil repellents mainly include fluorine-containing oil repellents and fluorine-free oil repellents. Fluorine-containing oil repellents are often perfluorinated and polyfluorinated alkyl compounds, containing stable CF bonds, with good water and oil resistance, durability, and difficult to wet. They can significantly reduce the surface tension of paper-based materials, but fluorine-containing materials used in tableware may pose food safety risks. Common fluorine-free oil repellents include bio-based, silicone and polyacrylate. Bio-based oil repellents are mainly chitosan-based, with high raw material costs and poor oil repellency. Chitosan has high viscosity, which is not conducive to industrial production, and requires additional purchase of production equipment, increasing production costs; silicone oil repellents are mostly used for waterproofing, and their oil repellency is far inferior to their waterproofing effect, and the price of silicon-containing monomers is relatively high, which limits the large-scale production of fluorine-free oil repellents in production workshops, making it difficult to achieve widespread use. Summary of the invention

[0005] The present invention aims to overcome the defects in the prior art that the coating process of pulp molded tableware is complicated and the cost of the fluorine-free oil-proof agent that can be used for pulp molded tableware is relatively high. A preparation method and application of a polymethacrylic acid fluorine-free oil-proof paper base are proposed to overcome the above defects.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical solutions: A method for preparing a polymethacrylic acid fluorine-free oil-proof paper base comprises the following steps: S1. Under anaerobic conditions, methacrylate monomer, initiator, emulsifier and cross-linking agent are uniformly mixed to allow the methacrylate monomer to undergo emulsion polymerization to obtain a polymethacrylate oil repellent; S2. The polymethacrylate oil-proof agent is mixed evenly with paper pulp, and the polymethacrylate fluorine-free oil-proof paper base is obtained by pulping, filtering, dehydrating and dry pressing.

[0007] Preferably, the methacrylate monomer in step S1 includes octadecyl methacrylate. An oil-proofing agent is mixed into the pulp, and the oil-proofing agent needs to be evenly dispersed in the pulp to ensure that each part of the prepared paper base has oil-proof properties. And because the preparation of the paper base requires dehydration, the oil-proofing agent needs to have good adhesion. Stearyl Methacrylate (SMA) is a methacrylate monomer with a long-chain alkyl group. The presence of the long-chain alkyl group makes the viscosity of stearyl methacrylate higher than that of other short-chain methacrylates, so that stearyl methacrylate can significantly increase the adhesion of the oil-proofing agent. In addition, stearyl methacrylate can form crosslinks between fibers, thereby increasing the strength and toughness of the paper base and improving its mechanical properties.

[0008] As further preferred, the methacrylate monomer in step S1 further comprises one or more combinations of hydroxyethyl methacrylate, ethyl methacrylate, methacryloyloxypropyl tris(trimethylsiloxy)silane, and diethylaminoethyl methacrylate.

[0009] As a further preferred embodiment, the mass ratio of octadecyl methacrylate in the methacrylate monomer is 1.2-2:3. As a hydrophobic monomer, octadecyl methacrylate may interfere with the hydrogen bonding between cellulose fibers when in excess, resulting in reduced strength and burst resistance of paper.

[0010] Preferably, the cross-linking agent in step S1 is glycidyl methacrylate.

[0011] Preferably, the emulsifier in step S1 includes one or more combinations of polysorbate 80, Span 80 and sodium dodecylbenzene sulfonate.

[0012] Preferably, the initiator in step S1 is 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride.

[0013] Preferably, the reaction time of the emulsion polymerization reaction in step S1 is 6-8 h.

[0014] Preferably, the pulp in step S2 is bagasse pulp.

[0015] On the other hand, the present invention discloses a fluorine-free and oil-proof paper base prepared by the above method, and its application in paper-based molded tableware.

[0016] Therefore, the present invention has the following beneficial effects: (1) The present invention obtains a polymethacrylate oil repellent by emulsion polymerization of methacrylate monomers in an oxygen-free environment. The synthesized fluorine-free oil repellent has lower raw material cost than silicone oil repellent and is more resistant to high temperatures than bio-based oil repellent.

[0017] (2) The present invention directly adds the fluorine-free oil-proofing agent into the pulp, eliminating the need for an additional coating device and effectively reducing production costs.

[0018] (3) The polymethacrylic acid fluorine-free oil-proof paper base prepared by the present invention is used in bagasse paper-based molded tableware, and has good water and oil resistance, and the oil resistance effect can reach 85°C without penetration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a curve diagram showing the relationship between the monomer conversion rate and the reaction time during the polymerization reaction in Example 1 of the present invention.

[0020] Figure 2 This is the particle size distribution diagram of the polymethacrylate oil-proofing agent in Example 1.

[0021] Figure 3 This is a schematic diagram for comparing oil-proof performance tests. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further clearly and completely described below through specific examples and in combination with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given, but they are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The experimental methods used in the following embodiments are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the embodiments, unless otherwise specified, can be obtained from commercial channels.

[0023] In the preparation method of a polymethacrylate fluorine-free oil-proof paper base of the present invention, the preparation of the polymethacrylate oil-proof agent comprises the following steps: (1) Preparation of PVA aqueous solution: Take 1-5 parts of polyvinyl alcohol and 95-99 parts of deionized water, mix thoroughly under the action of a magnetic stirrer to prepare a 1-5% PVA aqueous solution; (2) 40-90 parts of (meth)acrylate monomer and 1-5 parts of Span 80 are added to a monomer tube to obtain an oil phase solution, and nitrogen bubbling is performed to deoxygenate the solution; (3) 100-200 parts of PVA aqueous solution, 1-5 parts of polysorbate 80, and 0-0.5 parts of SDBS are added to a conical flask to obtain an aqueous phase solution, and nitrogen is bubbled through the solution to deoxygenate it; (4) Add 1-2 parts of 2,2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride initiator into a three-necked flask for deoxygenation, then add water phase and oil phase, set the reaction temperature to 25-50°C, and react at a stirring speed of 200-500 r / min for 4-10 hours; After the reaction is completed, the emulsion is naturally cooled and filtered to obtain a stable polymethacrylate oil-proofing agent.

[0024] The characterization test method in the embodiment of the present invention is as follows: Determination of reaction conversion rate (Conv.%): Conv.%=(S2 / S1)*100%. In the above formula, S1 is the solid content of the solution before the reaction, and S2 is the solid content of the emulsion after the polymerization reaction.

[0025] Determination of particle size of polymethacrylate oil-proofing agent: dilute the polymethacrylate emulsion 50-100 times with deionized water, and measure the particle size of the emulsion with a laser nanoparticle size analyzer.

[0026] Example 1 13 g of octadecyl methacrylate (the ratio of the total monomers is 3:7), 15 g of glycidyl methacrylate, 1 g of hydroxyethyl methacrylate, and 1.9 g of Span 80 are put into a monomer tube to obtain an oil phase, which is then vacuumed and nitrogen-bubbled to deoxygenate; 0.1 g of polysorbate 80 and 70 g of 2.5% PVA aqueous solution were placed in a conical flask to obtain an aqueous phase, which was then vacuumed and nitrogen-bubbled to deoxygenate. 0.45g of initiator 2.2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride was added to a three-necked reaction bottle, and nitrogen was bubbling to deoxygenate, and then oxygen-free water phase and oil phase were added, the reaction temperature was set to 39°C, the stirring speed was 300r / min, the reaction was performed for 8h, and the polymethacrylate fluorine-free oil-proofing agent was obtained after natural cooling and filtration. The polymethacrylate fluorine-free oil-proofing agent was added to the bagasse pulping liquid, and the polymethacrylate fluorine-free oil-proofing paper base was obtained after pulping, suction filtration, dehydration, and dry pressing.

[0027] During the reaction, samples were taken at different time points to determine the monomer conversion rate, and the relationship curve between the emulsion polymerization conversion rate and time was drawn. Figure 1As shown, the particle size of the polymethacrylate fluorine-free oil-proofing agent emulsion was measured by a laser nanoparticle size analyzer. Figure 2 shown.

[0028] Example 2 The ratio of octadecyl methacrylate to the total monomers is 4:6. The composition and weight proportion of the polymerization raw materials are as follows: 20g octadecyl methacrylate, 5g glycidyl methacrylate, 3g hydroxyethyl methacrylate, 2g diethylaminoethyl methacrylate, 0.4g Span 80, 0.9g polysorbate 80, 0.3g SDBS, 75g 2.5% PVA aqueous solution, 0.45g initiator 2.2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride, reaction temperature 39°C, reaction speed 300r / min, reaction time 6h, and other preparation steps are the same as those in Example 1.

[0029] The characterization test results show that the solid content of the polymethacrylate fluorine-free oil-proof agent is 28.7%, the conversion rate of the polymerization reaction is 91.6%, and the average particle size of the obtained polyacrylate fluorine-free oil-proof agent is 267nm.

[0030] Comparative Example 1 The ratio of octadecyl methacrylate to the total monomers is 5:6. The composition and weight proportion of the polymerization raw materials are as follows: 25g octadecyl methacrylate, 5g glycidyl methacrylate, 0.4g Span 80, 0.9g polysorbate 80, 0.3g SDBS, 75g 2.5% PVA aqueous solution, 0.45g initiator 2.2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride, reaction temperature 39°C, reaction speed 300r / min, reaction time 6h, and other preparation steps are the same as those in Example 1.

[0031] The characterization test results show that the solid content of the polymethacrylate fluorine-free oil-proof agent is 28.8%, the conversion rate of the polymerization reaction is 90.7%, and the average particle size of the obtained polyacrylate fluorine-free oil-proof agent is 317nm.

[0032] Comparative Example 2 The ratio of octadecyl methacrylate to the total monomers is 1:3. The composition and weight proportion of the polymerization raw materials are as follows: 10g octadecyl methacrylate, 5g glycidyl methacrylate, 10g methacryloyloxypropyl tris(trimethylsiloxy)silane, 3g hydroxyethyl methacrylate, 2g diethylaminoethyl methacrylate, 0.4g Span 80, 0.7g polysorbate 80, 0.2g SDBS, 60g 2.5% PVA aqueous solution, 0.45g initiator 2.2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride, reaction temperature 39°C, reaction speed 300r / min, reaction time 4h, and other preparation steps are the same as those in Example 1.

[0033] The characterization test results show that the solid content of the polymethacrylate fluorine-free oil-proof agent is 29.5%, the conversion rate of the polymerization reaction is 81.4%, and the average particle size of the obtained polyacrylate fluorine-free oil-proof agent is 334 nm.

[0034] Comparative Example 3 The ratio of octadecyl methacrylate to the total monomers is 1:6. The composition and weight proportion of the polymerization raw materials are as follows: 5g octadecyl methacrylate, 15g methacryloyloxypropyl tris(trimethylsiloxy)silane, 5g glycidyl methacrylate, 3g hydroxyethyl methacrylate, 2g diethylaminoethyl methacrylate, 0.4g Span 80, 0.8g polysorbate 80, 65g 2.5% PVA aqueous solution, 0.45g initiator 2.2'-azobis-[2-(2-imidazoline)-2-yl)propane] dihydrochloride, reaction temperature 39°C, reaction speed 300r / min, reaction time 6h, and other preparation steps are the same as those in Example 1.

[0035] The characterization test results show that the solid content of the polymethacrylate fluorine-free oil-proof agent is 22.2%, the conversion rate of the polymerization reaction is 67.9%, and the average particle size of the obtained polyacrylate fluorine-free oil-proof agent is 412nm.

[0036] The above tableware was subjected to oil resistance test. Hot oil at 95±5℃ was added and left to stand for 6 hours at room temperature to observe whether the surface of the tableware was wrinkled or deformed, whether there were stains on the back of the tableware, and whether there was liquid leakage. The test results were as follows: Figure 2 As shown. According to the test, the emulsion synthesized by oil-water ratio greater than 1:2 has better oil-proof effect when the solid content is above 35%, and its oil-proof effect can last for more than 6 hours without penetration.

[0037] Then, acid resistance test was conducted: hot oil at about 85°C was dripped onto the paper base prepared above, and the oil stains on the back were observed and the penetration time was observed. The test results are shown in Table 1: The results are as follows Figure 3 As shown, the paper bases of Examples 1 and 2 have good oil resistance. The content of octadecyl methacrylate in Comparative Example 1 is too high, and the content of octadecyl methacrylate in Comparative Example 3 is too low, and the oil resistance is significantly reduced. Due to the short reaction time, the oil resistance effect of Comparative Example 2 is poor.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a polymethacrylic acid fluorine-free oil-proof paper base, characterized in that: The steps include: S1. Under anaerobic conditions, methacrylate monomer, initiator, emulsifier and cross-linking agent are uniformly mixed to allow the methacrylate monomer to undergo emulsion polymerization to obtain a polymethacrylate oil repellent; S2. The polymethacrylate oil-proof agent is mixed evenly with paper pulp, and the polymethacrylate fluorine-free oil-proof paper base is obtained by pulping, filtering, dehydrating and dry pressing.

2. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: In step S1, the methacrylate monomer includes octadecyl methacrylate.

3. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 2, characterized in that: The methacrylate monomer in step S1 further includes one or more of hydroxyethyl methacrylate, ethyl methacrylate, methacryloyloxypropyl tris(trimethylsiloxy)silane, and diethylaminoethyl methacrylate.

4. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 3, characterized in that: The mass ratio of the octadecyl methacrylate in the methacrylate monomer is 1.2-2:

3.

5. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: The cross-linking agent in step S1 is glycidyl methacrylate.

6. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: The emulsifier in step S1 includes one or more combinations of polysorbate 80, Span 80 and sodium dodecylbenzene sulfonate.

7. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: The initiator in step S1 is 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride.

8. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: The reaction time of the emulsion polymerization reaction in step S1 is 6-8 h.

9. The method for preparing a polymethacrylic acid fluorine-free oil-proof paper base according to claim 1, characterized in that: The pulp in step S2 is bagasse pulp.

10. Use of the fluorine-free oil-proof paper base prepared according to any one of claims 1 to 9 in paper-based molded tableware.

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