阅读说明：本技术 一种用于防油纸的丙烯酸乳液、其制备方法与应用 (Acrylic emulsion for oil-proof paper, preparation method and application thereof ) 是由 黄宏存 袁业兴 朱清梅 陈穆伟 于 2021-09-02 设计创作，主要内容包括：本发明提供了防油纸用丙烯酸乳液,其由硬单体、软单体、功能性单体、乳化剂、引发剂、改性剂、消泡剂和软水制备得到；本申请提供的丙烯酸乳液通过选用适合的硬单体、软单体及功能性单体配比,在反应型乳化剂的协同作用下,调节乳液的分子量,提高涂层分子致密性,从而提高涂层的防水防油性能；同时在丙烯酸树脂主链上引入交联改性剂,当丙烯酸乳液涂布干燥成膜时,通过交联改性基团之间的反应,生成具有网状结构的聚合物涂层,提高涂层对防油纸表面的附着力。(The invention provides an acrylic emulsion for oil-proof paper, which is prepared from a hard monomer, a soft monomer, a functional monomer, an emulsifier, an initiator, a modifier, a defoaming agent and soft water; according to the acrylic emulsion provided by the application, the proper proportion of the hard monomer, the soft monomer and the functional monomer is selected, the molecular weight of the emulsion is adjusted under the synergistic effect of the reactive emulsifier, and the molecular compactness of a coating is improved, so that the water and oil resistance of the coating is improved; meanwhile, a crosslinking modifier is introduced into the main chain of the acrylic resin, and when the acrylic emulsion is coated, dried and formed into a film, a polymer coating with a net structure is generated through the reaction between crosslinking modifying groups, so that the adhesive force of the coating to the surface of the oilproof paper is improved.)

1. An acrylic emulsion for oil-proof paper is prepared from the following components:

the hard monomer is selected from one or more of methyl methacrylate, ethyl methacrylate and acrylonitrile;

the soft monomer is selected from one or more of methyl acrylate, ethyl acrylate and n-octyl acrylate.

2. The acrylic emulsion according to claim 1 wherein the functional monomer is selected from one or both of N-methylolacrylic acid and diacetone acrylamide.

3. The acrylic emulsion according to claim 1 wherein said initiator is selected from one or both of ammonium and potassium persulphate.

4. The acrylic emulsion according to claim 1, wherein the emulsifier is one or two selected from sodium acrylamidoisopropyl sulfonate and sodium vinyl acid sulfonate.

5. The acrylic emulsion according to claim 1, wherein the modifier is selected from one or both of potassium hydroxide and sodium hydroxide; the defoaming agent is selected from polyether defoaming agents.

6. The acrylic emulsion according to claim 1, wherein the hard monomer is contained in an amount of 5 to 7.5 wt%.

7. The acrylic emulsion according to claim 1, wherein the soft monomer is contained in an amount of 3 to 5.5 wt%.

8. The acrylic emulsion according to claim 1, wherein the content of the modifier is 8.5 to 10 wt%.

9. The method for preparing the acrylic emulsion for oilproof paper of any one of claims 1 to 8, comprising the steps of:

mixing 5-15 wt% of hard monomer, 3-9 wt% of soft monomer and 1-3 wt% of functional monomer to obtain a mixed monomer;

mixing 6-8 wt% of soft water and 0.5-2 wt% of emulsifier to obtain an emulsifier solution;

mixing 9-12 wt% of soft water and 0.2-1 wt% of an initiator to obtain an initiator solution;

mixing 45-62 wt% of soft water, 20 wt% of mixed monomer, 10 wt% of emulsifier solution and 5 wt% of initiator solution, vacuumizing, heating, and adding the rest of mixed monomer, emulsifier solution and initiator solution into the obtained mixed solution;

and adding 3-10 wt% of modifier and 0.2-0.5 wt% of defoamer into the obtained mixed solution to obtain the acrylic emulsion for the oilproof paper.

10. A composite oil-proof paper, which comprises oil-proof paper and a coating layer, wherein the coating layer is prepared from the acrylic emulsion as defined in any one of claims 1-8 or the acrylic emulsion prepared by the preparation method as defined in claim 9.

Technical Field

The invention relates to the technical field of high polymer materials, in particular to an acrylic emulsion for oil-proof paper, and a preparation method and application thereof.

Background

At present, with the upgrade of plastic forbidden orders, the application field of paper is more and more extensive, and a plurality of paper applications need to have certain oil resistance, such as packaging paper of various foods, outer packaging paper boards, release paper, carbonless copy paper and various art papers. Research and development of novel and efficient oil-proof paper will become the mainstream of development in the field of oil-proof paper.

The oil-proof paper used in the market at present is basically formed by uniformly spraying hot-melt PE plastic particles on the surface of paper, and compared with common paper, the oil-proof paper has the characteristics of water resistance, oil resistance and the like, for example, the high-temperature-resistant oil-proof paper disclosed in patent CN 107738491A. However, after the paper is coated, the waste materials such as disposable paper bowls and paper cups are difficult to be repulped after the PE layer is recovered and separated. If the paper is decomposed naturally, a long time is needed, the environment is greatly polluted, and meanwhile, the paper resource is wasted.

In order to solve the problem of difficult recovery of the coated paper, researches on solving the oil resistance problem of the paper by functional coatings have been started at home and abroad, such as oil-proof paper and a production method thereof related to Chinese patent CN 103669105A; the method is characterized in that an oil-proof coating is coated on base paper, the oil-proof index of the obtained oil-proof paper can reach 7 grades, but the oil-proof coating is added with a plasticizer to improve the oil-proof performance of the paper. The state has clearly regulated that plasticizers cannot be used for processing food products nor are they allowed to be used on food packaging. Aiming at the immaturity of the prior oil-proof coating technology, if a safe and environment-friendly functional oil-proof coating can be developed, the application of the oil-proof paper can be widened to a certain extent.

Disclosure of Invention

The technical problem to be solved by the invention is to provide the acrylic emulsion for the oil-proof paper, which has good water-proof and oil-proof performances and good adhesive force to the oil-proof paper.

In view of the above, the present application provides an acrylic emulsion for oilproof paper, which is prepared from the following components:

the hard monomer is selected from one or more of methyl methacrylate, ethyl methacrylate and acrylonitrile;

the soft monomer is selected from one or more of methyl acrylate, ethyl acrylate and n-octyl acrylate.

Preferably, the functional monomer is selected from one or two of N-hydroxymethyl acrylic acid and diacetone acrylamide.

Preferably, the initiator is selected from one or both of ammonium and potassium persulphate.

Preferably, the emulsifier is selected from one or two of sodium acrylamido isopropyl sulfonate and sodium ethylene acid sulfonate.

Preferably, the modifier is selected from one or two of potassium hydroxide and sodium hydroxide; the defoaming agent is selected from polyether defoaming agents.

Preferably, the content of the hard monomer is 5 to 7.5 wt%.

Preferably, the content of the soft monomer is 3-5.5 wt%.

Preferably, the content of the modifier is 8.5-10 wt%.

The application also provides a preparation method of the acrylic emulsion for the oil-proof paper, which comprises the following steps:

mixing 5-15 wt% of hard monomer, 3-9 wt% of soft monomer and 1-3 wt% of functional monomer to obtain a mixed monomer;

mixing 6-8 wt% of soft water and 0.5-2 wt% of emulsifier to obtain an emulsifier solution;

mixing 9-12 wt% of soft water and 0.2-1 wt% of an initiator to obtain an initiator solution;

mixing 45-62 wt% of soft water, 20 wt% of mixed monomer, 10 wt% of emulsifier solution and 5 wt% of initiator solution, vacuumizing, heating, and adding the rest of mixed monomer, emulsifier solution and initiator solution into the obtained mixed solution;

and adding 3-10 wt% of modifier and 0.2-0.5 wt% of defoamer into the obtained mixed solution to obtain the acrylic emulsion for the oilproof paper.

The application also provides composite oil-proof paper which comprises the oil-proof paper and a coating, wherein the coating is prepared from the acrylic emulsion or the acrylic emulsion prepared by the preparation method.

The application provides an acrylic emulsion for oil-proof paper, which is prepared from a hard monomer, a soft monomer, a functional monomer, an emulsifier, an initiator, a modifier, a defoaming agent and soft water; according to the preparation method, the molecular weight of the emulsion is adjusted through a proper monomer ratio, particularly, a functional monomer is added, and the molecular compactness of the coating is improved, so that the water and oil resistance of the coating is improved; meanwhile, due to the use of the reactive emulsifier, the emulsion not only plays an emulsification role, but also participates in the polymerization reaction of the emulsion and is combined on the acrylic acid main chain in a covalent bond form, so that the coating after the emulsion is coated and dried has an ultra-strong oleophobic effect, water drops or oil drops can roll off on the surface of the coating under the action of micro-power, and the performances of water resistance, oil resistance and the like are more stable; the cross-linking modifier is introduced into the main chain of the acrylic resin, and when the acrylic emulsion is coated, dried and formed into a film, a polymer coating with a net structure is generated through the reaction between cross-linking groups, so that the adhesive force of the coating to the surface of the oilproof paper is improved.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

In view of the requirements of oil resistance, water resistance and environmental protection of the coating for the oil-proof paper in the prior art, the application provides the acrylic emulsion for improving the oil resistance and the water resistance of the oil-proof paper; specifically, the embodiment of the invention discloses an acrylic emulsion for oilproof paper, which is prepared from the following components:

the hard monomer is selected from one or more of methyl methacrylate, ethyl methacrylate and acrylonitrile;

the hard monomer is selected from one or more of methyl acrylate, ethyl acrylate and n-octyl acrylate.

In the present application, the functional monomer is selected from one or two of N-methylolacrylamide and diacetone acrylamide. The content of the functional monomer is 1-3 wt%, and more specifically, the content of the functional monomer is 1.3-2.5 wt%.

The hard monomer is specifically selected from one or more of methyl methacrylate, ethyl methacrylate and acrylonitrile; the hard monomer is contained in an amount of 5 to 15 wt%, and more specifically, the hard monomer is contained in an amount of 5 to 7.5 wt%.

The soft monomer is specifically selected from one or more of methyl acrylate, ethyl acrylate and n-octyl acrylate. The content of the soft monomer is 3-9 wt%, more specifically, the content of the soft monomer is 3-5.5 wt%.

The emulsifier is a reactive emulsifier, and is selected from one or two of acrylamide isopropyl sodium sulfonate and sodium ethylene acid sulfonate; the content of the emulsifier is 0.5-2 wt%, more specifically, the content of the emulsifier is 0.6-1.8 wt%.

The initiator is selected from one or two of potassium persulfate and ammonium persulfate; the content of the initiator is 0.2-1.0 wt%, and more specifically, the content of the initiator is 0.2-0.6 wt%.

The defoaming agent is selected from polyether defoaming agents. The content of the defoaming agent is 0.2-0.5 wt%, more specifically, the content of the defoaming agent is 0.3-0.4 wt%.

The present application also provides an acrylic emulsion for grease resistant paper comprising the steps of:

mixing 5-15 wt% of hard monomer, 3-9 wt% of soft monomer and 1-3 wt% of functional monomer to obtain a mixed monomer;

mixing 6-8 wt% of soft water and 0.5-2 wt% of emulsifier to obtain an emulsifier solution;

mixing 9-12 wt% of soft water and 0.2-1 wt% of an initiator to obtain an initiator solution;

mixing 45-62 wt% of soft water, 20 wt% of mixed monomer, 10 wt% of emulsifier solution and 5 wt% of initiator solution, vacuumizing, heating, and adding the rest of mixed monomer, emulsifier solution and initiator solution into the obtained mixed solution;

and adding 3-10 wt% of modifier and 0.2-0.5 wt% of defoamer into the obtained mixed solution to obtain the acrylic emulsion for the oilproof paper.

In the process, the emulsifier and the initiator are respectively dissolved in water to respectively prepare the emulsifier solution and the initiator solution, and the mixed monomer is added in a semi-continuous manner, so that the stability of the latex is maintained while the conversion rate of the monomer is improved.

More specifically, the preparation method of the acrylic emulsion for kraft paper comprises the following steps:

(1) adding 5-15% of hard monomer, 3-9% of soft monomer and 1-3% of functional monomer into a material tank A, and uniformly stirring at room temperature to prepare a mixed monomer for later use;

(2) adding part of soft water (accounting for 10 percent of the total amount) and 0.5-2 percent of emulsifier into a B material tank, and uniformly stirring at room temperature to prepare an emulsifier solution for later use;

(3) adding part of soft water (accounting for 15 percent of the total amount) and 0.2-1 percent of initiator into a C material tank, uniformly stirring to prepare an initiator solution for later use;

(4) adding the rest soft water, 20% of mixed monomer, 10% of emulsifier solution and 5% of initiator solution into a reaction kettle, sealing, vacuumizing to- (0.01-0.06) MPa, starting a stirring and heating device, setting the stirring speed to be 100-200 r/min, keeping the temperature for 0.5-1 hour after the temperature reaches 80-85 ℃, continuously adding the prepared mixed monomer, emulsifier solution and initiator solution through a metering pump, and controlling the dripping time to be 2-3 hours;

(5) after the feeding is finished, preserving the heat at 70-75 ℃ for 1-2 hours, then adding 3-10% of modifier and 0.2-0.5% of defoamer, fully stirring for 0.5-1 hour, standing and cooling to obtain the acrylic emulsion.

The application also provides composite oil-proof paper which comprises the oil-proof paper and a coating, wherein the coating is prepared from the acrylic emulsion or the acrylic emulsion prepared by the preparation method.

The acrylic emulsion provided by the application is coated at 80-150 g/m²The coating amount of the base paper is 3 to 5g/m²。

In the preparation method provided by the application, before heating, the reaction kettle is firstly vacuumized to a negative pressure state to avoid side reaction caused by air in the kettle, and simultaneously, the pressure generated in the polymerization reaction is in a safe range, so that the safety of equipment personnel is ensured; by adopting a seed polymerization process and a semi-continuous feeding method, the monomer conversion rate of a polymerization system is always kept at a higher level, and the stability of latex is kept.

The oil-proof paper prepared by coating the acrylic emulsion on paper solves the problem of difficult recovery of the laminated paper and has super-strong oil-resistant effect. Compared with the existing acrylic emulsion, the oil-proof paper made of the emulsion has higher oil-proof grade, the surface tension of the coating is smaller, and oil drops form super-strong oil-proof effect on the surface of the coating.

For further understanding of the present invention, the acrylic emulsion for oilproof paper and the preparation method thereof provided by the present invention are described in detail below with reference to the following examples, and the scope of the present invention is not limited by the following examples.

Example 1

1. The raw material formula is as follows:

2. preparing an emulsion:

(1) uniformly stirring the hard monomer, the soft monomer and the functional monomer at room temperature to prepare a mixed monomer;

(2) uniformly stirring soft water accounting for 10 percent of the total amount and an emulsifier at room temperature to prepare an emulsifier solution;

(3) adding soft water accounting for 15% of the total amount and an initiator to room temperature, and uniformly stirring to prepare an initiator solution;

(4) adding the rest soft water, 20% of mixed monomer, 10% of emulsifier solution and 5% of initiator solution into a reaction kettle, sealing, vacuumizing to-0.01 MPa, starting a stirring and heating device, setting the stirring speed at 150r/min, keeping the temperature for 1 hour after the temperature reaches 80 ℃, continuously adding the prepared mixed monomer, emulsifier solution and initiator solution through a metering pump, and controlling the dripping time to be 3 hours;

(5) after the feeding is finished, preserving the heat for 1 hour at 70 ℃, then adding a modifier and a defoaming agent, fully stirring for 1 hour under the same condition, standing and cooling to obtain the acrylic emulsion.

Example 2

1. The raw material formula is as follows:

2. preparing an emulsion:

(1) uniformly stirring the hard monomer, the soft monomer and the functional monomer at room temperature to prepare a mixed monomer;

(2) uniformly stirring soft water accounting for 10 percent of the total amount and an emulsifier at room temperature to prepare an emulsifier solution;

(3) adding soft water accounting for 15% of the total amount and an initiator to room temperature, and uniformly stirring to prepare an initiator solution;

(4) adding the rest soft water, 20% of mixed monomer, 10% of emulsifier solution and 5% of initiator solution into a reaction kettle, sealing, vacuumizing to-0.05 MPa, starting a stirring and heating device, setting the stirring speed at 100r/min, keeping the temperature for 0.5 hour after the temperature reaches 85 ℃, continuously adding the prepared mixed monomer, emulsifier solution and initiator solution through a metering pump, and controlling the dripping time to be 2.5 hours;

(5) after the addition was complete, the temperature was maintained at 75 ℃ for 1.5 hours, and then the modifier and defoamer were added. Fully stirring for 0.6 hour under the same condition, standing and cooling to obtain the acrylic emulsion.

Example 3

1. The raw material formula is as follows:

2. preparing an emulsion:

(1) uniformly stirring the hard monomer, the soft monomer and the functional monomer at room temperature to prepare a mixed monomer;

(2) uniformly stirring soft water accounting for 10 percent of the total amount and an emulsifier at room temperature to prepare an emulsifier solution;

(3) adding soft water accounting for 15% of the total amount and an initiator to room temperature, and uniformly stirring to prepare an initiator solution;

(4) the remaining soft water, 20% of the mixed monomer, 10% of the emulsifier solution and 5% of the initiator solution were added to the reactor. Sealing, vacuumizing to-0.06 MPa, starting a stirring and heating device, setting the stirring speed at 200r/min, keeping the temperature for 0.6 hour after the temperature reaches 83 ℃, continuously adding the prepared mixed monomer, emulsifier solution and initiator solution by a metering pump, and controlling the dropping time to be 2 hours;

(5) after the feeding is finished, preserving the heat for 2 hours at 74 ℃, then adding a modifier and a defoaming agent, fully stirring for 0.5 hour under the same condition, standing and cooling to obtain the acrylic emulsion.

Comparative example 1

Performed as in example 1, except that: hard monomers in the raw material formula are omitted, and the soft water content is complemented to 100%.

Comparative example 2

Performed as in example 1, except that: the soft monomer in the raw material formula is omitted, and the soft water content is complemented to 100 percent.

Comparative example 3

Performed as in example 1, except that: functional monomers in the raw material formula are saved, and the soft water content is complemented to 100 percent.

Comparative example 4

Performed as in example 1, except that: the reactive emulsifier is replaced by the anionic emulsifier, the crosslinking modifier is omitted, and the soft water is supplemented to 100 percent.

1. Emulsion property detection

The emulsions obtained in examples 1 to 3 were examined and the results are shown in Table 1.

Wherein, the solid content is tested according to GB/T2793-1995; the glass transition temperature was tested with reference to GBT 13464-2008; the surface tension test is carried out according to GBT 22237-; the viscosity was tested with reference to GBT 2794-2013; the test for pH is carried out with reference to GBT 14518-1993.

TABLE 1 data Table for emulsion characteristics of examples 1 to 3

2. Emulsion coating Performance test

Preparing a sample: coating the emulsion at 150g/m²After the base paper is coated, the base paper is dried at 110 ℃ for 8S, and a functional coating (the thickness of the paper is 85 μm, and the thickness of the functional coating is 4 μm) is formed on the paper, so that the oil-proof paper is obtained.

And (3) testing: the surface tension and oil repellency ratings of the grease resistant paper samples were tested and the results are shown in table 2.

Wherein, the surface tension of the coating is tested according to GB/T14216-2008, and the oil resistance grade is tested according to TAPPI T559 cm-12.

TABLE 2 data of the emulsion coating properties of examples 1 to 3 and comparative examples 1 to 7

	Surface tension (mN/m)	Oil resistance grade (grade)
			Example 1	27	10
Example 2	25	10
			Example 3	28	11
Comparative example 1	37	4
			Comparative example 2	39	4
Comparative example 3	42	3
			Comparative example 4	41	4

As can be seen from the test results in Table 2, the oilproof paper prepared by the emulsions of the embodiments 1 to 3 of the invention has lower surface tension and excellent oil resistance, wherein the oil resistance level meets the standard requirement of TAPPI T559 cm-12; the oilproof papers of comparative examples 1 to 4 were significantly inferior in performance. Wherein, the comparison with the effects of comparative examples 1-3 shows that the performance of the oil-proof paper can be reduced by omitting any one of the hard monomer, the soft monomer and the functional monomer, and the oil-proof grade of the oil-proof paper can be effectively improved only by matching the hard monomer, the soft monomer and the functional monomer; the comparison with the effect of the comparative example 4 shows that the oil resistance of the oilproof paper is poor after the reactive emulsifier of the invention is replaced by other emulsifiers and the crosslinking modifier is omitted, which proves that the comprehensive performance of the oilproof paper can be effectively improved only by adopting the specific reactive emulsifier and introducing the crosslinking modifier.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.