CN111691225A

CN111691225A - Method for improving transparency and waterproof performance of paper sheet

Info

Publication number: CN111691225A
Application number: CN202010539761.XA
Authority: CN
Inventors: 高玉杰; 马昊然
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2020-06-15
Filing date: 2020-06-15
Publication date: 2020-09-22

Abstract

The invention provides the transparent paper with good waterproof performance, which is prepared by the method with relatively simple operation and has important significance. The invention adopts ethylene-vinyl acetate copolymer with similar refractive index with plant fiber as the main agent of the transparent agent, and fills the pores inside the paper by dipping, thereby completely coating the paper fiber, wherein the refractive index of each component inside the paper is nearly uniform, and the appearance is represented as the increase of the transparency of the paper. And because this clearing agent is the hydrophobic material, can realize the effective isolation with water after the paper fibre is coated by this material, the hydrogen bond connection between the fibre can not suffer the destruction of water, shows that the wet strength of paper is showing and is strengthening.

Description

Method for improving transparency and waterproof performance of paper sheet

Technical Field

The invention belongs to the field of paper transparency agents, and particularly relates to a preparation method of waterproof high-transparency paper

Technical Field

Because of the optical particularity of transparent or semitransparent paper, the prior production mainly depends on selecting proper fiber raw materials, and adopts methods for improving the compactness of paper sheets, such as improving the beating degree of pulp (fine fiber sticky beating), supercalendering and the like, so that the application range of the raw materials is narrowed, equipment and electric energy are consumed due to high beating degree, and the application range of the transparent paper is limited to a great extent due to low water tolerance of the paper.

Disclosure of Invention

The invention aims to prepare a paper transparency agent with hydrophobic property, so as to improve the transparency and hydrophobic property of paper and further enhance the application performance of the transparent paper.

The invention is realized by the following steps of the technical scheme:

step 1: taking 5g-20g of ethylene-vinyl acetate copolymer (EVA) particles with the mass fraction of Vinyl Acetate (VA) of 10-60 percent, heating the EVA particles to 100-200 ℃ to melt the EVA particles, keeping the heating temperature at 100-200 ℃, adding a crosslinking agent dicumyl peroxide (DCP) and an auxiliary crosslinking agent 1, 2-divinylbenzene (TMPTMA) to blend the EVA particles to generate a crosslinking reaction, and reacting for 30-60 min.

Step 2: adding liquid paraffin for viscosity adjustment, wherein the addition amount of the paraffin is 15-25% of the mass of the EVA, keeping the temperature at 80-150 ℃ in the adjustment process, and ending heating after fully and uniformly mixing to obtain a finished transparent agent

And step 3: heating the transparent agent product until it melts, and coating at a fixed amount of 15-9g/m²The surface of the base paper of the transparent paper (the beating degree of the transparent paper is 30-70 DEG SR) is kept unchanged, the paper is pressed by a press roll to promote the penetration of the transparent agent in the paper, and the pressure is 0.5kPa-2 kPa. Scraping the redundant transparent agent on the surface of the paper sheet, and naturally cooling to room temperature to obtain the finished transparent paper product

And 4, step 4: and (4) testing the finished transparent paper product obtained in the step (2).

The medicine is ethylene-vinyl acetate copolymer particles with the purity of 90-99%, 1, 2-divinylbenzene with the purity of 90-99% and dicumyl peroxide solid with the purity of 30-50%.

The preferred mass ratio of the medicine is ethylene-vinyl acetate copolymer: 1, 2-divinylbenzene and dicumyl peroxide is 90: 5

The VA mass fraction of the ethylene-vinyl acetate copolymer is preferably 40%.

The prepared paper transparent agent has good transparent waterproof performance, and when the addition amount of the transparent agent reaches 20g/m²When applied to the handsheet surface, good transparency of the sheet is achieved.

The ethylene-vinyl acetate copolymer is used as a main agent of the transparency agent and has a refractive index close to that of plant cellulose, the internal refractive index of the paper filled with the transparency agent tends to be uniform, and the transparency of the paper is improved; the ethylene-vinyl acetate copolymer has affinity with plant fibers and good hydrophobic property and mechanical property, and can effectively and completely coat paper fibers so as to improve the waterproof property and the paper strength of the transparent paper. The paper transparency agent with good hydrophobic property is prepared by the method which is relatively simple to operate, the requirements of the traditional method on a pulping working section are reduced, the electric quantity consumption is reduced, the papermaking duration is shortened, and the method has important significance.

Drawings

FIG. 1 is a drawing (a) of a base impregnated paper and (b) of a finished transparent paper in example 1;

FIG. 2 is a scanning electron micrograph of a transparent paper (a) as a finished product in example 1 and a transparent paper blank control (b);

FIG. 3 is a drawing (a) of a base impregnated paper and a drawing (b) of a finished transparent paper in example 2;

FIG. 4 is a scanning electron micrograph of a transparent paper (a) as a finished product in example 2 and a clear paper blank control (b).

Detailed Description

Example 1

100g (VA) of ethylene-vinyl acetate copolymer (EVA) particles with the mass fraction of 40 percent are taken to be placed in a beaker to be heated and melted, the heating temperature is kept at 160 ℃, 5g each of cross-linking agent dicumyl peroxide (DCP) and auxiliary cross-linking agent 1, 2-divinylbenzene (TMPTMA) are added, 20g of liquid paraffin is added after 50min of blending, a finished transparent agent is obtained after full and uniform mixing, the stirring is stopped, and the heating temperature is kept at 100 ℃. Coating 5g of the above product at a fixed amount of 15-39g/m²Keeping the temperature of the paper at 100 ℃ during the surface of the raw paper of the transparent paper, scraping off redundant transparent agent on the surface of the paper after the paper is fully soaked, taking out the paper and cooling to room temperature to obtain a finished product of the transparent paper (as shown in figure 1).

Finally, the obtained transparent paper and the blank control paper sample are observed under a scanning electron microscope (the result is shown in the attached figure 2) and the paper transparency and the paper strength are measured (table 1).

TABLE 1 paper clarity measurement of the samples

Example 2

300g of ethylene-vinyl acetate (EVA) particles with the mass fraction of Vinyl Acetate (VA) of 60 percent are taken to be placedOperating the single-screw extruder at 150 ℃ for 10min, adding 15g of dicumyl peroxide (DCP) and 1, 2-divinylbenzene (TMPTMA) respectively, adjusting the temperature to 165 ℃, operating the equipment for 50min, taking out the mixture, immediately placing the mixture into a 1000ml beaker, adding 90g of liquid paraffin with the temperature of 100 ℃ into the beaker, and uniformly mixing (keeping the heating temperature at 110 ℃ in the period) to obtain the finished transparent agent. Taking 5g of the above product, coating on a fixed amount of 15-39g/m²Keeping the temperature of the paper at 100 ℃ during the surface of the raw paper of the transparent paper, scraping off redundant transparent agent on the surface of the paper after the paper is fully soaked, taking out the paper and cooling to room temperature to obtain a finished product of the transparent paper (as shown in figure 3).

Finally, the obtained transparent paper and the blank control paper sample are observed under a scanning electron microscope (the test result is shown in figure 4) and the transparency of the paper is measured (table 2).

TABLE 2 paper clarity measurements of the samples

As is clear from tables 1 and 2, the handsheets impregnated with no fiber clearing agent had low transparency of the whole paper and extremely poor water resistance because the fiber surfaces were directly exposed to the air without filling the clearing agent between the fibers of the paper. After the impregnation of the clearing agent, the wet strength and the clearing degree are obviously improved. The fact that the finished impregnated transparent paper is hardly affected by water shows that the transparent paper fully coats paper fibers, effectively prevents the water from damaging hydrogen bonds among the fibers, and is considered to have strong hydrophobic property within a certain degree.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method for improving the clarity and water resistance of a sheet of paper, comprising the steps of:

step 1: taking 5g-20g of ethylene-vinyl acetate copolymer particles with 10-60% of Vinyl Acetate (VA) by mass fraction, heating the particles to 100-200 ℃ to melt the particles, keeping the heating temperature at 100-200 ℃, adding a crosslinking agent dicumyl peroxide (DCP) and an auxiliary crosslinking agent 1, 2-divinylbenzene (TMPTMA) to carry out blending to generate crosslinking reaction, adding liquid paraffin to carry out viscosity regulation after the reaction is carried out for 30-60 min, keeping the temperature at 80-150 ℃ in the regulation process, and finishing heating after full mixing to obtain a finished transparent agent.

Step 2: heating the transparent agent product until it melts, and coating at a fixed amount of 15-39g/m²The surface of the base paper of the transparent paper (the beating degree of the transparent paper is 30-70 DEG SR) is kept unchanged, the paper is pressed by a press roll to promote the penetration of the transparent agent in the paper, and the pressure is 0.5kPa-2 kPa. And scraping redundant transparent agent on the surface of the paper sheet, and naturally cooling to room temperature to obtain a transparent paper finished product.

2. The process according to claim 1, characterized in that the ethylene-vinyl acetate copolymer (VA) mass fraction is preferably 40%.

3. The process as claimed in claim 1, wherein the crosslinking reaction temperature is from 150 to 170 ℃.

4. The process as claimed in claim 1, wherein the co-crosslinking agent TMPTMA is added in an amount of 2-10% by mass based on the EVA.

5. The process as claimed in claim 1, wherein the amount of DCP as a crosslinking agent is 3-10% by mass of EVA.