CN109516486B - Preparation method of light calcium carbonate for carbonless copy paper - Google Patents

Abstract

The invention discloses a preparation method of light calcium carbonate for carbonless copy paper, which comprises the steps of calcining limestone to prepare quicklime, carrying out digestion reaction on the quicklime and water to generate lime milk, sieving by a 100-mesh sieve, and preparing 10-100g/L lime milk; heating lime milk to 40-90 ℃, adding a magnesium ion compound and dioctyl sodium sulfosuccinate and/or fulvic acid compound agent into the lime milk, introducing carbon dioxide, stirring at high speed in the carbonation reaction process, and stopping reaction when the pH of a reaction solution is reduced to 7-8 to obtain calcium carbonate slurry; and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at the temperature of 60-80 ℃ to obtain the light calcium carbonate product for the carbonless copy paper. The calcium carbonate prepared by the method has good dispersibility and narrow particle size distribution, and the color development optical density, the surface strength and the paper napping strength of the carbonless copy paper are improved when the calcium carbonate is applied to the carbonless copy paper.

Description

Preparation method of light calcium carbonate for carbonless copy paper

Technical Field

The invention relates to the technical field of calcium carbonate, in particular to a preparation method of light calcium carbonate for carbonless copy paper.

Background

Calcium carbonate is the most common mineral on the surface, but not all calcium carbonates are of value in the paper industry. Calcium carbonate is divided in the paper industry into fillers (GCC) and coating Pigments (PCC), which has earlier been used as a paper filler and pigment than GCC. The PCC particles have loose structures, rough appearance and special morphological characteristics. Compared with GCC, PCC has a high coefficient of astigmatism, giving filled paper better bulk, optical properties and retention. Domestic coating grade PCC is used in small amounts due to the high production cost and price of PCC. However, the superiority of PCC in paper coating is not comparable with GCC. In the future, more paper making enterprises may use PCC as a coating pigment. Researches show that the smoothness and the aging resistance of a paper coating can be improved by properly adding the ultrafine PCC, the absorptivity, the tightness, the opacity and the coating pore structure of the ink are improved, the roughness is reduced, and the water retention value of the coating is improved. The quality requirements for PCC coating pigments vary from paper grade to paper grade. Generally, the smaller the average particle size of PCC, the narrower the particle size distribution is, the more advantageous the smoothness, sizing and surface strength of the coated paper.

The carbonless copy paper is called carbonless paper or pressure-sensitive recording paper for short, is a new type of copy paper, and possesses the functions of direct copying and direct colour development. The carbonless copy paper is filled with PCC and covers the uneven surface of the base paper, so that the whiteness and the opacity of the paper can be improved, the smoothness and the glossiness of the paper surface are improved, the surface of the paper sheet has uniform and good ink absorbability, and finally, a good printing effect is obtained. Most precipitated calcium carbonate generally has the problems of wide particle size distribution, serious agglomeration and the like, and causes adverse effects on the processing and application of coated carbonless copy paper.

CN103923489A discloses a method for preparing a super-dispersible suspended calcium carbonate emulsion, which comprises the steps of preparing calcium carbonate powder into slurry with a certain solid content on the basis of obtaining the calcium carbonate powder by dry grinding, adding a super-dispersant in the process of preparing the slurry, and simultaneously adding a polyethylene glycol wetting agent and a titanate and aluminate composite coupling agent; and carrying out wet grinding by using the prepared slurry. The calcium carbonate produced by the method has high fineness and good dispersibility. However, the slurry added with a reagent such as polyethylene glycol is not suitable for industrial production because the slurry is likely to generate foam and corrode production equipment.

CN1253373C discloses a method for producing ultrafine calcium carbonate dispersible particles by a two-step reaction of first preparing uniform cubic precipitated calcium carbonate as seeds under conditions exceeding the critical supersaturation degree, and then in a second step, adding a reaction rate controlling agent to adjust the reaction conditions and perform crystal growth on the surface of the seed calcium carbonate. Thereby obtaining the superfine calcium carbonate with controllable granularity and uniform granularity distribution. The method of the invention is suitable for various existing reaction devices, no additional device is needed, the dosage of the additive used in the process is very small, and the obtained product has controllable particle size and particle size distribution. However, the calcium carbonate prepared by carbonizing the seed crystal has more intergrowth and agglomeration of particles, and the product is not suitable for being applied to the paper-making coating industry.

CN107758718A discloses a method for preparing superfine calcium carbonate nano-powder by calcite, which comprises the steps of crushing calcite, sieving, removing impurities, adding deionized water for digestion, and performing primary aging to obtain primary aged slurry; adding absolute ethyl alcohol into the ammonium bicarbonate water solution to obtain an ammonium bicarbonate alcohol water solution; under rapid and violent stirring, rapidly spraying the primary aged slurry and an ammonium bicarbonate alcohol aqueous solution into a reactor to generate white precipitates, rapidly adding a large amount of deionized water to dilute the precipitates, and performing secondary aging on the slurry; and (3) dehydrating after secondary aging, re-dispersing the obtained solid precipitate in deionized water, adding zinc sulfate into the slurry, stirring for 10min, adding phosphoric acid, introducing carbon dioxide for secondary carbonization under continuous stirring, filtering, washing and drying the slurry after secondary carbonization to obtain a precipitate, mixing the precipitate with n-butyl alcohol, and performing reduced pressure azeotropic distillation dehydration to obtain the superfine nano calcium carbonate powder. The method needs a large amount of deionized water, has very high cost, and can obtain a finished product by diluting the calcium carbonate suspension in a large amount and then drying the calcium carbonate suspension, so that the energy consumption is very high and the economic benefit is greatly reduced.

CN100509631C discloses a preparation method of light calcium carbonate for carbonless copy paper, which comprises adding a dispersant into silicon oxide slurry, grinding, adding calcium hydroxide slurry, and carbonizing to obtain the light calcium carbonate. The method can make the carbonless copy paper develop color faster. However, the method has complex operation flow and large addition amount of silicon oxide, and influences the purity of the product.

CN102502748B discloses a method for preparing rose-shaped calcium carbonate by microwave, wherein the precipitated calcium carbonate can be used as a high-quality pigment and filler and applied to industries such as papermaking, coating, plastics, rubber and the like. However, the calcium carbonate prepared by the method has a plurality of aggregates, and has adverse effects on the color development uniformity and the surface strength of the carbonless copy paper.

CN102674423B discloses a preparation method of flake-shaped superfine calcium carbonate for papermaking coating, the flake-shaped superfine calcium carbonate produced by the invention has small average diameter and thin thickness, the whiteness and the oil absorption value reach the national standard, and the flake-shaped superfine calcium carbonate can replace kaolin to be used as pigment for papermaking coating, thereby bringing economic benefit to enterprises. However, the method has great process difficulty, is not easy to control the particle size of the product, has certain disadvantages of fluidity and spindle-shaped calcium carbonate, and is not beneficial to the running of a high-speed paper machine.

CN101113004A discloses calcium carbonate for carbonless copy paper coating, preparation and application thereof, and the calcium carbonate prepared by the method can improve the smoothness and color development speed of carbonless copy paper. However, in the method, the crystal seeds are used for preparing the calcium carbonate, so that the calcium carbonate crystals are easy to agglomerate and grow, the particle size distribution is widened, and the surface strength of the carbonless copy paper is adversely affected.

According to the above, the calcium carbonate used for preparing the pigment of the coated paper at present has the defects of wide particle size distribution, poor dispersibility and the like, and causes the mechanical property and the processing property of the coated paper to be reduced. The light calcium carbonate with narrow particle size distribution, small average particle size and good dispersibility is prepared by the method and applied to the carbonless copy paper, so that the coated paper has excellent color rendering property and surface strength.

The above background disclosure is only for the purpose of assisting understanding of the inventive concept and technical solutions of the present invention, and does not necessarily belong to the prior art of the present patent application, and should not be used for evaluating the novelty and inventive step of the present application in the case that there is no clear evidence that the above content is disclosed at the filing date of the present patent application.

Disclosure of Invention

The invention aims at solving the problems of calcium carbonate for coating paper pigment and provides a preparation method of light calcium carbonate for carbonless copy paper. The method uses limestone as a raw material, calcines and digests the limestone to obtain calcium hydroxide slurry, adopts a bubbling carbonization method, improves the dispersion performance of calcium carbonate through the inhibition effect of magnesium ions on the growth of calcium carbonate crystals and the steric hindrance caused by the absorption of dioctyl sodium sulfosuccinate and/or fulvic acid on the crystal faces of the calcium carbonate, obtains PCC with narrow particle size distribution, and improves the color rendering performance and the paper napping strength of the coated carbonless copy paper.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) calcining limestone at the temperature of 1000-1200 ℃ for 200-300 minutes to prepare quicklime, carrying out digestion reaction on the quicklime and water to generate lime milk, and sieving by a 100-mesh sieve to prepare 10-100g/L lime milk;

(2) heating lime milk to 40-90 ℃, adding a magnesium ion compound and dioctyl sodium sulfosuccinate and/or fulvic acid compound agent into the lime milk, introducing carbon dioxide, stirring at high speed in the carbonation reaction process, and stopping reaction when the pH of a reaction solution is reduced to 7-8 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at the temperature of 60-80 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

Further, the mass ratio of the quicklime to the water in the digestion reaction is 1:6-8, stirring is carried out at room temperature, and the stirring speed is controlled to be 100-.

Furthermore, the addition amount of the compound agent is 0.3-3% of the weight of the lime milk.

Further, the weight ratio of the magnesium ion compound to the dioctyl sodium sulfosuccinate is 1-4: 1.

further, the weight ratio of the magnesium ion compound, the dioctyl sodium sulfosuccinate and the fulvic acid in the compound agent is 1-4: 1:1-2.

Further, the weight ratio of the magnesium ion compound to the fulvic acid in the compound agent is 1-3: 1.

further, the magnesium ion compound is one or more of magnesium carbonate, magnesium chloride and magnesium sulfate.

Further, the concentration of the carbon dioxide in the step (2) is 20-30%, and the reaction temperature is controlled at 20-30 ℃.

Further, the high-speed stirring speed is 300r/min-500 r/min.

Compared with the prior art, the invention has the advantages and beneficial effects that:

1. the invention uses limestone as raw material, calcines and digests to obtain calcium hydroxide slurry, adopts bubbling carbonization method, improves the dispersion property of calcium carbonate by the inhibiting effect of magnesium ions on the growth of calcium carbonate crystal and the steric hindrance caused by the absorption of fulvic acid and/or dioctyl sodium sulfosuccinate on the crystal face of calcium carbonate, obtains PCC with narrow particle size distribution, and has good application prospect.

2. The calcium carbonate prepared by the invention is applied to the carbonless copy paper, and the color development optical density, the surface strength and the paper napping strength of the carbonless copy paper are improved.

3. The method has the advantages of simple and feasible process, low production cost, suitability for industrial production and better economic and social benefits.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.

Example 1

A preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) crushing limestone to 10-15cm, calcining at 1150 ℃ for 300 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:6 to generate lime milk, and sieving with a 100-mesh sieve to prepare 20g/L lime milk;

(2) heating lime milk to 50 ℃, adding 1% of magnesium chloride and 1% of dioctyl sodium sulfosuccinate by weight of the lime milk into the lime milk, introducing 20% of carbon dioxide, keeping the stirring speed at 300r/min, and stopping reaction when the pH of a reaction solution is reduced to 7.5 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at the temperature of 60 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

Example 2

A preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) crushing limestone to 10-15cm, calcining at 1050 ℃ for 300 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:8 to generate lime milk, and sieving with a 100-mesh sieve to prepare 50g/L lime milk;

(2) heating lime milk to 70 ℃, adding 1% of magnesium sulfate, 0.3% of dioctyl sodium sulfosuccinate and 0.5% of fulvic acid, which are 1% of the weight of the lime milk, into the lime milk, introducing 25% of carbon dioxide, keeping the stirring speed at 350r/min, and stopping reaction when the pH value of a reaction solution is reduced to 7 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at 70 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

Example 3

A preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) crushing limestone to 10-15cm, calcining at 1200 ℃ for 200 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:7 to generate lime milk, and sieving with a 100-mesh sieve to prepare 100g/L lime milk;

(2) heating lime milk to 60 ℃, adding magnesium sulfate accounting for 0.35 percent of the weight of the lime milk and fulvic acid accounting for 0.1 percent of the weight of the lime milk into the lime milk, introducing carbon dioxide with the concentration of 30 percent, keeping the stirring speed at 500r/min, and stopping reaction when the pH value of a reaction solution is reduced to 8 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at 80 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

Comparative example 1

A preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) crushing limestone to 10-15cm, calcining at 1150 ℃ for 300 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:6 to generate lime milk, and sieving with a 100-mesh sieve to prepare 20g/L lime milk;

(2) heating lime milk to 50 ℃, introducing 20% carbon dioxide, keeping the stirring speed at 300r/min, and stopping reaction when the pH of the reaction liquid is reduced to 7.5 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at the temperature of 60 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

Comparative example 2

A preparation method of light calcium carbonate for carbonless copy paper comprises the following steps:

(1) crushing limestone to 10-15cm, calcining at 1050 ℃ for 300 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:8 to generate lime milk, and sieving with a 100-mesh sieve to prepare 50g/L lime milk;

(2) heating lime milk to 70 ℃, introducing 25% carbon dioxide, keeping the stirring speed at 350r/min, and stopping reaction when the pH of the reaction liquid is reduced to 7 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at 70 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.

After the calcium carbonate finished product prepared in the above examples is subjected to coating experiment and test according to the method: 50 parts of calcium carbonate, 70 parts of water, 30 parts of kaolin (prepared into liquid), 5 parts of oxidized starch, 5 parts of styrene-butadiene latex, 5 parts of color developing agent and 0.5 part of sodium polyacrylate. The paint is prepared by mixing the pigment and various auxiliary agents in a certain order. Taking the prepared coating, manually coating the coating at the speed of 2m/s by using a No. 0 press roll according to the coating weight of 55 g/square meter, and carrying out carbon-free copy paper performance detection after drying, wherein the test results are shown in Table 1.

Table 1: test effect of calcium carbonate prepared by embodiment of the invention applied to carbon paper

As can be seen from the above table, the light calcium carbonate prepared by the method of the invention has smaller average particle size, narrow particle size distribution, low viscosity of prepared coating, moderate water retention value compared with the calcium carbonate prepared by the common method (comparative example), is beneficial to the operation of a high-speed paper machine, can reduce the energy consumption of the paper machine, and has better economic benefit. Compared with common light calcium carbonate, the color development density and the surface strength of the coated carbonless copy paper are obviously improved, and the quality of the carbonless copy paper is greatly improved.

The foregoing is a more detailed description of the invention in connection with specific/preferred embodiments and is not intended to limit the practice of the invention to those descriptions. It will be apparent to those skilled in the art that various substitutions and modifications can be made to the described embodiments without departing from the spirit of the invention, and such substitutions and modifications are to be considered as within the scope of the invention.

Claims (2)

1. A preparation method of light calcium carbonate for carbonless copy paper is characterized by comprising the following steps:

(1) calcining limestone at the temperature of 1000-1200 ℃ for 200-300 minutes to prepare quicklime, carrying out digestion reaction on the quicklime and water to generate lime milk, and sieving by a 100-mesh sieve to prepare 10-100g/L lime milk;

(2) heating lime milk to 40-90 ℃, adding a magnesium ion compound, dioctyl sodium sulfosuccinate and fulvic acid compound agent into the lime milk, introducing carbon dioxide, stirring at a high speed in the carbonation reaction process, and stopping reaction when the pH value of a reaction solution is reduced to 7-8 to obtain calcium carbonate slurry;

(3) washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at the temperature of 60-80 ℃ to obtain a light calcium carbonate product for the carbonless copy paper;

the addition amount of the compound agent is 0.3-3% of the weight of the lime milk;

the weight ratio of the magnesium ion compound, the dioctyl sodium sulfosuccinate and the fulvic acid of the compound agent is 1-4: 1: 1-2;

the magnesium ion compound is one or more of magnesium carbonate, magnesium chloride and magnesium sulfate;

the mass ratio of the quicklime to the water in the digestion reaction is 1:6-8, stirring is carried out at room temperature, and the stirring speed is controlled to be 100-150 r/min;

in the step (2), the concentration of carbon dioxide is 20-30%, and the reaction temperature is controlled at 20-30 ℃;

the high-speed stirring speed is 300r/min-500 r/min.

2. A preparation method of light calcium carbonate for carbonless copy paper is characterized by comprising the following steps:

(1) crushing limestone to 10-15cm, calcining at 1050 ℃ for 300 minutes to obtain quicklime, carrying out digestion reaction on the quicklime and water according to the proportion of 1:8 to generate lime milk, and sieving with a 100-mesh sieve to prepare 50g/L lime milk;

(2) heating lime milk to 70 ℃, adding 1% of magnesium sulfate, 0.3% of dioctyl sodium sulfosuccinate and 0.5% of fulvic acid, which are 1% of the weight of the lime milk, into the lime milk, introducing 25% of carbon dioxide, keeping the stirring speed at 350r/min, and stopping reaction when the pH value of a reaction solution is reduced to 7 to obtain calcium carbonate slurry;

(3) and washing and filtering the calcium carbonate slurry by using absolute ethyl alcohol, and performing infrared drying at 70 ℃ to obtain the light calcium carbonate product for the carbonless copy paper.