SK37599A3 - De-inking liquid composition and its use for de-inking paper - Google Patents

Abstract

The invention concerns a liquid composition containing at least one first surfactant (A) and at least one second surfactant selected between (B) and (C). The non-ionic surfactant (A) is a fatty alcohol selected among the polyethoxylated or polypropoxylated fatty alcohols of the formula R1-O-[(CH2CH2O)x <.> (CH2-CH<CH3>O)y]-H. The non-ionic surfactant (B) is a fatty alcohol selected among the polyethoxylated fatty alcohols of the general formula R2-O-(CH2CH2O)z-H. The non-ionic surfactant (C) is a fatty alcohol selected among the polyethoxylated fatty alcohols corresponding to the formula R3-O-(CH2CH2O)w-H. The composition can be used for de-inking paper.

Description

Liquid decolorizing agents and their use in decolouring paper

Technical field

The present invention relates to paper decolorizing liquid compositions which are used in the recovery of paper pulp resulting from waste newsprint, magazine paper, photocopy and computer paper, and a process for preparing the same as well as their use in decolouring paper.

BACKGROUND OF THE INVENTION

In particular, the present invention relates to a liquid decolorizing agent and its use, which is suitable for decolouring paper by flotation and / or washing, which makes it possible to obtain reclaimed paper pulp of high quality, high whiteness and very low residual color content and achieve stable and reliable bleaching process. The bleaching operation is very important as it is one of the basic steps in recycling waste paper.

Many methods for decolouring waste paper are known. Recycling of waste paper has become a very important sector of industry in which it is necessary to develop and perfect new decolorizing agents and methods of their use with low energy and natural resources consumption, which are not very harmful to the environment and at the same time very efficiently recover paper pulp .

Conventional and standard methods for decolouring waste paper to obtain a base paper-making material fall into two categories: the first method is the flotation bleaching method and the second is the washing bleaching method.

These bleaching processes consist essentially of two steps. The first is the deburring of the waste paper, also known as pulping, and the second is the removal of the residual color by flotation or washing.

The first step is carried out by bringing the waste paper into contact with water and a chemical system, which usually contains a silicate, a basic agent, a soap or surfactant, and a bleaching agent, which are added separately, with stirring. Once the paper is pulped, the paper pulp is diluted in accordance with the first method and transferred to a flotation cell into which air is blown through the bottom. Foam is formed which carries away the paint particles either by flowing over the edge of the tank in which the paper pulp is located or draining by suction. In a second method, the pulp is diluted with water and then filtered or centrifuged from the paint particles dispersed in water. This step is repeated as many times as necessary to obtain crushed material of suitable quality for reuse. The third method comprises combining a wash and a flotation step to separate the ink from the pulp.

The chemical systems used in the bleaching are generally selected according to the method of separating the pulp and the ink particles.

For the method of separation by washing, the chemical system must be almost non-foaming under process conditions in order to reduce mechanical problems with respect to the equipment used. Furthermore, in the presence of a chemical system, the color particles to be separated from the pulp must be finely and well dispersed in order to increase the separation efficiency of said particles and to obtain a high quality pulp.

For the flotation method of separation must be more foaming than the method of washing, the particles of paint in this case will stick to the chemical system This is because of the foam resulting from flotation, allowing them to separate from the pulp. Furthermore, the ink particles must be able to agglomerate to form large sized aggregates which are lightened and thus improve their separation from the pulp and removal by air bubbles.

The Applicant has developed a liquid paper bleaching composition which can be used in both the blotting bleaching method and the flotation and washing bleaching method.

SUMMARY OF THE INVENTION

The novel liquid composition of the present invention provides high quality reclaimed paper pulp with high whiteness and very low residual color content while ensuring high performance and reliability in the industrial use of said composition.

Other advantages and characteristics of the invention will become clearer upon reading the description and examples that follow.

The compositions developed by the Applicant comprise at least one first nonionic surfactant (A) and at least one second nonionic surfactant selected from (B) and (C).

The nonionic surfactant (A) consists of at least one polyethoxylated and polypropoxylated aliphatic fatty alcohol of the following general formula:

R ¹ -O- ((CH ₂ CH ₂ O) _x . (CH ₂ -ch (CH ₃ ) 0) _y ] H is an alkyl group containing 16 to 22 carbon atoms;

the average value of x is between 5 and 30;

the average value of y is between 2 and 20.

The second nonionic surfactant (B) is composed of at least one polyethoxylated aliphatic fatty alcohol of the following general formula:

r ² -o- (ch ₂ ch ₂ o) _z -h where:

R ² is a linear alkyl radical having 10 to 16 carbon atoms;

the mean z is selected such that the weight fraction of oxyethylene units is between 55 and 75% based on the weight of the surfactant (B). For example, when the radical R ² contains 14 carbon atoms of between 6 to 13.

The third type of surfactant (C) consists of at least one polyethoxylated aliphatic fatty alcohol corresponding to the following general formula:

R ³ -O- (CH ₂ CH ₂ O) _w -H where:

R ³ is a linear alkyl radical containing 10 to 22 carbon atoms;

the mean w is selected such that the proportion by weight of oxyethylene units is between 35 and 45% based on the weight of the surfactant (C). In general, the mean value of w is between 1 and 10. For example, if the radical R ³ contains 13 carbon atoms, w is 1 to 4.

Generally, the weight ratio of surfactant (B) / surfactant (A) is between 0.02 and 1 and the weight ratio of surfactant (C) / surfactant (A) is between 0.02 and 1.

These compositions are prepared either in the operating medium, during the industrial paper decolorization process, or are preferably prepared in advance.

When prepared in advance, the compositions are stable over time and preferably do not require the presence of stabilizing ingredients.

Additional compounds may be added during the preparation of the compositions or during their use in the decolorization process. In particular, sodium hydroxide, sodium silicate and hydrogen peroxide may be added.

The nonionic surfactant (A) is preferably a mixture of fatty alcohols wherein the radical R ¹ is a linear alkyl group containing 16 to 20 carbon atoms, with 7 to 13 oxyethylene units and 3 to 10 oxypropylene units, and more preferably with 11 oxyethylene units and 4 oxypropylene units . Examples of fatty alcohols suitable as surfactant (A) are coconut fatty alcohol, tallow fatty alcohol, palmityl alcohol, myristyl alcohol, lauryl alcohol, and oleyl alcohol. Surfactants of type (A) which can be used according to the present invention are available from a variety of commercial sources. In particular, Rhoditek ^R 1000 and Rhoditek ^R 1200, sold by Rhône-Poulenc, gave good results when used in accordance with the invention.

The nonionic surfactant (B) is preferably a mixture of fatty alcohols wherein the radical R ² is a linear alkyl group containing 12 to 16 carbon atoms, with an oxyethylene units by weight of 5 to 65% by weight of the surfactant (B). More preferably, the surfactant (B) comprises 6 to 10 oxyethylene units. Surfactants of type (B) that can be used in the context of the present invention are available from a variety of commercial sources. In particular, the Synperonic A7 products sold by ICI gave good results when used in the methods of the present invention.

The nonionic surfactant (C) is preferably a mixture of fatty alcohols, wherein the radical R ³ is a linear alkyl group containing 12 to 14 carbon atoms, with an oxyethylene unit weight fraction of between 38 and 42% by weight of the surfactant (C). More preferably, the surfactant (C) comprises 2-4 oxyethylene units. Surfactants of type (C) which can be used according to the present invention are available from a variety of commercial sources. In particular, Synperonic A3 sold by ICI and Rhodasurf LA 30 sold by Rhône-Poulenc give good results in the process of the invention.

The liquid composition of the present invention may be packaged in a variety of forms that allow use in any type of industrial equipment used in decolorizing waste paper. Thus, the liquid compositions are prepared in the form of a solution, emulsion or dispersion without substantially changing the properties. However, in an alternative embodiment of the invention, the liquid composition is in the form of an aqueous solution. In this case, the amount of water is between 0.05 and 30% by weight.

The weight percent of surfactant in the liquid medium varies according to the type of surfactant, and typically ranges from 70 to 100% based on the total weight of the liquid composition.

The surfactants used in the present invention are prepared according to a method known to those skilled in the art. For example, surfactants are prepared by spraying ethylene oxide or sequentially spraying ethylene oxide and propylene oxide over a fatty alcohol. The reaction is carried out at a temperature of about 160 ° C in the presence of a basic catalyst.

The liquid compositions of the present invention can be used according to previously known methods. However, the Applicant has developed a particularly preferred bleaching method that includes at least one flotation step.

The bleaching process using the liquid composition of the present invention consumes a small amount of energy and a small amount of natural resources; Furthermore, it only has a small impact on the environment, while obtaining high-quality recovered paper pulp. This new process in which the liquid composition of the present invention is used comprises two steps.

The first step is pulping, whereby the ink containing paper is brought into contact with said composition and water in the pulper to convert the paper into pulp. The second step comprises at least one flotation process wherein the pulp is diluted with water. In this step, the pH is either not changed or is preferably made basic. The basic pH is preferably between 8.5 and 9.

If appropriate, conventional additives which are not present in the liquid composition are added in the first step. In general, the composition according to the invention is preferably used at a surfactant concentration of 0.01% by weight in the medium used in the first step, with no higher or lower concentrations being excluded. The content of the waste paper containing the ink to be treated is 5 to 20% by weight and more preferably 10 and 15% by weight in the medium.

This operation may be carried out at ambient temperature, but is preferably carried out at a temperature of 30 to 70 ° C. It is carried out in any known type of pulping apparatus with a mixing and de-pulping apparatus.

When the waste paper impregnation operation is carried out with a mixture of the liquid composition and optional additives, the pulp is allowed to stand for 0.5 to 4 hours. Before the second step, which comprises at least one flotation step, the pulp is usually diluted to obtain a pulp concentration in the water of 1 to 3% by weight.

The second step, known as the flotation step, is then carried out by blowing air through the bottom of the tank. The foam that is formed carries away the paint particles and separates the paint from the pulp. The foam is then removed from the tank by overflow or alternatively by suction.

The debris-free paint particles can then be used in papermaking.

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As an alternative embodiment of the invention, at least one surfactant (B) or (C) may be added after pulping and before flotation.

The following examples and tests, which do not limit the invention in any way, illustrate the preparation and use of the compositions of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Example 1 illustrates the use of a bleaching agent used in the prior art.

Other examples illustrate the bleaching compositions of the present invention. These compositions, in addition to Example 5, where Rhodasurf LA 30 is added after the pulping step, are prepared in the medium in which the paper to be decolorized is present.

The bleaching efficiency is determined by measuring the whiteness of sheets of paper prepared from paper pulp after pulping and ISO flotation. This efficiency reflects in the examples according to the invention an increase in whiteness relative to prior art paper.

The compositions of Examples 1 and 2 contain the same amount of ingredients except that the composition of Example 2 further comprises Synperonic A7. The nature of the 50/50 mixture of old newspapers and magazines is the same for Examples 1 and 2.

Formulations 3, 4 and 5 contain the same amount of ingredients except that the compositions of Examples 4 and 5 further comprise Rhodasurf LA 30. The nature of the 50/50 mixture of old newspapers and old magazines is the same for Examples 2, 3 and 5.

Example 1

The first pulping step is performed in a 25 liter pulper equipped with a propeller stirrer and the second in a 15 liter flotation chamber (Lamort equipment).

Place the following mixture of 50/50 old newspapers and old magazines in the pulper: sodium hydroxide (25%):

hydrogen peroxide (30%):

Rhoditek 1000:

sodium silicate (33.8%, SiO2 / Na2O 3.3 ratio) water at 45 ° C:

1500 g 60 g 50 g

3.37 g 111 g 10 liters

The water has a controlled hardness; [Ca ²⁺ ] = 3 x 10 ³ mol / l and [Mg ²⁺ ] = 1 x 10 ³ mol / l.

Pulping is performed for 12 minutes at a propeller rotational speed of 1500 rpm. The pulp is then allowed to stand for 30 minutes.

The second flotation step is performed in a 15 liter flotation chamber.

The pulp obtained according to the above process is diluted with water of the controlled hardness mentioned above so as to obtain a solid suspension containing 1.2% solids and heated to 45 ° C. The flotation step is carried out at neutral pH with air introduction for 6 minutes.

The float suspension is then filtered through a test sheet preparation machine. The test paper sheets are then dried and their brightness according to ISO (diffuse blue reflection factor) measured according to NF standard Q 03-039 is 59.7.

Example 2

The first step, which is pulping, is carried out in a 25 liter pulping apparatus equipped with a propeller mixer and the second step is carried out in a 15 liter flotation cell (Lamort apparatus).

The following mixture is placed in the pulper:

mixture of 50/50 old newspapers and old magazines: 1500 g sodium hydroxide (25%): 60 g hydrogen peroxide (30%): 50 g

Rhoditek 1000: 3.37 g

Synperonic A7: 0.27 g sodium silicate (33.8%, SiO ₂ / Na ₂ O 3.3 ratio) 111 g water at 45 ° C: 10 liters

The water has a controlled hardness; [Ca ²⁺ ] = 3 x 10 ³ mol / l and [Mg ²⁺ ] = 1 x 10 ^-3 mol / l.

Pulping and flotation is performed under the same conditions as above.

The float suspension is then filtered through a test sheet preparation machine. The test paper sheets are then dried and their whiteness according to ISO (diffuse blue reflection factor) measured according to NF standard Q 03-039 is 60.4.

Example 3

The first step, which is pulping, is carried out in a 25 liter pulping apparatus equipped with a propeller mixer and the second step is carried out in a 15 liter flotation cell (Lamort apparatus).

The following mixture is placed in the pulper:

mixture of 50/50 old newspapers and old magazines: 1500 g sodium hydroxide (25%): 60 g hydrogen peroxide (30%): 50 g

Rhoditek 1000: 3.37 g

Synperonic A7: 0.18 g sodium silicate (33.8%, SiO ₂ / Na ₂ O 3.3 ratio) 44.40 g water at 45 ° C: 10 liters

The water has a controlled hardness; [Ca ²⁺ ] = 3 x 10 ³ mol / l and [Mg ²⁺ ] = 1 x 10 ³ mol / l.

Pulping and flotation is performed under the same conditions as above.

The float suspension is then filtered through a test sheet preparation machine. The test paper sheets are then dried and their whiteness according to ISO (diffuse blue reflection factor) measured according to NF standard Q 03-039 is 51.7.

Example 4

The first step, which is pulping, is carried out in a 25 liter pulping apparatus equipped with a propeller mixer and the second step is carried out in a 15 liter flotation cell (Lam12 control).

The following mixture is placed in the pulper:

mixture of 50/50 old newspapers and old magazines: 1500 g sodium hydroxide (25%): 60 g hydrogen peroxide (30%): 50 g

Rhoditek 1000: 3.37 g

Synperonic A7: 0.18 g

Rhodasurf LA 30 0.75 g sodium silicate (33.8%, SiO ₂ / Na ₂ O 3.3 ratio) 44.40 g water at 45 ° C: 10 liters

The water has a controlled hardness; [Ca ²⁺ ] = 3 x 10 ^-3 mol / l and [Mg ²⁺ ] = 1 x 10 ^-3 mol / l.

Pulping and flotation is performed under the same conditions as above.

The float suspension is then filtered through a test sheet preparation machine. The test paper sheets are then dried and their whiteness according to ISO (diffuse blue reflection factor) measured according to NF standard Q 03-039 is 53.5.

Example 5

The first step, which is pulping, is carried out in a 25 liter pulping apparatus equipped with a propeller mixer and the second step is carried out in a 15 liter flotation cell (Lamort apparatus).

The following mixture is placed in the pulper:

mixture of 50/50 old newspapers and old magazines: 1500 g sodium hydroxide (25%): 60 g hydrogen peroxide (30%): 50 g

Rhoditek 1000: 3.37 g

Synperonic A7: 0.18 g

Rhodasurf LA 30 0.75 g sodium silicate (33.8%, SiO ₂ / Na ₂ O 3.3 ratio) 44.40 g water at 45 ° C: 10 liters

The water has a controlled hardness; [Ca ²⁺ ] = 3 x 10 ^-3 mol / l and [Mg ²⁺ ] = 1 x 10 ^-3 mol / l.

Pulping and flotation is performed under the same conditions as above except that Rhodasurf LA 30 is added after the pulping step.

The float suspension is then filtered through a test sheet preparation machine. The test paper sheets are then dried and their whiteness according to ISO (diffuse blue reflection factor), measured according to NF standard Q 03-039, is 53.6.

Claims (10)

PATENT CLAIMS A liquid bleaching composition, characterized in that it comprises at least one first surfactant (A) and at least one second surfactant selected from (B) and / or (C): . The nonionic surfactant (A) consists of at least one polyethoxylated and polypropoxylated aliphatic fatty alcohol of the following general formula: r ¹ -o - [(ch ₂ ch ₂ o) _x . (ch ₂ -ch (ch ₃ ) O) _y ] H where: R ¹ is an alkyl group having 16 to 22 carbon atoms; the average value of x is between 5 and 30; the average value of y is between 2 and 20; • the non-ionic surfactant (B) is composed of at least one polyethoxylated aliphatic fatty alcohol of the following general formula: r ² -o- (ch ₂ ch ₂ o) _z -h where: R ² is a linear alkyl radical having 10 to 16 carbon atoms and preferably 12 to 16 carbon atoms; the mean z is selected such that the weight fraction of oxyethylene units is between 55 and 75% based on the weight of the surfactant (B); z is preferably 6 to 6 10; . the non-ionic surfactant (C) consists of at least one polyethoxylated aliphatic fatty alcohol corresponding to the following general formula: R ³ -O- (CH ₂ CH ₂ O) _w -H where: R ³ is a linear alkyl radical having 10 to 22 carbon atoms and preferably 12 to 14 carbon atoms; the mean w is selected such that the proportion by weight of oxyethylene units is between 35 and 45% based on the weight of the surfactant (C); w is preferably 2 to 4. Liquid decolorizing composition according to claim 1, characterized in that the liquid composition comprises at least one surfactant (A), at least one surfactant (B) and at least one surfactant (C). Liquid decolorizing agent according to any one of claims 1 or 2, characterized in that the weight ratio surfactant (B) / surfactant (A) is between 0.02 and 1. Liquid decolorizing agent according to any one of claims 1 to 3, characterized in that the weight ratio surfactant (C) / surfactant (A) is between 0.02 and 1. A liquid decolorizing agent according to any one of claims 1 to 4, characterized in that the nonionic surfactant (A) is a mixture of fatty alcohols, wherein the radical R ¹ is a linear alkyl group having 16 to 20 carbon atoms, with 11 oxyethylene units and 4. Oxypropylene units. An aqueous solution of the liquid decolorant according to any one of claims 1 to 5, characterized in that it contains 0.05 to 30% by weight of water, based on the total weight of the aqueous solution. Use of a liquid composition according to any one of claims 1 to 5 in decolouring paper. Use of the liquid composition of claim 7 in decolouring paper. A method for decolouring waste paper containing a color in the presence of a liquid composition according to any one of claims 1 to 5, characterized in that it comprises: . a first step consisting of pulping, wherein the waste paper containing the ink is contacted in the pulper with said composition and water, thereby converting the paper into paper pulp; . a second step consisting of at least one flotation step, wherein the pulp in the medium is diluted with water at an unchanged pH or at an altered basic pH ranging from 8.5 to 9. A method for decolouring waste ink-containing paper according to claim 9, characterized in that at least one surfactant (B) or (C) is added after the first step and before the second step.