JPS60104589A - Purification of secondary fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION This invention relates to a method for cleaning secondary (i.e., not green or primary) cellulose fibers during repulping. In particular, the present invention effectively removes contaminants such as waxes and stickies from secondary fibers, disperses contaminants in the icy repulping medium, and removes contaminants from the pulp. Regarding how to put it out.

In accordance with the present invention, contaminants are almost completely removed from the secondary fibers, and they are sufficiently and permanently dispersed to prevent contaminants from depositing in newly formed sheets or on manufacturing equipment. can be prevented. These contaminants are commonly referred to as stickies, and include water-insoluble contaminants of various thermoplastic organic resins, such as waxes, hot melt adhesives, pressure sensitive adhesives, and adhesives.
- Includes nyl acetate type coating agents, SBR resins, latex adhesives, etc. Water-insoluble contaminants in inks and organic resins mentioned above are usually sticky and taraki (
It forms various types of deposits called stlckjes, tackjes).

These contaminants remain in the secondary fiber after repulping,
Alternatively, it can reagglomerate later in the paper manufacturing water, creating a wide variety of problems in the paper industry. This is especially noticeable in the manufacturing industry of corrugated pole liners and corrugated corrugated liners. This contaminant usually forms deposits on various papermaking equipment, such as the wet ends of press rolls and board making equipment, the polishing rolls of press sections, the surfaces of dryers, wires, press felts, and the like. This can result in sheet tears in the breaker stack, wrinkles in the winder, machine speed limitations due to wire fills, and work stoppages to clean up deposits, resulting in lost production time. and mechanical efficiency decreases. Furthermore, removing these deposits requires a large amount of solvent and manpower, which is not desirable. In addition, nutikki and taraki commonly contaminate the paper sheet itself and form deposits, causing sheet defects such as holes, deposits, speckles, and loss of gloss. Many of the products made from secondary fibers in medium paper manufacturing machines have slightly reduced water absorption due to contaminants.

By the way, in many paper manufacturing industries, re-rolled secondary fibers are used as raw materials. Paper products containing these above-mentioned fibers include terraces, paper towels, special quality products, corrugated liners, base paper, cylinder paperboard, and the like. In particular, in medium paper manufacturing machines and liner manufacturing machines, secondary fibers obtained from used medium paper are used as low-cost fibers. However, due to the presence of sticky deposits in the system and sheet, it is not practical to increase the ratio of secondary fibers to raw fibers.

Until recently, stickiness and taraki were primarily removed mechanically. For example, in the manufacture of towels, paper towels, battens, and secondary liners, suppression screens, reverse cleaning systems, and floating loops have been used to remove these contaminants during the secondary fiber processing process.

On the other hand, chemical methods using talc, polymers, and dispersants have not been very successful. Some attempts have been made to remove deposits in paperboard and liner manufacture using steam and asphalt dispersion units. However, these machines have high manufacturing costs and high running costs. Furthermore, although the known methods appear to be able to disperse the contaminants, they are unable to prevent the contaminants from reagglomerating. For example, when paper products are made from paper fibers that have been repulped, reagglomeration cannot be prevented.

Reagglomeration of contaminants typically results in the deposition problems described above. In many cases, the papermaking process is continuous, from repulping the secondary fibers to drying the new product. Also, manufacturing water is often redistributed into the system and reused. As a result, the contaminants may not be sufficiently dispersed or may even remain undispersed, creating problems when the treated water is recirculated through the system.

Therefore, repulped fibers inherently contain contaminants (waxes, stickies) that can be deposited in the papermaking system and on the sheet, reducing product yields and increasing prices. I end up.

The present invention is capable of significantly reducing (if not completely eliminating) the deposition of target contaminants on processing machinery and sheets when secondary fibers are used in papermaking processes. The secondary fibers obtained with this invention increase production throughput, reduce loss time for deposit removal, increase machine speed by preventing web breaks caused by sticky felts and rolls, It can improve drainage and speed up drying.

(Summary of the Invention) This invention particularly combines a nonionic surfactant and a dispersant to control foaming (e.g. antifoaming effect), achieve desired high ink efficiency, and improve the optical smoothness of handmade paper. The object of the present invention is to provide a method that can remove more contaminants from fibers than expected, and further limit the deposition and dispersion of contaminants.

This invention is a method for sufficiently removing and dispersing contaminants contained in secondary fibers during re-9urization. This method consists of a secondary fiber containing a contaminant, an effective amount of a substituent-containing oxyethylene glycol nonionic surfactant, and a water-soluble, low molecular weight polyelectrolyte dispersant containing a contaminant (
(at a temperature above the melting point of the contaminants to be removed from the secondary fibers); According to this method, it is possible to control stickiness and taraki more effectively than expected, as well as foaming control, and increase the optical smoothness of handmade paper.
High deinking efficiency can be obtained.

Here, the following terms are defined as follows.

"Cleaning type" or "washing" methods refer to well-dispersed secondary fiber whole-fiber methods that involve suspending contaminated secondary fibers in an icy medium and removing contaminants in an icy medium. dispersing in the medium and substantially separating the purified fibers from contaminants contained in the icy medium in a wash type step.

"Oxyethylene glycol surfactant with substituents"
is a nonionic surfactant having an oxyethylene glycol chain, in which the terminal hydroxyl group of the chain is substituted with either an aliphatic group or an alkyl aromatic ether group, and the other terminal Hydroxyl group? Substituted with a lyoxypropylene group or a pencil ether group.

Moreover, "low molecular weight" here refers to those having a molecular weight in the range of 500 to 50,000.

Also, "water soluble" as used herein refers to any material that can be sufficiently dissolved in water at room temperature to form a solution.

DETAILED DESCRIPTION OF THE INVENTION A typical process for this invention involves mixing contaminated secondary fibers with water, a substituent oxyethylene glycol surfactant, and a dispersant, thereby removing contaminants. Separated from the fibers, it is distributed or dispersed in a very stable manner in any icy fiber slurry or medium. In this case, each component is heated to a temperature above the melting point of the contaminant, or, if already at the desired temperature, e.g. due to heat in the system, held at that temperature to remove or disperse the contaminant. preferable. Generally this temperature is about 25
℃ to 85℃, often about 35℃ to 60℃
A typical range is ℃.

The purified fibers are separated or isolated from the contaminated aqueous medium by centrifugation, decanting, filtration, or preferably screening. For screen hanging,
There is a step in which a fiber bulb is passed through the holes in the perforated surface to retain and deposit the fibers while the icy medium is drained. As desired,
The step of separating or recovering contaminated fibers from the icy medium comprises:
A concentration or dilution step can be preceded and a washing type step can be performed, such as dilution and/or screening. These steps can be performed by stirring the diluted fiber slurry.

In this invention, contaminant control begins with re-pulping of the secondary fibers, ie, the surfactants and dispersants used in this invention are preferably during the re-luning process. However, the surfactant or dispersant may be added downstream from the repulping process, including the sidehill washer stage, or added to the caustic extraction stage of the bleach system, or even in combination. You may. It makes sense to select the dosing location in advance of the system exit, or where there are problems such as the dilution stage or where the temperature changes (here, causing contaminant deposition). I am getting .

When using purified secondary fibers, the accumulation of contaminants on paper processing machinery is a common experience. This is especially true when the purified fibers are obtained from papers with high water resistance, for example from wax-coated papers (such as cold cups) or from lined paper products (such as carton paper or box paper). It is. In this type of contaminant environment, contaminant deposition is effectively inhibited by substituent oxyethylene glycol surfactants (see below, U.S. Patent Application No. 093,744.1).
This problem can also occur even if the application (filed on November 13, 1979) is used.

When carrying out this invention, by introducing a water-soluble, low molecular weight polyelectrolyte dispersant and oxyethylene glycol having a substituent into the re-reconversion environment, contaminants can be effectively removed from the processing solvent. distributed. This was completely unexpected and unexpected.

This dispersion of contaminants into the liquid repulping medium was able to significantly reduce the build-up of target material on processing machinery during the papermaking process that follows repulping. This reduced work stoppage time. The secondary fibers obtained by this invention are later used in the paper manufacturing process, and their use significantly reduces sticky and taraki deposits that generally adhere to machines and the sheets themselves, thereby increasing machine efficiency. can be increased.

Furthermore, the polyelectrolyte dispersant here preferentially inhibits the formation of certain insoluble reaction products by complexing. That is, the reaction product is formed by metal ions such as calcium and magnesium and organic materials such as fatty acids (often components of printing inks), resins, casein and starch, which are usually present in secondary fibers. , this is prevented with a dispersant. Such insoluble hard water reaction products are similar to bathtub and hard water deposits.

This invention uses nonionic surface activators or surfactants. The surfactant comprises an oxyethylene glycol chain, the terminal hydroxyl group of this chain being replaced with an ether group selected from the group consisting of aliphatic ether groups and alkyl aromatic ether groups, and the other terminal hydroxyl group of this chain It is substituted with an ether group selected from the group consisting of polyoxyzolopyrene groups and benzyl ether groups. A typical general formula of the preferred surfactant of this invention is as follows.

R(-ArdOC2H4dOc3H6)-Y where a is 0 or 1, Ar represents an aromatic residue, preferably a monocyclic % formula % R represents an aliphatic group.

n has a value of 3-50.

m has a value of 0 to 50.

Y is selected from the group consisting of hydroxyl group and benzyl ether, and when m=0, it is benzyl ether.

Representative R groups are saturated and contain at least 6 carbons. When a is O, R contains 6 to 24 carbons.

When a is 1, R usually contains only 18 carbon atoms. In short, the R(Ar)a group contains at least 6 aliphatic carbon atoms and up to 24 carbon atoms total.

The above structural formula is believed to include two main types of surfactants as shown below. Namely, a, an alkylene oxide adduct of an alkylphenol, and b, a high (even higher than C5 aliphatic alcohol) alkylene oxide adduct can be considered. Details of these surfactants are described in U.S. Pat. , the contents of which are incorporated herein by reference.

Following U.S. Patent Application No. 4,093,744, U.S. Patent Application No. 4
There are 458432. The invention relates to cleaning methods for deinking and cleaning secondary fibers, and further relates to the use of substituted oxyethylene glycol nonionic surfactants in such cleaning type deinking and cleaning methods. . Deinking cleaning methods are distinguished from flotation methods, which are more technically complex and generally require more investment. Substituted oxyethylene glycol nonionic surfactants are described in U.S. Pat.
No. 93,744, the use of which results in unexpectedly low foaming at various processing temperatures and improved deinking and cleaning efficiency (compared to conventional cleaning methods).

The process herein, like U.S. Pat. Its drawbacks can be prevented or mitigated compared to the more capital-intensive and more sensitive floating method. This invention is based on the discovery of a special dispersant that has the effect of enhancing the effectiveness of the substituent oxyethylene glycol surfactants shown in US Pat. No. 4,937,44. This is contrary to expectations.

18- In the present invention, the dispersant substantially completely removes and sufficiently permanently disperses secondary fiber resin contaminants;
Prevent dispersion within the sheet or product.

The invention further includes the use of polyelectrolyte dispersants. Here, the term "polymer electrolyte dispersant" includes any homopolymer, binary copolymer, terpolymer, etc. of the following structural formula.

Here, R1, R2, R4 and R5 are independent, hydrogen,
C1 to C4 lower alkyl group, alkyl carboxyl group (
For example, -CH2C00H) or a mixture thereof. R and R6 can be hydrogen, xyl, alkylcarboxyl, or a mixture thereof. X can also be a carboxyl group (including salts or derivatives thereof, e.g. amides), an acetyl group, or a hydrocarbon group attached to a free radically polymerizable monomer (e.g. -C in styrene).
6H5). Also, a ten is 15 to about 1
Takes the value 000.

Examples of materials represented by the above general formula include polymaleic acid, polyacrylic acid, polymethacrylic acid, copolymers of polyacrylic acid and itaconic acid, copolymers of polyacrylic acid and hydrolyzed maleic acid, Copolymers of polymaleic acid and itaconic acid, copolymers of hydrolyzed polymaleic acid and vinyl acetate, copolymers of polyacrylic acid and acrylamide, copolymers of polyacrylic acid and methacrylic acid, styrene and maleic acid, copolymers of sulfonated styrene and maleic acid, copolymers of polymaleic acid and methacrylic acid, maleic acid telomer, and maleic acid/alkylsulfonic acid copolymers.

A particularly preferred water-soluble polymer electrolyte used in this invention is a polyacrylate compound. The I-reacrylade compound is a polymer, copolymer, or derivative thereof having the following structure, where R2*R5rXr& and b are the same as those described above.

In this invention, in particular, it is most preferable that X is -COOZ (Z is H or a monovalent cation such as Na'' + K''*NH4+). As described above, the representative and most preferred polymer electrolyte of the present invention is polyacrylic acid (for example, B,
F, Gutdrich K732), polymethacrylic acid (e.g. Tamol 850 manufactured by Rohm and Hass)
) and acrylic acid/methacrylic acid copolymer (AQUATREAT manufactured by Alco Chemical).

The polymer electrolyte of this invention must be water-soluble. Generally, to be water soluble, a polymer must have sufficient polar groups (eg, COOH) in the molecule to interact with polar water molecules.

This means that copolymers, binary copolymers, ternary copolymers, quaternary copolymers, etc. whose main portion or all are unsaturated monomers have polar functional groups in the polymer, and Must be soluble in water. Generally, at least 10 molar portions of the monomers constituting the polymer must have polar functional groups, such as, and have the desired water solubility.

The low molecular weight polyelectrolytes of this invention generally have about 50%
000, preferably from about 500 to
25,000, particularly preferably 750-5,000.

Further, the sum of a's is generally 5 to 1ooo, preferably 10 to 500, particularly preferably 12 to 450. It is known that the 22-material having a molecular weight in the above range has a lower molecular weight than polymers generally used as flocculants, that is, polymers having a molecular weight of several million or more. The flocculant acts to flocculate the suspended particles for the desired dispersion effect described herein. These high molecular weight materials therefore have the opposite effect than the materials mentioned above. The low molecular weight materials of this invention generally include:
Known as a "dispersant".

Operationally, the electrolyte of the present invention is mixed in a predetermined amount into an icy surfactant to prevent contaminants (e.g., pigment materials, coatings, fillers, adhesives, etc.) from depositing on processing equipment. must be prevented. Generally the concentration of this polyelectrolyte is about 5 to 500 ppm, preferably about 1
It is 0 to 75 ppm.

Another area in which the invention is particularly useful is in the cleaning of secondary fibers loaded with photocopy ink (eg, recycled photocopy materials). Photocopies may be made on coated or uncoated paper. Coated paper is attached and impregnated with various materials, increasing the ability of the paper and making it easier to attach electrophotographic imaging powder.
It can be stored permanently. Electrophotographic coatings, paper anti-bleeding materials, and imaging powders tend to become suspended (e.g., temporarily kept in solution by physical agitation of the liquid) during the repulping stage. They therefore form as a result of the final solidification or are deposited on the processing equipment only when the icy process vapor has cooled or if agitation is insufficient. Thus, the electrolytes described herein can be used to reduce or substantially eliminate such deposits in combination with substituent oxyethylene glycols.

Another area in which the invention may be practiced is in the deinking and cleaning of newsprint. Newsprint paper that is recycled is
Distinguished from other secondary fiber sources. This is because the printing inks used are printed directly onto uncoated, strong fibers. Other secondary fiber sources include
Printing is done on coated fibers. That is, it is not applied directly to the fiber itself. When deinking newsprint, basically all of the printing ink, which is relatively difficult to disperse, is removed. Since it contains 12q6 to 4 inches (wt%) of printing ink consisting of black, it becomes more difficult to remove the ink. Newsprint paper that is recycled is useful in large quantities, so a method for sufficiently deinking and purifying newsprint paper is most urgently needed in the secondary textile industry.

In this invention, various known solvents or auxiliary solvents can be used as appropriate in addition to the dispersant and the surfactant. Examples of particularly preferred solvents include tetrahydro7rane, tetrahydrofurfural alcohol and their ethoxylated and propylated derivatives.

Examples of the present invention will be described below. However, the present invention is not limited to this embodiment.

Example 1 A "cold cup" or drinking cup made of wax-coated paper for making handmade paper was deinked and clarified on an experimental scale using the deinking composition of Table IA. Ta.

Place the cold cup into the pulp machine under stirring) 71
℃ (below 160) for 60 minutes to repulp.

Table IA Materials Quantity Water 250ml Fiber base paper (deinked and purified) 18.8
F Chlorine dioxide (10%) 19m1 NaOH (50% aqueous solution) 0.4mt! Oxyethylene glycol (10%) with substituents
Medium 0.4ml 26- Table IB (Solvent) 1.50% by weight kerosene and 50% by weight aromatic naphtha (in nonylphenol-(E9)6-OH emulsifier) 2, butyl
"Calpitol" (diethylene glycol monobutyl ether) 3. "Pentoxone" (4-methoxy-4methyl-pentanone, manufactured by Shell Chemical ■) 4. Tetrahydrofuran (manufactured by Quaker-P Chemical ■) 5. Tetrahydrofuran with a mononidoxylene group Frill Alcohol (manufactured by Quaker Otes) Handsheets obtained from deinked and purified cold cups have improved gloss, but do not contain colored wax on the equipment (i.e. on the inside of the glass breaker). There was collective deposition. Then various dispersants were added to the deinking composition using /I61 solvent (see mixture of kerosene and aromatic naphtha).
Added in large amounts of ppm. The dispersants used are shown in Table IC
Shown below. Dispersants A1a, 2a, 3a in Table IC are of the invention.

Table IC (dispersant) 1a, 15% by weight aqueous solution “Dequent 20541 (
5m), 12% by weight of 50150 molti copolymer (see
Copolymer of hydrolyzed maleic anhydride and vinyl acetate with a molecular weight of about 3000) 2a, 50150 molar copolymer (copolymer of hydrolyzed maleic anhydride and vinyl acetate with a molecular weight of about 3000 (50% active) 3m, polyacrylic acid with a molecular weight of about 3,000, for example, Gudrite and 732. B, F, made by Gutdrich ■) (5
0% activity) 4a, sodium salt solution of ethylenediaminetetraacetic acid,
40% activity (e.g. Percent 100, manufactured by Dow Chemical ■) 5m, hexapotassium salt bath solution of hexamethylene diamine tetramethylene phosphonic acid, 36% active (e.g. Dequest 2054 manufactured by Monsanto ■) Handmade paper is made using the above composition. and its hunter optical smoothness was determined. This result is assigned to table ID. From Table ID, the best solvent and dispersant combination for this invention (i.e., the combination that results in the least wax deposits and increased optical slippage) has a molecular weight of approximately 3000. It can be seen that it is a combination of a lyacrylic acid dispersant and tetrahydrofurfuryl alcohol (linear chain 9Eo).

29-30- Example ■ The secondary fibers to which electrophotographic ink and/or electrostatic coating material were attached were deinked and purified to obtain handsheet paper. The glossiness of this handmade paper is shown in Table ■. Oxyethylene glycols having substituents shown in Table ■, nonylphenol, j? IJ ethylene (EO) oxide is a nonionic surfactant with an average of 95 moles of ethylene oxide per mole of nonylphenol.

Additionally, various amounts of propylene oxide (po)
is condensed with ethylene oxide chain soil to create an oxyethylene glycol nonionic surface agent with substituent groups (having various deinking properties). Other compositions for obtaining the gloss level of handmade paper are as shown in Table 1: 250 ml of water, 15 g of base paper for electrophotographic coating, 0.092 g.
50% NaOH. Substituted oxyethylene glycol was added in a limit of 0.041 nl and co-solvent c) in a limit of 4 ml (if added).

Note that two sheets of handmade paper were prepared for each example, and the glossiness was expressed as the average of the two sheets.

From Table 1, it can be seen that the nonylphenol ethoxy sheet has good deinking properties and its fibers exhibit electrophotographic quality.

From these results, the nonylphenol ethoxy sheet with more propylene oxide had slightly better performance than the one with less propylene oxide. Additionally, +9 lyacrylic acid dispersants, having a molecular weight of about 3000, have been found to enhance deinking and cleaning compared to those without them. Finally, wax-coated paper is
Addition of a cosolvent only slightly improved the deinking properties of the electrophotographic paper.

=33 Example m Various deinking surfactants, dispersants, and auxiliary solvents were combined to deink and purify Shinkai printing paper. This newsprint paper was reprinted as described in Example 1. A standard deinking/cleaning/re-rugging medium is as follows.

Water 500mA! Sodium metasilicate 0.5 F Newsprint 25.0 Pm Oxyethylene glycol o4P with substituents? 7L dispersant 25 ppm Auxiliary 1 line (if added) The glossiness (Hunter reflectance meter value) of handsheet paper obtained by deinking 03 nine-deinked newsprint paper is shown in Table 2.

34- Table ■ Oxygen with substituents Glossiness 35-

Claims (1)

[Scope of Claims] (1) A method for removing and dispersing pollutants from pollutant-containing secondary fibers during rerupping, comprising: a. a pollutant-containing secondary fiber and oxyethylene having a substituent; an effective amount of a glycol nonionic surfactant, an effective amount of a water-soluble low molecular weight polyelectrolyte dispersant, a medium having a temperature above the melting point of the contaminant to be removed from the secondary fibers, and a thermoplastic organic resin. containing water-insoluble waxes, adhesives or resins,
forming an aqueous repulping medium with a contaminant; b. dispersing the contaminant from the secondary fibers into the icy repulping medium so as to substantially disperse the contaminant-containing repulping medium; A method for purifying secondary fibers comprising: obtaining substantially purified fibers; and separating the CO substantially purified fibers from an icy repulping medium containing contaminants. 2. A method for purifying secondary fibers according to claim 1, wherein the icy repulping medium is at a temperature of about 25°C to 85°C. 3. A method for purifying secondary fibers according to claim 1, wherein the aqueous resolification medium is at a temperature of about 35°C to 60°C. 4. A method for purifying secondary fibers according to claim 1, wherein the substantially purified fibers are separated by screening. 5. The method of purifying secondary fibers according to claim 1, wherein the aqueous re-rugging medium further comprises tetranohydrofurfural alcohol, an ethoxylated derivative thereof, or a mixture thereof. 6. The method for purifying secondary fibers according to claim 1, further comprising the step of washing the substantially purified fibers. 7. The method for purifying secondary fibers according to claim 6, wherein the washing step includes a step of diluting the fibers to obtain a fiber slurry, and a step of separating the fibers from the slurry. 8. The polymer electrolyte dispersant comprises a copolymer of maleic acid and vinyl acetate.
Next fiber purification method. 9. The secondary fiber cleaning power method according to claim 1, wherein the polymer electrolyte dispersant contains a polyacrylic acid compound. 10 Polyacrylic acid compound has a molecular weight of 500 to 2500
The method for purifying secondary fibers according to claim 9, wherein the secondary fiber purification method is 0. 11 The polymer electrolyte dispersant has the structure shown below, and in the above structure, R1, R2, R4 and R5 are independently
, hydrogen, a C1-C4 lower alkyl group, an alkylcarboxyl group, or a mixture thereof. R3 and R6 are independently selected from the group consisting of oxy, hydrogen, carboxyl, alkylcarboxyl, or mixtures thereof. X is a carboxyl group, a salt or derivative of a carboxyl group,
an acetyl group, a hydrocarbon group attached to a free radically polymerizable monomer, cooz (z is a Hl-valent metal ion or ammonium, or a mixture thereof). Also a ten is 15
~1000 range of s, q as in 1, reverse heat 1, IJ lianggen chen 嘱 2 (, rectifier 71-tube i dimension,. 12, R1+ R3+R4 and R6 are hydrogen, R2 and R5 are hydrogen or methyl groups , X is a carboxyl group. 13. The method for purifying secondary fibers according to claim 1, wherein the contaminant includes wax. 14. Contamination. Purifying power method of secondary fibers according to claim 1, in which the substance includes an adhesive substance. 15. Claim 1, in which the secondary fibers include a tiered plate.
Method for purifying secondary fibers as described in Section 1. 16. Claim 15 in which the contaminant includes wax
Method for purifying secondary fibers as described in Section 1. 17. The method for purifying secondary fibers according to claim 15, wherein the contaminant includes a hot-melt adhesive.