JPH10183490A - New internally mixing paper-strengthening agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an internally mixing paper-strengthening agent capable of preventing scaling in a papermaking process and enabling stable operation by adding a specific water-soluble polyphosphoric acid salt to an aqueous solution of paper-strengthening agent. SOLUTION: This internally mixing paper-strengthening agent is prepared by adding a water-soluble polyphosphoric acid salt having a multidentate ligand forming a chelate compound by bonding to a metal ion, such as sodium hexametaphosphate in the molecule in an amount of 0.01-5.00 pts.wt. based on 100 pts.wt. solid content of the composition as a scaling preventing agent to an aqueous solution of dry paper-strengthening agent such as Mannich- modified or Hoffmann-modified polyacrylamide and a wet paper-strengthening agent such as a urea-formaldehyde-based resin or a melamine-formaldehyde- based resin and mixing these components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a paper strength enhancer. More specifically, the present invention relates to a novel internal paper strength enhancer containing a water-soluble polyphosphate having an excellent anti-scaling effect.

[0002]

2. Description of the Related Art In recent years,
The papermaking industry has been improving productivity and reducing costs mainly by increasing the size of equipment and speeding up papermaking. However, when trying to improve productivity, the stoppage of operation due to a papermaking system trouble is a very serious problem because the higher the papermaking speed, the greater the reduction in production. One of the causes of papermaking problems is the deterioration of papermaking water quality.

[0003] Paper is prepared by dispersing pulp fiber in a large amount of water, adding a sizing agent, bansulfate, a paper strength agent, a drainage agent, and the like, as necessary, to a paper. Drain by draining on a net. Next, after being pressed with a roll and drained further, it is dried with a drier and, if necessary, subjected to a calendering process or the like, and wound up on a reel. The water filtered through the wire is called white water and is circulated and used to slurry the pulp.

[0004] Fresh water, which is newly added for the purpose of replenishing water evaporated in a dryer and maintaining the quality of white water, is supplied to a papermaking system in the form of dilution water for a paper strength enhancer to be added or washing water for wires and rolls. Supplied. Water is rarely used because fresh water is used in large quantities. Usually, river water and well water are pumped and used. Although there is a difference depending on the area, river water and well water usually contain a large amount of suspended suspended solids, and a large amount of metals such as calcium, magnesium, iron, and silicon are dissolved in the form of oxides and carbonates. Even though it is called Shimizu, it actually contains such many impurities. Recently, the recovery rate of waste paper has increased significantly from the viewpoint of environmental protection, and the amount of calcium carbonate and white carbon, etc., contained in waste paper as fillers in water has increased, and the quality of papermaking water has deteriorated. I'm going all the way.

When metals such as calcium and magnesium in the white water are ionized and circulated through the papermaking system, they absorb carbon dioxide in the air and combine with them, or combine with carbonate ions derived from the filler to form new ones. It becomes crystals of calcium carbonate and magnesium carbonate and attaches as scale to piping, wires, rolls, etc. in the circulation line. In addition, when Shimizu is used as dilution water for the paper strength enhancer, the clay-like suspended substances contained in the Shimizu agglomerate in the pipe due to the cohesive force of the paper strength enhancer, and the dissolved metal salts become water temperature. When it is crystallized and precipitated due to a cause such as a decrease in the size, it is complicatedly entangled with this and forms a stronger scale and adheres to the inner wall of the pipe or the like.
These scales block the circulation line and the raw material supply line, causing a decrease in flow rate, and the peeled scale is mixed into the pulp slurry to damage the paper formation or cause paper breakage, that is, paper breakage. To a shutdown. In recent years, the frequency of occurrence of troubles due to such scale has been dramatically increased due to the progress of closed papermaking wastewater.

In order to solve this problem, a chelating reagent having a polydentate ligand in a molecule such as polyaminocarboxylic acid such as ethylenediaminetetraacetic acid, oxycarboxylic acid such as citric acid, maleic acid or phosphonic acid has been conventionally used in Shimizu. Alternatively, a method has been attempted in which white water is added to a circulation line to block metal ions such as calcium and magnesium to prevent scale from being generated.

[0007] The present inventors have confirmed that the sequestering ability of the metal ion and the amount of generated scale clearly have an inverse correlation, and then examined the ion sequestering ability of the above-mentioned conventional product for metal ions such as calcium and magnesium. As a result, they found that these conventional products had a small sequestering ability for their price, and needed to be added in unexpectedly large amounts in order to prevent crystal precipitation of salts such as calcium and magnesium. . That is, conventionally used chelating reagents such as ethylenediaminetetraacetic acid are inferior in cost performance as an anti-scaling agent, and are expected to become even more severe in the future. For the paper industry, which has to respond to the growing internationalization, traditional antiscaling agents have not always been satisfactory.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide various kinds of metal ions and clayey suspended substances contained in river water and well water used as fresh water in a papermaking system of a paper mill, or as a filler. Provide an internal paper strength enhancer that prevents papermaking-related troubles caused by calcium carbonate and the like contained in used paper mixed into white water and deteriorating the papermaking water quality, and enables stable operation. It is in. The present inventors have conducted intensive studies to solve the above problems facing the paper industry, and as a result, using a cheap inorganic water-soluble chelating reagent instead of the conventional organic water-soluble chelating reagent as a scaling inhibitor. It has been found that, when used in combination with a paper strength enhancer, the same sequestering ability can be exhibited with a much smaller addition amount than conventional products, and the present invention has been completed.

That is, the present invention provides a novel internal paper strength enhancer containing a polyphosphate having an excellent scaling-preventing effect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Paper strength enhancers can be broadly classified into internal paper strength enhancers and externally added paper strength enhancers. In the present invention, basically any type of internal strength paper enhancer is used. It is possible.

The reason why the present invention is limited to the internal paper strength enhancer is as follows. That is, in order to simultaneously exert the paper strength enhancing effect and the scaling prevention effect, the paper strength enhancing agent of the present invention must be added to the pulp slurry before it is made with a wire and sufficiently dispersed. That is,
It must be an internal paper strength enhancer. This is because the polyphosphate mixed in advance with the paper strength agent is filtered through a wire during papermaking, mixed with white water circulating in the papermaking system to block metal ions dissolved in the white water, This is because, by preventing the flocculation of the clay-like suspended matter by the effect of dispersing the fine particles of the acid salt, the scale is prevented from adhering to the piping, wires, rolls and the like of the circulation line.

When the present invention is applied to an external paper strength enhancer, most of the polyphosphate is converted into a product through a drying process together with the pulp fiber without being mixed into the circulating white water, so that the meaning of addition is lost. It is not appropriate. Internal paper strength enhancers are classified into dry strength and wet strength. PAM-based and starch-based are typical examples of the dry paper strength enhancer. PAM-based paper strength enhancers that occupy the mainstream are generally classified into anionic PAM, cationic PAM and amphoteric PAM according to ionicity. As described above, those usually referred to as cationic PAM are partially used. Cannot be clearly distinguished from amphoteric PAM. In the present invention, description will be made by classifying the anionic PAM and the amphoteric PAM into two types.

The anionic PAM comprises acrylamide,
It is produced by a known method such as copolymerization with an anionic monomer such as acrylic acid or itaconic acid, or hydrolysis of PAM with an alkali. The amphoteric PAM is produced by a known method such as Mannich reaction or Hoffman decomposition reaction of PAM, or copolymerization of acrylamide with a cationic monomer represented by dimethylaminoethyl methacrylate and an anionic monomer such as acrylic acid or itaconic acid. Is done.

On the other hand, examples of wet paper strength enhancers include urea-formaldehyde resins, melamine-formaldehyde resins, and epoxy-polyamide resins, all of which are produced by known methods. Any of the various internal paper strength enhancers described above can be suitably used as the paper strength enhancer of the present invention.

In the present invention, the polyphosphate may be added in the form of a powder or an aqueous solution during or after the production of the various internal paper strength enhancers. Usually, polymerization reaction or addition reaction for producing paper strength agent or cooling, dilution, pH
Immediately after the adjustment and other operations are completed, immediately before the product is transferred to a product tank, container, lorry, or the like, the paper strength enhancer is added as a powder or in the form of an aqueous solution with sufficient stirring and mixing.

The polyphosphate which can be used as the scaling inhibitor of the present invention has a polydentate ligand which forms a chelate compound by binding to a metal ion such as calcium or magnesium in the molecule, and Basically, any water-soluble material may be used. For example, metaphosphate, pyrophosphate, tripolyphosphate, tetrapolyphosphate and the like can be mentioned. Among them, hexametaphosphoric acid, pyrophosphate and tripolyphosphate are considered from the balance between sequestering ability, water solubility and price. The sodium salt of the acid is preferred. All of these polyphosphates can be produced by a known method.

Among the polyphosphates, there are hydrates in addition to anhydrides, and any of them can be used in the present invention. Also,
Sodium tripolyphosphate has 1-type and 11-type crystal modifications, both of which can be used in the present invention. In the present invention, the amount of the polyphosphate to be added to the paper strength enhancer is somewhat dependent on the concentration of metal ions and suspended solids contained in the target papermaking system white water or fresh water, and the magnitude of the chelating effect of the polyphosphate. Although the details cannot be limited due to the fluctuation, usually 0.01 to 100 parts by weight of the solid content of the paper strength agent is used.
To 5.00 parts by weight, preferably 0.05 to 1.00 parts by weight. If the amount is less than 0.01 parts by weight, the effect of preventing scaling is weak, and if it exceeds 5.0 parts by weight, the cost is increased for the effect, which is not preferable.

Since the novel paper-strengthening agent of the present invention contains polyphosphates as a scaling inhibitor as described above, when added to a papermaking system, the paper-strength when dry or wet is reduced. In addition to the strengthening, it is possible to prevent the generation of scale in the circulation line of the white water or the supply line of the paper strength enhancer and other places.

[0019]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to these examples unless the gist is changed. In the following, parts and percentages are by weight unless otherwise specified. Example 1 PAM-based anionic paper strength enhancer (Hopron 3150B, manufactured by Mitsui Toatsu Chemicals, Inc.) and Mannich modified paper strength enhancer (Mitsui Toatsu Chemicals, Hoplon 254MX, as dry paper strength enhancers) ), Hoffman modified paper strength enhancer (Mitsui Toatsu Chemicals, Inc., New Hoffman PAM), copolymerizable paper strength enhancer (Mitsui Toatsu Chemicals, Hopron 106), and wet strength Urea-formaldehyde paper strength agent (P-1500, manufactured by Euramine Industry Co., Ltd.)
Melamine-formaldehyde paper strength enhancer (P-6300, manufactured by Euramine Industry Co., Ltd.), epoxy-polyamide paper strength enhancer (P-56, manufactured by Tohoku Euroid Industries, Ltd.)
00) was prepared and a test for confirming the sequestering ability of metal ions was performed. Table 1 shows the physical property values of each of the above paper strength enhancers. The viscosity is a value measured at 25 ° C. by a BM type viscometer, and the unit is centipoise. The pH is a value measured with a pH meter after diluting 10 times with deionized water.

[0020]

[Table 1] For the purpose of the test, river water and well water were collected and analyzed for their components. Table 2 shows the analysis results. The pH was 7.6 for river water and 7.2 for well water.

[0021]

[Table 2] First, each of the above-mentioned paper strength enhancers is diluted with tap water to adjust the solid content concentration to 5%, and then, each of the paper strength enhancer aqueous solutions 100
Parts (solids 5 parts) was added with 0.1 parts of anhydrous sodium carbonate.
Was added under stirring to completely dissolve. Next, sodium hexametaphosphate, sodium pyrophosphate anhydride and sodium tripolyphosphate anhydride were added as a polyphosphate to each aqueous solution in an amount of 0.05 part, 0.0025 part,
Then, 400 parts of river water and well water were added, and the mixture was stirred at 25 ° C. for 1 hour. Stirring was adjusted so that all samples had the same strength. After stirring for 1 hour, a turbidity meter (Tokyo Denshoku Co., Ltd., T
Turbidity of each of the aqueous solutions was measured using a method of measuring -2600DB). The turbidity is the turbidity of water when kaolin is dispersed in water, expressed in terms of the kaolin addition rate (unit: ppm). Tables 3 to 5 show the measurement results of the turbidity.

Example 2 After the cardboard was shredded in advance, C.I. S. F is about 400ml
The mixture was beaten with a test beater until a slurry was obtained. Next, tap water was added to the pulp slurry to adjust the pulp concentration to 1% on a dry basis. The pH of this pulp slurry was 6.1. This pulp slurry 2 was collected in a plastic beaker, and the solid content concentration 1
% Sizing agent was added and stirred for 1 minute. Then, 1 ml of a 20% aqueous solution of aluminum sulfate · 18 hydrate was added, and the mixture was stirred again for 1 minute. Separately, 0.1 part of each of the polyphosphates used in Example 1 was added to 100 parts of the solid components of the various paper strength enhancers of Example 1 with stirring to dissolve them completely. A solution diluted with tap water was prepared so that the solid content concentration of the paper strength enhancer was 1%. This aqueous solution 6
ml was added to the above pulp slurry and further stirred for 1 minute. S.
The measurement of F and hand papermaking were performed. Hand-made paper should have a pH of 6.0
The pulp concentration was adjusted so that the rice tsubo of the paper became 120 g / m ² by using the adjusted tap water. After the hand-making was completed, the wet paper was dehydrated with a test press and then dried with a rotary drum dryer adjusted to a surface temperature of 110 ° C. Dry the paper in a constant temperature and humidity room at a temperature of 20 ° C and a humidity of 65%.
The sample was conditioned for 4 hours and subjected to paper strength measurement. The PAM-based paper strength enhancer was measured for dry paper strength, and the urea-formaldehyde-based, melamine-formaldehyde-based, and epoxy-polyamide-based paper strength enhancers were measured for wet paper strength.
C. S. Table 6 shows the measurement results of F and paper strength.

Comparative Example 1 A polyphosphate was prepared by disodium ethylenediaminetetraacetate.
Turbidity was measured in the same manner as in Example 1 except that dihydrate, citric acid / monohydrate and maleic acid were used. Tables 7 to 9 show the measurement results of the turbidity.

Comparative Example 2 The polyphosphate was disodium ethylenediaminetetraacetate.
Except for changing to dihydrate, citric acid / monohydrate, and maleic acid, all operations were the same as in Example 2, and C.I. S. F and paper strength were measured. C. S. Table 1 shows the measurement results of F and paper strength.
0 is shown.

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

[0029]

[Table 7]

[0030]

[Table 8]

[0031]

[Table 9]

[0032]

[Table 10] In Tables 6 and 10, urea-phor is a urea-formaldehyde resin, melamine is a melamine-formaldehyde resin, epoxy is an epoxy-polyamide resin, hexameta is sodium hexametaphosphate, tripoly is sodium tripolyphosphate, pyro Means sodium pyrophosphate, EDTA means disodium ethylenediaminetetraacetate dihydrate, and citric acid means citric acid monohydrate.

[0033]

As described above, the examples and comparative examples show that the novel paper-strengthening agent of the present invention has a small addition amount of 1/10 or less of the conventional chelating reagents such as ethylenediaminetetraacetic acid and citric acid. Since it contains an inexpensive polyphosphate having the same anti-scaling ability as above, it is an extremely cost-effective internal paper strength enhancer. As described above, the novel paper-strengthening agent of the present invention has an improved effect of preventing the generation of scale without lowering the original paper-strengthening effect in order to stabilize the operation of the papermaking system. , Its economic effect is enormous.

Claims (5)

[Claims] 1. A novel internal paper strength enhancer comprising a polyphosphate having an excellent anti-scaling effect. 2. The content of the polyphosphate is 0.01 to 5.00 per 100 parts by weight of the solid content of the paper strength agent.
The novel internal paper strength enhancer according to claim 1, which is in parts by weight. 3. The novel internal addition according to claim 1, wherein the polyphosphate has a polydentate ligand which binds to a metal ion to form a chelate compound in the molecule and is water-soluble. Paper strength enhancer. 4. The novel internal paper strength according to claim 1, wherein the paper strength enhancer is a polyacrylamide-based resin aqueous solution, a urea-formaldehyde-based resin aqueous solution, a melamine-formaldehyde-based resin aqueous solution, or an epoxy-polyamide-based resin aqueous solution. Enhancer. 5. An aqueous solution of a polyacrylamide resin,
The novel internal paper strength enhancer according to claim 4, which is an anionic polyacrylamide, a Mannich-modified polyacrylamide, a Hoffman-modified polyacrylamide, or a copolymerized polyacrylamide with an anionic monomer and a cationic monomer.