JPH10219591A - New paper-reinforcing agent to be added - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject reinforcing agent capable of preventing the trouble stoppage of a paper-making system to ensure a stable operation by including a polyphosphate salt excellent in the corrosion-preventing effect on a device. SOLUTION: For example, a PAN-based anionic paper-reinforcing agent as a fry paper-reinforcing agent, or a urea-formaldehyde-based paper reinforcing agent as a wet paper-reinforcing agent is diluted with water to prepare a solution having a solid content concentration of 5%, and 0.005 pt. of sodium hexametaphosphate, anhydrous sodium pyrophosphate or anhydrous sodium tripolyphosphate as a polyphosphate salt is added and perfectly dissolved in 100 pts. of a paper-reinforcing agent aqueous solution under stirring. 0.1 pt. of the solution is again added and perfectly dissolved in 100 pts. of white water to obtain the objective reinforcing agent.

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 paper-strengthening agent for internal paper, which contains a polyphosphate having an excellent effect of preventing corrosion of device materials.

[0002]

2. Description of the Related Art In recent years,
In the papermaking industry, as the environment surrounding the market is becoming increasingly severe, such as deterioration of raw wood and chips and resource saving, deterioration of papermaking water quality due to closed drainage, upgrading and diversification of paper products, etc. We have been working to reduce the cost of products by increasing the size of equipment, speeding up papermaking, and increasing the recovery rate of waste paper. When trying to improve productivity and reduce costs, shutting down the operation due to troubles in the papermaking system 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 corrosion of equipment materials.

[0003] In the production of paper, in general, chips obtained by crushing raw wood are first digested in a digester to remove impurities such as lignin, and then colored impurities contained in pulp are removed from chlorine, sodium hypochlorite, chlorine dioxide and the like. Or a reducing agent such as sulfurous acid gas or sodium sulfite for bleaching by multistage bleaching. Thereafter, the pulp is sent to the next papermaking process through a preparation process for disintegrating, beating and mixing various chemicals.
In the papermaking process, excess water in the pulp slurry is filtered through a mesh called a wire and then wound on a reel through a pressing process, a drying process, and the like. The water filtered through the wire is called white water and is circulated and used to slurry the pulp in the preparation process. However, some of the chemicals used during the digestion and bleaching of the chips are sent to the papermaking process with some remaining in the pulp fiber.Therefore, this white water usually contains fillers contained in waste paper and water pumped up from rivers. In addition to various metal ions derived from the above, a large amount of chloride ions and sulfate ions derived from the above chemicals is contained.

[0004] Further, aluminum sulfate added to fix the anionic paper strength agent to the pulp fiber and sulfuric acid added to adjust the papermaking pH as needed also increase the sulfate ions in the white water. ing. Among these various ions, the incorporation of corrosive substances such as chloride ions and sulfate ions is a particularly serious problem because it corrodes metallic equipment materials and causes the papermaking system to stop operating. .

Corrosion is caused by erosion and corrosion caused by the above-mentioned chloride ions and sulfate ions. A large amount of white water flows from a fan pump, which flows at a high speed, to the inlet, the inside of a centrifugal screen, and a stirrer or circulation. The seal portion of the pump is noticeable. As a solution to this problem, at present, there is no suitable means other than improving corrosion resistance by upgrading equipment materials or switching to cooking chemicals or bleaching chemicals that do not contain corrosive components. Over the years, there has been a long-awaited need for suitable materials or methods to prevent equipment corrosion.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems facing the papermaking industry. As a result, as a means for preventing equipment corrosion, inexpensive inorganic salts have been used to enhance paper strength. When added to the pulp slurry after mixing with the agent, the corrosion resistance of the equipment material is improved without upgrading the equipment material and without having to change the cooking and bleaching chemicals currently in use to new ones. It has been found that this is possible, and the present invention has been completed. That is, the present invention provides a novel internal paper-strengthening agent characterized by containing a polyphosphate having an excellent effect of preventing corrosion of device materials.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
It is an object of the present invention to prevent a trouble of stopping a papermaking system caused by corrosive substances such as chloride ions and sulfate ions entering various types of chemicals into a papermaking system and corroding equipment materials, thereby stabilizing the system. It is an object of the present invention to provide an internal paper strength enhancer that enables an improved operation. The most effective means for achieving the above object is the introduction of inexpensive additives having a corrosion preventing effect. According to the study of the present inventors, a polyphosphate is most suitable as this additive. If an appropriate amount of this polyphosphate is mixed with the internal paper strength enhancer, the paper strength enhancer is added to the pulp slurry, then filtered through a wire, mixed with white water circulating in the papermaking system, and mixed with the surface of the equipment material. This is to prevent the corrosion of the device material by forming a firm metal phosphate film insoluble in water. Further, by previously mixing the polyphosphate with the internal paper strength enhancer, an additional equipment for separately supplying the papermaking system to the papermaking system becomes unnecessary.

[0008] Paper strength enhancers can be broadly classified into internal paper strength enhancers and externally added paper strength enhancers. In the present invention, in order to prevent corrosion of papermaking equipment materials, internal paper strength enhancers are used. Must be a force enhancer. Basically, any type of internal paper strength enhancer can be used in the present invention.

The reason why the present invention is limited to the internal paper strength enhancer is as follows. That is, the paper strength enhancer of the present invention is fixed to the pulp after being added to the pulp slurry and exhibits a paper strength enhancing effect, but the polyphosphate mixed in advance with the paper strength enhancer is as described above. This is because it is effective in preventing corrosion when it is filtered through a wire, mixed with white water and circulated through a papermaking system. For these reasons, the present invention is limited to internal paper strength enhancers.

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. It is not appropriate.

The internal paper strength enhancers are classified into dry paper strength enhancers and wet paper strength enhancers. PA as a dry paper strength agent
M type and starch type are typical examples. PAM-based paper strength enhancers that occupy the mainstream are generally classified into anionic PAM, cationic PAM and amphoteric PAM according to ionicity. Also has an anionic property, so that amphoteric P
It cannot be clearly distinguished from AM. 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. On the other hand, examples of wet paper strength enhancers include urea-formaldehyde resins, melamine-formaldehyde resins, epoxy-polyamide resins, and the like, 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 an apparatus material corrosion inhibitor of the present invention may be basically any water-soluble polyphosphate. For example, metaphosphate, pyrophosphate, tripolyphosphate, tetrapolyphosphate and the like can be mentioned. Among these, hexametaphosphoric acid, pyrophosphate and sodium salt of tripolyphosphate are considered from the balance between water solubility and price. It is suitable. All of these polyphosphates can be produced by a known method. Among the polyphosphates, there are hydrates as well as anhydrides, all of which can be used in the present invention.
Also, sodium tripolyphosphate has an l-type and an 11-type crystal modification, 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 not limited in detail because it slightly varies depending on the amount of the corrosive substance contained in the target papermaking white water. The amount is 0.01 to 5.0 parts by weight, preferably 0.1 part by weight, based on 100 parts by weight of the solid content of the paper strength enhancer.
05 to 1.0 part by weight. If the addition amount is less than 0.01 part by weight, the effect of preventing corrosion 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 having an effect of preventing corrosion of device materials as described above, when added to papermaking systems, it can be dried or wet. The paper strength and protect the equipment material from corrosive substances by adsorbing on the surface of the equipment material in the white water circulation line and other places to form a solid water-insoluble metal phosphate film Can be.

[0017]

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 viscometer, and the unit is centipoise (cP). The pH is a value measured with a pH meter after diluting 10 times with deionized water.

[0018]

[Table 1] For the purpose of the test, white water was collected from a paper company and analyzed for components. Table 2 shows the results of the analysis. In addition, p
H was 5.7 and electric conductivity (unit: mS / cm) was 3.43.

[0019]

[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
To each part, sodium hexametaphosphate, anhydrous sodium pyrophosphate and anhydrous sodium tripolyphosphate were added as polyphosphates under stirring with 0.005 part to completely dissolve. This was added to 100 parts of white water with stirring under 0.1 part and completely dissolved again. This is 250
Transfer to a clear plastic container and measure 20mm x 35m
A test piece made of iron and 18-8 stainless steel having a thickness of 3 mm and a thickness of 3 mm was immersed in the whole surface, sealed, set in a constant temperature bath at 50 ° C., and subjected to a corrosion test for one month. After one month, the test piece was taken out and washed sufficiently with water, the state of the surface of the test piece was observed, and the concentration of the metal eluted into the white water was measured.

Tables 3 to 5 show the observation results of the metal surface and the measurement results of the dissolved metal concentration in the white water. The surface states (Tables 3 to 5, and Tables 7 to 9) in the tables represent the following states. ○: Good gloss, no trace of corrosion △: Some gloss, poor with slight trace of corrosion ×: No gloss, poor with trace of corrosion

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

Example 2 After cutting cardboard in advance, the C.I. S. F is about 400ml
The mixture was beaten with a test beater until a slurry was obtained. The above white water is used for beating, and the pulp concentration is 1% on a dry basis.
It was adjusted to become. The pH of this pulp slurry was 6.0. This pulp slurry was collected in a plastic beaker, and a sizing agent 1 having a solid content of 1% was added thereto.
ml and stirred for 1 minute.
1 ml of a 20% aqueous solution of octahydrate was added and stirred again for 1 minute.

Separately, the above-mentioned various paper strength enhancers were prepared, and sodium hexametaphosphate, anhydrous sodium tripolyphosphate and anhydrous sodium pyrophosphate were used as polyphosphates with respect to 100 parts of the solid content of the paper strength enhancer. To 0.
One part was added under stirring and completely dissolved, and then diluted with white water so that the solid content concentration of the paper strength agent was 1%.
6 ml of this aqueous solution was added to the pulp slurry to prepare 1
After stirring for one minute, a part of this pulp slurry was collected and C.I. S. F was measured and hand-made paper was made using a test hand-made paper machine. Hand paper was prepared by adjusting the pulp concentration using tap water adjusted to pH 6.0 so that the rice basis of the paper was 120 g / m ² . 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 paper at temperature 20
The paper was subjected to humidity control for 24 hours in a constant temperature and humidity room at 65 ° C. and a humidity of 65% 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.

[0026]

[Table 6]

Comparative Example 1 A corrosion test was carried out in the same manner as in Example 1 except that no polyphosphate was added to the paper strength agent. Tables 7 to 9 show the observation results of the test piece surface and the measurement results of the dissolved metal concentration in the white water.

[0028]

[Table 7]

[0029]

[Table 8]

[0030]

[Table 9]

Comparative Example 2 The same procedure was followed as in Example 2 except that no polyphosphate was added to the paper strength agent. S. F and paper strength were measured. C. S. Table 10 shows the measurement results of F and paper strength.

[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.

[0033]

The novel paper-strengthening agent of the present invention contains a polyphosphate, and therefore has excellent ability to prevent corrosion of equipment materials and to stabilize the operation of the papermaking system. It is a force enhancer and its economic effect is great.

Claims (5)

[Claims] 1. A novel internal paper strength enhancer comprising a polyphosphate which is excellent in preventing corrosion of device materials. 2. The novel internal paper strength enhancer according to claim 1, wherein the content of the polyphosphate is 0.01 to 5.0 parts by weight based on 100 parts by weight of the solid content of the paper strength enhancer. . 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.