JPH0711517B2 - Phosphorus segregation detection sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a phosphorus segregation portion detection sheet for quickly and easily detecting the distribution state of phosphorus in metal materials such as continuously cast slabs and large steel ingots. is there.

<Prior Art> Conventionally, the segregation portion of a large steel ingot is determined by a sulfaprint test method. This method is widely used as a method in which a photographic printing paper soaked in a sulfuric acid aqueous solution is attached to the test surface that has been cut from a large steel ingot and polished, and hydrogen sulfide generated from the sulfa segregation part is detected on the photographic printing paper. is doing. However, in recent years, steels that have undergone low-sulfurization treatment or calcium treatment such as hydrogen-induced cracking steel have been put to practical use, and the progress of high-grade steel production technology and segregation of continuous cast slabs has made progress, so solidification segregation by the conventional sulfaprint test method The fact is that the part cannot be detected. A phosphorus print test method has been devised which can detect such a segregated portion of high-grade steel as easily as a sulfaprint test method.

For example, JP-A-60-105961, JP-A-61-30756, and JP-A-61-487 by the group of Funabashi (one of the inventors).
62, JP-A-61-51567, JP-A-62-43558, and JP-A-60-296120 (JP-A-62-150157). These methods include (1 ) A method in which a detection sheet containing a reagent that reacts with the phosphorus segregation portion is attached to the surface of the steel sample to detect the phosphorus segregation portion as a color change point, and (2) the surface of the steel sample to be detected has phosphorus segregation. After affixing a detection sheet containing a reagent that reacts with the parts, peeling it off to develop the color of the phosphorus occluded in the detection sheet using a color-forming reagent, (3) Further, (1), ( Before performing the operation 2), the test surface of the steel material is contacted with a metal corrosive reagent containing alcohol in advance to corrode it, and then the corrosive liquid is removed.

Thus, in the phosphorus printing method, a test paper impregnated with a reaction reagent is attached to the test surface of the steel material, the phosphorus segregation part is selectively corroded, and the phosphorus eluted from the test surface is presented on the test paper. The color tone of the segregation image can be expressed in, for example, silver (Silver method), red (Red method), blue (Blue method), or the like depending on the type of reaction reagent and coloring agent used. As the reaction reagent, a silver nitrate solution, a copper nitrate solution, etc. are used, and as the color reagent, a reagent containing molybdate ion is used.

<Problems to be Solved by the Invention> The detection paper, which is the base paper of the detection material used in the above-mentioned phosphorus segregation portion detection method, merely holds, for example, a reaction chemical solution sufficient to react with the phosphorus segregation portion. Liquid absorbency, flatness and flexibility that adheres well to the surface to be tested, size and chemical resistance that can withstand the reaction chemicals, and the detection paper is paper when the detection paper is peeled off after being adhered to the surface and then treated with the reaction chemicals. Characteristics such as surface peelability and wet strength that prevent peeling from the layer or gelatin layer, and change in color tone of the detection paper proportional to the concentration of the phosphorus segregated portion are required. However, a sufficiently satisfactory detection sheet having a wide range of these characteristics has not yet been obtained.

The present invention pays attention to this point, and satisfies the size, wet strength, liquid absorption, chemical resistance, adhesion, peelability, and color tone change required for the phosphorus segregation portion detection paper, and An object of the present invention is to provide a phosphorus segregation portion detection sheet that can be clearly detected.

<Means for Solving Problems> In the phosphorus segregation detection paper of the present invention, a paper having size and wet strength is provided with a layer containing gelatin and a hardening agent for gelatin, and the coating amount of the layer is gelatin. 3-5g / m in solid content
² and the content of the hardening agent in the layer is 2 to 8% by weight in terms of solid content relative to gelatin. The gelatin hardener is preferably a non-formalin organic compound, as described later.

That is, the phosphorus segregation detection paper of the present invention has, as its basic structure, a paper layer and a layer containing gelatin and a hardening agent for gelatin. First, the paper layer used in the present invention is a paper layer mainly composed of natural pulp.
The paper layer contains a sizing agent with excellent chemical resistance to the above-mentioned phosphorus segregation reaction reagent and coloring reagent, and a paper strength enhancer to increase the moisture resistance, and the paper layer is chemically resistant to the phosphorus segregation part detection reagent. Give the property of. Examples of natural pulp include wood pulp, bamboo pulp, cotton pulp, and known plant fibers used in general papermaking technology such as waste paper pulp, but natural pulp containing less impurities such as iron and copper and heavy metals. Use is preferred. Natural pulp is usually beaten mechanically in water using a beater or the like to obtain a pulp slurry. The beating degree of the natural pulp used in the present invention is 150 to 5
It is in the range of 00 ml, preferably in the range of 200 to 350 ml. As the sizing agent, there are sizing agents such as rosin size, higher fatty acid salt and alkyl ketene dimer.However, since the present invention requires sizing property and chemical resistance, higher fatty acid salt and alkyl ketene dimer may be used alone or in combination. To use. The amount of higher fatty acid salt added is 0.1 to 2.0 with respect to the pulp.
It is less than wt%, preferably 0.5 to 1.0 wt%.
If it is less than 0.1% by weight, the sizing property is weak and the chemical resistance is inferior, and if it is 2.0% by weight or more, the sizing property becomes too strong and the penetrability and liquid absorption of the reactive chemical liquid are inferior. Is reduced in strength and delamination occurs.

The amount of alkyl ketene dimer added is 0.05 based on the pulp.
Is less than 0.5% by weight, preferably 0.1 to 0.3% by weight. If it is less than 0.05% by weight, the size is weak and the chemical resistance is inferior.If it is 0.5% by weight or more, the sizing property becomes too strong and the penetrability and liquid absorption of the reactive chemical liquid are poor, and the strength between the paper layer and the gelatin layer decreases. This is because delamination occurs.

A water-soluble aluminum salt or polyamide polyamine epichlorohydrin is used as a fixing agent for fixing the sizing agent to the pulp fiber. Furthermore, a wet strength agent is used to impart moisture resistance strength. Wet strength agents include melamine resin and polyamide polyamine epichlorohydrin,
In the present invention, a substance containing formalin or a compound forming formalin for preventing storage stability and excessive gelatin hardenability of the phosphorus segregation detection sheet and preventing deterioration of liquid absorption is not preferable. Therefore, in the present invention, polyamide polyamine epichlorohydrin is added to the pulp in an amount of less than 0.2 to 0.8% by weight in order to impart moisture resistance strength, for example, wet tensile strength of 0.
It is preferable to impart a moisture resistance strength of 6 kg / 15 mm or more. 0.
If it is less than 2% by weight, sufficient wet strength cannot be obtained and the detection paper is cut when peeling it from the steel ingot surface.

If it is more than 0.8% by weight, the uniformity and texture of the paper will be deteriorated and the cost will be disadvantageous.

In the present invention, in the pulp slurry, in addition to the above additives, other dyes, fluorescent paints, fillers such as kaolin, clay,
Although fillers such as calcium carbonate and titanium oxide can be used, it is necessary to select an additive that does not change the color tone by reacting with the reagent solution for detecting the phosphorus segregation portion. Paper basis weight is 65
It is preferably g / m ² or more and less than 80 g / m ² . If it is less than 65 g / m ² ,
The waist is weak and wrinkles easily occur when it is applied to the steel ingot, resulting in poor adhesion. When it is 80 g / m ² or more, the paper becomes hard and the adhesion to the steel ingot surface becomes poor, and when the detection treatment paper is brought into close contact with the steel ingot surface and then the reaction treatment chemical solution permeates from the back surface, the permeability becomes slow.

A layer having gelatin and a gelatin hardening agent is provided on the above-mentioned formalin-free paper having size and wet strength. The gelatin used in the present invention is preferably acid-treated gelatin, and the coating amount needs to be 3 to 5 g / m ² . If the coating amount of gelatin is less than 3 g / m ² , the liquid absorption will be poor,
The reagent solution for detecting the phosphorus segregation portion cannot be held, and the sensitivity is lowered. On the other hand, if it exceeds 5 g / m ² , not only the economy is poor, but also the gelatin layer is swollen by the reagent solution for detecting the phosphorus segregation portion, and the sensitivity is also lowered. As the gelatin hardener, inorganic hardeners such as chromium alum and chromium sulfate and organic compound hardeners such as formalin and triazine can be used, but chromium alum, chromium sulfate and the like are for detecting phosphorus segregation part. It is desirable to use a non-formalin-based curing agent that is an organic compound-based curing agent that does not react with the reagent solution for detecting the phosphorus segregation portion and that has a small change in curing action over time because it may react with the reagent solution. For example, triazine-based, epoxy-based, ethyleneimine-based, vinylsulfonyl-based and the like. The content of the hardening agent in the layer is required to be 2 to 8% by weight in terms of solid content with respect to gelatin. Particularly preferably 4 to
8% by weight.

If the content is less than 2% by weight with respect to gelatin, the curing of gelatin is insufficient and peeling from the detection surface becomes poor. Also,
When the content is more than 8% by weight with respect to gelatin, the gelatin layer is too hard and the amount of liquid absorption is extremely low. As a result, the phosphorus segregation part detection reagent solution cannot be retained in the paper layer and the sensitivity is lowered. . Therefore, in order to maintain sufficient releasability, the content of the curing agent is 4 to 8% by weight in terms of solid content relative to gelatin.
Is preferred.

If desired, the gelatin layer of the present invention may contain a surfactant. As the surfactant, any of anionic, cationic, nonionic and amphoteric surfactants can be used, but the use of anionic surfactants is preferable. The drying temperature of the gelatin layer of the present invention is not particularly limited, but low temperature drying is preferable.

<Examples> Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Examples 1 to 9 A mixture of wood pulp consisting of 50% LBKP and 50% NBSP was beaten to 300 ml with Canadian freeness. Then, this slurry was diluted with water, and polyamide polyamine epichlorohydrin was added to the pulp with stirring with 0.2% of pulp.
After adding and mixing by weight%, the alkyl ketene dimer was added to pulp.
2% by weight was added and mixed to obtain a pulp slurry, and a base paper having a basis weight of 75 g / m ² and a thickness of 80 μ was produced. After humidity conditioning at 20 ° C 65% JIS P-813
Wet pull strength according to 5, and Sekicht sizing degree according to JIS P-8122. Wet tensile strength 0.6 kg / 15 mm, Steckit sizing degree
Got 30 seconds. An acid-treated gelatin aqueous solution containing a triazine-based curing agent was applied to this base paper as shown in Table 1, dried, and used as No. 3 to No. 11 test papers, and each sample was dipped in a reagent solution for detecting phosphorus segregation part. Then, the liquid absorbency, chemical resistance, and color tone change were examined, and by adhering to the surface of the steel sample to be inspected, the adhesion and peelability at the time of printing were examined.

Example 10 A mixture of wood pulp consisting of 50% LBKP and 50% NBSP was beaten to 300 ml with Canadian freeness. Then
After diluting this slurry with water, while stirring, the polyacid polyamine epichlorohydrin was added to the pulp.
After adding and mixing 0.2% by weight, 0.03% by weight of alkyl ketene dimer and pulp are added and mixed to form a pulp slurry.
A cardboard with g / m ² and a thickness of 80μ was produced. Humidified at 20 ℃ 65% JI
Wet tensile strength was measured by SP-8135 and Steckigt sizing degree was measured by JIS P-8122 to obtain a wet tensile strength of 0.6 kg / 15 mm and a Steckigt sizing degree of 10 seconds. An acid-treated gelatin aqueous solution containing a triazine-based curing agent was applied to this base paper as shown in Table 1, dried, and used as a test paper of Sample No. 12 to be immersed in a reagent solution for detecting phosphorus segregation and to be used as Examples 1 to 9. Similarly, the characteristics of the test paper were investigated.

Examples 11 and 12 As shown in Table 1, an acid-treated gelatin aqueous solution containing a formalin curing agent in a base paper made in the same manner as in Examples 1 to 9 was prepared.
After coating and drying, the test papers No. 13 and No. 14 were immersed in a reagent solution for detecting phosphorus segregation, and the characteristics of the test papers were examined in the same manner as in Examples 1-9.

Examples 13 and 14 Tests of Samples No. 15 and No. 16 were carried out by applying an acid-treated gelatin aqueous solution containing a chromium sulfate curing agent to a base paper made in the same manner as in Examples 1 to 9 and drying as shown in Table 1. As test paper, each test paper was immersed in a reagent solution for detecting phosphorus segregation, and the characteristics of the test paper were investigated in the same manner as in Examples 1-9.

Comparative Examples 1 and 2 No. 1 and No. 2 test papers were coated on base papers produced in the same manner as in Examples 1 to 9 with an aqueous solution of acid-treated gelatin containing a triazine-based curing agent and dried as shown in Table 1. Then, each sample was immersed in a reagent solution for detecting phosphorus segregation, and the characteristics of the test paper were investigated in the same manner as in Examples 1-9.

The evaluation in Examples 1 to 14 and Comparative Examples 1 and 2 is ◯ ... Acceptable, × ...
Table 2 shows the results of being unusable, Δ ... Intermediate.

As is apparent from the results shown in Table 2, No. 3 to No. 3 according to the present invention
It can be seen that the No. 16 test paper is excellent as the detection paper.

Also, it can be seen that Nos. 6 to 11 are particularly excellent among them.

<Effects of the Invention> Since the phosphorus segregation portion detection paper of the present invention is configured as described above, as is apparent from the examples and the like, it has particularly excellent properties in size property, wet strength property, liquid absorbing property and peeling property. As shown, the chemical resistance, the adhesiveness and the color tone stability are also good, and the intended function as the base material for the phosphorus segregation detection material can be fully achieved, which is extremely useful.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taiji Matsumura 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Nobuichi Harima Ya 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Third Annex Building (72) Inventor Seiji Asai 6-2-1, Shinjuku, Katsushika-ku, Tokyo Mitsubishi Paper Mills Nakagawa Mill

Claims (3)

[Claims] 1. A paper having size and wet strength is provided with a layer containing gelatin and a hardening agent for gelatin, and the coating amount of the layer is 3 to 5 g / m ² in terms of solid content of gelatin, and The content of the hardener in the layer is 2 to 8 in terms of solid content relative to gelatin.
A phosphor segregation part detection sheet, characterized in that the content is% by weight. 2. The phosphor segregation portion detection paper according to claim 1, wherein the gelatin hardening agent is a non-formalin organic compound. 3. The gelatin hardener is selected from the group consisting of triazine hardeners, epoxy hardeners, ethyleneimine hardeners and vinylsulfonyl hardeners.
The phosphorus segregation part detection paper according to item.