JP6914693B2 - Wet magnetic particle flaw detection test fluorescent magnetic powder and wet magnetic particle flaw detection test method using the fluorescent magnetic powder - Google Patents

Description

The present invention relates to a fluorescent magnetic powder used in a fluorescent magnetic powder liquid in a wet magnetic particle inspection. Specifically, in the fluorescent magnetic powder, the fluorescent pigment on the surface of the magnetic powder is difficult to peel off and fall off. Therefore, even if fine particles are formed by the pulverization method, the fluorescent pigment remains on the surface of the magnetic powder in a high proportion. The fluorescent magnetic powder liquid using the above can form a defect indication pattern with high brightness, and since there are few fluorescent pigments that peel off and fall off, there is little so-called background phenomenon in which fluorescence is emitted except for the defective portion, and the opening is performed with high accuracy. The present invention relates to a fluorescent magnetic powder capable of producing a fluorescent magnetic powder liquid capable of detecting a defective portion.

As is well known, the wet magnetic particle inspection test method is standardized to JIS-Z-2320, and this test method is used for magnetized inspection objects such as steel parts such as shafts, magnetic materials and billets. Commercially available wet magnetic particle flaw detection test magnetic powder for steel materials, magnetic materials, etc. (Lumo using synthetic resin binders such as cellulose acetate synthetic resin and vinyl butyral synthetic resin for magnetic conductive particles such as triiron tetroxide particles and pure iron particles. Gen Yellow 50790: Product name: BASF or Festa A: Product name: Swada, etc. Average particle size 3 to 70 μm to which fluorescent pigments are attached: Volume-based distribution display-Hereafter, the same-and true specific gravity 2 5 g / cm ³ powder; hereinafter referred to as "magnetic powder" or "magnetic particles") is dispersed in water and brought into contact with a magnetic powder solution, which is present on the surface of the inspection object (at or near the surface of the inspection object). A test method (hereinafter, this test method is referred to as "wet") in which magnetic powder dispersed in a magnetic powder liquid is collected in a fine crack or pinhole) to form a defect indication pattern, and a surface defect portion is detected by this defect indication pattern. Magnetic particle inspection test ").

There are two methods for producing magnetic powder, one called "crushing method" and the other called "spraying method" among those skilled in the art. Among them, the crushing method was proposed earliest and has been put into practical use to date. Is the way to be.

In the pulverization method, an organic solvent-soluble synthetic resin is used as a binder, a fluorescent pigment is dispersed and placed in a solution prepared by dissolving this in a volatile organic solvent, and magnetic powder is mixed and kneaded to form a paste. This is a method in which the paste-like substance is dried into a lump, then pulverized into fine particles using a crusher such as a ball mill, and classified by a sieve or the like to obtain magnetic powder having a required particle size.

However, the pulverization method has a problem that the fluorescent pigment adhering to the magnetic powder is peeled off or dropped off when pulverized into fine particles using a pulverizer.

When a fluorescent magnetic powder solution in which fluorescent magnetic powder is dispersed or dropped from the surface of the magnetic powder is used for a magnetic particle flaw detection test, the brightness of the indicated pattern at the opening defect is reduced because the amount of fluorescent pigment covering the surface of the magnetic powder is small. The peeled / removed fluorescent pigment adheres to the surface of the object to be inspected other than the opening defect and emits fluorescence, which makes it difficult to see the indicated pattern of the opening defect, which is a so-called background phenomenon, and the detection accuracy of the opening defect is improved. descend.

Although peeling / falling off of the fluorescent pigment can be suppressed by increasing the amount of the binder resin, if the amount of the binder resin is increased, it becomes difficult to obtain fine fluorescent magnetic powder particles by the pulverization method.

Since the detection accuracy of the opening defect portion is improved when the fluorescent magnetic powder is fine particles, there is a problem that the detection accuracy is lowered if the fine fluorescent magnetic powder particles cannot be obtained.

Therefore, the fluorescent pigment on the surface of the magnetic powder does not easily peel off or fall off without increasing the amount of the binder resin, and even if fine fluorescent magnetic powder particles are formed by the pulverization method, the fluorescent pigment remains on the surface of the magnetic powder in a high proportion. It is desired to develop a fluorescent magnetic powder capable of producing a fluorescent magnetic powder liquid having less background phenomenon and high detection accuracy.

JP-A-2002-39999

Since the invention described in Patent Document 1 does not employ a pulverization step, peeling / detachment of the fluorescent pigment can be suppressed.

However, in the invention described in Patent Document 1, it is necessary to use γ-iron monoxide particle powder, and there is a problem that the fluorescent pigment is easily peeled off or dropped off with other magnetic conductive particles.

The present inventors have set the technical problem to solve the above-mentioned problems, and as a result of repeating many trials and trials and experiments, the particle surface of the magnetic particle powder is made of a fluorescent pigment via a binder resin. If the coated fluorescent magnetic particle for the wet magnetic particle inspection test and the binder resin is an acrylic emulsion resin having a glass transition point (Tg) of −3 to −9 ° C., the fluorescent magnetic particle for the wet magnetic particle inspection test. Since the fluorescent pigment adheres firmly to the surface of the magnetic powder without increasing the amount of the binder resin, even if fine fluorescent magnetic powder particles are formed by the pulverization method, there are few fluorescent pigments that peel off and fall off, and the proportion is high on the surface of the magnetic powder. Since the fluorescent magnetic particle remains as the fluorescent magnetic powder, the fluorescent magnetic powder liquid in which the fluorescent magnetic powder is dispersed has less background phenomenon, a defect indication pattern with high brightness can be obtained, and an opening defect portion can be detected with high accuracy. The above-mentioned technical problem was achieved by obtaining the remarkable knowledge that it becomes a fluorescent magnetic particle liquid.

The technical problem can be solved by the present invention as follows.

The present invention is a wet magnetic particle flaw detection test fluorescent magnetic powder in which the particle surface of the magnetic conductive particle powder is coated with a fluorescent pigment via a binder resin, and the binder resin has a glass transition point (Tg) of −3 to 3. Wet magnetic particle flaw detection test fluorescent magnetic powder that is an acrylic emulsion resin at -9 ° C.

Further, the present invention is a wet magnetic particle flaw detection test fluorescent magnetic powder in which the acrylic emulsion resin is an acrylic emulsion resin crosslinked with a cross-linking agent.

Further, the present invention is a fluorescent magnetic particle for a wet magnetic particle inspection, wherein the cross-linking agent is one or more cross-linking agents selected from an oxazoline group-containing polymer, a cresol novolac type epoxy resin, and adipic acid dihydrazide.

Further, the present invention is a fluorescent magnetic powder for a wet magnetic particle flaw detection test in which the ratio of the cross-linking agent to the acrylic emulsion resin is 1 to 11% by weight.

The present invention is a wet magnetic particle flaw detection test fluorescent magnetic powder containing 35 to 65% by weight of magnetic particle powder, 30 to 61% by weight of fluorescent pigment, and 0.09 to 3.5% by weight of binder resin.

Further, the present invention is a fluorescent magnetic particle for a wet magnetic particle inspection test having an average particle size of 2.0 to 5.5 μm.

Further, the present invention is a wet magnetic particle flaw detection test method characterized in that flaw detection is performed using the fluorescent magnetic particle for the wet magnetic particle flaw detection test described above.

Since the fluorescent magnetic powder according to the present invention is a fluorescent magnetic powder coated with a fluorescent pigment via an acrylic emulsion resin having a glass transition point of -3 to -9 ° C, the fluorescent pigment is on the surface of the magnetic powder without increasing the amount of the binder resin. Even if fine particles are formed by the pulverization method because they adhere firmly to the resin, there are few fluorescent pigments that peel off and fall off, and the fluorescent pigments remain on the surface of the magnetically conductive particles in a high proportion, so that the fluorescent magnetic powder is dispersed. Since the fluorescent magnetic powder liquid is less background phenomenon and a defect indication pattern with high brightness can be obtained, it is possible to produce a fluorescent magnetic powder liquid that can accurately detect even a minute opening defect portion. can.

In particular, if the binder resin is made into an acrylic emulsion resin at -3 to -9 ° C. which is crosslinked with a cross-linking agent, the fluorescent pigment can be further firmly adhered to the surface of the magnetic powder, and the peeling / falling off of the fluorescent pigment can be suppressed. Can be done.

(Magnetic particles)
The magnetic conductive particles in the present invention are not particularly limited.
Examples of the magnetic conductive particles include reduced iron powder, electrolytic iron powder, γ ferric monoxide powder, and triiron trioxide powder.

The average particle size of the magnetic conductive particles is preferably 0.5 to 5.0 μm, more preferably 1.0 to 3.0 μm.
This is because if the average particle size is out of the range, an accurate defect indication pattern may not be obtained.

(Fluorescent pigment)
The average particle size of the fluorescent pigment attached to the magnetic conductive particles is preferably 1.0 to 5.0 μm, more preferably 2.0 to 4.0 μm.
This is because the brightness of the defect indicating pattern becomes high.

Examples of fluorescent pigments include Pigment Yellow 101 (trade name: manufactured by Colortex) and Festa A (manufactured by Swada).

(Binder resin)
The binder resin according to the present invention is an acrylic emulsion resin having a glass transition point (Tg) of −3 to −9 ° C.

Examples of acrylic emulsion resins with Tg of -3 to -9 ° C are Cybinol® YC-1530 (Tg: -3 ° C), X-215-678E (Tg: -3 ° C), CA-333 (Tg). : -9 ° C) (manufactured by Saiden Chemical Co., Ltd.).

In the present invention, a cross-linking agent of an acrylic emulsion resin can be added in order to more firmly attach the fluorescent pigment to the surface of the magnetic conductive particles.

The cross-linking agent to be added is not particularly limited, but an oxazoline group-containing polymer, a cresol novolac type epoxy resin, and adipic acid dihydrazide can be preferably used.

Epocross (registered trademark) WS-300, WS-700 (manufactured by Nippon Catalyst Co., Ltd.) as oxazoline group-containing polymers, and Denacol (registered trademark) EM-160 (manufactured by Nagase ChemteX Corporation) as cresol novolac type epoxy resin. ).

The cross-linking agent is preferably 1 to 11% by weight, more preferably 3 to 7% by weight, based on the acrylic emulsion resin.

This is because if the proportion of the cross-linking agent is out of the above range, the fluorescent pigment is likely to peel off or fall off from the surface of the magnetic powder.

(Manufacturing method)
The fluorescent magnetic powder according to the present invention is prepared by adding magnetic particles and a fluorescent pigment to water and stirring the mixture, adding a binder resin and further stirring the mixture, drying the mixture at 130 to 140 ° C. for 3 to 4 hours, and then ball milling. It can be produced by crushing it to a desired average particle size with a crusher such as.

The content of the conductive magnetic particles in the fluorescent magnetic powder in the present invention is 35 to 65% by weight, more preferably 50 to 65% by weight.
The preferred content of the fluorescent pigment is 30-61% by weight, more preferably 35-50% by weight.
The preferred content of the binder resin is 0.09 to 3.5% by weight, more preferably 0.5 to 2.9% by weight, and even more preferably 0.5 to 2.0% by weight.

This is because if the magnetic conductive particles, the fluorescent pigment and the binder resin are out of the range, the fluorescent pigment is likely to be peeled off or fall off.

The average particle size of the fluorescent magnetic powder is preferably 2.0 to 5.5 μm.
This is because an accurate defect indication pattern can be obtained.

(Magnetic particle inspection test method)
An embodiment of a magnetic particle flaw detection test method using the fluorescent magnetic powder according to the present invention is shown.

A fluorescent magnetic powder solution can be prepared by dispersing the fluorescent magnetic powder in tap water. Further, in order to enhance the dispersibility of the fluorescent magnetic powder, a commercially available magnetic particle dispersant for magnetic particle inspection may be added.

The object to be inspected is magnetized by the axial energization method according to a conventional method, then a fluorescent magnetic powder liquid is sprayed, and an ultraviolet lamp is irradiated in a dark place to observe a defect indication pattern. The size and the like can be detected.

The fluorescent magnetic powder liquid using the fluorescent magnetic powder according to the present invention can be suitably used for detecting an opening defect portion having a depth of 10 to 100 μm.

The present invention will be described in more detail with reference to Examples and Comparative Examples.

Fluorescent pigments and magnetic conductive particles were added and dispersed in water as described in "Composition" of Tables 2 to 7.
Various binder resins are added to water in which fluorescent pigments and magnetic conductive particles are dispersed, stirred for 3 minutes, dried at 130 ° C. for 3 to 4 hours, and then crushed with a crusher (SAMPLE MILL / AS ONE Corporation) for 1 minute. The fluorescent magnetic powders of Examples and Comparative Examples were obtained.

Γ-500 (γ-Fe ₂ O ₃ particle powder / manufactured by Titan Kogyo Co., Ltd.) was used as the magnetic conductive particles, and Pigment Yellow 101 (manufactured by Colortex Co., Ltd.) was used as the fluorescent pigment.
In addition, water containing anion-modified polyvinyl alcohol (Goselan (registered trademark) L3266, manufactured by Nippon Synthetic Chemistry Co., Ltd.) was used as needed.

Table 1 shows the acrylic emulsion resins used in Examples and Comparative Examples.

As oxazoline group-containing polymer cross-linking agents, Epocross WS-300 (polymer main chain: acrylic, Tg: 90, molecular weight: Mn = 4 × 10 ⁴ , Mw = 12 × 10 ⁴ , non-volatile component 10 wt%), Epocross WS-700 (Polymer main chain: acrylic, Tg: 50, molecular weight: Mn = 2 × 10 ⁴ , Mw = 4 × 10 ⁴ , non-volatile component 25 wt%) was used.

A 5 wt% solution of Denacol EM-160 was used as the cresol novolac type epoxy resin.

In addition, a 10 wt% solution of adipic acid dihydrazide (ADH) manufactured by Nihon Kasei Corporation was used.

(Average particle size)
The particle size was measured with a particle size distribution meter (laser diffraction type particle size distribution measuring device SALD-2300, manufactured by Shimadzu Corporation), and a 50% average particle size was calculated.

(Fluorescence coefficient)
Weigh 2 g samples of the prepared fluorescent magnetic powders of Examples and Comparative Examples in a 500 ml beaker, add 500 ml of tap water containing 2 ml of Eco-Magna (registered trademark) dispersant EC-4 (manufactured by MARKTEC Corporation), and add 500 ml of fluorescent magnetic powder. After dispersing, the magnet is brought closer and separated from the solvent, and the process of discarding the separated solvent (hereinafter referred to as "magnetic washing") is repeated three times, and then the fluorescent magnetic powder is transferred to the chalet and charged at 130 ° C. for about 15 minutes. It was dried in a furnace.

The fluorescence coefficients of the fluorescent magnetic powder before and after magnetic washing were measured using a fluorometer (Luminance meter BM-9, manufactured by Topcon).
The "-" display in the table indicates that the measurement could not be performed.

(Initial dispersity)
Weigh 0.15 g of the fluorescent magnetic powder of Examples and Comparative Examples into a 500 ml disc cup, add 1.5 g of the eco-magna dispersant EC-4, disperse and observe. Those with a large number were evaluated as x, and those showing the dispersibility between ○ and × were evaluated as Δ on a three-point scale.

The results are shown in Tables 2-7.
In the table, "PY101" represents the fluorescent pigment Pigment Yellow 101, and the "before magnetic washing" and "after magnetic washing" columns represent the fluorescence coefficients of the respective fluorescent magnetic powders.
The "residual rate (%)" indicates what percentage of the fluorescence coefficient after magnetic washing is the fluorescence coefficient before magnetic washing. The numerical value in parentheses of the cross-linking agent represents the ratio (wt%) of the cross-linking agent to the acrylic emulsion resin.
The ratio (wt%) represents the ratio of each component in the solid content.

As shown in Tables 2 to 7, in the fluorescent magnetic powder according to the present invention, even if a fine fluorescent magnetic powder is produced by a pulverization method, the fluorescent pigment is less likely to peel off or fall off, and the fluorescent pigment firmly adheres to the surface of the magnetic conductive particles, and the fluorescent pigment is formed. It proved to remain at a high rate.

The fluorescent magnetic powder according to the present invention is a fluorescent magnetic powder in which even if fine fluorescent magnetic powder is formed by a pulverization method, the fluorescent pigment is less likely to peel off or fall off, and the fluorescent pigment is firmly adhered to the surface of the magnetic powder. If the flaw detection test is performed by the wet magnetic particle flaw detection test method using a fluorescent magnetic powder liquid using magnetic powder, the background phenomenon due to the fluorescent pigment that has peeled off or dropped off is small, and the brightness of the defect indication pattern is high, so that the opening defect portion can be found. It can be detected with high accuracy.
Therefore, it can be said that the industrial applicability of the present invention is high.

Claims (7)

A fluorescent magnetic powder for a wet magnetic particle inspection test in which the particle surface of the magnetic particle powder is coated with a fluorescent pigment via a binder resin, and the binder resin has a glass transition point (Tg) of −3 to −9 ° C. Wet magnetic particle flaw detection test fluorescent magnetic powder that is an acrylic emulsion resin. The fluorescent magnetic powder for a wet magnetic particle flaw detection test according to claim 1, wherein the acrylic emulsion resin is an acrylic emulsion resin crosslinked with a cross-linking agent. The fluorescent magnetic particle for a wet magnetic particle inspection test according to claim 2, wherein the cross-linking agent is one or more cross-linking agents selected from an oxazoline group-containing polymer, a cresol novolac type epoxy resin, and adipic acid dihydrazide. The fluorescent magnetic particle for a wet magnetic particle inspection test according to claim 2 or 3, wherein the ratio of the cross-linking agent to the acrylic emulsion resin is 1 to 11% by weight. The fluorescent magnetic powder for a wet magnetic particle inspection test according to any one of claims 1 to 4, wherein the magnetic particle powder is 35 to 65% by weight, the fluorescent pigment is 30 to 61% by weight, and the binder resin is 0.09 to 3.5% by weight. The fluorescent magnetic particle for a wet magnetic particle flaw detection test according to any one of claims 1 to 5, wherein the fluorescent magnetic powder has an average particle size of 2.0 to 5.5 μm. A wet magnetic particle flaw detection test method, characterized in that flaw detection is performed using the fluorescent magnetic particle for the wet magnetic particle flaw detection test according to any one of claims 1 to 6.