JP2006198677A - Composition of facing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition of facing material which is used for preventing occurrence of chemical reaction between a molten metal and a mold surface as well as defective seizure on a cast article through protection of the mold surface by applying a coating of the facing material on the mold surface to be contacted with the molten metal by means of coating or spraying (including sprinkling), has good releasability of the facing material from the cast article, and can manufacture the cast article with beautiful surface. <P>SOLUTION: The composition of the facing material includes fire-resistant particles, and contains 30-80 wt% of Al<SB>2</SB>O<SB>3</SB>and 1.5-7 wt% in total of Na<SB>2</SB>O and K<SB>2</SB>O in ash component in the facing material composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating composition.

  The casting mold agent is applied or sprayed (including bukkake) to the mold surface where the molten metal comes into contact, and the coating surface is applied to protect the mold surface, and the chemical reaction between the molten metal and the mold surface It is used to prevent the occurrence of casting defects in castings. Such a coating agent is generally composed of refractory particles, a binder, a sintering agent, a dispersion medium (solvent) and the like. Among these, the refractory particles are a coating base material, mainly for preventing casting seizure, and powders (aggregates) such as zircon, silica, magnesia, chromite, and graphite are used.

Patent Document 1 discloses that a coating agent containing a substance that expands crystal water by heating, such as vermiculite, obsidian, nacre, natural mica, etc., is applied to the core for pressure casting. Patent Document 2 discloses that pearlite and obsidian are heated and pulverized and used as a coating agent. As for the coating agent for the disappearance model, Patent Document 3 discloses that an ore having an endothermic peak temperature in a specific range by differential thermal analysis is used as the coating agent.
JP-A-3-226334 JP 52-18425 A JP 2003-290869 A

  However, further improvement is desired for improving casting quality, particularly for obtaining a smooth and high-quality casting surface.

  Also, in actual work sites, refractory particles are often selected empirically in consideration of the casting method and the refractory temperature, and the mold releasability after mold casting is not always good. For this reason, in order to remove the coating film remaining on the casting, a shot blasting process of usually 5 minutes to 1 hour is provided.

  The subject of this invention is providing the coating agent composition from which the casting film separation from a casting is good and a casting with a beautiful casting surface is obtained.

The present invention is a coating composition containing refractory particles, wherein the content of Al ₂ O ₃ in the ash content in the coating composition is 30 to 80% by weight, and Na ₂ O in the ash content The present invention relates to a coating agent composition having a total content of K ₂ O of 1.5 to 7% by weight.

  The present invention also relates to a mold obtained by applying the above-mentioned coating agent composition of the present invention to the mold surface, and a casting manufactured using the mold.

  ADVANTAGE OF THE INVENTION According to this invention, the coating agent composition from which the casting film separation from a casting is favorable and a casting with a beautiful cast surface is obtained is provided.

In the coating composition of the present invention, the content of Al ₂ O _{3 in} the ash is 30 to 80% by weight, and the total content of Na ₂ O and K ₂ O is 1.5 to 7% by weight. It is a certain coating composition.

In the present invention, the content of Al ₂ O _{3 in} the ash content of the coating composition and the total content of Na ₂ O and K ₂ O are within a specific range, thereby separating the coating film from the casting. And a particularly remarkable effect that a casting with a beautiful casting surface can be obtained. The reason why such a remarkable effect is manifested is not clear, but the content of Al ₂ O ₃ in the ash content in the coating composition of the present invention is 30 to 80% by weight (for example, Al ₂ A suitable amount of alumina, mullite, etc. containing a large amount of O ₃ component is blended), and the total content of Na ₂ O and K ₂ O is 1.5-7 wt% (for example, Na ₂ O In addition, an appropriate amount of obsidian, pearlite, pinestone, and the like containing a large amount of components of K ₂ O and the like can be used to maintain an atmosphere in which the molten metal is difficult to oxidize and create a strong coating film. ℃)), the coating film surface melts and the contact area between the coating film and the molten metal decreases, so that the casting film can be separated from the casting and the casting surface is beautiful. It is guessed.

The content of Al ₂ O ₃ in the ash content and the total content of Na ₂ O and K ₂ O in the coating composition of the present invention are measured by the following method. That is, ash content is extracted from the coating composition according to JIS-M8812 (1993) “Method for quantifying ash content”, and the components in the ash content are made into solutions according to JIS-R2212 (1991) “chemical analysis method for refractory bricks and mortar”. It is measured by analyzing the components in the solution with a sequential type high frequency plasma emission analyzer “ICPS-1000 IV”.

  Examples of components that are derived from ash in the coating composition of the present invention include refractory particles and sintering agents such as bentonite.

The content of Al ₂ O ₃ in the ash in the coating composition of the present invention is 30 to 80% by weight. From the viewpoint of forming a strong coating film and obtaining a casting with a beautiful casting surface, it is 30% by weight or more, preferably 32% by weight or more, and more preferably 35% by weight or more. From the viewpoint of good separation of the coating film, it is 80% by weight or less, preferably 75% by weight or less, more preferably 70% by weight or less. From the above viewpoint, it is preferably 30 to 70% by weight, and more preferably 30 to 60% by weight.

The total content of Na ₂ O and K ₂ O in the ash in the coating composition of the present invention is 1.5 to 7% by weight. From the viewpoint of promptly melting the surface of the coating film upon contact with the molten metal, the amount is 1.5% by weight or more, preferably 1.6% by weight or more, and more preferably 1.7% by weight or more. From the viewpoint of imparting sufficient heat resistance to the coating film, it is 7% by weight or less, preferably 6% by weight or less, and more preferably 5% by weight or less. From the above viewpoint, it is preferably 1.6 to 6% by weight, more preferably 1.7 to 5% by weight. The total of Na ₂ O and K ₂ O may be Na ₂ O alone or K ₂ O alone. When both Na ₂ O and K ₂ O are contained, Na ₂ O / K ₂ O (weight ratio) is preferably 1 / 3-3 / 1, 1/2 to 2/1 is more preferred.

Such a ratio can be achieved by combining refractory particles of known composition. For example, focusing on Na ₂ O and K ₂ O, obsidian (SiO ₂ : 74%, Al ₂ O ₃ : 13%, Fe ₂ O ₃ : 1.8%, Na ₂ O: 3.8%, K ₂ O: 3.9%), nacre (SiO ₂ : 73%, Al ₂ O ₃ : 12%, Fe ₂ O ₃ : 1.3%, Na ₂ O: 3.0%, K ₂ O: 5 .3), pine sebumite (SiO ₂ : 70%, Al ₂ O ₃ : 12%, Fe ₂ O ₃ : 1.5%, Na ₂ O: 3.0%, K ₂ O: 3.6%) Anorthite (SiO ₂ : 65%, Al ₂ O ₃ : 18%, K ₂ O: 17%), Anorthite (SiO ₂ : 69%, Al ₂ O ₃ : 19%, Na ₂ O: 12%) , Leucite (SiO ₂ : 55%, Al ₂ O ₃ : 23%, K ₂ O: 22%), meteorite ((Na, K) AlSiO ₄ ) and the like are preferably blended as appropriate. In addition, these% are weight%. Among these, it is preferable to contain at least one kind of refractory particles selected from obsidian, pearlite and pine sebite, and it is more preferable to contain obsidian.

On the other hand, if attention is focused on Al ₂ O ₃ , alumina (Al ₂ O ₃ : 100%), mullite (SiO ₂ : 28%, Al ₂ O ₃ : 72%), shaft bank 50% (SiO ₂ : 38%) Al ₂ O ₃ : 56%, Fe ₂ O ₃ : 1.7%, TiO ₂ : 2.6%), shaft bangs 85% (SiO ₂ : 8%, Al ₂ O ₃ : 85%, Fe ₂ O ₃ : 2.1%, TiO ₂ : 3.3%), diaspore (Al ₂ O ₃ : 85%, H ₂ O: 15%), wax (SiO ₂ : 67%, Al ₂ O ₃ : 28%) , H ₂ O: 5%), spinel (MgO: 28%, Al ₂ O ₃ : 72%), kaolin (SiO ₂ : 46%, Al ₂ O ₃ : 40%, H ₂ O: 14%), sillimanite _{(SiO 2: 37%, Al} 2 O 3: 63%), andalusite _{(SiO 2: 37%, Al} 2 O 3: 63%), kyanite Ito _{(SiO 2: 37%, Al} 2 O 3: 63%), gibbsite _{(SiO 2: 35%, Al} 2 O 3: 65%), black sand stone _{(SiO 2: 46%, Al} 2 O 3: 38% _{, Fe 2 O 3: 0.3%} , TiO2: 0.4%, CaO: 0.3%, MgO: 0.1%), Dekkaito _{(SiO 2: 43~47%, Al} 2 O 3: 39~ 41%), anorthite (SiO ₂ : 43%, Al ₂ O ₃ : 37%, CaO: 20%), one obtained by baking bauxite, and the like are preferably blended as appropriate. In addition, these% are weight%. Among these, it is preferable to contain refractory particles having 45% by weight or more of Al ₂ O ₃ , more preferably alumina, mullite, and shaft bank, and particularly preferably mullite.

Therefore, the present invention contains both the refractory particles (a) having 45 wt% or more of Al ₂ O ₃ and at least one refractory particles (b) selected from obsidian, nacre and pine sebumite. preferable. As an example of a combination of refractory particles satisfying the composition of the present invention, a mixture of obsidian: mullite = 1: 1 (weight ratio) (content of Al ₂ O ₃ in the mixture: 39.7%, Na ₂ O and (Total content with K ₂ O: 3.6%), obsidian: alumina = 1: 1 (weight ratio) mixture (Al ₂ O ₃ content in the mixture: 53.0%, Na ₂ O And K ₂ O (total content: 3.3%), obsidian: shaft bangs 50% = 1: 1 (weight ratio) mixture (Al ₂ O ₃ content in the mixture: 34.7%) , The total content of Na ₂ O and K ₂ O: 3.9%), obsidian: shaft bangs 85% = 1: 1 (weight ratio) mixture (content of Al ₂ O ₃ in the mixture) : 47.5%, the total content of the same Na ₂ O and K ₂ O: 3.4%), obsidian: shaft van ass 5% = 1: 3 mixture (weight ratio) (the content of Al ₂ O ₃ in the mixture: 65.6%, the total content of the same Na ₂ O and K ₂ O: 1.8%), Obsidian: Mullite = 1: 3 (weight ratio) mixture (content of Al ₂ O ₃ in the mixture: 55.9%, total content of Na ₂ O and K ₂ O: 1.9%) Etc.

The weight ratio of the refractory particles (a) having 45% by weight or more of Al ₂ O ₃ and at least one refractory particles (b) selected from obsidian, nacre and pine sebum is a viewpoint excellent in separating the coating film From the viewpoint of excellent cast surface, (a) / (b) = 1/1 to 9/1 is preferable, and (a) / (b) = 1/1 to 5/1 is more preferable.

In the coating composition of the present invention, those other than those described above can be used as the refractory particles, but the content of SiO ₂ in the ash content in the coating composition is such that the coating film is separated from the casting. From the viewpoint of easy handling, it is preferably 65% by weight or less, more preferably 60% by weight or less, and particularly preferably 45% by weight or less.

  The particle diameter (median diameter) of the refractory particles used in the present invention is preferably 100 μm or less, more preferably 70 μm or less, from the viewpoint of the roughness of the coating film after coating application, and from the viewpoint of economy, it is preferably set to 0. 5 micrometers or more are preferable and 1 micrometer is still more preferable. From the above viewpoint, the particle diameter of the refractory particles is preferably 0.5 to 100 μm, and more preferably 1 to 70 μm.

  The content of the refractory particles in the coating agent composition of the present invention is preferably 20 to 70% by weight, more preferably 20 to 50% by weight from the viewpoint of achieving the object of the present invention.

  Under severe casting conditions where the molten metal pressure and molten metal flow are high, it is preferable to contain both obsidian and mullite in the refractory particles, and the coating film from the casting is good and the casting surface is beautiful. From the viewpoint of obtaining a casting and a viewpoint of excellent seizure resistance, the ratio of obsidian in the refractory particles (weight ratio of obsidian / refractory particles) is preferably 0.1 / 1 to 0.4 / 1, and more The ratio is preferably 0.2 / 1 to 0.3 / 1, and the ratio of mullite in the refractory particles (weight ratio of mullite / refractory particles) is preferably 0.6 / 1 to 0.9 / 1. Yes, more preferably 0.7 / 1 to 0.8 / 1.

  In addition, the weight ratio of mullite to obsidian (mullite / obsidian) is 1 / 1-9 / from the viewpoint that the cast film is well separated from the casting, a casting with a beautiful casting surface is obtained, and the seizure resistance is excellent. 1 is preferable, and 2/1 to 5/1 is more preferable.

  The dispersion medium used in the coating agent composition of the present invention may be either aqueous or oily, but is preferably oily from the viewpoint of permeability. In the case of an oil-based coating composition, lower alcohols such as methanol, ethanol and isopropyl alcohol, aromatic solvents such as xylene and toluene, and hydrocarbon solvents such as mineral spirits can be used. Preferred are lower alcohols, and methanol is particularly preferred. Aromatic solvents and hydrocarbon solvents may be used as auxiliary solvents. In the case of an aqueous coating composition, water is the main dispersion medium. In the case of oily, the addition amount is preferably 20 to 120 parts by weight, more preferably 70 to 110 parts by weight, based on 100 parts by weight of the total refractory particles if it is a lower alcohol. Moreover, in the case of aqueous | water-based, 20-150 weight part is preferable with respect to a total of 100 weight part of refractory particles, and 70-130 weight part is more preferable.

  In addition, a binder as commonly used can be blended in the coating composition of the present invention. For example, there are organic binders such as phenol, rosin and petroleum resin that can form a strong coating film at room temperature, and inorganic binders such as sodium silicate and aluminum phosphate. These may be used in combination depending on conditions. The addition amount of the binder is preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the total refractory particles.

  Examples of the sintering agent include bentonites such as sodium bentonite and calcium bentonite, clays such as kibushi clay, ethyl silicate, and colloidal silica. The addition amount of the sintering agent is preferably 3 to 10 parts by weight with respect to 100 parts by weight of the total refractory particles.

  In addition, surfactants, dispersants, thixotropic agents, and the like are listed as components that can be blended in the coating composition of the present invention.

  Although the coating agent composition of the present invention can be used in the same manner as a general coating agent, it can be suitably used particularly as a sanding coating composition.

  The method of applying the coating composition of the present invention to the mold may be any of the conventionally known methods such as flow coating (bukkake method), dipping (dipping method), brush coating, spray coating, etc. A flow coating method is preferred. Further, as the foundry sand used for the casting mold, new sand or reclaimed sand such as zircon sand, chromite sand, synthetic mullite sand, etc. is used in addition to quartz sand mainly composed of quartz. Casting sand can also be used without the addition of a binder, in which case the filling properties are good, but if mold strength is required, a binder is added and cured with a curing agent. Is preferred.

  As a casting manufactured using the mold of the present invention, a casting having a beautiful casting surface is obtained, and therefore, it is suitable for a casting that requires a complicated structure and a beautiful casting surface. Specific examples of castings include members, parts, and the like used for hydraulic valves, motors, molds, engine frames, machine tools, building members, and the like of construction machines.

Examples 1-4 and Comparative Examples 1-6
After adding and kneading 0.2 parts by weight of an organic sulfonic acid curing agent (TK-3 manufactured by Kao Quaker Co., Ltd.) to 100 parts by weight of Fremantle quartz sand (No. 5), furan resin (manufactured by Kao Quaker Co., Ltd.) 340B) was mixed with 0.8 part by weight. Using this, a rectangular parallelepiped mold having a height of 150 mm, a width of 120 mm, and a depth of 100 mm was produced.

  After standing for 24 hours, the coating composition of the following composition containing the refractory particles shown in Table 1 was applied, and after the solvent was sufficiently dried, the molten FC-250 was poured into the mold at 1400 ° C. After 24 hours, the furan mold was released and the coating film was peeled off from the casting. Thereafter, shot blasting was performed for 2 minutes, and the cast skin was observed. Further, peeling of the coating film from the casting was evaluated by the following method. These results are shown in Table 1. The composition of the coating agent composition is 100 parts by weight of refractory particles, 100 parts by weight of water, 5 parts by weight of sodium bentonite, 1 part by weight of dextrin, and 0.1 parts by weight of preservative.

<Peeling of casting film from casting>
Regarding peeling of the coating film, first, visually, 100% was peeled off, and 0% was not peeled at all. Otherwise, the degree of peeling of the coating film was calculated by the following formula.
Peeling of coating film (%) = w / W × 100 (%)
w: Weight of coating film peeled off (g)
W: A value obtained by cutting out a part of the peeled coating film, measuring the area and weight, and converting to the weight of the coating film for the entire surface area of the casting (g)

  In Comparative Examples 2 and 6, the unevenness of the casting surface was remarkable, and in Comparative Example 3, a white film (chemically deposited) of the coating film remained on the casting surface. On the other hand, in Examples 1-4, there was little peeling of a coating film, the level which can be satisfied practically was achieved, and the state of the cast skin was also favorable.

Examples 5-7
For 100 parts by weight of recycled casting sand (equivalent to No. 5 sand), 0.28 parts by weight of organic sulfonic acid curing agent (TK-3 manufactured by Kao Quaker Co., Ltd.) and 340B of furan resin (Kao Quaker Co., Ltd.) Using this mixture, a cylindrical mold core having a general shape diameter of 482 mm and a height of 524 mm was produced.

  After standing for 2 hours, the coating composition of the following composition containing the refractory particles shown in Table 2 was dipped and applied, and after the solvent was sufficiently dried, a cylindrical shape with a rough diameter of 522 mm and a height of 686 mm It was installed in the main mold having the voids. A molten roll of FCD-450 was poured into this mold at 1410 ° C. to produce a hollow roll casting. This casting was subjected to a shot blasting treatment with a hanger shot for 30 minutes, and the occurrence of seizure and the appearance of the casting surface were observed. These results are shown in Table 2. When the peeling of the coating film from the casting was observed with the naked eye, it was confirmed that the coating film was peeled off almost for each of Examples 5 to 7 and good results were obtained. The composition of the coating agent composition is 100 parts by weight of refractory particles, 100 parts by weight of water, 5 parts by weight of sodium bentonite, 1 part by weight of dextrin, and 0.1 parts by weight of preservative.

Claims (8)

A coating composition containing refractory particles, wherein the content of Al ₂ O ₃ in the ash in the coating composition is 30 to 80% by weight, and Na ₂ O and K ₂ O in the ash A coating agent composition having a total content of 1.5 to 7% by weight. The coating composition according to claim 1, comprising refractory particles (a) having 45 wt% or more of Al ₂ O ₃ and at least one refractory particles (b) selected from obsidian, nacre and pine sebite. object. The coating composition according to claim 1 or 2, wherein the weight ratio of the refractory particles (a) to the refractory particles (b) is (a) / (b) = 1/1 to 9/1. The coating composition according to any one of claims 1 to 3, wherein the refractory particles (a) are mullite. The coating composition according to any one of claims 1 to 4, wherein the refractory particles (b) are obsidian. The coating composition according to any one of claims 1 to 5, which is used for sand molds. A mold formed by applying the coating agent composition according to any one of claims 1 to 6 to a mold surface. A casting produced using the mold according to claim 7.