JPS60108478A - Coating composition for protecting sensor - Google Patents

Abstract

PURPOSE:To provide the titled composition containing boron nitride, a low-melting frit, an inorganic pigment, a silicone resin, and its solvent at specific ratios, and capable of giving a coating film having excellent corrosion resistance and mold releasability when applied to a substrate and baked. CONSTITUTION:The objective composition contains (A) 20-60pts.(wt.) of powdery composition composed of (i) 30-80(wt)% boron nitride, (ii) 1-18% low- melting frit (e.g. frit glass) and (iii) the remaining part of inorganic pigment (e.g. BaSO4) and (B) 80-40pts. of a liquid composition composed of (iv) 20- 60% silicone resin and (v) the remaining part of an organic solvent of said silicone resin. (e.g. toluene).

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to a coating material for measuring objects such as liquid level gauges and thermometers used for measuring the liquid level and temperature of molten metal or molten alloy.

Conventional measuring body coating materials include solutions in which powders such as Vi boron nitride and titanium oxide (hereinafter referred to as KA) are dispersed in water, oil, solvents, etc., and measuring body coating materials in which binders are added to these solutions. However, this coating material has the disadvantage that the coating has a long coating life and must be coated every 2 to 3 days due to its low erodibility to molten metal.The present invention is a measuring body coating material that solves all of the above-mentioned disadvantages. The product we provide contains 30 to 80% monomer monoxide (hereinafter referred to as BN).
, 20-60 parts by weight of a powder composition containing 1-18% by weight of a low-melting point herbal medicine, the balance being an inorganic pigment, and 20-6% by weight of a silicone resin.
The liquid composition is characterized in that it contains 80 to 40 weight percent of the liquid composition, with the remainder being an organic solvent soluble in silicone resin. The present invention will be further explained in detail below.

The present invention is a measuring body coating material containing BN, a low melting point glaze, an inorganic pigment, a silicone resin, and a silicone resin-soluble solvent in a specific proportion. A coating film with excellent mold releasability is formed and can be used as a measuring body coating material.

The powder composition according to the present invention is composed of powders of BN, glaze, and inorganic pigment, and among these, BN is contained in the powder composition components in an amount of 30 to 80% by weight. If the BN exceeds 80 densities, the adhesion with the base material decreases and peeling or cracking occurs, and if the BN exceeds 30 densities, corrosion resistance and mold release deteriorate, which is not good. BN gives the coating film corrosion resistance and mold releasability, and if its purity is low, the corrosion resistance and mold releasability will decrease due to impurities, so if the purity is 90%
% or more is preferable. The particle size is preferably 10 μm or less since it has a significant effect on adhesion to the substrate.

Next, the low-melting point herbal medicine should be contained in the powder composition at a concentration of 1 to 18%, but if the herbal medicine exceeds 18%, the stone shape and heat resistance will deteriorate, and if it is less than 1%, it will not work as a base material. This is undesirable because the adhesion of the paint decreases, and the coating film peels or cracks occur.

A low melting point herbal medicine is one whose melting point is between 300 and 70.
It is at 0°C. The reason for blending such a low-melting-point elixir is that when applying the measuring body coating material of the present invention to a base material and baking it (3), the coating temperature (4) at which the adhesion with the base material decreases, 00
S softens at around ℃ and thermally decomposes the silicone resin to form a
i Reacts with O9 to become stable and adheres closely to the base material. Further, at high temperatures of 700 to 900° C., it reacts with inorganic pigments and becomes stable, resulting in poor adhesion to the substrate.

The inorganic pigment contains 2 to 69% by weight of the BN and the rest of the low melting point glaze, that is, the powder composition components, but if the inorganic '6 pigment exceeds 69% by weight, the BN content becomes relatively low and the mold release property is affected. This is not preferable because it decreases. Moreover, if it is less than 2%, peeling or cracking will occur in the coating film, which is not suitable.

Commercially available inorganic pigments include 几O2, At2O7, and BaS.
White pigments such as O4 and black pigments such as iron oxide (Fe3O4) can be used, and their particle size depends on their reactivity with the glaze,
In consideration of adhesion to the base material, the thickness is preferably 10μ or less, and preferably higher than the melting point of the glaze. This reacts with S = 02 produced when silicone (4) resin thermally decomposes or with the glaze, making it stable, and baking occurs over time, with peeling of the paint film and cracks that occur during rapid heating and cooling. This is necessary to create a coating film with strong adhesion.

Silicone resin is 20 to 60% by weight in the liquid composition components.
If it contains silicone resin, it should be 60% by weight.
If the temperature exceeds 1 to 1, the amount of gas generated during thermal decomposition will increase, causing blistering on the coating film. If it is less than 20% by weight, the adhesion to the substrate at low temperatures will decrease, which is not preferable. As the silicone resin, commercially available silicone resins can be used. Commercially available products include liquid types that contain organic solvents in which silicone resins are dissolved in organic solvents, and modified silicone resins that are mixed with alkyl resins, acrylic resins, phenolic resins, epoxy resins, etc. is also available.

The viscosity of these resins is preferably about 1,000 to 5,000 (1, P). Silicone resins have a viscosity of about 3 ()
It improves the adhesion to the substrate at temperatures up to , or (4) It reacts with the inorganic pigment to become stable and plays a role in adhering to the base material.

The solvent is contained in the liquid composition component in an amount of 40 to 80% by weight.
However, if the amount of solvent is less than 40% by weight, the mixture with the powder composition will be poor, making it difficult to achieve uniform dispersion, and at the same time, the workability during coating will be poor. Moreover, when it exceeds 80% by weight, the dispersed powder composition tends to settle and separate.

Any solvent may be used as long as it is compatible with the silicone resin, such as toluene and xylene.

This improves the mixability when mixing the powder composition components and the liquid composition components, and the workability when coating on a substrate.

In order to manufacture the measuring body coating material according to the present invention, the powder composition and the liquid composition may be placed in a mixer in the proportions described above and mixed for several hours.

In this way, the liquid level gauge used to measure the liquid level or temperature of molten metal or molten alloy manufactured by 1.
When used as a coating material for a measuring body such as a thermometer, it can be used as a undiluted solution or completely diluted with a solvent.For measuring bodies made of cast iron, stainless steel, etc., use an appropriate method such as brush coating, spray painting,
It is sufficient to apply by coating means such as dip coating and drying at room temperature, and since no special means are required, it can be easily used in the field.

All the embodiments of the present invention have been shown above, and will be explained in more detail. Note that all percentages in the examples are expressed on a weight basis.

The practical powder composition consisted of 18% BNN powder with a particle size of 5 μm or less, 2% glaze (frit glass, particle size 5 μm or less, melting point 500°C), and an inorganic pigment (BaSO4, particle size 5 μm or less).20
% and a liquid composition of 26% silicone resin and 34% toluene (IL-34%) were mixed uniformly in a ball mill.
As a result of spray painting a thermometer made of cast iron with a thickness of 50°C and drying it at 200°C for 1 hour, we conducted a continuous immersion test in aluminum molten at 700°C, and the resistance was 5.
It was 0 days or more. Moreover, the mold releasability was also good.

Comparative Example 7'402 (particle size 5μ or less) 30%, kaolinite 20% as a binder, boiled oil (linseed oil) as a dispersion medium
The corrosion resistance was 5 days when the measurement body coating material having a composition of 50% was used, and the mold releasability was poor.

As explained in the examples above, the measuring body coating material according to the present invention has a longer coating life than conventional ones, and also has excellent corrosion resistance and
It has excellent heat resistance and mold releasability, so it is effective as a measuring body protective coating material.

The physical properties of the coating film were measured by the following method.

(1) Corrosion resistance...The coating film of the cast iron thermometer is molten aluminum (
7) Expressed as the number of days of immersion until it is eroded by miniram.

f214 type property: The ease with which the aluminum attached to the cast iron side heating body comes off was visually observed.

Patent applicant Denki Kagaku Kogyo Co., Ltd. (8)

Claims (1)

[Claims] Boron nitride 30-80% by weight, low melting point glaze 1-18%
The composition contained 20 to 60 parts by weight of a powder composition in which $4 part is an inorganic pigment, 20 to 60 parts by weight of a silicone resin, and 80 to 40 parts by weight of a liquid composition in which the remainder is an organic solvent soluble in silicone resin. A coating composition for protecting measuring bodies.