JPH07266495A - Manufacture of resin-clad metallic body - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a resin-clad metallic body having excellent durability in which degradation of adhesion between the metallic body and a polyethylene resin coating layer is a little even when the metallic body is used for a long time under a hard condition. CONSTITUTION:A surface of a metallic material is coated with a primer made by mixing 1-8wt.%, of glass short fiber-containing silane modified polyethylene resin powder to an organic titanate solution having a density of 5-40wt.%, which is heated to 200-250 deg.C so as to form a sintered layer of the primer, the work is repeated for a plurality of times, and a coating layer of a silane modified polyethylene resin is formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin-coated metal body having excellent durability.

[0002]

2. Description of the Related Art In order to improve the corrosion resistance of a metal body, the surface of the metal body is generally coated with a synthetic resin. As a synthetic resin, an inexpensive and chemically stable polyethylene resin is widely used.

Polyethylene resin has poor adhesiveness to a metal body, and as a resin-coated metal body that improves this, JP-A-2-
Japanese Patent No. 76960 discloses a resin-coated metal body obtained by extrusion-coating a surface of a steel pipe with a silane-modified polyethylene resin, and then extrusion-coating a polyethylene resin thereon.

[0004]

In the resin-coated metal body of the above proposal, the silane-modified polyethylene resin serves as a primer to considerably improve the adhesiveness between the metal body and the polyethylene resin coating layer. In terms of durability, it is not yet fully satisfactory.

That is, the resin-coated metal body proposed above is
If it is used for a long period of time under severe conditions such as the transfer of hot water or high temperature chemicals, the adhesive strength between the metal body and the polyethylene resin coating layer will decrease due to the deterioration of the above primer and repeated shear stress, and at the interface There is a problem that the metal body peels off and rusts or corrodes.

The present invention solves the above-mentioned problems, and it is an object of the present invention that the adhesive strength between a metal body and a polyethylene resin coating layer is not significantly reduced even when used under severe conditions for a long period of time. It is to provide a method for producing a resin-coated metal body having excellent durability.

[0007]

A method for producing a resin-coated metal body according to the present invention comprises: a glass material containing silane-modified polyethylene resin powders 1 to 8 in a glass titanate solution having a concentration of 5 to 40% by weight on the surface of a metal material. A primer composed of a mixture of 10 wt% is applied, and this is heated to 200 to 250 ° C to form a sintered layer of the primer, and the above operation is repeated a plurality of times to form a coating layer of a silane-modified polyethylene resin on it. The above object can be achieved thereby.

In the present invention, the metal body is iron,
A metal such as steel or aluminum formed into an arbitrary shape such as a tubular shape, a rod shape, or a plate shape is used. The surface of these metal bodies is generally subjected to a blasting treatment, a degreasing treatment with an alkali or the like, and a pickling treatment with hydrochloric acid, nitric acid, sulfuric acid or the like in order to improve the adhesion to the primer.
Further, if necessary, a chemical conversion coating treatment with zinc phosphate, iron phosphate or the like may be performed.

On the surface of the metal body, a primer prepared by mixing a glass short fiber-containing silane-grafted polyethylene resin powder with an organic titanate solution is applied. As a method of applying the primer, a known primer method such as a roll, brush, brush or coating rod is adopted. The surface of the metal body to be applied may be an inner surface, an outer surface, or both inner and outer surfaces.

The organic titanate is tetra-iso.
-Propoxy titanium, tetra-n-butoxy titanium, tetrakis (2-ethylhexyloxy) titanium, tetrastearyloxy titanium, di-iso-propoxy bis (acetylacetonato) titanium, di-n-butoxy.
Examples thereof include bis (triethanolaminato) titanium and dihydroxy bis (lactato) titanium.

These organic titanates are diluted with an organic solvent such as iso-propanol, n-hexane, benzene and toluene, and the solution concentration is 5 to 40% by weight,
It is preferably adjusted to 10 to 30% by weight.

The solution concentration of the organic titanate is 5% by weight.
If the amount is less than the above, the workability at the time of application is poor, and the number of operations for forming the sintered layer of the primer increases due to the relationship with the thickness of the primer layer. It becomes susceptible to deterioration due to history and adversely affects the adhesive durability. On the other hand, when the concentration exceeds 40% by weight, workability at the time of coating is poor and the heating temperature may be relatively low, so that the size of cracks becomes small and the adhesion durability is adversely affected.

The glass short fiber-containing silane-modified polyethylene resin powder is a mixture of polyethylene resin 95 to 70% by weight, preferably 90 to 80% by weight, and glass short fiber 5 to 30% by weight, preferably 10 to 20% by weight. A silane compound is added to, and the mixture is melted and kneaded by an extruder or roll in the presence of a radical generator, the silane compound is grafted to the polyethylene resin by the action of the radical generator, and this is finely pulverized with a freeze pulverizer or the like. Can be obtained by

When the glass short fiber-containing silane-modified polyethylene resin powder is not used and the glass short fiber and the silane-modified polyethylene resin powder are separately used and mixed with the organic titanate solution, it is preferable. No results are obtained.

Here, as the polyethylene resin, usual low density, medium density, high density polyethylene and linear low density polyethylene are used. And, the silane compound is 0.1 to 1 with respect to 100 parts by weight of the polyethylene resin.
0 parts by weight, preferably 0.25 to 3 parts by weight are blended,
The radical generator is 0.001 to 2 parts by weight, preferably 0.0015 to 100 parts by weight of the polyethylene resin.
0.1 part by weight is blended.

The particle size of the silane-modified polyethylene resin powder containing short glass fibers is preferably in the range of 5 to 30 μm, more preferably 10 to 20 μm. If the particle size of the resin powder is too small, the dispersibility in the organic titanate solution is deteriorated and the resin particles are aggregated and a uniform primer cannot be obtained. On the other hand, if the particle size of the resin powder is too large, it becomes difficult for the resin powder to enter the cracks formed in the sintered layer of the primer, and a sufficient anchoring effect cannot be obtained. The adhesive strength of.

The silane compound contains a hydrolyzable alkoxy group (eg, methoxy group, ethoxy group, butoxy group) and is an unsaturated hydrocarbon group (eg, vinyl group, allyl group, butenyl group, particularly vinyl group). Groups are preferable), and typical examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldiethoxysilane and the like.

As the radical generator, organic peroxides such as dicumyl peroxide, dibutyl peroxide, 2,5-di-methyl-2,5-di (t-butyl peroxide) hexane and azobis. Organic azo compounds such as isobutyronitrile and dimethylazoisobutyrate are used.

The silane-modified polyethylene resin powder containing short glass fibers thus obtained has a concentration of 5 to 40% by weight.
In an organic titanate solution of 1 to 8% by weight, preferably 2 to
The primer is mixed in the range of 5% by weight.

If the glass short fiber-containing silane-modified polyethylene resin powder in the organic titanate solution is less than 1% by weight,
Cracks are less likely to occur in the sintered layer of the primer, and a sufficient anchor effect cannot be obtained. On the other hand, when the glass short fiber-containing silane-modified polyethylene resin powder exceeds 8% by weight, the number of cracks formed in the sintered layer of the primer becomes too large and the sintered layer of the primer is destroyed, thereby achieving the purpose. Can not be.

The above-mentioned primer is applied to the surface of the metal body, and then 200 to 250 ° C., preferably 220 to 24.
It is heated to 0 ° C., whereby a sintered layer of the primer is formed on the surface of the metal body. Then, this operation is repeated a plurality of times. Usually, it is repeated a few times, and the final thickness of the sintered layer is preferably 10 to 50 μm. As the heating method, a known heating method such as a heating method using hot air, a heating method using a burner, or an induction heating method is adopted.

A coating layer of silane-modified polyethylene resin is formed on the sintered layer of the primer thus formed. The silane-modified polyethylene resin constituting this coating layer can be obtained by the same method using the same polyethylene resin, silane compound and radical generator as those used in the preparation of the primer.

For example, 0.1 to 10 parts by weight of a silane compound and 0.001 to 2 parts by weight of a radical generator are added to 100 parts by weight of a polyethylene resin, and this is added in the presence of a radical generator by an extruder or a roll. It can be obtained by melt-kneading and grafting a silane compound onto a polyethylene resin by the action of a radical generator.

As a method of forming the coating layer of the silane-modified polyethylene resin on the sintered layer of the primer, a known method such as a melt extrusion method, a powder coating method, a sheet pressure bonding method or the like is adopted. . The thickness of the coating layer of the silane-modified polyethylene resin is generally about 0.05 to 3 mm.

The above silane-modified polyethylene resin is used for the purpose of reducing the linear expansion coefficient and suppressing molding shrinkage.
If necessary, known fillers such as short glass fibers, talc, mica, potassium titanate, and whiskers may be contained. Further, if necessary, known additives such as a coloring agent such as carbon black, an antioxidant and an ultraviolet absorber may be contained.

[0026]

The primer which is obtained by mixing the organic titanate solution having a concentration of 5 to 40% by weight with the glass short fiber-containing silane-modified polyethylene resin powder of 1 to 8% by weight is applied to the surface of the metal body, and this is applied at 200 to 250 ° C. When heated to form a sintered layer of the primer, titanium oxide mainly forms due to the action of the organic titanate, which chemically bonds strongly to the metal body, improving the adhesion between the metal body and the sintered layer of the primer. To do.

When observing the sintered layer of the primer with an electron microscope, innumerable small cracks (cracks) are formed on the surface thereof, and the cracks are formed by repeating the operation of forming the sintered layer of the primer a plurality of times. Since the generation location is shifted, even if moisture enters from the resin coating layer, the moisture can be prevented from reaching the metal surface.

When a coating layer of silane-modified polyethylene resin is formed on the thus-formed primer sintered layer, the resin of the coating layer enters into the numerous small cracks on the surface of the sintered layer. An anchor effect occurs, and due to this anchor effect and the adhesive force due to the silanol groups of the silane compound in the coating layer being hydrolyzed to form a siloxane bond, the sintered layer of the primer and the coating resin are firmly bonded.

Moreover, since the silane-modified polyethylene resin is contained in the sintered layer of the primer, the compatibility with the coating resin is improved, the adhesive force by heat fusion of both resins is increased, and the primer is baked. Since the tie layer contains short glass fibers, the molding shrinkage of the sintered layer is reduced, and the decrease in the adhesive force between the metal body and the coating layer is suppressed.

Further, the primer is sintered at a temperature of 200 to 250 ° C., and this temperature is relatively low, so that the silane-modified polyethylene resin in the primer is less likely to be carbonized, so that good primer baking is possible. A tie layer is formed and heat-bonded firmly to the silane-modified polyethylene resin of the coating layer.

[0031]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Example 1 As an organic titanate solution, di-iso-propoxy.
A 30 wt% i-propanol solution of bis (acetylacetonato) titanium (T-50: manufactured by Nippon Soda Co., Ltd.) was prepared.

As silane-modified polyethylene resin powder containing short glass fibers, polyethylene resin (density 0.935 g
/ Cm ³ , melt index 5g / 10 minutes) 80% by weight
And 20% by weight of glass short fibers (silane treated chopped strands, cut length 3 mm, filament diameter 13 μm) were mixed with a tumbler, 100 parts by weight of this mixture, 1 part by weight of vinyltrimethoxysilane and 0.04 parts by weight of dibutyl peroxide. Parts were mixed, melted and kneaded by an extruder at 190 ° C., pelletized by a pelletizer, and then freeze-ground to prepare a powder having an average particle size of 20 μm.

Then, 95 parts by weight of the above organic titanate solution and 5 parts by weight of glass short fiber-containing silane-modified polyethylene resin powder were placed in a container and well stirred to prepare a primer.

As the silane-modified polyethylene resin used for the coating layer, the same polyethylene resin as described above (density 0.935 g / cm ³ , melt index 5 g / 10
Min) 100 parts by weight, 1 part by weight of vinyltrimethoxysilane and 0.04 parts by weight of dibutyl peroxide are mixed,
This was melt-kneaded at 190 ° C. with an extruder and pelletized by applying it to a pelletizer.

Steel plate (length 120 mm x width 120 mm x thickness 2 m
m) is subjected to alkali degreasing and pickling treatment with nitric acid, and the treated surface is coated with the above-mentioned primer with a brush and heated at 240 ° C. for 10 minutes in a hot-air dryer to obtain a sintered layer of the primer on the surface of the steel sheet. Was formed.

Then, the primer-treated steel sheet was left to stand at room temperature for 5 minutes to be cooled, and the primer was again applied onto the sintered layer of the primer-treated steel sheet with a brush, and this was dried in a hot air dryer at 240 ° C. A similar sintered layer of the primer was formed on the first sintered layer of the steel sheet by heating for 10 minutes. The thickness of the thus obtained sintered layer (total thickness of the sintered layers) was 40 μm.

A spacer having a thickness of 2 mm was placed around the sintered layer of the steel sheet, and the silane-modified polyethylene resin for forming a coating layer was extruded in a molten state at 190 ° C. in the central portion thereof, and a press machine was pressed from above. 2mm thickness by pressing
A resin-coated steel sheet was produced by forming a coating layer of the silane-modified polyethylene resin of 1.

Regarding this resin-coated steel sheet, JIS K-
According to 6854, the peeling adhesion strength between the steel plate and the coating layer (however, T-type peeling adhesion strength of 10 mm width) was measured,
The peel adhesive strength was strong at a width of 25.8 kg / 10 mm.

The resin-coated steel sheet was dipped in hot water at 90 ° C. for 5 minutes, then dipped in cold water at 20 ° C. for 5 minutes, and this hot water-cold water dipping operation was repeated 10,000 cycles. Regarding, regarding the shrinkage and peeling of the coating resin layer at the end portion, the generation of a gap between the steel sheet and the like, the abnormalities were not observed at all. With respect to the resin-coated steel sheet after the hot water-cold water immersion test, the peel adhesion strength of the coating layer was measured, and the peel adhesion strength was 2
It had a width of 2.2 kg / 10 mm and had excellent adhesion durability.

Example 2 A steel pipe (outer diameter: 114 mm × length: 5 m) was alkali-degreased and pickled with nitric acid, and the inner surface of the steel pipe was subjected to Example 1
The same primer as used in 1. was applied with a rotating brush and heated by induction heating at 230 ° C. for 5 minutes to form a sintered layer of the primer on the inner surface of the steel pipe.

Next, the primer-treated steel pipe was left to cool at room temperature for 5 minutes, and the primer was again applied onto the sintered layer of the primer-treated steel pipe with a rotating brush, and this was heated at 230 ° C. by induction heating. A similar sintered layer of the primer was formed on the first sintered layer on the inner surface of the steel pipe by heating for 5 minutes. The thickness of the thus obtained sintered layer (total thickness of the sintered layers) was 30 μm.

On top of this sintered layer on the inner surface of the steel pipe, a silane-modified polyethylene resin, which is the same as that used in Example 1, is added.
A resin-coated steel pipe was produced by melt-extrusion coating at ℃ and forming a coating layer of silane-modified polyethylene resin having a thickness of 2.5 mm.

Hot water at 90 ° C. was added to the resin-coated steel pipe for 5 hours.
After passing 000 hours, the resin-coated steel pipe had excellent adhesion durability, with no shrinkage or peeling of the coating resin layer and cracking of the sintered layer of the primer being observed.

Example 3 A resin-coated steel sheet was produced in the same manner as in Example 1 except that the heating temperature after coating the primer was changed to 220 ° C.

The peel adhesion strength between the steel plate and the coating layer of this resin-coated steel plate was 25.3 kg / 10 mm width, which was strong.
Also, in the hot water-cold water 10,000 cycle immersion test,
No abnormalities such as shrinkage and peeling of the coating resin layer and generation of a gap between the coating resin layer and the like were observed. The peel adhesion strength after this hot water-cold water immersion test was 21.4 kg / 10 mm width, which was excellent in adhesion durability.

Example 4 The organic titanate solution concentration was changed to 10% by weight, the average particle size of the glass short fiber-containing silane-modified polyethylene resin powder was changed to 10 μm, and the operation of forming a sintered layer of the primer was repeated three times. Repeated (total thickness of sintered layers is 40μ
m). Other than that was performed similarly to Example 1, and manufactured the resin coated steel plate.

The peel adhesion strength between the steel plate and the coating layer of this resin-coated steel plate was 24.9 kg / 10 mm width, which was strong.
Also, in the hot water-cold water 10,000 cycle immersion test,
No abnormalities such as shrinkage and peeling of the coating resin layer and generation of a gap between the coating resin layer and the like were observed. The peel adhesion strength after this hot water-cold water immersion test was 21.1 kg / 10 mm width, which was excellent in adhesion durability.

Example 5 The organic titanate solution concentration was changed to 10% by weight, the average particle size of the glass short fiber-containing silane-modified polyethylene resin powder was changed to 10 μm, and the operation of forming a sintered layer of the primer was repeated three times. Repeated (total thickness of sintered layers is 40μ
m). Otherwise in the same manner as in Example 2, a resin-coated steel pipe was manufactured.

Hot water at 90 ° C. was added to the resin-coated steel pipe for 5 hours.
After passing 000 hours, the resin-coated steel pipe had excellent adhesion durability, with no shrinkage or peeling of the coating resin layer and cracking of the sintered layer of the primer being observed.

Example 6 The procedure of Example 1 was repeated, except that 93 parts by weight of the organic titanate solution and 7 parts by weight of glass short fiber-containing silane-modified polyethylene resin powder were mixed to prepare a primer.
A resin-coated steel plate was manufactured.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 25.2 kg / 10 mm width, which was strong.
Also, in the hot water-cold water 10,000 cycle immersion test,
No abnormalities such as shrinkage and peeling of the coating resin layer and generation of a gap between the coating resin layer and the like were observed. The peel adhesion strength after this hot water-cold water immersion test was 21.6 kg / 10 mm width, which was excellent in adhesion durability.

Example 7

A resin-coated steel sheet was produced in the same manner as in Example 1 except that 98 parts by weight of the organic titanate solution and 2 parts by weight of the glass short fiber-containing silane-modified polyethylene resin powder were mixed to prepare a primer.

The peel adhesion strength between the steel plate and the coating layer of this resin-coated steel plate was 25.5 kg / 10 mm width, which was strong.
Also, in the hot water-cold water 10,000 cycle immersion test,
No abnormalities such as shrinkage and peeling of the coating resin layer and generation of a gap between the coating resin layer and the like were observed. The peel adhesion strength after this hot water-cold water immersion test was 22.1 kg / 10 mm width, which was excellent in adhesion durability.

Comparative Example 1 A resin-coated steel sheet was produced in the same manner as in Example 1 except that the primer coating was omitted and the primer sintered layer was not formed.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 18.1 kg / 10 mm width. Also,
In a 10000-cycle immersion test of hot water / cold water, the coating resin layer on the entire circumference was peeled off from the end of the coating resin layer by about 5 mm, and the coating resin layer on the entire circumference was shrunk by about 1 to 2 mm from the end. Admitted. The peel adhesion strength after this hot water-cold water immersion test was 3.8 kg / 10 mm width, and the adhesion durability was poor.

Comparative Example 2 A resin-coated steel sheet was produced in the same manner as in Example 1 except that the concentration of the organic titanate solution was changed to 3% by weight and the total thickness of the sintered layers was changed to 15 μm.

The peel adhesion strength between the steel plate and the coating layer of this resin-coated steel plate was 20.4 kg / 10 mm width. Also,
In a hot water-cold water immersion test of 10,000 cycles, no abnormalities such as shrinkage of the coating resin layer, peeling, and generation of a gap between the steel plate were observed, but the peel adhesion strength after this hot water-cold water immersion test. Had a width of 11.5 kg / 10 mm and had poor adhesion durability.

Comparative Example 3 A resin-coated steel sheet was produced in the same manner as in Example 1 except that the concentration of the organic titanate solution was changed to 50% by weight.

The peel adhesion strength between the steel plate and the coating layer of this resin-coated steel plate was 21.1 kg / 10 mm width. Also,
In a hot water-cold water immersion test of 10,000 cycles, no abnormalities such as shrinkage of the coating resin layer, peeling, and generation of a gap between the steel plate were observed, but the peel adhesion strength after this hot water-cold water immersion test. Had a width of 10.2 kg / 10 mm and had poor adhesion durability.

Comparative Example 4 A resin-coated steel pipe was produced in the same manner as in Example 2 except that the primer coating was omitted and the primer sintered layer was not formed.

Hot water at 90 ° C. was added to the resin-coated steel pipe for 5 hours.
After passing 000 hours, peeling was observed in the coating resin layer on the entire circumference of the resin-coated steel pipe over about 50 mm from the pipe end, and the adhesion durability was poor.

Comparative Example 5 A resin-coated steel sheet was produced in the same manner as in Example 4, except that the heating temperature after coating the primer was changed to 180 ° C.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 11.5 kg / 10 mm width. Also,
In a 10000-cycle immersion test of hot water / cold water, the coating resin layer was peeled off during the test, and the adhesion durability was poor.

Comparative Example 6 A resin-coated steel sheet was produced in the same manner as in Example 4, except that the heating temperature after applying the primer was changed to 300 ° C.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 21.6 kg / 10 mm width. Also,
In a hot water-cold water immersion test of 10,000 cycles, no abnormalities such as shrinkage of the coating resin layer, peeling, and generation of a gap between the steel plate were observed, but the peel adhesion strength after this hot water-cold water immersion test. Had a width of 11.4 kg / 10 mm and had poor adhesion durability.

Comparative Example 7

A resin-coated steel sheet was produced in the same manner as in Example 1 except that 85 parts by weight of the organic titanate solution and 15 parts by weight of the glass short fiber-containing silane-modified polyethylene resin powder were mixed to prepare a primer.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 18.5 kg / 10 mm width. Also,
In a hot water-cold water immersion test of 10,000 cycles, the coating resin layer on the entire circumference was peeled off from the end of the coating resin layer for about 3 mm, and the coating resin layer on the entire circumference was shrunk for about 1 mm or less from the end. Admitted. The peel adhesion strength after this hot water-cold water immersion test was 4.0 kg / 10 mm width,
The adhesion durability was poor.

Comparative Example 8

A resin-coated steel sheet was prepared in the same manner as in Example 1 except that 99.5 parts by weight of the organic titanate solution and 0.5 part by weight of silane-modified polyethylene resin powder containing short glass fibers were mixed to prepare a primer. Was manufactured.

The peel adhesion strength between the steel sheet and the coating layer of this resin-coated steel sheet was 21.9 kg / 10 mm width. Also,
In a hot water-cold water immersion test of 10,000 cycles, no abnormalities such as shrinkage of the coating resin layer, peeling, and generation of a gap between the steel plate were observed, but the peel adhesion strength after this hot water-cold water immersion test. Had a width of 13.6 kg / 10 mm and had poor adhesion durability.

[0073]

As described above, according to the method for producing a resin-coated metal body of the present invention, glass short fiber-containing silane-modified polyethylene resin powders 1 to 8 are added to an organic titanate solution having a concentration of 5 to 40% by weight on the surface of the metal body. A primer composed of a mixture of 10 wt% is applied, and this is heated to 200 to 250 ° C to form a sintered layer of the primer, and the above operation is repeated a plurality of times to form a coating layer of a silane-modified polyethylene resin on it. According to such a manufacturing method, even if it is used for a long period of time under severe conditions, a resin-coated metal body excellent in durability with little decrease in adhesive strength between the metal body and the polyethylene resin coating layer is obtained. Obtainable.

Therefore, the resin-coated metal body obtained according to the present invention can be suitably used in various applications where corrosion resistance and durability are required.

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Claims (1)

[Claims] 1. A primer obtained by mixing 1 to 8% by weight of glass short fiber-containing silane-modified polyethylene resin powder with an organic titanate solution having a concentration of 5 to 40% by weight is applied to the surface of a metal body, and this is applied to 200 to A method for producing a resin-coated metal body, which comprises heating to 250 ° C. to form a sintered layer of a primer, repeating the above operation a plurality of times, and forming a coating layer of a silane-modified polyethylene resin thereon.