JPH06104220B2 - Method for forming heat fusible fluorine resin layer on metal surface - Google Patents

Description

The present invention relates to a method for forming a heat-meltable fluororesin layer on a metal surface, and more specifically, to a metal surface such as stainless steel, iron or aluminum, which has excellent heat-melting property. The present invention relates to a method for forming a fluororesin layer.

Technical Background of the Invention and Problems Thereof A heat-melting fluororesin such as a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (hereinafter sometimes abbreviated as PFA) has heat resistance, weather resistance, and chemical resistance. It has outstandingly superior properties in comparison with other synthetic resins in terms of corrosion resistance, slipping property, non-adhesiveness, etc. Utilizing these properties, pipelines and tanks handling corrosion resistant fluids or high temperature fluids Alternatively, it is widely used as a corrosive lining material for machines and the like.

However, since the fluororesin such as PFA is non-adhesive as described above, it is considerably difficult to adhere it to another material such as a metal even if an adhesive is used. If the adhesiveness between the base material such as a metal and the fluororesin is poor, the fluororesin liner is lifted from the base material, and the function as the liner cannot be achieved.

For this reason, many methods have been proposed for increasing the adhesiveness between PFA and other fluororesins and metals. One of them is, for example, a method of forming a dovetail groove on the surface of a base material such as a metal to improve the adhesiveness between the base material and the fluororesin. However, this method has a problem that it takes a lot of time to form the dovetail groove on the surface of the base material and the mechanical adhesion between the base material and the fluororesin is not sufficient. Further, a method has been proposed in which the surface of the fluororesin is treated with a solution of metallic sodium dissolved in liquid ammonia to chemically activate the surface. However, this method has a problem that the treatment liquid itself may cause environmental pollution and the handling thereof is dangerous. Further, a method such as subjecting the fluororesin surface to a physicochemical treatment such as plasma sputtering, or mechanically roughening the fluororesin surface has been proposed, but in this method, the treatment is time-consuming. Alternatively, there were problems such as cost increase.

On the other hand, the applicant of the present invention, in JP-A-55-61,961, discloses that a metal surface is coated with a primer composed of an aqueous dispersion of a fluororesin containing chromium ions and hydrogen ions, and a heat-melting fluororesin is applied thereon. It proposes a method for forming a surface layer capable of adhering a fluororesin on a metal surface, which is characterized by uniformly dispersing and adhering powder, and heating and melting at a temperature higher than the decomposition temperature of the thermofusible fluororesin. According to this method, a fluororesin layer firmly adhered to the metal surface can be provided, but since the primer contains chromium ions, its handling is dangerous and causes environmental pollution. There was a problem of fear. Moreover, there is a problem in that the foaming phenomenon is recognized due to the decomposition of the primer because it is heated at the time of adhesion.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and to provide a primer containing a chromium ion or an organic material containing a chromium ion which may cause environmental pollution. Without using PF on metal surface
It is an object of the present invention to provide a method capable of firmly forming a heat-meltable fluororesin layer such as A.

SUMMARY OF THE INVENTION A method of forming a heat-meltable fluororesin layer on a metal surface according to the present invention comprises: (i) a metal oxide powder and (ii) a metal surface.
The method is characterized in that after the metal powder or the metal fluoride powder or both are adhered, a heat-meltable fluororesin powder layer is provided on these powders and then heated to a temperature above the melting point of the heat-meltable fluororesin.

According to the method for forming a heat-meltable fluororesin layer on a metal surface according to the present invention, after (i) a metal oxide powder and (ii) a metal powder or a metal fluoride powder or both are adhered to the metal surface, Since a heat-meltable fluororesin powder layer is provided on these powders and then heated above the melting point of the heat-meltable fluororesin, it is possible to firmly bond the fluororesin layer and the metal without using a primer. Further, it is possible to obtain an effect that a pressurizing device is not necessarily required for adhesion, and furthermore, foaming due to decomposition of the primer does not occur during adhesion.

DETAILED DESCRIPTION OF THE INVENTION The method for forming the heat-meltable fluororesin layer on the metal surface according to the present invention will be specifically described below.

In the present invention, the heat-melting fluororesin layer is formed on the metal surface, and as the metal on which the heat-melting fluororesin layer is formed, metals such as stainless steel, iron and aluminum are widely used.

The metal on which the fluororesin layer is formed is preliminarily subjected to sand blasting or grid blasting on its surface to remove foreign substances such as rust adhering to the metal surface to clean the metal surface, It is preferable to roughen the metal surface in order to enhance the adhesive force between the metal and the fluororesin.

Next, (i) a metal oxide powder and (ii) a metal powder or a metal fluoride powder, or both are adhered to such a metal surface. Specific examples of the metal oxide powder to be attached include zinc oxide, cobalt oxide, manganese oxide, iron oxide, copper oxide, tin oxide, magnesium oxide and the like. These metal oxide powders may be used alone or in combination of two or more. Of these, zinc oxide and manganese oxide are particularly preferable.

Further, in the present invention, a metal powder, a metal fluoride powder, or both are used together with the above-mentioned metal oxide powder.

As the metal powder, specifically, zinc, cobalt, manganese, iron, copper, tin, magnesium or the like is used.

Further, as the metal fluoride powder, specifically, zinc fluoride, copper fluoride, chromium fluoride or the like is used.

In the present invention, 100 parts by weight of the metal oxide powder, 5 to 10 parts by weight of the metal powder or the metal fluoride powder or both.
It is preferably used in a mixed amount of 0 parts by weight, preferably 60 to 80 parts by weight.

The particle size of these (i) metal oxide powder and (ii) metal powder or metal fluoride powder is 200 μm.
The thickness is preferably 80 μm or less. When these powders exceed 200 μm, these powders are separated from the metal surface, which is not preferable.

These powders, as described above, are added to the metal surface at 0.0 / cm ₂
It is desirable to deposit in an amount of 01 to 0.1 g, preferably 0.003 to 0.005 g. To attach these powders to the metal surface, for example, by dispersing and mixing these powders in an organic solvent such as acetone, apply the powder to the metal surface by, for example, a brush coating method, and then dry the organic solvent. Good.

After depositing these powders on the metal surface as described above, the heat-meltable fluororesin powder is provided thereon. As the heat-meltable fluororesin, specifically, the above-mentioned PF
A, FEP which is a copolymer of tetrafluoroethylene and hexafluoropropylene, EPE which is a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether, PCTFE which is polychlorotrifluoroethylene, and ethylene ETFE or the like, which is a copolymer with tetrafluoroethylene, is used.

These heat-meltable fluororesins have a particle size of 20-500μ.
m, preferably about 100 to 500 μm.
This fluororesin powder is less than 20 μm or 500
When it exceeds μm, a foaming phenomenon is recognized, which is not preferable.

The above heat-fusible fluororesin powder has 1
Provided in an amount of 0.1 to 2.0 g, preferably 0.5 to 1.0 g per cm ₂ ,
The thickness of the fluororesin is 0.4 to 10 mm, preferably about 2 to 4 mm.

After the heat-meltable fluororesin layer is provided on the powder in this manner, heating is performed at a temperature equal to or higher than the melting temperature of the heat-meltable fluororesin. 360 if the heat fusible fluoropolymer is PFA
It is preferable to heat and melt at a temperature of ~ 370 ° C. Generally, the heating time is preferably 0.5 to 1 hour. Cooling after heating may be performed by natural cooling, for example.

When the heat-meltable fluororesin layer is formed on the metal surface through the powder in this way, the metal and the fluororesin layer are formed as compared with the case where the heat-meltable fluororesin layer is formed on the metal surface without using the powder. The adhesive strength with is significantly improved. For example, when the PFA layer is adhered to the iron plate via the zinc oxide powder and the manganese oxide powder, the peel strength is 8 to 10 Kgf / cm, whereas the PFA layer is directly adhered to the iron plate. In some cases, the peel strength is only 2-3 Kgf / cm.

Further, in the present invention, when forming the heat-fusible fluororesin layer on the metal surface, since the primer containing from ion or the primer containing organic resin is not applied, foaming due to decomposition of the primer does not occur at all, and the appearance is beautiful. Moreover, the adhesive strength between the fluororesin layer and the metal is excellent. Further, it is not always necessary to press-bond the fluororesin layer and the metal plate to each other for adhesion.

EFFECTS OF THE INVENTION According to the method for forming a heat-meltable fluororesin layer on a metal surface according to the present invention, (i) a metal oxide powder and (ii) a metal powder or a metal fluoride powder or both are attached to the metal surface. After that, a heat-melting fluororesin powder layer is provided on these powders, and since it is heated above the melting point of the heat-melting fluororesin, the fluororesin layer and metal are firmly bonded without using a primer. Further, it is possible to obtain the effect that the pressurizing device is not necessarily required for the adhesion, and furthermore, the foaming due to the decomposition of the primer does not occur during the adhesion.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 The surface of an iron plate (SS41) was degreased with acetone and then sandblasted to remove foreign substances such as rust on the surface for cleaning and roughening the surface of the metal plate.

In this way, the grain size of 30μ
Mixture of zinc oxide powder and zinc powder (zinc oxide powder
50% by weight, zinc powder 50% by weight) is dispersed in an acetone solvent so that the amount of 0.005 g per 1 cm _{2 of} metal surface is applied to these powders, and then the composition is dried to obtain a metal surface. The powder was deposited on top.

Next, add 1 cm ₂ of PFA powder with a particle size of 200 μm onto these powders.
After being provided in an amount of 0.7 g per unit, it was heated at a temperature of 370 ° C. for 1 hour.

In this way, the PFA layer was formed on the iron plate. When the peel strength (Kgf / cm) between the PFA layer and the iron plate was examined, the peel strength was 8.3 Kgf / cm.

Example 2 The surface of an iron plate (SS41) was degreased with acetone and then sandblasted to remove foreign substances such as rust on the surface for cleaning and roughening the surface of the metal plate.

In this way, the grain size of 30μ
0.005 per 1 cm _{2 of} metal surface, a composition prepared by dispersing a mixture of zinc oxide and zinc fluoride powder of m (65% by weight of zinc oxide powder, 35% by weight of zinc fluoride powder) in an acetone solvent.
The powders were applied so that the powders were applied in amounts of g and then dried to deposit the powder on the metal surface.

Next, add 1 cm ₂ of PFA powder with a particle size of 200 μm onto these powders.
After being provided in an amount of 0.7 g per unit, it was heated at a temperature of 370 ° C. for 1 hour.

In this way, the PFA layer was formed on the iron plate. When the peel strength (Kgf / cm) between the PFA layer and the iron plate was examined, the peel strength was 9.2 Kgf / cm.

Comparative Example 1 The procedure of Example 1 was repeated except that the metal oxide powder and the metal powder were not attached to the iron plate.
Formed with PFA layer.

The peel strength between the PFA layer and the iron plate was 2-3 Kgf / cm.

Claims (4)

[Claims] 1. After depositing (i) a metal oxide powder and (ii) a metal powder or a metal fluoride powder or both on a metal surface, a heat-meltable fluororesin powder layer is provided on these powders, Next, a method for forming a heat-meltable fluororesin layer on a metal surface, which comprises heating to a temperature not lower than the melting point of the heat-meltable fluororesin. 2. The metal oxide powder is zinc oxide, cobalt oxide, manganese oxide, iron oxide, copper oxide, tin oxide, or magnesium oxide having a particle size of 200 μm or less. The method described. 3. Metal powder or metal fluoride powder is 200μ
The method according to claim 1, which is zinc, cobalt, manganese, tin, copper or zinc fluoride, copper fluoride, or chromium fluoride having a particle diameter of m or less. 4. The method according to claim 1, wherein the heat-meltable fluororesin is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether having a particle size of 20 to 500 μm.