JPH0596235A - Fluoroplastic coated article - Google Patents

Abstract

PURPOSE:To provide a coated article having strong adhesion and heat resistance by applying a fluoroplastic layer to the surface of a glass base material to impart water repellency and non-tackiness thereto without markedly losing the transparency of said base material. CONSTITUTION:A transparent primer layer composed of silica or a mixture of silica with alumina vitrified by dehydrocondensation reaction at room temp. to 400 deg.C is applied to a glass or ceramics base material and a fluoroplastic coating layer containing FEP in an amount of 20% or more by wt. of a fluoroplastic component is applied on said primer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin coating, and more specifically, it imparts water repellency and non-adhesiveness to the surface of a glass substrate without significantly deteriorating the transparency of the glass, and has a strong adhesion. The present invention relates to a heat-resistant fluororesin coating and a fluororesin coating that imparts water repellency and non-adhesiveness to the surface of a ceramic substrate and has strong adhesion and heat resistance.

[0002]

2. Description of the Related Art Conventionally, as a water-repellent, non-tacky article using a fluoropolymer, a fluorocarbon resin is coated on a metal substrate such as aluminum or stainless steel through a primer containing a binder such as polyamideimide. Things are common,
It is often used in kitchen applications such as frying pans, hot plates, and jar rice cooker inner pots. Particularly when aluminum is used as a base material, a method is often used in which a fluorine resin is physically adhered to the surface of the aluminum by providing fine irregularities by etching or the like without using such a primer.

As a coating for glass, a frying pan made of glass or a pot made of glass in which the cooking surface is coated with a fluororesin is commercially available. Both are black or dark brown coating, which is a feature of glass. It was a loss of transparency. Perhaps because of this problem, the fluororesin coating of the product group is limited to the bottom or side surface of the glass frying pan or pan, which is relatively lower than the side surface, and the side surface that allows the cooked food to be seen through from the outside. There is no coating on the upper part or the lid. Therefore, the washability of these cooking utensils was insufficient.

On the other hand, as a transparent coating on glass, a silicone or acrylic resin coating is often used for the purpose of protecting the glass surface and preventing scattering of fragments at the time of breakage.
These polymers are insufficient in water repellency and non-adhesiveness.
Also, the coatings for the windshields of automobiles were wax-like temporary. That is, the present situation is that no coating has been developed that imparts water repellency and non-adhesiveness to the glass surface without significantly deteriorating the transparency of the glass and has strong adhesion and heat resistance. Moreover, as a coating on ceramics, one having sufficient adhesive strength has not been obtained.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a glass substrate with water repellency, without significantly losing the transparency of the glass substrate.
It aims to provide a coating that is non-tacky, yet has strong adhesion and heat resistance, and is a kitchen article such as a glass frying pan, a glass pot, a window material such as a microwave oven or a toaster oven, Home appliances, office equipment such as toner boxes for copying machines, telephone box window materials, building materials such as high-rise building window materials, automobile side mirrors, automobile traffic safety equipment such as mirrors installed at intersections, optical fiber cable cladding or coating. It is intended to solve problems in a wide range of fields that require transparency, water repellency, non-adhesiveness, adhesiveness, and heat resistance. Needless to say, the present invention is also effective in applications where special transparency is not important, such as coating on ceramics or glass cloth.

[0006]

According to the present invention, a transparent primer layer comprising silica or silica or a mixture of silica and alumina vitrified by a dehydration condensation reaction at room temperature to 400 ° C. or lower and a fluororesin is formed on a glass or ceramic substrate. 20% by weight or more FEP in the fluororesin component
It is a fluororesin coating characterized by being coated with a fluororesin coating layer containing

Note that at least the following is included as an embodiment of the present invention. (A) Fluororesin coating layer is PFA or PTF
E, or a mixture of PFA and PTFE in an amount of 80 wt% or less, the fluororesin coating of the present invention.

(B) The thickness of the transparent primer is 0.1μ
The fluororesin coating of the present invention, which has a structure of 5 μm or less.

The present invention will be described in detail below.

As the glass substrate used in the present invention, silicate glass such as soda lime glass, phosphosilicate glass, borosilicate glass and borosilicate low alkali glass, and quartz glass such as lead glass, barium glass and fluorine glass. However, it is not particularly limited. Also, those that have been strengthened by quenching can be used without any problems.

These glasses may be used as they are, or may be roughened by etching, blasting or the like. However, in the present invention, the improvement of the adhesive strength due to the roughening is not particularly required. Since the adhesive strength of the coating film can be obtained, even if roughening is performed, it should be kept within a range where the transparency is not significantly lost when the coating is completed. When coating glass, it is necessary to degrease and clean the surface with a solvent or alkali.

The ceramic substrate used in the present invention is not particularly limited and can be widely applied, and general ceramics such as pottery, porcelain, bricks and enamels and so-called fine ceramics can also be used. Similar to glass, ceramics do not require special surface treatment, but they are not excluded. In addition, degreasing and cleaning are necessary when coating.

The transparent primer used in the present invention, which is vitrified at room temperature to 400 ° C. or less by dehydration condensation reaction, or a transparent primer made of a fluororesin and a mixture of silica and alumina is, for example, PTFE (polytetrafluoroethylene) and silica as main components. The mixture is heated at about 400 ° C. and sintered to adhere it to a substrate such as glass or ceramics. Specifically, DuPont's transparent primer part number 858
It is -500 mag.

The fluorine resin used in the present invention is PTF.
E (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), CTFE (Polychlorotrifluoroethylene), PVdF (polyvinylidene fluoride) and their copolymers are used in the form of powder or dispersion.

FEP is preferably used for the purpose of enhancing the adhesiveness to the glass or ceramic substrate.
In order to obtain sufficient adhesiveness, it is necessary to add at least 20 wt% or more. Although the reason is unknown, sufficient adhesive strength cannot be obtained even if only PFA or PTFE is used on the primer or mixed with the primer without using FEP.
Also, for the purpose of increasing heat resistance, FEP in fluororesin
It is preferable to use PFA or PTFE or a mixture thereof as a fluororesin other than 80 wt% or less.

As a processing method, a transparent primer is applied on a base material, dried and sintered, and then the above resin mixture is applied and dried and sintered.

Considering the characteristics of the material, a multilayer structure may be used. Specifically, the structure is such that the first layer is coated with a transparent primer, the second layer is coated with FEP100% layer having good adhesiveness, and the third layer is coated with PFA or PTFE having good heat resistance or a mixture thereof.

The transparent primer is 20 wt% or more F
You may mix and use in the fluororesin containing EP. That is, room temperature to 400 ° C on a glass or ceramic substrate
It is also effective to coat a transparent primer composed of a fluororesin with silica or a mixture of silica and alumina vitrified by a dehydration condensation reaction below, and a mixture of a fluororesin containing 20 wt% or more FEP in the fluororesin component.

If necessary, carbon black, titanium oxide, mica, colored mica, conductive filler, etc. may be mixed and used in the resin.

[0019]

EXAMPLES Examples of the present invention will be described below. Examples 1 to 4 and Comparative Examples 1 to 3 Sheet glass (float glass made by Central Glass: see Table 1) was strengthened, and the surface was thoroughly degreased with MEK (methyl ethyl ketone) and then used as the first layer.
The primer shown in (1) was applied to a thickness of about 7 μm, dried at 150 ° C. for about 10 minutes, and then sintered at 400 ° C. for 20 minutes. An average of about 3.5μ of primer layer was obtained.

Thereafter, as a second layer, the resin composition shown in Table 2 was applied to about 20 μm, dried at 150 ° C. for about 10 minutes, and then the resin was sintered at 400 ° C. for 20 minutes. An average coating film of about 10μ was obtained.

The obtained fluoropolymer coating was subjected to an initial evaluation of the adhesive strength, transparency, contact angle with water between the glass substrate and the coating film, and evaluation after the heat aging test. The results are shown in Table 2. The evaluation method is as follows.

(Peeling strength) A commercially available FEP sheet was heat-sealed on the surface of a coating film, and then peeled in a direction of 180 ° with a width of 1 cm, and the peeling force at that time was measured by peeling strength (unit: kg / c).
m).

(Cross-cut test) JIS on the coating surface
Make a grid 100 stipulated in K 5400-1990.8.5.2, make a cellotape (Nichiban Co., Ltd.) sufficiently adhere to this surface, and immediately peel it off. This peeling is performed 40 times with a new cellophane tape, and 100 pieces of the tape are evaluated to evaluate how much remains.

(Visible light transmittance) 400 to 700 using a UV / visible spectrophotometer (U-3400 manufactured by Hitachi, Ltd.)
Ratio of integral values of visible light transmittance of nm (1
00%. ) Is the visible light transmittance. The transmittance of the glass plate used as the base material was 90%.

(Contact angle to water) Using a contact angle meter manufactured by Kyowa Interface Science Co., Ltd., the contact angle to water with respect to pure water is determined by the droplet method.

(Presence or absence of cracks) When cracks that could be visually confirmed were generated, it was judged that there were cracks.

(Comprehensive Evaluation) The practical adhesive strength is about 0.
Adhesive strength of 5 kg / cm or more, 80/100 in a cross-cut test
Is estimated to be necessary, and the visible light transmissivity at a film thickness of about 10 μm, which is estimated to be the minimum required, is subjected to a sensitivity test (1 year old boy, 1 year old boy, 1 year old boy, 1 person, Approximately 50% or more of the 40-year-old boys and 1 20-year-old female 3) were considered to have good see-through property, and cracks could not be visually confirmed.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

As described above, according to the present invention, water repellency and non-adhesiveness are imparted to the glass surface without significantly deteriorating the transparency of the glass substrate, and strong adhesion and heat resistance are provided. Since it is possible to obtain a coating having, it is possible to use glass frying pans, glass pots, kitchen supplies such as window materials such as microwave ovens and oven toasters, home appliances, office equipment such as copier toner boxes, telephone box window materials, Building materials such as high-rise building windows, automobile side mirrors, automobile traffic safety equipment such as mirrors installed at intersections, clad or coating of optical fiber cables, water repellency or non-adhesiveness,
It can be applied to a wide range of fields where adhesion or heat resistance is required. Needless to say, the present invention can be effectively applied to applications in which transparency is not particularly important, such as coating on ceramics or glass cloth.

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Claims (1)

[Claims] 1. A glass or ceramic substrate,
A transparent primer layer consisting of a fluororesin and silica or a mixture of silica and alumina that vitrifies at room temperature to 400 ° C or less by a dehydration condensation reaction is coated, and a fluororesin coating layer containing 20 wt% or more of FEP in the fluororesin component is coated thereon. A fluororesin coating characterized by being coated.