Aqueous composition for coating a substrate with a coating and method of coating

 

(57) Abstract:

Describes aqueous composition for coating in the form of a dispersion comprising perftoruglerodnye resin and a binder containing polyamideimide and polyster, characterized in that as perftoruglerodnaya resin it contains two perftoruglerodnykh polymer, one of which has a melt viscosity that is equal to at least 105Pass, and the second is a melt viscosity equal to 102-107Pas, and the melt viscosity of the first polymer, of at least 102Pass more melt viscosity of the second polymer, when the mass ratio of 50-85% of the first polymer and 15-50% of the second polymer, and the ratio of polyamidation to the polyster that the coating obtained by curing the specified composition, the mass ratio formed of polyamidoimide to the polyster that is equal to 3:1-1:3, and the mass ratio of fluoropolymer to binder in the cured coating is 2:1-1:1. Also describes the substrate with the coating and method of coating. The technical result - the creation of compositions with optimal characteristics, which can be applied to smooth substrates using roll. 4 C. and 9 C.p. f-crystals.

Typically, before applying the first layer of coating a metal substrate makes rough for mechanical adhesion promoted together with chemical adhesive creating a solid coating on the substrate. Typical methods of roughening include acid etching, sandblasting, machining chips and hot drying of rough layer of glass, ceramics or Frit to the substrate (the substrate). The problem of adhesion of non-stick coatings to substrates is decided depending on the nature of the coatings.

If the coating is intended to prevent sticking of food, creating the possibility of easy cleaning residues from food after cooking and must be durable or should contribute to slippage cooked food, difficulties arise with the adhesion of the coating to the substrate.

The substrate can be in the industry, or for the manufacture of products, for example, saw blades made from carbon steel. Regardless of the type of substrate or application, if you want to give the substrate roughness to improve adhesion of the coating, this leads to increased costs and other difficulties, including the creation of an uneven surface, which may act through the floor. This is particularly undesirable when you want a smooth surface, for example, in the case of saws or irons. The use of etching compositions may cause significant harm to the environment.

In the past attempts have been made to create coatings for substrates with a smooth surface damage rolls (see WO 92/10309 from 25.06.1992, and WO 92/10549 from 25.06.1992, in the name of H. P. Tannenbaum). Used parfocality, for example, polytetrafluoroethylene (PTFE) with different viscosities of melts or a mixture of PTFE with a copolymer of tetrafluoroethylene and hexaferrite (FEP) or perfluoroalkyl vinyl ether (PFA), in combination with polyamideimide or polyethersulfone.

With the aim of obtaining optimal results there is a need for further developments.

This invention provides an aqueous coating composition containing perftoruglerodnye resin and SNA resin consists of a mixture of two kinds perftoruglerodnykh resins, one of which has a melt viscosity of at least 105Pass, and the second 102- 107Pas and the melt viscosity of the first resin, at least at the 102Pas is higher than the viscosity of the second resin with the content of these resins: 50-85 wt.% the first resin and 15-50 wt.% the second resin, in this respect Polynicotinate to the polyster that the coating obtained by curing of the composition, the weight ratio formed of polyamidoimide to the polyster is from 3: 1 to 1: 3, preferably from 1.25:1 to 1:1,25, and the weight ratio of fluoropolymer to binder in the cured coating is 2:1 to 1:1. According to a particular variant of the present invention provides a two-layer coating on a substrate, in which the primer is made of a composition of this invention, and the coating of three or more layers with this primer and with an intermediate layer made of the cured aqueous composition for coating, including polyster and polytetrafluoroethylene in a weight ratio of 0.5 to 2.0:6,0.

In both types of coating the upper layer is made from a mixture of PTFE, mica, and Aslamova polymer.

The invention allows not only to reduce costs due to unavailable or is otherwise an advantage when removing food from the cookware and when sliding irons. It also allows you to put on a smooth substrate dispersion of PTFE with the help of the rolls.

Different variants of the invention include the use of a primer, at least two kinds of PTFE with different values of the viscosities of the melt. One such pair is a resin with relatively high and relatively low values of melt viscosity. Another pair contains a resin with a relatively low melt viscosity and resin with even more low viscosity of the melt. As a resin with lower viscosity of the melt can be used tetrafluoroethylene copolymers with fluorinated propylene (FEP) or perfluoroalkyl vinyl ether (PFA).

Adhesion of coatings of fluoropolymers with high melt viscosity to all kinds of metal substrates, in particular metal with a smooth surface, can be greatly enhanced by chemical formation of layers or create a concentration gradient in the primer, which is achieved according to this invention.

Adding perftoruglerodov polymer of low melt viscosity (MV) in the range of 103- 108P (102- 107Pas) and a polymeric binder comprising polyamideimide and polyphenylensulfide becomes more the degree of cure increases, which leads to improved adhesion. Required for this purpose, the curing temperature may change due to selection of fluoropolymer.

Similar effects can be achieved with the use of PTFE with low MV (at least 106P or 105Pas) in combination with PTFE with even lower MV (103-105P or 102- 104Pas). To create a gradient of concentrations of various polymers between the upper and lower coating layer, it is desirable that the difference between the viscosities of the melts of the two PTFE was at least 102P.

The melt viscosity of perftoralkil may be determined by known methods, for example, described in U.S. patent 4636549, Gangal et al (1987), see column 4, lines 25 to 63.

The use of coatings according to this invention on smooth substrates processed only by washing to remove grease and other contaminants that affect adhesion, provides good removal of food and good resistance to wear test described in U.S. patent 425859, Concannon and Vary (1981) No. 2, lines 14-24.

The usual known methods of preparing surfaces to improve the adhesion of coatings include etching and sandblasting or obeya grease and dirt is 16-24 micro inches (0.4 to 0.6 μm). Profile on steel can be in a wider range of values, but usually less than 50 microinches (1,3 µm). On steel and aluminum before applying the adhesive coating profile is usually increased to values larger than 100 microinches (2.5 μm), for aluminum in some cases up to 180-220 muradymov (4,6-5,6 μm). Thus, this invention is especially suitable for steel and aluminum substrates, has a profile of less than 100, preferably less than 50 microinches (less than 2.5 microns, preferably less than 1.3 μm).

Primers according to this invention can also be applied on the substrate, the roughness of which is obtained by a variety of known methods, with the aim of obtaining coatings with improved properties compared to coatings without these primers.

The following examples use the well-known polyamidoimide, colloidal silicon dioxide and dispersion, preferably as described in U.S. patent 4031286, Seymus, (1977) and 4049863, Vassiliou.

In the following examples is improved adhesion. Use the fluoropolymer in the form of 60% of the energy dispersions in water. As usual, the content of solid substances listed in the tables. The compositions have known from the prior art methods and then nanoacquity viscosity used acrylic polyelectrolyte, for example, Acrysol RM-5 (Rohm and Haas).

The following formulations for coatings applied by known techniques, preferably, rollers on the ring disks or even roll method with reverse rotation.

The individual layers are put on each other in the wet state with minimal drying and without layer-by-layer curing, and then the coating system is cured, for example, at 430oC, at least for 1 minute Then two-layer coating can be easily ustanovit, otpraznovat or roll on the surface of the pan with the ratio of depth to diameter of 0.2:1. Three-layer coating can easily roll the pan with the ratio of depth to diameter of 1:1 or to increase the surface to stretch by up to 30% of the diameter of the disk.

Numerous experiments have allowed to establish the intervals of relations performaire glue and ratios of ingredients in the binder is required to obtain the optimal values of resistance to scratching, resistance to etching, flexibility around a tapered core and release properties.

Examples.

Example 1: two-layer system - polyster /polyamidoimide/PTFE/ FEP-primer surface layer of Papalist in combination with an intermediate layer according to example 2 and the surface layer according to example 3, receiving a three-layer coating (see below).

Example 3. The surface layer.

The composition of the resin surface layer is a PTFE in combination with Acrysol RM-5 (see the end of the description).

1. Aqueous composition for coating in the form of a dispersion comprising perftoruglerodnye resin and a binder containing polyamideimide and polyster, characterized in that as perftoruglerodnaya resin it contains two perftoruglerodnykh polymer, one of which has a melt viscosity that is equal to at least 105PA, and the second is a melt viscosity equal to 102- 107PA s, and the melt viscosity of the first polymer, of at least 102PA with more melt viscosity of the second polymer, when the mass ratio of 50 to 85% of the first polymer and 15 to 50% of the second polymer, and the ratio of polyamidation to the polyster that the coating obtained by curing the specified composition, the mass ratio formed of polyamidoimide to the polyster that is equal to 3 : 1 to 1 : 3, and the mass ratio of fluoropolymer to binder in the cured coating, equal to 2 : 1 to 1 : 1.

2. Composition for coating under item 1, characterized in that animer viscosity of the melt, equal to 103- 104PA with.

3. Composition for coating under item 1, characterized in that as perftoruglerodnaya resin it contains a homopolymer of tetrafluoroethylene.

4. Composition for coating under item 1, characterized in that as perftoruglerodnaya resin contains a copolymer of hexaferrite and tetrafluoroethylene.

5. Composition for coating under item 1, characterized in that as perftoruglerodnaya resin contains a copolymer of perfluoroalkyl vinyl ether and tetrafluoroethylene.

6. Composition for coating under item 1, characterized in that the mass ratio of fluoropolymer to binder is equal to 1.75 : 1 - to 1.25 : 1.

7. The substrate with the coating, wherein the coating is double-layered and includes a primer layer deposited on the substrate and a surface layer applied to the primer layer, the primer layer is made of utverzhdenii compositions for coatings under item 1 and the specified surface layer is made of utverzhdenii compositions for coatings containing PTFE, mica, and decomposing the polymer and water.

8. The substrate with the coating, wherein the coating is at least three-layered and includes overhasty layer, deposited on the intermediate layer, the primer layer is made of utverzhdenii compositions for coatings on p. 1 specified intermediate layer is made of utverzhdenii water compositions for coatings containing polyster and polytetrafluoroethylene in a weight ratio of about 0.5 to 2.0 : 6 specified surface layer is made of utverzhdenii compositions for coatings containing fluoropolymer, mica, biodegradable polymer and water at a mass ratio of polymer to decompose the polymer, is 16 : 0,5 - 16 : 1,5.

9. The substrate is coated on p. 8, characterized in that it subjected the hood when the degree of extraction of depth to diameter of approximately 1 : 1, and the mass ratio of polyamidoimide to the polyster in the primer layer is 3 : 1 to 1 : 3.

10. The substrate is coated on p. 7 or 8, characterized in that the coating made from the composition under item 1 and the substrate is cleaned, preventing adhesion of the coating.

11. The substrate is coated on p. 7 or 8, characterized in that the substrate before coating is characterized by an average surface profile comprising less than 1.3 MK.

12. The substrate is coated on p. 7 or 8, characterized in that the layer grunto the polytetrafluoroethylene at the interface between the substrate and the primer layer in comparison with the opposite surface of the partition boundaries and a higher concentration of the mixture of polyamidoimide with polyster at the interface between the substrate and the primer layer, than on the opposite surface of the boundary.

13. The method of applying a coating on a substrate under item 7 or 8, characterized in that the layers of the coating applied to the substrate in the form of a disc without complete drying of one layer before applying another layer, and then coating system utverjdayut when heated, at least at 400oAnd then the disk is subjected to extraction with a degree of extraction of depth to diameter of approximately 1 : 1.

Priority points:

23.12.92 on PP.1 to 7 and 12;

03.11.93 on PP.8 - 11 and 13.

 

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