KR20050089963A - System of layers for transparent substrates and coated substrate - Google Patents

Abstract

The invention relates to a system of layers for coating the surface of transparent substrates, in particular, a system of layers with low emissivity (Low-E) for glass windows, comprising at least one layer of mixed oxides produced by reactive cathodic sputtering from a metallic target alloy. The mixed oxide layer comprises ZnO, Ti02 and at least one of the oxides Al203, Ga203 and Sb203 and finds application as upper and/or lower anti-reflection layer, partial layer of an anti-reflecting layer and/or a final finishing layer. Said system of layers is characterised by a high degree of hardness and excellent resistance to the maritime climate.

Description

Layer system and coated substrate for transparent substrates {SYSTEM OF LAYERS FOR TRANSPARENT SUBSTRATES AND COATED SUBSTRATE}

FIELD OF THE INVENTION The present invention relates to a multilayer system for transparent substrates, in particular glass glazing, comprising at least one layer of a mixed oxide made of ZnO and TiO ₂ produced by reaction sputtering from a metal target alloy and at least one additional metal oxide Has

Multilayer systems for panes or other transparent substrates generally have one or more silver layers, with a top layer and a bottom antireflective layer made of metal oxide, by means of a functional layer. Between the antireflective layer and the silver layer or silver layers, there may be one or more additional layers, which promote the construction of the silver layer and / or prevent the destructive elements from diffusing into the silver layer. With regard to multilayer systems, these multilayer systems may be low emissivity (low E) multilayer systems with thermal insulation and / or systems of this kind with sun protection. Low emissivity systems are medium color systems with high light transmission and high transmission of sunlight heat to save energy in the structure. In industrial manufacturing, multilayer systems are used using magnetically enhanced sputtering techniques.

During transport and storage, the surface layers are exposed to mechanical stress and, among other things, in countries with a marine climate, these surface layers are also exposed to aggressive chemical stress. In order to improve the mechanical and chemical resistance capability of the multilayer system, one or more oxide layers, in particular a top antireflective layer or a partial layer of the top antireflective layer, in particular a top coating, means a mixed oxide layer, meaning a layer made of one or more oxide Manufacturing in form is a known practice. In this way, the hardness and chemical resistance of the multilayer system can be improved.

Multilayer systems with mixed oxide layers of the kind specified at the outset are known from document EP-B1-0 304 234. In this case, the mixed oxide layer consists of at least two metal oxides, one of which is an oxide of Ti, Zr or Hf, and the other is an oxide of Zn, Sn, In or Bi. The mixed oxide layer can in this case be produced via simultaneous sputtering from several different metal targets or target alloys containing two metals.

The two sublayers, the double upper sublayer, consist of a mixed oxide mainly composed of zinc and aluminum, and in particular, a spinel structure of ZnAl ₂ O ₄ type to improve mechanical resistance and chemical resistance. A method for producing two sublayers is known from document EP-A1-0 922 681.

Document DE-C1-198 48 751 describes a multilayer system having a mixed oxide layer, which comprises 35 to 70 wt.% Zn and 29 to 64.5 wt.% Sn, based on the total proportion of metal. And at least one element of elements Al, Ga, In, B, Y, La, Ge, Si, As, Sb, Bi, Ce, Ti, Zr, Nb and Ta, which is 0.5 to 6.5% by weight.

Document US-A-4,996,105 describes a multilayer system with a mixed oxide layer of composition Sn _1-x Zn _x O _y . The mixed oxide layer is prepared by sputtering of a stoichiometric zinc tin alloy with a Zn: Sn ratio of 1.1 atomic percent.

Documents EP-A1-0 464 789 and EP-A1-0 751 099 also describe multilayer systems with antireflective layers made of mixed oxides. In this case, the mixed oxide layer containing ZnO or SnO as the main component contains the addition of Sn, Al, Cr, Ti, Si, B, Mg or Ga.

The multilayer described in document EP-A1-0 593 883, in which the upper antireflective layer is in the form of a triple nonmetallic layer consisting of two zinc oxide layers, in turn one titanium oxide layer arranged between the two sputtered layers. The system also belongs to the prior art. The triple layer can be covered with an additional top coating of titanium oxide. The inventor of this patent assumes that during deposition of the coating, a zinc titanate layer is formed between the zinc oxide layer and the titanium oxide layer, so that the zinc titanate layer is present in an area of less than nanometers and protects against environmental influences. To strengthen. However, from an analytical point of view, it is impossible to detect an intermediate zinc titanate layer for such a multilayer system.

For industrial coating facilities, there are difficulties associated with sputtering zinc titanate layers from Zn-Ti target alloys. Very particularly, at the start of the sputtering process, an insulating deposit from the electrical point of view actually occurs in the target and in the part of the sputtering chamber in the case of this material, which results in the formation of a defective product which results in some scraping during manufacture. It works.

An object of the present invention is to provide a multilayer system having at least one layer of a mixed oxide consisting of ZnO and TiO ₂ , on the other hand, in terms of their hardness and chemical resistance, on the other hand, during the process of sputtering a Zn-Ti alloy. In order to prevent the difficulties that occur, it is to further improve.

This object is achieved according to the invention by the features of claim 1.

In the multilayer system according to the invention, the functional layer is in particular a metallic layer, selected from silver, gold, platinum, advantageously selected from silver.

The thickness of the mixed oxide layer made in accordance with the invention is 2 to 20 nm and can be located anywhere in theory, in a multilayer system. However, with the partial layer of the upper antireflective layer, this forms approximately the actual top coating of the multilayer system. Lower antireflective layers and other sublayers of the upper antireflective layer may, for example, consist of SnO ₂ , ZnO, TiO ₂ and / or Bi ₂ O ₃ .

In one preferred embodiment of the invention, ZnO and TiO ₂ are present in the mixed oxide layer in a molar ratio of about 1: 1 to 2: 1, in particular in a molar ratio of 1: 1 or 2: 1, which is ZnTiO ₃ or Zn ₂ Means any one of TiO ₄ . The ratio of oxides Al ₂ O ₃ , Ga ₂ O ₃ and / or Sb ₂ O _{3 in} the mixed oxide layer is preferably 0.5 to 8% by weight.

The target alloy from which a mixed oxide layer of this kind can be produced thus represents at least one of metals Al, Ga and Sb, which is 90 to 40% by weight of Zn, 10 to 60% by weight of Ti and 0.5 to 8% by weight. .

In addition, one subject of the invention is a transparent substrate coated with a multilayer system as described above. The substrate is advantageously made of panes of at least one sheet of glass or plastic.

In the following, three comparative examples of a multilayer system with mixed oxide layers prepared according to the prior art are provided for comparison with the illustrative examples according to the invention. The multilayer system in this case has the same layer order for all examples, in which case the mixed oxide layer forms the top coating.

To evaluate the properties of the layers, eight different tests were performed in all examples. These tests are as follows.

1. scratch resistance test

In this example, the needle with weights is layered at a defined speed. This weight, which makes the scratches visible, provides a measure of hardness in terms of scratches.

2. Taber test

The layer is stressed using a friction roller of defined roughness, under a defined application pressure, and for a predetermined number of revolutions. The attacked layer was evaluated microscopically. The portion of the layer that is not broken appears in a%.

3.Erichsen washing test according to ASTM 2486

Visual assessment of scratches after 1000 trips

4. Condensation resistance test according to DIN 50021

Visual assessment of the change on the floor after 240 hours

5. Diffraction Light Measurement

After the condensation resistance test, a Gardner measuring device was used to measure the diffracted light to measure the proportion of the diffracted light generated by the change to the layer. The proportion of the diffracted light is shown as a%.

6. EMK test

This test is described in the publication Z. Silikattechnk 32 (1981), page 216. This test provides a measure of the passivation quality of the top coating on top of the silver layer and the corrosion behavior of the Ag layer. The smaller the preposition (mV) between the multilayer system and the reference electrode, the better the layer quality.

7.Salt fog test according to DIN 500021

Visual assessment of floor changes.

8. Environmental testing according to DIN 52344

Visual assessment of floor changes.

Next, these tests will be called these numbers.

(Comparative Example 1)

4 mm following the thickness of the float, in the prior art to the glass panes following layer sequence, that is a glass _{- 20nm SnO 2 - 17nm ZnO -} 11nm Ag - 2nm CrNi - 38nm SnO 2 - 2nm Zn x Sn y Sb z O n multi-layer system having An industrial scale continuous magnetron installation was used to attach the.

The mixed oxide layer forming the top coating was obtained from a metal target having a composition of 68% by weight Zn, 30% by weight Sn, 2% by weight Sb, via sputtering according to document DE-C1-198 48 751. / O ₂ working gas was applied in the atmosphere.

Tests 1-8 run on this multilayer system provided the following results.

1.30-175g

2. 87%

3. 11 small scratches

4. Red spot

5. 0.23%

6. 111 mV

7. 24 hours after spot defect

8. Matt area after 24 hours

(Comparative Example 2)

In 4 mm thick float glass panes, the same coating equipment is used to deposit the same order of layers, the only difference being that the top coating of the mixed oxides is replaced by stoichiometrically mixed oxides, which is described in document EP. Sputtering according to -A1-0 922 681 was applied from a target metal alloy having a composition of 55% by weight of Zn, 45% by weight of Al. The order of these layers is as follows.

Glass _{- 20nm SnO 2 - 17nm ZnO -} 11nm Ag - 2nm CrNi - 38nm SnO 2 - 3nm ZnAl 2 O 4.

This test provided the next floor evaluation.

1.49-119 g

2. 83-90%

3. No scratch

4. single spot defect

5. 0.26%

6. 190 mV

7. 24 hours after spot defect

8. 24 hours after corrosion spot

(Comparative Example 3)

For the same layer structure theoretically as in the previous examples, a top coating of a mixed oxide of ZnO and TiO ₂ was applied, wherein the layer of mixed oxide contained 3 atomic% Ti relative to its total metal content. Top coatings of this kind are described in document EP-A1-0 751 099. The top coating was applied from a target having a composition of 97 atomic percent Zn and 3 atomic percent Ti using the same sputtering equipment in an Ar / O ₂ working gas reaction atmosphere, with a mixed oxide of quantitative composition ZnO / Zn ₂ TiO ₄ . It became a nonstoichiometric layer of. The multilayer system had the following structure.

Glass - SnO ₂ 20nm - 17nm ZnO - Ag 11nm - CrNi 2nm - 38nm SnO ₂ - 3nm ZnO / Zn ₂ Ti ₄ O _2.

During the deposition of the layer in the reactive sputtering operation, a substantial problem occurred after working with this target material for about two days in the corresponding sputtering chamber, which meant that the process had to be stopped.

This multilayer system had the following characteristics.

1.112-193 g

2. 90-91%

3. 2 medium scratches and 10 small scratches

4. Red spot

5. 0.33%

6. 130 mV

7. 24 hours after spot defect

8. 24 hours after corrosion spot

(Example Embodiment)

As in the comparative example, the layer according to the invention was applied to the layers in the same order by sputtering, with a top coating. This was done from a target having a composition of 71 wt% Zn, 27 wt% Ti, 2 wt% Al.

For a 70:30 Ar / O ₂ ratio in the working gas, it was possible to deposit a basically stoichiometric Zn ₂ TiO ₄ layer with high surface smoothness. The sputtering problem was performed without any problem. The multilayer system had the following structure.

Glass _{- 20nm SnO 2 - 17nm ZnO -} 11nm Ag - 2nm CrNi - 38nm SnO 2 - 3nm Zn 2 TiO 4: Al.

This test showed the following characteristics for the multilayer system.

1.136-241g

2.91-92%

3. 1 medium scratch and 3 small scratches

4. No defect after 360 hours

5. 0.25%

6. 60 mV

7. No defect after 48 hours, first defect after 55 hours

8. No defect after 24 hours, first defect after 48 hours

The following table summarizes the test results of the four examples once more to provide an overview.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Scratch test 30-175 g 49-119 g 112-193 g 136-241 g Taber test 87% 83-90% 90-91% 91-92% Ericsen washing test 11 small scratches No scratch 2 medium scratches and 10 small scratches 1 medium scratch and 3 small scratches Condensation Resistance Test Red spots One spot defect Red spots 360 hours no defect Diffracted light measurement 0.23% 0.26% 0.33% 0.25% EMK test 111 mV 190 mV 130 mV 60 mV Salt fog test 24 hour late spot defect 24 hour late spot defect 24 hour late spot defect 55 hours after the first defect Climate change test 24 hours after matte area 24 hours corrosion point 24 hours corrosion point 48 hours after the first defect

Compared with the results of the example according to the prior art, the layer of mixed oxides Zn ₂ TiO ₄ : Al in a multilayer system exhibits the following distinguishing properties.

Sputtering can be performed without any problem.

-The hardness of the layer is large.

-Excellent electrochemical passivation

High resistance to moisture and electrolytes, for example NaCl solutions, which may lead to the conclusion that there is a very good resistance to the marine environment.

The series of examples should not be construed as having limited properties, and the good results are also seen as mixed oxide layers in which aluminum is replaced by gallium or antimony, or compounds of these elements, which layer is to the right of the multilayer system surface. It may be located at or on an inner or adjacent layer.

As described above, the present invention sputters Zn-Ti alloys on the other hand, with a multilayer system having at least one layer of mixed oxides consisting of ZnO and TiO ₂ , on the other hand, for their hardness and chemical resistance. It is used to further improve in order to prevent difficulties occurring during the process.

Claims (12)

As a multilayer system for transparent substrates, in particular glass panes, A multilayer, comprising at least one functional layer and at least one layer of a mixed oxide made of ZnO and TiO ₂ and at least one additional oxide, produced via reactive sputtering from a metal target alloy In the system, Wherein the additional oxide is Al ₂ O ₃ , Ga ₂ O ₃ and / or Sb ₂ O ₃ . The multilayer system of claim 1, wherein ZnO and TiO ₂ are present in the mixed oxide in a molar ratio of about 1: 1 to 2: 1. The multilayer system of claim 2, wherein ZnO and TiO ₂ are present in the mixed oxides in essentially molar ratios of 1: 1 or 2: 1. 4. The proportion of the oxides Al ₂ O ₃ , Ga ₂ O ₃ and / or Sb ₂ O ₃ in the mixed oxide layer is 0.5 to 8% by weight. Multilayer system. 5. The multilayer system according to claim 1, wherein the thickness of the mixed oxide layer is 2 to 20 nm. 6. 6. The mixed oxide layer of claim 1, wherein the mixed oxide layer is a lower and / or upper antireflective layer of a low emissivity (low E) multilayer system representing one or more functional layers made of silver. Multilayer system made. 6. The mixed oxide layer of claim 1, wherein the mixed oxide layer is a partial layer of the upper and / or lower antireflective layer of a low emissivity multilayer system representing one or more functional layers made of silver. Multilayer system made. 8. The multilayer system according to claim 1, characterized by the layer structure of the substrate-SnO ₂ -ZnO-Ag-CrNi-SnO ₂ -Zn ₂ TiO ₄ : Al. 9. The metal Al, Ga and Sb of claim 1, wherein the mixed oxide layer is 90 to 40 wt% Zn, 10 to 60 wt% Ti and 0.5 to 8 wt%. A multi-layer system, characterized in that it is made from a metal target alloy containing one or more. 10. The multilayer system of claim 9, wherein the target alloy for making the mixed oxide layer contains 71 wt% Zn, 27 wt% Ti, and 2 wt% Al. 10. The multilayer system of claim 9, wherein the target alloy for making the mixed oxide layer contains 56 weight percent Zn, 42 weight percent Ti and 2 weight percent Al. Transparent substrates, in particular such as windowpanes, coated with the multilayer system as claimed in claim 1,