VERRE TEXTURE POUR SERRE

TEXTURE GLASS GREENHOUSE

The invention relates to the field of glass with high transparency and scattering, especially for greenhouses.

Currently, non-textured glass surface planes are mostly used for greenhouses for horticultural purposes. In recent years, textured glazing whose texture is obtained by rolling emerged for this application. These textured glass scatter light, which has a positive impact on horticultural production. Indeed, the diffusion effect prevents hot spots on plants and provides better light penetration in all areas of the greenhouse and provides a more uniform lighting. However, these glasses have a lower transmission compared to the same non-textured glass, which has a negative impact on horticultural production. The high transmission searched for such glazing is the so-called hemispheric transmission (TLH, sometimes denoted T _H EM), that is to say the transmission averaged over several angles of incidence. For each angle of incidence, measuring all the light intensity passing through the glazing unit regardless of the angle of emergence. A glazing for greenhouses preferably has a high TLH and a blur (as determined by the value of Haze, said H) high. The Haze is the ratio of the diffuse transmission and total transmission of the glazing. The hemispherical transmission is an essential feature of this type of glazing and it is generally not desired that the glazing lose more than 5% and preferably not more than 3% of TLH because of its diffusing texture compared to a flat glass non-textured of the same nature and basis weight. A gain or a loss of 1% of TLH is already very sensitive. For Haze, a significant change is more in the order of 10%.

Photovoltaic glazing, such as those sold under the brand S-Albarino Albarino-T and Saint-Gobain can significantly get this type of behavior. However, for Albarino-S, H is high but the TLH is degraded with respect to a flat glass of the same kind, and for Albarino-T, TLH remains at a high level close to that of a glass similar smooth, but the H is too low. Although they represent some improvement over a non-textured glass, these glasses are not ideals. The WO03046617 teaches a textured plate by use photovoltaic pyramids. The Albarino-P sold by Saint-Gobain has a structure of this type. The faces of the pyramids have a slope approaching 45 °, but due to roundings made unintentionally in practice, the texture of this glass was actually an average gradient of about 30 ° to the general plane of the glazing. If such a texture leads to a high H, the TLH is however not sufficient. The invention provides a better compromise of these two properties TLH and H compared to textured glazing known.

The WO2015 / 032618 teaches a textured glass sheet comprising a first face provided with a first texturing and a second face having a second texturing, and a set comprising such a glass sheet and at least one element for use solar radiation disposed beneath the glass sheet.

The invention firstly relates to a transparent sheet comprising an embossed texture on a first of its main faces, such that if n is the refractive index of the material comprising the texture, P _m is the mean slope degree of the face textured Y (q) is the percentage of the textured surface slope greater than q / (n-1) degree, then we have the two cumulative conditions on Y (q):

Y (q)> 3% + f (q)%. P _m. (N-1)

and Y (q)> 10%

with f (q) = 24- (3.q) and q = 2 or 3.

Preferably Y (q)> 5% + f (q)%. P _m. (N-1). More preferably, Y (q)> 10% + f (q)%. P _m. (N-1). Preferably f (q) = 27- (3.q) and even f (q) = 30- (3.q).

Notably, one of eight combinations is particularly suitable:

- Y (q)> 5% + f (q)% P _m (n-1) with f (q) = 27- (3.q) and q = 2;.. or

- Y (q)> 5% + f (q)% P _m (n-1) with f (q) = 27- (3.q) and q = 3;.. or

- Y (q)> 5% + f (q)% P _m (n-1) with f (q) = 30- (3.q) and q = 2;.. or

- Y (q)> 5% + f (q)% P _m (n-1) with f (q) = 30- (3.q) and q = 3;.. or

- Y (q)> 10% + f (q)% P _m (n-1) with f (q) = 27- (3.q) and q = 2;.. or

- Y (q)> 10% + f (q)% P _m (n-1) with f (q) = 27- (3.q) and q = 3;.. or

- Y (q)> 10% + f (q)% P _m (n-1) with f (q) = 30- (3.q) and q = 2;.. or

- Y (q)> 10% + f (q)% P _m (n-1) with f (q) = 30- (3.q) and q = 3... As part of this application and especially in the examples, the TLH and haze are measured using the methods detailed in "Proc 7th IS is light in Horticultural Systems, Eds: S. and E. Hemming Heuvelink Acta Hort.956, ISHS 2012 ". In this document, mention is made of a Haze measured at 1 5 °. But in the field of transparent materials, the Haze is often measured at 2.5 °. A standard has not yet fully asserted in the field of greenhouses for horticulture, although the haze at 1, 5 degree is now more used. According to the invention, is introduced f (q) to take account of these two ways of measuring the Haze. To maximize a Haze at 1, 5 ° while keeping a very good compromise with TLH, we take q = 2 while maximizing a Haze 2.5 ° while keeping a very good compromise with TLH, we take q = 3.

According to the invention, a glazing unit having a distribution of slopes comprising relatively few areas with very small slope and few high slope zones and including the distribution of slopes is close to q / (n-1) °, q = 2 or 3, that is to say close to 4 ° for q = 2 and close to 6 ° for q = 3 for the index glass 1, 5. With this geometry, we get a much better combination of TLH values ​​and H.

The relief texture can be made of a material of the organic or inorganic type glass. In particular, it may be an inorganic glass comprising at least 40 wt% S1O2.

The refractive index of the material comprising the texture is generally in the range of 1, 4-1, 65 to 587nm.

The sheet is very absorbent in the spectral range of photosynthesis (400-700 nm) and it is the same for all material included in the sheet. The absorption of the sheet according to the invention in this spectral range is less than 2% and preferably less than 1% and even less than 0.5%. Absorption is obtained by measuring the transmission and reflection at normal incidence and by the relation Absorption (%) = 100% - transmission (%) - reflectance (%). Measurements of transmission and reflection (block and measured using an integrating sphere) are made using a spectrophotometer and are an average of the transmission and reflection values ​​for the wavelengths of area 400-700 nm.

The slope at a point on the surface of a sheet corresponds to the angle formed between the tangent plane at this point and the general plane of the sheet. Measuring the slope at a point is made of the extent of the variation in height in the vicinity of that point and the general plane of the sheet. The skilled person knows the devices capable of performing such measurements of height. Measuring the average percentage P _m of the surface is determined from the measured slopes at points spaced on a square grid period 20 pm. then calculated the average of the slope of these points.

Preferably, the texture comprises relatively large designs because it allows better control of the slopes actually created by rolling. Indeed, it is in practice very difficult to get rolling texture to the slopes when the controlled period of the units is less than 1 mm, particularly in a mineral glass. The rolling process necessarily produces unwanted curves and rounded to the uncontrolled slopes occupy the more area than the base pattern is small in size. By enlarging the pattern, the same rounded occupies a smaller fraction of the total period of the pattern and thus a lower impact.

For rolling a texture close to that desired, is preferably carried out on grounds of which the size is at least 1 mm and preferably at least 1, 5 mm and even preferably at least 2 mm and even preferably at least 2.5 mm (size means the diameter of the smallest circle containing the pattern). Preferably, the units have a size of at most 8 mm. Preferably the patterns are contiguous.

It is recalled that the Rs _m (average or not average period) of a profile (that is to say along a line segment) of a surface is defined by the relation:

wherein Si is the distance between two zero crossings (midline) and amounts, n + 1 being the number of zero crossing in amount in the particular profile. This parameter Rs _m represents the distance between peaks, that is to say not the texture parallel to the general plane of the sheet. The values of Rs _m are data after using Gaussian filters with cuts (or base length, cut-off English) 25 μηη and 8 mm (deletion periods of less than 25 μιτι and greater than 8 mm). Measurements of R _sm are based on a distance of at least 40 mm. For any point of the textured surface, the R _sm around said point corresponds to the arithmetic mean of R _sm for 10 profiles starting star from the considered point. For the calculation of R _sm about a point is removed greater than or equal to 40 mm values. This avoids taking into account the profiles in some specific guidelines textures such as prisms or parallel straight lines between aligned pyramids (R value _sm infinite or non-computable). We also define a R _sm means of a textured surface by calculating the arithmetic mean of R _sm about a point, the points are selected on a square grid with a pitch of 5 cm.

Preferably, the R _sm using the textured surface is comprised within the range of from 1 mm to 8 mm and preferably in the range from 1, 5 to 8 mm and even in the range of 2 mm to 8 mm and even in the range of 2.5 mm to 8 mm. More preferably, the R _sm around any point with a textured surface is in the range of 1 mm to 8 mm and preferably in the range from 1, 5 to 8 mm and even in the range of 2 mm to 8 mm and even in the range of 2.5 mm to 8 mm.

The slopes formed on an inorganic glass by hot rolling, generally in a temperature range from 800 to 1300 ° C, decreasing slightly during forming. Thus, when aiming at the glass sheet an average slope value P _m, preferably using a printing roller whose patterns have an average slope of at least P _m + 0,5 °, or even at least _m + 1 P °. More patterns of texture are big (R _sm highest average) plus the actually printed texture is close to that of the roller and text it is necessary to make a correction on the grounds of the roller.

Thus, for a R _sm average between 1 and 1, 5 mm, the average slope of the roll texture can be increased from 0.5 ° to 10 ° relative to the average slope of the desired texture. To R _sm average between 1, 5 and 2 mm, the average slope of the roll texture can be increased by 0.5 ° to 8 ° relative to the average slope of the desired texture. To R _sm average between 2 and 2.5 mm, the average slope of the roll texture can be increased from 0.5 ° to 6 ° relative to the average slope of the desired texture. To R _sm average greater than 2.5 mm, the average slope of the roll texture can be increased from 0.5 ° to 5 ° relative to the average slope of the desired texture. The grounds of the texture can be parallel linear patterns like parallel prisms or patterns that can be fit into a circle as cones or pyramids.

The invention is useful for glazing office letting light greenhouses for horticulture, and for other applications requiring high TLH and a strong H as a porch, a foyer, a public space.

According to the invention, the two main sides of the sheet may be textured. In this case, if the texture of one of the two sides is not according to the invention, then preferably, the texture of the invention is that the two sides whose average slope is strongest. Within the high average slope face is preferably such that P _m '.2. (N'-1) is less than 3 °, and even less than 2 °, P _m' and n 'being the average slope and respectively the refractive index of the material comprising the texture of the face less high average slope.

The invention also relates to a sheet P _m (n-1) greater than Pm -. (N'-1), P _m and P _m representing the average percentage respectively of the first and second main face and n and n ' being the refractive index of the material comprising the texture of respectively the first and the second main face. Preferably, the texture of the second main face having a mean slope such that P _m '.2. (N'-1) is less than 3 °, and even less than 2 °. Preferably, if Y '(q) is the percentage of the textured surface slope greater than q / (n'-1) degree of the second main face, then there is the relationship

Y '(q)> 3% + f (q)%. P _m. (N'-1)

with f (q) = 24- (3.q)

and q equal to 2 for both for Y (q) and Y '(q), q being 3 or so for both for Y (q) and Y' (q).

In particular, both sides of the sheet may be according to the invention.

An antireflection effect can be obtained on one or both sides of the sheet, and in particular on the textured face. This antireflection effect can be obtained by depositing a layer or several layers forming a stack, etching or any other suitable technique. The antireflection effect is selected to be effective at wavelengths 400-700 nm. An anti-reflection coating (or layer anti-reflective stack of anti-reflection effect with coatings) generally has a thickness in the range of 10 to 500 nm.

The sheet may be carried out in a completely monolithic material. The sheet may also be made of a monolithic material which has optionally been affixed an antireflection layer or a stack of anti-reflection effect in layers on one of its faces or on both sides. However, the texture may be performed in a first relatively thin material comprising texture and associated in the sheet to a second material providing rigidity to the entire sheet. this first material that should be present in a minimum thickness for achieving the relief patterns. Preferably the difference in refractive indices of the two materials does not exceed 0.2 and more preferably does not exceed 0.1. It is in this case a combination of several materials when performing texture by embossing a sol-gel film deposited on a transparent sheet, especially glass. Thus, the texture can be achieved by a first add-on material on a sheet of a second material. The sheet may also include more than two materials.

Preferably, two juxtaposed materials in the sheet have refractive indices whose difference does not exceed 0.2 and preferably does not exceed 0.1. This preference relates to the juxtaposition within the sheet materials present both more than 500 nm from the surface of the sheet, the surface of the sheet being in contact with the ambient air. A material present at more than 500 nm from the surface of the sheet may also be present on the surface of the sheet, its thickness being greater then 500 nm. The presence of more than 500 nm from the material surface is determined orthogonally with respect to the actual surface, which follows the texture, and not in relation to the general plane of the sheet. This preference on the difference in refractive indices, therefore does not concern an antireflection film (antireflection layer or antireflection coating) which is in contact with ambient air and is generally made of materials with fairly distant refractive indices of the on which it is deposited, and less than 500 nm thick. An antiglare layer or an antireflection stack are thin coatings does not modify the texture in relief to which they are applied. They follow the relief surface. That is why it can be said that anti-reflective surface coating (or layer stack of layers) in contact with ambient air, is not the material comprising the texture according to the invention.

The material comprising the texture according to the invention is of sufficient thickness to impart alone to the surface texture. It may be coated with an antireflection film (antireflection layer or antireflection effect to stack) but this coating follows the relief given surface by the material comprising the texture. Thus, the material comprising the texture according to the invention is of sufficient thickness to constitute more than 90% and preferably more than 95% by volume of the material contained between two planes parallel to the general plane of the sheet and one of which passes by the outermost point of the texture in contact with the ambient air and the other of which passes through the innermost point of the texture in contact with the ambient air. In practice, it is this material that the texture is imparted by a tool comprising the same or inverted by etching terrain. The material comprising the texture is thicker than 5 μιτι in a direction orthogonal to the actual surface (which follows the surface texture), and thickness greater than 5 μιτι in a direction orthogonal to the general plane of the sheet.

If the texture according to the invention does not comprise at its surface layer or antireflection stack, while the material comprising the texture according to the invention is in contact with the ambient air. If the texture according to the invention comprises at its surface a layer or an anti-reflection stack, then this is the layer or the stack which is in contact with ambient air.

Texture in a monolithic material, in particular glass, can generally be accomplished by embossing or laminating with at least one textured roller, or by acid etching. The textured glass sheet obtained may be coated with an antireflection coating.

If the sheet of the invention comprises a glass sheet, the latter is preferably thermally soaked. To do this, and if an antireflection coating must be applied to him, mention may do so:

- glass lamination to its softening temperature by at least one textured roller leading to a textured glass sheet, and

- cooling and then,

- application on one or both sides of the textured film of one or more layer (s) precursor sol-gel anti-reflective coating and then - heating of the textured coated sheet, followed by cooling of thermal tempering; heating is used both to raise the glass temperature to the tempering cooling, but also cooking the sol-gel coating.

Figure 1 shows the textured side of a glass sheet according to the invention, obtained by rolling, and according to Example 1. The texture of a main face comprises pyramids with bases irregular hollow and contiguous. The degree of gray reflects the depth of the points on the surface, the darker areas being deeper. In each of Figures 1 to 3, the lightest points are at the same height and the darkest points are at the same height. The depth of the reasons is the difference in height orthogonally to the general plane of the plate between the brightest and the darkest point points.

Figure 2 shows the textured side of a glass sheet according to the invention, obtained by rolling, and according to Example 2. The texture of a main face comprises pyramids with bases irregular hollow and contiguous. The pyramids are smaller than in the case of Figure 1, so that unintentionally rounded areas are more important. These rounded areas do not necessarily have the desired slope.

Figure 3 shows the textured side of a glass sheet according to the invention, obtained by rolling, and according to Example 3. The texture of a main face comprises pyramids with bases irregular hollow and contiguous. The pyramids are smaller than in the case of Figures 1 and 2, so that unintentionally rounded areas are more important. These rounded areas do not necessarily have the desired slope.

Figure 4 shows the most heavily textured face of a sheet of Albarino- S seen from above in a) and side view b). Of course the reasons in b) are not to scale. It is shown here that the patterns are bumps uniformly distributed on the surface.

By Figure 5 illustrates the impact of a change in size of pyramidal features (and thus a change of R _sm). The two textures in a) and b) have in fact the same rounded with the same radius of curvature at the vertices and patterns hollow. That is what is obtained in practice by glass rolling with a textured roller having at its pyramids without rounded surface at the peaks and patterns hollow. The texture larger in a) has a closer texture ideal texture because it has the largest areas of suitable slope. The areas marked "z" are suitable slope.

6 shows in the case of q = 2 how the invention differs from the prior art by the line Y = X, with X = 3% + 18% .P _m. (N-1) for f (q ) = 18% for q = 2. the points in this figure correspond to the examples in table 1. The field of the invention lies above the line, and above a horizontal line Y = 10%.

Figure 7 shows in the case of q = 3 how the invention differs from the prior art by the line Y = X, with X = 3% + 15% .P _m. (N-1) for f (q ) = 15% for q = 3. the points in this figure correspond to examples in table 2. the field of the invention is above this line and above a horizontal line Y = 10%.

8 shows a sheet 70 according to the invention in section in its edge. The textures and thicknesses are not to scale. This sheet 70 is a soda lime silicate mineral glass obtained by rolling between two rollers one of which was textured. The upper face 71 of the sheet has a texture according to the invention with juxtaposed pyramidal features. An anti-reflection layer 72 was deposited on the textured face of the monolithic substrate. The second face 73 of the sheet is flat, without special texture. The material comprising the texture is the material 70 and not the material of the layer 72.

Figure 9 shows a sheet 80 according to the invention in section in its edge. The textures and thicknesses are not to scale. This sheet 80 is a soda lime silicate mineral glass obtained by rolling between two rolls, both textured. The upper face 81 of the sheet has a texture according to the invention with juxtaposed pyramidal features. The second face 82 of the sheet has a texture (according to the invention or not) with juxtaposed pyramidal features, the average slope of the second face 82 being less than the average slope over the first face 81. This sheet is completely monolithic. His material includes textures of each face.

10 shows a sheet 90 according to the invention in section in its edge. The textures and thicknesses are not to scale. A substrate sheet 91 in silica glass gives rigidity to the whole. The substrate sheet 91 is an inorganic sheet obtained by hot rolling between two textured rollers. The two faces 92 and 93 of the substrate sheet 91 are accordingly textured. We can consider that the substrate sheet 91 is a sheet of Albarino- T. Above the face 92 of the substrate sheet 91 has been carried out a texture 94 according to the invention by embossing a sol-gel layer. The sol-gel material 95 and the material of the substrate sheet 91 have similar refractive indices, the difference in their refractive index not exceeding 0.1. Here, the material comprising the texture according to the invention the sol-gel material 95.

In the following examples, the sheets had a thickness of 4 mm. Was varied the average slope and the% slope greater than q / (n-1) degree, where q is equal to 2 for Examples 1 to 9 and 3 for Examples 10 to 17. The results are reported respectively in tables 2 and 3. the values ​​of Haze were measured at 1, 5 ° for examples 1-9 and 2.5 ° for examples 10 to 18. TLH values ​​are given relative to the flat glass same nature and the same surface weight. So this loss of TLH in%, denoted ATLH relative to flat glass. Indeed, flat glass necessarily has a higher value TLH than textured glasses of the same material. We seek that ATLH the lowest possible.

EXAMPLES 1-9

For Examples 1-4, lamination of the glass sheets is carried out having a main face whose texture is textured repetition pyramidal patterned irregular basis hollow of different sizes as reflected by the value of R _sm. Glazing examples 5 to 9 are commercial and comparative. The textures obtained for Examples 1 to 3 were respectively those shown in Figures 1 to 3, the depth being the height difference between the brightest point and the darkest of these figures. Figure 1 to Figure 3, there is an increase in the proportion of rounded areas that do not correspond exactly to those desired. The texture of Example 4 is similar in plan view to that of Figure 2, the difference being in the depth. Examples 5 to 9 correspond to the measured characteristics of textured glasses marketed under the brands in column 1 of the table. For all the examples, the refractive index of the inorganic glass used was 1, 52. In the table, X is 3% + 18% .P _m. (N-1) for f (q) = 18% for Example No. R _sm average depth Pm n X (%) Y (%) Haze ATLH

(Μηι) (mm) (% at 1.5 °) (%)

1 174 3.6 4 40.44 100 100% 2

2 100 1.8 3.8 38.55 61 75 1.9%

3 100 1.3 4.9 48.9 70 79% 2.5

4 80 1.8 3 31.08 50 60% 1.5

5 (Albarino-S) - 0.8 9.5 91.92 80 85% 5

6 (Albarino-T) - 0.8 2 21.72 15 20% 1

7 (Albarino-P) - 2.5 30 90 95 283.8 15%

8 (Arena C) - 5 49.8 40 50% 2.5

9 (Vetrasol) - 6 59.16 48 56% 3

Table 1

We note that for Example 5 Haze value is good but that TLH is extremely reduced. Regarding example 6, Haze value is extremely low. Examples 7 to 9 do not offer very good property of compromise. Examples 1 to 4 offer excellent compromise of properties in Haze and TLH. This corresponds to the fact that for these examples, Y> X.

EXAMPLES 10-17

For Examples 10 to 12, by lamination of the glass sheets is carried out having a main face whose texture is textured repetition pyramidal patterned irregular basis hollow of different sizes as reflected by the value of R _sm. The windows of Examples 13 to 17 are commercial and comparative. The textures obtained in Examples 10 to 12 are those respectively shown in Figures 1 to 3, the depth being the height difference between the brightest point and the darkest of these figures. These textures are different from those of Examples 1 to 3 by the depth which is deeper here chosen. Examples 13 to 17 correspond to the measured characteristics of textured glasses marketed under the brands in column 1 of Table 2. For all the examples, the refractive index of the mineral glass used was 1, 52. In Table 2, X is 3% + 15% .P _m. (N-1) for f (q) = 15% for q = 3. Example No. Average depth Rsm Pm n X (%) Y (%) Haze ATLH

(Μηι) (mm) (% at 2.5 °) (%)

10 260 3.6 6 49.8 100 100 3%

11 150 1.8 5.7 47.5 61 70% 2.9

12 150 1.3 7.4 60.7 70 75% 3.7

13 (Albarino-S) - 0.8 9.5 77.1 65 75% 5

14 (Albarino-T) - 0.8 2 18.6 8 10% 1

15 (Albarino-P) - 2.5 30 88 92 237.0 15%

16 (Arena C) - 5 42.0 25 30% 2.5

17 (Vetrasol) - 6 49.8 30 32% 3

Table 2

We note that for example 13 the value of Haze is good but the TLH is extremely reduced. As for Example 14, the value of Haze is extremely low. Examples 13 to 17 do not offer very good property of compromise. Examples 10 to 12 provide excellent balance of properties in Haze and TLH. This corresponds to the fact that for these examples, Y> X.