JP2008540879A - Greenhouse panel - Google Patents

Abstract

  In general, light transmissive panels disclose extruded multi-walled thermoplastic sheet structures having corrugated walls and / or surfaces, particularly for use as greenhouse roofs and wall elements. . The sheet structure has improved durability, excellent heat insulation properties, reduced maintenance requirements, and improved light transmittance.

Description

  The present invention relates generally to light transmissive panels and, in particular, greenhouses with improved durability, good thermal insulation properties, reduced maintenance requirements, and improved light transmission. It relates to panels for use as roof and wall elements.

  Greenhouse cultivation is managed by genuine industry standards for certain agricultural products. The profitability of these cultivations sometimes depends on narrow margins. Thus, the farmer must optimize all the factors, one of which is the amount of sunlight. The increase in brightness inside the greenhouse is a 1% decrease in light, but 1.2% for vegetables, 0.9% for cut flowers, and 0.6% for ornamental plants. It is particularly important in that it is known to correspond. Thus, it would be advantageous to increase the average transparency of such greenhouse wall and roof panels while simultaneously reducing the dimensions of the elements that form the framework that forms the opaque surface.

  Sun rays not only illuminate the interior of the greenhouse, but also warm the interior of the greenhouse. It is desirable for greenhouse walls and roofs to have good thermal insulation properties in order to adequately manage heat losses and increases so that it can be economically warm in winter and cool in summer.

  Another important issue relates to the weather resistance of roof and wall panels. The mechanical properties of the coating material must be able to withstand the weather and maintain itself in all situations. Thus, the combination of coating material and panel design must be able to withstand bad weather conditions such as hail, without being destroyed or otherwise damaged. The roof panel design should also facilitate drainage from rain and melting snow. In addition, the emission of roof panels that collect dust, mud and other particulates is dramatically reduced compared to clean panels.

  Accordingly, it would be desirable to provide a panel for use as a greenhouse roof and wall element that has superior thermal insulation properties, improved durability, reduced maintenance requirements, and improved light transmission.

  The present invention is a greenhouse panel with excellent heat insulation properties, improved durability, reduced maintenance requirements, and improved light transmittance. In one embodiment, the present invention provides an extruded thermoplastic multi-walled sheet structure comprising (i) a thermoplastic polymer, (ii) at least two generally parallel walls. Each wall has a first and second surface, the walls being spaced apart from each other, wherein at least one of the walls has a corrugated shape; A sheet structure having one or more corrugated surfaces, or a combination thereof, (iii) whose walls are separated from each other by ribs that span the length of the sheet in the extrusion direction It is.

  In a further embodiment, the sheet structure of the present invention includes two walls (a first wall and a second wall), each wall having an inner surface and an outer surface, and one or both of the walls are corrugated. It has the shape of

  In a further embodiment, the sheet structure of the present invention comprises two walls (a first wall and a second wall), each wall having an inner surface and an outer surface, one or more of the walls. One or more surfaces are corrugated.

  In a further embodiment, the sheet structure of the present invention has one or more walls having a corrugated structure defined by a sine wave with a pitch of about 0.1 mm to about 50 mm.

  In a further embodiment, the sheet structure of the present invention has one or more walls having one or more corrugated surfaces defined by sinusoidal waves with a pitch of about 0.01 mm to about 10 mm. .

  In a further embodiment, the sheet structure of the present invention comprises a thermoplastic resin, preferably PC, selected from the group of PC, PET, PETG and PMMA.

  In another embodiment, the sheet structure of the present invention is such that the thermoplastic polymer is one or more of an ultraviolet absorber, heat stabilizer, colorant, dye, processing aid, lubricant, filler or reinforcing aid. including.

  In another embodiment, the sheet structure of the present invention further comprises abrasion / scratch resistance, chemical resistance, ultraviolet (UV) resistance, reduced light scattering, reduced light reflection, reduced dust accumulation, reduced condensation, antibacterial Laminated or coextruded layers of one or more thermoplastic or thermoset resins to provide protection from materials, discoloration, haze formation or crack protection Including.

  In cross-section (multi-walled sheet cut across or perpendicular to the extrusion surface as shown in FIG. 1), the sheet is flat and has the longest dimension (length and width) in the horizontal plane When viewed, a series of two or more generally parallel horizontal walls (also referred to as “layers” or “faces” 10) and layers between the layers along the length and separating the layers There is a brazing material 20. These bracings 20 are sometimes also referred to as “webs” or “slats”. A known and commercially available structure of this type having the saddle structure shown in FIGS. 2A-2F is a vertical 21, diagonal 22, or between parallel planes and apart from each other It can be seen that it has a saddle structure, a combination of vertical and diagonal.

  As illustrated in FIGS. 2A-2D, prior art sheets typically have flat horizontal walls designated 11 (first or upper wall) and 12 (second or lower wall). Have. These sheet structures have two or more layers with a generally smooth surface and are collectively referred to as “multi-wall” sheets. For example, as shown in FIGS. 2E and 2F, in the case of three horizontal layers (referred to as “triple wall” sheets), there are two outer walls (11 and 12) and one inner wall 13. Each outer wall has an outer surface 14 and an inner surface 15. For multi-wall sheets having three or more walls, the inner wall surface is referred to as the inner upper surface 16 or the inner lower surface 17. For example, in FIG. 2E, the third wall 13 has an inner upper surface 16 and an inner lower surface 17.

  An important aspect of the invention is the surprising discovery that the light transmission of the sheet is improved by obtaining a wall structure optimized for at least one wall. Preferred optimized wall structures are: (1) a corrugated wall as illustrated in FIGS. 3 and 4, (2) one or more corrugations as illustrated in FIGS. Or (3) a combination thereof. As used herein, corrugated means having alternating ridges 30 and grooves 32. Preferably, the corrugation is in the direction of extrusion, which may be the machine direction or the longitudinal direction of the extruded sheet. An alternative preferred embodiment of the present invention is a sheet structure in which both outer walls have a corrugated shape (see FIG. 5).

  Without being bound by any particular theory, we believe that corrugated walls / surfaces improve light transmission by reducing the reflection of light reaching the sheet structure at low angles. Alternatively or in addition, the corrugated shaped wall / surface may allow light reflected at one part of the corrugated surface to be captured by another part of the corrugated surface (another part of that corrugated surface In part, the light reflected at a part of the corrugated surface reaches the surface at a more convenient angle so that it can propagate into the sheet structure rather than reflect off).

  In embodiments in which only one wall has a corrugated shape or only one wall has a corrugated surface, the preferred arrangement of the sheet of the present invention when used on a greenhouse roof or wall is such that the solar radiation is in the greenhouse. The corrugated wall / surface is placed outside or outside the greenhouse so that it passes through the sheet from the outside and through the corrugated wall / surface into the greenhouse.

  The peak or center of the ridge of the waveform is called the top 31. The center of the bottom of the corrugated groove is called a valley 33. Each ridge has a first surface 34 and a second surface 35 that meet at the apex 31. Each groove has a first surface 35 and a second surface 36 that meet at a valley 33. The first and second surfaces of the groove are the first surfaces of two adjacent ridges. The first and second surfaces of the ridge are the first surfaces of two adjacent grooves. The peaks and valleys are rounded, in other words, the intersection of the first and second surfaces of the ridges and valleys is not defined by the angle, but by the radius. The requirement that the top of the corrugation is rounded improves the overall durability of the sheet structure, in particular toughness. For example, in the case of thermoplastic polymers that are sensitive to incision, such as polycarbonate, the sharp corners (as defined by the angle) act as stress concentrators, and the ductility of the polymer, for example impact resistance, in particular cutting. Impact resistance may be significantly reduced. The requirement that the corrugated valleys be rounded reduces the likelihood that dirt, dust and other particulates will collect and collect at the bottom of the groove. The distance from the top to the valley is called the height of the ridge 37. The distance from the top to the valley is sometimes referred to as the depth of the groove 37. The distance between two adjacent peaks and / or two adjacent valleys is referred to as pitch 38.

  The radius defining the top of the ridge may be the same as or different from the radius defining the adjacent valley. The height and pitch may independently vary from ridge to ridge across the width (perpendicular to the extrusion direction) of the inventive sheet. For example, the pitch between each ridge across the width of the sheet may be constant while the height of the ridges may be different. The height of the ridges may vary irregularly or in a fixed pattern. Alternatively, the height of each ridge across the width of the sheet may be constant while the pitch between the ridges may be different. The pitch of the ridges may vary irregularly or in a fixed pattern. Alternatively, both the height and pitch of the ridges may differ either in an irregular or fixed pattern across the width of the sheet. Preferably, the top and valley radii are the same, the height of the ridges is constant across the width of the sheet, and the pitch between the ridges is constant across the width of the sheet. When the crest and trough radii are the same, both the height and pitch are constant and the repeating pattern of corrugations is the same across the width of the sheet and can be described as a periodic wave. The preferred wave description is that of a sine wave.

In one embodiment, the corrugation surface corrugation can be defined by the following equation:
When 0 ≦ x ≦ 0.25, z = 0.25− (0.25 ² −x ² ) ^1/2
Or when 0.25 ≦ x ≦ 0.5, z = 0.25 + (0.25 ² − (x−0.5) ² ) ^1/2
Where x = 1/2 pitch and z = height.

  For corrugated and non-corrugated walls, the thickness is defined by the distance from the first surface of the wall to the second surface of the wall. The thickness 50 of the corrugated upper wall 18 and the thickness 51 of the non-corrugated lower wall 12 are shown in FIG. The thickness 52 of the wall 40 with the corrugated surface is defined by the distance from the non-corrugated surface 41 to the top of the ridge of the opposite corrugated surface 42. The thickness 52 of the wall 40 having only one corrugated surface is shown in FIG. 6A. The thickness 53 of the wall 43 with two corrugated surfaces is defined by the distance from the top of the first corrugated surface ridge of the wall 45 to the top of the opposite corrugated surface 46 of the second corrugated surface 46. . The thickness 53 of the wall 43 with two corrugated surfaces is shown in FIG. 7A.

  In one embodiment, one or more of the walls have a corrugated shape, as illustrated in FIGS. If the multi-wall sheet of the present invention has one or more walls of a corrugated shape, preferably defined by sinusoids, the pitch of the corrugated walls is about 0.1 mm or more, preferably about 0.1 mm. 5 mm or more, more preferably about 0.75 mm or more, and most preferably about 1 mm or more. When the multi-wall sheet of the present invention has one or more walls with a corrugated shape defined by a sine wave, the pitch of the corrugated walls is about 50 mm or less, preferably about 30 mm or less, and more Preferably it is about 15 mm or less, and most preferably about 5 mm or less.

  In another embodiment, one or more of the walls have one or more corrugated surfaces, as illustrated in FIGS. When the multi-wall sheet of the present invention has one or more walls having one or more corrugated surfaces, the pitch of the corrugated surfaces is about 0.05 mm or more, preferably about 0.01 mm. Or more, more preferably about 0.05 mm or more, and most preferably about 0.1 mm or more. When the multi-wall sheet of the present invention has one or more walls having one or more corrugated surfaces, the pitch of the corrugated surfaces is about 10 mm or less, preferably about 5 mm or less, More preferably it is about 2 mm or less and most preferably about 1 mm or less.

  The wall thickness of the multiwall sheet of the present invention is independently about 0.1 mm or more, preferably about 0.3 mm or more, and most preferably about 0.5 mm or more. The wall thickness of the multiwall sheet of the present invention is independently about 10 mm or less, preferably about 5 mm or less, and most preferably about 1 mm or less.

  The thickness of the brazing material of the multi-wall sheet of the present invention is about 0.1 mm or more, preferably about 0.3 mm or more, and most preferably about 0.5 mm or more. The thickness of the brazing material of the multi-wall sheet of the present invention is about 8 mm or less, preferably about 4 mm or less, and most preferably about 0.8 mm or less.

  The multi-wall sheet of the present invention has a thickness of about 2 mm or more, preferably about 6 mm or more, and most preferably about 10 mm or more. The multi-wall sheet of the present invention has a thickness of about 100 mm or less, preferably about 50 mm or less, and most preferably about 16 mm or less.

  A preferred extruded thermoplastic sheet structure of the present invention comprises corrugated walls such that the edges of the sheet can be assembled into standard commercially available aluminum or plastic frames used in the greenhouse market and And / or surface. For example, commercially available pyramid-shaped or prism-shaped multi-wall sheets. They are sometimes referred to as zigzag sheets, which are not compatible with standard aluminum or plastic frameworks. Zigzag seats require a special expensive framework that is more difficult to install, time consuming and expensive to install. Furthermore, zigzag sheets do not last very long and are prone to breakage due to the sharp ridges at the top and bottom of the pyramid. Also, it is difficult to wash away the waste accumulated in the sharp corners of the bottom of the pyramid.

  Desired overall sheet thickness, number of walls (ie, layers or faces), and spacing between walls or layers (eg, vertical braid height) are selected as appropriate to provide desired sheet performance characteristics. can do. For sheet thicknesses up to about 40 mm, two or three spaced layers are preferably used (ie double or triple wall sheets). When three layers are used (first or top layer, second or bottom layer, and third or center layer), the center layer is at an equal distance from the top and bottom layers ( (In the middle) or closer to one or the other layer.

  The number and design of the brazing depends on the structural requirements of the sheet. The eaves may be upright 21 (that is, perpendicular to the sheet wall), diagonal 22 (including intersecting diagonals 23), or a combination thereof. When both upright and diagonal brazing are used, the diagonal brazing may intersect the wall at the same point 24 where the upright brazing intersects the wall, or may intersect at different points 25 and 26.

  As will be appreciated by those skilled in the art, depending on the need for stiffness, thermal insulation, light transmission and weather resistance, these types of structures can be prepared from a wide range of plastic resins. Preferably, the multi-wall sheet of the present invention is prepared from one of the known rigid thermoplastic resins. As thermoplastic resins, polycarbonate (PC), polypropylene (PP), polystyrene (PS), polystyrene acrylonitrile copolymer (SAN), butadiene-modified SAN (ABS), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET) , Glycol modified PET (PETG) and polyvinyl chloride (PVC). More preferably, the sheet structure is prepared from PC, PET, PETG, PMMA. Most preferably, the sheet structure is prepared from PC.

  The structures of the present invention are also wear / scratch resistant, chemical resistant, ultraviolet (UV) radiation resistant, light scattering, particularly when it is desired to modify the surface of the sheet structure in some way. Other thermoplastics to give desired performance results like reduction, light reflection reduction, dust accumulation reduction, condensation reduction, antibacterial, protection from discoloration, protection from cloud formation, protection from cracks, etc. Alternatively, a further layer of thermosetting resin may be included, laminated, or coextruded. Thermoplastic resins may contain the usual types of additives used for their known purposes for these types of resins and structures. These additives include stabilizers such as UV absorbers or heat stabilizers, colorants such as dyes, processing aids such as lubricants, fillers, reinforcing aids, fluorescent whitening agents, and fluorescent additions. Examples include, but are not limited to, agents. Such additives can be added to the resins used to prepare these structures and / or any layers laminated or coextruded to them for their known purposes.

  The multi-wall sheet structure of the present invention is prepared through a profile die by known extrusion processes. Corrugated surfaces are generated on the multi-wall sheet structure of the present invention during the extrusion process, for example, by using a corrugated calibrator unit or by post-embossing the sheet with an embossing roller. can do. In another embodiment, a corrugated film is laminated or coextruded onto one or more surfaces of one or more walls of a multi-wall sheet.

  While the invention has been disclosed in its preferred form, those skilled in the art will recognize that many changes, additions and deletions can be made without departing from the spirit and scope of the invention as set forth in the appended claims and equivalents thereof. It will be clear.

FIG. 2 shows a cross-sectional view along the extrusion direction of a prior art double wall sheet structure including vertical brazing.

Figures 2A-2F represent the brazing structure of various prior art multi-wall sheet structures.

3 and 3A show cross-sectional views of a double wall sheet structure of the present invention that includes walls having a corrugated shape.

Fig. 6 shows an alternative embodiment of a cross-sectional view of a double wall sheet structure of the present invention comprising a wall having a corrugated shape.

Fig. 4 shows an alternative embodiment of a cross-sectional view of a double wall sheet structure of the present invention comprising two walls having a corrugated shape.

6 and 6A show an alternative embodiment of a cross-sectional view of a double wall sheet structure of the present invention that includes a wall having a corrugated surface.

7 and 7A show an alternative embodiment of a cross-sectional view of a double wall sheet structure of the present invention that includes a plurality of walls having corrugated surfaces.

Claims (19)

  (I) a thermoplastic polymer; (ii) an extruded thermoplastic multi-wall sheet structure comprising at least two generally parallel walls, each wall having first and second surfaces, and The walls are at a distance from each other and at least one of the walls has a corrugated shape, one or more corrugated surfaces, or a combination thereof; (iii) the walls are in the extrusion direction A sheet structure that is separated from each other by brazing material that spans the length of the sheet.   The sheet according to claim 1, comprising two walls (first wall and second wall), each wall having an inner surface and an outer surface, wherein the first wall has a corrugated shape.   The sheet according to claim 2, wherein the second wall has a corrugated shape.   The sheet according to claim 1, comprising two walls (a first wall and a second wall), each wall having an inner surface and an outer surface, wherein the first wall has a corrugated outer surface.   The sheet of claim 4, wherein the first wall has a corrugated inner surface.   The sheet of claim 4, wherein the second wall has a corrugated outer surface.   The sheet of claim 5, wherein the second wall has a corrugated outer surface.   The sheet of claim 7, wherein the second wall has a corrugated inner surface.   The sheet of claim 2, wherein one or more surfaces are corrugated.   The sheet of claim 3, wherein one or more surfaces are corrugated.   4. A sheet according to claim 2 or 3, wherein the corrugations are defined by sinusoidal waves with a pitch of about 0.1 mm to about 50 mm.   9. A sheet according to claim 5, 6, 7, or 8, wherein the corrugation is defined by a sine wave with a pitch of about 0.1 mm to about 50 mm.   The wall and surface corrugations are defined by a sine wave, the corrugated wall sine wave pitch is about 0.1 mm to about 50 mm, and the corrugated surface sine wave pitch is about 0.01 mm to about 10 mm. The sheet according to claim 9 and 10.   The sheet of claim 1 having a thickness of about 2 mm to about 100 mm.   The sheet of claim 1 comprising three or more walls.   The sheet according to claim 1, wherein the thermoplastic resin is PC, PET, PETG, or PMMA.   The sheet according to claim 1, wherein the thermoplastic polymer is PC.   The sheet according to claim 1, wherein the thermoplastic polymer comprises one or more of an ultraviolet absorber, a heat stabilizer, a colorant, a dye, a processing aid, a lubricant, a filler or a reinforcing aid.   Abrasion / scratch resistance, chemical resistance, ultraviolet (UV) resistance, reduced light scattering, reduced light reflection, reduced dust accumulation, reduced condensation, antibacterials, protection from discoloration, protection from cloud formation or from cracks The sheet of claim 1 further comprising a laminated or coextruded layer of one or more thermoplastic or thermosetting resins to provide protection.

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