Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
1999-04-26
2001-09-04
Nakarani, D. S. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C047S017000, C047S019200, C047S029500, C047S029500, C047S029500, C428S451000, C428S458000
Reexamination Certificate
active
06284383
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a glass laminate for greenhouse. More particularly, the present invention relates to a glass laminate for greenhouse, which has excellent transmission for visible light and which is very effective for prevention of scattering of shattered pieces of glass at breakage, prevention of daytime temperature increase inside greenhouse, prevention of nocturnal radiational cooling, prevention of glass fogging caused by the dew condensation occurring owing to difference in temperature between greenhouse inside and outside, and prevention of falling of the waterdrops formed by said dew condensation. The present invention further relates to a greenhouse in which the above glass laminate is used at the lighting area.
BACKGROUND ART
Greenhouses are horticulture facilities covered with glass windows at the whole area. In greenhouses covered mainly with a transparent plate glass, glass breakage is dangerous to workers because the shattered pieces of glass mix with the soil in greenhouse. Glass has had further problems in that since glass has high transmittance to sunlight and high heat conductivity, the temperature inside greenhouse becomes very high in the daytime in summer, requiring a high cost for cooling and to the contrary, in the night in winter, the temperature inside greenhouse becomes low owing to radiational cooling, requiring a cost for heating.
In order to solve these problems, it has been conducted to attach, to the glass windows of greenhouse, a film for prevention of scattering of broken pieces of glass, or a sunlight-control film having a metal or metal oxide layer formed by vapor deposition (i.e. a heat ray-reflecting film).
For example, greenhouses having a heat ray-reflecting film attached to the glass of the lighting area thereof are proposed in JP-A-54-66227, JP-A-61-58527 and JP-A-61-58528. These proposals, however, have a main object of reducing the energy (e.g. fuel oils) required for the heating of greenhouse inside, and make no suggestion on any persistent and effective means for prevention of growth of the waterdrops formed by dew condensation.
With these film-attached glass windows, there has been a problem in that dew condensation takes place owing to the difference in temperature between greenhouse inside and outside, at the side of window facing the inside of greenhouse, i.e. at the film side of window, and it hinders the transmission of sunlight or induces the falling of waterdrops from the greenhouse ceiling, giving adverse effects on horticulture crops.
In order to solve this problem, it has been conducted to coat a surfactant on the film surface of window facing the inside of greenhouse. However, this approach had no persistent effect and had no practical applicability.
TASK TO BE ACHIEVED BY THE INVENTION
An object of the present invention is to provide a glass laminate for greenhouse, which is very effective for prevention of scattering of shattered pieces of glass at breakage, prevention of daytime temperature increase inside greenhouse, prevention of nocturnal radiational cooling, prevention of glass fogging caused by the dew condensation occurring owing to difference in temperature between greenhouse inside and outside, and prevention of growth and falling of waterdrops.
Other object of the present invention is to provide a glass laminate for greenhouse, which has the above-mentioned properties and exhibits the properties persistently.
MEANS FOR ACHIEVING THE TASK
The study by the present invention found out that the above objects of the present invention can be achieved by a glass laminate for greenhouse, comprising a heat ray-reflecting film laminated on one side of a transparent glass, which is characterized in that
(1) the heat ray-reflecting film comprises a transparent thermoplastic resin film, at least one metal oxide layer and at least one metal layer, on one side of the resin film,
(2) the glass laminate has the heat ray-reflecting film laminated, via an adhesive layer, on one side of the transparent glass, at the side opposite to the thermoplastic resin film side,
(3) the glass laminate has a film for prevention of growth of the waterdrops formed by dew condensation, which is formed on the surface of the thermoplastic resin film, and
(4) the glass laminate has an integral transmittance of 55% or more for a visible light having a wavelength of 400 nm to less than 750 nm and an integral transmittance of 50% or less for a near-infrared light having a wavelength of 750 nm to less than 2,100 nm.
The glass laminate of the present invention is utilized by using it at the lighting area of greenhouse. The construction of the present glass laminate is described below. To make the description simple, “at least one metal oxide layer and at least one metal layer” in the heat ray-reflecting film is hereinafter referred to simply as “heat ray-reflecting layer”. The detailed constitution of this heat ray-reflecting layer will be described later.
The glass laminate of the present invention has a constitution of a transparent glass/an adhesive layer/a heat ray-reflecting layer/a thermoplastic resin film/a film for prevention of growth of waterdrops. This glass laminate is used at the lighting area of greenhouse so that the side of the transparent glass is positioned outside the greenhouse and the side of the film for prevention of growth of waterdrops is positioned inside the greenhouse.
In a greenhouse, the glass laminate is used, in most cases, at the lighting area of house side and sloping roof.
The constitution of the present glass laminate is described in detail below.
In the glass laminate of the present invention, the transparent glass can be an ordinary transparent plate glass as long as it satisfies the optical properties required for the glass laminate. In particular, a plate glass conventionally used for greenhouses may be used as it is. As the transparent glass, a glass having such a thickness of 2.5 to 6 mm, in particular about 3 mm, as specified by JIS R 3202 can be used preferably.
In the present glass laminate, the heat ray-reflecting film is constituted by the above-mentioned heat ray reflecting layer and a film (hereinafter referred to as “base film” in some cases). The base film is a thermoplastic resin film which is transparent and flexible. Such a base film is desirably a heat-resistant thermoplastic resin film since a heat ray-reflecting layer is formed thereon by sputtering, vacuum deposition or the like. Preferred examples of the polymer forming the thermoplastic resin film are polyesters typified by polyethylene terephthalate and polyethylene-2,6-naphthalate; aliphatic polyamides; aromatic polyamides;
polyethylene; polypropylene; or the like. Of these, polyesters are more preferred. Of these thermoplastic films, a biaxially stretched polyethylene terephthalate film superior in heat resistance and mechanical strengths is particularly preferred.
Such a thermoplastic resin film can be produced by a known process. A biaxially stretched polyester film, for example, can be produced by drying a polyester, melting the dried polyester using an extruder at a temperature of Tm to (Tm+70)° C. (Tm is the melting point of the polyester), extruding the molten polyester from the die (for example, T-die, I-die or the like) onto a rotary cooling drum to rapidly cool it at 40 to 90° C. to produce an unstretched film, stretching the unstretched film at a temperature of (Tg−10) to (Tg+70)° C. (Tg is the glass transition temperature of the polyester) in a stretch ratio of 2.5 to 8.0 in its longitudinal direction, then stretching the resulting film in a stretch ratio of 2.5 to 8.0 in the transverse direction, and as necessary heat-setting the resulting film at a temperature of 180 to 250° C. for 1 to 60 seconds. The obtained film preferably has a thickness of 5 to 250 &mgr;m.
In the present invention, the heat ray-reflecting film has a structure in which a heat ray-reflecting layer is formed on one side of the above-mentioned base film. The heat ray-reflecting layer is constituted by at least o
Nakarani D. S.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teijin Limited
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