Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1998-10-13
2001-10-02
Nakarani, D. S. (Department: 1773)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C156S106000, C264S001700, C264S261000, C264S265000, C264S294000
Reexamination Certificate
active
06296799
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a composite sheet material, in particular, suitable for the manufacture of windshields mounted in automobile vehicles and a method of making the same. The composite sheet material comprises a glass layer constituting one of the opposed surfaces of the material and a resin layer constituting the other surface, these layers being provided in a laminated fashion.
BACKGROUND ART
Composite sheet materials often include a glass layer at at least either surface to achieve light weight and surface protection from scratching. One known type of such composite sheet materials is a laminate having a glass layer formed by bonding sheet glass to the front surface of a pre-molded resin sheet. Another type is a laminate having glass layers which are formed by bonding sheet glass to the front and rear surfaces of a pre-molded resin sheet respectively such that the resin sheet is sandwiched between the glass layers.
These types of composite sheet materials, however, reveal the drawback that since sheet glass is bonded to a pre-molded resin sheet, gaps are created between the resin sheet and the sheet glass if the surface of the resin sheet is not flat because of warp and shrinkage and these gaps result in bonding defects.
The invention is directed to overcoming this problem and one of the objects of the invention is therefore to provide a composite sheet material and its producing method, the material having at least a glass layer constituting either one of its opposed surfaces for the purpose of surface protection from scratching. This composite sheet material can be easily produced without causing bonding defects and is free from stress-strain.
DISCLOSURE OF THE INVENTION
The above object can be accomplished by a composite sheet material according to one aspect of the invention, the material comprising:
(a) a glass layer made of sheet glass and constituting either one of the opposed surfaces of the composite sheet material; and
(b) a resin layer constituting the other surface of the material and molded by applying a uniform pressure to an entire molten resinous material introduced onto the glass layer so as to be elongated, spreading over the glass layer,
the glass layer and the resin layer being laminated together.
According to another aspect of the invention, there is provided a composite sheet material comprising:
(a) a first glass layer made of sheet glass and constituting either one of the opposed surfaces of the composite sheet material;
(b) a second glass layer constituting the other surface of the material and made of sheet glass disposed parallel with the first glass layer; and
(c) a resin layer formed between the first and second glass layers and molded by applying a uniform pressure to an entire molten resinous material introduced between the first and second glass layers so as to be elongated, spreading over the first and second glass layers.
the first glass layer, the resin layer and the second glass layer being laminated in order.
According to still another aspect of the invention, there is provided a composite sheet material comprising:
(a) a glass layer made of sheet glass and constituting either one of the opposed surfaces of the composite sheet material;
(b) a first resin layer constituting the other surface of the material and made of a resin sheet disposed parallel with the glass layer; and
(c) a second resin layer formed between the glass layer and the first resin layer and molded by applying a uniform pressure to an entire molten resinous material introduced between the glass layer and the first resin layer so as to be elongated, spreading over the glass layer and the first resin layer,
the glass layer, the second resin layer and the first resin layer being laminated in order.
The composite sheet material of the invention has a resin layer which is molded by applying a uniform pressure to an entire molten resinous material which has been introduced onto a glass layer made of sheet glass, such that the molten resinous material is elongated, spreading over the glass layer. Therefore, the composite sheet material has at least one glass layer which constitutes either surface of the material and is hardly damaged by scratching, while being free from bonding defects likely to occur between the glass layer and the resin layer. Additionally, since a uniform pressure is applied to an entire molten resinous material, thereby elongating the molten material to form the resin layer, no stress-strain is generated.
The pressure uniformly applied to the entire molten resinous material may be high enough to restrain the gas contained in the molten resinous material from growing to be bubbles. This prevents creation of bubbles which make the resin layer turbid.
According to a preferred embodiment of the invention, a silane coupling agent or Volan (trade name of E.I.du Pont de Nemous and Company, for methacrylatochromic chloride) is applied in pretreatment to the joint surface of the sheet glass of the glass layer which is to be joined to the resin layer. Alternatively, there may be provided an intermediate layer between the joint surfaces of the glass layer and the resin layer, the intermediate layer being made from, for example, a thermoplastic resinous material which is adhesive to the sheet glass and to the molten resinous material to be molded and which moderates the contraction difference and thermal expansion difference between the sheet glass and the molten resinous material during molding of the molten resinous material into the resin layer.
With the above arrangement, the bonding strength between the glass layer and the resin layer can be enhanced. Prior to the formation of the resin layer, the intermediate layer may be formed by primer coating in which the above resinous material is applied to the joint surface of the sheet glass to be joined to the resin layer or alternatively formed by affixing a resin film formed from the above resinous material to the joint surface.
The sheet glass is transparent while the molten resinous material is selected from the group consisting of polycarbonate, acrylic resin, polystyrene, amorphous polyolefin, polyethylene terephthalate, ethylene-vinyl acetate copolymers (EVA), thermoplastic polyurethane (TPU), ethylene-acrylate-maleic anhydride ternary copolymers, hydrogenated styrene butadiene rubber (SBR hydride), polyvinyl butyral (PVB) and polyolefin elastomers, and the uniform pressure applied to the entire molten resinous material is not less than 15 kg/cm
2
which is high enough to restrain the gas contained in the molten resinous material from growing to be bubbles. With this arrangement, the resultant composite sheet material is not turbid but transparent and free from stress-strain.
In cases where the composite sheet material is provided with the intermediate layer, the thermoplastic resinous material from which the intermediate layer is formed can keep its transparency after the formation of the resin layer and may be selected from the group consisting of polycarbonate, acrylic resin, polystyrene, amorphous polyolefin, polyethylene terephthalate, ethylene-vinyl acetate copolymers (EVA), thermoplastic polyurethane (TPU), ethylene-acrylate-maleic anhydride ternary copolymers, hydrogenated styrene butadiene rubber (SBR hydride), polyvinyl butyral (PVB) and polyolefin elastomers. In cases where the resin layer made of a resin sheet is provided, this transparent resin sheet is preferably formed from a resinous material which is harder and has a higher melting point than the molten resinous material used in molding and selected from the group consisting of polycarbonate, acrylic resin, polystyrene, amorphous polyolefin, polyethylene terephthalate, ethylene-vinyl acetate copolymers (EVA), thermoplastic polyurethane (TPU), ethylene-acrylate-maleic anhydride ternary copolymers, hydrogenated styrene butadiene rubber (SBR hydride), polyvinyl butyral (PVB) and polyolefin elastomers.
It should be noted that the thinner the sheet glass is, the more lightweight the resultant composite sheet material is.
Fujimoto Satoshi
Nogawa Makoto
Oishi Masayuki
Sato Kan'ichi
Armstrong Westerman Hattori McLeland & Naughton LLP
Komatsu Ltd
Nakarani D. S.
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