Appeal 2007-3412
Application 10/832,450
molecular weights to synthesize a PVB (Toyama at 2:42–60) and then
blending 30 to 70 parts per hundred of a plasticizer (id. at 7:42–53).
41. Esters, including dihexyl adipate, are named as preferred plasticizers;
certain diesters of triethylene glycol are particularly preferred. (Toyama
at 7:11–41.)
42. Toyama discloses that dynamic viscoelasticity measurements yield the
ratio of the storage elastic modulus to the loss elastic modulus ("the loss
tangent," also referred to as "tan δ"). (Toyama at 9:45–49.)
43. According to Toyama, when the tan δ measurement is carried out as a
function of temperature, tan δ assumes a maximum value at a temperature
that "corresponds to the glass transition temperature (Tg), that is to say the
softening point, of the material." (Toyama at 9:49–55.)
44. Toyama teaches that when Tg is near room temperature, sound
insulation performance is "remarkably good," but that the PVB film
becomes too soft to handle easily, and the impact resistance of the laminated
glass "tends to be insufficient." (Toyama at 9:56–63.)
45. Toyama teaches that glass laminates meet its objectives when the
temperature corresponding to the maximum of tan δ is not over 30°C.
(Toyama at 9:40–44.)
46. In Example 1, Toyama describes a laminate using a PVB plasticized
with 60 phr of a diester, but no properties of the laminate are disclosed.
(Example 1 at 15:51 to 16:9.)
47. Toyama exemplifies a number of glass laminates having PVB layers
plasticized with 39 or 40 phr ester, having tan δ maximum temperatures
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