Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-07-08
2001-02-13
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S492000, C524S495000
Reexamination Certificate
active
06187850
ABSTRACT:
Priority is claimed from Japanese Patent Application No. Hei. 10-193368 filed on Jul. 8, 1998 and Japanese Patent Application No. Hei 11-70760 filed on Mar. 16, 1999, the complete disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a novel sealant composition and to a method for preparing the sealant composition. The sealant composition of the invention is especially favorable for sealing vehicle parts, such as car parts. For example, when filled inside the weather strip of a vehicle, the sealant composition seals the gap between the trim and the plate flange when the plate flange is inserted inside the trim.
The embodiment described herein uses a weather strip for a trunk lid; however, the invention is not limited to this embodiment. The sealant composition of the invention is applicable to any other weather strips, such as lift gates. The sealant composition can also be used for other purposes, such as sealing plate-to-plate gaps or plate-to-rubber gaps.
2. Description of the Related Art
A general example of an ordinary sealant applied to a trunk lid weather strip is described with reference to FIG.
1
and FIG.
2
.
FIG. 2
is a sectional view of the cross section of
FIG. 1
as cut along line
2
—
2
. In
FIG. 2
, the weather strip
12
comprises a trim
14
, a hollow seal
16
and a seal lip
18
. The trim
14
is provided with two pairs of pinching lips
20
and
22
therein, and a plate insert
24
is embedded in the trim
14
. The plate insert
24
is for retaining the shape of the trim
14
and for ensuring the pinching force of the lips
20
and
22
.
A sealant S is charged in the bottom of the trim
14
, and the weather strip
12
is fitted to the plate flange
26
of the trunk via the trim
14
. In this condition, an end portion of the plate flange
26
is inserted into the sealant S. In
FIG. 2
,
27
(dotted line) is a trunk lid.
The sealant ensures the plate flange is rust-proof and seals the inside of the weather strip trim well.
Table 1 shows one conventional sealant composition applicable to the site illustrated in
FIGS. 1 and 2
.
The conventional sealant composition (listed as the comparative example in Table 1) indispensably requires an organic solvent (for example, kerosene) to dissolve the base component, butyl rubber, to produce a predetermined viscosity.
Typical organic solvents for that purpose are generally toxic and volatile, and have the following problems:
(1) The organic solvents require special care to ensure safe working environments in the process of sealant production and coating. Organic solvents can also cause global environment protection problems, thus requiring the release (vaporization) of solvents from sealants to be minimized as much as possible.
(2) Fresh sealants just after production are tacky and stringing. Therefore, in charging the sealants in a desired site, the sealants often adhere to other parts, thus adversely affecting the charging of the sealants. In addition, the fluidity of the sealants is high. Therefore, after the sealant has been charged inside the trim, it is impossible to turn the trim upside down so as to continuously fit the weather strip to the plate flange. On the other hand, if the trim has been left too long after charging with the sealant, the organic solvent vaporizes from the sealant and the viscosity of the sealant increases. In that condition, the load for inserting the plate flange into the trim increases, and this increased load has negative influences on the weather strip fitting operation.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a sealant composition which is free, or at least substantially free, of volatile organic solvent so that the sealant composition is not volatile (non-drying), and which exhibits a sealability comparable to or higher than that of conventional sealants. To attain the above and other objects, the invention is characterized by the following composition.
The sealant composition of the invention comprises, as ingredients, at least one liquid rubber as the base component, at least one tackifier and at least one thixotropy promoter as secondary components, and at least one nonvolatile plasticizer and/or at least one process oil as the dispersion medium.
Preferably, the tackifier is a combination of a liquid tackifier and a resinous tackifier. More preferably, the liquid tackifier is a liquid polybutene.
Also preferably, the liquid rubber is a liquid NBR, the nonvolatile plasticizer is a diphthalate with an alcohol moiety having from 7 to 12 carbon atoms; and the process oil is a paraffinic process oil.
Still preferably, the thixotropy promoter is a powdery calcium carbonate.
In accordance with a preferred method of making the sealant composition, the liquid rubber and other secondary components are uniformly dispersed in a nonvolatile plasticizer or a process oil in a stirring mixer equipped with a rotating and revolving stirrer.
In the process where the tackifier is a combination of a liquid tackifier and a resinous tackifier, resinous tackifier desirably is ground and then dissolved or dispersed in the nonvolatile plasticizer or the process oil.
The non-drying sealant composition of the invention contains no solvent, or at least is substantially solvent free, so that the composition overcomes the problems (i.e., pollution of the environment and time-dependent change in physical properties) of solvent-containing sealants. In addition, the sealant charging operation with the composition is no more complicated than charging operations for solvent-containing sealants, and the sealing characteristics of the composition is comparable to or higher than those of solvent-containing sealants.
The composition of the invention that comprises a process oil but not a plasticizer as the dispersion medium is easy to apply to weather strips of which the trim is of an insertless type, i.e., without insert
24
. This is because the composition containing the process oil causes only minor swelling of the rubber substrate and the trim is not swollen to lower its mechanical strength.
REFERENCES:
patent: 3652380 (1972-03-01), Strack
patent: 4908411 (1990-03-01), Kinoshita et al.
patent: 5332784 (1994-07-01), Shiraki et al.
patent: 5858521 (1999-01-01), Okuda et al.
Kawamura Masato
Mabuchi Akira
Miura Yoshihiro
Mori Etsuro
Wakabayashi Koji
Cain Edward J.
Pillsbury Madison & Sutro LLP
Toyoda Gosei Co,., Ltd.
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