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
2002-09-16
2004-06-01
Robertson, Jeffrey B. (Department: 1712)
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...
C524S265000, C524S266000, C524S267000, C524S588000
Reexamination Certificate
active
06743843
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a vibration-absorbing silicone gel composition. More particularly, the invention relates to a silicone gel having excellent vibration-absorbing properties which is for use as a damper or insulator in electrical/electronic appliances.
BACKGROUND OF THE INVENTION
Electronic appliances to be mounted on vehicles, such as sound facilities, measuring instruments, video appliances, and recorders have hitherto employed vibration-proof dampers so as to prevent vibrations or impacts from being transmitted to the electronic appliances. Especially in the appliances in which reading/writing in recording media is conducted by means of an optical pickup, such as CDs, MDs, and DVDs, it is essential to employ dampers or insulators because the precision of reading is impaired by vibrations.
Dampers which absorb vibrations by means of an elastic material such as a coil spring were devised previously. Thereafter, ones comprising a coil spring and a silicone oil or silicone gel sealed up therein were devised because it is difficult to attenuate vibrations with the elastic material alone.
Furthermore, there have been cases where a structure which is formed by injecting a gel material or foam material into a container or bag made of a substance such as a rubber and sealing the container or bag and which employs no spring or the like is used as a damper as described in Japanese Patent Laid-Open Nos. 208534/1995 and 44342/1999. As the material to be sealed up in such a damper is generally used a silicone gel having a penetration of about from 70 to 200.
Such a vibration-absorbing gel desirably is a material having high damping properties and having a large value of loss tangent tan&dgr; in a measurement of coefficient of dynamic viscosity.
However, as described in Japanese Patent Laid-Open No. 123321/1994, there also is a desire for the use of a gel material which has not been sealed up in a container and is in an exposed state, as in the case of a damper having a structure comprising a cylindrical shell, a gel material held in the shell, and a support shaft held in the gel material and a damper material for use in the parts for fixing a plate spring supporting a movable part equipped with the objective of an optical pickup.
In this case, when the gel material has poor shape retention, the gel sags with vibrations or deforms according to vibrations to become unable to recover the original shape. As a result, the gel material has impaired damping properties and, in the worst case, comes not to function as a gel at all. In general, a gel composition having a large value of tan&dgr; has low shape retention and, hence, changes in shape with an intense vibration or impact. Consequently, in dampers having a gel not sealed up in a container or bag, the gel used should be a hard gel having shape retention at least on a given level. It has hence been impossible to attain a gel having high vibration-absorbing properties.
The invention relates to a highly vibration-absorbing silicone gel composition which eliminates the problems described above, has excellent shape retention, and can be used as a damper even in the state of being not sealed up in a container or bag.
DISCLOSURE OF THE INVENTION
As a result of extensive investigations made in order to overcome the problems described above, a vibration-absorbing silicone gel composition mainly comprising: 100 parts by weight of (a) an organopolysiloxane having a (meth)acryloyl group in its molecule; from 5 to 100 parts by weight of (b) an organopolysiloxane unreactive with ingredient (a); from 1 to 50 parts by weight of (c) an amorphous pulverization product of a three-dimensionally crosslinked silicone resin; from 1 to 20 parts by weight of (d) a fumed silica; and an effective amount of (e) a polymerization initiator, could be obtained.
BEST MODE FOR CARRYING OUT THE INVENTION
The invention will be described below in detail. Ingredient (a) used in the invention is an organopolysiloxane having a (meth)acryloyl group in the molecule. The term (meth)acryloyl group herein is a general term for acryloyl and methacryloyl. (Meth)acryloyl groups undergo a polymerization reaction with the aid of an active radical, which will be described below.
The organopolysiloxane as the backbone is an oligomer made up of linearly polymerized siloxane bonds. The silicon atom of each siloxane bond has further two bonds for linkage, which are monovalent hydrocarbon groups, preferably alkyl groups having 1 to 4 carbon atoms or aryl groups. The number of repetition of the siloxane bonds is from 50 to 10,000.
Ingredient (a) will have different crosslink densities on the number and positions of the (meth)acryloyl groups in the molecule, and is preferably designed to be suitable for gels. For example, it is preferred to use the organopolysiloxane described in Japanese Patent Laid-Open No. 184257/1994. However, ingredient (a) is not limited thereto, and any organopolysiloxane can be used as long as the molecule has been designed to attain a low crosslink density.
Preferred as ingredient (a) in the invention is an organopolysiloxane obtained by reacting a compound selected from vinyl-containing isocyanates, acrylic anhydride, methacrylic anhydride, acryloyl halides, and methacryloyl halides with an amino-terminated organopolysiloxane represented by the following general formula 1:
(wherein R
1
and R
2
are divalent hydrocarbon groups, preferably alkylene groups having 1 to 4 carbon atoms or arylene groups such as phenylene; R
3
is a monovalent hydrocarbon group, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group; R
4
is hydrogen or a monovalent hydrocarbon group, preferably an alkyl group such as methyl or an arylalkyl group such as benzyl; R
5
is hydrogen or a monovalent hydrocarbon group or substituted hydrocarbon group, preferably allyl, an alkyl group, or a di- or trialkoxysilylalkyl group; R
6
is a monovalent hydrocarbon group, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group; 1 is an integer of 0 to 4; n is an integer of 1 to 3; and m is an integer of 50 to 10,000).
The organopolysiloxane having an amino group at an end, which is represented by general formula 1, is obtained by causing an organosiloxane having a silanol group at an end to add to an organoalkoxysilane having an amino group. Subsequently, this organopolysiloxane is reacted with an isocyanate compound having at least one (meth)acryloyl group serving as a radical-curable functional group to thereby cause an isocyanate group to add to an amino group. Alternatively, the organopolysiloxane is reacted with (meth)acrylic anhydride or a (meth)acryloyl halide to thereby cause a (meth)acryloyl group to add to the amino group. Thus, the preferred ingredient (a) for use in the invention is produced. These reactions proceed quantitatively with great ease without necessitating a catalyst.
Although each reactant to be used can be suitably selected from compounds known in the relevant field, typical examples thereof are as follows. Typical examples of the organoalkoxysilane having an amino group are represented by general formula 2:
(wherein R
1
and R
2
are divalent hydrocarbon groups, preferably alkylene groups having 1 to 4 carbon atoms or arylene groups such as phenylene; R
3
is a monovalent hydrocarbon group, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group; R
4
is hydrogen or a monovalent hydrocarbon group, preferably an alkyl group such as methyl or an arylalkyl group such as benzyl; R
5
is hydrogen or a monovalent hydrocarbon group or substituted hydrocarbon group, preferably allyl, an alkyl group, or a di- or trialkoxysilylalkyl group; X is an alkoxy group; n is 0 or 1; and 1 is an integer of 0 to 4). Specific examples of these compounds include (&bgr;-aminoethyl)-&bgr;-aminoethyltrialkoxysilanes, (&bgr;-aminoethyl)-&ggr;-aminopropyltrialkoxysilanes, (&bgr;-aminopropyl)-&bgr;-aminoethyltrialkoxysilanes, (&ggr;-aminopropyl)-&ggr;-aminopropyltrialkoxysilanes, aminopropyltrialkoxysilanes, aminopropylmethyldialkoxys
Robertson Jeffrey B.
Sughrue & Mion, PLLC
Three Bond Co. Ltd.
LandOfFree
Silicone gel composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silicone gel composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silicone gel composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3365787