Kneaded rubber for expandable formulation

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

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C524S525000, C524S526000, C524S543000, C525S191000, C525S232000, C525S240000

Reexamination Certificate

active

06268428

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a non-vulcanized, kneaded rubber designed for expandable formulation uses. More specifically, the invention relates to a kneaded rubber suitable for die forming sponge parts, principally comprising continuous foam, to be used, for example, for producing door roof weather strips.
The kneaded rubber material for expandable formulation, according to the present invention, is applicable not only as die forming and sponge rubber material, but also as an extrusion molding material and a material for producing foam rubber products principally comprising closed-cell foam.
2. Description of the Related Art
A door weather strip will now be taken as an example for purposes of explanation. Sealability and a soft touch when opening and closing are demanded for door weather strips and the like. Therefore, at least the part of the strip facing the door should be formed of a sponge rubber with a low rebound elasticity.
The main parts of weather strips are extrusion molded, while the corner and end parts thereof are die formed using injection and transfer molding techniques. The sponge rubber comprises a low-viscosity blend, that is highly fluid at high temperatures so that the rubber can retain fluidity in dies for die forming and injection fluidity for injection molding.
Meanwhile, kneaded rubbers for expandable formulation, as prepared with kneaders such as the Banbury mixer and kneading rollers, are at a relatively low viscosity. These rubbers are generally stored so that the rubbers are folded together in a form of continuous sheet or continuous tape. Therefore, the rubbers are adhesive with a small kneaded rubber viscosity (green strength).
The following problems occur regarding the handling of the resulting kneaded rubbers after termination of the kneading procedures:
(1) After the termination of the kneading procedures, the resulting kneaded rubbers readily adhere to and remain on kneading rollers, involving a large variation in the material weight per unit area, when the kneaded rubbers are cut out in a sheet shape or in a tape shape from the kneading rollers. The kneaded rubbers readily remain on the rotors of the Banbury mixer, and thereby contaminate a subsequent batch with extraneous materials.
(2) Adhesion preventives, such as talc and surfactants do not function satisfactorily to permit storing the resulting kneaded rubbers in a folded shape. Therefore, these rubbers should be immersed in a water tank for storage. More specifically, a large volume of adhesion preventives causes die contamination (in both transfer and injection molding) and thus induces potential connection failure between the die-formed part and the main extrusion formed part of weather strip. Furthermore, kneaded rubbers storage in water, absorb water, leading to a frequent incidence of variation in the expansion ratio.
(3) Materials designed for single transfer molding, so-called ball materials, adhere together, leading to frequent occurrence of variation in the ball material weight when the ball materials are prepared by cutting.
(4) Due to the low green strength, the rubbers cannot be fed sufficiently into the feed rollers of material loaders, such as injection molding machines or extruders, so that molding failures readily occur due to poor loading of the materials.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a kneaded rubber for an expandable formulation, with the rubber exhibiting excellent fluidity during molding and good handling (drawing out of rolls, storage, ball material preparation, and material loading into molding machines) after termination of kneading.
The present inventors have attained the object by an expandable kneaded rubber comprised of a polymer alloy base, comprised of a sea phase of an ethylene/&agr;-olefin
on-conjugated polyene terpolymer rubber and an island phase of a polyolefin resin, where the polyolefin resin wholly or primarily comprises a monomer C
4
-C
6
&agr;-olefin and is at an MFR (Melt Flow Rate) of 15 g/10 min or more at 190° C. under a load of 2.196 kgf according to ASTM D 1238 and the kneaded rubber exerts a Mooney viscosity profile characterized according to JIS K 6300, according to the following equation:
(ML
1+4
80° C.)−(ML
1+4
160° C.)≧15.
Preferably, the kneaded rubber satisfies the following Mooney viscosity profile formula:
(ML
1+4
80° C.)−(ML
1+4
160° C.)≧30.
The kneaded rubber for expandable formulation can be readily produced by preparing the morphology, in the aggregated form, of the island phase in a non-spherical shape. The polyolefin resin comprising the island phase is preferably crystallizable. The kneaded rubber according to the invention is produced by softening or melting the polyolefin to prepare the above morphology of the island phase in a non-spherical shape during kneading.
As demonstrated in the following examples, the kneaded rubber for expandable formulation according to the invention achieves an increased green strength while the rubber retains fluidity allowing it to act as a molding material.
SUBSTITUTE SPECIFICATION
Therefore, the conventional handling problems of kneaded rubbers are overcome. More specifically, the kneaded rubber for expandable formulation according to this invention works well as it is excellent from the standpoint of kneaded rubber handling, drawn out of rolls, held in storage, used for ball material preparation, and as it is loaded into molding machines. The Mooney viscosity profile is shown graphically, together with those of conventional kneaded rubbers, are shown in FIG.
2
.


REFERENCES:
patent: 4818785 (1989-04-01), Otawa et al.
patent: 10-195227 (1998-07-01), None
patent: 97/02316 (1997-01-01), None

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Kneaded rubber for expandable formulation does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Kneaded rubber for expandable formulation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kneaded rubber for expandable formulation will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2550117

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.