Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-08-29
2004-08-17
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S216000, C525S232000, C525S240000
Reexamination Certificate
active
06777498
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an olefin thermoplastic elastomer, a process for producing the olefin thermoplastic elastomer and use of the olefin thermoplastic elastomer. More particularly, it relates to an olefin thermoplastic elastomer suitable for melt molding of irregular shaped corner connections or irregular shaped end parts such as a weather strip, door trim and the like for automobiles, a process for producing the same and use thereof.
BACKGROUND OF THE INVENTION
Conventional production of weather strips having a connection is generally carried out by cutting extrusion vulcanized molded articles of a rubber compound of an ethylene/propylene
on-conjugate diene terpolymer (EPDM), setting them in a mold from one side or both sides to form a cavity, injecting the same kind of a rubber molding material as this EPDM rubber compound into the cavity and performing vulcanizing molding.
Further, from the viewpoint of productivity, environmental adaptability and weight saving, a thermoplastic elastomer (composition) for which a vulcanization step is unnecessary has been used as materials of the molding in place of the vulcanized rubber prepared by using an ethylene/propylene
on-conjugate diene terpolymer (EPDM).
In general, vulcanization bonding or the like between a vulcanized rubber and a thermoplastic elastomer can be not conducted so that integration thereof has been conducted by means of an adhesive. However, it is not said that the integration with an adhesive is sufficient in view of productivity and environmental adaptability.
As the technique of a thermoplastic elastomer composition, addition of a polar group-containing resin can be described in JP-A-2(1990)-115249, JP-A-8(1996)-244068 and JP-A-10(1998)-324200. In the case of the addition of the polar group-containing resin, releasability of a molded article from a mold is lowered and thereby a molding cycle is prolonged.
As another technique, a technique that a specific ethylene/1-octene copolymer is added before molding a thermoplastic elastomer is disclosed in JP-A-9(1997)-40814. Although the present inventors confirmed that this technique is very effective against base material breaking, the rubber elasticity of molded articles is missing due to addition of a non-cross-linked ethylene polymer (ethylene/1-octene copolymer).
As a further technique of the vulcanized rubber, a technique of adding finely crystalline polyprolylene in addition to the conventional vulcanized rubber composition is disclosed in JP-A-10(1998)-7849. However, when finely crystalline polypropylene such as atactic polypropylene is added, not only rubber elasticity which the conventional vulcanized rubbers have is lowered but also tackiness of molded articles is induced occasionally with the elapse of time.
In addition to the techniques regarding the thermoplastic elastomers and the composition of vulcanized rubbers, there are a technique of obtaining anchoring effect by making a cut surface rough after cutting a vulcanized rubber (JP-A-9(1997)-118133) and a technique of applying a powdery polyolefin resin on the cut surface of a vulcanized rubber (JP-A-6(1994)-47816). Any of the above techniques, however, have a defect such that the adhesion is not improved for lowering in productivity.
Accordingly, it has been desired that an olefin thermoplastic elastomer having sufficient bonding strength to vulcanized rubbers without through an adhesive layer and capable of forming molded articles having such a characteristic that at peeling a base material is broken, that is, any of molded articles are broken but the molded articles are not broken at the interface thereof, and molded articles obtainable by melt bonding the elastomer with a vulcanized rubber be realized. Additionally, it has been desired that an olefin thermoplastic elastomer having sufficient hardness as a thermoplastic elastomer and capable of forming light weight molded articles with rubber elasticity, and having excellent moldability and economic properties, and molded articles obtainable by melt bonding the elastomer with a vulcanized rubber be realized.
OBJECT OF THE INVENTION
The present invention is intended to solve the problems associated with the prior art. It is an object of the invention to provide an olefin thermoplastic elastomer having sufficient bonding strength to vulcanized rubbers by no way of an adhesive layer and capable of forming molded articles having such a characteristic that at peeling a base material is broken, and to provide molded articles obtainable by melt bonding the elastomer with a vulcanized rubber. It is another object of the invention to provide an olefin thermoplastic elastomer having sufficient hardness as a thermoplastic elastomer and capable of forming light weight molded articles with rubber elasticity, and having excellent moldability and economic properties, and to provide molded articles obtainable by melt bonding the elastomer with a vulcanized rubber.
It is a further object of the invention to provide a process for preparing the above olefin thermoplastic elastomers.
SUMMARY OF THE INVENTION
The first olefin thermoplastic elastomer of the invention is an olefin thermoplastic elastomer, which forms an islands-sea structure, and has a particle phase having an average particle diameter of less than 2 &mgr;m, a gel fraction of from 0.5 to 15% by weight and a quantity of heat of melt at a temperature of 125° C. or below, as measured in a Differential scanning calorimeter (DSC), of 40% or more based on the total quantity of heat of melt.
The thermoplastic elastomer comprises an olefin resin and an olefin rubber and the olefin rubber is cross-linked.
The first olefin thermoplastic elastomer of the invention has a quantity of heat of melt, as measured in a differential scanning calorimeter (DSC), (which is the same as the above total quantity of heat of melt) of preferably 30 J/g or more.
With regard to the first olefin thermoplastic elastomer of the invention, the proportion of the islands phase having a ratio of major axis to minor axis of two or more is preferably not more than 3% based on the total of the islands phases, and the compression set (CS) at 70° C. is preferably not more than 65%. This compression set at 70° C. is an index of rubber elasticity.
The first olefin thermoplastic elastomer of the invention is obtainable by dynamically vulcanized an olefin resin and an olefin rubber in the presence of a cross-linking agent and preferably satisfies the following relation:
A×CS<
5.0
wherein A is an amount (part by weight) of a cross-linking agent for adding based on the total amount (100 parts by weight) of the olefin resin and olefin rubber, and CS (%) is a compression set at 70° C., which is an index of rubber elasticity.
The second olefin thermoplastic elastomer of the invention is prepared from a blend comprising:
5 to 50 parts by weight of a high-density polyethylene (A1) having a density (ASTM D 1505) of 0.940 g/cm
3
or more,
5 to 70 parts by weight of an ethylene/&agr;-olefin (
on-conjugated polyene) copolymer rubber (B) comprising ethylene, an &agr;-olefin of 3 to 20 carbon atoms and optionally a non-conjugated polyene, and
5 to 50 parts by weight of a polypropylene (C), provided that the total of the components (A), (B) and (C) is 100 parts by weight, and has a gel fraction of from 0.5 to 15% by weight.
With regard to the second olefin thermoplastic elastomer of the invention, the high-densitypolyethylene (A1) preferably has a melt flow rate at 190° C. (MFR; ASTM D 1238 under a load of 2.16 Kg) of not more than 10 g/10 min.
The second olefin thermoplastic elastomer of the invention is an olefin thermoplastic elastomer having an islands-sea structure, and desirably has a particle phase having an average particle diameter of not more than 2 &mgr;m, a gel fraction of from 0.5 to 15% by weight, and a quantity of heat of melt at a temperature of 125° C. or below, as measured in a differential scanning calorimeter (DSC), of 40% or more based on the total quantity of heat of melt. The second olefin thermo
Imai Tadashi
Uchiyama Akira
Burns Doane Swecker & Mathis L.L.P.
Mitsui Chemicals Inc.
Nutter Nathan M.
LandOfFree
Olefin thermoplastic elastomer, process for producing the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Olefin thermoplastic elastomer, process for producing the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Olefin thermoplastic elastomer, process for producing the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3320251