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
2001-05-17
2004-06-08
Mullis, Jeffrey (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...
C525S09200D, C525S09200D, C525S09200D, C525S09200D, C525S095000, C525S098000, C525S191000, C525S217000, C525S231000, C525S240000, C525S241000
Reexamination Certificate
active
06747094
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a high-impact thermoplastic resin composition comprising a partially or completely crosslinked saturated rubber-like polymer and a thermoplastic resin. More particularly, it relates to a high impact thermoplastic resin composition comprising a thermoplastic elastomer and a thermoplastic resin, said thermoplastic elastomer comprising a partially or completely crosslinked saturated rubber-like polymer and a polyolefinic resin and/or a polystyrene-based resin, and said thermoplastic resin being a polystyrene-based resin, polyamide-based resin, polyester-based resin or the like.
(2) Description of the Related Art
Many resins such as polystyrene-based resins, polycarbonate-based resins, polyamide-based resins and polyester-based resins are known as hard thermoplastic resins. These resins are widely used as material for a variety of commercial products such as domestic electrical appliances, automobiles, food containers, packages, information-related devices and buildings. However, many of these resins, when used singly, are low in impact resistance and have a limitation in their field of application. For instance, polystyrene (PS), which is one of the polystyrene-based resins, is favorably used for the said purposes because of its high rigidity and good moldability, but polystyrene per se is fragile and its use is limited. Therefore, its impact resistance improved version, i.e. high-impact polystyrene (HIPS), is more popularly used. In this high-impact polystyrene, its rubber component needs to be crosslinked for affording stabilized high impact resistance irrespective of molding conditions. In production of ordinary high-impact polystyrene, polybutadiene is used as rubber component because rubber can not be crosslinked unless it has double bond in the molecule. The material reinforced with rubber having double bond in the molecular is poor in weather resistance as its rubber component is subject to light deterioration. HIPS, therefore, has the disadvantage of being incapable of outdoor use, for instance use as building material. Styrene-acrylonitrile-butadiene (ABS) resin, which is one of polystyrene-based resins, is also known as high impact resin, but this resin has the same problems as HIPS—very bad weather resistance and incapability of outdoor use—because of use of polybutadiene as rubber component. Polycarbonate-based resins are credited with high impact resistance, and certainly their molded articles small in thickness show high impact resistance, but impact resistance lowers as thickness of the molded article increases. Therefore, in application of polycarbonate-based resins as a molding material, they are usually alloyed with ABS resin, although such alloying is also purposed to improve fluidity of polycarbonate resins. This material, too, involves the above problems because of use of ABS resin. In these circumstances, request has been rising for a high impact material with excellent weather resistance in certain uses, especially in use for building materials.
SUMMARY OF THE INVENTION
In view of the above circumstances, the present invention is envisaged to provide a high impact thermoplastic resin with excellent weather resistance.
In the course of studies pursued for attaining the above object, the present inventors found that a high-impact thermoplastic resin with excellent weather resistance can be obtained by forming an alloy of (a) a thermoplastic elastomer comprising a partially or completely crosslinked saturated rubber-like polymer and a polyolefinic resin and/or a styrene-based resin, more specifically a dynamically crosslinked thermoplastic elastomer comprising a saturated rubber-like polymer and a polyolefinic resin, a polystyrene-based resin or a polyolefinic resin/polystyrene-based resin mixture, and (b) a polystyrene-based resin such as polystyrene, poly(styrene-acrylonitrile). The present inventors further found that this alloy, which consists of a partially or completely crosslinked saturated rubber-like polymer and a polystyrene-based resin or consists of a partially or completely crosslinked saturated rubber-like polymer, a polystyrene-based resin and a polyolefinic resin, is also improved in chemical resistance when used in combination with a polystyrene-based resin and a polyolefinic resin, because of the presence of a polyolefinic resin in addition to a polystyrene-based resin. Thus, the present invention was completed. It was further found that a high-impact thermoplastic resin with excellent weather resistance can be obtained by using a resin other than polystyrene-based resins such as polystyrene and poly(styrene-acrylonitrile), for example a polycarbonate-based resin, a polyamide-based resin, a polyphenylene ether-based resin or a polyester-based resin, and forming an alloy thereof with a thermoplastic elatomer comprising a partially or completely crosslinked saturated rubber-like polymer and a polyolefinic resin and/or a styrene-based resin. The present invention has been attained on the basis of these findings.
Saturated rubber-like polymers can not be crosslinked in their molecules under the ordinary polystyrene resin producing conditions, but partial or complete crosslinkage can be attained by adding an organic peroxide in the presence of a polyolefinic resin or a polystyrene-based resin by using an extruder or other suitable means to effect dynamic crosslinking. This may be accounted for by the fact that in production of ordinary impact-resistant polystyrene resin, polymerization of styrene in the presence of an organic peroxide and crosslinking of a rubber-like polymer are carried out simultaneously, and when an organic peroxide necessary for crosslinking the saturated rubber-like polymer is added, it becomes impossible to control polymerization (because a run-away reaction takes place), but when dynamic crosslinking is effectuated by an extruder, as it is not accompanied by polymerization, it is possible to add an excess amount of an organic peroxide, allowing stabilized crosslinking of the saturated rubber-like polymer. According to the present invention, by making use of this dynamic crosslinking technique, a saturated rubber-like polymer is crosslinked in a polyolefinic resin or a polystyrene resin, and an alloy of this dynamically crosslinked thermoplastic elastomer and various types of thermoplastic resin is formed to realize a high-impact thermoplastic resin with excellent weather resistance.
Thus, the present invention provides a high-impact thermoplastic resin composition comprising (A) a thermoplastic elastomer comprising a partially or completely crosslinked saturated rubber-like polymer and a polyolefinic resin and/or a polystyrene-based resin, and (B) at least one thermoplastic resin selected from the group consisting of polystyrene-based resins, polyamide-based resins, polyurethane-based resins, polycarbonate-based resins, polyphenylene ether-based resins, polyester-based resins, acrylic resins, polyacetal-based resins and polyphenylene sulfide-based resins.
The thermoplastic elastomer used as component (A) in the present invention consists of a rubber moiety comprising a crosslinked rubber-like polymer and a fluid moiety comprising a polyolefinic resin and/or a polystyrene-based resin. In this case, if there exists no affinity or compatibility between the saturated rubber-like polymer and the polyolefinic resin or polystyrene-based resin forming the fluid moiety of the thermoplastic elastomer, no high interfacial strength with the saturated rubber-like polymer can be obtained, so that the molded products of the high-impact thermoplastic resin composition of the present invention are low in strength. Also, when a polyolefinic resin is used in combination with a polystyrene-based resin, if affinity or compatibility is absent between them or between these resins and the thermoplastic resin used as component (B), the molded products of the composition of the present invention tend to prove low in strength because of phase separation of said t
Kinoshita Hideo
Ohtani Ikuji
Yasui Takeshi
Asahi Kasei Kabushiki Kaisha
Mullis Jeffrey
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