Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-09-03
2000-03-28
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524108, 524110, 568591, C08K 506
Patent
active
060433035
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to hexagonal crystals of diacetals useful as nucleating agents for polyolefin resins, a nucleating agent comprising said hexagonal crystals, and a polyolefin resin composition comprising said nucleating agent and a polyolefin resin. The present invention also concerns with a method for molding said polyolefin resin composition by injection molding or extrusion molding, and molded products produced from the composition via processing.
BACKGROUND ART
Conventionally diacetals such as 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol and the like have been incorporated as a nucleating agent into polyolefin resins to improve the optical properties of the polyolefin resins such as transparency and gloss, their mechanical properties such as rigidity and their thermal properties (e.g. Japanese Unexamined Patent Publication No. 117044/1978).
However, the above-mentioned diacetal nucleating agent has posed problems of frequently developing fish eyes in the obtained molded products and coloring the molded products yellow. While polyolefin resins containing said diacetal nucleating agent are considerably improved in the above optical, mechanical and thermal properties compared with polyolefin resins free of the diacetal nucleating agent, there is a need for further improvements in optical, mechanical and thermal properties in view of the current growing demand for high qualities.
From the viewpoint of methods for molding polyolefin resins, problems are raised. That is, in high temperature melting molding methods, molded products tend to become yellowish, whereas in low temperature melting molding methods, fish eyes are easily formed due to a non-dispersed nucleating agent although the coloration of the molded products are suppressed.
An object of the present invention is to provide a nucleating agent which is capable of preventing the occurrence of the above-mentioned fish eyes and coloration and capable of increasing the molding speed and further improving the optical, mechanical and thermal properties of polyolefin resins, as well as a polyolefin resin composition and molded products containing such nucleating agent.
Another object of the invention is to provide a method for molding polyolefin resins substantially free of the foregoing prior art problems.
DISCLOSURE OF THE INVENTION
The present inventors carried out extensive research to achieve said objects. In the course of the research, the present inventors took an approach different from the conventional investigation which was limited to the chemical structure of diacetals, and continued the research paying attention to the crystal structure of diacetals.
As to the crystal structure of diacetals, it was already elucidated that a diacetal, when fully aged in a molten polyolefin, forms a fibril network. However, the relation of said network structure with the action of nucleating agents was not clear.
In particular, not only the relation of the network with the action of nucleating agents is unknown, but also fundamental questions are unresolved at all as to whether the diacetal network formed in a molten polyolefin is of molecular crystal or is amorphous and, if the network is crystalline, as to what the unit lattice thereof is like ("The Advanced Techniques of Additives for Polymers", published by Kabushiki Kaisha CMC on Jan. 6, 1988, pp 204-222 (Chapter 9, Nucleating Agent)).
"The Advanced Techniques of Additives for Polymers (published by Kabushiki Kaisha CMC on Jan. 6, 1988) referred to above describes on page 207 a structure of a freeze-dried product of a gel formed from a diacetal and a dioxane solvent, not a gel formed from a diacetal and a polymer. This freeze-dried product is not composed of hexagonal crystals of a diacetal but is composed of a hexagonally assembled structure of helically grown pillars. That is to say, said product is not a crystal composed of hexagonal unit lattices. It is also unknown whether said product is crystalline or amorphous.
In other words, the traditional researches on the n
REFERENCES:
patent: 4562265 (1985-12-01), Machell
patent: 4902807 (1990-02-01), Kobayashi et al.
Kobayashi Toshi-aki
Sakai Shizuyoshi
Egwim K. C.
New Japan Chemical Co. Ltd.
Wu David W.
LandOfFree
Hexagonal crystals of diacetals, nucleating agent comprising sai does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hexagonal crystals of diacetals, nucleating agent comprising sai, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hexagonal crystals of diacetals, nucleating agent comprising sai will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1326593