Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1995-02-24
1996-05-28
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523309, 528486, 528487, 528491, 528502, C08F 622, C08J 312, C08J 316
Patent
active
055212310
DESCRIPTION:
BRIEF SUMMARY
This application is a PCT application filed under 37 C.F.R. .sctn. 1,371.
FIELD OF ART
The present invention relates to a process for producing a thermoplastic copolymer powder with high bulk specific gravity.
BACKGROUND ART
It is desirable that thermoplastic resin powder has high bulk specific gravity in view of efficient utilization of the storage space of the powder as a product and incidental reduction of its transportation cost.
Hitherto, many studies have been made on the method for elevating bulk specific gravity of thermoplastic resin powder. For example, many researches have been conducted on means for improving powder properties of the powdery or granular polymers recovered from graft copolymer latices containing an elastomeric backbone polymer in a high ratio. For instance, U.S. Pat. No. 4,897,462 discloses a method for carrying out slow coagulation of a polymer latex in the presence of a coagulant of a specific concentration. Also, U.S. Pat. No. 4,275,178 discloses a method for improving the powder properties such as bulk specific gravity and blocking resistance of the produced coagulated slurries or dry powders by adding a hard polymer thereto.
The former method characterized by the slow coagulation in the presence of a coagulant of a specific concentration is capable of providing a spherical powder with a narrow particle size distribution, but it has disadvantages in that because of high water content of the powder after dehydration, when a heat treatment is carried out at a high temperature during solidification for obtaining the solid particles, the fine individual particles in the coagulated particles may be fused together without compacted sufficiently, making it unable to obtain the coagulated particles with high density and, consequently there can not be obtained the particles of high bulk specific gravity.
The latter method characterized by the addition of a hard polymer for improving the powder properties is designed to elevate bulk specific gravity of the powder by densifying the filled structure of the coagulated particle agglomerates by such means as cohesion of the coagulated particles, but this method has the problem that the effect of improving the density of the coagulated particles themselves can not be expected and a powder with a well satisfactory bulk specific gravity can not be obtained.
The present inventors have pursued further studies with a view to solving the above problems and, as a result, found that a polymer powder with a high bulk specific gravity comprising the compacted particles can be obtained by adding a specific polymer and/or an inorganic compound to a coagulation slurry or polymer powder obtained from a thermoplastic polymer latex and compressing and comminuting the resulting polymer powder. The present invention has been attained on the basis of this finding.
DISCLOSURE OF THE INVENTION
The present invention provides a process for producing a thermoplastic polymer powder which comprises adding a polymer (B) and/or an inorganic compound (C) to a coagulation slurry of a thermoplastic polymer (A) obtained by emulsion polymerization and having a glass transition temperature Tg defined by the following equation (1) or to a polymer powder obtained by drying said coagulation slurry, said polymer (B) and/or inorganic compound (C) being added in an amount of 0.1-10 parts by weight to 100 parts by weight of said thermoplastic polymer (A), compressing the thermoplastic polymer (A) at a temperature in the range of (Tg-30) to (Tg+50).degree. C. and then comminuting the mixture: .times.Tg.sub.n ( 1) polymer (A); W.sub.1, W.sub.2, . . . W.sub.n each represents the weight fraction of each monomer i (i=1, 2, . . . n) in said polymer (A); and Tg.sub.1, Tg.sub.2, . . . Tg.sub.n each represents the glass transition temperature of the polymer composed of each monomer i).
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic illustration of the apparatus used in the production process of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
In the
REFERENCES:
patent: 3992350 (1976-11-01), Bensa et al.
patent: 4169737 (1979-10-01), Burke, Jr. et al.
patent: 4374941 (1983-02-01), Sandstrom
patent: 4874841 (1989-10-01), Sugimori et al.
patent: 4897462 (1990-01-01), Yusa et al.
patent: 4977241 (1990-12-01), Sigimori et al.
patent: 5061556 (1991-10-01), Dotzauer et al.
patent: 5064938 (1991-11-01), Suzuki et al.
patent: 5273823 (1993-12-01), Hwang et al.
Patent Abstracts of Japan, vol. 12, No. 391 (C-537), Oct. 18, 1988, JP-A-63 135 404, Jun. 7, 1988.
Database WPI, Derwent Publications, AN 86-323231, JP-A-61 241 106, Oct. 27, 1986.
Hadano Wataru
Sato Haruki
Sugihara Masaki
Suzuki Fumio
Merriam Andrew E. C.
Michl Paul R.
Mitsubishi Rayon Co. Ltd.
LandOfFree
Process for producing thermoplastic copolymer powder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing thermoplastic copolymer powder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing thermoplastic copolymer powder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-787404