Toyo Engineering Corporation

Mitsui Chemicals, Inc.

Masashino Chemical Laboratory, Ltd

Musashino Chemical Laboratory, Ltd.

Kenichiro Matsuba

Koji Kawano

Tetsuo Maeda

Mune Iwamoto

Shiro Otsuzuki

Ryuichi Sugimoto

Katsunori Yagou

Yozo Maeda

Katsuhisa Arai

Tsuyoshi Aoki

Hiroya Honda

PROBLEM There is provided a method for producing polylactic acid, which is capable of obtaining polylactic acid at low cost, and having high molecular weight. SOLUTION A method for producing polylactic acid by polymerizing molten lactide using at least one reactor having plug flow characteristics with &#x3be;(&#x3c4;), calculated from the following FORMULA (1), of 0.3 or smaller:&#x3be;(&#x3c4;)=&#x222b;((&#x3c4;)&#xd7;(1&#x2212;&#x3c4;))&#x2003;&#x2003;(1)in the Formula (1), E(&#x3c4;) is a residence time distribution function determined by impulse response by starch syrup having a viscosity of 3 Pa&#xb7;s, and &#x3c4; is ratio of elapsed time &#x3b8; and mean residence time &#x3b8;.

Method for producing polylactic acid

A reactor which is a reactor () in the form of a cylindrical vessel having a liquid inlet and a liquid outlet and elongated in a flowing direction, comprising, in the interior, a drive shaft () coaxial with the reactor, one or more stages of plate-shaped or round-bar-shaped agitating elements () extending in a direction perpendicular to the drive shaft, baffles composed of plates or round bars or combination thereof and/or coiled, tubular, plate-shaped or helical heat-exchangers () installed on the inner wall side of the reactor, wherein the natural frequency of the agitating elements is greater than the numerical value at which the agitating elements begin to vibrate, the value being calculated from the viscosity of the solution in the reactor, and the rotating speed and structure of the agitating elements.

Reaction unit

A rubber modified polystyrene composition comprising polybutadiene particles dispersed in polystyrene, wherein the polybutadiene particles have an average volume particle diameter of 6 to 13 microns, and the composition has a gel content of 25 to 35% by weight and a degree of swelling of 13 to 22, is prepared by polymerizing the polybutadiene particles in the presence of styrene. The rubber modified polystyrene composition of the present invention may be used for components contacting flon compounds, such as components of refrigerators.

Flon-resistant rubber modified polystryrene composition

An oil resistant rubber modified polystyrene composition comprises polybutadiene rubber particles having an average volume particle diameter of 6 to 13 &mgr;m dispersed in polystyrene. The oil resistant rubber modified polystyrene of the present invention has a gel content of 25 to 35% by weight, a degree of swelling of 13 to 22, a residual volatile content of 2000 ppm or less, and a total amount of dimer and trimer of 8000 ppm or less. The oil resistant rubber modified polystyrene composition may be prepared by polymerizing styrene in the presence of polybutadiene rubber, foaming a solution of the rubber modified polystyrene under a reduced pressure of 3 to 40 mm Hg, heating the solution in a tubular heater to a temperature of 190 to 230&deg; C., and then flushing the heated solution into a gas-liquid separator to devolatilize an unreacted monomer and a solvent therefrom.

Oil-resistant rubber modified polystyrene composition

A method for removing volatile materials, comprises adding a blowing aid to a polymer composition containing volatile materials, mixing them in a static mixing apparatus, and extruding the resultant mixture by an extruding apparatus into a devolatilizing tank, thereby the mixture is made to be blown, to cause removal of the volatile materials. First, the blowing aid (6) is discharged with an addition nozzle apparatus (2), in a direction opposite to the direction of the flow of the polymer composition (1), to be added, and the polymer composition is introduced into the static mixing apparatus (3), at a pressure at which the blowing does not take place, thereby mixing them. Then, using the extruding apparatus (11), the resultant mixture is extruded into the devolatilizing tank (4), so that the polymer is made into a blown product at such a temperature and a pressure that the blowing coefficient B is 1.4 or more, thereby causing the removal of volatile materials.

Method for removing volatile materials from a polymer composition

A method of dissolving a rubber continuously to form a raw material for the production of rubber-modified polymer, by dissolving a rubber in a monomer liquid dissolving the rubber and capable of reacting with the rubber in the presence or absence of a solvent. Pieces of rubber are fed continuously to a dissolution tank to allow the dissolved rubber and the undissolved rubber to coexist in the dissolution tank, wherein the concentration of the dissolved rubber is the concentration at which the feeding to the reactor is made, and the quantity of the undissolved rubber present in the dissolution tank is at most the quantity that prevents pieces of the undissolved rubber from sticking to one another to form larger rubber masses. The time required for dissolution can be shortened, and the size of a dissolution tank can be made smaller, compared with the conventional methods.

Growing community of inventors

Chiba, Japan

Kenichiro Matsuba