Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-09-22
2002-08-20
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S219000, C554S055000
Reexamination Certificate
active
06437032
ABSTRACT:
This invention relates to a novel compound bearing an urethane linkage useful as a plasticizer for polyvinyl chloride (PVC) and a process for preparing the compound. This compound is an adduct of ricinoleic esters and an isocyanate, which is prepared by the process of the present invention is new and has formula 1 of the drawings enclosed with the specification.
The invention specifically relates to a process for the preparation of a compound bearing an urethane linkage useful as a plasticizer for poly vinylcllloride (PVC). The compound prepared by the process of the present invention is new and has the formula 1 shown in the drawings accompanying this specification. The compound of formula 1, is derived from a fatty acid ester bearing a hydroxyl functionality and/or compound containing isocyanate functionality. More specifically, the invention relates to a process for the preparation of urethane type compound of formula 1 of the drawings annexed with the specification having molecular weight in the range of 650 to 900.
The compound of formula 1, prepared by the process of the present invention has excellent compatibility with PVC on account of the desirable functional groups present in the molecule. Hence, the invention further provides a process for the preparation of improved compounded PVC employing the urethane type compound of formula 1 of the drawings enclosed with the specification.
It is well known in the prior art that addition of organic compounds, called plasticizers, to PVC confers on the PVC desirable properties such as flexibility, softness, good feel and ease of processability, extensibility and lower melting temperature [Encyclopedia of PVC Vol. 1 and 2, L. I. Nass (1976)]. Plasticizers function by dissolving in PVC, reducing the cohesive energy density between the polymer chains and reducing the polar forces exerted by the halogen atoms present in PVC. For any organic compound to function as an effective plasticizer for PVC it must possess (a) very high miscibility with PVC, (b) must have polar groups and (c) must have a low tendency to diffuse and migrate out of the polymer during its effective service life. In addition, the plasticizer must not cause colouration to PVC, should be non toxic, odorless, possess low volatility and thermally stable at the temperature of mixing and compounding PVC with plasticizer.
A variety of organic compounds have been reported as effective plasticizers for PVC. These include esters of phthalic anhydride with aliphatic alcohols (linear/branched) with four to fifteen carbon atoms, epoxidized soyabean oil, esters of trimellitic acids, phosphates, esters of benzoic and citric acids, and halogenated hydrocarbons. Higher molecular weight polyesters (800-6000) prepared by condensation of diols with adipic or sebacic acids are also used as plasticizers. Of these, phtlhalate based plasticizers are the most widely used because of their excellent compatibility with PVC, ease of fusion and all round desirable properties.
Nevertheless, phthalate esters are not without drawbacks. Dioetylphthalate has been implicated as a carcinogen causing liver cancer in rats. Their molecular weights are low on account of which they diffuse out of PVC rapidly and cause “fogging” (cloudy dsposits) of glasses and other transparent surfaces. They are easily extracted by organic solvents, making them unsuitable for use in solvent contact applications. They produce PVC products whose surface resistivity is very high (approximately 4×10
14
&OHgr; at 30° C.) for many applications such as antistatic products for hospitals flooring materials, footwear, hoses, clean room fixtures, trays for integrated circuits and floppy discs, conveyor belt etc. The surface resistivity can be brought down by a factor of 10
1
-10
2
by adding an antistat additive (example Irgastat 51 of Ciba Geigy). However, use of such additives leads to loss of desirable properties of PVC. The thermal and light stability is adversely affected and the antistatic additive exudes out of PVC.
To overcome the above problems envisaged in the prior art, the applicants have now provided a novel compound bearing an urethane. linkage shown in formula 1 of the drawings, which is useful as a plasticizer for PVC; a process for preparing such compound and, a manner in which a compounded PVC is prepared by employing the novel compound.
Therefore, one object of the present invention is to provide a compound having an urethane linkage of formula 1 of the drawings.
Another object of the invention relates to a process for the preparation of new plasticizer for PVC.
Yet another object of the present invention is to provide a process for the preparation of new plasticizer derived from fatty acid esters and a hydroxyl group, and an isocyanate bearing organic compound.
Still another object of the present invention is to provide a process for the preparation of improved compounded polyvinyl chloride using the compound of formula 1 of the enclosed drawings as a primary plasticizer. The use of compound of formula 1 in conjunction with PVC confers on PVC many desirable properties such as flexibility, softness, good mechanical and thermal properties. In addition, use of compound of formula 1 eliminates many of the drawbacks of the hitherto known plasticizers for PVC.
Further object of the invention is for a compounded PVC comprising polyvinyl chloride and a plasticizer of formula 1 of the drawings enclosed with the specification wherein Ar is as defmed in the said drawings.
In the course of the applicants research, they have developed a process for the preparation of a new organic compound of the formula 1 of the drawings wherein Aryl (Ar) is as defined in the annexed drawings which show useful properties as primary plasticizer for PVC. The compound of formula 1 is derived from the reaction of fatty acid esters having eighteen carbon atoms and a hydroxyl group, and organic isocyanates.
The fatty acid esters suitable for die present invention are esters of ricinoleic acid and 12 hydroxyl stearic acid. The ester can be derived by reacting ricinoleic acid or 12 hydroxystearic acid with an alcohol having a linear or branched alky group having 1-10 carbon atoms.
The isocyanate useful in the process of the present invention can be selected from any organic isocyanates having one or two isocyanate groups per molecule. Examples are toluene diisocyanate of formula 3 as shown in the drawings, 4,4′-diisocyanatodipheniylmetlhane of formula 4 as shown in the drawings, 1,4-diisocyanatobenzene of formula 5 as shown in the drawings, hexamethylene diisocyaniate of formula 6 as shown in the drawings, isophorone diisocyanate of formula 8 as shown in the drawings, 1,4-diisocyanatocyclohexane of formula 7 as shown in the drawings. The preferred isocyanates are those derived from aromatic compounds and having at least two isocyanate groups.
Accordingly, the present invention provides a novel compound bearing urethane linkage having formula 1 of the drawings accompanying this specification.
The invention also provides a process for the preparation of a compound bearing urethane linkage having fonnula 1 shown in the drawings accompanying the specification useful as a plasticizer for PVC which comprises reacting fatty acid esters bearing hydroxyl groups with an organic isocynate at a temperature in the range of 30-100° C. in the presence of a catalyst. The molar ratio of hydroxyl bearing fatty acid to the isocyanate may be in the range of 2:1.1, the preferred ration being 2:1.05. The catalyst employed in the reaction may be selected from any one of the following: di-n-butyltindilaurate, di-n-butyl-tinoxide, 1,4-diazabicyclo [2.2.2] octane (DABCO), 4′,4′-dimetlhylainino pyridine (DMAP) and 1,8-diazabicyclo [5.3.0] undec-7-ene (DBU). The concentration of the catalyst may range from 0.02-0.2% by weight of the isocyanate compound. The preferred concentration is in the range of 0.05%. The reaction is conducted for a period of 1-3 hours. The progress of the reaction is monitored by Brookfield viscos
Ganpat Raut Kundalik
Iyengar Srinivasan Subbagiri Ramaswamy
Kumar Saxena Prabhat
Swaminathan Sivaram
C.S.I.R.
Ladas & Parry
Mulcahy Peter D.
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