Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-03
2001-08-07
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06271291
ABSTRACT:
FIELD OF THE INVENTION
This invention is concerned with masterbatches of selected antistatic agents in certain copolyesters based on terephthalic acid, naphthalenedicarboxylic acid, and/or 1,4-cyclohexanedicarboxylic acid and on the blending of these masterbatches with the same or other homo- or copolyesters to provide films, sheeting, and thermoformed articles having antistatic properties. Specifically, antistat additives for certain copolyesters are disclosed which provide the required antistat performance in the final film, sheet, or molded article. However, these additives cause feeding problems during extrusion processing for some preferred copolyester compositions.
BACKGROUND OF THE INVENTION
Polyesters are widely used as extrusion and injection molding resins for applications such as fibers, films, sheeting, food and beverage containers and the like. Commonly used polyesters include polyethylene terephthalate (PET), poly-1,4-butylene terephthalate (PBT), and poly-1,4-cyclohexanedimethylene terephthalate (PCT). Copolyesters are frequently used when special properties such as lower processing temperatures, clarity, or inhibited crystallization are needed. Polyesters like most other synthetic polymers are poor conductors of electricity. Thus, during extrusion, processing, or handling of such polymers, static charges may accumulate. This is especially true under conditions of low relative humidity. Static charge is highly undesirable in that it can cause material handling problems during processing, lead to shocks when molded parts are handled, lead to the collection of dust on packages, and cause damage to sensitive electronic parts that are stored in plastic packaging due to dissipation of static charge. Therefore, it would be advantageous if thermoplastic polyesters could be provided which had good antistatic properties.
There are many antistat additives available for use in thermoplastic polymers including polyesters. Often these additives are blended with the same or other thermoplastic polymer in higher concentration to form a masterbatch that is subsequently let down for film or sheet extrusion or injection molding. In addition, some antistat additives can cause processing problems such as poor feeding during extrusion that can prohibit their use.
SUMMARY OF THE INVENTION
In accordance with this invention, there are provided masterbatch compositions comprising certain antistat agents and copolyesters containing 1,4-cydohexanedimethanol (CHDM) that are extrudable, and as such allow use of the antistat additives in producing the required antistat performance in the final film, sheet or molded artide prepared therefrom. The amount of antistatic agent utilized is from about greater than 1.6 weight percent to about 10 weight percent based on the total composition.
A preferred copolyester utilized is based on terephthalic acid, naphthalenedicarboxylic acid, and/or 1,4-cyclohexanedicarboxylic acid, and contains from about 80 to about 99 mole percent ethylene glycol and about 1 to about 20 mole percent of a modifying diol, preferably CHDM. It has been found unexpectedly that masterbatch compositions comprising the specified antistat additive and a copolyester as described above having ethylene glycol in an amount less than 80 mole percent are not satisfactory since such masterbatch compositions are not extrudable.
The antistatic agents are quatemary ammonium salts having thermal stability at temperatures greater than 200° C. Thermal stability is weight loss of less than 5 weight percent when heated to temperatures up to about 275° C. Exemplary are quatemary ammonium alkyl benzene sulfonate salts, quaternary ammonium alkane sulfonate salts, and the like. Specific examples include octyl dimethyl hydroxyethyl ammonium dodecylbenzene sulfonate and octyl dimethyl hydroxyethyl ammonium methane sulfonate. Other compounds of this type are listed in U.S. Pat. Nos. 4,904,825, 5,053,531 and 5,187,214. Some of these materials are available commercially from BASF Corporation. The resulting masterbatch compositions may be blended with the same or different homo- or copolyesters to provide films, sheeting and thermoformed articles having antistatic properties.
DETAILED DESCRIPTION OF THE INVENTION
The novel masterbatch compositions of the present invention comprise a copolyester comprising terephthalic acid, naphthalenedicarboxylic acid, and/or 1,4-cyclohexanedicarboxylic acid, or mixtures thereof, from about 80 to about 99 mole percent ethylene glycol and about 1 to about 20 mole percent of a modifying diol, preferably CHDM; and an antistatic agent. The antistatic agent is present in an amount of from about greater than 1.6 to about 10 weight percent, based on the final composition. Preferably the antistat is present in amounts of from about 3 to about 7 weight based on the total composition.
Useful polyesters in the practice of this invention include terephthalate, naphthalenedicarboxylate and 1,4-cyclohexanedicarboxylate copolyesters, preferably containing ethylene glycol and 1,4-cyclohexanedimethanol (CHDM) moieties. The modifying diol concentrations will generally range from about 1 to about 20 mole percent The copolyesters will generally contain at least about 80 mole percent of terephthalic, naphthalenedicarboxylic, or 1,4-cyclohexanedicarboxylic acid moieties. Mixtures of the acids may be used if desired.
About 1 to about 20 mole percent of modifying acids and/or glycols may be used. Exemplary modifying acid components (aliphatic, alicyclic, or aromatic dicarboxylic acids) of the linear copolyester are selected, for example, from isophthalic acid, 1,3-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, suberic acid, 1,12-dodecanedioic acid, and the like. In polymer preparation, it is often preferable to use a functional acid derivative thereof such as the dimethyl, diethyl, or dipropyl ester of the dicarboxylic acid. The anhydrides or acid halides of these acids also may be employed where practical.
Exemplary modifying diol components of the described copolyesters may be selected from neopentyl glycol, 1,4cyclohexanedimethanol, 1,2-propanediol, 1,3propanediol, 1,4butanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, Z,8-bis(hydroxymethyl)-tricyclo-[5.2.1.0]-decane wherein Z represents 3, 4, or 5; and diols containing one or more oxygen atoms in the chain, e.g. diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, and the like. In general, these diols contain 2 to 18, preferably 2 to 8 carbon atoms. Cycloaliphatic diols can be employed in their cis or trans configuration or as mixtures of both forms. 1,4-cyclohexanedimethanol is the preferred modifying diol.
It is preferred that the modifying diol is present at from about 1-15 mole %, preferably, 5-15 mole %, and more preferably, 10-14 mole %.
A particularly preferred embodiment of the copolyester comprises 100 mole % terephthalic acid, about 80-99 mole percent ethylene glycol and about 1 to 20 mole % 1,4-cyclohexanedimethanol.
Another particularly preferred embodiment of the copolyester comprises 100 mole % terephthalic acid, about 80-90 mole percent ethylene glycol and about 10 to 20 mole % 1,4-cyclohexanedimethanol.
The mole percentages of the diol component of copolyester of the invention total 100 mole %. The mole percentages of the acid component of the copolyester of the invention total 100 mole %.
Small amounts of branching agents such as trimellitc acid, pyromellitic dianhydride, trimethylolpropane, pentaerythritol, and the like may be used. Generally less than about 2 mole percent of such agents is used.
The CHDM and 1,4-cydohexanedicarboxylic components may be in the cis form, the trans form, or a mixture of cis and trans isomers. The acid moiety may be derived from the acid or a suitable synthetic equivalent such as a lower alkyl ester. The dimethyl esters are widely used to make polyesters. The naphthalenedicarboxylate moiety will generally be derived from 2,6-naphthalenedicarboxy
Bell Emily Tedrow
Dobbs Harold Eugene
Hanson Scott Arnold
McWilliams Douglas Stephens
Cain Edward J.
Eastman Chemical Company
Graves, Jr. Esq. Bernard J.
Tubach, Esq. Cheryl J.
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