Process for producing alkyd resins

Details Process for producing alkyd resins Process for producing alkyd resins

2002-03-29

2003-03-18

Boykin, Terressa M. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

C528S272000

Reexamination Certificate

active

06534624

ABSTRACT:

TECHNICAL FIELD
This invention relates to a process for producing alkyd resins using polyester resins which have been recovered from waste materials such as disused PET bottles and regenerated.
BACKGROUND ART
In the past, terephthalic acid was normally not used as the dibasic acid component which is one of starting materials for producing alkyd resins, or if used, only in minor amount, because terephthalic acid was more costly than phthalic acid or phthalic anhydride and also because it tended to render the produced resins turbid or cause occurrence of foreign matters. On the other hand, recently disposal of waste is becoming a serious issue and utilization of disused PET bottles by recycling is under study.
A production method of alkyd resins using polyester resins which have been recovered from waste materials such as disused PET bottles and regenerated is described in, for example, Hei 11 (1999)-228733A-JP. Said method comprises subjecting recovered polyester resin and an alkyd resin oligomer having a molecular weight not higher than 5,000 and containing hydroxyl groups to depolymerization and transesterification. However, this method is subject to a number of problems such that it requires advance synthesis of the alkyd resin oligomer and requires many hours for the depolymerization because the amount of the alcohol component in the occasion of depolymerization is too low to sufficiently depolymerize the recovered polyester resin.
The object of the present invention is to provide a method of producing alkyd resins within a short time, using the polyester resins which have been recovered from waste materials and regenerated.
DISCLOSURES OF THE INVENTION
We have engaged in concentrative studies with the view to accomplish the above object and now discovered that the object could be fulfilled by conducing depolymerization of said regenerated polyester resin and esterification thereof in a mixture of an alcoholic component containing tetra- or higher hydric alcohol(s), an oil and fat and/or a fatty acid, and a polybasic acid component, and completed the present invention.
Accordingly, therefore, the invention provides a production method of an alkyd resin having an oil length of 30-70%, characterized by depolymerizing a polyester resin whose chief starting material is terephthalic acid which has been recovered from waste materials and regenerated, and concurrently esterifying the depolymerized product, in a mixture of an alcoholic component, an oil and fat and/or a fatty acid, and a polybasic acid component, in said alcoholic component the weight ratio of tri- or lower polyhydric alcohol(s) to tetra- or higher polyhydric alcohols being between 0 and 20, said polyester resin being used in an amount of 5-40% by weight, based on the sum of the polyester resin, the alcoholic component, the oil and fat and/or the fatty acid, and the polybasic acid component.
According to the invention, furthermore, paint compositions containing the alkyd resins which are produced by the above method are provided.
Hereinafter the method of the invention is explained in further details.
EMBODIMENTS OF THE INVENTION
Those polyester resins made chiefly from terephthalic acid, which have been recovered from waste materials and regenerated, and which are used in the process of this invention (hereafter the polyester resins may be abbreviated as “regenerated PES”) include polyethylene terephthalate (e.g., PET bottles) which are recovered for recycling of resources, industrial waste polyethylene terephthalate, and polyester resins regenerated from the wastes occurring in the course of production of polyester products (film, fibers, automobile parts, electric and electronic parts, etc.) such as polyethylene terephthalate or polybutylene terephthalate made chiefly from terephthalic acid. In particular, recycled polyethylene terephthalate is suitable. The regenerated PES is normally used in the form of chips or pulverized pieces.
The method of the invention comprises depolymerization and esterification of such regenerated PES in a mixture of an alcoholic component containing tetra- or higher polyhydric alcohol(s) and optionally tri- or lower polyhydric alcohol(s); an oil and fat and/or a fatty acid; and a polybasic acid component, whereby obtaining an alkyd resin. The term, “esterification reaction”, as used herein includes ordinary esterification reactions and transesterification reactions.
Examples of tetra or higher polyhydric alcohols constituting the above alcoholic component include diglycerine, triglycerine, pentaerythritol, dipentaerythritol and sorbitol. Of those, pentaerythritol is particularly suitable because of favorable curing and drying property of the painted film of the paint compositions in which the resulting alkyd resin is used. Also examples of tri- or lower polyhydric alcohols include: trihydric alcohols such as trimethylolpropane, trimethylolethane and glycerine; and dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol and 1,4-dimethylolcyclohexane. Of those, glycerine, ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol are particularly suitable, from the standpoints of depolymerization ability as used in mixtures with said tetra- or higher polyhydric alcohols (e.g., pentaerythritol) and low-temperature dissolving ability of high temperature-melting tetra- or higher polyhydric alcohols.
In the alcoholic component, the blend ratio of tri- or lower polyhydric alcohols to tetra- or higher polyhydric alcohols should be within a range of 0-20, preferably 0.02-10, inter alia, 0.05-5 by weight.
Examples of the oil and fat, i.e., triglycerides of fatty acids, and/or the fatty acids to be mixed with above alcoholic component include the following: as oils and fats, soybean oil, safflower oil, linseed oil, tall oil, coconut oil, palm kernel oil, castor oil, dehydrated castor oil, fish oil and tung oil can be named. In particular, drying or semi-drying oils having iodine values of at least 100 are preferred, inter alia, soybean oil and tall oil are advantageous. As fatty acids, those of soybean oil, safflower oil, linseed oil, tall oil, coconut oil, palm kernel oil, castor oil, dehydrated castor oil, fish oil and tung oil may be named. Of those fatty acids, those of drying oils or semi-drying oils having iodine values of at least 100, inter alia, those of soybean oil and tall oil, are preferred.
The total amount of the selected oil and fat, and/or the fatty acid in the mixture is such that the oil length of the resulting alkyd resin should range 30-70%, preferably 40-60%, for imparting adequate drying property and physical performance of the dry painted films of paint compositions in which the alkyd resin is blended.
As the polybasic acid component to be concurrently used with above alcoholic component, the oil and fat and/or the fatty acid, those normally used as the acid component for forming alkyd resins can be similarly used. For example, dibasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, diphenylmethane-4,4′-dicarboxylic acid, succinic acid, fumaric acid, adipic acid, sebacic acid and maleic anhydride; tri- and higher polybasic acids such as trimellitic anhydride, pyromellitic anhydride, trimesic acid and methylcyclohexene-tricarboxylic acid; and C
1
-C
6
(in particular, C
1
-C
4
) alkyl esters of those dibasic acids and tri- and higher polybasic acids can be named. Of those, dibasic acids and their C
1
-C
6
(in particular, C
1
-C
4
) alkyl esters are preferred.
The use amount of such polybasic acid component is such that the equivalent number of the carboxyl groups in the polybasic acid component per hydroxyl equivalent of the alcoholic component should be within a range of 0.5-1, in particular, 0.6-0.99, inter alia, 0.7-0.99, for securing favorable water resistance and physica

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