WO1992019710A1

WO1992019710A1 - Solvent composition

Info

Publication number: WO1992019710A1
Application number: PCT/US1992/003312
Authority: WO
Inventors: Harold Leonard Jackson
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1991-05-09
Filing date: 1992-04-28
Publication date: 1992-11-12

Abstract

A solvent composition for cleaning polyester processing equipment containing at least about 60 % by weight of a dialkyl ester of a dibasic acid, and a vinyl polymerization inhibitor.

Description

TITLE

SOLVENT COMPOSITION FIELD OF THE INVENTION

This invention relates to a solvent composition particularly useful in the clean-up of equipment used in the processing of unsaturated polyester resins and vinyl ester resins.

BACKGROUND OF THE INVENTION

In the manufacture of cast and fiberglass- reinforced polyester resin products such as bathtubs, boat hulls, and the like, it is conventional to apply a gel coat of the resin to the mold surface followed by a mixture of resin and fiberglass. Application of the resin or the resin-fiberglass mixture is often done by spraying. As a finishing step before curing, the resin compositions are usually rolled or brushed to smooth the surface, to remove trapped air, and to embed the fiberglass into the resin. Equipment such as spray guns, rollers and brushes used in these operations require periodic cleaning to remove resin residue.

Traditional solvents for the removal of such residue are acetone and methylene chloride. These solvents are effective but volatile. These solvents not only cause air pollution, but there is evidence that methylene chloride is hazardous to the health of the user. Furthermore, acetone is highly flammable. Accordingly, there is a need for a replacement solvent that is less volatile and less hazardous.

Applicants' initial approach to provide a more desirable solvent was to try a mixture of dibasic esters, for applicant had previously found that such a mixture in combination with other ingredients could replace methylene chloride based system in paint

removers - see U.S. Patent 4,780,235. This

substitution did clean the resin processing equipment, but led to a further problem, namely that the resin polymerized in the solvent, making it very difficult to recover the solvent, and difficult to remove the waste from the container.

An object of the present invention is to provide a solvent system for cleaning polyester resin equipment that avoids the pollution and health hazards of the prior art, and does not raise solvent recovery problems.

SUMMARY OF THE INVENTION

The present invention is a composition

suitable for use in cleaning polyester processing equipment comprising at least about 60% by weight of at least one C₁ to C₄ dialkyl ester of a C₄ to C₆ aliphatic dibasic acid, and 0.001 to 1.0% by weight of a vinyl polymerization inhibitor, preferably about 0.01 to

0.2%. The preferred composition of the present

invention also contains at least about 0.1 part per million by weight of an ultraviolet light fluorescing compound. The presence of this fluorescing compound allows the persons working with the solvent to

determine if this resin processing equipment is

relatively free from solvent, and thus relatively free from vinyl polymerization inhibitor, for the presence of large concentrations of solvent and inhibitor on the resin processing equipment will increase the time

required to cure the polyester resin.

The solvent system of the present invention may also contain other solvents in complemental

amounts.

If desired the composition of the invention may also contain an odorant that will mask the odor of the solvent system.

DETAILED DESCRIPTION

The solvent system of the present invention contains at least 60% by weight of a C₁ to C₄ dialkyl ester of a C₄ to C₆ aliphatic dibasic acid. In most instances this component of the solvent system will be a mixture of aliphatic dibasic acids that have been esterified with one aliphatic alcohol; however, the invention includes solvent systems which have only one aliphatic dibasic acid esterified with one aliphatic alcohol, as well as mixtures of aliphatic dibasic acids that have been esterified with mixtures of aliphatic alcohols. Commercially available dibasic esters are satisfactory, for example the commercially available dibasic acid mixture containing about 17% by weight dimethylsuccinate, about 66% by weight dimethyl

glutarate, and about 17% by weight dimethyl adipate or the commercially available mixture containing about 77% by weight dimethyl glutarate and about 23% by weight dimethyl adipate.

Suitable vinyl polymerization inhibitors for use in the solvent of the invention include

hydroquinone; 2,5-diphenylhydroquinone; 2,5-dichlorohydroquinone; 2,5-dimethylhydroquinone; 1,4-napthaquinone 4-(t-butyl) catechol and 2 , 6-di-t-butyl

catechol . Other possibilities include phenothiazine, trinitrobenzene, 2,5-dihydroxy-1,4-benzoquinone;

quinone, 1,4-benzoquinone; chloranil; 9,10- phenanthraquinone and 4-amino-1-naphthol.

Other solvents that may be used in the composition of the invention to complement the dibasic acid esters include:

N-Methoxy-2-pyrrolidone

Dipropylene glycol monomethyl ether

acetate

Ethyl 3-ethoxypropionate

Xylene

Propylene carbonate

gamma-Butyrolactone

Acetic acid ester of C₇ to C₁₃ oxo

alcohols

Suitable ultraviolet light fluorescing

compounds include anthracene and napthalene. If it is desired to add an odorant to mask the smell of the solvent system, suitable commercially available odorants include: Cobratec(R) Reodorant Fresh Air(OS) from PMC

Specialties Group, Inc. 501 Murray Rd., Cincinnati, OH

Cobratec(R) Reodorant Lemon(OS) as above Cobratec(R) Reodorant Vanilla (OS) as above Reodorant No. RM-190/540 from Creative

Fragrances Manufacturing Inc. 10420 Piano Rd., Dallas, TX 75238

Rho-D-Ban 201AX, from Lautier Industrial Div., Member of the Florasynth Group, 410 E. 67th St., NY, NY

Rho-D-Ban 222CX, as above.

The amount of odorant added will depend on the specific one selected, and different users will

probably desire different amounts.

EXAMPLES

Example 1

A curable polyester mixture was prepared by mixing 1.4 parts by weight of Lupersol DDM-9 with 98.6 parts by weight of a general purpose unsaturated

polyester resin, Koppers 6060-5. Lupersol DDM-9, a product of Organic Peroxides Division, Atochem North America, is a solution of methyl ethyl ketone peroxide containing 8.8±0.1% active oxygen. Koppers 6060-5 resin, a product of Koppers Company, is an iso- and/or tere-phthalic resin recommended for laminating

applications.

Four solutions were prepared by dissolving 33 parts by weight of the above polyester/DDM-9 mixture in 67 parts by weight of (a) dibasic ester (hereinafter sometimes DBE) solvent, (b) DBE solvent containing

0.02% hydroquinone (HQ), (c) DBE solvent containing

0.01% hydroquinone, and (d) DBE solvent containing

0.004% hydroquinone. These solutions were stored at room temperature and inspected at regular intervals for gel formation. The DBE solvent was about 17% by weight dimethyl succinate, about 66% by weight dimethyl glutarate and about 17% by weight dimethyl adipate.

Solution Gel Time, hrs

(a) Resin/DBE 20

(b) Resin/DBE/0.02% HQ None at 192 hrs.

(c) Resin/DBE/0.01% HQ None at 192 hrs. (d) Resin/DBE/0.004% HQ 65

Similar prevention of gelation occurred when the same experiments were performed with Hetron® 197 with antimony oxide, a corrosion resistant polyester resin from Ashland Chemicals; Reichhold 33-072, a general purpose o-phthalate polyester resin from

Reichhold Chems, Inc.; and Alpha 77-601SV, a

dicyclopentadiene (DCPB) polyester resin from Alpha Resins Corp.

Example 2

The general procedure of Example 1 was employed with a variety of commercial unsaturated

polyester and vinyl ester resins. The data are

recorded in Table I.

Example 3

The procedure and resins of Example 2 were used except 4-tertiary butyl catechol was employed as the antigelling agent rather than hydroquinone. The data are recorded in Table II.

Example 4

A composition for the clean-up of resins, particularly unsaturated polyester and vinyl ester resins, was prepared. To one gallon of a mixture of dibasic esters containing about 77% dimethyl glutarate and 23% dimethyl adipate were added 1.1 g hydroquinone, 0.042 g anthracene, and 10.3 g Cobratec® Reodorant

Fresh Air (OS) odorant from PMC Specialties Group, Inc. The resulting clear, essentially colorless solution possessed a pleasant, agreeable odor and fluoresced strongly when exposed to ultraviolet light from a Mineralight® lamp, model UVSL-25.

A mixture of 2 parts by weight of this solution with 1 part of Aropol® 7241 T-15 isophthalic acid-based unsaturated polyester resin (Ashland

Chemical Co.) containing 1.4% Lupersol® DDM-9 methyl ethyl ketone peroxide catalyst formed no gel after storing at room temperature for 20 days. In contrast, 2 parts of the mixture of 77% dimethyl glutarate and 23% dimethyl adipate with 1 part of the Aropol® 7241 T-15/Lupersol® DDM-9 solution set to a firm gel in less than 20 hours at room temperature.

When Ashland's Aropol® L2530 T-20 low styrene o-phthalic acid-based unsaturated polyester resin or when Ashland's Hetron® 197P chlorinated unsaturated polyester resin were substituted for the Aropol® 7241 T-15 resin in the above procedure, similar results were observed.

Claims

CLAIMS:

1. A composition comprising at least about 60% by weight of at least one C₁ to C₄ dialkyl ester of a C₄ to C₆ aliphatic dibasic acid, and 0.001 to 1.0% by weight of a vinyl polymerization inhibitor.

2. The composition of claim 1 which also contains at least about 0.1 part per million parts by weight of an ultraviolet light fluorescing compound.

3. The composition of claim 1 in which the composition contains dimethyl glutarate, and dimethyl adipate, and the vinyl polymerization inhibitor is selected from the group consisting of hydroquinone, 1,4-napthaquinone, and 4-(t-butyl) catechol.

4. The composition of claim 2 in which the ultraviolet light fluorescing compound is selected from the group consisting of anthracene and napthalene.

5. The composition of claim 3 in which the aliphatic dibasic ester contains about 17% by weight dimethyl succinate, about 66% by weight dimethyl glutarate, and about 17% by weight dimethyl adipate.

6. The composition of claim 3 in which the aliphatic dibasic ester contains about 77% by weight dimethyl glutarate and about 23% by weight dimethyl adipate.

7. The composition of claim 1 containing at least one additional solvent selected from the group consisting of N-methyl-2-pyrrolidone; dipropylene glycol monomethyl ether acetate; ethyl 3-ethoxypropionate; xylene; propylene carbonate; gamma-butyrolaction; and acetic acid ester of 7 to 13 carbon atom oxo alcohols.

8. The composition of claim 1 which consists essentially of the dialkyl ester, the inhibitor, and a ultraviolet light fluorescing compound.