US1884770A - Finish remover containing methyl acetate - Google Patents

Description

v Patented Oct. 25, 1932 UNITED STATES) PATENT OFFICE,

BORIS N. LOUGOVOY, OF NEW YORK, N. Y., ASBIGNOB TO CHADELOID CHEMICAL COMPANY, OF NEW YORK N. Y., A CORPORATION OF WEST VIRGINIA FINISmREMOVER CONTAINING METHYL ACETATE No Drawing.

: One of the common paint and varnish removers, which is considered'as having good efficiency, is a mixture of about equal parts of benzol and acetone, carrying three to four ounces of parafiin wax per gallon.

While such a composition produces a relatively high speed remover, it is desirable to produce a remover which will be still faster, ecause increase in speed of a remover, i. e.,

faster cutting power, will result in a saving not only of time but also a saving in the amount of remover necessary to clean a given area of a painted surface. The activity of a paint and varnish remover is usually tested in the trade by a means which is not absolutely reliable but nevertheless is usually sufiiciently convincing to the user. This method involves ap-. plying some of the removing composition to r a dried coating of paint or varnish and noting the time taken for the surface to wrinkle. The quickness of securing. this wrinkling effect is regarded, as an indication of the solvent action or cutting power of the removing composition.

Solvent mixtures vary greatly in cutting power. In removers involving the use of a penetrating hydrocarbon, such as benzol, and

a loosening alcoholic solvent, a very great 40 variation is observable in the cutting action,

depending upon the choice of solvents.'

Practically speaking, benzol has usually been regarded as the best and cheapest penetrating hydrocarbon. Acetone is a readily 43 available and effective ketone body. Such a Application filed November 30, 1928. Serial No. 322,869.

composition with a few ounces of paraflin wax per gallon will have a cutting or softening action which might be designated by the figure 100. If the acetone is replaced by ordinary 95% wood alcohol the rating of re mover will be in the neighborhood of say 130 (i. e. requiring 1.3 times as long to produce the softening). If ordinary 95% denatured alcohol is used the rating will be about 160. The figures indicate (by inverse ratio) the relative speeds, the acetone remover being the most active.

While this maybe suflicient for the ordinary testing by the customer, a more exact method of comparison would be desirable in rating the removing action of various solvents. For this purpose when working on the present problem I adopted the following" procedure: A piece of old painted wood was selected taking care that the portion used 5 had a good even, thick coat of paint. This was'cut into strips. Various solvents were placed in a series of test tubes and a strip of pa nted wood was put into each test tube. The time which elapsed before the first appearance of any'wrinkling was noted accurately by astop watch for each solvent (simple or mixed) being tested. The comparative removing action was thus roughly represented by the number of seconds.

Methyl acetate, and particularly a grade which is substantially free from water, produces a substantial increase in'the cutting power of a remover as compared with remover of a similar character but usingacetone instead of methyl acetate.

In order to secure the quickest possible action for a paint-and varnish remover, the

cutting power of various single solvents of 35 different natureswas first investigated, tuming then to a mixture oftwo solvents, three sfilvents, and so forth. (These are solvents only, no wax or other thickener being added.)

The results of this investigation are tabulated below, the tests being conducted on painted strips as described above:

Table 1 Cutting Single solvents power- 7 seconds Benml 3, 600 Chlorobenzol 400 'Irlchlorethylene 360 Petroleum ha No actizrln 0 1, 0 0 2. 400 80 Lugosol,(a mixed condensat n roduct o ned by treatment of acetone with a smal amount (say 0.03%)

of caustic soda, neutralizing the product and remov ng the unconverted acetone. This solvent has a bo1l1ng range [ram up to 170 C.) 45 Methyl ethyl ketone 75 Mesltyl nxlrle 210 Furfura 300 Methyl acetate 8O Ethyl nnatnfn 105 "Methyl cellosolve" (methyl ether of ethylene glycol).. 90

Binary mixtures (in equal parts) Benzol and anhydrous methyl alcohol 45 Benlol and anhydrous ethyl alcohol"--. 150 House] and acetone Benzol and methyl ethyl ketone. 55 Benzol and furlural 90 Benzol and methyl acetate- 45 Benzol and ethyl acetate 75 Chlorobenzol and methyl acetate- 0 Trlchlorethylcne and methyl acetate 35 Petroleum naphtha and methyl acetate 110 Anhydrous methyl alcohol and methyl acetat 25 Acetone and methyl acetate 90 Lugosol and methyl acetate 45 Methyl ethyl ketone and methyl acetate.-- 40 "Methyl ce losolve" and methyl acetate 35 Ternary miziurea (in equal parts) Ilenzol, anhydrous methanol and methyl acctate 28 Benzol, lugosol and methyl acetate.- 15 Benzol, anhydrous methanol and "lugoso 35 Benzol, anhydrous methanol and acetone 60 Benzol, acetone and methyl cellosolve 32 Benzol, methyl acetate and methyl cellnsolve" 25 Petroleum naphtha, anhydrous methanol and methyl acetate 52 Petroleum naphtha, lugosol and methyl acetate"..- 32 Petroleum naphtha, lugosol and ethyl acetate 125 automobile covered with a good layer of aged oil paint and the activity or the cuttingspeed of the remover was measured by noting the time when uniform wrinkling or blistering of the finish was plainly visible. The time was measured in seconds and the number of seconds obtained in each case was adopted as a criterion of the efiiciency of the remover.

'All figures given below concerning the rating V of removers were obtained by this method.

In addition to high elliciency or high cutting power, a good paint and varnish and lacquer remover should possess the property of slow-drying, that is, a paint and varnish remover when placed in a relativey thin layer on a painted or lacquered surface shouldresupport by means of a swab or an ordinary putty knife. If a remover dries too fast the result will be an insufficient softening action and it will therefore be necessary to use too large a quantity of remover to soften a given area to the desired degree. For extreme service conditions a remover should not lose more than about 5% of its weightif a layer of about 7 mm. thick is allowed to stand in an open dish exposed to the action of the air at a temperature around 75 F. for twenty-four hours. In order to fulfill the conditions of slow evaporation, it is customary to add to a removing composition a substance, such as wax, which is capable of dissolving in one of the solvents (hereinafter called wax solvent for brevity) and which at the same time is precipitated from the solution therein, by another solvent of the removing mixture (hereinafter called wax-precipitant or brevity). Under these conditions such removing composition will form a surface-skin or film which will afterwards act as a retarder of evaporation. Paraffin and ceresin Waxes are the mostwidely used substances of this kind eitheralone or in the presence of a protective coloid, such as cellulose esters or soaps. Other waxes or retarders can be used.

Methyl acetate as the sole solvent, in spite of its high power, presents the disadvantage of being too volatile. For example, methyl acetate in the presence of 1% of parafiin wax (towards which methyl acetate has a slight solvent action which is indicated by the fact that upon digestion of a small amount of wax in this medium the formation of a protective skin is observable) has the following rate of exaporation at 72 F. as expressed by loss in weight in per cent of original weight of the sample (containing 1% wax):

Per cent In 30 minutes, loss in weight 19 In 60 minutes, loss in weight 45 In 120 minutes, loss in weight 6-1 Such a high loss by evaporation indicates the presence of an ,abortive or poorly-functioning protective film, an obstacle in the way of using this solvent as the sole solvent in a paint and varnish remover.

Observation on the rate of evaporation of paint and varnish removing mixtures shows that one of the essential conditions for a low rate of evaporation is the choice of solvents in the remover having proper volatilities, relative to each other. If the volatility of V the wax precipitant is higher than the volatility of the wax solvent, the rate of evaporation will be high even with a large proportion of evaporation retarding material. This can be explained by the fact that under these conditions when evaporation starts the wax precipitant willvolatilize more rapidly. Therefore the ratio of the wax solvent to wax precipitant in the mixture will increase and consequently more wax will enter into solution, thus destroying or weakening the surfacefilm, and this film impairment will be augmented as evaporation progresses.

It should be mentioned, however, that the above observation is true only when solvents introduced into paint and varnish remover mixtures do not form those constant boiling, or constant volatilizing mixtures, which obmin with benzol and alcohol, or benzol, alcohol and acetone mixtures. In this latter case formation and stability of surface-film depends chiefly upon the proportion of wax in the mixture and possibly in part upon. the proper allotropic form taken by the precipitated wax, favoring formation of flakes in preference to needles in the case of parafiin wax. Such mixtures may be composed. of:

E mample 1 (for comparison) Parts Benzol 50 Anhydrous methanol Acetone 25 Parafiin wax 2 In spite of the fact that acetone and methyl alcohol (considered separately) have a higher degree of volatility than benzol, the rate of evaporation of this composition is very low amounting to about 2% loss in weight intwenty-four hours on exposure to the air at a temperature around C. and a thickness of layer of about 7 mm. This is because methyl, alcohol forms constant boiling (or constant evaporating) mixturesboth with benzol and acetone, which result in mutuality of evaporation of allthree solvents, thus preserving sufiiciently well the initial equilibrium between wax, wax solvent and wax precipitant.

If a wax solvent is introduced which does not form a uniformly evaporating mixture (but is less readily volatile than the wax precipitants), the above observation regard ing the relation between the volatility of wax solvents and wax precipitants begins to show its influence. For example If benzol in Examplel is replaced by toluol. the rate of evaporation will be increased. l/Vith thebenzol-containing mixture of Example 1 the loss in weight under the conditions of thetest outlined in this example after half an hour was not over 0.2%, and after two hours exposure was a little over 1%. The loss in weight with the toluol-oontaining mixture during half an hour was about 7% and in two hours, was about 20%.

he Replacing acetone of Example 1, by

meth l acetate, the rate of evaporation was foun to be a proximately the same as in Example 1; t. at is, the loss in weight is very small with benzol as the wax solvent, increasing with an increase in boiling point (lowervolatility) of the hydrocarbon wax solvent.

In a formula containing benzol, methyl alcohol and methyl acetate (Example 3), the alcohol forms constant boiling mixtures both with benzol and with methyl acetate, which result in mutuality of evaporation of all three solvents, similarly to the case of benzol, methyl alcohol and acetone mixture.

In other words in such cases methyl acetata may be substituted for acetone without disturbing the uniformity of evaporation, (and without substantially increasing the rate of evaporation of the remover solvents as a Whole). The remover of Example 3, has a higher cutting power than that of Exam le 1, the methyl acetate is therefore a use 111 potent ingredient to improve the cutting speed of this type of remover. As in the case of acetone, when a light benzolic hydrocarbon solvent, such as benzol, is replaced by a heavier one, such as ,toluol or xylol, the rate of evaporation will be much higher. Some formulas of this type are given below:

Example 2 Parts Benzol 50 Methyl acetate 25 Acetone 25 Paraffin wax 2 Cutting speed, 135 seconds as against 150 seconds for the remover composition given in Example Per cent Loss in weight in 2 hrs 1 5 Loss in weight in 24 hrs. a little over--- 3 When benzol wasreplaced by toluol, the composition of the remover then being:

No loss in weight in 2 hours. Only about 1.5% loss in weight in 24 hours.

Cutting speed seconds Part:

Toluol 5O Methyl acetate 25 Acetone 25 Paraffin wax 2 Loss in weight in 2 hours was about 25%. Ewample 3 Parts Benzol; 50

'Methyl acetate 25 Anhydrous Inethanol 25 Paraffin wax 2 tility higher than (or as high as) such a wax precipitant is not possible, the rate of evaporation can be reduced measurably by the introductlon together with such a low highly volatile precipitating solvent, of a suitable proportion of another wax precipitant with a volatility lower than the volatility of the wax solvent. The use of such a supplementary solvent thus serves as a corrective of the rate of eva oration. Accordingly, in cases when methy acetate has a tendency to volatilize ahead of and independently from the wax solvent, a satisfactory rate of evaporation may be obtained in two difierent ways: In one case some very volatile wax solvent, having volatility higher than methyl acetate,

such as petroleum ether, or carbon bisulphide, can be used as the wax solvent. In the other case, when a less volatile wax solvent is employed, a supplementary wax precipitating solvent of lower volatility than methyl acetate, will be used to' suppress the high rate of evaporation due to the tendency of methyl acetate to volatilize ahead of the wax solvent. As illustrative of the first of these two cases, I have obtained a remover with a rather low rate of evaporation when using a mixture of methyl acetate, acetone and light petroleum ether, as for instance:

Emmple 4 Parts Petroleum ether (B. P. 4060 C.) 50 Acetone 25 Methyl acetate 25 Para n wax 2 Loss in weight in 2 hours, about 10% as against 59% loss in weight within same period of time when the composition contained petroleum distillate (B. P. (SO-85 C.) in place of etroleum ether.

owever, in such cases, when very volatile hydrocarbon wax solvents are usedthe removing mixture will possess a high degree of infiammability and if this should be undesirable for the purposes in hand, the other mode of repression of the rate of evaporation may be followed, namely by introducing along with highly volatile wax precipitants another wax precipitant, with a volatility lower than that of the wax solvents. This modification may be illustrated with a mixture containing high boiling chlorinated hydrocarbons and methyl acetate.

Ewample 5 (unbalanced remover) Trichlorethylene 40 parts Methyl acetate 20 parts Acetone 30 parts Paraffin wax -4 2 parts Loss in weight in 24 hours, around- Example 6 The replacement of acetone with lugosol, a solvent which is a mixture of acetone condensation products by alkali) having a boiling range from 60-1 C., resulted in a very great suppression of the rate of evaporation, for example:

Trichlorethylene 40 parts Methyl acetate 20 parts Lugosol 30 parts Paraffin wax 2 parts Loss in weight in 24 hours 2% Example 6 differs from Example 5 onl by substitution of the higher boiling lugosol wax-precipitant for acetone. Yet the rateof evaporation has been enormously improved. Acetone alone ac'ts as an evaporation-stimulating agent for methyl acetate. Mixed with its higher boiling condensation products (as lugosol) an evaporation-sup ressing tendency'becomes distinctly evident. Ve thus have the curious phenomenon of a fairly volatile solvent (lugosol) cooperating with the wax in the repression of evaporation of a still more volatilesolvent (methyl acetate). Utilizing this phenomenon I am able to produce paint, varnish and lacquer removers in practical form from solvents of moderate cost but highly effective as a cutting agent of a composite nature.v The ad dition of evaporation suppressing solvents, such as lugosol, methyl ethyl ketone, and the like, to mixturesv containing acetone and methyl acetate, will ermit the utilization of the advantage of igh solvent power of methyl acetate in cases when the use of methyl acetate would otherwise be prohibitive on account of high eva oration.

In discussing met yl acetate as a desirable ingredient of a paint and varnish removing composition, there should also be mentioned another advantage of this material, es eci ally important in cases when the use 0 benzol as a wax solvent is not desirable. Petroleum hydrocarbons, such as light petroleum distillates, are satisfactory wax solvents and can sometimes beused in paint removing compositions in place of benzol. However, such a hydrocarbon solvent very often resents a difiiculty owing to its poor miscibility with other solvents, especially in the. presence of wax. It is known that petroleum hydrocarbons with an increase in their boiling point become more and more diificultly miscible with such solvents as alcohol, acetone and the like. While petroleum ether, for example, is very easily miscibile with methyl alcohol, petroleum distillate having a boiling point around 100 is not readily miscible with this solvent. Light petroleum distillate, which was mentioned as a substitute for benzol as a wax solvent and which had a boiling range between (SO-85 0., is miscible with methyl alcohol and'acetone in its pure state but separates from the mixture immediately upon the addition of even traces of wax. Methyl acetate has a very attractive property in this connection in that it serves as a blending agent for these two mixtures and therefore presents the possibility of employing powerful loosening solvents in con unction with petroleum hydrocarbons, a feature which is particularly desirable in this case in view of the poor removin action of petroleum hydrocarbons themse ves.

In addition to serving as a blending agent for a wax-containing mixture of petroleum hydrocarbons and an immiscible solvent, such as acetone or methyl alcohol, the anhydrous methyl acetate apparently acts in such mixtures very much as methyl alcohol acts in the mixtures with benzol and acetone, that is, it formsfa mixture which has a tendency toward a uniform evaporation. Under the term uniform evaporation I mean that when such a mixture is exposed to the air, all ingredients evaporate simultaneously, hence the composition of the solvent mixture is not altered.

When a mixture of equal parts of methyl acetate and light petroleum hydrocarbons to seventy-five hours. After, seventy-five hours of exposure, all samples containing mixtures of solvents were analyzed for the purpose of determining. the relative proportion of hydrocarbon and loosenin solvent. In all cases when the loosening so vent is a water soluble one the determination was made by measuring the oil layer, separated after the sample had been diluted with a definite amount of water. In all cases when a mixture contained a water insoluble loosening solvent, such as methyl acetate, the analysis was made in the following way: 15 cc. of a mixture was taken with 25 cc. of 10% alco holic solution of caustic potash. The mixture was boiled under a reflux condenser for one hour, diluted with water and the volume of the upper oil layer was measured. To check this determination the aqueous layer was separated out and was titrated with standard acid and the amount of alkali con sumed was used for calculating the ester (e. g. methyl acetate).

Composition of solvent mix- Loss In volume m tures at the end No; i Solvent Amount Ratiooi hydro- Tomi hydro- 15 hrs. 60 hrs. hrs. carbon carbon (ieterloosening mined; solvent 1 40 cc. Methyl acetate 3 cc. 6 cc.

40 cc. Petroleum distillate 2 cc. 4. 5 40 cc. mlxleggg. methyl acetate and petro eum dis- 5 m I m cm 868 mm. I 40 'Flanml 1. 0 2. 0 4. 0 40 cc. Methanol 2. 0 4. 0 6. o 40 cc. mixture benzol and mama... 3.0 e. o 10.0 15 cc. so 40 cc. A Fatima is. 0 c. o 10. 0 40 cc. Petroleum distillate 2. 0 4. 5 6. 0 40 cc. mixture acetone and petroleum distillate 4. o a 0 13. o 16 co. 27 i 40 w. Mainannl 1. 0 2. 0 i3. 0 w 40 cc. Petroleum distillate 3. 0 e. o 10. o 40 co. mixture methanol and petroleum comma s. 5 a 5 1a a 15 cc. a; a

(boiling between 60 and (3.), was kept in an open graduated cylinder, and the same amount each of methyl acetate and petroleum hydrocarbons were placed separately in grad uated cylinders of the same size, the three cyl inders all placed beside each other and allowed to stand at room temperature, all under identical conditions, the loss of solvents was uniform in each cylinder, but not alike in the three cases, as is illustrated in the table given below. 7

In another series of tests, this same mixture of light petroleum distillate and acetone, in one case, and the same petroleum ditillate and anhydrous methanol, in another case, were tested. In order to examine the behavior of a constant boiling mixture under the cam conditions of the test, a mixture of bonsai an methanol (in comparison with benaol .nl methanol separately) was also The results of all tests are given in the table below. The total time of evaporation was up KOH heated in a pressure bottle for 1 hour, diluted with water-oily layer=4.8 cc.

c. 15 cc. mixture, shaken with alcoholic KOH (25 cc?1 (exactly 10% solution), boiled under a reflux, diluted wit water-oily 1ayer=7.2 cc. Aqueous layer titrated for consumed KOH and result calculated for methyl acetate. Amount found 6.9 gr. or about 7.0 cc.

Examination of the table shows that methyl acetate volatilizes together with light petroleum hydrocarbon very much similarly to the bcnzol and alcohol mixture.

Taking into consideration that methyl acetate forms a constant boiling mixture with methyl alcohol, the behavior of methyl acetate in admixture with petroleum hydrocarhon can becompared with the action of methanol in the mixture containing benzol, methanal and another solvent, such as acetone, i. e, the methyl acetate in the case of petroleum acts as an equalizer of evaporation. This explains the results of Example 7 given below, which otherwise may seem contradictory to the above-mentioned rule regarding the influence of the relative volatility of solvents upon the rate of evaporation. In this case methyl acetate when mixed with petroleum distillate of the above boiling range acts as an equalizer of evaporation in such a way that the wax precipitant and the wax solvent evaporate together, thus producing a properly balanced removing composition.

Some examples of this type of remover, i. e., remover containing petroleum hydrocarbons as a wax solvent, are given below. It is understood that in all examples given in the presentappli'cation I do not want to restrict myself to the exact proportion of ingredients, such proportions should be regarded merely from the standpoint of illustration.

Example 7 Light petroleum distillate (B. P.

range 6080 C.) 30 parts Anhydrous methanol; 30 parts Anhydrous methyl acetate 40 parts Parafiin wax 2 parts Loss in weight in 24 hours 1% Cutting speed 120 seconds Ewample 8 Distillate from casinghead na htha (B. P. range 60 C. to 115 30 parts Lugosol '50 parts Anhydrous methyl acetate 50 parts Paraffin wax 3 parts Loss in weight in 24 hours 6.8% Cutting speed 210 seconds In all the examples the proportions are given by volume, including wax, which was measured in the molten state.

What I claim is 1. A waxy-bodied finish solvent remover containing wax and a wax solvent and containing substantially anhydrous methyl acetate, the methyl acetate amounting to at least 20% of the entire bulk of solvents in said remover, the Whole remover having an evaporation loss in 24 hours, exposed to the air at room temperature, not considerably over 5%. Y

2. A waxy-bodied finish remover, stablein-storage, such remover comprising a wax and a composite solvent, the solvent being composed of petroleum hydrocarbons substantially all distilling at not above 85 0., as a wax solvent and a mixture of organic wax precipitants comprising a substance selected from the herein described group 0011- sisting of methyl alcohol, acetone and 'lugosol, together with methyl acetate, the latter serving as a blending agent for the wax precipitants not readily miscible with said hydrocarbons in the presence of wax, and

also serving as an equalizer of volatility, the methyl acetate being at least 20% of the total remover solvent, the wax precipitants being in amount at least as great as the petroleum hydrocarbons, and such remover when exposed as a thin film to the atmosphere at room temperature for 24 hours shows an evaporation loss not substantially over 6.8%.

3. A finish remover containing wax, a wax solvent consisting substantially of readily volatile petroleum hydrocarbons substantially all distilling at below 115 C., and a wax precipitating loosening solvent material which normally is not readily miscible with the said wax solvent in the presence of wax, and substantially anhydrous methyl acetate which serves as a blending agent for the petroleum hydrocarbons and said loosening solvent material in the presence of wax, an which also has itself'a strong solvent action on dried finish coatin s, said methyl acetate constituting at least a out 20% of the total remover solvents.

4. A wax-bodied finish remover containing methyl acetate in amount at least equal to 20% of the entire amount of solvents in the remover, other organic solvents which are wax precipitants selected from the herein described group consisting of acetone, lugosol and methanol, a waxy evaporation retarding material, and a wax solvent selected from the herein described group consisting of benzol, petroleum ether, light petroleum distillate distilling between about 60 and about 85 0., and trichlorethylene, such complete remover having an evaporation loss, when exposed to the atmosphere at normal room temperature of not substantially above 6.8% in 24 hours.

-5. A wax-bodied finish remover containing methyl acetate in amount at least equal to 20% of the'entire amount of solvents in the remover, at least one other organic solvent which is a wax recipitant selected from the herein described class consisting of methyl alcohol, acetone and lugosol, a waxy evaporation retarding material, and a wax solvent selected from the herein described group consisting of benzol, petroleum ether, light petroleum distillate distilling between about 60 and about 85 O., and trichlorethylene, such complete remover having an evaporation loss, when exposed to the atmosphere, at normal room temperature of not substantially above 5% in 24 hours. I

6. A finish remover having the following formula- About 50 parts 7. A finish remover having the following w Petroleum I hydrocarbons boiling point range 60 to 85 C About parts Anhydrous methanol About 30 parts m Anhydrous methyl acetate- About 40 parts "Wax About 2 parts In testimony whereof I aflix my signature.

BORIS N. LOUGOVOY,