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Claims  |
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I claim:
1. A composition for stripping a polymeric coating from a surface
consisting essentially of:
a. about 10% to about 60% by weight of a terpene compound;
b. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidines;
c. about 2% to about 20% by weight of a terpene emulsifying surfactant; and
d. about 10% to about 60% by weight of a high flash point, high KB solvent
selected from the group consisting of ethylene carbonate and propylene
carbonate.
2. The composition according to claim 1 wherein said solvent is propylene
carbonate.
3. The composition according to claim 2 wherein said compound (b) is
N-methylpyrrolidone.
4. The composition according to claim 3 further comprising about 5% to
about 15% of a solvent extender or bulking agent.
5. The composition according to claim 4 wherein said surfactant is a
phosphate ester surfactant.
6. The composition according to claim 4 wherein said surfactant is an
alkaline stable mixture of mono and di-substituted phosphate esters of
decylalcoholethoxylate.
7. The composition according to claim 5 wherein said surfactant is a
phosphate ester of a long-chain alcohol ethoxylate.
8. The composition according to claim 6 wherein said terpene is dipentene.
9. The composition according to claim 8 further comprising an odor-masking
compound.
10. The composition according to claim 9 wherein said odor-masking compound
is d'limonene.
11. The composition according to claim 4 wherein said solvent extender or
bulking agent is ethanol or isopropanol.
12. The composition according to claim 1 additionally comprising between
about 0.5% and about 20% by weight water.
13. The composition according to claim 8 wherein said composition comprises
about 1% to about 5% by weight water.
14. The composition according to claim 12 further comprising about 0.02% to
about 5% by weight of a thixotropic agent.
15. The composition according to claim 14 wherein said thixotropic agent is
selected from the group consisting of hydroxypropylcellulose, methyl
cellulose and ethyl cellulose.
16. The composition according to claim 15 wherein said thixotropic agent is
ethyl cellulose.
17. The composition according to claim 16 wherein said thixotropic agent is
in the form of a microgel.
18. The composition according to claim 1 further comprising isopropanol,
water, ethyl cellulose, N-methylpyrrolidone and d'limonene and wherein
said terpene is dipentene and said surfactant is a phosphate ester
surfactant.
19. The composition according to claim 18 having a pH ranging from about
6.0 to about 8.0.
20. An impregnated applicator for us in stripping a polymeric coating from
a surface comprising:
1. a paint stripping composition consisting essentially of:
a. about 10% to about 60% by weight of a terpene compound;
b. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidines;
c. about 2% to about 20% by weight of a terpene emulsifying surfactant; and
d. about 10% to about 60% by weight of a high flashpoint, high K.sub.B
solvent selected from ethylene carbonate and propylene carbonate; and
2. a fabric piece comprising material stable to said stripping composition,
wherein said composition is absorbed to said fabric pieces.
21. The applicator according to claim 20 wherein said fabric piece
comprises non-woven, highly absorbent fabric containing an absence of
chemical binders.
22. The applicator according to claim 20 wherein said fabric is selected
from the group consisting of polyester, cellulose/propylene,
rayon/polyester and woodpulp/polyester.
23. The applicator according to claim 20 wherein said solvent is propylene
carbonate.
24. The applicator according to claim 20 wherein said solvent is propylene
carbonate.
25. The applicator according to claim 24 further comprising about 5% to
about 15% of a solvent extender or bulking agent.
26. The applicator according to claim 20 wherein said surfactant is a
phosphate ester surfactant.
27. The applicator according to claim 25 wherein said surfactant is an
alkaline stable mixture of mono and di-substituted phosphate esters of
decylalcoholethoxylate.
28. The applicator according to claim 26 wherein said surfactant is a
phosphate ester of a long-chain alcohol ethoxylate.
29. The applicator according to claim 25 wherein said terpene is dipentene.
30. The applicator according to claim 29 further comprising an odor-masking
compound.
31. The applicator according to claim 30 wherein said odor-masking compound
is d'limonene.
32. The applicator according to claim 25 wherein said solvent extender or
bulking agent is ethanol or isopropanol.
33. The applicator according to claim 25 additionally comprising between
about 0.5% and about 20% by weight water.
34. The applicator according to claim 33 wherein said composition comprises
about 2% to about 5% by weight water.
35. The applicator according to claim 33 further comprising about 0.02% to
about 5% by weight of a thxiotropic agent.
36. The applicator according to claim 35 wherein said thixotropic agent is
selected from the group consisting of hydroxypropylcellulose, methyl
cellulose and ethyl cellulose.
37. The applicator according to claim 36 wherein said thixotropic agent is
ethyl cellulose.
38. The applicator according to claim 36 wherein said thixotropic agent is
in the form of a microgel.
39. The applicator according to claim 20 having a pH ranging from about 6.0
to about 8.0.
40. The applicator according to claim 20 further comprising propylene
carbonate, ethanol, water, ethyl cellulose, N-methylpyrrolidone and
d'limonene and wherein said terpene is dipentene and said surfactant is a
phosphate ester surfactant.
41. A method of making a paint stripper composition containing a microgel
comprising:
1. mixing a thixotropic agent in the presence of water and a solvent
extender or bulking agent to produce a microgel-containing suspension; and
2. adding said suspension to a mixture comprising:
a. about 10% to about 60% by weight of a terpene compound;
b. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidines; and
c. about 2% to about 20% by weight of a terpene emulsifying surfactant.
42. The method according to claim 41 wherein said mixture further comprises
about 10% to about 60% by weight of a high flash point, high K.sub.B
solvent selected from the group consisting of ethylene carbonate,
propylene carbonate, glycols and glycol ethers.
43. The method according to claim 42 wherein said solvent is propylene
carbonate.
44. The method according to claim 42 wherein said compound (b) is
N-methylpyrrolidone.
45. The method according to claim 42 wherein said surfactant is a phosphate
ester surfactant.
46. The method according to claim 45 wherein said surfactant is an alkaline
stable mixture of mono- and di-substituted phosphate esters of
decylalcoholethoxylate.
47. The method according to claim 45 wherein said surfactant is a phosphate
ester of a long-chain alcohol ethoxylate.
48. The method according to claim 42 wherein said terpene is dipentene.
49. The method according to claim 48 wherein said mixture further comprises
an odor-masking compound.
50. The method according to claim 49 wherein said odor-masking compound is
d'limonene.
51. The method according to claim 42 wherein said solvent extender or
bulking agent is ethanol or isopropanol.
52. The method according to claim 42 wherein the amount of water used
comprises between about 0.5% and about 20% by weight of the final
composition.
53. The method according to claim 52 wherein the amount of water comprises
about 2% to about 5% by weight of the final composition.
54. The method according to claim 42 wherein said thixotropic agent
comprises about 0.02% to about 5% by weight of the final composition.
55. The method according to claim 54 wherein said thixotropic agent is
selected from the group consisting of hydroxypropylcellulose, methyl
cellulose and ethyl cellulose.
56. The method according to claim 54 wherein said thixotropic agent is
ethyl cellulose.
57. The method according to claim 41 wherein said final composition
comprises propylene carbonate, ethanol, water, ethyl cellulose,
N-methylpyrrolidone, d'limonene, dipentene and a phosphate ester
surfactant.
58. The method according to claim 42 wherein said final composition has a
pH ranging from about 6.0 to about 8.0.
59. A method for removing a polymeric coating from a surface comprising:
1. applying to said coating an amount of a composition effective for
removing said coating, said composition consisting essentially of:
a. about 10 % to about 60% by weight of a terpene compound;
b. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidines;
c. about 2% to about 20% by weight of a terpene emulsifying surfactant; and
d. about 10% to about 60% by weight of a high flash point, high KB solvent
selected from ethylene carbonate and propylene carbonate;
2. contacting said composition with said coating for a period ranging from
about 20 minutes to about 90 minutes; and
3. removing said composition and said polymeric coating from said surface.
60. The method according to claim 59 wherein said solvent is propylene
carbonate.
61. The method according to claim 59 wherein said compound (b) is
N-methylpyrrolidone.
62. The method according to claim 59 further comprising about 5% to about
15% of a solvent extender or bulking agent.
63. The method according to claim 62 wherein said surfactant is a phosphate
ester surfactant.
64. The method according to claim 63 wherein said terpene is dipentene.
65. The method according to claim 62 wherein said solvent extender or
bulking agent is ethanol or isopropanol.
66. The method according to claim 62 wherein said composition further
comprises between about 0.5% and about 20% by weight water.
67. The method according to claim 66 further comprising about 0.02% to
about 5% by weight of a thixotropic agent.
68. The method according to claim 67 wherein said thixotropic agent is
ethyl cellulose in the form of a microgel.
69. The method according to claim 67 wherein said composition is removed
(step 3) by spraying with water.
70. The method according to claim 59 wherein said composition comprises
isopropanol, water, ethyl cellulose, N-methylpyrrolidone, d'limonene,
dipentene and a phosphate ester surfactant.
71. The method according to claim 59 wherein said composition has a pH
ranging from about 6.0 to about 8.0.
72. A method of removing a polymeric coating from a surface comprising:
1. applying to a polymeric coating an impregnated applicator comprising:
a. a stripping composition consisting essentially of:
i. about 10% to about 60% by weight of a terpene compound;
ii. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidones;
iii. about 2% to about 20% by weight of a terpene emulsifying surfactant;
and
iv. about 10% to about 60% by weight of a high flash point, high KB solvent
selected rom the group consisting of ethylene carbonate and propylene
carbonate; and
b. a fabric piece comprising a material stable to said stripping
composition, herein said composition is absorbed to said fabric piece;
2. contacting said impregnated applicator to said polymeric coating for a
time sufficient to remove said coating; and
3. removing said applicator from said surface.
73. The method according to claim 72 wherein said fabric piece comprises
non-woven, highly absorbent fabric containing an absence of chemical
binders.
74. The method according to claim 73 wherein said fabric is selected from
the group consisting of polyester, cellulose/propylene, rayon/polyester
and woodpulp/polyester.
75. The method according to claim 72 wherein said solvent is propylene
carbonate.
76. The method according to claim 75 wherein said compound (ii) is
N-methylpyrrolidone.
77. The method according to claim 72 wherein said stripping composition
further comprises about 5% to about 15% of a solvent extender or bulking
agent.
78. The method according to claim 77 wherein said surfactant is a phosphate
ester surfactant.
79. The method according to claim 78 wherein said terpene is dipentene.
80. The method according to claim 77 wherein said solvent extender or
bulking agent is ethanol or isopropanol.
81. The method according to claim 72 wherein said stripping composition
further comprises between about 0.5% and about 20% by weight water.
82. The method according to claim 72 wherein said stripping composition
further comprises about 0.02% to about 5% by weight of a thixotropic
agent.
83. The method according to claim 72 wherein said thixotropic agent is
selected from the group consisting of hydroxypropylcellulose, methyl
cellulose and ethyl cellulose in the form of a microgel.
84. The method according to claim 72 having a pH ranging from about 6.0 to
about 8.0.
85. The method according to claim 72 wherein said stripping composition
comprises ethanol, water, ethyl cellulose, N-methylpyrrolidone,
d'limonene, dipentene and a phosphate ester surfactant.
86. A composition for stripping a polymeric coating from a surface
consisting essentially of:
a. about 10% to about 60% by weight of a terpene compound;
b. about 10% to about 50% by weight of a compound selected from the group
consisting of pyrrolidones and pyrrolidines; and
c. about 2% to about 20% by weight of a terpene emulsifying surfactant. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention relates to non-toxic, non-flammable, safe
compositions employing primarily biodegradable components for use in
removing and stripping paint, varnishes and stains from hard and/or
flexible surfaces. The compositions avoid the use of methylene chloride,
methanol, toluol or acetone.
BACKGROUND OF THE INVENTION
With the introduction of new and more durable types of synthetic resins and
polymers in protective and decorative coatings, the problem of stripping
has become increasingly difficult. Prior art paint removers typically
contain blends of aromatic solvents, ketones, paraffin, methanol and
diluents, for example, mineral spirits in order to reduce raw material
costs. Those prior art strippers made with the foregoing solvents focused
industry attention on the flammable and toxic characteristics.
As an alternative, improved prior art solvents utilize chlorinated solvents
as a way to extend the usefulness of paint strippers while simultaneously
reducing fire hazards associated with their use. Methylene chloride
(dichloromethane) has been almost universally used as the solvent of
choice, although some compositions have been formulated with ethylene
dichloride and trichlorethylene, among other chlorinated hydrocarbon
solvents. Many of the chlorinated hydrocarbons including methylene
chloride are suspected carcinogens and methylene chloride is designated a
hazardous substance under the Federal Hazardous Substance Act (FHSA). In
addition, methylene chloride, as a high vapor pressure chlorinated
solvent, probably contributes to atmospheric ozone depletion. Methanol is
a poison if ingested and the U.S. Consumer Products Safty Commission
requires a warning designating it as a poison when its concentration in
consumer products exceeds 4 percent by weight. Toluene contains trace
quantities of benzene, a known carcinogen, and acetone with its high vapor
pressure and low flash point is highly flammable.
Paint strippers which include methylene chloride can be formulated to
soften, lift and blister paint films. The stripper which is applied to the
substrate by brush, immersion or spray and allowed to loosen the paint or
varnish has an available work life of only several minutes because of the
tendency of the methylene chloride to evaporate rapidly. Because of the
high vapor pressure of methylene chloride, in an effort to extend the work
life of the stripper made with that solvent, paraffin is often included as
an evaporation suppressant. The paraffin functions by forming a thin film
at the surface of the paint remover which retards evaporation. This thin
film formation and resultant evaporation suppressant activity of paraffin
is produced by the evaporation and surface chilling which occur when
methylene chloride or mixtures containing methylene chloride are exposed
to air. However, methylene chloride strippers must be handled carefully
since they are highly toxic and can cause severe skin irritation. Further,
even with the incorporation of paraffin, the volatility of the methylene
chloride is still very high and when methylene chloride is formulated
with, for example, toluene, the resulting high levels of hydrocarbon
emissions necessitate the provision of good ventilation to safely use the
methylene chloride paint strippers.
A further disadvantage of paint strippers formulated with methylene
chloride is that the short work life compromises the ability of the
stripper to function efficiently in many applications. For example, many
industrial uses of paint strippers involve stripping accumulated paint
from equipment and walls. Paint strippers utilizing methylene chloride,
suffer from the disadvantage that the short work life prevents the
stripper from entering crevices in the accumulated paint layers thus
creating the necessity, in some cases, of applying a large number of
applications of stripper to remove a number of accumulated paint layers.
Furthermore, the short work life of methylene chloride creates a recoating
phenomenon in which stripped paint recoats the surface of one of the
accumulated paint layers or the surface to be stripped as the solvent
evaporates.
To remove paint on vertical surfaces, a thickener is generally added to
avoid the problem of stripper flowing off the surface before it has had a
chance to remove the paint layer. It is preferable to add a thickener,
which in combination with the other stripper ingredients, may be easily
washed off the surface after the stripping has taken place. However, if a
paint stripper is too thick, it may be used on vertical surfaces, but it
may not be amenable to spraying. Furthermore, the use of methylene
chloride within the stripper may evaporate, thus producing a stripper
which varies greatly in viscosity as a function of the evaporation time of
the solvents in the stripper. Depending upon the required viscosity and
the compatibility of the paint stripper ingredients with the paint
stripper thickening system it may be necessary to reformulate the paint
stripper with each application. Because of their high flash point,
stripping compositions of the present invention may be adapted for a
number of applications by simply changing the amount and type of thickener
employed without modifying the other components.
OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide paint stripper
compositions which are safe and effective to remove paint and other
polymeric coatings in protective and decorative coatings on flexible and
inflexible surfaces.
It is also an object of the present invention to provide compositions which
are non-flammable and effective paint strippers which do not contain
petroleum based aromatic compounds, ketones or methanol.
It is an additional object of the present invention to provide stripping
compositions and methods for removing conventional lacquers, varnishes,
enamels, for example, drying oil type, alkyds, or drying oil-alkyd
modified enamels, epoxy esters, epoxy amides, amine-catalyzed epoxies,
acrylics and polyurethanes, among others.
It is a further object of the present invention to provide a method of
stripping polymeric coatings using the compositions of the present
invention.
It is yet another object of the present invention to provide a method of
making the compositions of the present invention, especially those
compositions which are thixotropic and utilize microgel formation.
It is still a further object of the present invention to provide efficient
paint stripping compositions which are pleasant, non-offensive in odor and
which do not emit harmful fumes.
It is yet an additional object of the present invention to provide an
effective paint and varnish removing composition which is non-caustic, has
a neutral pH and will not harm wood.
Still an additional object of the present invention is a stripping
composition that stays wet and active longer, may cover more surface area
than prior art compositions and strips through multiple layers of paint
and varnish.
SUMMARY OF THE INVENTION
These and other objects of the present invention are accomplished by paint
stripper compositions having flash points above about 120.degree. F. and
an absence of low-boiling VOC's comprising:
a. about 10% to about 60% by weight of a terpene compound containing at
least 10 carbon atoms;
b. about 10% to about 50% by weight of N-methyl pyrrolidone or its
equivalent; and
c. about 2% to about 20% by weight of a terpene emulsifying surfactant.
Compositions of the present invention may further comprise one or more of
the following: about 5% to about 15% by weight of a solvent extender or
bulking agent, about 10% to about 60% of a high flash point, high K.sub.B
(kauri-butanol) solvent selected from the group consisting of ethylene
carbonate, propylene carbonate, butylene carbonate, glycols and glycol
ethers, about 0% to about 20% water, from 0% to about 5% by weight of a
thixotropic or thickening agent, about 2% to about 20% by weight of an
odor masking component, for example d'limonene and mixtures, thereof.
Depending upon the desired pH of the compositions, a base or acid may
additionally be added to adjust the pH of the compositions of the present
invention. In addition, for certain industrial applications it has
surprisingly been found that the use of certain halogenated hydrocarbons
containing both chlorine and fluorine in an amount ranging from about 2%
up to about 40% results in compositions exhibiting especially advantageous
stripping efficiencies.
The paint stripper compositions of the present invention are safe,
effective and can be used in a wide variety of applications.
Environmentally safe, biodegradable compositions of the present invention
solve many of the problems associated with the use of low-boiling
chlorinated hydrocarbons in prior art paint strippers, including the
health hazards and environmental problems associated with the use of those
stippers. The compositions of the present invention have a high flash
point, preferably above about 93.degree. C. (200.degree. F.), are
generally biodegradable and can be formulated to be highly active in the
pH range of about 6.0 to about 8.0, a particularly useful advantage over
prior art compositions. In addition, certain embodiments of the present
invention provide the advantage that they can be used to treat a coated
surface and then removed by simply washing the treated surface with water.
In one particularly preferred aspect of the present invention, stripper
compositions of the present invention are adsorbed onto paper or fabric
sheets and used to strip paint and other coatings from a surface. Sheets
to which are adsorbed the compositions of the present invention are very
easy to handle and provide simple and efficient means to remove paint from
large surface areas, for example walls, doors and panels.
The compositions of the present invention can be used to strip or remove
conventional lacquers, varnishes, enamels, epoxy esters, epoxy amides and
acrylics, among other polymeric coatings. The time required to strip paint
finishes completely is competitive with that of conventional strippers
containing chlorinated solvents, and ranges from about 20 minutes to about
80 minutes, with a preferred range of about 20 to about 35 minutes.
In removing coatings from surfaces, the compositions of the present
invention produce a wrinkling or blistering of the polymer coating. While
not to be limited by theory, this fundamental blistering is believed to be
produced by swollen gel. When normally insoluble high polymers are placed
in contact with an active solvent, the polymer absorbs the solvent and
expands until an equilibrium condition occurs. In order to accommodate the
increased volume and still remain within the original surface perimeter,
the polymer tends to fold or wrinkle so as to relieve internal stresses.
The solvent mixtures solvate the active groups of the polymer, and in so
doing, reduce solid to solid adhesion. The forces which build up in the
polymer generally, as a result of a combination of swelling and weakened
adhesion, are sufficiently high to tear the film loose from the surface.
Wrinkle formation occurs because solvent penetration into the polymer and
deterioration of the polymer cohesive bonds proceed at approximately the
same speed. There is rapid parting of the film from the substrate and
almost as rapid rupturing of the film itself.
In the method aspects of the present invention, compositions of the present
invention are used to strip and/or remove polymeric coatings on a number
of surfaces. In a particularly preferred method of using the compositions
of the present invention, stripping composition preferably adsorbed to
fabric or paper is placed in contact with a coated surface and after a
period of time sufficient to soften and/or blister the underlying coating,
the paper is removed along with the softened coating in one easy step.
Depending upon the formulation of the composition to be used, further
method aspects of the present invention involve making the compositions of
the present invention using a stepwise procedure in which thixotropic
agents are mixed separately from the active ingredients. Certain
thixotropic compositions, for example methylcellulose, such as Methocel
311, available from Dow Chemical Corp. Midland, Mich., hydroxypropyl
cellulose, Klucell.TM., available from Hercules, Inc., Wilmington, Del.,
ethyl cellulose, such as Bermocol PR.TM., available from Seaboard Sales,
N.J.) and clays modified with quaternary compounds (high medium and low
polar), such as Bentone 27, a product of NL Industries, N.J., U.S.A.
containing from 0% to about 5%, preferably about 0.02% to about 5%, and
most preferably about 1 to about 3% of thixotropic agent preferably in
microgel form are made by producing the microgel separately from the
active components to prevent their encapsulation and then adding the
component in which microgel formation has occurred to the active
ingredients of the compositions. Microgel formation which occurs separate
from the other active agents in the compositions of the present invention
produces a composition exhibiting acceptable thixotropy for stripping or
removing polymeric coatings on vertical surfaces and enhanced stripping
activity. In addition, this method aspect of the present invention results
in a composition that is much easier to make than compositions in which
microgel formation occurs in the presence of the active ingredients and
the quality control of which can be easily monitored.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of the present invention comprise from about 10% to about
60% by weight of a terpene compound. As used herein, the term terpene
refers to a class of acyclic and cyclic unsaturated compounds derived from
natural essential oils and resins having at least 10 carbon atoms.
Terpenes that find use in the present invention include alcohols and
aldehydes as well as unsaturated hydrocarbons. Any number of terpene
compounds, including combinations of these terpenes may be used in the
present invention as the base or primary solvent as polymer absorbents.
Preferred terpene compounds are those compounds which have a K.sub.B value
of at least about 108 (the same value as toluol, an aromatic hydrocarbon
which is the solvent of choice in many prior art strippers) and a flash
point above about 120.degree. F.
K.sub.B is a measure of the solvency of a hydrocarbon. In general, the
higher the K.sub.B value, the greater the general solvent power of the
hydrocarbon under test conditions described by ASTM
D1133. To determine K.sub.B value, a hydrocarbon sample is added to a
standard solution of kauri gum in butyl alcohol until sufficient kauri gum
precipitates to blur vision of 10 point type viewed through the flask.
When used in varnish, lacquer and enamel formulations, a hydrocarbon
diluent with a high K.sub.B value dissolves relatively large quantities of
solids.
The preferred terpene compounds for use in the present invention are
represented by unsaturated hydrocarbons, alcohols and aldehydes having at
least 10 carbon atoms and include 3,7-dimethyloctanol, alpha-pinene,
beta-pinene, delta-3-carene, citronellal, citronellol, hydroxycitronellal,
d-limonene, linalool, gamma-terpinene, tetrahydrolinalool and terpineol,
among others, with cyclic terpenes being preferred. Especially preferred
terpenes for use in compositions of the present invention include
dipentene, because of its high K.sub.B value. A preferred mixture of
terpenes for use in the present invention includes Pine Oil.TM. from
Glidco (Jacksonville, Fla.) because of its very high K.sub.B value (500)
and its relatively high boiling range (190.degree. C. to 222.degree. C.).
Pine Oiltm contains a number of terpine alcohols and terpene hydrocarbons,
including high percentages of alpha-terpineol.
Compositions of the present invention comprise about 10% to about 60% by
weight of a terpe | | |
