JPS61233539A - Polyester film laminate and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a polyester film laminate and a method for producing the same, and more particularly to highly processed products such as audio magnetic tape, video magnetic tape, computer magnetic tape, The present invention relates to a polyester film laminate having excellent adhesiveness and solvent resistance, useful as a base material for floppy disks, X-ray photographic films, etc., and a method for producing the same.

BACKGROUND OF THE INVENTION It is known to melt extrude and form films from thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends thereof with small proportions of other resins. It is also known that the resulting two-wheel stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since the surface is highly crystal oriented, the surface has high cohesion and poor receptivity to paints, adhesives, inks, and the like.

Therefore, when a synthetic resin layer is provided on the surface of such a polyester film, for example, the surface of the film is subjected to a corona discharge treatment in order to strengthen the adhesion between the two.

A method is used in which the surface is activated by ultraviolet irradiation treatment, plasma treatment, or flame treatment and then coated with a synthetic resin coating. However, although these methods of activating the film surface can be expected to improve adhesion to the coating layer by increasing the secondary bonding force due to wetting,
Its activity decreases over time. Therefore, these means of activating the film surface are not necessarily satisfactory.

As another method for increasing the receptivity of the polyester film surface, an etching method has been proposed in which the surface is swollen or partially dissolved with various agents.

This involves etching the film surface by bringing it into contact with chemicals such as acid, alkali, amine aqueous solution, trichloroacetic acid, or phenols, thereby decomposing, dissolving, and relaxing the crystal orientation near the surface, and at the same time reducing cohesion. This is intended to increase the adhesiveness with the binder resin by reducing the adhesiveness, and its effect is most reliable, and the adhesiveness between the film and the layer provided thereon, such as a synthetic resin coating layer, becomes strong.

However, some of the chemicals used in this method are harmful and may be dangerous to handle, and there is a risk that volatile substances from the chemicals may be released into the atmosphere. There are various disadvantages from a practical point of view, such as the need to be careful.

As a method similar to this method, a primer layer (undercoat layer) is provided on the surface of the film in advance, a thin surface layer different from the base film is formed, and then a desired layer, such as a synthetic resin layer, is coated. be. When forming the undercoat layer, a coating process is usually performed in a process different from the polyester film forming process. However, highly processed products such as audio magnetic tape, video magnetic tape, and computer magnetic tape.

In applications where precision and delicate quality must be maintained, such as floppy disks, X-ray photographic film, photographic film for printing, and diazo microfilm, the resulting film may be contaminated with dust even if an easily adhesive surface is successfully formed. If surface defects are present, the base film cannot be used for these purposes, but this defect is likely to occur in this separate process. Therefore, it is desirable to perform the undercoating process in an atmosphere as free from dust as possible. There is a polyester film forming process that satisfies these conditions, and if undercoating is performed in this process, it will be possible to obtain a product that can be fully used for the above-mentioned advanced film processed products.

On the other hand, in the prior art, methods of modifying the surface of a polyester film to make it easily adhesive by treating the surface with a primer have in most cases been achieved by applying a composition dissolved in an organic solvent to the surface layer of the film. Ta. If such methods are carried out during film production, contamination of the surrounding environment by fugitive organic solvents.

The use of organic solvents should be kept to a minimum as much as possible, as this may lead to unfavorable conditions in terms of safety and hygiene and adversely affect the film forming process. Therefore, when performing in-line subbing treatment in the film forming process, it is preferable to use a composition using water as a solvent from the viewpoints of process, economy, and safety. Therefore, many primer compositions using water as a solvent have been proposed, and in particular, many proposals have been made for aqueous solutions or dispersions of polyurethane or polyester.

For example, Japanese Patent Publication No. 4B-10193 discloses the use of polyurethane having solvent resistance to acetone and water dispersibility.

However, these primer compositions swell or dissolve in solvents used in magnetic coatings, such as methyl ethyl ketone, cyclohexanone, tetrahydrofuran, etc., and are insufficient in terms of solvent resistance. When a highly polar paint such as a magnetic paint is applied on such a primer layer, the primer layer and the magnetic layer are mixed, which not only reduces the adhesion effect of the primer layer but also causes flow on the surface of the coated layer. A good coated surface cannot be obtained.

Particularly in recent years, recording densities have been increasing in coated magnetic recording media, and magnetic layers are becoming thinner. In particular, the film thickness of floppy disks has rapidly become thinner, and the film thickness has been reduced to about 1 μm.

When the magnetic layer becomes thin like this, it is not preferable because the above-mentioned flow that occurs on the surface of the magnetic layer makes it difficult to obtain a good magnetic surface and causes deterioration of electromagnetic conversion characteristics.

OBJECTS OF THE INVENTION An object of the invention is various coatings applied to polyester films, such as cellophane inks.

Magnetic paints, gelatin compositions, offset inks.

It has excellent adhesion to electrophotographic toners, chemical matte paints, diazo paints, heat-sealable compositions, inorganic film-forming substances, etc., and does not cause peeling when these coatings are applied. It is an object of the present invention to provide a polyester film laminate coated with a single layer of primer having stable solvent resistance that is not affected by drying conditions of a coating solution. Another object of the present invention is to provide a preferred method for producing such polyester film laminates.

According to the present invention, an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group and a sulfuric acid half ester base is formed on at least one side of a polyester film using an aqueous melamine resin. A polyester film laminate provided with a single layer of crosslinked primer, and an aqueous polyester film having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half ester base on at least one side of the polyester film before crystal orientation is completed. This is achieved by a method for producing a polyester film laminate, which is characterized by applying an aqueous primer coating solution containing polyurethane and an aqueous melamine resin, followed by drying, stretching, and heat treatment to complete crystal orientation.

In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate,
Polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-
Examples include 2゜6-naphthalene dicarboxylate,
Copolymers of these or blends of these with small proportions of other resins are also included.

The polyester film of the present invention is obtained by melt-extruding such a linear saturated polyester resin, forming it into a film by a conventional method, and subjecting it to oriented crystallization and heat treatment crystallization. This polyester film is preferably crystal oriented to such an extent that the heat of crystal fusion measured by a scanning calorimeter in a nitrogen stream [at a heating rate of 10°C/min] is usually 4 cal/g or more. .

In the present invention, a polyester film before completion of crystal orientation refers to an unstretched film obtained by thermally melting the polymer and forming it into a film as it is; an unstretched film oriented in either the vertical direction or the horizontal direction. Uniaxially stretched film: Further, a film that has been stretched and oriented at a low magnification in both the vertical and horizontal directions (two-wheel stretched film before being finally re-stretched in the vertical or horizontal direction to complete oriented crystallization), etc. This includes:

The aqueous primer coating liquid used in the present invention contains an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base, and an aqueous melamine resin. This aqueous polyurethane has enhanced water compatibility with a carboxylic acid group, a sulfonic acid group, or a sulfuric acid half ester base, and such water affinity-imparting groups are usually introduced after the synthesis of the polyurethane. For example, a carboxylic acid group can be introduced by using a carboxylic acid group-containing polyhydroxy compound as one of the raw material polyhydroxy compounds during polyurethane synthesis, or by introducing a hydroxyl group-containing carboxylic acid or amine into the isocyanate group of a polyurethane having unreacted isocyanate groups. This can be carried out by reacting a group-containing carboxylic acid, then adding the reaction product to an aqueous alkali solution under high speed stirring, and neutralizing it. In addition, the introduction of a sulfonic acid group or a sulfuric acid half-ester base is usually carried out by forming a prepolymer from a polyhydroxy compound, a polyisocyanate, and a chain extender, and adding an amino group or a hydroxyl group that can react with the terminal isocyanate group and a sulfonic acid group or This can be carried out by adding and reacting a compound having a sulfuric acid half ester base in its molecule, and finally obtaining an aqueous polyurethane having a sulfonic acid group or a sulfuric acid half ester base in its molecule. In this case, it is preferable to carry out the formation reaction in an organic solvent, then add water and then remove the solvent. Another method is to synthesize a polyurethane having a sulfonic acid group using a compound having a sulfonic acid group as one of the raw materials, and then add the polyurethane to an alkaline aqueous solution under high speed stirring to neutralize it. , a method of adding the following sultone compound to the primary or tertiary amino group of the main chain or side chain of polyurethane in the presence of an alkali to introduce an alkali sulfonic acid salt (for example, -803Na, etc.). Sodium hydroxide is an alkaline aqueous solution.

It is preferable to use an aqueous solution of potassium hydroxide, ammonia, alkylamine, etc., but ammonia does not leave the alkali in the coating film (undercoat film).

Amines that volatilize under dryness conditions are particularly preferred. The amount of bases such as carboxylic acid bases, sulfonic acid bases, and sulfuric acid half-ester bases is preferably 5 to 15% by weight. If the proportion of the base is too small, the water affinity of the polyurethane will be insufficient, making it difficult to prepare a coating solution, and if it is too large, the inherent properties of the polyurethane will be impaired, which is not preferable. Such aqueous polyurethane forms a stable aqueous dispersion or aqueous solution using a dispersion aid if desired.

Examples of polyhydroxy compounds used in the synthesis of polyurethane include polyethylene glycol.

Polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1.5
-bentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate.

Polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate.

Trimethylolpropane, trimethylolethane.

Examples include pentaerythritol and glycerin. Examples of the polyisocyanate compound include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, an adduct of hexamethylene diisocyanate and trimethylolethane, and the like. Examples of carboxylic acid-containing polyols include dimethylolpropionic acid and dimethylolbutyric acid.

Examples include dimethylolvaleric acid and trimellitic acid his(ethylene glycol) ester. Examples of the amino group-containing carboxylic acid include β-aminopropionic acid, γ-aminobutyric acid, and P-aminobenzoic acid. As the hydroxyl group-containing carboxylic acid, for example, 3
-Hydroxypropionic acid, γ-hydroxybutyric acid, P
-(2-hydroxyethyl)benzoic acid, malic acid, etc. can be mentioned. Examples of compounds containing an amino group or a hydroxyl group and a sulfonic group include aminomethanesulfonic acid, 2-aminoethanesulfonic acid, and 2-amino-5-
Methylbenzene-1-sulfonic acid.

Examples include sodium β-human O-oxyethanesulfonate, propane sultone or butane sultone adducts of aliphatic di-primary amine compounds, and preferably aliphatic di-primary amine compounds.
Examples include butane sultone adducts of grade amine compounds.

Examples of compounds containing an amino group or a hydroxyl group and a sulfuric acid half-ester group include aminoethanol sulfuric acid, ethylenediamineethanol sulfuric acid, and aminobutanol sulfuric acid.

and droxyethanol sulfate, γ-hydroxypropanol sulfate, α-hydroxybutanol sulfate, etc.

Polyurethane can be synthesized using these compounds by conventionally well-known methods.

Water-based melamine resins that crosslink with water-based polyurethane are compounds containing two or more methylol groups and/or alkoxymethyl groups in the melamine molecule, and precondensates thereof, such as hexamethylol melamine resin and trimethoxymethyl melamine resin. , trimethyloltrimethoxymethylmelamine resin, etc. Here “aqueous”
means the property of being dissolved or dispersed in an aqueous medium. Such aqueous melamine resins tend to promote self-crosslinking on the acidic side and tend to cause changes in the aqueous liquid over time.

In this respect, since the aqueous polyurethane used in the present invention is neutral or alkaline, the primer coating liquid is advantageous in terms of quality control as it is a stable liquid that does not change over time. Furthermore, when using water-based polyurethane containing volatile amine salts or ammonia salts, ammonia and amines are volatilized by heating after application, and acid groups such as carboxylic acid groups and sulfonic acid groups are generated, which can cause melamine resin and It has the advantage of promoting crosslinking. Further, when using an aqueous polyurethane containing an alkali metal salt, it is preferable to add an acid catalyst (for example, an organic acid such as acetic acid or glycolic acid) to the primer coating solution immediately before coating.

The aqueous primer coating liquid used in the present invention may be an aqueous solution or an aqueous dispersion (but is not particularly limited. The ratio of aqueous polyurethane to aqueous melamine resin is 100 parts by weight of the former to 100 parts by weight of the latter It is preferably from 1 to 40 parts by weight, more preferably from 2 to 30 parts by weight.If the proportion of melamine resin is too large, the easy adhesion performance will be reduced, and if it is too small, the solvent resistance will be reduced, which is the purpose of the present invention. It becomes difficult to obtain a good coated surface when the product is applied, which is not preferable.

The aqueous primer coating solution is made by dissolving or dispersing the above two components in an aqueous medium, but it can also be used by adding a necessary amount of a surfactant such as an anionic surfactant or a nonionic surfactant. .

As such a surfactant, the surface tension of the aqueous coating solution is 40
dyne/tx or less and promotes wetting to polyester films, such as polyoxyethylene alkylphenyl ether.

Polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester.

Examples include fatty acid metal soaps, alkyl sulfates, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chlorides, and alkylamine hydrochlorides. Furthermore, within the scope of not detracting from the effects of the present invention,
For example, antistatic agents, ultraviolet absorbers, pigments, organic fillers, and inorganic fillers.

Other additives such as lubricants, anti-blocking agents, etc. can be mixed.

The aqueous primer coating solution may be applied to the polyester film in a normal coating process, that is, in a process in which it is applied to the two-wheel stretched and heat-set polyester film separately from the film manufacturing process.

However, this process tends to introduce dirt, dust, etc., and it is desirable to apply the coating in a clean atmosphere for advanced products such as magnetic tapes and floppy disks. From this point of view, coating during the polyester film manufacturing process is preferable. In particular, it is preferable to apply an aqueous primer coating liquid to one or both sides of the polyester film before the crystal orientation is completed during this step. In this case, the fixed valve concentration of the aqueous primer coating liquid is usually 30% by weight or less, more preferably 10% by weight or less. The coating amount is preferably 0.5 to 20 g, more preferably 1 to 10 g per TIL of the running film.

Any known coating method can be used as the coating method.

For example, a roll coating method, a gravure coating method, an O-le plush method, a spray coating, an air knife coating, an impregnation method, a curtain coating method, etc. may be applied alone or in combination.

The polyester film coated with the aqueous primer coating solution is dried and subjected to processes such as stretching and heat setting. For example, a longitudinally uniaxially stretched polyester film coated with an aqueous primer coating solution is guided into a stenter, where it is laterally stretched and heat-set. During this time, the coating solution dries and further undergoes a crosslinking reaction, forming a continuous film on the film. Heat for the crosslinking reaction is usually supplied by heat during stretching or heat setting. For example, 200°C for about 10 seconds and 150°C for about 1 minute.

Heating may be performed at 120° C. for about 15 minutes, 220° C. for about 8 seconds, etc., or heating may be performed under harsher or milder conditions. The coating solution is dried at 100℃ for approximately 5 minutes.
It may be heated at 110° C. for about 5 seconds and at 90° C. for about 20 seconds. It may also be air-dried.

Oriented crystallization conditions of polyester film, e.g. stretching,
Conditions such as heat fixation can be carried out under conditions conventionally accumulated in the art.

Effects of the invention The polyester film having the primer layer thus obtained can be used as an ink for cellophane.

magnetic paints, gelatin compositions, toner compositions for electrophotography,
Shows high adhesion to a wide range of paints such as chemical matte paints, and has excellent solvent resistance to organic solvents such as methyl ethyl ketone, toluene, ethyl acetate, butyl acetate, ethanol, dioxane, tetrahydrofuran, cyclohexanone, and cyclohexane. shows.

Example The present invention will be further explained below with reference to Examples.

Note that "parts" in the examples mean "parts by weight." Moreover, each characteristic of the film was measured by the following method.

1. Apply the evaluation paint to the adhesive primer-coated polyester film, dry it at 80℃ for 1 minute, and then dry it at 60℃ for 24 hours.
It is aged for a period of time and then roll coated so that the coating thickness is 2 μm on average. Load the resulting coated film onto the head of an RCA abrasion tester (RCA)! It wears out at 50g,
The adhesion is measured by the number of times it is worn until holes form on the coated surface.

[Adjustment of paint for evaluation] Nitrocellulose R81/2 as lacquer thinner for paint
[Freus containing 25% isopropanol; manufactured by Daicel] was dissolved to prepare a 40 wt% solution, and the solution was
3.9 parts, followed by polyester resin (Desmophen #
1700: manufactured by Bayer AG) 32.5 parts, chromium dioxide magnetic powder 2.60 parts 1 Soybean oil fatty acid (Legion P: manufactured by Riken Vitamin ■) as a dispersant/wetting agent, cationic activator (cation AB: manufactured by Nippon Oil & Fats ■) 1 part, 0.5 part, and 0.8 part of squalene (shark liver oil) were put into a ball mill. Methyl ethyl ketone (hereinafter abbreviated as MEK)/cyclohexanone/toluene-3/4/3
Further, 282 parts of the mixed solution consisting of (weight ratio) is further mixed and sufficiently pulverized to prepare a mother liquor paint (45 wt%). To 50 parts of this mother liquor, 48 parts of an addition reaction product of trimethylolpropane and tolulein diisocyanate (Coronate L Nippon Polyurethane Co., Ltd.) and 6.25 parts of butyl acetate were added to give a final solid content concentration of 42. 75
A magnetic paint for wt% evaluation was obtained.

2o Apply a drop of tetrahydrofuran (approximately 0.02 cc) to the surface of the polyester film coated with a solvent-resistant primer using a dropper.
Drop it, place gauze on top of it, place a weight of 100 g on it, and move the gauze at a speed of about 101,000 tons.

After drying at room temperature, interference micrographs of those not treated with tetrahydrofuran and those treated with tetrahydrofuran were compared at 400 times magnification, and the state of surface change of the primer was judged as follows.

Those with almost no primer: × Those with almost no change in primer: 0 Those with a slight change in surface morphology in the middle 20~Δ Those with a considerable change in surface morphology = ×~Δ Those with an intermediate change in surface morphology :Δ Example 1 Polyurethane aqueous dispersion having carboxylic acid amine base [
(manufactured by Toyo Polymer ■: trade name Merci-585] 880 parts as non-volatile components), polyoxyethylene nonylphenyl ether [manufactured by NOF ■: trade name NS-240]
10 parts of methylolated melamine (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumitex Resin M-3) were diluted with ion-exchanged water to prepare an aqueous primer coating solution with a solid content concentration of 3% by weight. The DH of this coating liquid was 1.3, and there was no change in the physical properties of the coating liquid even after long-term storage.

This coating liquid was applied to a two-wheel stretched polyethylene terephthalate film by the gravure foot method, and then heated to 140°C.
Heat treated for 45 seconds in a drying zone, with an average coating weight of 5.
A primer-coated polyester film laminate of 04-DrV/d was obtained.

The film had sufficient adhesion to the magnetic paint for evaluation, and it was possible to form a good painted surface without running streaks.

Example 2 Intrinsic viscosity measured in O-chlorophenol at 25°C 0
．． 65 polyethylene terephthalate (containing lubricant) 2
Melt extruded onto a rotating cold drum maintained at 0°C to a thickness of 9.
An unstretched film of 50 μm was obtained.

Next, this film was stretched 3.5 times in the machine axis direction, and then a coating solution identical to the coating solution prepared in Example 1 was applied to both sides of the uniaxially stretched film by a kiss coating method. The average coating amount at this time was 50 ay/rd in terms of solid content. Subsequently, the film was stretched 3.9 times in the transverse direction at 105°C and further heat treated at 210°C to obtain a 75 μm thick two-wheel polyester film laminate coated with primer on both sides.

Example 3 In place of the aqueous polyurethane solution of Example 2, an aliphatic polyester with a valence of 08 and 53 consisting of adipic acid, sebacic acid, 1,5-bentanediol and neopentyl glycol components, hexamethylene diisocyanate, aminoethanol sulfuric acid half ester, and water were used. A coating solution was prepared in the same manner as in Example 2, except that 80 parts of an aqueous polyurethane dispersion (as a non-volatile component) synthesized from potassium oxide and having 2.2 wt% (solid content) of 108O groups in the molecule was used. A polyester film laminate was obtained in exactly the same manner as in Example 2 except for using this coating solution.

Example 4 Example 1 Coating Solution A polyurethane dispersion containing a carboxylic acid amine salt manufactured by Coating Solution M [manufactured by Dainippon Ink Industries ■: trade name Hytran HW-1001] was carried out in the same manner as in Example 1, and the coating was carried out in the same manner as in Example 1. A polyester film laminate was obtained in exactly the same manner as in Example 2 except that a liquid was used.

Comparative Example 1 The two-wheel stretched polyethylene terephthalate film used in Example 1 was evaluated without being coated.

Comparative Example 2 In the coating liquid preparation method, melamine resin was not added, and 90 parts of aqueous polyurethane and 1 part of polyoxynonylphenyl ether were used.
A laminate was obtained by applying a solution prepared under the same conditions as in Example 1 to a polyester film in the same manner as in Example 1, except that 0 part was used.

Comparative Example 3 The coating liquid prepared in Comparative Example 2 was applied under the conditions of Example 2 to obtain a polyester laminate.

Comparative Example 4 In preparing the coating solution, the amount of polyurethane aqueous dispersion was 80%
part to 40 parts, and further increased the amount of melamine resin from 10 parts to 5 parts.
A polyester film laminate was obtained in exactly the same manner as in Example 2 except that the amount was changed to 0 parts.

Comparative Example 5 In Example 2, the polyurethane dispersion was replaced with a cationic polyurethane dispersion [manufactured by Kao Soap: trade name: Softex U]
Coating liquid (1) H: 4.6 using [E-296A]
) was prepared, and a polyester film laminate was obtained in exactly the same manner as in Example 2. On the other hand, when this coating liquid was stored at 30° C. for one month, the liquid became slightly cloudy.

The dry coating thickness of the above evaluation coating material was 1.5 μm on the polyester film laminates of Examples 1 to 4 and Comparative Examples 1 to 5.
The adhesiveness, coating properties, and stability of the primer coating solution were evaluated.

The results are shown in Table 1.

(Left below) From Table 1, it is clear that the primer of the present invention has good stability of the primer coating solution, does not cause streaks during paint application, enables uniform and stable coating, and has excellent adhesion. It is clearly a good primer.

Patent Applicant Teijin Co., Ltd. Representative Patent Attorney 1) Written amendment to the patent procedure dated Δ month θ, 1985

Claims (1)

[Claims] 1. A primer layer formed by crosslinking an aqueous polyurethane containing at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base with an aqueous melamine resin is provided on at least one side of the polyester film. polyester film laminate. 2. The laminate according to claim 1, wherein the base of the aqueous polyurethane is an amine base. 3. The laminate according to claim 2, wherein the amine base is a carboxylic acid amine base. 4. Applying an aqueous primer coating solution containing an aqueous polyurethane and an aqueous melamine resin having at least one of a carboxylic acid base, a sulfonic acid base, and a sulfuric acid half ester base to at least one side of the polyester film before crystal orientation is completed. A method for producing a polyester film laminate, which comprises drying, stretching, and heat treating to complete crystal orientation. 5. The manufacturing method according to claim 4, wherein the base of the aqueous polyurethane is an amine base. 6. The manufacturing method according to claim 5, wherein the amine base is a carboxylic acid amine base.