JPS5932486B2 - Hardener for epoxy resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel compounds suitable for use as curing agents for epoxy resins containing at least one 1,2-epoxy group.

With this new curing agent, epoxy resins can be cured at or below room temperature, for example at temperatures of about 5° C., without the need for any external heating.

The present invention also provides a novel coating composition prepared by mixing such a curing agent with an epoxy resin coating, and a method of forming a protective film on a substrate using the coating composition. , the coating is a cured epoxy resin that protects the substrate from the harmful effects of various substances applied onto it, such as sprayed fuel, kerosene, heated oils, and solvents. sell.

The novel coating compositions and methods of applying the same disclosed herein are free of volatile solvents and therefore are suitable for containing atomized fuel tanks, heated oil tanks, and highly flammable liquids. It can be suitably used to provide a protective coating on other containers.

Novel compounds according to the invention useful for curing epoxy resins having at least one 1,2-epoxy group are of the formula:

where (n) has a numerical value of at least 2.

The value of (n) can range from 2 to 5, but generally best results can be obtained when it is 2.
The novel compounds of the present invention, represented by the above formula, are advantageously used for curing epoxy resins or polyepoxides consisting of organic materials having at least one vicinal epoxy group, viz.

Said organic substance may be a saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic compound;
It may have a substituent such as a halogen atom, a hydroxyl group, or an ether radical.

Furthermore, these compounds may be either monomers or polymers. Generally, such epoxy resins consist of polyether derivatives of polyhydric organic compounds, said derivatives having 1,2-epoxy groups, said polyhydric organic compounds containing polyhydric alcohols or at least two It consists of polyhydric phenols containing phenolic hydroxyl groups.

Polyhydric phenols that can be used in preparing such glycidyl polyethers include monocyclic phenols such as resorcinol, catechol, hydroquinone, and
bis(4-hydroxyphenyl)-2,2-propane,
4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxyphenyl)-2 , 2-butane, bis(4-hydroxy-2-methylphenyl)-2,2-propane, bis(4-hydroxy-2-tert-butylphenyl)-2
,2-propane, bis(4-hydroxy-2,5-dichlorophenyl)-2,2-propane, 4,4'-dihydroxybisphenyl4,4'-dihydroxypentachlorobisphenyl, bis(2 -Polycyclic phenols such as hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, phloroglucinol, 1,4-dihydroxynaphthalene, and 1,4-bis(4-hydroxyphenyl)cyclohexane, and the presence of an acidic condensation catalyst There are many polyvalent phenol complexes, such as novolac resins, pyrogallol and phloroglucinol, which are synthesized by condensing phenols and aldehydes.

Regarding the properties and production of the above-mentioned novolac resin, see 1.
Published in 947, T.I., S., Carswell (
T. S. Phenylplast (
Phenylplast), page 29.

Further, the polyether derivative of the polyvalent organic compound for making the epoxy resin may be an ether having a 1,2-epoxy group such as polyglycidyl ether of an aliphatic polyhydric alcohol, such as ethylene glycol, propylene glycol, trimethylene glycol, etc. , butylene glycol, diethylene glycol, 4,4'-dihydroxydicyclohexyltriethylene glycol, glycerol,
It may consist of diglycidyl ethers such as dipropylene glycol, as well as ethers containing two or more glycidyl creeps such as glycidyl polyethers, glycerol, mannitol, sorbitol, polyalkylalkolyl, polyvinyl alcohol, etc.

These epoxy resins, in other words glycidyl polyethers, can be prepared by reacting predetermined amounts of at least one polyhydric compound with epihalohydrin in an alkaline solvent.

Although it is preferred to use epichlorohydrin as the epihalohydrin in the preparation of the epoxide starting material, other epihalohydrins, such as epibromohydrin, can also be used effectively.

When producing an epoxy resin, an aqueous alkaline solution is used to bond with the halogen of epihalohydrin.

The amount of alkali used may be substantially equal to the amount of halogen present, but it is preferable to use a somewhat excessive amount. For the above purpose, it is also possible to use a mixed aqueous solution of alkali metal hydroxide, for example, mixed with potassium hydroxide, but economically it is preferable to use an aqueous sodium hydroxide solution. That is clear.

The product of the above reaction is not a single simple compound, but its main product consists of a complex mixture of glycidyl polyethers, as shown by the following formula:

In the formula, (n) is an integer of 0, 1, 2, 3..., preferably the maximum value is 10, and (B) is
It represents a divalent hydrocarbon radical group of a polyvalent compound, but 2
Preferably, it is a phenol of a valent value.

If the product compound consists of a single molecule, (n) can be an integer, but since the polyether actually obtained is a mixture, the value of (n) determined, for example, by molecular weight measurement. is an average value and is not necessarily an integer.

Polyethers suitable for use with the curing agents of the present invention are made from bis(4-hydroxyphenyl)-2,2-propane, in which glyceryl and 2,2-bis(phenylene)propane radical groups are 1 to 2 chains having alternating bonds with etheric oxygen atoms interposed between them
and has a 1,2-epoxy value of about 170 to 25
It has an epoxide equivalent weight of 0.

Polyethers suitable for use such as about 175 to 20
an epoxide equivalent weight of 0 and a 1 of about 1.8 to 1.95;
It is a glycidyl polyether of bisphenol A, which has a 2-epoxy value and is normally liquid.

Here, the term "epoxy value" means the number of epoxy groups contained in an average molecule of the material used.

The "epoxy value" is obtained by dividing the average molecular weight of the epoxy resin by the so-called "epoxide equivalent weight.""Epoxideequivalent" is calculated by heating 1 gram of polyepoxide sample with an excess amount of pyridinium chloride dissolved in pyridine at the boiling point for about 20 minutes, and removing the excess pyridinium chloride with phenolpthalene using 0.1N sodium hydroxide. It can be determined by back titrating until the end point is reached.

This measurement can be performed by calculating by considering 1 equivalent of hydrochloric acid as 1 equivalent of epoxide. Such methods can be used to obtain all epoxide equivalents described herein.
When the novel compounds of this invention are used as curing agents for epoxy resins, they are preferably used in an amount sufficient to cure the epoxy resin to an insoluble and infusible polymer.

Generally, the amount of curing agent used should be in at least 5% stoichiometric excess, where the term "stoichiometric amount" used refers to the amount of each to be reacted. To supply one amino hydrogen to an epoxy group,
Indicate the amount needed.

In particular, excellent results are obtained when the curing agent is used in an excess of 5% to 50% of the stoichiometric amount. A preferred curing agent of the above formula in which the value of (n) is 2 comprises about 6 moles of phenol, 3 moles of formaldehyde (in the form of a 36% formalin solution) and 0.2 weight percent triethylamine. Stir for 2 hours,
The solution can then be prepared by adding 9 moles of 3,5,5-trimethyl-3-aminomethylcyclohexylamine into the solution and heating the solution at 100<0>C for about 1 hour.

Water produced during the reaction is removed by distillation. The curing agent thus produced is pale yellow in color and highly reactive towards epoxy resins.

Therefore, the novel curing agent according to the invention does not require any addition of commonly used curing accelerators in its use. The coating composition prepared by mixing the novel curing agent according to the invention has a fluid density, exhibits good mechanical and chemical resistance in use, is smooth, sticky, and has strong curing protection. A membrane may be provided on the application substrate.

Such novel coating compositions may consist of the following components.

A liquid epoxy resin having a finite number of epoxy groups, an epoxy equivalent weight of about 185 to 210, and a viscosity of about 900 cps or less at 25°C.

(B) A filler in an amount of about 20 to 50 percent by weight of the epoxy resin. (O suitable amount of dispersant for the above filler.

(to) (n) in the above formula is at least 2, preferably 2
Novel curing agents according to the invention, which are from 1 to 5.

The above-mentioned method for providing a protective film made of a coating composition on a substrate involves applying the same coating composition onto the surface of the substrate and curing the coating composition without heating it at all. It can be achieved. In the experimental examples related to the present invention, the liquid epoxy resins actually used were epichlorohydrin and diphthalamic acid.
It is a reaction product with enylolpropane and has the following formula:

Such resins have a viscosity at 250°C of less than about 900 cps, preferably about 700 to 800 cps.

In the above structural formula, (n is preferably about 0.2; at that value, the resin will have a molecular weight of about 380.

However, this (n) can be in the range of 0 to 10. The epoxy resin produced when the above epoxy resin is synthesized is a mixture of one or more types of compounds,
Therefore, (the average value of n, not necessarily O or 1
not an integer like . Particularly preferred resins exhibiting the above properties are manufactured by Sh.
It is manufactured by Mica IC Company and is commercially available under the product name 828.

Commercially available liquid epoxy resins suitable for use in connection with the present invention include DOwCOrning COr.
pOratiOn)'s "Day●Iichi●R331(D
ER-331) and CibaL
td. )'s "Ciba Resin 50"
2] The term "epoxy equivalent" refers to the average molecular weight of an epoxy resin divided by the number of epoxy radical groups per molecule thereof, or corresponds to one epoxy group or one gram equivalent of epioxide. means epoxy resin.

In the practice of this invention, the effective and novel amount of curing agent is
The amount is sufficient to cure the epoxy resin.

Generally, the amount used should be about 35 to 40%, preferably 35%, of the total amount of liquid epoxy resin.

It is usually desirable to add an epoxy resin to the novel curing agent of the present invention immediately prior to its use on a substrate for the purpose of forming a protective film.

This is because the resin coating composition to which the novel curing agent is added can be rapidly and easily cured not only at low temperatures but also at or near normal room temperature.

The novel coating compositions provided by the present invention contain about 20 to 50%, preferably 33%, of the desired epoxy resin, and are inert to other components in the composition and about 50% of the desired epoxy resin.
consisting of a large number of particles with maximum dimensions of microns,
Contains at least one filler.

Generally the particle size of such fillers is about 25 to 50
It can be microns. Examples of suitable inert fillers include: i.e. sand, crushed shells,
Rock, aluminum powder, copper powder, quartz powder, titanium dioxide, asbestos, silica, calcium carbonate, graphite, triiron tetroxide, silicon dioxide, cane earth, aluminosilicate, silicon carbide, boron carbide, birchstone, talc, mica etc.

In terms of corrosion protection, stainless steel flakes, steel powder, titanium magnetite oxide or mixtures thereof can be suitably used.

The novel coating composition preferably further contains a dispersant component to promote proper and uniform dispersion of the filler particles in the resin.

Best results are obtained using an effective amount of fumed silica as the dispersant. Generally, this fumigated silica should be used in an amount of 5 to 20%, preferably 10%, by weight of the epoxy resin, and it not only prevents settling of the filler in the coating composition, but also helps the coating composition. This can have the effect of increasing the overall corrosion resistance of the composition.

Additionally, it is desirable to add silicic acid as another component of the new coating composition, in an amount of about 1 to 7 percent, preferably 3 percent, by weight of the epoxy resin.

Silicic acid can have the effect of promoting adhesion of the coating composition to wet or greasy substrate surfaces. Furthermore, it is preferable to use silicone oil as another component, and the amount used is approximately 5.4% of the total base component.
Approximately 1 ounce to 2 ounces per 120 pounds is preferred.

Silicone oil facilitates the dispersion of pigments when they are used in combination with paint compositions.

Furthermore, silicone oil can also have the effect of lowering the surface tension of the coating composition and promoting the dispersion of the coating composition on the substrate. Furthermore, it is also preferred that the novel coating compositions provided by the present invention contain a sufficient amount of aluminum hydroxide as a fire retardant in the coating composition.

Although aluminum hydroxide may be the most preferred fire suppressant, other similar materials may be used as substitutes.

Generally, such aluminum hydroxide should be used in amounts up to 5% by weight of the coating composition. The novel coating composition described above can generally be prepared by mixing its various components one by one in an appropriate order, but if desired two or more components can be mixed together. A mixture may be prepared in advance and the remaining ingredients may be mixed therewith.

However, it should be noted here that the novel curing agent according to the invention should be added immediately before use of the coating composition.

This is because this curing agent can easily cure the resin coating at or near room temperature, even without any heating for curing. When the coating composition described above is applied to a given substrate, the resultant film formed on the same substrate has a highly satisfactory chemical resistance to atomized fuels, gasoline, heated oils, solvents, etc. It has been found that they can exhibit high compressive strength, low shrinkage rate, good thermal resistance, coefficient of thermal expansion and adhesive properties as well.

The novel coating composition provided by the present invention can be applied to the surface coating and/or repair of any substrate such as wood, cement, metal, glass, etc.

In particular, it is preferably used for treating the surfaces of metal materials such as copper, aluminum, brass, steel and iron.

Thus, for example, pipes, piles, reaction vessels, oil well drilling platforms, containers for injection fuel, heated oil and solvents,
It can be suitably used for well jackets, heat exchange pipes, molds, etc. When the novel coating composition according to the present invention is used on a particular substrate, an amount sufficient to impart the desired chemical resistance to the surface of the substrate is used, and at least 0.3 mm.
Preferably, a sufficient amount is used to provide a coating thickness of .

Application of such coating compositions to substrates can be carried out by techniques well known in the art, such as painting, spraying or dipping.

The novel coating composition according to the invention applied to a substrate by these methods cures easily at or near room temperature, resulting in a beautiful appearance and high chemical resistance on the same substrate. It can form a strong, long-lasting protective coating that is resistant to damage.

Claims (1)

[Scope of Claims] 1. Suitable for use in curing epoxy resins, consisting of a novel compound represented by the following formula, ▲which includes mathematical formulas, chemical formulas, tables, etc.▼In the formula, (n) is at least 2. 2. The curing agent for epoxy resin according to claim 1, wherein (n) is 2 to 5. 3. The curing agent for epoxy resin according to claim 1, wherein (n) is 2.