JPS61133228A - Epoxy resin curing - Google Patents

Abstract

PURPOSE:A guanidine with a specific structure is used as a curing catalyst to cure an epoxy resin using a mercaptan as a curing agent whereby the title resin which is used as an adhesive is cured rapidly even at a relatively lower temperature. CONSTITUTION:(A) 0.01-20pts.wt., per 100pts.wt. of component A, of a guanidine of the formula (R1-R4 are H, 1-8C alkyl) is used as a curing catalyst to cure (B) an epoxy resin with (C) a mercaptan curing agent. The component A is preferably tetramethylguanidine and/or tetraethylguanidine in an amount 0.001-10pts.wt. per 100pts.wt. of component B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for curing epoxy resins, and in particular to a method for curing epoxy resins, which can be extremely rapidly hardened at relatively low temperatures, such as room temperature or lower.

(Prior Art) Conventionally, in order to cure polyepoxy compounds at low temperatures such as room temperature, polyamines or polyamides are used alone as a curing agent, or phenols or alcohols are used as a curing accelerator in addition to these.

Although acidic substances such as aromatic carboxylic acids were used in combination, a sufficiently satisfactory curing speed could not be achieved.

In addition, if polymercaptans are used as a curing agent,
Although polyepoxy compounds can be cured even at low temperatures, such as room temperature, the curing speed in this case is also slow. Practically, polymercaptans include polyethylene polyamine (Japanese Patent Publication No. 48-17880), polyamide (the same publication), and 2.4.6-tri(dimethylamine)phenol (Japanese Patent Application Laid-open No. 17299-1982). In the past, it has been possible to improve the curing speed by using a variety of amines such as triethylenediamine (the same publication) or basic substances such as amides.

(Problems to be Solved by the Invention) However, even in this case, there were drawbacks such as a sufficient curing speed could not be obtained and a cured product with a strong amine odor and one color was produced.

For example, when polyethylene polyamines are used in combination with polymercaptan, the curing speed is insufficient and there is a drawback that an amine odor is produced. Also.

2,46-tri(dimethylamine) in polymercaptan
When phenol is used in combination, the curing speed is relatively fast, but t is not sufficient, and there is a drawback that the cured product is colored. When triethylenediamine is used in combination with polymercaptan, the curing speed is relatively fast, but it is not sufficient, and since triethylenediamine is a solid, it is necessary to use it dissolved in polymercaptan. had the disadvantage that workability was reduced due to extremely high viscosity.

Even when polyamides are used in combination with polymercaptan, there are disadvantages in that the curing speed is not sufficient and the cured product is colored.

Accordingly, one object of the present invention is to develop a method for curing epoxy resins that can be cured rapidly at low temperatures and that can produce cured products that do not produce amine odor or coloration.

(Means and effects for solving the problems) The present invention solves the above problems by using tetramethylguanidine as a curing catalyst.

That is, 9 the present invention provides that when a polyepoxy compound is cured with a mercaptan curing agent, the general formula H (wherein + & + Rz + Rs and R4 represent hydrogen or an alkyl group having 1 to 8 carbon atoms; The present invention relates to a method for curing an epoxy resin, which is characterized by using a guanidine compound represented by the formula (which may be the same or different) as a curing catalyst.

As the epoxy resin of the present invention, mainly compounds having two or more epoxy groups in the molecule can be used.

Typical epoxy resins that can be used in the present invention include the following.

+a) Poly(i[[iPolyglycidyl ether of phenol.

For example, 2.2-bis(4-hydroxyphenyl)propane, 1.1-bis(4-hydroxyphenyl)ethane, baboon(4-hydroxyphenyl)methane, etc. tD Diglycidyl ether of diphenylolalkane, etc.: 4.
4'-dihydroxydiphenyl sulfone.

Diglycidyl ethers such as hydroquinone, resorcinol, dihydroxyphenyl or dihydroxynaphthalene:
Polyepoxy compounds derived from polyhydric phenols such as polyglycidyl ethers of phenols or novolaks or resols, which are condensates of phenols and formaldehyde.

(b) Polyglycidyl, II/Neil, 9+j L of aliphatic polyhydroxy compounds (d ethylene glycol, glycerol, trimethylolpropane,
Polyglycidyl ethers such as pentaerythritol and neopentyl glycol.

(C) Polyglycidyl ester of polycarboxylic acid.

For example, diglycidyl esters of phthalic acid, terephthalic acid, adipic acid, tetrahydroheptalic acid, hexahydrophthalic acid and the like.

(d) Polyglycidyl esters of polymers of unsaturated fatty acids, such as the dimeric diglycidyl esters of lylunic acid.

(Epoxidized esters of 61 unsaturated acids, such as epoxidized linseed oil or soybean oil.

(f) Epoxidized dienes, such as jepoxybutane.

fg) Others include epoxidized vinylcyclohexane, polyglycidyl isocyanurate, diglycidylaniline, λ2-bis-(4-hydroxyphenyl)propane, water f-added diglycidyl ether of hydrogenated bisphenol A, etc.

The above polyepoxy compounds can be used alone or in combination depending on the purpose.

These polyepoxy compounds contain butyl glycidyl ether to reduce viscosity. Monoepoxy compounds such as glycidyl ether, alkyl glycidyl ether, and 2-ethylhexyl glycidyl ether of synthetic fatty acids may be blended and used. The monoepoxy compound can be used in an amount of 0 to 200% by weight based on the polyepoxy compound, and is preferably 100% by weight or less in terms of hardness of the cured product.

The mercaptan curing agent used in the method of the present invention is a polymer having two or more 18H groups in one molecule obtained by reacting the following components (a) and (b) or (c). It is an alkyl carboxylic acid ester. In some cases, a compound having one 8H group in the molecule may be used in combination.

(a) Mercaptoalkylcarboxylic acid having a 18H group directly bonded to an aliphatic hydrocarbon and a carboxyl group (-COOH).

(b) Polyhydric alcohol.

(c) Mono- or polyepoxy compound.

As the mercaptoalkyl carboxycarbohydrate of component (a) above, when a flexible cured product is intended, an aliphatic hydrocarbon with a large number of carbon atoms to which -3H and -COOH groups are directly connected is used. If hard or cured products are intended, those with a small number of carbon atoms are used as appropriate. Mercaptoalkylcarboxylic acids in which the aliphatic hydrocarbons mentioned above have 1 to 18 carbon atoms are preferred, and examples of such compounds include mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, mercaptohexonic acid, mercaptooctanoic acid, and mercaptostearin. Examples include acids.

In addition, the polyhydric alcohol of component (b) is diethylene glycol and triethylene glycol.

1,4-butanediol, 1,6-hexanediol.

Neopentyl glycol, trimethylolethane.

Trimethylolpropane, glycerin, Tris(2-?
, c++diethyl)in cyanurate, pentaerythritol, ditrimethylolpropane.

Dipentaerythritol, mannitol, diruvite and their alkylene oxides (sometimes ethylene oxide,
With propylene oxide, butylene oxide, etc.
polyethylene glycol with an average molecular weight of 1500 or less,
Examples include polypropylene glycol.

Furthermore, as the monoepoxy compound of component (c).

Cyclohexene oxide, styrene oxide, 1゜2-
Epoxydecane, butyl glycidyl ether.

Examples of polyepoxy compounds include phenyl glycidyl ether, lauryl glycidyl ether, butylphenol glycidyl ether, and the like.

The above-mentioned Bo+7 epoxy compound is mentioned.

To obtain a polymercaptoalkyl carboxylic acid ester, (2) per equivalent of the hydroxy group of the polyhydric alcohol of component (2) or the epoxy group of the epoxy compound of component (3),
b) Ingredient mercaptoalkyl carboxylic acid is 0.5 to 5
equivalent, preferably 1-2. ．． Mix at a ratio such that 5 equivalents are obtained and perform 9 reactions. The reaction conditions were heating at 120°C for about 1 hour, then gradually raising the temperature to 140°C, and heating at the same temperature for about 1 hour.
The reaction is preferably carried out by heating at 160° C. for about 3 hours. When a polyhydric alcohol is used, water is produced as a by-product, so a solvent that is azeotropic with water, such as toluene or xylene, is added to the mixture, and the esterification reaction is carried out while azeotropically separating water.

Examples of the mercaptan curing agent thus obtained include the following compounds.

Triethylene glycol bis(mercaptoacetate)
, triethylene glycol bis(merrbutopropionate), triethylene glycol bis(mercaptobutyrate), 1,4-butanediol bis(mercaptoacetate), 1,4-butanediol bis(mercaptoacetate).

Neopentyl glycol bis(mercaptoacetate)
, Neopentyl Glycol Bis(Mercaptooctanate), Glycerin Tris (Mercaptoacetate), Glycerin Tris (Mercaptopropionate), Glycerin Tris (Mercaptopentanate), Trimethylolpropane Tris (Mercaptoacetate), Trimethylolpropane Tris (mercaptopropionate),
Trimethylolpropane tris (mercaptobutyrate). trimethylolpropane tris (merca 7') pekin tris), pentaerythritol tetrakis (mercaptoacetate), pentaerythritol tetrakis (mercaptopropionate).

Pentaerythritite Tetrakis (Mercaptobutyrate), Pentaerythritite Tetrakis (Mercaptopentanate), Pentaerythritite Tetrakis (Mercaptohexonate), Pentaerythritite Tetrakis (Mercaptooctanate).

Bismercaptoacetate, a glycol ether obtained by adding 3 moles of ethylene oxide to bisphenol A, bismercaptocrobionate, a glycol ether obtained by adding 3 moles of propylene oxide to bisphenol F, and an epoxy resin with an epoxy equivalent of 190 (Evomix). Bismercaptoacetate obtained by reacting R-140゜Mitsui Petrochemical Epoxy (trade name) with mercaptoacetic acid, Tetrakis mercaptopropionate obtained by reacting Evomisoku R-140 with mercaptopropionic acid, Phenylglycidyl Examples include bismercaptopropionate obtained by reacting an ether with mercaptopropionic acid, and tetrakismercaptobutyrate obtained by reacting neopentyl glycol diglycidyl ether with mercaptobutyric acid.

Examples of mercaptans having one 8H group in one molecule include dodecylmercaptan, thiophenol, and dodecylbenzylnorkabutane. Octadecylthioglycolate. Examples include dodecyl thioglycolate and dodecyl-5-mercaptopropionate. These should be from 0 to 10% by weight in the mercaptan curing agent;
If there are too many of these, the curability will be poor.

The amount of the mercaptan curing agent used in the present invention varies depending on the type of polyepoxy compound and the type of mercaptan, and although it cannot be generally specified, it is usually 10 to 10 parts by weight per 100 parts by weight of the epoxy resin. It is preferably selected from within the range of 150 parts by weight. The equivalent ratio is preferably 0.5 to 1.5 equivalents of 18H group in the mercaptan curing agent to 1 equivalent of epoxy group in the epoxy resin. If the amount of mercaptan curing agent is too small, curing tends to be insufficient and there will be too much unreacted curing agent.

Examples of guanidine compounds include guanidine, tetramethylguanidine, and tetraethylguanidine.

Examples include tetrapropylguanidine, and among these, tetramethylguanidine, tetraethylguanidine, etc. are preferred because they are liquid substances with low viscosity at room temperature and can be quickly and uniformly mixed with the epoxy resin and/or mercaptan curing agent.

The amount of the guanidine compound used is 0.00% relative to the epoxy resin.
01 to 20 parts by weight is preferred, particularly 0.5 to 16 parts by weight. If the amount of the guanidine compound is too small, the curing reaction will be delayed, and if it is too large, the effect of improving the curing speed will be saturated.

Alternatively, (A) and (B) may be mixed together in advance, and (C) is added thereto.
C) may be mixed in advance, and (Bl may be added thereto), or (B) and (C) may be mixed in advance, and this and CAl may be further mixed and cured.These curing reactions Before or at that time, in the above (A), (B) and/or (C1,
Solvents, diluents.

Fillers, pigments, stabilizers 1 coal tar, other bituminous materials,
Pine oil, plasticizers, various resins, rubber, various fiber substances, etc. can be mixed as appropriate.

Incidentally, after the above-mentioned compounds (B) and (C) are mixed, the curing reaction proceeds, so it is preferable to use the mixture immediately.

The curing method of the present invention can be applied to household and industrial adhesives, concrete or asphalt road lanes, etc.
Stop lines, crosswalks, other road marking lines (demarcation lines) for warnings and instructions, adhesion of inorganic particles of anti-slip agents on roads, adhesion of gold layers to metals, insulating coatings on metals, inorganic fillers ( For example, asbestos 9 powder, 9 clay, marble, dust.

It can be widely used in various fields such as sealants and sealants in combination with glass fibers, etc.).

(Examples) Next, the present invention will be described in detail based on Examples and Comparative Examples, but these Examples are merely illustrative.

This is not intended to limit the invention. Note that "parts" described in one example mean "parts by weight" unless otherwise specified.

Example 1 Ingredients! (a) Epoxy resin io
.

(Glycidyl ether of 2,2-bis(4-hydroxyphenyl)propane manufactured by Nimitsui Petrochemical Epoxy, epoxy equivalent 185-195) (b) Pentaerythritol tetrakis (3-60 mercaptoglopionate) (C) Tetramethylguanidine 0.5~
16 The above (al and (bl) were mixed in a beaker and stirred for 1 minute, then (C) was added and stirred for 1 to 2 seconds. After this.

The time until hardening was measured. The results are shown in Table 1 below. Note that (a), (b), and (C) above are in advance.

Those that had been left for 1 hour in thermostatic chambers at 20°C and 0°C were used, and the curing temperatures were set at 20°C and 0°C, respectively. The curing end point was defined as the point at which the contents did not flow at all even if the beaker was tilted at an angle of 45 degrees or more.

Table 1 with blank spaces below Curing time In this case, none of the obtained cured products was colored at all.

Comparative Example 1 In place of tetramethylguanidine in Example 1,
Triethylenediamine was heated and dissolved in pentaerythritoltetrakis (3-mercaptocropionate) using triethylenediamine, and then mixed with an epoxy resin and stirred. After this.

The time until hardening was measured. The results are shown in the second section below.
Shown in the table.

Table 2 Curing time In this case, the obtained cured product was colored yellow.

(Effect of the invention)

Claims (1)

[Claims] 1. When curing an epoxy resin with a mercaptan curing agent, there are general formulas ▲ mathematical formulas, chemical formulas, tables, etc. A method for curing an epoxy resin, the method comprising using a guanidine compound represented by 8 alkyl groups (which may be the same or different) as a curing catalyst. 2. The method for curing an epoxy resin according to claim 1, wherein the guanidine compound represented by the general formula is tetramethylguanidine and/or tetraethylguanidine. 3. The method for curing an epoxy resin according to claim 1 or 2, wherein the guanidine compound is used in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the polyepoxy compound.