JPS6210528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified epoxy resin composition that imparts mechanical properties, particularly flexibility, without impairing the physical properties of the epoxy resin. .

Epoxy resins are widely used in fields such as paints, electrical insulation materials, civil engineering and construction materials, and adhesives due to their excellent properties such as mechanical strength, adhesiveness, heat resistance, and chemical resistance.

On the other hand, cured epoxy resins have brittle properties;
As a method of improving this and imparting elasticity and toughness, a method of adding polysulfide, polychloroprene, polybutadiene, dimer acid, polyester ether, polyamide, etc. is generally known.

However, these methods have problems, such as deterioration of mechanical strength, electrical properties, heat resistance, or solvent resistance.

Furthermore, it is necessary to select an appropriate modification method depending on the field of use.

For example, epoxy resin is used as a raw material for cathode electrodeposition paint resin for automobile bodies, whose use has expanded in recent years, and various methods have been proposed to improve the performance of the paint film, such as chipping and corrosion resistance. ing. Among these, one effective method is to apply liquid polybutadiene, which has been widely used in conventional anodic electrodeposition coating resins, as a flexibility imparting agent.

In this case, due to the structure of the liquid polybutadiene, its compatibility with the epoxy resin is insufficient, and even if it is chemically bonded to the epoxy resin using an appropriate reactive group, it cannot be expected to obtain a clear homogeneous coating film.

Therefore, efforts have been made to improve their compatibility. For example, in JP-A-54-97632, a butadiene-acrylonitrile copolymer containing carboxyl groups at both terminals is reacted with an epoxy resin to form the base of a cationic electrodeposition paint resin.
In this case, the acrylonitrile part, which is a copolymerized component, is made to have compatibility with the epoxy resin, and although this has been considerably improved, it cannot be said to be completely sufficient in terms of homogeneous clearness of the coating film, and it is not flexible. In terms of addition, the microstructure of the butadiene moiety is limited to a narrow range, and the existing oligomers are functional polymers with relatively high molecular weights, so it is necessary to achieve homogeneity as an electrodepositing resin. The usage conditions are limited in terms of the blending ratio with the epoxy resin or the concentration of cationic groups to impart electrophoretic properties. In addition, in practical terms, price is also a factor that cannot be ignored.

On the other hand, JP-A No. 55-5933 is an example in which liquid polybutadiene is also used. This uses a reaction product obtained by reacting a conjugated diene polymer having a carboxyl group at the end of the molecule and/or in the middle of the molecule with an epoxy resin as the base of the cationic electrodeposition paint resin.

The liquid polybutadiene used here is essentially a high-vinyl type liquid polybutadiene containing carboxyl groups at both terminals, and is thought to be aimed at improving coating surface smoothness and coating film curability.

However, as mentioned above, although there are some differences in the microstructure of the polybutadiene component, its compatibility with the epoxy resin is insufficient.

There are many demands for imparting flexibility to epoxy resins, not only in the field of cationic electrodeposition paints, but also in other fields such as coatings and various molded products.

The present inventors have arrived at the present invention as a result of intensive studies on modification methods that can meet these diverse needs and physical properties and have wide applicability.

That is, the present invention has a number average molecular weight of 300 to
20,000, preferably 500 to 5,000, or an adduct [A] of a copolymer of a conjugated diene and a vinyl monomer and an α/β-unsaturated dicarboxylic acid or its anhydride, represented by the general formula [] (Here, R ₁ and R ₂ are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom, and a methoxy group, and R ₃ is an alkyl group having 1 to 5 carbon atoms, a phenyl group, and a benzyl group, and n = an integer of 0 to 3) is reacted with an epoxy resin and/or mixed with an adduct-modified product [C] obtained by reacting the compound [B]. The present invention relates to a method for producing a modified epoxy resin composition with improved performance.

The feature of the present invention is that the microstructure or molecular weight of the conjugated diene polymer or copolymer is
This means that it can be freely selected according to the purpose or required performance. For example, an adduct-modified product based on a liquid polybutadiene rich in high cis 1,4 bonds can effectively impart flexibility to an epoxy resin with a relatively small amount.

In addition, high 1/2 vinyl type products can lead to particularly hard compositions. The amount of α/β unsaturated dicarboxylic acid or its anhydride (hereinafter represented by maleic anhydride) to be introduced into liquid polybutadiene, and the modification conditions of the adduct can be adjusted in equimolar amounts to the epoxy resin (as a monomer). Another feature of the present invention is that it can be reacted with liquid polybutadiene molecules in an amount close to that amount.

The conjugated diene polymer used in the present invention is a conjugated diene polymer having a number average molecular weight of 300 to 20,000, preferably 500 to 5,000.

Conjugated diene polymers include conjugated diene homopolymers and conjugated diene copolymers. The microstructure of the double bond is not a problem, but the type 1/4 bond,
1.2 type bonds or 3.4 type bonds may also be included in any proportion.

Examples of the conjugated diene monomer include butadiene, isoprene, chloroprene, and 1.3-pentadiene, and examples of other copolymerizable monomers include acrylic esters, methacrylic esters, acrylonitrile, styrene, ethylene, and propylene.

These copolymerizable monomers may be one or two types.
It is also possible to copolymerize by mixing more than one species.
In addition, as the conjugated diene monomer in the copolymer,
They are butadiene and isoprene, and the copolymerization ratio is preferably 50 mol% or more.

These conjugated diene polymers and copolymers of conjugated dienes and the above monomers also include those having free carboxyl groups at their terminals.

Examples of the α/β-unsaturated dicarboxylic acid or its anhydride include maleic anhydride, maleic acid, fumaric acid, itaconic acid, and citraconic acid. Among these, maleic anhydride is preferred. The compound [B] to be reacted with the acid anhydride group of the conjugated diene polymer to which maleic anhydride has been added, that is, the adduct [A], should be used to impart compatibility with the epoxy resin and to give a good final cured product. Appropriate compounds or combinations of appropriate compounds are carefully selected in consideration of aspects such as imparting performance or adjusting the number of functional groups of carboxyl groups, which are reactive groups with epoxy resins, and the use of modified epoxy resins. . It is represented by the general formula [].

Examples of compounds [B] having a primary amino group or a secondary amino group in the molecule include N-methylaniline, N-ethylaniline, N-methyltoluidine, diphenylamine, dibenzylamine, and N-benzylaniline. etc. Also,
General formula [] for compound [B] (Here, R ₄ is a saturated or unsaturated aliphatic alcohol residue having 1 to 18 carbon atoms, a fatty acid residue, an alkylphenoxy residue, and a di-(alkyl having 1 to 18 carbon atoms)-amino group. , R ₅ is a hydrogen atom or a methyl group, and m is an integer of 1 to 5.) Compounds having a hydroxyl group in the molecule, such as ethylene oxide adducts and propylene oxide adducts of saturated or unsaturated fatty acids. ethylene oxide adduct and propylene oxide adduct of aliphatic alcohol derived from the fatty acid, 2
An alkylene oxide adduct of a grade amine, diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, etc. may be used in combination.

The amount of these compounds [B] to be used is 0.3 to 1.2 equivalents, preferably 0.5 to 1.0 equivalents, per equivalent of the bound acid anhydride group of the adduct [A]. Preferably 0.5-1.0
It is equivalent. In addition, when the alcohol of the said general formula [] is used together with compound [B], the total amount of these is 0.3-1.2 equivalent, Preferably 0.5-1.0 equivalent.

If the amount is less than 0.3 equivalent, sufficient compatibility of the polydiene component with the epoxy resin will not be imparted.

When the amount of compound [B] used is one equivalent or less relative to the acid anhydride group, the excess acid anhydride group may be left as is or may be ring-opened.

Furthermore, as an epoxy resin, per molecule, 1
For example, an epoxy resin obtained from bisphenol A and epichlorohydrin, an epoxy resin obtained from hydrogenated bisphenol A and epichlorohydrin, or bisphenol A and β-methylepichlorohydrin. , polyglycidyl ethers of novolac resins, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin or trimethylolpropane, and polyglycidyl esters of polycarboxylic acids such as adipic acid or phthalic acid.

The adduct [A] of a conjugated diene polymer and maleic anhydride is synthesized by a known method. That is, a conjugated diene polymer and maleic anhydride are mixed and heated at 50 to 300°C, preferably 150 to 210°C, 30°C.
It can be synthesized by reacting for minutes to 10 hours.

When an anti-gelling agent is required, add 0.01~ to the reaction system.
Add 5% by weight. The amount of maleic anhydride used is such that the content in the adduct [A] is 5 to 50% by weight, preferably 5 to 30% by weight.

If the content in the adduct [A] is 5% by weight or less,
It becomes difficult to impart compatibility with the epoxy resin, and if it exceeds 50% by weight, the subsequent modification reaction becomes difficult due to increased viscosity, and the effect of imparting flexibility to the epoxy resin decreases. .

Next, the reaction between the adduct [A] and the compound [B] having a secondary amino group in the molecule is carried out by a known method.

That is, the adduct [A] and the compound [B] are
It is obtained by reacting at 200°C, preferably 80 to 160°C for 30 minutes to 5 hours. In this case, a small amount of a catalyst such as a quaternary ammonium salt, a tertiary amine, or an organic acid is usually used as the catalyst. If necessary, an inert solvent such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, or ethylene glycol ethyl ether monoacetate can be used.

The reaction between the obtained modified adduct [C] and the epoxy resin is carried out by mixing the two at 50 to 250°C, preferably at 80°C.
Obtained by reacting at ~200°C for 30 minutes to 10 hours. The reaction is carried out by acid value tracking. If necessary, the reaction catalyst and reaction solvent described above can also be used.

The amount of the adduct-modified product [C] of a conjugated diene polymer for modifying the epoxy resin depends on the use of the modified epoxy resin, so it cannot be stated unconditionally.
5 to 100 parts by weight per 100 parts by weight, preferably 5 to 50 parts by weight
Parts by weight.

Since the epoxy resin modified according to the present invention has epoxy in its molecules, it can be used in the same way as ordinary unmodified epoxy resin, and the resulting cured product has excellent mechanical strength, adhesiveness, and heat resistance. Moreover, it is possible to obtain particularly excellent flexibility while maintaining various properties such as chemical resistance.

Therefore, this modified epoxy resin can be made into a cationic electrodeposition coating resin with excellent chipping resistance by aminating the remaining epoxy and further adding isocyanates, or can be used in various forms by combining with an appropriate curing agent. It is used for coating purposes, and is also used for molded products that have been added with fillers to provide elasticity and toughness.

Examples will be shown below, but the present invention is not limited thereto.

Example 1 Number average molecular weight 1680, viscosity at 20°C 650 centipoise, iodine value (Wiss method) 445, cis 1,4-structure 76%, trans 1,4-structure 23% and 1,2-vinyl structure 340 g of liquid polybutadiene with physical properties of 1%, 60 g of maleic anhydride, and 0.68 g of iron naphthenate (Fe = 5.0%) were placed in a 500 ml four-necked flask, and heated at 190°C under an N ₂ gas atmosphere for 4 hours.
By reacting for hours, maleated polybutadiene with a total acid value of 162 was obtained.

In a 500ml four-necked flask, add 200g of the above maleated polybutadiene, 32.7g of N-methylaniline, and 24g of benzyltrimethylammonium chloride.
A product having an acid value of 74.0 and a total amine value of 1 or less was obtained by charging 130 to 135° C. for 4 hours.

Next, 20 g of this product was reacted with 80 g of epi-bis epoxy resin (epoxy equivalent: 488, trade name Sumiepoxy ESA011, manufactured by Sumitomo Chemical Co., Ltd.) in an N ₂ gas atmosphere at 150 to 160°C for 3 hours to reduce the acid value. A homogeneous and highly transparent modified epoxy resin with an epoxy equivalent weight of 720 was obtained.

7.0g of this modified epoxy resin and BF ₃ .
C ₂ H ₅ NH ₂ complex 0.07g, ethylene glycol ethyl ether monoacetate (hereinafter referred to as ECA)
(abbreviated as )), combed to 3.0g, applied on a mild steel plate,
By baking at 160°C for 20 minutes, a highly transparent and glossy cured film was obtained.

It was confirmed from the clear properties of this cured film that the polybutadiene component was sufficiently compatible with the epoxy resin.

Furthermore, in a test on a sample with a film thickness of 20 μ, pencil hardness: 2H, Erichsen: 8 mm or more, Dupont impact value (0.5 kg load, center of impact 1/2 inch, lining, hereinafter the same conditions) 50 cm or more, and bending 2
It was found that sufficient flexibility was imparted at m/m or less.

On the other hand, 100g of modified epoxy resin, 48.7g of ECA,
Diethylamine 5.1gr, diethanolamine 7.3g
Confirm that the epoxy group has reacted by reacting at 80℃ x 3 hours under _N2 gas atmosphere,
Next, tolylene diisocyanate (2.4/
A urethane crosslinked resin was obtained by adding dropwise 67 g of a 70% ECA solution (2.6-condensation ratio = 80/20) and reacting for 2 hours.

This resin liquid was applied to a mild steel plate and baked at 180°C for 20 minutes to obtain a clear, glossy cured film.

This cured film had an Erichsen impact value of 8 mm or more and a Dupont impact value of 50 cm, confirming sufficient flexibility.

Example 2 Maleated polybutadiene obtained in Example 1
200g and diethylene glycol monobutyl ether 24.8g, N-methylaniline 16.4g and trimethylbenzylammonium chloride 25mg
was reacted at 150° C. for 3 hours in a N ₂ gas atmosphere to obtain a product with an acid value of 70 and a total amine value of 1 or less.

By reacting 25 g of this modified product, 75 g of epi-bis type epoxy resin (epoxy equivalent: 488), and 43 g of ECA at 150°C for 3 hours in an _N2 gas atmosphere, a homogeneous and transparent product with an acid value of 1 or less and an epoxy equivalent of 820 was produced. A modified epoxy resin was obtained.

10 g of this modified epoxy resin solution and 0.7 g of diaminodiphenylmethane were thoroughly mixed, applied to a mild steel plate, and baked at 160° C. for 20 minutes, resulting in a very clear cured film.

This cured film (20μ) had a pencil hardness of 2H, an Erichsen impact strength of 8 mm or more and a Dupont impact strength of 50 cm or more, and a bending test of 2 m/m or less, and was confirmed to have sufficient flexibility.

Comparative Example 1 Maleated polybutadiene obtained in Example 1
15 g and 85 g of Epibis type epoxy resin (epoxy equivalent: 488) were gelled during heating under _N2 gas atmosphere. This phenomenon was observed in the same way even if the ratio of the two used was changed, and the epoxy resin could not be modified by this method.

Comparative Example 2 Maleated polybutadiene obtained in Example 1
A half-esterified product having an acid value of 71 was obtained by reacting 30 g of n-amyl alcohol, 4.0 g of n _- amyl alcohol, and 5 mg of benzyltrimethylammonium chloride at 125 to 135° C. for 2 hours in an N 2 gas atmosphere. To this was added 136 g of Epibis type epoxy resin (epoxy equivalent: 488), and the reaction was further carried out at 150 to 160°C for 3 hours, so that the acid value became "0". The epoxy equivalent of this product was 708, and its appearance was white and lumpy. Furthermore, 7.0 g of this modified epoxy resin, 3.0 g of methyl ethyl ketone, and 0.6 g of diaminodiphenylmethane were mixed and dissolved, and this was coated on a glass plate and baked at 180°C for 20 minutes. Turbidity was observed, indicating that the polybutadiene component was not compatible with the epoxy resin.

That is, it is recognized that the modified system using only the concomitant components as compound [B] in the present invention has insufficient compatibility with the epoxy resin.

Claims (1)

[Scope of Claims] 1. An adduct of a conjugated diene polymer or a copolymer of a conjugated diene and a vinyl monomer with a number average molecular weight of 300 to 20,000 and an α/β-unsaturated dicarboxylic acid or its anhydride [A ] to general formula [] (Here, R ₁ and R ₂ are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom, and a methoxy group, and R ₃ is an alkyl group having 1 to 5 carbon atoms, a phenyl group, and a benzyl group, and n A modified epoxy characterized by reacting and/or mixing with an epoxy resin an adduct-modified product [C] obtained by reacting a compound [B] represented by Method for producing resin composition.