JPH021170B2 - - Google Patents

Description

[Detailed description of the invention] The present invention has excellent adhesive strength to metal plates etc.
This invention relates to a resin composition useful as a paint, an adhesive, etc. that provides a film with excellent processability.

Taking adhesives as an example, it is known that mixtures of carboxyl group-containing polyolefins and epoxy resins, and their curing components are suitable for adhering polyolefin resin films and metal plates, for example.

Regarding adhesion between a polyolefin resin film and a metal plate, carboxyl group-containing polyolefin alone is sufficient in terms of adhesive strength, but there are problems in the workability of painting the metal plate and there are also problems in terms of corrosion resistance. Mixtures of epoxy resins and curing components are one of the measures to improve these points, and fine particles of carboxyl group-containing polyolefins are dispersed in organic solvent solutions of epoxy resins and other components. Gives paintability,
The excellent corrosion resistance of epoxy resin compensates for the weaknesses of carboxyl group-containing polyolefins.

However, in order to melt the carboxyl group-containing polyolefin to form a continuous film and to sufficiently cure the epoxy resin, heating and drying at a relatively high temperature is required, which is one of the drawbacks of polyolefin resins. The problem arises as to how to prevent decomposition.

Normally, it is effective to mix a decomposition inhibitor such as BHT to prevent thermal decomposition, but the effect is not always complete when exposed to large volumes of hot air such as in gas oven drying, and the amount of Since increasing the amount of decomposition inhibitor has a negative effect on film performance, it is necessary to complete film formation with short heating to suppress thermal decomposition.

For example, drying at 200° C. for 1 to 2 minutes is a sufficient condition for forming a film of carboxyl group-containing polyolefin, but in order to sufficiently cure the epoxy resin, some measures are required.

For curing components that react only with epoxy groups, such as amines, use an amount greater than the chemical equivalent, or
It is necessary to combine it with a low molecular weight epoxy resin with a small epoxy equivalent, but in the case of the former, an excessive amount of the curing component remains in the film and harms the physical properties of the film, and in the case of the latter, short chains Because a network is formed, the flexibility, which is one of the characteristics of epoxy resin, is significantly impaired.

In order to achieve rapid curing with resin-based curing components such as butylated urea resins and phenolic resins, it is common to increase the amount, but in this case, a thermosetting reaction of the curing component itself occurs. Not much flexibility can be expected from the film, even in combination with a high molecular weight epoxy resin.

The present invention can address the above-mentioned problems and is a resin composition useful for paints, adhesives, and the like.
That is, (A) a polyolefin and/or a carboxyl group-containing polyolefin, (B) a compound containing two glycidyl groups (a), a compound having three or more glycidyl groups (b), and divalent or trivalent or more valent phenols ( (c) A branched epoxy resin obtained by reacting (C) a branched epoxy resin, or an unbranched epoxy resin, and (C) a curing component of the epoxy resin.

(B) in the present invention is used to improve the drawbacks of linear epoxy resins as described above.

In other words, the branched epoxy resin (B) has a structure in which branches are formed from the main chain of a normal linear epoxy resin, and the end of the branch chain is an epoxy group. Because it has many groups and has a branched structure, it has an excellent ability to create a network structure.

Therefore, it is an extremely effective resin for applications that require short-time curing as mentioned above, and in particular, it can be cured sufficiently in a short time without sacrificing the inherent flexibility of epoxy resin. This is difficult to achieve by other means.

The compound (A) containing two glycidyl groups used in the branched epoxy resin (B) is, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, or a compound obtained from bisphenol A and epichlorohydrin. The epi-bis type epoxy resin is preferably bisphenol A diglycidyl ether or one containing bisphenol A diglycidyl ether as a main component.

Compounds (b) having three or more glycidyl groups include trihydroxybenzene glycidyl ether,
There are pentaerythritol glycidyl ether, glycidyl ether of polyphenols, etc.
From the viewpoint of physical properties, it is preferable to use a novolac type epoxy resin (molecular weight of about 400 to 1000).

Examples of divalent or trivalent or higher phenols (c) include bisphenol A, bisphenol F, diphenolic acid, resorcinol, hydroquinone, catechol, phloroglucinol, tetrachlorobisphenol A, or novolaks obtained from phenols and formaldehyde. It may be a resin or a resol resin. Bisphenol A is preferred.

In order to synthesize the branched epoxy resin according to the invention, a compound having two glycidyl groups (a), a compound having three or more glycidyl groups (b), and a divalent or trivalent or more valent phenol (c) are used. Mix, heat and melt, add a catalyst to accelerate the reaction if necessary,
Obtained by heating and stirring. Examples of the catalyst include caustic soda and triphenylphosphine.

There are no particular restrictions on the blending ratio of each component, but
If the amount of the compound (b) having three or more glycidyl groups is too large, the degree of branching will increase, and if the degree of reaction is kept low to prevent this, a large amount of unreacted substances will remain, which will affect the performance of the epoxy resin. This is not desirable as it will cause damage.

In addition, as another means to prevent gelation, reducing the blending amount of the compound (b) having three or more glycidyl groups will reduce the difference from normal epi-bis type epoxy resin, and if this is used, Even if it is used as a paint for metal coating or for cans, there will be almost no superiority in terms of performance balance. To express this more clearly, if we express the case where one branch appears on the main chain as a branching degree of 1, then the average branching degree is
A range of 0.1 to 3.0 is appropriate. The average degree of branching can be expressed as follows.

Average degree of branching = Number of moles of branching / Number of moles of resin Number of moles of branching = Amount of compound (b) used / Branching equivalent of compound (b) Branching equivalent of compound (b) = Molecular weight of compound (b) / Molecular weight of compound (b) Number of glycidyl groups -2 In other words, compound (2) is considered to have two glycidyl groups incorporated into the main chain, and the remaining glycidyl groups serve as branching sites. Therefore, a degree of branching of 1 means that there is one branched chain in the final main product.

That is, when it exceeds 3, bonding between branched chains tends to occur and there is an extremely high risk of gelation, and when it is less than 0.1, the effect of branched chains is not noticeable and characteristics are difficult to be seen. Note that at a level of 1 or less, it appears that there is a shortage, but in reality the product is not uniform and the level is 1.
It is a mixture of those with higher branching degrees and those with almost no branching, and even with an average of about 0.1, it is clearly 0.
A better performance balance than that of the previous one is obtained. Therefore, the blending ratio (weight ratio) of components (a), (b), and (c) is in the range of (A):(B):(C)=65-10:0.5-60:20-40. suitable. The resin obtained in this range has a weight average molecular weight of 8000 to 80000, a number average molecular weight of 1500 to 5000, and an epoxy equivalent of 500 to 2000.
For example, Epi-Bis type typical product Epicoat #1007 has a weight average molecular weight of 11,700 and a number average molecular weight of
4200, epoxy equivalent: 1940 (actually measured), it has the characteristics of a wider molecular weight distribution and a smaller epoxy equivalent. This suggests that it has a completely different performance balance than normal epi-bis type epoxy resins, especially in terms of curability.In fact, when combined with a curing component, the ability to create a network structure is remarkable. Are better.

The mixing ratio of the branched epoxy resin and the unbranched epoxy resin can be freely selected depending on the desired performance, but in general, the mixing ratio of the branched epoxy resin and the unbranched epoxy resin is 5:95 to 95:5. The range is preferably 50:50 to 20:80 in consideration of cost. Additionally, epoxy resins are rarely used alone as paint resins, and are usually mixed with curing components to form paints. is exactly the same. The curing component (C) is a resin-based curing component such as phenol resin, urea resin, benzoguanamine resin, polyamide resin, melamine resin, acrylic resin, or in combination with a low molecular weight curing component such as metal chelate, amine, isocyanate, etc. It can be used as a thermosetting paint or adhesive.

It is also possible to make an oxidative polymerization type by esterifying with fatty acids, and as is currently being done, this epoxy ester can be used as a base, further modified with styrene, etc., and combined with melamine resin, etc. to make paints. There is no problem in doing so.

Of course, it can also be made into a paint by handling it in the same way as general epi-bis type epoxy resin, such as by making it water-soluble by modifying it with acrylic acid or by combining it with the above-mentioned curing component to make a powder paint.

The blending amount may be determined depending on the application, but in combination with a resin-based curing component, the range of epoxy resin:resin-based curing component = 95:5 to 5:95 is preferred. More preferably 70:30-5:
It is 95. In combination with low molecular weight curing components such as metal chelates, the ratio of branched resin mixed epoxy resin to curing component is preferably in the range of 80:20 to 99:1.

Regarding (A), polyethylene, polypropylene, copolymers of ethylene and propylene, ethylene-propylene-diene terpolymers, copolymers of ethylene and butene-1, and these polyolefins are mixed with maleic acid and maleic anhydride. acids, those modified with α,β-ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid, polyolefins modified with α,β-ethylenically unsaturated carboxylic acids and α,β-ethylenically unsaturated carboxylic acids, etc.
Those modified with β-ethylenically unsaturated carboxylic acid alkyl esters, those obtained by copolymerizing olefin monomers such as ethylene, propylene, butene, and α,β-ethylenically unsaturated carboxylic acids, those modified with olefin monomers and α,β-ethylene These carboxyl group-containing polyolefins are copolymerized with unsaturated carboxylic acid alkyl esters and then saponified. Magnesium acetate, aluminum hydroxide,
A combination of metal compounds such as zinc oxide and calcium carbonate, or a mixture thereof can be used.

Regarding the ratio of (A) and (B), the weight ratio is 95:5 ~
The ratio is preferably 5:95. In order to use (A), (B) and (C) in paints, adhesives, etc., it is usually preferable to disperse or dissolve them in an organic solvent. Components such as surfactants and lubricants, or pigments such as titanium oxide and zinc oxide may be added as necessary.

The present invention will be explained below based on Examples and Comparative Examples. In the examples, "parts" and "%" indicate parts by weight and % by weight, respectively.

[Example of manufacturing branched epoxy resin]

The branched epoxy resin used in the Examples of the present invention was prepared as follows.

Epoxy resin B-1 (average degree of branching set at 0.4) Epicoat #828 (epoxy resin manufactured by Yuka Ciel Epoxy Co., Ltd.) 62.80 parts DEN438 (novolac type epoxy resin manufactured by Dow Chemical Company) 6.44 Bisphenol A 30.75 Caustic soda 0.01 (total) 100) When the above four substances are heated and melted and stirred, the temperature rises to 180°C due to the heat of reaction. The temperature will start to drop after about 10 minutes, but keep it at 175-180℃.
Let react for 1 hour. After the reaction was completed, the mixture was cooled to obtain a solid resin.

The obtained resin had a number average molecular weight of 3,400, a weight average molecular weight of 18,900, and an epoxy equivalent weight of 1,100.

Epoxy resin B-2 (average degree of branching set at 0.6) Epicote #828 61.26 parts DEN438 4.68 Bisphenol A 34.05 Caustic soda 0.01 Total 100 When the above four substances are heated and melted and stirred, the temperature rises to 180°C due to the heat of reaction. The temperature will start to drop after about 10 minutes, but keep it at 175-180℃ until 1
Allow time to react. After the reaction was completed, the mixture was cooled to obtain a solid resin.

The obtained resin had a number average molecular weight of 4,600, a weight average molecular weight of 25,000, and an epoxy equivalent weight of 1,900.

Example 1 Branched epoxy resin B-1 was dissolved in butyl cellosolve to a solid content of 45%, and added to 113 parts of this solution.
Maleic anhydride with a solid content of 10% was prepared by adding 15 parts of butylated urea resin Supervecamine P-138 (manufactured by Nippon Reichhold), using xylene as a thermal solvent, and methyl isobutyl ketone as a poor solvent. 600 parts of a modified polypropylene suspension (containing 0.9% maleic anhydride) was added, stirred at high speed for 30 minutes, and passed through a homogenizer to form an adhesive.

Apply this adhesive to an electrogalvanized steel sheet with a thickness of 0.5 mm using a roll coater to a dry film thickness of 10 μm. Immediately after hot air drying (200°C, 2 minutes), the film thickness
A 100 μm polypropylene film was crimped using a hot roll laminator, further heated and fused in a hot air oven at 200° C., and then cooled with water to obtain a polypropylene-coated metal plate.

Regarding the obtained polypropylene coated metal plate,
When an Erichsen peel test based on JISK-6744-8.2 was performed, there was no peeling of the film, and no peeling of the film was observed even after immersion in boiling water for 30 minutes after the Erichsen peel test.

In addition, when a salt spray test based on JISZ 2371 was conducted, there was no change after 100 hours, indicating good corrosion resistance.

Example 2 A similar polypropylene-coated metal plate was obtained by replacing the butylated urea resin of Example 1 with 20 parts of a blocked isocyanate obtained by reacting a polyether polyol with toluene diisocyanate and further blocking with methyl ethyl ketoxime.

The adhesive strength of the obtained coated metal plate was very good as in Example 1.

Further, the results remained good with no change even after 100 hours of salt spray test.

Example 3 Instead of branched epoxy resin B-1 in Example 1, 30 parts of branched epoxy resin B-2, 20 parts of unbranched epoxy resin Epicoat 1007 (manufactured by Yuka Ciel Epoxy Co., Ltd.) and 50 parts of butyl cellosolve were added. When a similar coated metal plate was prepared using 100 parts of the solution dissolved in 100 parts of the 100 parts of the solution and tested, the adhesion and corrosion resistance were as good as in Example 1.

Example 4 Instead of 600 parts of the maleic anhydride-modified polypropylene suspension in Example 1, 6 parts of maleic anhydride-modified polypropylene (maleic anhydride content 0.9%) and ethylene propylene copolymer (molecular weight
225000, MI=30) suspension in 90 parts of xylene and methyl isobutyl ketone mixed solvent
A similar coated metal plate was made using 600 parts and a series of tests were conducted. As a result, as in Example 1, the adhesiveness and corrosion resistance were good.

Claims (1)

[Scope of Claims] 1 (A) a polyolefin and/or a carboxyl group-containing polyolefin, (B) a compound containing two glycidyl groups (a), a compound having three or more glycidyl groups (b), and a divalent or trivalent compound A resin composition comprising a branched epoxy resin obtained by reacting the above phenols (c), or the branched epoxy resin and an unbranched epoxy resin, and (C) a curing component of the epoxy resin. 2. The resin composition according to claim 1, which is obtained by dispersing or dissolving (A), (B), and (C) in an organic solvent. 3. The resin composition according to claim 1 or 2, wherein (a) contains bisphenol A diglycidyl ether or bisphenol A diglycidyl ether as a main component. 4. The resin composition according to any one of claims 1 to 3, wherein (b) is a novolac type epoxy resin. 5. The resin composition according to any one of claims 1 to 4, wherein (c) is bisphenol A. 6. The resin composition according to any one of claims 1 to 5, wherein (A) and (B) are used in a weight ratio of 5:95 to 95:5. 7 (C) is a resin-based curing component, and (B) and (C) are used in a weight ratio of 70:30 to 95:5 according to any one of claims 1 to 6. resin composition.