JPH04366156A - Curable resin composition - Google Patents

Abstract

PURPOSE:To obtain a curable resin composition which can give a cured product excellent in all of mechanical strengths, water resistance, solvent resistance, heat resistance, durability and adhesion to substrate and can be used for coating materials, surface treatments, coatings, adhesives, sealing materials, molding materials, etc. CONSTITUTION:The above mentioned cured product can be obtained from a curable resin composition comprising a compound having at least two 2- oxazoline groups, a compound having at least two mercapto groups and a carboxylic polymer.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a novel curable resin composition. More specifically, this invention cures in a short time even at room temperature (for example, 0 to 40 degrees Celsius), and has all the characteristics of mechanical strength, water resistance, solvent resistance, heat resistance, durability, and adhesion to substrates. The present invention relates to a curable resin composition that produces a cured product with excellent properties and is useful for applications such as paints (including coating agents), surface treatment agents, adhesives, sealants, and molding materials.

0002

[Prior Art] The reaction between a 2-oxazoline group and a carboxyl group is known, and the ring-opening reaction of the oxazoline group results in an esteramide bond: -CONH-CR (R')-CR"(R"') -O
It is known to produce CO-. Tokuko Sho 45-3
Publication No. 1467 discloses that a linear polyesteramide can be obtained by reacting bis-2-oxazoline with a dicarboxylic acid. Also, a method for producing a crosslinked resin using this reaction is known. For example, in Japanese Patent Publication No. 44-31821, a poly-2-oxazoline compound is added to a polymer having a carboxyl group in the side chain. JP-A-52-19727 discloses a method of obtaining a crosslinked polymer by applying a resin composition containing a polycarboxylic acid compound and an oxazoline resin containing a free oxazoline group at the side chain or end. Crosslinking to obtain a coating film is described in Journal of Polymer Science, Polymer Chemistry Edition, Vol. 23, pp. 1805-1817 (1985) [Jou
rnal of Polymer Science:
Polymer Chemistry Edition
, Vol. 23, 1805-1817 (1985)
] discloses a method of crosslinking a copolymer containing a pendant cyclic imino ether with a dicarboxylic acid.

On the other hand, the reaction between a 2-oxazoline group and a mercapto group is also known, and the ring-opening reaction of the 2-oxazoline group results in a thioetheramide bond: -CONH-CR (R')-CR"(R"')- S
- is known to be generated. Tokuko Showa 63-540
No. 08 discloses that a linear polythioetheramide can be obtained by reacting bis-2-oxazoline with a dimercapto compound. In addition, the method for producing crosslinked resins or crosslinked elastomers using this reaction is also described in the above-mentioned Journal of Polymer Science, Polymer Chemistry Edition No. 23.
Volume 1805-1817 (1985) (Method of crosslinking a copolymer containing a pendant cyclic imino ether with a polyvalent thiol), Japanese Patent Publication No. 1-118412
No. 1 (Method of vulcanizing an acrylic elastomer having a 2-oxazoline group with a polymercapto compound), Japanese Patent Publication No. 2-37945 (Method of vulcanizing an acrylic elastomer containing an oxazoline group with a polymercapto compound)
has been disclosed.

0004

[Problems to be Solved by the Invention] When a compound having a 2-oxazoline group and a compound having a carboxyl group are used in combination, the curing speed is too slow (see Comparative Example 6 in Table 8 below).
(Refer to gel fraction data), even after sufficient curing, the cured product may have unsatisfactory mechanical strength, water resistance, solvent resistance, heat resistance, durability, and adhesion to the substrate. be.

Although the combination of a compound having a 2-oxazoline group and a compound having a mercapto group has a high curing speed, the resulting cured product is unsatisfactory in mechanical strength, durability, and adhesion to the substrate. is the current situation. This invention applies to relatively low temperatures such as room temperature (e.g. 0 to
40℃. (same below) can be cured in a short time, and the cured product has excellent mechanical strength, water resistance,
An object of the present invention is to provide a curable resin composition that has excellent solvent resistance, heat resistance, durability, and adhesion to a substrate.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a compound (A) having two or more 2-oxazoline groups, a compound (B) having two or more mercapto groups, and a carboxyl A curable resin composition containing a group-containing polymer (C) is provided. Compounds having two or more 2-oxazoline groups (A
) is a polyoxazoline compound (A
-1) and oxazoline group-containing polymer (A-2)
One or more of these. The 2-oxazoline group has the following formula 1:

[0007]

[Chemical formula 1]

It is expressed as follows. That is, in the 2-oxazoline group, one or more hydrogen atoms may be substituted. Examples of the polyoxazoline compound (A-1) include 2,2'-bis-(2-oxazoline), 2,2'-
Methylene-bis-(2-oxazoline), 2,2'-ethylene-bis-(2-oxazoline), 2,2'-trimethylene-bis-(2-oxazoline), 2,2'-tetramethylene-bis- (2-oxazoline), 2,2'
-hexamethylene-bis-(2-oxazoline), 2,
2'-octamethylene-bis-(2-oxazoline),
2,2'-ethylene-bis-(4,4'-dimethyl-2
-oxazoline), 2,2'-p-phenylene-bis-
(2-oxazoline), 2,2'-m-phenylene-bis-(2-oxazoline), 2,2'-m-phenylene-bis-(4,4'-dimethyl-2-oxazoline),
Examples include bis-(2-oxazolinylcyclohexane) sulfide and bis-(2-oxazolinylnorbornane) sulfide, and any one of these may be used alone or two or more may be used in combination.

The oxazoline group-containing polymer (A-2) is
It is formed by polymerizing addition-polymerizable oxazoline (a-1) and, if necessary, at least one other monomer (a-2). What is addition polymerizable oxazoline (a-1)?
This is expressed by the following formula 2.

0010

[Case 2]

Specific examples of the addition polymerizable oxazoline (a-1) include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2- Examples include oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and 1 selected from these groups. Seed compounds can be used alone or
Alternatively, two or more kinds of compounds can be used in combination. Among them, 2-isopropenyl-2-oxazoline is suitable because it is industrially easily available. The amount of addition-polymerizable oxazoline (a-1) used is not particularly limited, but is preferably 1% by weight or more in the polymer (A-2). If the amount is less than 1% by weight, the degree of curing will be insufficient, and durability, water resistance, etc. will tend to be impaired.

Other monomers (a-2
) is not particularly limited as long as it is a monomer that can be copolymerized with the addition-polymerizable oxazoline (a-1) and does not react with the oxazoline group. For example, methyl (meth)acrylate, (meth) (meth)acrylic acid esters such as butyl acrylate and 2-ethylhexyl (meth)acrylate; unsaturated nitriles such as (meth)acrylonitrile; (
Unsaturated amides such as meth)acrylamide and N-methylol(meth)acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; Halogenated α, β-unsaturated monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride; α, β-unsaturated monomers such as styrene, α-methylstyrene, etc.
Examples include β-unsaturated aromatic monomers, and one kind of these compounds or a mixture of two or more kinds thereof can be used.

The polymer (A-2) is prepared by adding the addition-polymerizable oxazoline (a-1) and, if necessary, at least one other monomer (a-2), using a conventionally known polymerization method, such as suspension polymerization. , solution polymerization, emulsion polymerization, etc. Compound(
A) may be supplied in any form such as an organic solvent solution, an aqueous solution, a nonaqueous dispersion, an emulsion, or a powder.

In the present invention, the compound (B) having two or more mercapto groups includes, for example, 2,3-
Aliphatic mercapto compounds such as dimercapto-1-propanol, 1,4-dimercapto-2,3-butanediol, 2,3-dimercaptosuccinic acid, 1,6-dimercaptohexane, dimercapto diethyl ether; 3,4
-dimercaptotoluene, bis(4-mercaptophenyl) sulfide, 4-t-butyl-1,2-benzenedithiol, 2,5-dimercapto-1,3,4-thiadiazole, 2,4,6-trithiol-s -triazine, 2-dibutylamino-4,6-dithiol-s-triazine, 2-phenylamino-4,6-dithiol-s
- Aromatic mercapto compounds such as triazine, etc., but aromatic mercapto compounds, especially 2-dibutylamino-4,6
-dithiol-s-triazine and 2,4,6-trithiol-s-triazine are industrially readily available and suitable.

In this invention, the carboxyl group-containing polymer (C) is obtained by polymerizing an unsaturated carboxylic acid (c-1) and, if necessary, at least one other monomer (c-2). It is a polymer (C-I) or a condensation polymer (C-II) containing a carboxyl group. Examples of the unsaturated carboxylic acid (c-1) include unsaturated monocarboxylic acids such as (meth)acrylic acid, cinnamic acid, and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid; Examples include monoesters, and one type or a mixture of two or more types selected from these groups can be used. The amount of unsaturated carboxylic acid (c-1) used is not particularly limited, but is preferably in the range of 1 to 20% by weight based on the polymer (C). If the amount used is less than 1% by weight, it will not be a substantially effective amount for the reaction with compound (A), and if it exceeds 20% by weight, the water resistance of the cured product will decrease, which is not preferred. In addition,
When a dicarboxylic acid is used instead of the polymer (C), there are problems in that the adhesion to the substrate, solvent resistance, and durability are low.

Other monomers (c-2
), in addition to the above-mentioned monomer (a-2), monomers having a functional group that can react with an oxazoline group, such as aminoethyl (meth)acrylate, glycidyl (meth)acrylate, etc.
Examples include acrylate and p-vinylphenol, and one or more of these can be used.

Polymer (C-I) can be produced by the same polymerization method as polymer (A-2). Polymer (C
As -II), a wide variety of known resins can be used, such as polyester resins, polyurethane resins, and polyamide resins containing carboxyl groups. The polymer (C) may be supplied in any form such as an organic solvent solution, an aqueous solution, a nonaqueous dispersion, an emulsion, or a powder.

In the present invention, the blending ratio of compound (A), compound (B) and polymer (C) is not particularly limited, but for example, compound (A) may be mixed with 100 parts by weight of compound (A). B) 1 to 100 parts by weight, polymer (C
) 50 to 1000 parts by weight are preferred. Compound(
If the amount of B) is less than 1 part by weight, the curing speed and degree of curing will be insufficient, and the durability and water resistance of the cured product may be impaired. The mechanical strength and adhesion to the substrate tend to be impaired. If the amount of polymer (C) is less than 50 parts by weight, the adhesion to the substrate will be impaired, and if it exceeds 1000 parts by weight,
The degree of curing is insufficient, and the durability, water resistance, etc. of the cured product may be impaired.

The curable resin composition of the present invention has film-forming properties and can be used as a paint (or coating agent), a surface treatment agent, an adhesive, a sealant, etc. In this case, the curable resin composition may contain, for example, a plasticizer such as a phthalate ester; a filler such as calcium carbonate, talc, clay, or mica; , pigments such as zinc white, red oxide, and phthalocyanine; dyes; thickeners such as polyvinyl alcohol, hydroxyethyl cellulose, and starch; dispersants; wetting agents; antifoaming agents such as silicones, and the like may be appropriately contained. When using the curable resin composition of the present invention as a paint, surface treatment agent, coating agent, adhesive, sealant, etc., it can be applied to a substrate by a method commonly used in the industry, such as by using a roll coater, spraying, dipping, or brush coating. After applying it, it can be cured. Substrates include, for example, wood, plastic, organic or inorganic fibrous materials (e.g. paper,
(cloth, etc.), metal, inorganic materials (e.g., inorganic board, etc.)
etc. can be used. Furthermore, as will be described later, it is also possible to make films, tapes, sheets, etc. by a casting method.

The curable resin composition of the present invention can also be used as a molding material. In this case, the curable resin composition may contain, for example, fillers, pigments, dyes, fibers, etc., which are commonly used in molding materials, as necessary to the extent that the object of the present invention is not impaired. You can stay there. When using the curable resin composition of the present invention as a molding material, for example, press method, injection molding method, transfer molding method, reaction injection molding method (RIM method), SMC method, etc.
It may be formed by various methods.

The method for producing the curable resin composition of the present invention is not particularly limited, and a wide range of methods commonly used by those skilled in the art can be applied. For example, compound (B), polymer (C), and other additives mentioned above may be added to a solution, dispersion, or powder of compound (A) and mixed. The curable resin composition of the present invention can be used at room temperature (for example, from 0 to 40°C).
It can be cured in a short period of time (e.g., several days) even at a temperature of Produces a cured product that has heat resistance, durability, and adhesion to substrates.

[0022]

[Operation] The curable resin composition of this invention has two or more
- Contains a compound (A) having an oxazoline group, a compound (B) having two or more mercapto groups, and a carboxyl group-containing polymer (C), so when cured, mechanical strength, water resistance, Produces a cured product that has excellent solvent resistance, heat resistance, durability, and adhesion to substrates.

Although it is not clear why the combination of compound (A), compound (B) and polymer (C) produces such effects, the combination of compound (A)
) and the compound (B) react quickly to achieve short-time curing, and the polymer (C) forms a semi-IPN [IPN: interpenetrating compound] with this cured matrix.
Polymer network
It is thought that the cured product exhibits the excellent performance as described above by intertwining with the oxazoline group derived from the compound (A).

[0024]

[Examples] Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples. In the following, unless otherwise specified, "%" means "% by weight" and "parts" means "parts by weight." - Production Example 1 (Production Example of Compound (A)) - Into a flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer and dropping funnel, 782.4 parts of deionized water and Hytenol N-08 (No. Polyoxyethylene nonylphenyl ether sulfate ammonium salt (manufactured by Ichi Kogyo Seiyaku Co., Ltd.) 15%
Prepare 128 parts of aqueous solution and add appropriate amount of ammonia water (28%
) to adjust the pH to 9.0, and heated to 70° C. while slowly flowing nitrogen gas. 64 parts of a 5% aqueous solution of potassium persulfate was poured into the solution, followed by 3 parts of a monomer mixture of 288 parts of butyl acrylate, 320 parts of styrene, and 32 parts of 2-isopropenyl-2-oxazoline prepared in advance. dripped over time. During the reaction, nitrogen gas was continuously blown into the flask to maintain the temperature inside the flask at 70±1°C. After the dropwise addition was completed, the temperature was maintained at the same temperature for 2 hours, and then the internal temperature was raised to 80°C and stirring was continued for 1 hour to complete the reaction. Thereafter, it was cooled to obtain an aqueous resin dispersion (1) with a nonvolatile content of 39.8% and a pH of 8.0.

-Production Examples 2 to 5 (Production Examples of Compound (A)) - In the above Production Example 1, the same operations as Production Example 1 were repeated except that the polymer composition was changed as shown in Table 1 to obtain an aqueous Resin dispersion (2
) to (5) were obtained. - Production Examples 6 and 7 (Production Example of Polymer (C)) - In Production Example 1 above, the same operation as Production Example 1 was repeated except that the polymer composition was changed as shown in Table 3 to disperse the aqueous resin. liquid (6
), (7) were obtained. However, pH adjustment using ammonia water was performed after the reaction was completed.

Table 1 shows the polymer composition, nonvolatile content concentration, and pH of the aqueous resin dispersions obtained in Production Examples 1 to 5. Table 2
, 3 shows the polymer composition, nonvolatile content concentration, and pH of the aqueous resin dispersions obtained in Production Examples 6 and 7 and the commercially available aqueous resin dispersions used below. - Production Example 8 (Production Example of Compound (A)) - 4 with a stirrer, thermometer, cooler, dropping funnel and nitrogen gas introduction tube
A neck flask was charged with 100 parts of xylene, and the temperature was raised to 90°C. While blowing nitrogen gas into the mixture, 40 parts of methyl methacrylate, 40 parts of butyl acrylate, 20 parts of 2-isopropenyl-2-oxazoline, and perbutyl O (t-butyl peroxy-2-
A mixture consisting of 5 parts of ethylhexanoate) was added dropwise from the dropping funnel over 3 hours, kept at 90°C for 3 hours, and then cooled to room temperature to obtain a resin solution (10) with a non-volatile content of 49.8%. .

-Production Examples 9 and 10 (Production Example of Compound (A)) -Production Example 8
, except that the polymer composition was as shown in Table 2.
Repeat the same operation as in Production Example 8 to prepare resin solution (11),
(12) was obtained. - Production Example 11 (Production Example of Polymer (C)) - In Production Example 8, the same operation as Production Example 8 was repeated except that the polymer composition was changed as shown in Table 3 to obtain a resin solution (13). I got it.

Table 2 shows the polymer compositions, nonvolatile content concentrations (commercial products do not contain solvents) of the resin solutions obtained in Production Examples 8 to 10, and the commercially available polyoxazoline compounds used below.
Indicates pH. Table 3 shows the polymer composition and nonvolatile content concentration of the resin solution obtained in Production Example 11.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

-Examples 1 to 7 and Comparative Examples 1 to 4- (Film physical properties) Aqueous resin dispersions were prepared according to the formulations shown in Table 4, and treated under conditions of 20 ± 0.5°C and 75 ± 3% RH. After casting on a tetrafluoroethylene resin plate, the film was dried in air at room temperature (20° C.) for one day and night to form a film with a thickness of about 0.3 mm. The obtained film was left under the same conditions for 7 days, and then used as a test piece and subjected to the following tests. The results are shown in Tables 5 and 6.

(1) Solvent Resistance A test piece was immersed in acetone at room temperature for 72 hours, and its swelling rate and dissolution rate were calculated according to the following equations 1 and 2.

[0034]

[Math 1]

[0035]

[Math 2]

(2) Film strength Using an Instron tensile tester, the tensile speed was 10.
Measured in cm/min. (3) Boiling water resistance The appearance of the film after being immersed in boiling water for 4 hours was observed. In addition, in Table 4, mercapto compounds (B-1) to (B-3
) is as follows.

(B-1): 2,4,6-trithiol-s-triazine (B-2): 3,4-dimercaptotoluene (B-3)
:2,3-dimercaptosuccinic acid (adhesive strength) Using an aqueous resin dispersion prepared according to the formulation shown in Table 4, Kanakin cloth (1 mm thick) and SUS plate (2 mm thick) were bonded together under the following bonding conditions. pasted together.

[Lamination conditions] Coating amount: 12g/30cm2 Coating method: Manual roll press conditions: 0.5kg/cm at room temperature (20°C)
Press curing for 3 hours at room temperature (20° C.) for 5 days The normal strength, water resistance strength, heat resistance strength, and boiling water resistance strength of the obtained bonded board were measured according to the following methods. The results are shown in Tables 5 and 6.

(4) Normal strength 180 degree peeling strength was measured at 20°C and 60% RH. (5) Water resistance: 180°C while wet after being left in water at 20°C for 20 hours.
The peeling strength was measured.

(6) Heat Resistance Strength The 180 degree peeling strength was measured immediately after being left at 60° C. for 1 hour. (7) Boiling Water Resistance Strength After being immersed in boiling water for 4 hours, it was left in water at 20°C for 30 minutes, and the 180 degree peeling strength while wet was measured.

Peeling strength was measured using an Instron tensile tester at a tensile speed of 30 cm/min.

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

As shown in Tables 5 and 6, the curable resin compositions of Examples produced cured products with excellent film properties and adhesive strength. Among film physical properties, film strength refers to mechanical strength, boiling water resistance refers to water resistance, heat resistance, and durability, water resistance refers to water resistance and adhesion, heat resistance refers to heat resistance and adhesion, and boiling water resistance refers to water resistance and adhesion. Strength represents water resistance, heat resistance, durability, and adhesion. Comparative Examples 1 and 3 were inferior in all physical properties other than solvent resistance, and Comparative Examples 2 and 4 were inferior in all physical properties other than elongation.

- Examples 8 to 14 and Comparative Examples 5 and 6 - Resin solutions were prepared according to the formulations shown in Tables 7 and 8. These resin solutions were cast onto a tetrafluoroethylene resin substrate. These were dried at 20° C. for 24 hours under reduced pressure of 90 mmHg, and then heat-treated under the conditions shown in the gel fraction columns of Tables 7 and 8, each having a thickness of approximately 0.3 m.
A film of m was obtained. This film was immersed in acetone for 24 hours, and the gel fraction was calculated using the following formula (3):

[0047]

[Math 3]

Calculated according to the following. For other tests, it was cast on a steel plate, dried under reduced pressure as before, and then heated at 120°C for 60 minutes to obtain a film thickness of about 0.1 mm.
A coating film was obtained. Each coating film was evaluated by the following tests, and the results are shown in Tables 7 and 8. (8) Checkerboard test A test was conducted and evaluated in accordance with 8.5.1 of Japanese Industrial Standard K5400.

(9) Pencil scratch test A test was conducted using a paint film pencil scratch tester under a load of 500 g in accordance with Japanese Industrial Standard K5401. (10) Solvent resistance test After rubbing the paint film 20 times with absorbent cotton impregnated with methyl ethyl ketone, the appearance of the paint film was as follows: ◎～○
Evaluation was made on a 3-grade scale from ~×.

◎: No change. ○: The gloss of the coating film has disappeared. ×: The coating film peeled off from the test plate. (11) Salt Spray Test A salt spray test was conducted in accordance with 9.1 of Japanese Industrial Standard K5400. After spraying was continued for 240 hours, the condition of the coating film was evaluated in the following three grades.

Good: Rust width within 2 mm from the cross cut portion. Fairly good: Rust width from cross cut part is over 2mm, 4mm
Below and without blister. Defective: Rust width over 4mm from the cross cut part, or blisters. In addition, mercapto compounds (B-4) and (B
-5) and (B-6) are as follows.

(B-4): 2-dibutylamino-4,6-dithiol-S-triazine (B-5): 4-t-butyl-1,2-benzenethiol (B-6): 1,6 -dimercaptohexane

0053
]

[Table 7]

[0054]

[Table 8]

As shown in Tables 7 and 8, the curable resin compositions of Examples have a high gel fraction, no or almost no peeling in the grid test, high pencil hardness, and excellent solvent resistance and Salt spray test results are good. The gel fraction is an index of curing speed, and the higher the gel fraction is, the faster the curing is. The grid test is an index of adhesion, and the larger the value, the better the adhesion. The pencil scratch test is an indicator of mechanical strength, and the higher the number before H, the greater the mechanical strength. Salt spray test is an indicator of water resistance and durability. Comparative Example 5 was inferior in adhesion and salt spray test, and Comparative Example 6 was inferior in adhesion and salt spray test.
However, the curing speed is slow, and mechanical strength, solvent resistance, water resistance, and durability are all inferior. Comparative Example 7 and Example 8
When compared with Example 8, the curing time is faster and the adhesion, mechanical strength, solvent resistance, water resistance, and durability are better.

[0056]

[Effects of the Invention] The cured product of the curable resin composition of the present invention has excellent mechanical strength, water resistance, solvent resistance, heat resistance, durability, and adhesion to substrates. For,
It can be suitably used as a paint, a surface treatment agent, a coating agent, an adhesive, a sealant, a molding material, etc. Moreover,
This curable resin composition can be heated at room temperature (for example, 0 to 40°C).
), so if it is cured at room temperature,
It does not require a large amount of heating energy for curing, and is used when forming a film on or impregnating a substrate to cure it, such as plastics, organic fibers, paper, etc., or when it is difficult to heat. This is particularly useful when performing so-called on-site construction.

Claims (2)

[Claims] 1. A curable resin composition comprising a compound (A) having two or more 2-oxazoline groups, a compound (B) having two or more mercapto groups, and a carboxyl group-containing polymer (C). Claim 2: Based on 100 parts by weight of compound (A),
Compound (B) 1-100 parts by weight, polymer (C) 50-1
2. The curable resin composition according to claim 1, wherein the proportion is 0.000 parts by weight.