JPS5953281B2 - Curing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a curable substance having an ethylenically unsaturated group in its molecule is cured at room temperature using a dialkyl peroxide type organic peroxide in the presence of copper.

The present invention relates to a method of curing at low temperatures. Conventionally, it is well known that in curable compositions in which a curable substance having an ethylenically unsaturated group in the molecule and copper coexist, the curability of the curable substance through polymerization is often hindered by the copper. ,or,
Example in real life.

It is also known that copper powder and the like are used as stabilizers to prevent polymerization during the production of substances having ethylenically unsaturated groups in their molecules, such as methyl methacrylate. However, while the above-mentioned properties of copper can be effectively used for purposes such as stabilizers, for example, when a curable resin having an ethylenically unsaturated group in its molecule coexists with or comes into contact with copper, it cures. This is a major hindrance in applications such as paints, inks, adhesives, molded products, etc. in which curable substances such as curable resins having ethylenically unsaturated groups in the molecule in the presence of copper are polymerized and cured by copper. There is a great general need for technological developments such as methods of curing without hindrance.

In particular, copper is a metal with excellent electrical conductivity, so it is used in a wide range of applications that require electrical conductivity. When a substance is used in coexistence with or in contact with copper, the curing of the curable resin is hindered, so even though curable resins with ethylenically unsaturated groups in their molecules have various excellent properties, Since it is difficult to use due to large curing interference, its use is severely restricted.

In order to utilize the excellent conductivity of copper as described above, the present inventors have developed a conductive composition in which copper powder is added as a conductivity imparting agent to a curable resin having an ethylenically unsaturated group in the molecule. When considering various curing methods, we found that especially when the added copper powder is exposed to high temperatures in the air, the surface of the added copper powder is susceptible to oxidation, and that the oxides produced by this oxidation are Since it becomes an insulator, it is considered unfavorable for conductivity.
We focused on a method of curing a curable resin having an ethylenically unsaturated group in the molecule at a low temperature such as room temperature. In a low temperature curing method for curable resins having unsaturated groups,
Curing interference caused by copper was significant, and no method that was practically satisfactory could be found.

Therefore, as a result of intensive research into methods of curing various catalysts at low temperatures without curing interference caused by copper, we have found that curable substances such as curable resins having ethylenically unsaturated groups in their molecules are cured at 130°C, for example. By adding a dialkyl peroxide type organic peroxide to the conductive composition, which does not act as a curing catalyst unless heated at a high temperature such as ~160°C, curing of copper is eliminated and the curing can be performed quickly at a low temperature such as room temperature. Furthermore, according to this method, there is no need to worry about changes in conductivity caused by various additives to prevent oxidation of copper due to high temperatures and interference with curing due to copper, and in fact, it has excellent conductivity. I got it.

The present inventors have further described the application of the present invention in which a conductive composition containing such copper powder and having ethylenically unsaturated groups in the molecule is cured with a dialkyl peroxide type organic peroxide at a low temperature. As a result of further investigation, we found that not only the case of curable resin that exhibits conductivity, but also general cases, such as copper powder that contains ethylenically unsaturated groups in the molecule simply for decoration! It has been found that it can be used when coexisting with a chemical substance, or when it is desired to harden a hardening substance having a saturated group at a low temperature.
This invention has been achieved.

That is, the present invention provides a method for curing a curable substance having an ethylenically unsaturated group in the molecule by a curing reaction of the curable substance in coexistence with copper or in contact with copper, as a curing catalyst for the upper curable substance. The curing of the curable substance is carried out in the presence of the organic peroxide at a temperature so low that dialkyl peroxide type organic peroxide alone does not contribute to the curing reaction of the curable substance. This is a method for curing a curable substance having an ethylenically unsaturated group in its molecule.

The curable substance having an ethylenically unsaturated group in the molecule used in the present invention refers to a monomer having an ethylenic double bond in the molecule, a monomer having an ethylenic double bond in the molecule, and a monomer having an ethylenic double bond in the molecule. It means a curable composition comprising a polymer having a double bond and a curable polymer having an ethylenic double bond in the molecule.

The monomers having an ethylenic double bond in the molecule include, for example, acrylic acid, butyl acrylate, 2-hydroxyethyl acrylate mono(2-hydroxyethyl acrylate) acid phosphate, ethoxyethyl acrylate, dimethylaminoethyl acrylate, Acrylic compounds such as methacrylic acid, methyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, mono(2-hydroxyethyl methacrylate) acid phosphate, sulfopropyl methacrylate, methylol acrylamide, styrene, vinyltoluene, divinyl These include vinyl aromatic compounds such as benzene and 2-vinylpyridine, as well as itaconic acid esters such as diethyl itaconate and monomethyl itaconate, and allyl compounds such as diallyl phthalate and triallyl isocyanate. Examples of polymers having ethylenic double bonds include those made from unsaturated carboxylic acids and polyols such as polypropylene maleate, polydiethylene fumarate, polybutylene itaconate, polypropylene glycol diacrylate, etc. Polyester, a polymer obtained by reacting a monostyrene acrylate-butyl acrylate copolymer with glycidyl methacrylate, a polymer obtained by reacting a vinyl chloride monovinyl acetate monomaleic anhydride copolymer with hydroxypropyl acrylate, and 1. 2-A vinyl polymer having an ethylenic double bond in its side chain, such as polybutadiene; an epoxy resin into which an ethylenic double bond is introduced, such as that obtained by reacting a bisphenol type epoxy resin with acrylic acid or maleic anhydride; Typical examples include polyurethanes having ethylenic double bonds, such as those obtained by reacting polypropylene glycol with toluene diisocyanate and hydroxypropyl acrylate.

Copper referred to in the present invention is, for example, commercially available metallic copper or an alloy containing copper as one component, and these may be spherical, dendritic,
It is used in shapes such as foil, plate, and line. The dialkyl peroxide type organic peroxide used in the present invention is
It means an organic peroxide with a structure in which hydrocarbon groups are connected by a -0-0 bond, and a temperature of 100°C or higher for a spontaneous thermal decomposition half-life of 10 hours. Examples of dialkyl peroxide type polymerization catalysts include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, A,a″ bis(
t-butylperoxy)P-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-
Products such as butylperoxy)hexyne are commercially available, and other organic products such as peroxyketal type, diaralkyl peroxide type, bridged peroxide type (transannual peroxide), and polyalkylidene peroxide type are commercially available. Includes peroxides that satisfy the above-mentioned spontaneous thermal decomposition half-life conditions.

The low temperature referred to in the present invention varies depending on the curability, type of substance, type of dialkyl peroxide type organic catalyst, and combination thereof used in the present invention, but is generally 100°C or less, preferably about 10 to 50°C.

In the present invention, the ratio of the curable substance having an ethylenically unsaturated group in the molecule and copper greatly depends on whether the curable substance and copper coexist or are in contact with each other. In the case of a composition exhibiting properties, it is preferable that the composition contains, for example, 40 to 90% by weight of fine commercially available copper powder. The proportion of the dialkyl peroxide type 5 organic peroxide used in the present invention is usually 0.1 to 5% by weight based on the curable substance having an ethylenically unsaturated group in the molecule, and is used to achieve the desired hardening. It may be selected appropriately depending on the speed. In carrying out the present invention, in order to cure the curable substance at the low temperature used, a polymerization catalyst or a photosensitizer that cures at that temperature may be coexisting in advance. The curing method of the present invention may be carried out under any atmosphere, such as an inert gas such as nitrogen or carbon dioxide, or air. There are no particular restrictions. When carrying out the present invention, if the surface of copper coexisting with or in contact with a curable substance having an ethylenically unsaturated group in its molecules is covered with an oxide film, for example, the surface of the copper should be treated to remove the oxide film in advance. In order to accelerate the curing of the curable substance, it is preferable to carry out the curing method of the present invention after an acid group is present in the curable substance having an ethylenically unsaturated group in the molecule.

The curing method according to the present invention is particularly applicable to conductive curable compositions containing copper powder as an additive to a curable substance having an ethylenically unsaturated group in the molecule. When applied to applications such as molded products, it is a useful means for each of these applications, and is also a useful method when polymerizing and curing the above-mentioned curable composition on a copper plate, for example. Therefore, the industrial value of the present invention is extremely high.

Examples are described below, and the parts and percentages described below are
means parts by weight and weight %, respectively, and the concentrations described in the examples represent the proportion of the component in the total components in %.

Example 1 Maleic anhydride (4 mol), phthalic anhydride (6 mol),
A liquid resin (hereinafter abbreviated as A resin) consisting of 76% unsaturated polyester synthesized from propylene glycol (10 mol) and 24% styrene and dicumyl peroxide (4) as a catalyst (manufactured by Hon Yushi Co., Ltd., trade name: Percumyl D) A mixed solution prepared by adding A resin at a ratio of 1% to resin A was applied to a thickness of approximately 100μ on two glass plates whose surfaces had been cleaned, and the areas to which each of these coatings was applied were A polyester film for mold release was placed on each surface of the glass plate so as to be in contact with the glass plate, and one of the two glass plates thus obtained was placed in a dryer at 30°C and the other at 130°C. After storing each coat for 15 hours and allowing it to cool to room temperature, the polyester film for mold release was peeled off to determine the surface hardness of each coated product. Since the stored product had not undergone any polymerization and curing, the coating material adhered to the release polyester film in an uncured state, making it impossible to obtain a smooth coating surface (see Experiment No. 1). ).

On the other hand, in the case of a product stored in an atmosphere of 130°C, polymerization and curing have proceeded, and the polyester film for mold release is easily peeled off, and its surface is smooth, and the surface hardness of the cured product in this case is JIS The pencil hardness was H to 2H according to the method shown by -5400 (see Experiment No. 2).

On the other hand, a composition in which dicumyl peroxide was added as a catalyst at a ratio of 1% to resin A to a composition consisting of 60 parts of resin A and 40 parts of copper powder (flake-like, 325 mesh) was used to clean the surface. Two glass plates were prepared in the same manner as in Experiment Nos. 1 and 2 above, except that the coating was applied to two glass plates each having a thickness of about 500μ, and one of them was coated at 30°C. , and another one in each dryer at 130°C for 15 hours, and then allowed to cool to room temperature. After peeling off the release polyester film, the surface hardness of each coated product was measured. When I tried to determine this, I found that when the product was stored in an atmosphere at 130°C, the coating material adhered to the release polyester film in an uncured state because the polymerization and curing had not progressed, resulting in a smooth coating surface. (See experiment number 3).

On the other hand, for those stored in an atmosphere of 30°C, polymerization and curing have progressed, and the above polyester film for mold release can be easily peeled off, and its surface is smooth. The hardness was F-H according to the pencil hardness display method according to JIS-5400 (see experiment number 4).
.

The above experimental results are summarized in Table 1 below. Example 2 A conductive composition (hereinafter abbreviated as composition A) prepared by blending 60 parts of the copper powder used in Example 1 with 10 parts of mono(2-hydroxyethyl methacrylate) acid phosphate was tested with 7 widths. 30 parts of A resin used in Example 1. Each of the dialkyl peroxide type organic peroxides listed in Table 2 Experiment Nos. 1 to 3 was added as a catalyst to a composition mixed in such a proportion as to be 1% of resin A. Two pieces of glass with each surface cleaned. Each coating was applied to a thickness of about 500 μm on a substrate, and a release polyester film was placed on the surface of the coated portion of each coating so as to come into contact with the surface of each coating. Place each glass plate one by one in a drying oven at 130°C.
After being stored for 5 hours and then left to cool to room temperature, the polyester film for mold release was peeled off and the surface hardness of each coated product was determined, but it was found that polymerization and curing had progressed in each coated product. As a result, each of these coatings adhered to the polyester film in an uncured state, and it was not possible to obtain a smooth coating surface in any of them (see Experiment Nos. 1 to 3).

On the other hand, each of the remaining coated glass plates was stored for 15 hours in a dryer at 15°C, and then allowed to cool to room temperature, and then the polyester film was peeled off. Because polymerization and curing had progressed, they could be easily peeled off, and the surfaces of all of them were smooth, and the surface hardness of each of these cured products was F4H on the pencil hardness scale according to the method shown in JIS-5400. Experiment number 4-6
reference).

The above experimental results are summarized in Table 2 below, and a test was conducted from the measurement terminal of a tester (trade name: Multitester K-30D, manufactured by Sanwa Denki Keiki Co., Ltd.) on the surface of each cured product obtained in Experiment Nos. 4 to 6. Table 2 also shows the resistance values measured by contacting the pins with a spacing of 1 cm. Example 3 70 parts of A composition used in Example 2, experiment number 1 in Table 3
To each composition in which each of the polymerizable curable resins described in 4 to 4 was mixed at a ratio of 3, dicumyl peroxide was added as a catalyst in an amount of 1.5% to each polymerizable curable resin.
The added material was applied in the same manner as in Example 2 using two glass plates each with a cleaned surface.
For each polymerizable curable resin, one glass plate was stored in a dryer at 120°C for 15 hours, and then allowed to cool to room temperature. After that, an attempt was made to peel off the mold release polyester film covering the surface of each coated product. When I tried each of the above coatings, the polymerization and curing had not progressed, so the coatings adhered to the release polyester film in an uncured state, making it impossible to obtain a smooth coating surface. Ta(
(See experiment numbers 1 to 4).

On the other hand, apply 30% to each of the remaining glass plates coated above.
After being stored in a dryer at ℃ for 15 hours and then allowed to cool to room temperature, the release polyester film that covered the surface of each coated product was peeled off. All coated products were easily cured because polymerization had progressed. In both cases, the surface is smooth, and the surface hardness of each of these cured products is JIS-5.
The pencil hardness was expressed by the method shown in 400 and had the values shown in Experiment Nos. 5 to 8 in Table 3 (see Experiment Nos. 5 to 8).

The above experimental results are summarized in Table 3 below, and Example 2 was performed on the surface of each cured product obtained in Experiment Nos. 5 to 8.
The resistance values measured using the same test method as in the case of 2 are also listed in Table 3.

Claims (1)

[Claims] 1 When a curable substance having an ethylenically unsaturated group in its molecule is cured by the curing reaction of the curable substance in coexistence with copper or in contact with copper, a dialkyl peroxide type organic compound is used as a curing catalyst for the curable substance. In the molecule, the above-mentioned curing of the curable substance is carried out in the presence of the organic peroxide at such a low temperature that peroxide alone does not contribute to the curing reaction of the curable substance. A method for curing a curable substance having an ethylenically unsaturated group.