JP2005264125A - Composition for preventing cure inhibition of radically curable resin with air - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing the cure inhibiting action on a resin surface with air which is a common defect of radically curable resins, and causing practical problems of the tackiness caused by the uncured or incompletely cured surface resin. <P>SOLUTION: Tung oil has been supposed to have no functional group reactive with isocyanate group from its structure, however, it has been unexpectedly found that the separation of oil and resin which is a defect in the use of a drying oil and the generation of tackiness by the air-induced inhibition of a radically curable resin can be prevented by the use of a radically curable resin and a compound having isocyanate group in combination with tung oil. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for preventing sticking due to uncured or incomplete curing of the surface resin, which is a drawback common to all radical curable resins, and is a phenomenon that inhibits the curing of the resin surface by air, and the phenomenon that appears as an actual problem It is.

Radical curable resins include unsaturated polyester resins and various oligomers having (meth) acryloyl groups, such as vinyl ester resins synthesized by reaction of epoxy resins with (meth) acrylic acid, in one molecule. Polyester having one or more (meth) acryloyl groups in one molecule (unsaturated) urethane-acrylic resin (hereinafter referred to as unsaturation) sharing one or more (meth) acryloyl groups and a urethane bond Examples thereof include so-called thermosetting acrylic resins that contain or are produced without or containing acrylate, methyl methacrylate containing polymer, and copolymerizable monomer.

However, these radically curable resins are produced industrially, regardless of their size, and their applications are remarkably large and are used in various fields.

Problems to be solved by the present invention

The problem to be solved by the present invention is that the resin surface layer is uncured due to the effect of inhibiting the curing of air, which occurs when these radical curable resins are cured at room temperature or a temperature close thereto, particularly in a thin film state, or It is the occurrence of stickiness due to incomplete curing, which is a large barrier in practical use, and is particularly remarkable for resin systems having a (meth) acryloyl group.

Conventionally, various methods have been proposed to correct these drawbacks, and some of them have been widely used. For example, the most common and effective method is the addition of a small amount of wax (around 0.1 phr).
That is, when the resin containing the wax is cured, the wax is extruded onto the surface of the resin and covers the surface of the cured resin, thereby preventing the air inhibiting action.
In addition, there is a method of incorporating an allyl ether structure and CH ₂ ═CH—CH ₂ —O— into the resin, which is effective for a polyester resin system using a styrene monomer.

However, although the addition of wax is still useful for the above-mentioned oligomers having a (meth) acryloyl group, it is ineffective unless used several times to about 10 times compared to a polyester resin containing styrene. In addition, the time required for drying is remarkably long, and some polyester resins have several tens of minutes to be tack-free, but the oligomer system containing a (meth) acryloyl group is 2 to 3 to become duck-free. It will take days, and in some cases it may not dry out completely.

It is also known that even if a polyester resin is used, the effect of the wax is greatly diminished when the glycol or aliphatic dicarboxylic acid containing an ether bond is used as the modified acid, and the polyester resin is not completely dried.

In addition, when allyl ether is incorporated into the resin structure, radically curable resins that do not contain styrene require a large amount of allyl ether compounds, which are problematic in terms of cost, physical properties, and sometimes the risk of gelation in the manufacturing process. And the dryness is not sufficient, it does not necessarily meet the object of the present invention.

Moreover, using dry oil together is also known as known knowledge.
However, linseed oil, which is mentioned as a representative of drying oil and is generally used as an air-drying alkyd paint, has no effect.

In addition, although tung oil and the like are effective in improving the drying property, they are poorly compatible with the radical curable resin and are easy to separate. As a result, they are separated and deposited on the surface of the cured resin, resulting in drying only of tung oil. Significant “chirimen” occurs.
Therefore, it is known to use dry oil, but it has not been carried out practically at all.

Means for solving the problem

In general, a radical curable resin is reacted with a polyvalent isocyanate compound to improve its physical properties.
For example, a polyester resin is allowed to react with several percent of diisocyanate with a hydroxyl group which is a terminal group of the polyester resin to mainly improve toughness. However, this method has nothing to do with improving air curability. That is, even when the isocyanate compound is used in combination, there is no power to prevent the air curing inhibiting action.

As a result of various studies in order to eliminate the air-inhibiting action of radical curable resins,
(1) Radical curable resin (2) Polyvalent isocyanate compound (3) By simultaneously using and reacting the three components of tung oil, it has been found that each of the conventional problems can be solved. Was able to be completed.

In other words, Tung Oil's published chemical structure is based on the combination of the above three components, although it is thought that the main component is glycerides of eleostayric acid and there is no reaction point with the isocyanate compound. Separation from the system is sufficiently prevented, and “chirimen rice cake”, which is a fatal defect that occurs when using paulownia oil, disappears completely, and as a result, the air hardening inhibition action of the system is eliminated.

The use of dry oils other than tung oil is difficult to achieve good results within a practical time by itself, but the purpose may be achieved in combination with tung oil.
In particular, dehydrated castor oil and oil deer oil meet this purpose.

The invention's effect

As described above, the stickiness of the surface portion due to the air curing inhibition of the radical curable resin is a big barrier when putting the resin into practical use, but in order to prevent this,
Polyvalent isocyanate compound
By using paulownia oil in combination, the effect of inhibiting the curing of air can be completely prevented.
At this time, as described above, the effect cannot be obtained by adding only the polyvalent isocyanate compound or only the tung oil alone.

The most effective method of the present invention is a so-called curable acrylate resin having one or more (meth) acryloyl groups in one molecule that is strongly affected by air curing inhibition, and also has utility value. large.
As the types thereof, vinyl ester resins obtained by reacting (i) epoxy resins with (meth) acrylic acid.
(Ii) A (unsaturated) urethane-acrylate resin sharing a (meth) acryloyl group and a urethane bond in the same molecule.
(Iii) Polyester having a (meth) acryloyl group. So-called polyester acrylate.
(Iv) Radical curable so-called thermosetting acrylic resins containing a polymer soluble in methyl methacrylate (v) unsaturated polyester resins and the like.

The polyvalent isocyanate compound is 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight per 100 parts by weight of these resins.
If the amount is 0.1 parts by weight or less, the effect of addition is poor, and if it is 20 parts by weight or more, the viscosity increases and handling becomes difficult, or gelation occurs.

There are no particular restrictions on the polyvalent isocyanates that can be used in the present invention, but examples include the following types.
2,4 tolylene diisocyanate, 2,4 and 2,6 mixed tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, Xylylene diisocyanate, hydrogenated bisphenol diisocyanate, and trimers of these isocyanates

In addition to the above components, the amount of drying oil, typically tung oil, used to prevent air-inhibiting action is based on 100 parts by weight of the total amount of radical curable resin and polyvalent isocyanate compound. 0.1 parts by weight or more and 20 parts by weight or less, more preferably 1 part by weight or more and 10 parts by weight or less. At 0.1 parts by weight or less, almost no effect is observed even when a drying oil is added, and when 20 parts by weight or more is added, the effect of improving the drying property is not increased. It is not desirable because the work is strengthened.

In the present invention, if necessary, waxes can be used in combination, and a system useful for preventing air inhibition can be obtained.

It goes without saying that the organic / inorganic reinforcing material, filler, colorant, mold release agent, various polymers, and the like can be used in combination as necessary when the composition of the present invention is put to practical use.
Next, in order to help understanding of the present invention, examples will be shown below.

Into a 1 liter separable flask equipped with a synthetic stirrer of a unsaturated polyester resin (A), a distillation condenser, a thermometer and a gas introduction tube, 160 g of diethylene glycol, 53 g of propylene glycol, 98 g of maleic anhydride, phthalic anhydride 148 g of acid was charged, esterified at 190 to 205 ° C. in a nitrogen stream, and stopped at an acid value of 29.9. The temperature was lowered to 160 ° C., 0.08 g of hydroquinone was added, and 230 g of styrene was further added at a temperature of 150 ° C. to synthesize an unsaturated polyester resin (A) as a uniform solution. It was pale yellow and had a viscosity of about 5 poise.

Production of air-curable composition (B) In a 250 cc polyethylene bottle, 95 parts by weight of unsaturated polyester resin (A), 5 parts by weight of 2,4-tolylene diisocyanate, and 4 parts by weight of tung oil are weighed. After sealing tightly and shaking and stirring to make a uniform solution, it was left in a thermostat at 70 to 75 ° C. for 5 hours. It was confirmed by infrared analysis that the absorption of the isocyanate group disappeared. This was designated as composition (B).
To 50 parts by weight of the composition (B), 0.8 parts by weight of methyl ethyl ketone and 0.4 parts by weight of cobalt naphthenate (6% Co) are added, and 0.5 m / m thick on a bonderite steel plate with a bar coater. Painted to become.
The coating film gelled after about 1 hour and became almost tack-free after 6 hours.
The coating film hardness after standing overnight was B.

Comparative example

i) A curing agent was similarly blended only with the unsaturated polyester (A), and coating was performed. The gelation of the coating film was approximately 1 hour to 1 and a half hours, but the surface was not cured and dried, and the stickiness remained after 3 days.
ii) 5 parts by weight of tolylene diisocyanate was added to 95 parts by weight of the unsaturated polyester (A), heated to 70 to 75 ° C. for 5 hours, and then 5 parts by weight of styrene was added and coated and cured in the same manner. The result was almost the same as i), and the stickiness of the coating film remained after 3 days.

Preparation of unsaturated isocyanate (C) 174 g of 2,4-tolylene diisocyanate and 130 g of 2-hydroxyethyl methacrylate were charged into a 500 CC polyethylene bottle, and the internal temperature was It reached 56 ° C. Furthermore, when heated at 70 to 75 ° C. for 3 hours, as a result of infrared analysis, about 50 (%) of the isocyanate group is considered to have reacted, and the unsaturated isocyanate (C) is obtained in an almost colorless liquid state. It was.

Unsaturated urethane acrylate (D) synthesis stirrer, reflux condenser, thermometer, 1 liter separable flask equipped with gas inlet tube, 500 g of polytetramethylene glycol (Mn = 1980), unsaturated When 76 g of isocyanato (C), 0.03 g of parabenzoquinone and 1 g of tung oil were charged and reacted at 70 to 75 ° C. in dry air for 5 hours, infrared analysis revealed that the free isocyanate group had disappeared. It was.
Unsaturated urethane acrylate (D) was obtained with a pale yellowish brown color and a viscosity of about 210 poise.

90 parts by weight of unsaturated urethane acrylate (D), 10 parts by weight of trimethylolpropane trimethacrylate, 2 parts by weight of methyl ethyl ketone peroxide, 0.5 part by weight of cobalt naphthenate, 0.2 part of pyrrolidineacetoacetamide The parts by weight were uniformly mixed and cast into an aluminum cup having a diameter of 6 cm so as to have a depth of about 5 m / m. After standing overnight, a soft rubber-like cured resin having no surface stickiness was obtained.

Heat-curing acrylate (E) adjusted 1-liter separable flask equipped with a stirrer, reflux condenser, thermometer, gas introduction tube, methyl methacrylate monomer-270 g, 2-hydroxyethyl methacrylate 30 g, lauryl mercaptan 1 0.5 g and 3 g of azobisisobutyronitrile, polymerized in a nitrogen stream and gradually heated to 80-85 ° C. until the viscosity at room temperature reaches about 10 poises, and then 0.1 g of hydroquinone was added. When 12 g of paulownia oil, 3 g of dehydrated castor oil, 25 g of isocyanatoethyl methacrylate (trade name “MOI” manufactured by Showa Denko KK) are added, the gas is switched to air and reacted at 70 to 75 ° C. for 5 hours. As a result of the analysis, it was confirmed that the free isocyanate group had disappeared.
A light yellowish brown thermosetting acrylate (E) was obtained.

In 100 parts by weight of thermosetting acrylate (E), 0.5 parts by weight of paraffin having a melting point of 52 to 54 ° C. is heated and dissolved, and returned to room temperature. Further, 2 parts by weight of methyl ethyl ketone peroxide, cobalt naphthenate (6 % Co) and 1 part by weight of pyrrolidine acetoacetamide were added and the mixture was homogenized and coated on a bonderite steel sheet to a thickness of 0.5 to 0.6 m / m. The coating film had a paraffin layer formed on the surface after about 1 hour, became tack-free, completely cured after standing overnight, and showed a hardness of 2H.

Comparative example

(I) In the case of a coating film having the same composition except that paulownia oil and dehydrated castor oil were not used, the amount of wax was insufficient, so that the surface was not sticky after being left for 3 days.
(Ii) In the case of a coating film having the same composition except that isocyanatoethyl methacrylate is not used, a mixed oil of paulownia oil and dehydrated castor oil is separated and deposited, and large and small “crepe-like” wrinkles are formed on the surface. Occurred.

Synthetic stirrer of vinyl ester resin (F), reflux condenser, thermometer, gas introduction tube, 1 liter separable flask, 80 g of bisphenol type epoxy resin with epoxy equivalent of 186, 172 g of methacrylic acid, triphenylphosphine 1 .5g and hydroquinone 0.25g are charged. When the reaction was carried out at 130 to 135 ° C. for 3 hours under an air stream, the acid value became 5.9, so it was discontinued.
A light yellow, viscous syrup-like novinyl ester resin (F) was obtained at room temperature.

100 g of vinyl ester resin (F), 60 g of bisphenol A ethylene oxide adduct (each 1 mol of ethylene oxide addition type) monomethacrylate, 40 g of methyl methacrylate, 35 g of hexamethylene diisocyanate, 10 g of tung oil, dibutyltin Take 0.5 g of dilaurate in a 500 cc polyethylene bottle, homogenize by shaking well, and then warm to 70-75 ° C for 3 hours. As a result of infrared analysis, the free isocyanate group disappears. It was confirmed.
To 50 parts by weight of this mixed resin, 1 part by weight of methyl ethyl ketone peroxide, 0.5 part by weight of cobalt naphthenate (6% Co) and 0.2 part by weight of pyrrolidineacetoacetamide were uniformly added and mixed. The sample coated at a thickness of 0.5 to 0.6 m / m and allowed to stand at room temperature became tack-free after about 5 hours, and the hardness after standing overnight showed F to H.

Comparative example

In the case of the coating film having the same composition except that no tung oil was added, the stickiness remained even after standing for 3 days, and the hardness measurement was impossible.

Mixed polyester-oligoacrylate of about 70% by weight (dihydroxyethyl methacrylate) phthalate, about 25% (%) monohydroxyethyl methacrylate phthalate, about 5% (%) 2-hydroxyethyl methacrylate -A mixture of 200 parts by weight (abbreviated as polyester-acrylate), 20 parts by weight of diphenylmethane diisocyanate, and 10 parts by weight of paulownia oil was placed in a 500 cc polyethylene bottle and homogenized by shaking vigorously. , And heated in a constant temperature bath at 70 to 75 ° C. for 6 hours. A polyester acrylate (G) having a light reddish brown color and a viscosity of about 29 poise was obtained.
After 100 parts by weight of polyester acrylate (G) is uniformly mixed with 1.5 parts by weight of methyl ethyl ketone peroxide, 0.5 parts by weight of cobalt naphthenate (6% Co) and 0.2 parts by weight of pyrrolidineacetoacetamide, It was coated on a bonderite steel sheet at a thickness of 0.3 to 0.4 m / m, and immediately heated and cured in a thermostatic bath at 60 ° C.
Gelation occurred after 8 minutes and the surface was tack free approximately 20 minutes later. The hardness after standing overnight at room temperature was 2-3H. Further, the resin in the polyethylene bottle was uniform even after one week, and no separation of tung oil was observed.

Comparative example

(I) With the resin having the same composition except for tung oil, the surface was not sticky even when heated at 60 ° C. or even after 8 hours.
(Ii) In the resin of the same composition except for diphenylmethane diisocyanate, after standing overnight, tung oil and polyester acrylate (G) are separated in a polyethylene bottle, and tung oil is floating on the surface layer. It was recognized.

Claims (7)

When the radical curable resin is cured in the presence of air, (1) dical curable resin (2) polyvalent isocyanate (3) dry oil is used together in order to prevent the surface from inhibiting the curing of air. The composition which prevents the hardening inhibitory effect by the air of radical curable resin which consists of this. 2. The composition according to claim 1, wherein the radical curable resin is an unsaturated polyester resin. 2. The composition according to claim 1, wherein the radical curable resin is polyester acrylate. The composition according to claim 1, wherein the radical curable resin is a vinyl ester resin which is a reaction product resin of an epoxy resin and (meth) acrylic acid. 2. The composition according to claim 1, wherein the radical curable resin is a urethane-acrylate resin containing a (meth) acryloyl group and a urethane bond. 2. The composition according to claim 1, wherein the radical curable resin is used in combination with a methyl methacrylate monomer containing polymethyl methacrylate polymerized or other copolymerizable monomer. The composition according to claim 1, wherein the drying oil is tung oil.