JP3019401B2 - Microencapsulated curing agent, method for producing the same, unsaturated polyester resin composition containing the same, curing method and stabilizing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an unsaturated polyester resin curing agent.
Specifically, it is stably present in the unsaturated polyester resin,
At the time of resin curing, a microencapsulated curing agent containing a curing agent as a core substance that enables rapid curing, a method for producing the curing agent, an unsaturated polyester resin composition containing the curing agent, an unsaturated resin The present invention relates to a method for curing and stabilizing a polyester resin.

<Conventional technology> Conventionally, unsaturated polyester resin is compounded with glass fiber, inorganic filler, thickener, stabilizer, and release agent, and then added with a curing agent and heat-cured or, if necessary, with a curing accelerator. It cures at room temperature and is widely used for molding FRP.

Organic peroxides are generally used as a curing agent for unsaturated polyester resins, but a resin solution containing a curing agent has a pot life and, for example, gels, so that the resin solution can withstand long-term storage. I can't. For this reason, at present, two of the resin and the curing agent or the three of the curing accelerator are mixed and used immediately before use. On the other hand, it is desirable that the curing temperature is low in practical use. However, a low curing temperature results in poor stability of the curing agent. Various studies have been conducted to satisfy these conflicting conditions. As a result, it has been confirmed that the above-mentioned disadvantages can be eliminated by microencapsulating the curing agent. In recent years, microencapsulated curing agents have been actively developed. For example, JP-A-48-7086 discloses that a liquid or solid organic peroxide colored with a dye or a pigment is formed of a natural or synthetic crystalline or amorphous polymer substance such as gelatin or polystyrene. Consisting of a coated hardener capsule and an unsaturated polyester resin,
Curable compositions that are stable at room temperature and have potential reactivity are disclosed. However, colored hardener capsules cannot be used for transparent moldings. JP-A-57-12
No. 017 discloses a temperature of 74 to 1 for obtaining a half-life of 10 hours.
Unsaturated polyester resin suitable for sheet molding compound (SMC) that can be compression molded at low temperature and low pressure with microcapsules of liquid or solid organic peroxide at 58 ° C and a curing accelerator such as cobalt naphthenate, JP-T-59-502018 contains liquid or solid hardening agent microcapsules and is characterized in that its action is isolated in the compounding molding material until released under predetermined process conditions. A method for producing a reinforced polyester resin product is disclosed.

<Problems to be Solved by the Invention> However, in a microencapsulated organic peroxide liquid at room temperature, the core substance gradually dissolves the membrane substance, and has its own stability and unsaturated polyester blended with it. The stability of the resin composition is impaired. Further, when solid organic peroxide is microencapsulated as it is, it does not solve the above-mentioned problems of the known curing agent, and furthermore, it is difficult to completely cover with a film material due to its shape and surface condition. Has disadvantages.

In this way, simply microencapsulating a liquid or solid organic peroxide cannot always achieve its purpose. Curing of an unsaturated polyester resin is generally achieved by using a very small amount of a curing agent, and when the curing agent is microencapsulated, any non-microencapsulated resin is contained in the resin. If curing starts, storage stability will be significantly impaired. Further, when the hardening agent is coated with a strong film, there is a possibility that hardening is delayed or uneven hardening occurs during hardening. As described above, it is not easy to obtain an unsaturated polyester resin composition which quickly cures upon curing and has good storage stability only by microencapsulating the curing agent.

Further, in an SMC obtained by mixing a glass fiber, a filler, and the like with an unsaturated polyester resin, microcapsules are broken by friction of a reinforcing agent, and it is difficult to maintain the above performance. Further, it is difficult to completely destroy the capsule film and to effectively disperse the curing agent in the resin only by pressurizing or heating.

<Means for Solving the Problems> The present inventors have found that when mixed with an unsaturated polyester resin, the organic stability of the resin enables quick and uniform curing without impairing the storage stability of the resin. As a result of research for the purpose of developing a curing agent for unsaturated polyester resin in which peroxide is microencapsulated, a specific organic peroxide can be achieved by a microencapsulated curing agent obtained by using a specific means. After confirming this, the present invention was completed.

That is, the present invention is a solid material at normal temperature, a core material that is an organic peroxide for curing an unsaturated polyester resin having a difference between the melting point and the thermal decomposition temperature of at least 5 ° C, the melting point of the organic peroxide or more, Melts below the thermal decomposition temperature, cools and solidifies
~ 200μm fine particles, the solidified fine particles, unsaturated polyester resin, the core material is not reactive, solid at normal temperature, the film material having the property of melting at the unsaturated polyester resin curing temperature by A microencapsulated curing agent for an unsaturated polyester resin, comprising the core material obtained by covering, and the film material covering the core material;
A core material which is a solid at normal temperature and is an organic peroxide for curing an unsaturated polyester resin having a difference between a melting point and a thermal decomposition temperature of at least 5 ° C. After being melted and cooled and solidified to form fine particles of 1 to 200 μm, the solidified fine particles are not reactive with the unsaturated polyester resin and the core substance, and are solid at ordinary temperature.
A method for producing a microencapsulated curing agent for unsaturated polyester resin, characterized by being covered with a film material having a property of melting at the unsaturated polyester resin curing temperature, comprising: An unsaturated polyester resin composition,
The present invention relates to a method for curing an unsaturated polyester resin using the curing agent of the present invention, and a method for stabilizing an unsaturated polyester resin in which the curing agent of the present invention is added to an unsaturated polyester resin.

An organic peroxide which is solid at room temperature (20 ° C.) is used as the core substance of the present invention. For example, as peroxydicarbonates, dimyristyl peroxydicarbonate and the like, and as dialkyl peroxides, dicumyl peroxide, α, α'-bis (t-butylperoxy-m-
Isopropyl) benzene, α, α'-bis (t-butylperoxy-p-isopropyl) benzene, ketone peroxides such as cyclohexanone peroxide, and peroxyesters such as di-t-butylperoxyisophthalate, peroxy Examples of the ketals include 1,3-diphenyl 2,2-bis (t-butylperoxy) propane, 1-phenyl 3,3-bis (t-butylperoxy) butane, 1-benzoyl 2-methyl-2,2-bis (T-butylperoxy) ethane, 1,1-bis (t-
Examples of butylperoxy) cyclododecanes and diacyl peroxides include decanoyl peroxide, methatoryl peroxide, lauroyl peroxide, and the like, provided that the above-mentioned conditions are satisfied. May also be used as a mixture.

Curing of the unsaturated polyester resin is started by heating, and is classified into a medium temperature curing at 50 to 100 ° C and a high temperature curing at 100 ° C or higher. In the former, peroxydicarbonates, diacyl peroxides, ketone peroxides, peroxyketals, hydroperoxides or peroxyesters are preferred and used alone or in combination with a curing accelerator. The latter is preferably a peroxyketal, a peroxyester or a dialkyl peroxide.

Table 1 shows melting points and thermal decomposition temperatures of typical organic peroxides. The melting point of the organic peroxide can be lowered by mixing other substances, and can be used within a range that does not hinder the present invention. But,
In this case, since the range of the melting point is widened, it is preferable to use the resin alone if faster curing is expected. The thermal decomposition temperature is determined by the heating test method described in the journal Safety Engineering (Hiroshi Kitagawa et al., Safety Engineering, Vol. 4, No. 2, p. 133-134, 136, 1965).
Year), and specifically means a temperature at which decomposition of the organic peroxide starts to occur rapidly when the temperature of the organic peroxide is increased at a constant rate.

Next, the method for producing the microencapsulated curing agent of the present invention will be described. That is, an organic peroxide that is solid at the above-mentioned ordinary temperature and has a difference between the melting point and the thermal decomposition temperature of at least 5 ° C. is melted in a range from the melting point to the thermal decomposition temperature,
Microcapsules are manufactured using this melt. For microencapsulation, a conventionally known technique can be used. That is, a coacervation method by phase separation from an aqueous solution,
There are an interfacial polymerization method, an in-situ polymerization method, and the like, and details thereof are described in “Latest Microencapsulation Technology” by Sogo Gijutsu Center. Microencapsulation is usually carried out from a dispersion or solution having colloidal properties.
An insoluble impervious substance is attached to an organic peroxide dispersed as a particle phase in a liquid to form a partition wall film, or an insoluble impervious partition wall film at the interface between the organic peroxide and the medium. This is done by making As a membrane substance,
It is necessary that it does not react with the organic peroxide and does not dissolve at the temperature at which the encapsulation is performed. Since this depends on the type of the organic peroxide, it must be selected in each case. In addition, in the case of using a resin mixed with a resin, it is necessary to appropriately select a film material depending on the type of the resin and the organic peroxide used so that a substance outside the film does not penetrate into the film.

As the membrane substance, for example, gelatin, casein, gum arabic, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, methyl vinyl ether, maleic anhydride copolymer, etc. can be used as hydrophilic colloid substances in the coacervation method, and formaldehyde, glutar It is obtained by curing with an aldehyde or the like. In the interfacial polymerization method and the in-situ polymerization method, isocyanate and water, isocyanate and polyamine, isocyanate and polyol, isothiocyanate and water, isothiocyanate and polyol, epoxy resin compound, urea formalin Resin or the like can be used.

The organic peroxide dissolved in the microencapsulation is formed into fine particles of 1 to 200 μm and then solidified by cooling.

By the method described above, the above-mentioned microencapsulated curing agent for unsaturated polyester resin of the present invention is obtained.

The particle diameter and the thickness of the film of the microcapsules are appropriately determined depending on the purpose.

 Incidentally, a material having a diameter of 1 to 200 μm is practically preferable.

The unsaturated polyester resin used in the present invention includes: (a) maleic anhydride as an unsaturated dibasic acid, maleic acid, fumaric acid, mesaconic acid, tetraconic acid, itaconic acid, chlorinated maleic acid, and anhydride as a saturated dibasic acid; Phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, halogenated phthalic anhydride, adipic acid, succinic acid,
Sebacic acid and polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, hexylene glycol, hydrogenated bisphenol A, 2,2-di (4-hydroxypropoxyphenyl) propane, 2 An alkyd resin obtained by subjecting 1,2-di (4-hydroxyethoxyphenyl) propane, ethylene oxide, propylene oxide and the like to dehydration condensation at a specific ratio at 170 to 200 ° C. in a nitrogen stream, and (b) styrene, O-chloroform. It is a mixture of crosslinkable monomers such as styrene, vinyl toluene, methyl methacrylate, diallyl phthalate, triallyl isocyanate.

The hardening agent obtained by microencapsulation used in the present invention can be used alone or in combination with a hardening accelerator forming a redox system. Examples of the hardening accelerator include, for example, cobalt naphthenate Metal salts of higher fatty acids, thioureas such as benzoylthiourea and ethylenethiourea, ethylenediamine, L-ascorbic acid, sodium p-toluenesulfinate and the like.
Since the accelerating effect differs depending on the combination with the curing agent, it is necessary to appropriately select it.

In the unsaturated polyester resin curing agent comprising the microencapsulated curing agent and the redox-based curing accelerator of the present invention, the ratio of the pure organic peroxide and the curing accelerator in the microencapsulated curing agent is as follows: The ratio can be selected from 90/10 to 90/90 (weight ratio) depending on the desired curing speed.

In the unsaturated polyester resin composition comprising the unsaturated polyester resin and the microencapsulated curing agent of the present invention, the pure content of the organic peroxide in the unsaturated polyester resin curing agent is 0.1 to 100 parts by weight of the resin. It is 5 parts by weight, preferably 0.5 to 3 parts by weight. When the amount is less than 0.1 to part by weight, the effect as a curing agent is insufficient, and even when the amount exceeds 5 parts by weight, the effect of the curing agent is equivalent to that of 5 parts by weight, which is not economically preferable.

In the unsaturated polyester resin composition of the present invention, reinforcing agents such as glass fibers such as roving cloth, chopped strands, chopped strand mats, or carbon fibers, calcium carbonate, clay, and hydroxide for the purpose of improving the strength of molded articles. A filler such as aluminum can be compounded, and the compounding amount is 10 to 90% by weight of the total amount. If the amount is too small or too large, the strength of the molded article is unpreferably reduced. Further, depending on the purpose, a thickener such as an oxide or hydroxide of an alkaline earth metal such as magnesium oxide, a low shrinkage agent such as a thermoplastic resin, a copolymer thereof, or a block-braft copolymer, stearin A release agent such as zinc acid or a polymerization inhibitor such as benzoquinone can be used.

The molding temperature of the unsaturated polyester resin composition of the present invention can be appropriately selected depending on the molding method. For example, molding of resin concrete, continuous molding of corrugated sheet or flat plate, filament winding molding or resin injection molding is performed at 50 to 100 ° C. (formed by curing reaction), and peroxydicarbonates, diacyl peroxides, ketone peroxides. A hardening agent obtained by microencapsulating an organic peroxide such as peroxyketals, hydroperoxides or peroxyesters is used alone or in combination with a hardening accelerator forming a redox system. Also, SMC, bulk molding compound (BMC) or matched die molding is performed at 100 ° C. or higher, and a curing agent in which peroxyketals, peroxyesters or dialkyl peroxides are microencapsulated is used.

<Effect of the Invention> As described above, the microencapsulated curing agent of the present invention is obtained by using a specific means for a specific organic peroxide, and thus has several excellent features. I have.

First, the microencapsulated hardener of the present invention has a core material of a solid organic peroxide, around which a membrane material forms an insoluble and impermeable thin partition wall. In addition, the curing agent comprising a microencapsulated curing agent and a curing accelerator is far superior in storage stability to a curing agent comprising the same non-microencapsulated organic peroxide and a curing accelerator. The unsaturated polyester resin composition of the present invention obtained by mixing a microencapsulated curing agent or a curing agent comprising a microencapsulated curing agent and a curing accelerator with an unsaturated polyester resin is not microencapsulated. It is stabilized and has a much longer pot life or shelf life than a resin composition obtained by mixing the same organic peroxide or a curing agent comprising the same with a curing accelerator.

Further, when the state of the solid organic peroxide physically changes from a solid to a liquid at the melting point, a sudden increase in volume is caused. That is, the microencapsulated curing agent of the present invention, when the unsaturated polyester resin is cured, the organic peroxide as the core substance is liquefied by heating, and the volume is increased to destroy the film substance and rapidly cure. Is made possible. Further, the destruction is promoted by pressure, mechanical friction and the like.

As described above, the microencapsulated curing agent of the present invention and the unsaturated polyester resin composition containing the same have excellent storage stability, a long pot life and shelf life, and a curing reaction with a sharp rise upon curing. It is to be.

<Examples> Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the examples, parts represent parts by weight.

Example 1 A mixture of 316 g of a 5.06% gelatin aqueous solution and 316 g of a 5.06% gum arabic aqueous solution was mixed, and the temperature in the system was adjusted to 45 ° C. with stirring.
Dimyristyl peroxydicarbonate is added to this aqueous solution.
100 g were added. Further, 400 g of distilled water at 60 ° C. was added to raise the temperature in the system to 50 ° C. to melt dimyristyl peroxydicarbonate. After melting and stirring for about 5 minutes, a 50% aqueous acetic acid solution was added to adjust the pH to 4.4. Thereafter, the temperature of the solution was lowered to 20 ° C. over about 20 minutes. And 37%
After adding 6 ml of formaldehyde aqueous solution and stirring for 4 minutes, 1
Raise the pH to 9.0 using a 0% aqueous sodium hydroxide solution 15
For a minute.

By the above treatment, a dimyristyl peroxycarbonate dispersion having an average particle size of 30 μm was obtained.

Washed twice with 1000 cc of hot water at 33 ° C. Unencapsulated dimyristyl peroxydicarbonate was washed with a mixed solution of n-hexane and ethanol (mixing ratio 50:50). Thereafter, the resultant was dried to obtain 70 g of a hardener having an average particle diameter of 35 μm microencapsulated with a gelatin film containing 85% by weight of pure dimyristyl peroxydicarbonate.

Example 2 Example 1 was repeated except that the temperature in the system was set to 65 ° C., cyclohexanone peroxide was used as the organic peroxide, and the temperature in the system was set to 75 ° C. using distilled water at 80 ° C., and the system was washed with n-hexane. 85% of cyclohexanone peroxide
75 g of a microencapsulated curing agent containing% by weight were obtained.

Example 3 Three parts of a curing agent obtained by microencapsulating the dimyristyl peroxydicarbonate obtained in Example 1 was mixed with 100 parts of an ortho-based medium-reactive unsaturated polyester resin to obtain an unsaturated polyester resin composition. Next, this composition was laminated on two # 450 glass mats, wrapped with a polyester film, and the time until gelation occurred in a 10 ° C. incubator was measured, and the time was defined as the pot life.
The results are shown in Table 2.

Example 4 100 parts of the curing agent obtained by microencapsulating the cyclohexanone peroxide obtained in Example 2 and 20 parts of cobalt naphthenate were mixed to obtain a curing agent. Next, the above-mentioned curing agent 3 was added to 100 parts of an ortho-type middle reactive unsaturated polyester resin.
And the pot life was measured in the same manner as in Example 3. Second result
It is shown in the table.

Example 5 An unsaturated polyester resin composition was obtained by mixing 1.2 parts of the microencapsulated curing agent obtained in Example 1 with 100 parts of an ortho-based reactive unsaturated polyester resin. Next, this composition was laminated on three glass mats of # 450, cured by a convection thermostat at 60 ° C. by inserting a thermocouple, and measured for gel time (GT), curing time (CT), and hardness. The results are shown in Table 3.

Comparative Example 1 The pot life was measured according to Example 3 except that 2.5 parts of unmicroencapsulated dimyristyl peroxydicarbonate was used as a curing agent. Second result
It is shown in the table.

Comparative Example 2 Example 4 except that 2.1 parts of non-microencapsulated cyclohexanone peroxide were used as a curing agent.
The pot life was measured according to. The results are shown in Table 2.

Comparative Example 3 40 g of microcapsules containing 50% by weight of a pure methyl ethyl ketone peroxide were obtained in the same manner as in Example 1 except that methyl ethyl ketone peroxide (Permec N manufactured by NOF Corporation) was used as the organic peroxide and washed with ethanol. Since the core substance is a liquid organic peroxide, the membrane of the microcapsules was easily broken in the washing step, and the yield was considerably deteriorated. Next, the pot life was measured according to the example except that 5 parts of microencapsulated methyl ethyl ketone peroxide was used as a curing agent. The results are shown in Table 2.

Comparative Example 4 GT, CT and hardness were measured in the same manner as in Example 5 except that 1 part of unmicroencapsulated dimyristyl peroxycarbonate was used as a curing agent. The results are shown in Table 3.

Comparative Example 5 Cyclohexane on peroxide was used as an organic peroxide, and cyclohexanone peroxide was microencapsulated without melting while maintaining the temperature in the system at 45 ° C.
Except for washing with n-hexane, according to Example 1, 60 g of a microencapsulated curing agent containing 63% by weight of a pure cyclohexanone peroxide was obtained. Since the core substance was microencapsulated in a solid state, the microcapsule membrane was easily broken in the washing step, and the yield was deteriorated. Next, an unsaturated polyester resin composition was obtained in the same manner as in Example 4 except that 4 parts of microencapsulated cyclohexanone peroxide was used as a curing agent, and the pot life was measured. The results are shown in Table 2.

From Table 2, the unsaturated polyester resin composition containing the curing agent alone or in combination with the curing accelerator forming the redox system of the present invention has a much longer pot life than the comparative example. , It was confirmed that it was stabilized.

Furthermore, in Table 3, the value of (CT-GT) / CT, which is a measure of the sharpness of the rise of curing, is smaller than that of Comparative Example, and thus it was confirmed that the curing agent of the present invention was quick-acting. .

Continuation of front page (56) References JP-A-4-48926 (JP, A) JP-A-48-7086 (JP, A) JP-A-57-12017 (JP, A) JP-A-1-189345 (JP, A) , A) JP-A-1-266845 (JP, A) JP-A-59-502018 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 283/00-283/01 C08F 4/00-4/82 C08F 290/00-290/14 C08F 299/00-299/08 B01J 13/02

Claims (6)

(57) [Claims] 1. A core material which is an organic peroxide for curing an unsaturated polyester resin which is solid at ordinary temperature and has a difference between a melting point and a thermal decomposition temperature of at least 5 ° C. Melts below the pyrolysis temperature, cools and solidifies to 1-200
μm fine particles, the solidified fine particles, the unsaturated polyester resin, not reactive with the core material, solid at room temperature, the film material having the property of melting at the unsaturated polyester resin curing temperature, A microencapsulated curing agent for an unsaturated polyester resin, comprising the core material obtained by covering and the film material covering the core material. 2. A core material which is an organic peroxide for curing an unsaturated polyester resin which is solid at normal temperature and has a difference between a melting point and a thermal decomposition temperature of at least 5 ° C. Melts below the pyrolysis temperature, cools and solidifies to 1-200
μm fine particles, the solidified fine particles, the unsaturated polyester resin, not reactive with the core material, solid at room temperature, the film material having the property of melting at the unsaturated polyester resin curing temperature, A method for producing a microencapsulated curing agent for unsaturated polyester resin, characterized by covering. 3. A hardening agent for unsaturated polyester resin comprising the hardening agent according to claim 1 and a redox hardening accelerator. 4. An unsaturated polyester resin according to claim 1 or 3,
An unsaturated polyester resin composition comprising the curing agent according to any one of the above. 5. A method for curing an unsaturated polyester resin, comprising curing the unsaturated polyester resin using the curing agent according to claim 1. 6. The unsaturated polyester resin according to claim 1 or 3,
A method for stabilizing an unsaturated polyester resin by adding the curing agent according to any one of the above.