JP5605827B2 - Unsaturated ester-based resin composition, unsaturated ester-based cured product, and production methods thereof - Google Patents

Description

  The present invention relates to an unsaturated ester resin composition that can give an unsaturated ester cured product having a good surface condition and excellent toughness.

  Unsaturated ester resins are widely used in various applications such as coating compositions and molding compositions containing reinforcing materials such as glass fibers. On the other hand, the unsaturated ester resin after curing (hereinafter referred to as “unsaturated ester cured product”) is inherently very brittle material, and therefore it is necessary to impart toughness in actual use.

  So far, various techniques for imparting toughness to the unsaturated ester cured product have been disclosed. For example, a softening agent such as a conjugated diene polymer (Patent Document 1), a reactive liquid polymer having a carboxyl group as a terminal group (Patent Document 2), or a vinyl terminal group-containing reactive liquid polymer (Patent Document 3), A method of adding to an unsaturated ester resin is disclosed. However, in the cured product obtained by these methods, although toughness is improved, it is insufficient, and other properties such as mechanical properties (for example, elastic modulus) may be deteriorated.

  Patent Document 4 discloses a method in which an epoxy resin is added to an unsaturated ester resin to prepare a resin composition and then cured with a radical initiator. However, in this method, when uncured epoxy resin comes out on the surface, the surface condition of the cured product is deteriorated (the surface is tacky), or the toughness of the cured product cannot be sufficiently improved was there.

  Patent Document 5 discloses a method of adding a radical initiator and an epoxy resin curing agent to a resin composition obtained by combining an unsaturated ester resin and an epoxy resin. However, this method cannot remarkably improve the toughness of the unsaturated ester resin. Moreover, the epoxy resin curing agent reacts with the double bond of the unsaturated ester resin and the curing reaction of the epoxy resin becomes insufficient, and the surface state may not be improved.

  Recent research (for example, Non-Patent Document 1) reports that the addition of acrylonitrile-butadiene-styrene (ABS) resin to an unsaturated ester resin improves the toughness of the resulting cured product. However, in this method, the elastic modulus, which is one of the most important characteristics of the cured product, may be reduced.

U.S. Pat. No. 3,231,634 U.S. Pat. No. 4,419,487 U.S. Pat. No. 4,350,789 U.S. Pat. No. 3,634,542 US Pat. No. 5,137,990

Polymer, vol. 43, 4503-4514 (2002)

  The present invention has been made in view of the above circumstances, and an object of the present invention is a curable resin that is excellent in mechanical properties (for example, elastic modulus and the like) and toughness, and can give a cured product having a good surface state. It is to provide a composition.

  The present inventors have intensively studied a method for dramatically improving the toughness of the cured product of the unsaturated ester resin composition. In particular, when rubber-like linear polymers are used, mechanical properties such as elastic modulus may be deteriorated. Therefore, the use of crosslinked rubber particles has been studied.

  Surprisingly, when a radical initiator is added to the unsaturated ester resin composition containing the unsaturated ester resin and the epoxy resin in the presence of specific crosslinked rubber particles and cured, the resin composition contains The radical initiator is involved only in the cross-linking reaction of the carbon-carbon unsaturated double bond and is hardly involved in the curing reaction of the epoxy resin. Regardless, the present inventors have found that a cured product having a good surface state, no reduction in elastic modulus, and significantly improved toughness can be obtained.

Specifically, the unsaturated ester resin composition of the present invention that has been able to solve the above problems includes an unsaturated ester resin of 60 to 99 parts by mass, an epoxy resin of 0.5 to 20 parts by mass, and a butadiene rubber. From alkyl (meth) acrylate and allyl (meth) acrylate in the presence of one or more cross-linked rubber polymers selected from the group consisting of butadiene-styrene rubber, butadiene butyl acrylate rubber, butyl acrylate rubber, and organosiloxane rubber 0.1 or more cross-linked rubber particles having a number average particle diameter of 20 to 600 nm, obtained by polymerizing at least 75% by mass of a vinyl monomer (100% by mass) with at least 75% by mass selected from the group consisting of The crosslinked rubber particles are dispersed in the state of primary particles throughout the unsaturated ester resin composition. And wherein the door.

  In a preferred embodiment, the unsaturated ester resin is an unsaturated ester resin composed of 51 to 80% by mass of a curable unsaturated ester compound and 20 to 49% by mass of an ethylenically unsaturated monomer. That is.

  In the present invention, the step of mixing the crosslinked rubber particles and the epoxy resin to obtain a crosslinked rubber particle-containing epoxy resin, and the step of mixing the crosslinked rubber particle-containing epoxy resin and the unsaturated ester resin And a process for producing the unsaturated ester resin composition. Furthermore, the manufacturing method of the unsaturated ester hardened | cured material characterized by including the process of adding 0.1-5 mass parts of radical initiators with respect to 100 mass parts of said unsaturated ester resin compositions, and also hardening | curing it. Are included in the present invention.

  In the present invention, an unsaturated ester cured product obtained by adding 0.1 to 5 parts by mass of a radical initiator to 100 parts by mass of the unsaturated ester resin composition and curing it. Are also included. Here, it is a preferred embodiment that the crosslinked rubber particles are dispersed in a cured product in the form of primary particles.

  Since the unsaturated ester resin composition of the present invention is a combination of specific crosslinked rubber particles and an epoxy resin, the unsaturated ester-based cured product has a good surface condition, no decrease in elastic modulus, and greatly improved toughness. Can be obtained.

It is an electron micrograph of unsaturated ester type hardened material of the present invention.

[Unsaturated ester resin composition]
The unsaturated ester resin composition of the present invention comprises unsaturated ester resin 60 to 99 parts by mass, epoxy resin 0.5 to 20 parts by mass, butadiene rubber, butadiene-styrene rubber, butadiene butyl acrylate rubber, butyl acrylate. Crosslinked rubber particles 0.1 to 20 having a number average particle diameter of 20 to 600 nm obtained by polymerizing a vinyl monomer in the presence of one or more rubber polymers selected from the group consisting of rubber and organosiloxane rubbers And the crosslinked rubber particles are dispersed in the state of primary particles throughout the unsaturated ester resin composition. Hereinafter, the unsaturated ester resin composition of the present invention will be described in detail.

(Unsaturated ester resin)
The unsaturated ester resin used in the present invention is composed of a curable unsaturated ester compound and an ethylenically unsaturated monomer. It is preferable that 51-80 mass% is contained in 100 mass% of unsaturated ester resin from a viewpoint of a physical property balance, and, as for a curable unsaturated ester compound, it is more preferable that 55-75 mass% is contained. .

  Unsaturated ester resins are sold for molding and laminating. When a commercially available product is used in the present invention, the content of curable unsaturated ester compound is about 60% by mass (ethylenically unsaturated monomer). It is preferable to select a solution having a content rate of about 40% by mass. For example, DERAKANE (registered trademark) 411-35, which is a vinyl ester resin described later, contains 45% styrene as an ethylenically unsaturated monomer.

<Curable unsaturated ester compound>
The curable unsaturated ester compound is not particularly limited as long as it is a curable compound having an ethylenic double bond and an ester group. For example, a polyhydric alcohol and an unsaturated polycarboxylic acid or anhydride thereof And unsaturated polyesters obtained from the above, vinyl esters obtained from unsaturated monocarboxylic acids and polyvalent epoxides, and the like.

≪Unsaturated polyester≫
Examples of the polyhydric alcohol include carbon atoms such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, di-1,2 propylene glycol, 1,4-butanediol, and neopentyl glycol. Is a dihydric alcohol having 2 to 12 carbon atoms, preferably a dihydric alcohol having 2 to 6 carbon atoms, and more preferably propylene glycol. These dihydric alcohols may be used alone or in combination of two or more.

  Examples of the unsaturated polyvalent carboxylic acid include divalent carboxylic acids having 3 to 12 carbon atoms, and more preferably divalent carboxylic acids having 4 to 8 carbon atoms. Specific examples include fumaric acid and maleic acid. These divalent carboxylic acids may be used alone or in combination of two or more.

  In the present invention, a saturated polyvalent carboxylic acid or an anhydride thereof may be used in combination with the unsaturated polyvalent carboxylic acid or the anhydride thereof. At this time, the unsaturated polyvalent carboxylic acid is at least 50 mol% or more. It is preferably included. Examples of the saturated polyvalent carboxylic acid or its anhydride include phthalic anhydride, terephthalic acid, isophthalic acid, adipic acid, glutaric acid and the like. These saturated polyvalent carboxylic acids or anhydrides thereof may be used alone or in combination of two or more.

  Unsaturated polyester, the polyhydric alcohol and unsaturated polyvalent carboxylic acid or anhydride thereof, for example, in the presence of a catalyst such as an organic titanate such as tetrabutyl titanate, an organic tin compound such as dibutyltin oxide, It can be obtained by a condensation reaction.

  The curable unsaturated ester compound can also be obtained commercially from, for example, Ashland, Reichhold, AOC, and the like.

≪Vinyl ester≫
Examples of the unsaturated monocarboxylic acid include (meth) acrylic acid and crotonic acid.

  Examples of the polyvalent epoxide include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and novolak type epoxy resins.

  The formation reaction of vinyl ester and its kind are described in US Pat. No. 3,179,623. For example, a vinyl ester produced by reacting methacrylic acid with a bisphenol A type epoxy resin or a novolac type epoxy resin is well known as a typical example.

  Vinyl esters can also be obtained commercially, for example, as DERAKANE 411-35 and DERAKANE 470-300 from Ashland.

  In this invention, you may use other vinyl esters other than the above typical vinyl esters, for example, the urethane modified vinyl ester etc. which can be obtained as DION9800 of Reichhold.

<Ethylenically unsaturated monomer>
The ethylenically unsaturated monomer constituting the unsaturated ester resin together with the curable unsaturated ester compound is polymerized to an unsaturated group in the ester main chain to form a polymer chain between the crosslinking points. Moreover, it functions also as a solvent of a curable unsaturated ester compound, and improves the handleability of a curable unsaturated ester compound. Examples of such ethylenically unsaturated monomers include aromatic group-containing unsaturated monomers such as styrene and methylstyrene (vinyltoluene); nitrile group-containing unsaturated monomers such as acrylonitrile; methyl acrylate, Ester group-containing unsaturated monomers such as methyl methacrylate and vinyl acetate; condensation reaction products of polyhydric carboxylic acids such as phthalic acid, adipic acid, maleic acid and malonic acid with unsaturated alcohols such as allyl alcohol, cyanur Examples include polyfunctional ester monomers such as acid allyl esters. These may be used alone or in combination of two or more. In particular, aromatic group-containing unsaturated monomers such as styrene and methylstyrene are preferable from the viewpoint of physical properties.

(Epoxy resin)
Since the unsaturated ester resin composition of the present invention includes an epoxy resin, the toughness of a cured product obtained from the composition can be improved. Examples of such epoxy resins include aromatic epoxy resins such as monofunctional or polyfunctional glycidyl ethers of bisphenols (such as bisphenol A and bisphenol F); 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylic acid ester And alicyclic epoxy resins such as 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxycyclohexanecarboxylate. These epoxy resins may be used alone or in combination of two or more. Bisphenol A type epoxy resins are commercially available, for example, as Epon 828 from Hexion Specialty Chemicals and as DER 331 from Dow Chemical. The bisphenol F type epoxy resin is available, for example, as Epon862 or Epon863 from Hexion Specialty Chemicals.

(Crosslinked rubber particles)
Since the unsaturated ester resin composition of the present invention is configured to further contain crosslinked rubber particles together with the epoxy resin, the toughness of the cured product obtained by curing the composition is remarkably improved, and the epoxy resin Oozes out to the surface of the cured product. Moreover, it can prevent that the intrinsic elasticity of unsaturated ester resin falls.

  The crosslinked rubber particles used in the present invention are one kind in the presence of one or more kinds of rubber polymers selected from the group consisting of butadiene rubber, butadiene-styrene rubber, butadiene butyl acrylate rubber, butyl acrylate rubber, and organosiloxane rubber. It can be obtained by polymerizing the above vinyl monomers. The crosslinked rubber particles can be formed by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, and the like, and is preferably manufactured by emulsion polymerization from the viewpoint of particle size control.

  The method for introducing the crosslinked structure into the rubber polymer is not particularly limited, and a generally used method can be employed. For example, a method in which a crosslinkable monomer such as a polyfunctional vinyl compound or a mercapto group-containing compound is added to the rubber polymer and then polymerized is exemplified.

  The rubber polymer often has a single layer structure, but may have a multilayer structure. When the rubber polymer has a multilayer structure, the polymer composition of each layer may be different.

  The crosslinked rubber particles are preferably 55 to 97% by mass, more preferably 70 to 90% by mass of a rubber polymer core polymer, and preferably 3 to 45% by mass, more preferably 10 to 30% by mass of the vinyl unit. And a shell polymer which is a polymer of a monomer.

  When the content rate of the shell polymer is less than 3% by mass, the crosslinked rubber particles are easily aggregated during handling, which may cause a problem in operability. Moreover, when the content rate of a shell polymer exceeds 45 mass%, the content rate of the core polymer in a crosslinked rubber particle will fall, and there exists a tendency for the toughness improvement effect with respect to hardened | cured material to fall.

  The rubber polymer is preferably at least one selected from butadiene rubber, butyl acrylate rubber, and organosiloxane rubber from the viewpoint of improving toughness, and more preferably butadiene rubber.

Examples of the vinyl monomer include aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; ) Acrylate, ethyl (meth) acrylate, alkyl (meth) acrylate such as butyl (meth) acrylate; allyl (meth) acrylate; glycidyl vinyl monomer such as glycidyl (meth) acrylate and glycidyl vinyl ether; hydroxyethyl (meth) acrylate And hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate; divinyl monomers such as ethylene glycol di (meth) acrylate and 1,3 butylene glycol di (meth) acrylate. The vinyl monomer may be used alone or in combination of two or more, but in order to disperse the crosslinked rubber particles in the state of primary particles throughout the unsaturated ester resin composition, before Symbol vinyl monomer in 100% by mass, it is at least alkyl (meth) acrylate, and allyl (meth) over at least one monomer selected from the group consisting of acrylate at least 75 wt%.

In the present invention, for example, styrene 0-20 wt%, methyl methacrylate 75 to 100 wt%, allyl (meth) acrylate 0-20% by weight, and the shell polymer forming monomer which is a combination of 0 to 15 wt% glycidyl methacrylate It is preferable to use a shell polymer that is a polymer (100% by mass ). Thereby, a desired toughness improving effect and mechanical properties can be realized in a well-balanced manner. Particularly, it preferred considered interfacial adhesion between Matricaria click scan resins by including allyl methacrylate as a constituent component can be improved.

  Since the rubber is crosslinked, the crosslinked rubber particles contain a solvent-insoluble component. The amount of solvent-insoluble matter in the crosslinked rubber particles (ie, the gel fraction of rubber) is determined by immersing the sample in an excess amount of methyl ethyl ketone (MEK) for 24 hours at room temperature and then centrifuging at 12,000 rpm for 1 hour. The soluble fraction is removed together with the solvent, and the ratio of the residual sample mass to the input sample mass when the mass of the remaining MEK insoluble matter is measured is expressed in mass%. The amount of solvent insolubles in the crosslinked rubber particles used in the present invention is preferably 80 to 100% by mass and more preferably 90 to 100% by mass from the viewpoint of obtaining an excellent performance balance.

  The number average particle diameter of the crosslinked rubber particles used in the present invention is 20 to 600 nm, and is preferably 50 to 400 nm from the viewpoint of effective toughness improvement. The number average particle diameter of the crosslinked rubber particles can be measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.).

  From the viewpoint of effectively improving the toughness of the cured product, making the surface state good, and suppressing the decrease in elastic modulus, the crosslinked rubber particles of the present invention are in the state of primary particles in the unsaturated ester resin composition. It is preferable that they are dispersed. In this specification, “the state of primary particles” refers to a state in which crosslinked rubber particles having a primary particle diameter of 20 to 600 nm are evenly dispersed throughout the unsaturated ester resin plastic (without aggregation).

(Mixing ratio)
The unsaturated ester resin composition of the present invention includes 60 to 99 parts by mass of an unsaturated ester resin and 0.5 to 20 parts by mass of an epoxy resin, and further 0.1 to 20 parts by mass of crosslinked rubber particles. It is necessary to include. From the viewpoint of the balance between toughness and mechanical properties, an unsaturated ester resin composition comprising 76 to 97 parts by mass of unsaturated ester resin, 2 to 16 parts by mass of epoxy resin, and 1 to 8 parts by mass of crosslinked rubber particles. Preferably there is.

  That is, the resin composition of the present invention comprises 0.1 to 20% by mass of crosslinked rubber particles, and 100% by mass of the composition (total of crosslinked rubber particles, epoxy resin and unsaturated ester resin). Resin 0.5-20 mass% and unsaturated ester resin (mixture of a curable unsaturated ester compound and an ethylenically unsaturated monomer) 60-99.4 mass% are included.

[Method for producing unsaturated ester resin composition]
The unsaturated ester resin composition of the present invention is a state in which the crosslinked rubber particles are primary particles in order to obtain an unsaturated ester cured product having a good surface state, no decrease in elastic modulus, and greatly improved toughness. More preferably, it is dispersed. A method for producing the unsaturated ester resin composition in such a state will be described below.

(Method for producing unsaturated ester curable composition)
The unsaturated ester resin composition of the present invention comprises a step of mixing crosslinked rubber particles and an epoxy resin to obtain a crosslinked rubber particle-containing epoxy resin, the crosslinked rubber particle-containing epoxy resin, and an unsaturated ester resin. It is preferable to manufacture through the process of mixing. As a result, air bubbles can be easily removed from the mixture (resin composition), and further, the crosslinked rubber particles are dispersed in the unsaturated ester resin plastic material in the form of primary particles without agglomeration, and the toughness of the cured product is greatly improved. be able to.

  The crosslinked rubber particle-containing epoxy resin can be obtained by using a method described in the prior art (for example, US Pat. No. 4,778,851), but the crosslinked rubber particle of the present invention is contained in the epoxy resin. From the viewpoint of dispersing in the state of primary particles, and from the viewpoint of producing a crosslinked rubber particle-containing epoxy resin at a high speed and low cost to an extent capable of industrial production, the following steps are preferably performed. That is, a first step for obtaining a crosslinked rubber particle loose aggregate containing a specific organic solvent, a second step for obtaining a crosslinked rubber particle-dispersed epoxy resin by adding an epoxy resin to the loose aggregate, and this crosslinked rubber particle dispersion. And a third step of removing the specific organic solvent from the epoxy resin.

  Specifically, in the first step, an aqueous medium dispersion in which crosslinked rubber particles are dispersed in an aqueous medium is used as a raw material. After mixing this raw material with a specific organic solvent (preferably MEK) having a solubility in water at 20 ° C. of 5% by mass or more and 40% by mass or less, a coagulant (preferably sodium sulfate aqueous solution) and excess water are added and mixed. Then, the crosslinked rubber particles are extracted into the organic solvent phase, and then the aqueous phase not containing the crosslinked rubber particles is separated and removed. In this way, an organic solvent phase containing slowly aggregated crosslinked rubber particles is obtained, which is referred to as a crosslinked rubber particle loose aggregate. In the present invention, this first step may be repeated for the obtained crosslinked rubber particle loose aggregate. Thereby, impurities (water-soluble impurities) contained in the crosslinked rubber particles can be removed.

[Method for producing unsaturated ester-based cured product]
The unsaturated ester cured product of the present invention can be produced by further adding a radical initiator to the unsaturated ester resin composition of the present invention and curing it. In that case, the addition amount of the radical initiator is 0.1 to 5 parts by mass (more preferably 0.5 to 3 parts by mass) with respect to 100 parts by mass of the unsaturated ester resin composition. The radical initiator used in this production method is considered to act exclusively as a curing agent for unsaturated ester resins because of its small amount.

  A method for curing the unsaturated ester resin composition of the present invention is not particularly limited, and a method generally used as a molding method for a thermosetting resin composition, for example, an infusion method, a resin transfer molding ( Examples include RTM) method, pultrusion method, hand layup method, spray layup method, and casting method, and a method of curing while molding. In that case, if it hardens | cures, combining composite materials, such as a fiber and a textile fabric, the hardened | cured material which has a higher elasticity modulus can be obtained.

  The curing conditions are set in consideration of many factors such as a radical initiator to be used. For example, the unsaturated ester resin composition of the present invention or a composite thereof is introduced into a mold, and 20 ° C to 200 ° C. It may be cured under heating and pressure appropriately set from the temperature range of 0.5 to 250 psi.

(Radical initiator)
The radical initiator used in the present invention is a curing agent of an unsaturated ester resin, and is an initiator of a crosslinking reaction of a carbon-carbon unsaturated double bond in the resin. If necessary, a curing accelerator or Used with cocatalyst.

  Such radical initiators include benzoyl peroxide, cumene hydroperoxide, dicumyl peroxide, lauroyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, t-butyl. Organic peroxides such as perbenzoate; and azo compounds such as azobisisobutyronitrile. From the viewpoint of curing the unsaturated ester resin more effectively, one or more selected from the group consisting of benzoyl peroxide, cumene hydroperoxide, dicumyl peroxide, and methyl ethyl ketone peroxide is preferable, and cumene is more preferable. Hydroperoxide and dicumyl peroxide.

  Curing accelerators are additives that act as catalysts for radical initiator decomposition reactions (radical generation reactions), including naphthenic acid and octenoic acid metal salts (cobalt salts, tin salts, lead salts, etc.) and toughness. From the viewpoint of improving the appearance and appearance, cobalt naphthenate is preferred. When a curing accelerator is added, in order to prevent a curing reaction from occurring suddenly, immediately before the reaction (for example, after introducing the unsaturated ester resin composition of the present invention into a mold), It is preferable to add 0.1-1 mass part with respect to 100 mass parts of unsaturated ester resin composition.

  The cocatalyst is an additive for causing radical generation to occur at a low temperature so that the radical initiator decomposes even at a low temperature, and examples thereof include amine compounds such as N, N-dimethylaniline, triethylamine, and triethanolamine. However, N, N-dimethylaniline is preferable because an efficient reaction is possible. When adding a co-catalyst, 0.01-0.5 mass part with respect to 100 mass parts of unsaturated ester resin composition of this invention, or 1-15 mass with respect to 100 mass parts of radical initiators. It is preferable to add in the range of parts. The amine compound is also a curing agent for the epoxy resin. However, since the amine compound is a tertiary amine and has no active hydrogen, this alone is insufficient as an epoxy curing agent. Therefore, it is usually used in combination with a primary amine or secondary amine curing agent. For this reason, even when the amine compound is added in the present invention, the object is to expect the action of the radical initiator as a promoter.

[Unsaturated ester-based cured product]
In the unsaturated ester cured product of the present invention produced by the above method, the crosslinked rubber particles are dispersed in the cured product in the form of primary particles. And this hardened | cured material has the outstanding mechanical characteristic including a fracture toughness that an epoxy resin does not ooze out easily.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and can be implemented with appropriate modifications within a range that can be adapted to the above and the gist described below. These are all included in the technical scope of the present invention. In the following examples and comparative examples, “parts” and “%” mean parts by mass and mass%, respectively.

Evaluation method First, the evaluation method of the resin composition and hardened | cured material which were manufactured by the Example and the comparative example is demonstrated below.

(Latex solids)
The latex sample obtained after the reaction was dried in a hot air dryer at 120 ° C. for 1 hour, and the solid content was measured based on the remaining amount after drying.

(Solvent insoluble component amount (gel fraction))
5 g of latex was put into 60 ml of methanol. The resulting precipitate was centrifuged and dried at 50 ° C. for 3 hours. The sample thus obtained was immersed in methyl ethyl ketone for 24 hours, and then centrifuged at 12,000 rpm for 1 hour, and the mass fraction of methyl ethyl ketone insoluble matter in the sample was calculated.

(Fracture toughness)
Fracture toughness G1c was measured at 23 ° C. using a 1/4 inch bar with a notch in accordance with ASTM D-5045.

(Flexural modulus)
Flexural modulus was measured at 23 ° C. using a 1/4 inch bar according to ASTM D-790.

(Production Example 1: Production of crosslinked rubber particles)
1300 g of rubber latex and 440 g of pure water were charged into a 3 liter glass reactor, and this mixture was heated to 70 ° C. with stirring while introducing nitrogen. This rubber latex contains 480 g of polybutadiene particles having an average particle diameter of 0.1 μm and 1.5% by mass of sodium dodecylbenzenesulfonate based on 100% by mass of this polybutadiene. After adding 1.2 g of azoisobutyronitrile, a mixture of 6 g of styrene, 108 g of methyl methacrylate, and 6 g of glycidyl methacrylate was added over 3 hours. Thereafter, the mixture was further stirred for 2 hours to obtain a rubber particle latex (latex (A)). The solid content of the latex (A) was 32%. Further, the gel fraction of the latex (A) is 98%, which indicates that the rubber particles are crosslinked.

(Production Example 2: Production of dispersion in which latex (A) is dispersed in epoxy resin)
340 g of methyl ethyl ketone (MEK) was charged into a 1 liter tank, and 273 g of the latex (A) obtained in Preparation Example 1 was added at 25 ° C. After mixing well, 126 g of pure water was added, and 30 g of 5% by weight aqueous solution of sodium sulfate was added with stirring. When the stirring was stopped, the aqueous phase and the MEK phase were separated. After removing the aqueous phase and adding 90 g of MEK to the remaining MEK phase, 302 g of pure water was added with stirring, and 30 g of a 5% by weight aqueous solution of sodium sulfate was further added. When the stirring was stopped, the aqueous phase and the MEK phase were separated. The aqueous phase was removed, and the remaining MEK phase and 204 g of bisphenol A type epoxy resin (Epon 828: manufactured by Hexion Specialty Chemicals) were mixed as an epoxy resin. From this mixture, MEK was removed with a rotary evaporator. Thus, a dispersion (dispersion (B)) in which latex (A) was dispersed in bisphenol A type epoxy resin was obtained. 100% by mass of the dispersion (B) is composed of 70% by mass of epoxy resin and 30% by mass of crosslinked rubber particles.

  In order to examine the degree of dispersion of the rubber particles, piperidine was added to this dispersion and cured at 120 ° C. for 16 hours. The appearance of the obtained cured product was transparent. This indicates that the crosslinked rubber particles are completely primary dispersed in the epoxy resin.

Example 1
Dispersion (B) was mixed with a bisphenol A type epoxy vinyl ester resin (DERAKANE 411-350, manufactured by Ashland) as an unsaturated ester resin at room temperature to obtain an unsaturated ester resin composition. This DERAKANE 411-350 contains styrene as an ethylenically unsaturated monomer and a reaction product of bisphenol A type epoxy and methacrylic acid as a curable unsaturated ester compound. Further, cobalt naphthenate (CoN) as a curing accelerator and cumene hydroperoxide (CHP) as a radical initiator were added to the unsaturated ester resin composition. The amount added is shown in Table 1. The obtained mixture was poured into a vertical mold and formed into a plate shape of about 12 cm × 12 cm × 0.5 cm. After curing at 24 ° C. for 24 hours, post-curing was performed at 120 ° C. for 2 hours to prepare a test panel. Test specimens suitable for each test method were cut from several pieces of the test panels, and fracture toughness and flexural modulus were measured. The test results are shown in Table 1.

  The test panel was observed with an electron microscope (FIG. 1). In FIG. 1, the crosslinked rubber particles are dyed with OsO4. It can be seen that the unsaturated ester cured product of the present invention has the crosslinked rubber particles uniformly dispersed (dispersed in the form of primary particles) in the cured product.

(Comparative Example 1)
Without using the dispersion (B), only the bisphenol A type epoxy vinyl ester resin was cured by the same method as in Example 1 to obtain a test piece. Table 1 shows the test results of the test pieces.

(Comparative Example 2)
Instead of the dispersion (B), a bisphenol A type epoxy resin (Epon 828: manufactured by Hexion Specialty Chemicals) was added and cured in the same manner as in Example 1 to obtain a test piece. Table 1 shows the test results of the test pieces.

  From this result, it can be seen that the cured product of the present invention has improved toughness and elastic modulus.

(Example 2)
Dispersion (B) was mixed with urethane-modified vinyl ester resin (DION 9800-05A, manufactured by Reichhold) as an unsaturated ester resin at room temperature to obtain an unsaturated ester resin composition. This DION 9800-05A contains styrene as an ethylenically unsaturated monomer and a urethane-modified vinyl ester resin as a curable unsaturated ester compound. Further, benzoyl peroxide (BPO) as a radical initiator was added to the unsaturated ester resin composition. The amount added is shown in Table 2. The obtained mixture was poured into a vertical mold and formed into a plate shape of about 12 cm × 12 cm × 0.5 cm. After curing at 60 ° C. for 17 hours, post-curing was performed at 120 ° C. for 2 hours to prepare a test panel. Test specimens suitable for each test method were cut from several pieces of the test panels, and fracture toughness and flexural modulus were measured. The test results are shown in Table 2.

(Comparative Example 3)
Without using the dispersion (B), only the urethane-modified vinyl ester resin was cured by the same method as in Example 2 to obtain a test piece. Table 2 shows the test results of the test pieces.

  From this result, it can be seen that the cured product of the present invention has improved toughness and elastic modulus.

Claims (6)

60 to 99 parts by mass of unsaturated ester resin,
0.5-20 parts by weight of epoxy resin,
Alkyl (meth) acrylate and allyl (meth) in the presence of one or more cross-linked rubber polymers selected from the group consisting of butadiene rubber, butadiene-styrene rubber, butadiene butyl acrylate rubber, butyl acrylate rubber, and organosiloxane rubber Crosslinked rubber particles 0 having a number average particle size of 20 to 600 nm, obtained by polymerizing a vinyl monomer (100% by mass) containing at least 75% by mass of one or more monomers selected from the group consisting of acrylates. 1 to 20 parts by mass;
And the crosslinked rubber particles are dispersed in the state of primary particles throughout the unsaturated ester resin composition.   The unsaturated ester resin composition according to claim 1, wherein the unsaturated ester resin is composed of 51 to 80% by mass of a curable unsaturated ester compound and 20 to 49% by mass of an ethylenically unsaturated monomer. object. Mixing the crosslinked rubber particles and the epoxy resin to obtain a crosslinked rubber particle-containing epoxy resin, and mixing the crosslinked rubber particle-containing epoxy resin and the unsaturated ester resin. The method for producing an unsaturated ester resin composition according to claim 1 or 2.   A step of adding 0.1 to 5 parts by mass of a radical initiator and curing with respect to 100 parts by mass of the unsaturated ester resin composition obtained by the production method according to claim 3. A method for producing a saturated ester-based cured product.   An unsaturated ester obtained by adding 0.1 to 5 parts by mass of a radical initiator to 100 parts by mass of the unsaturated ester resin composition according to claim 1 or 2, and curing it. Hardened material.   The unsaturated ester cured product according to claim 5, wherein the crosslinked rubber particles are dispersed in a state of primary particles.