Method for producing radically curable resin composition

Abstract

To provide a method for producing a radical curable resin composition with excellent moldability, while suppressing aldehyde emission during curing.SOLUTION: A method for producing a radical curable resin composition includes a first step for mixing a low-shrinkage agent with an aldehyde scavenger to obtain a mixture, and a second step for mixing the mixture with a radical-polymerizable resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a radically curable resin composition. [Background technology]

[0002] BACKGROUND ART Radical-curable resin compositions containing radical-polymerizable resins such as unsaturated polyester resins have been used in the construction industry to finish building materials.

[0003] On the other hand, these radically curable resin compositions may generate formaldehyde during curing, which may pose a serious health hazard.

[0004] Therefore, as a radical curable resin composition, for example, a resin composition for sheet molding compounds and bulk molding compounds containing an unsaturated polyester resin composition, a low-profile agent, and ethylene urea (a formaldehyde scavenger) has been proposed (see, for example, Example 1 of Patent Document 1 below). In the resin composition of Patent Document 1, the amount of formaldehyde emitted is suppressed by ethylene urea. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-154589 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, when volatile organic compounds (VOCs) emitted from building materials and interior materials become highly concentrated in living spaces, problems arise in that people living there suffer from health problems such as sick building syndrome.

[0007] Recently, attention has also been focused on the environment inside a vehicle. Generally, due to exposure to sunlight, the temperature inside a vehicle is often higher than in a home, and in the scorching summer sun, it can exceed 50°C. It has become clear that the types and quantities of VOCs inside a vehicle are extremely high.

[0008] In particular, molding materials (for example, SMC) are increasingly required to suppress the amount of aldehyde emissions.

[0009] Furthermore, when a molded article is produced using a radically curable resin composition, productivity is required.

[0010] The present invention provides a method for producing a radical-curable resin composition that is excellent in productivity while suppressing the amount of aldehyde emitted during curing. [Means for solving the problem]

[0011] The present invention [1] is a method for producing a radical-curable resin composition, comprising a first step of dissolving an aldehyde scavenger in a low-profile agent to obtain a mixture, and a second step of mixing the mixture with a radical-polymerizable resin.

[0012] The present invention [2] includes the method for producing a radical-curable resin composition according to the above [1], wherein the aldehyde scavenger is a urea compound.

[0013] The present invention [3] includes the method for producing a radically curable resin composition according to the above [2], wherein the urea compound is ethylene urea.

[0014] The present invention [4] includes the method for producing a radically curable resin composition according to any one of the above [1] to [3], wherein the blending ratio of the aldehyde scavenger is 1 part by mass or more and 3 parts by mass or less per 100 parts by mass of the total amount of the radically polymerizable resin and the low shrinkage agent.

[0015] The present invention [5] includes the method for producing a radically curable resin composition according to any one of the above [1] to [4], wherein in the second step, a curing agent is further mixed, and the curing agent is t-amylperoxyisopropyl carbonate. [Effects of the Invention]

[0016] The method for producing a radically curable resin composition of the present invention involves dissolving an aldehyde scavenger in a low-profile agent to obtain a mixture, and then mixing the mixture with a radically polymerizable resin. This makes it possible to produce a radically curable resin composition with excellent productivity while suppressing the amount of aldehyde emitted during curing. DETAILED DESCRIPTION OF THE INVENTION

[0017] The method for producing a radically curable resin composition of the present invention includes a first step of dissolving an aldehyde scavenger in a low-profile agent to obtain a mixture, and a second step of mixing the mixture with a radically polymerizable resin. That is, in this method, the aldehyde scavenger is first dissolved in a low-profile agent to obtain a mixture, and the mixture is then mixed with a radically polymerizable resin. Therefore, as will be described in detail later, it is possible to produce a radically curable resin composition with excellent productivity while suppressing the amount of aldehyde emitted during curing.

[0018] <1st process> In the first step, an aldehyde scavenger is dissolved in a low-profile agent to obtain a mixture.

[0019] When a molded article (described later) is obtained using the radical curable resin composition, the low-profile agent is blended to suppress cure shrinkage and heat shrinkage of the molded article (described later).

[0020] The low-profile agent includes a low-profile polymer, such as polyethylene, polystyrene, styrene-based thermoplastic elastomer, crosslinked polystyrene, polyvinyl acetate-polystyrene block copolymer, polyvinyl acetate, polymethyl methacrylate, and saturated polyester.

[0021] Examples of the styrene-based thermoplastic elastomer include a styrene-butadiene block copolymer elastomer, a styrene-isoprene block copolymer elastomer, a styrene-ethylene / butylene block copolymer elastomer, and a styrene-ethylene / propylene block copolymer elastomer. A preferred example of the styrene-based thermoplastic elastomer is a styrene-butadiene block copolymer elastomer.

[0022] Commercially available styrene-based thermoplastic elastomers may also be used, such as D1101, D1102, D1155, DKX405, DKX410, DKX415, D1192, D1161, D1171, G1651, G1652, G1654, G1701, and G1730 (all manufactured by Kraton Polymers), Asaprene T411, Asaprene T432, Tufprene A, Tufprene 125, Tufprene 126S, Tufprene 315, Tufprene 912, Tuftec H1141, Tuftec H1041, Tuftec H1043, and Tuftec H1052 (all manufactured by Asahi Kasei Corporation), and Septon 1001 and 1201 (all manufactured by Kuraray Co., Ltd.).

[0023] The styrene content in the styrene-based thermoplastic elastomer is, for example, 5% by mass or more and, for example, 80% by mass or less.

[0024] The low-shrinkage polymer is preferably polystyrene, a styrene-based thermoplastic elastomer, polyvinyl acetate, polymethyl methacrylate, or saturated polyester, and more preferably a styrene-based thermoplastic elastomer, polyvinyl acetate, or saturated polyester.

[0025] The number average molecular weight of the low shrinkage polymer is, for example, 5,000 or more, preferably 10,000 or more, and for example, 200,000 or less, preferably 100,000 or less.

[0026] The low-profile polymers can be used alone or in combination of two or more.

[0027] The low shrinkage agent is prepared as a solution in which the low shrinkage polymer is dissolved in a polymerizable monomer (preferably styrene) described below. That is, the low shrinkage agent preferably contains the low shrinkage polymer and the polymerizable monomer described below, and more specifically, is a polymerizable monomer solution of the low shrinkage polymer.

[0028] The solids concentration of the polymerizable monomer solution of the low-shrinkage polymer is, for example, 20% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 55% by mass or more, and for example, 80% by mass or less, preferably 70% by mass or less. That is, the content of the polymerizable monomer in the polymerizable monomer solution of the low-shrinkage polymer is 20% by mass or more, preferably 30% by mass or more, and for example, 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 45% by mass or less.

[0029] Furthermore, examples of the low shrinkage agent, that is, the polymerizable monomer solution of the low shrinkage polymer, include saturated polyester resins.

[0030] The saturated polyester resin is obtained by dissolving a saturated polyester in a polymerizable monomer, which will be described later. In other words, the saturated polyester resin is a polymerizable monomer solution of a saturated polyester (a polymerizable monomer solution of a low-shrinkage polymer).

[0031] The saturated polyester is a polymerization product of a polybasic acid not containing an ethylenically unsaturated bond, which will be described later, and a polyhydric alcohol, which will be described later.

[0032] Preferred examples of the polybasic acid not containing an ethylenically unsaturated bond include adipic acid and isophthalic acid.

[0033] The polyhydric alcohol is preferably a dihydric alcohol, and more preferably neopentyl glycol.

[0034] Saturated polyesters can be obtained by polycondensation (condensation polymerization) of polybasic acids containing no ethylenically unsaturated bonds with polyhydric alcohols.

[0035] To polycondense (condensation polymerize) a polybasic acid having no ethylenic unsaturated bonds with a polyhydric alcohol, they are blended so that the equivalent ratio of the polybasic acid to the polyhydric alcohol (hydroxyl groups of the polyhydric alcohol / carboxyl groups of the polybasic acid) is, for example, 0.9 or more, preferably 0.95 or more, and for example, 1.2 or less, preferably 1.1 or less, and stirred under normal pressure in a nitrogen atmosphere.

[0036] The reaction temperature is, for example, 150°C or higher, preferably 190°C or higher, and for example, 250°C or lower, preferably 230°C or lower.

[0037] The reaction time is, for example, 8 hours or more and, for example, 30 hours or less.

[0038] In the above reaction, a known solvent and a known catalyst may be added as needed.

[0039] This gives a saturated polyester.

[0040] The acid value of the saturated polyester (measurement method: in accordance with JIS K6901 (2008)) is, for example, 5 mgKOH / g or more and, for example, less than 40 mgKOH / g.

[0041] Then, this saturated polyester is dissolved in a polymerizable monomer (preferably styrene) described later, and an additive (a polymerization inhibitor (described later) (preferably hydroquinone)) is added as needed to prepare a saturated polyester resin.

[0042] In preparing the saturated polyester resin, the blending ratio of the polymerizable monomer is, for example, 35 parts by mass or more and, for example, 100 parts by mass or less, relative to 100 parts by mass of the saturated polyester, and the blending ratio of the polymerization inhibitor is, for example, 0.001 part by mass or more, preferably 0.005 part by mass or more, and, for example, 0.1 part by mass or less, preferably 0.05 part by mass or less, relative to 100 parts by mass of the saturated polyester.

[0043] The blending ratio of the low-profile agent will be described later.

[0044] The aldehyde scavenger suppresses the amount of aldehyde (specifically, formaldehyde, acetaldehyde, the same applies below) emitted during curing.

[0045] Aldehyde scavengers include, for example, hydrazide compounds and urea compounds.

[0046] Examples of hydrazide compounds include carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, and succinic acid dihydrazide.

[0047] Examples of urea compounds include ethylene urea, dimethylethylene urea, propylene urea, and tetrabutyl urea.

[0048] Furthermore, as the aldehyde scavenger, for example, compound (C) described in JP-A No. 2005-154589 can also be used.

[0049] As the aldehyde scavenger, preferably, a urea compound is used from the viewpoint of further suppressing the amount of aldehyde released during curing, and more preferably, ethylene urea is used from the viewpoint of further suppressing the amount of aldehyde released during curing.

[0050] The proportion of the aldehyde scavenger to be added will be described later.

[0051] In the first step, an aldehyde scavenger is dissolved in a low-shrinkage agent (a polymerizable monomer solution of a low-shrinkage polymer).

[0052] When dissolving an aldehyde scavenger in a low shrinkage agent (a polymerizable monomer solution of a low shrinkage polymer), the aldehyde scavenger is added to the low shrinkage agent (a polymerizable monomer solution of a low shrinkage polymer), and the mixture is heated and stirred to obtain a mixture.

[0053] The heating temperature is, for example, 50° C. or more, preferably 60° C. or more, and for example, 100° C. or less, preferably 90° C. or less. The heating time is, for example, 0.5 hours or more, and for example, 3 hours or less, preferably 2 hours or less.

[0054] The mixture is then cooled to room temperature (25°C).

[0055] The blending ratio of the aldehyde scavenger is, from the viewpoint of suppressing the amount of aldehyde emitted during curing and improving productivity, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and for example, 20 parts by mass or less, preferably 17 parts by mass or less, and more preferably 15 parts by mass or less, relative to 100 parts by mass of the low-shrinkage polymer.

[0056] Furthermore, from the viewpoint of suppressing the amount of aldehyde emitted during curing and improving productivity, the blending ratio of the aldehyde scavenger is, for example, 3 parts by mass or more, preferably 4 parts by mass or more, and more preferably 6 parts by mass or more, and for example, 15 parts by mass or less, preferably 10 parts by mass or less, and more preferably 8 parts by mass or less, relative to 100 parts by mass of the low profile agent.

[0057] <Second process> In the second step, the mixture is mixed with a radical polymerizable resin.

[0058] Examples of the radical polymerizable resin include unsaturated polyester resin, vinyl ester resin, and urethane (meth)acrylate. As the radical polymerizable resin, unsaturated polyester resin is preferred from the viewpoint of excellent properties (toughness, strength, durability, weather resistance, hot water resistance, and transparency).

[0059] The unsaturated polyester resin contains an unsaturated polyester and a polymerizable monomer, that is, the unsaturated polyester resin is an unsaturated polyester resin composition containing an unsaturated polyester and a polymerizable monomer.

[0060] Unsaturated polyesters are condensation products of polybasic acids and polyhydric alcohols.

[0061] The polybasic acid includes a polybasic acid having an ethylenically unsaturated double bond as an essential component (hereinafter referred to as an ethylenically unsaturated bond-containing polybasic acid) and a polybasic acid not having an ethylenically unsaturated double bond as an optional component (hereinafter referred to as an ethylenically unsaturated bond-free polybasic acid).

[0062] Examples of ethylenically unsaturated bond-containing polybasic acids include ethylenically unsaturated aliphatic dibasic acids and anhydrides thereof, halides of ethylenically unsaturated aliphatic dibasic acids, and alkyl esters of ethylenically unsaturated aliphatic dibasic acids.

[0063] Examples of ethylenically unsaturated aliphatic dibasic acids include maleic acid, fumaric acid, itaconic acid, and dihydromuconic acid. Furthermore, examples of ethylenically unsaturated bond-containing polybasic acids include acid anhydrides derived from the above-mentioned ethylenically unsaturated aliphatic dibasic acids. Examples of acid anhydrides derived from ethylenically unsaturated aliphatic dibasic acids include maleic anhydride. Examples of ethylenically unsaturated bond-containing polybasic acids include maleic anhydride.

[0064] Examples of polybasic acids not containing ethylenically unsaturated bonds include saturated aliphatic polybasic acids, saturated alicyclic polybasic acids, aromatic polybasic acids, anhydrides of these acids, halides of these acids, and alkyl esters of these acids.

[0065] Examples of saturated aliphatic polybasic acids include saturated aliphatic dibasic acids.

[0066] Examples of saturated aliphatic dibasic acids include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, hexylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylsuccinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Saturated aliphatic polybasic acids include acid anhydrides derived from the above saturated aliphatic dibasic acids. Examples of acid anhydrides derived from saturated aliphatic dibasic acids include oxalic anhydride and succinic anhydride.

[0067] Examples of saturated alicyclic polybasic acids include saturated alicyclic dibasic acids.

[0068] Examples of saturated alicyclic dibasic acids include HET acid, 1,2-hexahydrophthalic acid, 1,1-cyclobutanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid (cis- or trans-1,4-cyclohexanedicarboxylic acid or a mixture thereof). Examples of saturated alicyclic polybasic acids include acid anhydrides derived from the above saturated alicyclic dibasic acids. Examples of acid anhydrides derived from saturated alicyclic dibasic acids include HET acid anhydride.

[0069] Examples of aromatic polybasic acids include aromatic dibasic acids.

[0070] Examples of aromatic dibasic acids include phthalic acid (orthophthalic acid, isophthalic acid, terephthalic acid), trimellitic acid, and pyromellitic acid. Examples of aromatic polybasic acids include acid anhydrides derived from the above aromatic dibasic acids. Examples of acid anhydrides derived from aromatic dibasic acids include phthalic anhydride.

[0071] The polybasic acids can be used alone or in combination of two or more kinds.

[0072] When the polybasic acid includes an ethylenically unsaturated bond-containing polybasic acid and an ethylenically unsaturated bond-free polybasic acid, the blending ratio of the ethylenically unsaturated bond-containing polybasic acid relative to 100 moles of the polybasic acid is, for example, 10 mol% or more, preferably 20 mol% or more, and for example, 99 mol% or less, preferably 80 mol% or less.

[0073] Polyhydric alcohols include, for example, dihydric alcohols and trihydric alcohols.

[0074] Examples of dihydric alcohols include aliphatic diols, alicyclic diols, and aromatic diols. Examples of aliphatic diols include alkanediols and ether diols. Examples of alkanediols include ethylene glycol, propylene glycol (1,2- or 1,3-propanediol or a mixture thereof), butylene glycol (1,2-, 1,3-, or 1,4-butylene glycol or a mixture thereof), 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, and 3,3-dimethylolheptane. Examples of ether diols include diethylene glycol, triethylene glycol, and dipropylene glycol. Examples of alicyclic diols include cyclohexanediol (1,2-, 1,3-, or 1,4-cyclohexanediol or a mixture thereof), cyclohexanedimethanol (1,2-, 1,3-, or 1,4-cyclohexanedimethanol or a mixture thereof), cyclohexanediethanol (1,2-, 1,3-, or 1,4-cyclohexanediethanol or a mixture thereof), and hydrogenated bisphenol A. Examples of aromatic diols include an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A.

[0075] Examples of trihydric alcohols include glycerin, trimethylolpropane, and triisopropanolamine.

[0076] The polyhydric alcohol is preferably a dihydric alcohol. The polyhydric alcohol is more preferably an aliphatic diol. The polyhydric alcohol is further preferably an alkanediol. The polyhydric alcohol is particularly preferably propylene glycol or neopentyl glycol.

[0077] The polyhydric alcohols can be used alone or in combination of two or more kinds.

[0078] The unsaturated polyester can be obtained by polycondensation of a polybasic acid and a polyhydric alcohol.

[0079] To polycondense a polybasic acid and a polyhydric alcohol, the polybasic acid and the polyhydric alcohol are first mixed in the following equivalent ratio.

[0080] The equivalent ratio of polyhydric alcohol to polybasic acid (hydroxyl groups of polyhydric alcohol / carboxyl groups of polybasic acid) is, for example, 0.9 or more, preferably 0.95 or more, and for example, 1.2 or less, preferably 1.1 or less.

[0081] After mixing the polybasic acid and the polyhydric alcohol, the polybasic acid and the polyhydric alcohol are reacted with each other under normal pressure and under a nitrogen atmosphere while stirring. The reaction temperature is, for example, 150°C or higher, preferably 190°C or higher, and, for example, 250°C or lower, preferably 230°C or lower.

[0082] In the above reaction, a known solvent and a known reaction catalyst may be added as needed.

[0083] This gives an unsaturated polyester.

[0084] The acid value of the unsaturated polyester (measurement method: in accordance with JIS K6901 (2008)) is, for example, 5 mgKOH / g or more, preferably 10 mgKOH / g or more, and for example, less than 40 mgKOH / g, preferably 30 mgKOH / g or less.

[0085] The weight average molecular weight of the unsaturated polyester is, for example, 2,000 or more, preferably 4,000 or more, and for example, 25,000 or less, preferably 20,000 or less.

[0086] The weight average molecular weight is a weight average molecular weight calculated in terms of polystyrene by GPC (gel permeation chromatography), and can be determined by measuring the unsaturated polyester by GPC.

[0087] Examples of the polymerizable monomer include styrene-based monomers and (meth)acrylic acid ester-based monomers.

[0088] Examples of styrene-based monomers include styrene, vinyltoluene, t-butylstyrene, and chlorostyrene.

[0089] Examples of (meth)acrylic acid ester monomers include (meth)acrylic acid alkyl esters, (meth)acrylic acid allyl esters, ring-containing (meth)acrylic acid esters, (meth)acrylic acid hydroxyalkyl esters, (meth)acrylic acid alkoxyalkyl esters, (meth)acrylic acid aminoalkyl esters, (meth)acrylic acid fluoroalkyl esters, and polyfunctional (meth)acrylic acid esters. Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate. Examples of (meth)acrylic acid allyl esters include allyl (meth)acrylate. Examples of ring-containing (meth)acrylic acid esters include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate. Examples of alkoxyalkyl (meth)acrylates include 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate. Examples of aminoalkyl (meth)acrylates include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and chloride salts thereof. Examples of the fluoroalkyl (meth)acrylate include trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate.Examples of polyfunctional (meth)acrylic acid esters include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0090] The polymerizable monomer is preferably a styrene-based monomer, more preferably styrene.

[0091] The polymerizable monomers can be used alone or in combination of two or more kinds.

[0092] The unsaturated polyester resin is prepared by dissolving the unsaturated polyester in a polymerizable monomer (preferably styrene) and, if necessary, adding an additive (a polymerization inhibitor (described later) (preferably hydroquinone)).

[0093] In preparing the unsaturated polyester resin, the blending ratio of the polymerizable monomer is, for example, 50 parts by mass or more, preferably 60 parts by mass or more, and for example, 100 parts by mass or less, relative to 100 parts by mass of the unsaturated polyester. The blending ratio of the polymerization inhibitor is, for example, 0.001 part by mass or more, preferably 0.005 part by mass or more, and for example, 0.1 part by mass or less, preferably 0.05 part by mass or less, relative to 100 parts by mass of the unsaturated polyester.

[0094] In the second step, the mixture is mixed with a radically polymerizable resin to produce a radically curable resin composition.

[0095] In the radical curable resin composition, the blending ratio of the aldehyde scavenger, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low shrinkage agent, is, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and for example, 4 parts by mass or less, preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less.

[0096] When the blending ratio of the aldehyde scavenger is equal to or greater than the above lower limit, the amount of aldehyde emitted can be suppressed.

[0097] Furthermore, if the blending ratio of the aldehyde scavenger is equal to or less than the above upper limit, productivity and moldability can be improved.

[0098] In the radical curable resin composition, the blending ratio of the low profile agent is, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low profile agent, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass or less.

[0099] In the radically curable resin composition, the blending ratio of the low-profile polymer relative to 100 parts by mass of the total amount of the radically polymerizable resin and the low-profile agent is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and for example, 30 parts by mass or less, preferably 20 parts by mass or less.

[0100] In the radical curable resin composition, the blending ratio of the radical polymerizable resin is, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and for example, 80 parts by mass or less, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low shrinkage agent.

[0101] In addition, in the second step, a curing agent is preferably mixed in. In such a case, the radical curable resin composition contains a curing agent.

[0102] Examples of the curing agent include organic peroxides, such as peroxyesters and peroxymonocarbonates.

[0103] Examples of peroxyesters include t-butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxylaurate, t-hexyl peroxyacetate, and t-amylperoxy-3,3,5-trimethylhexanoate. A preferred example of the peroxyester is t-butyl peroxybenzoate. Furthermore, from the viewpoint of reducing the amount of styrene released, preferred examples of the peroxyester include t-hexyl peroxyacetate and t-amylperoxy-3,3,5-trimethylhexanoate.

[0104] Examples of peroxymonocarbonates include t-amylperoxyisopropyl carbonate, t-hexylperoxyisopropyl(mono)carbonate, and bis(4-t-butylcyclohexyl)peroxycarbonate. A preferred example of the peroxymonocarbonate is t-amylperoxyisopropyl carbonate.

[0105] As the curing agent, t-amylperoxyisopropyl carbonate can be used from the viewpoint of further reducing the amount of styrene emitted.

[0106] On the other hand, although the use of t-amylperoxyisopropyl carbonate can further reduce the amount of styrene emitted, the amount of aldehyde emitted tends to increase due to the generation of aldehyde caused by t-amylperoxyisopropyl carbonate. However, in this method for producing a radical-curable resin composition, an aldehyde scavenger is first dissolved in a low-profile agent to obtain a mixture, and this mixture is then mixed with a radical-polymerizable resin, so that even when t-amylperoxyisopropyl carbonate is used, the increase in the amount of aldehyde emitted can be suppressed.

[0107] The curing agents can be used alone or in combination of two or more.

[0108] The mixing ratio of the curing agent is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low shrinkage agent.

[0109] In addition, additives can be further mixed in an appropriate ratio in the second step, in which case the radically curable resin composition contains the additives.

[0110] Examples of additives include polymerization inhibitors, wetting and dispersing agents, release agents, colorants, flame retardants, pattern materials, antibacterial agents, hydrophilic agents, photocatalysts, UV absorbers, UV stabilizers, separation inhibitors, silane coupling agents, antistatic agents, thixotropic agents, thixotropic stabilizers, and polymerization accelerators. The additives can be used alone or in combination of two or more.

[0111] The polymerization inhibitor is added to adjust the pot life and the curing reaction.

[0112] Examples of the polymerization inhibitor include hydroquinone compounds, benzoquinone compounds, catechol compounds, phenol compounds, and N-oxyl compounds. Examples of the polymerization inhibitor include benzoquinone compounds. Examples of the benzoquinone compounds include p-benzoquinone and methyl-p-benzoquinone. Examples of the benzoquinone compounds include p-benzoquinone.

[0113] The mixing ratio of the polymerization inhibitor is, for example, 0.01 part by mass or more and, for example, 0.1 part by mass or less, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low shrinkage agent.

[0114] As described above, if necessary, after mixing the curing agent and additives, a filler can also be mixed, if necessary.

[0115] Examples of the filler include inorganic fillers. Examples of the inorganic filler include oxides, hydroxides (e.g., aluminum hydroxide), carbonates, sulfates, silica, glass powder, hollow fillers, silicates, fluorides, phosphates, and clay minerals. A preferred filler is carbonate (preferably calcium carbonate).

[0116] The fillers can be used alone or in combination of two or more.

[0117] The blending ratio of the filler relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low shrinkage agent is, for example, 5 parts by mass or more, preferably 50 parts by mass or more, preferably 80 parts by mass or more, more preferably 100 parts by mass or more, even more preferably 150 parts by mass or more, and for example, 300 parts by mass or less, preferably 210 parts by mass or less.

[0118] In particular, when the filler is aluminum hydroxide or calcium carbonate, the blending ratio of the filler is, for example, 80 parts by mass or more, preferably 100 parts by mass or more, more preferably 150 parts by mass or more, and for example, 210 parts by mass or less, per 100 parts by mass of the total amount of the radical polymerizable resin and the low-profile agent.

[0119] In particular, when the hollow filler is a hollow filler, the amount is, for example, 5 parts by mass or more and, for example, 60 parts by mass or less.

[0120] A molding material can be prepared by blending reinforcing fibers with such a radically curable resin composition, and a molded article can be obtained from such a molding material by a known method.

[0121] Examples of reinforcing fibers include inorganic fibers, organic fibers, and natural fibers. Examples of inorganic fibers include glass fibers, carbon fibers, metal fibers, and ceramic fibers. Examples of organic fibers include polyvinyl alcohol fibers, polyester fibers, polyamide fibers, fluororesin fibers, and phenolic fibers. Examples of natural fibers include hemp and kenaf.

[0122] As the reinforcing fiber, preferably, inorganic fiber is used, and more preferably, carbon fiber or glass fiber is used.

[0123] Examples of the shape of the reinforcing fibers include cloth (e.g., roving cloth), mat (e.g., chopped strand mat, preformable mat, continuous strand mat, and surfacing mat), strand, roving, nonwoven fabric, and paper.

[0124] The length of the reinforcing fibers is not particularly limited and is, for example, 1.5 mm or more, and from the viewpoint of improving strength, preferably 5 mm or more, more preferably 15 mm or more, and for example, 80 mm or less, preferably 40 mm or less.

[0125] The molding material is obtained, for example, as a sheet-like molding material by impregnating reinforcing fibers with the radical curable resin composition.

[0126] The molding material can be prepared by a known method. Specific examples include SMC (sheet molding compound), TMC (thick molding compound), and BMC (bulk molding compound). SMC is preferred.

[0127] The content of the reinforcing fibers relative to the molding material is, for example, 20 mass % or more, and for example, 50 mass % or less, or preferably 40 mass % or less.

[0128] This results in a molding material.

[0129] Next, in order to thicken the molding material so that it can be subjected to heat compression molding (described later), a thickener is mixed therewith, if necessary, and then the molding material is aged.

[0130] Examples of thickeners include alkaline earth metal oxides, alkaline earth metal hydroxides, and polyisocyanate compounds. Examples of alkaline earth metal oxides include magnesium oxide. Examples of alkaline earth metal hydroxides include magnesium hydroxide and calcium hydroxide. Examples of polyisocyanate compounds include diphenylmethane diisocyanate (MDI).

[0131] As the thickener, preferably, an alkaline earth metal oxide is used, and more preferably, magnesium oxide is used.

[0132] The thickeners can be used alone or in combination of two or more.

[0133] The blending ratio of the thickener is, for example, 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and for example, 10 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the total amount of the radical polymerizable resin and the low-profile agent.

[0134] The aging temperature is, for example, 20° C. or higher and, for example, 50° C. or lower. The aging time is, for example, 8 hours or higher and, for example, 120 hours or lower.

[0135] The molding material is then heated and compression molded by a known method.

[0136] The conditions for the heat compression molding are appropriately set depending on the purpose and application. Specifically, the molding temperature is, for example, 100°C or higher, preferably 120°C or higher, and, for example, 200°C or lower, preferably 160°C or lower. The molding pressure is, for example, 1 MPa or higher, preferably 3 MPa or higher, more preferably 5 MPa or higher, and, for example, 30 MPa or lower, preferably 15 MPa or lower.

[0137] This causes the molding material to harden and be molded, resulting in a molded article containing the hardened molding material.

[0138] The molded article has a thickness of, for example, 0.1 mm or more, preferably 1.0 mm or more, and for example, 10 mm or less, preferably 5 mm or less.

[0139] The molded article includes a cured product of the molding material containing the radically curable resin composition, and therefore has excellent productivity while suppressing the amount of aldehyde emitted during curing.

[0140] Such molded articles can be used in a wide range of applications, such as building materials, housings, casting materials, machine parts, electronic and electrical parts, and various components for vehicles, ships, aircraft, etc.

[0141] <Action and effect> The method for producing a radically curable resin composition includes a first step of dissolving an aldehyde scavenger in a low-profile agent to obtain a mixture, and a second step of mixing the mixture with a radically polymerizable resin. That is, in this method, the aldehyde scavenger is first dissolved in a low-profile agent to obtain a mixture, and the mixture is then mixed with a radically polymerizable resin. Therefore, it is possible to produce a radically curable resin composition with excellent productivity while suppressing the amount of aldehyde emitted during curing.

[0142] For example, in Patent Document 1, an unsaturated polyester resin composition, a low-profile agent, and a formaldehyde scavenger are mixed together to produce a resin composition. If the formaldehyde scavenger is mixed directly, the specific surface area decreases, and the formaldehyde suppression effect decreases.

[0143] On the other hand, once the aldehyde scavenger is dissolved, the size (particle diameter) of the aldehyde scavenger that precipitates thereafter can be reduced, which increases the specific surface area and, as a result, improves the aldehyde suppression effect.

[0144] Therefore, in this method, ethylene urea (aldehyde scavenger) is dissolved in the low-profile agent in the first step, which makes it possible to suppress the amount of aldehyde emitted during curing.

[0145] On the other hand, dissolving an aldehyde scavenger in a radical polymerizable resin has also been considered, but dissolving an aldehyde scavenger in a radical polymerizable resin reduces the viscosity due to reaction and / or coordination between the radical polymerizable resin and the aldehyde scavenger (particularly when the radical polymerizable resin is an unsaturated polyester resin, reaction between free carboxyl groups in the radical polymerizable resin and the aldehyde scavenger (e.g., ethylene urea)). This reduced viscosity makes the molding material sticky, making it difficult to peel the molding material from a carrier film that is attached to the molding material during production, for example. This, in turn, reduces productivity.

[0146] Therefore, in this method, in the first step, an aldehyde scavenger is dissolved in the low-profile agent rather than in the radical polymerizable resin, which improves productivity and reduces the amount of aldehyde emitted during curing. [Example]

[0147] Specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the above "Description of the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass.

[0148] <Ingredient details> Details of the active ingredients used in the following examples and comparative examples are shown below. Unsaturated polyester resin: unsaturated polyester resin of Synthesis Example 1, styrene content 40% by mass Saturated polyester resin: low shrinkage agent, saturated polyester resin of Synthesis Example 2, styrene content 40% by mass Styrene-butadiene block copolymer elastomer solution: low-profile agent, trade name "Kraton (registered trademark) G1701" (manufactured by Kraton Polymers), styrene content 70% by mass Polyvinyl acetate solution: shrinkage reducing agent, number average molecular weight 30,000, styrene content 60% by mass Polystyrene solution: shrinkage reducing agent, number average molecular weight 110,000, styrene content 65% by mass Polymethyl methacrylate solution: shrinkage reducing agent, number average molecular weight 60,000, styrene content 70% by mass TAIC: t-amylperoxyisopropyl carbonate, hardener TBPB: t-butyl peroxybenzoate, hardener

[0149] <Preparation of Unsaturated Polyester Resin> Synthesis Example 1 A flask equipped with a thermometer, nitrogen gas inlet tube, reflux condenser, and stirrer was charged with 10.0 mol of maleic anhydride, 6.5 mol of propylene glycol, and 4.0 mol of neopentyl glycol. Subsequently, a polycondensation reaction was carried out at 200-210°C with stirring under a nitrogen gas atmosphere. This resulted in an unsaturated polyester with an acid value of 26.5 mgKOH / g. The acid value was measured in accordance with JIS K6901 (2008). Next, 0.01 parts by mass of hydroquinone as a polymerization inhibitor and 66.7 parts by mass of styrene were added to 100 parts by mass of this unsaturated polyester, and the mixture was uniformly mixed. This resulted in an unsaturated polyester resin (styrene content: 40% by mass).

[0150] <Preparation of saturated polyester resin> Synthesis Example 2 A flask equipped with a thermometer, nitrogen gas inlet tube, reflux condenser, and stirrer was charged with 4.0 mol of isophthalic acid and 10.5 mol of neopentyl glycol. The mixture was then subjected to a polycondensation reaction at 200-210°C while stirring under a nitrogen gas atmosphere. The reaction mixture was then cooled to 150°C when the acid value of the reaction product reached 10 mgKOH / g. Next, 6.0 mol of adipic acid was added, and the reaction was again carried out at 210-220°C. This resulted in a saturated polyester with an acid value of 9.5 mgKOH / g. To 100 parts by mass of this saturated polyester, 0.01 parts by mass of hydroquinone as a polymerization inhibitor and 66.7 parts by mass of styrene were added and mixed uniformly. This resulted in a saturated polyester resin (styrene content: 40% by mass).

[0151] <Production of radically curable resin composition, molding material, and molded article> Examples 1 to 8 [1st step] Ethylene urea was added to the low profile additive according to the formulations shown in Tables 1 and 2, and the mixture was heated to 70-80°C and stirred for 1 hour. This allowed the ethylene urea to dissolve in the low profile additive, yielding a mixture. The resulting mixture was then cooled to room temperature (25°C).

[0152] [Second process] According to the formulations shown in Tables 1 and 2, the mixture, the radical polymerizable resin, the curing agent, and the polymerization inhibitor were mixed together, and then the filler was mixed therewith.

[0153] In this way, a radically curable resin composition was produced.

[0154] As described above, ethylene urea was dissolved in the low profile agent in Examples 1 to 8. In Tables 1 and 2, the dissolution method column indicates "dissolved in low profile agent."

[0155] Thereafter, a thickener was blended into the radical curable resin composition, and then reinforcing fibers were added and thoroughly impregnated. Thereafter, the mixture was aged at 40°C for 2 days to obtain a molding material.

[0156] Two sheets of molding material measuring 210mm long x 210mm wide were cut out from the molding material, stacked together, and placed in the center of a positive mold for SMC molding (a flat plate measuring 300mm long x 300mm wide). They were heated and pressurized for 4 minutes at molding temperatures (upper mold / lower mold) of 145°C / 130°C and a molding pressure of 10MPa. This resulted in a molded product 2mm thick.

[0157] Comparative Examples 1 and 2 Ethylene urea was added to the radical polymerizable resin according to the formulation shown in Table 2, and the mixture was heated to 70-80°C and stirred for 1 hour. This allowed the ethylene urea to dissolve in the radical polymerizable resin, yielding a mixture. The resulting mixture was then cooled to room temperature (25°C).

[0158] Next, the mixture was mixed with a low-profile agent, a curing agent, and a polymerization inhibitor, and then the filler was mixed.

[0159] In this way, a radically curable resin composition was produced.

[0160] As described above, ethylene urea was dissolved in a radical polymerizable resin in Comparative Examples 1 and 2. The dissolution method column in Table 2 indicates "dissolved in a radical polymerizable resin."

[0161] Next, molding materials and molded articles were produced based on the same procedures as in Example 1. In Comparative Example 2, the carrier film could not be peeled off from the cut molding material, and therefore molding was not possible.

[0162] Comparative Example 3 The radical polymerizable resin, the low shrinkage agent, the ethylene urea, the curing agent, and the polymerization inhibitor were mixed together, and then the filler was mixed.

[0163] In this way, a radically curable resin composition was produced.

[0164] As described above, the radical polymerizable resin, the low-profile agent, and the ethylene urea were mixed all at once in Comparative Example 3. In the dissolution method column of Table 2, this is indicated as "mixing all at once."

[0165] Comparative Example 4 The radical polymerizable resin, ethylene urea, curing agent, and polymerization inhibitor were mixed together, and then the filler was mixed.

[0166] In this way, a radically curable resin composition was produced.

[0167] As described above, no low profile agent was blended in Comparative Example 4. In Table 2, the dissolution method column shows "not added."

[0168] Next, molding materials and molded articles were produced according to the same procedures as in Example 1.

[0169] <Evaluation> [Productivity] Productivity was evaluated based on the following criteria, and the results are shown in Tables 1 and 2. (standard) ◯: The carrier film could be easily peeled off from the cut molding material. △: When the carrier film was peeled off from the cut molding material, a small amount of molding material remained on the film. In addition, the molding material was slightly sticky. ▲: When the carrier film was peeled off from the cut molding material, some molding material remained on the film. The molding material was also sticky. ×: The carrier film could not be peeled off from the cut molding material. Also, a considerable amount of molding material remained on the carrier film. Also, the molding material was sticky and could not be molded.

[0170] [Mold shrinkage rate] The molded articles of each Example and Comparative Example were measured for mold shrinkage in accordance with JIS K6911 (1995), except that the dimensions of the mold and the molded articles used for molding were used. The results are shown in Tables 1 and 2.

[0171] [exterior] Productivity was evaluated based on the following criteria, and the results are shown in Tables 1 and 2. (standard) ◯: No yellowing or swelling occurred on the surface of the molded product (hot side of the mold). △: Yellowing occurred on the surface of the molded product (hot side of the mold). ×: Sink marks, yellowing, irregularities, blistering, etc. occurred on the surface of the molded product (hot side of the mold).

[0172] [VOC measurement] VOC (volatile organic compounds) measurements were conducted in accordance with JASO (Society of Automotive Engineers of Japan) standard M902.

[0173] Specifically, the molded articles of each Example and Comparative Example were cut into a predetermined size (100 mm length x 100 mm width x 2 mm thickness) 24 hours after production to produce test pieces.

[0174] The back side (low-temperature molding side) of each test piece was attached with double-sided tape (commercially available low-VOC type (solvent-free)) so that the back side (dull side) of the aluminum foil faced outwards.

[0175] The results of the VOC measurements are shown in Tables 1 and 2. The amounts of aldehyde and VOC emissions were also evaluated based on the following criteria. The results are shown in Tables 1 and 2.

[0176] [Table 1]

[0177] [Table 2]

Claims

1. a first step of dissolving an aldehyde scavenger in a low-profile agent to obtain a mixture; a second step of mixing the mixture with a radical polymerizable resin, the low profile agent comprises a low profile polymer; The method for producing a radical curable resin composition, wherein the low-shrinkage polymer comprises at least one selected from the group consisting of polyethylene, polystyrene, a styrene-based thermoplastic elastomer, crosslinked polystyrene, a polyvinyl acetate-polystyrene block copolymer, polyvinyl acetate, polymethyl methacrylate, and saturated polyester.

2. The method for producing a radical-curable resin composition according to claim 1 , wherein the aldehyde scavenger is a urea compound.

3. The method for producing a radically curable resin composition according to claim 2, wherein the urea compound is ethylene urea.

4. 4. The method for producing a radical curable resin composition according to claim 1, wherein a mixing ratio of the aldehyde scavenger is 1 part by mass or more and 3 parts by mass or less with respect to 100 parts by mass of a total amount of the radical polymerizable resin and the low shrinkage agent.

5. In the second step, a curing agent is further mixed, The method for producing a radically curable resin composition according to any one of claims 1 to 4, wherein the curing agent is t-amylperoxyisopropyl carbonate.

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