Molding material and molded article

Abstract

This molding material contains an unsaturated polyester resin composition and natural plant fibers. The unsaturated polyester resin composition includes: a thermosetting resin containing an unsaturated polyester; and a resin component containing a polymerizable monomer. The glass transition temperature when curing a mixture of the thermosetting resin and the polymerizable monomer is 0°C to 60°C inclusive. The content ratio of the polymerizable monomer is 40 mass% or less with respect to the total amount of the thermosetting resin and the polymerizable monomer.

Description

Molding materials and molded products

[0001] The present invention relates to molding materials and molded articles, and more particularly to molding materials and molded articles including cured products of the molding material.

[0002] Conventionally, molded articles made from molding materials containing unsaturated polyester resin compositions (particularly sheet molding compounds (SMC), bulk molding compounds (BMC), and thick molding compounds (TMC)) have been used in a wide range of fields due to their excellent mechanical properties, water resistance, electrical insulation, and corrosion resistance.

[0003] As such a molding material, a molding material comprising an unsaturated polyester resin (an unsaturated polyester resin containing unsaturated polyester and styrene), a polyvinyl acetate resin (a polyvinyl acetate resin containing polyvinyl acetate and styrene), aluminum hydroxide particles, and chopped glass fiber has been proposed (see, for example, Example 1 of Patent Document 1 below). In Example 1 of Patent Document 1, the content of styrene (polymerizable monomer) is 57.9% by mass relative to the total amount of styrene (polymerizable monomer) and unsaturated polyester resin (thermosetting resin).

[0004] Japanese Patent Publication No. 2004-161813

[0005] On the other hand, depending on the purpose and application, flexibility is required for molded products. Furthermore, molded products may be used in combination with other components. In such cases, it is necessary to prevent damage to other components even when they come into contact.

[0006] The present invention provides a molding material for manufacturing a molded article that improves flexibility and suppresses damage to other components even when in contact with them, and a molded article including a cured product of the molding material.

[0007] The present invention [1] is a molding material comprising an unsaturated polyester resin composition and plant natural fibers, wherein the unsaturated polyester resin composition comprises a thermosetting resin containing an unsaturated polyester and a resin component containing a polymerizable monomer, the glass transition temperature when the mixture of the thermosetting resin and the polymerizable monomer is cured is 0°C or higher and 60°C or lower, and the content ratio of the polymerizable monomer is 40.0% by mass or less with respect to the total amount of the thermosetting resin and the polymerizable monomer.

[0008] The present invention [2] comprises the molding material described in [1] above, wherein the unsaturated polyester resin composition contains aluminum hydroxide.

[0009] The present invention [3] comprises the molding material described in [1] or [2] above, wherein the unsaturated polyester resin composition contains a flame retardant.

[0010] The present invention [4] includes a molding material according to any one of the above [1] to [3], wherein the plant natural fiber is a plant natural fiber that has been treated to be flame-retardant.

[0011] The present invention [5] includes a molded article comprising a cured product of the molding material described in any one of the above items [1] to [4].

[0012] The molding material of the present invention contains natural plant fibers. Therefore, even if it comes into contact with other components, it can suppress damage to those components.

[0013] Furthermore, in this molding material, the glass transition temperature when the mixture of thermosetting resin and polymerizable monomer is cured is between 0°C and 60°C. Also, the content of polymerizable monomer is 40% by mass or less relative to the total amount of thermosetting resin and polymerizable monomer. Therefore, flexibility can be improved.

[0014] The molded article of the present invention includes a cured product of the molding material of the present invention. Therefore, flexibility is improved, and damage to other components can be suppressed even when in contact with other components.

[0015] 1. Molding material: The molding material comprises an unsaturated polyester resin composition and plant-derived natural fibers.

[0016] <Unsaturated polyester resin composition> The unsaturated polyester resin composition contains resin components.

[0017] <Resin Components> The resin components include thermosetting resins and polymerizable monomers.

[0018] [Thermosetting Resins] Thermosetting resins contain an unsaturated polyester resin as an essential component. The unsaturated polyester resin contains an unsaturated polyester and polymerizable monomers (described later). In other words, thermosetting resins contain an unsaturated polyester. To put it another way, an unsaturated polyester resin is a resin composition containing an unsaturated polyester and polymerizable monomers (described later).

[0019] Unsaturated polyesters are obtained by the reaction of polybasic acids with polyhydric alcohols.

[0020] Polybasic acids include polybasic acids having an ethylenically unsaturated double bond as an essential component (hereinafter referred to as ethylenically unsaturated bond-containing polybasic acids) and polybasic acids not having an ethylenically unsaturated double bond as an optional component (hereinafter referred to as ethylenically unsaturated bond-free polybasic acids).

[0021] Examples of polybasic acids containing ethylenically unsaturated bonds include ethylenically unsaturated aliphatic dibasic acids and their anhydrides, halides of ethylenically unsaturated aliphatic dibasic acids, and alkyl esters of ethylenically unsaturated aliphatic dibasic acids.

[0022] Examples of ethylenically unsaturated aliphatic dibasic acids include maleic acid, fumaric acid, itaconic acid, and dihydromuconic acid. Polybasic acids containing ethylenically unsaturated bonds include, for example, acid anhydrides derived from the above-mentioned ethylenically unsaturated aliphatic dibasic acids. An example of an acid anhydride derived from ethylenically unsaturated aliphatic dibasic acids is maleic anhydride.

[0023] Preferably, the polybasic acid containing ethylenically unsaturated bonds is maleic acid (preferably infinitely maleic acid) or fumaric acid. More preferably, the polybasic acid containing ethylenically unsaturated bonds is fumaric acid.

[0024] Examples of polybasic acids that do not contain 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.

[0025] Examples of saturated aliphatic polybasic acids include saturated aliphatic dibasic acids.

[0026] Examples of saturated aliphatic dibasic acids include saturated aliphatic dibasic acids having 2 to 7 carbon atoms, and saturated aliphatic dibasic acids having 8 or more carbon atoms.

[0027] Examples of saturated aliphatic dibasic acids having 2 to 7 carbon atoms include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 3,3-dimethylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, adipic acid, and pimelic acid. Adipic acid is preferably given as a saturated aliphatic dibasic acid having 2 to 7 carbon atoms.

[0028] Examples of saturated aliphatic dibasic acids having 8 or more carbon atoms include linear saturated aliphatic dibasic acids having 8 or more carbon atoms. Examples of linear saturated aliphatic dibasic acids having 8 or more carbon atoms include suberic acid, azelaic acid, and sebacic acid. Preferably, sebacic acid is given as a linear saturated aliphatic dibasic acid having 8 or more carbon atoms.

[0029] Furthermore, saturated aliphatic polybasic acids include acid anhydrides derived from the saturated aliphatic dibasic acids mentioned above. Examples of acid anhydrides derived from saturated aliphatic dibasic acids include oxalic anhydride and succinic anhydride.

[0030] Examples of saturated alicyclic polybasic acids include saturated alicyclic dibasic acids.

[0031] 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. An example of an acid anhydride derived from saturated alicyclic dibasic acids is het acid anhydride.

[0032] Examples of aromatic polybasic acids include aromatic dibasic acids.

[0033] Examples of aromatic dibasic acids include phthalic acids (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. An example of an acid anhydride derived from an aromatic dibasic acid is phthalic anhydride. Preferably, isophthalic acid is used as the aromatic dibasic acid.

[0034] Examples of ethylenically unsaturated polybasic acids that do not contain ethylenically unsaturated bonds include saturated aliphatic polybasic acids and aromatic dibasic acids.

[0035] Polybasic acids can be used alone or in combination of two or more types.

[0036] When the polybasic acid includes polybasic acids containing ethylenically unsaturated bonds and polybasic acids not containing ethylenically unsaturated bonds, from the viewpoint of improving flexibility and suppressing damage to other components even when in contact with other components, the content of polybasic acids containing ethylenically unsaturated bonds is, for example, 10 mol% to 30 mol%, preferably 15 mol% to 20 mol%, per 100 moles of total polybasic acids. The content of polybasic acids not containing ethylenically unsaturated bonds is, for example, 70 mol% to 90 mol%, preferably 80 mol% to 85 mol%.

[0037] The polybasic acid preferably contains a saturated aliphatic dibasic acid having 8 or more carbon atoms (preferably a linear saturated aliphatic dibasic acid having 8 or more carbon atoms). When the polybasic acid contains a saturated aliphatic dibasic acid having 8 or more carbon atoms (preferably a linear saturated aliphatic dibasic acid having 8 or more carbon atoms), water resistance can be improved.

[0038] From the viewpoint of water resistance, the content of the saturated aliphatic dibasic acid having 8 or more carbon atoms is 40 mol% to 70 mol%, preferably 50 mol% to 65 mol%, relative to 100 mol of the total polybasic acid.

[0039] The polybasic acid preferably consists of an ethylenically unsaturated bond-containing polybasic acid and an ethylenically unsaturated bond-free polybasic acid.

[0040] Examples of the polyhydric alcohol include dihydric alcohols and trihydric alcohols.

[0041] Examples of the dihydric alcohol include aliphatic diols, alicyclic diols, and aromatic diols.

[0042] Examples of the aliphatic diol include alkane diols and ether diols.

[0043] Examples of the alkane diol include alkane diols having 2 to 10 carbon atoms. Examples of the alkane diol having 2 to 10 carbon atoms include ethylene glycol, propylene glycol (1,2- or 1,3-propanediol, or a mixture thereof), butylene glycol (1,2- or 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. Propylene glycol is preferable as the alkane diol.

[0044] Examples of ether diols include diethylene glycol, triethylene glycol, and dipropylene glycol. Diethylene glycol is preferred as the ether diol.

[0045] Examples of alicyclic diols include cyclohexanediol (1,2- or 1,3- or 1,4-cyclohexanediol or mixtures thereof), cyclohexanedimethanol (1,2- or 1,3- or 1,4-cyclohexanedimethanol or mixtures thereof), cyclohexanediethanol (1,2- or 1,3- or 1,4-cyclohexanediethanol or mixtures thereof), and hydrogenated bisphenol A.

[0046] Examples of aromatic diols include ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A.

[0047] Examples of trihydric alcohols include glycerin, trimethylolpropane, and triisopropanolamine.

[0048] Preferably, dihydric alcohols are used as polyhydric alcohols. More preferably, aliphatic diols are used as polyhydric alcohols. Even more preferably, alkanediols are used as polyhydric alcohols.

[0049] Polyhydric alcohols can be used alone or in combination of two or more types.

[0050] Unsaturated polyesters are prepared by reacting a polybasic acid with a polyhydric alcohol.

[0051] The equivalent ratio of the polyhydric alcohol to the polybasic acid (hydroxyl group of the polyhydric alcohol / carboxyl group of the polybasic acid) is, for example, 0.9 to 1.2, preferably 0.95 to 1.1.

[0052] The reaction temperature is, for example, 150°C to 250°C, preferably 190°C to 230°C.

[0053] In addition, known solvents and known reaction catalysts may be added to the above reaction as needed.

[0054] This process prepares unsaturated polyester.

[0055] The acid value of unsaturated polyester (measurement method: in accordance with JIS K6901 (2008)) is, for example, 5 mg KOH / g to 40 mg KOH / g, preferably 10 mg KOH / g to 30 mg KOH / g, and more preferably 20 mg KOH / g to 30 mg KOH / g.

[0056] The weight-average molecular weight of the unsaturated polyester is, for example, 2,000 to 25,000, preferably 4,000 to 20,000.

[0057] Note that the weight-average molecular weight is the weight-average molecular weight converted to polystyrene using GPC (gel permeation chromatography).

[0058] Unsaturated polyesters can be used alone or in combination of two or more types.

[0059] The thermosetting resin may also contain, as an optional component, a vinyl ester resin (a vinyl ester resin containing a vinyl ester and a polymerizable monomer (described later)). Preferably, the thermosetting resin does not contain a vinyl ester resin and consists of an unsaturated polyester resin.

[0060] Thermosetting resins can be used alone or in combination of two or more types.

[0061] The content of unsaturated polyester is, for example, 55.0% to 90.0% by mass, preferably 60.0% to 85.0% by mass, more preferably 65.0% to 80.0% by mass, and even more preferably 70.0% to 78.0% by mass, relative to the resin component.

[0062] [Polymerizable monomers] Examples of polymerizable monomers include styrene monomers and (meth)acrylic acid ester monomers.

[0063] Examples of styrene-based monomers include styrene, vinyltoluene, t-butylstyrene, and chlorostyrene.

[0064] Examples of (meth)acrylic acid ester monomers include alkyl (meth)acrylates, allyl (meth)acrylates, ring-structure-containing (meth)acrylic acid esters, hydroxyalkyl (meth)acrylates, alkoxyalkyl (meth)acrylates, aminoalkyl (meth)acrylates, fluoroalkyl (meth)acrylates, and polyfunctional (meth)acrylic acid esters. Examples of alkyl (meth)acrylates 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 allyl (meth)acrylates include allyl (meth)acrylate. Examples of ring-structure-containing (meth)acrylate 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)acrylate esters include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate. Examples of alkoxyalkyl (meth)acrylate esters include 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate. Examples of aminoalkyl (meth)acrylate esters include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and their chloride salts. Examples of (meth)acrylate fluoroalkyl esters include (meth)acrylate trifluoroethyl and (meth)acrylate heptadecafluorodecyl.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. Preferably, polyfunctional (meth)acrylic acid ester monomers are used. More preferably, trimethylolpropane tri(meth)acrylate is used as a (meth)acrylic acid ester monomer. Even more preferably, trimethylolpropane tri(meth)acrylate is used as a (meth)acrylic acid ester monomer.

[0065] Preferably, polymerizable monomers include styrene monomers. More preferably, polymerizable monomers include styrene.

[0066] Polymerizable monomers can be used individually or in combination of two or more types.

[0067] The content of polymerizable monomers is, for example, 15.0% to 40.0% by mass, preferably 20.0% to 35.0% by mass, and more preferably 22.0% to 30.0% by mass, relative to the resin component.

[0068] The content of polymerizable monomers is 40.0% by mass or less, preferably 35.0% by mass or less, more preferably 30.0% by mass or less, even more preferably 28.0% by mass or less, or, for example, 5.0% by mass or more, preferably 10.0% by mass or more, more preferably 15.0% by mass or more, even more preferably 18.0% by mass or more, particularly preferably 20.0% by mass or more, and even more preferably 22.0% by mass or more, based on the total amount of thermosetting resin and polymerizable monomers.

[0069] If the ratio of polymerizable monomers to the total amount of thermosetting resin and polymerizable monomers is below the above upper limit, flexibility can be improved.

[0070] On the other hand, if the ratio of polymerizable monomers to the total amount of thermosetting resin and polymerizable monomers exceeds the above upper limit, flexibility decreases. In addition, the amount of remaining polymerizable monomers increases, leading to an increased environmental burden.

[0071] [Thermoplastic resin] The resin component may include a thermoplastic resin if necessary.

[0072] Examples of thermoplastic resins include polyethylene, polystyrene, styrene-based thermoplastic elastomers, crosslinked polystyrene, polyvinyl acetate-polystyrene block copolymer, polyvinyl acetate, polymethyl methacrylate, and saturated polyester resins.

[0073] Thermoplastic resins can be used alone or in combination of two or more types.

[0074] Furthermore, a polymerizable monomer solution of a thermoplastic resin can also be prepared by dissolving the thermoplastic resin in the polymerizable monomer.

[0075] In a polymerizable monomer solution of a thermoplastic resin, the solid content concentration of the thermoplastic resin is, for example, 10% to 70% by mass, preferably 20% to 40% by mass.

[0076] Thermoplastic resins can be used alone or in combination of two or more types.

[0077] The content of thermoplastic resin is, for example, 15% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and more preferably 0% by mass, relative to the resin component. In other words, more preferably, the resin component does not contain thermoplastic resin.

[0078] If the content of thermoplastic resin is below the above upper limit, flame retardancy can be improved.

[0079] <Aluminum Hydroxide> The unsaturated polyester resin composition may contain aluminum hydroxide as needed.

[0080] Aluminum hydroxide imparts flame retardancy.

[0081] The average particle size of aluminum hydroxide is, for example, 1 μm or more, and for example, 50 μm or less, preferably 25 μm or less.

[0082] The average particle size of aluminum hydroxide can be determined by creating a particle size distribution curve using a laser diffraction / scattering particle size distribution analyzer and calculating the particle size equivalent to 50% by mass.

[0083] The aluminum hydroxide content is, for example, 50 to 500 parts by mass, preferably 100 to 450 parts by mass, and more preferably 110 to 300 parts by mass, per 100 parts by mass of the resin component. In particular, when the molding material is SMC, the aluminum hydroxide content is, for example, 110 to 300 parts by mass, per 100 parts by mass of the resin component. In particular, when the molding material is BMC, the aluminum hydroxide content is, for example, 250 to 400 parts by mass, per 100 parts by mass of the resin component.

[0084] More specifically, the aluminum hydroxide content is, for example, 50 parts by mass or more, preferably 100 parts by mass or more, and more preferably 110 parts by mass or more, from the viewpoint of flame retardancy, and from the viewpoint of suppressing an excessive increase in the viscosity of the unsaturated polyester resin composition, it is, for example, 500 parts by mass or less, preferably 450 parts by mass or less, and more preferably 300 parts by mass or less.

[0085] <Additives> The unsaturated polyester resin composition may contain additives as needed, to the extent that it does not impair the effects of the present invention.

[0086] Examples of additives include fillers, flame retardants, curing agents, mold release agents, polymerization inhibitors, thickeners, colorants, wetting and dispersing agents, patterning agents, antibacterial agents, hydrophilic agents, photocatalysts, UV absorbers, UV stabilizers, separation inhibitors, silane coupling agents, antistatic agents, thixotropic agents, thixotropic stabilizers, and polymerization accelerators. Additives can be used individually or in combination of two or more.

[0087] [Fillers] Fillers are fillers other than aluminum hydroxide, and examples include inorganic fillers. Examples of inorganic fillers include oxides (e.g., alumina, titanium oxide), hydroxides (e.g., magnesium hydroxide, excluding aluminum hydroxide), carbonates (e.g., calcium carbonate), sulfates (e.g., barium sulfate), silica (e.g., crystalline silica, fused silica, fumed silica, dry silica (aerosil)), hollow fillers, silicates (e.g., silica sand, diatomaceous earth, glass powder, glass balloons, mica, clay, kaolin, talc), fluorides (e.g., fluorite), phosphates (e.g., calcium phosphate), metal powders, ceramics, milled fibers, and clay minerals (e.g., smectite). Preferably, carbonates are used as fillers. More preferably, calcium carbonate is used as a filler.

[0088] The fillers can be used individually or in combination of two or more types.

[0089] The proportion of the filler is, for example, 30 to 200 parts by mass, preferably 50 to 150 parts by mass, per 100 parts by mass of the resin component.

[0090] [Flame retardants] Examples of flame retardants (excluding aluminum hydroxide) include phosphorus-containing flame retardants, nitrogen-containing flame retardants, expanded graphite, halogen-based flame retardants, antimony trioxide, zinc stannate, and zinc borate. Preferably, flame retardants include phosphorus-containing flame retardants, nitrogen-containing flame retardants, phosphorus and nitrogen-containing flame retardants, and expanded graphite.

[0091] Phosphorus-containing flame retardants contain phosphorus but do not contain nitrogen. Examples of phosphorus-containing flame retardants include red phosphorus, phosphate esters, polyphosphates, and phosphinate metal salts.

[0092] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, and tricresyl phosphate.

[0093] Examples of polyphosphates include aluminum polyphosphate.

[0094] Examples of phosphinate metal salts include aluminum trisdiethylphosphinate and aluminum trismethylethylphosphinate.

[0095] Furthermore, commercially available phosphorus-containing flame retardants can be used. Specifically, the OP series (specifically Exolit OP1230 (aluminum trisdiethylphosphinate), manufactured by Clariant Chemicals) is an example.

[0096] Preferably, phosphorus-containing flame retardants include metal phosphinate salts, and more preferably, aluminum trisdiethylphosphinate.

[0097] Nitrogen-containing flame retardants contain nitrogen but do not contain phosphorus. Examples of nitrogen-containing flame retardants include triazine compounds.

[0098] Triazine compounds are compounds that have a triazine skeleton. Examples of triazine compounds include melamine, acetogyanamine, benzoguanamine, melon, melam, succinoguanamine, ethylenedimelamine, triguanamine, and melamine cyanurate.

[0099] Furthermore, commercially available nitrogen-containing flame retardants can be used. Specifically, MC-4000 (melamine cyanurate, manufactured by Nissan Chemical Corporation) is one example.

[0100] Preferably, a triazine compound is used as a nitrogen-containing flame retardant. More preferably, melamine cyanurate is used as a nitrogen-containing flame retardant.

[0101] Examples of phosphorus and nitrogen-containing flame retardants include ammonium polyphosphate and melamine polyphosphate.

[0102] Expanded graphite is a graphite intercalation compound produced by inserting sulfuric acid or other substances between the layers of flaky natural graphite. Expanded graphite expands at temperatures of approximately 150 to 300°C as the intercalations expand.

[0103] The average particle size of the expanded graphite is 150 μm or less, preferably 100 μm or less, and for example, 10 μm or more, preferably 50 μm or more.

[0104] The average particle size of expanded graphite can be determined by observing it with an optical microscope, measuring the maximum diameter (major axis) and the particle size in the direction perpendicular to the maximum diameter (minor axis) for any 50 expanded graphite samples, and calculating the average value of the major and minor axes.

[0105] Commercially available expanded graphite can also be used. Specifically, product number 9510045 from Ito Graphite Industry Co., Ltd. is one example.

[0106] Flame retardants can be used alone or in combination of two or more types.

[0107] The flame retardant content is, for example, 1 to 40 parts by mass per 100 parts by mass of the resin component.

[0108] [Curing agent] Examples of curing agents include peroxides. Examples of peroxides include benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-amyl peroxyisopropyl carbonate, t-hexyl peroxyisopropyl monocarbonate, 1,1-bis(t-butyl peroxy)cyclohexane, t-butyl peroxy-2-ethylhexanoate, amyl peroxy-2-ethylhexanoate, 2-ethylhexyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, and t-hexyl peroxyacetate. Preferably, t-butyl peroxyisopropyl carbonate is used as the curing agent.

[0109] The hardening agent can be used alone or in combination of two or more types.

[0110] The proportion of the curing agent is, for example, 0.1 to 5 parts by mass, preferably 1 to 3 parts by mass, per 100 parts by mass of the resin component.

[0111] [Release Agents] Examples of release agents include fatty acids, fatty acid metal salts, liquid waxes, fluoropolymers, and silicone polymers. Examples of fatty acids include stearic acid and lauric acid. Examples of fatty acid metal salts include zinc stearate and calcium stearate.

[0112] Preferably, the release agent is a fatty acid metal salt, and more preferably, zinc stearate.

[0113] Release agents can be used alone or in combination of two or more types.

[0114] The proportion of the release agent is, for example, 1 to 10 parts by mass, preferably 3 to 8 parts by mass, per 100 parts by mass of the resin component.

[0115] [Polymerization inhibitors] Polymerization inhibitors adjust the pot life and curing reaction.

[0116] Examples of polymerization inhibitors include hydroquinone compounds, benzoquinone compounds, catechol compounds, phenol compounds, and N-oxyl compounds.

[0117] Preferred polymerization inhibitors include benzoquinone compounds, hydroquinone compounds, and N-oxyl compounds.

[0118] An example of a benzoquinone compound is p-benzoquinone.

[0119] Examples of hydroquinone compounds include hydroquinone, methylhydroquinone, and t-butylhydroquinone. Preferably, t-butylhydroquinone is used as the hydroquinone compound.

[0120] More preferably, benzoquinone compounds are used as polymerization inhibitors.

[0121] Polymerization inhibitors can be used alone or in combination of two or more types.

[0122] The polymerization inhibitor content is, for example, 0.01 to 2 parts by mass, preferably 0.02 to 1 part by mass, per 100 parts by mass of the resin component.

[0123] [Thickener] A thickener is added to increase the viscosity of the unsaturated polyester resin composition to a level suitable for heat compression molding. Preferably, the thickener is added before (preferably immediately before) impregnating the unsaturated polyester resin composition with reinforcing fibers (described later).

[0124] Examples of thickeners include alkaline earth metal oxides and alkaline earth metal hydroxides. Examples of alkaline earth metal oxides include magnesium oxide. Examples of alkaline earth metal hydroxides include magnesium hydroxide and calcium hydroxide. Furthermore, isocyanate monomers (e.g., toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI)) and their prepolymers can also be used as thickeners.

[0125] Preferably, alkaline earth metal oxides are used as thickeners. More preferably, magnesium oxide is used as a thickener.

[0126] The proportion of the thickening agent is, for example, 0.1 to 20 parts by mass, preferably 0.1 to 1 part by mass, per 100 parts by mass of the resin component.

[0127] Thickening agents can be used alone or in combination of two or more types.

[0128] <Preparation of Unsaturated Polyester Resin Composition> The unsaturated resin composition is prepared by mixing the resin component with aluminum hydroxide, which is added as needed, and additives, which are added as needed.

[0129] Furthermore, in the above preparation, an unsaturated polyester resin can also be prepared by first dissolving an unsaturated polyester in a polymerizable monomer (preferably styrene) and, if necessary, blending in the above-mentioned additives.

[0130] In the preparation of the unsaturated polyester resin, the content of polymerizable monomer is, for example, 10 to 40 parts by mass, preferably 20 to 35 parts by mass, per 100 parts by mass of unsaturated polyester.

[0131] Furthermore, after preparing the unsaturated polyester resin, polymerizable monomers can also be added when mixing this unsaturated polyester resin with other components (aluminum hydroxide and additives as needed).

[0132] This is used to prepare an unsaturated polyester resin composition.

[0133] Furthermore, in such an unsaturated polyester resin composition, the glass transition temperature when the mixture of the thermosetting resin and polymerizable monomer is cured is 0°C to 60°C, preferably 10°C to 50°C, more preferably 20°C to 40°C, and even more preferably 30°C to 35°C.

[0134] More specifically, the glass transition temperature is 0°C or higher, preferably 10°C or higher, more preferably 20°C or higher, even more preferably 30°C or higher, and 60°C or lower, preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower.

[0135] If the glass transition temperature is above the lower limit, moldability can be improved. On the other hand, if the glass transition temperature is below the lower limit, moldability will decrease.

[0136] Furthermore, if the glass transition temperature is above the lower limit mentioned above, water resistance can also be improved.

[0137] Furthermore, if the glass transition temperature is below the upper limit mentioned above, the flexibility will improve.

[0138] On the other hand, if the glass transition temperature exceeds the upper limit, the flexibility decreases.

[0139] The method for measuring the glass transition temperature will be described in detail in the examples below.

[0140] <Plant Natural Fibers> Examples of plant natural fibers include fibers whose main component is cellulose (50% by mass). Examples of such fibers include seed hair fibers, herbaceous plant fibers (bast fibers), woody plant fibers (bast fibers), leaf vein fibers, monocotyledonous plant fibers, wood fibers, and fruit fibers.

[0141] Examples of seed hair fibers include cotton, kapok, and kapok. Examples of herbaceous fibers (bast fibers) include flax, ramie, hemp, jute, and kenaf. Examples of woody fibers (bast fibers) include paper mulberry, paperbush, gampi, kudzu, mulberry, and elm. Examples of leaf vein fibers include Manila hemp, sisal, banana, and pineapple. Examples of monocotyledonous plant fibers include bamboo, reed, and rice. Examples of wood fibers include coniferous trees and broad-leaved trees. Examples of fruit fibers include palm and betel nut.

[0142] The basis weight of natural plant fibers is, for example, 200 g / m². ２ ~700g / m ２ That is the case.

[0143] Furthermore, from a flame-retardant standpoint, plant-based natural fibers can also be treated to make them flame-retardant. In other words, plant-based natural fibers that have been treated to make them flame-retardant can also be used.

[0144] Flame-retardant treated plant-based natural fibers are fibers that have been treated with a flame-retardant agent to make them flame-retardant.

[0145] Examples of flame retardants include boron-containing flame retardants.

[0146] Boron-containing flame retardants include, for example, boron and borax. The boron content is, for example, 20% to 80% by mass, preferably 30% to 70% by mass, and more preferably 40% to 60% by mass, relative to the boron-containing flame retardant. The borax content is, for example, 20% to 80% by mass, preferably 30% to 70% by mass, and more preferably 40% to 60% by mass, relative to the boron-containing flame retardant.

[0147] Furthermore, the boron-containing flame retardant can also be prepared as an aqueous solution. The solid content concentration of the aqueous solution of the boron-containing flame retardant is, for example, 10% to 30% by mass.

[0148] To flame-retardant plant fibers using a flame retardant, the flame retardant is applied to the plant fibers, and then they are dried.

[0149] The application method is not particularly limited, and examples include spraying an aqueous solution of a boron-containing flame retardant onto natural plant fibers, and immersing natural plant fibers in an aqueous solution of a boron-containing flame retardant and then dewatering them.

[0150] The drying conditions are optimized by temperature, for example, in the range of 15°C to 120°C, and are preferably adjusted so that the residual moisture content is 0.1% or less. The drying time is, for example, 1 hour to 48 hours, preferably 3 hours to 24 hours. The drying temperature is, for example, 15°C to 120°C, preferably 40°C to 80°C. Specifically, the drying conditions selected are 24 hours at 40°C and 3 hours at 120°C.

[0151] This process allows for the production of flame-retardant treated plant-based natural fibers.

[0152] In flame-retardant treated plant natural fibers, the content of the flame retardant is, for example, 5% to 30% by mass, preferably 10% to 20% by mass, relative to the total amount of plant natural fibers and flame retardant.

[0153] As natural plant fibers, herbaceous fibers (bast fibers) are preferred. More preferably, as natural plant fibers, jute is preferred, and even more preferably, flame-retardant treated jute is preferred.

[0154] Furthermore, as a plant-based natural fiber, plant-based natural fiber yarns can also be created as one-dimensional materials by processing individual fibers individually or in bundles. Additionally, by combining plant-based natural fiber yarns, they can be used to create two-dimensional fabrics such as woven or knitted cloths, or they can be directly formed into mats.

[0155] Plant-derived natural fibers can take various forms, such as cloth (e.g., plain weave, twill weave, satin weave, and knit) and mat (e.g., nonwoven fabrics, paper, and felt).

[0156] The fiber length of the plant natural fiber is, for example, 1 mm to 1000 mm, preferably 10 mm to 100 mm.

[0157] The aspect ratio of natural plant fibers is, for example, 100 or more, and for example, 100,000 or less.

[0158] Plant-based natural fibers can be used alone or in combination of two or more types.

[0159] The content of plant natural fibers is, for example, 8% to 50% by mass, preferably 10% to 40% by mass, and more preferably 20% to 30% by mass, relative to the molding material.

[0160] More specifically, the content of plant natural fibers relative to the molding material is, from the viewpoint of strength, for example, 8% by mass or more, preferably 10% by mass or more, and more preferably 20% by mass or more, and from the viewpoint of impregnation, for example, 50% by mass or less, preferably 40% by mass or less, and more preferably 30% by mass or less.

[0161] <Other Reinforcing Fibers> The molding material may include other reinforcing fibers other than plant-based natural fibers, as needed.

[0162] Other reinforcing fibers with low hardness are preferred. Examples of other reinforcing fibers include polyvinyl alcohol-based fibers, polyester-based fibers, polyamide-based fibers, fluororesin-based fibers, and phenol-based fibers.

[0163] Other forms of reinforcing fibers include, for example, cloth (e.g., plain weave, twill weave, satin weave, and knitted yarn), mat (e.g., nonwoven fabric, paper, and felt), and the appropriate form is selected depending on the type of fiber.

[0164] The length of the other reinforcing fibers is not particularly limited, for example, 1.5 mm or more, preferably 5 mm or more, more preferably 20 mm or more, and also, for example, 80 mm or less, preferably 40 mm or less, from the viewpoint of improving strength.

[0165] Other reinforcing fibers can be used alone or in combination of two or more types.

[0166] The content of other reinforcing fibers is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, and most preferably 0% by mass, relative to the molding material. In other words, most preferably, the molding material does not contain other reinforcing fibers.

[0167] <Preparation of Molding Material> To prepare the molding material, plant-derived natural fibers and other reinforcing fibers as needed are blended into an unsaturated polyester resin composition. Specifically, the plant-derived natural fibers and other reinforcing fibers as needed are impregnated with the unsaturated polyester resin composition. A molded article can then be obtained from such a molding material by a known method.

[0168] Known methods can be used to prepare the molding material. Specifically, these include SMC (sheet molding compound), TMC (thick molding compound), and BMC (bulk molding compound). BMC and SMC are preferred.

[0169] This yields a molding material (preferably a sheet-like molding material) comprising an unsaturated polyester resin composition, plant-based natural fibers, and other reinforcing fibers as needed.

[0170] 2. Molded product: The molded product includes a cured product of the above-mentioned molding material.

[0171] To harden the molding material, it must first be aged to increase its viscosity so that it can be subjected to heat compression molding (described later).

[0172] During maturation, the maturation temperature is, for example, 20°C or higher, and for example, 50°C or lower. The maturation time is, for example, 8 hours or more, and for example, 120 hours or less.

[0173] This allows the molding material to maintain its shape.

[0174] Next, the molding material is heat-compressed using a known method.

[0175] The conditions for heat compression molding are set appropriately according to the purpose and application. In heat compression molding, the molding temperature is, for example, 100°C to 200°C. The molding pressure is, for example, 0.1 MPa to 20 MPa, preferably 1 MPa to 15 MPa, and more preferably 5 MPa to 12 MPa.

[0176] This allows the molding material to be shaped and cured, resulting in a molded product.

[0177] Furthermore, examples of molding methods by shape hardening include press molding, injection molding, transfer molding, calendering, pultrusion, resin transfer molding, preform-matched die molding, double belt press molding, and extrusion molding. Preferably, molding methods by shape hardening include press molding, injection molding, double press molding, and calendering. More preferably, molding methods by shape hardening include press molding and injection molding. Even more preferably, molding methods by shape hardening include press molding.

[0178] The thickness of the molded product is, for example, 4.0 mm or less, preferably 3.5 mm or less, more preferably 3.0 mm or less, even more preferably 2.5 mm or less, particularly preferably 2.0 mm or less, most preferably 1.5 mm or less, even more preferably 1.0 mm or less, and also, for example, 0.2 mm or more.

[0179] Furthermore, from the viewpoint of attaching various parts to the molded product, the molded product may have, in addition to the portion having the thickness described above, a thick-walled portion that is relatively thicker and a thin-walled portion that is relatively thinner. Such thick-walled and thin-walled portions may be formed, for example, to constitute ribs or bosses for attaching various parts.

[0180] The molded product includes a cured product of the above-mentioned molding material. Therefore, flexibility is improved, and damage to other components can be suppressed even when the product comes into contact with them.

[0181] Such molded products are suitably used, for example, as fireproof sheets, connector covers for electrical components, gaskets (fixing sealants), brackets (support parts), busbars, harnesses (electrical wires with terminal and connector treatments at the ends to allow connection to other equipment), connector parts, support parts, insulation (insulating and shielding materials), filters, plugs, clips, and sealing materials. In particular, since the molded products can suppress damage to other components even when they come into contact with other components, they can be suitably used even when the molded products rub against other components.

[0182] 3. Effects: In unsaturated polyester resin compositions used as molding materials, the glass transition temperature when a mixture of thermosetting resin and polymerizable monomer is cured is between 0°C and 60°C. Therefore, the cured product of the unsaturated polyester resin composition can be made soft and has excellent flexibility.

[0183] Furthermore, in the unsaturated polyester resin composition, the content of polymerizable monomers is 40% by mass or less relative to the total amount of polymerizable monomers and thermosetting resin. Therefore, molded articles obtained using this unsaturated polyester resin composition have excellent flexibility.

[0184] More specifically, the molding material described in Patent Document 1 comprises an unsaturated polyester resin (an unsaturated polyester resin containing an unsaturated polyester and a polymerizable monomer), a polyvinyl acetate resin (a polyvinyl acetate resin containing a polyvinyl acetate and a polymerizable monomer), aluminum hydroxide particles, and chopped glass fiber, wherein the polymerizable monomer content is 57.9% by mass relative to the total amount of polymerizable monomers and thermosetting resin.

[0185] Polymerizable monomers are solvents for dissolving unsaturated polyesters. Furthermore, during the curing of unsaturated polyester resins, polymerizable monomers are crosslinkable monomers (reactive diluents) that can crosslink with unsaturated polyesters.

[0186] Patent Document 1 describes a mixture of unsaturated polyester and polymerizable monomers in excess. The excess polymerizable monomers do not react with the unsaturated polyester, but instead polymerize with each other to form a cured polymerizable monomer product. Such a cured product reduces flexibility.

[0187] In contrast, in the unsaturated polyester resin composition, the content of polymerizable monomers is 40% by mass or less relative to the total amount of polymerizable monomers and thermosetting resin. Therefore, the amount of cured polymerizable monomers can be reduced. As a result, flexibility can be improved.

[0188] Furthermore, the molding material contains natural plant fibers. Therefore, even if it comes into contact with other components, it can suppress damage to those components.

[0189] More specifically, molded products manufactured from molding materials may be used in combination with other components. In such cases, it is required that the molded products prevent damage to other components even when they come into contact with each other.

[0190] On the other hand, because this molding material contains natural plant fibers, soft natural plant fibers are dispersed on the surface of the molded product manufactured from this material. Therefore, even if the molded product comes into contact with other components, the natural plant fibers can prevent damage to those components.

[0191] The present invention will be described in further detail below with reference to examples. However, the following description represents one embodiment of the present invention, and the present invention is not limited to these descriptions.

[0192] The specific numerical values ​​such as blending ratios (content percentages), physical properties, and parameters used in the following description can be replaced with the corresponding upper limits (values ​​defined as "less than or equal to" or "less than") or lower limits (values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content percentages), physical properties, and parameters described in the "Modes for Carrying Out the Invention" section above. Furthermore, unless otherwise specified in the following description, "parts" and "%" refer to mass.

[0193] <Details of Components> The product names and abbreviations of the components used in each example and each comparative example are described in detail below. Aluminum hydroxide: average particle diameter 8 μm Calcium carbonate: average particle diameter 3 μm Phosphorus-containing flame retardant: phosphinic acid metal salt, product name "Exolit OP1230", manufactured by Clariant Chemicals; nitrogen-containing flame retardant, melamine cyanurate, nitrogen content 49 mass%, product name "MC-4000", manufactured by Nissan Chemical Corporation; expanded graphite: product name "9510045", manufactured by Ito Graphite Industries Co., Ltd.; non-woven jute: basis weight 300 g / m ２ , basis weight 500 g / m ２ , basis weight 600 g / m ２ Woven jute: basis weight 300 g / m ２

[0194] <Production of Unsaturated Polyester Resin> Production Example 1 2400 parts by mass of propylene glycol, 620 parts by mass of fumaric acid, 3830 parts by mass of sebacic acid, and 1200 parts by mass of isophthalic acid were reacted at a reaction temperature of 200°C until the acid value reached 27 mgKOH / g, thereby preparing an unsaturated polyester. Then, 33.4 parts by mass of styrene was mixed with 100 parts by mass of the unsaturated polyester to obtain an unsaturated polyester resin (containing 25.0 mass% of styrene).

[0195] Production Examples 2 to 4 Unsaturated polyester resins were produced according to the same procedure as in Production Example 1, except that the formulation of each component was changed based on Table 1.

[0196] <Production of Flame-Retardant Treated Natural Plant Fibers> Production Example 5 A 20 mass% aqueous solution of a flame retardant treatment agent (boron-containing flame retardant (boron : borax = 1:1)) was spray-applied to woven jute (300 g / m ２ ) at a rate of 225 g / m ２ , followed by drying (24 hours, 40°C). Thereby, a flame-retardant treated natural plant fiber was produced. The content of the flame retardant treatment agent (solid content) relative to the flame-retardant treated natural plant fiber was 45 g / m ２ .

[0197] Production Example 6 Non-woven jute (300 g / m ２) is treated with a 20% by mass aqueous solution of a flame retardant (boron-containing flame retardant (boron:borax = 1:1)) at a rate of 225 g / m². ２ The material was spray-coated in the specified ratio and then dried (24 hours at 40°C). This produced flame-retardant treated natural plant fibers. The flame retardant (solid content) for the flame-retardant treated natural plant fibers was 45 g / m². ２ That was the case.

[0198] Manufacturing Example 7: Nonwoven jute fabric (600g / m²) ２ ) Add a 20% by mass aqueous solution of a flame retardant (boron-containing flame retardant (boron:borax = 1:1)) to 450 g / m² ２ The material was spray-coated in the specified ratio and then dried (24 hours at 40°C). This produced flame-retardant treated natural plant fibers. The flame retardant (solid content) for the flame-retardant treated natural plant fibers was 90 g / m². ２ That was the case.

[0199] <Manufacturing of Molding Materials and Molded Products> Examples 1 to 11, Example 14, Example 15, and Comparative Examples 1 to 3 [Manufacturing of Molding Materials] Based on the information in Tables 2 and 3, each component (unsaturated polyester resin, polymerizable monomer, thermoplastic resin, aluminum hydroxide, filler, flame retardant, curing agent, mold release agent, polymerization inhibitor, viscosity reducer, silane coupling agent) was mixed using a kneader. This yielded an unsaturated polyester resin composition.

[0200] Based on the information in Tables 2 and 3, magnesium oxide was added as a thickener to an unsaturated polyester resin composition, followed by the addition of plant-based natural fibers and / or other reinforcing fibers. A molding material (SMC) was then prepared using a known SMC impregnation machine.

[0201] [Manufacturing of molded products] Molding material was heated and compressed using a 300 mm x 300 mm flat metal sheet to produce molded products of predetermined thicknesses (3 mm, 2 mm, and 1 mm).

[0202] In detail, the molding process was carried out under the following conditions: mold temperature of 140°C for both the product surface and back surface, molding pressure of 10 MPa, and mold holding time of 300 seconds. After that, the molded product was demolded and immediately cooled by sandwiching it between steel plates.

[0203] Examples 12, 13, Comparative Example 4, and Comparative Example 5: Based on the descriptions in Tables 2 and 3, each component was mixed using a kneader. This yielded an unsaturated polyester resin composition.

[0204] Based on the information in Tables 2 and 3, magnesium oxide was added as a thickener to an unsaturated polyester resin composition, followed by the addition of plant-based natural fibers and / or other reinforcing fibers. A molded material (BMC) was then prepared using a known BMC machine. Subsequently, molded articles were manufactured according to the same procedure as in Example 1.

[0205] <Evaluation> (Glass Transition Temperature) To the unsaturated polyester resin of each synthesis example, or a mixture of the thermosetting resin and polymerizable monomer of each example and comparative example, 0.5 parts by mass of 8% cobalt octenoate and 1 part by mass of 55% methyl ethyl ketone peroxide were added and stirred, and allowed to cure at room temperature for 15 hours. After that, the cured product obtained by after-curing at 140°C for 2 hours was measured by DMA under conditions of heating rate of 5°C / min and frequency of 1 Hz, and the peak temperature of the loss tangent was defined as the glass transition temperature. The results are shown in Tables 1 to 3.

[0206] (Shore D Hardness) The Shore D hardness was measured for the molded products of each example and comparative example in accordance with JIS K7215:1986. The results are shown in Tables 2 and 3. The lower the Shore D hardness, the better it can be evaluated that damage to surrounding components can be suppressed even when in contact with other surrounding components when used as a functional component in combination with other components.

[0207] (Flexibility) Molded products of each example and comparative example were cut to 300 mm in length and 100 mm in width. The lengthwise direction was bent by hand. Flexibility was evaluated based on the following criteria. The results are shown in Tables 2 and 3. {Criteria} A: It could be bent until the distance between the ends was 100 mm. B: It could be bent until the distance between the ends was 100 mm, but cracks occurred when held in that position for 30 seconds. C: It cracked or broke before the distance between the ends reached 100 mm.

[0208] (Flame Retardancy) For molded articles (thickness: 3 mm, 2 mm, 1 mm) of each example and comparative example, flame retardancy was evaluated according to fire resistance tests: JIS C60695-11-10:2015 and JIS C60695-11-20:2015. Tables 2 and 3 show the applicable flammability classification and thickness.

[0209]

[0210]

[0211]

[0212] The above invention is provided as an illustrative embodiment of the present invention, but this is merely illustrative and should not be interpreted restrictively. Modifications of the present invention that are obvious to those skilled in the art are included in the claims below.

[0213] The molding material and molded articles of the present invention are suitably used, for example, in the manufacture of fire-resistant sheets, connector covers for electrical components, gaskets (fixing sealants), brackets (support parts), busbars, harnesses (electric wires in which the ends of multiple wires are treated with terminals and connectors so that they can be connected to other equipment), connector parts, support parts, insulation (insulating and shielding materials), filters, plugs, clips, and sealing materials.

Claims

1. A molding material comprising an unsaturated polyester resin composition and plant natural fibers, wherein the unsaturated polyester resin composition comprises a resin component comprising a thermosetting resin containing an unsaturated polyester and a polymerizable monomer, the glass transition temperature when the mixture of the thermosetting resin and the polymerizable monomer is cured is 0°C or higher and 60°C or lower, and the content ratio of the polymerizable monomer is 40.0% by mass or less relative to the total amount of the thermosetting resin and the polymerizable monomer.

2. The molding material according to claim 1, wherein the unsaturated polyester resin composition contains aluminum hydroxide.

3. The molding material according to claim 1, wherein the unsaturated polyester resin composition contains a flame retardant.

4. The molding material according to claim 1, wherein the plant natural fiber is a plant natural fiber that has been treated to be flame-retardant.

5. A molded article comprising a cured product of the molding material described in any one of claims 1 to 4.

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