Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/40—Plastics, e.g. foam or rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
  • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/10—Polyamides derived from aromatically bound amino and carboxyl groups of amino-carboxylic acids or of polyamines and polycarboxylic acids

Definitions

• the present invention relates to a resin composition for cores and cores.
• Patent Document 1 discloses a core resin containing a polyvinyl alcohol resin and an easy-release agent.
• the present invention aims to provide a core resin composition that exhibits high heat resistance and can be used to produce cores that do not deform even under the molding conditions of super engineering plastics. It also aims to provide a core made using this core resin composition.
• the present disclosure (1) is a resin composition for a core, which contains a polyvinyl alcohol resin and organic fibers having a melting point of 200°C or higher.
• the present disclosure (2) is the resin composition for a core according to the present disclosure (1), in which the fiber diameter of the organic fibers is 50 ⁇ m or less.
• the present disclosure (3) is the resin composition for a core according to the present disclosure (1) or (2), in which the organic fiber is an aramid fiber.
• the present disclosure (4) is the resin composition for a core according to the present disclosure (1), (2), or (3), in which the content of the organic fiber is 3% by weight or more and 40% by weight or less.
• the present disclosure (5) is a core resin composition according to the present disclosure (1), (2), (3) or (4), further comprising a heat-resistant filler, wherein the total surface area of the heat-resistant filler per unit mass of the core resin composition calculated by the following formula (1) is 10 m 2 /g or more.
• the present disclosure (6) is the resin composition for a core according to the present disclosure (5), in which the average particle size of the heat-resistant filler is 1 nm or more and 100 nm or less.
• the present disclosure (7) is the resin composition for a core according to the present disclosure (5) or (6), in which the content of the heat-resistant filler is 5% by mass or more and 70% by mass or less.
• the present disclosure (8) is a resin composition for a core according to the present disclosure (1), (2), (3), (4), (5), (6), or (7), which has a melt flow rate (MFR) of 50 g/10 min or less under conditions of 230°C and a 10 kg load.
• the present disclosure (9) is a resin composition for a core according to the present disclosure (1), (2), (3), (4), (5), (6), (7), or (8), containing 0.1% by mass or more and 2% by mass or less of an easy-release agent.
• the present disclosure (10) is a resin composition for a core according to the present disclosure (1), (2), (3), (4), (5), (6), (7), (8), or (9), containing 0.1 mass% or more and 10 mass% or less of a plasticizer.
• the present disclosure (11) is a core resin composition according to the present disclosure (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10), which is in the form of pellets.
• the present disclosure (12) is a core made using the core resin composition of the present disclosure (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), or (11). The present invention will be described in detail below.
• a core resin composition containing polyvinyl alcohol resin can exhibit high heat resistance by incorporating organic fibers with a melting point of 200°C or higher. They also discovered that using such a core resin composition makes it possible to manufacture cores that do not deform even under high-temperature conditions, such as those used to mold super engineering plastics, and thus completed the present invention.
• the core resin composition contains a polyvinyl alcohol resin.
• a polyvinyl alcohol resin By using a polyvinyl alcohol resin, it can be easily removed from the molded body by, for example, immersing it in water.
• the degree of polymerization of the polyvinyl alcohol resin is preferably not more than 4000. When the degree of polymerization is not more than 4000, the resin can exhibit sufficient solubility in water.
• the degree of polymerization is more preferably 180 or more, even more preferably 200 or more, even more preferably 220 or more, and more preferably 3400 or less, even more preferably 2300 or less, even more preferably 1200 or less, and particularly preferably 900 or less.
• the degree of polymerization can be determined, for example, by measuring polyvinyl acetate before saponification by gel permeation chromatography (GPC) or by measuring the viscosity of an aqueous solution in accordance with JIS K6726.
• the saponification degree of the polyvinyl alcohol resin is preferably 72 mol % or more and 99.8 mol % or less. By setting the content within the above range, the solubility in water can be sufficiently exhibited.
• the saponification degree is more preferably 80 mol% or more, even more preferably 87 mol% or more, even more preferably 92 mol% or more, particularly preferably 95 mol% or more, more preferably 99.5 mol% or less, even more preferably 99 mol% or less.
• the saponification degree can be measured, for example, by a method in accordance with JIS K 6726.
• the saponification degree indicates the proportion of units that are actually converted into vinyl alcohol units among vinyl ester units that can be converted into vinyl alcohol units by saponification.
• the degree of saponification can be controlled, for example, by adjusting the saponification conditions, that is, the hydrolysis conditions.
• the weight average molecular weight (Mw) of the polyvinyl alcohol resin is preferably 8,000 or more, more preferably 9,000 or more, even more preferably 10,000 or more, even more preferably 11,000 or more, particularly preferably 14,000 or more, especially more preferably 17,000 or more, and is preferably 200,000 or less, more preferably 150,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less, especially preferably 40,000 or less, especially more preferably 32,000 or less, and most preferably 24,000 or less.
• the weight average molecular weight (Mw) of the entire polyvinyl alcohol resin is calculated based on the weight average molecular weight of each resin and its weight fraction, and is obtained by summing the values obtained by multiplying the weight average molecular weight of each polyvinyl alcohol resin by its weight fraction.
• the weight average molecular weight (Mw) is preferably 8000 or more, more preferably 9000 or more, even more preferably 10000 or more, even more preferably 11000 or more, particularly preferably 14000 or more, particularly more preferably 17000 or more, preferably 200000 or less, more preferably 150000 or less, even more preferably 100000 or less, even more preferably 50000 or less, particularly preferably 40000 or less, particularly more preferably 30000 or less, and most preferably 200000 or less.
• the number average molecular weight (Mn) of the above polyvinyl alcohol resin is preferably 4,000 or more, more preferably 4,500 or more, even more preferably 5,000 or more, even more preferably 10,000 or more, particularly preferably 16,000 or more, and preferably 90,000 or less, more preferably 60,000 or less, even more preferably 30,000 or less, even more preferably 25,000 or less, particularly preferably 22,000 or less.
• the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyvinyl alcohol resin is preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, even more preferably 1.6 or more, and is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.5 or less, even more preferably 2.0 or less.
• the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined, for example, by gel permeation chromatography (GPC), by measuring a polyvinyl ester before saponification by GPC, by measuring a polyvinyl ester obtained by re-esterifying a polyvinyl alcohol resin by GPC, or by measuring the viscosity of an aqueous solution in accordance with JIS K 6726.
• GPC gel permeation chromatography
• the polyvinyl alcohol resin preferably has a viscosity of 30 mPa ⁇ s or less in a 4% by mass aqueous solution, which provides fluidity suitable for extrusion and injection molding and water solubility suitable for use as a core.
• the viscosity of the 4% by mass aqueous solution is preferably 3 mPa ⁇ s or more, more preferably 5 mPa ⁇ s or more, more preferably 20 mPa ⁇ s or less, and even more preferably 10 mPa ⁇ s or less.
• the viscosity of the 4% by mass aqueous solution can be measured, for example, by a method in accordance with JIS K6276.
• the polyvinyl alcohol resin may be an unmodified polyvinyl alcohol resin or a modified polyvinyl alcohol resin.
• the unmodified polyvinyl alcohol resin refers to a polyvinyl alcohol resin containing only vinyl ester units and vinyl alcohol units
• the modified polyvinyl alcohol resin refers to a modified polyvinyl alcohol resin having structural units other than vinyl ester units and vinyl alcohol units.
• the modified polyvinyl alcohol resin include those modified with a hydrophilic modifying group such as a sulfonic acid group, a pyrrolidone ring group, an amino group, a carboxyl group, etc. These hydrophilic groups include not only the functional groups but also their salts such as sodium salts and potassium salts.
• the content of the polyvinyl alcohol resin in the core resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 65% by mass or more, and is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.
• the polyvinyl alcohol resin may contain multiple types of polyvinyl alcohol resins with different degrees of polymerization, saponification, etc. When the polyvinyl alcohol resin contains multiple types of polyvinyl alcohol resins, the content of the polyvinyl alcohol resins represents the total content of the multiple types of polyvinyl alcohol resins.
• vinyl esters examples include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, and vinyl benzoate.
• the method for polymerizing vinyl esters is not particularly limited, but examples include solution polymerization, bulk polymerization, and suspension polymerization.
• Polymerization catalysts used to polymerize the vinyl esters include, for example, 2-ethylhexyl peroxydicarbonate (Trigonox EHP manufactured by Tianjin McEIT), 2,2'-azobisisobutyronitrile (AIBN), t-butyl peroxyneodecanoate, bis(4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-cetyl peroxydicarbonate, and di-s-butyl peroxydicarbonate.
• One or more of the above polymerization catalysts may be used alone, or two or more may be used in combination.
• the polyvinyl alcohol resin may be a saponified polymer of a vinyl ester and another unsaturated monomer.
• unsaturated monomers include monomers other than the vinyl esters and having an unsaturated double bond such as a vinyl group.
• Specific examples include olefins, (meth)acrylic acid and salts thereof, (meth)acrylic acid esters, unsaturated acids other than (meth)acrylic acid, salts and esters thereof, (meth)acrylamides, N-vinylamides, vinyl ethers, nitriles, vinyl halides, allyl compounds, vinylsilyl compounds, isopropenyl acetate, sulfonic acid group-containing compounds, and amino group-containing compounds.
• Examples of olefins include ethylene, propylene, 1-butene, and isobutene.
• (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.
• Examples of unsaturated acids other than (meth)acrylic acid, and salts and esters thereof include maleic acid and salts thereof, maleic acid esters, itaconic acid and salts thereof, itaconic acid esters, methylenemalonic acid and salts thereof, and methylenemalonic acid esters.
• Examples of (meth)acrylamides include acrylamide, n-methylacrylamide, N-ethylacrylamide, and N,N-dimethylacrylamide.
• Examples of N-vinylamides include N-vinylpyrrolidone.
• Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, and n-butyl vinyl ether.
• Examples of nitriles include (meth)acrylonitrile.
• Examples of vinyl halides include vinyl chloride and vinylidene chloride.
• the allyl compounds include allyl acetate and allyl chloride.
• Examples of the vinylsilyl compound include vinyltrimethoxysilane.
• Examples of sulfonic acid group-containing compounds include (meth)acrylamidoalkanesulfonic acids such as (meth)acrylamidopropanesulfonic acid and salts thereof, and olefinsulfonic acids such as ethylenesulfonic acid, allylsulfonic acid, and methallylsulfonic acid and salts thereof.
• Examples of the amino group-containing compound include allylamine, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, and polyoxypropylene vinylamine.
• the core resin composition contains organic fibers having a melting point of 200° C. or higher. By including the organic fibers, heat resistance can be improved. In the case of fibers whose melting point cannot be measured, the thermal decomposition initiation temperature or softening temperature can be used instead. In this case, if any one of the melting point, softening temperature, or thermal decomposition initiation temperature is 200°C or higher, the heat resistance can be improved.
• the organic fibers mentioned above have an aspect ratio of 12 or more. The aspect ratio is preferably 20 or more, more preferably 35 or more, and even more preferably 50 or more.
• organic fibers examples include aramid fibers, nylon fibers, rayon fibers, polyester fibers, and cellulose fibers.
• aramid fibers are preferred because they can further enhance heat resistance.
• the melting point of the organic fiber is 200° C. or higher, preferably 250° C. or higher, and more preferably 300° C. or higher. There is no particular upper limit, and in view of the gist of the present application, the higher the melting point, the better.
• the melting point can be confirmed by a differential scanning calorimeter (DSC). If the melting point cannot be measured by DSC because it is higher than the decomposition temperature, the thermal decomposition onset temperature can be measured using a thermogravimetric analyzer or the like, and the measured value can be used. TG-DTA or the like can also be used.
• the content of the organic fibers in the core resin composition is preferably 3% by weight or more and 40% by weight or less. By setting the content within this range, heat resistance can be further improved.
• the content of the organic fibers is more preferably 4.5% by weight or more, even more preferably 9% by weight or more, and even more preferably 35% by weight or less.
• the content can be further reduced, and in that case, the content is even more preferably 20% by weight or less, and particularly preferably 10% by weight or less.
• the core resin composition preferably further contains a heat-resistant filler.
• a heat-resistant filler By including a heat-resistant filler, the heat resistance can be further improved.
• the total surface area is calculated by multiplying the surface area (m 2 ) per heat-resistant filler (4 ⁇ (B/2) 2 ) by the number of heat-resistant fillers per 1 g of the core resin composition.
• Examples of materials for the heat-resistant filler include metals, metal oxides, ceramics, carbon materials, glass, etc. Furthermore, resin particles having a melting point of 200° C. or higher can also be used as the particulate filler.
• Examples of the metal oxide include titanium oxide, aluminum oxide, calcium oxide, lithium oxide, molybdenum oxide, vanadium oxide, zinc oxide, nickel oxide, cesium oxide, and iron oxide. Other examples include boron nitride, aluminum nitride, gold, silver, copper, platinum, palladium, and silicon carbide.
• Examples of the carbon material include carbon black, graphite, and diamond. Among these, titanium oxide and carbon black are preferred from the viewpoints of cost performance, availability, etc.
• Examples of the resin having a melting point of 200° C. or higher include polyethylene terephthalate, polyamide, aromatic polyamide (aramid), polyimide, polyether ether ketone (PEEK), and the like.
• the core resin composition may also contain other additives such as antioxidants, colorants, antifoaming agents, ultraviolet absorbers, and preservatives.
• Examples 1 to 10 Comparative Examples 1 to 3
• Polyvinyl alcohol resin, organic fibers, inorganic fibers, antioxidant, heat-resistant filler, and easy-release agent were mixed to obtain the formulation shown in Table 1, and the mixture was pelletized at an extrusion temperature of 190°C to 210°C using a processing device "TEM26SX" manufactured by Toshiba Machine Co., Ltd., to obtain pellets of a resin composition for a core.
• TEM26SX manufactured by Toshiba Machine Co., Ltd.
• Total surface area of heat-resistant filler per unit mass of core resin composition (m 2 /g) The total surface area of the particulate filler per unit mass of the core resin composition was calculated based on the following formula (1).
• E density of heat-resistant filler (g/m 3 )
• melt flow rate (MFR) Using a melt index tester No. 120-FWP (manufactured by Yasuda Seiki Seisakusho, Ltd.), the melt flow rate (MFR) of the core resin composition was measured according to a method in accordance with ASTM D 1238 under conditions of an initial weight of the core resin composition of 7.5 g, 230°C, a load of 10 kg, and a measurement time interval of 0.25 minutes.
• the present invention provides a core resin composition that exhibits high heat resistance and can be used to produce cores that do not deform even under the molding conditions of super engineering plastics. It also provides cores made using this core resin composition.

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