JP2005307141A - Resin composition for metal coating film excellent in impact resistance and production process therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin composition for a metal coating film excellent in impact resistance, and to provide a process for its production. <P>SOLUTION: The resin composition for the metal coating film excellent in impact resistance is composed of at least three resins of a polyester resin (A), a gumlike elastic resin (B) and a polyolefin copolymer resin (C) having a functional group-containing unit capable of forming a covalent bond without by-producing a polyester and water. The composition has a structure of finely dispersed 1-30 pts.mass of the gumlike elastic resin (B) based on 100 pts.mass of the polyester resin (A) by mixed fusion and kneading and 0.1-10 pts.mass of the polyolefin copolymer resin (C) in a mixed ratio of the gumlike elastic resin (B) to the polyolefin copolymer resin (C) of 10:1-10:5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal-coated film resin composition having excellent impact resistance and a method for producing the same. More specifically, the present invention relates to a resin composition for a film excellent in impact resistance used for drawing, a laminated metal can film for forming a coated film of a laminated steel sheet for cans used by drawing and ironing, and a method for producing the same. .

  Conventionally, for example, an epoxy-phenolic resin, an epoxy-amino resin, or an aqueous epoxy-acrylic resin coating has been applied to the inside of a beverage can to prevent corrosion. In recent years, a polyester film having impact resistance has been changed in advance to a paint can because it has excellent flavor retention and can-making properties, and the paint solvent treatment and lubricating liquid treatment can be omitted in the can-making process. Beverage cans that are deep-drawn and drawn and wrung using laminated steel plates are becoming popular.

  JP-A-3-269704 (Patent Document 1) discloses a resin constituting a resin film for coating a laminated steel sheet for deep drawing and ironing processing described above, from crystalline polyester resin and amorphous polyester resin. A method of laminating a resin composition is disclosed. In this method, the crystallization rate of the interface can be easily reduced during the laminating step, so that the adhesion is improved, but the impact resistance and gas barrier properties are lowered. There were restrictions on the process such as using a stretched film to actively leave crystallization.

  Japanese Patent Application Laid-Open No. 7-195617 (Patent Document 2) discloses a technique of laminating a film made of a composition of a polyester resin and an ionomer resin on a metal plate. With this technology, even if crystallization is reduced, the resin itself has impact resistance, so it can have both adhesion and impact resistance, but it has reached the point where it can sufficiently improve impact resistance at low temperatures. Not in. Furthermore, in Japanese Patent Application Laid-Open No. 7-290644 (Patent Document 3) and Japanese Patent Application Laid-Open No. 7-290643 (Patent Document 4), a ternary composition of a polyester resin, an ionomer resin, and a polyester elastomer is applied to a coating on a metal plate. Techniques to do this are disclosed. Although these techniques have improved impact resistance to some extent at both low temperature and room temperature, they have not yet reached a sufficient level.

  Furthermore, WO99 / 27026 (Patent Document 5) discloses a resin composition in which an olefin rubber-like elastic body encapsulated with an ionomer resin is finely dispersed in a polyester resin. With this resin composition, it is possible to greatly improve the adhesion and impact resistance. However, when a metal container is continuously formed by ironing for a long period of time, the impact resistance is reduced or whitened. In some cases, the appearance was deteriorated. On the other hand, in Japanese Patent Application Laid-Open No. 2003-113292 (Patent Document 6), in order to solve the above technical problem, an olefin rubber-like elastic resin encapsulated with an epoxy group-containing polyolefin resin is finely dispersed in a polyester resin. A resin composition is disclosed.

Japanese Patent Laid-Open No. 3-269074 JP-A-7-195617 Japanese Patent Laid-Open No. 7-290644 Japanese Patent Laid-Open No. 7-290643 WO99 / 27026 JP 2003-113292 A

  The technique disclosed in Japanese Patent Application Laid-Open No. 2003-113292 selects a polyolefin-based resin having an epoxy group-containing unit as a compatibilizing agent capable of strong interaction with a polyester resin, and melts and kneads a rubber-like elastic resin. Dispersion is intended to reduce whitening during processing and improve impact resistance. With this resin composition, it is possible to reduce whitening when the metal container is continuously formed by ironing for a long period of time and to greatly improve the impact resistance of the molded can body. Depending on the composition conditions and manufacturing conditions, fine dispersion could not be sufficiently achieved, and as a result, the impact resistance of the molded can body sometimes deteriorated.

  In the resin composition, in order to finely disperse the rubber-like elastic resin in the polyester resin, it is necessary to blend the respective raw materials with a kneading extruder. However, the melting point of the rubber-like elastic resin and the polyolefin copolymer resin is too low with respect to the melt kneading temperature of the polyester resin, and the polyester resin and the polyolefin copolymer resin react to react locally. Since heat is generated, when the resin composition is blended by a kneading extruder, the rubbery elastic resin is finely dispersed in the polyester resin unless the proper composition conditions of the raw material resin and the production conditions of the resin are selected. In addition to being able to obtain a stable film, even if a film is obtained, impact resistance may be reduced in a can body that has been processed after being laminated to a steel plate.

  The present invention relates to a laminated steel sheet film in which a rubber-like elastic resin is dispersed in a polyester resin for the purpose of improving impact resistance, and has a shock-resistant film capable of stably finely dispersing the rubber-like elastic resin. Resin composition and a method for producing the resin composition are provided.

  As a result of intensive studies to solve the above problems, the present inventors have stably carried out rubber-like elastic resin by kneading and extrusion under proper raw material composition conditions and appropriate production conditions. The present invention was completed by finding that a resin composition for film having fine impact properties and impact resistance can be produced.

That is, the gist of the present invention is as follows.
(1) At least three types of polyester resin (A), rubber-like elastic resin (B), and polyolefin copolymer resin (C) having a functional group-containing unit capable of covalently bonding without forming polyester and water molecules as a by-product A resin composition having a structure in which a rubber-like elastic resin (B) is finely dispersed in a polyester resin (A) by melt-kneading, and is rubber against 100 parts by mass of the polyester resin (A) The elastic elastomer resin (B) is 1 to 30 parts by mass, the polyolefin copolymer resin (C) is 0.1 to 10 parts by mass, and the rubber elastic resin (B) and the polyolefin copolymer The resin composition for metal-coated films having excellent impact resistance, wherein the mixing ratio of the polymer resin (C) is in the range of 10: 1 to 10: 5.

(2) The rubber-like elastic resin (B) is 1 to 30 parts by mass and the polyolefin-based copolymer resin (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyester resin (A). Further, when a resin composition having a mixing ratio of the rubber-like elastic resin (B) and the polyolefin copolymer resin (C) in the range of 10: 1 to 10: 5 is melt-kneaded to produce a resin composition. The metal-coated film having excellent impact resistance according to (1) above, wherein a shear rate of at least 80 sec ⁻¹ or more is applied within the range of the melting point of the polyester resin (A) + 5 ° C. to + 50 ° C. It is a manufacturing method of a resin composition.

(3) The polyolefin copolymer resin (C) is a polyolefin copolymer resin containing 10% by mass or less of an epoxy group-containing unit as a functional group unit that can be covalently bonded to polyester. (2) It is a manufacturing method of the resin composition for metal coating films which is excellent in impact resistance.
(4) The inherent viscosity of the polyester resin is in the range of 0.5 to 1.5 dl / g, the moisture content is 200 ppm or less, and the end of the polyester chain is a carboxylic acid residue (—COOH) and / or a hydroxyl group (—OH). It is a manufacturing method of the resin composition for metal coating films which is excellent in impact resistance as described in said (2) and (3) characterized by the above-mentioned.

  As described in detail above, the resin composition for metal-coated film and the production method of the present invention can stably finely disperse a rubber-like elastic resin in a polyester resin, and are obtained by the present invention. The film using the resin composition is also stably provided with impact resistance. From this, it can be said that it is an industrially very high value invention as a manufacturing method of resin compositions, such as a coating film used for the laminated metal plate for drink cans by which impact resistance is calculated | required.

Below, the resin composition for metal coating films which is excellent in impact resistance which is this invention, and the manufacturing method of the resin composition are demonstrated.
First, the resin composition of the present invention will be described. The resin composition of the present invention comprises a polyester resin (A), a rubber-like elastic resin (B), and a polyolefin copolymer resin (C) having a functional unit that can be covalently bonded without forming a water molecule as a polyester. The rubber-like elastic resin (B) is finely dispersed in the polyester resin (A) for the purpose of improving the impact resistance of the polyester resin (A). However, since it is difficult to finely disperse the rubber-like elastic resin (B) in a polyester resin in a submicron order particle size by only ordinary kneading, functional groups capable of covalently bonding to the polyester A polyolefin copolymer resin (C) having a containing unit is added as a compatibilizing agent for the rubber-like elastic resin (B) and encapsulated.

  Here, the rubber-like elastic resin (B) is “finely dispersed” in the polyester resin (A) means that 70% by volume or more of the particles of the rubber-like elastic resin (B) are 20 μm or less. It is in a state of being dispersed in the polyester resin (A) with an equivalent spherical equivalent diameter. When the equivalent spherical equivalent diameter of the rubber-like elastic resin (B) is more than 20 μm, the impact resistance is lowered and the film forming property of the resin composition is lowered. The equivalent sphere equivalent diameter is preferably 1.5 μm or less, more preferably 1.0 μm or less, and even more preferably 0.8 μm or less. If it exceeds 1.5 μm, sufficient impact resistance may not be exhibited.

  The rubber-like elastic resin (B) “encapsulated” with the polyolefin-based copolymer resin (C) is 60% or more, preferably 80% or more of the interface of the rubber-like elastic resin (B). Preferably, 90% or more is covered with the polyolefin copolymer resin (C), and the direct contact area between the polyester resin (A) and the rubber-like elastic resin (B) is less than 30%. By having such a structure, it becomes easy to finely disperse the rubber-like elastic resin (B) encapsulated with the polyolefin-based copolymer resin (C), and the impact resistance and film forming property are improved. The rubber-like elastic resin (B) generally has low adhesion to the metal plate, but since the polyolefin copolymer resin (C) having a polar group has adhesion to the metal plate, the finely dispersed particles are Even if it contacts a metal plate, it has the effect that the adhesiveness of a resin composition and a metal plate can be ensured.

  It is not necessary that all particles of the rubber-like elastic resin (B) are encapsulated with the polyolefin-based copolymer resin (C), and at least 70% or more of the rubber-like elastic resin (B) in the volume ratio is polyolefin-based. What is necessary is just to encapsulate with copolymer resin (C). When the unencapsulated rubber-like elastic resin (B) exceeds 30% by volume, fine dispersion becomes difficult, impact resistance is reduced, and the resin composition is coated on a metal plate Increases the ratio of the rubber-like elastic resin (B) that is in direct contact with the metal plate, making it impossible to ensure the adhesion between the resin composition and the metal plate.

  The average equivalent spherical equivalent diameter of the non-encapsulated rubber-like elastic resin (B) is not particularly specified, but is preferably 1.0 μm or less from the viewpoint of impact resistance and workability. Further, an excessive amount of the polyolefin-based copolymer resin (C) may be dispersed alone in the polyester resin (A) without encapsulating the rubber-like elastic resin (B). The amount and diameter of the polyolefin-based copolymer resin (C) that is not encapsulated are not particularly limited. However, the volume ratio of the total polyolefin-based copolymer resin (C) is 20% or less, and the average equivalent spherical equivalent diameter. It is desirable that it is 1.0 μm or less. If the volume ratio exceeds 20%, the basic properties such as heat resistance of the resin composition may change. Further, when the average equivalent sphere equivalent diameter exceeds 1.0 μm, the workability may be deteriorated.

  The composition of these resins is 1 to 30 parts by mass of the rubber-like elastic resin (B) and 1 to 10 parts by mass of the polyolefin copolymer resin (C) with respect to 100 parts by mass of the polyester resin (A). Yes, it is essential that the mixing ratio of the rubber-like elastic resin (B) and the polyolefin copolymer resin (C) is in the range of 10: 1 to 10: 5. If the rubber-like elastic resin (B) is less than 1 part by mass relative to 100 parts by mass of the polyester resin (A), impact resistance may be insufficient even if finely dispersed, which is not preferable. When the amount of the rubber-like elastic resin (B) exceeds 30 parts by mass, the rubber elasticity of the added rubber-like elastic resin (B) causes a decrease in shearing force at the time of kneading and makes it difficult to make fine dispersion. The amount is preferably 8 to 20 parts by mass, more preferably 10 to 15 parts by mass, from the balance between fine dispersion and impact resistance.

  If the polyolefin copolymer resin (C) is less than 0.1 part by mass relative to 100 parts by mass of the polyester resin (A), diffusion during kneading is insufficient and the effect as a compatibilizing agent is reduced, resulting in a rubbery elastic resin. Although it depends on the amount of (B), it may not be able to be uniformly finely dispersed. If it exceeds 10 parts by mass, although it is finely dispersed, local thickening occurs due to reaction with polyester, and stable film formation cannot be achieved. There is a case. Preferably it is 0.5-6 mass parts from the balance of fine dispersion and film forming property, More preferably, it is 1-4.5 mass parts. The mixing ratio of the rubber-like elastic resin (B) and the polyolefin-based copolymer resin (C) is 10: 1 to 10: 5 so that the rubber-like elastic resin (B) is stably added to the polyolefin-based copolymer resin ( It is preferable to encapsulate and finely disperse in C), and fine dispersion may be difficult outside this range. More preferably, it is 10: 1.5-10: 3.

  Next, each constituent of the resin composition of the present invention will be described in detail. First, regarding the polyester resin (A), the polyester resin (A) used in the present invention includes only a hydroxycarboxylic acid compound residue, a dicarboxylic acid residue and a diol compound residue, or a hydroxy resin. A thermoplastic polyester having a carboxylic acid compound residue, a dicarboxylic acid residue, and a diol compound residue as constituent units. Moreover, these mixtures may be sufficient.

  Examples of dicarboxylic acid compounds that form dicarboxylic acid residues include terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2 , 6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid and other aromatic dicarboxylic acids, and adipic acid, vimelic acid, sebacic acid, azelaic acid, decanedicarboxylic acid Examples thereof include aliphatic dicarboxylic acids such as acid, malonic acid, succinic acid, malic acid, and citric acid, cyclohexanedicarboxylic acid, and cycloaliphatic dicarboxylic acids. These may be used alone or in combination of two or more. May be used in combination.

  Next, diol compounds that form diol residues are exemplified by 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as “bisphenol A”), bis (4-hydroxyphenyl) methane, bis (2 -Hydroxyphenyl) methane, o-hydroxyphenyl-p-hydroxyphenylmethane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ) Ketone, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) -p-diisopropylbenzene, bis (3,5-dimethyl-4-hydroxyphenyl) methane, bis (3-methyl-4-hydroxyphenyl) ) Methane, bis (3,5-dimethyl) -4-hydroxyphenyl) ether, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfide, 1,1-bis (4-hydroxyphenyl) ethane 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5 -Trimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis ( 3,5-dimethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4-hydroxyphene) ) Propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-) 4-hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxyphenyl) propane, 1,1,1,3,3,3-hexafluoro2,2-bis (4-hydroxyphenyl) propane, Aromatic diols such as 4,4′-biphenol, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, 4,4′-dihydroxybenzophenone, and ethylene glycol, trimethylene glycol, Propylene glycol, tetramethylene glycol, 1,4-butanediol, pentamethylene glycol, neopentylglycol , Hexamethylene glycol, dodecamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, aliphatic diols such as hydrogenated bisphenol A, alicyclic diols such as cyclohexanedimethanol, and the like. It can also be used in a mixture of two or more.

  Moreover, the polyester resin obtained from these may be used independently or may be used in mixture of 2 or more types. The polyester resin (A) used in the present invention may be composed of these compounds or a combination thereof, and is an aromatic polyester resin composed of an aromatic dicarboxylic acid residue and a diol residue. Is preferable from the viewpoint of processability and thermal stability.

The polyester resin (A) used in the present invention is a small amount of structural units derived from polyfunctional compounds such as trimesic acid, pyromellitic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, pentaerythritol, for example, You may contain 2 mol% or less.
From the viewpoints of heat resistance and processability, the most preferred combination of these dicarboxylic acid compounds and diol compounds is a dicarboxylic acid of terephthalic acid 50 to 95 mol%, isophthalic acid and / or orthophthalic acid 50 to 5 mol%. It is a combination of a compound and a diol compound of a glycol having 2 to 5 carbon atoms.

Next, the rubber-like elastic resin (B) of the present invention will be described. As the rubber-like elastic resin (B) constituting the resin composition of the present invention, known rubber-like elastic resins widely described in Toshio Nishi, “Points of rubber material selection”, Japanese Standards Association (1993) and the like are widely used. it can. Among these, a copolymer having a constituent unit of (Formula 2) is preferable from the viewpoint of the barrier property of corrosion factors such as water vapor and oxygen.
—R ₁ CH—CR ₂ R ₃ — (Formula 2) wherein R ₁ and R ₃ are each independently an alkyl group having 1 to 12 carbon atoms or hydrogen, and R ₂ is an alkyl having 1 to 12 carbon atoms. Group, phenyl group or hydrogen)

  Specifically, ethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, ethylene-butene copolymer, ethylene-acrylic copolymer, styrene-butadiene copolymer Examples thereof include a copolymer comprising a coalescence and a hydrogenated product thereof. More specifically, very low density polyethylene, low density polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-3-ethylpentene copolymer, A copolymer of ethylene and an α-olefin having 3 or more carbon atoms, such as an ethylene-1-octene copolymer, an ethylene-vinyl acetate copolymer, a copolymer of ethylene-acrylic acid or a derivative thereof, and ethylene-methacrylic acid; Alternatively, a copolymer with a derivative thereof, ethylene obtained by copolymerizing butadiene, isoprene, 5-methylidene-2-norbornene, 5-ethylidene-2-norbornene, cyclopentadiene, 1,4-hexadiene or the like with the binary copolymer. , A terpolymer composed of an α-olefin having 3 or more carbon atoms and a non-conjugated diene, styrene-butadiene Examples thereof include a copolymer, a hydrogenated product thereof, and a styrene-isoprene copolymer. Among them, very low density polyethylene, low density polyethylene, binary copolymer of ethylene-propylene copolymer or ethylene-vinyl acetate copolymer, or ethylene-propylene copolymer, 5 as non-conjugated diene. -Using methylidene-2-norbornene, 5-ethylidene-2-norbornene, cyclopentadiene, 1,4-hexadiene, the amount of α-olefin was 20 to 60% by mass, and the amount of non-conjugated diene was 0.5 to 10% by mass. Polymerized resins are preferred. Since these resins have a crystalline phase, good impact resistance can be maintained in the region from −10 ° C. to room temperature.

  Furthermore, the preferable melt viscosity range of the rubber-like elastic resin (B) is determined by the dispersibility in the polyester resin (A), and in order to finely disperse in the polyester resin (A), the melt kneading temperature, shearing Compared to the viscosity of the polyester resin (A) in the speed range, the viscosity is preferably ½ or less. Depending on the melt viscosity of the polyester resin (A), the molecular weight of the rubber elastic resin (B) and It is desirable to control the molecular weight dispersion so as to be in the above viscosity range. Specific melt viscosity measurement conditions are exemplified by a capillary viscometer in a shear rate range of 100 to 1000 / s at a temperature of the melting point of the highest melting point component + 35 ° C. among the resins constituting the polyester resin (A). The method of measuring by is mentioned.

  The rubber-like elastic resin (B) used in the present invention may be a homopolymer of these structural units, or two or more types of copolymers, or a resin formed from these units. It may be a copolymer of units. Examples of repeating units include addition of α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, etc. O-, m-, p-methylstyrene, o-, m-, p-ethylstyrene, t in addition to aliphatic olefins such as repeating units appearing when polymerized, repeating units when isobutene is added, and styrene monomers -An aromatic olefin such as an alkylated styrene such as butyl styrene, a halogenated styrene such as monochlorostyrene, an addition polymer unit of a styrene monomer such as α-methylstyrene, and the like.

The polyolefin copolymer resin (C) of the present invention will be described. For the purpose of finely dispersing the rubber-like elastic resin (B) in the polyester resin (A), a polyolefin-based copolymer resin (C) having a functional group-containing unit capable of being covalently bonded without forming a polyester and a water molecule as a by-product. Must contain.
A functional group unit capable of covalent bonding without forming a water molecule as a co-polymer with polyester can form a covalent bond by reacting with a carboxylic acid residue (—COOH) and / or a hydroxyl group (—OH) at the end of the polyester chain. And when forming the said covalent bond, it is a functional group containing unit which does not by-produce a water molecule by dehydration condensation etc. If water molecules are formed as a by-product, water molecules are present in the kneading system, which may cause a hydrolysis reaction of the polyester resin (A), which is not preferable because it causes a decrease in the molecular weight of the polyester.

  As long as it is a functional group-containing unit capable of covalently bonding without forming a polyester and water molecule as a by-product, it may have any chemical structure. Specific examples include functional group-containing units such as epoxy groups and maleic anhydride. By having functional group-containing units such as epoxy groups and maleic anhydride in the polyolefin copolymer resin (C), the polyester resin (A) and the polyolefin copolymer resin (C) are covalently bonded. Thus, fine dispersion can be improved and, at the same time, even if the coating temperature rises by continuous ironing, the fine dispersion state can be stably maintained. Since the reactivity is higher, an epoxy group-containing unit is preferable among the functional group-containing units for fine dispersion.

  The polyolefin-based copolymer resin (C) used in the present invention is composed of a unit of (Formula 2) and a functional group-containing unit. The functional group-containing unit is preferably copolymerized at 10% by mass or less. The polyolefin-based copolymer resin (C) used in the present invention may be a copolymer of one or more of these units, or a copolymer in which the units are copolymerized with resin units. Specifically, the structural unit represented by (Formula 2) is exemplified by propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene. In addition to aliphatic olefins such as repeating units obtained by addition polymerization of α-olefin such as isobutene, repeating units when isobutene is added, styrene monomer, o-, m-, p-methylstyrene, o-, Examples thereof include alkylated styrenes such as m-, p-ethylstyrene and t-butylstyrene, halogenated styrenes such as monochlorostyrene, and aromatic olefins such as styrene monomer addition polymer units such as α-methylstyrene.

  Furthermore, in the polyolefin-based copolymer resin (C), in addition to the functional group-containing unit, the third unit having a polar group other than the preceding functional group may be copolymerized at 40% by mass or less. preferable. By copolymerization of a nonpolar (formula 2) unit with a third unit having a polar group, S.P. Y. Hobbs, et al. , Polymer, Vol. 29, 1598 (1988), the Spread Parameter between the rubber-like elastic resin (B) / polyolefin copolymer resin (C) in the polyester resin (A) can be positively controlled. The coalesced resin (C) encapsulates the rubber-like elastic resin (B) and is stably dispersed in the polyester resin (A), which is suitable for fine dispersion. As a result, in the resin composition, the rubber-like elastic resin (B) component does not directly contact the metal, but contacts the metal via the polyolefin copolymer resin (C) containing the polar unit. Good adhesion can be secured.

Examples of polar group-containing units are vinyl alcohol as an example having a —C—O— group, vinyl chloromethyl ketone as an example having a —C═O group, acrylic acid, methacrylic acid, acetic acid as examples having a —COO— group. Vinyl acid such as vinyl and vinyl propionate and its metal salt or ester derivative, maleic anhydride as an example having C ₂ O ₃ group, imide derivative of maleic anhydride as an example having C ₂ O ₂ N-group, -CN As an example having a group, acrylonitrile, As an example having a —NH ₂ group, As an example having an —NH— group, As an example having an —X group (halogen) As an example having a —SO ₃ — group Styrene sulfonic acid, etc. are mentioned, and even if these are contained alone or in plural in the polyolefin resin (C) good.

The unit having a polar group contained in the polyolefin-based copolymer resin (C) may be a unit having a group in which elements having a difference in electronegativity of boring of 0.39 (eV) ^0.5 or more are bonded, It is not limited to the above specific example. Examples of polar group-containing units that are preferable for positively controlling the above Spread Parameter include vinyl esters such as vinyl ether, vinyl acetate, and vinyl propionate, methacrylic acid esters or acrylic acid esters such as ethyl, methyl, propyl, and butyl, Acrylonitrile is mentioned.

  Examples of the polyolefin-based copolymer resin (C) include an ethylene-functional group-containing methacrylate copolymer, an ethylene-vinyl acetate-functional group-containing methacrylate copolymer, and an ethylene-functional group-containing acrylic ester copolymer. And ethylene-vinyl acetate-functional group-containing acrylate copolymer, ethylene-methyl acrylate-maleic anhydride copolymer, and the like. Among them, ethylene-vinyl acetate-functional group-containing methacrylate copolymer, An ethylene-methyl acrylate-maleic anhydride copolymer is preferred from the viewpoint of thermal stability.

  Next, the manufacturing method of the resin composition of this invention is described. The method for producing the resin composition of the present invention includes a melt kneading method, a solvent mixing method, and the like. It is most preferable because it can be finely dispersed, can prevent the functional group reacting with the polyester of the polyolefin-based copolymer resin (C) from decreasing in activity, and has few impurities such as residual solvent. Examples of resin kneading include dry blending with a tumbler blender, Henschel mixer, V-type blender, etc., and then melt kneading with a single screw or twin screw extruder. For finer dispersion, it is preferable to use a twin-screw extruder with good kneading efficiency.

As conditions for melt-kneading and producing the resin composition of the present invention, the kneading temperature is such that the resin temperature at the time of melt-kneading is within the range of the melting point of the polyester resin (A) + 5 ° C. to + 50 ° C., and at least the shear rate is 80 sec ⁻ Must be at least ¹ . The resin temperature in this case means the resin temperature immediately after the kneader part of the screw of the extruder. If the temperature cannot be measured at the same site, the resin temperature extruded from the die may be measured. If the resin temperature after kneading is less than the melting point of the polyester resin (A) + 5 ° C., the polyester resin (A) may not be melted, which makes it difficult to achieve uniform fine dispersion.

  When the resin temperature is higher than the melting point of the polyester resin (A) + 50 ° C., the reaction between the polyester (A) and the polyolefin copolymer resin (C) is promoted, and the reaction heat locally increases the temperature, resulting in a rubber-like elastic body. The resin (B) and / or the polyolefin copolymer resin (C) will be thermally deteriorated, and the kneading efficiency will be lowered due to the lower melt viscosity of the polyester, making it difficult to make fine dispersion. Furthermore, excessive heat is applied to the resin composition, which may cause a decrease in physical properties of the resin composition due to thermal deterioration, which is not preferable. Preferred for fine dispersion is a lower temperature within a range where the polyester resin does not melt even within the above temperature range.

Furthermore, the shear rate must be at least 80 sec ⁻¹ within the temperature range. When the shear rate is less than 80 sec ⁻¹ , fine dispersion becomes difficult.
For fine dispersion, it is preferable to set the kneading conditions so that the resin temperature and shear rate are set, and the maximum shearing force of the extrusion apparatus is applied to the resin. Specifically, it is preferable that the temperature is set at a lower temperature and the screw rotation speed is higher. The screw shape is also preferably a type that can apply a shearing force to the resin, and it has many kneader parts to the extent that it does not cause a significant decrease in physical properties (especially a decrease in viscosity) in order to improve kneading efficiency. For example, increasing the resin filling rate and frequently using a reverse screw to increase the back pressure. For the same reason, a twin screw extruder is preferable to a single screw.

  When performing melt-kneading in the air, there is a case where a method of shutting off oxygen by replacing the melt-kneaded part of the resin with inert gas is used to prevent oxidative degradation of the olefin resin. Inactive used to reduce the compatibilizing effect of the polyolefin copolymer resin (C), which may react with the moisture of the polyolefin copolymer resin (C) and the site capable of covalent bonding with the polyester. It is preferable to use a gas that has been subjected to a drying treatment.

  In the case where an epoxy group-containing unit is used as the functional group unit capable of covalently bonding with the polyester, the polyolefin copolymer resin (C) contains a polyolefin copolymer resin (C ) Is preferably used. The polyolefin-based copolymer resin (C) is composed of a unit of (Formula 2) and an epoxy group-containing unit. The polyolefin-based copolymer resin (C) used in the present invention may be a copolymer of one or more of these units, or a copolymer in which the units are copolymerized with resin units.

  If the epoxy group-containing unit exceeds 10% by mass, the amount of bonding between the epoxy group and the polyester resin (A) increases, the viscosity of the polyester resin (A) increases, and the fine dispersion becomes uneven. As a result, when the resin composition is used as a film, the film properties may be deteriorated, resulting in film scratches during the ironing process described above, reduced impact resistance, or reduced adhesion between the metal and the coating. Furthermore, this tendency becomes particularly remarkable when forming a film simultaneously with kneading. Therefore, when forming a film in such a process, the content of the epoxy group-containing unit is 5% by mass or less, more preferably 8% by mass or less. Is desirable.

Examples of the epoxy group-containing unit include glycidyl esters of α, β-unsaturated acids shown in (Formula 3).
_{CH 2 = CR-CO-O} -CH 2 -CH (O) -CH 2 ( Equation 3)
(Wherein R is a hydrogen atom, a lower alkyl group or a lower alkyl group substituted with a glycidyl ester group)
More specifically, it is an ester such as glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, etc. Among them, it has good thermal stability and suppresses the generation of thermally deteriorated products even during long-term continuous kneading. From the viewpoint that it can be used, glycidyl methacrylate is particularly preferably used.

Furthermore, in the polyolefin-based copolymer resin (C), as described above, in addition to the unit of (Formula 2) and the epoxy group-containing unit, the third unit having a polar group other than the epoxy group is 40% by mass. Copolymerization is preferred below.
Examples of the polyolefin-based copolymer resin (C) having an epoxy group-containing unit include ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate copolymer, ethylene-glycidyl acrylate copolymer, ethylene -Vinyl acetate-glycidyl acrylate copolymer etc. are mentioned, Among them, ethylene-vinyl acetate-glycidyl methacrylate copolymer is preferred from the viewpoint of thermal stability.

  On the other hand, the polyester resin (A) used in the present invention has an intrinsic viscosity of 0.5 to 1.5 dl / g or less, a moisture content of 200 ppm or less, and the end of the polyester chain efficiently reacts with the compatibilizer. Therefore, a polyester having a carboxylic acid residue (—COOH) and / or a hydroxyl group (—OH) is preferable. When the intrinsic viscosity of the polyester resin (A) is less than 0.5 dl / g, the melt viscosity of the polyester is lowered when heat plasticizing at the time of kneading, and an efficient kneading effect cannot be obtained, making fine dispersion difficult. And, since the film strength obtained is insufficient, it is not preferable. If it exceeds 1.5 dl / g, the rubber-like elastic resin (B) and the polyolefin copolymer resin (C) are poorly diffused during melt kneading, making it difficult to uniformly disperse them. Further, it is uneconomical, and heat generation during melt kneading with the rubber-like elastic resin (B) and the polyolefin-based copolymer resin (C) increases, so that the rubber-like elastic resin (B) and / or the polyolefin-based co-polymer is used. This is not preferable because an oxidative degradation product of the polymer resin (C) is easily generated and thermally decomposed.

Moreover, when the moisture content of the polyester resin (A) is 200 ppm or more, there is a possibility of reacting with a functional group-containing unit such as an epoxy group covalently bonded to the polyester in the polyolefin-based copolymer resin (C), which reacts originally. Bonding with the polyester resin (A) becomes impossible and the effect as a compatibilizer is reduced. As a result, fine dispersion may not be achieved, which is not preferable. Said melting | fusing point is calculated | required with thermal analyzers, such as a differential scanning thermal analyzer (DSC). In addition, the intrinsic viscosity is measured at a concentration of 0.5% in o-chlorophenol at 25 ° C., and is obtained by the following equation (1). In the formula, C represents the concentration expressed in g of resin per 100 ml of solution, t ₀ represents the solvent flow time, and t represents the solution flow time.
Intrinsic viscosity = {1n (t / t ₀ )} / C (1)
Further, the moisture content is determined by the Karl Fischer method or the like.

  The resin of the present invention contains an appropriate amount of an antioxidant, a heat stabilizer, a light stabilizer, a release agent, a lubricant, a pigment, a flame retardant, a plasticizer, a nucleating agent, an antistatic agent, an antibacterial antifungal agent, etc., depending on the purpose. It is also possible to add. Among these, a lubricant is added for the purpose of improving lubricity when a film is coated on a metal plate or a laminate plate is processed, and a known lubricant as disclosed in JP-A-5-186613 is used. It is done. As the lubricant, inorganic particles having a particle size of 2.5 μm or less such as silica, alumina, titania, calcium carbonate, barium sulfate and the like are preferable, and the addition amount is preferably 0.05 to 20%.

  In particular, a monodispersed lubricant having an average particle size of 2.5 μm or less and a particle size ratio (major axis / minor axis) of 1.0 to 1.2 is preferable in terms of pinhole resistance of the film, Examples thereof include true spherical silica and true spherical titanium oxide. The average particle size and particle size ratio of the lubricant can be determined by observation with an electron microscope. The particle size distribution of the lubricant is sharp, and a standard deviation of 0.5 or less is desirable. Since the addition amount of the lubricant is related to the cutting property of the film manufacturing process, it is generally preferable to use a small amount when the particle size is large and a large amount when the particle size is small. For example, depending on the type of lubricant, the average particle size is 0.2 to 2.0 μm and is about 0.02 to 0.5%. Examples of the pigment include inorganic pigments such as alumina, titanium dioxide, and barium carbonate as white pigments. The average particle diameter of the pigment is preferably 2.5 μm or less for the same reason as that of the lubricant. The addition amount of the pigment is an amount necessary for achieving the coloring function, and is used within a range of about 3 to 50% by mass. A known method can be used as a method for adding the pigment.

  As a plasticizer of a polyester resin, for example, a molar ratio of an aromatic polybasic acid having 8 to 20 carbon atoms or an ester forming derivative thereof to an aliphatic polybasic acid having 2 to 20 carbon atoms or an ester forming derivative thereof is 0. A polycondensation of these polybasic acid components having a molecular weight of ˜2.0 and an aliphatic alcohol having 2 to 20 carbon atoms into a monobasic acid having 2 to 20 carbon atoms or an ester-forming derivative thereof and / or carbon The plasticizer for polyester resins which consists of polyester terminal-esterified with the monohydric alcohol of several 1-18 can be mentioned.

  In the resin composition, an antistatic agent disclosed in JP-A-5-222357 is incorporated into the resin composition for the purpose of preventing wrapping of the film around a roll in the film-forming process and prevention of static electricity damage such as adhesion of dirt to the film surface. The method of kneading can be applied as necessary. Further, conventionally known antibacterial agents disclosed in JP-A-11-48431, JP-A-11-138702 and the like can be used as necessary.

  The resin composition selected by the production method of the present invention can be widely used as a metal coating material. Although a metal is not specifically limited, Steel plates, such as tinplate and tin free steel, aluminum, copper, nickel, etc. are mentioned. Further, the coating on the metal may be either single-sided or double-sided. The thickness of the coating film when the composition of the present resin is coated on a metal is not particularly limited, but is preferably 1 to 300 μm. If it is less than 1 μm, sufficient impact resistance may not be obtained, and if it exceeds 300 μm, the economy is poor.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples.
As shown in Table 1, as the polyester resin (A), Unitika Co., Ltd. polyethylene terephthalate (PET, SA-1346P, SA-1325P, MA-1344), rubbery elastic body (B), Mitsui Sumitomo Polyolefin Ultra low density polyethylene (VLDPE, Evolue SP0540), manufactured by JSR Corporation, polyolefin resin (C) containing 10% by mass or less of functional group-containing unit, Sumitomo Chemical Co., Ltd. as an ethylene copolymer ) Ethylene-glycidyl methacrylate copolymer (E-GMA, GMA content: 6% by mass, Bond First 2C) and ethylene-methyl acrylate-glycidyl methacrylate copolymer (E-MA-GMA, GMA content: 3% by mass) , BF-7L), ethylene-vinyl acetate-glycidyl methacrylate Copolymer (E-VA-GMA, GMA content: 12% by mass, BF-7B) and ethylene-methyl acrylate-maleic anhydride copolymer (E-MA-MAH, MAH content: 2-4 mass) %, AX8390).
Table 1 shows the physical properties of the resins used in the examples and comparative examples.

（実施例１〜１４、比較例１〜４）

(Examples 1-14, Comparative Examples 1-4)

  Table 2 shows the resin temperature when kneading and extruding while changing the raw material composition and the setting conditions during kneading, and the dispersion diameter of the corresponding rubber-like elastic resin (B) and / or olefin copolymer resin (C). The result of the film forming property of the obtained pellets is shown. For kneading, a dry blend of a predetermined amount of polyester resin (A), rubber-like elastic resin (B), and olefin copolymer resin (C) was used, and a twin-screw kneading extruder (Toyo Seiki Seisakusho Co., Ltd.) This was performed by extruding with a twin screw extruder 2D25S). The resin temperature was determined by measuring the temperature of the resin melt-extruded from the kneading extruder. The domain diameter is a sample obtained by rapidly cooling and solidifying a resin composition melt-extruded from a kneading extruder with water, cleaved at a liquid nitrogen temperature, and immersed in m-xylene at 130 ° C. for 30 minutes to form a rubber-like elastic resin (B ) And / or olefin copolymer resin (C) was dissolved, and then SEM observation was performed. Table 2 shows 30 domains with large diameters existing in 5 fields of arbitrary cross section, and shows the average diameter of the domains (if the shape is not spherical, the maximum length from the end to the end of the domain is used). It was. Moreover, using this pellet, a single-layer film having a thickness of 25 μm was obtained with a biaxially extruded T die (extrusion temperature: 250 to 270 ° C.).

In Table 2, the average domain diameter and film formability were evaluated as follows.
(Domain average diameter) The average value of the 30 points is 0.8 μm or less: ◎, 0.8 to 1.0 μm: ○, 1.0 to 1.5 μm: Δ, 1.5 μm or more: x, domain is formed Not done: XX.
(Film-forming property) The surface property of the selected film is visually judged, and it is a uniform film surface property: ○, the film has unevenness such as foreign matter: Δ, the film has defects such as holes : X.

Examples 1 to 12 are examples within the scope of the present invention, but the average dispersion diameter of the resin composition obtained by melt-kneading extrusion is 0.8 μm or less, and the dispersion state is good. There was no problem in film forming. Example 13 is an example in which the kneading temperature of the resin composition is 50 ° C. or higher with respect to the melting point temperature of the polyester resin (A), and Example 14 was kneaded at a shear rate of 80 sec ⁻¹ during kneading. It is an example. In these cases, the average domain diameter was 0.8 to 1.0 [mu] m, but was slightly over 0.8 [mu] m, and there was no problem in film forming properties.

  On the other hand, although the comparative example 1 is an example which added 30 mass parts or more of rubber-like elastic-body resin (B) with respect to 100 mass parts of polyester resins (A), the domain was not formed but was not disperse | distributed. Comparative Example 2 is an example containing 10 mass% or more of an epoxy group-containing unit that reacts with the polyester resin (A) in the polyolefin-based copolymer resin (C), but it is not uniform even though it is partially finely dispersed, In addition, bumps and the like occurred and film formation was impossible. Comparative Example 3 is an example in which the ratio of the rubber-like elastic resin (B) and the polyolefin-based copolymer resin (C) was 10:10, and stable fine dispersion of the rubber-like elastic resin (B). Was impossible, and a uniform film could not be obtained. Comparative Example 4 is an example in which the ratio of the rubber-like elastic resin (B) and the polyolefin copolymer resin (C) was 10: 0.25, but fine dispersion was impossible and a uniform film was used. I couldn't get it.

(Examples 13 to 17, Comparative Examples 5 and 6)
0.35 mm heated to 260 ° C. using films obtained in Examples 3, 5, 9, 12 and films of Comparative Example 2 and Comparative Example 3 with no foreign matter or the like in a healthy part. The film was bonded to one side of a thickness of tin-free steel (TFS) and rapidly cooled to 100 ° C. or less within 10 seconds by water cooling. The room temperature resin-coated steel sheet thus obtained was immersed in an aqueous solution of 1.5% by mass of citric acid-1.5% by mass of sodium chloride for 24 hours, and then the length (mm) of the peeled film (average of 30 samples) ). Evaluation was performed as follows.

(Adhesion)
No peeling: ◎, 0.0 to 0.5 mm as ◯, 0.5 to 2.0 mm as Δ, and over 2.0 mm as x. The results of the adhesion test are shown in Table 3.
Further, the impact resistance of this metal plate was evaluated by a DuPont drop impact test (height 30 cm, r = 8 mm). The swelled portion of the sample after the test was placed in 1.0% saline, and the ERV value (mA) when a voltage of +6 V was applied was measured using the steel plate as the anode. The ERV value was evaluated according to the following index. Furthermore, after putting in a 0 degreeC constant temperature layer for 24 hours, the same impact resistance evaluation was performed and the impact resistance in low temperature was evaluated. Evaluation was performed as follows.
(Impact resistance)
All 30 samples were 0.01 mA or less: ◎, 1 to 5 were 0.01 mA or more: ○, 5 to 10 were 0.01 mA or more: Δ, and 7 or more were 0.01 mA or more: x. The respective results are shown in Table 3.

As shown in Table 3, the film made of the resin composition obtained by the production method according to the present invention exhibited excellent impact resistance even at adhesion, room temperature and low temperature. On the other hand, since Comparative Example 9 could not be finely dispersed, there were problems in adhesion, room temperature and low temperature. In Comparative Examples 5 and 6, since the fine dispersion was insufficient, the impact resistance at low temperature was lowered.

Patent applicant: Nippon Steel Corporation
Attorney Attorney Shiina and others 1

Claims (4)

From polyester resin (A), rubber-like elastic resin (B), and polyolefin copolymer resin (C) having a functional group-containing unit capable of covalently bonding without forming polyester and water molecules as a by-product A resin composition having a structure in which the rubber-like elastic resin (B) is finely dispersed in the polyester resin (A) by melt kneading, and the rubber-like elastic body with respect to 100 parts by mass of the polyester resin (A) The resin (B) is 1 to 30 parts by mass, the polyolefin copolymer resin (C) is 0.1 to 10 parts by mass, and the rubber-like elastic resin (B) and the polyolefin copolymer resin. A resin composition for a metal-coated film excellent in impact resistance, wherein the mixing ratio of (C) is in the range of 10: 1 to 10: 5. The rubber-like elastic resin (B) is 1 to 30 parts by mass with respect to 100 parts by mass of the polyester resin (A), the polyolefin copolymer resin (C) is 0.1 to 10 parts by mass, and rubber When a resin composition is produced by melt-kneading a resin composition in which the mixing ratio of the elastic elastomer resin (B) and the polyolefin copolymer resin (C) is in the range of 10: 1 to 10: 5, the resin temperature A method for producing a resin composition for a metal-coated film excellent in impact resistance, characterized in that the melting point of the polyester resin (A) is in the range of + 5 ° C. to + 50 ° C. and a shear rate of at least 80 sec ⁻¹ is applied. The polyolefin copolymer resin containing 10 mass% or less of an epoxy group-containing unit as a functional group unit capable of covalently bonding the polyolefin copolymer resin (C) to polyester. Of producing a resin composition for a metal-coated film having excellent impact resistance. The intrinsic viscosity of the polyester resin is in the range of 0.5 to 1.5 dl / g, the moisture content is 200 ppm or less, and the end of the polyester chain is a carboxylic acid residue (—COOH) and / or a hydroxyl group (—OH). The method for producing a resin composition for a metal-coated film having excellent impact resistance according to claims 2 and 3.