Laminate

Abstract

To provide a laminate containing a polyester resin that contains a recycled polyester as a raw material and capable of preventing an oligomer from being deposited on the surface even when stored for a long time in a high temperature and high humidity environment.　Provided is a laminate including: a base material layer formed with a polyester resin containing a recycled polyester; and a resin layer laminated on at least one surface of the base material layer and formed with a fluorine-based resin containing hydrophobic particles.

Description

Laminate

[0001] The present technology relates to a laminate, and more specifically to a laminate using, as a raw material, a polyester resin containing recycled polyester recovered from packaging materials such as used PET bottles so that it can be reused.

[0002] For various industrial applications such as films, sheets, and packaging materials, plastic materials produced from raw materials derived from petroleum, a fossil fuel, are primarily used due to their ease of molding and cost. Examples of such plastic materials include polyester resins, polyolefin resins, and polyamide resins. Among these, polyester resins are widely used due to their excellent mechanical properties, chemical stability, heat resistance, transparency, and low cost.

[0003] In recent years, there has been a growing movement to reduce the use of fossil fuels and CO2 emissions in various applications of such fossil fuel-derived plastic materials in consideration of the environment. As an attempt to reduce the use of such fossil fuels, a method has been proposed in which polyester resin recovered from used packaging materials such as PET bottles is reused and recycled as recycled polyester for molding packaging materials again (see, for example, Patent Documents 1 and 2). Patent Documents 1 and 2 propose a reduction in CO2 emissions by recovering used products formed using fossil fuel-derived polyester resins and using the reused polyester resin as part of the packaging material.

[0004] JP 2011-256328 A JP 2012-41463 A

[0005] Oligomer precipitation phenomenon of PET-laminated steel sheets for containers under moist heat treatment. Yamanaka, Y; Kitagawa, J; Kojima, K; Nakano, H., Surface Technology, Vol. 69, No. 7, 2018, pp. 302-307.

[0006] However, when polyester resins are kept in a high-temperature, high-humidity environment for a long time during the manufacturing process or during use, the resulting oligomers precipitate on the resin surface, resulting in a decrease in heat resistance. Polyester resins usually maintain transparency because polyester oligomers such as cyclic trimers remaining in the polyester polymer chain are dispersed, but when heated at high temperatures, the polyester polymer crystallizes, causing the oligomers in the polyester polymer chain to be expelled from the crystals and precipitate on the resin surface (Non-Patent Document 1).

[0007] In particular, when recycled polyester resin is kept in a high-temperature, high-humidity environment for a long period of time, it becomes noticeable that even more oligomers precipitate than in virgin polyester resin before recycling.

[0008] In light of the above, the present technology aims to provide a laminate that uses polyester resin, including recycled polyester, as a raw material and that can prevent oligomers from precipitating on the surface even when kept in a high-temperature, high-humidity environment for a long period of time.

[0009] The present engineers have found that a laminate having a specific configuration can prevent oligomer deposition on the surface.

[0010] That is, the present technology provides a laminate including: a substrate layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluororesin containing hydrophobized particles, laminated on at least one surface of the substrate layer. The hydrophobized particles may have a DBA value of 250 meq / kg or less. The fluororesin may be a tetrafluoroethylene resin. The recycled polyester may be recycled polyethylene terephthalate. The fluororesin may be a cured product of a fluororesin composition including a reactive functional group-containing tetrafluoroethylene polymer and a curing agent. The curing agent may include an isocyanurate polyisocyanate and not include an adduct polyisocyanate. The laminate may have a tensile strength retention rate of 70% or more after aging at 200°C for 6 hours. The laminate may be used under conditions of 175°C and 85 bar. The present technology also provides a release film including: a base layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluorine-based resin containing hydrophobic particles, laminated on at least one surface of the base layer.

[0011] This technology provides a laminate that uses a polyester resin containing recycled polyester as a raw material and that can prevent oligomers from precipitating on the surface even when maintained in a high-temperature, high-humidity environment for a long period of time. Note that the effects of this technology are not necessarily limited to the effects described herein and may be any of the effects described in this specification.

[0012] Fig. 1 is a diagram showing an example of the structure of a laminate according to the present technology; Fig. 2 is a diagram showing a test piece placed on a heat press machine in an evaluation test for oligomer prevention; Fig. 3 is a diagram showing an example of a method for using a release film according to the present technology in transfer molding; Fig. 4 is an enlarged image taken by a laser microscope of the surface of a SUS plate in Example 1; Fig. 5 is an enlarged image taken by a laser microscope of the surface of a SUS plate in Comparative Example 1; Fig. 6 is an enlarged image taken by a laser microscope of the surface of a SUS plate in Comparative Example 2.

[0013] Hereinafter, embodiments for implementing the present technology will be described in detail. Note that the embodiments described below are examples of typical embodiments of the present technology, and the present technology is not limited to these embodiments. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​described before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types.

[0014] 1. Laminate

[0015] A laminate according to a first embodiment of the present technology includes a substrate layer formed from a polyester resin containing recycled polyester, and a resin layer formed from a fluororesin containing hydrophobic particles, laminated on at least one surface of the substrate layer. The resin layer may be laminated on both surfaces of the substrate layer. An example of the structure of a laminate according to the present technology is shown in FIG. 1. As shown in FIG. 1, a laminate 100 according to the present technology includes a substrate layer 101 and a resin layer 102 and a resin layer 103 laminated on both surfaces thereof. The substrate layer 101 is formed from a polyester resin containing recycled polyester. The two resin layers 102 and 103 are formed from fluororesins containing hydrophobic particles. The two resin layers 102 and 103 may be formed from the same fluororesin or different fluororesins.

[0016] The laminate of the present technology is composed of the base material layer and the resin layer formed on at least one side of the base material layer, and therefore can prevent oligomers from precipitating on the surface even when kept in a high-temperature, high-humidity environment for a long period of time.

[0017] The laminate of the present technology will be described in more detail below.

[0018] [Base material layer]

[0019] The substrate layer is formed from a polyester resin containing recycled polyester. Examples of recycled polyester include material recycled polyester, mechanically recycled polyester, and chemically recycled polyester. Material recycled polyester refers to polyester obtained by sorting, crushing, washing, etc., used polyester molded products such as bottles, containers, and films to remove contaminants and foreign matter, and then flaking them. Mechanically recycled polyester refers to polyester obtained by treating flakes of material recycled polyester at high temperature and reduced pressure for a certain period of time to remove contaminants from the resin and to adjust the degree of polymerization by repolymerizing a portion of the polyester. Chemically recycled polyester refers to polyester obtained by decomposing polyester to the monomer level and repolymerizing the monomer.

[0020] Examples of polyester types used as this recycled polyester include polyesters whose dicarboxylic acid component is terephthalic acid and whose diol component is ethylene glycol, i.e., polyesters whose main component is polyethylene terephthalate (PET); polyesters whose dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid and whose diol component is ethylene glycol, i.e., polyesters whose main component is polyethylene naphthalate (PEN); and polyesters whose dicarboxylic acid component is 2,5-furandicarboxylic acid and whose diol component is ethylene glycol, i.e., polyesters whose main component is polyethylene furanoate (PEF).

[0021] Examples of dicarboxylic acid components other than those mentioned above include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, and ester derivatives thereof.

[0022] Examples of diol components other than ethylene glycol include 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, 5-methylol-5-ene tetyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamantanediol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, pentaerythritol, and bis-β-hydroxyethyl terephthalate (BHET).

[0023] As long as the properties of the present technology are not impaired, the polyester may contain a monomer other than the dicarboxylic acid component and the diol component, and the content thereof may be preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 3 mol % or less, based on all constituent units.

[0024] The polyester may be polymerized using a polymerization catalyst, such as a manganese (Mn) catalyst, a titanium (Ti) catalyst, an aluminum (Al) catalyst, a lithium (Li) catalyst, a germanium (Ge) catalyst, or an antimony (Sb) catalyst.

[0025] In the base layer, the content of recycled polyester in the polyester resin is not particularly limited, but can be 5% by mass to 100% by mass relative to the mass of the polyester resin.

[0026] The thickness of the substrate layer may be, for example, preferably 10 μm to 80 μm, more preferably 15 μm to 75 μm, and even more preferably 20 μm to 70 μm.

[0027] [Resin layer]

[0028] The resin layer is laminated on at least one surface of the base layer, and is made of a fluororesin. The fluororesin contains hydrophobic particles.

[0029] <Fluorine-based resin>

[0030] The fluororesin preferably contains a tetrafluoroethylene resin, and more preferably contains a tetrafluoroethylene resin as a main component. "Tetrafluoroethylene resin as a main component" means that the fluororesin is composed solely of tetrafluoroethylene resin, or that the amount of tetrafluoroethylene resin is the largest among the components contained in the fluororesin. More specifically, "tetrafluoroethylene resin as a main component" means that the content of tetrafluoroethylene resin is 50 mass% or more relative to the mass of the fluororesin. Furthermore, the fluororesin may be, for example, a cured product of a fluororesin composition containing a reactive functional group-containing fluoropolymer and a curing agent.

[0031] The reactive functional group-containing fluoropolymer contained in the fluororesin composition may be a fluoropolymer that can be cured with the curing agent. The reactive functional group and the curing agent may be appropriately selected by a person skilled in the art. The reactive functional group may be, for example, a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, or a silyl group, and is preferably a hydroxyl group. These groups allow the reaction to proceed smoothly to obtain the cured product. Of these reactive functional groups, a hydroxyl group is particularly suitable for the reaction to obtain the cured product. That is, the reactive functional group-containing fluoropolymer may preferably be a hydroxyl group-containing fluoropolymer, and more preferably a hydroxyl group-containing tetrafluoroethylene polymer.

[0032] The fluorine-containing unit of the reactive functional group-containing fluorine-based polymer is preferably the fluorine-containing unit based on perfluoroolefin.The fluorine-containing unit based on this perfluoroolefin can more preferably be based on one, two or three selected from tetrafluoroethylene (tetrafluoroethylene, hereinafter referred to as "TFE"), hexafluoropropylene (HFP) and perfluoro(alkyl vinyl ether) (PAVE).Preferably, among the fluorine-containing units based on this perfluoroolefin, the fluorine-containing unit based on TFE is the most abundant.

[0033] The hydroxyl value of the reactive functional group-containing fluoropolymer (particularly the hydroxyl value of the hydroxyl group-containing fluoropolymer) is preferably 10 mgKOH / g to 300 mgKOH / g, more preferably 10 mgKOH / g to 200 mgKOH / g, and even more preferably 10 mgKOH / g to 150 mgKOH / g. When the hydroxyl value of the reactive functional group-containing fluoropolymer is equal to or greater than the lower limit of the above-mentioned range, the curability of the resin composition can be improved. Furthermore, when the hydroxyl value of the reactive functional group-containing fluoropolymer is equal to or less than the upper limit of the above-mentioned range, the cured product of the resin composition can be suitable for multiple moldings. The hydroxyl value is obtained by measurement according to JIS K 0070.

[0034] The acid value of the reactive functional group-containing fluoropolymer (particularly the acid value of the hydroxyl group-containing fluoropolymer) is preferably 0.5 mgKOH / g to 100 mgKOH / g, more preferably 0.5 mgKOH / g to 50 mgKOH / g. When the acid value of the reactive functional group-containing fluoropolymer is equal to or greater than the lower limit of the above-mentioned range, the curability of the resin composition can be improved. Furthermore, when the acid value of the reactive functional group-containing fluoropolymer is equal to or less than the upper limit of the above-mentioned range, the cured product of the resin composition can be suitable for multiple moldings.

[0035] The reactive functional group of the reactive functional group-containing fluoropolymer may be introduced into the fluoropolymer by copolymerizing a monomer having the reactive functional group with a fluorine-containing monomer (particularly the perfluoroolefin). That is, the reactive functional group-containing fluoropolymer may contain polymerization units based on the reactive functional group-containing monomer and polymerization units based on the fluorine-containing monomer (particularly the perfluoroolefin).

[0036] When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group may preferably be a hydroxyl group-containing vinyl ether or a hydroxyl group-containing allyl ether. Examples of hydroxyl group-containing vinyl ethers include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether, and 6-hydroxyhexyl vinyl ether. Examples of hydroxyl group-containing allyl ethers include 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Alternatively, the monomer having the reactive functional group may be a hydroxyalkyl ester of (meth)acrylic acid, such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. One or a combination of two or more of these compounds may be used as the monomer having the reactive functional group. When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group is more preferably a hydroxyl group-containing vinyl ether, and particularly preferably 4-hydroxybutyl vinyl ether and / or 2-hydroxyethyl vinyl ether, from the viewpoint of the curability of the resin composition.

[0037] When the reactive functional group is a carboxyl group, the monomer having the reactive functional group may preferably be an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid.When the reactive functional group is an amino group, the monomer having the reactive functional group may be, for example, an amino vinyl ether or an allylamine.When the reactive functional group is a silyl group, the monomer having the reactive functional group may preferably be a silicone vinyl monomer.

[0038] The fluorine-containing monomer is preferably a perfluoroolefin. Examples of perfluoroolefins include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE). Preferably, the fluorine-containing monomer includes TFE.

[0039] Preferably, the reactive functional group-containing fluoropolymer may contain, in addition to polymerized units based on the reactive functional group-containing monomer and polymerized units based on the fluorine-containing monomer, polymerized units based on a fluorine-free vinyl monomer. The fluorine-free vinyl monomer may be, for example, one or a combination of two or more selected from the group consisting of vinyl carboxylic acid esters, alkyl vinyl ethers, and non-fluorinated olefins. Examples of vinyl carboxylic acid esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, vinyl benzoate, and vinyl para-t-butylbenzoate. Examples of alkyl vinyl ethers include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether. Examples of non-fluorinated olefins include ethylene, propylene, n-butene, and isobutene. The reactive functional group-containing fluorine-based polymer may contain, in addition to the polymerization units based on the reactive functional group-containing monomer and the polymerization units based on the fluorine-containing monomer which is a perfluoroolefin, polymerization units based on a fluorine-based monomer other than a perfluoroolefin, such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinyl ether.

[0040] The reactive functional group-containing fluoropolymer may be, for example, a TFE / non-fluorinated olefin / hydroxybutyl vinyl ether copolymer, a TFE / carboxylic acid vinyl ester / hydroxybutyl vinyl ether copolymer, or a TFE / alkyl vinyl ether / hydroxybutyl vinyl ether copolymer. More specifically, the reactive functional group-containing fluoropolymer may be a TFE / isobutylene / hydroxybutyl vinyl ether copolymer, a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer, or a TFE / VdF / hydroxybutyl vinyl ether copolymer. The reactive functional group-containing fluoropolymer is particularly preferably a TFE / isobutylene / hydroxybutyl vinyl ether copolymer or a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer. The reactive functional group-containing fluoropolymer may be, for example, a Zeffle GK series product.

[0041] The curing agent contained in the fluororesin composition may be appropriately selected by those skilled in the art depending on the type of reactive functional group contained in the reactive functional group-containing fluoropolymer. When the reactive functional group is a hydroxyl group, the curing agent may be preferably one or a combination of two or more selected from an isocyanate-based curing agent, a melamine resin, a silicate compound, and an isocyanate-group-containing silane compound. When the reactive functional group is a carboxyl group, the curing agent may be preferably one or a combination of two or more selected from an amino-based curing agent and an epoxy-based curing agent. When the reactive functional group is an amino group, the curing agent may be one or a combination of two or more selected from a carbonyl-group-containing curing agent, an epoxy-based curing agent, and an acid anhydride-based curing agent. The content of the curing agent in the fluororesin composition may be, for example, preferably 15 to 30 parts by mass, more preferably 10 to 25 parts by mass, per 100 parts by mass of the reactive functional group-containing fluoropolymer. These numerical ranges also apply to the content of the curing agent in the cured product of the fluororesin composition. The content of the curing agent may be measured by pyrolysis gas chromatography (Py-GC / MS).

[0042] In one embodiment of the present technology, the reactive functional group contained in the reactive functional group-containing fluoropolymer may be a hydroxyl group, and the curing agent may be an isocyanate-based curing agent. In this embodiment, the isocyanate-based curing agent is preferably a hexamethylene diisocyanate (HDI)-based polyisocyanate. The content of the HDI-based polyisocyanate in the fluororesin composition may be, for example, preferably 15 to 50 parts by mass, more preferably 20 to 40 parts by mass, and even more preferably 23 to 35 parts by mass, per 100 parts by mass of the reactive functional group-containing fluoropolymer. These numerical ranges also apply to the content of the HDI-based polyisocyanate in a cured product of the fluororesin composition.

[0043] Examples of HDI-based polyisocyanates include isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates. In the present technology, the isocyanate-based curing agent preferably contains an isocyanurate-type polyisocyanate, more preferably contains an isocyanurate-type polyisocyanate and does not contain an adduct-type polyisocyanate. When an isocyanurate-type polyisocyanate is used as the curing agent, the content of the isocyanurate-type polyisocyanate may be, for example, 10 parts by mass to 50 parts by mass, preferably 15 parts by mass to 40 parts by mass, and more preferably 20 parts by mass to 30 parts by mass, per 100 parts by mass of the reactive functional group-containing fluoropolymer. These numerical ranges also apply to the content of the isocyanurate-type polyisocyanate in the cured product of the tetrafluoroethylene-based resin composition. The content of these isocyanurate-type polyisocyanates may be determined by pyrolysis gas chromatography (Py-GC / MS).

[0044] <Hydrophobicized particles>

[0045] The fluororesin contains hydrophobized particles, which makes it possible to more effectively suppress or prevent oligomer deposition on the surface even when a polyester resin containing recycled polyester is used.

[0046] The particles may be inorganic or organic. Examples of inorganic particles include silicon dioxide (particularly amorphous silicon dioxide), calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Examples of organic particles include crosslinked polymer particles and calcium oxalate. In the present technology, the particles are preferably inorganic particles, more preferably silicon dioxide particles, and even more preferably amorphous silicon dioxide. The amorphous silicon dioxide may be sol-gel type silica. Examples of amorphous silicon dioxide include amorphous silicon dioxide from the Sylysia series.

[0047] The average particle size of these particles may be preferably 1 μm to 10 μm, more preferably 2 μm to 9 μm. The average particle size may be measured according to a laser diffraction particle size analysis method.

[0048] As an example of hydrophobic particles, for example, hydrophobic silicon dioxide can be produced by subjecting the silanol groups present on the surface of amorphous silicon dioxide synthesized by a dry method or amorphous silicon dioxide synthesized by a wet method to a surface treatment to impart hydrophobicity.Such surface treatments include, for example, coating the surface of amorphous silicon dioxide with waxes such as paraffin wax, carnauba wax, amide wax, and polyethylene wax.The obtained hydrophobic silicon dioxide exhibits hydrophobicity because the silanol groups on the surface of the amorphous silicon dioxide are covered with a wax layer.Other examples include adding an organic silicon compound such as tetramethylsilane, vinyltrichlorosilane, vinyltrimethoxysilane, epoxy group-containing silane, or dimethyldichlorosilane, or an amino group-containing organic compound, to amorphous silicon dioxide, and modifying it by hydrolysis or the like. The hydrophobic silicon dioxide obtained in this manner is formed by chemically reacting the silanol groups on the surface of amorphous silicon dioxide with an organosilicon compound or the like, and has hydrophobic groups such as alkyl groups on its surface.

[0049] Examples of such hydrophobic silicon dioxide include those having the product names "AEROSIL R972," "AEROSIL R974," "AEROSIL R976," "AEROSIL R104," "AEROSIL R106," "AEROSIL R202," "AEROSIL R805," "AEROSIL R812," "AEROSIL R812S," "AEROSIL R816," "AEROSIL R7200," "AEROSIL R8200," and "AEROSIL R9200" (all manufactured by Nippon Aerosil Co., Ltd.), and those having the product names "Sylohorbic 200," "Sylohorbic 704," "Sylohorbic 505," and "Sylohorbic 603" (all manufactured by Fuji Silysia Chemical Ltd.).

[0050] Examples of titanium oxide include those under the trade name "AEROXIDE TiO2 T805" (manufactured by Evonik Degussa), etc. Examples of aluminum oxide include those under the trade name "AEROXIDE Alu C" (manufactured by Evonik Degussa), etc., which are fine particles whose particle surfaces have been made hydrophobic by treating them with a silane coupling agent.

[0051] The content of the hydrophobic particles may be, for example, 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 10 to 30 parts by mass, relative to 100 parts by mass of the reactive functional group-containing fluoropolymer. These numerical ranges also apply to the content of the hydrophobic particles in the cured product of the tetrafluoroethylene-based resin composition. The content of the hydrophobic particles may be measured by thermogravimetric analysis (TGA).

[0052] <DBA adsorption amount (DBA value)>

[0053] The degree of hydrophobicity of hydrophobized particles is expressed by the amount of di-n-butylamine (DBA) adsorption (hereinafter referred to as the DBA value). Silicon dioxide particles exhibit hydrophilicity due to the presence of a large number of hydroxyl groups on their surface. DBA adsorbs to the hydroxyl groups on the surface of silicon dioxide particles via ionic bonds. The DBA adsorption amount serves as a measure of the degree of hydrophobicity. For example, in hydrophobic silicon dioxide treated with silicone oil, the hydroxyl groups present on the silicon dioxide surface are covered with the silicone oil or disappear through reaction. Any hydroxyl groups remaining on the surface of hydrophobic silicon dioxide will bond with DBA, and the amount of bonded hydroxyl groups can be determined. A lower DBA adsorption amount indicates that the hydroxyl groups have been converted into siloxane bonds, indicating higher hydrophobicity.

[0054] The hydrophobized particles may have a DBA value of preferably 250 meq / kg or less, more preferably 175 meq / kg or less, even more preferably 70 meq / kg or less, and even more preferably 65 meq / kg or less.

[0055] The DBA value is measured, for example, by the following method. Step (i): 250 mg of a dried sample is weighed out, 50 ml of N / 500-di-n-butylamine solution (petroleum benzine solution) is added, and the mixture is left to stand at 20°C for approximately 2 hours. Step (ii): 5 ml of chloroform and 2 to 3 drops of indicator (crystal violet) are added to 25 ml of this supernatant, and the mixture is titrated with N / 100 perchloric acid solution (acetic anhydride solution) until the purple color changes to blue, and the titration value at this point is designated as A. Step (iii): A blank experiment is conducted separately, and the titration value is designated as B. The DBA adsorption amount is calculated using the following formula: DBA adsorption amount (m mol / kg) = 80(B - A)f, where f is the titer of the N / 100 perchloric acid solution.

[0056] The fluororesin composition before curing may contain a solvent. The type of solvent may be appropriately selected by those skilled in the art. Examples of the solvent include butyl acetate, ethyl acetate, and methyl ethyl ketone (also known as MEK). For example, a mixture of these three types may be used as the solvent.

[0057] <Other additives>

[0058] The fluororesin may contain other additives depending on the application. For example, when the laminate is used for mold release, the fluororesin may contain a mold release promoter. Examples of the mold release promoter include amino-modified methylpolysiloxane, epoxy-modified methylpolysiloxane, carboxy-modified methylpolysiloxane, and carbinol-modified methylpolysiloxane. Preferably, the mold release promoter is amino-modified methylpolysiloxane.

[0059] The amount of the release accelerator may be, for example, 0.01 to 3 parts by mass, preferably 0.05 to 2 parts by mass, and more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. These numerical ranges also apply to the content of the release accelerator in the cured product of the tetrafluoroethylene resin composition.

[0060] The fluororesin composition before curing can be produced by mixing and stirring the above-described components by means known to those skilled in the art. For the mixing and stirring, a mixer such as a high-speed mixer, a homomixer, or a paint shaker can be used. For the mixing and stirring, a dissolver such as an edge turbine type high-speed dissolver can also be used.

[0061] The thickness of the resin layer formed from the fluorine-based resin may be, for example, preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and even more preferably 3 μm to 10 μm.

[0062] [Physical properties of laminate]

[0063] <Tensile strength retention rate>

[0064] In the laminate, the tensile strength retention after aging at 200°C for 6 hours can be preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and even more preferably 95% or more.

[0065] The tensile strength retention rate was measured by taking the average tensile strength of five laminate samples before heating to 200°C in the tensile strength measurement and using it as the sample before aging (blank, 0 hr). Separately, five laminate samples were placed in a hot air oven set at 200°C, removed after 6 hours, and left in an environment of 23°C and 50% humidity for 24 hours to be used as the aged sample. The tensile strength was measured at 23°C using a Tensilon universal testing machine (manufactured by A&D Co., Ltd.) in accordance with JIS K 7161.

[0066] As an evaluation criterion, the smaller the degree of decrease in the measured value after aging compared to the blank measured value, the more excellent the heat resistance was judged to be. A tensile strength retention of 70% or more was judged to be preferable, 80% or more was more preferable, 90% or more was even more preferable, and 95% or more was even more preferable.

[0067] [Method of manufacturing laminate]

[0068] The method for producing a laminate includes a coating step of coating at least one surface of a substrate layer formed from a polyester resin containing recycled polyester with a fluororesin composition containing hydrophobic particles, and a curing step of curing the fluororesin composition after the coating step. The above description applies to the substrate layer and fluororesin composition used in the coating step, so further description is omitted. The coating step may be performed as appropriate by those skilled in the art to achieve a desired layer thickness. For example, the fluororesin composition may be applied to at least one surface of the substrate layer by a gravure roll method, a reverse roll method, an offset gravure method, a kiss coat method, a reverse kiss coat method, a wire bar coating method, a spray coat method, or an impregnation method. The apparatus for applying the composition using these methods may be appropriately selected by those skilled in the art. The curing step includes heating the fluororesin composition, for example, preferably at 100°C to 200°C, more preferably at 120°C to 180°C, for example, preferably for 10 seconds to 240 seconds, more preferably for 30 seconds to 120 seconds. The heating cures the fluororesin composition. The resulting cured product forms the resin layer. The amount of the fluororesin composition to be applied may be appropriately determined by those skilled in the art depending on the thickness of the resin layer to be formed.

[0069] [Uses of the laminate]

[0070] The laminate of the present technology may be used for release purposes. More specifically, it may be used as a release film in the encapsulation (molding) of flip-chip-connected semiconductor elements. Such a release film may be used, for example, by being disposed between a mold and a flip-chip resin (underfill resin) in flip-chip connection. Furthermore, the release film may be used, for example, by being disposed between a mold and a resin in transfer molding for encapsulating flip-chip-connected semiconductor elements. The encapsulation (molding) temperature in the encapsulation (molding) in which the release film is used may be, for example, 100°C to 250°C, and preferably 120°C to 200°C.

[0071] An example of a method for using the release film of the present technology in transfer molding used for sealing a semiconductor element with flip-chip connection will be described with reference to FIG.

[0072] An example of a method for using the release film of the present technology in transfer molding will be described with reference to FIG. 3 . As shown in FIG. 3A , a release film 100 of the present technology is placed between an upper mold 201 and a lower mold 203 on which a semiconductor element mounting substrate 202 is placed. Next, as shown in FIG. 3B , with the release film 100 attached to the inner surface of the mold 201, the upper mold 201 is brought into contact with the substrate 202 and the lower mold 203. Next, as shown in FIG. 3C , a resin 204 is introduced between the upper mold 201 and the substrate 202, and then the resin 204 is cured. After curing, the upper mold 201 is released from the substrate 202 as shown in FIG. 3D . The release film of the present technology has excellent releasability, allowing the cured resin 204 to be smoothly released from the upper mold 201 in the step of FIG. 3D . If the release film does not have good releasability, the release film 250 may stick to the hardened resin 204, as shown in FIG. 3(E), for example.

[0073] In such transfer molding, resins used to encapsulate semiconductor elements include epoxy resins, silicone resins, etc. The release film of the present technology can be used to encapsulate semiconductor elements using such resins.

[0074] The release film of the present technology can be used, for example, preferably for two or more moldings, more preferably for four or more moldings, even more preferably for five or more moldings, even more preferably for six or more moldings, and particularly preferably for eight or more moldings. The release film of the present technology can be used, for example, preferably for two to twenty moldings, more preferably for four to fifteen moldings, even more preferably for five to fifteen moldings, even more preferably for six to fifteen moldings, and particularly preferably for eight to twelve moldings. The release film of the present technology maintains its performance and is tear-resistant through multiple mold releases. Therefore, the release film of the present technology can be used for multiple moldings. This reduces sealing (molding) costs.

[0075] 2. Release film

[0076] A release film according to a second embodiment of the present technology includes a substrate layer formed from a polyester resin containing recycled polyester, and a resin layer formed from a fluororesin containing hydrophobic particles laminated on at least one surface of the substrate layer. All of the descriptions regarding the substrate layer and the resin layer described in "1. Laminate" above in 1. also apply to the release film. Therefore, a description of the substrate layer and the resin layer will be omitted.

[0077] [Method of producing release film]

[0078] The present technology provides a method for producing the above-described release film. The production method includes a coating step of coating at least one surface of a substrate layer formed from a polyester resin containing recycled polyester with a fluororesin composition containing hydrophobized particles, and a curing step of curing the fluororesin composition after the coating step. The above description applies to the substrate layer and fluororesin composition used in the coating step, so further description is omitted. The coating step may be performed appropriately by those skilled in the art to achieve a desired layer thickness. For example, the fluororesin composition may be applied to at least one surface of the substrate layer by a gravure roll method, a reverse roll method, an offset gravure method, a kiss coat method, a reverse kiss coat method, a wire bar coat method, a spray coat method, or an impregnation method. Apparatus for coating by these methods may be appropriately selected by those skilled in the art. The curing step includes heating the fluororesin composition, for example, preferably at 100° C. to 200° C., more preferably at 120° C. to 180° C., for example, preferably for 10 seconds to 240 seconds, more preferably for 30 seconds to 120 seconds. The heating cures the fluororesin composition.

[0079] The present technology can also employ the following configurations. [1] A laminate comprising: a substrate layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluororesin containing hydrophobized particles, laminated on at least one surface of the substrate layer. [2] The laminate according to [1], in which the hydrophobized particles have a DBA value of 250 meq / kg or less. [3] The laminate according to [1] or [2], in which the fluororesin is a tetrafluoroethylene resin. [4] The laminate according to any one of [1] to [3], in which the recycled polyester is recycled polyethylene terephthalate. [5] The laminate according to any one of [1] to [4], in which the fluororesin is a cured product of a fluororesin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent. [6] The laminate according to [5], in which the curing agent contains an isocyanurate polyisocyanate and does not contain an adduct polyisocyanate. [7] The laminate according to any one of [1] to [6], which has a tensile strength retention rate of 70% or more after aging for 6 hours at 200° C. [8] The laminate according to any one of [1] to [7], which is used under conditions of 175° C. and 85 bar. [9] A release film comprising: a base layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluorine-based resin containing hydrophobic particles, laminated on at least one surface of the base layer.

[0080] The present technology will be described in more detail below based on examples. Note that the examples described below are representative examples of the present technology, and the scope of the present technology is not limited to these examples.

[0081] [Oligomer prevention]

[0082] Figure 2 shows a test piece placed on a heat press in an evaluation test for oligomer prevention. A 50 mm x 50 mm test piece 21 was cut out from the laminate of the following Examples and Comparative Examples, and the test piece 21 was sandwiched between two 150 mm x 70 mm SUS plates 22 as shown in Figure 2. The test piece 21 sandwiched between the SUS plates 22 was then placed between an upper plate 23 and a lower plate 24 of a heat press (LP-S-50 manufactured by LABTECH ENGINEERING COMPANY LTD.). The upper plate 23 and the lower plate 24 were each pressed in the direction of the arrows at a temperature of 175°C and a press pressure of 85 bar for 5 minutes.

[0083] After pressing, the test piece 21 was peeled off from the SUS plate 22. The precipitation of oligomers was evaluated by a magnified image of the surface of the SUS plate 22 from which the test piece 21 was peeled off, photographed with a laser microscope under the following photographing conditions: Photographing device: Laser microscope (OLS5000 model, manufactured by OLIMPUS) Objective lens: 50x Actual magnification: 1178x

[0084] The sticking was evaluated based on the ease of peeling the test piece 21 from the SUS plate 22. The evaluation criteria were as follows:

[0085] <Oligomer precipitation> A: No oligomers B: Some oligomers detected C: Much oligomers detected

[0086] <Stickness> A: No sticking B: Slight resistance C: Sticking

[0087] Example 1

[0088] Preparation of Fluorine-Based Resin Composition (A-1)

[0089] A fluororesin composition (A-1) was prepared by mixing and stirring 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene resin composition (Zeffle (registered trademark) GK570, manufactured by Daikin Industries, Ltd., of which 65% by mass is the hydroxyl group-containing tetrafluoroethylene resin), 10.58 parts by mass of silicon dioxide particles surface-treated with polydimethylsiloxane (Sylohorbic 704 (DBA value: 65 meq / kg), manufactured by Fuji Silysia Chemical Ltd.), 14.30 parts by mass of an isocyanurate-type polyisocyanate (curing agent, Sumidur (registered trademark) N3300, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 5.70 parts by mass of butyl acetate, 42.10 parts by mass of ethyl acetate, and 84.20 parts by mass of methyl ethyl ketone.

[0090] A film (thickness: 38 μm, glass transition temperature: 110° C.) formed from a polyethylene terephthalate resin containing recycled polyethylene terephthalate was prepared as a substrate layer. Fluorine-based resin composition (A-1) was applied to both surfaces of the film. These applications were carried out using a kiss-reverse type coating device. After the application, the fluorine-based resin composition (A-1) was cured by heating at 150° C. for 60 seconds, thereby obtaining a release film in which resin layers were laminated on both surfaces of a polyethylene terephthalate resin film containing recycled polyethylene terephthalate (hereinafter referred to as "the release film of Example 1").

[0091] The thickness of the release film of Example 1 was 53±5 μm. The thickness of the base material layer in the release film of Example 1 was 38 μm±4 μm. The thickness of the resin layer of the release film of Example 1 was 5±1 μm. The tensile strength retention rate after aging at 200° C. for 6 hours was 97% (tensile strength before heating: 158 MPa, tensile strength after heating: 153 MPa). Figure 4 is a surface image of the resin layer side of the release film of Example 1. As shown in Figure 4, there was no precipitation of oligomers on the SUS plate surface, and the film did not stick to the SUS plate.

[0092] (Comparative Example 1)

[0093] Preparation of Fluorine-Based Resin Composition (RA-1)

[0094] Instead of silicon dioxide particles surface-treated with polydimethylsiloxane (Silophobic 704, manufactured by Fuji Silysia Chemical Ltd.), 11.47 parts by mass of silicon dioxide particles that had not been hydrophobized (Silysia 380 (DBA value: 500 meq / kg), manufactured by Fuji Silysia Chemical Ltd.), 10.00 parts by mass of isocyanurate-type polyisocyanate (curing agent, Sumidur (registered trademark) N3300, manufactured by Sumitomo Bayer Urethane Co., ... A fluororesin composition (RA-1) was prepared in the same manner as in the preparation of the fluororesin composition (A-1), except that 7.79 parts by mass of butyl acetate (curing agent, Sumidur (registered trademark) N3300, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by mass of adduct polyisocyanate (curing agent, Duranate (registered trademark) AE700-100, manufactured by Asahi Kasei Corporation), 6.18 parts by mass of butyl acetate, 44.62 parts by mass of ethyl acetate, and 89.24 parts by mass of methyl ethyl ketone were mixed, and a coating film of the resin composition was also prepared.

[0095] A film (thickness: 38 μm, glass transition temperature: 110° C.) formed from a polyethylene terephthalate resin containing recycled polyethylene terephthalate was prepared as a substrate layer. A fluororesin composition (RA-1) was applied to both surfaces of the film. These applications were carried out using a kiss-reverse type coating device. After the application, the fluororesin composition (RA-1) was cured by heating at 150° C. for 60 seconds, thereby obtaining a release film in which resin layers were laminated on both surfaces of a polyethylene terephthalate resin film containing recycled polyethylene terephthalate (hereinafter referred to as the "release film of Comparative Example 1").

[0096] The thickness of the release film of Comparative Example 1 was 58±6 μm. The thickness of the base material layer in the release film of Comparative Example 1 was 38 μm±4 μm. The thickness of the resin layer of the release film of Comparative Example 1 was 10±1 μm. The tensile strength retention rate after aging at 200° C. for 6 hours was 78% (tensile strength before heating: 146 MPa, tensile strength after heating: 114 MPa). Figure 5 is a surface image of the resin layer side of the release film of Comparative Example 1. As shown in Figure 5, slight precipitation of oligomers on the film surface was confirmed, and there was some resistance to the adhesion of the film to the SUS plate.

[0097] (Comparative Example 2)

[0098] A release film (hereinafter referred to as "the release film of Comparative Example 2") was obtained in the same manner as in Example 1, except that no resin layers were laminated on both sides of the substrate layer.

[0099] The thickness of the release film of Comparative Example 2 was 48±5 μm. The tensile strength retention rate after aging at 200° C. for 6 hours was 67% (tensile strength before heating: 230 MPa, tensile strength after heating: 154 MPa). Figure 6 is a surface image of the release film of Comparative Example 2. As shown in Figure 6, a large amount of oligomer precipitation was confirmed on the film surface, and the film stuck to the SUS plate.

[0100] [Moldability]

[0101] <Vacuum suction>

[0102] The fluororesin compositions of Example 1 and Comparative Example 1 were molded using a transfer molding machine (MZ-1106-01, manufactured by Apic Yamada). A transfer pressure of 8.5 MPa was used in the molding. The molding temperature used for curing the fluororesin compositions in the molding was 175°C. After molding was completed, vacuum suction was confirmed, showing that the release film 100 was stuck to the inner surface of the mold 201, as shown in FIG. 3(B).

[0103] <Wrinkles, tears>

[0104] After molding, the release film was visually inspected for wrinkles and tears.

[0105] <Resin leakage>

[0106] Resin leakage from the molding machine during molding was checked visually.

[0107] <Multi-shot suitability>

[0108] Transfer molding of an epoxy resin was carried out using the release film of Example 1. The molding was carried out as shown in Figure 3. The molding was carried out so that the layer formed from the molded product of the fluororesin composition was in contact with the mold and the layer formed from the molded product of the fluororesin composition was in contact with the epoxy resin. Next, the same molding was carried out again using the release film used in the previous molding. The same molding was carried out two more times using the same release film, for a total of four moldings using one release film.

[0109] In all four moldings using the release film of Example 1, the epoxy resin molded body was smoothly released from the release film, demonstrating that the release film of Example 1 has excellent releasability and that this releasability is maintained throughout multiple moldings.

[0110] The release film of Example 1 could be used for at least four moldings in succession.

[0111] Furthermore, when molding was performed several more times, the release film of Example 1 broke at the tenth molding. That is, the release film of Example 1 has excellent multi-shot suitability.

[0112] The release films of Comparative Examples 1 and 2 were used to perform molding multiple times in the same manner as the release film of Example 1. As a result, the release film of Comparative Example 1 broke during the third molding. The release film of Comparative Example 2 broke during the second molding.

[0113] 100 Release film 101 Base layer 102 Resin layer 103 Resin layer

Claims

1. A laminate comprising: a substrate layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluorine-based resin containing hydrophobic particles, laminated on at least one surface of the substrate layer.

2. The laminate according to claim 1, wherein the hydrophobized particles have a DBA value of 250 meq / kg or less.

3. The laminate according to claim 1, wherein the fluorine-based resin is a tetrafluoroethylene-based resin.

4. The laminate of claim 1, wherein the recycled polyester is recycled polyethylene terephthalate.

5. The laminate according to claim 1, wherein the fluororesin is a cured product of a fluororesin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent.

6. The laminate according to claim 5, wherein the curing agent contains an isocyanurate-type polyisocyanate and does not contain an adduct-type polyisocyanate.

7. The laminate according to claim 1, which has a tensile strength retention rate of 70% or more after aging at 200°C for 6 hours.

8. The laminate according to claim 1, which is used under conditions of 175°C and 85 bar.

9. A release film comprising: a substrate layer formed from a polyester resin containing recycled polyester; and a resin layer formed from a fluorine-based resin containing hydrophobic particles, laminated on at least one surface of the substrate layer.

Images