Laminate and method for producing same

Abstract

This laminate comprises, in this order, a substrate layer (A), an adhesive layer (B), and a resin layer (C) containing a poly(3-hydroxyalkanoate)-based copolymer (c1). The adhesive layer (B) contains a resin (b1) having a glass transition temperature greater than -20°C but no greater than 0°C, and an acid value of less than 40 mg KOH / g. The adhesive layer (B) has a basis weight of at least 0.1 g / m2 but less than 5.0 g / m2. The resin layer (C) has a thickness of at least 5 μm but no more than 100 μm.

Description

Laminate and method for manufacturing same

[0001] The present invention relates to a laminate in which a resin layer is laminated on at least one surface of a base layer such as paper, a method for producing the same, and a molded product thereof.

[0002] In recent years, the problem of marine pollution caused by discarded plastic packaging materials has come to the forefront, and environmentally friendly packaging materials made from paper have been attracting attention.

[0003] Paper used as packaging materials is usually laminated with plastic to impart water resistance, oil resistance, or heat sealability. It is preferable to laminate with a biodegradable plastic so as not to impair the biodegradability of the paper.

[0004] Among biodegradable plastics, poly(3-hydroxyalkanoate) resins (hereinafter also referred to as P3HA resins) are thermoplastic polyesters that are produced and accumulated as energy storage substances within the cells of many microbial species, and are capable of biodegrading not only in soil but also in seawater. Therefore, laminates obtained by laminating these resins onto a paper substrate are extremely promising from the perspective of environmental protection.

[0005] Methods for integrating paper and P3HA-based resin include extrusion lamination, aqueous slurry coating, etc. Among these, extrusion lamination is preferred because it allows for increased processing speed to improve productivity, and coating methods make it difficult to obtain sufficient mechanical strength for the resin layer.

[0006] However, because P3HA-based resins generally have high melt viscosity and poor penetration into paper, it has not been easy to bond the melt-extruded resin to paper with sufficient strength. As a result, when producing cup-shaped products such as beverage cups, the laminate layer peels off from the paper, causing problems such as leakage when filled with contents.

[0007] In order to solve such problems, Patent Document 1 describes a laminate in which an adhesive layer having a glass transition temperature of the entire resin of 20°C or higher and lower than 90°C is provided between a substrate layer such as paper and a resin layer containing a poly(3-hydroxyalkanoate) copolymer.

[0008] International Publication No. 2023 / 228736

[0009] According to the method described in Patent Document 1, the adhesive strength between a substrate layer such as paper and a resin layer containing a P3HA-based resin can be improved. However, the adhesive strength may not be sufficient in some cases, and further improvement is required.

[0010] In view of the above-described current situation, an object of the present invention is to provide a laminate comprising, in this order, a base layer, an adhesive layer, and a resin layer containing a poly(3-hydroxyalkanoate)-based resin, wherein the adhesive strength between the base layer and the resin layer is improved.

[0011] As a result of intensive research to solve the above-mentioned problems, the inventors discovered that the above-mentioned problems can be solved by selecting and using a resin whose glass transition temperature and acid value are each within a specific range as the resin constituting the adhesive layer, and thus completed the present invention.

[0012] That is, the present invention provides a laminate comprising, in this order, a substrate layer (A), an adhesive layer (B), and a resin layer (C) containing a poly(3-hydroxyalkanoate)-based copolymer (c1), wherein the adhesive layer (B) contains a resin (b1) having a glass transition temperature of more than −20° C. and not more than 0° C. and an acid value of less than 40 mg KOH / g, and the adhesive layer (B) has a basis weight of 0.1 g / m ２ Above, 5.0g / m ２ The present invention also relates to a laminate manufacturing method comprising: a step (i) of forming, on at least one surface of a substrate layer (A), an adhesive layer (B) containing a resin (b1) having a glass transition temperature higher than -20°C and lower than 0°C and an acid value of less than 40 mgKOH / g; and a step (ii) of forming, on the surface of the adhesive layer (B), a resin layer (C) containing a poly(3-hydroxyalkanoate)-based copolymer (c1) by extrusion lamination. The present invention also relates to a molded article comprising the laminate.

[0013] According to the present invention, it is possible to provide a laminate comprising, in this order, a base layer, an adhesive layer, and a resin layer containing a poly(3-hydroxyalkanoate)-based resin, wherein the adhesive strength between the base layer and the resin layer is improved. According to a preferred embodiment of the present invention, the laminate can be produced with good productivity.

[0014] 1 is a schematic diagram illustrating a stack structure of a stack according to an embodiment of the present invention.

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0016] [Laminate] A laminate according to one embodiment of the present invention has an adhesive layer (B) and a resin layer (C) containing a poly(3-hydroxyalkanoate) copolymer (c1) on at least one surface of a base layer (A). As shown in Fig. 1, in the laminate 1, the base layer (A) denoted by reference numeral 2, the adhesive layer (B) denoted by reference numeral 3, and the resin layer (C) denoted by reference numeral 4 are laminated in this order.

[0017] The adhesive layer (B) may be laminated directly on the base layer (A), or another layer may be further included between the adhesive layer (B) and the base layer (A) as long as the adhesiveness is not impaired.

[0018] The resin layer (C) may be the outermost layer exposed on the surface of the laminate, or another layer may be laminated on the resin layer (C) for the purpose of imparting water resistance, gloss, design properties, etc.

[0019] The adhesive layer (B) and the resin layer (C) may be provided on only one side of the base layer (A), or the adhesive layer (B) and the resin layer (C) may be provided on each of both sides of the base layer (A). When the adhesive layer (B) and the resin layer (C) are provided on only one side of the base layer (A), no other layer may be formed on the other side, and the base layer (A) may be the outermost layer exposed on the surface of the laminate, or another layer may be laminated thereon for the purpose of imparting water resistance, gloss, design properties, or adhesiveness.

[0020] When the substrate layer (A) has an adhesive layer (B) and a resin layer (C) on each side, the materials constituting the adhesive layer (B) on the front side and the adhesive layer (B) on the back side, the basis weight and thickness may be the same or different. The same applies to the resin layer (C) on the front side and the resin layer (C) on the back side. In this application, the basis weight (g / m ２ ) refers to the dry weight (solids content) of the layer.

[0021] [Substrate layer (A)] The material constituting the substrate layer (A) is not particularly limited, but is preferably biodegradable. Examples include paper (mainly composed of cellulose), cellophane, cellulose ester; polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, or a substrate of any of these on which an inorganic material such as aluminum or silica is vapor-deposited. Among these, paper is preferred because it has excellent heat resistance and is inexpensive.

[0022] The type of paper is not particularly limited and can be appropriately selected depending on the application of the laminate, and examples include cup base paper, kraft paper, fine paper, coated paper, tissue paper, glassine paper, paperboard, etc. If necessary, a water-resistant agent, a water-repellent agent, an inorganic substance, etc. may be added to the paper, and the paper may be subjected to a surface treatment such as an oxygen barrier layer coating or a water vapor barrier coating.

[0023] The substrate layer (A) may also be subjected to a surface treatment such as corona treatment, ozone treatment, plasma treatment, frame treatment, anchor coat treatment, oxygen barrier layer coating, water vapor barrier coating, etc. These surface treatments may be performed alone or in combination.

[0024] [Adhesive Layer (B)] The adhesive layer (B) is a layer mainly composed of a resin. By providing the adhesive layer (B) between the base layer (A) and the resin layer (C), it is possible to improve the adhesion between the base layer (A) and the resin layer (C). Furthermore, when the laminate according to this embodiment is bonded by heat sealing, it is also possible to improve the adhesive strength. Furthermore, by providing the adhesive layer (B), the oil resistance of the laminate is improved, and when it comes into contact with oily foods, etc., it is possible to suppress the seepage of oil.

[0025] The adhesive layer (B) contains at least a resin (b1) having a glass transition temperature (Tg) of more than -20°C and less than 0°C and an acid value of less than 40 mgKOH / g. The use of such a resin in the adhesive layer (B) can improve the adhesion strength between the substrate layer (A) and the resin layer (C). It is presumed that a low Tg of 0°C or less makes the resin (b1) more likely to soften due to the heat generated when forming the resin layer (C), making it easier to ensure good adhesion strength. In particular, as described below, when the resin layer (C) contains a reaction product of a copolymer (c1) and an organic peroxide, the elasticity increases during melting and the wettability decreases, which generally tends to reduce the adhesion strength between the substrate layer (A) and the resin layer (C). However, the use of resin (b1) in the adhesive layer (B) can achieve good adhesion strength.

[0026] The Tg of the resin (b1) is not particularly limited as long as it is higher than -20°C and 0°C or lower. If the Tg is higher than 0°C, the adhesion strength between the base layer (A) and the resin layer (C) becomes insufficient. In order to achieve an excellent effect of improving the adhesion strength between the base layer (A) and the resin layer (C), the upper limit of the Tg is preferably -5°C or lower, more preferably -10°C or lower, and even more preferably -15°C or lower.

[0027] The Tg of the resin (b1) can be controlled by adjusting the types of monomers constituting the resin and the ratio of their use.

[0028] The Tg of the resin (b1) can be measured by differential thermal analysis, but can also be calculated from the Tg of the homopolymer of each monomer constituting the resin and the weight fraction of each monomer using the following formula: (1 / Tg)=(W １ / Tg １ ) + (W ２ / Tg ２ )+...+(Wn / Tg ｎ ) In the formula, W ｉ represents the weight fraction of each monomer, and Tg ｉ represents the Tg of the homopolymer of each monomer, where i represents an integer of 1 to n, and W １ +W ２ +...+W ｎ =1.

[0029] The acid value of the resin (b1) is not particularly limited as long as it is 0 or more and less than 40 mgKOH / g. If the acid value is 40 mgKOH / g or more, the polarity of the resin becomes high, which reduces the affinity with the P3HA-based resin contained in the resin layer (C), and the adhesion strength between the base layer (A) and the resin layer (C) becomes insufficient. The lower limit of the acid value may be 10 mgKOH / g or more, 20 mgKOH / g or more, or 30 mgKOH / g or more.

[0030] The acid value of a resin is a value attributable to acidic groups such as carboxyl groups contained in the resin, and the greater the content of acidic groups, the higher the acid value. Specifically, the acid value of a resin is expressed as the mass (mg) of potassium hydroxide required to neutralize 1 g of the resin.

[0031] The acid value of the resin can be measured by potentiometric titration (neutralization titration) specified in ASTM D664, but can also be calculated from the acid value of each monomer constituting the resin and the weight fraction of each monomer using the following formula: (1 / X)=(W １ / X １ ) + (W ２ / X ２ ) + ... + (W ｎ / X ｎ ) In the formula, W ｉ represents the weight fraction of each monomer, and X ｉ represents the acid value of each monomer, where i represents an integer from 1 to n, and W １ +W ２ +...+W ｎ =1.

[0032] The type of resin (b1) is not particularly limited, and a resin that satisfies the above-mentioned Tg and acid value may be selected from resins commonly used in the fields of coated paper or resin films. Among these, resins that have a high affinity with substrates such as paper and P3HA-based resins are preferred, and examples of such resins include acrylic resins, styrene-acrylic resins, polyester resins, urethane resins, and copolymer resins thereof. These resins may be used alone, or two or more resins may be mixed in any ratio.

[0033] Resin (b1) is preferably at least one of an acrylic resin, a styrene-acrylic resin, and a polyester resin, since this has a particularly excellent effect of improving adhesion strength. In particular, at least one of an acrylic resin and a styrene-acrylic resin is preferred.

[0034] The acrylic resin refers to a resin containing at least an acrylic monomer and / or a methacrylic monomer as constituent monomers.

[0035] The acrylic or methacrylic monomer is not particularly limited, and examples thereof include alkyl (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, alkyl (meth)acrylate, stearyl (meth)acrylate, and cyclohexyl (meth)acrylate; phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, and 2-ethoxyethyl (meth)acrylate; (meth)acrylic acid, etc. These may be used alone, or two or more may be used in combination as necessary. Among the (meth)acrylic monomers listed above, butyl acrylate and 2-ethylhexyl acrylate are generally known as monomers that lower the Tg of the resin.

[0036] The styrene-acrylic resin refers to a resin containing, as a constituent monomer, a monomer having a styrene skeleton, in addition to the acrylic monomer and / or methacrylic monomer. Examples of the monomer having a styrene skeleton include styrene and α-methylstyrene.

[0037] In a preferred embodiment, the acrylic resin and styrene-acrylic resin preferably contain, as constituent monomers, a vinyl monomer having a carboxyl group and / or a styrene skeleton-containing monomer in addition to a (meth)acrylic acid ester. Examples of vinyl monomers having a carboxyl group include (meth)acrylic acid. The content ratio thereof is preferably 10% by weight or less of the total amount of constituent monomers of the resin, from the viewpoint of making the acid value of resin (b1) less than 40 mg KOH / g. The content ratio of the styrene skeleton-containing monomer is preferably 50% by weight or less of the total amount of constituent monomers of the resin, from the viewpoint of making the Tg of resin (b1) 0°C or less.

[0038] Specific types of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN); aliphatic polyester resins such as polycaprolactone, polybutylene succinate adipate, polybutylene succinate, and polylactic acid; and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate and polybutylene azelate terephthalate. However, the poly(3-hydroxyalkanoate) copolymer (b2) described below does not fall under the category of the polyester resin.

[0039] The resin component contained in the adhesive layer (B) may be the resin (b1) alone, or may contain a poly(3-hydroxyalkanoate) copolymer (b2) together with the resin (b1). By including the poly(3-hydroxyalkanoate) copolymer (b2) in the adhesive layer (B), it is possible to improve the biodegradability of the entire laminate while maintaining good adhesive strength between the base layer (A) and the resin layer (C).

[0040] The definition and specific examples of the poly(3-hydroxyalkanoate) copolymer (b2) are the same as those of the poly(3-hydroxyalkanoate) copolymer (c1) described below, and therefore will not be described again. In particular, it is preferable to use a poly(3-hydroxybutyrate) copolymer (b2-1) containing 3-hydroxybutyrate units and other hydroxyalkanoate units as the poly(3-hydroxyalkanoate) copolymer (b2).

[0041] The average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units in all monomer units constituting the copolymer (b2-1) is not particularly limited, but may be, for example, 3-hydroxybutyrate units / other hydroxyalkanoate units = 99 / 1 to 80 / 20 (mol % / mol %), and preferably 97 / 3 to 85 / 15 (mol % / mol %).

[0042] The content of the poly(3-hydroxyalkanoate) copolymer (b2) in the adhesive layer (B) is preferably 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more, as a ratio of the copolymer (b2) to the total of the resin (b1) and the copolymer (b2). On the other hand, from the viewpoint of suppressing the heating temperature when forming the adhesive layer (B) and from the viewpoint of maintaining the adhesive strength between the base layer (A) and the resin layer (C), the upper limit of the ratio is preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 20% by weight or less.

[0043] The proportion of the resin (b1) contained in the adhesive layer (B), or the total proportion of the resin (b1) and the poly(3-hydroxyalkanoate) copolymer (b2), is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more, of the total amount (solid content) of the adhesive layer (B). The upper limit may be 100% by weight or less, and may be 99% by weight or less.

[0044] Examples of components other than the resin (b1) and the poly(3-hydroxyalkanoate) copolymer (b2) in the adhesive layer (B) include other resins (particularly water-soluble resins or water-dispersible resins), dispersants, viscosity modifiers, water retention agents, antifoaming agents, water-resistant agents, pH adjusters, cationic resins, anionic resins, ultraviolet absorbers, metal salts, lubricants, plasticizers, inorganic fillers, coloring dyes, and pigments.

[0045] As described below, the adhesive layer (B) is preferably a coated layer of a coating agent, and particularly preferably a coated layer of a water-dispersible coating agent, which allows the adhesive layer (B) to be formed simply by applying the water-dispersible coating agent and then performing a heat treatment to evaporate the water, thereby improving the productivity of the laminate.

[0046] In the laminate according to this embodiment, the basis weight of the adhesive layer (B) is 0.1 g / m ２ 5.0g / m or more ２ The weight is adjusted to a range of less than 0.1 g / m ２ If the amount is less than 5.0 g / m, the adhesiveness to the resin layer (C) may decrease. ２ If the weight per unit area exceeds 0.5 g / m, a large amount of heat is required during drying, which increases the load on the equipment, and for example, insufficient drying may cause problems such as blocking during winding of the raw web. ２ 4.5g / m or more ２ Preferably, the content is 1.0 g / m or less. ２ 4.0g / m or more ２ More preferably, 2.0 g / m or less ２ 3.5g / m or more ２ The following is even more preferred:

[0047] [Resin Layer (C)] The resin layer (C) contains a poly(3-hydroxyalkanoate) copolymer (c1). The resin layer (C) may be the outermost layer in the laminate according to this embodiment, and in that case, the resin layer (C) can be used for heat sealing (described below).

[0048] The poly(3-hydroxyalkanoate) copolymer (c1) is a biodegradable aliphatic polyester (preferably a polyester containing no aromatic ring) and is a copolymer having at least one or two or more types of 3-hydroxyalkanoate units. The 3-hydroxyalkanoate units are preferably represented by the following general formula (1): [-CHR-CH ２ -CO-O-] (1)

[0049] In the general formula (1), R is C ｐ H ２ｐ＋１ where p is an integer of 1 to 15. Examples of R include linear or branched alkyl groups such as methyl, ethyl, propyl, methylpropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl. p is preferably an integer of 1 to 10, and more preferably an integer of 1 to 8.

[0050] The poly(3-hydroxyalkanoate) copolymer (c1) preferably contains 3-hydroxyalkanoate units (particularly units represented by general formula (1)) in an amount of 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more of all structural units (monomer units). The poly(3-hydroxyalkanoate) copolymer may contain only two or more types of 3-hydroxyalkanoate units as structural units of the polymer, or may contain other units (e.g., 4-hydroxyalkanoate units) in addition to one or more types of 3-hydroxyalkanoate units.

[0051] The poly(3-hydroxyalkanoate) copolymer (c1) is preferably a copolymer containing 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) units and other hydroxyalkanoate units.

[0052] The other hydroxyalkanoate units may be 3-hydroxyalkanoate units other than 3HB units, or may be hydroxyalkanoate units other than 3-hydroxyalkanoate units (for example, 4-hydroxyalkanoate units). Only one type of other hydroxyalkanoate unit may be included, or two or more types may be included.

[0053] Specific examples of the poly(3-hydroxyalkanoate) copolymer (c1) include poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), poly(3 Examples of suitable poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB), etc. In particular, from the viewpoints of productivity and mechanical properties of the resin composition, P3HB3HH or P3HB4HB is preferred, with P3HB3HH being particularly preferred.

[0054] A specific method for producing P3HB3HH is described in, for example, WO 2010 / 013483. Commercially available P3HB3HH products include Kaneka Biodegradable Polymer Green Planet (registered trademark) manufactured by Kaneka Corporation.

[0055] The average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units in all monomer units constituting the poly(3-hydroxyalkanoate) copolymer (c1) is preferably 3-hydroxybutyrate units / other hydroxyalkanoate units=99 / 1 to 80 / 20 (mol % / mol %), more preferably 97 / 3 to 85 / 15 (mol % / mol %), from the viewpoint of achieving both strength and productivity of the resin layer (C).

[0056] The average content ratio of each monomer unit in all monomer units constituting the poly(3-hydroxyalkanoate) copolymer (c1) can be determined by a method known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139. The average content ratio means the molar ratio of each monomer unit in all monomer units constituting the copolymer (c1), and when the copolymer (c1) is a mixture of two or more types, it means the molar ratio of each monomer unit contained in the entire mixture.

[0057] The poly(3-hydroxyalkanoate) copolymer (c1) preferably contains at least a copolymer (c1-1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 mol % or more and 10 mol % or less. Because the copolymer (c1-1) has a relatively fast crystallization rate, when the resin layer (C) is formed by a lamination method, crystallization and solidification after lamination proceeds rapidly, improving peelability from the pressure-bonding surface of a cooling roll or the like, and increasing productivity of the laminate.

[0058] From the viewpoint of productivity, the content of the copolymer (c1-1) is preferably 50% by weight or more and 100% by weight of the total amount of the copolymer (c1). The lower limit is preferably 60% by weight or more, and more preferably 70% by weight or more. The upper limit is not particularly limited, but from the viewpoint of improving the crack resistance of the resin layer (C), it is preferably 90% by weight or less, and more preferably 80% by weight or less.

[0059] The content of other hydroxyalkanoate units in copolymer (c1-1) may be 1 mol % or more and 10 mol % or less, preferably 2 mol % or more and 8 mol % or less, and more preferably 3 mol % or more and 6 mol % or less. Two or more copolymers having different monomer compositions may be used in combination as copolymer (c1-1).

[0060] The poly(3-hydroxyalkanoate) copolymer (c1) preferably contains, in addition to the copolymer (c1-1), a copolymer (c1-2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more, thereby improving the crack resistance of the resin layer (C).

[0061] The content of other hydroxyalkanoate units in copolymer (c1-2) is preferably 24 mol% or more and 99 mol% or less, more preferably 24 mol% or more and 50 mol% or less, even more preferably 24 mol% or more and 35 mol% or less, and particularly preferably 24 mol% or more and 30 mol% or less.

[0062] When copolymer (c1-2) is used, its content is not particularly limited, but from the viewpoint of the balance between the crystallization rate and crack resistance of copolymer (c1), it is preferably 1% by weight or more and 50% by weight or less. The lower limit is more preferably 5% by weight or more, and even more preferably 10% by weight or more. The upper limit is more preferably 40% by weight or less, and even more preferably 35% by weight or less.

[0063] Furthermore, the poly(3-hydroxyalkanoate) copolymer (c1) may further contain, in addition to the copolymers (c1-1) and / or (c1-2), a copolymer (c1-3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is more than 10 mol % and less than 24 mol %, thereby increasing the flexibility of the resin layer (C).

[0064] The content of copolymer (c1-3) is not particularly limited, but is preferably, for example, 0% by weight or more and 50% by weight or less, and the upper limit may be 30% by weight or less, 20% by weight or less, 10% by weight or less, or 5% by weight or less.

[0065] As described above, examples of the other hydroxyalkanoate units contained in the copolymers (c1-1), (c1-2), and (c1-3) include 3-hydroxyhexanoate units, 3-hydroxyvalerate units, 4-hydroxybutyrate units, 3-hydroxyoctanoate units, and 3-hydroxyoctadecanoate units. Only one type of other hydroxyalkanoate unit may be contained, or two or more types may be contained. Furthermore, the other hydroxyalkanoate units contained in the copolymers (c1-1), (c1-2), and (c1-3) may be the same or different. In particular, the other hydroxyalkanoate units in at least one or all of the copolymers (c1-1), (c1-2), and (c1-3) are preferably 3-hydroxyhexanoate.

[0066] The method for obtaining a blend of multiple P3HA-based resins is not particularly limited, and may be a method for obtaining a blend by microbial production or a method for obtaining a blend by chemical synthesis. Alternatively, a blend may be obtained by melt-kneading two or more resins using an extruder, kneader, Banbury mixer, roll, etc., or by dissolving two or more resins in a solvent, mixing, and drying the resins.

[0067] The weight average molecular weight of the entire poly(3-hydroxyalkanoate) copolymer (c1) is not particularly limited, but from the viewpoint of achieving both strength and productivity of the resin layer (C), it is preferably from 100,000 to 2,000,000, more preferably from 150,000 to 1,000,000, and particularly preferably from 200,000 to 500,000. The upper limit may be 400,000 or less, or may be 300,000 or less. The weight average molecular weight of the copolymer (c1) described here is a value measured for the copolymer before it is reacted with the organic peroxide.

[0068] The weight-average molecular weight can be determined as a polystyrene-equivalent molecular weight using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), a polystyrene gel (Showa Denko K.K.'s "K-G 4A" or "K806M") as a column, and chloroform as a mobile phase. Calibration curves are prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. A column suitable for measuring the molecular weight may be used as the column for the GPC.

[0069] [Organic Peroxide] The poly(3-hydroxyalkanoate) copolymer (c1) contained in the resin layer (C) may be an unmodified resin, but preferably contains a reaction product of the copolymer (c1) and an organic peroxide. This can increase the melt tension of the copolymer (c1), so that when the resin layer (C) is formed by extrusion lamination, thickness fluctuations and neck-in in the TD direction of the resin layer (C) can be suppressed even if the production rate is increased, and high productivity can be achieved.

[0070] The entire copolymer (c1) may be a modified product obtained by reacting with an organic peroxide, or a part of the copolymer (c1) may be a modified product, and the remainder may be an unmodified product that has not been reacted with an organic peroxide. That is, the copolymer (c1) may be a mixture of a modified product and an unmodified product.

[0071] The copolymer (c1-1) and the copolymer (c1-3) may each be a modified product obtained by reacting with an organic peroxide, or an unmodified product that has not been reacted with an organic peroxide, or a mixture of a modified product and an unmodified product.

[0072] Examples of the organic peroxides include diisobutyl peroxide, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di(3,5,5-trimethylhexanoyl)peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di(3,5,5-trimethylhexanoyl)peroxide, dilauroyl peroxide, t-butylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxy isopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, t-amylperoxy-3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-di-t-butylperoxybutane, and the like. Among these, t-butylperoxy 2-ethylhexyl carbonate, t-butylperoxy isopropyl carbonate, and t-butylperoxy 2-ethylhexanoate are preferred. The organic peroxides may be used alone or in combination of two or more.

[0073] The amount of the organic peroxide used can be appropriately determined taking into consideration its effect, but is preferably 1.0 part by weight or less, particularly preferably 0.8 part by weight or less, relative to 100 parts by weight of the copolymer (c1) to be reacted with the organic peroxide. The lower limit is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, and more preferably 0.3 part by weight or more.

[0074] The weight-average molecular weight of the copolymer (c1) after the reaction with the organic peroxide is preferably in the range of about 50,000 to 150,000 higher than the weight-average molecular weight of the P3HA-based resin before the reaction as described above. The method for measuring the weight-average molecular weight is as described above.

[0075] The reaction of a part or all of the copolymer (c1) with the organic peroxide can be carried out by a step of melt-kneading them in an extruder ("melt-kneading step"), or by a step of reacting a part or all of the copolymer (c1) with the organic peroxide in a solution or aqueous dispersion of the copolymer (c1) ("in-liquid reaction step").

[0076] In the melt-kneading step, the organic peroxide can be added in various forms such as a solid or a liquid. It may also be added in the form of a solution or dispersion of the organic peroxide diluted with a diluent or the like.

[0077] In the melt-kneading step, the copolymer (c1) to be modified and an organic peroxide are charged into an extruder and melt-kneaded, but other components such as a crystal nucleating agent, a lubricant, a filler, a plasticizer, etc., as described below, may also be charged into the extruder in addition to these components and melt-kneaded. In this embodiment, it is preferable to perform melt-kneading without adding a crosslinking agent having two or more radically reactive functional groups (e.g., epoxy groups or carbon-carbon double bonds) as disclosed in U.S. Pat. No. 9,034,989.

[0078] In the melt-kneading step, the copolymer (c1) to be modified, the organic peroxide, and, if necessary, other components may be charged separately into the extruder, or the components may be mixed together and then charged into the extruder.

[0079] In the melt-kneading step, the entire copolymer (c1) may be reacted with an organic peroxide. Alternatively, a portion of the copolymer (c1) may be reacted with an organic peroxide to form a reaction product, and the remaining copolymer (c1) may be added to the reaction product and further melt-kneaded. In this case, the remaining copolymer (c1) added later does not react with the organic peroxide. From the viewpoint of productivity and property improvement, it is preferable to react a portion of the copolymer (c1) with an organic peroxide and then add the remaining copolymer (c1).

[0080] The melt-kneading in the melt-kneading step can be carried out according to a known or conventional method, and can be carried out, for example, using an extruder (single-screw extruder, twin-screw extruder), a kneader, etc. The conditions for melt-kneading are not particularly limited and can be set appropriately, but it is preferable to set a resin temperature and a residence time that allow the organic peroxide to complete the reaction during melt-kneading.

[0081] The resin layer (C) is preferably a resin layer containing a poly(3-hydroxyalkanoate) copolymer (c1) as a main component. Specifically, the content of the copolymer (c1) in the resin layer (C) is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, and even more preferably 80 to 100% by weight. The lower limit may be 90% by weight or more, or may be 95% by weight or more.

[0082] The resin layer (C) may further contain poly(3-hydroxybutyrate) (hereinafter also referred to as PHB) in addition to the copolymer (c1). This can promote the crystalline solidification of the resin layer (C). The content of PHB may be, for example, about 0 to 30 parts by weight, and preferably 0 to 10 parts by weight, per 100 parts by weight of the copolymer (c1).

[0083] The resin layer (C) may contain only the copolymer (c1) or only the copolymer (c1) and PHB as the resin component, or may further contain other resins in addition to these. The other resins are preferably biodegradable resins, such as aliphatic polyester resins such as polycaprolactone, polybutylene succinate adipate, polybutylene succinate, and polylactic acid; and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate and polybutylene azelate terephthalate. These other resins may be used alone or in combination of two or more.

[0084] The resin layer (C) may contain additives typically added to resin materials, provided that the effects of the present invention are not impaired. Examples of such additives include inorganic fillers, colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolites, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather resistance improvers, UV absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding properties improvers. These additives may be used alone or in combination of two or more. However, the additives are optional components, and the resin layer (C) may not contain these additives.

[0085] Examples of the crystal nucleating agent include polyhydric alcohols such as pentaerythritol, galactitol, and mannitol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, boron nitride, etc. Among these, pentaerythritol is preferred because it has a particularly excellent effect of promoting the crystallization of poly(3-hydroxyalkanoate) resins.

[0086] The amount of the nucleating agent in the resin layer (C) is not particularly limited, but is preferably 0.1 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight, per 100 parts by weight of the total amount of the resin components contained in the resin layer (C).

[0087] Examples of the lubricant include saturated or unsaturated fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, and erucic acid amide; alkylene fatty acid amides such as methylene bisstearic acid amide and methylene bisstearic acid amide; and aliphatic amide compounds such as pentaerythritol.

[0088] The amount of the lubricant in the resin layer (C) is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1 part by weight, per 100 parts by weight of the total amount of the resin components contained in the resin layer (C). By making the amount 0.1 part by weight or more, the effect of improving the releasability due to the addition of the lubricant can be obtained.

[0089] Examples of the inorganic filler include talc, calcium carbonate, mica, silica, clay, kaolin, titanium oxide, alumina, zeolite, etc. The average particle size of these inorganic fillers is preferably 0.5 μm or more.

[0090] The amount of the inorganic filler in the resin layer (C) is preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, per 100 parts by weight of the total amount of the resin components contained in the resin layer (C). By making the amount 0.5 part by weight or more, the effect of improving releasability due to the incorporation of the inorganic filler can be obtained.

[0091] The plasticizer is not particularly limited, but from the viewpoint of compatibility with the poly(3-hydroxyalkanoate) resin, it is preferable to use an ester compound having an ester bond in the molecule.

[0092] Examples of ester compounds that can be used as plasticizers include modified glycerin-based compounds, dibasic acid ester-based compounds, adipate ester-based compounds, polyether ester-based compounds, benzoate ester-based compounds, phthalate ester-based compounds, citrate ester-based compounds, sebacate ester-based compounds, isosorbide ester-based compounds, polycaprolactone-based compounds, etc. Among these, modified glycerin-based compounds, dibasic acid ester-based compounds, adipate ester-based compounds, polyether ester-based compounds, citrate ester-based compounds, sebacate ester-based compounds, and isosorbide ester-based compounds are preferred.

[0093] The modified glycerin compound is preferably a glycerin ester compound. Any of a monoester, diester, or triester of glycerin can be used as the glycerin ester compound, but a triester of glycerin is preferred from the viewpoint of compatibility with the P3HA resin.

[0094] The blending amount of the plasticizer is preferably 0.1 parts by weight or more and less than 20.0 parts by weight relative to 100 parts by weight of the total amount of the resin components contained in the resin layer (C). By blending the plasticizer in an amount of 0.1 parts by weight or more, the strength of the resin layer (C) can be improved, and the laminate can be given strength sufficient for practical use.

[0095] In the laminate according to this embodiment, the thickness of the resin layer (C) is set in the range of 5 μm or more and 100 μm or less. If the thickness is less than 5 μm, the resin may cool too quickly during lamination of the resin layer (C), resulting in a decrease in adhesion to the substrate layer (A) on which the adhesive layer (B) is formed. In addition, cracks are likely to occur in the resin layer (C) when the laminate is processed into a molded product. The lower limit of the thickness is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 40 μm or more, and particularly preferably 50 μm or more.

[0096] Furthermore, if the thickness of the resin layer (C) exceeds 100 μm, the resin temperature may become uneven during the formation of the resin layer (C), which may cause uneven thickness or poor appearance due to melt fracture. Furthermore, the laminate may become too hard, resulting in molding defects. The upper limit of the thickness is preferably 80 μm or less, more preferably 60 μm or less.

[0097] [Method for producing laminate] An example of a method for producing the laminate according to this embodiment will be described below. The laminate according to this embodiment can be produced by forming an adhesive layer (B) on at least one surface of the base layer (A) (step (i)), and then forming a resin layer (C) on the surface of the formed adhesive layer (B) (step (ii)).

[0098] In the step (i) of forming the adhesive layer (B) on at least one surface of the base layer (A), it is preferable to apply a solution or an aqueous dispersion such as an aqueous slurry containing the components constituting the adhesive layer (B) to one or both surfaces of the base layer (A), and then heat and dry the applied solution.

[0099] The method for applying the solution or aqueous dispersion to the substrate is not particularly limited, and any known method capable of forming a resin layer on a substrate can be used as appropriate. Specifically, a spraying method, a scattering method, a slit coater method, an air knife coater method, a roll coater method, a bar coater method, a comma coater method, a blade coater method, a screen printing method, a gravure printing method, etc. can be used. Before applying the solution or aqueous dispersion, a step of subjecting the substrate layer (A) to a surface treatment such as the above-mentioned corona treatment may be carried out.

[0100] The drying treatment after coating can be carried out using a known heating method, such as hot air heating, infrared heating, microwave heating, roll heating, or hot plate heating, which can be used alone or in combination of two or more.

[0101] Next, step (ii) of forming a resin layer (C) on the surface of the formed adhesive layer (B) is carried out. The method of forming the resin layer (C) may be a method of applying a solution or aqueous dispersion containing the components constituting the resin layer (C) to the surface of the adhesive layer (B), heating and drying, and forming a film. However, from the viewpoint of adhesion with the adhesive layer (B), productivity, and quality of suppressing thermal degradation, it is preferable to form the resin layer (C) on the surface of the adhesive layer (B) by extrusion lamination or thermal lamination. The extrusion lamination method is more preferable because of its excellent productivity.

[0102] As the extrusion lamination method, a general extrusion lamination method can be used. Specifically, a molten resin material is extruded into a film shape from a T-shaped die, and while being cooled using a cooling roll, the film is pressed onto the surface of the adhesive layer (B), and immediately thereafter, the resin material is peeled off from the cooling roll to form the resin layer (C), thereby producing a laminate.

[0103] When forming a resin layer (C) containing a P3HA-based resin by the lamination method, the heating temperature in the lamination method (hereinafter also referred to as the lamination temperature) is preferably a temperature in the range of the melting point (Tm) or higher of the resin composition constituting the resin layer (C) during lamination, and less than a temperature 30°C higher than the melting point (Tm). The melting point refers to the top temperature of the melting point peak on the highest temperature side in the crystalline melting curve obtained by differential scanning calorimetry. If the lamination temperature is lower than the melting point, the resin cannot be sufficiently fluidized, and the adhesive strength with the adhesive layer (B) tends to be insufficient. Furthermore, if the lamination temperature is 30°C higher than the melting point, the solidification rate of the P3HA-based resin after lamination slows, and as a result, sufficient peelability from the pressure-bonded surface tends to be insufficient. Specifically, the lamination temperature is preferably 160°C or higher, more preferably 165°C or higher, and particularly preferably 170°C or higher. The upper limit of the lamination temperature is preferably 180° C. or lower. When the lamination temperature is 180° C. or lower, a decrease in the mechanical strength of the resin layer (C) due to thermal decomposition of the P3HA-based resin tends to be avoided.

[0104] The lamination temperature may be set so that the temperature of the resin layer (C) containing the P3HA-based resin is within the above range during lamination. For example, in the case of extrusion lamination, the temperature of the T-die may be adjusted, and in the case of thermal lamination, the temperature of the heating roll used to bond the films may be adjusted.

[0105] The surface temperature of the cooling roll in the extrusion lamination method is not particularly limited as long as it is a temperature at which the resin layer (C) can be cooled and pressed, and can be determined appropriately. The surface temperature of the cooling roll may be, for example, 20 to 70°C, and preferably 40 to 60°C. When the surface temperature is within the above range, crystallization of the P3HA resin is promoted, resulting in reduced adhesion to the cooling roll and achieving solidification in a short period of time.

[0106] For the purpose of improving the adhesion between the resin layer (C) and the base material layer (A) on which the adhesive layer (B) is formed, the surface of the adhesive layer (B) may be subjected to corona treatment, plasma treatment, flame treatment, ozone treatment, etc.

[0107] From the viewpoint of adhesiveness and processability (balance between melting and crystallization), it is preferable that the steps (i) and (ii) are carried out successively.

[0108] [Molded Article] A molded article according to one aspect of the present embodiment includes the laminate described above and has a desired size and shape. The molded article is advantageous in various applications because it is formed from a laminate including a resin layer (C) containing a P3HA-based resin.

[0109] The molded article is not particularly limited as long as it contains the laminate, and examples thereof include paper, film, sheet, tube, plate, rod, container (e.g., bottle container), bag, part, etc. From the viewpoint of measures against marine pollution, the molded article is preferably a bag or a bottle container.

[0110] The molded article may be the laminate itself, or may be a laminate that has been subjected to secondary processing. By subjecting the laminate to secondary processing, the molded article can be suitably used as various packaging container materials such as shopping bags, various bags, food and confectionery packaging materials, cups, trays, cartons, etc. (in other words, in various fields such as food, cosmetics, electronics, medicine, and pharmaceuticals). Since the molded article includes a resin layer (C) that has high adhesion to the substrate and good heat resistance, it can be more suitably used as a container for holding liquids, particularly as a container for holding hot contents, such as a cup for food and beverages such as instant noodles, instant soup, and coffee, a tray for prepared meals, bento boxes, and microwaveable foods.

[0111] The secondary processing can be carried out in the same manner as conventional resin-laminated paper or coated paper, i.e., using various bag-making machines, filling and packaging machines, etc. Processing can also be carried out using machines such as paper cup forming machines, punching machines, box making machines, etc. In these processing machines, known techniques can be used to bond the laminate, such as heat sealing, impulse sealing, ultrasonic sealing, high-frequency sealing, hot air sealing, and frame sealing.

[0112] In order to improve the physical properties of the molded article, the molded article can be composited with another molded article made of a material different from the molded article (for example, fiber, thread, rope, woven fabric, knitted fabric, nonwoven fabric, paper, film, sheet, tube, plate, rod, container, bag, part, foam, etc.). These materials are also preferably biodegradable.

[0113] The following items are preferred embodiments of the present disclosure, but the present invention is not limited to the following items. [Item 1] A laminate comprising, in this order, a substrate layer (A), an adhesive layer (B), and a resin layer (C) containing a poly(3-hydroxyalkanoate) copolymer (c1), wherein the adhesive layer (B) contains a resin (b1) having a glass transition temperature of more than -20°C and not more than 0°C and an acid value of less than 40 mgKOH / g, and the adhesive layer (B) has a basis weight of 0.1 g / m ２ Above, 5.0g / m ２a laminate in which the thickness of the resin layer (C) is 5 μm or more and 100 μm or less. [Item 2] The laminate according to item 1, in which the resin (b1) is at least one selected from the group consisting of an acrylic resin, a styrene-acrylic resin, and a polyester resin. [Item 3] The laminate according to item 1 or 2, in which the adhesive layer (B) further contains a poly(3-hydroxyalkanoate)-based copolymer (b2). [Item 4] The laminate according to any one of items 1 to 3, in which the poly(3-hydroxyalkanoate)-based copolymer (c1) contains 50 wt % or more of a copolymer (c1-1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 to 10 mol %. [Item 5] The laminate according to item 4, in which the other hydroxyalkanoate units are 3-hydroxyhexanoate units. [Item 6] The laminate according to any one of Items 1 to 5, wherein the poly(3-hydroxyalkanoate) copolymer (c1) comprises a reaction product of the copolymer (c1) and an organic peroxide. [Item 7] A method for producing a laminate, comprising: step (i) of forming, on at least one surface of a substrate layer (A), an adhesive layer (B) comprising a resin (b1) having a glass transition temperature higher than -20°C and equal to or lower than 0°C and an acid value of less than 40 mgKOH / g; and step (ii) of forming, on the surface of the adhesive layer (B), a resin layer (C) comprising the poly(3-hydroxyalkanoate) copolymer (c1) by extrusion lamination. [Item 8] The production method according to Item 7, wherein step (i) is a step of applying a coating liquid comprising the resin (b1) to at least one surface of the substrate layer (A) and drying the coating liquid to form the adhesive layer (B). [Item 9] The method according to item 7 or 8, wherein the poly(3-hydroxyalkanoate) copolymer (c1) comprises a reaction product of the copolymer (c1) and an organic peroxide. [Item 10] A molded article comprising the laminate according to any one of items 1 to 5.

[0114] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0115] The P3HA-based resin pellets used as the resin layers in the examples and comparative examples were produced using the following P3HA powders. A-1: ​​Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a 3-hydroxyhexanoate (3HH) composition of 26.3 mol% and a standard polystyrene-equivalent weight average molecular weight measured by GPC of 360,000, according to the method described in Example 9 of WO 2019 / 142845 A-2: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a 3HH composition of 2.1 mol% and a standard polystyrene-equivalent weight average molecular weight measured by GPC of 360,000, according to the method described in Example 2 of WO 2019 / 142845 A-3: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a 3-hydroxyhexanoate (3HH) composition of 6.0 mol% and a weight average molecular weight of 220,000 in terms of standard polystyrene measured by GPC, obtained in accordance with the method described in Example 1 of WO 2019 / 142845

[0116] (Acid Value of Resin) The acid value of the resin was calculated from the acid value of each monomer constituting the resin and the weight fraction of each monomer according to the above formula.

[0117] (Glass Transition Temperature of Resin) The glass transition temperature of the resin was calculated from the glass transition temperature of the homopolymer of each monomer constituting the resin and the weight fraction of each monomer according to the above formula.

[0118] (Method for producing P3HA-based resin pellets) A-1 (24 parts by weight) and A-2 (16 parts by weight) as P3HA, tributylperoxyisopropyl monocarbonate (NOF Corporation: Perbutyl I, 1-minute half-life temperature: 158.8°C, 0.105 parts by weight) as an organic peroxide, plasticizer (Riken Vitamin Co., Ltd.: BIOCIZER, 0.42 parts by weight), pentaerythritol (Mitsubishi Chemical Corporation: Neuraizer P, 1.0 part by weight), and behenamide (Nippon Fine Chemicals Co., Ltd.: BNT-22H, 0.5 parts by weight) were fed from the main feeder, and A-3 (60 parts by weight) was fed from the side feeder into a co-rotating intermeshing twin-screw extruder (Toshiba Machine Co., Ltd.: TEM26SS (L / D = 60)), and melt-kneading was carried out at a barrel temperature of 140 to 160°C, a screw rotation speed of 100 rpm, and a discharge rate of 10 kg / hr. The P3HA (A-1 and A-2) introduced from the main feeder during this process was a reaction product with the organic peroxide. The strand obtained from the die was passed through a water tank filled with warm water at 40 to 45°C to solidify it, and then cut into P3HA-based resin pellets using a pelletizer.

[0119] (Example 1) Basis weight 210 g / m ２ On one side of the cup base paper, dry weight 1 g / m ２ An aqueous acrylic resin coating liquid AC-1 (SEIKOAT [TE-2316] manufactured by Seiko PMC Corporation, solid content concentration 40% by weight, glass transition temperature (Tg) -8°C, acid value 36 mgKOH / g) was applied using a bar coater so that the adhesive layer (B) was formed. The adhesive layer (B) was then heated for 2 minutes in a hot air drying oven set at 100°C.

[0120] Next, the P3HA-based resin pellets were fed into a single-screw extruder equipped with a T-type die, and extruded from the T-type die under conditions such that the resin temperature immediately after extrusion was 163°C. Using a cooling roll set at 40°C, the resin was laminated to a thickness of 20 μm on the adhesive layer (B) of the cup base paper with adhesive layer (B) prepared above, forming a resin layer (C), and a laminate was obtained.

[0121] (Examples 2 and 3) A laminate was obtained in the same manner as in Example 1, except that the aqueous acrylic resin coating liquid AC-1 was used and the basis weight of the adhesive layer (B) and the thickness of the resin layer (C) were changed to the contents shown in the table.

[0122] (Example 4) An aqueous dispersion HB-1 of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (average 3HH ratio 11 mol%, weight average molecular weight in terms of standard polystyrene measured by GPC 220,000, PHB content in the composition 6.3 wt%, solid content concentration 40 wt%) was blended with an aqueous acrylic resin coating liquid AC-1 in a solid content ratio of AC-1:HB-1 = 80 parts by weight:20 parts by weight, and stirred to prepare an aqueous polyester resin coating liquid AC-2 (solid content concentration 40%). A laminate was obtained by the same operation as in Example 2, except that the adhesive layer (B) was formed using this coating liquid AC-2.

[0123] (Examples 5 to 8) Aqueous styrene-acrylic resin coating liquid AC-3 (SEIKOAT [RE-2016] manufactured by Seiko PMC Corporation, solid content concentration 33 wt%, glass transition temperature (Tg) -19 ° C, acid value 31 mg KOH / g) was used, and laminates were obtained in the same manner as in Example 1, except that the basis weight of the adhesive layer (B) and the thickness of the resin layer (C) were set as shown in the table.

[0124] (Example 9) The aqueous acrylic resin coating liquid AC-3 was mixed with the aqueous dispersion liquid HB-1 of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) in a solids ratio of AC-3:HB-1 = 50 parts by weight:50 parts by weight, and stirred to prepare an aqueous polyester resin coating liquid AC-4 (solids concentration 30%). A laminate was obtained in the same manner as in Example 2, except that the adhesive layer (B) was formed using this coating liquid AC-4.

[0125] (Example 10) The aqueous acrylic resin coating solution AC-3 was mixed with the aqueous dispersion HB-1 of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) in a solids ratio of AC-3:HB-1 = 80 parts by weight:20 parts by weight, and stirred to prepare an aqueous polyester resin coating solution AC-5 (solids concentration 30%). A laminate was obtained in the same manner as in Example 2, except that the adhesive layer (B) was formed using this coating solution AC-5.

[0126] (Comparative Example 1) The P3HA resin pellets were charged into a single-screw extruder equipped with a T-die, and extruded from the T-die under conditions such that the resin temperature immediately after extrusion was 163°C. A cooling roll set at 40°C was used to extrude a 210 g / m2 P3HA resin pellet having no adhesive layer (B) formed thereon. ２ The laminate was laminated to a thickness of 30 μm on one side of the cup base paper.

[0127] (Comparative Example 2) Basis weight 210 g / m ２ On one side of the cup base paper, dry weight 3 g / m ２ An aqueous acrylic resin coating liquid AC-6 (SEIKOAT [RE-2194] manufactured by Seiko PMC Corporation, solid content concentration 38 wt %, glass transition temperature (Tg) 2°C, acid value 33 mgKOH / g) was applied using a bar coater so that the thickness of the coating became as shown in the figure, and then the coating was heated for 2 minutes in a hot air drying oven set at 100°C to form an adhesive layer (B).

[0128] Next, the P3HA-based resin pellets were fed into a single-screw extruder equipped with a T-type die, and extruded from the T-type die under conditions such that the resin temperature immediately after extrusion was 163°C. Using a cooling roll set at 40°C, the resin was laminated to a thickness of 30 μm on the adhesive layer (B) of the cup base paper with adhesive layer (B) prepared above, forming a resin layer (C), and a laminate was obtained.

[0129] Comparative Example 3 A laminate was obtained in the same manner as in Comparative Example 2, except that an aqueous acrylic resin coating liquid AC-7 (SEIKOAT [QE-2128] manufactured by Seiko PMC Corporation, solid content concentration 37% by weight, glass transition temperature (Tg) 63°C, acid value 38 mgKOH / g) was used.

[0130] (Comparative Examples 4 and 5) Laminates were obtained in the same manner as in Comparative Example 2, except that an aqueous styrene-acrylic resin coating liquid AC-8 (SEIKOAT [NE-2260] manufactured by Seiko PMC Corporation, solid content concentration 49 wt %, glass transition temperature (Tg) -10°C, acid value 53 mgKOH / g) was used and the basis weight of the adhesive layer (B) and the thickness of the resin layer (C) were set as shown in the table. The laminate strength of the laminates of Examples 1 to 10 and Comparative Examples 1 to 5 was evaluated.

[0131] (Evaluation of Laminate Strength) The day after extrusion lamination, a 30 mm long cross cut was made in the resin layer (C) with a cutter knife, the resin layer (C) was peeled off by hand, and the state of the peeled surface was visually inspected and evaluated according to the following criteria. The results are shown in Table 1. <Evaluation> ⊚: Cohesive failure of the paper occurs over the entire peeled surface. ◯: Cohesive failure of the paper occurs in some areas, but not in others. △: Cohesive failure of the paper occurs in some areas, but resistance to peeling is maintained. ×: Cohesive failure of the paper does not occur at all. If the above evaluation result is ⊚, ○, or △, it can be said that there is sufficient laminate strength.

[0132]

[0133] <Results> Table 1 shows that in each Example, the substrate layer (A) and the resin layer (C) containing the poly(3-hydroxyalkanoate) copolymer (c1) were bonded with sufficient strength via the adhesive layer (B). In contrast, in Comparative Example 1, in which the resin layer (C) was laminated directly on the substrate layer (A) without forming the adhesive layer (B), the adhesion was insufficient. Furthermore, in Comparative Examples 2 to 5, a resin with an excessively high glass transition temperature or an excessively high acid value was used in the adhesive layer (B), resulting in insufficient adhesion.

[0134] REFERENCE SIGNS LIST 1 Laminate 2 Base material layer (A) 3 Adhesive layer (B) 4 Resin layer (C)

Claims

1. A laminate comprising, in this order, a substrate layer (A), an adhesive layer (B), and a resin layer (C) containing a poly(3-hydroxyalkanoate) copolymer (c1), wherein the adhesive layer (B) contains a resin (b1) having a glass transition temperature of more than -20°C and not more than 0°C and an acid value of less than 40 mgKOH / g, and the adhesive layer (B) has a basis weight of 0.1 g / m ２ Above, 5.0g / m ２ and the resin layer (C) has a thickness of 5 μm or more and 100 μm or less.

2. The laminate according to claim 1, wherein the resin (b1) is at least one selected from the group consisting of acrylic resins, styrene-acrylic resins, and polyester resins.

3. The laminate according to claim 1 or 2, wherein the adhesive layer (B) further contains a poly(3-hydroxyalkanoate) copolymer (b2).

4. The laminate according to claim 1 or 2, wherein the poly(3-hydroxyalkanoate) copolymer (c1) contains 50% by weight or more of a copolymer (c1-1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 to 10 mol%.

5. The laminate according to claim 4, wherein said other hydroxyalkanoate units are 3-hydroxyhexanoate units.

6. The laminate according to claim 1 or 2, wherein the poly(3-hydroxyalkanoate) copolymer (c1) comprises a reaction product of the copolymer (c1) and an organic peroxide.

7. A method for producing a laminate, comprising: a step (i) of forming, on at least one surface of a substrate layer (A), an adhesive layer (B) containing a resin (b1) having a glass transition temperature of greater than -20°C and equal to or less than 0°C and an acid value of less than 40 mgKOH / g; and a step (ii) of forming, on the surface of the adhesive layer (B), a resin layer (C) containing a poly(3-hydroxyalkanoate) copolymer (c1) by extrusion lamination.

8. The manufacturing method according to claim 7, wherein step (i) is a step of applying a coating liquid containing resin (b1) to at least one surface of the substrate layer (A) and drying it to form an adhesive layer (B).

9. The method according to claim 7 or 8, wherein the poly(3-hydroxyalkanoate) copolymer (c1) comprises a reaction product of the copolymer (c1) with an organic peroxide.

10. A molded article comprising the laminate of claim 1 or 2.

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