Composition for hot melt adhesive

Abstract

Provided is a composition for hot melt adhesives, which contains a poly (3-hydroxyalkanoate)-based resin, has a reduced melt viscosity, and has good mechanical properties. The composition for a hot melt adhesive contains a poly (3-hydroxyalkanoate)-based resin (A) and a polycaprolactone (B). The poly (3-hydroxyalkanoate)-based resin (A) may be a poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer. A laminate can be produced by melting the composition for a hot-melt adhesive under heating, applying the molten composition to a first substrate, then bonding the applied surface to a second substrate, and cooling the composition to bond the first substrate and the second substrate.

Description

Technical Field

[0001] The present invention relates to a composition for hot-melt adhesives. Background Art

[0002] Hot melt adhesives are adhesives that are mainly composed of thermoplastic resins and are solid at room temperature. They are used for sealing cartons and paper boxes, etc.

[0003] When a hot melt adhesive is used, for example, the adhesive is melted by heating with a heat gun or the like, applied to the bonding surface, and then the substrates are bonded together. The adhesive can then be cooled and solidified to bond the substrates together.

[0004] Conventionally known resin materials as main components of such hot melt adhesives include ethylene-vinyl acetate (EVA) copolymers, ethylene-acrylate copolymers, polyolefins, polyamides, polyesters, polycarbonates, synthetic rubbers, and the like.

[0005] On the other hand, the impact of plastic waste on the ecosystem, the generation of harmful gases when burned, and the greenhouse effect caused by the large amount of combustion heat are becoming a burden on the global environment. As a material that can solve this problem, the development momentum of biodegradable plastics is growing stronger.

[0006] Patent Document 1 discloses a hot melt adhesive using biodegradable plastics, and more specifically, discloses a hot melt adhesive mainly composed of a polymer containing an aliphatic polyester segment composed of a lactic acid segment, a diol, and a dicarboxylic acid.

[0007] However, although biodegradable plastics such as polylactic acid can be biodegraded in compost or the like, it cannot be expected that they can be biodegraded in a short period of time in the ocean where the temperature is low.

[0008] Among them, poly(3-hydroxyalkanoate) resins are attracting attention because they are biodegradable materials even in seawater.

[0009] Patent Document 2 discloses the use of a solution of a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer, which is one type of poly(3-hydroxyalkanoate)-based resin, and an organic solvent as a biodegradable adhesive.

[0010] However, there are no reports showing the use of poly(3-hydroxyalkanoate)-based resins for hot-melt adhesives.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2021-102775

[0014] Patent Document 2: International Publication No. 2021 / 153250 Summary of the invention

[0015] Problems to be solved by the invention

[0016] During their research, the inventors found that poly(3-hydroxyalkanoate) resins generally have high melt viscosity, making it difficult to heat and melt them as hot melt adhesives and apply them to a substrate. On the other hand, when using poly(3-hydroxyalkanoate) resins with relatively low molecular weight, there is a problem that although the melt viscosity decreases, the mechanical properties are reduced.

[0017] In view of the above-mentioned current situation, an object of the present invention is to provide a hot-melt adhesive composition containing a poly(3-hydroxyalkanoate)-based resin, having a reduced melt viscosity and excellent mechanical properties.

[0018] Solution to the problem

[0019] The present inventors have conducted intensive studies and have found that a hot melt adhesive composition having a reduced melt viscosity and good mechanical properties can be provided by combining a poly(3-hydroxyalkanoate) resin with polycaprolactone as a biodegradable resin to produce a hot melt adhesive, thereby completing the present invention.

[0020] That is, the present invention relates to a hot-melt adhesive composition containing a poly(3-hydroxyalkanoate)-based resin (A) and polycaprolactone (B).

[0021] In addition, the present invention also relates to a method for manufacturing a laminate, which comprises: melting the above-mentioned hot-melt adhesive composition under heating, applying it to a first substrate, bonding the coated surface to a second substrate, cooling the composition, and bonding the first substrate and the second substrate to manufacture a laminate.

[0022] Effects of the Invention

[0023] According to the present invention, a hot-melt adhesive composition can be provided which contains a poly(3-hydroxyalkanoate)-based resin and has a reduced melt viscosity and excellent mechanical properties. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0025] The hot-melt adhesive composition of the present embodiment contains at least a poly(3-hydroxyalkanoate)-based resin (A) and polycaprolactone (B).

[0026] <Poly(3-hydroxyalkanoate)-based resin (A)>

[0027] Poly(3-hydroxyalkanoate) resin is a general term for polymers containing at least 3-hydroxyalkanoic acid as a monomer unit, and is generally biodegradable. Poly(3-hydroxyalkanoate) resin is sometimes referred to as P3HA hereinafter. P3HA is an aliphatic polyester, preferably a polyester without an aromatic ring. As P3HA, only one type may be used, or two or more types may be used in combination.

[0028] The above-mentioned P3HA preferably contains a 3-hydroxyalkanoic acid repeating unit represented by the formula: [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 In the above P3HA, it is preferred that 50 mol % or more, more preferably 70 mol % or more, of the 3-hydroxyalkanoic acid repeating unit represented by the above formula is contained in all monomer repeating units (100 mol %).

[0029] The above-mentioned P3HA may be a homopolymer or a copolymer. When the above-mentioned P3HA is a copolymer, it may be a copolymer containing two or more repeating units represented by the above formula, or a copolymer containing the repeating unit represented by the above formula and other repeating units. In addition, the form of copolymerization is not particularly limited, and may be random copolymerization, alternating copolymerization, block copolymerization, graft copolymerization, etc., and random copolymerization is preferred because it is easy to obtain.

[0030] Specific examples of P3HA include poly(3-hydroxybutyrate) (abbreviation: P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (abbreviation: P3HB3HO), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate) (abbreviation: P3HB3HOD), poly(3-hydroxybutyrate-co-3-hydroxydecanoate) (abbreviation: P3HB3HD), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HV3HH), etc. Among them, P3HB, P3HB3HH, P3HB3HV, and P3HB4HB are preferred from the viewpoint of easy industrial production.

[0031] By changing the composition ratio of the repeating units in P3HA, the melting point or crystallinity of PHA can be changed, and ultimately the physical properties such as Young's modulus and heat resistance can be changed. In addition, from the viewpoint of being able to impart physical properties between polypropylene and polyethylene, being easy to industrially produce, and being a plastic useful in terms of physical properties, P3HB3HH, which is a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoic acid, is particularly preferred.

[0032] P3HA can be produced by microorganisms. P3HA produced by such microorganisms is usually composed of only D-type (R-type) hydroxyalkanoic acid repeating units. From the perspective of ease of industrial production, among the P3HA produced by microorganisms, P3HB and P3HB3HH are preferred, and P3HB3HH is more preferred.

[0033] When P3HA contains 3-hydroxybutyrate (3HB) units, the average content ratio of repeating units in P3HA is preferably 97 / 3 to 75 / 25 (mol / mol), more preferably 95 / 5 to 80 / 20 (mol / mol), and particularly preferably 95 / 5 to 85 / 15 (mol / mol), from the viewpoint of balance between flexibility, handleability, and initial fixation.

[0034] When the average content ratio of the above-mentioned other hydroxyalkanoate units in P3HA is 3 mol% or more, the flexibility of P3HA can be improved, the melting point is lowered, and the workability when the hot melt adhesive composition is melt-coated can also be improved. In addition, when the average content ratio of the above-mentioned other hydroxyalkanoate units in P3HA is 25 mol% or less, a moderate crystallization rate can be achieved, and the initial fixation when the hot melt adhesive composition is melt-coated and bonded to other substrates can be improved.

[0035] As P3HA, two or more P3HAs having different average content ratios of repeating units may be used in combination. In this case, the numerical range of the average content ratio refers to the average content ratio of the repeating units contained in the mixture of the two or more P3HAs contained in the hot melt adhesive composition.

[0036] The average content ratio of the repeating units of P3HA can be measured by hydrolysis to monomer units or alcohol esterification gas chromatography or the like (for example, refer to International Publication No. 2014 / 020838).

[0037] The molecular weight of P3HA is not particularly limited. From the perspective of the balance between adhesive strength and operability during melt coating, the weight average molecular weight is preferably 10,000 to 1,500,000, more preferably 100,000 to 1,000,000, and further preferably 150,000 to 800,000. When the weight average molecular weight is 10,000 or more, the strength of the adhesive layer becomes good and sufficient adhesive strength can be achieved. On the other hand, when it is 1,500,000 or less, the melt viscosity decreases, and the operability when the hot melt adhesive composition is melt-coated becomes good.

[0038] As P3HA, two or more P3HAs having different weight average molecular weights may be used in combination. In particular, from the viewpoint of particularly excellent balance between reduced melt viscosity and good mechanical properties, a P3HA having a higher molecular weight and a P3HA having a lower molecular weight may be used in combination. The weight average molecular weights shown by the two P3HAs may be appropriately selected from the above-mentioned weight average molecular weight range.

[0039] The determination method of the above-mentioned weight average molecular weight can be gel permeation chromatography (GPC) (Showa Denko Co., Ltd. [Shodex GPC-101]), and the chromatographic column utilizes polystyrene gel (Showa Denko Co., Ltd. [Shodex K-804]), and chloroform is used as the mobile phase to obtain the molecular weight in the case of polystyrene conversion. As the chromatographic column on the GPC, a suitable chromatographic column for measuring the above-mentioned molecular weight can be used.

[0040] As a microorganism producing P3HA, there is no particular limitation as long as it is a microorganism with the ability to produce P3HA. For example, as a P3HB-producing bacterium, Bacillus megaterium discovered in 1925 and other known natural microorganisms such as Cupriavidus necator (old classification: Alcaligenes eutrophus, Ralstonia eutropha, Alcaligenes latus) are known. P3HB accumulates in the cells of these microorganisms.

[0041] In addition, as a producer of copolymers of 3HB and other hydroxyalkanoates, there are known P3HB3HV and P3HB3HH-producing bacteria Aeromonas caviae, P3HB4HB-producing bacteria Alcaligenes eutrophus, etc. In particular, with regard to P3HB3HH, in order to improve the productivity of P3HB3HH, it is preferred to introduce the genes of the P3HA synthase group Alcaligenes eutrophus AC32 strain (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)). Microbial cells that accumulate P3HA in the cell body and are cultured under appropriate conditions can be used. In addition, in addition to the above, according to the desired P3HA to be produced, genetically recombinant microorganisms into which various P3HA synthesis-related genes are introduced can also be used, and the culture conditions including the type of substrate need only be optimized.

[0042] <Polycaprolactone (B)>

[0043] Polycaprolactone is a polyester having a monomer unit represented by the formula: [-(CH2)5-CO-O-]. Polycaprolactone is sometimes referred to as PCL below. PCL can usually be produced by ring-opening polymerization of ε-caprolactone using a cationic or anionic initiator. In order to promote polymerization, an organic metal catalyst is sometimes used. However, PCL obtained by other production methods can also be used. In addition, the end-capping structure is not particularly limited. PCL generally has a melting point of 50~65°C, a crystallization temperature of 10~30°C, and a glass transition temperature of -50~-60°C, which are not limited.

[0044] The molecular weight of PCL is not particularly limited. From the perspective of the balance between adhesive strength and operability during melt coating, the weight average molecular weight is preferably 1000 to 500000, more preferably 5000 to 400000, further preferably 10000 to 300000, and particularly preferably 20000 to 250000. When the weight average molecular weight is 1000 or more, the strength of the adhesive layer becomes good and sufficient adhesive strength can be achieved. On the other hand, when it is 500000 or less, the melt viscosity decreases, and the operability when the hot melt adhesive composition is melt-coated can be improved.

[0045] In particular, from the viewpoint of further improving mechanical properties such as strength and elongation, the weight average molecular weight of PCL is preferably 100,000 or more, more preferably 120,000 or more.

[0046] On the other hand, from the viewpoint of further reducing the melt viscosity, the weight average molecular weight of PCL is preferably less than 100,000, more preferably 90,000 or less, and even more preferably 70,000 or less.

[0047] As PCL, two or more PCLs having different weight average molecular weights may be used in combination. In particular, from the perspective of excellent balance between reduced melt viscosity and good mechanical properties, a combination of a first PCL having a higher molecular weight and a second PCL having a lower molecular weight is preferred.

[0048] In this embodiment, the weight average molecular weight of the first PCL is preferably 100,000 or more, more preferably 120,000 or more. The weight average molecular weight of the second PCL is preferably 70,000 or less, more preferably 50,000 or less, and further preferably 40,000 or less.

[0049] The ratio of the first PCL with a higher molecular weight to the second PCL with a lower molecular weight is not particularly limited, and the weight ratio of the first PCL / the second PCL is preferably 95 / 5 to 40 / 60, more preferably 90 / 10 to 50 / 50, and further preferably 85 / 15 to 60 / 40. When the two PCLs are used in combination within this range, it is possible to achieve both the improvement of the mechanical properties based on the first PCL and the reduction of the melt viscosity based on the second PCL at a high level.

[0050] The weight average molecular weight of PCL can be measured by the same method as that used to measure the weight average molecular weight of P3HA.

[0051] In the above-mentioned hot melt adhesive composition, although the content ratio of poly (3-hydroxyalkanoate) resin (A) and polycaprolactone (B) can be appropriately set, the weight ratio of (A) component / (B) component is preferably 95 / 5~5 / 95. Within this range, a hot melt adhesive composition having a reduced melt viscosity and good mechanical properties while utilizing a poly (3-hydroxyalkanoate) resin having seawater decomposability can be provided. The above-mentioned weight ratio is more preferably 90 / 10~10 / 90, further preferably 80 / 20~20 / 80, and particularly preferably 70 / 30~30 / 70. In addition, it can be 95 / 5~50 / 50, or 50 / 50~5 / 95. From the viewpoint of further reduced melt viscosity, it is preferably 50 / 50~5 / 95.

[0052] <Fatty acid glyceride (C)>

[0053] The hot melt adhesive composition of this embodiment may further contain fatty acid glyceride (C). By adding fatty acid glyceride (C), the melt viscosity can be greatly reduced while maintaining mechanical properties to a certain extent.

[0054] As fatty acid glyceryl esters, monoesters, diesters, or triesters of glycerol may be used, but from the perspective of compatibility with poly(3-hydroxyalkanoate) resin (A) and polycaprolactone (B), triesters of glycerol are preferred. Among the triesters of glycerol, diacetic glycerol monoester is particularly preferred. Specific examples of diacetic glycerol monoester include: diacetic glycerol monolaurate, diacetic glycerol monooleate, diacetic glycerol monostearate, diacetic glycerol monocaprylate, diacetic glycerol monocaprate, and the like. Among them, diacetic glycerol monolaurate is preferred. As commercially available products of the above-mentioned modified glycerol compounds, "BIOCIZER", "RIKEMAL" (registered trademark) PL series of Riken Vitamin Co., Ltd., and the like can be cited.

[0055] In the hot melt adhesive composition, the content of fatty acid glyceride (C) is preferably 0 to 50 parts by weight relative to 100 parts by weight of the total of the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B). The lower limit is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and further preferably 5 parts by weight or more. The upper limit is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and further preferably 15 parts by weight or less.

[0056] <Other ingredients>

[0057] As resin components, the hot melt adhesive composition may contain only poly(3-hydroxyalkanoate) resin (A) and polycaprolactone (B), or may further contain other resins. Such other resins are preferably biodegradable resins, for example, aliphatic polyester resins such as polybutylene succinate and polylactic acid, aliphatic aromatic polyester resins such as polybutylene terephthalate adipate, polybutylene terephthalate sebacate, and polybutylene terephthalate azelate, etc.

[0058] The content of these other resins may be about 0 to 30 parts by weight, preferably 0 to 10 parts by weight, more preferably 0 to 5 parts by weight, and particularly preferably 0 to 1 part by weight, relative to 100 parts by weight of the total of the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B).

[0059] The hot melt adhesive composition may further contain a plasticizer other than the fatty acid glyceride (C). Such a plasticizer is not particularly limited, and examples thereof include dibasic acid ester compounds, adipic acid ester compounds, polyether ester compounds, benzoic acid ester compounds, citrate compounds, and isosorbide compounds.

[0060] Examples of the above-mentioned dibasic acid ester compounds include: dibutyl adipate, diisobutyl adipate, di(2-ethylhexyl adipate), diisononyl adipate, diisodecyl adipate, di[2-(2-butoxyethoxy)ethyl adipate], di[2-(2-butoxyethoxy)ethyl adipate], di(2-ethylhexyl) azelaic acid, dibutyl sebacate, di(2-ethylhexyl) sebacate, diethyl succinate, mixed dibasic acid ester compounds, and the like.

[0061] Examples of the adipate-based compounds include diethylhexyl adipate, dioctyl adipate, and diisononyl adipate.

[0062] Examples of the polyether ester compound include polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate.

[0063] The content of plasticizers other than fatty acid glyceride (C) can be about 0 to 30 parts by weight, preferably 0 to 10 parts by weight, more preferably 0 to 5 parts by weight, and particularly preferably 0 to 1 part by weight, relative to 100 parts by weight of the total of the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B).

[0064] The hot melt adhesive composition may contain additives that are commonly used in the adhesive field. As such additives, inorganic fillers such as talc, calcium carbonate, mica, silica, titanium oxide, and alumina can be cited; waste paper such as rice husks, sawdust, and newspapers, various starches, cellulose, and other organic fillers; colorants such as pigments and dyes; odor adsorbents such as activated carbon and zeolite; spices such as vanillin and dextrin; antioxidants, antioxidants, weathering agents, ultraviolet absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, sliding improvers, adhesives, fillers, and agents can be included. The additive may contain only one or more. In addition, the solid content concentration of the additive can be appropriately set according to its purpose of use.

[0065] <Hot-melt adhesive composition>

[0066] The hot melt adhesive composition of the present embodiment is solid or semisolid at room temperature (usually about 15 to 30° C.) and does not exhibit fluidity suitable for coating at room temperature, but exhibits fluidity suitable for coating by melting it at an appropriate temperature.

[0067] The hot melt adhesive composition contains substantially no volatile organic solvent or water. Specifically, the total amount of organic solvent and water in the hot melt adhesive composition is preferably 10 wt % or less, more preferably 1 wt % or less, and even more preferably 0.1 wt % or less.

[0068] The hot-melt adhesive composition may be used as a hot-melt adhesive as it is, or may be used as a hot-melt adhesive after adding appropriate additives or adjusting the shape.

[0069] The shape of the hot-melt adhesive composition is not particularly limited, and may be a general shape of a hot-melt adhesive, specifically, a stick shape, a pellet shape, a sheet shape, or a film shape.

[0070] The viscosity of the hot-melt adhesive composition when heated and melted, that is, the melt viscosity, is low, and therefore, the workability when the hot-melt adhesive composition is melt-coated on a substrate can be improved.

[0071] As an indicator of such a low melt viscosity, the hot melt adhesive composition has a shear rate of 1.2×10 2 s -1 The melt viscosity measured using a Capillograph at a temperature of 150° C. is preferably 2900 Pa·s or less, more preferably 2000 Pa·s or less, further preferably 1500 Pa·s or less, and particularly preferably 1000 Pa·s or less.

[0072] The hot melt adhesive composition can be used to bond two substrates after being heated and melted. Specifically, the hot melt adhesive composition can be heated and melted, applied to a first substrate, and then the applied surface is attached to a second substrate, and the composition is cooled and solidified, thereby bonding the first substrate and the second substrate. When the hot melt adhesive composition is heated and applied to the first substrate, a glue gun or a hot air gun can be used.

[0073] Alternatively, the hot-melt adhesive composition may be placed on the first substrate and the second substrate, and then the composition may be heated to melt and then cooled to bond the first substrate and the second substrate.

[0074] The heating temperature when melting the hot-melt-adhesive composition can be appropriately set in consideration of the melting point of the hot-melt-adhesive composition, and can be, for example, in the range of about 100 to 180°C.

[0075] The type of the substrate on which the hot-melt adhesive composition can be used is not particularly limited, but since the hot-melt adhesive composition is biodegradable, the substrate is preferably also biodegradable. The shape of the substrate is not particularly limited.

[0076] The substrate showing biodegradability is not particularly limited, and examples thereof include: paper (mainly composed of cellulose), cellophane, cellulose ester, polyvinyl alcohol, polyamino acid, polyglycolide, pullulan, biodegradable polyester, etc. In addition, materials obtained by vapor-depositing inorganic substances such as aluminum and silicon on these substrates can also be used as the above-mentioned substrate. Among them, paper or biodegradable polyester is preferred from the perspective of excellent heat resistance and excellent biodegradability.

[0077] The type of paper is not particularly limited, and examples thereof include waxed paper for paper cups, single-sided glossy paper, kraft paper, full-grain pulp paper, coated paper, thin paper, glassine paper, and cardboard.

[0078] The biodegradable polyester that can constitute the above-mentioned substrate is not particularly limited, and examples thereof include aliphatic polyester resins such as polybutylene succinate (PBS) resins, polycaprolactone resins, and polyhydroxyalkanoate resins, and aliphatic aromatic polyester resins such as polybutylene terephthalate adipate (PBAT) resins, polybutylene terephthalate sebacate, and polybutylene terephthalate succinate resins.

[0079] The above-mentioned substrate may be added with a water-resistant agent, a water-repellent agent, an inorganic substance, etc., as needed, or may be subjected to surface treatment such as oxygen barrier coating or water vapor barrier coating.

[0080] The use of the hot-melt adhesive composition is not particularly limited, and it can be used for various bonding. Specific examples include sealing of cardboard boxes, sealing of thick paper boxes (paper boxes), and assembling of sanitary materials (such as disposable diapers).

[0081] Preferred aspects of the present disclosure are listed in the following items, but the present invention is not limited to the following items.

[0082] [Project 1]

[0083] A hot-melt adhesive composition comprises a poly(3-hydroxyalkanoate) resin (A) and polycaprolactone (B).

[0084] [Project 2]

[0085] The hot-melt adhesive composition according to item 1, wherein

[0086] The poly(3-hydroxyalkanoate)-based resin (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0087] [Item 3]

[0088] The hot-melt adhesive composition according to item 2, wherein

[0089] The average content ratio of 3-hydroxyhexanoate units in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is 3 to 25 mol %.

[0090] [Item 4]

[0091] The hot melt adhesive composition according to any one of items 1 to 3, wherein the hot melt adhesive composition is 2 s -1 The melt viscosity measured at a temperature of 150°C is less than 2900 Pa·s.

[0092] [Item 5]

[0093] The hot-melt adhesive composition according to any one of items 1 to 4, wherein

[0094] The weight average molecular weight of the poly(3-hydroxyalkanoate)-based resin (A) is 100,000 to 1,000,000.

[0095] [Item 6]

[0096] The hot-melt adhesive composition according to any one of items 1 to 5, wherein

[0097] The weight average molecular weight of polycaprolactone (B) is 20,000 to 250,000.

[0098] [Item 7]

[0099] The hot-melt adhesive composition according to any one of items 1 to 6, wherein

[0100] The polycaprolactone (B) contains two or more types of polycaprolactones having weight average molecular weights different from each other.

[0101] [Item 8]

[0102] The hot-melt adhesive composition according to any one of items 1 to 7, wherein

[0103] The weight ratio of the poly(3-hydroxyalkanoate) resin (A) / polycaprolactone (B) is 95 / 5 to 5 / 95.

[0104] [Item 9]

[0105] The hot-melt adhesive composition according to any one of Items 1 to 8, further comprising a fatty acid glyceride (C).

[0106] [Item 10]

[0107] The hot-melt adhesive composition according to item 9, wherein

[0108] The fatty acid glyceride (C) is glyceryl diacetate monolaurate.

[0109] [Item 11]

[0110] The hot-melt adhesive composition according to item 9 or 10, wherein

[0111] The content of the fatty acid glyceride (C) is 50 parts by weight or less based on 100 parts by weight of the total of the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B).

[0112] [Item 12]

[0113] A method for manufacturing a laminate, the method comprising:

[0114] The laminate is produced by melting the hot-melt adhesive composition according to any one of items 1 to 11 under heating, applying the composition to a first substrate, laminating the applied surface to a second substrate, and cooling the composition to bond the first substrate to the second substrate.

[0115] Example

[0116] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

[0117] The following raw materials were used in Examples and Comparative Examples.

[0118] [Poly(3-hydroxyalkanoate)-based resin (A) used]

[0119] Poly(3-hydroxyalkanoate) resin (A-1): average content ratio 3HB / 3HH=89 / 11 (mol% / mol%), weight average molecular weight 600,000 g / mol

[0120] Poly(3-hydroxyalkanoate) resin (A-2): average content ratio 3HB / 3HH=89 / 11 (mol% / mol%), weight average molecular weight 200,000 g / mol

[0121] [Polycaprolactone (B)]

[0122] (B-1): Poly-ε-caprolactone: manufactured by Fuji Film Wako Pure Chemical Industries, weight average molecular weight 28500

[0123] (B-2): Capa6250: Made by Ingevity, weight average molecular weight 66200

[0124] (B-3): Capa6400: Made by Ingevity, weight average molecular weight 80900

[0125] (B-4): Capa6500: manufactured by Ingevity, weight average molecular weight 138800

[0126] (B-5): Capa6800: Made by Ingevity, weight average molecular weight 232500

[0127] Fatty acid glycerides (C): BIOCIZER manufactured by Riken Vitamin

[0128] [Method for measuring weight average molecular weight]

[0129] The weight average molecular weight of each resin was determined as a molecular weight in terms of polystyrene by gel permeation chromatography (GPC) (Shodex GPC-101 manufactured by Showa Denko K.K.) using a polystyrene gel (Shodex K-804 manufactured by Showa Denko K.K.) as a column and chloroform as a mobile phase.

[0130] (Examples 1 to 42)

[0131] Into a kneading / extrusion tester (Laboplast Mill manufactured by Toyo Seiki Seisaku-sho, Ltd.), a poly(3-hydroxyalkanoate) resin (A) and polycaprolactone (B) were charged so as to give a total amount of 40 g at the weight ratio described in each table, and kneaded at 150° C. for 5 to 10 minutes.

[0132] In Examples 33 to 42, the total amount of (A) + (B) was 40 g as 100 parts by weight, and fatty acid glyceride (C) in the parts by weight shown in the table was added to the above-mentioned kneading / extrusion tester and kneaded in the same manner.

[0133] (Comparative Examples 1 and 2)

[0134] As described in the table, only the poly(3-hydroxyalkanoate)-based resin (A) was used.

[0135] [Melt viscosity]

[0136] The melt viscosity of the kneaded product obtained in each example or the melt viscosity of the poly(3-hydroxyalkanoate) resin (A) in Comparative Examples 1 and 2 was measured by Capillograph. The measurement temperature was set to 150°C. The melt viscosity of the kneaded product obtained in each example or the melt viscosity of the poly(3-hydroxyalkanoate) resin (A) in Comparative Examples 1 and 2 was measured by Capillograph ... 2 S -1 ) at a melt viscosity (Pa·s).

[0137] [Tensile test]

[0138] The kneaded products obtained in each example or the poly(3-hydroxyalkanoate)-based resin (A) in Comparative Examples 1 and 2 were press-molded at 160°C to obtain a 100 μm thick sheet. A No. 3 dumbbell-shaped test piece was cut from the obtained sheet and used as a sample for a tensile test.

[0139] The tensile test was performed using AG-2000A manufactured by Shimadzu Corporation, with the measurement temperature at 23° C. and the tensile speed at 50 mm / min. The strength at break (MPa) and the elongation at break (%) are shown in each table.

[0140]

[0141]

[0142]

[0143] Table 1 shows the results of Comparative Examples 1 and 2 in which the melt viscosity and tensile test evaluation of the poly(3-hydroxyalkanoate) resin (A) alone were performed. In Comparative Example 1, although the mechanical properties were good, the melt viscosity was high and it was not suitable for use as a hot melt adhesive. On the other hand, Comparative Example 2 using the poly(3-hydroxyalkanoate) resin (A) with a lower molecular weight showed a lower melt viscosity than Comparative Example 1, but the elongation at break was significantly reduced.

[0144] The kneaded products prepared by combining the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B) were evaluated for melt viscosity and tensile test in each of the Examples in Tables 2 to 6. All of the Examples can be used as hot melt adhesives having a lower melt viscosity than that of Comparative Example 1. In addition, the elongation at break is higher than that of Comparative Example 2, and the mechanical properties are good.

Claims

1. A hot-melt adhesive composition comprising a poly(3-hydroxyalkanoate) resin (A) and polycaprolactone (B).

2. The hot-melt adhesive composition according to claim 1, wherein The poly(3-hydroxyalkanoate)-based resin (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

3. The hot-melt adhesive composition according to claim 2, wherein The average content ratio of 3-hydroxyhexanoate units in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is 3 to 25 mol %.

4. The hot melt adhesive composition according to claim 1 or 2, which has a shear rate of 1.2×10 2 s -1 The melt viscosity measured at a temperature of 150°C is less than 2900 Pa·s.

5. The hot-melt adhesive composition according to claim 1 or 2, wherein The weight average molecular weight of the poly(3-hydroxyalkanoate)-based resin (A) is 100,000 to 1,000,000.

6. The hot-melt adhesive composition according to claim 1 or 2, wherein The weight average molecular weight of polycaprolactone (B) is 20,000 to 250,000.

7. The hot-melt adhesive composition according to claim 1 or 2, wherein The polycaprolactone (B) contains two or more types of polycaprolactones having weight average molecular weights different from each other.

8. The hot-melt adhesive composition according to claim 1 or 2, wherein The weight ratio of the poly(3-hydroxyalkanoate) resin (A) / polycaprolactone (B) is 95 / 5 to 5 / 95. 9 . The hot-melt adhesive composition according to claim 1 , further comprising fatty acid glyceride (C).

10. The hot-melt adhesive composition according to claim 9, wherein The fatty acid glyceride (C) is glyceryl diacetate monolaurate.

11. The hot-melt adhesive composition according to claim 9, wherein The content of the fatty acid glyceride (C) is 50 parts by weight or less based on 100 parts by weight of the total of the poly(3-hydroxyalkanoate) resin (A) and the polycaprolactone (B).

12. A method for manufacturing a laminate, the method comprising: The hot-melt adhesive composition according to claim 1 or 2 is melted under heating, applied to a first substrate, the applied surface is bonded to a second substrate, and the composition is cooled to bond the first substrate to the second substrate, thereby producing a laminate.

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