Adhesive composition

Abstract

To provide an adhesive composition employing α-glucose with reduced environmental impact.SOLUTION: An adhesive composition comprising a saccharide derivative in which at least a part of hydrogen of hydroxyl groups contained in a saccharide having α-glucose structural units and having a weight-average molecular weight (Mw) of 5000 or more and 20000 or less, or a saccharide having xylose structural units and having a weight-average molecular weight (Mw) of 200 or more and 2000 or less, is substituted with a substituent, and a tackifying resin having a softening point of 80°C or more, wherein the substituent of the saccharide derivative may be a linear or branched aliphatic hydrocarbon chain or may be a structure having an aromatic ring, and the tackifying resin is a terpene-based resin and / or a rosin-based resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition using a biomass raw material, and in particular to a hot melt adhesive composition. [Background technology]

[0002] Conventionally, adhesive materials have been produced using components synthesized from petroleum-derived chemical substances. However, the use of petroleum-derived components poses a problem of significant environmental impact. To address this problem, Patent Document 1 proposes an adhesive composition using a plant-derived β-1,3-glucan derivative. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 118677 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the plant-derived β-1,3-glucan proposed in Patent Document 1 results in heterogeneous derivatization reactions, resulting in poor reaction efficiency and the need for large amounts of solvent. This is thought to be due to the high molecular weight of plant-derived β-1,3-glucan, its strong intermolecular interactions, and its triple helix structure. The weight-average molecular weight (Mw) of plant-derived β-1,3-glucan paramylon is 100,000 to 400,000, while that of other plant-derived β-1,3-glucans, such as pachyman and curdlan, is even higher. In fact, when producing paramylon derivatives in the examples of Patent Document 1, due to its poor solubility and high solution viscosity after dissolution, approximately 100 times the amount of pyridine solvent was required in a heterogeneous system. The use of such large amounts of solvent places a heavy burden on the environment and reduces productivity. To avoid the use of large amounts of solvent, the molecular weight of β-1,3-glucan can be reduced using acids or enzymes, but this not only complicates the process but also makes it difficult to control the molecular weight and molecular weight distribution.

[0005] To solve these problems, the inventors discovered an adhesive composition that uses α-glucan or xylan with a specific molecular weight as the sugar, resulting in high reaction efficiency and production using a process with low environmental impact. For example, α-1,4-glucan amylose or xylan has weak intermolecular interactions and can react while dissolved in an organic solvent such as pyridine. This results in higher reaction efficiency than β-1,3-glucan, and allows for a reduction in the amount of solvent required. Furthermore, it can be dissolved in aqueous solvents, enabling reactions without the use of organic solvents. [Means for solving the problem]

[0006] The adhesive composition of one aspect of this embodiment has an α-glucose structural unit. Heavy The composition comprises a saccharide derivative in which at least some of the hydrogen atoms of the hydroxyl groups contained in a saccharide having a weight-average molecular weight (Mw) of 5,000 or more and 20,000 or less, or a saccharide having a xylose structural unit and a weight-average molecular weight (Mw) of 200 or more and 2,000 or less, are substituted with a substituent, and a tackifier resin having a softening point of 80° C. or more. The substituent of the saccharide derivative comprises the structure of the following formula 1 or 2, and the tackifier resin is a terpene resin and / or a rosin resin. [ka] (Formula 1) [ka] (Formula 2) In formula 1, R1 is a straight-chain, branched-chain, saturated, or unsaturated aliphatic hydrocarbon group. In formula 2, R2 is an aromatic hydrocarbon group or an aliphatic hydrocarbon group different from R1. The C=O bond in parentheses in formulas 1 and 2 may not be included.

[0007] It is preferable that 10 - 90% of the hydrogens of the hydroxyl groups contained in the saccharide are substituted with the substituent of (Formula 1) and 90 - 10% are substituted with the substituent of (Formula 2). In (Formula 2), R2 may be an aromatic-containing group or an aliphatic hydrocarbon group different from (Formula 1). In this specification, the numerical range n1 - n2 means n1 or more and n2 or less when n1 < n2, and means n2 or more and n1 or less when n1 > n2.

[0008] The adhesive composition according to another aspect of this embodiment contains a saccharide derivative in which at least a part of the hydrogens of the hydroxyl groups contained in a saccharide having a weight average molecular weight (Mw) of 5000 or more and 20000 or less having an α-glucose structural unit or a saccharide having a weight average molecular weight (Mw) of 200 or more and 2000 or less having a xylose structural unit are substituted with a substituent, and a tackifying resin having a softening point of 80°C or more. The substituent of the saccharide derivative contains the structure of the following (Formula 1), and the tackifying resin is a terpene resin and / or a rosin resin.

Chemical formula

[0009] The adhesive composition preferably contains a derivative of amylose, which is a saccharide having an α-glucose structural unit. The content of the tackifying resin contained in the adhesive composition is preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the saccharide derivative. Moreover, it is preferable that the softening point of the tackifying resin of the adhesive composition is 80°C or more and 110°C or less.

Advantages of the Invention

[0010] The adhesive composition according to one aspect of this embodiment has good reaction efficiency and can be produced in a process with low environmental impact.

Modes for Carrying Out the Invention

[0011] <<Adhesive composition>> The adhesive composition of this embodiment contains a saccharide derivative and a tackifier resin in specific blending amounts. In particular, the adhesive composition of this embodiment is a hot-melt adhesive composition that is melted by applying heat. A curing agent / softening agent, etc. may be added to the adhesive composition as needed.

[0012] <<Sugars>> The saccharide used in the saccharide derivative of this embodiment is at least one saccharide selected from amylose having a weight-average molecular weight (Mw) of 5,000 to 20,000 and xylan having a weight-average molecular weight (Mw) of 200 to 2,000. The saccharide of this embodiment is highly soluble in various solvents, such as water, pyridine, DMSO, and DMF, allowing for easy synthesis and purification processes, resulting in high yields of the derivative. The saccharide of this embodiment is preferably a plant-derived raw material (biomass raw material). When the molecular weight (Mw) of amylose is less than 5,000, the cohesive strength tends to decrease at high temperatures, resulting in poor heat resistance as an adhesive, making it difficult to use amylose in adhesive compositions. On the other hand, when the molecular weight (Mw) of amylose is greater than 20,000, the solubility in the reaction solvent decreases, limiting the reaction system and making it difficult to synthesize the desired saccharide derivative. In particular, amylose having a molecular weight (Mw) of 6,000 or more and 15,000 or less is preferred, considering that it can be easily obtained by simple processing when extracted from natural products.

[0013] If the molecular weight (Mw) of xylan is less than 200, the cohesive strength is likely to decrease at high temperatures, and the heat resistance as an adhesive is low, making it difficult to use xylan as an adhesive composition. On the other hand, if the molecular weight (Mw) of xylan is greater than 2000, the solubility in the reaction solvent decreases, restricting the reaction system and making it difficult to synthesize the target saccharide derivative. It is preferable that the molecular weight (Mw) of xylan is 300 or more and 1500 or less.

[0014] <Amylose> The amylose of this embodiment has a molecular weight (Mw) of 5,000 to 20,000, and includes polysaccharides in which glucose structural units are arranged in a linear chain via α-[1,4] glycosidic bonds, and polysaccharides in which some of the glucose structural units have branched chains via α-[1,6] bonds. Furthermore, the amylose of this embodiment may include a mixture of amylose and amylopectin. Such amylose may have some of the hydroxyl groups substituted as raw materials, and can be obtained by hydrolyzing starch obtained from plants by conventional methods using acid or enzyme treatment to reduce its molecular weight.

[0015] <Xylan> The xylan of this embodiment has a molecular weight (Mw) of 200 to 2000, is a polymer of xylose building blocks, and is linked by β-1,4 glycosidic bonds. Such xylans are derived from natural products and are obtained by extracting hemicellulose, which constitutes plant cell walls, and hydrolyzing it with an acid or enzyme treatment to reduce its molecular weight. Xylans may have branched chains, and some of the hydroxyl groups in the raw material may be substituted. The monosaccharides constituting the xylan of this embodiment may contain small amounts of glucose, mannose, galactose, and arabinose.

[0016] <<Sugar derivatives>> The saccharide derivative of this embodiment is one in which the above saccharide is partially or entirely substituted with a substituent. The substituent of the saccharide derivative preferably includes both the substituents of (Formula 1) and (Formula 2).

[0017] [ka] (Formula 1)

[0018] [ka] (Formula 2)

[0019] In the substituent of the saccharide derivative (Formula 1), the structure of R1 is an aliphatic hydrocarbon chain, which may be linear, branched, saturated, or unsaturated. Examples of linear saturated hydrocarbon chains include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, palmityl, margaryl, stearyl, nonadecyl, arachidyl, heneicosyl, behenyl, tricosyl, and tetracosyl. Examples of branched saturated hydrocarbon chains include, but are not limited to, isopropyl, sec-butyl, isobutyl, tert-butyl, neopentyl, isopentyl, sec-pentyl, 3-pentyl, tert-pentyl, isohexyl, isoheptyl, isooctyl, isononyl, isodecyl, isoundecyl, isolauryl, isolidecyl, isomyristoyl, isopentadecyl, isopalmitoyl, isomargaryl, isostearyl, isononadecyl, isoarachidyl, isoheneicosyl, isobehenyl, isotricosyl, and isotetracosyl.

[0020] Examples of unsaturated hydrocarbon chains include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icosenyl, henicosenyl, docosenyl, tricosenyl, and tetracosenyl, which have double bonds. Examples of such groups include, but are not limited to, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, pentadecynyl, hexadecynyl, heptadecynyl, octadecynyl, nonadecynyl, icosinyl, henicosinyl, docosinyl, tricosinyl, tetracosinyl, and the like.

[0021] The main raw materials for these hydrocarbon chains may be those directly isolated from natural products, those semi-synthesized using isolated products as starting materials, or synthetic products. From the viewpoint of reducing environmental impact, those derived from natural products are preferred over synthetic products, and palmityl and stearyl, which are easily obtained as vegetable fatty acids, are more preferred.

[0022] In the substituent of the saccharide derivative (Formula 2), R2 may have a structure having an aromatic ring. Examples of the structure having an aromatic ring include phenyl, benzyl, tolyl, xylyl, mesityl, as-pseudocumyl, v-pseudocumyl, s-pseudocumyl, duryl, methoxyphenyl, hydroxyphenyl, acetylphenyl, and cinnamyl. Further examples of the structure having an aromatic ring include, but are not limited to, those having the aromatic ring structure of polycyclic aromatic compounds such as naphthalene and anthracene, heteroaromatic compounds such as furan and pyrrole, and non-benzene-based aromatic compounds such as azulene.

[0023] These aromatic ring-containing structures may be used alone or in combination of two or more. Furthermore, the main raw material for these aromatic rings may be directly isolated from natural products, semi-synthesized from isolated products as starting materials, or synthetic products. From the viewpoint of reducing environmental impact, natural products are preferred over synthetic products, and phenyl, benzyl, or tolyl, which are easily available from plants, are preferred, with phenyl being more preferred.

[0024] Furthermore, in the substituent (formula 2) of the saccharide derivative, R2 may not be an aromatic compound but may be an aliphatic hydrocarbon chain different from the substituent R1 in (formula 1). For example, when the substituent R1 in (formula 1) is a linear aliphatic hydrocarbon chain, the substituent R2 in (formula 2) may be a branched aliphatic hydrocarbon chain. Also, when the substituent R1 in (formula 1) is an unsaturated aliphatic hydrocarbon chain, the substituent R2 in (formula 2) may be a saturated aliphatic hydrocarbon chain. Furthermore, when the substituent R1 in (formula 1) is an unsaturated aliphatic hydrocarbon chain, the substituent R2 in (formula 2) may be a saturated aliphatic hydrocarbon chain. Also, when the substituent R1 in (formula 1) is an aliphatic hydrocarbon chain having 10 carbon atoms, the substituent R2 in (formula 2) may be an aliphatic hydrocarbon chain having 18 carbon atoms. Two or more types of substituent R2 in (formula 2) may be used in combination, as long as they are aliphatic hydrocarbon chains different from the substituent R1 in (formula 1).

[0025] Furthermore, when the substituent R1 in (Formula 1) is a branched aliphatic hydrocarbon chain, the saccharide derivative does not need to have the substituent (Formula 2). In other words, the saccharide derivative may be a single branched aliphatic hydrocarbon chain. When the substituent R1 in (Formula 1) is a branched aliphatic hydrocarbon chain, the saccharide derivative can be used as an adhesive material without crystallizing, even if the degree of substitution (DS) is at its maximum.

[0026] If a saccharide derivative crystallizes, it loses its thermoplasticity and is unable to function as a hot-melt adhesive. Therefore, the saccharide derivative of this embodiment is less likely to crystallize because the substituent R1 in (Formula 1) is different from the substituent R2 in (Formula 2), and thus has effective functionality as a material for a hot-melt adhesive. Furthermore, if the saccharide derivative has a branched aliphatic hydrocarbon chain, it is bulkier than a linear aliphatic hydrocarbon chain, and if the saccharide derivative has an aliphatic hydrocarbon chain with an unsaturated bond, it is less likely to crystallize even if the substituent R1 in (Formula 1) is alone, due to the bending of the hydrocarbon chain at the unsaturated bond, and thus has effective functionality as a material for a hot-melt adhesive.

[0027] In particular, derivatizing sugars with both aliphatic and aromatic substituents is thought to inhibit intermolecular interactions between aliphatic hydrocarbon chains, intermolecular interactions between structures with aromatic rings, and π-π stacking, thereby weakening the intramolecular and intermolecular interactions of the sugar derivatives. As a result, sugar derivatives are thought to be less likely to crystallize. Furthermore, sugar derivatives with branched aliphatic hydrocarbon chains are thought to be more difficult to crystallize because the contact area between molecular chains is smaller and the intermolecular interactions are weaker than those with linear aliphatic hydrocarbon chains. In the case of sugar derivatives with aliphatic hydrocarbon chains with unsaturated bonds, it is thought that crystallization is inhibited by bending of the hydrocarbon chain at the unsaturated bond.

[0028] Although some unsubstituted hydroxyl groups derived from the sugars may remain, fully substituted sugars reduce hydrophilicity and improve yields during simple purification using water. Furthermore, fully substituted sugars eliminate hydrogen bonds between the hydroxyl groups derived from the sugars, lowering the melting temperature and allowing bonding at lower temperatures. The term "fully substituted sugars" refers to sugars in which 95% or more of the hydrogen atoms in the hydroxyl groups have been substituted, with 99% or more being preferred and 100% being more preferred. Furthermore, if more than 30% of the hydroxyl groups in the sugars remain unsubstituted, the sugar derivative itself will become crystalline, increasing the likelihood that the adhesive will become hard and brittle.

[0029] The hydroxyl groups of the saccharide derivatives may be used as reaction sites with a crosslinking agent to crosslink the saccharide derivatives together. Crosslinking the saccharide derivatives can increase the cohesive strength of the adhesive. The crosslinking agent is not particularly limited as long as it can react with the saccharide-modified derivative at room temperature or under heat to form a crosslinked structure. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents, with isocyanate-based crosslinking agents being particularly preferred.

[0030] Examples of the isocyanate crosslinking agent include isocyanate monomers such as xylylene diisocyanate, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate; polyfunctional isocyanate compounds containing two or more isocyanate groups in the molecule, which are obtained by addition reaction of these with dihydric or higher alcohols such as trimethylolpropane; and isocyanurates and derivatives thereof.

[0031] Blocked isocyanate compounds in which the isocyanate groups are masked with a blocking agent can also be used. Hot melt adhesives, in particular, are required to maintain an uncrosslinked state before use and crosslink after melting and bonding, so the use of blocked isocyanate compounds is preferred. By using a blocked isocyanate, the isocyanate groups of the blocked isocyanate are masked with the blocking agent before heating and melting, so they do not react with the hydroxyl groups of the sugar derivative and do not crosslink, making it possible to melt the sugar derivative. After heating and melting, the blocking agent dissociates from the isocyanate groups, exposing the isocyanate groups. After bonding, the isocyanate groups of the blocked isocyanate react with the hydroxyl groups of the sugar derivative, allowing the sugar derivative to crosslink.

[0032] When all hydrogen atoms of hydroxyl groups contained in the saccharide are substituted, the aliphatic substitution ratio, which is the ratio of the substituent of (Formula 1) to all the substituents, is preferably 10% or more and 90% or less. However, when the substituent R1 of (Formula 1) is a branched aliphatic hydrocarbon chain or an unsaturated aliphatic hydrocarbon chain, the ratio of the substituents may be 100%, that is, the saccharide derivative may be a saccharide derivative of one type of branched aliphatic hydrocarbon chain or a saccharide derivative of one type of unsaturated aliphatic hydrocarbon chain.

[0033] The bond type of the substituent of the saccharide derivative of this embodiment may be an ester bond (when the substituent (Formula 1) (Formula 2) has a C=O bond in ()) or an ether bond (when the substituent (Formula 1) (Formula 2) does not have a C=O bond in ()). Furthermore, the substituent of the saccharide derivative may have a single bond type of only an ether bond or only an ester bond, or a mixture of both. From the viewpoint of ease of synthesis, an ester bond is preferred.

[0034] <Method for producing sugar derivatives> The method for producing a saccharide derivative involves reacting both the substituents of (Formula 1) and (Formula 2) with a saccharide selected from at least one saccharide selected from amylose having a molecular weight (Mw) of 20,000 or less and xylan having a molecular weight (Mw) of 2,000 or less, or reacting the saccharide with one type of branched aliphatic hydrocarbon chain of (Formula 1).

[0035] The method for producing a saccharide derivative by reacting a saccharide with both the substituents of (Formula 1) and (Formula 2) is as follows: (a) a dissolving step of dissolving saccharides in a good solvent; (b) a first reaction step in which some hydroxyl groups of the saccharide are esterified or etherified; (c) a second reaction step in which the remaining hydroxyl groups of the saccharide after the first reaction step are esterified or etherified; (d) a purification step of purifying the reaction product from the reaction solution after the second reaction step.

[0036] By going through steps (b) and (c), the saccharide is reacted with both the substituents of (Formula 1) and (Formula 2). Thus, the substituent of (Formula 1) is substituted in step (b), followed by the substituent of (Formula 2) in step (c), or the substituent of (Formula 2) is substituted in step (b), followed by the substituent of (Formula 1) in step (c).

[0037] A method for producing a saccharide derivative by reacting a saccharide with a substituent of formula (1) is as follows: (a) a dissolving step of dissolving saccharides in a good solvent; (b) a first reaction step in which some hydroxyl groups of the saccharide are esterified or etherified; (d) a purification step of purifying the reaction product from the reaction solution after the first reaction step.

[0038] These steps allow the reaction to proceed homogeneously and in a very simple manner by sequentially adding the reactants, thereby obtaining the desired saccharide derivative. The saccharide may be either amylose or xylan alone, or a mixture of two or more saccharides.

[0039] The good solvent in step (a) is a solvent that can almost completely dissolve the raw material saccharide, and examples of such good solvents include, but are not limited to, water, pyridine, DMF, DMSO, and mixtures thereof. Methods for dissolving the raw material saccharide in a solvent include stirring, shaking, ultrasonic waves, heating, etc.

[0040] When the reactions in steps (b) and (c) are esterification, acid chlorides are preferred for the hydroxyl groups of the sugars. As the esterification method, the Schotten-Baumann reaction or a reaction in pyridine is preferred. When the reactions in steps (b) and (c) are etherification, alkyl chlorides are preferred for the hydroxyl groups of the sugars. As the etherification method, Williamson ether synthesis is preferred.

[0041] The purification step of step (d) is carried out by combining, for example, separation purification using two liquids, removal of the solvent by evaporation to dryness under reduced pressure, recrystallization using a saturated solvent, reprecipitation using a poor solvent, etc., but is not limited to these.

[0042] <<Tackifying resin>> The tackifying resin used in the adhesive composition of this embodiment provides fluidity to the hot melt adhesive composition during melt application and also provides adhesive strength to the adherend. Examples of tackifying resins include rosin, rosin-based resins, terpene-based resins, petroleum resins, and coumarone-indene resins, and have a softening point of 80°C or higher. These resins can be used alone or in combination. Because the saccharide derivative is a biomass-based material, the tackifying resin is also preferably a biomass-based material to reduce environmental impact. For this reason, rosin, rosin-based resins, or terpene-based resins are preferred, and one or more of these may be used in combination. A combination of multiple rosin-based resins or multiple terpene-based resins may also be used. Furthermore, the softening point of the tackifying resin is preferably 110°C or lower from the standpoint of compatibility with the saccharide derivative. A softening point above 110°C reduces compatibility with the saccharide derivative, resulting in reduced adhesion to low-polarity adherends such as PP.

[0043] Examples of rosin-based resins with a softening point of 80°C or higher and 110°C or lower include Super Ester A100 (100°C), Pine Crystal KE-359 (100°C), and Ester Gum HP (80°C) manufactured by Arakawa Chemical Industries, Ltd.; and Haritack FK100 (96-102°C), Haritack F85 (80-9°C), Haritack PH (93-101°C), Haritack FG-90 (85-95°C), and Harie Star DS-110S (110°C) manufactured by Harima Chemical Industries, Ltd. The temperature in parentheses is the softening point temperature.

[0044] Examples of terpene resins with a softening point of 80°C or higher and 110°C or lower include Yasuhara Chemical's YS Polystar T100 (100°C), YS Polystar T800 (80°C), YS Resin TO105 (105°C), YS Resin TO85 (85°C), YS Resin PX1000 (100°C), and YS Resin PX800 (80°C). The temperatures in parentheses are softening temperatures.

[0045] The content of the tackifier resin is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, per 100 parts by mass of the saccharide derivative. If the content of the tackifier resin exceeds 50 parts by mass, the adhesive layer becomes brittle, cracks tend to occur, and the adhesive strength decreases. If the content is less than 5 parts by mass, the adhesiveness to low-polarity adherends such as PP decreases.

[0046] The hot melt adhesive composition of this embodiment can be used by adding a saccharide derivative and a tackifying resin and molding them into a linear or pellet shape using a melt-stirring mixing vessel or extruder, or by kneading them using a kneader or the like and molding them into a sheet or the like. [Example]

[0047] The present invention will be specifically explained below with reference to several examples and comparative examples, but the present invention is not limited to these.

[0048] <Sugar derivative 1> 60 g of amylose (95% α-glucose, Mw approximately 10,000) was dissolved in 600 mL of pyridine with stirring. After the amylose was completely dissolved in the pyridine, the solution was cooled in an ice bath and 35 g of benzoyl chloride was added dropwise with stirring. 229 g of palmitoyl chloride was then added dropwise. After the addition was complete, the reaction solution was removed from the ice bath and stirred for a total of 12 hours. The reaction solution was then added to 2 L of water and stirred, and the water was filtered off. The precipitate was dissolved in 300 mL of ethyl acetate and gradually poured into 3 L of methanol with stirring. The final precipitate was filtered and dried to obtain 283 g of corn extract-derived amylose palmitate benzoate powder. The substitution ratio of the saccharide derivative (A1) synthesized in Example 1 was 80% aliphatic hydrocarbon chains and 20% aromatic ring-containing structures. It was also confirmed to be thermally meltable at 180 °C. The thermal melting at 180°C was confirmed under the following conditions.

[0049] [180℃ melting point] The obtained saccharide derivative was put into a melt flow reactor set at a temperature of 180°C, and after 180 seconds, a load of 21.2 N was applied and the discharge of molten resin from the discharge outlet was visually confirmed. 〇: Emission was confirmed ×: Emission was not confirmed

[0050] <Sugar derivatives 2-4, comparative sugar 1, comparative sugar derivative 2> Saccharide derivative 2 (A2: 50% aliphatic hydrocarbon chains, 50% structures with aromatic rings), Saccharide derivative 3 (A3: 45% aliphatic hydrocarbon chains, 50% structures with aromatic rings), and Saccharide derivative 4 (A4: 20% aliphatic hydrocarbon chains, 80% structures with aromatic rings) were prepared in the same manner as Saccharide derivative 1, except that the ratios of palmitoyl chloride and benzoyl chloride were changed to the specified proportions to obtain the saccharide derivatives with the substitution ratios shown in Table 1. Comparative saccharide derivative 1 is an example with no substitution (cA1: 100% unsubstituted), and comparative saccharide derivative 2 is an amylose with a molecular weight (Mw) of 1000 before substitution, prepared in the same manner as Saccharide derivative 1 (cA2: 70% aliphatic hydrocarbon chains, 25% structures with aromatic rings).

[0051] [Table 1] These saccharide derivatives, comparative saccharides, or comparative saccharide derivatives and a tackifier resin were kneaded together to produce the hot-melt adhesive compositions of Examples 1 to 10 and Comparative Examples 1 to 2, which will be described below. In addition, Comparative Example 3, which was to be compared with the examples, contained only the saccharide derivative and no tackifier resin. The hot melt adhesive compositions of Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated as follows.

[0052] <<Evaluation method>> The adhesive performance of the hot melt adhesive compositions of these Examples and Comparative Examples was evaluated using three evaluation methods: maximum stress at SUS, maximum stress at PP, and holding strength at SUS at 40°C. The specific evaluation methods for maximum stress at SUS, maximum stress at PP, and holding strength at SUS at 40°C are as follows.

[0053] <Maximum stress against SUS> Preparation of test specimens Two SUS (stainless steel) plates measuring 100 mm in length, 25 mm in width, and 1 mm in thickness were prepared, and the molten adhesive compositions obtained in the Examples and Comparative Examples were applied to a test piece to a thickness of 0.2 mm, so that the edges of the SUS plates overlapped each other by an adhesive area of ​​25 mm x 12.5 mm. The layer of adhesive composition was then sandwiched between the SUS plates and superimposed, and this layer, with the adhesive composition thickness at 0.2 mm, was left in a 23°C environment for 60 minutes to obtain a SUS maximum point stress test piece.

[0054] Measurement of maximum point stress The prepared test pieces were pulled in opposite directions against one SUS plate at a pulling rate of 1 mm / min in a tensile tester at 23°C, and the maximum stress (MPa) was measured. A higher maximum stress against SUS is preferred for an adhesive composition, and for example, a value of 0.6 MPa or more is preferred for a hot-melt adhesive composition.

[0055] <Maximum stress against PP> Instead of the SUS plates, two PP (polypropylene) plates measuring 100 mm in length, 25 mm in width, and 2 mm in thickness were prepared. Other than that, test pieces for the maximum stress against PP were obtained in the same manner as for the SUS plates. The maximum stress against PP was measured in the same manner as for the maximum stress against the SUS plates. A higher maximum stress against PP is preferable for an adhesive composition; for example, a value of 0.5 MPa or higher is preferable for a hot-melt adhesive composition.

[0056] <Holding strength against SUS40℃> Sheet production The molten adhesive compositions obtained in the Examples and Comparative Examples were sandwiched between a 100 μm thick PET film and a 100 μm thick release-treated PET film, and then heat-pressed at 200°C for 1 hour at 1 MPa to form a 30 μm thick adhesive layer. In this way, adhesive sheets were produced.

[0057] Holding force measurement The prepared adhesive sheet was cut to a size of 25mm x 100mm, and the release-treated PET film was peeled off. A SUS plate was attached to the exposed adhesive layer to create a test specimen. The SUS plate had an area of ​​25mm x 25mm. The SUS plate and 100μm-thick PET film were pressed to the SUS plate by rolling it back and forth three times with a 2kg roller. If the adhesive layer was too hard to adhere, the adhesive sheet was heated with a hot dryer or similar device to soften the adhesive before application. The test specimen was left in a dry environment at 40°C for 20 minutes, and then a 1kg load was applied to the end of the test specimen not attached to the SUS plate in the same environment. In other words, the load was applied in the shear direction of the test specimen. The amount of adhesive sheet slippage or the time until the adhesive sheet fell off was measured one hour after the start of load application in the shear direction of the test specimen. The holding strength was better when the adhesive sheet did not fall off, and the smaller the measured value of adhesive sheet slippage, the better. For example, in the case of a hot melt adhesive composition, if the amount of slippage of the adhesive sheet is 0.2 mm or less, it can be determined that the holding power is high.

[0058] Example 1 100 parts by mass of the saccharide derivative (A1) and 20 parts by mass of the tackifier resin PX-1000 were dry-blended in a metal container. The metal container was placed on a hot plate at 180°C and stirred with a metal spatula for 2-3 minutes, whereupon the saccharide derivative (A1) and the tackifier resin PX-1000 were completely melted and kneaded together, yielding a molten adhesive composition.

[0059] <Examples 2-11, Comparative Examples 1-3> Adhesive compositions were obtained in the same manner as in Example 1, using combinations of saccharide derivatives (A) and tackifier resins (B) and their blending amounts (parts by mass) as shown in Tables 2, 3, and 4. The symbols for the tackifier resins (B) are the trade names shown below. PX-1000: Terpene resin (softening point 100°C: YS Resin PX1000; manufactured by Yasuhara Chemical) SEA-100: Rosin resin (softening point 100°C: Super Ester A100; manufactured by Arakawa Chemical Industries) Estergum HP: Rosin-based resin (softening point 80°C: Estergum HP; manufactured by Arakawa Chemical Industries, Ltd.) DS-110S: Rosin resin (softening point 110°C: Harie Star DS-110S; manufactured by Harima Chemicals) SEA-125: Rosin resin (softening point 125°C: Superester A125; manufactured by Arakawa Chemical Industries) In Table 4, "nd" indicates that the composition could not be used as a hot-melt adhesive composition and therefore could not be measured.

[0060] In Example 5, only 5 parts by mass of blocked isocyanate was used. The substitution of the saccharide derivative A3 used in Example 5 was 45% aliphatic hydrocarbon chain, 50% aromatic ring structure, and 5% unsubstituted OH. The closer the ratio of aliphatic hydrocarbon chain to aromatic ring structure is to 5:5, the easier the resin flows, so a crosslinking reaction occurs with the unsubstituted OH by the blocked isocyanate, strengthening the holding power. However, not all of the unsubstituted OH by the blocked isocyanate is converted into a crosslinked polymer through the crosslinking reaction. Bronate (registered trademark) 1902 (manufactured by Bronate) was used as the blocked isocyanate.

[0061] [Table 2]

[0062] [Table 3]

[0063] [Table 4]

[0064] <Evaluation of Adhesive Composition> A hot melt adhesive composition preferably satisfies three conditions: a maximum stress against SUS of 0.6 MPa or more, a maximum stress against PP of 0.4 MPa or more, and a holding power that prevents the PET film from falling.

[0065] Examples 1 to 3 are adhesive compositions obtained by kneading a saccharide derivative (A1) with a terpene-based tackifying resin (B). Comparative Example 3 uses only the saccharide derivative (A1) and no tackifying resin. Compared to Comparative Example 3, Examples 1 to 3 have higher maximum stress against PP, which indicates their effectiveness as hot-melt adhesive compositions. Comparative Example 3 does not satisfy the maximum stress against PP standard, making it unsuitable as an adhesive composition. Furthermore, it can be seen that all adhesive compositions are effective when the amount of tackifying resin (B) is in the range of 5 to 50 parts by mass, preferably 10 to 40 parts by mass.

[0066] Examples 4 to 6 are adhesive compositions prepared by kneading 20 parts by mass of a terpene-based tackifier resin (B) with a saccharide derivative (A2), (A3), or (A4). Examples 4 to 6 differ from Example 1 only in the saccharide derivative. Compared to Example 1, Examples 4 to 6 have lower maximum stress against SUS, maximum stress against PP, and holding power. However, all of these compositions meet the standards for hot-melt adhesive compositions and are therefore effective. Furthermore, considering that the saccharide derivative (A1) in Example 1 has 80% aliphatic hydrocarbon chains and 20% aromatic ring structures as substituents, and the saccharide derivative (A4) in Example 6 has 20% aliphatic hydrocarbon chains and 80% aromatic ring structures as substituents, it is clear that a higher substitution ratio of aliphatic hydrocarbon chains is preferable for the terpene-based tackifier resin (B).

[0067] Examples 7 to 11 are adhesive compositions prepared by kneading a saccharide derivative (A1) with a rosin-based tackifying resin (B). While Example 1 used a terpene-based tackifying resin, Examples 7 to 11 use a rosin-based tackifying resin. Compared to Example 1, Examples 7 to 10 were evaluated as having approximately the same maximum stress against SUS, maximum stress against PP, and holding power. Example 11 was also evaluated as having approximately the same maximum stress against SUS and holding power, demonstrating its effectiveness as a hot-melt adhesive composition. Example 10 is an adhesive composition containing two rosin-based tackifying resins (B), 10 parts by mass of Ester Gum HP and 10 parts by mass of DS-110S. It can be seen that Example 10 exhibits improved maximum stress against PP compared to the adhesive compositions of Example 8 (20 parts by mass of Ester Gum HP), Example 9 (20 parts by mass of DS-110S), and Example 11 (20 parts by mass of SEA-125).

[0068] Comparative Example 1 was prepared by kneading comparative saccharide cA1 (100% unsubstituted amylose (weight average molecular weight (Mw) 10,000)) with terpene-based tackifying resin (B). In fact, Comparative Example 1 could not be thermally melted at 180°C (no thermoplasticity was exhibited), and was therefore unusable as a hot-melt adhesive. Comparative Example 2 is an adhesive composition obtained by kneading a comparative saccharide derivative cA2 (molecular weight (Mw) of 1000, 70% aliphatic hydrocarbon chains, and 25% structures with aromatic rings) with a terpene-based tackifying resin (B). Because the molecular weight of the comparative saccharide derivative in Comparative Example 2 was small, the fluidity was too high, and the maximum point stress against SUS, the maximum point stress against PP, and the holding power did not meet the standards, making it unusable as a hot-melt adhesive.

Claims

1. The present invention comprises a saccharide derivative in which at least some of the hydrogen atoms of hydroxyl groups contained in a saccharide having an α-glucose structural unit and a weight average molecular weight (Mw) of 5,000 or more and 20,000 or less, or a saccharide having a xylose structural unit and a weight average molecular weight (Mw) of 200 or more and 2,000 or less, are substituted with a substituent, and a tackifier resin having a softening point of 80°C or more, The substituent of the saccharide derivative includes the following structures (Formula 1) and (Formula 2): The adhesive composition wherein the tackifier resin is a terpene resin and / or a rosin resin. 【Chemistry 1】 (Formula 1) 【Chemistry 2】 (Formula 2) In formula 1, R1 is a linear, branched, saturated, or unsaturated aliphatic hydrocarbon group; In formula 2, R2 is an aromatic hydrocarbon group or an aliphatic hydrocarbon group different from R1, The C═O bond in the parentheses in (Formula 1) and (Formula 2) may not be included.

2. The adhesive composition according to claim 1, wherein 10-90% of the hydrogen atoms of the hydroxyl groups contained in the saccharide are substituted with the substituent of (Formula 1) and 90-10% of the hydrogen atoms of the hydroxyl groups are substituted with the substituent of (Formula 2).

3. The present invention comprises a saccharide derivative in which at least some of the hydrogen atoms of hydroxyl groups contained in a saccharide having an α-glucose structural unit and a weight average molecular weight (Mw) of 5,000 or more and 20,000 or less, or a saccharide having a xylose structural unit and a weight average molecular weight (Mw) of 200 or more and 2,000 or less, are substituted with a substituent, and a tackifier resin having a softening point of 80°C or more, The substituent of the saccharide derivative has a structure of the following formula 1: The adhesive composition wherein the tackifier resin is a terpene resin and / or a rosin resin. 【Transformation 3】 (Formula 1) In formula 1, R1 is an aliphatic hydrocarbon group having a branched chain or an unsaturated bond, and the C=O bond in the parentheses in formula 1 may not be contained.

4. 4. The adhesive composition according to claim 1, wherein the saccharide having an α-glucose structural unit is amylose.

5. The adhesive composition according to claim 1 , wherein the tackifier resin is contained in an amount of 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the saccharide derivative.

6. The adhesive composition according to any one of claims 1 to 3, wherein the tackifier resin has a softening point of 80°C or higher and 110°C or lower.

Images