Urethane-based adhesive composition, vulcanized rubber bonding method, conveyor belt

Abstract

An object of the present invention is to provide an adhesive composition having excellent adhesiveness to a vulcanized rubber containing a high proportion of BR, a method for bonding vulcanized rubbers using the above adhesive composition, and a conveyor belt. The solution is a urethane-based adhesive composition containing a polyol component and a polyisocyanate component. The polyol component includes the following polyol 1 and polyol 2, and the above urethane-based adhesive composition is used for bonding vulcanized rubbers. Polyol 1: A polyol compound having a glass transition temperature of -30 to +60°C, a hydroxyl value of 1 to 20 KOH mg / g, and having an ester bond. Polyol 2: A polyol compound having a hydroxyl value exceeding 20 KOH mg / g and 500 KOH mg / g or less, and having a skeleton containing at least one selected from polymers of isoprene and / or butadiene, their hydrides, polyolefins, ester bonds, and carbonate bonds.

Description

Technical Field

[0001] The present invention relates to a urethane-based adhesive composition, a method for bonding vulcanized rubber, and a conveyor belt. Background Art

[0002] Conventionally, for example, in order to endlessize a belt such as a conveyor belt (for example, elongate it and / or form it into a loop), rubber is connected to rubber by joining vulcanized rubber or unvulcanized rubber. In the above joining method, generally, vulcanization joining in which unvulcanized rubbers are vulcanized to join them to each other, and natural vulcanization bonding in which vulcanized rubbers are bonded to each other with an adhesive are used.

[0003] For vulcanization joining, equipment for vulcanizing unvulcanized rubbers to each other is required. Especially in the case of endlessizing a large-sized product such as a conveyor belt, it is necessary to make the above equipment large-sized.

[0004] On the other hand, natural vulcanization bonding has the advantage of not requiring such large-sized equipment. As adhesives that can be used for natural vulcanization bonding (the above adhesives are also referred to as natural vulcanization adhesives), for example, Patent Documents 1 and 2 are known.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 6733436

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2021-031562 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] Among them, the present inventors prepared an adhesive with reference to Patent Document 1 and evaluated it. As a result, it was clarified that an adhesive containing chloroprene rubber and polyisocyanate sometimes has low adhesiveness to vulcanized rubber of a rubber composition containing butadiene rubber (BR) in an amount of, for example, more than 30% by mass in the rubber component (Comparative Example 6).

[0011] In addition, an adhesive composition was prepared with reference to Patent Document 2 and evaluated. As a result, it was clarified that an adhesive composition containing a polyisocyanate compound and a polyester sometimes also has low adhesiveness to vulcanized rubber containing butadiene rubber (BR) in an amount of more than 30% by mass in the rubber component (Comparative Examples 3 to 5 and 8).

[0012] Therefore, an object of the present invention is to provide an adhesive composition having excellent adhesiveness to vulcanized rubber containing a high proportion of BR. Further, it is also an object to provide a method for bonding vulcanized rubber using the above adhesive composition and a conveyor belt manufactured using the above adhesive composition.

[0013] Method for solving the problem

[0014] The present inventors conducted in-depth research to solve the above problems and found that by containing a polyol component and a polyisocyanate component, and the polyol component includes polyol 1 and polyol 2 having a hydroxyl value within a specific range, etc., the desired effects can be obtained, thus completing the present invention.

[0015] Based on the above understanding, etc., the present invention specifically solves the above problems through the following constitution. [1]

[0017] A urethane-based adhesive composition containing a polyol component and a polyisocyanate component, the above polyol component includes the following polyol 1 and polyol 2, and the above urethane-based adhesive composition is used for bonding vulcanized rubber.

[0018] Polyol 1: A polyol compound having a glass transition temperature of -30 to +60 °C, a hydroxyl value of 1 to 20 KOHmg / g, and having an ester bond

[0019] Polyol 2: A polyol compound having a hydroxyl value exceeding 20 KOHmg / g and being 500 KOHmg / g or less, and the skeleton having at least one selected from polymers of isoprene and / or butadiene, their hydrogenated products, polyolefins, ester bonds, and carbonate bonds [2]

[0021] According to the urethane-based adhesive composition described in [1], in all the hydroxyl groups of the above polyol component, the proportion of the hydroxyl groups of the above polyol 1 is 10 to 30 mol%. [3]

[0023] According to the urethane-based adhesive composition described in [1] or [2], in all the hydroxyl groups of the above polyol component, the proportion of the hydroxyl groups of the above polyol 2 is 40 to 70 mol%. [4]

[0025] According to the urethane-based adhesive composition described in any one of [1] to [3], the above polyol component further includes polyol 3 having a hydroxyl value exceeding 500 KOHmg / g and being 1300 KOHmg / g or less. [5]

[0027] The urethane-based adhesive composition according to [4], wherein the hydroxyl value of the above-mentioned polyol 3 is 1000 to 1300 KOHmg / g. [6]

[0029] The urethane-based adhesive composition according to [4] or [5], wherein, among all the hydroxyl groups of the above-mentioned polyol component, the proportion of the hydroxyl groups of the above-mentioned polyol 3 is 10 to 40 mol%. [7]

[0031] The urethane-based adhesive composition according to any one of [1] to [6], wherein the molar ratio of all the isocyanate groups of the above-mentioned polyisocyanate component to all the hydroxyl groups of the above-mentioned polyol component is 1.0 to 3.0. [8]

[0033] The urethane-based adhesive composition according to any one of [1] to [7], wherein the glass transition temperature of the above-mentioned polyol 1 is 0 to +50 °C. [9]

[0035] The urethane-based adhesive composition according to any one of [1] to [8], wherein the number average molecular weight of the above-mentioned polyol 1 is 6,000 to 23,000.

[10]

[0037] The urethane-based adhesive composition according to any one of [1] to [9], wherein the above-mentioned polyol 2 has at least polyisoprene, polybutadiene, their hydrogenated products, or polycarbonate as a backbone.

[11]

[0039] The urethane-based adhesive composition according to any one of [1] to

[10] , which further contains a solvent, and the above-mentioned solvent contains at least an acetate-based solvent.

[12]

[0041] A method for bonding vulcanized rubber, wherein the vulcanized rubbers are bonded to each other using the urethane-based adhesive composition according to any one of [1] to

[11] .

[13]

[0043] A conveyor belt, wherein the ends of the belt are bonded to each other using the urethane-based adhesive composition according to any one of [1] to

[11] .

[0044] Effects of the Invention

[0045] The urethane-based adhesive composition of the present invention has excellent adhesiveness to vulcanized rubber containing a high proportion of BR. Further, a method for bonding vulcanized rubber using the urethane-based adhesive composition of the present invention and a conveyor belt manufactured using the urethane-based adhesive composition of the present invention can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram showing an example of the bonding form of the conveyor belt of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The present invention will be described in detail below.

[0048] In addition, in this specification, the numerical range indicated by "~" means the range including the numerical values described before and after "~".

[0049] In this specification, unless otherwise specified, each component can use the substances corresponding to the component alone or in combination of two or more. When the component contains two or more substances, the content of the component means the total content of the two or more substances.

[0050] In this specification, the joining of vulcanized rubbers bonded to each other with an adhesive is sometimes simply referred to as "bonding".

[0051] In this specification, the adhesiveness to vulcanized rubber containing a high proportion of BR is sometimes simply referred to as "adhesiveness". In addition, the adhesiveness to vulcanized rubber containing a high proportion of BR being more excellent is sometimes referred to as the effect of the present invention being more excellent.

[0052] [Urethane-based Adhesive Composition]

[0053] The urethane-based adhesive composition of the present invention (the adhesive composition of the present invention) is the following urethane-based adhesive composition:

[0054] It contains a polyol component and a polyisocyanate component. The above polyol component includes the following polyol 1 and polyol 2, and the above urethane-based adhesive composition is used for bonding vulcanized rubber.

[0055] Polyol 1: It is a polyol compound having a glass transition temperature of -30 to +60 °C, a hydroxyl value of 1 to 20 KOHmg / g, and having an ester bond

[0056] Polyol 2: A polyol compound having a hydroxyl value exceeding 20 KOHmg / g and 500 KOHmg / g or less, and having at least one selected from polymers of isoprene and / or butadiene, their hydrides, polyolefins, ester bonds, and carbonate bonds in its skeleton

[0057] It can be considered that the adhesive composition of the present invention can obtain the desired effect due to such a configuration. The reason is not clear, but it is presumably as follows.

[0058] It can be considered that if the adhesive composition of the present invention is applied to a vulcanized rubber containing BR in a high proportion, a polyol 2 having a hydroxyl value exceeding 20 KOH mg / g and not exceeding 500 KOH mg / g moves and / or penetrates to the surface of the vulcanized rubber, and in this state, the polyol component reacts with the polyisocyanate component, so that the cured product (adhesive) produces a crosslinking effect and an anchoring effect, and as a result, a strong adhesion occurs between the vulcanized rubbers.

[0059] Hereinafter, each component contained in the adhesive composition of the present invention will be described in detail.

[0060] [Polyol component]

[0061] The polyol component contained in the adhesive composition of the present invention is a compound having a plurality of hydroxyl groups. The number of hydroxyl groups possessed by the polyol component only needs to be 2 or more on average per 1 molecule, and preferably 2 to 4.

[0062] In the present invention, the polyol component includes polyol 1 and polyol 2. Thereby, the adhesiveness of the adhesive composition of the present invention is excellent.

[0063] [Polyol 1]

[0064] In the present invention, polyol 1 included in the polyol component is a polyol compound having a glass transition temperature of -30 to +60 °C, a hydroxyl value of 1 to 20 KOH mg / g, and an ester bond.

[0065] [Glass transition temperature of polyol 1]

[0066] In the present invention, the glass transition temperature (Tg) of polyol 1 is -30 to +60 °C (not less than -30 °C and not more than +60 °C). By setting the Tg of polyol 1 within the above range, the adhesiveness of the adhesive composition of the present invention is excellent.

[0067] From the viewpoints of more excellent effects of the present invention and excellent expression of initial strength, the Tg of polyol 1 is preferably 0 to +60 °C, more preferably +10 to +50 °C, and further preferably +15 to +50 °C.

[0068] From the viewpoints of more excellent effects of the present invention and large initial strength, the Tg of polyol 1 is preferably 0 to +60 °C, more preferably +10 to +50 °C, and further preferably +15 to +40 °C.

[0069] In the present invention, the glass transition temperature of each polyol component can be measured by a differential scanning calorimeter. For example, the above measurement can be carried out at a heating rate of 20 °C / min, and the glass transition temperature can be calculated by the midpoint method from the results.

[0070] [Hydroxyl value of polyol 1]

[0071] In the present invention, the hydroxyl value (OH value) of polyol 1 is 1 to 20 KOHmg / g. By the OH value of polyol 1 being in the above range, the adhesiveness of the adhesive composition of the present invention is excellent.

[0072] From the viewpoints of more excellent effects of the present invention and excellent performance of initial strength, the OH value of polyol 1 is preferably 5 to 20 KOHmg / g, and more preferably 10 to 20 KOHmg / g.

[0073] In the present invention, the hydroxyl value of each polyol component can be measured in accordance with JIS K1557-1:2007.

[0074] (Ratio of hydroxyl groups possessed by polyol 1)

[0075] From the viewpoints of more excellent effects of the present invention and excellent performance of initial strength, the ratio of the hydroxyl groups possessed by polyol 1 among all the hydroxyl groups possessed by the polyol components is preferably 10 to 30 mol%, and more preferably 10.0 to 20.0 mol%.

[0076] The above range of the ratio can also be the same when the polyol component further contains polyol 3 described later.

[0077] (Acid value of polyol 1)

[0078] From the viewpoints of more excellent effects of the present invention and excellent performance of initial strength, the acid value of polyol 1 is preferably 1 to 20 KOHmg / g, and more preferably 2 to 10 KOHmg / g.

[0079] In the present invention, the acid value of each polyol component can be measured in accordance with JIS K0070:1992.

[0080] [Ester bond of polyol 1]

[0081] In the present invention, polyol 1 has an ester bond in addition to a plurality of hydroxyl groups. By polyol 1 having an ester bond, the adhesiveness of the adhesive composition of the present invention is excellent.

[0082] From the viewpoints of more excellent effects of the present invention and excellent performance of initial strength, polyol 1 preferably has an ester bond in the skeleton of polyol 1, and more preferably the above skeleton has a polyester.

[0083] (Examples of polyol 1)

[0084] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, polyol 1 preferably contains a polyester polyol (a compound having a polyester polymer backbone and multiple hydroxyl groups).

[0085] (Number-average molecular weight of polyol 1)

[0086] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the number-average molecular weight of polyol 1 is preferably 6,000 to 23,000.

[0087] In the present invention, when each polyol component is a polymer (for example, a polyester polyol as polyol 1), the number-average molecular weight of each polyol component can be a polystyrene conversion value obtained by gel permeation chromatography using tetrahydrofuran as a solvent.

[0088] [Polyol 2]

[0089] In the present invention, polyol 2 contained in the polyol component is a polyol compound having a hydroxyl value exceeding 20 KOH mg / g and being 500 KOH mg / g or less, and a backbone having at least one selected from polymers of isoprene and / or butadiene, their hydrogenated products, polyolefins, ester bonds, and carbonate bonds.

[0090] [Hydroxyl value of polyol 2]

[0091] In the present invention, the hydroxyl value (OH value) of polyol 2 exceeds 20 KOH mg / g and is 500 KOH mg / g or less. By the OH value of polyol 2 being in the above range, the adhesiveness of the adhesive composition of the present invention is excellent.

[0092] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the OH value of polyol 2 is preferably 21 to 400 KOH mg / g, more preferably 30 to 300 KOH mg / g, and further preferably 45 to 225 KOH mg / g.

[0093] When polyol 2 contains a polyol having a polyester backbone (polyester polyol), from the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the OH value of the polyester polyol as polyol 2 is preferably 21 to 200 KOH mg / g, more preferably 21 to 100 KOH mg / g.

[0094] When the polyol 2 contains a polyol having a polybutadiene backbone (polybutadiene polyol), from the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the OH value of the polybutadiene polyol is preferably 30 to 200 KOHmg / g, more preferably 35 to 90 KOHmg / g.

[0095] When the polyol 2 contains a polyol having a polycarbonate backbone (polycarbonate polyol), from the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the OH value of the polycarbonate polyol is preferably 30 to 300 KOHmg / g, more preferably 100 to 225 KOHmg / g.

[0096] (Ratio of hydroxyl groups possessed by polyol 2)

[0097] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, in all the hydroxyl groups possessed by the polyol component, the ratio of the hydroxyl groups possessed by the polyol 2 is preferably 10.0 to 70.0 mol%.

[0098] The above ratio of the hydroxyl groups possessed by the polyol 2 can be the same even when the polyol component further contains the following polyol 3.

[0099] [Backbone of polyol 2]

[0100] In the present invention, in addition to a plurality of hydroxyl groups, the polyol 2 has at least one selected from polymers of isoprene and / or butadiene, their hydrogenated products, polyolefins, ester bonds, and carbonate bonds as a backbone. By having the above structure in the backbone of the polyol 2, the adhesiveness of the adhesive composition of the present invention is excellent.

[0101] When the polyol 2 has an ester bond in the backbone, the backbone of the polyol 2 preferably has a polyester. As the polyol 2 as described above, for example, a polyester polyol (a compound having a polyester polymer backbone and a plurality of hydroxyl groups) can be cited.

[0102] When the polyol 2 has a carbonate bond in the backbone, the above backbone preferably has a polycarbonate. As the polyol 2 as described above, for example, a polycarbonate polyol (a compound having a polycarbonate polymer backbone and a plurality of hydroxyl groups) can be cited.

[0103] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, it is preferred that the polyol 2 has at least polyisoprene, polybutadiene, their hydrogenated products, or polycarbonate as a backbone, and more preferably has at least polybutadiene, its hydrogenated product, or polycarbonate.

[0104] (Viscosity of polyol 2)

[0105] From the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the viscosity of polyol 2 (for example, polybutadiene polyol) at 30 °C is preferably 6.0 Pa·s or less.

[0106] From the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the viscosity of polyol 2 (for example, polyisoprene polyol) at 75 °C is preferably 1000 mPa·s or less.

[0107] (Examples of polyol 2)

[0108] From the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, polyol 2 preferably contains at least one selected from polyisoprene polyol, polybutadiene polyol, their hydrogenated polyols, and polycarbonate polyol, and more preferably contains at least one selected from polybutadiene polyol, its hydrogenated polyol, and polycarbonate polyol.

[0109] (Number-average molecular weight of polyol 2)

[0110] From the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the number-average molecular weight of polyol 2 is preferably 500 to 5,000, and more preferably 500 to 3,000.

[0111] (Polyol 3)

[0112] From the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the above polyol component preferably further contains polyol 3 having a hydroxyl value exceeding 500 KOHmg / g and being 1300 KOHmg / g or less.

[0113] For the same reason as above, the hydroxyl value of polyol 3 is more preferably 1000 to 1300 KOHmg / g.

[0114] (Ratio of hydroxyl groups possessed by polyol 3)

[0115] When the polyol component further contains polyol 3, from the viewpoint that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the ratio of the hydroxyl groups possessed by polyol 3 in all the hydroxyl groups possessed by the polyol component is preferably 10 to 70 mol%, and more preferably 20 to 65 mol%.

[0116] (Ratio of hydroxyl groups possessed by polyols 2 and 3 when the polyol component further contains polyol 3)

[0117] When the polyol component further contains polyol 3 and contains a polycarbonate polyol as polyol 2, from the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, among all the hydroxyl groups possessed by the polyol component, the proportion of the hydroxyl groups possessed by the above polyol 2 (including the polycarbonate polyol) is preferably 10.0 to 50.0 mol%, more preferably 20.0 to 40.0 mol%.

[0118] In addition, in the above case, from the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, among all the hydroxyl groups possessed by the polyol component, the proportion of the hydroxyl groups possessed by polyol 3 is preferably 20.0 to 70.0 mol%, more preferably 40.0 to 65.0 mol%.

[0119] (Structure of polyol 3)

[0120] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, a preferred example of polyol 3 is a low-molecular compound (monomer) having a plurality of hydroxyl groups.

[0121] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, in polyol 3, the plurality of hydroxyl groups are preferably bonded to a hydrocarbon group, and more preferably bonded to a hydrocarbon group formed only by carbon atoms and hydrogen atoms.

[0122] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the number of carbon atoms of the above hydrocarbon group is preferably 2 to 15, more preferably 3 to 5.

[0123] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the above hydrocarbon group is preferably a linear or branched alkyl group.

[0124] Examples of polyol 3 include, for example, butanediol, diethyl-1,5-pentanediol, butylethylpropanediol, and nonanediol.

[0125] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, polyol 3 preferably contains butanediol, and more preferably contains 1,4-butanediol.

[0126] (Molecular weight of polyol 3)

[0127] From the viewpoint that the effects of the present invention are more excellent and the performance of the initial strength is excellent, the molecular weight of polyol 3 is preferably less than 500.

[0128] In addition, in the present invention, when the polyol component is a low molecular weight (monomer), the molecular weight of the polyol component can be measured by a usual method used for measuring the molecular weight of a low molecular compound.

[0129] [Polyisocyanate]

[0130] The adhesive composition of the present invention contains a polyisocyanate component. The polyisocyanate component is a compound having a plurality of isocyanate groups.

[0131] Examples of the polyisocyanate component include aromatic polyisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), and triphenylmethane triisocyanate;

[0132] 1,6-hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate (NBDI), trans-cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis(isocyanatomethyl)cyclohexane (H6XDI), dicyclohexylmethane diisocyanate (H 12 MDI) and other aliphatic polyisocyanates (the above aliphatic includes the concepts of linear, branched, and alicyclic);

[0133] Their carbodiimide-modified polyisocyanates.

[0134] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the polyisocyanate component preferably contains an aromatic polyisocyanate, more preferably contains at least one selected from MDI, polymeric MDI, their carbodiimide-modified products, and triphenylmethane triisocyanate, and further preferably contains polymeric MDI and / or triphenylmethane triisocyanate.

[0135] The so-called polymeric MDI is polymethylene polyphenyl polyisocyanate. Polymeric MDI can be a mixture of polymethylene polyphenyl polyisocyanates with different degrees of polymerization. In addition to polymethylene polyphenyl polyisocyanate, polymeric MDI can further contain MDI. There is no particular limitation on polymeric MDI.

[0136] Examples of triphenylmethane triisocyanate include triphenylmethane-4,4',4''-triisocyanate.

[0137] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the polyisocyanate component is preferably liquid at normal temperature (23 °C).

[0138] Examples of the polyisocyanate component that is liquid at normal temperature include polymeric MDI.

[0139] The polyisocyanate component can be in a state dissolved in a solvent.

[0140] (Combination of polyol component and polyisocyanate component)

[0141] From the viewpoints that the effects of the present invention are more excellent and the expression of the initial strength is excellent, the polyol component and the polyisocyanate component are preferably: a combination 1 of a polyol component containing polyol 1, a polycarbonate polyol as polyol 2, and polyol 3 and a polyisocyanate component containing triphenylmethane triisocyanate,

[0142] A combination 2 of a polyol component containing polyol 1, a polybutadiene polyol or a polyisoprene polyol as polyol 2, and polyol 3 and a polyisocyanate component containing polymeric MDI.

[0143] ·Combination 1

[0144] From the viewpoints that the effects of the present invention are more excellent, the expression of the initial strength, and the magnitude of the initial strength are excellent, in the above combination 1, it is preferable that polyol 1 contains a polyester polyol having a Tg of 0 to +40°C, and / or

[0145] Among all the hydroxyl groups of the polyol component, the proportion of the hydroxyl groups of polyol 2 is 10.0 to 40.0 mol%, and the proportion of the hydroxyl groups of polyol 3 is 20.0 to 70.0 mol%.

[0146] More preferably, polyol 1 contains a polyester polyol having a Tg of 0 to +40°C, among all the hydroxyl groups of the polyol component, the proportion of the hydroxyl groups of polyol 2 is 10.0 to 40.0 mol%, and the proportion of the hydroxyl groups of polyol 3 is 20.0 to 70.0 mol%.

[0147] ·Combination 2

[0148] From the viewpoints that the effects of the present invention are more excellent, the expression of the initial strength, and the magnitude of the initial strength are excellent, in the above combination 2, it is preferable that polyol 1 contains a polyester polyol having a Tg of 0 to +40°C,

[0149] polyol 2 contains a polybutadiene polyol,

[0150] polyol 2 contains a polybutadiene polyol having a hydroxyl value of 30 to 90 KOHmg / g, and / or

[0151] Among all the hydroxyl groups of the polyol component, the proportion of the hydroxyl groups of polyol 2 is 50.0 to 70.0 mol%, and the proportion of the hydroxyl groups of polyol 3 is 20.0 to 40.0 mol%.

[0152] More preferably, the polyol 1 contains a polyester polyol having a Tg of 0 to +40°C.

[0153] The polyol 2 contains a polybutadiene polyol having a hydroxyl value of 30 to 90 KOHmg / g. Among all the hydroxyl groups of the polyol component, the proportion of the hydroxyl groups of the polyol 2 is 50.0 to 70.0 mol%, and the proportion of the hydroxyl groups of the polyol 3 is 20.0 to 40.0 mol%.

[0154] (Molar ratio of NCO / OH)

[0155] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the molar ratio (NCO / OH) of all the isocyanate groups of the polyisocyanate component to all the hydroxyl groups of the polyol component is preferably 0.7 to 5.5, more preferably 1.0 to 3.0, and further preferably 1.5 to 2.5.

[0156] (Solvent)

[0157] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the adhesive composition of the present invention preferably further contains a solvent.

[0158] The solvent is not particularly limited as long as it has solubility or compatibility with the polyol component and has no reactivity. The same applies to the polyisocyanate component.

[0159] As the solvent, organic solvents can be mentioned. Specifically, for example, ester solvents, ketones such as methyl ethyl ketone, and ethers such as tetrahydrofuran can be mentioned.

[0160] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the solvent preferably contains an ester solvent, more preferably contains an acetate solvent, and further preferably contains ethyl acetate.

[0161] (Content of solvent)

[0162] When the adhesive composition of the present invention further contains a solvent, the content of the solvent is preferably 30 to 80% by mass in the total amount of the adhesive composition of the present invention. In the above case, the total amount of the polyol component and the polyisocyanate component can be 20 to 70% by mass in the total amount of the adhesive composition of the present invention.

[0163] When the polyisocyanate component is in a state dissolved in the solvent, the amount of the solvent used together with the polyisocyanate component is included in the above content of the solvent.

[0164] (Other components)

[0165] In addition to the above components, the adhesive composition of the present invention may further contain, as needed, additives such as catalysts, carbon black, white fillers (e.g., silica, calcium carbonate, clay, talc), anti-aging agents, antioxidants, pigments (dyes), plasticizers, softeners, and flame retardants. The types and contents of the above additives can be appropriately selected.

[0166] (Catalyst)

[0167] From the viewpoint of more excellent effects of the present invention and excellent performance of initial strength, the adhesive composition of the present invention preferably further contains a catalyst.

[0168] Examples of the catalyst include carboxylic acids such as 2-ethylhexanoic acid and oleic acid; phosphoric acids such as polyphosphoric acid, ethyl acid phosphate, and butyl acid phosphate; bismuth catalysts such as bismuth octoate; tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate; and amine-based catalysts such as 1,4-diazabicyclo[2.2.2]octane, 2,4,6-tris(dimethylaminomethyl)phenol (e.g., DMP-30), and bis(2-dimethylaminoethyl)ether.

[0169] The catalyst preferably contains a tin-based catalyst and / or an amine-based catalyst, and more preferably contains a tin-based catalyst and an amine-based catalyst.

[0170] The amount of the catalyst can be appropriately selected.

[0171] (Manufacturing method 1 of the adhesive composition)

[0172] The adhesive composition of the present invention can be manufactured, for example, by mixing the above components. In addition, in the case of manufacturing as described above, the adhesive composition of the present invention can be a one-component system.

[0173] (Manufacturing method 2 of the adhesive composition)

[0174] From the viewpoint of excellent storage stability, the adhesive composition of the present invention is preferably at least a two-component system.

[0175] In the case of making the adhesive composition of the present invention a two-component system, it is only necessary to add at least a polyol component to the first liquid and a polyisocyanate component to the second liquid. Other components can be appropriately added to the first liquid and / or the second liquid.

[0176] In the case of the adhesive composition of the present invention being a two-component system, it is only necessary to mix and use the first liquid and the second liquid.

[0177] [Urethane-based adhesive composition]

[0178] Regarding the adhesive composition of the present invention, it can be a polyurethane-based adhesive formed by the reaction of a polyol component and a polyisocyanate component.

[0179] [Bonding vulcanized rubber]

[0180] The adhesive composition of the present invention can be used for bonding vulcanized rubber.

[0181] The above-mentioned vulcanized rubber refers to rubber that has been vulcanized. The adhesive composition of the present invention only requires that at least one of the adherends is vulcanized rubber, and it is possible to cite the case where both adherends are vulcanized rubber as one of the preferred embodiments. When both adherends are vulcanized rubber, the types of the two vulcanized rubbers can be the same or different. When both adherends are vulcanized rubber, from the viewpoints of more excellent effects of the present invention and excellent initial strength performance, the types of the two vulcanized rubbers are preferably the same. In addition, when bonding adherends having layers of multiple different types of vulcanized rubber to each other, for the same reasons as above, it is preferred to bond homogeneous vulcanized rubbers to each other. For example, when bonding adherends having a layer of vulcanized rubber A and a layer of vulcanized rubber B to each other, it is preferred to bond the layers of vulcanized rubber A to each other and / or the layers of vulcanized rubber B to each other.

[0182] Examples of the rubber component contained in the vulcanized rubber include diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), aromatic vinyl compound-conjugated diene copolymer rubber (such as styrene-butadiene rubber), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR).

[0183] In addition to the rubber component, the vulcanized rubber can further contain various additives commonly used in rubber compositions such as fillers such as carbon black or silica, silane coupling agents, zinc oxide, stearic acid, anti-aging agents, processing aids, oils (such as processing oils, aromatic oils), liquid polymers, vulcanizing agents (such as sulfur), and vulcanization accelerators.

[0184] The vulcanized rubber is preferably vulcanized rubber obtained using sulfur. The vulcanization conditions are not particularly limited.

[0185] The adhesive composition of the present invention has excellent adhesiveness to vulcanized rubber containing BR in a high proportion (for example, the content of BR in the rubber component exceeds 30% by mass). In addition, the adhesive composition of the present invention also has excellent adhesiveness to vulcanized rubber containing BR in a low proportion (for example, the content of BR in the rubber component is less than 30% by mass) or vulcanized rubber not containing BR.

[0186] The adhesive composition of the present invention can be cured, for example, under the conditions of 5 to 40 °C and 10 to 80% RH.

[0187] Since the adhesive composition of the present invention enables easy endless processing of rubber articles with each other (particularly, long-shaped substances), it is preferably used, for example, for bonding conveyor belts with each other.

[0188] [Vulcanized rubber bonding method]

[0189] Next, the vulcanized rubber bonding method of the present invention will be described.

[0190] The vulcanized rubber bonding method of the present invention is a vulcanized rubber bonding method in which vulcanized rubbers are bonded to each other using the urethane-based adhesive composition of the present invention.

[0191] The adhesive composition used in the vulcanized rubber bonding method of the present invention is not particularly limited as long as it is the urethane-based adhesive composition of the present invention.

[0192] The vulcanized rubber used in the vulcanized rubber bonding method of the present invention is not particularly limited as long as it is rubber that has been vulcanized. The vulcanized rubber can be the same as the vulcanized rubber described in the above [Bonded vulcanized rubber].

[0193] As described above, since the vulcanized rubber bonding method of the present invention uses an adhesive composition having excellent adhesiveness to vulcanized rubber, it is useful for bonding vulcanized rubber, particularly vulcanized rubber containing BR in a high proportion (for example, more than 30% by mass in the rubber component).

[0194] After vulcanization, the vulcanized rubber can be subjected to physical surface treatment such as buffing or chemical surface treatment such as a surface treatment agent (for example, a primer) as needed.

[0195] From the viewpoint that the effect of the present invention is more excellent because the unevenness of the surface of the vulcanized rubber is increased to facilitate penetration of the adhesive composition, physical surface treatment such as buffing is preferably performed on the vulcanized rubber.

[0196] For example, in the vulcanized rubber bonding method of the present invention, the adhesive composition of the present invention can be applied to the above-mentioned vulcanized rubber, the above-mentioned vulcanized rubber can be bonded to another vulcanized rubber, and it can be cured under the conditions of 15 to 35 °C and 40 to 70% RH to bond the vulcanized rubbers to each other.

[0197] When bonding vulcanized rubbers to each other, the position where the bonding is performed in the vulcanized rubber is not particularly limited. Examples of the above position include the surface and the end of the vulcanized rubber.

[0198] In the case where there are a plurality of vulcanized rubbers, the plurality of vulcanized rubbers can be connected to each other to form a long strip.

[0199] In addition, in one vulcanized rubber or the vulcanized rubbers integrated as described above, the ends in the above-mentioned vulcanized rubber may be bonded to each other to form the above-mentioned vulcanized rubber into a loop shape (ring shape).

[0200] [Conveyor belt]

[0201] The conveyor belt of the present invention is a conveyor belt in which the ends of the belt are bonded to each other using the urethane-based adhesive composition of the present invention.

[0202] The adhesive composition used in the conveyor belt of the present invention is not particularly limited as long as it is the urethane-based adhesive composition of the present invention.

[0203] The belt used for the conveyor belt of the present invention is not particularly limited as long as it can be used for a conveyor belt.

[0204] As the above-mentioned belt (conveyor belt as a raw material), for example, a belt having a structure in which cover rubbers are provided above and below a coated rubber in which a tensile strength material is embedded can be cited. As the above-mentioned tensile strength material, there is no particular limitation, and for example, canvas, steel cord, etc. can be cited.

[0205] The vulcanized rubber constituting the belt is not particularly limited as long as it is a rubber that can be used for a conveyor belt. For example, the vulcanized rubber can be the same as the vulcanized rubber described in the above-mentioned [bonded vulcanized rubber].

[0206] After vulcanization, the vulcanized rubber can be subjected to physical surface treatment such as grinding with a grinding wheel or chemical surface treatment such as a surface treatment agent (for example, a primer) as needed.

[0207] Regarding the vulcanized rubber of the portion bonded in the belt, from the viewpoint that the unevenness of its surface is large and it is easy to penetrate the adhesive composition, resulting in more excellent effects of the present invention, physical surface treatment such as grinding with a grinding wheel is preferably performed.

[0208] [Between the ends of the belt]

[0209] In the present invention, when bonding the ends of the belt to each other, the bonding surface in the belt preferably includes vulcanized rubber.

[0210] When multiple belts are used in the conveyor belt of the present invention, the multiple belts can be connected with the ends of each belt to each other to make the belt elongated and integrated.

[0211] In addition, the ends of one belt can be bonded to each other to form the above-mentioned belt into a loop shape (ring shape). The same applies to the belt that is elongated and integrated as described above.

[0212] The conveyor belt of the present invention is preferably bonded with the adhesive composition of the present invention, and the ends are bonded to each other in one belt, or the ends of the belts that are elongated and integrated as described above are bonded to each other to form an endless (ring-shaped) belt.

[0213] As the manufacturing method (bonding method, endless forming method) of the conveyor belt of the present invention, for example, a belt-shaped belt (the conveyor belt as a raw material. The same applies hereinafter) is produced by vulcanization as usual, and then the adhesive composition of the present invention is applied to the ends of the above belt to bond the ends of the belt to each other. The belt can be processed as described later before applying the adhesive composition of the present invention to the ends of the belt, or it can be unprocessed. Regarding the processing (bonding form), for example, there are the peeling method in which the thickness of the end of the belt is cut obliquely with respect to the traveling direction and bonded; the stepped method in which each layer such as the cover rubber, coating rubber, and tension-resistant material at the end of the belt is peeled and cut stepwise and bonded; the overlapping method in which the ends of the belt are overlapped and bonded (without special processing of the belt); the finger joint method (electro-optical joint method or insertion method) in which the ends of the belt are cut into a wedge shape and butt-jointed and bonded, the method in which the thickness of the end of the belt is cut into a wedge shape with respect to the traveling direction and butt-jointed and bonded, modified types or combined types of each method, etc.

[0214] As the manufacturing method of the conveyor belt of the present invention, for example, the Figure 1 scheme shown. The present invention is not limited to the attached drawings. Figure 1 It is a schematic diagram showing an example of the bonding form of the conveyor belt of the present invention. Figure 1 Regarding the above bonding form, it specifically shows an example of the stepped method in which each layer of the cover rubber, coating rubber, and tension-resistant material (not shown) at the end of the belt is peeled and cut stepwise and bonded.

[0215] As the belt (the rubber to be bonded), as Figure 1 (a) shows, prepare a belt 1 in which each layer of the cover rubber 2a, 2b, coating rubber 3, and tension-resistant material (not shown) in the end region 4 is peeled and cut stepwise, and a belt 1' in which each layer of the cover rubber 2a', 2b', coating rubber 3', and tension-resistant material (not shown) in the end region 4' is peeled and cut stepwise. Then, after applying the adhesive composition of the present invention to the bonding interface in the end region 4 and / or the bonding interface in the end region 4', bond the end region 4 and the end region 4' as Figure 1 (b) shows to manufacture a conveyor belt. That is, Figure 1 (b) shows that the conveyor belt bonds the vulcanized rubbers at the ends of the belt to each other using the adhesive composition of the present invention. Regarding the bonding of vulcanized rubbers to each other, as a combination, for example, in Figure 1In (b), the same type of vulcanized rubber such as the combination of covering rubbers 2a and 2a', covering rubbers 2b and 2b', and coating rubbers 3 and 3' with each other, and different types (or blends) of vulcanized rubber such as the combination of covering rubber 2a and coating rubber 3', and coating rubber 3 and covering rubber 2b'.

[0216] As a method for manufacturing the conveyor belt of the present invention, for example, the adhesive composition of the present invention is applied to the vulcanized rubber of the belt (which can be any of the vulcanized rubbers such as covering rubber and coating rubber possessed by the belt), dried, and then the vulcanized rubbers of the belt (adherend rubbers) are bonded to each other by pressing, and left at 0 to 35 °C (preferably 15 to 30 °C, more preferably 20 to 25 °C) for 3 to 72 hours (preferably 3 to 24 hours, more preferably 6 to 18 hours). Further, by heating and pressurizing, the reaction of the adhesive composition is accelerated, and the time required for the bonding treatment can be shortened. However, in order to avoid over-vulcanization of the vulcanized rubber, the heating is preferably 100 °C or lower.

[0217] Examples

[0218] The following shows examples to specifically illustrate the present invention. However, the present invention is not limited thereto.

[0219] <Manufacture of Adhesive Composition>

[0220] Each component shown in "First Liquid (Blend / Mass Parts)" in the following table is used in the composition (mass parts) shown in the table, and they are mixed with a stirrer to prepare the first liquid.

[0221] Each component shown in "Second Liquid (Blend / Mass Parts)" in the following table is used in the composition (mass parts) shown in the table, and they are mixed with a stirrer to prepare the second liquid.

[0222] Next, the first liquid and the second liquid prepared as described above are mixed in the amounts (mass parts) shown in "Mixing of First Liquid / Second Liquid" in the following table to manufacture each adhesive composition.

[0223] <Production 1 of Adherend Rubber>

[0224] Each component (mass parts) shown in the following (BR-based composite 1) is mixed with a stirrer to prepare an unvulcanized rubber composition. In addition, the following (BR-based composite 1) is the same as the BR-based composite 1 shown in Table 7 below.

[0225] (BR-based composite 1)

[0226] ·100 parts by mass of a rubber component of NR / SBR / BR = 28 / 36 / 36 (mass parts)

[0227] · Carbon black: 65 parts by mass of ISAF carbon black

[0228] · Oil: 6 parts by mass

[0229] · Sulfur: 1.4 parts by mass

[0230] · Vulcanization accelerator D: 0.2 parts by mass

[0231] · Vulcanization accelerator CZ: 1.0 parts by mass

[0232] Next, the unvulcanized rubber composition obtained as described above was vulcanized at 148 °C to obtain a vulcanized rubber (a vulcanized sheet with a size of 6 inches × 4 inches square and a thickness of 2 mm). After the surface of the vulcanized rubber was ground with sandpaper, a surface treatment agent (trade name: Affleet, manufactured by Tokyo Materials Co., Ltd.) was applied and dried to prepare adherend rubber 1.

[0233] <Preparation of laminate 1>

[0234] Prepare 2 sheets of adherend rubber 1 prepared as described above, apply the adhesive composition prepared as described above to each of the adherend rubbers 1, and bond the adherend rubbers 1 to each other on the surface where the adhesive composition has been applied to form a sample. Place a weight of 10 kg on the sample and cure it for 3 hours or 1 week under the conditions of 23 °C and 50% RH to prepare each laminate 1.

[0235] <Evaluation>

[0236] The following evaluations were carried out using each laminate 1 prepared as described above. The results are shown in the "Evaluation Results" in Tables 1 to 6.

[0237] <Adhesiveness>

[0238] Using each laminate 1 cured for 1 week, a T-peel test was carried out at room temperature (23 °C) and a peel rate of 50 mm / min to measure the peel strength (maximum peak strength. Unit: N / 25 mm), and the failure state after the peel test was visually confirmed.

[0239] · Peel strength (after 1 week)

[0240] ◎ indicates that the peel strength of laminate 1 cured for 1 week is 80 N / 25 mm or more.

[0241] ○ indicates that the above peel strength exceeds 60 N / 25 mm and is less than 80 N / 25 mm.

[0242] △ indicates that the above peel strength is 40 - 60 N / 25 mm.

[0243] × indicates that the above peel strength is less than 40 N / 25 mm.

[0244] ·Failure state after peel test (after 1 week)

[0245] CF indicates cohesive failure. MF indicates that the vulcanized rubber has failed. "CF / MF" indicates the coexistence of CF and MF.

[0246] AF indicates interfacial failure. "CF / AF" indicates the coexistence of CF and AF.

[0247] ·Evaluation criteria for adhesiveness to vulcanized rubber

[0248] In the present invention, the adhesiveness to vulcanized rubber containing a high proportion of BR was evaluated based on the peel strength of each laminate 1 after the above-mentioned curing for 1 week and the failure state after the peel test.

[0249] That is, in the present invention, when the peel strength of the laminate 1 after curing for 1 week exceeds 60 N / 25 mm and the failure state is CF and / or MF, the adhesiveness to vulcanized rubber containing a high proportion of BR is evaluated as excellent. The greater the peel strength is than 60 N / 25 mm, the more excellent the adhesiveness is.

[0250] On the other hand, when the peel strength of the laminate 1 after curing for 1 week is 60 N / 25 mm or less, or the failure state is AF, the adhesiveness to vulcanized rubber containing a high proportion of BR is evaluated as poor.

[0251] <Expression of initial strength>

[0252] Using each laminate 1 after curing for 3 hours, a T-shaped peel test was carried out at room temperature (23 °C) and a peel speed of 50 mm / minute, the peel strength (maximum peak strength. Unit: N / 25 mm) was measured, and the failure state after the peel test was confirmed visually.

[0253] ·Peel strength (after 3 hours)

[0254] ◎ indicates that the peel strength of each laminate 1 after curing for 3 hours is 25 N / 25 mm or more.

[0255] ○ indicates that the above peel strength exceeds 10 N / 25 mm and is less than 25 N / 25 mm.

[0256] △ indicates that the above peel strength is 5 - 10 N / 25 mm.

[0257] × indicates that the above peel strength is less than 5 N / 25 mm.

[0258] In addition, the expression of the failure state after the peel test (after 3 hours) is the same as that of the failure state after the above peel test (after 1 week).

[0259] ·Evaluation criteria for the performance of the initial strength

[0260] In the present invention, the performance of the initial strength of the vulcanized rubber containing a high proportion of BR was evaluated based on the peel strength of each laminate 1 after the above-mentioned 3-hour curing and the failure state after the peel test.

[0261] In the present invention, when the peel strength (after 3 hours) of each laminate 1 after 3-hour curing exceeds 10 N / 25 mm and the failure state is CF and / or MF, it is evaluated that the performance of the initial strength of the vulcanized rubber containing a high proportion of BR is excellent. The greater the peel strength is than 10 N / 25 mm, the more excellent the adhesiveness is.

[0262] On the other hand, when the peel strength is 10 N / 25 mm or less, or when the failure state is AF, it is evaluated that the performance of the initial strength of the vulcanized rubber containing a high proportion of BR is poor.

[0263] Table 1

[0264]

[0265] Table 2

[0266]

[0267] Table 3

[0268]

[0269] Table 4

[0270]

[0271] Table 5

[0272]

[0273] Table 6

[0274]

[0275] The details of each component shown in Tables 1 to 6 are as follows.

[0276] [First liquid]

[0277] (Polyol 1)

[0278] ·Polyester polyol 1-1: Vylon GK-810, manufactured by Toyobo Co., Ltd. Tg 46°C, hydroxyl value 19 KOHmg / g, acid value 5 KOHmg / g, Mn 6,000.

[0279] · Polyester polyol 1-2: Vylon GK-890, manufactured by Toyobo Co., Ltd. Tg 17°C, hydroxyl value 13 mg KOH / g, acid value 5 mg KOH / g, Mn 11,000.

[0280] · Polyester polyol 1-3: Vylon 630, manufactured by Toyobo Co., Ltd. Tg 7°C, hydroxyl value 5 mg KOH / g, acid value < 2 mg KOH / g, Mn 23,000.

[0281] · Polyester polyol 1-4: Vylon 500, manufactured by Toyobo Co., Ltd. Tg 4°C, hydroxyl value 5 mg KOH / g, acid value < 2 mg KOH / g, Mn 23,000.

[0282] · Polyester polyol 1-5: Vylon 550, manufactured by Toyobo Co., Ltd. Tg -15°C, hydroxyl value 4 mg KOH / g, acid value < 2 mg KOH / g, Mn 28,000.

[0283] · Polyester polyol 1-6: Vylon UR-3210, manufactured by Toyobo Co., Ltd. Tg -3°C, hydroxyl value 2.5 mg KOH / g, acid value < 1 mg KOH / g, Mn 40,000.

[0284] · Polyester polyol 1-7: Vylon UR-6100, manufactured by Toyobo Co., Ltd. Tg -30°C, hydroxyl value 5 mg KOH / g, acid value < 1 mg KOH / g, Mn 32,000.

[0285] · Comparative polyester polyol: Vylon 200, manufactured by Toyobo Co., Ltd. Tg 67°C, hydroxyl value 6 mg KOH / g, acid value < 2 mg KOH / g, Mn 17,000.

[0286] (Polyol 2)

[0287] · Polyester polyol 2-1: Vylon GK-680, manufactured by Toyobo Co., Ltd. Tg 10°C, hydroxyl value 21 mg KOH / g, acid value < 2 mg KOH / g, Mn 6,000.

[0288] · Butadiene-based polyol 2-1: Poly bd 15HT, manufactured by Idemitsu Kosan Co., Ltd. Hydroxyl value 102.7 mg KOH / g, Mn 1,200. Hydroxyl-terminated liquid polybutadiene. 1.5 Pa·s @ 30°C

[0289] · Butadiene-based polyol 2-2: Poly bd 45HT, manufactured by Idemitsu Kosan Co., Ltd. Hydroxyl value 46.6 mg KOH / g, Mn 2,800. Hydroxyl-terminated liquid polybutadiene. 5.0 Pa·s @ 30°C

[0290] · Polyisoprene skeleton polyol 2: Poly ip, manufactured by Idemitsu Kosan Co., Ltd. Hydroxyl value 46.6 KOH mg / g, Mn 2,500. Hydroxyl-terminated liquid polyisoprene. 7.5 Pa·s @ 30°C

[0291] · Polyolefin skeleton polyol 2: Epole, manufactured by Idemitsu Kosan Co., Ltd. Hydroxyl value 50.5 KOH mg / g, Mn 2,500. Hydroxyl-terminated liquid polyolefin. 75 Pa·s @ 30°C

[0292] · Polyester polyol 2-2: Polyester polyol of 2,4-diethyl-1,5-pentanediol and phthalic anhydride. HS2N-226P, manufactured by Toyo Kosan Co., Ltd. Hydroxyl value 56.1 KOH mg / g, Mn 2,000

[0293] · Polycarbonate polyol 2-1: EATERNACOLL PH200D, manufactured by Ube Industries, Ltd. Hydroxyl value 57.3 KOH mg / g, acid value 0.03 KOH mg / g, Mn 2,000. Polycarbonate polyol using 1,5-pentanediol and 1,6-hexanediol as raw materials. 2200 - 3400 mPa·s @ 75°C (liquid).

[0294] · Polycarbonate polyol 2-2: EATERNACOLL UP-50, manufactured by Ube Industries, Ltd., hydroxyl value 224.4 KOH mg / g, Mn 500, 300 mPa·s @ 75°C (room temperature liquid). Polycarbonate polyol using 2-methyl-1,3-propanediol as raw material

[0295] · Comparative polyether polyol 1: EXCENOL2020, manufactured by Asahi Glass Co., Ltd., hydroxyl value 56.1 KOH mg / g, Mn 2,000

[0296] · Comparative polyether polyol 2: VORANOL TM P 400 Polyol, manufactured by Dow Chemical Co., Ltd., hydroxyl value 260 KOH mg / g, Mn 431

[0297] (Polyol 3)

[0298] · 1,4BD: 1,4-butanediol (commercial product, manufactured by Mitsubishi Chemical Corporation), hydroxyl value 1245 KOH mg / g, molecular weight 431

[0299] · PD-9: 2,4-diethyl-1,5-pentanediol (commercial product, manufactured by KH Neochem Co., Ltd.), hydroxyl value 700 KOH mg / g, molecular weight 160.3

[0300] · BEPG: 2-butyl-2-ethyl-1,3-propanediol (commercial product, manufactured by KH Neochem Co., Ltd.), hydroxyl value 700 KOH mg / g, molecular weight 160.3

[0301] · ND: 1,9-Nonanediol (commercially available product, manufactured by Kuraray Co., Ltd.), hydroxyl value 700 KOHmg / g, molecular weight 160.3

[0302] (Catalyst)

[0303] · Metal catalyst: Tin dioctyl dilaurate. Trade name U-810, manufactured by Nitto Kasei Co., Ltd.

[0304] · Amine-based catalyst: Bis(dimethylaminoethyl) ether. Trade name BL-19, manufactured by Evonik Industries AG

[0305] [Liquid 2]

[0306] · Aromatic polyisocyanate 1: Polymerized MDI. Sumidule 44V-10, manufactured by Sumika Covestro Urethane Co., Ltd., solid content 100%, NCO% 32.0%

[0307] · Aromatic polyisocyanate 2: Carbodiimide-modified MDI. Trade name Millionate MTL, manufactured by Tosoh Corporation. Solid content 100%, NCO% 29.0%

[0308] · Aromatic polyisocyanate 3: Triphenylmethane-4,4’,4”-triisocyanate (Mw 367.36) Desmodur RE, manufactured by Sumika Covestro Urethane Co., Ltd. Solid content 27% by mass, NCO% 9.3%

[0309] · Aliphatic polyisocyanate: A mixture of isocyanurate of pentamethylene diisocyanate and urethane of pentamethylene diisocyanate. Stabio D-376N, manufactured by Mitsui Chemicals, Inc. Solid content 100%, NCO% 22.0%

[0310] According to the results shown in Tables 1 to 6, in Comparative Examples 1 and 2 that do not contain Polyol 1, the adhesiveness to vulcanized rubber containing a high proportion of BR is poor.

[0311] In Comparative Examples 3 to 5 and 8 that do not contain Polyol 2, the adhesiveness to vulcanized rubber containing a high proportion of BR is poor.

[0312] In Comparative Example 6 that does not contain Polyol 1 and 2 and contains chloroprene rubber as a substitute, the adhesiveness to vulcanized rubber containing a high proportion of BR is poor.

[0313] In Comparative Example 7 that does not contain Polyol 1, the adhesiveness to vulcanized rubber containing a high proportion of BR is poor.

[0314] In contrast, the adhesive composition of the present invention has excellent adhesiveness to vulcanized rubber containing BR in a high proportion.

[0315] <Adhesiveness to Various Rubber Adherends>

[0316] As the rubber adherends, six types of belts (BR-based composites 1 to 3, wear-resistant belts, heat-resistant belts, oil-resistant belts) commonly used as the cover rubber of conveyor belts and commonly used coating rubbers were used. The main components and vulcanization systems of each belt are shown in Table 7. In addition, in the following examples, the adhesion between homogeneous vulcanized rubbers was evaluated.

[0317] In addition, in the polymer column in the table, "NR" refers to natural rubber, "NBR" refers to nitrile rubber, "SBR" refers to styrene-butadiene rubber, and "BR" refers to butadiene rubber.

[0318] In addition, in the carbon black column, "ISAF" refers to "Intermidiates Super Abrasion Furnace", "HAF" refers to "High Abrasion Furnace", and "GPF" refers to "General Purpose Furnace".

[0319] In addition, in the vulcanization system column (vulcanization component column),

[0320] "D" refers to a guanidine-based vulcanization accelerator (trade name "Sancerra D-G" manufactured by Sanshin Chemical Industry Co., Ltd.),

[0321] "CZ" refers to a sulfenamide-based vulcanization accelerator (trade name "Nocceler CZ-G" manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.),

[0322] "NS" refers to a sulfenamide-based vulcanization accelerator (trade name "Sancerra NS-G" manufactured by Sanshin Chemical Industry Co., Ltd.),

[0323] "TS" refers to a thiuram-based vulcanization accelerator (trade name "Sancerra TS-G" manufactured by Sanshin Chemical Industry Co., Ltd.),

[0324] "M" refers to a thiazole-based vulcanization accelerator (trade name "Nocceler M" manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.).

[0325] "phr" in the carbon black column, oil / plasticizer column, and vulcanization system column indicates parts by mass relative to 100 parts by mass of the polymer.

[0326] BR-based composite 1 in the table is the same as (BR-based composite 1) used in the above <Production 1 of Rubber Adherend>.

[0327] Table 7

[0328]

[0329] <Production of adherend rubber 2>

[0330] Using the respective components (parts by mass) shown in the rubber compounding of Table 7 above, each adherend rubber was prepared by operating in the same manner as in the above-mentioned <Production of adherend rubber 1> (the same until the application of the surface treatment agent). The adhesive composition shown in “Adhesive composition used” in Table 7 was applied to two pieces of each of the adherend rubbers prepared as described above. Samples were made by bonding the adherend rubbers of the same type (compounding) to each other on the surface where the adhesive composition was applied. A weight of 10 kg was placed on the samples, and they were cured for 1 week under the conditions of 23 °C and 50% RH to prepare each laminate 2.

[0331] <Evaluation>

[0332] Using each laminate 2 prepared as described above, the same evaluation as in the above-mentioned <Adhesiveness> was carried out. The evaluation criteria were also the same as above. The results are shown in Table 7.

[0333] According to the results shown in Table 7, when the adhesive composition of Comparative Example 6, which does not contain polyols 1 and 2 and contains chloroprene rubber instead, was used for vulcanized rubbers (BR-based composites 1 to 3) containing BR in a high proportion, the adhesiveness between the vulcanized rubbers was poor.

[0334] In contrast, the adhesive composition of the present invention has excellent adhesiveness to vulcanized rubbers (e.g., the cover rubber of the BR-based composite in a conveyor belt) containing BR in a high proportion such as more than 30% by mass in the vulcanized rubber.

[0335] In addition, the adhesive composition of the present invention also has excellent adhesiveness to vulcanized rubbers that do not contain BR or contain BR in a low proportion (30% by mass or less in the vulcanized rubber) (e.g., the heat-resistant belt or the coating rubber in a conveyor belt).

[0336] Explanation of symbols

[0337] 1, 1’ belt

[0338] 2a, 2b, 2a’, 2b’ cover rubber

[0339] 3, 3’ coating rubber

[0340] 4, 4’ end region.

Claims

1. A urethane-based adhesive composition containing a polyol component and a polyisocyanate component, wherein the polyol component comprises the following polyol 1 and polyol 2, and the urethane-based adhesive composition is used for bonding vulcanized rubber. Polyol 1: A polyol compound having a glass transition temperature of -30 to +60 °C, a hydroxyl value of 1 to 20 KOHmg / g, and having an ester bond. Polyol 2: A polyol compound having a hydroxyl value exceeding 20 KOHmg / g and being 500 KOHmg / g or less, and having a skeleton with at least one selected from polymers of isoprene and / or butadiene, their hydrides, polyolefins, ester bonds, and carbonate bonds. The molar ratio of all isocyanate groups in the polyisocyanate component to all hydroxyl groups in the polyol component is 0.7 to 5.

5.

2. The urethane-based adhesive composition according to claim 1, wherein the proportion of the hydroxyl groups in polyol 1 among all the hydroxyl groups in the polyol component is 10 to 30 mol%.

3. The urethane-based adhesive composition according to claim 1 or 2, wherein the proportion of the hydroxyl groups in polyol 2 among all the hydroxyl groups in the polyol component is 40 to 70 mol%.

4. The urethane-based adhesive composition according to claim 1 or 2, wherein the polyol component further comprises polyol 3 having a hydroxyl value exceeding 500 KOHmg / g and being 1300 KOHmg / g or less.

5. The urethane-based adhesive composition according to claim 4, wherein the hydroxyl value of polyol 3 is 1000 to 1300 KOHmg / g.

6. The urethane-based adhesive composition according to claim 4, wherein the proportion of the hydroxyl groups in polyol 3 among all the hydroxyl groups in the polyol component is 10 to 40 mol%.

7. The urethane-based adhesive composition according to claim 5, wherein the proportion of the hydroxyl groups in polyol 3 among all the hydroxyl groups in the polyol component is 10 to 40 mol%.

8. The urethane-based adhesive composition according to claim 1 or 2, wherein the molar ratio of all isocyanate groups in the polyisocyanate component to all hydroxyl groups in the polyol component is 1.0 to 3.

0.

9. The urethane-based adhesive composition according to claim 1 or 2, wherein the glass transition temperature of polyol 1 is 0 to +50 °C.

10. The urethane-based adhesive composition according to claim 1 or 2, wherein the number average molecular weight of polyol 1 is 6,000 to 23,000.

11. The urethane-based adhesive composition according to claim 1 or 2, wherein polyol 2 has at least polyisoprene, polybutadiene, their hydrides, or polycarbonate as a skeleton.

12. The urethane-based adhesive composition according to claim 1 or 2, which further contains a solvent, and the solvent at least comprises an acetate-based solvent.

13. A method for bonding vulcanized rubber, wherein, Bond vulcanized rubbers to each other using the urethane-based adhesive composition according to any one of claims 1 to 12.

14. A conveyor belt, wherein, Bond the ends of the belt to each other using the urethane-based adhesive composition according to any one of claims 1 to 12.

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