Moisture-curing hot melt adhesive composition

Abstract

To provide a new moisture-curing hot-melt adhesive composition with superior effectiveness. [Solution] One embodiment of the present invention is a moisture-curable hot-melt adhesive composition comprising a urethane prepolymer, wherein the urethane prepolymer is obtained by reacting a polyol compound with a polyisocyanate compound, and the amount of urethane bonding in the urethane prepolymer is 0.90 mol / kg or more.

Description

Technical Field

[0001] The present invention relates to a moisture-curable hot-melt adhesive composition.

Background Art

[0002] A moisture-curable hot-melt adhesive that reacts with moisture and cures can be applied to an adherend, and after pressing another adherend onto this coated surface and then cooling and solidifying, the adherends can be joined only by this process, and the workability is high. Therefore, moisture-curable hot-melt adhesives are used in various fields including the construction field, the electrical field, and the automotive field. In general, a crystalline ester polyol is formulated in a moisture-curable hot-melt adhesive in order to obtain a high initial peel strength (peel strength immediately after joining). Since ester polyol undergoes hydrolysis in a wet-heat environment, the adhesiveness after joining may become unstable.

[0003] Patent Document 1 discloses a moisture-curable polyurethane hot-melt resin composition containing a polycarbonate polyol made from a glycol compound having a branched structure, which is excellent in initial adhesive strength, final adhesive strength, and hydrolysis resistance.

[0004] Patent Document 2 discloses an adhesive composition containing one or more effective amounts of non-polymer diols selected from aromatic diols, aliphatic diols, and mixtures thereof, and optionally a functional and / or non-functional polymer (acrylic-based) or mixtures thereof, which has improved green strength and hydrolysis resistance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the moisture-curing polyurethane hot melt resin composition described in Patent Document 1 had a high viscosity, which could limit the types of coating machines that could be used for application. Furthermore, the adhesive composition described in Patent Document 2 contained an acrylic polymer, which required application at a higher temperature, and there was a risk that the adhesive composition would gel.

[0007] Therefore, the object of the present invention is to provide a new moisture-curing hot-melt adhesive composition that has superior effects. [Means for solving the problem]

[0008] The inventors of this invention have conducted diligent research and discovered that a moisture-curing hot-melt adhesive composition containing a specific urethane prepolymer can solve the above problems, thereby completing the present invention. That is, the present invention is as follows.

[0009] Embodiment (1) of the present invention is A moisture-curing hot-melt adhesive composition containing a urethane prepolymer, The aforementioned urethane prepolymer is obtained by reacting a polyol compound with a polyisocyanate compound. This is a moisture-curing hot-melt adhesive composition characterized in that the amount of urethane bonding in the urethane prepolymer is 0.90 mol / kg or more. Embodiment (2) of the present invention is The moisture-curing hot-melt adhesive composition of embodiment (1) is characterized by further comprising a carbodiimide compound. Embodiment (3) of the present invention is The moisture-curable hot-melt adhesive composition of embodiment (2) is characterized in that the molecular weight or number-average molecular weight of the carbodiimide compound is 500 or more. Embodiment (4) of the present invention is The polyol compound is a moisture-curable hot-melt adhesive composition of any of the above embodiments (1) to (3), characterized in that it comprises a polyether polyol compound and a polyester polyol compound. Embodiment (5) of the present invention is The moisture-curing hot-melt adhesive composition according to any of the above embodiments (1) to (4) is characterized in that the amount of ester bonds in the urethane prepolymer is 6.00 mol / kg or less. Embodiment (6) of the present invention is A moisture-curing hot-melt adhesive composition according to any of the above embodiments (1) to (5), characterized in that it is for use as an interior material for automobiles. Embodiment (7) of the present invention is A first substrate and a second substrate are laminated with an adhesive layer in between. The adhesive layer is a cured product of any of the moisture-curing hot-melt adhesive compositions of form (1) to (6), The first substrate and the second substrate are each independently selected from the group consisting of foam, natural leather, synthetic leather, film, woven fabric, and nonwoven fabric, resulting in a laminate. [Effects of the Invention]

[0010] According to the present invention, a new moisture-curing hot-melt adhesive composition with superior effects can be provided. [Modes for carrying out the invention]

[0011] Furthermore, if isomers exist for the compounds described, all possible isomers can be used in this invention unless otherwise specified.

[0012] Furthermore, in this application, the number-average molecular weight is measured using gel per-emission chromatography. In this application, if the upper limit and lower limit are stated separately, it shall be considered that a numerical range combining any upper limit and any lower limit is substantially disclosed. In this application, unless otherwise specified, various measurements are carried out at an environmental temperature of room temperature (25°C).

[0013] 1. Moisture-curable hot melt adhesive composition The moisture-curable hot melt adhesive composition of the present disclosure contains a urethane prepolymer. The urethane prepolymer according to the present disclosure is obtained by reacting a polyol compound and a polyisocyanate compound. Further, the urethane prepolymer preferably has a urethane bond amount contained in the urethane prepolymer of 0.90 mol / kg or more, but the present disclosure is not limited thereto.

[0014] The moisture-curable hot melt adhesive composition can further contain a carbodiimide compound. Further, the moisture-curable hot melt adhesive composition can contain other additives as necessary.

[0015] The moisture-curable hot melt adhesive composition of the present disclosure will be described in detail below.

[0016] 1-1. Raw materials of the moisture-curable hot melt adhesive composition 1-1-1. Urethane prepolymer The urethane prepolymer according to the present disclosure is obtained by reacting a polyol compound and a polyisocyanate compound. The hydroxyl group contained in the polyol compound reacts with the isocyanate group contained in the polyisocyanate compound to form a urethane bond, and a urethane prepolymer can be obtained. Further, the urethane prepolymer can contain a catalyst as its raw material when reacting the polyol compound and the polyisocyanate compound.

[0017] · Polyol compound The polyol compounds used as raw materials for the urethane prepolymer according to this disclosure are not particularly limited as long as they do not hinder the effects of this disclosure, and include polyether polyol compounds, polyester polyol compounds, polycarbonate polyol compounds, polyester ether polyol compounds, polyhydric phenol compounds, and the like. These can be used individually or in combination.

[0018] Examples of polyether polyol compounds include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and their copolyethers, which are obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide, and tetrahydrofuran, respectively. They can also be obtained by polymerizing the above-mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane. Examples of polyester polyol compounds include polyols obtained by the dehydration condensation reaction of a polycarboxylic acid compound (e.g., a dicarboxylic acid) and a polyol compound (e.g., a diol). Examples of polycarboxylic acid compounds include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or acid esters or acid anhydrides thereof. Examples of polyol compounds include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or mixtures thereof. Other examples of polyester polyols include polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone. Examples of polycarbonate polyol compounds include those obtained by reacting at least one polyhydric alcohol, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or diethylene glycol, with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like. Examples of polyester ether polyol compounds include polyols obtained by a dehydration condensation reaction between a polycarboxylic acid compound (e.g., a dicarboxylic acid) and a polyether polyol. Examples of polycarboxylic acid compounds include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or their acid esters or acid anhydrides. Examples of polyether polyols include glycols such as diethylene glycol or propylene oxide adducts; or mixtures thereof. Examples of polyhydric phenol compounds include monocyclic polyhydric phenols such as pyrogallol and hydroquinone; and bisphenols such as bisphenol A, bisphenol F, and bisphenol sulfone.

[0019] These polyol compounds can be used individually or in combination. In particular, polyether polyol compounds can improve the hydrolysis resistance of the cured product of moisture-curable hot-melt adhesive compositions. Polyester polyol compounds also have the effect of improving the heat resistance of the cured product of moisture-curable hot-melt adhesive compositions. Since these effects are achieved simultaneously, it is preferable that the polyol compound contains both a polyether polyol compound and a polyester polyol compound.

[0020] The mixing ratio (mass ratio) of the polyether polyol compound to the polyester polyol compound is not particularly limited as long as it does not hinder the effects of this disclosure. For example, (total mass of all polyether polyol compounds / total mass of all polyester polyol compounds) can be 20 / 80 to 80 / 20, preferably 30 / 70 to 70 / 30, more preferably 40 / 60 to 60 / 40, and even more preferably 45 / 55 to 65 / 35. When the mixing ratio of the polyether polyol compound to the polyester polyol compound is within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be improved. In this disclosure, the polyester ether polyol compound is treated as a polyether polyol compound.

[0021] The molecular weight or number-average molecular weight of the polyol compound is not particularly limited as long as it does not hinder the effects of this disclosure, and can be freely selected considering the physical properties of the urethane prepolymer. The molecular weight or number-average molecular weight of the polyol compound can be, for example, 300 to 8,000.

[0022] The hydroxyl value of the polyol compound is not particularly limited as long as the effects of this disclosure are not hindered, and can be freely selected considering the physical properties of the urethane prepolymer. The hydroxyl value of the polyol compound can be, for example, 50 to 1,000 mgKOH / g. Here, the hydroxyl value is a value measured in accordance with JIS K0070:1992 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products".

[0023] • Polyisocyanate compounds The polyisocyanate compounds used as raw materials for the urethane prepolymers relating to this disclosure are not particularly limited, as long as they do not impair the effects of this disclosure. The polyisocyanate compound may be a bifunctional polyisocyanate compound or a trifunctional or more functional polyisocyanate compound. Furthermore, the polyisocyanate compound may be aromatic, aliphatic, or alicyclic. For example, a bifunctional polyisocyanate compound is: Aromatic polyisocyanate compounds include 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethandianate (2,4'-MDI), and 2,2'-diphenylmethane diisocyanate. (2,2'-MDI), hydrogenated MDI, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, polymethylene polyphenyl polyisocyanate, 1,5-naphthalenediisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylenediisocyanate (TMXDI), etc. Examples of alicyclic polyisocyanate compounds include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate; Examples of alkylene-based polyisocyanate compounds include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropyl diisocyanate, methylene diisocyanate, and lysine diisocyanate; These are some examples. Examples of polyisocyanate compounds with three or more functions include isocyanate compounds such as 1-methylbenzol-2,4,6-triisocyanate, 1,3,5-trimethylbenzol-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate, triphenylmethane-4,4',4”-triisocyanate, polymeric MDI, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and 1,8-diisocyanatomethyloctane. Furthermore, these polyisocyanate compounds may include modified forms, derivatives, and the like. These polyisocyanate compounds can be used individually or in combination. The polyisocyanate compound is preferably MDI, TDI, or a modified or derivative of MDI or TDI, and more preferably monomeric MDI and crude MDI.

[0024] ·catalyst As a catalyst, known catalysts that promote the urethane reaction can be used. More specifically, examples of catalysts include metal catalysts such as tin-based catalysts and lead-based catalysts; amine-based catalysts; acidic catalysts; basic catalysts; and so on. These catalysts can be used individually or in combination.

[0025] 1-1-2. Properties of urethane prepolymers • Amount of urethane bond The amount of urethane bonds in the urethane prepolymer according to this disclosure refers to the amount of urethane bonds contained in the urethane prepolymer. The amount of urethane bonds in the urethane prepolymer can be adjusted by the hydroxyl value of the polyol compound and the number of isocyanate groups contained in the polyisocyanate compound, which are blended as raw materials for the urethane prepolymer. That is, the amount of urethane bonds in the urethane prepolymer can be adjusted by the isocyanate index of the raw materials for the urethane prepolymer, as described later.

[0026] The amount of urethane bonding in the urethane prepolymer is preferably 0.90 mol / kg or more, more preferably 1.00 mol / kg or more, 1.10 mol / kg or more, 1.20 mol / kg or more, or 1.30 mol / kg or more. The upper limit of the amount of urethane bonding contained in the urethane prepolymer is not particularly limited, but for example, it is 5.00 mol / kg or less, 4.00 mol / kg or less, 3.00 mol / kg or less, 2.50 mol / kg or less, 2.00 mol / kg or less, or 1.50 mol / kg or less. When the amount of urethane bonding contained in the urethane prepolymer is within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be made even better.

[0027] The amount of urethane bonded is calculated using the following method. This study covers all polyol compounds and polyisocyanate compounds that serve as raw materials for urethane prepolymers. For a urethane prepolymer mass of 1 kg, the amount (mass) of each polyol compound and polyisocyanate compound is determined so that the NCO% of the urethane prepolymer reaches the desired value. The amount (mass) of each polyol compound is divided by its molecular weight, and then multiplied by the number of functional groups in each polyol compound to calculate the total number of hydroxyl groups in all polyol compounds. This number of hydroxyl groups is then considered the amount of urethane bonding in the urethane prepolymer, assuming that all of these hydroxyl groups react with the isocyanate groups of the polyisocyanate compounds to form urethane bonds.

[0028] • Amount of ester bonds The amount of ester bonds in the urethane prepolymer according to this disclosure refers to the amount of ester bonds contained in the urethane prepolymer. The amount of ester bonds in the urethane prepolymer can be adjusted by the amount of polyester polyol compound added.

[0029] The amount of ester bonds is measured by the following method. This study covers all polyol compounds and polyisocyanate compounds that serve as raw materials for urethane prepolymers. For a urethane prepolymer mass of 1 kg, the amount (mass) of each polyol compound and polyisocyanate compound is determined so that the NCO% of the urethane prepolymer reaches the desired value. The amount (moles) of each polyester polyol compound is calculated by dividing the total amount (mass) of each polyester polyol compound by the number-average molecular weight of each polyester polyol. The amount (moles) of each polyester polyol is then divided by the molecular weight per unit of the repeating structure within each polyester polyol, and multiplied by the number of ester groups per unit of the repeating structure within each polyester polyol to calculate the amount of ester bonds in each polyester polyol. The total amount of ester bonds in the urethane prepolymer is then calculated by summing the amounts of ester bonds in each polyester polyol compound. Here, for example, in the case of a polyester polyol composed of a polycarboxylic acid compound and a polyol compound, the individual structure of the repeating structure composed of these compounds is considered as one constituent unit of the repeating structure. In this case, for example, when the polycarboxylic acid is a dicarboxylic acid and the polyol compound is a diol, the molecular weight per constituent unit of the repeating structure is the mass of the structure obtained by subtracting the mass of [(2 hydrogen atoms + 1 oxygen atom) × 2] from the sum of the molecular weights of the polycarboxylic acid compound and the polyol compound.

[0030] The amount of ester bonds in the urethane prepolymer is not particularly limited, but preferred upper limits are 6.00 mol / kg or less, 5.00 mol / kg or less, 4.00 mol / kg or less, and 3.50 mol / kg or less, and preferred lower limits are 0.50 mol / kg or more, 1.00 mol / kg or more, 1.50 mol / kg or more, and 1.70 mol / kg or more. The urethane prepolymer does not need to contain ester bonds (the amount of ester bonds may be 0.00 mol / kg), but if the amount of ester bonds contained in the urethane prepolymer is within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be improved. Furthermore, when the urethane prepolymer contains ester bonds, the upper limit of [amount of ester bonds in the urethane prepolymer] / [amount of urethane bonds in the urethane prepolymer] is preferably 10.0 or less, 7.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.2 or less, and the lower limit is preferably 0.1 or more, 0.2 or more, 0.5 or more, 1.0 or more, or 1.1 or more.

[0031] ·Number average molecular weight The number-average molecular weight of the urethane prepolymer is not particularly limited as long as it does not hinder the effects of this disclosure, and can be between 3,000 and 8,000. By adjusting the number-average molecular weight of the urethane prepolymer, properties such as the adhesive strength of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be adjusted. The number-average molecular weight of the urethane prepolymer can be measured by gel permeation chromatography (GPC) (standard polymer = polystyrene).

[0032] ·viscosity The viscosity of the urethane prepolymer is not particularly limited as long as it does not hinder the effects of the present invention. For example, the melt viscosity of the urethane prepolymer at 140°C can be 2,000 to 6,000 mPa·s. By adjusting the viscosity of the urethane prepolymer, properties such as the coatability of the moisture-curing hot-melt adhesive composition can be adjusted. The melt viscosity of the urethane prepolymer at 140°C shall be measured using a rheometer (Anton Paar, MCR302) with a parallel plate attached, after heating the sample to 140°C and under conditions of a frequency of 1 Hz and a shear rate of 1 rad / s.

[0033] • Isocyanate group content (NCO%) The NCO% of the urethane prepolymer is not particularly limited as long as the effects of this disclosure are not hindered, but is preferably 0.3% to 3.5%, and more preferably 1.2% to 2.5%. When the NCO% of the urethane prepolymer is within this range, it is possible to promote curing by moisture while suppressing foaming during work, and furthermore, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot melt adhesive composition can be improved. The NCO% (isocyanate group content) of the prepolymer can be measured in accordance with Method A (toluene / dibutylamine, hydrochloric acid method) of JIS K1603-1:2007 "Plastics - Test methods for aromatic isocyanates in polyurethane raw materials Part 1: Method for determining isocyanate group content".

[0034] Gel fraction The gel fraction of the urethane prepolymer is not particularly limited as long as the effects of this disclosure are not inhibited, but its lower limit is preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more, and its upper limit is 95% by mass or less, 90% by mass or less, or 85% by mass or less. By setting it within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be made even better.

[0035] The gel fraction is calculated using the following method. A predetermined amount (e.g., 0.045 g) of cured material from a moisture-curing hot-melt adhesive composition is weighed out, immersed in a predetermined amount (e.g., 9 g) of tetrahydrofuran (THF), left to stand for 20 hours, the insoluble portion of the cured material remaining in the THF without dissolving is removed, vacuum-dried, its mass is measured, and the gel fraction is calculated by dividing it by the mass of the cured material before immersion.

[0036] 1-2. Carbodiimide Compounds The moisture-curing hot-melt adhesive compositions of this disclosure may contain carbodiimide compounds. The carbodiimide compounds according to this disclosure are not particularly limited as long as they are compounds having a carbodiimide group. Examples of carbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide, cyanamide, N,N'-diisopropylcarbodiimide, N,N'-dicyclohexylcarbodiimide, N-cyclohexylcarbodiimide, N'-methylpolystyrene 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and metho-p-toluene. Examples include 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide sulfonic acid, bis(2,6-diisopropylphenyl)carbodiimide, bis(trimethylsilyl)carbodiimide, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimidemetho-p-toluenesulfonate, N,N'-di-tert-butylcarbodiimide, and 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimidemethiozide. Other commercially available products include Carbodilite® E-02, E-03A, E-05, E-pellets, HMV-15CA, HMV-5CA-LC, LA-1, SV-02, SW-12G, V-02, V-02B, V-02-L2, V-03, V-04, V-05, V-07, V-09, V-09GB, V-10 from Nisshinbo Chemical Corporation; Stavaxol® I, P, P100 from Rhein Chemie Corporation; LUBIO AS 15, LUBIO AS1-SP, LUBIO AS 4 from Schaefer Corporation; and Elastostab H01 from BASF Corporation. These carbodiimide compounds can be used individually or in combination. When a moisture-curing hot-melt adhesive composition contains a carbodiimide compound, the moist heat aging properties of the cured product obtained by curing the moisture-curing hot-melt adhesive composition can be further improved.

[0037] The molecular weight or number-average molecular weight of the carbodiimide compound is not particularly limited as long as it does not hinder the effects of this disclosure, but is preferably 300 to 10,000, more preferably 400 to 8,000, even more preferably 500 to 8,000, and particularly preferably 500 to 5,000. When the molecular weight or number-average molecular weight of the carbodiimide compound is within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curable hot-melt adhesive composition can be further improved. Furthermore, carbodiimide compounds volatilized from moisture-curing hot-melt adhesive compositions or their cured products may adhere to surrounding objects in the usage environment, causing their surfaces to become cloudy. For example, when used for bonding automotive interior components, it may cause clouding of the car's glass. By setting the molecular weight or number-average molecular weight of the carbodiimide compound to 500 or more, it becomes easier to prevent such clouding.

[0038] 1-3. Other additives The moisture-curing hot melt adhesive compositions of this disclosure may optionally contain other additives. Other additives are not limited to known components found in moisture-curing hot melt adhesive compositions. Examples of other additives include fillers, plasticizers, pigments, dyes, antioxidants, defoamers, nucleating agents, antistatic agents, flame retardants, adhesion promoters, antimicrobial agents, light stabilizers, stabilizers, dispersants, solvents, hydrophilic agents, waxes, and the like. These may be used individually or in combination.

[0039] 2. Method for producing a moisture-curing hot-melt adhesive composition 2-1. Method for producing urethane prepolymer The method for producing the urethane prepolymer is not particularly limited, and known methods can be used. Specifically, for example, a predetermined amount of polyisocyanate compound is placed in a container and stirred under a nitrogen gas atmosphere. A predetermined amount of polyol compound is then added dropwise. A catalyst may be added as needed to promote the reaction. Stirring for the specified time is allowed to complete the reaction. At this point, a portion of the reaction product may be sampled, and the isocyanate group content may be measured to confirm that it is within the desired range.

[0040] The amounts of polyol compound and polyisocyanate compound are not particularly limited, but for example, they can be blended so that the isocyanate index of the urethane prepolymer is 0.5 to 2.0, preferably 1.0 to 2.0, and more preferably 1.2 to 1.6. Here, the isocyanate index refers to the ratio of the total number of moles of active hydrogen in the resin composition, which is the raw material blend of the urethane prepolymer, to the number of moles of isocyanate groups in the polyisocyanate compound (moles of isocyanate groups / moles of active hydrogen).

[0041] The amount of catalyst added is not particularly limited, but for example, if the total amount of the polyol compound is 100 parts by mass, the amount of catalyst can be 0.01 to 5.0 parts by mass.

[0042] 2-2. Method for producing moisture-curing hot-melt adhesive compositions The method for producing a moisture-curing hot-melt adhesive composition when additives other than urethane prepolymers are added is not particularly limited, and known methods can be used. Specifically, for example, a predetermined amount of urethane prepolymer is placed in a container, a carbodiimide compound and other additives are added thereto, and the mixture is stirred.

[0043] The amount of carbodiimide compound blended is not particularly limited as long as it does not hinder the effects of this disclosure. The amount of carbodiimide compound blended is preferably 0.1 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, 1.5 parts by mass or more, 2.0 parts by mass or more, 2.5 parts by mass or more, or 3.0 parts by mass or more, when the total amount of polyol compound blended into the urethane prepolymer is 100 parts by mass, and is also preferably 10.0 parts by mass or less, 8.0 parts by mass or less, 6.0 parts by mass or less, or 5.0 parts by mass or less. For example, when the total amount of polyol compound blended into the urethane prepolymer is 100 parts by mass, the amount can be 0.1 to 10.0 parts by mass, preferably 1.0 to 10.0 parts by mass, more preferably 1.0 to 8.0 parts by mass, even more preferably 1.0 to 6.0 parts by mass, even more preferably 1.0 to 5.0 parts by mass, and particularly preferably 3.0 to 5.0 parts by mass. When a moisture-curing hot-melt adhesive composition contains a carbodiimide compound within this range, the moist heat aging properties of the cured product obtained by curing the moisture-curing hot-melt adhesive composition can be further improved. The amount of other additives (additives other than urethane prepolymer and carbodiimide compounds) blended (total blended amount) is not particularly limited as long as it does not hinder the effects of this disclosure. For example, if the total amount of polyol compounds blended into the urethane prepolymer is 100 parts by mass, the amount can be 10.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or 1.0 part by mass or less, or 0.1 parts by mass or more, 0.2 parts by mass or more, 0.3 parts by mass or more, 0.4 parts by mass or more, or 0.5 parts by mass or more.

[0044] 3. Applications of moisture-curing hot melt adhesive compositions Moisture-curing hot-melt adhesive compositions are suitable for use in building interior components such as decorative sheet covering materials, furniture components, and interior materials for automobiles, railways, ships, and aircraft (for example, for bonding the seams of seat and headrest cover pads). They are particularly suitable for use in automobile interior materials used in high-temperature and high-humidity environments.

[0045] The moisture-curing hot-melt adhesive composition can be applied to an object by heating and melting it. Known application methods can be used, such as brushes, spatulas, syringes, sealing guns, and dispensers. Furthermore, since the moisture-curing hot-melt adhesive composition of this disclosure can have a low melt viscosity, it can also be applied using a non-contact method (e.g., a spray method). From the viewpoint of improving breathability and productivity (for example, making it easier to manufacture even long objects), application to the object by spray coating is preferable. The application amount (or basis weight) of the moisture-curing hot melt adhesive composition is 1 to 100 g / m². 2 Preferably, it is 3-50 g / m 2 It is more preferable that the amount be 5-30 g / m 2 It is particularly preferable that this be the case.

[0046] The technology relating to this disclosure may be provided as a cured product of a moisture-curable hot-melt adhesive composition, or as a laminate containing a cured product of a moisture-curable hot-melt adhesive composition. For example, the technology relating to this disclosure may be a laminate in which a first substrate and a second substrate are laminated with an adhesive layer in between, wherein the adhesive layer is a cured product of the moisture-curable hot-melt adhesive composition relating to this disclosure. In this case, the material and shape of the first substrate and the second substrate are not particularly limited, but it is preferable that the first substrate and the second substrate be independently selected from the group consisting of foam (e.g., urethane foam), natural leather, synthetic leather, film (resin film), woven fabric and nonwoven fabric. Such laminates can be manufactured by applying the application method of the moisture-curing hot-melt adhesive composition described above. Such laminates can be used as building interior components such as decorative sheet covering materials, furniture components, and components that make up interior materials for automobiles, railways, ships, aircraft, etc. [Examples]

[0047] The effects of the moisture-curing hot-melt adhesive composition of this disclosure will be specifically explained below with reference to examples. Table 1 shows the raw materials for each example and comparative example of the moisture-curing hot melt adhesive composition produced, and the evaluation results of the obtained moisture-curing hot melt adhesive compositions.

[0048] <Manufacturing of moisture-curing hot-melt adhesive compositions> In a 1-liter four-necked flask equipped with a stirring blade, MDI was added as a polyisocyanate compound in the proportions shown in Table 1. The flask was then purged with nitrogen gas and heated to 80°C. Next, polyol compounds were added to the flask in the proportions shown in Table 1, heated to 80°C and melted. The mixture was then stirred for at least 2 hours under a nitrogen gas atmosphere while maintaining the liquid temperature below 100°C. This caused the polyol compounds and polyisocyanate compounds to react and obtain a urethane prepolymer. Furthermore, carbodiimide compounds and other additives were added according to Table 1, and the mixture was stirred for at least 2 hours to obtain the moisture-curable hot-melt adhesive compositions of each example and comparative example.

[0049] The raw materials used in the moisture-curing hot melt adhesive composition are shown below. • Polyol compounds Polyester polyol Polyol 1: A reaction product of sebacic acid (SA) and 1,6-hexanediol (HD), with a number-average molecular weight of 5,000. Polyol 2: A reaction product of adipic acid (AA) and 1,6-hexanediol (HD), with a number-average molecular weight of 4,500. Polyol 3: A reaction product of adipic acid (AA) and terephthalic acid with ethylene glycol and 1,4-butylene glycol (BG), with a number average molecular weight of 3,000. Polyol 4: A reaction product of 1,12-dodecanediol (DDA) and 1,6-hexanediol (HD), with a number-average molecular weight of 3,700. Polyol 5: A reaction product of adipic acid (AA) and 1,4-butanediol (BD), with a number-average molecular weight of 2,000. Polyether polyol Polyol 6: Polypropylene glycol (PPG), number average molecular weight 1,000 Polyol 7: Polypropylene glycol (PPG), number average molecular weight 700 Polyol 8: A copolymer of bisphenol A (BP) and propylene oxide (PO), with a number average molecular weight of 500. ·wax (1) Microcrystalline wax Hi-Mic-2095 manufactured by Nippon Seiro Co., Ltd. • Anti-packaging agent (1) Dappo SN348 manufactured by Sanopco • Anti-aging agent (1) BASF IRGANOX 1076 (2) BASF IRGAFOS168 ·catalyst (1) DMDEE (amine-based catalyst, dimorpholino diethyl ether) • Crystallization agent (1) ADEKA NA11 • Polyisocyanate compounds (1) Monomeric MDI, molecular weight: 250 • Carbodiimide compounds (1) Carbodilite V04PF manufactured by Nisshinbo Chemical Co., Ltd., number average molecular weight: 2,000 (2) Stavaxol I, manufactured by Rhein Chemie, number average molecular weight: 380 (3) Stavaxol P, manufactured by Rhein Chemie, number average molecular weight: 2,000 (4) Schaefer LUBIO AS 15, number average molecular weight: 1,500 (5) Carbodilite HMV-15CA manufactured by Nisshinbo Chemical Co., Ltd., number average molecular weight: 3,400 (6) Elastostab H01 manufactured by BASF, number average molecular weight: 1,900

[0050] <Evaluation and Measurement> • NCO% of urethane prepolymer The NCO% of the urethane prepolymer in each example and comparative example was measured in accordance with Method A (toluene / dibutylamine, hydrochloric acid method) of JIS K1603-1:2007 "Plastics - Test methods for aromatic isocyanates in polyurethane raw materials Part 1: Method for determining isocyanate group content".

[0051] • Isocyanate index of urethane prepolymer The isocyanate index of the urethane prepolymers for each example and comparative example is shown.

[0052] ·Compatibility The compatibility of the carbodiimide compound with the urethane prepolymer in the moisture-curing hot-melt adhesive compositions of each example and comparative example containing the carbodiimide compound was observed visually. For the observation, the carbodiimide compound of each example and comparative example was added to the urethane prepolymer of each example and comparative example under a nitrogen gas atmosphere, and the mixture was stirred for 1 hour to prepare the evaluation sample. The evaluation criteria were as follows. A "-" was used if the carbodiimide compound was not present. ○: No suspension of urethane prepolymer was observed with the naked eye. ×: The suspension of the urethane prepolymer was observed with the naked eye.

[0053] • Amount of urethane bonds in urethane prepolymer The amount of urethane bonding in the urethane prepolymer of each example and comparative example was calculated using the method described above.

[0054] • Amount of ester bonds in urethane prepolymers The amount of ester bonds in the urethane prepolymer of each example and comparative example was calculated using the method described above.

[0055] • Gel fraction of urethane prepolymer The moisture-curing hot-melt adhesive compositions of each example and comparative example were applied to a release-treated PET film and cured to obtain the cured products of each example and comparative example. 0.045 g of the obtained cured product was weighed out and immersed in 9 g of tetrahydrofuran (THF), and left to stand for 20 hours. The insoluble portion of the cured product remaining in the THF without dissolving was removed, vacuum-dried, and its mass was measured. The gel fraction of the urethane prepolymer was calculated by dividing the mass by 0.045 g.

[0056] • Glass haze level The moisture-curing hot-melt adhesive compositions of each example and comparative example were melted at 130°C and dispensed at a rate of 20 g / m² using a hand gun. 2 A polyurethane foam (EL-67F, manufactured by Inoac Co., Ltd.) was spray-coated to achieve the desired result. The polyurethane foam was then bonded to a surface made of fabric (PET material), and cured at room temperature for 12 hours to obtain a laminate. The laminate was processed to a diameter of 80 mm and a thickness of 250 μm to create a test specimen for evaluation. The test specimen was placed at the bottom of a glass container (a container that was not open at the top) with a diameter of 90 mm and a height of 190 mm. A glass petri dish was placed on top of the test specimen (inside the glass container), and 1 ml of ethylenediamine aqueous solution at a concentration of 0.012 g / ml was placed in the glass petri dish. The top of this glass container was sealed with a glass plate with a diameter of 90 mm, and the container was left in a constant temperature bath at 80°C for 72 hours. After that, the glass plate was removed, and the reflectance of the treated glass plate was measured using a gloss meter. The degree of glass haze was calculated from the reflectance of the glass plate before treatment, which was measured beforehand, according to formula 1 below. The reflectance values ​​before and after processing were measured nine times for each glass plate, and the average value was used. (Formula 1) Glass haze degree = Reflectance of glass plate after treatment / Reflectance of glass plate before treatment × 100 Furthermore, the degree of glass haze was judged according to the following evaluation criteria. ○: 90.0% or higher △: 70.0% or more and less than 90.0% ×: Less than 70.0%

[0057] ·Moist heat aging The moisture-curing hot-melt adhesive compositions of each example and comparative example were melted at 130°C and dispensed at a rate of 20 g / m² using a hand gun. 2 The polyurethane foam (EL-67F, manufactured by Inoac Co., Ltd.) was coated in this manner. Subsequently, the polyurethane foam was bonded to a surface made of fabric (PET fabric) to obtain a laminate. Each laminate was subjected to moist heat treatment for 200 hours, 400 hours, and 600 hours, respectively, at 85°C and 95% relative humidity. After treatment, each laminate was molded to a width of 25 mm and a length of 250 mm, left to stand at room temperature for 12 hours, and prepared as a test specimen for evaluation. The test specimens were subjected to a 180° peel test at 25°C using a material testing machine (Autograph precision universal tester, manufactured by Shimadzu Corporation), and the peel strength under each moist heat treatment condition was measured. The evaluation involved scoring the peel strength for processing times of 200 hours, 400 hours, and 600 hours using the following evaluation criteria. 3. The peel strength is 2.5 N / 25 mm or higher. 2. The peel strength is between 1.3 N / 25 mm and less than 2.5 N / 25 mm. 1. Peel strength is less than 1.3 N / 25 mm. Furthermore, the combined evaluation scores for peel strength at 200 hours, 400 hours, and 600 hours of moist heat treatment were used as the overall evaluation, and the results were assessed according to the following evaluation criteria. ○: The total evaluation score for 200 hours, 400 hours, and 600 hours is between 7 and 9 points. △: The total evaluation score for 200 hours, 400 hours, and 600 hours is between 4 and 6 points. ×: The sum of the evaluation scores for 200 hours, 400 hours, and 600 hours is 3 points or less.

[0058] [Table 1]

[0059] Furthermore, using the moisture-curing hot-melt adhesive compositions of Examples 1, 11, and 12, laminates were manufactured in the same manner as described above, except that the objects to be bonded were changed from urethane foam and fabric to the substrates (upper and lower layers) shown in Table 2. The moist heat aging properties and overall evaluation were then assessed. The evaluation results are shown in Table 2. In Table 2, "Fabric" refers to PET fabric. EL-45 is a urethane foam manufactured by Inoac Corporation.

[0060] [Table 2]

Claims

1. A moisture-curing hot-melt adhesive composition containing a urethane prepolymer, The aforementioned urethane prepolymer is obtained by reacting a polyol compound with a polyisocyanate compound. The amount of urethane bond in the aforementioned urethane prepolymer is 0.90 mol / kg or more. It further contains a carbodiimide compound, A moisture-curing hot-melt adhesive composition wherein the molecular weight or number-average molecular weight of the carbodiimide compound is 500 or more.

2. The moisture-curable hot-melt adhesive composition according to claim 1, characterized in that the polyol compound comprises a polyether polyol compound and a polyester polyol compound.

3. The moisture-curable hot-melt adhesive composition according to claim 1 or 2, characterized in that the amount of ester bonds in the urethane prepolymer is 6.00 mol / kg or less.

4. A moisture-curing hot-melt adhesive composition according to claim 1 or 2, characterized in that it is for use as an interior material for automobiles.

5. A first substrate and a second substrate are laminated with an adhesive layer in between. The adhesive layer is a cured product of the moisture-curing hot-melt adhesive composition described in claim 1 or 2. A laminate characterized in that the first substrate and the second substrate are each independently selected from the group consisting of foam, natural leather, synthetic leather, film, woven fabric and nonwoven fabric.

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