JP2021172769A - Reactive hot-melt adhesive composition - Google Patents

Abstract

To provide a reactive hot-melt adhesive composition capable of improving compatibility between urethane prepolymers during heating.SOLUTION: The reactive hot-melt adhesive composition contains a urethane prepolymer and at least either talc or mica. The urethane prepolymer contains a polymer chain containing polyol-derived structural units and a polyisocyanate-derived structural unit and has an isocyanate group as a terminal group of the polymer chain. The polyol-derived structural units include a polyester polyol-derived structural unit and at least either a polyether polyol-derived structural unit or a polybutadiene polyol-derived structural unit. The total content of the talc and the mica is 0.5 mass% or more based on the total amount of the reactive hot-melt adhesive composition.SELECTED DRAWING: None

Description

The present invention relates to reactive hot melt adhesive compositions.

Since the reactive hot melt adhesive composition is a solvent-free adhesive, it has a small load on the environment and the human body and can be adhered for a short time, so that it is an adhesive suitable for improving productivity. As the reactive hot melt adhesive, a urethane prepolymer having an isocyanate group at the end is mainly used.

Urethane prepolymers are synthesized, for example, by the reaction of polyols with isocyanates. Patent Documents 1 and 2 disclose urethane prepolymers containing polyester polyols, polyether polyols, and polybutadiene polyols as polyols.

International Publication No. 2017/187768 JP-A-2019-065220

The reactive hot melt adhesive composition containing a urethane prepolymer as a main component is used by heating it when it is applied. According to the studies by the present inventors, in particular, when a urethane prepolymer containing a polyester polyol, a polyether polyol, and a polybutadiene polyol is used as the polyol, the urethane prepolymers tend to be easily phase-separated from each other during heating. Was found. If the urethane prepolymers are phase-separated from each other during heating, unevenness may occur when used as an adhesive, or the adhesive properties may deteriorate.

Therefore, an object of the present invention is to provide a reactive hot melt adhesive composition capable of improving the compatibility between urethane prepolymers at the time of heating.

One aspect of the present invention relates to a reactive hot melt adhesive composition. The reactive hot melt adhesive composition contains a urethane prepolymer and at least one of talc or mica. The urethane prepolymer contains a polymerized chain containing a structural unit derived from a polyol and a structural unit derived from polyisocyanate, and has an isocyanate group as a terminal group of the polymerized chain. Structural units derived from polyols include at least one of structural units derived from polyester polyols and structural units derived from polyether polyols or polybutadiene polyols. The total content of talc and mica is 0.5% by mass or more based on the total amount of the reactive hot melt adhesive composition. According to such a reactive hot melt adhesive composition, it is possible to improve the compatibility between urethane prepolymers at the time of heating.

The total content of talc and mica may be 20% by mass or less based on the total amount of the reactive hot melt adhesive composition.

The total content of talc and mica may be 3 to 200 parts by mass, where 100 parts by mass is the total of the structural units derived from the polyether polyol and the structural units derived from the polybutadiene polyol.

According to the present invention, there is provided a reactive hot melt adhesive composition capable of improving the compatibility between urethane prepolymers at the time of heating.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

As used herein, "polypoly" means a compound having two or more hydroxy groups in the molecule.

As used herein, "polyisocyanate" means a compound having two or more isocyanate groups in the molecule.

<Definition>
In the present specification, the numerical range indicated by using "~" indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step may be replaced with the upper limit value or the lower limit value of the numerical range of another step. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, or both. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more. In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. means.

[Reactive hot melt adhesive composition]
The reactive hot melt adhesive composition of one embodiment (hereinafter, also referred to simply as "adhesive composition") contains a urethane prepolymer and at least one of talc or mica. In general, the reactive hot-melt adhesive composition is a moisture-curable type, and the urethane prepolymer is mainly polymerized by reacting with moisture in the air or moisture on the surface of the adherend. It can exhibit adhesive strength and the like.

According to the adhesive composition of the present embodiment, it is possible to suppress phase separation between urethane prepolymers during heating and improve compatibility. Further, since the adhesive composition of the present embodiment is a solvent-free adhesive, the load on the environment and the human body is small, and the adhesive composition can be adhered for a short time. Further, since the adhesive composition of the present embodiment is a one-component adhesive, it is easy to handle.

The urethane prepolymer contains a polymerized chain containing a structural unit derived from a polyol and a structural unit derived from polyisocyanate, and has an isocyanate group as a terminal group of the polymerized chain. Structural units derived from polyols include at least one of structural units derived from polyester polyols and structural units derived from polyether polyols or polybutadiene polyols. That is, the urethane prepolymer of the present embodiment is a reaction product of a polyester polyol and a polyol containing at least one of a polyether polyol or a polybutadiene polyol and a polyisocyanate, and has an isocyanate group as a terminal group of the reaction product. doing. By containing such a urethane prepolymer, the adhesive composition of the present embodiment can exhibit excellent adhesive strength after moisture curing.

The polyol giving a structural unit derived from a polyol is a polyester polyol giving a structural unit derived from a polyester polyol, and a polyether polyol giving a structural unit derived from a polyether polyol or a polybutadiene polyol giving a structural unit derived from a polybutadiene polyol. Includes at least one. The content of each structural unit corresponds to the amount of each polyol charged to give each structural unit. That is, the content of each structural unit can be adjusted by adjusting the amount of each polyol charged to give each structural unit.

The solidification time and viscosity of the adhesive composition can be adjusted by including the structural unit derived from the polyester polyol in the polymerized chain. As the polyester polyol giving a structural unit derived from the polyester polyol, a compound produced by a polycondensation reaction of a polyhydric alcohol and a polycarboxylic acid can be used. The polyester polyol has, for example, a polyhydric alcohol having 2 to 15 carbon atoms and 2 or 3 hydroxyl groups, and 2 to 14 carbon atoms (including carbon atoms in the carboxyl group), and has 2 to 2 carbon atoms. It may be a polycondensate with a polycarboxylic acid having 6 carboxyl groups. One type of polyester polyol may be used alone, or two or more types may be used in combination.

The polyester polyol may be a linear polyester diol formed from a diol and a dicarboxylic acid, or a branched polyester triol formed from a triol and a dicarboxylic acid. The branched polyester triol can also be obtained by reacting a diol with a tricarboxylic acid.

Examples of the polyhydric alcohol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol isomers, pentandiol isomers, hexanediol isomers, and 2,2-. Diol-1,3-propanediol, 2-methylpropanediol, 2,4,4-trimethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,4-cyclohexane Diols, aliphatic or alicyclic diols such as 1,4-cyclohexanedimethanol; aromatic diols such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resorcinol, hydroquinone and the like can be mentioned. One type of polyhydric alcohol may be used alone, or two or more types may be used in combination. Among these, an aliphatic diol is preferable, and an aliphatic diol having 2 to 6 carbon atoms is more preferable.

Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,2,4-benzenetricarboxylic acid; maleic acid, fumaric acid, aconitic acid, 1,2,3-propane. Fat groups such as tricarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, azelaic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid, 1,4-cyclohexanediene-1,2-dicarboxylic acid Alternatively, an alicyclic polycarboxylic acid and the like can be mentioned. One type of polycarboxylic acid may be used alone, or two or more types may be used in combination.

Instead of the above-mentioned polycarboxylic acid, a polycarboxylic acid derivative such as a carboxylic acid anhydride or a compound in which a part of the carboxyl group is esterified can also be used. Examples of the polycarboxylic acid derivative include dodecylmaleic acid and octadecenylmaleic acid.

The polyester polyol may be a crystalline polyester polyol or an amorphous polyester polyol. Here, the determination of crystallinity and amorphousness can be made in the state at 25 ° C. In the present specification, the crystalline polyester polyol means a polyester polyol which is crystalline at 25 ° C., and the amorphous polyester polyol means a polyester polyol which is amorphous at 25 ° C.

The number average molecular weight (Mn) of the crystalline polyester polyol is preferably 500 to 12000, more preferably 800 to 10000, and further preferably 1000 to 9000 from the viewpoint of improving waterproofness and adhesive strength. In the present specification, the number average molecular weight is a value measured by gel permeation chromatography (GPC) and converted into standard polystyrene. The GPC can be measured under the following conditions.
Columns: "Gelpack GLA130-S", "Gelpack GLA150-S" and "Gelpack GLA160-S" (manufactured by Hitachi Kasei Co., Ltd., packed column for HPLC)
Eluent: tetrahydrofuran Flow rate: 1.0 mL / min Column temperature: 40 ° C
Detector: RI

Examples of the amorphous polyester polyol include an amorphous polyester polyol having a number average molecular weight of 3000 or less and an amorphous polyester polyol having a number average molecular weight of 5000 or more. The Mn of the amorphous polyester polyol having a number average molecular weight of 3000 or less is preferably 500 to 3000, more preferably 1000 to 3000, from the viewpoint of improving the adhesive strength of the adhesive composition. The Mn of the amorphous polyester polyol having a number average molecular weight of 5000 or more is preferably 5000 to 9000, more preferably 7000 to 8000 from the viewpoint of improving impact resistance.

The content of the structural unit (polyester polyol) derived from the polyester polyol is preferably 60 to 90% by mass, more preferably 60 to 90% by mass, based on the total amount of the structural unit (polyol) derived from the polyol from the viewpoint of further improving the adhesive strength. It is 75 to 85% by mass.

The inclusion of structural units derived from the polyether polyol in the polymerized chain makes it possible to adjust the appropriate melt viscosity and open time after application of the adhesive composition, resulting in excellent workability, adhesiveness, waterproofness, and flexibility. Tends to be able to be given. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, ethylene oxide-modified polypropylene glycol and the like.

The number average molecular weight of the polyether polyol is preferably 500 to 6000, more preferably 700 to 5500, still more preferably 1000 to 5000, from the viewpoint of initial adhesive strength, adhesive strength after curing, and appropriate open time after coating. Is. One type of polyether polyol may be used alone, or two or more types may be used in combination.

The polybutadiene polyol is a compound having a polymer chain derived from butadiene and hydroxyl groups at both ends of the polymer chain. The polybutadiene polyol may be a liquid butadiene copolymer having a hydroxyl group at the molecular terminal. When the polymerized chain contains a structural unit derived from a polybutadiene polyol, it tends to be possible to improve the impact resistance and adhesiveness of the adhesive composition after moisture curing. The polybutadiene polyol may be a liquid butadiene copolymer having a hydroxyl group at the molecular terminal. The number average molecular weight of the polybutadiene polyol is preferably 1000 to 5000, more preferably 1000 to 4000, and even more preferably 1200 to 3000. When the number average molecular weight of the polybutadiene polyol is 1000 or more, the impact resistance is more likely to be improved, and when it is 5000 or less, the adhesiveness is less likely to decrease.

The total content of the structural unit derived from the polyether polyol (polyether polyol) and the structural unit derived from the polybutadiene polyol (polybutadiene polyol) makes it easy to adjust the adhesive composition to a low viscosity, and impact resistance after moisture curing. From the viewpoints that the properties can be more easily improved, the viscosity when the adhesive composition is heated and melted does not become too high, and the coating workability is improved, it is preferable to use the total amount of structural units (polyols) derived from the polyol as a reference. Is 5 to 40% by mass, more preferably 10 to 25% by mass.

The polyol may contain a polyol other than a polyester polyol, a polyether polyol, and a polybutadiene polyol. Examples of such polyols include polyether ester polyols, polyurethane polyols, polycarbonate polyols, polyolefin polyols and the like. Such a polyol may be used alone or in combination of two or more.

The polyisocyanate can be used without particular limitation as long as it is a compound having two or more isocyanate groups. The polyisocyanate may be, for example, a compound having two isocyanate groups (diisocyanate). Examples of the polyisocyanate include aromatic isocyanates such as diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate and p-phenylenedi isocyanate; alicyclic isocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate; hexamethylene diisocyanate and the like. The aliphatic isocyanate of the above can be mentioned. From the viewpoint of reactivity and adhesiveness, the polyisocyanate preferably contains an aromatic diisocyanate, and more preferably contains a diphenylmethane diisocyanate. One type of polyisocyanate may be used alone, or two or more types may be used in combination.

Urethane prepolymers can be synthesized by reacting polyols with polyisocyanates. At this time, the polyol includes a polyester polyol and at least one of a polyether polyol or a polybutadiene polyol.

The urethane prepolymer contains a polymer chain containing a structural unit derived from a polyol and a structural unit derived from polyisocyanate, and has an isocyanate group as a terminal group of the polymer chain. When synthesizing such a urethane prepolymer, the ratio of the isocyanate group (NCO) equivalent of polyisocyanate to the hydroxy group (OH) of the polyol (isocyanate group (NCO) equivalent of polyisocyanate / hydroxy group (OH) equivalent of polyol, NCO / OH) is greater than 1, preferably 1.3 to 3.0, and more preferably 1.5 to 2.0. When the NCO / OH ratio is 1.3 or more, the viscosity of the obtained urethane prepolymer is suppressed from becoming too high, and the workability tends to be improved easily. When the NCO / OH ratio is 3.0 or less, foaming is less likely to occur during the moisture curing reaction of the adhesive composition, and a decrease in adhesive strength tends to be easily suppressed.

The adhesive composition of the present embodiment contains at least one of talc and mica, and preferably contains talc. When the adhesive composition contains at least one of talc and mica, it is possible to suppress phase separation between urethane prepolymers during heating and improve compatibility. The reason why such a phenomenon occurs is not always clear, but when the reactive hot-melt adhesive composition contains at least one of talc and mica, tyxonicity is exhibited and urethane prepolymers are liable to be entangled with each other. It is thought that this is because.

Talc means, for example, hydrous magnesium silicate having a flaky (scaly) crystal structure. Examples of the talc include those having the composition represented by _{Mg 3} Si ₄ O ₁₀ (OH) _2. Talc preferably has a relatively small average particle size from the viewpoint of adhesive applicability. The average particle size of talc is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 10 μm or less. Here, the average particle size of talc may be the average particle size (D50 (median size of particle size distribution)) measured by the sedimentation method. One type of talc may be used alone, or two or more types may be used in combination.

When talc is crushed from rough stone, the manufacturing method is not particularly limited, and is an axial flow mill method, an annual mill method, a roll mill method, a ball mill method, a jet mill method, and a container rotary compression shear mill method. And so on. Further, it is preferable that the talc after crushing the rough stone is classified by various classifiers to make the distribution of the particle size uniform. The classifier is not particularly limited, and is an impactor type inertial force classifier (variable impactor, etc.), a Coanda effect utilization type inertial force classifier (elbow jet, etc.), and a centrifugal field classifier (multistage cyclone, microplex, dispersion). Separator, AccuCut, Turbo Classifier, Turboplex, Micron Separator, Super Separator, etc.).

Examples of commercially available talc products include trade names "FFR", "JA-13R", and "SW-special" manufactured by Asada Flour Milling Co., Ltd.

Mica means, for example, a silicate mineral having a layered crystal structure. Examples of mica include those having a composition represented by _{Namg 2.5} Si ₄ O ₁₀ F, KMg _2.5 Si ₄ O _{10 F, and the like.} From the viewpoint of adhesive applicability, mica preferably has a relatively small average particle size. The average particle size of mica is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 10 μm or less. Here, the average particle size of mica may be the average particle size (D50 (median size of particle size distribution)) measured by the sedimentation method. One type of mica may be used alone, or two or more types may be used in combination.

The total content of talc and mica is 0.5% by mass or more, preferably 0.7% by mass or more, more preferably 1% by mass or more, and further, based on the total amount of the reactive hot melt adhesive composition. It is preferably 2% by mass or more, and particularly preferably 3% by mass or more. When the total content of talc and mica is 0.5% by mass or more based on the total amount of the reactive hot melt adhesive composition, phase separation between urethane prepolymers is suppressed during heating to improve compatibility. It is possible to improve. The total content of talc and mica is not particularly limited, but is preferably 20% by mass or less, more preferably 18% by mass or less, still more preferably 15% by mass or less, based on the total amount of the reactive hot melt adhesive composition. Is.

The total content of talc and mica is 0.6 parts by mass or more, 0.8 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, and 3 parts by mass or more when the total amount of urethane prepolymer is 100 parts by mass. , Or 4 parts by mass or more, and may be 30 parts by mass or less, 25 parts by mass or less, or 20 parts by mass or less. When the total content of talc and mica is in such a range, phase separation between urethane prepolymers can be further suppressed during heating, and compatibility can be further improved.

The total content of talc and mica is preferably 3 to 200 parts by mass when the total of the structural units derived from the polyether polyol and the structural units derived from the polybutadiene polyol is 100 parts by mass. When the total content of talc and mica is in such a range, phase separation between urethane prepolymers can be further suppressed during heating, and compatibility can be further improved. The total content of talc and mica is 4 parts by mass or more, 5 parts by mass or more, and 7 parts by mass or more when the total of the structural units derived from the polyether polyol and the structural units derived from the polybutadiene polyol is 100 parts by mass. , Or 10 parts by mass or more, and may be 190 parts by mass or less, 180 parts by mass or less, 170 parts by mass or less, or 150 parts by mass or less. The content of the structural unit derived from the polyether polyol and the structural unit derived from the polybutadiene polyol corresponds to the amount of each polyol charged to give each structural unit.

The adhesive composition may further contain a catalyst from the viewpoint of accelerating the curing of the urethane prepolymer and developing higher adhesive strength. Examples of the catalyst include dibutyltin dilaurate, dibutylthioneoctate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine and the like.

The adhesive composition may further contain a thermoplastic polymer from the viewpoint of increasing the rubber elasticity of the adhesive layer to be formed and further improving the impact resistance. Examples of the thermoplastic polymer include polyurethane, ethylene-based copolymer, propylene-based copolymer, vinyl chloride-based copolymer, acrylic copolymer, and styrene-conjugated diene block copolymer.

The adhesive composition may further contain a tackifier resin from the viewpoint of imparting stronger adhesiveness to the formed adhesive layer. Examples of the tackifying resin include rosin resin, rosin ester resin, hydrogenated rosin ester resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, petroleum resin, hydrogenated petroleum resin, kumaron resin, ketone resin, and styrene resin. Examples thereof include modified styrene resin, xylene resin, and epoxy resin.

The adhesive composition may contain an appropriate amount of an antioxidant, a pigment, an ultraviolet absorber, a surfactant, a flame retardant, a filler and the like, if necessary.

In the adhesive composition, since the isocyanate group of the urethane prepolymer contained in the adhesive composition reacts with the moisture in the air or the moisture on the surface of the base material, for example, the temperature is 23 ° C. and the humidity is 50% for 24 hours or more. It can be cured by curing. By curing under such conditions, a cured product of the adhesive composition can be formed.

The method for producing the adhesive composition may include a step of reacting the polyol with the polyisocyanate to obtain a urethane prepolymer in the presence of talc, or reacting the polyol with the polyisocyanate to obtain the urethane prepolymer. May include a step of obtaining the urethane prepolymer and a step of mixing the urethane prepolymer and talc. The reaction temperature of the polyol and the polyisocyanate may be, for example, 85 to 120 ° C. The temperature at which the urethane prepolymer and talc are mixed may be, for example, 85 to 120 ° C. In the mixing, defoaming may be performed under reduced pressure.

The melt viscosity at 120 ° C. measured using a rotational viscometer of the adhesive composition may be 30 Pa · s or less, 25 Pa · s or less, or 20 Pa · s or less from the viewpoint of improving coatability. The lower limit of the melt viscosity at 120 ° C. is not particularly limited, but may be, for example, 1 Pa · s or more. In this specification, the melt viscosity of the adhesive composition at 120 ° C. means a value measured by the method described in Examples.

The adhesive composition of the present embodiment can suppress phase separation between urethane prepolymers during heating and improve compatibility even when the urethane prepolymer contains a polyol component having low compatibility. It will be possible. Further, since the adhesive composition of the present embodiment is a solvent-free adhesive, the load on the environment and the human body is small, and the adhesive composition can be adhered for a short time. Further, since the adhesive composition of the present embodiment is a one-component adhesive, it is easy to handle.

In the adhesive composition of the present embodiment, various adherends can be adhered to each other via a cured product of the adhesive composition. Examples of the adherend include metal base materials such as SUS and aluminum, and non-metal base materials such as polycarbonate, polyamide, polyetherimide, and glass.

[Adhesive and its manufacturing method]
The adhesive of one embodiment is the above-mentioned reactive hot melt adhesive that adheres the first adherend, the second adherend, the first adherend, and the second adherend to each other. A cured product of the composition is provided. Examples of the adhesive body of the present embodiment include semiconductor devices, non-sewn clothing, electronic devices, and the like.

As the first adherend and the second adherend, the same ones as those exemplified in the above-mentioned adherend can be exemplified.

The adhesive of the present embodiment has a step of melting the above-mentioned reactive hot melt adhesive composition and applying it to a first adherend to form an adhesive layer, and a second coating on the adhesive layer. It can be manufactured by a method including a step of arranging an adhesive and crimping a second adherend to obtain an adhesive precursor, and a step of curing an adhesive layer in the obtained adhesive precursor. can.

The temperature at which the adhesive composition is melted may be, for example, 80 to 180 ° C. The method of applying the adhesive composition to the first adherend is not particularly limited, and a known method can be appropriately applied.

Examples of the method of crimping the second adherend include a method of crimping using a pressure roll or the like.

The conditions for curing the adhesive layer in the adhesive precursor may be the same as the curing conditions for the adhesive composition described above.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto. Unless otherwise specified, parts are parts by mass.

(Examples 1 to 4, Comparative Examples 1 and 2)
80 parts of the polyol (polyester polyol A: 10 parts, polyester polyol B: 40 parts, polyester polyol C: 10 parts, polyester polyol D: 20 parts) and the mass parts shown in Table 1 which were previously dehydrated by a vacuum dryer. After uniformly mixing polypropylene glycol or polybutadiene polyol and talc, 25 parts of diphenylmethane diisocyanate was further added and mixed uniformly. Then, the obtained mixture was reacted at 110 ° C. for 1 hour, and further defoamed and stirred at 110 ° C. for 1 hour under reduced pressure to obtain an adhesive composition containing a urethane prepolymer and talc.

(Polyol)
-Polyester polyol A (crystalline polyester polyol obtained by reacting adipic acid and 1,6-hexanediol, number of hydroxyl groups: 2, Mn: 5000)
-Polyester polyol B (crystalline polyester polyol obtained by reacting adipic acid and ethylene glycol, number of hydroxyl groups: 2, Mn: 2000)
-Polyester polyol C (crystalline polyester polyol obtained by reacting sebacic acid with 1,6-hexanediol, number of hydroxyl groups: 2, Mn: 5000)
-Polyester polyol D (amorphous polyester polyol obtained by reacting isophthalic acid and neopentyl glycol, number of hydroxyl groups: 2, Mn: 2000)
-Polyether polyol (polypropylene glycol (number of hydroxyl groups: 2, Mn: 2000))
-Polybutadiene polyol (number of hydroxyl groups: 2, number average molecular weight: 1400, manufactured by Nippon Soda Corporation, trade name: G-1000)

(Polyisocyanate)
-Diphenylmethane diisocyanate (number of isocyanate groups: 2)

(talc)
-Talc A (average particle size: 3.9 μm or less, manufactured by Asada Flour Milling Co., Ltd., trade name "FFR")
-Talc B (ratio of particles with an average particle size of 45 μm or less: 90 to 95%, manufactured by Asada Flour Milling Co., Ltd., trade name "SW-Toku")

Each property of the adhesive composition obtained in Examples 1 to 4 and Comparative Examples 1 and 2 was evaluated as follows. The results are shown in Table 1.

(Measurement of melt viscosity)
The melt viscosity of the adhesive composition (sample amount: 15 g) at a rotor rotation speed of 50 rpm and 120 ° C. was measured using a No. 4 rotor with a TVB-25H type viscometer (manufactured by Toki Sangyo Co., Ltd.).

(Evaluation of compatibility)
The adhesive composition was added to the syringe, and the syringe was allowed to stand vertically and heated at 110 ° C. for 24 hours. Then, with the syringe standing vertically, the components existing in the upper part and the components existing in the lower part of the syringe were extracted, and IR measurement was performed on these components to confirm whether or not there was a change in the absorption spectrum. The case where there was no change in the absorption spectrum was evaluated as "A" as having good compatibility, and the case where there was a change in the absorption spectrum was evaluated as "B" as having poor compatibility.

The adhesive compositions of Examples 1 to 4 in which the total contents of talc and mica satisfy the predetermined conditions were excellent in compatibility between the urethane prepolymers at the time of heating. On the other hand, the adhesive compositions of Comparative Examples 1 and 2 in which the total content of talc and mica did not satisfy the predetermined conditions had insufficient compatibility between the urethane prepolymers at the time of heating. From these results, it was confirmed that the reactive hot melt adhesive composition of the present invention can improve the compatibility between urethane prepolymers at the time of heating.

Claims (3)

A urethane prepolymer containing a polymer chain containing a structural unit derived from a polyol and a structural unit derived from polyisocyanate and having an isocyanate group as a terminal group of the polymer chain.
With at least one of talc or mica,
Contains,
The structural unit derived from the polyol includes at least one of a structural unit derived from a polyester polyol and a structural unit derived from a polyether polyol or a structural unit derived from a polybutadiene polyol.
The total content of the talc and the mica is 0.5% by mass or more based on the total amount of the reactive hot melt adhesive composition.
Reactive hot melt adhesive composition. The total content of the talc and the mica is 20% by mass or less based on the total amount of the reactive hot melt adhesive composition.
The reactive hot melt adhesive composition according to claim 1. The total content of the talc and the mica is 3 to 200 parts by mass, where 100 parts by mass is the total of the structural units derived from the polyether polyol and the structural units derived from the polybutadiene polyol.
The reactive hot melt adhesive composition according to claim 1 or 2.