Reactive polyurethane hot melt adhesive compositions and articles

Abstract

The present invention relates to a reactive polyurethane hot melt adhesive composition and an article comprising an adhesive layer formed thereby. The reactive polyurethane hot melt adhesive composition is prepared from raw materials comprising the following components: component (A) comprising at least one polyether polyol; component (B) comprising at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2); component (C) comprising at least one acrylic resin (C1), wherein the acrylic resin (C1) comprises an active functional group that reacts with isocyanate groups and has a number average D90 particle size of 350 μm or less; and component (D) comprising at least one polyisocyanate, wherein the equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6.

Description

Technical Field

[0001] The present invention relates to a reactive polyurethane hot melt adhesive composition having good processability and particularly suitable for the field of electronic assembly. The present invention also relates to an article produced by applying the adhesive composition.

Background Art

[0002] Reactive polyurethane hot melt adhesives (referred to as "HMPUR" hereinafter, abbreviated as "hot melt adhesives") generally contain a urethane prepolymer terminated with isocyanate groups as a main component, are coated when heated to a molten state, have a specific initial tack, and produce stronger adhesion after reacting with moisture on the surface of air or a substrate or other active hydrogen-containing substances for curing. Reactive polyurethane hot melt adhesives have been widely used in various industries such as bookbinding, shoe and clothing manufacturing, wood panel processing, automotive interiors, and the electronics industry.

[0003] Reactive polyurethane hot melt adhesives have advantages such as solvent-free, good fluidity, high sizing efficiency, one-component without the need for glue preparation, rapid curing of the adhesive layer, low heat shrinkage rate, low density, uniform stress transmission, and easy adjustment of open time, and show good adhesion strength to metal materials such as stainless steel and aluminum, materials such as ABS plastic, polycarbonate (PC), and glass. Therefore, reactive polyurethane hot melt adhesives are particularly suitable for electronic assembly manufacturing lines that are developing towards miniaturization, weight reduction, and efficient high-density packaging.

[0004] Current electronic assembly manufacturing lines generally employ injection technology for high manufacturing efficiency, which uses piezoelectric injection dispensing valves to extrude hot melt adhesive at high speed and in small quantities to achieve precise dispensing or accurate filling. Precision piezoelectric injection dispensing valves typically have a small glue dispensing force and a small nozzle diameter (less than 0.5 mm, or even less than 0.2 mm). Therefore, there are high requirements for the viscosity, compatibility, and fluidity of the hot melt adhesive, and it needs to be extruded smoothly and maintain a consistent shape. However, in practice, problems often arise such as the hot melt adhesive not being able to be properly extruded from the piezoelectric injection dispensing valve, or the nozzle becoming clogged. Furthermore, during injection / dispensing, the hot melt adhesive is heated to a molten state, which makes it more likely to adhere to the nozzle of the piezoelectric injection system, leading to frequent shutdowns and cleaning, and significantly impacting manufacturing efficiency. In addition, in the assembly of precision electronic devices, the amount of adhesive used in each part is often small, and it is often necessary to use a single hot-melt adhesive (typically in 30ml syringe packaging) in a molten state for a long period of time. Therefore, good thermal stability is required for hot-melt adhesives.

[0005] Considering the above-mentioned problems with hot-melt adhesive dispensing in the current electronic assembly industry, there is a need for reactive polyurethane hot-melt adhesives with good dispensing performance and high thermal stability. [Overview of the project]

[0006] The present invention comprises the following components, namely, Component (A) containing at least one polyether polyol, Component (B) comprising at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2), Component (C) comprising at least one acrylic resin (C1), wherein the acrylic resin (C1) contains an active functional group that is reactive with an isocyanate group, and the acrylic resin (C1) has a number average D90 particle size of 350 μm or less, and Component (D) containing at least one type of polyisocyanate Includes, This invention relates to a reactive polyurethane hot-melt adhesive composition prepared from raw materials in which the equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6, preferably 1.5 to 5, and more preferably 1.7 to 3.

[0007] Preferably, the acrylic resin (C1) has a number-average D90 particle size of 250 μm or less, more preferably 210 μm or less, even more preferably in the range of 100 μm to 210 μm, and most preferably in the range of 120 μm to 200 μm.

[0008] Preferably, the acrylic resin (C1) has a number-average D90 particle size in the range of 160 to 200 μm.

[0009] Preferably, the acrylic resin (C1) has a glass transition temperature (Tg) of 30 to 110°C, preferably 40 to 80°C, and more preferably 45 to 58°C.

[0010] In one embodiment, the active functional group that reacts with the isocyanate group includes one or two of the hydroxyl group and the amino group.

[0011] In one embodiment, the acrylic resin (C1) has a hydroxyl value in the range of 1 to 10 mg KOH / g, preferably 2 to 10 mg KOH / g, and more preferably 4 to 10 mg KOH / g.

[0012] In one embodiment, the acrylic resin (C1) has a weight-average molecular weight in the range of 3,000 to 80,000 g / mol, preferably 5,000 to 60,000 g / mol, and more preferably 5,000 to 50,000 g / mol.

[0013] In one embodiment, the content of the acrylic resin (C1) is in the range of 3 to 25% by weight, preferably 5 to 20% by weight, and more preferably 5 to 15% by weight, based on the total weight of components (A) to (D).

[0014] In one embodiment, component (C) further comprises at least one acrylic resin (C2), the acrylic resin (C2) substantially does not contain any active functional groups that are reactive with isocyanate groups.

[0015] In one embodiment, the weight ratio of crystalline polyester polyol (B1) to amorphous polyester polyol (B2) is in the range of 1:9 to 9:1, preferably 1:9 to 5:1, more preferably 1:9 to 3:1, and most preferably 1:3 to 3:1.

[0016] In one embodiment, components (A), (B), and (C) are substantially free of aromatic compounds.

[0017] In one embodiment, at least one polyisocyanate is an aromatic polyisocyanate.

[0018] In one embodiment, components (A), (B), (C), and (D) each comprise at least one partially or entirely bio-based material.

[0019] In one embodiment, the composition has a bio-based content of 10% or more, preferably 30% or more, and more preferably 40% or more, the bio-based content being determined according to ASTM D6866.

[0020] In one embodiment, the composition has a viscosity at 100°C in the range of 1,500 to 10,000 mPa.s, preferably in the range of 1,500 to 8,000 mPa.s, and more preferably in the range of 1,500 to 5,000 mPa.s.

[0021] The present invention further provides an article including a first substrate and an adhesive layer disposed on the first substrate, the adhesive layer being formed by curing the reactive polyurethane hot melt adhesive composition.

[0022] In one embodiment, the adhesive layer has a thickness in the range of 0.01 to 2 mm, preferably in the range of 0.05 to 1 mm, more preferably in the range of 0.1 to 0.5 mm.

[0023] In one embodiment, the adhesive layer is formed by coating the reactive polyurethane hot melt adhesive composition on the first substrate by a piezoelectric injection system and curing the resulting product.

[0024] The present invention further provides the use of an acrylic resin in the reactive polyurethane hot melt adhesive composition according to the present invention for improving dispensing performance, wherein the acrylic resin is the acrylic resin (C1) according to the present invention.

[0025] In one embodiment, the composition has a total number of nozzle blockages of less than 5, preferably less than 3.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] In the present invention, the "polyester polyol" includes products obtained by the condensation reaction of polycaprolactone polyol, polycarbonate polyol, and a polyhydroxy compound and a polybasic acid. In the case of the reactants in the above condensation reaction, the polyhydroxy compound may be, for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, etc. These can be used alone or in combination of two or more. The polybasic acid is preferably a dibasic acid, and may be, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,12 - decanedicarboxylic acid, etc. The above polycaprolactone polyol can be obtained by the reaction of a compound having a hydroxyl group and ε - caprolactone. The polyester polyol can be divided into aliphatic polyester polyol and aromatic polyester polyol depending on whether it contains a benzene ring structure or not.

[0027] In the present invention, the "crystalline polyester polyol" refers to a polyester polyol having a crystallinity exceeding 10%, including semi - crystalline polyester polyol. The "non - crystalline polyester polyol" refers to a polyester polyol having a crystallinity less than 10%, including amorphous polyester polyol. The "crystallinity" refers to the ratio of the crystalline region in the polymer, expressed as a percentage. In the present invention, the crystallinity is determined by the wide - angle X - ray diffraction (WAXD) method. Specifically, based on the integration of the WAXD diffraction spectrum, the crystallinity (%) is equal to 100% multiplied by the ratio of the crystalline diffraction peak area to the sum of the crystalline diffraction peak area and the non - crystalline diffraction peak area. The crystallinity is determined by a Bruker D8 ADVANCE DaVinci X - ray diffractometer in the present invention.

[0028] In this invention, "number-average D90 particle size" refers to the particle size corresponding to 90% of the cumulative particle size distribution, and the number of particles with a particle size less than D90 accounts for 90% of the total sample. The number-average D90 particle size as specified herein is determined using a Microtrac S3500 laser particle size analyzer that utilizes a wet method (ethanol as a carrier).

[0029] In this invention, viscosity is determined at 110°C using a DVT-II type Brookfield viscometer with a 27# rotor.

[0030] The following describes in detail an article containing a reactive polyurethane hot-melt adhesive composition and an adhesive layer formed therefrom, according to an embodiment.

[0031] In one embodiment, the present invention relates to a reactive polyurethane hot melt adhesive composition prepared from raw materials comprising the following components: component (A) comprising at least one polyether polyol; component (B) comprising at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2); component (C) comprising at least one acrylic resin (C1), wherein the acrylic resin (C1) comprises an active functional group that is reactive with isocyanate groups, and the acrylic resin (C1) has a number average D90 particle size of 350 μm or less; and component (D) comprising at least one polyisocyanate, wherein the equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6, preferably 1.5 to 5, more preferably 1.7 to 3.

[0032] Preferably, the present invention relates to a reactive polyurethane hot melt adhesive composition prepared from raw materials comprising the following components: component (A) comprising at least one polyether polyol; component (B) comprising at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2); component (C) comprising at least one acrylic resin (C1), wherein the acrylic resin (C1) comprises an active functional group that is reactive with isocyanate groups, and the acrylic resin (C1) has a number average D90 particle size of 210 μm or less, preferably in the range of 100 μm to 210 μm, more preferably in the range of 120 μm to 200 μm; and component (D) comprising at least one polyisocyanate, wherein the equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6, preferably 1.5 to 5, more preferably 1.7 to 3.

[0033] Surprisingly, the inventors have found that when preparing a reactive polyurethane hot-melt adhesive composition, using a combination of polyether polyol, crystalline polyester polyol, amorphous polyester polyol, acrylic resin containing active functional groups within a specific particle size range, and polyisocyanate enables a reactive polyurethane hot-melt adhesive with excellent initial tackiness, adhesive strength, and thermal stability, and more importantly, excellent dispensing performance. For example, when using a piezoelectric injection system for spraying / dispensing, dispensing is smooth, the nozzle is less likely to clog with the adhesive, and the hot-melt adhesive is suitable for use in electronics industry assembly lines.

[0034] In the present invention, component (A) comprises at least one polyether polyol. The polyether polyol comprises any polyether polyol available in the art. In one embodiment, the polyether polyol comprises a polymer or oligomer formed from one or more monomers selected from ethylene oxide, propylene oxide, 1,2-epoxybutane, 1,4-epoxybutane and mixtures thereof, or a polymer or oligomer formed from alkylene glycol. The alkylene glycol generally has three or more carbon atoms and is, for example, propylene glycol or butanediol. From the viewpoint of the desired initial tackiness and adhesive strength of the hot melt adhesive, the number-average molecular weight of the polyether polyol is preferably in the range of 200 to 8,000 g / mol, more preferably in the range of 500 to 5,000 g / mol, even more preferably in the range of 700 to 3,000 g / mol, more favorably in the range of 1,500 to 2,500 g / mol, particularly 2,000 g / mol. Preferably, the polyether polyol contains a homopolymer of propylene oxide having a number-average molecular weight in the range of 500 to 5,000 g / mol. The polyether polyol can be a commercially available product such as the Voranol series from Dow Chemical Company or the Wanol series from Wanhua.

[0035] Component (A) may contain one or more polyether polyols, for example, two polyether polyols having different number average molecular weights.

[0036] The content of component (A) is preferably in the range of 15 to 35% by weight, more preferably in the range of 18 to 30% by weight, even more preferably in the range of 20 to 29% by weight, and more favorably in the range of 23 to 29% by weight, based on the total weight of components (A) to (D).

[0037] In the present invention, component (B) comprises at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2).

[0038] Crystalline polyester polyol (B1) includes any crystalline polyester polyol available in the art. In one embodiment, polyester polyol (B1) generally has a melting point in the range of 40°C to 120°C, preferably 45°C to 100°C, and more preferably 48°C to 80°C. In one embodiment, polyester polyol (B1) is prepared by a condensation reaction of at least one diol selected from butanediol, hexanediol, octanediol and decanediol with at least one diacid selected from adipic acid, sebacic acid, dodecanediic acid and terephthalic acid. The number-average molecular weight of the polyester polyol (B1) is preferably in the range of 1,500 to 10,000 g / mol, more preferably in the range of 1,500 to 8,000 g / mol, even more preferably in the range of 1,500 to 6,000 g / mol, more favorably in the range of 1,500 to 4,000 g / mol, and particularly in the range of 1,500 to 3,500 g / mol.

[0039] Component (B) may contain one or more crystalline polyester polyols (B1). Examples of commercially available crystalline polyester polyols (B1) include Dynacoll(R) 7360, 7361, 7380, and 7750 from Evonik, the Wanthanol series from Yantai Wanhua Corporation, NL2000D from Mitsubishi, and the Capa series from Perstorp.

[0040] Polyester polyol (B2) is an amorphous polyester polyol. Amorphous polyester polyols have a crystallinity of less than 10%, have no melting point, and include, but are not limited to, amorphous polyester polyols. Amorphous polyester polyols include any amorphous polyester polyol available in the art. In one embodiment, amorphous polyester polyols are obtained by reacting a carboxylic acid (aromatic carboxylic acid and / or aliphatic carboxylic acid) with an aliphatic polyol, preferably by reacting an aliphatic diol with an aromatic dicarboxylic acid. In another embodiment, amorphous polyester polyols include amorphous polycarbonate polyols. The number-average molecular weight of the polyester polyol (B2) is preferably in the range of 1,000 to 8,000 g / mol, more preferably in the range of 1,500 to 7,000 g / mol, even more preferably in the range of 1,600 to 6,000 g / mol, more favorably in the range of 1,800 to 4,000 g / mol, particularly in the range of 1,900 to 3,000 g / mol, and especially 2,000 g / mol.

[0041] Component (B) may contain one or more amorphous polyester polyols (B2). Examples of commercially available amorphous polyester polyols (B2) include Evonik's Dynacoll(R) 7110, 7130, and 7140, Cargill / Croda's Priplast series, Covestro's Desmophen series amorphous polyester polyols, and Stepan's Stepapol series.

[0042] Preferably, component (B) is composed of at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2).

[0043] The content of component (B) is preferably in the range of 15 to 60% by weight, more preferably in the range of 25 to 55% by weight, and more favorably in the range of 35 to 52% by weight, based on the total weight of components (A) to (D).

[0044] In component (B), the weight ratio of crystalline polyester polyol (B1) to amorphous polyester polyol (B2) is not particularly limited. Preferably, the weight ratio of crystalline polyester polyol (B1) to amorphous polyester polyol (B2) is in the range of 1:9 to 9:1, more preferably in the range of 1:9 to 5:1, even more preferably in the range of 1:9 to 3:1, and most preferably in the range of 1:3 to 3:1, for example, 1:4 to 4:1, 1:3 to 3:1, or 1:2 to 2:1.

[0045] In the present invention, component (C) comprises at least one acrylic resin (C1). The acrylic resin (C1) contains an active functional group that is reactive with an isocyanate group, and its number average D90 particle size is 350 μm or less. Preferably, its number average D90 particle size is 250 μm or less, preferably 210 μm or less, more preferably in the range of 100 to 210 μm, most preferably in the range of 120 to 200 μm, and most preferably in the range of 160 to 200 μm. The acrylic resin (C1) has, for example, a number average D90 particle size of 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, or 210 μm.

[0046] Examples of active functional groups that react with isocyanate groups include hydroxyl groups, amino groups, and other functional groups having active hydrogen. Preferably, the active functional group that reacts with isocyanate groups includes one or two of hydroxyl groups and amino groups, and more preferably includes hydroxyl groups; that is, the acrylic resin (C1) contains hydroxyl functional groups. When preparing the adhesive composition of the present invention, the active functional groups contained in the acrylic resin (C1) may react with the polyisocyanate in component (D) to form a prepolymer having a urethane structure, but it cannot be guaranteed that all acrylic resins (C1) will form a prepolymer having a urethane structure.

[0047] The acrylic resin (C1) exists in the form of extremely small particles or powder. The shape of the particles is not particularly limited and can be spherical or elliptical, for example.

[0048] The inventors have found that when preparing a reactive polyurethane hot-melt adhesive composition, adding an acrylic resin containing active functional groups and having a number-average D90 particle size within a specific range significantly improves the dispensing / spraying performance of the composition. For example, dispensing becomes smoother, nozzle clogging is less likely, and nozzle clogging is less likely to occur. While not bound by theory, the inventors believe that an acrylic resin satisfying the above two requirements is well compatible with other components in the system, and therefore the prepared adhesive composition has excellent fluidity and processability.

[0049] Preferably, the acrylic resin (C1) has a hydroxyl value in the range of 1 to 10 mg KOH / g, more preferably 2 to 10 mg KOH / g, and even more preferably 4 to 10 mg KOH / g, for example, 5, 6, 7, 8, 9, 10 mg KOH / g.

[0050] Acrylic resin (C1) can be obtained by polymerizing a hydroxyl group-containing (meth)acrylic compound as a constituent monomer with optionally other (meth)acrylic compounds. In the present invention, "(meth)acrylic compound" refers to either or both a methacrylic compound and an acrylic compound. Examples of hydroxyl group-containing (meth)acrylic compounds include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of other (meth)acrylic compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylic acid.

[0051] The acrylic resin (C1) preferably has a weight-average molecular weight in the range of 3,000 to 80,000 g / mol, more preferably 5,000 to 60,000 g / mol, and even more preferably 5,000 to 50,000 g / mol, for example, 15,000, 25,000, 30,000, 35,000, 40,000, and 45,000 g / mol.

[0052] The content of acrylic resin (C1) is preferably in the range of 3 to 25% by weight, more preferably 5 to 20% by weight, and even more preferably 5% to 15% by weight, based on the total weight of components (A) to (D).

[0053] The acrylic resin (C1) preferably has a glass transition temperature (Tg) of 30 to 110°C, preferably 40 to 80°C, more preferably 45 to 58°C, for example, 45, 50, 53, 55, 56, 57, 58, 59, 60, 62, 65, 68, 70, 72, 75, 78, and 80°C. Acrylic resin (C1) having a preferred Tg is beneficial for compositions with good compatibility. The glass transition temperature can be tested by conventional methods in the art, for example, differential scanning calorimetry (DSC) using a heating rate of about 10°C / min.

[0054] In some embodiments, the acrylic resin has a number-average D90 particle size of 350 μm or less and a Tg of 30 to 110°C.

[0055] In some embodiments, the acrylic resin has a number-average D90 particle size of 250 μm or less and a Tg of 30 to 110°C.

[0056] In some embodiments, the acrylic resin has a number-average D90 particle size of 210 μm or less and a Tg of 30 to 110°C.

[0057] In some embodiments, the acrylic resin has a number-average D90 particle size in the range of 100 μm to 210 μm and a Tg of 30 to 110°C.

[0058] In some embodiments, the acrylic resin has a number-average D90 particle size in the range of 120 μm to 210 μm and a Tg of 30 to 110°C.

[0059] In some embodiments, the acrylic resin has a number-average D90 particle size in the range of 160 μm to 210 μm and a Tg of 30 to 110°C.

[0060] In some embodiments, the acrylic resin has a number-average D90 particle size of 350 μm or less and a Tg of 40 to 80°C.

[0061] In some embodiments, the acrylic resin has a number-average D90 particle size of 250 μm or less and a Tg of 40 to 80°C.

[0062] In some embodiments, the acrylic resin has a number-average D90 particle size of 210 μm or less and a Tg of 40 to 80°C.

[0063] In some embodiments, the acrylic resin has a number-average D90 particle size of 100 μm to 210 μm and a Tg of 40 to 80°C.

[0064] In some embodiments, the acrylic resin has a number-average D90 particle size of 120 μm to 200 μm and a Tg of 40 to 80°C.

[0065] In some embodiments, the acrylic resin has a number-average D90 particle size in the range of 160 μm to 210 μm and a Tg of 40 to 80°C.

[0066] In some embodiments, the acrylic resin has a number-average D90 particle size of 350 μm or less and a Tg of 45 to 58°C.

[0067] In some embodiments, the acrylic resin has a number-average D90 particle size of 250 μm or less and a Tg of 45 to 58°C.

[0068] In some embodiments, the acrylic resin has a number-average D90 particle size of 210 μm or less and a Tg of 45 to 58°C.

[0069] In some embodiments, the acrylic resin has a number-average D90 particle size of 100 μm to 210 μm and a Tg of 45 to 58°C.

[0070] In some embodiments, the acrylic resin has a number-average D90 particle size of 120 μm to 200 μm and a Tg of 45 to 58°C.

[0071] In some embodiments, the acrylic resin has a number-average D90 particle size in the range of 160 μm to 210 μm and a Tg of 45 to 58°C.

[0072] Component (C) may further comprise at least one acrylic resin (C2) that is substantially free of active functional groups that react with isocyanate groups. The expression "substantially free" means that the acrylic resin (C2) contains less than 5% by weight, preferably less than 3% by weight, and more preferably less than 1% by weight, of active functional groups that react with isocyanate groups. The difference between acrylic resin (C1) and (C2) is whether or not they contain active functional groups that react with isocyanate groups. When preparing the adhesive composition of the present invention, the acrylic resin (C2) does not react with the polyisocyanate in component (D), and therefore, the acrylic resin (C2) is present in the resulting composition. The weight-average molecular weight of the acrylic resin (C2) is not particularly limited, and an acrylic resin (C2) with an appropriate molecular weight can generally be selected so that the desired viscosity is obtained from the prepared composition.

[0073] Preferably, component (C) may consist of acrylic resin (C1), or acrylic resin (C1) and acrylic resin (C2).

[0074] When component (C) contains acrylic resin (C1) and acrylic resin (C2), the ratio of acrylic resin (C1) to acrylic resin (C2) is not particularly limited and may be in the range of 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, or 4:6 to 6:4 by weight.

[0075] In the present invention, component (D) comprises at least one polyisocyanate. The polyisocyanate comprises isocyanate compounds having two or more isocyanate groups (-NCO), and oligomers or polymers formed therefrom, such as trimers. The polyisocyanate may be aliphatic, aromatic, or a mixture thereof. The polyisocyanate may also contain other substituents that do not significantly adversely affect the performance of the composition of the present invention, such as viscosity or adhesion. Examples of polyisocyanates include diphenylmethane diisocyanate compounds (MDI) and their isomers, diphenylmethane 4,4'-diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, other oligomeric methylene isocyanates; toluene diisocyanate compounds (TDI) and their isomers, isophorone diisocyanates, and hydrogenated aromatic diisocyanates. At least one polyisocyanate in component (D) is preferably an aromatic polyisocyanate, more preferably a linear aromatic isocyanate compound. Although not bound by theory, the inventors believe that using an aromatic polyisocyanate in component (D) can provide the adhesive composition of the present invention with good adhesive strength and heat resistance.

[0076] The content of component (D) is preferably in the range of 12 to 30% by weight, more preferably 15 to 25% by weight, even more preferably 16 to 23% by weight, and more favorably 17 to 20% by weight, based on the total weight of components (A) to (D).

[0077] In a method for preparing a composition of the present invention using components (A) to (D), the hydroxyl groups and / or other active functional groups in components (A) to (C) react with the isocyanate groups in component (D) to produce a prepolymer having a urethane structure. In components (A) to (D) of the present invention, in order to provide an adhesive composition containing isocyanate groups, the equivalent ratio of isocyanate groups to hydroxyl groups (NCO / OH) is 1.2 to 6, preferably 1.5 to 5, and more preferably 1.7 to 3. In some embodiments of the present invention, the adhesive composition has a free NCO content of 3% to 4%, preferably 3.1% to 3.6%. Free NCO refers to the isocyanate groups remaining after components (A) to (D) are mixed and the isocyanate groups react with hydroxyl groups in an equivalent ratio of 1:1. "Free NCO content" refers to the weight percentage of isocyanate groups present in the adhesive composition, based on 100% by weight of the total weight of the composition, and can be used to characterize the effectiveness of the reactive polyurethane hot melt adhesive. A higher free NCO content means that the adhesive composition of the present invention has a higher degree of crosslinking after curing, and therefore has better heat resistance and creep resistance.

[0078] According to one embodiment of the present invention, components (A), (B), and (C) for preparing the reactive polyurethane hot-melt adhesive composition of the present invention are substantially free of aromatic compounds. The expression "substantially free of aromatic compounds" means that the content of aromatic compounds in components (A), (B), and (C) is less than 5% by weight, preferably less than 3% by weight, more preferably less than 1% by weight, and particularly 0% by weight. Components (A), (B), and (C) preferably use aliphatic or alicyclic compounds, i.e., they are completely free of aromatic compounds. Although not bound by theory, the inventors believe that the absence of aromatic compounds in components (A), (B), and (C) enables the adhesive composition of the present invention to have good flexibility and wettability.

[0079] According to one embodiment of the present invention, components (A), (B), and (C) for preparing the reactive polyurethane hot-melt adhesive composition of the present invention are substantially free of aromatic compounds, and component (D) contains at least one aromatic polyisocyanate.

[0080] In addition to the product obtained by mixing components (A) to (D), the reactive polyurethane hot-melt adhesive composition of the present invention may contain the following optional components, namely catalysts, antioxidants, tackifiers, plasticizers, stabilizers, UV absorbers, fillers, dyes, pigments, fluorescent agents, deodorants, adhesion promoters (e.g., silane coupling agents), surfactants, defoamers, waxes, and thermoplastic resins, provided that the presence of the optional components does not adversely affect the physical properties of the adhesive composition of the present invention, such as initial tackiness and thermal stability. Examples of catalysts, but not limited to, include nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine; metal salts such as potassium acetate, zinc stearate, and tin octanoate; and organometallic compounds such as dibutyltin dilaurate. Preferably, the catalyst comprises ether and morpholine functional groups, such as 2,2-dimorpholinyl ethyl ether, di(2,6-dimethylmorpholinyl ethyl) ether, and 4,4'-(oxy-di-2,1-ethanediyl)bismorpholine (DMDEE). The amount of catalyst added is in the range of 0.01 to 2% by weight, based on the total weight of the adhesive composition. The addition of antioxidants can protect the adhesive composition from decomposition induced, for example, by heat, light, or residual catalyst in the raw materials. Antioxidants may include hindered phenol antioxidants, phosphite antioxidants, thioether antioxidants, etc. Examples of commercially available antioxidants include Irganox 565, 1010, and 1076 from Ciba Corporation. Examples of fillers include talc, clay, silica and their processed forms, carbon black, and mica.

[0081] According to one embodiment of the present invention, components (A), (B), (C), and (D) for preparing the reactive polyurethane hot-melt adhesive composition of the present invention include at least one partially or completely bio-based material. Partially or completely bio-based material refers to a material having a bio-based content of 0.1% or more, and the bio-based content of each component is determined according to ASTM D6866. Currently, an increasing number of bio-based raw materials are available on the market. For example, bio-based polyether polyols include ECOPROL H500, H1000, and H2000 from SK Corporation; bio-based crystalline polyester polyols include Dynacoll Terra from Evonik Corporation and the Benebiol series from Mitshubishi Chem; bio-based amorphous polyester polyols include Priplast 3238 and Priplast 1838 from Cargill Corporation; and bio-based polyisocyanates include Desmodur(R)eco N7300 from Covestro Corporation. For example, the bio-based crystalline polyester polyol used in the present invention has a bio-based content of 80%, preferably 90% or more. The bio-based amorphous polyester polyol used in the present invention has a bio-based content of 80%, preferably 90% or more.

[0082] The reactive polyurethane hot-melt adhesive composition of the present invention may be bio-based. Preferably, the bio-based content is 10% or more, preferably 30% or more, more preferably 40% or more, for example 30%, 35%, 40%, 45%, or 50%, and the bio-based content is determined according to ASTM D6866. More specifically, the bio-based content of each component is determined according to ASTM D6866, and the bio-based content of the composition is the sum of (bio-based content of all components × weight percentage of components in the composition).

[0083] The reactive polyurethane hot-melt adhesive composition of the present invention typically has a viscosity suitable for coating. Specifically, its viscosity at 110°C is in the range of 1,500 to 10,000 mPa.s, preferably in the range of 1,500 to 8,000 mPa.s, and more preferably in the range of 1,500 to 5,000 mPa.s, and the viscosity is determined using a DVT-II type Brookfield viscometer utilizing a 27# rotor.

[0084] Preferably, the reactive polyurethane hot melt adhesive composition comprises the following components: Component (A) as defined above, in an amount of 15-35% by weight, Component (B) as defined above, in an amount of 15-60% by weight, 3-25% by weight of the above-defined component (C1), Component (D) as defined above, in an amount of 12-30% by weight, Includes, The equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6. It is prepared according to the raw materials.

[0085] More preferably, the reactive polyurethane hot melt adhesive composition comprises the following components: Component (A) as defined above, in an amount of 18-30% by weight, Component (B) as defined above, in an amount of 25-55% by weight, 5-20% by weight of the above-defined component (C1), Component (D) as defined above, in an amount of 15-25% by weight, Includes, The equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6. It is prepared according to the raw materials.

[0086] More preferably, the reactive polyurethane hot melt adhesive composition comprises the following components: Component (A) as defined above, in an amount of 20-29% by weight, Component (B) as defined above, in an amount of 35-52% by weight, 5-15% by weight of the above-defined component (C1), Component (D) as defined above, in an amount of 16-23% by weight, Includes, The equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6. It is prepared according to the raw materials.

[0087] Regarding the preparation of the reactive polyurethane hot-melt adhesive composition of the present invention, in one embodiment, this can be done as follows: pre-mix components (A), (B), and (C), dehydrate them, add component (D) while heating and react, and then add optional additives and fillers to prepare the adhesive composition. The adhesive composition may be packaged in a moisture-proof container such as a high-temperature heat-resistant plastic needle tube. The above reaction method is usually carried out under solvent-free conditions, but it can also be carried out in an organic solvent (e.g., ethyl acetate and toluene). When an organic solvent is used, the preparation method further includes a step of removing the organic solvent so that the prepared prepolymer having a urethane structure does not contain the organic solvent.

[0088] The method for applying the reactive polyurethane hot-melt adhesive composition of the present invention is as follows: first, heating and melting the reactive polyurethane hot-melt adhesive composition of the present invention in a temperature range of 50 to 130°C to coat a first substrate; adhering a second substrate to the composition; and, if necessary, selecting whether or not to apply pressure to bond the first and second substrates. The coating of the adhesive composition of the present invention on the first substrate may be performed on a flat surface or in a fine groove. The coating may be performed using, for example, a roller coater, spray coater, T-die coater, blade coater or comma coater, or by spraying, inkjet printing, screen printing or offset printing. The composition of the present invention is particularly suitable for coating using a piezoelectric injection system. When coating, the moisture-curable polyurethane hot-melt resin composition of the present invention may be formed continuously or discontinuously on constituent elements of various shapes, such as dots, lines, triangles, squares, circles or curves.

[0089] The reactive polyurethane hot-melt adhesive composition of the present invention achieves excellent coating performance while possessing good initial tackiness (green strength, adhesive strength before curing), adhesive strength after curing, aging resistance, heat resistance, and excellent open time. In particular, the reactive polyurethane hot-melt adhesive composition of the present invention is dispensed smoothly during spray coating, is less likely to clog nozzles, and nozzle clogging is less likely to occur, making it especially suitable for use in precision assembly lines in the electronics industry and contributing to improved manufacturing efficiency.

[0090] Another aspect of the present invention provides an article comprising a first substrate and an adhesive layer on the first substrate formed by curing a reactive polyurethane hot-melt adhesive composition of the present invention. In one embodiment, the article comprises a first substrate, a second substrate, and an adhesive layer between the first and second substrates formed by curing a reactive polyurethane hot-melt adhesive composition of the present invention. The first and second substrates are each selected from a variety of materials such as metals, glass, inorganic building materials, plastics, fibers, and composite materials. The substrates may be subjected to corona treatment, plasma treatment, or priming treatment, as desired. The thickness of the adhesive layer can be set according to the requirements of a particular application. In one embodiment, the adhesive layer is coated onto the first substrate by spraying / dispensing the reactive polyurethane hot-melt adhesive composition of the present invention. The adhesive layer preferably has a thickness in the range of 0.01 to 2 mm, more preferably in the range of 0.05 to 1 mm, and even more preferably in the range of 0.1 to 0.5 mm. In one embodiment, the adhesive layer is formed by coating a first substrate with the reactive polyurethane hot-melt adhesive composition of the present invention using a piezoelectric injection system, and then curing it. Examples of articles of the present invention, but not limited to, include various electronic devices such as mobile phones, computers, headphones, televisions, cameras, and automotive electronic components.

[0091] A further aspect of the present invention provides the use of the acrylic resin (C1) according to the present invention in a reactive polyurethane hot-melt adhesive composition according to the present invention to improve dispensing performance.

[0092] Dispensing performance could be evaluated by a nozzle clogging test. The nozzle clogging test was performed as follows: A VERMES MDC3200 glue dispenser was used for continuous glue dispensing, and a nozzle with a diameter of 0.1 mm was selected. Glue dispensing was performed for 5 seconds. A 5-second interval was then observed, followed by another 5-second glue dispensing. This cycle was repeated until 30 ml of glue was dispensed in approximately 3 hours. Nozzle clogging was observed every 10 minutes, and the number of nozzle cloggings within 3 hours was recorded. Five different glues were used for glue dispensing for each sample type, and the total number of nozzle cloggings was recorded. The reactive polyurethane hot-melt adhesive composition of the present invention has a total number of nozzle cloggings of less than 5, preferably less than 3.

[0093] The present invention will be described in more detail below with reference to examples and comparative examples. The following examples are not intended to limit the scope of the present invention. [Examples]

[0094] Test method Viscosity (mPa·s): 27# Measured at 110°C using a DVT-II type Brookfield viscometer with a rotor.

[0095] Initial tackiness (MPa) (also known as green strength): Two 100mm x 25mm x 6mm polycarbonate sheets were prepared as substrates. Two adhesive lines were coated in the center of one polycarbonate sheet at 11mm intervals parallel to the length of the substrate, and limiting steel wires with a diameter of 0.2mm were placed on both sides of the two adhesive lines. The other polycarbonate sheet was then pressed onto the first polycarbonate sheet at a 90-degree angle to form a cross-shaped laminate, and the laminates were pressed together so that each adhesive strip after pressing was 25mm long and 1mm wide. The laminate was placed in an environment of 23°C and 50% relative humidity for 20 minutes, and then a cross tensile test was performed. Each sample was tested 5 times and the average value was taken.

[0096] Adhesion strength (MPa): Following the same method as the initial tackiness test, cross-shaped laminates were prepared and left in an environment of 23°C and 50% relative humidity for 24 hours, followed by a cross tensile test. Each sample was tested five times and the average value was taken.

[0097] Thermal stability (%): At 110°C, the sample was placed in a DVT-II Brookfield viscometer (27# rotor). The first occurrence of a plateau value was recorded. Subsequently, the viscosity value after 6 hours was recorded. The viscosity growth rate was calculated and expressed as a percentage.

[0098] Shape: A VERMES MDC3200 glue dispenser was used for continuous glue dispensing, with a 0.1 mm diameter nozzle selected for dispensing. The shape of the dispensed glue line was observed. If the shape was stable and maintained without scattering, it was recorded as "Pass"; if it was flattened, it was recorded as "Fail".

[0099] Nozzle clogging test: A VERMES MDC3200 glue dispenser was used for continuous glue dispensing, with a 0.1 mm diameter nozzle selected. Glue dispensing was performed for 5 seconds. A 5-second interval was then observed, followed by another 5-second dispensing. This cycle was repeated until 30 ml of glue was dispensed, which took approximately 3 hours. Nozzle clogging was observed every 10 minutes, and the number of cloggings within the 3-hour period was recorded. Five different glues were used for dispensing for each sample type, and the total number of cloggings was recorded.

[0100] Bead width: A VERMES MDC3200 glue dispenser was used for continuous glue dispensing, with a 0.1mm diameter nozzle selected. The bead width was tested.

[0101] Bio-based content of the composition: The sum of (bio-based content of all components × weight percentage of components in the composition).

[0102] raw material Dow Voranol 2120P, polyether polyol.

[0103] Evonik Dynacoll 7360, aliphatic crystalline polyester polyol, crystallinity 50.1%

[0104] Evonik D7750, aliphatic polyester polyol, bio-based content 96%, crystallinity 55.7%.

[0105] PE2000: A proprietary bio-based polyester polyol. Using sebacic acid and bio-based 1,4-butanediol as raw materials, a condensation reaction was carried out in the presence of a titanium-based catalyst to prepare linear aliphatic crystalline polyester polyol B1-3 with a number average molecular weight of 2,000 g / mol, a bio-based content of 100%, a crystallinity of 56.2%, a hydroxyl value of 55 mgKOH / g, and an acid value of less than 1.

[0106] Cargill / Croda Priplast 3238, aliphatic amorphous polyester polyol, 100% bio-based.

[0107] Diana MB3068 is a hydroxyl-functionalized acrylic resin with a hydroxyl value of 8 mg KOH / g, number average D90 particle size of 190 μm, Tg of 51°C, and weight average molecular weight of 4,1000 g / mol.

[0108] Diana BR113 is an acrylic resin with a number average particle size of 270 μm and a D90 particle size, and does not contain active functional groups.

[0109] Covestro Desmodur 44C, aromatic diisocyanate MDI.

[0110] BASF Irganox 1010: Antioxidant.

[0111] Huntsman DMDEE: Catalyst.

[0112] adhesive composition Samples of adhesive compositions were prepared by the following method. Polyether polyols, crystalline polyester polyols, amorphous polyester polyols, and acrylic resin components were first added to a reactor according to the weight percentage of each component in Table 1. The reactor was heated to 150°C in a nitrogen atmosphere and vacuumed for 2-3 hours to remove water. The temperature was then lowered to 110°C. Dry nitrogen gas was introduced, and polyisocyanate and antioxidants were added. The reaction was carried out by stirring at 120°C for 2 hours under a nitrogen atmosphere. The catalyst was added, and the reaction was further carried out by stirring for 30 minutes under a nitrogen atmosphere. The resulting mixture was then discharged into a 30 ml high-temperature heat-resistant plastic needle tube, vacuum-degassed at 120°C for 30 minutes, and then sealed and cooled.

[0113] In Examples 1-4 and Comparative Examples 1-2, samples of adhesive compositions were prepared using raw materials according to the corresponding weight percentages listed at the top of Table 1. Examples 1-4 used hydroxyl group-containing acrylic resins with a number-average D90 particle size within the scope of the present invention, Comparative Example 1 did not use acrylic resin, and Comparative Example 2 used an acrylic resin with a larger particle size. According to the performance test results shown in Table 1, when the sample of Comparative Example 1 was sprayed / dispensed using a piezoelectric spray system, adhesive scattering occurred, the adhesive beads were crushed, a constant aspect ratio could not be maintained, and the adhesive strength and bonding properties were poor. In Comparative Example 2, nozzle clogging occurred frequently. In contrast, all performance indices for Examples 1-4 were satisfactory. The experimental results demonstrate that the use of acrylic resins containing active functional groups with a number-average D90 particle size within the scope of the present invention can effectively solve the problems that frequently occur during spraying / dispensing.

[0114] [Table 1]

Claims

1. A reactive polyurethane hot melt adhesive composition prepared by raw materials containing the following components, wherein the raw materials are Component (A) containing at least one type of polyether polyol, Component (B) comprising at least one crystalline polyester polyol (B1) and at least one amorphous polyester polyol (B2), Component (C) comprising at least one acrylic resin (C1), wherein the acrylic resin (C1) contains an active functional group that reacts with an isocyanate group, and the acrylic resin (C1) has a number average D90 particle size of 350 μm or less, and Component (D) containing at least one type of polyisocyanate Includes, A reactive polyurethane hot-melt adhesive composition wherein the equivalent ratio (NCO / OH) of isocyanate groups to hydroxyl groups of the above components is 1.2 to 6, preferably 1.5 to 5, and more preferably 1.7 to 3.

2. The reactive polyurethane hot melt adhesive composition according to claim 1, wherein the acrylic resin (C1) has a number average D90 particle size of 250 μm or less, preferably 210 μm or less, more preferably in the range of 100 μm to 210 μm, most preferably in the range of 120 μm to 200 μm, and most preferably in the range of 160 to 200 μm.

3. The reactive polyurethane hot-melt adhesive composition according to claim 1 or 2, wherein the reactive functional group having reactivity with an isocyanate group comprises one or two of a hydroxyl group and an amino group.

4. The reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 3, wherein the acrylic resin (C1) has a hydroxyl value in the range of 1 to 10 mg KOH / g, preferably 2 to 10 mg KOH / g, and more preferably 4 to 10 mg KOH / g.

5. The reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 4, wherein the acrylic resin (C1) has a glass transition temperature (Tg) of 30 to 110°C, preferably 40 to 80°C, and more preferably 45 to 58°C.

6. The reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 5, wherein the acrylic resin (C1) has a weight-average molecular weight in the range of 3,000 to 80,000 g / mol, preferably 5,000 to 60,000 g / mol, and more preferably 5,000 to 50,000 g / mol.

7. The reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 6, wherein the content of acrylic resin (C1) is in the range of 3 to 25% by weight, preferably 5 to 20% by weight, and more preferably 5% to 15% by weight, based on the total weight of components (A) to (D).

8. A reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 7, wherein component (C) further comprises at least one acrylic resin (C2), and the acrylic resin (C2) substantially does not contain an active functional group that is reactive with an isocyanate group.

9. The reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 8, wherein the weight ratio of crystalline polyester polyol (B1) to amorphous polyester polyol (B2) is in the range of 1:9 to 9:1, preferably 1:9 to 5:1, more preferably 1:9 to 3:1, and most preferably 1:3 to 3:

1.

10. A reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 9, wherein component (A), component (B), and component (C) substantially do not contain aromatic compounds.

11. The reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 10, wherein at least one polyisocyanate is an aromatic polyisocyanate.

12. A reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 11, wherein component (A), component (B), component (C), and component (D) each contain at least one partially or entirely bio-based material.

13. A reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 12, having a bio-based content of 10% or more, preferably 30% or more, more preferably 40% or more, wherein the bio-based content is determined according to ASTM D6866.

14. A reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 13, having a viscosity at 100°C in the range of 1,500 to 10,000 mPa.s, preferably in the range of 1,500 to 8,000 mPa.s, and more preferably in the range of 1,500 to 5,000 mPa.s.

15. An article comprising a first substrate and an adhesive layer disposed on the first substrate, formed by curing a reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 14.

16. The article according to claim 15, wherein the adhesive layer has a thickness in the range of 0.01 to 2 mm, preferably in the range of 0.05 to 1 mm, and more preferably in the range of 0.1 to 0.5 mm.

17. The article according to claim 15 or 16, wherein the adhesive layer is formed by coating a first substrate with a reactive polyurethane hot-melt adhesive composition according to any one of claims 1 to 14 using a piezoelectric injection system and curing the resulting product.

18. Use of an acrylic resin in a reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 14 for improving dispensing performance, wherein the acrylic resin is the acrylic resin (C1) according to any one of claims 1 to 14.

19. The use of the reactive polyurethane hot melt adhesive composition according to claim 18, wherein the total number of nozzle clogs is less than 5, preferably less than 3.

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