Adhesive composition for vehicle

Abstract

The present invention relates to an adhesive composition for a vehicle, comprising: a first urethane acrylate oligomer; a second urethane acrylate oligomer; an acrylic polymer not containing a urethane group; and an acrylic monomer, wherein the first urethane acrylate oligomer includes one or two functional groups in one molecule, and the second urethane acrylate oligomer includes three to six functional groups in one molecule.

Description

Automotive adhesive composition

[0001] The present invention relates to an automotive adhesive composition having excellent workability due to a fast curing speed, excellent storage stability and mechanical strength such as shear strength, and excellent adhesive strength even under harsh conditions such as high temperature, high humidity, and oil exposure.

[0002] With the rapid advancement of adhesive functionality and performance, physical bonding methods such as welding, previously used in assembly processes such as automobiles, construction, and civil engineering, are shifting towards chemical bonding methods. In particular, chemical bonding using adhesives is a lightweight bonding method that is simple and allows for a variety of bonding methods to be combined, expanding its application scope to various fields. Adhesives used in structures to replace these conventional physical bonding methods require adhesive performance such as shear strength, peel strength, fracture strength, and creep resistance, as well as various physical properties such as heat resistance, water resistance, and chemical resistance. Therefore, they typically contain additives such as thermosetting resins, thermoplastic resins, or synthetic rubber. Adhesives that can be applied to these structures are widely used, including one-component or two-component epoxy, acrylic, or urethane adhesives.

[0003] Meanwhile, recently, issues such as environmental pollution and stability have been raised regarding adhesives, and as a result, there is a growing demand for adhesives that have excellent properties such as adhesive strength, durability, and hardening properties, as well as excellent storage stability, and can completely replace physical bonding methods.

[0004] As an alternative, Korean Patent Publication No. 2021-0094604 (Patent Document 1) discloses a two-component adhesive comprising an acrylic compound, an oxidizing agent, and a reducing agent, and an adhesive laminate core for a stator comprising the same. However, the adhesive of Patent Document 1 has the disadvantage of requiring stirring before use and having a short working life, resulting in poor workability. Furthermore, conventional instant adhesives containing cyanoacrylate as a main component, while having excellent workability, have limitations such as low adhesive strength and poor oil resistance.

[0005] Therefore, there is a need for research and development on an adhesive composition suitable for use in automobile drive motors that has a fast curing speed, excellent workability, excellent mechanical strength such as storage stability and shear strength, and excellent adhesive strength even under harsh conditions such as high temperature, high humidity, and oil exposure.

[0006] The present invention aims to provide an automotive adhesive composition having excellent workability due to a fast curing speed, excellent mechanical strength such as storage stability and shear strength, and excellent adhesive strength even under harsh conditions such as high temperature, high humidity, and oil exposure, and particularly an adhesive composition for an automotive drive motor.

[0007] The present invention comprises a first urethane acrylate oligomer, a second urethane acrylate oligomer, an acrylic polymer not containing a urethane group, and an acrylic monomer,

[0008] The above first urethane acrylate oligomer contains 1 or 2 functional groups in one molecule,

[0009] The above second urethane acrylate oligomer provides an automotive adhesive composition containing 3 to 6 functional groups per molecule.

[0010] The adhesive composition according to the present invention has a fast curing speed, excellent workability, and superior mechanical strength, such as storage stability and shear strength. Furthermore, the adhesive composition exhibits excellent adhesive strength even under harsh conditions, such as high temperatures, high humidity, and oil exposure, making it highly suitable as an adhesive for structures operating in harsh environments, such as electric vehicle drive motors. In particular, the adhesive composition is highly suitable as an adhesive for bonding thin steel plates within electric vehicle drive motors.

[0011] The present invention is described in detail below.

[0012] The “weight average molecular weight” used in this specification is measured by a conventional method known in the art, and can be measured by, for example, a GPC (gel permeation chromatography) method.

[0013] Additionally, the “glass transition temperature” is measured by a conventional method known in the art, and can be measured by, for example, differential scanning calorimetry (DSC).

[0014] In this specification, “(meth)acrylic” means “acrylic” and / or “methacrylic”, and “(meth)acrylate” means “acrylate” and / or “methacrylate”.

[0015] An automotive adhesive composition according to the present invention comprises a first urethane acrylate oligomer, a second urethane acrylate oligomer, an acrylic polymer not containing a urethane group, and an acrylic monomer, wherein the first urethane acrylate oligomer contains 1 or 2 functional groups in one molecule, and the second urethane acrylate oligomer contains 3 to 6 functional groups in one molecule.

[0016] In particular, the adhesive composition according to the present invention includes two types of urethane acrylate oligomers having different numbers of functional groups, thereby further improving the crosslinking density and enhancing the elasticity and adhesive strength of the cured product.

[0017] “Parts by weight” in this specification refers to the content ratio of each component, and may also mean “% by weight.”

[0018]

[0019] 1st urethane acrylate oligomer

[0020] The first urethane acrylate oligomer plays a role in improving the adhesive strength of the cured product being manufactured.

[0021] The first urethane acrylate oligomer may be synthesized directly using a known method, or a commercially available product may be used. For example, the first urethane acrylate oligomer may be prepared by reacting a polyol compound, a first isocyanate compound, and a first (meth)acrylate monomer. In this case, the first (meth)acrylate monomer may include a hydroxyl group (-OH).

[0022] The first urethane acrylate oligomer forms a urethane group (-NH-(C=O)-O) through a chemical reaction between a hydroxyl group (-OH) of a polyol compound and an isocyanate group (-NCO) of a first isocyanate compound, and then reacts with a hydroxyl group (-OH) of a first (meth)acrylate monomer, thereby having acrylate reactivity and can impart adhesive strength to a cured product after curing of the adhesive composition.

[0023] The above polyol compound may be a polyalkylene polyol of diol or triol, an acrylic polyol, a polyester polyol, a polycarbonate polyol, a polyether polyol, a polycarbonate polyol, etc.

[0024] Specifically, the polyalkylene polyol of the diol or triol may include, for example, 1,2-hexanediol, 1,2-octanediol, 1,2-decanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polypropylene triol, poly(propylene glycol) diglycidyl ether, polypropylene glycol glycerol ether, etc.

[0025] The first isocyanate compound may be two or more isocyanate-containing compounds, for example, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4'-diphenylmethylene diisocyanate (4,4'-MDI), 2,4'-diphenylmethylene diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, 1,5-naphthalene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate or trimers thereof, isophorone diisocyanate, bis(4-isocyanatecyclohexyl)methane, 1-methyltrimethylene diisocyanate, 1,3-cyclopentene diisocyanate, It may include at least one selected from the group consisting of 1,4-cyclopentene diisocyanate, 1,2-cyclopentene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-cyclohexane, triphenylmethane triisocyanate, tris(isocyanatephenyl) thiophosphate, 1,6,10-undecane triisocyanate, and 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene.

[0026] The first (meth)acrylate monomer may include a hydroxyl group (-OH) and a (meth)acrylate group. For example, the first (meth)acrylate monomer may include at least one selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyisopropyl methacrylate, acrylic acid, and methacrylic acid.

[0027] The above first urethane acrylate oligomer can be prepared by reacting a polyol compound, a first isocyanate compound, and a first (meth)acrylate monomer in a molar ratio of 1:0.8:0.05 to 1:1.5:1.2, or a molar ratio of 1:0.9:0.09 to 1:1.3:1.10. If the molar ratio of each compound is less than the above range, the adhesion of the prepared coating film may be poor, and if it exceeds the range, the storage stability of the composition may be poor.

[0028] Specifically, if the molar ratio of the first isocyanate compound to the polyol compound is below the above range, the adhesiveness of the produced coating film may be poor, and if it exceeds the above range, the storage stability of the composition may be poor. In addition, if the molar ratio of the first (meth)acrylate monomer to the polyol compound is below the above range, the storage stability of the composition may be poor, and if it exceeds the above range, the workability of the composition may be poor.

[0029] The above first urethane acrylate oligomer contains one or two functional groups per molecule. Specifically, the first urethane acrylate oligomer may contain two functional groups per molecule. At this time, the 'functional group' may be an acrylate group. When the number of functional groups of the first urethane acrylate oligomer is within the above range, that is, when one molecule contains one or two functional groups, the adhesive strength of the adhesive composition containing it is further improved. On the other hand, when the first urethane acrylate oligomer having a monofunctional or difunctional structure as described above is not included and only a urethane acrylate oligomer having three or more functional groups per molecule is included, the crosslinking density of the composition increases, which may result in an increase in the hardness of the cured product, thereby causing a problem of insufficient adhesive strength.

[0030] In addition, the first urethane acrylate oligomer may have a weight average molecular weight (Mw) of 1,000 g / mol to 25,000 g / mol, 2,000 g / mol to 20,000 g / mol, or 2,000 g / mol to 16,000 g / mol. When the weight average molecular weight of the first urethane acrylate oligomer is less than the above range, the tensile strength of the manufactured cured product is low, resulting in insufficient adhesive strength. When the weight average molecular weight is more than the above range, excessive adhesive strength may cause problems such as poor flexibility, storage stability, and workability.

[0031] The first urethane acrylate oligomer may be included in an amount of 20 to 40 wt%, or 25 to 37 wt%, based on the total amount of the adhesive composition. If the amount of the first urethane acrylate oligomer is less than the above range, the adhesive strength of the cured product produced may be poor, and if it exceeds the above range, the drying time may be excessively long.

[0032]

[0033] Secondary urethane acrylate oligomer

[0034] The second urethane acrylate oligomer plays a role in improving the hardness of the cured product by increasing the crosslinking density.

[0035] The second urethane acrylate oligomer may be synthesized directly using a known method, or a commercially available product may be used. For example, the second urethane acrylate oligomer may be prepared by reacting a second isocyanate compound and a second (meth)acrylate monomer containing a hydroxyl group.

[0036] The second isocyanate compound may be two or more isocyanate-containing compounds, for example, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4'-diphenylmethylene diisocyanate (4,4'-MDI), 2,4'-diphenylmethylene diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, 1,5-naphthalene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, trishexamethylene triisocyanate, isophorone diisocyanate, bis(4-isocyanatecyclohexyl)methane, 1-methyltrimethylene diisocyanate, 1,3-cyclopentene It may include at least one selected from the group consisting of diisocyanate, 1,4-cyclopentene diisocyanate, 1,2-cyclopentene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-cyclohexane, triphenylmethane triisocyanate, tris(isocyanatephenyl) thiophosphate, 1,6,10-undecane triisocyanate, and 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene.

[0037] The second (meth)acrylate monomer may include, as a hydroxyl group-containing monomer, at least one selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid dimer, 2-hydroxyethyl methacrylate, 2-hydroxyisopropyl methacrylate, pentaerythritol triacrylate, and caprolactone-modified (meth)acrylate.

[0038] The above second urethane acrylate oligomer can be prepared by reacting a second isocyanate compound and a second (meth)acrylate monomer in a molar ratio of 0.1:1 to 0.6:1, or a molar ratio of 0.2:1 to 0.5:1.

[0039] If the molar ratio of the second isocyanate compound to the second (meth)acrylate monomer is outside the above range, it is not only difficult to manufacture or secure a second urethane acrylate oligomer containing a desired functional group, but also the problem of poor adhesion of the manufactured coating film may occur, and if it exceeds the above range, the problem of poor storage stability of the composition may occur.

[0040] Specifically, the second urethane acrylate oligomer of the present invention contains 3 to 6 functional groups in one molecule. At this time, the 'functional group' may be an acrylate group, and when the number of functional groups is within the above range, sufficient crosslinking is possible, so that the reactivity of the adhesive including it is excellent. On the other hand, if the second urethane acrylate oligomer having three or more functional groups as described above is not included, and only the first urethane acrylate oligomer having a monofunctional or difunctional group is included, the crosslinking density of the composition may be insufficient, which may cause a problem in that the mechanical properties of the cured product become inferior.

[0041] In addition, the second urethane acrylate oligomer may have a weight average molecular weight (Mw) of 500 g / mol to 5,000 g / mol, or 800 g / mol to 4,000 g / mol. When the weight average molecular weight of the second urethane acrylate oligomer is less than the above range, the crosslinking density may be insufficient, resulting in poor mechanical properties of the cured product produced. When the weight average molecular weight exceeds the above range, the storage stability and workability of the composition may be poor.

[0042] The second urethane acrylate oligomer may be included in an amount of 2 to 15 wt%, or 5 to 12 wt%, based on the total amount of the adhesive composition. If the amount of the second urethane acrylate oligomer is less than the above range, the crosslinking density may be insufficient, resulting in poor mechanical properties of the cured product produced. If the amount exceeds the above range, the drying time may be excessively long, or the adhesive strength of the cured product produced may be poor.

[0043]

[0044] Meanwhile, in the automotive adhesive composition of the present invention, the total amount of the first urethane acrylate oligomer and the second urethane acrylate oligomer may be included in an amount of 30 to 50 parts by weight or 35 to 48 parts by weight, based on 1 to 10 parts by weight of the acrylic polymer. If the total amount of the first urethane acrylate oligomer and the second urethane acrylate oligomer is less than the above range, the adhesive strength and reliability of the cured product may be insufficient due to insufficient cohesion of the adhesive, and if it exceeds the above range, the viscosity of the adhesive composition may be high, resulting in problems such as poor ejection during work, resulting in insufficient workability.

[0045] In addition, in the automotive adhesive composition of the present invention, the first urethane acrylate oligomer and the second urethane acrylate oligomer may be included in a weight ratio of 2:1 to 9:1, or a weight ratio of 3:1 to 7:1. When the weight ratio of the first urethane acrylate oligomer and the second urethane acrylate oligomer is less than the above range, that is, when the weight of the first urethane acrylate oligomer is small or the same as the weight of the second urethane acrylate oligomer, the cohesive force of the adhesive is insufficient, resulting in a problem of insufficient adhesive force and reliability of the cured product. When the weight ratio exceeds the above range, that is, when the weight of the first urethane acrylate oligomer is excessive, the viscosity of the adhesive composition may be excessively high, resulting in a problem of insufficient workability, such as poor ejection during work.

[0046]

[0047] acrylic polymer

[0048] Acrylic polymers do not contain urethane groups and do not participate in the reaction during curing, thus serving to relieve stress in the composition.

[0049] The above acrylic polymer is not particularly limited as long as it does not typically contain a urethane group and can be included in an adhesive composition, and a product directly synthesized according to a known method or a commercially available product can be used. In this case, the acrylic polymer may be, for example, one manufactured by polymerizing a third (meth)acrylate monomer containing an alkyl group having 1 or 2 carbon atoms and a fourth (meth)acrylate monomer containing an alkyl group having 3 to 5 carbon atoms.

[0050] As the third (meth)acrylate monomer, for example, one or more selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate can be used.

[0051] As the fourth (meth)acrylate monomer, for example, at least one selected from the group consisting of n-propyl acrylate, isopropyl acrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylacrylate, t-butyl acrylate, isobutylacrylate, n-butylmethacrylate, t-butyl methacrylate, and isobutylmethacrylate may be used.

[0052] The above acrylic polymer can be manufactured using a radical polymerization method, and the weight average molecular weight can be controlled depending on the initiator and polymerization time.

[0053] In addition, the acrylic polymer may be a copolymer of methyl methacrylate and butyl methacrylate, and may be copolymerized at a weight ratio of 0.1:1 to 1.2:1, or a weight ratio of 0.3:1 to 1:1, or a weight ratio of 0.5:1 to 0.95:1. In this case, when the weight ratio of methyl methacrylate and butyl methacrylate is within the above range during copolymerization, there is an advantage of effectively alleviating stress of the composition.

[0054] The above acrylic polymer may have a weight average molecular weight (Mw) of 40,000 g / mol to 80,000 g / mol, or 50,000 g / mol to 60,000 g / mol, specifically 52,000 g / mol to 58,000 g / mol. When the weight average molecular weight of the acrylic polymer is within the above range, it has an effect of relieving stress upon fracture of the adhesive composition. On the other hand, when the weight average molecular weight of the acrylic polymer is less than the above range, a problem occurs in which the brittleness of the manufactured cured product is weakened, and when it exceeds the above range, a problem may occur in which the viscosity of the adhesive composition is very high, resulting in insufficient handleability.

[0055] The above acrylic polymer may have a glass transition temperature (Tg) of 40°C to 80°C, or 45°C to 50°C. When the glass transition temperature of the acrylic polymer is within the above range, it has a stress-relieving effect on the composition. On the other hand, when the glass transition temperature of the acrylic polymer is below the above range, the problem of reduced adhesiveness may occur, and when it exceeds the above range, the problem of reduced toughness of the manufactured cured product may occur.

[0056] In addition, the acrylic polymer may be included in the composition in an amount of 1 to 10 parts by weight, or 3 to 7 parts by weight, based on a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer. When the acrylic polymer is included within the above content range, the produced coating film does not stain, thereby providing good appearance properties. On the other hand, when the acrylic polymer content is less than the above range, the acrylic polymer content is low, resulting in no stress relaxation effect of the adhesive, and when it exceeds the above range, the adhesive strength of the cured product may be poor.

[0057]

[0058] Acrylic monomer

[0059] The above acrylic monomer plays a role in improving workability by controlling the viscosity of the composition.

[0060] The acrylic monomer may include, for example, at least one selected from the group consisting of hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (2-HEMA), glycidyl methacrylate (GMA), methyl methacrylate (MMA), acryloyl morpholine (ACMO), isobornyl acrylate (IBOA), 2-hydroxypropyl methacrylate (2-HPMA), hydroxypropyl acrylate (HPA), ethoxyethoxy ethyl acrylate (EOEOEA), butylacrylate (BA), benzyl acrylate (BZA), benzyl methacrylate (BZMA), lauryl acrylate (LA), lauryl methacrylate (LMA), isodecyl acrylate (IMA), isodecyl methacrylate (IDMA), phenoxy methacrylate (PHEMA), caprolactone acrylate (CA), and stearyl acrylate (SA).

[0061] The above acrylic monomer may have a glass transition temperature of 80°C or higher, or 80°C to 200°C.

[0062] Specifically, the acrylic monomer may include a first acrylic monomer having a glass transition temperature of 130°C to 160°C and a second acrylic monomer having a glass transition temperature of 80°C to 120°C. More specifically, the acrylic monomer may include a first acrylic monomer having a glass transition temperature of 140°C to 150°C and a second acrylic monomer having a glass transition temperature of 90°C to 110°C. When the adhesive composition includes two types of acrylic monomers having different glass transition temperatures as described above, there is an effect of increasing the adhesive strength of the cured product.

[0063] The acrylic monomer may be included in the composition in an amount of 20 to 70 parts by weight, or 35 to 60 parts by weight, specifically 25 to 45 parts by weight, based on a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer. When the acrylic monomer is included within the above content range, the viscosity of the composition is appropriate, thereby providing excellent workability. On the other hand, when the content of the acrylic monomer is less than the above range, the viscosity of the composition is high, resulting in a problem of reduced workability, and when it exceeds the above range, the toughness of the produced cured product may be reduced.

[0064] Specifically, the composition may comprise 15 to 35 parts by weight and 5 to 20 parts by weight of the second acrylic monomer, relative to a total of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer. Alternatively, the composition may comprise 20 to 30 parts by weight of the first acrylic monomer, and / or 5 to 15 parts by weight of the second acrylic monomer, relative to a total of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer.

[0065] If the content of the first acrylic monomer and / or the second acrylic monomer is below the above range, a problem of poor adhesive strength of the cured product may occur, and if it exceeds the above range, a problem of poor workability may occur due to low viscosity of the adhesive composition.

[0066] Additionally, the composition may further include a third acrylic monomer having a glass transition temperature of 40° C. to 60° C. For example, the third acrylic monomer may be hydroxyethyl methacrylate.

[0067] Additionally, the third acrylic monomer may be included in the composition in an amount of 10 to 35 parts by weight or 15 to 30 parts by weight, based on a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer. When the third acrylic monomer is included within the above content range, the viscosity of the composition may be appropriate, thereby improving workability.

[0068]

[0069] organic peroxides

[0070] The above adhesive composition may additionally contain an organic peroxide to radically polymerize urethane acrylate.

[0071] Examples of the organic peroxide include organic peroxides such as dicumyl peroxide, t-butyl hydroperoxide, p-methane hydroperoxide, methyl ethyl ketone peroxide, cyclohexane peroxide, dicumyl peroxide, diisopropylbenzene hydroperoxide, ketone peroxides, diallyl peroxides, and peroxyesters. These organic peroxides may be used singly or as a mixture of two or more, and may include dicumyl peroxide from the viewpoint of further improving the reactivity and storage stability of the adhesive composition.

[0072] At this time, the organic peroxide may have a half-life temperature of 80°C to 200°C for 1 minute from the viewpoints of stability, reactivity, and compatibility. Specifically, the organic peroxide may have a half-life temperature of 100°C to 180°C for 1 minute. The "half-life temperature" is the temperature at which an aqueous solution containing the organic peroxide at a concentration of 0.1 mol% reaches 50% of its initial active hydrogen content within 1 minute.

[0073] The organic peroxide may be included in the composition in an amount of 1 to 15 parts by weight or 2 to 10 parts by weight, based on a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer. If the amount of the organic peroxide is less than the above range, the curing reaction of the adhesive composition may be somewhat slow, resulting in a problem of insufficient workability. If the amount exceeds the above range, the curing of the adhesive composition may progress rapidly, resulting in cracks occurring in the cured product.

[0074]

[0075] additives

[0076] The adhesive composition according to the present invention may additionally include additives such as a coupling agent. In this case, the additives are not particularly limited as long as they can be conventionally added to adhesive compositions.

[0077] The above additive may be included in the composition in an amount of 0.1 to 20 parts by weight, or 0.5 to 10 parts by weight, based on a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer, but is not limited thereto.

[0078] The automotive adhesive composition according to the present invention, as described above, may be a single-component adhesive composition, and has excellent workability due to a fast curing speed, storage stability, and mechanical strength such as shear strength. In addition, the adhesive composition has excellent adhesive strength even under harsh conditions such as high temperature, high humidity, and oil exposure, making it highly suitable as an adhesive for structures operating in harsh environments, such as electric vehicle drive motors. In particular, the automotive adhesive composition is highly suitable as an adhesive composition for automotive drive motors.

[0079] Hereinafter, the present invention will be described in more detail through examples. However, these examples are provided solely to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0080] [Example]

[0081] Manufacturing Example 1. Manufacturing of the first urethane acrylate oligomer-1

[0082] 1,6-Hexanediol, isophorone diisocyanate, and 2-hydroxyethyl acrylate were reacted in a molar ratio of 1:1.2:0.1 to produce a first urethane acrylate oligomer-1 (containing two functional groups) having a weight average molecular weight (Mw) of 15,000 g / mol.

[0083]

[0084] Manufacturing Example 2. Manufacturing of second urethane acrylate oligomer-1

[0085] Caprolactone-modified (meth)acrylate and hexamethylene diisocyanate trimer were reacted at a molar ratio of 1:0.4 to produce a second urethane acrylate oligomer-1 (containing three functional groups) having a weight-average molecular weight (Mw) of 3,000 g / mol.

[0086]

[0087] Manufacturing Example 3. Manufacturing of the first urethane acrylate oligomer-2

[0088] Caprolactone-modified (meth)acrylate, isophorone diisocyanate, and 2-hydroxyethyl acetate were reacted in a molar ratio of 1:1:1 to produce a first urethane acrylate oligomer-2 (containing two functional groups) having a weight average molecular weight (Mw) of 3,000 g / mol.

[0089]

[0090] Manufacturing Example 4. Manufacturing of second urethane acrylate oligomer-2

[0091] Pentaerythritol triacrylate and isophorone diisocyanate were reacted at a molar ratio of 1:0.25 to produce a second urethane acrylate oligomer-2 (containing 6 functional groups) having a weight average molecular weight (Mw) of 1,000 g / mol.

[0092]

[0093] Manufacturing Example 5. Manufacturing of second urethane acrylate oligomer-3

[0094] Pentaerythritol triacrylate and hexamethylene diisocyanate trimer were reacted at a molar ratio of 1:0.2 to produce a second urethane acrylate oligomer-3 (containing 9 functional groups) having a weight average molecular weight (Mw) of 4,000 g / mol.

[0095]

[0096] Manufacturing Example 6. Manufacturing of acrylic polymer-1

[0097] Acrylic polymer-1 having a weight average molecular weight (Mw) of 55,000 g / mol and a glass transition temperature (Tg) of 47°C was prepared by copolymerizing methyl methacrylate (MMA) and butyl methacrylate (BMA) at a weight ratio of 0.8:1.

[0098]

[0099] Manufacturing Example 7. Manufacturing of acrylic polymer-2

[0100] Acrylic polymer-2 having a weight average molecular weight (Mw) of 40,000 g / mol and a glass transition temperature (Tg) of 100°C was prepared by polymerizing methyl methacrylate (MMA).

[0101]

[0102] Examples 1 to 12 and Comparative Examples 1 to 6. Preparation of adhesive compositions

[0103] An adhesive composition was prepared by mixing ingredients in the same amounts as in Tables 1 to 3.

[0104] Ingredients (weight parts) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 First Urethane Acrylate Oligomer-1 (Preparation Example 1) 30 35 30 30 36 30 Second Urethane Acrylate Oligomer-1 (Preparation Example 2) 10 5 15 4 10 Second Urethane Acrylate Oligomer-2 (Preparation Example 4) 10 First Urethane Acrylate Oligomer-2 (Preparation Example 3) Second Urethane Acrylate Oligomer-3 (Preparation Example 5) Acrylic Polymer-1 (Preparation Example 6) 5 5 5 5 Acrylic Polymer-2 (Preparation Example 7) 5 First Acrylic Monomer 2 5 30 25 25 25 25 Second Acrylic Monomer 10 5 10 5 10 10 Third Acrylic Monomer 15 15 15 15 15 15 15 Fourth Acrylic Monomer Organic Peroxide 444444 Coupling agent 111111 Total 100100100100100100

[0105]

[0106] Ingredients (weight parts) Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 First Urethane Acrylate Oligomer-1 (Preparation Example 1) 30 30 30 30 30 20 Second Urethane Acrylate Oligomer-1 (Preparation Example 2) 10 10 10 10 10 10 20 Second Urethane Acrylate Oligomer-2 (Preparation Example 4) First Urethane Acrylate Oligomer-2 (Preparation Example 3) Second Urethane Acrylate Oligomer-3 (Preparation Example 5) Acrylic Polymer-1 (Preparation Example 6) 5 5 1 1 0 5 5 Acrylic Polymer-2 (Preparation Example 7) First Acrylic Monomer 30 25 25 23 15 25 Second Acrylic Monomer 20 10 9 20 10 Third Acrylic Monomer 10 19 13 15 15 Fourth Acrylic Monomer 15 Organic Peroxide 444444 Coupling agent 111111 Total 100100100100100100

[0107]

[0108] Ingredients (weight parts) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 First Urethane Acrylate Oligomer-1 (Preparation Example 1) 3030 Х404030 Second Urethane Acrylate Oligomer-1 (Preparation Example 2) 15 Х1515 Second Urethane Acrylate Oligomer-2 (Preparation Example 4) First Urethane Acrylate Oligomer-2 (Preparation Example 3) 10 Second Urethane Acrylate Oligomer-3 (Preparation Example 5) 10 Acrylic Polymer-1 (Preparation Example 6) 555510 ХAcrylic Polymer-2 (Preparation Example 7) First Acrylic Monomer 15253025 Х25 Second Acrylic Monomer 2010151010 Third Acrylic Monomer 1515301515 Fourth Acrylic Monomer Organic Peroxide 4444154 Coupling agent 1111201 Total 100100100100100100

[0109]

[0110] Below, the manufacturer and product name, or ingredient name, of each ingredient used in comparative examples and examples are shown in Table 4.

[0111] Ingredient Notes 1st acrylic monomer Acryloyl morpholine (Tg: 145°C) 2nd acrylic monomer Isobornyl acrylate (Tg: 88°C) 3rd acrylic monomer Hydroxyethyl methacrylate (Tg: 45°C) 4th acrylic monomer Polyethylene glycol (Mw: 400g / mol) diacrylate (Tg: 7°C) Organic peroxide Dicumyl peroxide (1 minute half-life temperature: 112°C) Coupling 3-methacryloxypropyl trimethoxy silane

[0112]

[0113] Test example: Physical property evaluation

[0114] The physical properties of the compositions of the examples and comparative examples were measured using the following methods, and the results are shown in Table 5 below.

[0115] (1) Productivity

[0116] Using an in-die mold device, one sheet of electrical steel plate (manufacturer: POSCO, product name: 25PNX1250F) was cured at 150°C for 1 minute, and then a total of 160 sheets were laminated. During lamination, an adhesive composition of an example or comparative example was applied between each electrical steel plate to a thickness of 5 to 10 μm to produce a core. The adhesion status of the core taken out from the mold device was checked, and productivity was evaluated as pass or NG based on the following criteria.

[0117] Pass: No peeling or lifting of each layer of electrical steel sheet

[0118] NG: The electrical steel sheet peels or lifts due to insufficient adhesive strength.

[0119] (2) Peel strength

[0120] According to the ISO 1464 standard, an electrical steel plate (manufacturer: POSCO, product name: 25PNX1250F) was cut into 25 mm wide, 100 mm long, and 0.25 mm thick to produce a steel plate specimen, and an adhesive composition of an example or comparative example was applied onto the steel plate specimen to a width of 25 mm, a length of 80 mm, and a thickness of 10 ㎛. Thereafter, another steel plate specimen was laminated and fixed on the adhesive composition, and then treated at 180°C for 5 minutes and cured at 25°C for 24 hours to produce a sample. Thereafter, the peel strength of the sample was measured under an environment of a tensile speed of 10 mm / min using a universal materials testing machine.

[0121] (3) Shear bond strength

[0122] According to EN 1465 standard, electrical steel plates (manufacturer: POSCO, product name: 25PNX1250F) were cut to 20 mm in width and 25 mm in length, and an adhesive composition of an example or comparative example was applied to a thickness of 10 μm. Then, another electrical steel plate was covered and fixed on the adhesive composition, and then another electrical steel plate was covered and fixed on top of that, and then treated at 180°C for 5 minutes and cured at 25°C for 24 hours to prepare a sample.

[0123] Afterwards, the breaking strength and breaking displacement of the sample were measured under an environment of a tensile speed of 10 mm / min using a universal material testing machine.

[0124] (4) High temperature durability

[0125] A sample manufactured in the same manner as the sample for measuring shear bond strength in item (3) was left at 150°C (high temperature) for 200 hours, then left at 25°C for 24 hours, and then the shear bond strength of the sample was measured using a universal material testing machine under an environment of a tensile speed of 10 mm / min to evaluate high-temperature durability.

[0126] (5) Thermal shock resistance

[0127] A sample manufactured in the same manner as the sample for measuring shear bond strength in item (3) was subjected to a total of 300 cycles using a thermal shock device, where one cycle was performed at -40°C for 30 minutes and then at 140°C for 30 minutes. Afterwards, the sample was left at 25°C for 24 hours, and the shear bond strength of the sample was measured using a universal material testing machine at a tensile speed of 10 mm / min to evaluate the thermal shock resistance.

[0128] (6) Storage stability

[0129] The initial viscosity of the adhesive composition was measured at 25°C, and then the composition was left at 25°C for two weeks. The viscosity change rate relative to the initial viscosity was calculated. A viscosity change rate of 5% or less was evaluated as pass, and a change rate of more than 5% was evaluated as NG.

[0130] Item Productivity Peel strength (N / 25mm) Shear bond strength High temperature durability (MPa) Thermal shock resistance (MPa) Storage stability Breaking strength (MPa) Breaking displacement (mm) Standard 40 or more 5.8 or more 8 or more 5 or more 5 or more 5% or less: pass, over 5%: NG Example 1 pass 6 5 6.29 6 5.65 6pass Example 2 pass 7 8 6.31 1.25 7 5.7pass Example 3 pass 5 0 6.19 5 5.65 6pass Example 4 pass 5 2 6 9.35 35 3pass Example 5 pass 7 2 6.31 0.8 5.45 6pass Example 6 pass 5 6 6.18 15 15 3pass Example 7 pass 6 9 6.39 6 5.35 2pass Example 8pass455.885.35.3passExample 9pass686.29.35.45.3passExample 10pass626.29.35.45.3passExample 11pass596.19.35.35.3passExample 12pass435.88.55.25.1passComparative example 1pass265.35.15.15.1passComparative example 2pass415.68.15.35.2passComparative example 3pass265.14.62.32.3passComparative example 4pass826.310.64.23.6passComparative example 5NGManufacturing not possibleComparative example 6pass6267.55.55.5pass

[0131]

[0132] As shown in Table 5, the adhesive compositions of Examples 1 to 12 have excellent productivity and storage stability, and it can also be confirmed that the cured products produced therefrom have excellent peel strength, shear bond strength, high-temperature durability, and thermal shock resistance.

[0133] On the other hand, the cured products prepared from the adhesive composition of Comparative Example 1 containing the first urethane acrylate oligomer-2 of Preparation Example 3 containing two functional groups instead of the second urethane acrylate oligomer of the present invention and the adhesive composition of Comparative Example 3 not containing the first urethane acrylate oligomer had insufficient peel strength and shear bond strength. In particular, it can be confirmed that the adhesive composition of Comparative Example 3 has poor high-temperature durability and thermal shock resistance.

[0134] In addition, the cured product manufactured from the adhesive composition of Comparative Example 2 containing the second urethane acrylate oligomer-3 of Manufacturing Example 5 containing nine functional groups had insufficient breaking strength.

[0135] In addition, the cured product prepared from the adhesive composition of Comparative Example 4 that did not include the second urethane acrylate oligomer was poor in high-temperature durability and thermal shock resistance.

[0136] In addition, the adhesive composition of Comparative Example 5, which does not contain an acrylic monomer, had a high viscosity and could not be stirred, so it could not be manufactured as an adhesive.

[0137] In addition, the cured product manufactured from the adhesive composition of Comparative Example 6, which does not include an acrylic polymer, had insufficient fracture displacement, which is a shear bond strength.

Claims

1. Containing a first urethane acrylate oligomer, a second urethane acrylate oligomer, an acrylic polymer not containing a urethane group, and an acrylic monomer, The above first urethane acrylate oligomer contains 1 or 2 functional groups in one molecule, The second urethane acrylate oligomer is an automotive adhesive composition containing 3 to 6 functional groups per molecule.

2. In claim 1, An automotive adhesive composition comprising the first urethane acrylate oligomer and the second urethane acrylate oligomer in a weight ratio of 2:1 to 9:

1.

3. In claim 1, The above acrylic polymer has a weight average molecular weight of 40,000 g / mol to 80,000 g / mol and a glass transition temperature of 40°C to 80°C, and is an automotive adhesive composition that is a copolymer of methyl methacrylate and butyl methacrylate.

4. In claim 1, The above acrylic monomer is an automotive adhesive composition having a glass transition temperature of 80°C or higher.

5. In claim 1, An automotive adhesive composition further comprising an organic peroxide having a half-life temperature of 80°C to 200°C for 1 minute.

6. In claim 1, An automotive adhesive composition comprising 1 to 10 parts by weight of an acrylic polymer not containing a urethane group, with respect to a total amount of 30 to 50 parts by weight of the first urethane acrylate oligomer and the second urethane acrylate oligomer.