JP7452266B2 - Adhesives and adhesives - Google Patents

Description

The present invention relates to an adhesive and an adhesive body.

Various members constituting a vehicle are sometimes bonded using an adhesive containing an epoxy resin (for example, Patent Document 1).

JP2019-38926A

Although conventional adhesives containing epoxy resins exhibit good adhesion to various adherends, their cured products tend to exhibit low tan δ at low temperatures below room temperature. A low tan δ may affect adhesive properties, damping properties, etc. Therefore, adhesives that bond adherends used in a wide temperature range such as vehicle parts should have a high tan δ in as wide a temperature range as possible. It is desirable to be able to form a cured product that maintains the

Accordingly, one aspect of the present invention provides an adhesive that includes an epoxy resin and can form a cured product exhibiting a high tan δ in a wide temperature range including a low temperature range around 0°C.

One aspect of the invention provides an adhesive comprising an epoxy resin comprising a dimer acid diglycidyl ester and a block copolymer elastomer having a polymethyl methacrylate block and a poly n-butyl acrylate block.

Another aspect of the present invention provides an adherend having two or more adherends and an adhesive layer that adheres the two or more adherends. The adhesive layer is a cured product of the adhesive according to one aspect of the present invention.

According to one aspect of the present invention, there is provided an adhesive that includes an epoxy resin and can form a cured product exhibiting a high tan δ in a wide temperature range including a low temperature range around 0°C.

It is a viscoelastic curve showing the relationship between tan δ of a cured adhesive and temperature.

Hereinafter, several embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In this specification, (meth)acryloyl means acryloyl or methacryloyl, and the same applies to other similar expressions.

An adhesive according to one embodiment includes an epoxy resin including a dimer acid diglycidyl ester and a block copolymer elastomer having a polymethyl methacrylate block and a poly n-butyl acrylate block. The adhesive may further include a curing agent that reacts with the epoxy resin to advance the curing reaction. When the adhesive includes a curing agent, the adhesive is an adhesive set consisting of a first liquid containing an epoxy resin and a second liquid containing a curing agent, that is, a two-component adhesive. Good too. In that case, at least one of the first liquid and the second liquid further contains a block copolymer elastomer.

The content of dimer acid diglycidyl ester may be 5% by mass or more and 30% by mass or less, or 20% by mass or more based on the mass of the adhesive excluding the silane coupling agent and inorganic filler described below. It may be less than % by mass.

The epoxy resin may further contain other epoxy resins in addition to the dimer acid diglycidyl ester. Other epoxy resins may have 2 to 4 epoxy groups.

Examples of other epoxy resins include glycidyl ester type epoxy resins such as phthalate diglycidyl ester; bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins, and hydrogenated epoxy resins. Diglycidyl ether type epoxy resins such as bisphenol A type epoxy resins; novolak type epoxy resins such as phenol novolac type epoxy resins and cresol novolak type epoxy resins; biphenyl type epoxy resins such as biphenyl type epoxy resins and biphenylaralkyl type epoxy resins ; a glycidylamine type epoxy resin which is a reaction product of an amine compound (for example, p-aminophenol, diaminodiphenylmethane, isocyanuric acid) and epichlorohydrin; and aliphatic epoxy resins.

Other epoxy resins may further have a (meth)acryloyl group. In this specification, compounds having two or more epoxy groups and one (meth)acryloyl group are classified as epoxy resins. The epoxy resin may be a compound having two or more epoxy groups and no (meth)acryloyl group.

The adhesive may further include an acrylic monomer having two or more (meth)acryloyl groups. Since the adhesive component containing such a combination has high compatibility with the block copolymer elastomer, it is easy to obtain an adhesive having good storage stability. In addition, a particularly more pronounced effect can be achieved in terms of elongation at -40°C.

The acrylic monomer is a bifunctional or more functional compound having an acryloyl group, a methacryloyl group, or both. The number of (meth)acryloyl groups that the acrylic monomer has may be 2 to 4.

The acrylic monomer may be, for example, a poly(meth)acrylate of an aliphatic polyol. Examples of poly(meth)acrylates of aliphatic polyols include diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and bifunctional (meth)acrylic monomers such as polyethylene polypropylene glycol di(meth)acrylate, trifunctional (meth)acrylic monomers such as trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate, and Examples include tetrafunctional (meth)acrylic monomers such as ditrimethylolpropane tetra(meth)acrylate. Other examples of acrylic monomers include tris(2-(meth)acryloyloxyethyl)isocyanurate, 2,2'-di(meth)acryloyloxydiethyl phosphate, and ethylene oxide-modified phosphoric acid di(meth)acrylate. Can be mentioned. These acrylic monomers can be used alone or in combination of two or more.

The acrylic monomer may have two or more (meth)acryloyl groups and an epoxy group. In this specification, compounds having two or more (meth)acryloyl groups and one or more epoxy groups are classified as acrylic monomers. The acrylic monomer may be a compound having two or more (meth)acryloyl groups and no epoxy group.

The adhesive (or first liquid) according to one embodiment may further include a monofunctional acrylic monomer having one (meth)acryloyl group, a monofunctional epoxy resin having one epoxy group, or both of these. good.

The content of the acrylic monomer having two or more (meth)acryloyl groups in the adhesive according to one embodiment includes the acrylic monomer having two or more (meth)acryloyl groups and the epoxy monomer having two or more epoxy groups. The amount may be 10 to 90% by weight, 20 to 80% by weight, 30 to 70% by weight, or 40 to 60% by weight based on the total amount of resin. The total amount of the acrylic monomer having two or more (meth)acryloyl groups and the epoxy resin having two or more epoxy groups is the mass of the adhesive excluding the silane coupling agent and inorganic filler described below. The content may be 40% by mass or more, 45% by mass or more, or 50% by mass or more, and may be 75% by mass or less, 70% by mass or less, or 65% by mass or less. In the case of a two-part adhesive, the total amount of the acrylic monomer having two or more (meth)acryloyl groups and the epoxy resin having two or more epoxy groups is the silane coupling agent described below in the first part. and 50 to 100% by mass, 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 85 to 100% by mass, or 90 to 100% by mass, based on the mass of the part excluding the inorganic filler. There may be.

Curing agents may include compounds such as aliphatic amine compounds and aromatic amine compounds. When the adhesive contains an acrylic monomer, the curing agent may contain a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group. The compound may have 2-4 or 2-3 nucleophilic reactive groups.

The nucleophilic reactive group may be, for example, an aliphatic amino group or a thiol group. From the viewpoint of reactivity with the (meth)acryloyl group, the nucleophilic reactive group may be an aliphatic amino group. The combination of an epoxy resin and/or acrylic monomer and a compound having an aliphatic amino group can exhibit excellent curability at room temperature and suppression of dripping when an adhesive is applied. . Examples of compounds having aliphatic amino groups include aliphatic amine compounds having two or more primary aliphatic amino groups, such as 1,3-bisaminomethylcyclohexane and 1,6-hexanediamine. Can be mentioned. An example of a commercially available compound having an aliphatic amino group is jER Cure 3080 (manufactured by Mitsubishi Chemical Corporation, trade name).

The content of the compound having a nucleophilic reactive group may be 10% by mass or more and 25% by mass or less based on the mass of the adhesive excluding the silane coupling agent and inorganic filler described below. , or 20% by mass or less. In the case of a two-part adhesive, the content of the compound having a nucleophilic reactive group in the second part is based on the mass of the second part excluding the silane coupling agent and inorganic filler described below. , 30-100% by mass, 40-100% by mass, 50-100% by mass, 60-100% by mass, 70-100% by mass, 80-100% by mass, 85-100% by mass, or 90-100% by mass. There may be.

The block copolymer elastomer is a triblock copolymer in which a polymethyl methacrylate block, a poly n-butyl acrylate block, and a polymethyl methacrylate block are bonded in this order, that is, polymethyl methacrylate-block-poly n-butyl acrylate-block- It may also be polymethyl methacrylate. Triblock copolymers are less likely to bleed out after curing. The proportion of the polymethyl methacrylate block in the block copolymer elastomer may be 5% by mass or more, or 10% by mass or more, and 40% by mass based on the total mass of the polymethyl methacrylate block and poly n-butyl acrylate block. Below, it may be 35% by mass or less, 30% by mass or less, or 25% by mass or less. The block copolymer elastomer may contain only polymethyl methacrylate blocks and poly n-butyl acrylate blocks, or may contain other partial structures such as terminal groups or small amounts of other blocks. The total proportion of the polymethyl methacrylate block and the poly n-butyl acrylate block in the block copolymer elastomer is 80 to 100% by mass, 90 to 100% by mass, or 95 to 100% by mass based on the mass of the block copolymer elastomer. It may be %.

From the viewpoint of further improving the elongation at -40 ° C., the melt flow rate (MFR) of the block copolymer elastomer may be 40 g / 10 minutes or less, 20 g / 10 minutes or less, or 10 g / minute or less, It may be 1.0 g/10 minutes or more, or 2.0 g/10 minutes or more. The MFR here is a value measured under the conditions of 190° C. and 2.16 kg.

From the viewpoint of further improving the elongation at -40°C, the tensile elongation of the block copolymer elastomer at room temperature (23°C) may be 200% or more, or 400% or more. The tensile elongation of the block copolymer elastomer is a value measured by a tensile test using a molded article formed solely from the block copolymer elastomer as a test piece.

The content of the block copolymer elastomer in the adhesive is 10% by mass or more based on the mass of the adhesive excluding the silane coupling agent and inorganic filler described below, from the viewpoint of elongation at -40 ° C. It may be 15% by mass or more, 20% by mass or more, or 25% by mass or more, and may be 50% by mass or less, 45% by mass or less, or 40% by mass or less.

The adhesive may further include an inorganic filler. In the case of a two-part adhesive, the first part, the second part, or both can contain an inorganic filler. By incorporating an inorganic filler, dripping when applied to an adherend can be more effectively suppressed. Examples of inorganic fillers include silica particles, calcium carbonate particles, mica, talc, boron nitride, and glass beads. The silica particles may be, for example, unmodified silica fillers, or silica fillers modified with an alkyl chain, a (meth)acryloyl group, or the like.

The content of the inorganic filler in the adhesive may be 0 to 50% by volume, 0 to 30% by volume, or 0 to 20% by volume based on the amount of adhesive. In the case of a two-part adhesive, the content of the inorganic filler in the first part and the content of the inorganic filler in the second part may be the same or different.

The adhesive may further contain a silane coupling agent. In the case of a two-part adhesive, the first part, the second part, or both can contain a silane coupling agent. The silane coupling agent may be, for example, a compound having a hydrolyzable silyl group and a functional group that reacts with at least one of an acrylic monomer, an epoxy resin, or a curing agent. The hydrolyzable silyl group is, for example, a group having a silicon atom and 1 to 3 alkoxy groups bonded to the silicon atom. The number of carbon atoms in the alkoxy group bonded to the silicon atom may be, for example, 1 to 4. Examples of functional groups that react with at least one of the acrylic monomer and the epoxy resin include amino groups such as primary amino groups and secondary amino groups, epoxy groups, mercapto groups, and (meth)acryloyl groups. . In this specification, compounds having a hydrolyzable silyl group and a (meth)acryloyl group are classified as silane coupling agents.

Specific examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane and 3-aminopropyltrimethoxysilane.

Commercially available silane coupling agents include, for example, KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KBM-4803, KBM-502, KBM-503, KBE-502, KBE-503. , KBM-5103, KBM-5803, KBM-602, KBM-603, KBM-903, KBE-903, KBE-9103P, KBM-573, KBM-575, KBM-802, and KBM-803 (Shin-Etsu Chemical (manufactured by Kogyo Co., Ltd., trade name) is available.

The content of the silane coupling agent in the adhesive may be 0 to 5% by mass, or 0 to 3% by mass based on the amount of the adhesive.

The adhesive may further contain other components if necessary. Examples of other components include pigments (eg, carbon black, titanium oxide particles), and elastomers.

In the case of a two-part adhesive, only one of the first part and the second part may contain a pigment. Alternatively, both the first liquid and the second liquid may contain pigments, and in that case, the pigment contained in the first liquid and the pigment contained in the second liquid may be different. When the adhesive set contains a pigment in this manner, when the first liquid and the second liquid are mixed, the mixed state of the first liquid and the second liquid can be visualized. By making the mixture of the first liquid and the second liquid into a mixed state in which the pigment is sufficiently and uniformly dispersed, better adhesive strength tends to be obtained.

The adhesives exemplified above are used to bond adherends together to obtain a desired bonded body having two or more adherends and an adhesive layer that adheres them. The adherend may be, for example, a molded body of metal such as steel, iron, copper, tinplate, aluminum, stainless steel, resin, or carbon fiber reinforced plastic (CFRP). The two or more adherends may be molded bodies made of the same or different materials.

A method of obtaining an adhesive body having two adherends using a two-component adhesive includes, for example, arranging the two adherends with a gap between them, and placing a second adherend in the gap between the two adherends. It includes injecting a first part and a second part and curing an adhesive that is a mixture of the first part and the second part. The first liquid and the second liquid may be mixed at approximately the same time that they are injected into the gap between the two adherends, or may be mixed and then injected between the two adherends. The first liquid and the second liquid, or a mixture thereof (adhesive), are injected between two adherends using, for example, a mixing nozzle.

There are two methods of obtaining an adhesive: applying an adhesive, which is a mixture of a first liquid and a second liquid, onto one adherend, and applying the applied adhesive between the two. The method may include bonding the adhesive to the adherend, and then curing the adhesive. By curing the adhesive, an adhesive layer is formed that is interposed between the two adherends and bonds them together.

The mixing ratio of the first liquid and the second liquid is determined by considering the stoichiometric ratio of the reaction between the acrylic monomer and epoxy resin contained in the first liquid and the curing agent contained in the second liquid. Adjusted for proper curing. For example, the volume ratio of the first liquid to the second liquid may be 0.5 to 5.0.

Curing conditions are adjusted to properly cure the adhesive. For example, the adhesive may be cured in an environment of 10 to 40°C. The curing time is adjusted, for example, between 1 hour and 1 week. The adhesive may be heated, and the heating temperature in that case may be, for example, 40 to 120°C.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples.

1. Preparation of adhesive set A first liquid containing an acrylic monomer, an epoxy resin, an elastomer, a silane coupling agent, and optionally an inorganic filler, and a second liquid containing a curing agent, an elastomer, and optionally an inorganic filler are prepared respectively. did. Tables 1 and 2 show the content of each component in the entire adhesive set including the first and second liquids in mass% based on the total amount of components other than the silane coupling agent and inorganic filler. show.

Details of each raw material shown in the table are as follows.
(1) Acrylic monomer/HDDA: 1,6-hexanediol diacrylate (Daicel Ornex Corporation)
(2) Epoxy resin/EP830: Bisphenol F type epoxy resin (EPICLON830, DIC Corporation)
・EP850: Bisphenol A epoxy resin (EPICLON850, DIC Corporation)
・jER871: Dimer acid diglycidyl ester (Mitsubishi Chemical Corporation)
(3) Curing agent/1,3-BAC: 1,3-bisaminomethylcyclohexane (Mitsubishi Gas Chemical Co., Ltd.)
(4) Curing accelerator/SIZ: 1H-imidazole (Shikoku Kasei Kogyo Co., Ltd.)
(5) Block copolymer elastomer LA3320: Triblock copolymer of methyl methacrylate-n-butyl acrylate-methyl methacrylate (methyl methacrylate unit: 15% by mass, MFR (190°C/2.16kg): 6.2g/ 10 minutes, Clarity LA3320, Kuraray Co., Ltd.)
(6) Other elastomers・RC110C: Acrylate polymer at both ends (XMAP RC110C, Kaneka Corporation)
(7) Silane coupling agent 3-glycidyloxypropyltrimethoxysilane (KBM-403, Shin-Etsu Chemical Co., Ltd.)
(8) Inorganic filler KS-1000: Heavy calcium carbonate, (Calfine Co., Ltd.)

2. tanδ of cured product
The first and second liquids of each adhesive set were mixed at a volume ratio of 2:1, and the formed adhesive was cured at 25°C for 7 days in a mold with a gap of 0.5 mm width. Ta. A test piece with a width of 5 mm and a length of 30 mm was cut out from the obtained plate-shaped cured body. The dynamic viscoelasticity of the obtained test piece in tensile mode was measured under the conditions of a temperature range of -60 to 150°C, a frequency of 1.0 Hz, and a heating rate of 10°C/min. In the viscoelastic curve obtained from the adhesive set of each example, tan δ shows a peak in the vicinity of -40°C and in the region of 0°C or higher, and the value of tan δ between the two peaks is approximately 0.3 or more. maintained a relatively high value. FIG. 1 is an example of a viscoelastic curve showing the relationship between viscoelasticity and temperature, which was obtained from the adhesive set of Example 2.

3. Shear strength A 0.5 mm spacer was placed between two cold-rolled steel plates with a size of 2 mm x 100 mm and a thickness of 0.5 mm so that the thickness of the adhesive was 0.5 mm. In this state, the first liquid and the second liquid were mixed using a mixing nozzle (manufactured by Tomita Engineering Co., Ltd.) and injected between the cold rolled steel sheets to prepare an evaluation sample. A tensile test was performed on the produced evaluation sample at a distance between chucks of 50 mm and a test speed of 5 mm/min, and the shear strength (MPa) with respect to the steel plate was measured. The measurement results of shear strength are classified according to the following criteria and shown in Tables 1 and 2. The adhesive of the example showed good shear strength. Table 3 shows the shear strength of Examples.
A: Shear strength 2 MPa or more B: Shear strength less than 2 MPa

Claims (7)

an epoxy resin containing dimer acid diglycidyl ester;
A block copolymer elastomer having a polymethyl methacrylate block and a poly n-butyl acrylate block,
Including adhesive. The adhesive according to claim 1, further comprising an acrylic monomer having two or more (meth)acryloyl groups. The adhesive according to claim 2, further comprising a curing agent containing a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group. The adhesive according to claim 3, wherein the nucleophilic reactive group is an aliphatic amino group. The adhesive according to any one of claims 1 to 4, further comprising an inorganic filler. The adhesive is
a first liquid containing the acrylic monomer and the epoxy resin;
a second liquid containing the curing agent;
an adhesive set comprising: at least one of the first liquid and the second liquid further containing the block copolymer elastomer;
The adhesive according to claim 3 or 4. having two or more adherends and an adhesive layer that adheres the two or more adherends,
An adhesive body, wherein the adhesive layer is a cured product of the adhesive according to any one of claims 1 to 5.

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