KR102095540B1 - Structural epoxy adhesives - Google Patents

Abstract

The present invention discloses a structural epoxy adhesive having excellent flame retardancy and adhesion properties by mixing an epoxy resin and a polyurethane resin capped with a capping agent containing dimethylpyrazole (DMP) at an appropriate ratio.
Structural epoxy adhesive according to the present invention is based on 100 parts by weight of epoxy resin, polyurethane resin 20 to 40 parts by weight, silane coupling agent 0.1 to 5 parts by weight, core-shell structure toughening agent 10 to 50 parts by weight, filler 10 ~ 30 parts by weight, 1 to 20 parts by weight of curing agent and 0.1 to 1 parts by weight of catalyst, the polyurethane-based resin is 100 to 40 parts by weight of polyol, 20 to 40 parts by weight of isocyanate, 0.1 to 5 parts by weight of chain extender and cap Characterized in that it contains 10 to 25 parts by weight of the extinguishing agent.

Description

Structural epoxy adhesive {STRUCTURAL EPOXY ADHESIVES}

The present invention relates to a structural epoxy adhesive, and more specifically, an epoxy-based resin and a polyurethane-based resin capped with a capping agent containing dimethylpyrazole (DMP) at a chain end in an appropriate proportion, thereby providing excellent flame retardancy and adhesion properties. It relates to a structural epoxy adhesive.

Structural adhesives can be defined as materials used to bond other high strength materials such as wood, composites or metals. Structural adhesives can be used in a variety of applications, such as the automotive and aerospace industries. It can also be used to replace or reinforce conventional fastening techniques such as screws, bolts, nails, staples, and soldering.

In order to be suitable as a structural adhesive, research has been conducted having high mechanical strength as well as excellent adhesion.

Background art related to the present invention includes Republic of Korea Patent Publication No. 10-2015-0067355 (published on June 17, 2015), the document describes UV-resistant epoxy structural adhesive.

An object of the present invention is to provide a structural epoxy adhesive excellent in flame retardancy and adhesive properties.

Structural epoxy adhesives according to the present invention for achieving the above object is based on 100 parts by weight of epoxy-based resin, 20 to 40 parts by weight of polyurethane-based resin, 0.1 to 5 parts by weight of silane coupling agent, toughening agent of core-shell structure 10 to 50 parts by weight, 10 to 30 parts by weight of the filler, 1 to 20 parts by weight of the curing agent and 0.1 to 1 parts by weight of the catalyst, and the polyurethane-based resin relative to 100 parts by weight of polyol, isocyanate 20 to 40 parts by weight, chain extension It characterized in that it contains 0.1 to 5 parts by weight and 10 to 25 parts by weight of the capping agent.

The polyurethane-based resin may be that the terminal made of isocyanate is capped with a capping agent containing dimethylpyrazole (DMP).

The chain extender may include one or more of amino groups, water-soluble aliphatic, alicyclic, aromatic, heterocyclic and hydrazine having 1 to 60 carbon atoms.

The polyurethane-based resin may have a weight average molecular weight of 10,000 to 70,000.

The core-shell structure toughening agent may include core-shell structure elastomer particles.

The filler may include halosite nanotubes (HNT).

The curing agent may include an amide-based curing agent.

The structural epoxy adhesive according to the present invention has an excellent effect in flame retardancy and adhesive properties by blending an epoxy resin and a polyurethane resin capped with a capping agent containing dimethylpyrazole (3,5-DMP) at a chain end in an appropriate ratio. have.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, a structural epoxy adhesive according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The structural epoxy adhesive according to the present invention is based on 100 parts by weight of an epoxy resin, 20 to 40 parts by weight of a polyurethane resin, 0.1 to 5 parts by weight of a silane coupling agent, 10 to 50 parts by weight of a toughening agent for a core-shell structure, and 10 fillers It contains ~ 30 parts by weight, 1-20 parts by weight of curing agent and 0.1-1 part by weight of catalyst.

Epoxy-based resins exist in a liquid state at room temperature, and are excellent in water resistance and adhesiveness. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and the like can be used.

The polyurethane-based resin refers to a polymer containing a urethane bond in the main chain and an isocyanate in the terminal. The polyurethane-based resin comprises 20 to 40 parts by weight of isocyanate, 0.1 to 5 parts by weight of chain extender, and 10 to 25 parts by weight of capping agent based on 100 parts by weight of polyol.

The polyol means a polyol containing two or more hydroxy groups. The polyol may be selected from a high molecular weight polyol having a number average molecular weight of 400 or more, a low molecular weight polyol having a number average molecular weight of less than 400, or any mixture thereof.

The isocyanate means an organic compound containing two or more isocyanate groups, that is, a polyisocyanate compound. The polyisocyanate compound usually contains 3 or less isocyanate groups. Di-isocyanate is the most preferred polyisocyanate compound.

The polyurethane-based resin preferably contains 20 to 40 parts by weight of isocyanate, and if it is outside this range, it may be insufficient to produce a polyurethane-based resin having desired properties.

The chain extender may include one or more of amino groups, water-soluble aliphatic, alicyclic, aromatic, heterocyclic and hydrazine having 1 to 60 carbon atoms. Examples of such chain extenders are hydrazine, ethylene diamine, piperazine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine , 2-methylpentamethylenediamine, triethylene triamine, isophorone diamine (or 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane), bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, polyethylene amine, polyoxyethylene amine and polyoxypropylene amine (eg Jeffamine, manufactured by TEXACO), and mixtures thereof.

It is preferable that the polyurethane-based resin contains 0.1 to 5 parts by weight of a chain extender. If it is outside this range, it is difficult to form an end portion made of isocyanate.

The capping agent includes dimethylpyrazole (3,5-DMP), and a terminal composed of isocyanate can be capped with dimethylpyrazole (3,5-DMP). The polyurethane-based resin preferably contains 10 to 25 parts by weight of the capping agent. If it is outside this range, capping at the distal end is insufficient.

The polyurethane-based resin may have a weight average molecular weight of 10,000 to 70,000. If it is outside this range, it may be difficult to control the viscosity of the polyurethane-based resin and the viscosity of the epoxy adhesive.

The silane coupling agent acts as a contact point in the middle to bond two different materials of inorganic materials such as glass, metal, mineral, etc., and organic materials such as organic polymers and adhesives. In the structural epoxy adhesive according to the present invention, the silane coupling agent can improve adhesion and increase the strength of the filler.

The silane coupling agent is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane and 3-chloro And one or more of propyl trimethoxysilane.

It is preferable that the structural epoxy adhesive contains 0.1 to 5 parts by weight of a silane coupling agent. If it is outside this range, it may be insufficient to exhibit an adhesion promoting effect.

The core-shell structure toughening agent may include core-shell structure elastomer particles. Specifically, the core-shell structure is made of rubber, and the types of resins included in each of the core and the shell may be different.

 The elastomer is, for example, natural rubber, styrene-butadiene rubber, polyisoprene, polyisobutylene, polybutadiene, isoprenebutadiene copolymer, neoprene, nitrile rubber, butadiene-acrylonitrile copolymer, butyl rubber, polysulfide elastomer , Acrylic elastomers, acrylonitrile elastomers, silicone rubbers, polysiloxanes, polyester rubbers, diisocyanate linked condensation elastomers, EPDM (ethylene-propylene diene rubber), chlorosulfonated polyethylene, fluorinated hydrocarbons, thermoplastic elastomers such as styrene and (AB) and (ABA) type block copolymers of butadiene or isoprene, (AB) n type multi-segment block copolymers of polyurethane or polyester, and the like.

It is preferable that the structural epoxy adhesive includes 10 to 50 parts by weight of a core-shell structure toughening agent. As a standard, the strength of 35Mpa should be satisfied at less than 20 ℃, 45Mpa at 20 ~ 30 ℃, and 42Mpa at temperatures exceeding 30 ℃. However, if it is less than 10 parts by weight, there is a problem that the impact peeling strength is out of spec. On the contrary, when it exceeds 50 parts by weight, the T-peel and impact strength do not deviate, but the shear strength deviates from the spec.

The filler imparts excellent dispersibility and flame retardancy in the structural epoxy adhesive.

It is preferred that the filler comprises a halosite nanotube (HNT).

The halosite nanotube is an aluminum silicate clay mineral composed of a 1: 1 ratio of aluminum and silicon, and is formed of nanoparticles in a tube shape. When the halosite nanotube is surface-treated with a silane, compatibility and interfacial adhesion in the adhesive can be further improved.

The length of the halosite nanotube may be 50 to 1000 μm, but is not limited thereto.

It is preferable that the structural epoxy adhesive contains 10 to 30 parts by weight of a filler. If it is outside this range, it may be difficult to exhibit excellent dispersibility and flame retardancy.

It is preferable that a curing agent contains an amide type curing agent. For example, dicyandiamide (DICY) may be used.

It is preferable that the structural epoxy adhesive contains 1 to 20 parts by weight of a curing agent. If it is less than 1 part by weight, or more than 20 parts by weight, viscosity control of the structural epoxy adhesive may be difficult.

The structural epoxy adhesive contains 0.1 to 1 part by weight of a catalyst to promote the reaction between components in the adhesive.

As the catalyst, one or more of aliphatic urea compounds and imidazole compounds may be used. Aliphatic urea compounds include, for example, p-chloro-N, N-dimethyl (Monuron), 3,4-dichlorophenyl-Ν, Ν-dimethyl (Diuron), N- (3-chloro-4-methylphenyl) -N ', N'-dimethylurea (Chlortoluron), tert-acrylic- or alkylene amines, such as benzyldimethylamine, 2,4 , 6-tris (dimethylaminomethyl) phenol, piperidine or derivatives thereof.

Further, the structural epoxy adhesive of the present invention may further include 0.1 to 1 part by weight of tetrabutylphosphonium tetrafluoroborate. When the tetrabutylphosphonium tetrafluoroborate is further included, viscosity control is easy, and excellent adhesive shear strength can be exhibited.

Looking at the specific embodiment of the structural epoxy adhesive as described above is as follows.

1. Preparation of structural epoxy adhesive

Examples 1 to 3, and Comparative Examples 1 to 5

Bisphenol A type epoxy resin (Huntsman), polyurethane resin, 3-glycidoxypropyl trimethoxysilane (Sigma Aldrich) as a coupling agent, butyl rubber (average diameter 10 µm) as a toughening agent, and filler Structural epoxy by mixing HNT surface-treated with 3-chloropropyl trimethoxysilane as DICY (dicyandiamide, Sigma Aldrich), 3-phenyl-1,1-dimethylurea catalyst as the composition of Table 1 and Table 2 as a curing agent An adhesive was prepared. The core-shell structure is composed of butyl rubber, and the core contains chlorosulfonated polyethylene resin, and the shell contains polyurethane resin.

The polyurethane resin was mixed with 30 parts by weight of isocyanate, 5 parts by weight of hydrazine chain extender and stirred with respect to 100 parts by weight of polyol, and capped 90% of the end by adding 25 parts by weight of 3,5-DMP as a capping agent. The prepared polyurethane resin has a weight average molecular weight of 20,000, a main chain containing a urethane bond, and a resin composed of isocyanates capped with 3,5-DMP.

The composition of Table 1 and Table 2 describes parts by weight based on 100 parts by weight of bisphenol A-type epoxy resin.

Example 4

A structural epoxy adhesive was prepared under the same conditions as in Example 1, except that it further contained 1 part by weight of tetrabutylphosphonium tetrafluoroborate.

[Table 1]

[Table 2]

2. Method for evaluating physical properties and results

The following items were evaluated using the structural epoxy adhesives prepared in Examples 1 to 4 and Comparative Examples 1 to 5, and the measurement results are shown in the following [Table 3].

(1) Shear strength (MPa / inch): measured according to ASTM D-1876-01.

(2) T-shaped peel strength (N / 25mm): measured according to ASTM D-1002-05.

(3) Impact peel strength (N / 25mm): Measured according to ISO 11343.

(4) Flame retardance: measured according to the UL-94 method.

[Table 3]

Referring to Tables 1 to 3, Examples 1 to 4 satisfying the structural epoxy adhesive composition of the present invention showed high overall results in terms of shear strength, peel strength, and flame retardancy. In particular, Example 4 was tetrabutylphos. 1 part by weight of phonium tetrafluoroborate By including, it shows the result of higher shear strength than Examples 1 to 3.

However, in Comparative Examples 1 to 5, compared with Examples 1 to 4, the result was low, or physical properties were not measured.

Therefore, the structural epoxy adhesive according to the present invention, by mixing the epoxy resin and a polyurethane resin having a capped end in an appropriate ratio, and by including a filler, shear strength 30 ~ 50 MPa / inch, T-shaped peel strength 300 ~ 320 It can exhibit N / 25mm, impact peel strength 40 ~ 50 N / 25mm and excellent flame retardancy.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and may be manufactured in various different forms, and having ordinary knowledge in the art It will be understood that a person can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (7)

With respect to 100 parts by weight of the epoxy resin, 20 to 40 parts by weight of the polyurethane resin, 0.1 to 5 parts by weight of the silane coupling agent, 10 to 50 parts by weight of the toughening agent containing the core-shell elastomer particles, 10 to 30 parts by weight of the filler Part, 1 to 20 parts by weight of a curing agent and 0.1 to 1 part by weight of a catalyst comprising an aliphatic urea compound,
The polyurethane-based resin comprises 20 to 40 parts by weight of isocyanate, 0.1 to 5 parts by weight of chain extender, and 10 to 25 parts by weight of capping agent, based on 100 parts by weight of polyol,
The polyurethane-based resin is capped with a capping agent containing dimethylpyrazole (DMP) at the end composed of isocyanate,
The filler is a structural epoxy adhesive, characterized in that it comprises a halosite nanotubes (HNT) surface-treated with silane.
delete According to claim 1,
The chain extender is a structural epoxy adhesive, characterized in that it comprises at least one of an amino group, a water-soluble aliphatic, alicyclic, aromatic, heterocyclic and hydrazine having 1 to 60 carbon atoms.
According to claim 1,
The polyurethane-based resin is a structural epoxy adhesive, characterized in that the weight average molecular weight of 10,000 to 70,000.
delete delete According to claim 1,
The curing agent is a structural epoxy adhesive comprising an amide-based curing agent.