JPH05105861A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain an adhesive compsn. having a well-balanced performance required of the adhesive, i.e., quick gelation at room temp. as well as hardening in a short time, a high shear strength, a high T-peel strength, an adhesion to an oil-contaminated surface, and a water resistance. CONSTITUTION:An adhesive compsn. comprises an epoxy resin, a mercapto curing agent in an amt. enough to harden the epoxy resin, and a polysulfied adduct modified so as to inactivate part of the terminal -SH groups thereof against epoxy groups.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for manufacturing parts made of metal and fiber reinforced composites (for example, SMC, glass fiber reinforced polyester resin, transfer resin moldings, etc.) and automobiles, boats and many other products. The present invention relates to a structural adhesive for adhering to various substrates similar or dissimilar to the parts obtained.

[0002]

2. Description of the Related Art The SMC is a continuous material composed of thermosetting resin, reinforcing fibers and additives required for molding process and product performance, such as a catalyst, a fine particle filler, a mold release agent, a pigment and a dimensional stabilizer. It is defined as the sheet that did. Fiber-reinforced polyester (FRP) is a polyester thermosetting resin containing reinforcing fibers and usual additives.
These materials are generally called fiber reinforced composites, reinforced composites or simply composites.

A typical one of the structural adhesives useful for adhering the composite to the same or different adherends is a two-component polyurethane adhesive. This adhesive is used by mixing a prepolymer and a curing agent immediately before use. The appropriate mixing ratio of the two compounds varies depending on the reactivity of each of the prepolymer and the curing agent. However, it is the present situation that an actual mixing person relies on the skill of an operator to find an appropriate mixing ratio, and even when an automatic mixing machine is used, a considerable loss occurs in the mixing process.

Another example of a structural adhesive useful for adhering composites to the same or different adherends is an epoxy-based adhesive. A typical example of this adhesive composition contains a polyfunctional epoxy resin and is cured by a separately prepared curing agent. The curing rate and the physical properties of the cured product mainly depend on the curing agent, that is, the composition of the adhesive itself. Therefore, the composition can be changed to achieve the properties desired by the user.

When using a structural adhesive, the adhesive is applied to the surface of the material to be bonded, for example a metal,
The surface to be adhered of the adherend (regardless of the same kind or different kind of material) is pressed against the above-mentioned application portion. Since both the adhesive and adherent surfaces are often not flat, it is desirable for the adhesive used to have the ability to fill depressions of various depths. Further, the adhesive must be fluid and non-curing until the adhesive surface and the adherend surface are adhered to each other. Adhesives that cure too quickly have poor flexibility and are not suitable for assembly process applications. For this reason, the time during which the adhesive has fluidity has been measured, and this time is called the pot life. The two substances to be adhered are, for example, 70 to 19
It is preferable that the adhesive itself is allowed to cure in a furnace at a temperature of 0 ° C. for about 5 minutes, but it is generally preferable that the adhesive itself is left at room temperature for one day to several days, for example, three days, and then cured.

Typical examples of epoxy-based structural adhesive compositions are USP 4,707,518 and 4,803,232.
Issue No. 4,623,702, No. 4,316,979
No. 3, ibid. 3,101,326, ibid. 4,689,389
No. 3,882,091, No. 4,017,554 and the like. Epoxy resin, rubber modifier, amine curing agent, mercapto curing agent, amide curing agent,
There have been proposed methods for producing a high-strength adhesive composition by combining a number of Lewis acids and the like.

[0007]

However, all of the above-mentioned adhesive compositions have the following performances (1) to (6) (1) room temperature premature gelation and curing which are usually required for adhesives (2). High shear strength (3) High T-peel strength (4) Adhesion to contaminated oil surface (5) Curing completion in a relatively short time (6) It is hard to say that it has a good balance of water resistance. Therefore, an object of the present invention is to provide an adhesive composition having the above-mentioned various performances in a well-balanced manner.

[0008]

Means for Solving the Problems As a result of intensive investigations in view of such circumstances, the present inventors have found that an adhesive composition containing an epoxy resin and a specific amount of a mercapto-based curing agent and a specific polysulfide adduct which will be described later. It was found that the above object can be achieved, and the present invention has been completed.

That is, the present invention provides the following component (a),
(B), and (c) (a) Epoxy resin (b) Epoxy resin (a) in an amount necessary for curing the mercapto-based curing agent (c) A part of the terminal -SH is made inactive to the epoxy group. The present invention provides an adhesive composition containing a polysulfide adduct modified as described above.

The epoxy resin used in the present invention may be any one of low molecular weight or high molecular weight as long as it has an epoxy value of 1 or more (that is, the average number of epoxy groups per mole is 1 or more). Can be used. Preferred epoxy resins include, for example, ethylene glycol, triethylene glycol, 1,2-propylene glycol,
Polyglycidyl ethers of polyhydric polyols such as 1,5-pentanediol, 1,2,6-hexanetriol, 2,2-bis (4-hydroxycyclohexyl) propane; for example, oxalic acid, succinic acid, glutaric acid, Polyglycidyl esters of aliphatic or aromatic polycarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, dimerized linoleic acid; bisphenol A, bisphenol F, 1,1-bis (4-hydroxyphenyl) ethane, 1 Examples thereof include polyglycidyl ethers of polyphenols such as 1,1-bis (4-hydroxyphenyl) isobutane and 1,5-dihydroxynaphthalene; novolac resins and the like or a mixture thereof. Particularly preferred are polyglycidyl ethers such as bisphenol A and bisphenol F, and phenol novolac resins. Further, rubber-modified epoxy resin can also be used. Examples of these include an epoxy compound obtained by reacting with a liquid or solid butadiene- (meth) acrylonitrile having at least two functional groups capable of reacting with an epoxy group, such as a carboxyl group, a hydroxyl group mercapto group, and an amino group. ..

Examples of the mercapto-based curing agent used in the present invention include mercaptoalkyl esters of polycarboxylic acids; polythioglycolic acid esters; mercaptocarboxylic acids; mercaptocarboxylic acids and linear chains having at least 7 carbon atoms. Ester with glycol glycol;
Reaction products of condensates of polyalkylene glycols with epichlorohydrin or organic silicone compounds and NaSH; reaction products of epoxidized dienes with hydrogen sulfide or alkyl mercaptans; glycidyl esters or glycidyl dimerized fatty acids or alcohols Reaction product of ether and hydrogen sulfide; chlorohydrin ester of dimerized fatty acid or alcohol or ether and NaSH
And reaction products of monoepisulfide, di-, tri-mercaptodiphenyl oxide, polyalkylene episulfides having a thiol group and an amino group, and reaction products of tris (mercaptoethyl) trioxane with hydrogen sulfide or ammonia. These mercapto-based curing agents are commercially available as can be seen in the examples below. In addition, for example, "Epoxy Resin
s, Chemistry, and Technology
y "2nd Ed., revised and exp
and edited, edited by C. A. May, Ma
rcell Dekker Inc. (New Yor
kN. Y. , 1988).

The mercapto type curing agent is added in an amount necessary for curing the epoxy resin. The amount added is
Although it varies depending on the type of epoxy resin used, specifically, 30 to 150 parts by weight is used with respect to 100 parts by weight of the epoxy resin having an epoxy equivalent of 190.

Polysulfide used in the present invention
The adduct epoxides a part of the terminal -SH of polysulfide.
Inactive towards Si groups (ie reactive towards epoxy groups)
Is not present)). here,
"Terminal-SH" is present on the polysulfide side chain -S
It also includes H. Police that meet these conditions
Ruffide adducts are, for example, polysulfide compounds
After reacting with the terminal -SH in the polysulfide compound,
Compounds that do not react with the epoxy groups in the adhesive composition (below
Below, referred to as modified compound)
can do. Polysulfidation used here
The compound has a structure represented by disulfide bonds.
A compound having at least one resulfide bond
For example, HS- (C₂H_Four-O-CH₂-O-
C₂H _Four-S-S)_n-C₂H_Four-O-CH₂-OC₂H_Four−
SH (n = 2-5) is mentioned. As a commercial product, L
P-70, LP-3, LP-2, LP-32, LP-1
2, LP-55, LP-31, etc. (Thiokol Ch
(manufactured by electronic Co.). The above compounds are
5 to 50% by weight, preferably 4 to 5% by weight of the bright adhesive composition
40% by weight is used. Further, as the modified compound,
Poxide (However, the hydroxyl group of this epoxide is sterically
Be well protected and not react with other epoxy groups
Required), carboxylic acid, isocyanate, etc. or these
A mixture of Particularly preferably isocyanate
And phenylisocyanate is the most preferred
Yes.

The terminal -SH in the polysulfide adduct thus obtained is at least a part thereof, preferably about 5%.
% Is required to be inactive with respect to the epoxy group, but the inactive ratio is more preferably 50% or more, further preferably 100%.

The adhesive composition of the present invention may contain an amine-based or amide-based curing agent in addition to the mercapto-based curing agent. In addition, polyamine and / or polyamide catalysts, particulate fillers, thixotropic agents, opacifying agents, and other additives commonly used in adhesives can optionally be used.

[0016]

EFFECTS OF THE INVENTION The adhesive composition of the present invention can be cured at room temperature and exhibits the following six performance items in a well-balanced manner. That is, premature gelation within 30 minutes, high shear strength (for example, 1000 psi or more), high T-peel strength (for example, 15 to 20 pli or 1 b / inch), alcohol-cleaned aluminum surface, contaminated surface, oil-contaminated surface iron, etc. Adhesiveness to an adherend and SMC, complete curing in a relatively short time (for example, about 3 days at room temperature) (reaching the maximum shear strength), and water resistance are excellent. Moreover, it is possible to meet the demand from the user side such as a suitable viscosity at the time of use, a simple usage method and an operation. The adhesive composition of the present invention is particularly effectively used when structural adhesion of a metal or the like is performed at room temperature.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In addition, unless otherwise indicated, the percentage display in the examples indicates% by weight.

Example 1 2 mol of glycidylpropyltrimethoxysilane (Do
w Corning Z-6040) and 1 mol of LP-3
Polysulfide polymer (average molecular weight 1,000, nD
1.5649, pour point 26 ° C, flash point (PMCC) 174 ° C,
2.0% curing agent, Thiokol Chemical
Div. The reaction of Trenton, NJ) was carried out in 200 ml of methylene chloride under reflux for 5 hours. The resulting solution was evaporated completely to 100% solids. This solid is I
As a result of R analysis, the oxysilane ring in the silane was completely disappeared, and further -SH was completely disappeared (polysulfide addition compound No. 1). 2 moles of Cardura E ester (Versatic 9
Glycidyl ester of 11 acid, Shell Chemi
cal) and 1 mol of LP-3 polysulfide polymer are reacted in 300 ml of methylene chloride under reflux for 6 hours,
The product was dried. As a result of IR analysis, the thiol group was an inactive thioether group (polysulfide addition compound No. 2).

Example 2 0.0542 mol of LP-3 polysulfide, 0.11
A mole of phenyl isocyanate, 150 ml of methylene chloride and 0.3 g of stannous octoate were placed in a reaction flask and reacted under reflux for 7 hours. Then, it was left at room temperature overnight. Place the resulting yellow solution in a rotary evaporator,
When the solvent was completely evaporated, a viscous yellow liquid was obtained (designated as polysulfide addition compound No. 3).
As a result of IR analysis, all isocyanate groups in the raw material and −
It turned out that the SH had reacted. 2 mol of phenyl isocyanate and 1 mol of LP-32 polysulfide polymer (average molecular weight 4,000, nD 1.5689, pour point 7 ° C, flash point (PMCC) 212 ° C, crosslinker 0.5
%, Manufactured by Thiokol Chemical Co.) was used to carry out the same reaction as above. As a result of analysis of the product (designated as polysulfide addition compound No. 4), the presence of free phenylisocyanate groups was not recognized.

Example 3 In the same manner as in Examples 1 and 2, a polysulfide addition compound (designated as No. 5) was prepared using phenyl isocyanate and LP-32. Thereafter, this was mixed with various amounts of unreacted LP-32 to obtain an adhesive composition containing polysulfide adducts each having a different amount of -SH. The composition is shown in Table 1.

[0021]

[Table 1]

The hardness after 24 hours of curing with the above compositions 1 to 5 was measured (Shore D-2 hardness). The results are shown in Table 2.

[0023]

[Table 2]

From Tables 1 and 2, the adhesive composition of the present invention containing the inactive polysulfide addition compound (No. 5) in an amount of 25% (4) showed considerably good results.
% Content (2) shows good results, and further 100
It can be seen that the composition containing 1% (1) shows remarkably good results.

Example 4 The polysulfide addition compound shown in Example 2 (No.
Compositions were prepared by changing the mixing ratio of 4) and subjected to a shear test and a T-peel test. The composition and results are shown in Table 3.

[0026]

[Table 3]

From the results in Table 3, it can be seen that the compositions containing the two mercapto curing agents and containing the inactive polysulfide adduct show the highest shear value and peeling value.

Example 5 The adduct of Epon 828 with LP-3 and LP-32 used in Example 3 was prepared according to US Pat. No. 4,316,979.
It was synthesized according to the description in Japanese Patent Publication (polysulfide addition compound Nos. 6 and 7). Comparison was made between these addition compounds, unmodified LP-3 and LP-32 polysulfide polymers, and those modified with phenylisocyanate (polysulfide addition compounds No. 3 and 4).
The adhesive composition was prepared according to the composition shown in Table 3. The results are shown in Table 4.

[0029]

[Table 4]

From the results shown in Table 4, the polysulfide compound modified with phenyl isocyanate was excellent in T-
It can be seen that it exhibits peeling performance.

Example 6 The compositions shown in Table 5 were prepared and tested for the items shown in Table 5. The results are shown in Table 5.

[0032]

[Table 5]

From the results shown in Table 5, the residual rate of shear strength after 14 days of immersion in water was large in the composition C of the present invention.

Example 7 A comparison of the composition containing no polysulfide polymer, the composition containing the polysulfide adduct of the present invention, and the composition containing unmodified polysulfide in shear strength and T-peel strength was compared. went. Table 3
And according to the composition shown in Table 5. The results are shown in Table 6.

[0035]

[Table 6]

From the results in Table 6, it can be seen that the adhesive composition of the present invention exhibits good shear strength and T-peel strength.

Example 8 The mechanical properties of the composition using the polysulfide addition compound included in the present invention were measured and compared with the composition using the unmodified polysulfide. Preparation of the composition is Capc
The same procedure as described in Tables 3 and 5 was performed using ure WR-6. The results are shown in Table 7.

[0038]

[Table 7]

From the results in Table 7, it can be seen that the adhesive composition of the present invention exhibits good mechanical properties.

Example 9 Tests shown in Table 8 were conducted according to the composition shown in Table 3 using the two kinds of polysulfide adducts shown in Table 8. The results are shown in the table.

[0041]

[Table 8]

From the results in Table 8, it can be seen that the adhesive of the present invention strengthens the adhesiveness to the aluminum surface washed with isopropanol and Alconox.

Example 10 To investigate the cure rate using the polysulfide adduct of the present invention, the change in shear strength as a function of time was measured and the results are set forth in Table 9. In addition, the adhesive composition,
It was prepared according to the composition shown in Table 3 and Table 5.

[0044]

[Table 9]

From the results shown in Table 9, it can be seen that in the composition containing the polysulfide adduct of the present invention, the initial curing is fast, and the curing after 14 days is advanced. Moreover, the residual rate of the shear strength is high even after immersion in water for 14 days, which is 28% of the case where the unmodified polysulfide polymer LP-32 is used.
, The strength of 34% was maintained.

Example 11 Adhesion to oil-contaminated aluminum surfaces and clean aluminum surfaces was tested using the inventive adhesive compositions of the compositions shown in Table 10 and other compositions as a comparison, and the results Is shown in Table 10.

[0047]

[Table 10]

From the results shown in Table 10, it can be seen that the detergent composition of the present invention has excellent adhesion to the contaminated surface.

Claims (1)

[Claims] 1. The following components (a), (b), and (c) (a) epoxy resin (b) mercapto-based curing agent in an amount necessary to cure the epoxy resin (a) (c) terminal- An adhesive composition comprising a polysulfide adduct obtained by modifying a part of SH so as to be inactive with respect to an epoxy group.