Adhesive Composition with Retarding Additive

Abstract

The present disclosure relates to an adhesive composition comprising one or more (meth)acrylate ester monomers, a catalyst system and a retarding additive, wherein the retarding additive is a secondary amine; and to the use of secondary amines as retarding agents for adhesive compositions comprising methacrylate monomers.

Claims

1. An adhesive composition comprising one or more (meth)acrylate ester monomers, a catalyst system and a retarding additive, wherein the retarding additive is a secondary amine.

2. The adhesive composition according to claim 1, wherein the secondary amine is a secondary amine comprising more than one secondary amine group.

3. The adhesive composition according to claim 2, wherein the secondary amine is a secondary aryl amine.

4. The adhesive composition according to claim 3, wherein the secondary aryl amine is selected from compounds having formula (1) ##STR00004## wherein R1 and R2 are independently selected from C.sub.6-C.sub.18 alkyl groups, formula (2) ##STR00005## wherein R1 is selected from C.sub.6-C.sub.18 alkyl groups and R2 is selected from hydrogen or C.sub.1-C.sub.6 alkyl groups, or formula (3) ##STR00006## wherein R1 and R2 are independently selected from hydrogen or C.sub.1-C.sub.6 alkyl groups.

5. The adhesive composition according to claim 1, wherein the retarding additive is selected from cyclic secondary amines.

6. The adhesive composition according to claim 5, wherein the cyclic secondary amine is a 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

7. The adhesive composition according to any of the preceding claims, wherein the retarding additive is comprised in an amount of 1% to 5% by weight, based on the total weight of the adhesive composition.

8. The adhesive composition according to any of the preceding claims, wherein the one or more methacrylate ester monomers are comprised in an amount of 10% to 90% by weight, based on the total weight of the adhesive composition.

9. Use of a secondary amine or a mixture of secondary amines as a retarding additive for an adhesive composition comprising methacrylate monomers.

Description

EXAMPLES

[0039] The following materials were used in preparation of the example formulations:

THFMA: tetrahydrofurfuryl methacrylate, obtained as Sartomer® SR203H available from Sartomer
EHMA: ethylhexyl methacrylate, obtained as VISIOMER® EHMA available from Evonik
MAA: methacrylic acid, obtained available from Sigma Aldrich
Silquest A174: vinyl silane, obtained from Momentive
Maleic acid: obtained from DSM
VULKANOX® BHT: butylated hydroxytoluene, obtained from Lanxess
PARALOID TMS2670J: MBS core shell impact modifier, obtained from Dow
PARALOID EXL 2300G: AIM core shell, obtained from Dow
Sartomer® SR348C: ethoxylated bisphenol A dimethacrylate, obtained from Sartomer
CAB-O-SIL® TS720: treated fumed silica, obtained from Cabot
Trigonox® C: t-butyl peroxybenzoate, obtained from AkzoNobel
Soligen copper: obtained from Borchers
VULKANOX® HS LG: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, obtained from Lanxess
KGL097: 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine, obtained from Lake Chemicals
The amounts shown in Table 2 are in weight %.

Resin

[0040] First, maleic acid was dissolved into THFMA at room temperature (about 25° C.). All components for the resin in Table 2 were added together and mixed using a speed mixer (centrifugal mixer) until a homogenous product resulted.

Hardener

[0041] A solution of 200 ppm of soligen copper in EHMA was prepared. All components for the hardener in Table 2 were added together and mixed using a speed mixer (centrifugal mixer) until a homogenous product resulted. VULKANOX® HS LG was ground prior to addition, and then dissolved in post addition into the matrix.

TABLE-US-00002 TABLE 2 Example 1 Example 2 Resin VISIOMER ® EHMA 10.1 10.1 Methacrylic acid 3 3 Silquest A174 1 1 Solution 6% Maleic 42 42 acid/94% THFMA VULKANOX ® BHT 0.2 0.2 PARALOID TMS2670J 10 10 Sartomer ® SR348 C 25 25 CAB-O-SIL ® TS720 6.5 6.5 Trigonox C 2.2 2.2 Hardener VISIOMER ® EHMA 47.5 45.5 Soligen copper 12.5 12.5 solution 200 ppm in Visiomer EHMA KGL097 5 5 PARALOID EXL 2300G 8 8 Sartomer ® SR348 C 25 25 CAB-O-SIL ® TS720 2 2 VULKANOX ® HS LG — 2

TABLE-US-00003 TABLE 3 Test Example 1 Example 2 Exotherm test Time to 32° C. 1 min 3 min 30 s Maximum 140° C. 135° C. temperature Time to max 4 min 7 min 30 s exotherm Lap Shear Stainless 23 CF/SCF 20 CF Strength Steel CFRP 13 CF 11 CF ABS  5 CF/SDF 5 CF Tensile Tensile 32 30 properties strength (MPa) Modulus (MPa) 880 860 Elongation at  12  10 break (%) DMA Glass  69° C.  68° C. transition temperature Tests performed on mix ratio 1:1 by weight of resin and hardener

Exotherm Test at 23° C.

[0042] Mix 7 g resin+7 g hardener into a cup, then transfer into a silicon mold and follow exotherm reaction over time with a thermocouple.

[0043] Record time to reach 32° C., maximum temperature, and time to reach maximum temperature.

Lap Shear Strength (ISO 4587)

[0044] The CFRP (Carbon Fibre Reinforced Polymer) and ABS (Acrylonitrile Butadiene Styrene) substrates were degreased by wiping with isopropanol and abraded. The aluminum substrates were sandblasted and rinsed with acetone. The adhesive composition was dispensed onto one surface of the substrate pair. The two surfaces were mated and held to each other with a compressor-type tubing clamp. The overlap area was 25.0 mm×12.5 mm. The bonded joints were left to cure for 24 h at 23° C. The clamps were then removed and the bonded joints were tested for tensile shear strength (TSS) according to ISO 4587 at crosshead speed of 10 mm/min. The TSS values were recorded in megapascals (MPa). The average value of 3 tested joints is reported.

Tensile Properties (ISO 527)

[0045] A plate of 2 mm thickness was prepared under press and cured for 1 week at room temperature (about 25° C.) before to be tested according to ISO 527.

Dynamic Mechanical Analysis (ISO 6721)

[0046] Samples from the same plate were tested in torsion according to ISO 6721 from −100 to +150° C. to determine glass transition temperature.

[0047] The above test results show that the addition of the retarding additive in the composition of Example 2 according to the present disclosure slows down the reactivity of the system without impacting either the adhesion, tensile properties or glass transition temperature.

[0048] The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed disclosure.