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WO-2026093045-A1 - CURABLE COMPOSITION BASED ON THIOL-CURING EPOXIDES AND USE FOR BONDING, POTTING, SEALING AND/OR COATING

WO2026093045A1WO 2026093045 A1WO2026093045 A1WO 2026093045A1WO-2026093045-A1

Abstract

An actinic radiation-setting and heat-curable composition comprises: (A) an epoxy-containing compound; (B) a thiol; (C) a nitrogen-containing compound as accelerator; (D) a radically curable component comprising a (meth)acrylate (D1), wherein the (meth)acrylate (D1) is at least difunctional; (E) a radical photoinitiator; and (F) a stabilizer. The thiol (B) comprises tris(3-mercaptopropyl)isocyanurate, the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 to 0.250, and the (meth)acrylate (D1) has an equivalent weight of at least 100.0 g/mol.

Inventors

  • Ruiz Perez, Julian
  • Fischer, Beatrix

Assignees

  • DELO INDUSTRIE KLEBSTOFFE GMBH & CO. KGAA

Dates

Publication Date
20260507
Application Date
20251020
Priority Date
20241030

Claims (13)

  1. 1. A mass that can be fixed by actinic radiation and hardened by heat, comprising the following components: (A) an epoxy-containing compound; (B) a thiol; (C) a nitrogen-containing compound as an accelerator; (D) a radically curable component comprising a (meth)acrylate (D1) wherein the (meth)acrylate (D1) is at least difunctional; (E) a radical photoinitiator; and (F) a stabilizer; characterized in that the thiol (B) comprises tris(3-mercaptopropyl)isocyanurate, the ratio of the epoxide groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 to 0.250, and the (meth)acrylate (D1) has an equivalent weight of at least 100.0 g/mol.
  2. 2. Mass according to claim 1, wherein the epoxy-containing compound (A) has an equivalent weight of at most 300 g/mol.
  3. 3. Mass according to claim 1 or 2, wherein the epoxide-containing compound (A) comprises an aromatic epoxide.
  4. 4. Composition according to any of the preceding claims, wherein the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.020 to 0.225
  5. 5. Mass according to any one of the preceding claims, wherein the thiol (B) comprises at least 70 wt.% tris(3-mercaptopropyl)isocyanurate, based on the total weight of the thiol (B)
  6. 6. Mass according to claim 5, wherein the thiol (B) consists of Tris(3-mercaptopropyl)isocyanurate.
  7. 7. Composition according to any of the preceding claims, wherein the (meth)acrylate (D1) has a homopolymerization glass transition temperature of 60 °C or higher.
  8. 8. Mass according to any of the preceding claims, wherein the radically curable component further comprises another ethylene unsaturated compound (D2) that is different from the (meth)acrylate (D1).
  9. 9. Mass according to any of the preceding claims, wherein the mass comprises the following components, each based on the total weight of components (A) to (F): (A) 0.5 to 15 wt.% of the epoxy-containing compound; (B) 15 to 70% by weight of the thiol; (C) 0.5 to 30 wt.% of the nitrogen-containing compound as an accelerator; (D) 20 to 80 wt.% of the radically curable component; (E) 0.01 to 5 wt% of the radical photoinitiator; and (F) 0.01 to 2 wt% of the stabilizer.
  10. 10. Mass according to claim 9, wherein the mass further contains up to 80 wt.% of additives as component (G), based on the total weight of the mass.
  11. 11. Mass according to claim 9 or 10, wherein the mass contains 0.5 to 12.0 wt.% of the epoxy compound (A), based on the total weight of components (A) to (F).
  12. 12. Mass according to any one of claims 9 to 11, wherein the mass contains 40 to 80 wt.% of the radically curable component (D), based on the total weight of components (A) to (F).
  13. 13. Use of the compound according to any of the preceding claims for bonding, potting, sealing and/or coating substrates. ...

Description

DELO Industrial Adhesives GmbH & Co. KGaA Our reference number: D 3405 WO WS/TH Curable compound based on thiol-curing epoxies and used for bonding, potting, sealing and/or coating. AREA OF INVENTION The invention relates to a mass based on thiol-curing epoxides that can be fixed by actinic radiation and hardened by heat. Furthermore, the invention relates to the use of the mass for bonding, potting, sealing and/or coating substrates. TECHNICAL BACKGROUND In the field of adhesive technology, there is a growing need for very short curing times to achieve high cycle rates. Light-curing adhesives offer one solution. However, the substrates must be sufficiently translucent to allow the adhesives to cure uniformly and with minimal stress under light exposure. Other curing mechanisms, such as heat or moisture, are significantly slower, and fast curing speeds are often accompanied by drastically reduced processing times. Dual-curing adhesives offer an alternative, combining the advantages of rapid light curing with a second curing mechanism. For example, irradiating fillet welds allows for quick fixation of the components, which can then be held in position without further mechanical support. Light curing drastically reduces the time required to process a component in subsequent steps. The second curing mechanism ensures final curing and guarantees the permanent mechanical strength and chemical resistance of the adhesive bond. This final curing can also take place separately in time and space from the light curing. Crucially, this requires the formation of a network that is as homogeneous as possible. In other words, the... The network formed by dark curing does not differ significantly from the network formed by light curing. For this purpose, epoxy-thiol systems can be advantageously equipped with light-curing capability. The heat-curing adhesive is typically combined with a (meth)acrylate component and a photoinitiator. Such resins also have the advantage that heat curing can be accelerated by adding an amine component, thus enabling the bonding or potting of temperature-sensitive substrates. Application areas range from electronics manufacturing and medical technology to optics and the automotive industry. WO 2005/052021 A1 discloses a one-component compound comprising, in addition to an epoxy resin, a latent curing accelerator, and at least a difunctional thiol, a radiation-curable compound based on a (meth)acrylate and a photoinitiator. The proportion of the thiol component is limited to a maximum of 5 wt.% to achieve a sufficient processing time. WO 2016/143777 A1 describes the challenges encountered in the formulation of thiol-containing compounds intended for UV curing. The high reactivity of thiols and acrylate-containing components leads to significantly shortened processing times, preventing the use of these compounds as adhesives. This problem is solved within the scope of the cited invention by the addition of a thiol hardener based on glycolurils. The described thiol hardeners are also free of hydrolysis-sensitive ester groups and are particularly suitable for increasing the moisture resistance of the cured compounds. Further formulation examples based on glycoluril derivatives can be found in WO 2016/143815 A1. Dual-curing formulations based on ester-free thiol hardeners are also described in WO 2018/047849 A1 and WO 2023/065802 A1. Dual-curing compounds are particularly well-suited for fixing precisely aligned components during the assembly of camera modules and for subsequent curing. Avoiding stray light is an important consideration here. Quality feature. EP 4 317 234 A1 discloses dual-curing epoxy-thiol compounds for this purpose, which require a minimum amount of an epoxy-containing component to produce matte surfaces during heat curing. EP 3 724 253 B1 describes dual-curing compounds that require low temperatures for heat curing and simultaneously offer working times of up to several days at room temperature. These properties are achieved, among other things, through a special stabilizer combination consisting of a sulfonyl isocyanate and an acid. Further dual-curing formulations can also be found in WO 2023/286699 A1 and WO 2023/286700 A1. Current developments are placing ever-increasing demands on cycle times, requiring continuous optimization of fixing speeds and strengths, while maintaining moderate curing temperatures and long processing times. The materials disclosed in the prior art are not suitable for meeting these increasing demands. SUMMARY OF THE INVENTION One object of the present invention is to avoid the disadvantages of compositions known from the prior art and to provide masses, in particular single-component masses, that can be fixed by actinic radiation and cured by heat and are characterized by rapid light fixation and high light fixation strength combined with long processing times. The object of the invention is further to provide masses that harden at low temperatures