Cyanoacrylate compositions

Abstract

The present invention relates to a curable cyanoacrylate composition suitable for use as an adhesive composition, for example as an adhesive composition in the form of an adhesive tape.

Description

background Technical Field

[0002] The present invention relates to curable cyanoacrylate compositions which are suitable for use as adhesive compositions, for example in the form of tapes.

[0003] A brief description of the relevant technology

[0004] Cyanoacrylate monomers that are solid at room temperature are known, such as phenylethyl cyanoacrylate, ethylhexyl cyanoacrylate, and hexadecyl cyanoacrylate. Such room temperature solid cyanoacrylate monomers can be used to prepare cyanoacrylate products in the form of rods and tapes. However, compositions based on these monomers perform poorly across a range of metrics relative to compositions containing conventional room temperature liquid forms of cyanoacrylate monomers. Furthermore, solid cyanoacrylate monomers are typically non-standard specialty chemicals that are costly and difficult to synthesize.

[0005] Henkel's previously developed cyanoacrylate tapes have been based on monomers that are solid at room temperature (e.g., phenylethyl cyanoacrylate). However, the use of solid cyanoacrylate monomers to prepare adhesive tapes makes them impossible to use as "instant tack" tapes and negates the primary advantage of using cyanoacrylates as instant adhesives.

[0006] Liquid cyanoacrylate monomers allow for better diffusion through the bulk, resulting in faster room temperature cure than solid cyanoacrylate monomers.

[0007] However, adhesive tapes based on standard liquid cyanoacrylate monomers are difficult to obtain. This is not only due to the inherent reactivity of cyanoacrylate monomers towards the film formers themselves, but also because of the need for materials with sufficient structural integrity to achieve proper film formation.

[0008] A rare example is described in U.S. Patent Application No. 2015 / 0107761, which discloses an adhesive tape comprising a curable film on a release substrate and / or a carrier substrate. The curable film comprises at least one cyanoacrylate monomer and at least one film-forming (co)polymer.

[0009] It would be advantageous to develop adhesive tapes that achieve instant tack without the need for heating under pressure. Summary of the invention

[0010] In one aspect, the present invention includes a curable composition comprising:

[0011] a cyanoacrylate component; and

[0012] Solid thermoplastic polyether polyurethane resin; and

[0013] The molecular weight Mw of the solid thermoplastic polyether polyurethane resin is in the range of about 180,000 g / mol to about 260,000 g / mol, wherein the molecular weight Mw is measured according to ASTM D5296-05.

[0014] The composition of the present invention is non-flowable at room temperature (25° C.) and is suitable for use as an adhesive composition. Desirably, the composition of the present invention is substantially solid and can be used to provide any suitable solid form. The composition of the present invention can be used in any suitable application, such as in the form of a tape. The composition of the present invention can be provided on a carrier, or can be in a self-supporting form. For example, the composition can be applied to a release liner; an interliner layer or liner with different release values ​​can be used. The composition can be applied by using a suitable solvent, for example, by casting onto the liner by a suitable solvent.

[0015] The molecular weight Mw of the solid thermoplastic polyether polyurethane resin can be in the range of about 200,000 g / mol to about 240,000 g / mol, for example, in the range of about 215,000 g / mol to 230,000 g / mol, for example, in the range of 220,000 g / mol to 225,000 g / mol, for example, about 223,000 g / mol, wherein the molecular weight Mw is determined according to ASTM D5296-05 (Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography).

[0016] The melting point of the solid thermoplastic polyether polyurethane resin may range from 160°C to 200°C, such as from 165°C to 190°C, such as from 170°C to 180°C.

[0017] Suitably, the cyanoacrylate component is a liquid curable cyanoacrylate component.

[0018] The cyanoacrylate component (i) may be selected from ethyl cyanoacrylate, butyl cyanoacrylate, β-methoxycyanoacrylate, and combinations thereof.

[0019] The solid thermoplastic polyether polyurethane resin may be present in an amount of about 25 wt % to about 90 wt % based on the total weight of the composition, suitably greater than 50 wt %, such as about 65 wt % to about 85 wt % based on the total weight of the curable composition.

[0020] Without wishing to be bound by theory, compositions containing less than about 25% by weight of a solid thermoplastic polyether polyurethane component may have elastomeric properties insufficient to allow the composition to be properly applied to the parts to be bonded. Compositions containing greater than about 90% by weight of a solid thermoplastic polyether polyurethane component may exhibit poor adhesive properties. When the solid thermoplastic polyether polyurethane resin is present in an amount of about 25% to about 90% by weight, based on the total weight of the curable composition, this may provide the composition with an acceptable balance of adhesive properties and a composition that can form a coating having elastomeric properties sufficient to allow the composition to be applied to the parts to be bonded.

[0021] The cyanoacrylate component (i) may be present in the curable composition in an amount of about 10 wt % to about 75 wt %, suitably about 10 wt % to 50 wt %, for example about 15 wt % to about 35 wt %, wherein the weight percentages are based on the total weight of the composition.

[0022] The present invention may include a stabilizer for the cyanoacrylate component.

[0023] In some embodiments, the stabilizer for the cyanoacrylate component is present in an amount from about 10 ppm to about 200 ppm, such as from about 25 ppm to about 100 ppm.

[0024] The stabilizer may be selected from boron trifluoride (BF3) or sulfur dioxide (SO2).

[0025] Desirably, the stabilizer is sulfur dioxide (SO2).

[0026] The composition of the invention may also contain at least one solvent. The use of a solvent may be beneficial, for example, for formulation or distribution purposes.

[0027] However, whenever weight percentages are used, they are based on the total weight of the composition without solvent.

[0028] In some embodiments, the present invention comprises a solvent selected from the group consisting of ethyl acetate, tetrahydrofuran, methyl ethyl ketone, cyclohexanone, and acetone.

[0029] Desirably, the present invention comprises ethyl acetate as the solvent.

[0030] The composition of the invention may be provided in any suitable solid form, such as in tape form, in filament form, or as a coating applied to a substrate.

[0031] Suitably, the composition of the invention is provided in tape form.

[0032] In another aspect, the present invention also relates to an adhesive tape comprising the curable composition according to the present invention, and one or more release liners.

[0033] The tape of the present invention may be a transfer tape. One or more release liners may be used to transfer the curable composition (eg, in film form) to at least one substrate.

[0034] The tape of the present invention can exhibit adhesive properties at room temperature, wherein the curable composition of the article can be attached to at least one surface by applying mild pressure to the tape. The cyanoacrylate component of the composition will act as an instant adhesive. Therefore, the composition of the present invention should immediately adhere to any compatible substrate.

[0035] In another aspect, the present invention also relates to a method for preparing a curable composition, the method comprising the steps of:

[0036] (i) combining a solid thermoplastic polyether polyurethane resin component as described above with a cyanoacrylate component as described above and a solvent to form a mixture;

[0037] (ii) applying the mixture of step (i) to a substrate, optionally by casting;

[0038] (iii) allowing the solvent to evaporate or actively removing the solvent to form a curable composition in solid form.

[0039] In some embodiments of the method, the substrate is a release liner.

[0040] In some embodiments of the method, the solvent is ethyl acetate.

[0041] In some embodiments of the method, the solid thermoplastic polyether polyurethane resin is present in the curable composition in an amount greater than about 50 weight percent, wherein the weight percent is based on the total weight of the composition.

[0042] The solid thermoplastic polyether urethane resin may be present in an amount equal to or greater than the amount of the cyanoacrylate component.

[0043] In a further aspect, the present invention also relates to the composition according to the invention in cured form.

[0044] In yet another aspect, the present invention also relates to an assembly comprising two substrates bonded together by the composition of the present invention in cured form. DETAILED DESCRIPTION

[0045] As described above, the present invention provides a curable composition comprising: a cyanoacrylate component and a solid thermoplastic polyether polyurethane resin; wherein the molecular weight Mw of the solid thermoplastic polyether polyurethane resin is in the range of about 180,000 g / mol to about 260,000 g / mol, wherein the molecular weight Mw is determined according to ASTM D5296-05.

[0046] It has been unexpectedly discovered that combining a solid thermoplastic polyether polyurethane resin with a curable cyanoacrylate component can be used to prepare films having very high integrity.

[0047] The solid thermoplastic polyether polyurethane resin used in the curable composition of the present invention may be present in an amount greater than about 50% by weight based on the total weight of the composition. Without wishing to be bound by any theory, it is believed that such a relatively high proportion of thermoplastic polyether polyurethane resin in the composition may contribute to the high integrity of any film formed from the composition.

[0048] Thermoplastic polyether polyurethane resins have shown excellent stability in various types of cyanoacrylate monomers.

[0049] Thermoplastic polyether polyurethane resins have mechanical properties that range between those of thermoplastics and thermosets. This is achieved through 'virtual crosslinks' caused by hydrogen bonding effects between urethane groups on opposite polymer chains. This interchain hydrogen bonding imparts a variety of physical properties to these unique materials and manifests itself macroscopically in the form of excellent elasticity and elongation.

[0050] These rubber-like or elastic type properties allow the preparation of membranes with very high integrity.

[0051] Additionally, thermoplastic polyether polyurethane resin film formers have excellent tensile strength and elongation properties, which provide benefits over other available film formers.

[0052] It is believed that the use of liquid cyanoacrylate monomers allows for better diffusion through the bulk than solid cyanoacrylate monomers, thereby resulting in faster room temperature curing.

[0053] When solid thermoplastic polyether urethane resins are combined with liquid cyanoacrylate monomers, the resulting films not only have high internal structural integrity, but also cure instantly upon contact with standard substrates.

[0054] Solid thermoplastic polyether polyurethane resins suitable for use in the present invention are those having a molecular weight Mw in the range of about 180,000 g / mol to about 260,000 g / mol. Suitably, the molecular weight Mw of the solid thermoplastic polyether polyurethane resin is in the range of about 200,000 g / mol to about 240,000 g / mol, for example, in the range of about 215,000 g / mol to 230,000 g / mol, for example, in the range of 220,000 g / mol to 225,000 g / mol, for example, about 223,000 g / mol, wherein the molecular weight Mw is determined according to ASTM D5296-05. The melting point of the solid thermoplastic polyether polyurethane resin may be 160° C. to 200° C., for example, 165° C. to 190° C., for example, 170° C. to 180° C. Suitable solid thermoplastic polyether polyurethane resins include those available from Lubrizol, Carrer del Gran Vial, 17, 08160 Montmelo, Barcelona, ​​Spain. 960. 960 is a solid thermoplastic polyether polyurethane resin having a Mw of 222,906 as determined according to D5296-05 (Standard Test Method for Molecular Weight Average and Molecular Weight Distribution of Polystyrene by High Performance Size Exclusion Chromatography) and a melting point of 170°C to 180°C.

[0055] The formulation of the compositions and products of the present invention can be achieved by combining a solid thermoplastic polyether polyurethane resin with a solvent and stirring at an elevated temperature. Desirably, the mixture is stirred at an elevated temperature (e.g., at about 65° C.). The actual temperature used can vary depending on the melting point of the TPU used or its solubility. The mixing is carried out for a time sufficient to dissolve the TPU component into the solvent, which can vary depending on the batch size. At this stage, a stabilizer can be added. Then, the cyanoacrylate component is added to the composition. Without wishing to be bound by any theory, it is believed that the late addition of the cyanoacrylate component has a beneficial effect on the stability of the final product.

[0056] The adhesive formulation can be applied to a substrate (e.g., a release liner), optionally by casting. The substrate can be placed for a period of time (e.g., about 5 minutes), optionally at an elevated temperature (e.g., about 60° C.), to facilitate the removal of the solvent. After this period of time, the film thickness can be significantly less than the wet coating thickness. Once the solvent has evaporated, rapid winding can be performed to prevent dust particles or moisture from contacting the surface of the film.

[0057] Suitably, the composition of the present invention can be provided in any suitable solid form, and the solid form includes a band form, a silk form, or as a coating applied to a substrate, and the substrate includes, for example, a silk or a line made of another material, such as a nylon line or a polyester line. The composition in its solid form (such as a band form or a silk form) can have the integrity to be enough to be handled without breaking. The composition in its solid form (such as a band form or a silk form) can be applied to a substrate (such as a metal bolt) at room temperature. The composition in its solid form (such as a band form or a silk form) can be heat-resistant at a temperature of at least 150°C (such as 180°C). This means that the composition is durable enough to maintain performance at a temperature of a common industrial environment. Even at an elevated temperature, the composition in its solid form (such as a band form or a silk form) can be non-sticky and dry to the touch, thereby not requiring a carrier (such as a release liner). The composition in a band form or a silk form can be rolled up on itself and will not adhere to itself because it is non-sticky and dry to the touch. Alternatively, the tape form or filament form may comprise a curable composition as described herein and one or more release liners. For example, a release liner may be useful when the temperature at which the composition is to be stored is above 40°C, because at temperatures above 40°C, the non-adhesive composition may become tacky and may adhere to itself. As mentioned above, the composition of the present invention may also be in any suitable solid form, including tape form, filament form, or as a (solid, dry to the touch) coating applied to a substrate, the substrate including, for example, a filament or thread made of another material, such as nylon thread or polyester thread.

[0058] Definitions and Standard Test Methods

[0059] As used herein, the term "liquid" means liquid in a temperature range of about 5°C to 30°C, suitably liquid at room temperature and atmospheric pressure.

[0060] As used herein, the term "solid" means solid in the temperature range of about 5°C to 40°C, suitably solid at room temperature and atmospheric pressure. The solid state is defined as a state of matter in which the material is not fluid but holds its boundaries without support, with atoms or molecules occupying fixed positions relative to each other and not free to move.

[0061] As used herein, the term "tape" means an article comprising a curable composition, and one or more release liners.

[0062] As used herein, the phrase "stabilizer" or "Lewis acid stabilizer" means a substance that stabilizes the curable cyanoacrylate component, for example, by inhibiting premature polymerization of the cyanoacrylate. Examples of such substances include boron trifluoride (BF3) or sulfur dioxide (SO2). Those skilled in the art will readily appreciate that other suitable stabilizers (e.g., another suitable Lewis acid) can be used to stabilize the curable cyanoacrylate component. It is disclosed that ethyl cyanoacrylate, β-methoxycyanoacrylate, or butyl cyanoacrylate can be used as a carrier for the stabilizer to prepare a stabilizer solution, which is suitable for adjusting the amount of stabilizer in the curable composition based on ethyl cyanoacrylate, β-methoxycyanoacrylate, or butyl cyanoacrylate, respectively.

[0063] For purposes of the present invention, tack-free means dry to the touch, but the composition will not flake off during handling or use. For example, an article to which the composition of the present invention has been applied is dry to the touch. An article to which the composition of the present invention has been applied is considered dry to the touch if 20 such articles are placed individually on dry tissue paper for four hours and the appearance of the tissue paper does not change.

[0064] The molecular weights disclosed herein are determined according to ISO 13885-1:2008 "Binders for paints and varnishes--Gel permeation chromatography (GPC)--Part 1: Tetrahydrofuran (THF) as eluent."

[0065] The melting and resolidification temperature ranges are measured according to ISO 1137-1:2016 "Plastics—Differential scanning calorimetry (DSC)—Part 1 General Principles".

[0066] Example

[0067] Example compositions of the present invention may be those provided in Table 1.

[0068] Table 1

[0069]

[0070] The composition of Table 1 can be prepared as follows:

[0071] In a suitable container, a solid thermoplastic polyether urethane resin is dissolved in a solvent (such as ethyl acetate). The mixture is brought to a suitable temperature (e.g., about 65° C.) and stirred until complete dissolution of the solid thermoplastic polyether urethane resin is achieved. Then, a stabilizer is added, followed by the relevant cyanoacrylate monomer.

[0072] When used herein with respect to the present invention, the words "comprise / comprising" and the words "have / include" are used to specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0073] It should be understood that certain features of the present invention described in the context of separate embodiments for clarity may also be provided in combination in a single embodiment. On the contrary, various features of the present invention described in the context of a single embodiment for brevity may also be provided individually or in any suitable sub-combination.

Claims

1. A curable composition comprising: a cyanoacrylate component; and Solid thermoplastic polyether polyurethane resin; and The molecular weight Mw of the solid thermoplastic polyether polyurethane resin is in the range of about 180,000 g / mol to about 260,000 g / mol, wherein the molecular weight Mw is determined according to ASTM D5296-05.

2. The composition according to claim 1, wherein the molecular weight Mw of the solid thermoplastic polyether polyurethane resin is in the range of about 200,000 g / mol to about 240,000 g / mol, for example in the range of about 215,000 g / mol to 230,000 g / mol, for example in the range of 220,000 g / mol to 225,000 g / mol, for example about 223,000 g / mol, wherein the molecular weight Mw is determined according to ASTM D5296-05.

3. A composition according to any preceding claim, wherein the solid thermoplastic polyether polyurethane resin has a melting point of 160 to 200°C, such as 165 to 190°C, such as 170 to 180°C.

4. A composition according to any preceding claim, wherein the cyanoacrylate component is a liquid curable cyanoacrylate component.

5. The composition of any preceding claim, wherein the cyanoacrylate component is selected from the group consisting of ethyl cyanoacrylate, butyl cyanoacrylate, beta-methoxycyanoacrylate, and combinations thereof.

6. A composition according to any preceding claim, wherein the solid thermoplastic polyether polyurethane resin is present in an amount of about 25 wt % to about 90 wt % based on the total weight of the composition, suitably greater than 50 wt %, for example about 65 wt % to about 85 wt %, based on the total weight of the curable composition.

7. The composition of any preceding claim, wherein the cyanoacrylate component is present in an amount of about 10 wt % to about 75 wt % based on the total weight of the composition, such as about 15 wt % to 35 wt % based on the total weight of the curable composition.

8. A composition according to any preceding claim further comprising from about 5 ppm to about 200 ppm, such as from about 10 ppm to about 100 ppm, of a stabilizer for the cyanoacrylate component.

9. The composition of claim 8, wherein the stabilizer is selected from boron trifluoride (BF3) or sulfur dioxide (SO2).

10. The composition of claim 9, wherein the stabilizer is sulfur dioxide (SO2).

11. A composition according to any preceding claim, further comprising a solvent selected from the group consisting of ethyl acetate, tetrahydrofuran, methyl ethyl ketone, cyclohexanone and acetone.

12. A composition according to claim 11, wherein the solvent used is ethyl acetate.

13. A composition according to any preceding claim provided in tape form, filament form, or in the form of a coated substrate.

14. A composition according to any preceding claim provided in tape form.

15. An adhesive tape comprising a curable composition according to any preceding claim, and one or more release liners.

16. A method for preparing a curable composition, the method comprising the following steps: i) combining a solid thermoplastic polyether polyurethane resin component as described in any one of claims 1 to 12 with a cyanoacrylate component as described in any one of claims 1 to 12 and a solvent, to form a mixture; ii) applying the mixture of step (i) to a substrate, optionally by casting; iii) allowing the solvent to evaporate or actively removing the solvent to form a curable composition in solid form.

17. The method of claim 16, wherein the substrate is a release liner.

18. The process according to claim 16 or 17, wherein the solvent is ethyl acetate.

19. The method of any one of claims 16-18, wherein the solid thermoplastic polyether polyurethane resin is present in the curable composition in an amount greater than about 50 weight percent, wherein the weight percent is based on the total weight of the composition.

20. A composition according to any one of claims 1 to 14 in cured form.

21. An assembly comprising two substrates bonded together by a composition according to any one of claims 1 to 14 in cured form.

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