Base composition for a two-component adhesive comprising graphene oxide

Abstract

The present invention relates to a base composition for a two-component adhesive and, more particularly, to a base composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant. The base composition of the present invention is mixed with a curing agent to form a two-component adhesive. In particular, although graphene having high tensile strength and thermal conductivity is added as an adhesion promoter, the composition exhibits excellent dispersibility and dispersion stability, thereby improving the adhesive strength of the adhesive and reducing shrinkage.

Description

Main composition for a two-part adhesive containing graphene oxide

[0001] The present invention relates to a main component composition for adhesives, and more specifically, to a main component composition for two-component adhesives comprising a polyol, graphene oxide, and a dispersant.

[0002] The subject composition of the present invention forms a two-component adhesive by mixing with a curing agent, and in particular, graphene, which has high tensile strength and thermal conductivity, is added as an adhesion promoter while having excellent dispersibility and dispersion stability, thereby improving the adhesive strength and shrinkage of the adhesive.

[0003] High-density energy storage is required to store large amounts of energy in limited spaces, and to this end, development is underway to condense, store, and utilize gaseous fuels at cryogenic temperatures. In particular, regarding the manufacturing of structures for gaseous fuel storage, methods using adhesives to secure joints are being developed, rather than relying on traditional welding or joints. However, adhesives can cause issues such as microcracks and interlayer separation due to the difference in thermal expansion coefficients between the substrate and the adhesive in cryogenic environments. Carbon composite materials possess excellent physical properties, such as very high strength and a low thermal expansion coefficient; when incorporated into adhesives, this reduces the rate of thermal expansion, thereby minimizing damage to the adhesive layer and offering the potential for improved adhesion. Graphene exhibits superior properties among existing materials, including tensile strength, thermal conductivity, and electron mobility, making it a desirable component for adhesives; however, it has the disadvantage of causing aggregation upon addition. To address the dispersion issues of graphene, research on surface modification utilizing various functional groups of graphene oxide is actively being conducted. However, these studies have encountered problems such as high reaction heat, low reproducibility, and unsuitability for mass production, requiring improvements. Therefore, there is a need for the development of technology that ensures dispersion stability while adding graphene, thereby maximizing the improvement of physical properties as an adhesive.

[0004] In order to solve the problems of the conventional technology described above, the present invention aims to provide a main component composition for a two-component adhesive that can improve the dispersibility of graphene.

[0005] To achieve the above objective, the present invention provides a main composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant.

[0006] In addition, the present invention provides a two-component adhesive comprising a main composition of polyol, graphene oxide, and a dispersant.

[0007] In addition, the present invention provides a method for preparing a main composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant.

[0008] The main composition for a two-component adhesive according to the present invention can improve the dispersion stability of graphene while enhancing the physical properties of the cryogenic adhesive due to the high thermal conductivity and high tensile strength, which are advantages of graphene.

[0009] Figure 1 illustrates the sedimentation state of graphene in Comparative Examples 1 to 3.

[0010] FIGS. 2 to 7 illustrate the luminizer measurement results in Examples 1, 5, 6, 3, 9, and 10.

[0011] FIGS. 8 to 12 illustrate the luminizer measurement results in Examples 11, 13, 14, 12, and 17.

[0012] The present invention will be explained in more detail below through specific embodiments. The following embodiments describe a preferred embodiment of the present invention, and the scope of the present invention is not to be interpreted as being limited by the matters described in the following embodiments.

[0013] The present invention relates to a main composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant. In one aspect, the polyol is a polyether polyol having two or more functional groups, preferably a polyether diol (preferably comprising a primary hydroxyl group or a mixture of primary and secondary hydroxyl groups). Examples of suitable polyether polyols are polyoxyalkylene polyols, such as polyethylene glycol, polypropylene glycol, polytetramethyl glycol, and polybutyl glycol. Additionally, homopolymers or copolymers of the listed polyoxyalkylene polyols, as well as mixtures thereof, are suitable for the purposes of the present invention. Particularly suitable copolymers comprise compounds selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, propylene glycol, triethylene glycol, 2-ethylhexanediol-1,3-glycerin, trimethylolpropane, trimethylolethane, tris(hydroxyphenyl)propane, triethanolamine, and triisopropylamine, and adducts of at least one compound selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide. More preferably, they may comprise one or more selected from the group consisting of polypropylene glycol (PPG), polyoxypropylenetriol (GP), polytetramethylene glycol (PTMG), polytetramethylene ether glycol (PTMG), polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

[0014] In one aspect, the polyol may be polytetramethylene etherglycol (PTMEG) or polycaprolactone polyol having an average molecular weight in the range of 100 g / mol to 80,000 g / mol. If the polyol molecular weight exceeds 80,000 g / mol, the viscosity increases, which leads to reduced dispersion efficiency and reduced dispersion stability in the dispersion solution, as well as a problem of reduced performance improvement for graphene after the manufacture of the polyurethane adhesive. Preferably, it is polytetramethylene etherglycol (PTMEG) having a molecular weight in the range of 300 g / mol to 600 g / mol or polycaprolactone polyol having a molecular weight in the range of 500 g / mol to 800 g / mol. Since the molecular weight of the polyol affects the stability of graphene particles, it is necessary to optimize the molecular weight range according to the type of polyol to maintain a uniform size of dispersed particles.

[0015] In the present invention, graphene oxide was used as high-performance graphene to enhance the dispersibility of graphene and maximize the expression of its inherent properties.

[0016] The graphene oxide of the present invention was used as an adhesion promoter. An adhesion promoter differs from an adhesive in that it has no substantial adhesive strength on its own, but it acts on the interface (adhesion surface) of a substrate to enhance the adhesion strength and durability of the adhesive with the substrate, and is also referred to as an "adhesion promoter." The adhesion promoter can be used in the form of a primer that is applied to the substrate surface in advance to modify the surface of the substrate prior to the use of the adhesive, but it can also be used in the form of a small amount added to the adhesive.

[0017] In the present invention, by including graphene in the main composition beforehand, the adhesive properties of the adhesive are improved and the drying time or reaction time is accelerated, thereby increasing product productivity and stability.

[0018] In one aspect, the oxygen content of the graphene oxide of the present invention may be 5 to 30%. As the oxygen content decreases below 5%, dispersion is not smooth, and as it increases above 30%, the physical properties of the graphene deteriorate, so the physical properties of the adhesive are not improved. Preferably, the oxygen content of the graphene oxide of the present invention may be 10 to 20%, more preferably 15%.

[0019] In one aspect, the graphene oxide may be included in an amount of 0.2% or more and less than 1.5% by weight based on the content of the entire composition. If the content of graphene oxide is less than 0.2% by weight, the physical properties due to graphene may be degraded, and if it is 1.5% by weight or more, the viscosity increases and the dispersion efficiency decreases. This is because the graphene clumps together, causing the physical properties to degrade relative to the amount added.

[0020] The dispersant of the present invention is intended to ensure the dispersion stability of graphene.

[0021] In one aspect, the dispersant may be one or more selected from the group consisting of polyether-based, modified polyether-based, polyurethane-based, polyacrylate-based, modified polyacrylate-based, and fatty acid salt-based. More preferably, it may be a modified polyether, a polyurethane copolymer, or a combination thereof.

[0022] In one aspect, the above-mentioned dispersant may be of the solvent-free type.

[0023] In one aspect, the dispersant may be a dispersant having an amine value of 1 to 100 mgKOH / g. If the amine value exceeds 100 mgKOH / g, the polyurethane reaction does not proceed smoothly when manufacturing a polyurethane-based adhesive, resulting in a decrease in the performance of the adhesive. Preferably, it may be a modified polyether with an amine value in the range of 1 to 10 mgKOH / g or a polyurethane copolymer with an amine value in the range of 30 to 60 mgKOH / g.

[0024] In one aspect, the main composition for a two-component adhesive according to the present invention may include graphene oxide and a dispersant in a weight ratio of greater than 1:1 and less than or equal to 1:3.

[0025] Based on graphene oxide 1, if the dispersant is 1 or less, the dispersion stability of graphene is reduced, and if it exceeds 3, the dispersion stability is also reduced. This is because, in polyurethane adhesives, the dispersant is an impurity, which can lead to a problem of degrading adhesive properties.

[0026] Commercially available dispersants may be used. Examples of commercially available products include "DISPERBYK-2008," "BYK-9076," "BYK-9077," and "ANTI-TERRA-U" (all manufactured by Big Chem Co., Ltd.).

[0027] In addition, the present invention relates to a two-component adhesive comprising a main composition of polyol, graphene oxide, and a dispersant.

[0028] In one aspect, the two-component adhesive composition may be for cryogenic or ultra-low temperature applications. To maintain adhesion without deformation at very low temperatures, it must have high shear and peel strength, and no thermal expansion or shrinkage must occur. It must maintain strength over a long period of time and be usable for bonding various materials such as metal and masonry.

[0029] Cryogenic adhesives include epoxy-based and polyurethane-based adhesives, and there are also hybrid adhesives that appropriately mix epoxy and polyurethane or utilize a portion of the epoxy as a soft segment of polyurethane.

[0030] The main component composition for the two-component adhesive of the present invention is combined with a curing agent composition to become a two-component adhesive. The curing agent is not limited, but a diisocyanate may be used, for example, one or more of 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 1,4-benzene diisocyanate, cyclohexane-1,4-diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, 4,6-xylene diisocyanate, and isophorone diisocyanate may be selected, and more preferably, 4,4'-diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, or 2,6-toluene diisocyanate.

[0031] In addition, the present invention provides a method for preparing a main component composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant, comprising: a) a step of adding a dispersant to a polyol and stirring at 4,000 to 8,000 rpm for 5 to 20 minutes at 20 to 28 ℃; b) a step of preparing a first dispersion by adding graphene oxide to the stirred mixture of step a) and stirring at 4,000 to 8,000 rpm for 40 to 80 minutes; and c) a step of preparing a second dispersion by dispersing the first dispersion of step b) at 600 to 1,200 bar with a high-pressure disperser at 5 passes or less.

[0032] In the first dispersion, the dispersion RPM and dispersion time should be determined using a simple particle size analyzer, and it is desirable to set the RPM to a level lower than the equipment operating limit. The time should be determined by checking the change in particle size with a simple particle size meter.

[0033] In the second dispersion stage, the dispersion pressure must be between 600 and 1,200 bar, and the process must be carried out with 5 passes or fewer. After dispersion, the dispersion solution is checked using a simple particle size analyzer; if it exhibits a particle distribution at the target level, the dispersion is considered complete. The dispersion pressure and number of passes can be determined using a simple particle size analyzer, and while the dispersion equipment manufacturer sets an upper limit for the pressure, it is advisable to set it below that limit. The number of passes should be selected considering the working time during mass production.

[0034] The following manufacturing examples and embodiments illustrate the present invention without limiting the scope of the invention.

[0035] [Preparation Example 1]

[0036] Manufacturing of Graphene Oxide

[0037] 40 g of graphite and 240 g of NaNO3 were added to 1000 ml of sulfate solution and stirred for 14 hours. Afterward, distilled water was added to wash and freeze-dried to prepare graphene oxide powder. The oxygen content was 15% relative to the total content of carbon, hydrogen, and oxygen.

[0038] [Example 1]

[0039] <Preparation of Main Composition for Two-Part Adhesives>

[0040] A cooler was connected to a 2L double-jacketed reaction vessel and maintained at 25°C. 996g of polytetramethylene etherglycol (PTMEG) (200 g / mol) and 2g of a polyurethane copolymer having an amine value of 50 mgKOH / g were added to the reaction vessel and stirred for 10 minutes at 6,000 rpm using a homomixer (SILVERSON, L5M-A). Additionally, 2g of the graphene oxide (GO) prepared above was mixed in, and the mixture was dispersed using a homogenizer (SILVERSON, L5M-A) at 6,000 rpm for 60 minutes to prepare the first dispersion. At this time, the dispersion rpm and dispersion time were determined using a simple particle size analyzer. The rpm was set to a level lower than the equipment operating limit, and the time was determined by checking changes in particle size using a simple particle size analyzer.

[0041] Subsequently, the first dispersion was dispersed using a high-pressure disperser (Micronox, MN400BF), and a second dispersion was performed at 1,000 bar with 5 passes or fewer. After dispersion, the dispersion was checked using a simple particle size analyzer; if the dispersion showed a particle distribution at the target level, the dispersion was completed to produce the second dispersion. The dispersion pressure and passes were determined using a simple particle size analyzer. The pressure was set below the upper limit specified by the dispersion equipment manufacturer. The number of passes was selected considering the working time during mass production.

[0042] [Examples 2 to 10]

[0043] Examples 2 to 10 were prepared in the same manner as Example 1, except that the combination of each component was changed as shown in Table 1 below. The remainder, excluding the weight of graphene oxide and dispersant, was all polyol so that the total weight was 1000g.

[0044] GO g (weight%) Polyol (molecular weight) Dispersant (amine value mgKOH / g), g GO:weight ratio of dispersant Example 12g (0.2) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 2g 1:1 Example 22g (0.2) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 2.5g 1:1.25 Example 32g (0.2) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 3g 1:1.5 Example 42g (0.2) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 3.5g 1:1.75 Example 52g (0.2) PTMEG (1,000 g / mol) Polyurethane Copolymer (50) 4g 1:2 Example 62g (0.2) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 6g 1:3 Example 75g (0.5) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 7.5g 1:1.5 Example 87g (0.7) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 10.5g 1:1.5 Example 910g (1) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 15g 1:1.5 Example 1015g (1.5) PTMEG (1,000 g / mol) Polyurethane copolymer (50) 22.5g 1:1.5

[0045] [Examples 11 to 17]

[0046] Examples 11 to 17 were prepared in the same manner as Example 1, except that the combination of each component was changed as shown in Table 2 below.

[0047] g of GO (weight%) Polyol (molecular weight) Dispersant (amine value, mgKOH / g), g GO:weight ratio of dispersant Example 112g (0.2) Polycaprolactone polyol (540 g / mol) Modified polyether (3), 2g 1:1 Example 122g (0.2) Polycaprolactone polyol (540 g / mol) Modified polyether (3), 3g 1:1.5 Example 132g (0.2) Polycaprolactone polyol (540 g / mol) Modified polyether (3), 4g 1:2 Example 142g (0.2) Polycaprolactone polyol (540 g / mol) Modified polyether (3), 6g 1:3 Example 155g (0.5) Polycaprolactone polyol (540 g / mol) Modified polyether (3), 10g 1:1.5 Example 167g (0.7) Polycaprolactone polyol (540 g / mol) modified polyether (3), 20g 1:1.5 Example 1710g (1) Polycaprolactone polyol (540 g / mol) modified polyether (3), 20g 1:1.5

[0048] [Comparative Examples 1 to 3]

[0049] A composition as shown in Table 3 below was prepared without adding a dispersant to a mixture of polyol and graphene oxide (oxygen content 15%).

[0050] g of GO (weight%) Polyol (molecular weight) g Comparative Example 12g (0.2) PTMEG (200 g / mol) 998 g Comparative Example 22g (0.2) Polycaprolactone Polyol (540 g / mol) 998 g Comparative Example 32g (0.2) PTMEG (1,000 g / mol) 998 g

[0051] [Experimental Example 1]

[0052] Visual Evaluation

[0053] Visual evaluation was performed to evaluate dispersion using the mixtures prepared in Examples 1 to 17 above. Visual evaluation refers to a visual inspection by a person's eyes, and was evaluated as "unstable" if graphene sedimentation was observed, and "stable" if no sedimentation was observed.

[0054] Examples 1 to 17 above were evaluated as “stable” in the visual evaluation. Comparative Examples 1 to 3, which do not contain a dispersant, were all evaluated as “unstable,” as graphene sedimentation was observed as shown in FIG. 1 (a), (b), and (c).

[0055] It was confirmed that when no dispersant is added, graphene oxide does not exhibit dispersion stability in polyol, so adding a specific dispersant in an appropriate amount is very important for ensuring dispersion stability.

[0056] [Experimental Example 2]

[0057] <Variance Stability Assessment>

[0058] We intended to measure the dispersion stability of the main composition for the two-component adhesive prepared in the above examples.

[0059] Variance stability was measured using a Lumisizer (LS610, LUM), and the instability index result was measured at 60 minutes. The results are shown in Table 4 below.

[0060] Classification Instability Index (60 min) Example 10.624 Example 20.073 Example 30.016 Example 40.029 Example 50.061 Example 60.094 Example 70.019 Example 80.013 Example 90.010 Example 100.102 Example 110.108 Example 120.015 Example 130.037 Example 140.029 Example 150.019 Example 160.013 Example 170.010

[0061] The dispersion stability was measured to be excellent throughout Examples 1-17.

[0062] However, Examples 1 and 11 showed slightly lower dispersion stability compared to other examples. This was determined to be due to the dispersant content being lower compared to other examples. Additionally, Example 5 showed slightly lower dispersion stability compared to other examples. This was determined to be due to the graphene oxide content being higher compared to other examples.

[0063] [Preparation Example 2]

[0064] A two-component adhesive was prepared by mixing 90 wt% of the main composition prepared in Example 3 above with 10% of 2,6-toluene diisocyanate as a curing agent. The adhesive strength was evaluated as excellent at 14 MPa as a result of measuring according to the ISO 4587 method.

[0065] Although embodiments of the present invention have been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

[0066] The present invention is available for use in the adhesive industry.

Claims

1. A main component composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant.

2. A main component composition for a two-component adhesive according to claim 1, wherein the polyol is one or more selected from the group consisting of polypropylene glycol (PPG), polyoxypropylene triol (GP), polytetramethylene glycol (PTMG), polytetramethylene ether glycol (PTMG), polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

3. A main component composition for a two-component adhesive according to claim 1, characterized in that the polyol is polytetramethylene etherglycol (PTMEG) or polycaprolactone polyol having an average molecular weight in the range of 100 g / mol to 80,000 g / mol.

4. A main component composition for a two-component adhesive according to claim 1, characterized in that the graphene oxide has an oxygen content of 5 to 30%.

5. A main component composition for a two-component adhesive according to claim 4, wherein the graphene oxide has an oxygen content of 10 to 20%.

6. A main component composition for a two-component adhesive according to claim 1, characterized in that the graphene oxide is included in an amount of 0.2% or more and less than 1.5% by weight based on the content of the total composition.

7. A main component composition for a two-component adhesive according to claim 1, characterized in that the dispersant is one or more selected from the group consisting of polyether-based, modified polyether-based, polyurethane-based, polyacrylate-based, modified polyacrylate-based, and fatty acid salt-based.

8. A main component composition for a two-component adhesive according to claim 7, wherein the dispersant has an amine value of 1 to 100 mgKOH / g.

9. A two-component adhesive main composition according to claim 1, characterized in that the two-component adhesive main composition comprises graphene oxide and a dispersant in a weight ratio of greater than 1:1 and less than or equal to 1:

3.

10. A two-component adhesive comprising a main component composition for a two-component adhesive according to any one of claims 1 to 9.

11. A method for preparing a main component composition for a two-component adhesive comprising a polyol, graphene oxide, and a dispersant, wherein a) a step of adding a dispersant to the polyol and stirring at 4,000 to 8,000 rpm for 5 to 20 minutes at 20 to 28 ℃; b) a step of preparing a first dispersion by adding graphene oxide to the stirred mixture of step a) and stirring at 4,000 to 8,000 rpm for 40 to 80 minutes; and c) a step of preparing a second dispersion by dispersing the first dispersion of step b) in a high-pressure disperser at 600 to 1,200 bar in 5 passes or less; comprising a method for preparing a main component composition for a two-component adhesive.

12. A method for preparing a main component composition for a two-component adhesive according to claim 11, wherein the polyol is one or more selected from the group consisting of polypropylene glycol (PPG), polyoxypropylene triol, polytetramethylene glycol, polytetramethylene ether glycol, polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

13. A method for preparing a main component composition for a two-component adhesive according to claim 11, wherein the polyol is a polytetramethylene ether glycol or a polycaprolactone polyol having an average molecular weight in the range of 100 g / mol to 80,000 g / mol.

14. A method for preparing a main component composition for a two-component adhesive according to claim 11, characterized in that the graphene oxide has an oxygen content of 5 to 30%.

15. A method for preparing a main component composition for a two-component adhesive according to claim 14, wherein the graphene oxide has an oxygen content of 10 to 20%.

16. A method for preparing a main component composition for a two-component adhesive according to claim 11, characterized in that the graphene oxide is included in an amount of 0.2% or more and less than 1.5% by weight based on the content of the total composition.

17. A method for preparing a main component composition for a two-component adhesive according to claim 11, wherein the dispersant is one or more selected from the group consisting of polyether-based, modified polyether-based, polyurethane-based, polyacrylate-based, modified polyacrylate-based, and fatty acid salt-based.

18. A method for preparing a main component composition for a two-component adhesive according to claim 17, wherein the dispersant has an amine value of 1 to 100 mgKOH / g.

19. A method for manufacturing a main component composition for a two-component adhesive according to claim 11, characterized in that the main component composition for the two-component adhesive comprises graphene oxide and a dispersant in a weight ratio of greater than 1:1 and less than or equal to 1:3.

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