Polyaspartic ester structural adhesive composition and related production method

Abstract

The present invention relates to an adhesive production method for fast curing at low temperatures for structurally bonding materials together, and to an adhesive composition obtained by this method.

Description

[0001] DESCRIPTION

[0002] Polyaspartic Ester Structural Adhesive Composition and Related Production Method

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to an adhesive used to structurally bond materials together and the production methods of this adhesive.

[0005] PRIOR ART

[0006] Structural adhesives are an important component widely used in various fields of modern industry. The main feature of these adhesives is that they generally react very quickly, producing a thermosetting polymer. Thermoset polymers are types of polymers that harden when treated with heat or chemicals and do not melt again. This feature makes adhesives resistant to high pressure and mechanical stress. This fast reaction kinetics of adhesives is based on the polyesterification of acrylic monomers by reacting with organic peroxides. Acrylic monomers generally consist of compounds such as methyl methacrylate (C5H8O2), while organic peroxides (e.g. benzoyl peroxide, C14H10O4) serve as catalysts of this reaction. The polymers obtained as a result of this reaction not only harden quickly, but are also highly resistant to acids and bases. These properties make structural adhesives a preferred material, especially in the construction, automotive and aerospace industries.

[0007] Despite these advantageous properties of adhesives, there are also some disadvantages seen especially in the acrylic type versions. These adhesives can lose their adhesion strength when in contact with water, which can be a problem especially in humid environments or outdoor applications. They are also unstable to ketone-type solvents (e.g., acetone, C3H6O), limiting their use in various chemical environments. The brittle structure of structural adhesives creates a disadvantage, especially in terms of their resistance to impacts. This may cause problems in structures exposed to mechanical impacts. Their resistance to thermal cycles is also weak, which can lead to performance losses in applications where temperature changes occur frequently. Finally, these adhesives form a very hard and brittle structure once applied, making it difficult to clean mis- or over-applied areas. One of the materials that can be used in structural adhesives is the chemical Carbodiimide. The use of carbodiimides in the adhesive industry has the potential to improve the performance and ease of application of polyurethane adhesives, while also providing more environmentally friendly and less toxic alternatives. The use of carbodiimides is particularly common in areas such as the automotive, construction and footwear industries. These types of adhesives are preferred in applications requiring high strength, flexibility and durability.

[0008] However, adhesives comprising carbodiimide also have some disadvantages. For example, such adhesives may be less effective in humid environments and may be sensitive to certain chemicals. Additionally, the use of carbodiimides in the manufacturing process may result in increased cost and complexity in certain applications. Therefore, the selection and application of adhesives produced using carbodiimide must be made taking into account the specific requirements and environmental conditions of the application. R&D studies need to be carried out to eliminate or reduce these disadvantages.

[0009] The general disadvantages of structural adhesives are even more diverse. First of all, these adhesives have limited flexibility. In particular, the lack of flexibility of thermoset polymers can create poor resistance to sudden load changes. This can be a problem, especially in applications where dynamic loads and vibrations are intense. Additionally, some structural adhesives may experience loss of performance under certain chemical and environmental conditions. For example, they may have limited resistance to UV rays or oxidative environments, limiting their use in outdoor applications or locations exposed to sunlight. Heat resistance is also an important factor; adhesives that can lose performance at high temperatures may not be suitable in hot environments or applications requiring high temperatures.

[0010] In addition, the long-term durability and aging resistance of these adhesives are also important. Over time, environmental factors and chemical degradation can affect the structural integrity of the adhesive. This is an issue that should be taken into account, especially in structural applications that are expected to be long-lasting. In addition, the applicability and ease of use of structural adhesives is also an important factor. Some adhesives may require specialized equipment or the application process may be complex, which can increase labor costs and application difficulties. These factors play an important role in the selection and use of the adhesive and should be taken into account in cost-effectiveness analyses.

[0011] In literature studies, polyaspartic resin production, polyaspartic coating, carbodiimide production, and acrylic structural adhesives have been found. However, no article that combines these topics and explains this mixture and its application area has been encountered.

[0012] The following documents are found during the preliminary patent research made.

[0013] Japanese document with publication number JPH111559A describes a method of producing cross-linked polyaspartic acid resin. Basically, it involves hydrolyzing the imide ring of polysuccinimide in the form of a dispersion by reacting a dispersant with a crosslinking agent. Polyamine can be used as a cross-linking agent, and water-miscible or immiscible organic solvents can be used as dispersants. Polysuccinimidine, after being dissolved in a good solvent, can be dispersed by adding a poor solvent. The resulting cross-linked polyaspartic resin can be used in various industrial applications. Among the technical benefits mentioned in the publication, there is no information about increasing the drying speed or strengthening the adhesion feature, but technical benefits focused on the use of the crosslinker are explained. The invention demonstrates the technical benefits of performance enhancement by crosslinking agents and not by resin and further development is required, in particular to improve chemical resistance as a result of the application of the crosslinking agent. Otherwise it needs reinforcement, especially against ketone-containing solvents.

[0014] Chinese document with publication number CN107987274B details the production method and use of polyaspartic acid ester resin. The main raw materials include aminosilane modified graphene oxide, primary diamine, alkali catalyst and maleic acid ester. The preparation method of aminosilane modified graphene oxide involves adding graphene oxide to the solution in alcohol, heating, mixing, and adding amino silane coupling agent. The production method of polyaspartic acid ester resin includes the steps of mixing these materials, heating, adding maleic acid ester drop by drop, maintaining the reaction temperature and then cooling. This resin is then used in the production of anti-corrosive paint. The anticorrosive paint is obtained by mixing a component A comprising aliphatic isocyanate, elastic curing agent and polyaspartic acid ester resin and a component B comprising anti-sequestration agent, pigment, filling material, molecular sieve, antifoam, leveling agent, dispersant, hydroxy acrylic resin and organic solvent. This paint is used primarily as an adhesive with anti-corrosive properties. This invention can generally be described as a derivative of the processes that can be used in aspartic acid resin production, but it does not offer sufficient performance in chemical resistance. Studies should be carried out to increase the degree of cross-linking and especially R&D studies should be carried out to increase thermal resistance. The time required for the adhesive to have the desired effect on the surface it is applied to is not specified, and there is no information about an additive to ensure rapid drying.

[0015] As a result, all abovementioned problems have made it necessary to make an improvement in the relevant technical field.

[0016] AIM OF THE INVENTION

[0017] The present invention aims to eliminate the abovementioned problems and to make a development in the relevant technical field.

[0018] The main object of the present invention is to reveal an adhesive structure that reacts quickly with the products, has the feature of fast drying and curing at low temperatures.

[0019] Another object of the present invention is to reveal a thermosetting polymer production method that provides resistance to chemicals - ketone type solvents.

[0020] Another object of the present invention is to provide improvements in impact resistance, shear forces, thermal and chemical resistance by increasing the degree of cross-linking in the polymer matrix.

[0021] Another object of the present invention is to reveal an adhesive structure suitable for coloring works.

[0022] Another object of the present invention is to provide an adhesive structure that is easy to clean from incorrectly or excessively applied areas.

[0023] BRIEF DESCRIPTION OF THE INVENTION

[0024] In order to achieve all the objects mentioned above and to emerge from the detailed explanation below, the present invention is an adhesive production method used to structurally bond materials together. Accordingly; it comprises the following method steps; a. mixing a material in polyaspartic ester structure with an amine value between 200 - 205 mg*KOH / g with a cross-linking agent, b. adding filling material to the mixture and mixing c. adding a material with a diisocyanate structure to the mixture obtained at the end of the method step b. under inert gas or in a vacuum environment.

[0025] A preferred embodiment of the invention is the use of N,N'-(2-methyl-1 ,5- pentanediyl)bi- aspartic acid 1 ,1', 4, 4' -tetra ethyl ester or N,N'-(3,3-dimethyldicyclohexylmethane-4,4'- diyl)-bi-aspartic acid tetra ethyl ester with an amine value between 200 and 205 mg*KOH / g as the material in the polyaspartic ester structure in method step a.

[0026] Another preferred embodiment of the invention is the use of Carbodiimide as a crosslinking agent in method step a.

[0027] In a preferred embodiment of the invention, in method step b., one of the individuals or combinations selected from the group consisting of calcium carbonate, barium sulfate, aluminum hydroxide, feldspar, titanium dioxide, silicon dioxide, talc, basalt, bentonite, kaolin and mica is added to the mixture.

[0028] In another preferred embodiment of the invention, in method step c, one of the individuals or combinations selected from the group consisting of diphenylmethane diisocyanate (MDI) comprising 2,4, 2,2 and 4,4 isomers and mixtures thereof; toluene diisocyanate (TDI) comprising 2,4, 2,6 isomers and mixtures thereof; hexamethylene diisocyanate (HDI); isophorone diisocyanate (IPDI) and tetramethylxylene diisocyanate (TMXDI) as materials in the diisocyanate structure is added to the mixture obtained in method step b.

[0029] Independent of the foregoing, the invention is also an adhesive composition for structurally bonding materials together. Accordingly;

[0030] In another preferred embodiment of the invention, the polyaspartic ester material is N,N'- (2-methyl -1 ,5- pentanediyl)bi-aspartic acid 1 , 1 ',4, 4' -tetra ethyl ester or N,N'-(3,3- dimethyldicyclohexylmethane-4,4'-diyl)-bi-aspartic acid tetra ethyl ester with an amine value between 200 and 205 mg*KOH / g.

[0031] In a preferred embodiment of the invention, the crosslinking agent is Carbodiimide. In a further preferred embodiment of the invention, the filling material is selected from the group consisting of calcium carbonate, barium sulfate, aluminum hydroxide, feldspar, titanium dioxide, silicon dioxide, talc, basalt, bentonite, kaolin and mica.

[0032] In a preferred embodiment of the invention, the material in the diisocyanate structure is one of the individuals or combinations selected from the group consisting of diphenylmethane diisocyanate (MDI) comprising 2,4, 2,2 and 4,4 isomers and mixtures thereof; toluene diisocyanate (TDI) comprising 2,4, 2,6 isomers and mixtures thereof; hexamethylene diisocyanate (HDI); isophorone diisocyanate (IPDI) and tetramethylxylene diisocyanate (TMXDI).

[0033] DETAILED DESCRIPTION OF THE INVENTION

[0034] In this detailed description, the inventive subject “Polyaspartic Ester Structural Adhesive Composition” is described by means of examples only for clarifying the subject matter such that no limiting effect is created.

[0035] The subject of the invention relates to a polyaspartic ester-containing adhesive for shortening the drying time and providing curing properties at a temperature of at least 10°C.

[0036] The production methods of the adhesive, in its simplest form, comprise the following method steps: a. mixing a material in polyaspartic ester structure with an amine value between 200 - 205 mg*KOH / g with a cross-linking agent, b. adding filling material to the mixture and increasing the mixing speed c. adding diisocyanate to the mixture obtained at the end of the method step b. under inert gas or in a vacuum environment.

[0037] The adhesive composition obtained at the end of the mentioned method steps comprises the following;

[0038] • Material with polyaspartic ester structure in the range of 25-40% by weight,

[0039] • Cross-linking agent in the range of 0,1 -1 ,0% by weight,

[0040] • Filling material in the range of 59-74% by weight,

[0041] • Diisocyanate in the range of 20-33% by weight In the preferred embodiment of the invention as the material with the polyaspartic ester structure mentioned in the method step a above, N, N'-(2-methyl -1 ,5-pentanediyl)bi- aspartic acid 1 , 1 ',4,4'-tetra ethyl ester or N ,N'-(3,3-dimethyldicyclohexylmethane-4,4'- diyl)-bi-aspartic acid tetra ethyl ester is used. These materials are used as the main raw material of the adhesive that is intended to be protected. It is preferably used in the composition at a rate of 30.55% by weight. The important thing here is that the Amin value is 200 - 205 mg*KOH / g. In this way, the composition prepared in line with the purpose of the invention gives positive results in the test results.

[0042] In the preferred embodiment of the invention, Carbodiimide is used as the cross-linking agent. The disadvantage of Carbodiimide, which is frequently used in the production of polyurethane adhesives, is that polyurethane adhesives may be less effective in humid environments and are sensitive to certain chemicals. Additionally, the use of carbodiimides in the manufacturing process may result in increased cost and complexity in certain applications. Although similar disadvantages may occur in the use of carbodiimide in polyaspartic ester-containing adhesives instead of polyurethane adhesives, these disadvantages can be significantly reduced and the adhesive gains impact resistance thanks to the method steps and composition desired to be protected by the invention. The composition in the preferred embodiment of the invention comprises 0,28% carbodiimide by weight.

[0043] As a filling material, which is one of the important components, any individual or combination selected from the group consisting of calcium carbonate, barium sulfate, aluminum hydroxide, feldspar, titanium dioxide, silicon dioxide, talc, basalt, bentonite, kaolin and mica may be used in the preferred embodiment of the invention. Each alternative filling material affects the chemical and physical properties of the adhesive in different ways. The choice of filling material depends on the requirements of the application in which the adhesive will be used and the expected performance characteristics. These filling materials improve the strength, flexibility, heat and chemical resistance, color and many other properties of adhesives. The correct selection of filling materials and their proportioning in line with the composition within the scope of protection of the invention are the determining factors of the general performance of the adhesive and its behavior during application. In addition to the properties of fast drying and increasing cross-linking and gaining chemical and mechanical strength in the adhesive; Calcium carbonate (CaCOs): It increases the hardness and therefore the durability of the adhesive.

[0044] Barium sulphate (BaSCM): It is used as a weight and density enhancer. It is preferred in special applications to provide protection against radiation.

[0045] Aluminum Hydroxide (AI(OH)s): It is known for its flame retardant properties. It is used in high temperature applications or situations requiring fire safety.

[0046] Feldspat: It adds strength and hardness to adhesives and improves their thermal properties.

[0047] Titanium Dioxide (TiC ): It is used as a pigment and adds whiteness or opacity to adhesives. It also increases UV resistance.

[0048] Silicon Dioxide (SiC ): It is generally used to increase the mechanical properties and thermal durability of adhesives. It also improves the rheological (flow) properties of adhesives.

[0049] Talk (Mg3Si40io(OH)2): It provides slipperiness and smoothness to adhesives, and also increases the compatibility of the adhesive with its content if combined with another filler.

[0050] Basalt: It provides high strength and durability and is especially suitable for adhesives under heavy load.

[0051] Bentonite: It provides water retention capacity and viscosity control to adhesives. Bentonite is used especially in water-based adhesives.

[0052] Kaolin: It is added to adhesives as a low-cost filling material. Moreover, it can improve the color stability and opacity of the adhesive.

[0053] Mica: It gives adhesives flexibility and heat resistance and provides electrical insulation properties.

[0054] The filling material constitutes 59-74% by weight of the adhesive composition, depending on the use of the above materials in the adhesive composition. Calcium carbonate, the comparison and test results of which were made in the invention, constitutes 69,17% of the composition by weight. Diisocyanates play an important role in polyaspartic ester adhesives. Such adhesives are generally polyurea-polyaspartic hybrid systems created as a result of the reaction of polyaspartic esters and diisocyanates. In general, diisocyanates provide cross-head formation, fast curing and hardening, high performance and durability, chemical and mechanical resistance against environmental conditions, wide application area features in polyaspartic ester adhesives, in addition to these features, the present invention also provides low temperature curing feature with the help of Carbodiimide. As a diisocyanate to ensure low temperature curing properties, in the preferred embodiment of the invention, one of the following individual or combinations selected from the group comprising diphenylmethane diisocyanate (MDI) comprising 2,4, 2,2 and 4,4 isomers and mixtures; toluene diisocyanate (TDI) comprising 2,4, 2,6 isomers and mixtures; hexamethylene diisocyanate (HDI); isophorone diisocyanate (IPDI) and tetramethylxylene diisocyanate (TMXDI), is used. The selection of these materials can be chosen based on the following purposes and features within the scope of this invention;

[0055] Diphenylmethane Diisocyanate (MDI);

[0056] • The 2.4, 2.2 and 4.4 isomers of MDI and mixtures thereof are used.

[0057] • MDI generally produces tough, high-strength polyurethanes.

[0058] • 4,4'-MDI forms stiffer and less flexible structures, while 2,4 and 2,2 isomers provide more flexible products.

[0059] • MDI shows excellent performance, especially under heavy load, and performs well at low temperature.

[0060] Toluene Diisocyanate (TDI):

[0061] • TDI comprises 2,4 and 2,6 isomers and mixtures thereof.

[0062] • TDI is often used in the production of flexible foams and elastomers.

[0063] • Adhesives comprising TDI have high elasticity and good adhesion properties.

[0064] • TDI provides effective curing at lower temperatures and creates lighter adhesives. Hexamethylene Diisocyanate (HDI):

[0065] • HDI is an aliphatic diisocyanate and does not yellow when exposed to UV light.

[0066] • When used in adhesives, HDI provides good weather resistance and aesthetic appearance.

[0067] • HDI is generally preferred for thin film applications and exhibits high chemical resistance. Isophorone Diisocyanate (IPDI):

[0068] • IPDI is an aliphatic diisocyanate and offers high UV resistance.

[0069] • Adhesives comprising IPDI provide flexibility and high wear resistance.

[0070] • IPDI creates long-lasting and durable adhesives that are particularly suitable for outdoor applications.

[0071] Tetramethylxylene Diisocyanate (TMXDI):

[0072] • TMXDI is an aliphatic diisocyanate with a unique structure.

[0073] • When used in adhesives, TMXDI provides high elasticity and excellent low temperature performance.

[0074] • TMXDI offers superior resistance to water and other environmental factors.

[0075] The materials described above as di isocyanate can be used in the range of 20-33% by weight in the scope where the invention is desired to be protected. In the preferred embodiment of the invention, where performance and optimization tests were performed, the adhesive composition comprises 25% Hexamethylene diisocyanate by weight.

[0076] Curing feature can be achieved at 10°C with CaCOs, Carbodiimide and Hexamethylene diisocyanate used in the preferred embodiment of the invention. As a result of the inclusion of carboxylic acids in calcium carbonate in the reaction of hexamethylene diisocyanate and N, N'-(2-methyl -1 ,5-pentanediyl)bi-aspartic acid 1 , 1 ',4,4'-tetra ethyl ester thanks to the environment provided by carbodiimide, and as a result of the reaction of carboxylic acids formed in the product in contact with moisture, the number of polyurea bonds increases, and since the number of cross-links is increased, the desired fast and low temperature curing can be achieved.

[0077] The addition of diisocyanate under inert gas mentioned in method step c. prevents impurities that may occur as a result of a reaction other than the desired reactions, provides a safer production and increases the speed of the reaction by preventing the reaction from being affected by external factors. In the preferred embodiment of the invention, nitrogen is used as inert gas, but this method step can also be used under a different inert gas or in a vacuum environment. Choosing nitrogen both reduces costs and can create a safer environment than the use of alternative gases or vacuum. The protection scope of the invention is specified in the appended claims and cannot be limited to the description made for illustrative purposes in this detailed description. Likewise, it is clear that a person skilled in the art can present similar embodiments in the light of the above descriptions without departing from the main theme of the invention.

Claims

CLAIMS1. An adhesive used to structurally bond materials together and the production method thereof, characterized in that, to ensure curing at a temperature of at least 10°C, it comprises the following methods steps; a. mixing a material in polyaspartic ester structure with an amine value between 200 - 205 mg*KOH / g with a cross-linking agent, b. adding filling material to the mixture and mixing, c. adding a material with a diisocyanate structure to the mixture obtained at the end of the method step b. under inert gas or in a vacuum environment.

2. Method according to claim 1 , characterized in that; in the method step a. N,N'- (2-methyl-1 ,5- pentanediyl)bi-aspartic acid 1 ,1 ',4, 4' -tetra ethyl ester or N,N'-(3,3- dimethyldicyclohexylmethane-4,4'-diyl)-bi-aspartic acid tetra ethyl ester with an amine value between 200 - 205 mg*KOH / g is used as the material in the polyaspartic ester structure.

3. Method according to claim 1 , characterized in that; in the method step a. Carbodiimid is used as the crosslinking agent.

4. Method according to claim 1 , characterized in that; in the method step b., one of the individuals or combinations selected from the group consisting of calcium carbonate, barium sulfate, aluminum hydroxide, feldspar, titanium dioxide, silicon dioxide, talc, basalt, bentonite, kaolin and mica is added to the mixture.

5. Method according to claim 1 , characterized in that; in the method step c., one of the individuals or combinations selected from the group consisting of diphenylmethane diisocyanate (MDI) comprising 2,4, 2,2 and 4,4 isomers and mixtures thereof; toluene diisocyanate (TDI) comprising 2,4, 2,6 isomers and mixtures thereof; hexamethylene diisocyanate (HDI); isophorone diisocyanate (IPDI) and tetramethylxylene diisocyanate (TMXDI) as materials in the diisocyanate structure is added to the mixture obtained in method step b.

6. An adhesive composition used for structurally bonding materials together, characterized in that; to ensure curing at a temperature of at least 10°C, comprises the following;• Material with polyaspartic ester structure in the range of 25-40% by weight,• Cross-linking agent in the range of 0, 1 -1 ,0% by weight,• Filling material in the range of 59-74% by weight,• Material in the diisocyanate structure in the range of 20-33% by weight.

7. Composition according to claim 6, characterized in that; the polyaspartic ester material is N,N'-(2-methyl -1 ,5- pentanediyl)bi-aspartic acid 1 ,1 ',4, 4' -tetra ethyl ester or N,N'-(3,3-dimethyldicyclohexylmethane-4,4'-diyl)-bi-aspartic acid tetra ethyl ester with an amine value between 200 and 205 mg*KOH / g.

8. Composition according to claim 6, characterized in that; the cross-linking agent is Carbodiimide.

9. Composition according to claim 6, characterized in that; the filling material consists of one of the individuals or combinations selected from the group consisting of calcium carbonate, barium sulphate, aluminum hydroxide, feldspar, titanium dioxide, silicon dioxide, talc, basalt, bentonite, kaolin and mica.

10. Composition according to claim 6, characterized in that; materials in the diisocyanate structure is one of the individuals or combinations selected from the group consisting of diphenylmethane diisocyanate (MDI) comprising 2,4, 2,2 and 4,4 isomers and mixtures thereof; toluene diisocyanate (TDI) comprising 2,4, 2,6 isomers and mixtures thereof; hexamethylene diisocyanate (HDI); isophorone diisocyanate (IPDI) and tetramethylxylene diisocyanate (TMXDI).