An adhesive and its preparation method and application

Abstract

The present application relates to the technical field of adhesive, in particular to an adhesive, a preparation method and application thereof, comprising component A and component B, wherein the component A comprises castor oil 30-40 parts, polyether polyol 5-20 parts, fumed silica 0.8-3 parts, glycerol 0.1-1 part, filler 40-60 parts, molecular sieve 2-5 parts, thixotropic agent 2-5 parts, chain extender 0.1-0.8 part and auxiliary agent 0.1-0.8 part by weight; the component B comprises isocyanate; the viscosity of the polyether polyol at 25 DEG C is less than or equal to 4000 mPa.s, and the hydroxyl value is 15-40 mgKOH / g.The adhesive prepared by the present application has excellent workable time (more than 40 min), sag displacement difference (less than or equal to 1 cm), tensile shear strength (more than 10 MPa) and colloid hardness (more than 80).

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to an adhesive, its preparation method, and its application. Background Technology

[0002] In the mass production of vans, bonding finished sheet metal to finished sheet metal (extruded polystyrene) sheets and to the metal structural components of the van body is one of the core processes. The quality of this bonding directly affects the structural stability, durability, and production efficiency of the vehicle. Currently, the general-purpose adhesives widely used in the industry exhibit numerous insurmountable technical defects in this scenario, severely restricting production efficiency and product quality: extruded polystyrene sheets have smooth surfaces and low density, while the metal structural components of the van body have surface tension differences. When applying traditional adhesives to vertical or inclined surfaces, due to insufficient thixotropy, adhesive dripping is highly likely, affecting the vehicle's appearance and the assembly accuracy of other components. Simultaneously, vans must withstand vibrations, impacts, and varying environmental temperatures during transportation, placing stringent requirements on the strength of the adhesives. Furthermore, excessively short operating windows force workers to compress the construction process, leading to insufficient bonding and significantly reducing production efficiency.

[0003] Chinese invention patent CN119432302B discloses an adhesive for bonding polished aluminum in tooling and its preparation method. By controlling the selection and combination of polyols, dispersants, and catalysts in the system, as well as the amount of each raw material added, the provided adhesive achieves a roller peel strength ≥60N when used for bonding polished aluminum (1-2mm) to honeycomb panels, meeting the requirements of practical exterior wall applications. However, this patent only addresses the bonding scenario of aluminum honeycomb panels to polished aluminum and does not explore the thixotropy, tensile shear strength, or operating window of the adhesive, thus limiting its application scope. Summary of the Invention

[0004] The first aspect of this invention provides an adhesive comprising component A and component B. By weight, component A comprises: 30-40 parts castor oil, 5-20 parts polyether polyol, 0.8-3 parts fumed silica, 0.1-1 parts glycerol, 40-60 parts filler, 2-5 parts molecular sieve, 2-5 parts thixotropic agent, 0.1-0.8 parts chain extender, and 0.1-0.8 parts additives; component B comprises isocyanate; the polyether polyol has a viscosity ≤4000 mPa•s at 25°C and a hydroxyl value of 15-40 mgKOH / g.

[0005] The isocyanate includes diphenylmethane diisocyanate (MDI).

[0006] Optionally, the polyether polyol has a viscosity of ≤4000 mPa•s at 25°C and a hydroxyl value of 20-30 mg KOH / g.

[0007] Optionally, the polyether polyol has a viscosity of 500-1000 mPa•s at 25°C and a hydroxyl value of 21-27 mgKOH / g.

[0008] This study found that limiting the viscosity of polyether polyols to ≤4000 mPa・s at 25℃ and the hydroxyl value to 15-40 mgKOH / g can optimize performance through multiple synergistic effects: the moderate viscosity can prevent the system from losing fluidity prematurely due to excessive viscosity (shortening the operation time), and can also synergize with the three-dimensional network formed by the thixotropic agent (polyamide wax) and fumed silica to maintain the stability of the colloidal structure and improve anti-sagging properties; while the hydroxyl value range of 15-40 mgKOH / g can ensure that its reaction rate with component B MDI is in a balanced state - the number of hydroxyl groups is not too many (avoiding the reaction being too fast and shortening the operation time) nor too few (ensuring that the molecular chains are long enough to support the structure after curing), and at the same time, it complements the hydroxyl groups of castor oil, jointly participating in the cross-linking reaction, thereby extending the operation time and enhancing the anti-sagging ability of the colloidal structure through a stable molecular skeleton.

[0009] Optionally, by weight, component A includes: 30-40 parts castor oil, 5-15 parts polyether polyol, 1-3 parts fumed silica, 0.1-1 part glycerin, 40-50 parts filler, 2-5 parts molecular sieve, 2-5 parts thixotropic agent, 0.1-0.5 parts chain extender, and 0.1-0.5 parts auxiliaries.

[0010] The amount of fumed silica added to the adhesive is 1-3 wt%.

[0011] Optionally, the amount of fumed silica added to the adhesive is 1.5-2.5 wt%.

[0012] When the amount of fumed silica is limited to 1-3wt%, the abundant hydroxyl groups on the surface of fumed silica can form hydrogen bonds with the polar groups of the thixotropic agent (polyamide wax), constructing a superimposed three-dimensional network structure: fumed silica particles are uniformly dispersed in the system, enhancing the stability of the thixotropic network, and the amount of 1-3wt% can ensure that the network density is sufficient to resist the action of gravity when placed vertically, and it will not cause the system to be rigidified due to excessive amount. At the same time, the fumed silica in this amount can also synergize with active calcium, heavy calcium and other powders, further inhibiting colloidal flow through mechanical interlocking between particles, and together with the thixotropic agent, the sag displacement difference is controlled to be ≤1cm. Further research found that when the amount of fumed silica is limited to 1.5-2.5wt%, in addition to synergizing with the thixotropic agent to build an anti-sag network, it can also improve the mechanical properties through synergistic effect with other components in the system: fumed silica particles in this range are more uniformly dispersed, and their high specific surface area can form stronger interfacial bonding force with castor oil and polyether polyol, acting as a reinforcing phase embedded in the colloidal matrix; at the same time, fumed silica and active calcium, heavy calcium and other powders form a gradient filling structure, reducing internal porosity after solidification, on the basis of ensuring the sag performance, through the synergy of particle reinforcement and molecular chain crosslinking, the tensile shear strength is improved to ≥10MPa, and the dense structure makes the colloidal hardness maintain ≥80.

[0013] The filler includes active calcium, calcium oxide and heavy calcium, and the weight ratio of the active calcium, calcium oxide and heavy calcium is 1:(0.1-0.8):(0.5-2.5).

[0014] Optionally, the weight ratio of the active calcium, calcium oxide and heavy calcium is 1:(0.1-0.5):(0.7-1.5).

[0015] The weight ratio of the castor oil and polyether polyol is (3.5-5.5):1.

[0016] The thixotropic agent includes at least one of hydrogenated castor oil, polyamide wax, organic bentonite, polyurea wax, modified hydrogenated castor oil and attapulgite.

[0017] The chain extender includes at least one of 1,4-butanediol, propylene glycol, ethylene glycol, 1,6-hexanediol, neopentyl glycol and diethylene glycol.

[0018] The auxiliary agent includes a plasticizer and a defoaming agent.

[0019] The defoaming agent includes a silicone defoaming agent.

[0020] Optionally, the defoaming agent is selected from the brand SX08 of Sijin Technology.

[0021] The plasticizer includes at least one of epoxy fatty acid methyl ester, dioctyl phthalate, dioctyl adipate, epoxy soybean oil, tributyl citrate and dioctyl sebacate.

[0022] The performance balance can be achieved by the synergistic effect of adding a certain content of the thixotropic agent and the chain extender: the crystal network formed by the thixotropic agent polyamide wax can delay the thickening speed of the system, and the hydrogen bond network of the fumed silica can cooperate to maintain the colloidal fluidity, so that the operation time is prolonged to more than 42 min; and the appropriate chain extender (such as 0.2 parts of propylene glycol) can be selectively reacted with isocyanate to prolong the molecular chain length and optimize the crosslinking density, so as to avoid the low strength caused by insufficient chain extension, and also to avoid the rapid reaction caused by excessive amount. Under the synergistic effect of the two, the thixotropic network guarantees the operation window, and the molecular structure after chain extension improves the mechanical properties, so that the tensile shear strength is greater than or equal to 10.9 MPa, and the colloidal hardness is greater than or equal to 84.

[0023] The second aspect of the present application provides a preparation method of an adhesive, comprising the following steps: first, uniformly mixing and dispersing castor oil, polyether polyol, fumed silica, glycerol and thixotropic agent; then, uniformly mixing and dispersing fillers and molecular sieves; finally, uniformly mixing and dispersing chain extenders and additives to obtain component A; preparing isocyanate to obtain component B.

[0024] Optionally, the preparation method of the component A comprises the following steps:

[0025] Step 1: using a double-planetary stirred tank, adding castor oil, polyether polyol, fumed silica, glycerol and thixotropic agent, stirring for 10-30 min, stirring rate 10-30 r / min, dispersion rate 900-1100 r / min;

[0026] Step 2: adding fillers and molecular sieves, stirring rate 10-30 r / min, dispersion rate 900-1100 r / min, stirring for 10-30 min;

[0027] Step 3: heating to 60-85℃, then stirring for 20-40 min, controlling the stirring rate 10-30 r / min and the dispersion rate 200-400 r / min;

[0028] Step 4: adding chain extenders and additives, stirring for 20-40 min;

[0029] Step 5: stirring while cooling to 50-70℃, stopping stirring, discharging, and obtaining the adhesive.

[0030] The third aspect of the present application provides an application of the adhesive, which is applied to the bonding of a car body structure component.

[0031] Optionally, the car body structure component comprises at least one of an extruded sheet and a metal piece.

[0032] Beneficial effects

[0033] 1、By limiting the viscosity of polyether polyol at 25℃ ≤4000mPa•s, the hydroxyl value is 15-40mgKOH / g, the operation time can be prolonged, and the sagging performance is improved.

[0034] 2、By limiting the addition amount of fumed silica in the adhesive to 1-3wt%, the sagging performance can be further improved, and the sagging displacement difference is ≤1cm.

[0035] 3、By limiting the addition amount of fumed silica in the adhesive to 1.5-2.5wt%, the tensile shear strength (≥10MPa) and the gel hardness (≥80) of the adhesive can be further improved on the basis of excellent sagging performance.

[0036] 4、By adding a specific content of thixotropic agent and chain extender, the operation time can be prolonged to more than 42min, and the tensile shear strength is ≥10.9MPa and the gel hardness is ≥84.

[0037] 5、The adhesive preparation method is simple, and can meet the bonding of carriage structure parts. DETAILED DESCRIPTION

[0038] Example 1

[0039] An adhesive includes A component and B component (MDI), and the A component is shown in Table 1, wherein the source of the components is shown in Table 2, and " / " means general chemical raw materials.

[0040] Table 1

[0041] Component Specific Material Ingredient / Specification Example 1 Example 2 Example 3 Castor oil / 35 32 38 Polyether polyol / 10 13 7 Fumed silica / 2 2 2 Glycerin / 0.5 0.5 0.5 Filler (active calcium) / 20 20 20 Filler (calcium oxide) / 6 6 6 Filler (heavy calcium) / 20 20 20 Molecular sieve 3A 3 3 3 Thixotropic agent Polyamide wax 3 3 3 Auxiliary (plasticizer) Epoxy fatty acid methyl ester 0.2 0.2 0.2 Chain extender Propylene glycol 0.2 0.2 0.2 Auxiliary (antifoaming agent) / 0.1 0.1 0.1

[0042] Table 2

[0043] Component Specific Material Ingredient / Specification Manufacturer Grade Castor oil First grade oil / Adani Polyether polyol / Wanhua Chemical WANOL POP3630 (25℃ viscosity 500-1000 mPa•s, hydroxyl value 21-27 mgKOH / g) Fumed silica / Wacker AEROSIL 200 Glycerin / / / Active calcium / Lingshou County Mountain River Mineral Product Processing Factory 1250 mesh Calcium oxide / / / Heavy calcium / Zhejiang Qintang Calcium Industry QT-7692 Molecular sieve 3A / / Thixotropic agent Polyamide wax Shanghai Yunhe Material Akema OPTIMA Plasticizer Epoxy fatty acid methyl ester / / Chain extender Propylene glycol / / Antifoaming agent / Sixin Technology SX08 antifoaming agent

[0044] The preparation method of the adhesive is the following steps:

[0045] Step 1, using double planetary stirred tank, adding castor oil, polyether polyol, fumed silica, glycerol, thixotropic agent, stirring for 20min, stirring rate 20r / min, dispersion rate 960r / min;

[0046] Step 2, add fillers and molecular sieves, stirring rate 20r / min, dispersion rate 960r / min, stirring for 20min;

[0047] Step 3, heating to 75℃, stirring for another 30min, controlling stirring rate 25r / min, dispersion rate 300r / min;

[0048] Step 4, add chain extender and auxiliary agent, stirring for 30min;

[0049] Step 5, stirring while cooling to 60°C, stop stirring, discharge, to get A component;

[0050] Step 6, prepare MDI, to get B component.

[0051] Comparative Example 1

[0052] The specific implementation is the same as Example 1; the difference is that in Comparative Example 1, the polyether polyol brand is: Wanhua WANOLF3056D (the polyether polyol has a viscosity of 400-700 mPa•s at 25°C, and a hydroxyl value of 56±1.5 mgKOH / g).

[0053] Comparative Example 2

[0054] The specific implementation is the same as Example 1; the difference is that in Comparative Example 2, the addition amount of fumed silica is 0.5 parts.

[0055] Comparative Example 3

[0056] The specific implementation is the same as Example 1; the difference is that in Comparative Example 3, the addition amount of active calcium is 10 parts, and the addition amount of heavy calcium is 30 parts.

[0057] Comparative Example 4

[0058] The specific implementation is the same as Example 1; the difference is that in Comparative Example 4, the addition amount of active calcium is 30 parts, and the addition amount of heavy calcium is 10 parts.

[0059] Comparative Example 5

[0060] The specific implementation is the same as Example 1; the difference is that in Comparative Example 5, no molecular sieve is added.

[0061] The preparation method of the adhesive is the following steps:

[0062] Step 1, use a double-planetary stirred tank, add castor oil, polyether polyol, fumed silica, glycerol, thixotropic agent, stir for 20 min, stirring speed 20 r / min, dispersion speed 960 r / min;

[0063] Step 2, add filler, stirring speed 20 r / min, dispersion speed 960 r / min, stir for 20 min;

[0064] Step 3, heat to 75°C, then stir for 30 min, control stirring speed 25 r / min, dispersion speed 300 r / min;

[0065] Step 4, add chain extender and auxiliary agent, stir for 30 min;

[0066] Step 5, stirring while cooling to 60°C, stop stirring, discharge, to get A component;

[0067] Step 6, prepare MDI to obtain component B.

[0068] Comparative Example 6

[0069] The specific implementation is the same as that of Example 1; the difference is that no thixotropic agent is added in Comparative Example 6.

[0070] The preparation method of the adhesive is as follows:

[0071] Step 1, use a double planetary stirred tank, add castor oil, polyether polyol, fumed silica, and glycerol, stir for 20 min, stirring rate 20 r / min, dispersion rate 960 r / min;

[0072] Step 2, add fillers and molecular sieves, stirring rate 20 r / min, dispersion rate 960 r / min, stir for 20 min;

[0073] Step 3, heat to 75°C, then stir for 30 min, control stirring rate 25 r / min, dispersion rate 300 r / min;

[0074] Step 4, add chain extender and auxiliary agent, stir for 30 min;

[0075] Step 5, stir while cooling to 60°C, stop stirring, discharge, to obtain component A;

[0076] Step 6, prepare MDI to obtain component B.

[0077] Comparative Example 7

[0078] The specific implementation is the same as that of Example 1; the difference is that the amount of thixotropic agent added in Comparative Example 7 is 6 parts.

[0079] Comparative Example 8

[0080] The specific implementation is the same as that of Example 1; the difference is that the amount of chain extender added in Comparative Example 8 is 1 part.

[0081] Performance test method

[0082] The adhesives prepared in the examples and comparative examples were tested for the following properties, and the test data are shown in Table 3.

[0083] 1. Workable time: after the components A and B are mixed evenly (components A and B are mixed at a weight ratio of 6:1), timing starts, and the ambient temperature is kept at room temperature (25±2°C) during the timing. The mixed adhesive is stirred and tried to be applied every 5 min. If obvious resistance is felt (the stirring torque increases by more than 50% compared with the initial state), stop timing. The time difference is the workable time (for compartment glue, customers usually require >40 min).

[0084] 2. SAG: A and B components were mixed uniformly (A and B components were mixed in a weight ratio of 6:1), applied to a vertically placed extruded plate (20 cm x 10 cm x 1 cm), and a line was drawn at the lowest point of the glue. After 20 min, the displacement difference of the glue was observed.

[0085] 3. Tensile shear strength: A and B components were mixed uniformly (A and B components were mixed in a weight ratio of 6:1), and GB / T 7124-2008 was referred to.

[0086] 4. Glue hardness: A and B components were mixed uniformly (A and B components were mixed in a weight ratio of 6:1), and a Shore hardness tester (Shore D) was used to test after curing at room temperature (25°C) for 12 h.

[0087] Performance test data

[0088] Table 3

[0089] Performance test Operable time min Sag displacement difference cm Tensile shear strength MPa Colloid hardness Example 1 45 0.2 11 84 Example 2 42 0.4 10.9 86 Example 3 47 0.2 11.2 84 Comparative Example 1 36 0.8 11 84 Comparative Example 2 42 1.5 10.4 82 Comparative Example 3 42 1.8 11 86 Comparative Example 4 42 0.4 8.8 76 Comparative Example 5 42 0.5 9 75 Comparative Example 6 45 12 10.8 80 Comparative Example 7 38 0.1 9.5 75 Comparative Example 8 38 0.2 9.4 80

[0090] As can be seen from the data in Table 3, the adhesives prepared in Examples 1-3 all have excellent workable time (> 40 min), SAG (≤ 1 cm), tensile shear strength (≥ 10 MPa), and glue hardness (≥ 80). However, the comparative examples cannot simultaneously have excellent workable time, SAG, tensile shear strength, and glue hardness because the components of the formulations are not within the preferred range.

Claims

1. An adhesive, characterized by, The A component includes castor oil 30-40 parts, polyether polyol 5-20 parts, fumed silica 0.8-3 parts, glycerol 0.1-1 part, filler 40-60 parts, molecular sieve 2-5 parts, thixotropic agent 2-5 parts, chain extender 0.1-0.8 part and auxiliary agent 0.1-0.8 part by weight; the B component includes isocyanate; the polyether polyol has viscosity ≤4000 mPa•s at 25℃ and hydroxyl value 15-40 mgKOH / g; The filler includes active calcium, calcium oxide and heavy calcium, and the weight ratio of the active calcium, calcium oxide and heavy calcium is 1:(0.1-0.8):(0.5-2.5).

2. The adhesive according to claim 1, characterized in that, The A component includes castor oil 30-40 parts, polyether polyol 5-15 parts, fumed silica 1-3 parts, glycerol 0.1-1 part, filler 40-50 parts, molecular sieve 2-5 parts, thixotropic agent 2-5 parts, chain extender 0.1-0.5 part and auxiliary agent 0.1-0.5 part by weight.

3. The adhesive according to claim 1 or 2, characterized in that, The addition amount of the fumed silica in the adhesive is 1-3 wt%.

4. The adhesive according to claim 3, characterized in that, The addition amount of the fumed silica in the adhesive is 1.5-2.5 wt%.

5. The adhesive of claim 1, wherein The weight ratio of the active calcium, calcium oxide and heavy calcium is 1:(0.1-0.5):(0.7-1.5).

6. The adhesive of claim 2, wherein The weight ratio of the castor oil and polyether polyol is (3.5-5.5):

1.

7. A process for the preparation of the adhesive according to any one of claims 1 to 6, characterized in that, The method includes the following steps: First, the castor oil, polyether polyol, fumed silica, glycerol and thixotropic agent are mixed and dispersed uniformly; then the filler and molecular sieve are mixed and dispersed uniformly; finally, the chain extender and auxiliary agent are mixed and dispersed uniformly to obtain the A component; the isocyanate is prepared to obtain the B component.

8. Use of the adhesive according to any one of claims 1 to 7, characterized in that, The adhesive is applied to a car body structure component.

9. Use of the adhesive according to claim 8, characterized in that, The car body structure component includes at least one of an extruded sheet and a metal piece. The car body structure component includes at least one of an extruded sheet and a metal piece.