An industrial couplant based on linalool for ultrasonic non-destructive testing and a preparation method thereof

Abstract

The application relates to a linalool-based industrial couplant for ultrasonic nondestructive testing and a preparation method thereof. The couplant is prepared from natural linalool, an environmentally-friendly raw material, and benzyl phosphate is added to change the connection structure of the molecular chain, so that a unique high-molecular gel network is prepared, the acoustic matching property of the couplant is effectively improved, and acoustic scattering is reduced. Meanwhile, the introduction of the benzene ring structure and the phosphorus-containing compound improves the high-temperature resistance and wear resistance of the couplant, so that the industrial couplant with the wide-temperature adaptability, the thermal stability and the environmental protection compatibility is prepared, and the industrial couplant is suitable for ultrasonic nondestructive testing of various types of industrial products.

Description

Technical Field

[0001] This invention relates to nondestructive testing coupling agents and their preparation methods, specifically to a linalool-based industrial coupling agent for ultrasonic nondestructive testing and its preparation method. Background Technology

[0002] Ultrasonic nondestructive testing (NDT) technology, as a core means of industrial quality control, is widely used in aerospace, energy equipment, and rail transportation. Its principle is based on the propagation characteristics of ultrasonic waves in materials to identify internal defects. During the testing process, the ultrasonic transducer needs to be in close contact with the surface of the workpiece to achieve efficient sound energy transmission. However, air gaps significantly hinder ultrasonic wave penetration, leading to signal attenuation and decreased testing accuracy. Therefore, industrial coupling agents are applied as sound-transmitting media at the interface between the ultrasonic probe and the workpiece. Their main functions are to eliminate air, improve sound transmission efficiency, and reduce friction to protect the probe.

[0003] Traditional industrial coupling agents such as water, engine oil, or chemical pastes are inexpensive and easy to use, but they have significant limitations. Water is prone to runoff and may cause workpiece corrosion; engine oil and transformer oil, while providing stable coupling effects, pose environmental pollution risks; chemical pastes (such as carboxymethyl cellulose), while suitable for rough surfaces, leave residues after drying, affecting the workpiece's appearance and subsequent processing. These drawbacks are particularly pronounced in the inspection of workpieces at high or low temperatures or with complex curved surfaces, limiting the application of ultrasonic technology under extreme conditions.

[0004] With the rapid development of my country's equipment manufacturing industry, the requirements for testing efficiency and environmental protection are increasing. Existing industrial coupling agents are insufficient to meet the demands of wide temperature range or high-precision imaging, and some materials may damage probes or interfere with signals. For example, patent application number 202311855442.X discloses an industrial coupling agent prepared from perfluoropolyether base oils with low, medium, and high viscosity ranges and composite additives, which can simultaneously meet high and low temperature operating conditions. Furthermore, the trend of green manufacturing is driving the industry to shift towards biodegradable and low-toxicity coupling agents to reduce the environmental burden of industrial waste. For example, patent application number 201710165537.3 discloses a water-soluble composition ultrasonic flaw detection coupling agent, avoiding the environmental pollution and harm to human health caused by solvent-based coupling agents.

[0005] Currently, the bottlenecks in this technology lie in the acoustic matching, thermal stability, and environmental compatibility of the coupling agent. There is an urgent need for a new type of industrial coupling agent that can efficiently fill microscopic gaps to improve ultrasonic wave transmittance, while also possessing wide temperature adaptability, rapid wetting, and cleanability, thereby overcoming the shortcomings of traditional materials and providing a reliable guarantee for high-precision non-destructive testing. Summary of the Invention

[0006] The purpose of this invention is to provide an industrial coupling agent for ultrasonic nondestructive testing based on linalool and its preparation method. This coupling agent uses natural linalool as an environmentally friendly raw material. The addition of benzyl phosphate alters the molecular chain connection structure, creating a unique polymeric gel network that effectively improves the acoustic matching of the coupling agent and reduces sound scattering. Simultaneously, the introduction of benzene ring structures and phosphorus-containing compounds improves the coupling agent's high-temperature resistance and wear resistance, resulting in an industrial coupling agent with wide temperature adaptability, thermal stability, and environmental compatibility, applicable to ultrasonic nondestructive testing of various industrial products. This coupling agent has a wide operating temperature range, moderate viscosity, good fluidity, high thermal stability, low acoustic impedance, and is more environmentally friendly.

[0007] The objective of this invention is achieved through the following technical solution: A linalool-based industrial coupling agent for ultrasonic nondestructive testing, wherein the coupling agent is prepared from the following raw materials in parts by weight: Linalool 60-80 parts; 28-40 parts of benzylphosphonic acid; 10-15 parts of co-solvent; Catalyst 0.2-1 part; 50-80 parts of phenol; 1 part acid catalyst; Sodium hydroxide 0.5-2 parts; 2-3 parts of silane coupling agent; Antioxidant 5-10 parts; 0.2-0.8 parts of defoamer.

[0008] The aforementioned linalool-based industrial coupling agent for ultrasonic non-destructive testing, wherein the latent solvent is one or more of low molecular weight polyethylene glycol and glycerol.

[0009] The aforementioned linalool-based industrial coupling agent for ultrasonic non-destructive testing, wherein the catalyst is one or more of aluminum oxide and concentrated sulfuric acid.

[0010] The aforementioned linalool-based industrial coupling agent for ultrasonic non-destructive testing, wherein the acid catalyst is one or more of concentrated sulfuric acid, concentrated phosphoric acid, and concentrated hydrochloric acid.

[0011] The aforementioned linalool-based industrial coupling agent for ultrasonic nondestructive testing, wherein the silane coupling agent is one or more of K550, K560, and K570.

[0012] The aforementioned linalool-based industrial coupling agent for ultrasonic non-destructive testing includes an antioxidant comprising a corrosion inhibitor and a rust inhibitor; preferably, the corrosion inhibitor is one or more of a thiadiazole derivative and a metal passivating agent; preferably, the rust inhibitor is one or more of a fatty acid amine and a sulfonate.

[0013] A method for preparing a linalool-based industrial coupling agent for ultrasonic nondestructive testing, the method comprising the following preparation steps: (1) After mixing linalool, benzyl phosphoric acid and co-solvent in the weight ratio, add the catalyst and continue mechanical stirring at 90°C for 60 min to 80 min until benzyl phosphoric acid is completely dissolved and the liquid viscosity increases. (2) After adding the melted phenol solution in proportion, add the acid catalyst dropwise, stir continuously and heat to 130℃~140℃, and react for 160min~190min; (3) After the liquid cools down naturally, add sodium hydroxide dropwise and continue stirring until no more solids precipitate out of the solution; (4) Filter the liquid and remove water from the solution by vacuum distillation; (5) Add silane coupling agent, antioxidant and defoamer in sequence according to the proportion. While adding the component additives, continue to stir the liquid for 60 min to 120 min. After the liquid is completely transparent, the linalool-based industrial coupling agent is obtained.

[0014] The significant features and beneficial effects of this invention are: 1. The coupling agent of this invention uses natural linalool as an environmentally friendly raw material. The addition of benzyl phosphate changes the connection structure of the molecular chain, preparing a unique polymer gel network, which effectively improves the acoustic matching of the coupling agent and reduces sound scattering. At the same time, the introduction of benzene ring structure and phosphorus-containing compounds improves the high temperature resistance and wear resistance of the coupling agent, making it an industrial coupling agent with wide temperature adaptability, thermal stability and environmental compatibility, which can be applied to ultrasonic non-destructive testing of various types of industrial products.

[0015] 2. The coupling agent prepared by this invention has a wide operating temperature range, moderate viscosity, good fluidity, high thermal stability, low acoustic impedance, and is more environmentally friendly. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the embodiments.

[0017] This invention discloses a linalool-based industrial coupling agent for ultrasonic non-destructive testing, which is prepared from the following raw materials in the indicated weight proportions: Linalool 60-80 parts; 28-40 parts of benzylphosphonic acid; 10-15 parts of co-solvent; Catalyst 0.2-1 part; 50-80 parts of phenol; 1 part acid catalyst; Sodium hydroxide 0.5-2 parts; 2-3 parts of silane coupling agent; Antioxidant 5-10 parts; Defoamer 0.2-0.8 parts; Its potential solvent is one or more of low molecular weight polyethylene glycol and glycerol. The catalyst is one or more of alumina and concentrated sulfuric acid. The acid catalyst is one or more of concentrated sulfuric acid, concentrated phosphoric acid, and concentrated hydrochloric acid. The silane coupling agent is one or more of K550, K560, and K570. Antioxidants include corrosion inhibitors and rust inhibitors. Corrosion inhibitors are one or more of thiadiazole derivatives and metal passivators. Rust inhibitors are one or more of fatty acid amines and sulfonates. The defoamer is a silicone polymer or an acrylate copolymer.

[0018] This invention provides a method for preparing a linalool-based industrial coupling agent for ultrasonic nondestructive testing, comprising the following steps: (1) After mixing linalool, benzyl phosphoric acid and co-solvent in a certain weight ratio, add a small amount of catalyst and continue mechanical stirring at 90°C for 60 min to 80 min until benzyl phosphoric acid is completely dissolved and the liquid viscosity increases. (2) After adding the melted phenol solution in proportion, add the acid catalyst dropwise, stir continuously and heat to 130℃~140℃, and react for 160min~190min; (3) After the liquid cools down naturally, add sodium hydroxide dropwise and continue stirring until no more solids precipitate out of the solution; (4) Filter the liquid and remove water from the solution by vacuum distillation; (5) Add silane coupling agent, antioxidant and defoamer in sequence according to the proportion. While adding each component additive, continue stirring the liquid for 60 min to 120 min. After the liquid is completely transparent, the linalool-based industrial coupling agent is obtained.

[0019] The reaction process of this invention is divided into the following two reaction stages: I:

[0020] II: .

[0021] Example 1 Weigh 60 parts linalool, 30 parts benzyl phosphoric acid, and 10 parts polyethylene glycol into a three-necked flask equipped with a reflux condenser and mix thoroughly. Heat to 90°C, add 0.5 parts alumina, and mechanically stir continuously at 90°C for 60 minutes. Then add 50 parts phenol solution and dropwise add 1 part concentrated sulfuric acid. Stir at a constant speed and heat to 130°C, maintaining the temperature for 165 minutes. After the reaction is complete, allow the liquid to cool naturally to room temperature. Transfer the liquid to a beaker, add sodium hydroxide dropwise, and stir continuously until no more solids precipitate. Filter the liquid using a filter paper funnel and dehydrate under vacuum to obtain the base oil for preparing the coupling agent. Add 2 parts K570 silane coupling agent, 3 parts metal passivator, and 5 parts sulfonate to the oil sequentially. Stir at a constant speed at room temperature for 80 minutes. Then add 0.5 parts silicone polymer and stir continuously until the liquid is completely transparent to obtain the desired linalool-based industrial coupling agent. Example 2

[0022] Weigh 60 parts linalool, 40 parts benzyl phosphoric acid, and 15 parts polyethylene glycol into a three-necked flask equipped with a reflux condenser and mix thoroughly. Heat to 90°C, add 0.7 parts alumina, and mechanically stir continuously at 90°C for 80 minutes. Then add 50 parts phenol solution and dropwise add 1 part concentrated sulfuric acid. Stir at a constant speed and heat to 130°C, maintaining the temperature for 170 minutes. After the reaction is complete, allow the liquid to cool naturally to room temperature. Transfer the liquid to a beaker, add sodium hydroxide dropwise, and stir continuously until no more solids precipitate. Filter the liquid using a filter paper funnel and dehydrate under vacuum to obtain the base oil for preparing the coupling agent. Add 3 parts K570 silane coupling agent, 3 parts metal passivator, and 5 parts sulfonate to the oil sequentially. Stir at a constant speed at room temperature for 100 minutes. Then add 0.5 parts silicone polymer and continue stirring until the liquid is completely transparent to obtain the desired linalool-based industrial coupling agent. Example 3

[0023] Weigh 70 parts linalool, 30 parts benzyl phosphoric acid, and 10 parts polyethylene glycol into a three-necked flask equipped with a reflux condenser and mix thoroughly. Heat to 90°C, add 0.5 parts alumina, and mechanically stir continuously at 90°C for 65 minutes. Then add 60 parts phenol solution and dropwise add 1 part concentrated sulfuric acid. Stir at a constant speed and heat to 135°C, maintaining the temperature for 180 minutes. After the reaction is complete, allow the liquid to cool naturally to room temperature. Transfer the liquid to a beaker, add sodium hydroxide dropwise, and stir continuously until no more solids precipitate. Filter the liquid using a filter paper funnel and dehydrate under vacuum to obtain the base oil for preparing the coupling agent. Add 2 parts K570 silane coupling agent, 3 parts metal passivator, and 5 parts sulfonate to the oil sequentially. Stir at a constant speed at room temperature for 80 minutes. Then add 0.5 parts silicone polymer and stir continuously until the liquid is completely transparent to obtain the desired linalool-based industrial coupling agent. Example 4

[0024] Weigh 70 parts linalool, 40 parts benzyl phosphoric acid, and 15 parts polyethylene glycol into a three-necked flask equipped with a reflux condenser and mix thoroughly. Heat to 90°C, add 0.7 parts alumina, and mechanically stir continuously at 90°C for 80 minutes. Then add 60 parts phenol solution and dropwise add 1 part concentrated sulfuric acid. Stir at a constant speed and heat to 135°C, maintaining the temperature for 180 minutes. After the reaction is complete, allow the liquid to cool naturally to room temperature. Transfer the liquid to a beaker, add sodium hydroxide dropwise, and stir continuously until no more solids precipitate. Filter the liquid using a filter paper funnel and dehydrate under vacuum to obtain the base oil for preparing the coupling agent. Add 3 parts K570 silane coupling agent, 3 parts metal passivator, and 5 parts sulfonate to the oil sequentially. Stir at a constant speed at room temperature for 100 minutes. Then add 0.5 parts silicone polymer and stir continuously until the liquid is completely transparent to obtain the desired linalool-based industrial coupling agent.

[0025] Performance testing The linalool-based industrial coupling agents prepared in Examples 1-4 of this invention were tested for acoustic impedance, high temperature resistance, viscosity, and pH value. The specific test results are compared with the performance of ordinary engine oil ultrasonic coupling agents in the table below.

[0026]

[0027] As shown in the table above, the industrial coupling agents in Examples 1-4 exhibit significantly increased heat resistance due to the introduction of benzyl phosphate and benzene rings. The formation of the molecular cross-linking network slightly increases the viscosity of the coupling agent, but the increase is small and does not affect normal ultrasonic non-destructive testing. Furthermore, the coupling agent retains the excellent acoustic impedance performance of oil-based ultrasonic coupling agents. In other words, the linalool-based industrial coupling agent of this invention possesses excellent thermal stability and acoustic matching, and its pH value is neutral, making it environmentally friendly.

Claims

1. A linalool-based industrial coupling agent for ultrasonic non-destructive testing, characterized in that, The coupling agent is prepared from the following raw materials in the following weight proportions: Linalool 60-80 parts; 28-40 parts of benzylphosphonic acid; 10-15 parts of co-solvent; Catalyst 0.2-1 part; 50-80 parts of phenol; 1 part acid catalyst; Sodium hydroxide 0.5-2 parts; 2-3 parts of silane coupling agent; Antioxidant 5-10 parts; 0.2-0.8 parts of defoamer.

2. The linalool-based industrial coupling agent for ultrasonic nondestructive testing according to claim 1, characterized in that, The potential solvent is one or more of low molecular weight polyethylene glycol and glycerol.

3. The linalool-based industrial coupling agent for ultrasonic nondestructive testing according to claim 1, characterized in that, The catalyst is one or more of aluminum oxide and concentrated sulfuric acid.

4. The linalool-based industrial coupling agent for ultrasonic nondestructive testing according to claim 1, characterized in that, The acid catalyst is one or more of concentrated sulfuric acid, concentrated phosphoric acid, and concentrated hydrochloric acid.

5. The linalool-based industrial coupling agent for ultrasonic nondestructive testing according to claim 1, characterized in that, The silane coupling agent is one or more of K550, K560, and K570.

6. The linalool-based industrial coupling agent for ultrasonic nondestructive testing according to claim 1, characterized in that, The antioxidant includes a preservative and a rust inhibitor; preferably, the preservative is one or more of a thiadiazole derivative and a metal passivating agent; preferably, the rust inhibitor is one or more of a fatty acid amine and a sulfonate.

7. A method for preparing an linalool-based industrial coupling agent for ultrasonic nondestructive testing, characterized in that, The method includes the following preparation steps: (1) After mixing linalool, benzyl phosphoric acid and co-solvent in the weight ratio, add the catalyst and continue mechanical stirring at 90°C for 60 min to 80 min until benzyl phosphoric acid is completely dissolved and the liquid viscosity increases. (2) After adding the melted phenol solution in proportion, add the acid catalyst dropwise, stir continuously and heat to 130℃~140℃, and react for 160min~190min; (3) After the liquid cools down naturally, add sodium hydroxide dropwise and continue stirring until no more solids precipitate out of the solution; (4) Filter the liquid and remove water from the solution by vacuum distillation; (5) Add silane coupling agent, antioxidant and defoamer in sequence according to the proportion. While adding the component additives, continue to stir the liquid for 60 min to 120 min. After the liquid is completely transparent, the linalool-based industrial coupling agent is obtained.

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