Buffer block for air chamber for pump as well as preparation method and application of buffer block

Abstract

The invention belongs to the technical field of buffer materials, and particularly discloses a buffer block for an air chamber for a pump as well as a preparation method and application of the buffer block, raw materials for preparing a core layer of the buffer block comprise a polyurethane prepolymer and a chain extender composition A, and raw materials for preparing a shell layer of the buffer block comprise a polyurethane prepolymer and a chain extender composition B; the chain extender composition A comprises the following components in parts by weight: 60-80 parts of an MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 3-5 parts of water, 0.5-1 part of an antioxidant, 0.5-2 parts of a catalyst and 0.5-2.5 parts of a foam stabilizer; the chain extender composition B is prepared from 100-120 parts of an MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of a hydrolysis-resistant agent, 0.5-1 part of an antioxidant, 0.5-2 parts of a catalyst and 0.5-2.5 parts of a foam stabilizer, the whole buffer block can achieve an effective pressure stabilizing effect, can adapt to conveying media with complex properties, has excellent dynamic fatigue performance and is suitable for large-scale production. And when being applied to the air chamber structure of the slurry pump, the pressure of the slurry pump can be effectively stabilized for a long time, and the application prospect is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cushioning materials, and particularly relates to a cushion block for an air pack for a pump and a preparation method and application thereof. BACKGROUND

[0002] The mud pump is usually in the form of a three-cylinder plunger pump, which is a reciprocating pump, and the output pressure of the pump changes periodically during operation. The air pack installed at the outlet of the mud pump can balance the peak value of the high-pressure fluid pressure of the mud pump, play a role in stabilizing the pressure, reducing the loss and ensuring the safety, and make the mud pump achieve the best suction effect. The conventional air pack of the mud pump adopts a bag type structure, and the air pack structure has a nitrogen-filled air bag inside, and the air bag expands and contracts to buffer the high-pressure fluid pressure of the mud pump. The air pack of this type needs to be inflated and the air bag needs to be replaced regularly, which is troublesome for the workers to operate on site, has high maintenance cost, and poor safety. Based on the above problems, the prior art proposes a non-inflatable air pack, which has the advantages of easy maintenance, no need to inflate or replace the air bag, can suppress both flow pulse and acceleration pulse, has long service life, and avoids the safety risk of inflation.

[0003] In the prior art, the air pack for the drilling mud pump disclosed in CN112283062A adopts a shell in which a buffer inner container is arranged, and a buffer block assembly is arranged in the buffer inner container to stabilize the flow and pressure of the mud pump body. The performance of the buffer block in the structure of the buffer / air pack is a key factor directly affecting the flow stabilization and pressure stabilization effect.

[0004] Polyurethane elastomers are widely used in the field of cushioning materials and other fields due to their excellent wear resistance, high strength and excellent impact absorption performance, and are one of the commonly used materials for preparing cushion blocks. At present, the polyurethane elastomers of the MDI system are more commonly used in the market, have excellent mechanical properties and good prepolymer stability, but have the problem of poor dynamic fatigue resistance. In the face of complex operating conditions and conveying media of the mud pump, developing a cushion block with excellent mechanical properties and long service life is an effective way to expand the application prospect of the cushion block in the field of mud pumps. Therefore, the application provides a cushion block for an air pack for a pump and a preparation method and application thereof. SUMMARY

[0005] The application provides a cushion block for an air pack for a pump and a preparation method and application thereof to solve the above problems.

[0006] The application achieves the above-mentioned purposes through the following technical solutions. As a first aspect of the present application, a kind of air bag for pump buffer block is provided, the buffer block has core-shell structure, the raw materials for preparing buffer block core layer include polyurethane prepolymer and chain extender composition A, the raw materials for preparing buffer block shell layer include polyurethane prepolymer and chain extender composition B;According to parts by weight, The chain extender composition A includes MOCA chain extender 60-80 parts, hexanediol 40-60 parts, epoxy soybean oil 2-5 parts, hydrolysis resistant agent 1-1.5 parts, antioxidant 0.5-1 part, catalyst 0.5-2 parts and foam stabilizer 0.5-2.5 parts; The chain extender composition B includes MOCA chain extender 100-120 parts, modified calcium carbonate whisker 10-15 parts, hydrolysis resistant agent 1-1.5 parts, antioxidant 0.5-1 part, catalyst 0.5-2 parts and foam stabilizer 0.5-2.5 parts.

[0007] As a further optimization scheme of the present application, the amount of polyurethane prepolymer and chain extender composition A, chain extender composition B is 100:10-40.

[0008] As a further optimization scheme of the present application, the NCO content of the polyurethane prepolymer is 6-12 %.

[0009] As a further optimization scheme of the present application, the preparation method of the modified calcium carbonate whisker is: first, silane coupling agent is added to anhydrous ethanol, heated and stirred until completely dissolved to obtain a silane coupling agent solution, then calcium carbonate whisker is added to the silane coupling agent solution, ultrasonic dispersion, water bath stirring reaction, standing and drying to obtain modified calcium carbonate whisker.

[0010] As a further optimization scheme of the present application, the catalyst is triethylenediamine or bis (2-methoxyethyl) amine, the foam stabilizer is organosilicon surfactant, and the hydrolysis resistant agent is carbodiimide.

[0011] As a second aspect of the present application, a preparation method of the air bag for pump buffer block as described above is also provided, comprising the following steps: (1) Excess diphenylmethane diisocyanate is reacted with polyol at 80-85 ℃ to obtain polyurethane prepolymer, and the raw materials for preparing chain extender composition A are added to the polyurethane prepolymer to obtain the raw materials for preparing buffer block core layer; (2) Excess diphenylmethane diisocyanate is reacted with polyol at 80-85 ℃ to obtain polyurethane prepolymer, and the raw materials for preparing chain extender composition B are added to the polyurethane prepolymer to obtain the raw materials for preparing buffer block core layer; (3) The raw materials for preparing the shell and core layers of the buffer block are injected into a mold in a coaxial pouring mode to mold and form an elastomer, a gradient pressure is applied to the elastomer by the mold, and then the elastomer is demolded and aged.

[0012] As a further optimization of the present application, in step (1), the polyol is selected from polyester polyols with a hydroxyl value of 56-140 mgKOH / g and a number average molecular weight Mn of 2000-4000.

[0013] As a further optimization of the present application, in step (3), the gradient pressure is applied as follows: the elastomer is kept in a pressure-free state for 1-5 min, a pressure of 50-55 N is applied to the elastomer for 5-10 min, a pressure of 50-100 N is applied to the elastomer for 10-15 min, and the elastomer returns to a pressure-free state for 15-20 min.

[0014] As a third aspect of the present application, there is also provided a use of the buffer block for an air bag of a pump as described in any of the above aspects in a mud pump.

[0015] As a further optimization of the present application, the medium delivered by the mud pump is a corrosive mud containing acid or alkali.

[0016] In summary, the present application has the following advantages: The buffer block provided by the present application is prepared by a prepolymer method, diphenylmethane diisocyanate is reacted with a polyol to obtain a polyurethane prepolymer, which is then mixed with chain extender composition A and chain extender composition B respectively to obtain raw materials for preparing the shell and core layers of the buffer block, and the raw materials are then coaxially poured into a mold to mold and form an elastomer. The optimization of the components of chain extender composition A and chain extender composition B enables the core layer of the buffer block to have excellent toughness, the shell layer of the buffer block to have good strength, excellent acid and alkali resistance, and excellent wear resistance, and the overall buffer block to effectively stabilize the pressure, adapt to complex delivery media, and have excellent dynamic fatigue performance. When the buffer block is applied to the air bag structure of a mud pump, it helps to effectively stabilize the pressure of the mud pump for a long time, is practical and reliable, more durable, and has a good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A coaxial pouring diagram of the buffer block provided by the present application; Figure 2 Different shapes of the buffer block provided by the present application and the buffer block assembly applied to the air bag. DETAILED DESCRIPTION

[0018] The application will be described in further detail below with reference to the drawings. It is necessary to point out here that the following detailed description is only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Those skilled in the art can make some non-essential improvements and adjustments to the application according to the above description.

[0019] I. Materials and Methods The methods used in the application are conventional methods known to those skilled in the art, and if no specific conditions are indicated, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagents or instruments is indicated, they are conventional products that can be purchased on the market.

[0020] Diphenylmethane diisocyanate (MDI), purity ≥ 99.5 %; The polyol is selected from polyester polyols with a hydroxyl value of 56-140 mg KOH / g and a number average molecular weight Mn of 2000-4000. In the test content of the application, a polyhexanediol adipate polyol with a number average molecular weight Mn of 2000 and a hydroxyl value of 56 mg KOH / g is selected. MOCA (3,3 ， - dichloro-4,4 ， - diamino diphenyl methane) chain extender, which belongs to aromatic diamine chain extender, and the chemical formula is C 13 H 12 Cl2N2; Hexanediol (HDO), a symmetrical aliphatic dihydric alcohol with hydroxyl groups at both ends, with the chemical formula C6H 14 O2; Epoxidized soybean oil (ESO), with the chemical formula C 57 H 98 O 12 , epoxy value ≥ 6; Calcium carbonate whisker, needle-shaped single crystal, length 20-80 μm, diameter 0.5-2 μm, aspect ratio 20-30, density about 2.8 g / cm 3 , good thermal stability below 800 ℃; The catalyst is triethylenediamine or bis (2-methoxyethyl) amine; the foam stabilizer is an organic silicon surfactant; and the hydrolysis-resistant agent is a carbodiimide.

[0021] II. Test Content 1. Preparation of polyurethane prepolymer The polyhexanediol adipate polyol with a number average molecular weight Mn of 2000 and a hydroxyl value of 56 mg KOH / g is dehydrated at a temperature of about 110 ℃ for 2 h, then cooled to 50 ℃, and an excess of molten diphenylmethane diisocyanate (MDI) is added. The mixture is stirred rapidly to allow it to warm up naturally, and when the temperature is substantially constant, the mixture is heated to 80-85 ℃ and reacted for 2 h. The polyurethane prepolymer is degassed for 1 h. In the test content of the present application, the NCO content of the polyurethane prepolymer is controlled to be 8%.

[0022] 2. Preparation of the cushioning block with core-shell structure The raw materials for preparing the core layer of the cushioning block include the polyurethane prepolymer and the chain extender composition A, and the raw materials for preparing the shell layer of the cushioning block include the polyurethane prepolymer and the chain extender composition B.

[0023] In the present application, the chain extender composition A includes MOCA chain extender 60-80 parts, hexanediol 40-60 parts, epoxy soybean oil 2-5 parts, water 3-5 parts, catalyst 0.5-2 parts, foam stabilizer 0.5-2.5 parts, and antioxidant 0.5-1 part.

[0024] In the present application, the chain extender composition B includes MOCA chain extender 100-120 parts, modified calcium carbonate whisker 10-15 parts, hydrolysis-resistant agent 1-1.5 parts, catalyst 0.5-2 parts, foam stabilizer 0.5-2.5 parts, and antioxidant 0.5-1 part.

[0025] The preparation steps of the cushioning block with core-shell structure are as follows: First, the raw materials for preparing the chain extender composition A are added to the polyurethane prepolymer at a temperature of 60 ℃, and stirred and mixed uniformly to obtain the raw materials for preparing the core layer of the cushioning block. The raw materials for preparing the chain extender composition B are added to the polyurethane prepolymer at a temperature of 60 ℃, and stirred and mixed uniformly to obtain the raw materials for preparing the core layer of the cushioning block.

[0026] Then, the raw materials for preparing the shell layer and the core layer of the cushioning block are injected into a mold at a temperature of 65 ℃ in a coaxial pouring manner (pouring schematic diagram as shown in Figure 2 The elastic body is formed by molding; Finally, the mold is removed after the gradient pressure is applied to the elastic body, and the elastic body is cured at 90 ℃ for 12 h.

[0027] The gradient pressure refers to: maintaining the elastic body in a pressure-free state for 1-5 min, applying a pressure of 50-55 N to the elastic body for 5-10 min, applying a pressure of 50-100 N to the elastic body for 10-15 min, and returning the elastic body to a pressure-free state for 15-20 min.

[0028] 3. Verification test 3.1, Optimization of raw material ratio for preparing the core layer of the cushion block The raw materials for preparing the core layer of the cushion block include polyurethane prepolymer and chain extender composition A. The polyurethane prepolymer used is the same as that shown in Section 1. The chain extender composition A provided by the present application includes, in terms of parts by weight, 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxy soybean oil, 3-5 parts of water, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer, and 0.5-1 part of antioxidant. In order to obtain a core layer material of the cushion block with excellent performance, the raw material ratio of the chain extender composition A is adjusted according to Table 1.

[0029] Table 1, Raw material ratio of chain extender composition A ; According to the raw material ratio of the chain extender composition A shown in Table 1, the raw materials for preparing the chain extender composition A were added to the polyurethane prepolymer at a temperature of 60 °C, stirred and mixed uniformly, poured into a mold to foam, and when the opalescent time was reached, the mold was closed and placed under a pressure of 10 MPa to react and form a core layer test piece, which was denoted as A-1 to A-3, a-1 to a-3. The core layer test piece was demolded and aged at 90 °C for 12 h, and finally, after being placed at room temperature for 7 d, the core layer test piece was tested for the following test items: (1) The hardness of the test piece was tested using an elastomer-plastic Shore A hardness tester according to GB / T 531.1-2008.

[0030] (2) The tensile strength and elongation at break were tested using a universal testing machine according to ASTM D3574-17 standard, and the test piece size was required to be 150 mm x 25 mm x 10 mm, and the tensile rate was 500 mm / min.

[0031] (3) The compression set was tested according to DIN ISO 815-1:2016 standard, and the test piece size was required to be: diameter of 29.0 mm ± 0.5 mm, thickness of 12.5 mm ± 0.5 mm, the original height H0 and the spacer height H2 of the test piece were measured, the test piece height was compressed by 40 %, and was placed in a circulating air oven at 80 °C for 22 h; after taking out, the compressed state was maintained, and the room temperature was cooled for 2 h; after 10 min of pressure relief, the height H1 of the test piece was measured to an accuracy of 0.1 mm.

[0032] The compression set calculation formula is: Cs%= (H0-H1) / (H0-H2) x 100%.

[0033] The results are shown in Table 2.

[0034] Table 2, Performance test results ; As can be seen from Table 2, when the amount of MOCA chain extender is increased, the hardness and tensile strength of the test piece will increase to a certain extent, but the elongation at break will decrease accordingly. The reaction between MOCA and NCO produces more substituted urea groups, and MOCA itself contains benzene rings, which can provide rigidity for the hard segment, so that the regularity of the hard segment is improved, and the mechanical properties are improved.

[0035] Under the condition that the amount of chain extender composition A and the amount of the remaining components of chain extender composition A are consistent, the use of MOCA chain extender and hexanediol together has a positive effect on obtaining a core layer material with both strength and toughness, which is due to the fact that hexanediol is a linear small molecule with symmetrical structure, and the generated hard segment has a certain flexibility which is beneficial to the interlaced aggregation of soft and hard segments, reduces the degree of phase separation, and improves the elongation at break of the material.

[0036] Finally, comparing A-3 and a-3 test pieces, increasing the epoxy soybean oil in the binary chain extender system of MOCA chain extender and hexanediol has a positive effect on promoting the improvement of the elongation at break of the core layer material while ensuring the hardness and tensile strength of the core layer material, so that the core layer material has both strength and toughness.

[0037] 3.2, Optimization of raw material ratio for preparing the shell layer of the cushion block The raw materials for preparing the core layer of the cushion block include polyurethane prepolymer and chain extender composition A. The polyurethane prepolymer used is the same as that shown in Section 1. The chain extender composition B provided by the present application includes 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whisker, 1-1.5 parts of hydrolysis-resistant agent, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer, and 0.5-1 part of antioxidant.

[0038] In order to obtain a core layer material of the cushion block with excellent performance, the raw material ratio of chain extender composition B is adjusted according to Table 3.

[0039] Table 3, Raw material ratio of chain extender composition B ; According to the raw material ratio of chain extender composition B given in Table 3, the raw materials for preparing chain extender composition B are added to the polyurethane prepolymer under the condition of 60 ℃ temperature, and stirred and mixed uniformly. Pour into the mold to foam. When the milk white time is reached, the mold is closed and placed under a pressure of 10 Mpa for reaction molding to obtain the shell layer test piece, which is recorded as B-1 to B-3, b-1 to b-4. The core layer test piece is demolded and placed in a 90 ℃ curing oven for 12 h. Finally, it is placed in a normal temperature environment for 7 days.

[0040] The shell layer material is tested according to the same test items as the core layer material, and the results are shown in Table 4.

[0041] Table 4, performance test results ; As can be seen from Table 4, the amount of MOCA chain extender is positively correlated with the hardness and tensile strength of the shell material. By comparing the data of B-3 and b-4 test pieces, it can be seen that the combination of modified calcium carbonate whiskers and MOCA chain extender can promote the synchronous improvement of the strength and toughness of the shell material. The unmodified calcium carbonate whisker is not conducive to its dispersion in the polyurethane prepolymer. After modification by the surfactant, its dispersion performance can be improved, which helps to exert the synergistic effect of the MOCA chain extender. In addition, compared with the use of nano material-nano calcium carbonate, the modified calcium carbonate whisker has a more excellent effect on strengthening the structure of the shell material.

[0042] Further, the shell material as the outer material of the buffer block will directly contact the medium. The shell material with good medium adaptability has a positive significance for expanding the application scenarios of the buffer block. Therefore, the acid and alkali resistance and wear resistance of the shell material are tested.

[0043] The specific test items are as follows: (1) The acid and alkali resistance refers to the standard GB / T 13353-92. Sulfuric acid solution and sodium hydroxide solution with a mass concentration of 10% are selected. The shell test piece is immersed in the sulfuric acid solution and the sodium hydroxide solution, respectively. After 10 days, the mass change rate of each shell test piece is measured. The smaller the mass change rate, the stronger the acid and alkali resistance. The mass before immersion is denoted as M0, and the mass after immersion is denoted as M1. Mass change rate (%) = { (M0-H1) / M0} x 100%.

[0044] (2) The wear resistance refers to the standard GB / T 1689-2014. The shell material is fixed on an Akron abrasion tester and rubbed with a grinding wheel at a specified inclination angle (usually 15°±0.5°) and load (26.7 N±0.2 N). After a specified mileage (1.61 km), the mass loss of the test piece is measured, and the abrasion volume is calculated. The grinding wheel shaft speed is 34 r / min±1 r / min. The size of the shell material is required to be an outer diameter of about 68 mm and a thickness of 12.7 mm±0.2 mm. The smaller the Akron abrasion, the stronger the wear resistance.

[0045] The results are shown in Table 5.

[0046] Table 5, performance test results ; As can be seen from Table 5, the shell material has good acid and alkali resistance and wear resistance, as the outer structure of the buffer block, it helps to improve the acid and alkali resistance and wear resistance of the buffer block, and can effectively adapt to the complex conveying medium of acid or alkali, and can be applied to the air bag of the mud pump to adapt to different mud pump conveying media, and is durable. The addition of modified calcium carbonate whiskers has a positive effect on improving the acid and alkali resistance and wear resistance of the shell material, and the improvement effect is better than that of modified calcium sulfate whiskers. The calcium carbonate whiskers without modification treatment affect its dispersibility in the shell material, which is not conducive to the acid and alkali resistance and wear resistance.

[0047] 3.3, Optimization of the structure of the buffer block and the preparation method Based on the performance of the core layer material and the shell material, the raw materials for preparing the core layer material A-3 and the raw materials for preparing the shell material B-2 were selected, and a coaxial pouring method (coaxial pouring diagram as shown in Figure 1 The mold was injected at a temperature of 65 ℃ to form an elastomer, and after the mold applied a gradient pressure to the elastomer, it was demolded and cured at 90 ℃ for 12 h.

[0048] The pressure application method was adjusted according to the following grouping: Pressure application method C-1: keep the elastomer in a pressure-free state for 1-5 min, apply a pressure of 50 N to the elastomer for 5-10 min, apply a pressure of 100 N to the elastomer for 10-15 min, and the elastomer returns to a pressure-free state for 15-20 min.

[0049] Pressure application method C-2: keep the elastomer in a pressure-free state for 1-5 min, apply a pressure of 100 N to the elastomer for 5-10 min, apply a pressure of 50 N to the elastomer for 10-15 min, and the elastomer returns to a pressure-free state for 15-20 min.

[0050] Pressure application method C-3: keep the elastomer in a pressure-free state for 1-5 min, apply a pressure of 50 N to the elastomer for 5-15 min, and the elastomer returns to a pressure-free state for 15-20 min.

[0051] Pressure application method C-4: keep the elastomer in a pressure-free state for 1-5 min, apply a pressure of 100 N to the elastomer for 5-15 min, and the elastomer returns to a pressure-free state for 15-20 min.

[0052] Pressure application method C-5: apply a pressure of 100 N to the elastomer for 1-20 min.

[0053] Different cushion block test pieces were prepared according to different pressure application modes, denoted as C-1 to C-5, and a cushion block test piece prepared by keeping the elastomer in a pressure-free state at all times within 1-20 min was prepared as a control test piece, denoted as C-6.

[0054] In addition, to investigate the performance of the cushion block with a core-shell structure, a cushion block without a core-shell structure prepared from the raw material for preparing the shell layer material and a cushion block without a core-shell structure prepared from the raw material for preparing the core layer material were prepared, respectively, denoted as C-7 and C-8.

[0055] The core layer cushion block was prepared from the raw material for preparing the core layer material, and then a shell layer cushion block was prepared from the raw material for preparing the shell layer material using a customized mold to wrap the core layer cushion block, thereby obtaining a cushion block with a core-shell structure. Finally, the pressure was applied according to the pressure application mode C-1, and the obtained cushion block was denoted as C-9.

[0056] The dynamic fatigue tests were performed on the cushion block test pieces C-1 to C-9. The dynamic fatigue resistance of the test piece was characterized by the number of times the test piece was compressed when the test piece started to crack under cyclic compression. The more times the test piece was compressed when the test piece started to crack, the better the durability of the test piece under the action of pressure and heat, and the better the dynamic fatigue resistance. The specific operation method is as follows: The test piece with a size of 50 mm×50 mm×25 mm was installed on the support clamp of the dynamic testing machine, the pressure was set to 0-6 KN, the compression frequency was 2.0 Hz, and the number of times the test piece was compressed when the test piece started to crack was recorded without air cooling. Five parallel tests were performed, and the average value was calculated, i.e., the average compression times of the test piece when it started to crack were obtained.

[0057] The results are shown in Table 6.

[0058] Table 6, performance test results ; As can be seen from Table 6, the raw material for preparing the shell layer material and the raw material for preparing the core layer material were injected into the mold in a coaxial pouring manner to form an elastomer, and then the mold was closed. The elastomer was subjected to gradient pressure according to the pressure application mode C-1, and the obtained cushion block had good dynamic fatigue resistance. Under the premise of a certain pressure application mode, the raw material for preparing the shell layer material was injected into the mold in a coaxial pouring manner with the raw material for preparing the core layer material to mold and form the elastomer, which could optimize the interface morphology of the core layer and the shell layer, so that the cushion block had good dynamic fatigue resistance and could be applied to the air bag structure of the mud pump, thereby helping to effectively and stably maintain the pressure of the mud pump for a long time.

[0059] Application of the cushion block in the mud pump The buffer block provided by the application has the following specific application in the mud pump: first, the buffer blocks are combined into a buffer block assembly, the shapes of the buffer blocks prepared by molding can be in the shape of a cylinder, 1 / 2 cylinder or 1 / 4 cylinder, and the single buffer blocks are combined into the buffer block assembly in the mode as shown in the drawings, and the drawings show that three buffer blocks in the shape of a cylinder are combined into a buffer block assembly, and 12 buffer blocks in the shape of 1 / 4 cylinder are combined into a buffer block assembly, and the damping holes can be further formed in the buffer blocks according to the buffering needs. Figure 2

[0060] Subsequently, the buffer block assembly is installed into the capsule body, and the shape of the capsule body is adapted to the shape of the buffer block assembly; The shell of the air bag is in the cavity type structure, and the upper and lower parts are provided with the connecting ports, the internal cavity is in the ellipsoid type, and the external shape is approximately in the spherical type. The bottom is connected to the mud pump discharge branch through the connecting flange, the capsule body provided with the buffer block assembly is inserted into the shell of the air bag, the upper end is clamped in the upper end plane groove of the shell, the periphery and the bottom of the capsule body are preferably provided with the damping holes for buffering, the top connecting flange of the air bag is connected to the upper part of the shell through the bolts, and the protruding part of the top connecting flange is inserted into the capsule body to fix the capsule body.

[0061] The unbalanced pressure generated when the mud pump works is stored and released by the capsule body and the buffer block in the air bag to balance and stabilize the pressure of the discharged mud, the buffer block with excellent strong plasticity, acid and alkali resistance and wear resistance is applied to the air bag of the mud pump through the design of the structure of the buffer block and the raw materials and process for preparing the buffer block, the effective pressure stabilization effect can be achieved, the complex conveying medium can be adapted, meanwhile, the buffer block provided by the application has excellent dynamic fatigue performance, the application of the buffer block to the air bag structure of the mud pump helps to effectively and stably stabilize the pressure of the mud pump for a long time, and the application is practical and reliable, more durable and has good application prospect.

[0062] The above-described embodiments only express several embodiments of the application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the application. It should be pointed out that, for the ordinary skilled in the art, several improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application.​

Claims

1. A buffer block for an air tank for a pump, characterized by, The buffer block has a core-shell structure, raw materials for preparing the core layer of the buffer block include polyurethane prepolymer and chain extender composition A, and raw materials for preparing the shell layer of the buffer block include polyurethane prepolymer and chain extender composition B; according to parts by weight, The chain extender composition A includes MOCA chain extender 60-80 parts, hexanediol 40-60 parts, epoxy soybean oil 2-5 parts, water 3-5 parts, antioxidant 0.5-1 part, catalyst 0.5-2 parts, and foam stabilizer 0.5-2.5 parts. The chain extender composition B includes MOCA chain extender 100-120 parts, modified calcium carbonate whisker 10-15 parts, hydrolysis-resistant agent 1-1.5 parts, antioxidant 0.5-1 part, catalyst 0.5-2 parts, and foam stabilizer 0.5-2.5 parts.

2. The air tank buffer block for a pump according to claim 1, wherein The polyurethane prepolymer and the chain extender composition A and the chain extender composition B are used in a ratio of 100:10-40.

3. The air tank buffer block for a pump according to claim 1, wherein The NCO content of the polyurethane prepolymer is 6-12%.

4. The air bottle cushion block of claim 1, wherein, The modified calcium carbonate whisker is prepared by the following method: first, a silane coupling agent is added to anhydrous ethanol, heated and stirred until completely dissolved to obtain a silane coupling agent solution, then calcium carbonate whisker is added to the silane coupling agent solution, ultrasonic dispersion, water bath stirring reaction, standing and drying to obtain the modified calcium carbonate whisker.

5. The air bag bumper for a pump according to claim 1, wherein The catalyst is triethylenediamine or bis(2-methoxyethyl)amine, the foam stabilizer is a silicone surfactant, and the hydrolysis-resistant agent is a carbodiimide.

6. A method of producing a cushioning block for an air receiver for a pump as claimed in any one of claims 1 to 5, characterized in that, The method comprises the following steps: (1) Excess diphenylmethane diisocyanate is reacted with polyol at 80-85 ℃ to obtain polyurethane prepolymer, and the raw materials for preparing the chain extender composition A are added to the polyurethane prepolymer to obtain the raw materials for preparing the core layer of the buffer block; (2) Excess diphenylmethane diisocyanate is reacted with polyol at 80-85 ℃ to obtain polyurethane prepolymer, and the raw materials for preparing the chain extender composition B are added to the polyurethane prepolymer to obtain the raw materials for preparing the core layer of the buffer block; (3) The raw materials for preparing the shell layer and the core layer of the buffer block are injected into a mold in a coaxial pouring manner to mold into an elastomer, a gradient pressure is applied to the elastomer by the mold, then the elastomer is demolded and aged.

7. The method of producing a buffer block for an air tank for a pump according to claim 6, characterized by, In step (1), the polyol is selected from polyester polyol with a hydroxyl value of 56-140 mg KOH / g and a number average molecular weight Mn of 2000-4000.

8. The method of claim 6, wherein the air bag cushion for a pump is prepared by the steps of: In step (3), the gradient pressure is applied as follows: the elastomer is kept in a pressure-free state for 1-5 min, a pressure of 50-55 N is applied to the elastomer for 5-10 min, a pressure of 50-100 N is applied to the elastomer for 10-15 min, and the elastomer returns to the pressure-free state for 15-20 min.

9. Use of the buffer block for air bag of a pump according to any one of claims 1-5 in a mud pump.

10. Use according to claim 9, characterised in that, The medium transported by the mud pump is corrosive mud containing acid or alkali.

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