Slow expansion type putty water stop strip and preparation method thereof

Abstract

The invention provides a slow expansion type putty water stop strip and a preparation method thereof, and relates to the field of water stop materials. Comprising the following raw materials: chlorinated polyethylene, natural rubber, a plasticizer, coumarone resin, calcium stearate, water-absorbent resin, bentonite and carbon black. The preparation method comprises the following steps: putting the chlorinated polyethylene, the coumarone resin, the calcium stearate, the carbon black and the water-absorbent resin into a container, and uniformly stirring; adding a plasticizer into the container, uniformly stirring and clustering, taking out, and standing for 6-12 hours to obtain a mixture A; natural rubber is added into the internal mixer, internal mixing is conducted for 8-10 min, and the natural rubber is taken out for use; putting the internally mixed natural rubber and the mixture A into an internal mixer, and internally mixing for 3-5 minutes; and adding bentonite, internally mixing for 3-5 minutes, discharging, standing for 12-24 hours, adding into the internal mixer, internally mixing for 2-5 minutes, discharging, and carrying out extrusion molding on the rubber material subjected to secondary internal mixing. By increasing the strength and viscosity of the special composite rubber, the water-absorbent resin and the bentonite are effectively wrapped and bound, the water absorption speed of the water-stop strip can be effectively reduced, and the expansion time can be prolonged.

Description

Technical Field

[0001] The invention relates to the field of water-stopping materials, and in particular to a slow-swelling putty water-stopping strip and a preparation method thereof. Background Art

[0002] At present, the implementation standard of putty water stop strips is GB / T18173.3-2014. For putty-type water-expanding rubber (i.e. putty water stop strips), it stipulates three different models, namely, in static distilled water, the rubber volume expansion ratio is ≥150%, ≥220%, and ≥300%. Putty-type water stop strips are mostly used in underground construction joints. There must be a process sequence of pouring in the construction joints. When in use, the water stop strips are placed on the interface of the already poured concrete wall. Later, the uncured concrete is poured again, that is, the water stop strips will directly contact the uncured concrete. In such an environment, the water stop strips will inevitably absorb the moisture in the concrete and expand rapidly. However, the moisture content in the concrete is the water required to meet the normal strength hydration reaction of the concrete, which is a fixed ratio; the water stop strips absorb the moisture in the concrete in advance, destroying the original concrete water-cement ratio, thereby causing the local concrete strength to be damaged, which will cause overall safety hazards in the project. On the other hand, after the concrete solidifies, the waterstop will slowly lose water and shrink in size in a dry environment, forming a hole in the construction joint that runs through the entire underground exterior wall structure, causing the waterstop's sealing to fail.

[0003] To solve the above problems, Patent 202310544601.8 discloses a slow-swelling high-expansion ratio water-swelling rubber waterstop strip and its preparation method. It uses easily hydrolyzed polyester polyurethane as a temporary waterproof layer. In the early stage of the water-swelling rubber waterstop strip being immersed in water, water can be isolated from the rubber matrix to prevent the rubber matrix from absorbing water and swelling in the early stage. After the polyester polyurethane waterproof layer is hydrolyzed, the rubber matrix begins to absorb water and the volume expands rapidly, achieving a water-stopping effect. However, if the surface layer of the waterstop strip is partially damaged (such as during the paving construction process and the pouring and vibrating process), the slow-swelling will fail. Patent 201310104215.3 discloses a composite slow-swelling waterstop rubber and its preparation method, which consists of an expansion part and a composite part, wherein the expansion part is composed of raw rubber, carbon black, bentonite, antioxidant, accelerator and expansion agent; the composite part is composed of raw rubber, carbon black, calcium powder, softener and accelerator. The physical and mechanical properties of this water-stop rubber are good. Compared with ordinary water-stop rubber, there is a layer of permeable rubber on the outer layer of the expansion body. The moisture in the concrete is first absorbed by the outer layer of rubber, thus ensuring that the internal expansion body does not expand before the concrete solidifies and will only expand when there is a water leak.

[0004] The above-mentioned prior arts all set the water-stop rubber into a double-layer structure, using the outer layer of water-absorbing material to absorb the moisture in the unsolidified concrete, while the inner water-absorbing material plays a water-absorbing function in the later stage and plays a role in water-stopping. Although the water-stopping effect of the water-stop strip in the later stage is improved, there is still a problem of insufficient concrete strength at the construction joint due to the reduction of moisture in the unsolidified concrete, which affects the overall strength of the wall. At the same time, if the surface layer of the water-stop strip is partially damaged (such as during the paving construction process and the pouring and vibrating process), it will cause the slow expansion failure. The above two slow expansion technologies cannot meet the standards according to the existing material standard JG / T141-2001, and do not meet the current GB50208 "Underground Engineering Waterproof Acceptance Code" on the slow expansion putty water stop strip requirements, so they have no practical use value. Summary of the invention

[0005] The purpose of the present invention is to provide a slow-swelling putty water-stop strip, which has softness, slow-swelling property and cold resistance and can still maintain softness at -20°C.

[0006] Another object of the present invention is to provide a method for preparing a slow-swelling putty waterstop strip. The preparation method is simple. The waterstop rubber prepared by the method has softness, slow swelling and cold resistance, and will not affect the water-cement ratio of concrete during construction.

[0007] The third object of the present invention is to provide a product that meets the requirements of GB50208 "Acceptance Code for Waterproofing of Underground Engineering" regarding slow-swelling putty waterstop strips.

[0008] The present invention solves the technical problem by adopting the following technical solutions.

[0009] On the one hand, an embodiment of the present invention provides a slow-swelling putty water stop strip, comprising the following raw materials: chlorinated polyethylene, natural rubber, plasticizer, coumarone resin, calcium stearate, water-absorbing resin, bentonite and carbon black, wherein the water-absorbing resin is sodium acrylate resin and the plasticizer is polyol benzoate.

[0010] In some embodiments of the present invention, the following raw materials are included, by weight: 3-9 parts of chlorinated polyethylene, 2-6 parts of natural rubber, 6-10 parts of plasticizer, 0.3-0.8 parts of coumarone resin, 0.05-0.2 parts of calcium stearate, 0.5-2 parts of water-absorbing resin, 10-20 parts of bentonite and 0.05-0.2 parts of carbon black.

[0011] In some embodiments of the present invention, the following raw materials are included, by weight: 5-6 parts of chlorinated polyethylene, 4-5 parts of natural rubber, 8-9 parts of plasticizer, 0.4-0.6 parts of coumarone resin, 0.08-0.1 parts of calcium stearate, 1-2 parts of water-absorbing resin, 15-17 parts of bentonite and 0.05-0.1 parts of carbon black.

[0012] In some embodiments of the present invention, the following raw materials are included, by weight: 6 parts of chlorinated polyethylene, 4 parts of natural rubber, 7 parts of plasticizer, 0.5 parts of coumarone resin, 0.1 parts of calcium stearate, 1 part of water-absorbing resin, 14 parts of bentonite and 0.1 parts of carbon black.

[0013] In some embodiments of the present invention, the following raw materials are included, by weight: 9 parts of chlorinated polyethylene, 6 parts of natural rubber, 10 parts of plasticizer, 0.8 parts of coumarone resin, 0.2 parts of calcium stearate, 1.5 parts of water-absorbing resin, 18 parts of bentonite and 0.2 parts of carbon black.

[0014] The embodiment of the present invention provides a method for preparing a slow-swelling putty water stop strip, comprising the following steps:

[0015] S1, placing chlorinated polyethylene, coumarone resin, calcium stearate, carbon black and water-absorbing resin in a container and stirring them evenly; in this step, the chlorinated polyethylene and carbon black, water-absorbing resin, calcium stearate and coumarone resin are mixed evenly, the time and number of mixing steps are reduced, and the aging damage of the rubber composite material caused by too long mixing time and too high temperature and the high-temperature failure of the water-absorbing resin are reduced.

[0016] S2, add the plasticizer into the container, stir evenly and form a mass, take it out and let it stand for 6-12 hours to obtain the mixture A; so that each raw material completes the initial plasticization at room temperature, reduces the high-temperature plasticization time, avoids the high temperature plasticization time being too long, resulting in excessive temperature, causing aging of the rubber composite material and high-temperature failure of the water-absorbing resin; at the same time, ensure the accurate ratio of various powder and granular materials. During the standing process, the raw materials gradually transform into a plastic state, reducing the subsequent mixing time.

[0017] S3, adding the natural rubber into the internal mixer, mixing for 8-10 minutes, and taking it out for use; completing the mixing and initial plasticization of the natural rubber, so that the natural rubber can be more easily combined with the mixed material A evenly during the high-temperature mixing stage.

[0018] S4, put the natural rubber and mixed material A after the banburying in step S3 into a banbury mixer, and banbury for 3-5 minutes; add bentonite, banbury for another 3-5 minutes, discharge, place for 12-24 hours, then add it into the banbury mixer, banbury for 2-5 minutes, and discharge. The natural rubber and chlorinated polyethylene mixed materials are blended and plasticized at a high temperature of 100°C, so that a three-dimensional grid structure is formed between the molecules of the main rubber composite material, which effectively binds and wraps the bentonite water-absorbing resin and other materials, so that the finished product can ensure that the whole expands without breaking or cracking after absorbing water, and the water absorption and expansion are slow.

[0019] S5, the rubber material after the second mixing in step S4 is fed into the extrusion molding equipment, the feeding temperature is guaranteed to be 60℃±5℃, the extruder head is preheated to 70℃-100℃ in advance, and extrusion molding is performed. In the extrusion molding stage, the three-time mixing and plasticization is completed to make the material softer, and the internal structure of the material is made dense and compact through physical extrusion molding, and finally the final preparation is made for the slow expansion of the finished material.

[0020] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0021] The water stop strip provided by the present invention is prepared by step-by-step mixing with chlorinated polyethylene, natural rubber, plasticizer, coumarone resin, calcium stearate, water-absorbing resin, bentonite and carbon black as raw materials. The chlorinated polyethylene and natural rubber are the main materials, and the chlorinated polyethylene has excellent weather resistance, ozone resistance, oil resistance, flame retardancy, chemical resistance, aging resistance and coloring performance. It has good toughness (still flexible at -30°C) and good compatibility with other polymer materials. After mixing, a three-dimensional grid structure is formed between chlorinated polyethylene and natural rubber molecules, forming a flexible skeleton of the product, which plays a role in connecting, wrapping and binding bentonite water-absorbing resin and other materials. When the water stop strip is in a water-containing environment, water molecules need to pass through the three-dimensional grid structure formed by cross-linking of chlorinated polyethylene and natural rubber before they can combine with the water-absorbing resin and absorb water and expand; since the water penetration process is slow, the water stop strip can be slowly expanded or not expanded in the early stage; plasticizers can increase the softness of the water stop rubber, making it plastic and frost-resistant; Coumarone resin plays a role in increasing the cohesive force between material molecules, while increasing the viscosity between the raw materials, it improves the plasticity of the water stop rubber; chlorinated polyethylene is easy to release hydrogen chloride when heated, and the stabilizer calcium stearate can absorb hydrogen chloride, and calcium stearate also plays a role in internal lubrication and preventing adhesion during machining;

[0022] The function of water-absorbing resin is to expand after absorbing water; carbon black is a reinforcing agent, which can improve the tear resistance of chlorinated polyethylene and natural rubber, and can also improve the adhesion between chlorinated polyethylene and natural rubber skeleton. In the processing process, carbon black also plays a heat-conducting role, so that the material is heated evenly during the mixing stage, ensuring that the temperature inside and outside the raw material is consistent.

[0023] Bentonite has the property of swelling upon absorbing water, which helps the absorbent resin absorb water. The calcium ions in the bentonite have the function of slowing down the water absorption rate of the absorbent resin. Bentonite is also a good filling material between the skeleton grids.

[0024] The composition provided by the present invention can effectively wrap and bind the water-absorbing resin and bentonite by increasing the strength and viscosity of the special composite rubber, and can effectively slow down the water absorption speed of the waterstop strip and prolong the expansion time; and can improve the plasticity of the waterstop rubber so that the waterstop rubber has softness and cold resistance and still maintains a soft texture at -20°C.

[0025] The preparation method provided by the present invention improves the softness of the composite rubber and strengthens the interaction between molecules through multiple banburying, so that a three-dimensional grid structure is formed inside the rubber composite material, thereby improving the wrapping force and binding force of materials such as water-absorbing resin and bentonite, and achieving slow expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 Schematic diagram of the molecular structure of natural rubber in an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the molecular structure of chlorinated polyethylene in an embodiment of the present invention;

[0029] Figure 3 This is a physical picture of the water-stop rubber of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0032] The embodiment of the present invention provides a slow-swelling putty waterstop strip, which includes the following raw materials in parts by weight: 3-9 parts of chlorinated polyethylene, 2-6 parts of natural rubber, 6-10 parts of plasticizer, 0.3-0.8 parts of coumarone resin, 0.05-0.2 parts of calcium stearate, 0.5-2 parts of water-absorbing resin, 10-20 parts of bentonite and 0.05-0.2 parts of carbon black.

[0033] More preferably, the following raw materials are included, by weight: 5-6 parts of chlorinated polyethylene, 4-5 parts of natural rubber, 8-9 parts of plasticizer, 0.4-0.6 parts of coumarone resin, 0.08-0.1 parts of calcium stearate, 1-2 parts of water-absorbing resin, 15-17 parts of bentonite and 0.05-0.1 parts of carbon black.

[0034] More preferably, the following raw materials are included, by weight: 6 parts of chlorinated polyethylene, 4 parts of natural rubber, 7 parts of plasticizer, 0.5 parts of coumarone resin, 0.1 parts of calcium stearate, 1 part of water-absorbing resin, 14 parts of bentonite and 0.1 parts of carbon black.

[0035] Preferably, the following raw materials are included by weight: 9 parts of chlorinated polyethylene, 6 parts of natural rubber, 10 parts of plasticizer, 0.8 parts of coumarone resin, 0.2 parts of calcium stearate, 1.5 parts of water-absorbing resin, 18 parts of bentonite and 0.2 parts of carbon black. Chlorinated polyethylene and natural rubber are added in a ratio of 3:2, and the obtained rubber has the best strength and toughness.

[0036] The embodiment of the present invention provides a method for preparing a slow-swelling putty water stop strip, comprising the following steps:

[0037] S1, placing chlorinated polyethylene, coumarone resin, calcium stearate, carbon black and water-absorbing resin in a container, and pre-dry-mixing them evenly;

[0038] S2, add the plasticizer into the container, stir evenly with an electric stirrer in time, and stir evenly when the materials are stirred and peeled off the wall. Under the action of the plasticizer, the powder raw materials are adhered together, that is, plasticized into agglomerates; after plasticized into agglomerates, take out and place in a cool and dry place, and stand for 6-12 hours to obtain mixed material A;

[0039] S3, adding natural rubber into an internal mixer, mixing for 8-10 minutes, and taking out for later use;

[0040] S4, putting the natural rubber and mixed material A after the internal mixing in step S3 into a preheated internal mixer, and mixing for 3-5 minutes; adding bentonite, and mixing for another 3-5 minutes, discharging the material, leaving it for 12-24 hours, and then adding it to the internal mixer again, mixing for 2-5 minutes, and discharging the material.

[0041] S5, feeding the rubber material after the secondary mixing in step S4 into the extrusion molding equipment, ensuring the feeding temperature at 60°C ± 5°C, preheating the extruder head to 70°C-100°C in advance, and extruding and molding.

[0042] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0043] Example 1

[0044] Prepare the raw materials according to the following ratio:

[0045] 6 parts of chlorinated polyethylene, 4 parts of natural rubber, 7 parts of plasticizer, 0.5 parts of coumarone resin, 0.1 parts of calcium stearate, 1 part of water-absorbing resin, 14 parts of bentonite and 0.1 parts of carbon black.

[0046] The water-stop rubber of this embodiment is prepared according to the following steps:

[0047] S1, placing chlorinated polyethylene, coumarone resin, calcium stearate, carbon black and water-absorbing resin in a container, and pre-dry-mixing them evenly;

[0048] S2, add the plasticizer into the container, stir evenly with an electric stirrer in time, and stir evenly until the material is stirred and peeled off the wall. After plasticizing into a mass, take it out and place it in a cool and dry place. After standing for 10 hours, obtain mixed material A;

[0049] S3, adding natural rubber into an internal mixer, mixing for 8 minutes, and taking it out for later use;

[0050] S4, putting the natural rubber and mixed material A after the internal mixing in step S3 into a preheated internal mixer, and mixing for 3 minutes; adding bentonite, mixing for another 3 minutes, discharging, leaving for 12 hours, and then adding to the internal mixer, mixing for 2 minutes, and discharging;

[0051] S5, feeding the rubber material after the secondary mixing in step S4 into the extrusion molding equipment, the feeding temperature is guaranteed to be 60℃±5℃, the extruder head is preheated to 70-100℃ in advance, and extrusion molding is performed to obtain the water-stop rubber of this embodiment.

[0052] Example 2

[0053] Prepare the raw materials according to the following ratio:

[0054] 9 parts of chlorinated polyethylene, 6 parts of natural rubber, 10 parts of plasticizer, 0.8 parts of coumarone resin, 0.2 parts of calcium stearate, 1.5 parts of water-absorbing resin, 18 parts of bentonite and 0.2 parts of carbon black.

[0055] The water-stop rubber of this embodiment is prepared according to the following steps:

[0056] S1, placing chlorinated polyethylene, coumarone resin, calcium stearate, carbon black and water-absorbing resin in a container, and pre-dry-mixing them evenly;

[0057] S2, add the plasticizer into the container, stir evenly with an electric stirrer in time, and stir evenly until the material is stirred and peeled off the wall. After plasticizing into a mass, take it out and place it in a cool and dry place. After standing for 10 hours, obtain mixed material A;

[0058] S3, adding natural rubber into an internal mixer, mixing for 8 minutes, and taking it out for later use;

[0059] S4, putting the natural rubber and mixed material A after the internal mixing in step S3 into a preheated internal mixer, and mixing for 3 minutes; adding bentonite, mixing for another 3 minutes, discharging, leaving for 12 hours, and then adding to the internal mixer, mixing for 2 minutes, and discharging;

[0060] S5, feeding the rubber material after the secondary mixing in step S4 into the extrusion molding equipment, the feeding temperature is guaranteed to be 60℃±5℃, the extruder head is preheated to 70℃-100℃ in advance, and extrusion molding is performed to obtain the water-stop rubber of this embodiment.

[0061] Example 3

[0062] Prepare the raw materials according to the following ratio:

[0063] 3 parts of chlorinated polyethylene, 2 parts of natural rubber, 6 parts of plasticizer, 0.3 parts of coumarone resin, 0.05 parts of calcium stearate, 0.5 parts of water-absorbing resin, 10 parts of bentonite and 0.05 parts of carbon black.

[0064] The water-stop rubber of this embodiment is prepared in the same manner as in Example 1.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that in this example, chlorinated polyethylene is not added, and an equal amount of natural rubber is used to replace chlorinated polyethylene. The remaining raw material proportions and the preparation method of the water-stop rubber are the same as those in Example 1.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that in this example, no natural rubber is added, and an equal amount of chlorinated polyethylene is used to replace the natural rubber. The remaining raw material proportions and the preparation method of the water-stop rubber are the same as those in Example 1.

[0069] Experimental example

[0070] The waterproof rubber prepared in Example 1-3 was used as the object, and a third-party testing agency was commissioned to test the performance of the waterproof rubber according to the relevant standards of GB50208-2011, and the results are shown in Table 1. Among them, the hardness requirement is ≤40 degrees, the 7-day expansion rate requirement is ≤60% of the final expansion rate, and the final expansion rate is ≥220%, the heat resistance requirement is: after 2 hours at 80°C, the waterproof rubber has no flow deformation; the low-temperature flexibility requirement is: after 2 hours at -20°C, the waterproof rubber has no cracks; the water resistance requirement is: after immersion in water for 15 hours, the whole is expanded without fragments.

[0071] Table 1 Performance of water-stop rubber of Examples 1-3 and Comparative Examples 1-2

[0072]

[0073] It should be noted that in Table 1, expansion rate=(volume after expansion / volume before expansion)×100%, and 7-day expansion rate / 21-day expansion rate refers to the ratio of the 7-day expansion rate to the 21-day expansion rate.

[0074] It can be concluded from Table 1 above that the water-stop rubber provided in the embodiment of the present invention has a Shore hardness (type C) of less than 40 degrees and has good softness; the 7-day expansion ratio is less than 60% of the final (21-day) expansion ratio. The national standard stipulates that the initial setting time of cement shall not be earlier than 45 minutes, generally 1 to 3 hours; the final setting time shall not be later than 12 hours, generally 5 to 8 hours. There are no free water molecules after the final setting of concrete. After the final setting of concrete, the hydration products generated by the reaction of cement and water will fill the pores of the concrete, so that the moisture inside the concrete is fixed in the cement hydration products, and no free water molecules exist. The expansion rate of the water-stop rubber in the embodiment is relatively small in the first 7 days. Before 24 hours and 48 hours, the rubber water-stop strip hardly expands, that is, before the final setting of the concrete, the rubber water-stop strip does not expand and will not absorb moisture in the concrete, effectively avoiding the problem that the water-stop strip absorbs water and expands too early to destroy the water-cement ratio of the concrete and form a seepage channel. It should be noted that the expansion ratio in Table 1 was tested in distilled water, while in actual use, the waterstop is in an unsolidified concrete environment. Therefore, in actual use, the waterstop has a better slow expansion effect.

[0075] Secondly, the water-stop rubber provided in the embodiment of the present invention has high temperature resistance that meets the requirements, has certain flexibility at low temperatures, and is not easy to break.

[0076] The raw material of Comparative Example 1 does not contain chlorinated polyethylene, and the raw material of Comparative Example 2 does not contain natural rubber, and the molecular chain of chlorinated polyethylene is a straight structure, such as Figure 2 As shown in the figure, a single chlorinated polyethylene molecule cannot form a three-dimensional grid structure, and the natural rubber molecular chain is also a straight structure, such as Figure 1 As shown, a single natural rubber molecule cannot form a three-dimensional grid structure; therefore, the composite rubber formed by Comparative Examples 1 and 2 does not have a three-dimensional grid structure inside, and the remaining raw materials such as bentonite, water-absorbing resin, etc. cannot be effectively wrapped and restrained, and will expand rapidly after absorbing water, and the rubber will be stretched and broken.

[0077] To sum up, the water-stop rubber provided in the embodiment of the present invention increases the strength and viscosity of the special composite rubber, forms a three-dimensional grid structure between the chlorinated polyethylene and the natural rubber molecules, and realizes the wrapping and restraint of the water-absorbing resin, which can effectively slow down the water absorption rate of the water-stop strip and prolong the expansion time; by improving the plasticity of the water-stop rubber, the water-stop rubber has softness and cold resistance, and still maintains a soft texture at -20°C.

[0078] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A slow-swelling putty water stop strip, characterized in that: The raw materials include chlorinated polyethylene, natural rubber, plasticizer, coumarone resin, calcium stearate, water-absorbing resin, bentonite and carbon black.

2. The slow-swelling putty waterstop strip according to claim 1, characterized in that: The raw materials include, by weight: 3-9 parts of chlorinated polyethylene, 2-6 parts of natural rubber, 6-10 parts of plasticizer, 0.3-0.8 parts of coumarone resin, 0.05-0.2 parts of calcium stearate, 0.5-2 parts of water-absorbing resin, 10-20 parts of bentonite and 0.05-0.2 parts of carbon black.

3. The slow-swelling putty waterstop strip according to claim 1, characterized in that: The raw materials include the following by weight: 5-6 parts of chlorinated polyethylene, 4-5 parts of natural rubber, 8-9 parts of plasticizer, 0.4-0.6 parts of coumarone resin, 0.08-0.1 parts of calcium stearate, 1-2 parts of water-absorbing resin, 15-17 parts of bentonite and 0.05-0.1 parts of carbon black.

4. The slow-swelling putty waterstop strip according to claim 2 or 3, characterized in that: The raw materials are as follows, calculated by weight: 6 parts of chlorinated polyethylene, 4 parts of natural rubber, 7 parts of plasticizer, 0.5 parts of coumarone resin, 0.1 parts of calcium stearate, 1 part of water-absorbing resin, 14 parts of bentonite and 0.1 parts of carbon black.

5. The slow-swelling putty waterstop strip according to claim 2 or 3, characterized in that: The raw materials are as follows, calculated by weight: 9 parts of chlorinated polyethylene, 6 parts of natural rubber, 10 parts of plasticizer, 0.8 parts of coumarone resin, 0.2 parts of calcium stearate, 1.5 parts of water-absorbing resin, 18 parts of bentonite and 0.2 parts of carbon black.

6. A method for preparing the slow-swelling putty waterstop strip according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, placing chlorinated polyethylene, coumarone resin, calcium stearate, carbon black and water-absorbing resin in a container and stirring them evenly; S2, adding the plasticizer into the container, stirring evenly and forming a mass, taking it out and letting it stand for 6-12 hours to obtain a mixture A; S3, adding natural rubber into an internal mixer, mixing for 8-10 minutes, and taking out for later use; S4, putting the natural rubber and mixed material A after the internal mixing in step S3 into an internal mixer and mixing for 3-5 minutes; Add bentonite, knead for 3-5 minutes, discharge, place for 12-24 hours, add to the internal mixer, knead for 2-5 minutes, and discharge; S5, feeding the material after the secondary mixing in step S4 into an extrusion molding device, with the feeding temperature being 60°C±5°C and the extruder head being 70-100°C, and extrusion molding.

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