Polyurethane foam, battery pack and method for filling gaps of battery pack

Abstract

The invention discloses polyurethane foam, a battery pack and a method for filling gaps of the battery pack, and belongs to the technical field of polyurethane. The polyurethane foam comprises a surface and a core part in the surface, at least part of the surface is provided with a surface layer, the cell area of the outer surface of the surface layer accounts for 30%-50%, and the aperture ratio of the core part is 80%-95%. The polyurethane foam disclosed by the invention not only has good vacuumized performance and filling performance, but also has good waterproof sealing performance, can be placed in a gap of a battery pack after being vacuumized, is tightly filled in the gap after vacuum is broken, and plays a role in waterproof sealing at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethanes, and particularly to polyurethane foam, a battery pack, and a method for filling the gaps in the battery pack. Background Art

[0002] With the rapid development of new energy vehicles, the corresponding on-vehicle power batteries are also developing rapidly. On-vehicle power batteries are usually supplied to automobile manufacturers in the form of battery packs (Packs). A battery pack usually consists of multiple components, such as battery cell modules, boxes, etc. When designing a battery pack, considering the efficiency of installation and disassembly of each component, a gap of 1-12 mm is usually reserved.

[0003] A battery pack with excellent performance needs to meet at least the following three conditions: ① The above-mentioned gap needs to be filled so that the components in the battery pack are tightly fitted to prevent problems such as component looseness, shaking, and displacement. ② The filling material used to fill the above-mentioned gap needs to have good waterproof and sealing performance, such as blocking glue, plugging glue, and preventing glue leakage, etc.; ③ The filling of the above-mentioned gap needs to be quick and easy to operate during assembly and disassembly operations.

[0004] In the prior art, the filling materials used to fill the above-mentioned gap mainly include glue-like materials such as potting glue, sealant, and caulking glue. These glue-like materials often have too high viscosity, and are likely to entrap air during use, resulting in bubbles in the cured glue, which affects the strength and sealing performance of the cured glue. In addition, due to the inconsistent sizes of the above-mentioned gaps, it is also difficult to determine whether the glue-like materials completely fill the above-mentioned gaps during use.

[0005] On the other hand, polyurethane, as a new type of organic polymer material, is known as the "fifth plastic" and is widely used in the fields of 3C electronic products, new energy vehicles, building decoration, etc. due to its good shock absorption and buffering performance, sealing performance, and heat insulation performance.

[0006] In view of the above problems in the existing battery packs, the inventor of the present invention considered using polyurethane foam to fill the gaps in the battery pack. However, the inventor found that due to the unique rebound performance of the existing polyurethane foam, it would be difficult to stuff the polyurethane foam into the narrow gaps in the battery pack for filling, which would bring problems such as complicated process operations, increased operation difficulty, and reduced assembly efficiency. At the same time, the conformability between the existing polyurethane foam and the components also needs to be further improved. Moreover, the waterproof and sealing performance of the existing polyurethane foam also needs to be further improved to avoid situations such as glue leakage. That is, the existing polyurethane foam still cannot solve the above problems in the existing battery packs. Summary of the Invention

[0007] To solve the above technical problems, an object of the present invention is to provide a polyurethane foam, a battery pack, and a method for filling the gaps in the battery pack.

[0008] To achieve the above object, in a first aspect of the present invention, there is provided a polyurethane foam, the polyurethane foam comprising a surface and a core part inside the surface, at least part of the surface having an epidermal layer, the proportion of the cell area on the outer surface of the epidermal layer being 30% - 50%, and the open cell rate of the core part being 80% - 95%.

[0009] According to a specific embodiment of the present invention, preferably, the contact angle of the surface of the polyurethane foam having the epidermal layer with water > 105°.

[0010] According to a specific embodiment of the present invention, preferably, the water absorption rate of the polyurethane foam < 10%.

[0011] According to a specific embodiment of the present invention, preferably, the density of the polyurethane foam is 80 - 200 kg / m 3 .

[0012] According to a specific embodiment of the present invention, preferably, the thickness of the polyurethane foam is 2 - 20 mm.

[0013] According to a specific embodiment of the present invention, preferably, the average cell diameter of the core part of the polyurethane foam is 100 - 300 μm.

[0014] According to a specific embodiment of the present invention, preferably, the 15% compressive strength of the polyurethane foam is 10 - 50 kPa, and the 70% compressive strength of the polyurethane foam is 60 - 150 kPa.

[0015] According to a specific embodiment of the present invention, preferably, the permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression ≤ 10%.

[0016] According to a specific embodiment of the present invention, preferably, after the polyurethane foam is placed in a packaging bag and evacuated, the thickness retention rate of the polyurethane foam ≤ 35%.

[0017] According to a specific embodiment of the present invention, preferably, after the polyurethane foam is placed in a packaging bag and evacuated and then the vacuum is broken, the time required for the thickness recovery rate of the polyurethane foam to be 60% is 5 - 20 min, and the time required for the thickness recovery rate of the polyurethane foam to be 95% is 1 h - 12 h.

[0018] According to a specific embodiment of the present invention, preferably, at least one surface of the polyurethane foam has a coating.

[0019] In a second aspect of the present invention, a battery pack is provided, which at least includes: a box body, a battery cell module, and a filling component; the box body at least includes a bottom plate and an end plate, the bottom plate and the end plate enclose a chamber, and a plurality of beam bodies are arranged in the chamber; the battery cell module is arranged in the chamber of the box body;

[0020] There is a gap between the battery cell module and the beam body, and / or there is a gap between the battery cell module and the end plate; the filling component is filled in the gap;

[0021] The filling component includes a packaging bag and a filling material arranged in the packaging bag;

[0022] The filling material is the above-mentioned polyurethane foam.

[0023] In a third aspect of the present invention, a method for filling the gap of a battery pack is provided, which includes the following steps: placing the above-mentioned polyurethane foam in a packaging bag to obtain a filling component; evacuating the filling component; then placing the evacuated filling component in the gap of the battery pack; and then breaking the vacuum of the filling component so that the filling component fills the gap.

[0024] Advantages of the Invention

[0025] The present invention has at least the following beneficial effects:

[0026] On the one hand, the polyurethane foam of the present invention has good compression performance and rebound performance, can be easily placed in the gap of the battery pack after being evacuated, and can fit tightly and compactly fill the gap of the battery pack after breaking the vacuum, and will not cause excessive extrusion to the components in the battery pack, having good evacuable performance and filling performance; on the other hand, the polyurethane foam of the present invention has good waterproof and sealing performance, and can play roles such as glue blocking, glue plugging, waterproofing, and preventing glue leakage in the battery pack. Description of the Drawings

[0027] Figure 1 It is a scanning electron microscope photograph of the surface of the polyurethane foam in Example 1.

[0028] Figure 2 It is a scanning electron microscope photograph of the surface of the polyurethane foam in Example 7 before evacuation.

[0029] Figure 3 It is a scanning electron microscope photograph of the surface of the polyurethane foam in Example 7 after evacuation. Detailed Embodiments

[0030] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the following detailed description of the present invention is provided, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0031] It should be noted that unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0032] Various raw materials, reagents, instruments, and equipment used in the present invention, unless otherwise specifically stated, can be obtained through market purchases or can be prepared by existing methods.

[0033] It should be understood that the terms "comprising," "including," and / or "containing" when used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0034] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0035] <Polyurethane foam>

[0036] According to a specific embodiment of the present invention, the present invention provides a polyurethane foam, the polyurethane foam including a surface and a core part inside the surface. At least part of the surface has an epidermal layer, and the proportion of the cell area on the outer surface of the epidermal layer is 30% - 50%, and the open cell rate of the core part is 80% - 95%.

[0037] It should be noted that in the present invention, the epidermal layer is a surface layer part located on the surface of the foam and significantly denser than the core part. The surface having the epidermal layer includes the surface perpendicular or nearly perpendicular to the thickness direction of the polyurethane foam.

[0038] Among them, the proportion of the cell area on the outer surface of the skin layer is obtained by the following method: Scanning the outer surface of the skin layer of the polyurethane foam with a scanning electron microscope (SEM), identifying the cell area by the gray-scale difference between the cell area and the non-cell area, and calculating the percentage of the cell area in the entire field of view area through image analysis software, which is the proportion of the cell area on the outer surface of the skin layer. The size of the field of view is determined based on the magnification of the SEM. For each specimen, the number of cells measured each time can be, for example, 50 - 200, preferably 50 - 100. Randomly and independently take more than 5 specimens from the outer surface of the skin layer of the polyurethane foam, repeat the above operation, and take the average value to obtain the proportion of the cell area on the outer surface of the skin layer of the polyurethane foam.

[0039] The open-cell rate of the core part is obtained by the method described in GB / T10799 - 2008 (Determination of the percentage of open and closed cells in rigid cellular plastics). Specifically, the open-cell rate of the core part is calculated using the calculation formula of the volume open-cell rate O v in GB / T10799 - 2008. The specimen used for testing the open-cell rate of the core part is prepared in the following way: Take the polyurethane foam, cut it into a size of 25 mm in length × 25 mm in width, remove the part with a thickness of 1 / 3 from the upper and lower surfaces, and use the remaining middle part (i.e., the middle part with a thickness of 1 / 3) as the specimen. If the thickness of the remaining middle part is less than 50 mm, stack multiple middle parts to make the total thickness reach more than 50 mm. In the following specific examples, the instrument used for testing the open-cell rate of the core part is the BSD-TD full-automatic true density and open-cell rate instrument.

[0040] The inventors of the present invention have found through research that if the proportion of the cell area on the outer surface of the skin layer > 50%, although the polyurethane foam is easily evacuated, its waterproof and sealing performance is poor; if the proportion of the cell area on the outer surface of the skin layer < 30%, although the polyurethane foam has better waterproof and sealing performance, it is not easily evacuated; if the open-cell rate of the core part > 95%, the waterproof and sealing performance of the polyurethane foam is poor; if the open-cell rate of the core part < 80%, the rebound performance of the polyurethane foam is poor and it is not conducive to evacuation. The present invention controls the proportion of the cell area on the outer surface of the skin layer to be 30% - 50%, and at the same time controls the open-cell rate of the core part to be 80% - 95%, thereby enabling the polyurethane foam to have both good evacuability and filling performance, and good waterproof and sealing performance, achieving a better balance between the compression and rebound performance and the waterproof and sealing performance.

[0041] In some embodiments, the contact angle between the surface of the polyurethane foam with an epidermal layer and water is > 105°, such as 110°, 120°, 130°, 140°, 150° or 160°, etc. Based on controlling that the epidermal layer of the polyurethane foam has an outer surface cell area ratio of 30% - 50%, the present invention further controls the contact angle between the surface with the epidermal layer and water to be > 105°, so that the surface of the polyurethane foam has a hydrophobic interface, thereby making the polyurethane foam have better waterproof and sealing performance. Among them, the contact angle between the surface of the polyurethane foam with the epidermal layer and water is measured according to the method described in ASTM D5725 - 99(2003) (Standard Test Method for Wettability and Absorbency of Sheet Materials Using an Automated Contact Angle Tester). In the specific examples below, the instrument used for this test is the CA200S full - automatic optical contact angle measuring instrument.

[0042] In some embodiments, the water absorption rate of the polyurethane foam is < 10%, such as 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1%, etc. The present invention controls that the epidermal layer of the polyurethane foam has an outer surface cell area ratio of 30% - 50%, which can reduce or even prevent water and other small - molecule substances from passing through the foam, and further controls the water absorption rate of the polyurethane foam to be < 10%, so that the polyurethane foam has better waterproof and sealing performance. Among them, the water absorption rate of the polyurethane foam is measured according to the hygroscopicity test method B described in GBT5480 - 2017 (Test Methods for Mineral Wool and Its Products). The calculation formula for the water absorption rate is: Water absorption rate (%) = (Weight of the polyurethane foam after water absorption - Weight of the polyurethane foam before water absorption) × 100% / Weight of the polyurethane foam before water absorption.

[0043] In some embodiments, the density of the polyurethane foam is 80 - 200 kg / m 3 ³, such as 80 kg / m 3 ³, 100 kg / m 3 ³, 120 kg / m 3 ³, 140 kg / m 3 ³, 160 kg / m 3 ³, 180 kg / m 3 ³ or 200 kg / m 3 ³, etc., and preferably 100 - 180 kg / m 3 ³. Among them, the density of the polyurethane foam is measured according to the method described in GB / T 6343 - 2009 (Cellular Plastics and Rubbers - Determination of Apparent Density). The apparent total density calculated by formula (1) in 7.1 of this standard is the density of the polyurethane foam.

[0044] In some embodiments, the thickness of the polyurethane foam is 2 - 20 mm, such as 2 mm, 5 mm, 10 mm, 15 mm, or 20 mm, etc., and preferably 2 - 15 mm. In the following specific examples, the thickness of the polyurethane foam can be measured using a commercially available thickness gauge.

[0045] By controlling the density and thickness of the polyurethane foam within the above ranges, the present invention can further endow the polyurethane foam with better compression performance, and thus better vacuum-pumpable performance.

[0046] In some embodiments, the polyurethane foam is a sheet-shaped foam material (also referred to as a polyurethane foam sheet), and its planar shape is, for example but not limited to, rectangular, circular, etc. The present invention does not impose special restrictions on its planar shape and size, and can be conventionally selected by those skilled in the art according to the actual situation.

[0047] In some embodiments, the average pore diameter of the core of the polyurethane foam is 100 - 300 μm. If the average pore diameter of the core of the polyurethane foam is greater than 300 μm, the compression strength of the foam is too low, thus affecting the rebound performance and service life of the foam; if the average pore diameter of the core of the polyurethane foam is less than 100 μm, it is easy to cause the foam to shrink, resulting in poor compression performance of the foam, and thus poor vacuum-pumpable performance of the foam. On the basis of controlling the pore area ratio of the outer surface of the skin layer and the open-cell rate of the core within the above ranges, the present invention further controls the average pore diameter of the core of the polyurethane foam within the above range, enabling the polyurethane foam to have better compression and rebound performance, and thus better vacuum-pumpable performance and filling performance. Among them, the test method for the average pore diameter of the core of the polyurethane foam includes: cutting the core of the polyurethane foam along a direction perpendicular to the thickness direction of the polyurethane foam to obtain a cross-sectional sample of the core; after soaking the sample in liquid nitrogen for 1 minute, taking a magnified photograph of the cross-sectional sample of the core through a scanning electron microscope (SEM), and measuring the diameters of all the pores present on the cross-section with a length and width less than 30 mm. The size of the field of view is determined based on the magnification of the SEM. For each sample, the number of pores measured each time can be, for example, 50 - 200, preferably 50 - 100. Randomly and independently take more than 5 samples from the core of the polyurethane foam, repeat the above operations, and take the average value to obtain the average pore diameter of the core of the polyurethane foam.

[0048] In some embodiments, the 15% compression strength of the polyurethane foam is 10 - 50 kPa, such as 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa or 50 kPa, etc., preferably 15 - 35 KPa; and the 70% compression strength of the polyurethane foam is 60 - 150 kPa, such as 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 110 kPa, 120 kPa, 130 kPa, 140 kPa or 150 kPa, etc., preferably 70 - 120 kPa.

[0049] The 15% compression strength of the polyurethane foam can represent the pre-tightening force of the foam (i.e., the initial compression rebound force before being in the working state), and it is also the expansion force on the module at the initial stage of the use of the battery cell module (i.e., the initial stage of the life); the 70% compression strength can represent the compression rebound force of the foam in the long-term working state for filling the gap in the battery pack, and it is also the expansion force on the module at the end stage of the use of the battery cell module (i.e., the end stage of the life).

[0050] If the 15% and 70% compression strengths of the polyurethane foam are lower than the above ranges, the compression rebound force of the polyurethane foam is too low, and problems such as looseness, shaking or displacement of the components in the battery pack are likely to occur; if the 15% and 70% compression strengths of the polyurethane foam are higher than the above ranges, the compression rebound force of the polyurethane foam is too high, and the components in the battery pack are likely to be deformed due to extrusion, and at the same time, the polyurethane foam has poor vacuum-pumping performance. And in the present invention, by further controlling the 15% and 70% compression strengths of the polyurethane foam within the above ranges, the polyurethane foam further has good vacuum-pumping performance and filling performance.

[0051] Among them, both the 15% compression strength and the 70% compression strength of the polyurethane foam are tested according to the method described in Test-C of ASTM D 3574-17. Specifically, it may include the following steps:

[0052] The first step is to use a polyurethane foam sheet with a planar size of 50 mm × 50 mm. ① For sheets with a thickness of 10 mm - 20 mm, a single sheet is used as the specimen. ② For sheets with a thickness less than 10 mm, the sheets need to be stacked until the thickness is greater than or equal to 10 mm, and then used as the specimen. For example: 2-mm sheets are stacked 5 layers, 3-mm sheets are stacked 4 layers, 4-mm sheets are stacked 3 layers, 5-mm sheets are stacked 2 layers, 8-mm sheets are stacked 2 layers, etc.;

[0053] The second step is to place the specimen at 23 ± 2 °C and (50 ± 5)% RH for at least 16 h;

[0054] Step 3: Then, conduct a compression test on the specimen. Set the maximum pressure to 2000 N, the compression speed to 2 mm / min, and pause for 60 s every 5% compression (e.g., pause for 60 s at 5%, 10%, 15%... 70% compression, etc.).

[0055] Thus, the compression strengths of the polyurethane foam at 15% compression (i.e., compressed to 85% of the initial thickness of the specimen) and 70% compression (i.e., compressed to 30% of the initial thickness of the specimen) are obtained respectively.

[0056] In the specific embodiments below, the instrument used for this test is a universal material testing machine.

[0057] In some embodiments, the permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression is ≤ 10%, such as 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1%, etc., preferably ≤ 5%.

[0058] Generally, after repeated compression, the thickness of the polyurethane foam will be lost. The present invention further controls the permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression within the above range, so that the thickness loss of the foam after repeated compression is low, and thus the foam has good anti-fatigue performance and a long service life.

[0059] Among them, the permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression is tested according to the method described in Test-I5 of ASTM D3574-17. Specifically, it may include the following steps:

[0060] Step 1: The same as the first step of the 15% compression strength and 70% compression strength tests of the above-mentioned polyurethane foam;

[0061] Step 2: The same as the second step of the 15% compression strength and 70% compression strength tests of the above-mentioned polyurethane foam;

[0062] Step 3: Then, conduct a compression test on the specimen, increase the compression amount of the specimen from 0% to 50% and then remove the compression, which is recorded as 1 compression. The compression speed is 12 mm / min, and perform 10,000 times of the compression;

[0063] Step 4: Then, calculate the permanent deformation rate of the specimen. The calculation formula for the permanent deformation rate is: Permanent deformation rate (%) = (thickness of the polyurethane foam before compression - thickness of the polyurethane foam after 10,000 times of 50% compression) × 100% / thickness of the polyurethane foam before compression.

[0064] In the specific embodiments below, the instrument used for this test is a universal material testing machine.

[0065] In some embodiments, after the polyurethane foam is placed in a packaging bag and evacuated, the thickness retention rate of the polyurethane foam is ≤ 35%. The present invention further controls the thickness retention rate of the polyurethane foam after evacuation to be below 35%, so that the polyurethane foam has better vacuum-evacuability. If the thickness retention rate of the polyurethane foam after evacuation > 35%, it is difficult to evacuate the polyurethane foam, and its vacuum-evacuability is poor. Among them, the evacuation time is ≤ 20 s (e.g., 20 s), and the vacuum degree in the packaging bag after evacuation is -0.1 MPa. The present invention does not impose special restrictions on the evacuation instrument, and commercially available instruments can be used. The calculation formula for the thickness retention rate is: thickness retention rate (%) = (total thickness of the polyurethane foam and the packaging bag after evacuation - total thickness of the packaging bag) × 100% / thickness of the polyurethane foam before evacuation. It should be noted that the packaging bag includes upper and lower surfaces in the thickness direction, so the total thickness of the packaging bag is twice the single-layer thickness of the packaging bag. The single-layer thickness of the packaging bag is, for example, 0.05 mm.

[0066] In some embodiments, after the polyurethane foam is placed in a packaging bag and evacuated, and then the vacuum is broken, the time required for the thickness recovery rate of the polyurethane foam to reach 60% is 5 - 20 min, and the time required for the thickness recovery rate of the polyurethane foam to reach 95% is 1 h - 12 h. The present invention further controls the time required for the thickness recovery rate of the polyurethane foam to reach 60% and 95% after breaking the vacuum to be in the ranges of 5 - 20 min and 1 h - 12 h respectively, so that the thickness recovery speed of the foam is appropriate, it has better rebound force release performance, and thus has better compression and rebound performance, can fill the gaps in the battery pack quickly and sufficiently, has better filling performance, and can effectively prevent problems such as looseness, shaking or displacement between the components in the battery pack, and at the same time avoid over-compressing the battery core. If the time required for the foam to reach the above thickness recovery rate is lower than the above time range, the rebound force of the foam is released too fast, and it is easy to squeeze the battery core and deform it; if the time required for the foam to reach the above thickness recovery rate is higher than the above time range, the rebound force of the foam is released too slowly, and it is not easy to fit tightly and compactly fill the gaps in the battery pack. Among them, the evacuation time is ≤ 20 s (e.g., 20 s), and the vacuum degree in the packaging bag after evacuation is -0.1 MPa. The single-layer thickness of the packaging bag is, for example, 0.05 mm. The present invention does not impose special restrictions on the evacuation instrument, and commercially available instruments can be used. The calculation formula for the thickness recovery rate is: thickness recovery rate (%) = thickness of the polyurethane foam after being placed for the above time after breaking the vacuum × 100% / thickness of the polyurethane foam before evacuation.

[0067] In some embodiments, at least one surface of the polyurethane foam has a coating. Preferably, the material of the coating includes polyurethane. The surface having the coating includes a surface perpendicular or nearly perpendicular to the thickness direction of the polyurethane foam. Those skilled in the art can understand that the coating is located outside the skin layer. By further providing a coating on at least one surface of the polyurethane foam, the present invention can endow the foam with better waterproof and sealing properties, making it suitable for application scenarios with higher waterproof requirements. When there is a coating on the surface of the polyurethane foam, the pore area ratio of the outer surface of the skin layer is still measured by the method described above. Specifically, the surface of the polyurethane foam having the coating is scanned by a scanning electron microscope (SEM), and the pore regions and non-pore regions covered by the coating are identified using gray-scale differences, thereby calculating the pore area ratio of the outer surface of the skin layer.

[0068] <Preparation Method of Polyurethane Foam>

[0069] According to the specific embodiments of the present invention, the preparation method of the polyurethane foam of the present invention includes the following steps: Coating the raw material mixture of the polyurethane foam on the surface of a film material, and after reaction, obtaining the polyurethane foam.

[0070] In some embodiments, the raw material mixture of the polyurethane foam includes a polyol-containing composition and an isocyanate.

[0071] In some embodiments, the polyol-containing composition includes at least polyol, a blowing agent, and a catalyst.

[0072] (Polyol)

[0073] In some embodiments, the polyol includes a combination of a first polyol, a second polyol, and a third polyol. The first polyol includes a polyol with a hydroxyl value of 220 - 470 mgKOH / g and an average functionality of ≥3. The second polyol includes a polyol with a hydroxyl value of 24 - 56 mgKOH / g and an average functionality of 3 - 6. The third polyol includes a polyol with a hydroxyl value of 17 - 37 mgKOH / g and an average functionality of ≥3.

[0074] In some embodiments, the mass ratio of the first polyol, the second polyol, and the third polyol is (0.5 - 2):1:1.

[0075] By using three polyols with the above-mentioned hydroxyl value and average functionality ranges and preferably controlling the ratio of the three polyols within the above range, the present invention is conducive to making the pore area ratio of the outer surface of the skin layer and the open cell rate of the core of the polyurethane foam within the range of the present invention, and further conducive to making the average pore diameter of the core of the foam within the range controlled by the present invention.

[0076] In some embodiments, the first polyol may include a polyether polyol.

[0077] In some embodiments, the second polyol may include a polyether polyol.

[0078] In some embodiments, the primary hydroxyl group content of the second polyol is ≥70% by mass. The primary hydroxyl group content of the polyol is usually provided by the manufacturer. If the manufacturer does not provide the primary hydroxyl group content of the polyol, the amount of reagent consumed in the reaction can be determined by methods such as potentiometric titration or acid-base titration in the prior art, and then the primary hydroxyl group content can be calculated. The present invention preferably controls the primary hydroxyl group content of the second polyol within the above range, which can provide a suitable open cell ratio, is beneficial to keeping the open cell ratio of the core of the polyurethane foam within the range controlled by the present invention; at the same time, it is beneficial to enabling the polyurethane foam to achieve rapid curing under the reaction conditions described below in the present invention.

[0079] In some embodiments, the hydroxyl value of the second polyol is preferably 28 - 34 mgKOH / g.

[0080] In some embodiments, the relative molecular mass of the second polyol is 5000 - 12000, preferably 6000 - 10000. The present invention preferably controls the relative molecular mass of the second polyol within the above range, which is beneficial to keeping the permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression within the range controlled by the present invention, and at the same time is beneficial to enabling the foam to have good thermal stability; and is beneficial to enabling the raw material mixture of the polyurethane foam to have a suitable viscosity, and thus have better preparation operability.

[0081] In some embodiments, the third polyol may include a polymer polyol, specifically, it may include a polymer polyol formed by graft copolymerization modification of a polyol using acrylonitrile and / or styrene. Among them, the polyol for graft copolymerization modification may include a polyether polyol or a polyester polyol. Since the polyester polyol has a relatively high viscosity and poor practical operability, a polymer polyol formed by graft copolymerization of a polyether polyol with acrylonitrile and styrene is preferably used. The average functionality of the polymer polyol is preferably 3.

[0082] In some embodiments, the solid content of the third polyol is 15% by mass - 50% by mass, preferably 25% by mass - 45% by mass. The present invention preferably controls the solid content of the third polyol within the above range, which is beneficial to enabling the raw material mixture of the polyurethane foam to have a suitable viscosity, and thus have better preparation operability; at the same time, it is beneficial to enabling the polyurethane foam to have a compression strength, an outer surface cell area ratio, and a core open cell ratio within the ranges controlled by the present invention.

[0083] Specifically, the third polyol includes, for example, at least one of the following products: SP30-15, SP37-25, CHP-H30, CHP-H45, CHP-H50.

[0084] (Blowing agent)

[0085] In some embodiments, the blowing agent includes one or more of deionized water, nitrogen, liquid carbon dioxide, etc., and preferably deionized water.

[0086] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the blowing agent is 0.5% - 1.5%. Here, the mass fraction of the blowing agent preferably refers to the mass fraction of deionized water. The present invention preferably controls the content of the blowing agent within the above range, which is beneficial to keeping the density of the polyurethane foam and the average cell diameter of the core within the controlled range of the present invention.

[0087] (Catalyst)

[0088] In some embodiments, the catalyst includes one or more of a metal catalyst and a blowing catalyst. Among them, the metal catalyst includes one or more of organotin-based, potassium carboxylate-based, bismuth carboxylate-based, zinc carboxylate-based (such as zinc isooctanoate, zinc neodecanoate) and organozirconium-based organometallic catalysts. The blowing catalyst includes amine catalysts, such as A33 (i.e., a solution prepared from 33% triethylenediamine and 67% dipropylene glycol), A1 bis(dimethylaminoethyl) ether (i.e., a solution prepared from 70% bis(dimethylaminoethyl) ether and 30% dipropylene glycol), dimethylethanolamine, pentamethyldiethylenetriamine, etc.

[0089] The chemical reactions of polyurethane mainly include two types of reactions: one is the gel reaction, and the other is the blowing reaction. The metal catalyst is mainly used for the gel reaction of polyurethane; the blowing catalyst is mainly used for the blowing reaction of polyurethane. Considering the need to achieve a good balance between the gel reaction and the blowing reaction, a combination of a metal catalyst and a blowing catalyst is preferably used. In some embodiments, the mass ratio of the metal catalyst to the blowing catalyst is (1 - 2):1. If no metal catalyst and blowing catalyst are added, that is, the addition amounts of the metal catalyst and the blowing catalyst are 0, the gel and blowing reactions of polyurethane are very weak, the foam is difficult to cure, and the surface of the foam is prone to stickiness; if the mass ratio of the metal catalyst to the blowing catalyst > 2:1, the gel reaction is faster than the blowing reaction, which easily causes shrinkage on the surface of the foam, thus easily leading to depressions on the surface of the foam and easily making the compressive strength of the foam too high; if the mass ratio of the metal catalyst to the blowing catalyst < 1:1, the blowing reaction is faster than the gel reaction, which easily makes the surface feel of the foam rough and easily makes the compressive strength of the foam too low.

[0090] In some embodiments, based on 100% of the total mass of the polyol, the mass fraction of the catalyst is 0.01% - 0.1%.

[0091] (Foam stabilizer)

[0092] In some embodiments, the polyol-containing composition further comprises a foam stabilizer.

[0093] In some embodiments, the foam stabilizer comprises a modified copolymer of dimethyl silicone and polyether, also known as polyether-modified silicone oil. The present invention preferably uses polyether-modified silicone oil as the foam stabilizer.

[0094] Specifically, the foam stabilizer includes, for example, one or more of DC6070, DC2525, and MONMENTIVE L580, etc.

[0095] In some embodiments, based on 100% of the total mass of the polyol, the mass fraction of the foam stabilizer is 0% - 0.7%. If the content of the foam stabilizer is higher than the above range, it is likely to cause excessive shrinkage of the foam. The present invention preferably controls the content of the foam stabilizer within the above range, which is more conducive to keeping the core porosity and average cell diameter of the foam within the controlled range of the present invention.

[0096] (Hydrophobic modifier)

[0097] In some embodiments, the polyol-containing composition further comprises a hydrophobic modifier.

[0098] In some embodiments, the hydrophobic modifier includes one or more of acrylic compounds, silicone compounds, and fluorinated organic compounds, etc., preferably fluorinated organic compounds. Fluorinated organic compounds have high chemical stability, high heat resistance stability, and properties such as water and oil resistance. Moreover, compared with acrylic compounds and silicone compounds, fluorinated organic compounds have lower surface tension and more excellent hydrophobic properties. Therefore, the present invention preferably uses fluorinated organic compounds as the hydrophobic modifier.

[0099] Specifically, the fluorinated organic compounds include, for example, one or more of XSY-W601 water repellent, XSY-W802 water repellent, XSY-W801 water repellent, and perfluorohexyl ethanol, etc.

[0100] According to a specific embodiment of the present invention, a hydrophobic modifier is introduced into the polyol-containing composition. The hydrophobic modifier has the property of reducing the surface tension. During the chemical reaction of the polyurethane foam, the hydrophobic modifier is uniformly dispersed in the polyol-containing composition. When the polyol-containing composition reacts with the isocyanate, the surface and the core of the generated polyurethane foam have uniform hydrophobicity, which is beneficial to keeping the contact angle of the surface with an epidermal layer of the foam with water and the water absorption rate of the foam within the ranges controlled by the present invention.

[0101] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the hydrophobic modifier is 0.5% - 2.5%.

[0102] (Flame retardant)

[0103] In some embodiments, the polyol-containing composition further includes a flame retardant.

[0104] In some embodiments, the flame retardant includes, but is not limited to, one or more of expanded graphite, metal hydroxides, antimony trioxide, and zinc borate.

[0105] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the flame retardant is 12% - 30%.

[0106] According to a specific embodiment of the present invention, by using a flame retardant, the polyurethane foam has better flame retardant properties and can meet the UL-94 HBF rating (burning rate < 40 mm / min). Considering from the perspective of flame retardant efficiency, expanded graphite can be selected as the flame retardant; considering from the perspective of comprehensive cost, metal hydroxides can be selected as the flame retardant; the present invention preferably uses expanded graphite. The present invention preferably controls the content of expanded graphite within the above range, so that the polyurethane foam meets the HBF rating requirement of a burning rate < 40 mm / min, and at the same time, the polyurethane foam will not have a permanent deformation rate higher than the range controlled by the present invention due to excessive content of the flame retardant.

[0107] (Crosslinking agent)

[0108] In some embodiments, the polyol-containing composition further includes a crosslinking agent.

[0109] In some embodiments, the crosslinking agent includes, but is not limited to, one or more of bifunctional, trifunctional, and tetrafunctional alcohol compounds, alcohol amine compounds, etc. Examples of bifunctional compounds include, but are not limited to, one or more of monoethanolamine, ethylene glycol, and 1,4-butanediol, etc. Examples of trifunctional compounds include, but are not limited to, one or more of diethanolamine, triethanolamine, glycerol, and trimethylolpropane, etc. Examples of tetrafunctional compounds include, but are not limited to, pentaerythritol, etc. Since ethylene glycol has a symmetric chemical structure and relatively low cost, ethylene glycol is preferably used as the crosslinking agent in consideration of the toughness and cost of the foam.

[0110] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the crosslinking agent is 2% - 4%. The present invention preferably controls the content of the crosslinking agent within the above range, so that the polyurethane foam will not affect its compression and rebound performance due to too low a content of the crosslinking agent, nor will the permanent deformation rate be higher than the range controlled by the present invention due to too high a content of the crosslinking agent.

[0111] (Other functional additives)

[0112] In some embodiments, the polyol-containing composition may also optionally include other functional additives. The other functional additives include, but are not limited to, one or more of anti-aging agents and colorants, etc.

[0113] In some embodiments, the anti-aging agent includes at least one of, but is not limited to, antioxidants (such as 1010, 168, etc.), ultraviolet absorbers (such as UV531), and light stabilizers (such as UV-P), etc.

[0114] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the anti-aging agent is 0.5% - 1.5%.

[0115] In some embodiments, the colorant includes, but is not limited to, one or more of black paste, red paste, yellow paste, blue paste, white paste, etc.

[0116] In some embodiments, based on the total mass of the polyol being 100%, the mass fraction of the colorant is 1% - 3%.

[0117] (Isocyanate)

[0118] In some embodiments, the viscosity of the isocyanate (including isocyanate and its modified products) is 1 - 4000 mPa·s (25°C), the content of NCO (isocyanate group) is 13% - 48%, and the average functionality ≥ 2.

[0119] In some embodiments, the isocyanate may include, but is not limited to, one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (PAPI), and their modified products, etc. Preferably, the isocyanate may be a modified product of TDI and / or MDI. Specifically, the isocyanate may include, but is not limited to, one or more of TDI-80, polyether-modified MDI, carbodiimide slightly modified MDI Lupranate 227, etc.

[0120] In some embodiments, the NCO index, that is, the molar ratio of -NCO (isocyanate group) of the isocyanate to -OH (hydroxyl group) of the polyol, is (1.00 - 1.10):1. Preferably, the NCO index is 1.05; according to the calculation with an NCO index of 1.05, the mass ratio of the isocyanate to the polyol-containing composition is (30 - 140):100.

[0121] (Preparation steps)

[0122] As described above, the method for preparing the polyurethane foam includes: coating a raw material mixture of the polyurethane foam on the surface of a film material, and after reaction, obtaining the polyurethane foam.

[0123] In some embodiments, the preparation steps of the polyurethane foam may specifically include:

[0124] Mixing: Mixing the components of the polyol-containing composition evenly under stirring conditions to obtain a polyol-containing composition; then mixing the polyol-containing composition with the isocyanate evenly under stirring conditions to obtain a raw material mixture of the polyurethane foam;

[0125] Coating: Coating the raw material mixture of the polyurethane foam on the surface of the film material;

[0126] Reaction: After reacting at a suitable temperature for a suitable time, a polyurethane foam is formed on the surface of the film material.

[0127] In some embodiments, the stirring speed in the mixing step can generally be 1500 - 3000 revolutions per minute. When using nitrogen as a foaming agent, a polyol-containing composition without a foaming agent can be prepared first in the mixing step, and then it is mixed evenly with the isocyanate under stirring conditions while injecting nitrogen. In this case, the stirring speed can be 400 - 500 revolutions per minute. Among them, the way of injecting nitrogen can be continuous injection throughout the production process, and no special limitation is imposed on the injection amount of nitrogen, as long as a polyurethane foam with the cell area ratio on the outer surface of the skin layer and the core open cell rate controlled by the present invention can be prepared.

[0128] In some embodiments, the coating method can adopt conventional methods in the art, such as but not limited to double-film coating or single-film coating, etc. The coating amount can be determined based on the thickness of the polyurethane foam controlled by the present invention. When the double-film coating process is adopted, the raw material mixture of the polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture of the polyurethane foam. After reaction, polyurethane foam is formed in the middle of the upper film material and the lower film material. When the single-film coating process is adopted, the raw material mixture of the polyurethane foam is coated on the surface of the lower film material, and after reaction, polyurethane foam is formed on the surface of the lower film material.

[0129] In some embodiments, when at least one surface of the polyurethane foam has a coating, the preparation method of the polyurethane foam of the present invention (i.e., the polyurethane foam with a coating) includes:

[0130] Preparation of the coating: Spraying the raw material mixture of the coating on the surface of the film material to obtain a film material containing the coating;

[0131] Coating: Coating the raw material mixture of the polyurethane foam on the surface of the film material containing the coating;

[0132] Reaction: After reacting at a suitable temperature for a suitable time, polyurethane foam is formed on the surface of the film material.

[0133] Among them, the raw material mixture of the coating can be the raw material mixture of the polyurethane foam without a blowing agent. In addition, the mixing steps of the raw material mixture of the polyurethane foam are as described above and will not be elaborated here. In addition, the mixing steps of the raw material mixture of the coating are basically the same as those of the raw material mixture of the polyurethane foam, except that no blowing agent is added. In addition, whether double-film coating or single-film coating is adopted, the raw material mixture of the coating can be sprayed on the surface of the lower film material, and the surface of the upper film material can be selected to be sprayed or not sprayed with the raw material mixture of the coating.

[0134] In some embodiments, the film materials (including the upper film material and the lower film material) include at least one of a common silicon-free paper-based release film, a silicone oil-containing release film, a mirror release film, etc. These release films can all use commercially available products. Since the mirror release film is more excellent and prominent in terms of high transparency, excellent anti-adhesion performance, easy peeling, etc., it is helpful for the integrity and continuity of the polyurethane foam skin layer. Therefore, it is preferably to use a mirror release film, so that the skin layer of the polyurethane foam is smoother, and it is beneficial to make the proportion of the cell area on the outer surface of the skin layer within the range controlled by the present invention. In addition, as described above, the present invention preferably introduces a hydrophobic modifier into the polyol-containing composition, and combined with the use of the above release film, a hydrophobic interface can be formed on the skin layer of the present invention. Especially in the case of using a mirror release film, a superhydrophobic interface can be formed, which is more beneficial to keep the contact angle between the surface with the skin layer and water and the water absorption rate of the foam within the range controlled by the present invention, and can effectively prevent the penetration of moisture, having a good waterproof and sealing effect.

[0135] In some embodiments, the thicknesses of the upper film material and the lower film material are 0.03 - 0.15 mm respectively. If the film material thickness is too small or too large, the comprehensive cost will be increased, and the preferred thickness is 0.05 - 0.1 mm.

[0136] In some embodiments, the appropriate temperature is 60°C - 120°C, and the appropriate time is 10 min - 30 min. After the reaction is completed, the upper film material and the lower film material are peeled off (when using the double-film coating process), or the lower film material is peeled off (when using the single-film coating process) to obtain the polyurethane foam.

[0137] According to the specific embodiments of the present invention, the preparation method of the present invention can realize the continuous and large-scale preparation of polyurethane foam with a thickness of less than 20 mm, and can realize the preparation of polyurethane foam with a skin layer having an outer surface cell area ratio of 30% - 50% and a core part having an open cell rate of 80% - 95% controlled by the present invention.

[0138] <Application>

[0139] The polyurethane foam of the present invention has both good vacuum pumping performance and filling performance, and good waterproof and sealing performance, and is suitable for use as a filling material for the battery pack gap in the battery pack.

[0140] According to the specific embodiments of the present invention, the present invention provides a battery pack, which at least includes: a box body, a battery cell module, and a filling component; the box body at least includes a bottom plate and an end plate, the bottom plate and the end plate enclose a chamber, and several beam bodies are arranged in the chamber; the battery cell module is arranged in the chamber of the box body;

[0141] There is a gap between the battery cell module and the beam, and / or there is a gap between the battery cell module and the end plate; the filling component is filled in the gap;

[0142] The filling component includes a packaging bag and a filling material disposed in the packaging bag;

[0143] The filling material is the polyurethane foam mentioned above.

[0144] According to the specific embodiments of the present invention, the present invention also provides a method for filling the gap of a battery pack, which includes the following steps: placing the polyurethane foam in a packaging bag to obtain a filling component; evacuating the filling component; then placing the evacuated filling component in the gap of the battery pack; and then breaking the vacuum of the filling component to make the filling component fill in the gap.

[0145] In some embodiments, the thickness of the packaging bag is 0.02 - 0.1 mm, preferably 0.05 - 0.1 mm. If the thickness of the packaging bag is too low, it is easy to leak air; if the thickness of the packaging bag is too high, it is not conducive to the flatness of the foam after evacuation. The present invention controls the thickness of the packaging bag within the above range, so that the packaging bag is not easy to leak air and ensures that the foam after evacuation has better flatness.

[0146] In some embodiments, the material of the packaging bag may include but is not limited to at least one of NY / CPE (nylon / polyvinyl chloride), PET / NY / PE (polyethylene terephthalate / nylon / polyethylene), NY / PET / PE (nylon / polyethylene terephthalate / polyethylene), etc.

[0147] In some embodiments, the degree of vacuum achieved by evacuating the filling component is ≤ -0.1 MPa.

[0148] In some embodiments, the packaging bag is provided with a tear notch, and breaking the vacuum of the filling component is achieved by tearing the packaging tape through the tear notch.

[0149] On the one hand, the polyurethane foam of the present invention has good compression and rebound performance, and thus has good vacuum-pumping performance and filling performance. The polyurethane foam of the present invention can be easily and quickly placed in the gaps of the battery pack after being vacuum-pumped, which has the advantage of simple operation. Moreover, after breaking the vacuum, the polyurethane foam of the present invention can quickly expand, fill the gaps of the battery pack, and can provide a suitable compression and rebound force for a long time, achieving a snug and tight filling in the gaps, preventing problems such as looseness, shaking or displacement between the components in the battery pack, and at the same time not causing excessive extrusion to the components in the battery pack. On the other hand, the polyurethane foam of the present invention also has good waterproof and sealing performance, and can play roles such as glue blocking, glue plugging, waterproofing, and preventing glue leakage in the battery pack.

[0150] Embodiment

[0151] The technical solution of the present invention will be specifically described below through examples. However, the present invention is not limited to these examples, and of course, various deformations can be carried out within the scope of the key points of the present invention for implementation.

[0152] The raw materials used in the following examples and comparative examples include:

[0153] The first polyol: polyether polyol CHE-306, with a hydroxyl value of 305 mgKOH / g, an average functionality of 3, and a molecular weight of 550;

[0154] The second polyol: polyether polyol CHE-1Q59, with a hydroxyl value of 32.5 mgKOH / g, a primary hydroxyl content of 85%, an average functionality of 4.2, and a molecular weight of 7500;

[0155] The third polyol: polymer polyol CHP-H30, with a hydroxyl value of 22 - 27 mgKOH / g, an average functionality of 3, and a solid content of 26% - 30%;

[0156] The blowing agent: deionized water or nitrogen;

[0157] The metal catalyst: bismuth carboxylate DABCO MB20;

[0158] The blowing catalyst: A33 (i.e., a solution prepared from 33% triethylenediamine and 67% dipropylene glycol);

[0159] The foam stabilizer: polyether-modified silicone oil DC2525;

[0160] The hydrophobic modifier: XSY-W601;

[0161] The flame retardant: expanded graphite EG-150;

[0162] The crosslinking agent: ethylene glycol, polyester grade;

[0163] Antioxidant: 1010;

[0164] Colorant: Special Black ZY8069;

[0165] Toluene diisocyanate: TDI-80, viscosity is 3 mPa·s (25°C), NCO content is 48%, average functionality is 2.0;

[0166] Self-made polyether-modified MDI: viscosity is 3000±500 mPa·s (25°C), NCO content is 13%±2%, average functionality is 2.1; The preparation method of this polyether-modified MDI includes: reacting pure MDI (MDI-100), polyether polyol CHE-306 and polyether polyol CHED-28 in a mass ratio of 57:4:39 in a reaction kettle at 65-85°C under stirring conditions for 2.5 h to obtain polyether-modified MDI;

[0167] MDI-100: NCO content is 33.5%;

[0168] CHE-306: hydroxyl value is 305 mgKOH / g, average functionality is 3, molecular weight is 550;

[0169] CHED-28: hydroxyl value is 28 mgKOH / g, average functionality is 2, molecular weight is 4000;

[0170] Carbodiimide slightly modified MDI: Lupranate 227, viscosity is 28 mPa·s (25°C), NCO content is 32.1%, average functionality is 2.2.

[0171] Example 1

[0172] By weight, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.024 part of bismuth carboxylate DABCO MB20, 0.016 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 47 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam was coated on the surface of the lower film material, and then the upper film material was covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material were PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam was formed in the middle of the upper film material and the lower film material. After the reaction ended, the upper film material and the lower film material were peeled off to obtain polyurethane foam. The scanning electron microscope photograph of the surface of the polyurethane foam in this example is as Figure 1 shown.

[0173] Example 2

[0174] By weight, 20 parts of polyether polyol CHE-306, 40 parts of polyether polyol CHE-1Q59, 40 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.015 part of bismuth carboxylate DABCO MB20, 0.015 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 40 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam was coated on the surface of the lower film material, and then the upper film material was covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material were PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam was formed in the middle of the upper film material and the lower film material. After the reaction ended, the upper film material and the lower film material were peeled off to obtain polyurethane foam.

[0175] Example 3

[0176] By weight, 50 parts of polyether polyol CHE-306, 25 parts of polyether polyol CHE-1Q59, 25 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.03 part of bismuth carboxylate DABCO MB20, 0.03 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 20 parts of expanded graphite EG-150, 2 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 51 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0177] Example 4

[0178] By weight, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 0.5 part of deionized water, 0.05 part of bismuth carboxylate DABCO MB20, 0.05 part of A33, 0.5 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 0.5 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 42 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0179] Example 5

[0180] By weight, 24 parts of polyether polyol CHE-306, 38 parts of polyether polyol CHE-1Q59, 38 parts of polymer polyol CHP-H30, 1.5 parts of deionized water, 0.006 part of bismuth carboxylate DABCO MB20, 0.004 part of A33, 2.5 parts of hydrophobic modifier XSY-W601, 30 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 1.5 parts of antioxidant 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 42 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0181] Example 6

[0182] By weight, 30 parts of polyether polyol CHE-306, 35 parts of polyether polyol CHE-1Q59, 35 parts of polymer polyol CHP-H30, 1.5 parts of deionized water, 0.066 part of bismuth carboxylate DABCO MB20, 0.034 part of A33, 1.0 part of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.7 part of foam stabilizer DC2525, 1.5 parts of antioxidant 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 51 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0183] Example 7

[0184] By weight, 30 parts of polyether polyol CHE-306, 35 parts of polyether polyol CHE-1Q59, 35 parts of polymer polyol CHP-H30, 1.5 parts of deionized water, 0.06 part of bismuth carboxylate DABCO MB20, 0.04 part of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 52 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam;

[0185] By weight, 30 parts of polyether polyol CHE-306, 35 parts of polyether polyol CHE-1Q59, 35 parts of polymer polyol CHP-H30, 0.06 part of bismuth carboxylate DABCO MB20, 0.04 part of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 34 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for the coating;

[0186] The raw material mixture for the coating was sprayed onto the surface of the lower film material with a spraying machine to obtain a lower film material with a coating; the thickness of the coating was about 0.1 mm;

[0187] Using a double-film coating process, the raw material mixture for polyurethane foam was coated onto the surface of the lower film material with a coating, and then the upper film material was covered onto the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower film material were PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam was formed in the middle of the upper film material and the lower film material. After the reaction was completed, the upper film material and the lower film material were peeled off to obtain polyurethane foam. One surface of the polyurethane foam in this example had a coating. The scanning electron microscope photos of the surface of the polyurethane foam in this example before vacuum pumping were as shown in Figure 2 ; the scanning electron microscope photos of the surface after vacuum pumping were as shown in Figure 3 ; among them, the polyurethane foam in this example was placed in a packaging bag and then vacuum pumped. The vacuum pumping time was 20 s, the vacuum degree in the packaging bag after vacuum pumping was -0.1 MPa, and the single-layer thickness of the packaging bag was 0.05 mm.

[0188] Example 8

[0189] By weight, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 0.5 part of deionized water, 0.006 part of bismuth carboxylate DABCO MB20, 0.004 part of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions, and the stirring speed was 2000 revolutions per minute to obtain a polyol-containing composition without a foaming agent; then 100 parts of the polyol-containing composition without a foaming agent and 42 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions, and nitrogen was injected into the mixture as a foaming agent at a flow rate of 5-6 L / min, and the stirring speed was 400-500 revolutions per minute. The nitrogen was injected in a continuous manner from the start of the machine until the end of the machine along with the entire production process to obtain a raw material mixture for polyurethane foam; a double-film coating process was used to coat the raw material mixture for polyurethane foam on the surface of the lower film material, and then the upper film material was covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material were PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam was formed in the middle of the upper film material and the lower film material. After the reaction was completed, the upper film material and the lower film material were peeled off to obtain polyurethane foam.

[0190] Example 9

[0191] By weight, 50 parts of polyether polyol CHE-306, 25 parts of polyether polyol CHE-1Q59, 25 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.024 part of bismuth carboxylate DABCO MB20, 0.016 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 139 parts of self-made polyether-modified MDI are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are made of PET mirror release film with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0192] Example 10

[0193] By weight, 50 parts of polyether polyol CHE-306, 25 parts of polyether polyol CHE-1Q59, 25 parts of polymer polyol CHP-H30, 0.5 part of deionized water, 0.024 part of bismuth carboxylate DABCO MB20, 0.016 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 4 parts of ethylene glycol, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 36 parts of isocyanate TDI-80 are mixed evenly under stirring conditions, and the stirring speed is 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are made of PET mirror release film with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0194] Comparative Example 1

[0195] By weight, 10 parts of polyether polyol CHE-306, 45 parts of polyether polyol CHE-1Q59, 45 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.024 part of bismuth carboxylate DABCO MB20, 0.016 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 34 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0196] Comparative Example 2

[0197] By weight, 60 parts of polyether polyol CHE-306, 20 parts of polyether polyol CHE-1Q59, 20 parts of polymer polyol CHP-H30, 1.0 part of deionized water, 0.024 part of bismuth carboxylate DABCO MB20, 0.016 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 61 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions at a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0198] Comparative Example 3

[0199] By weight, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 0.4 part of deionized water, 0.06 part of bismuth carboxylate DABCO MB20, 0.04 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, with a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 40 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, with a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are made of PET mirror release film with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0200] Comparative Example 4

[0201] By weight, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 1.6 parts of deionized water, 0.08 part of bismuth carboxylate DABCO MB20, 0.04 part of A33, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed evenly under stirring conditions, with a stirring speed of 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 55 parts of isocyanate Lupranate 227 are mixed evenly under stirring conditions, with a stirring speed of 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam is coated on the surface of the lower film material, and then the upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material are made of PET mirror release film with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam is formed in the middle of the upper film material and the lower film material. After the reaction is completed, the upper film material and the lower film material are peeled off to obtain polyurethane foam.

[0202] Comparative Example 5

[0203] By weight parts, 33.4 parts of polyether polyol CHE-306, 33.3 parts of polyether polyol CHE-1Q59, 33.3 parts of polymer polyol CHP-H30, 0.5 part of deionized water, 0.006 part of bismuth carboxylate DABCO MB20, 0.003 part of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 1.5 parts of ethylene glycol, 0.8 part of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed evenly under stirring conditions, and the stirring speed was 2000 revolutions per minute to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 36 parts of isocyanate Lupranate 227 were mixed evenly under stirring conditions, and the stirring speed was 2000 revolutions per minute to obtain a raw material mixture for polyurethane foam; using a double-film coating process, the raw material mixture for polyurethane foam was coated on the surface of the lower film material, and then the upper film material was covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower mold material were PET mirror release films with a thickness of 0.05 mm. After reacting at 100 °C for 15 min, polyurethane foam was formed in the middle of the upper film material and the lower film material. After the reaction was completed, the upper film material and the lower film material were peeled off to obtain polyurethane foam.

[0204] The characteristics of the polyurethane foams in the above examples and comparative examples are shown in Table 1 and Table 2 respectively.

[0205] The polyurethane foams were evaluated according to the following criteria, and the evaluation results are shown in Table 1 and Table 2:

[0206] Vacuumable performance: If the thickness retention rate after vacuuming ≤ 35%, it is qualified; if the thickness retention rate after vacuuming > 35%, it is unqualified.

[0207] Filling performance: If the time required for the thickness recovery rate to be 60% is 5 - 20 min and the time required for the thickness recovery rate to be 95% is 1 h - 12 h, it is qualified; if the time required for the thickness recovery rate to be 60% or the time required for the thickness recovery rate to be 95% is not within the above range, it is unqualified.

[0208] Waterproof sealing performance: If the contact angle of the surface with the skin layer with water > 105° and the water absorption rate < 10%, it is qualified; if the contact angle of the surface with the skin layer with water or the water absorption rate is not within the above range, it is unqualified.

[0209] Table 1 Characteristics of Examples

[0210]

[0211] Table 2 Characteristics of Comparative Examples

[0212]

[0213] As can be seen from Table 1 and Table 2, the proportion of the cell area on the outer surface of the skin layer of the polyurethane foam provided in Comparative Examples 1-5 and / or the core opening ratio are not within the scope of the present invention. These polyurethane foams cannot have both good vacuum-pumpable performance and filling performance, as well as good waterproof sealing performance.

[0214] On the one hand, the polyurethane foams provided in Examples 1-10 of the present invention have good compression performance and rebound performance, and can be easily placed in the gaps of the battery pack after being evacuated. After breaking the vacuum, they can fit tightly and fill the gaps of the battery pack, and at the same time will not cause excessive extrusion to the components in the battery pack, having good vacuum-pumpable performance and filling performance; on the other hand, they have good waterproof sealing performance and can play roles such as glue blocking, glue plugging, waterproofing, and preventing glue leakage in the battery pack.

[0215] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A polyurethane foam, the polyurethane foam comprising a surface and a core inside the surface, at least a part of the surface having an epidermis layer, the proportion of the cell area of the outer surface of the epidermis layer being 30%-50%, and the open cell rate of the core being 80%-95%.

2. The polyurethane foam according to claim 1, wherein, The contact angle between the surface of the polyurethane foam having the epidermis layer and water > 105°.

3. The polyurethane foam according to claim 1, wherein, The water absorption rate of the polyurethane foam < 10%.

4. The polyurethane foam according to claim 1, wherein, The density of the polyurethane foam is 80 - 200 kg / m 3 .

5. The polyurethane foam according to claim 1, wherein, The thickness of the polyurethane foam is 2-20 mm.

6. The polyurethane foam according to claim 1, wherein, The average cell diameter of the core of the polyurethane foam is 100-300 μm.

7. The polyurethane foam according to claim 1, wherein The 15% compression strength of the polyurethane foam is 10-50 kPa, and the 70% compression strength of the polyurethane foam is 60-150 kPa.

8. The polyurethane foam according to claim 1, wherein, The permanent deformation rate of the polyurethane foam after 10,000 times of 50% compression ≤ 10%.

9. The polyurethane foam according to claim 1, wherein, After the polyurethane foam is placed in a packaging bag and evacuated, the thickness retention rate of the polyurethane foam ≤ 35%.

10. The polyurethane foam according to claim 1, wherein, After the polyurethane foam is placed in a packaging bag and evacuated, and then the vacuum is broken, the time required for the thickness recovery rate of the polyurethane foam to reach 60% is 5-20 min, and the time required for the thickness recovery rate of the polyurethane foam to reach 95% is 1 h-12 h.

11. The polyurethane foam according to claim 1, wherein, At least one surface of the polyurethane foam has a coating.

12. A battery pack, the battery pack at least comprising: A box body, a battery cell module and a filling component; the box body at least includes a bottom plate and an end plate, the bottom plate and the end plate enclose a chamber, and a plurality of beam bodies are arranged in the chamber; the battery cell module is arranged in the chamber of the box body; There is a gap between the battery cell module and the beam body, and / or there is a gap between the battery cell module and the end plate; the filling component is filled in the gap; the filling component includes a packaging bag and a filling material arranged in the packaging bag; The filling material is the polyurethane foam according to any one of claims 1-11.

13. A method for filling the gaps in a battery pack, comprising the following steps: The polyurethane foam according to any one of claims 1-11 is placed in a packaging bag to obtain a filling component; the filling component is evacuated; then the evacuated filling component is placed in the gap of the battery pack; after that, the vacuum of the filling component is broken to make the filling component fill in the gap.

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