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

Abstract

The present invention discloses polyurethane foam, a battery pack, and a method for filling gaps in a battery pack, belonging to the field of polyurethane technology. The polyurethane foam comprises a surface and a core within the surface, at least a portion of the surface having a skin layer, the outer surface of the skin layer having a pore area of ​​30%-50%, and the core having an open porosity of 80%-95%. The polyurethane foam of the present invention has both good vacuuming and filling properties, as well as good waterproof and sealing properties. After vacuuming, it can be placed in the gap of the battery pack, and after the vacuum is broken, it fills the gap tightly and docilely, while also providing a waterproof and sealing effect.

Description

Technical Field

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

[0002] With the rapid development of new energy vehicles, the corresponding development of automotive power batteries is also rapid. Automotive power batteries are typically supplied to automakers in the form of battery packs. Battery packs typically consist of multiple components, such as cell modules and a housing. When designing a battery pack, a gap of 1-12mm is typically reserved to ensure efficient installation and removal of each component.

[0003] A high-performance battery pack must meet at least the following three conditions: ① The aforementioned gaps must be filled, ensuring a tight fit between components within the pack to prevent looseness, shaking, or displacement. ② The filling material used to fill these gaps must possess excellent waterproof sealing properties, such as blocking and preventing glue leakage. ③ Filling these gaps must be quick and easy during assembly and disassembly.

[0004] In the prior art, filling materials used to fill these gaps primarily include glue-based materials such as potting compounds, sealants, and caulking compounds. These glue-based materials often have high viscosity, which can easily trap air during use, leading to bubbles in the cured glue, which can affect the strength and sealing properties of the cured glue. Furthermore, due to the varying sizes of the gaps, it can be difficult to determine whether the glue has completely filled the gaps during use.

[0005] On the other hand, polyurethane, as an emerging organic polymer material, is known as the "fifth plastic". Due to its good shock absorption, sealing, and thermal insulation properties, it is widely used in 3C electronic products, new energy vehicles, architectural decoration and other fields.

[0006] In response to the above-mentioned problems in existing battery packs, the inventors considered using polyurethane foam to fill the gaps in the battery packs. However, the inventors found that due to the unique resilience of existing polyurethane foam, trying to fill the narrow gaps in the battery pack with polyurethane foam will lead to complicated process operations, increased difficulty in operation, and reduced assembly efficiency. At the same time, the fit between the existing polyurethane foam and the components needs to be further improved. Moreover, the waterproof sealing performance of the existing polyurethane foam also needs to be further improved to avoid glue leakage and other situations. In other words, the existing polyurethane foam still cannot solve the above-mentioned problems in existing battery packs. Summary of the Invention

[0007] In order to solve the above technical problems, the purpose 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] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a polyurethane foam, which includes a surface and a core inside the surface, at least a portion of the surface has a skin layer, the pore area of ​​the outer surface of the skin layer accounts for 30%-50%, and the open porosity of the core is 80%-95%.

[0009] According to a specific embodiment of the present invention, preferably, the contact angle between the surface of the polyurethane foam having the epidermal layer and water is greater than 105°.

[0010] According to a specific embodiment of the present invention, preferably, the water absorption rate of the polyurethane foam is less than 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 of the polyurethane foam is 100-300 μm.

[0014] According to a specific embodiment of the present invention, preferably, 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.

[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 is ≤10%.

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

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

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

[0019] A second aspect of the present invention provides a battery pack, comprising at least: a box, a battery cell module, and a filling assembly; the box comprising at least a bottom plate and an end plate, the bottom plate and the end plate forming a cavity, wherein a plurality of beams are disposed in the cavity; the battery cell module is disposed in the cavity of the box;

[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 assembly includes a packaging bag and a filling material disposed in the packaging bag;

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

[0023] The third aspect of the present invention provides a method for filling the gaps in a battery pack, 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 vacuumed filling component in the gaps in the battery pack; and then breaking the vacuum of the filling component to allow the filling component to fill the gaps.

[0024] Effects 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 and rebound properties, and can be easily placed in the gap of the battery pack after being vacuumed, and can be tightly and compactly filled in the gap of the battery pack after the vacuum is broken, without causing excessive squeezing of the components in the battery pack, and has good vacuuming and filling properties; on the other hand, the polyurethane foam of the present invention has good waterproof and sealing properties, and can play the roles of blocking glue, plugging glue, waterproofing, and preventing glue leakage in the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0029] Figure 3 This is a scanning electron microscope photograph of the surface of the polyurethane foam of Example 7 after vacuuming. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

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

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] It will be understood that the terms “comprises,” “comprising,” and / or “containing” when used herein specify the presence of 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] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be 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, which includes a surface and a core inside the surface, at least a portion of the surface has a skin layer, the pore area of ​​the outer surface of the skin layer accounts for 30%-50%, and the open porosity of the core is 80%-95%.

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

[0038] The cell area percentage of the outer surface of the epidermis is measured using the following method: scanning the outer surface of the epidermis of the polyurethane foam using a scanning electron microscope (SEM), identifying the cell area using the grayscale difference between the cell area and the non-cell area, and calculating the percentage of the cell area to the entire field of view using image analysis software. This is the cell area percentage of the outer surface of the epidermis. The size of the field of view is determined based on the magnification of the SEM. For each sample, the number of cells measured each time can be, for example, 50-200, preferably 50-100. Five or more samples are randomly and independently taken from the outer surface of the epidermis of the polyurethane foam. The above process is repeated and the average value is taken to obtain the cell area percentage of the outer surface of the epidermis of the polyurethane foam.

[0039] The open porosity of the core is measured according to the method described in GB / T10799-2008 (Determination of volume percentage of open and closed cells of rigid foam plastics). Specifically, the open porosity of the core adopts the volume open porosity in GB / T10799-2008. v The core porosity test specimens were prepared as follows: polyurethane foam was cut into 25 mm long x 25 mm wide pieces. After removing 1 / 3 of the thickness from the top and bottom surfaces, the remaining middle portion (i.e., the middle 1 / 3 thickness) was used as the specimen. If the remaining middle portion was less than 50 mm thick, multiple pieces of the middle portion were stacked to achieve a total thickness of 50 mm or greater. In the specific examples below, the core porosity test was conducted using a BSD-TD fully automatic true density porosity analyzer.

[0040] The inventors have discovered through research that if the pore area of ​​the outer surface of the epidermis accounts for more than 50%, the polyurethane foam is easy to be vacuumed, but has poor waterproof and sealing performance; if the pore area of ​​the outer surface of the epidermis accounts for less than 30%, the polyurethane foam has good waterproof and sealing performance, but is not easy to be vacuumed; if the open porosity of the core is more than 95%, the polyurethane foam has poor waterproof and sealing performance; if the open porosity of the core is less than 80%, the polyurethane foam has poor rebound performance and is not conducive to vacuuming. The present invention controls the pore area of ​​the outer surface of the epidermis to 30%-50%, and at the same time controls the open porosity of the core to 80%-95%, thereby ensuring that the polyurethane foam has both good vacuumability and filling performance, as well as good waterproof and sealing performance, achieving a good balance between compression rebound performance and waterproof and sealing performance.

[0041] In some embodiments, the contact angle of the surface of the polyurethane foam with the skin layer with water is greater than 105°, for example, 110°, 120°, 130°, 140°, 150°, or 160°. In addition to controlling the surface of the polyurethane foam to have a skin layer with a cell area accounting for 30%-50% of the outer surface, the present invention further controls the contact angle of the surface of the skin layer with water to be greater than 105°, thereby providing the surface of the polyurethane foam with a hydrophobic interface and thereby improving the waterproof and sealing properties of the polyurethane foam. The contact angle of the surface of the polyurethane foam with the skin layer with water is measured according to the method described in ASTM D5725-99 (2003) (Standard Method for Testing the Wettability and Absorbency of Sheet-Shaped Materials Using an Automatic Contact Angle Tester). In the specific examples below, the instrument used for this test is a CA200S fully automatic optical contact angle meter.

[0042] In some embodiments, the polyurethane foam has a water absorption rate of less than 10%, such as 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%. The present invention controls the surface of the polyurethane foam to have a skin layer with an outer surface pore area accounting for 30%-50%, which can reduce or even prevent the passage of water and other small molecules through the foam. Furthermore, the water absorption rate of the polyurethane foam is controlled to less than 10%, resulting in better waterproof and sealing properties. 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 water absorption rate is calculated as follows: 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 , for example 80kg / m 3 、100kg / m 3 , 120kg / m 3 、140kg / m 3 、160kg / m 3 、180kg / m 3 or 200kg / m 3 etc., preferably 100-180 kg / m 3 The density of polyurethane foam is measured according to the method described in GB / T 6343-2009 (Determination of apparent density of foamed plastics and rubber). The apparent total density calculated using formula (1) in 7.1 of this standard is the density of 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., preferably 2-15 mm. In the specific examples below, the thickness of the polyurethane foam can be measured using a commercially available thickness gauge.

[0045] The present invention controls the density and thickness of the polyurethane foam within the above ranges, which can further enable the polyurethane foam to have better compression performance and thus better vacuumability.

[0046] In some embodiments, the polyurethane foam is a sheet-like foam material (also referred to as a polyurethane foam sheet), and its plane shape is, for example, but not limited to, rectangular, circular, etc. The present invention does not impose any special restrictions on its plane shape and size, and those skilled in the art can make a conventional selection based on actual conditions.

[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, thereby 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 performance of the foam. The present invention, on the basis of controlling the pore area ratio of the outer surface of the epidermis and the open porosity of the core within the above range, further controls the average pore diameter of the core of the polyurethane foam within the above range, so that the polyurethane foam has better compression rebound performance, thereby having better vacuum performance and filling performance. The method for testing the average cell diameter of the polyurethane foam core includes: cutting the polyurethane foam core perpendicular to the thickness of the polyurethane foam to obtain a cross-sectional specimen; soaking the specimen in liquid nitrogen for 1 minute, then taking a magnified photograph of the cross-sectional specimen using a scanning electron microscope (SEM), and measuring the diameters of all cells within the cross-section with a length and width less than 30 mm. The field of view is determined by the SEM magnification. For each specimen, the number of cells measured at each time can be, for example, 50-200, preferably 50-100. The above procedure is repeated at five or more random locations within the polyurethane foam core, and the average value is calculated to determine the average cell diameter of the polyurethane foam core.

[0048] In some embodiments, the 15% compressive strength of the polyurethane foam is 10-50 kPa, for example, 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% compressive strength of the polyurethane foam is 60-150 kPa, for example, 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 polyurethane foam can represent the preload of the foam (i.e., the initial compression rebound force before it is in the working state), and is also the expansion force on the module at the early stage of use of the battery module (i.e., the early stage of its life); the 70% compression strength can represent the compression rebound force of the foam in the long-term working state when it is used to fill gaps in the battery pack, and is also the expansion force on the module at the end of the use of the battery module (i.e., the end of its life).

[0050] If the 15% and 70% compressive strengths of the polyurethane foam are below the aforementioned ranges, the compression rebound force of the polyurethane foam is too low, and the components in the battery pack are prone to sagging, shaking, or shifting. If the 15% and 70% compressive strengths of the polyurethane foam are above the aforementioned ranges, the compression rebound force of the polyurethane foam is too high, and the components in the battery pack are easily deformed due to compression, and the polyurethane foam's vacuumability is also poor. The present invention further controls the 15% and 70% compressive strengths of the polyurethane foam within the aforementioned ranges, thereby achieving both good vacuumability and filling properties.

[0051] The 15% compressive strength and 70% compressive strength of the polyurethane foam are both obtained by testing according to the method described in Test-C of ASTM D 3574-17. Specifically, the following steps may be included:

[0052] The first step is to use a polyurethane foam sheet with a plane size of 50mm×50mm. ① For sheets with a thickness of 10mm-20mm, use a single sheet as the sample. ② For sheets with a thickness of less than 10mm, stack the sheets until the thickness is greater than or equal to 10mm before using them as the sample. For example: stack 5 layers of 2mm sheets, 4 layers of 3mm sheets, 3 layers of 4mm sheets, 2 layers of 5mm sheets, 2 layers of 8mm sheets, etc.

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

[0054] In the third step, the sample is subjected to a compression test with the maximum pressure set to 2000N and the compression speed set to 2mm / min. The sample is kept in a compression state for 60s for every 5% compression (e.g., the compression is 5%, 10%, 15%...70%, etc., and the sample is kept in a compression state for 60s).

[0055] Thus, the compressive strength of the polyurethane foam when compressed by 15% (i.e., compressed to 85% of the initial thickness of the sample) and compressed by 70% (i.e., compressed to 30% of the initial thickness of the sample) were obtained respectively.

[0056] In the specific embodiments below, the instrument used for the 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%, for example, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1%, etc., preferably ≤5%.

[0058] Generally speaking, polyurethane foam loses thickness after repeated compression. The present invention further controls the permanent deformation rate of the polyurethane foam after 10,000 cycles of 50% compression within the aforementioned range, minimizing the thickness loss after repeated compression. This, in turn, improves the foam's fatigue resistance and extends its service life.

[0059] The permanent deformation rate of the polyurethane foam after 10,000 cycles of 50% compression is obtained by testing according to the method described in Test-I5 of ASTM D3574-17. Specifically, the following steps may be included:

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

[0061] The second step is the same as the second step of the 15% compressive strength and 70% compressive strength tests of the polyurethane foam described above;

[0062] The third step is to perform a compression test on the sample, increasing the compression amount of the sample from 0% to 50% and then removing the compression, which is recorded as one compression, and the compression speed is 12 mm / min, and the compression is performed 10,000 times;

[0063] Step 4. Calculate the permanent deformation of the sample. The formula for calculating the permanent deformation is: Permanent deformation (%) = (thickness of polyurethane foam before compression - thickness of polyurethane foam after 10,000 compressions of 50%) × 100% / thickness of polyurethane foam before compression.

[0064] In the specific embodiments below, the instrument used for the 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 below 35%, ensuring that the polyurethane foam exhibits excellent vacuumability. If the thickness retention rate of the polyurethane foam after evacuation is greater than 35%, the polyurethane foam is difficult to evacuate and exhibits poor vacuumability. The evacuation time is ≤20 seconds (e.g., 20 seconds), and the vacuum level within the packaging bag after evacuation is -0.1 MPa. The present invention does not impose any particular restrictions on the equipment used for evacuation; commercially available equipment can be used. The thickness retention rate is calculated as follows: Thickness retention rate (%) = (Total thickness of the polyurethane foam and 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 comprises two thickness surfaces, upper and lower, in the thickness direction. Therefore, the total thickness of the packaging bag is twice the thickness of a single layer of the packaging bag. The thickness of a single layer of the packaging bag is, for example, 0.05 mm.

[0066] In some embodiments, the polyurethane foam is placed in a packaging bag and evacuated. After the vacuum is broken, the time required for the polyurethane foam to recover 60% of its thickness is 5-20 minutes, and the time required for the polyurethane foam to recover 95% of its thickness is 1 hour to 12 hours. The present invention further controls the time required for the polyurethane foam to recover 60% and 95% of its thickness after the vacuum is broken to be within the ranges of 5-20 minutes and 1 hour to 12 hours, respectively. This allows the foam to recover at an appropriate thickness speed, have better rebound force release performance, and thus have better compression rebound performance. This allows the foam to fill gaps in the battery pack more quickly and fully, and has better filling performance. This effectively prevents problems such as loosening, shaking, or shifting between components in the battery pack, while also avoiding excessive squeezing of the battery cells. If the time required for the foam to reach the above-mentioned thickness recovery rate is lower than the above-mentioned time range, the rebound force of the foam is released too quickly, which can easily squeeze and deform the battery cell; if the time required for the foam to reach the above-mentioned thickness recovery rate is higher than the above-mentioned time range, the rebound force of the foam is released too slowly, which can make it difficult to fit and tightly fill the gaps in the battery pack. The vacuuming time is ≤20s (for example, 20s), and the vacuum degree in the packaging bag after vacuuming is -0.1MPa. The thickness of a single layer of the packaging bag is, for example, 0.05mm. The present invention does not impose any special restrictions on the vacuuming instrument, and commercially available instruments can be used. The thickness recovery rate is calculated as follows: Thickness recovery rate (%) = thickness of the polyurethane foam after the vacuum is broken after being placed for the above-mentioned time × 100% / thickness of the polyurethane foam before vacuuming.

[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 with the coating includes a surface that is perpendicular or nearly perpendicular to the thickness direction of the polyurethane foam. It will be understood by those skilled in the art that the coating is located on the outside of the epidermis. The present invention can make the foam have better waterproof sealing performance by further providing a coating on at least one surface of the polyurethane foam, which is suitable for application scenarios with higher waterproof requirements. In the case where the surface of the polyurethane foam has a coating, the percentage of the pore area of ​​the outer surface of the epidermis is still tested using the above method. Specifically, a scanning electron microscope (SEM) is used to scan the coated surface of the polyurethane foam, and the grayscale difference is used to identify the pore area and the non-pore area covered by the coating, thereby calculating the percentage of the pore area of ​​the outer surface of the epidermis.

[0068] <Preparation Method of Polyurethane Foam>

[0069] According to a specific embodiment of the present invention, the preparation method of the polyurethane foam of the present invention comprises the following steps: coating the raw material mixture of the polyurethane foam on the surface of the membrane material, and obtaining the polyurethane foam after reaction.

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

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

[0072] (Polyol)

[0073] In some embodiments, the polyol comprises a combination of a first polyol, a second polyol, and a third polyol, wherein the first polyol comprises a polyol having a hydroxyl value of 220-470 mgKOH / g and an average functionality ≥3, the second polyol comprises a polyol having a hydroxyl value of 24-56 mgKOH / g and an average functionality of 3-6, and the third polyol comprises a polyol having a hydroxyl value of 17-37 mgKOH / g and an average functionality ≥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] The present invention adopts three polyols having the above-mentioned hydroxyl value and average functionality range, and preferably controls the ratio of the three polyols within the above-mentioned range, which is beneficial for making the pore area ratio of the outer surface of the epidermis layer of the polyurethane foam and the open porosity of the core within the range of the present invention, and further helps to make 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 content of the second polyol is ≥70% by mass. The primary hydroxyl content of the polyol is typically provided by the manufacturer. If the manufacturer does not provide the primary hydroxyl content of the polyol, the primary hydroxyl content can be calculated by measuring the amount of reagents consumed in the reaction using conventional methods such as potentiometric titration or acid-base titration. The present invention preferably controls the primary hydroxyl content of the second polyol within the above-mentioned range to provide a suitable open porosity, which is beneficial for ensuring that the core open porosity of the polyurethane foam is within the range controlled by the present invention. This also facilitates rapid curing of the polyurethane foam under the reaction conditions described below.

[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 5,000-12,000, preferably 6,000-10,000. In the present invention, the relative molecular mass of the second polyol is preferably controlled within the above range, which helps ensure that the permanent deformation rate of the polyurethane foam after 10,000 cycles of 50% compression is within the range controlled by the present invention, and also helps to ensure that the foam has good thermal stability. It also helps to ensure that the raw material mixture of the polyurethane foam has an appropriate viscosity, thereby improving the preparation and operability.

[0081] In some embodiments, the third polyol may include a polymer polyol, specifically a polymer polyol formed by graft copolymerization of a polyol with acrylonitrile and / or styrene. The graft copolymerization-modified polyol may include a polyether polyol or a polyester polyol. Because polyester polyols have high viscosity and poor operability, polymer polyols formed by graft copolymerization of polyether polyols with acrylonitrile and styrene are preferred. The average functionality of the polymer polyol is preferably 3.

[0082] In some embodiments, the solid content of the third polyol is 15% to 50% by mass, preferably 25% to 45% by mass. In the present invention, the solid content of the third polyol is preferably controlled within the above range, which helps ensure that the raw material mixture of the polyurethane foam has a suitable viscosity, thereby improving preparation operability; and also helps ensure that the polyurethane foam has a compressive strength, outer surface cell area ratio, and core open porosity 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, and CHP-H50.

[0084] (foaming agent)

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

[0086] In some embodiments, the mass fraction of the blowing agent is 0.5%-1.5%, based on the total mass of the polyol as 100%. The mass fraction of the blowing agent herein preferably refers to the mass fraction of deionized water. In the present invention, the content of the blowing agent is preferably controlled within the above range, which helps to ensure that the density of the polyurethane foam and the average cell diameter of the core are within the ranges controlled by the present invention.

[0087] (catalyst)

[0088] In some embodiments, the catalyst includes one or more of a metal catalyst and a foaming catalyst. The metal catalyst includes one or more of an organometallic catalyst such as an organotin catalyst, potassium carboxylates, bismuth carboxylates, zinc carboxylates (e.g., zinc isooctanoate, zinc neodecanoate), and an organozirconium catalyst. The foaming catalyst includes an amine catalyst, such as one or more of A33 (a solution of 33% triethylenediamine and 67% dipropylene glycol), A1 bis(dimethylaminoethyl) ether (a solution of 70% bis(dimethylaminoethyl) ether and 30% dipropylene glycol), dimethylethanolamine, and pentamethyldiethylenetriamine.

[0089] Polyurethane chemical reactions primarily include two types of reactions: one is the gelation reaction, and the other is the foaming reaction. Metal catalysts are primarily used for the gelation reaction of polyurethane; foaming catalysts are primarily used for the foaming reaction of polyurethane. Considering the need to achieve a good balance between the gelation reaction and the foaming reaction, a combination of a metal catalyst and a foaming catalyst is preferably used. In some embodiments, the mass ratio of the metal catalyst to the foaming catalyst is (1-2):1. If no metal catalyst and foaming catalyst are added, that is, the amount of metal catalyst and foaming catalyst added is 0, the gelation and foaming reactions of the polyurethane are very weak, the foam is difficult to mature, and the foam surface is easily sticky. If the mass ratio of the metal catalyst to the foaming catalyst is greater than 2:1, the gelation reaction is faster than the foaming reaction, which can easily cause the foam surface to shrink, resulting in depressions and excessively high compressive strength. If the mass ratio of the metal catalyst to the foaming catalyst is less than 1:1, the foaming reaction is faster than the gelation reaction, which can easily make the foam surface feel rough and the compressive strength of the foam is easily low.

[0090] In some embodiments, based on the total mass of the polyol as 100%, 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 dimethylsiloxane and polyether, also known as polyether-modified silicone oil. In the present invention, polyether-modified silicone oil is preferably used as the foam stabilizer.

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

[0095] In some embodiments, the mass fraction of the foam stabilizer is 0%-0.7%, based on the total mass of the polyol as 100%. If the foam stabilizer content exceeds the above range, it may cause excessive shrinkage of the foam. In the present invention, the foam stabilizer content is preferably controlled within the above range to more easily maintain the core open porosity and average cell diameter of the foam within the ranges controlled by 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 an acrylic compound, an organosilicon compound, and an organofluorine compound, preferably an organofluorine compound. Organofluorine compounds have high chemical stability, high thermal stability, and are water and oil resistant. Compared to acrylic compounds and organosilicon compounds, organofluorine compounds have lower surface tension and better hydrophobic properties. Therefore, organofluorine compounds are preferably used as hydrophobic modifiers in the present invention.

[0099] Specifically, the organic fluorine compound includes, for example, one or more of XSY-W601 waterproofing agent, XSY-W802 waterproofing agent, XSY-W801 waterproofing agent, and perfluorohexylethanol.

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

[0101] In some embodiments, based on the total mass of the polyol as 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 comprises a flame retardant.

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

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

[0106] According to a specific embodiment of the present invention, the use of a flame retardant ensures that the polyurethane foam has excellent flame retardancy, meeting the UL-94 HBF rating (burning rate <40 mm / min). From the perspective of flame retardancy efficiency, expanded graphite can be used as the flame retardant; from the perspective of overall cost, metal hydroxides can be used as the flame retardant; expanded graphite is preferred in the present invention. The present invention preferably controls the expanded graphite content within the aforementioned range, ensuring that the polyurethane foam meets the HBF rating requirement of a burning rate <40 mm / min, while also preventing the polyurethane foam from experiencing a permanent deformation rate exceeding the controlled range due to an excessively high flame retardant content.

[0107] (cross-linking agent)

[0108] In some embodiments, the polyol-containing composition further comprises a cross-linking agent.

[0109] In some embodiments, the cross-linking agent includes, but is not limited to, one or more of difunctional, trifunctional, and tetrafunctional alcohol compounds and amine compounds. Difunctional compounds include, but are not limited to, one or more of monoethanolamine, ethylene glycol, and 1,4-butanediol. Trifunctional compounds include, but are not limited to, one or more of diethanolamine, triethanolamine, glycerol, and trimethylolpropane. Tetrafunctional compounds include, but are not limited to, pentaerythritol. Since ethylene glycol has a symmetrical chemical structure and is relatively inexpensive, ethylene glycol is preferred as a cross-linking agent in terms of the toughness and cost of the foam.

[0110] In some embodiments, the mass fraction of the crosslinking agent is 2%-4% based on the total mass of the polyol as 100%. In the present invention, the crosslinking agent content is preferably controlled within the above range, so that the compression rebound performance of the polyurethane foam is not affected by too low a crosslinking agent content, and the permanent deformation rate does not exceed the range controlled by the present invention due to too high a crosslinking agent content.

[0111] (Other functional additives)

[0112] In some embodiments, the polyol-containing composition may further optionally include other functional additives, including but not limited to one or more of an anti-aging agent and a colorant.

[0113] In some embodiments, the anti-aging agent includes but is not limited to at least one of an antioxidant (such as 1010, 168, etc.), an ultraviolet absorber (such as UV531), a light stabilizer (such as UV-P), etc.

[0114] In some embodiments, based on the total mass of the polyol as 100%, the mass fraction of the antioxidant 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, and the like.

[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 modifications) is 1-4000 mPa·s (25° C.), the NCO (isocyanate group) content is 13%-48%, and the average functionality is ≥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 modifications thereof. Preferably, the isocyanate may be TDI and / or a modified MDI. Specifically, the isocyanate may include, but is not limited to, one or more of TDI-80, polyether-modified MDI, and carbodiimide-lightly modified MDI (Lupranate 227).

[0120] In some embodiments, the NCO index, i.e., 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; based on the NCO index of 1.05, the mass ratio of the isocyanate to the polyol-containing composition is calculated to be (30-140):100.

[0121] (Preparation Steps)

[0122] As described above, the preparation method of the polyurethane foam comprises: coating the raw material mixture of the polyurethane foam on the surface of the membrane material, and obtaining the polyurethane foam after reaction.

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

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

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

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

[0127] In some embodiments, the stirring speed in the mixing step can generally be 1500-3000 rpm. When nitrogen is used as a blowing agent, a polyol-containing composition without a blowing agent can be first prepared in the mixing step, and then the composition is mixed with the isocyanate under stirring conditions and nitrogen is injected simultaneously. In this case, the stirring speed can be 400-500 rpm. The nitrogen injection method can be continuous injection throughout the entire production process. There is no particular limitation on the amount of nitrogen injected, as long as a polyurethane foam having a pore area ratio of the outer surface of the skin layer and a core open porosity controlled by the present invention can be produced.

[0128] In some embodiments, the coating method can be conventional in the art, such as, but not limited to, double-film coating or single-film coating, and the coating amount can be determined based on the thickness of the polyurethane foam controlled by the present invention. When a double-film coating process is used, 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 the reaction, the polyurethane foam is formed between the upper and lower film materials. When a single-film coating process is used, the raw material mixture of the polyurethane foam is coated on the surface of the lower film material. After the reaction, the 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 method for preparing the polyurethane foam of the present invention (i.e., the polyurethane foam with a coating) includes:

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

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

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

[0133] The raw material mixture for the coating layer can be a raw material mixture for polyurethane foam that does not contain a blowing agent. The steps for mixing the raw material mixture for the polyurethane foam are as described above and will not be repeated here. Furthermore, the steps for mixing the raw material mixture for the coating layer are substantially the same as those for the polyurethane foam, except that no blowing agent is added. Furthermore, whether double-film coating or single-film coating is employed, the raw material mixture for the coating layer can be sprayed onto the surface of the lower film material, while the surface of the upper film material can be sprayed with or without the raw material mixture for the coating layer.

[0134] In some embodiments, the film material (including the upper film material and the lower film material) includes at least one of a conventional paper-based release film without silicone oil, a release film containing silicone oil, and a mirror release film. These release films can all be commercially available products. Since the mirror release film has better and more outstanding performance in terms of high transparency, excellent anti-sticking properties, and easy peeling, it is helpful for the integrity and continuity of the polyurethane foam skin layer. Therefore, it is preferred to use a mirror release film to make the skin layer of the polyurethane foam smoother and help to make the cell area ratio of 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 composition containing polyols, and combines it with the use of the above-mentioned release film, so that the skin layer of the present invention can form a hydrophobic interface, especially when using a mirror release film, a super-hydrophobic interface can be formed, which is more conducive to making the contact angle of the surface with water and the water absorption rate of the foam within the range controlled by the present invention, which can effectively prevent the penetration of water and have a good waterproof sealing effect.

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

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

[0137] According to a specific embodiment 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 controlled by the present invention having a skin layer with an outer surface pore area accounting for 30%-50% and a core with an open porosity of 80%-95%.

[0138] <Application>

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

[0140] According to a specific embodiment of the present invention, the present invention provides a battery pack, which includes at least: a box body, a battery cell module, and a filling assembly; the box body includes at least a bottom plate and an end plate, the bottom plate and the end plate enclose a cavity, and a plurality of beams are arranged in the cavity; the battery cell module is arranged in the cavity of the box body;

[0141] 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;

[0142] The filling assembly includes a packaging bag and a filling material arranged in the packaging bag;

[0143] The filling material is the polyurethane foam.

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

[0145] In some embodiments, the packaging bag has a thickness of 0.02-0.1 mm, preferably 0.05-0.1 mm. If the packaging bag is too thin, it is prone to air leakage; if it is too thick, it is detrimental to the smoothness of the foam after vacuuming. By controlling the packaging bag thickness within the above range, the present invention reduces air leakage and ensures that the foam after vacuuming has good smoothness.

[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), and the like.

[0147] In some embodiments, the filling assembly is evacuated to a vacuum level of ≤-0.1 MPa.

[0148] In some embodiments, the packaging bag is provided with an easy-tear opening, and the vacuum of the filling assembly is broken by tearing the packaging tape through the easy-tear opening.

[0149] On the one hand, the polyurethane foam of the present invention has good compression rebound performance, and thus has good vacuum performance and filling performance. The polyurethane foam of the present invention can be easily and quickly placed in the gap of the battery pack after being vacuumed, and has the advantage of simple operation. Moreover, after the vacuum is broken, the polyurethane foam of the present invention can expand rapidly and fill the gap in the battery pack, and can provide a suitable compression rebound force for a long time, so as to achieve a docile and tight filling in the gap, and prevent problems such as looseness, shaking or displacement between the components in the battery pack, while not causing excessive squeezing of the components in the battery pack. On the other hand, the polyurethane foam of the present invention also has good waterproof sealing performance, and can play the role of blocking glue, blocking glue, waterproofing, and preventing glue leakage in the battery pack.

[0150] Example

[0151] The technical solutions of the present invention are specifically described below through examples, but the present invention is not limited to these examples and can of course be implemented with various modifications within the scope of the gist of the present invention.

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

[0153] First polyol: polyether polyol CHE-306, hydroxyl value 305 mgKOH / g, average functionality 3, molecular weight 550;

[0154] Second polyol: polyether polyol CHE-1Q59, hydroxyl value 32.5 mgKOH / g, primary hydroxyl content 85%, average functionality 4.2, molecular weight 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] Foaming agent: deionized water or nitrogen;

[0157] Metal catalyst: bismuth carboxylate DABCO MB20;

[0158] Foaming catalyst: A33 (i.e., a solution of 33% triethylenediamine and 67% dipropylene glycol);

[0159] Foam stabilizer: polyether modified silicone oil DC2525;

[0160] Hydrophobic modifier: XSY-W601;

[0161] Flame retardant: expanded graphite EG-150;

[0162] Cross-linking agent: ethylene glycol, polyester grade;

[0163] Anti-aging agent: 1010;

[0164] Colorant: Extra Black ZY8069;

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

[0166] The homemade polyether-modified MDI has a viscosity of 3000±500 mPa·s (25°C), an NCO content of 13%±2%, and an average functionality of 2.1. The preparation method comprises: prepolymerizing pure MDI (MDI-100) with polyether polyol CHE-306 and polyether polyol CHED-28 in a ratio of 57:4:39 by mass in a reactor at 65-85°C under stirring for 2.5 hours to obtain the polyether-modified MDI.

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

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

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

[0170] Carbodiimide-mildly modified MDI: Lupranate 227, with a viscosity of 28 mPa·s (25°C), an NCO content of 32.1%, and an average functionality of 2.2.

[0171] Example 1

[0172] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.016 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 47 parts of isocyanate Lupranate 227, mix evenly under stirring conditions, the stirring speed is 2000 rpm, and the raw material mixture of polyurethane foam is obtained; the double-film coating process is used to coat the raw material mixture of polyurethane foam 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 polyurethane foam. The upper film material and the lower film material are both made of PET mirror release film with a thickness of 0.05mm. After reacting at 100°C for 15 minutes, polyurethane foam is formed between 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. The scanning electron microscope photo of the surface of the polyurethane foam of this embodiment is shown as follows. Figure 1 shown.

[0173] Example 2

[0174] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.015 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 are mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition are mixed with 40 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0175] Example 3

[0176] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.03 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 20 parts of expanded graphite EG-150, 2 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 51 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0177] Example 4

[0178] In parts 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 parts of deionized water, 0.05 parts of bismuth carboxylate DABCO MB20, 0.05 parts of A33, 0.5 parts of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 0.5 parts of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 42 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0179] Example 5

[0180] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.004 parts 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 anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 42 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0181] Example 6

[0182] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.034 parts of A33, 1.0 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.7 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 51 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0183] Example 7

[0184] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.04 parts of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010, and 2 parts of special black ZY8069 are mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; and 100 parts of the polyol-containing composition and 52 parts of isocyanate Lupranate 227 are mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a raw material mixture for polyurethane foam.

[0185] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.04 parts of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010, and 2 parts of special black ZY8069 are mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; and 100 parts of the polyol-containing composition and 34 parts of isocyanate Lupranate 227 are mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a raw material mixture for a coating;

[0186] The raw material mixture of the coating is sprayed on the surface of the lower film material by a sprayer to obtain a lower film material containing the coating; the thickness of the coating is about 0.1 mm;

[0187] A double-film coating process is used to coat the raw material mixture of polyurethane foam on the surface of the lower film material containing the coating, and then the upper film material is covered on the surface of the raw material mixture of polyurethane foam. The upper film material and the lower mold material both use a PET mirror release film with a thickness of 0.05 mm. After reacting at 100°C for 15 minutes, polyurethane foam is formed between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam. One surface of the polyurethane foam of this embodiment has a coating. The scanning electron microscope photograph of the surface of the polyurethane foam of this embodiment before vacuuming is as follows: Figure 2 As shown; after vacuuming, the scanning electron microscope photo of its surface is as follows Figure 3 The polyurethane foam of this embodiment is placed in a packaging bag and then vacuumed. The vacuuming time is 20 seconds. The vacuum degree in the packaging bag after vacuuming is -0.1 MPa. The thickness of a single layer of the packaging bag is 0.05 mm.

[0188] Example 8

[0189] In parts 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 parts of deionized water, 0.006 parts of bismuth carboxylate DABCO MB20, 0.004 parts of A33, 1 part of hydrophobic modifier XSY-W601, 12 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1.5 parts of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition without a blowing agent; and 100 parts of the polyol-containing composition without a blowing agent were mixed with 42 parts of isocyanate Lupranate 227. The mixture is mixed uniformly under stirring, and nitrogen is injected into the mixture as a foaming agent at a flow rate of 5-6 L / min. The stirring speed is 400-500 rpm. The nitrogen injection is continuous from the start of the machine until the end of the machine, thereby obtaining a raw material mixture for polyurethane foam. The raw material mixture for polyurethane foam is coated on the surface of a lower film material using a double-film coating process, and then an upper film material is covered on the surface of the raw material mixture for polyurethane foam. Both the upper film material and the lower film material are coated with a 0.05 mm thick PET mirror release film. After reacting at 100° C. for 15 minutes, polyurethane foam is formed between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0190] Example 9

[0191] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.016 parts 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 were mixed evenly under stirring conditions at a stirring speed of 2000 rpm to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 139 parts of homemade polyether-modified MDI were mixed evenly under stirring conditions at a stirring speed of 2000 rpm to obtain a raw material mixture of polyurethane foam; a double-film coating process was adopted to coat the raw material mixture of 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 of polyurethane foam, and the upper film material and the lower mold material both used a PET mirror release film with a thickness of 0.05 mm. After reacting at 100°C for 15 minutes, polyurethane foam was formed between the upper and lower film materials. 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] In parts 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 parts of deionized water, 0.024 parts of bismuth carboxylate DABCO MB20, 0.016 parts 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 were mixed uniformly under stirring conditions at a stirring speed of 2000 rpm to obtain a polyol-containing composition; then 100 parts of the polyol-containing composition and 36 parts of isocyanate TDI-80 were mixed uniformly under stirring conditions at a stirring speed of 2000 rpm to obtain a raw material mixture of polyurethane foam; a double-film coating process was adopted to coat the raw material mixture of polyurethane foam on the surface of a lower film material, and then an upper film material was covered on the surface of the raw material mixture of polyurethane foam, and both the upper film material and the lower mold material used a PET mirror release film with a thickness of 0.05 mm. After reacting at 100°C for 15 minutes, a polyurethane foam was formed between the upper and lower film materials. 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] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.016 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 34 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0196] Comparative Example 2

[0197] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.016 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 61 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0198] Comparative Example 3

[0199] In parts 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 parts of deionized water, 0.06 parts of bismuth carboxylate DABCO MB20, 0.04 parts of A33, 1.5 parts of hydrophobic modifier XSY-W601, 15 parts of expanded graphite EG-150, 3 parts of ethylene glycol, 0.4 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 40 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0200] Comparative Example 4

[0201] In parts 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 parts of bismuth carboxylate DABCO MB20, 0.04 parts 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 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 55 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

[0202] Comparative Example 5

[0203] In parts 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 parts of deionized water, 0.006 parts of bismuth carboxylate DABCO MB20, 0.003 parts 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 parts of foam stabilizer DC2525, 1 part of anti-aging agent 1010 and 2 parts of special black ZY8069 were mixed uniformly under stirring at a stirring speed of 2000 rpm to obtain a polyol-containing composition; 100 parts of the polyol-containing composition were then mixed with 36 parts of isocyanate Lupranate 227, mixing uniformly under stirring at a speed of 2000 rpm to obtain a raw material mixture for polyurethane foam; using a double-film coating process, coating the raw material mixture for polyurethane foam on the surface of a lower film material, and then covering the surface of the raw material mixture for polyurethane foam with an upper film material, both the upper film material and the lower film material using a 0.05 mm thick PET mirror release film, reacting at 100° C. for 15 minutes, forming polyurethane foam between the upper and lower film materials. After the reaction is completed, the upper and lower film materials are peeled off to obtain polyurethane foam.

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

[0205] The polyurethane foam was evaluated according to the following criteria, and the evaluation results are shown in Tables 1 and 2:

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

[0207] Filling performance: If the time required for the thickness recovery rate to reach 60% is 5-20 minutes, and the time required for the thickness recovery rate to reach 95% is 1 hour-12 hours, it is qualified; if the time required for the thickness recovery rate to reach 60% or the time required for the thickness recovery rate to reach 95% is outside the above range, it is unqualified.

[0208] Waterproof sealing performance: If the contact angle between the surface with the epidermis and water is greater than 105° and the water absorption rate is less than 10%, it is qualified; if the contact angle between the surface with the epidermis and water or the water absorption rate is not within the above range, it is unqualified.

[0209] Table 1 Characteristics of the embodiment

[0210]

[0211] Table 2 Characteristics of comparative examples

[0212]

[0213] It can be seen from Table 1 and Table 2 that the pore area ratio of the outer surface of the skin layer and / or the core open porosity of the polyurethane foam provided in Comparative Examples 1-5 are outside the scope of the present invention. These polyurethane foams cannot have both good vacuum performance and filling performance, as well as good waterproof and sealing performance.

[0214] The polyurethane foam provided in Examples 1-10 of the present invention has good compression and rebound properties, and can be easily placed in the gap of the battery pack after being evacuated, and can be tightly and compactly filled in the gap of the battery pack after the vacuum is broken, without causing excessive squeezing of the components in the battery pack, and has good vacuum evacuation and filling properties; on the other hand, it has good waterproof and sealing properties, and can play the role of blocking glue, plugging glue, waterproofing, and preventing glue leakage in the battery pack.

[0215] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A polyurethane foam, comprising a surface and a core within the surface, wherein at least a portion of the surface comprises a skin layer, the cell area of ​​the outer surface of the skin layer accounts for 30%-50%, and the open porosity of the core is 80%-95%; The raw material mixture of the polyurethane foam includes a composition containing a polyol and an isocyanate; the composition containing a polyol includes at least a polyol, a blowing agent, a catalyst, and a hydrophobic modifier; based on the total mass of the polyol being 100%, the mass fraction of the hydrophobic modifier is 0.5%-2.5%; The polyol comprises a combination of a first polyol, a second polyol and a third polyol, wherein the first polyol comprises a polyol having a hydroxyl value of 220-470 mgKOH / g and an average functionality of ≥3, the second polyol comprises a polyol having a hydroxyl value of 24-56 mgKOH / g and an average functionality of 3-6, and the third polyol comprises a polyol having a hydroxyl value of 17-37 mgKOH / g and an average functionality of ≥3, and the mass ratio of the first polyol, the second polyol and the third polyol is (0.5-2):1:1; The hydrophobic modifier includes one or more of acrylic compounds, organosilicon compounds and organofluorine compounds.

2. The polyurethane foam according to claim 1, wherein The contact angle between the surface of the polyurethane foam having the skin layer and water is greater than 105°.

3. The polyurethane foam according to claim 1, wherein The water absorption rate of the polyurethane foam is less than 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 being compressed 10,000 times at 50% is ≤10%.

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

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

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

12. A battery pack, comprising at least: A box body, a battery cell module, and a filling assembly; the box body includes at least a bottom plate and an end plate, the bottom plate and the end plate enclose a cavity, and a plurality of beams are arranged in the cavity; the battery cell module is arranged in the cavity 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 to 11.

13. A method for filling a gap in a battery pack, comprising the following steps: Place the polyurethane foam described in any one of claims 1-11 in a packaging bag to obtain a filling component; evacuate the filling component; then place the vacuumed filling component in the gap of the battery pack; then break the vacuum of the filling component to fill the gap.

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