A polyurethane foam and a method for producing the same

Abstract

The application provides a polyurethane foam and a preparation method thereof. The raw materials for preparing the polyurethane foam include 70-85wt% of a polyol component and 15-30wt% of an isocyanate component according to percentage by weight; the polyol component includes polyether polyol, chain extender, surfactant, catalyst and additive; and the additive includes nano carbon powder. The polyurethane foam provided by the application contains nano carbon powder, and the nano material provides finer nucleation points to make the cells finer, and the black filler can also improve the light leakage property; in addition, the polyurethane foam has a better density range, compression strength and cohesive strength.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and relates to a foam, in particular to a polyurethane foam and a preparation method thereof. BACKGROUND

[0002] In the 3C consumer electronics, household appliances and other industries, products are increasingly inclined to be light, thin and delicate, and users are increasingly pursuing the appearance and design of products, and products are updated faster and faster, and the combination and assembly of various parts, disassembly and maintenance have higher requirements. For electronic screens, it is required to be able to be disassembled and assembled without damage, and the reusable adhesive tape is used to achieve the effect of bonding and repeated disassembly without leaving marks.

[0003] Polyurethane foam has good buffering, shock-absorbing and energy-absorbing characteristics, and is widely used in electronic products, especially on the screens of electronic products. However, the traditional polyurethane foam adhesive tape has the disadvantage of being not removable after being pasted. Due to the strong adhesion, foam or adhesive layer will be left during removal, making it difficult to rework. In addition, during the cleaning process, the foam debris can easily contaminate the pasted object. Ordinary polyurethane foam is hard in quality, which can also cause water ripples on the screen during use. Since the current display screens are frameless or have ultra-thin frames, the width of the adhesive tape used is also very narrow, about 2 mm or less, and the too large pores of the polyurethane foam can cause light leakage.

[0004] CN 113652177A discloses a PU foam double-sided adhesive tape and a preparation method thereof. The PU foam double-sided adhesive tape comprises, from top to bottom, a 10-100 μm pressure-sensitive adhesive layer, a 1050 μm reinforcing layer, a 10-60 μm pressure-sensitive adhesive layer, a 100-2000 μm PU foam layer, a 10-100 μm pressure-sensitive adhesive layer, and a 25-100 μm release layer. The reinforcing layer is made of any one of TPU and thermoplastic elastomer. The PU foam layer is a 50-95% foaming layer with an internal closed cell structure formed by foaming polyester or polyether polyurethane on a PET black film. The release layer is made of double-sided release film or double-silicon release paper. The double-sided adhesive tape provided by the patent has good stress buffering performance, reworkability, adhesion and high temperature retention, but the double-sided adhesive tape cannot solve the problem of light leakage of the foam adhesive tape.

[0005] CN 109575213A discloses a dry process foaming polyurethane resin prepared from polyol, chain extender, diphenyl methane diisocyanate and N-dimethyl formamide. The dry process foaming polyurethane resin preparation method provided by the patent includes two kinds, wherein the "one-step method" is to directly mix the preparation raw materials for viscosity increase and dilution, and the dry process foaming polyurethane resin of the patent can be obtained by controlling the proportion of raw materials and the viscosity and solid content of the final system; the "two-step method" is to first make the diphenyl methane diisocyanate and the polyol pre-polymerize to obtain a prepolymer, and then obtain the dry process foaming polyurethane resin of the patent through chain extension. The foaming polyurethane resin obtained by dry process foaming has coarse and uneven cell, small number of cells and poor economic benefit. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a polyurethane foam and a preparation method thereof. The composition of the polyurethane foam contains nano carbon powder. The nano material provides finer nucleation points to make the cells finer, and the black filler can also improve the light leakage. In addition, it also has a better density range, compression strength and cohesive strength.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In the first aspect, the present application provides a polyurethane foam. The preparation raw materials of the polyurethane foam include a polyol component 70-85wt% and an isocyanate component 15-30wt% by weight percentage.

[0009] The polyol component includes polyether polyol, chain extender, surfactant, catalyst and additive.

[0010] The additive includes nano carbon powder.

[0011] The preparation raw materials of the polyurethane foam provided by the present application contain nano carbon powder. The nano material provides finer nucleation points to make the cells finer, and the black filler can also improve the light leakage.

[0012] For example, the content of the polyol component in the polyurethane foam of the present application is 70-85wt%, which can be 70%, 75%, 80% or 85%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0013] The content of the isocyanate component is 15-30wt%, which can be 15%, 20%, 25%, 30% or 35%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0014] The polyol component content in the polyurethane foam is 70-85 wt%, and the isocyanate component content is 15-30 wt%. The polyol component is used to form the soft segment of the polyurethane foam, and too high content will result in too low foam strength, and too low content will result in too high foam strength. The isocyanate component is used to form the hard segment of the polyurethane foam, and too high content will result in too high foam strength, and too low content will result in too low foam strength.

[0015] Preferably, the molecular mass of the polyol component is 300-6000 kg / mol, for example, it can be 300 kg / mol, 1000 kg / mol, 3000 kg / mol, 5000 kg / mol, or 6000 kg / mol, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0016] Preferably, the polyether polyol includes any one or a combination of at least two of polytetrahydrofuran polyether polyol, polypropylene oxide polyether polyol, or polyethylene oxide polyether polyol, and a typical but non-limiting combination includes a combination of polytetrahydrofuran polyether polyol and polypropylene oxide polyether polyol, a combination of polypropylene oxide polyether polyol and polyethylene oxide polyether polyol, a combination of polytetrahydrofuran polyether polyol and polyethylene oxide polyether polyol, or a combination of polytetrahydrofuran polyether polyol, polypropylene oxide polyether polyol, and polyethylene oxide polyether polyol.

[0017] Preferably, the mass ratio of the polyether polyol, the chain extender, the surfactant, the catalyst, and the additive is (70-85):(1-6):(2-10):(0.5-3):(5-30), for example, it can be 70:5:5:2.5:17.5, 80:6:2:0.5:11.5, 85:1:8:1:5, or 70:6:10:3:11, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0018] Preferably, the chain extender includes butanediol and / or dipropylene glycol.

[0019] Preferably, the surfactant includes polyorganosiloxane.

[0020] Preferably, the catalyst includes a metal nickel-based catalyst.

[0021] Preferably, the average particle size of the additive is 50-200 nm, for example, it can be 50 nm, 100 nm, 150 nm, or 200 nm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0022] Preferably, the NCO% content of the isocyanate component is 18-33.5%, for example, it can be 18%, 20%, 22%, 24%, 26%, 28%, 30% or 33.5%, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0023] Preferably, the isocyanate component comprises MDI prepolymers and / or PMDI.

[0024] Preferably, the density of the polyurethane foam is 180-300 g / L, for example, it can be 180 g / L, 220 g / L, 260 g / L or 300 g / L, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0025] Preferably, the compressive strength of the polyurethane foam at 25% compression ratio is 3-10 kPa, for example, it can be 3 kPa, 5 kPa, 7 kPa or 10 kPa, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0026] Preferably, the cohesive strength of the polyurethane foam is ≥ 6 N / inch, for example, it can be 6 N / inch, 8 N / inch, 10 N / inch, 12 N / inch, 14 N / inch, 16 N / inch or 18 N / inch, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0027] In a second aspect, the present application provides a method for preparing the polyurethane foam as described in the first aspect, the method comprising the following steps:

[0028] (1) mixing polyether polyol, chain extender, surfactant, catalyst and additives in the formula amount to obtain a polyol component;

[0029] (2) mixing the isocyanate component and the polyol component obtained in step (1) in the formula amount, then introducing inert gas for mechanical foaming, coating and curing to obtain the polyurethane foam.

[0030] Preferably, the mixing time in step (1) is 15-30 min, for example, it can be 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0031] Preferably, the mechanical foaming time in step (2) is 0.5-1 min, for example, it can be 0.5 min, 0.6 min, 0.7 min, 0.8 min, 0.9 min or 1 min, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0032] Preferably, the inert gas in step (2) comprises any one or a combination of at least two of nitrogen, helium, argon or neon, typically but not limited to a combination of nitrogen and helium, nitrogen and argon, nitrogen and neon, or helium, argon and neon.

[0033] Preferably, the flow rate of the inert gas in step (2) is 100-1000 cc / min, for example, it can be 100 cc / min, 300 cc / min, 500 cc / min, 700 cc / min or 1000 cc / min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0034] The present application adopts mechanical foaming, compared with the existing chemical foaming, the cell is more delicate and controllable, and the light leakage of the polyurethane foam is better. The mechanical foaming of the present application is that the isocyanate component and the polyol component are mixed

[0035] In the mechanical foaming process, the flow rate of the gas is 100-1000 cc / min, and too high flow rate will result in low foam density, and too low flow rate will result in high foam density.

[0036] The numerical range of the present application not only includes the above-mentioned point values, but also includes any point values between the above-mentioned numerical ranges which are not listed. Due to the limited space and for the sake of simplicity, the present application does not exhaustively list the specific point values included in the range.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] (1) The compression strength of the polyurethane foam provided by the present application is as low as 3 kPa at a 25% compression ratio, and does not exceed 10 kPa, which ensures good cushioning effect and prevents water ripples on the screen;

[0039] (2) The cohesive strength of the polyurethane foam provided by the present application is above 6 N / inch, which ensures that the polyurethane foam tape will not be damaged by cohesion when it is peeled off, and the foam will not be left on the adherend;

[0040] (3) The average cell size of the polyurethane foam provided by the present application can be reduced to 100-150 um, the cell is more delicate, and the nano-carbon powder is black, which further improves the light leakage of the polyurethane foam;

[0041] (4) The density of the polyurethane foam provided by the present application can be as low as 180 g / L, which reduces the weight of the tape, while ensuring appropriate compression strength and high cohesive strength;

[0042] (5) The present application adopts a mechanical foaming form, compared with the existing chemical foaming, the cell is more delicate and controllable, and the light leakage of the polyurethane foam is better. DETAILED DESCRIPTION

[0043] The technical solutions of the present application are further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0044] Embodiment 1

[0045] The present embodiment provides a polyurethane foam, the preparation raw materials of the polyurethane foam include a polyol component 80wt% and an isocyanate component 20wt% by weight percentage;

[0046] The polyol component includes a polyether polyol, a chain extender, a surfactant, a catalyst and a nano carbon powder with an average particle size of 100nm; the molecular mass of the polyol component is 3000kg / mol.

[0047] The mass ratio of the polyether polyol, the chain extender, the surfactant, the catalyst and the nano carbon powder is 70:5:5:1.5:17.5.

[0048] The chain extender includes butanediol; the surfactant includes polyorganosiloxane; and the catalyst includes a metal nickel catalyst.

[0049] The NCO% content of the isocyanate component is 28.5%; the isocyanate component includes MDI prepolymer and PMDI.

[0050] The preparation method of the polyurethane foam includes the following steps:

[0051] (1) mixing the polyether polyol, the chain extender, the surfactant, the catalyst and the additive according to the formula amount, and obtaining the polyol component after 20min;

[0052] (2) mixing the isocyanate component and the polyol component obtained in step (1) according to the formula amount, then introducing inert gas with a flow rate of 500cc / min for mechanical foaming, coating, curing to obtain the polyurethane foam.

[0053] Embodiment 2

[0054] The present embodiment provides a polyurethane foam, the preparation raw materials of the polyurethane foam include a polyol component 85wt% and an isocyanate component 15wt% by weight percentage;

[0055] The polyol component includes polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder with an average particle size of 200 nm; the molecular mass of the polyol component is 6000 kg / mol.

[0056] The mass ratio of the polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder is 70:6:2:0.5:21.5.

[0057] The chain extender includes butanediol and dipropylene glycol; the surfactant includes polyorganosiloxane; the catalyst includes metal nickel catalyst.

[0058] The NCO% content of the isocyanate component is 25.5%; the isocyanate component includes MDI prepolymer.

[0059] The preparation method of the polyurethane foam includes the following steps:

[0060] (1) mixing polyether polyol, chain extender, surfactant, catalyst and additives according to the formulation amount, and obtaining polyol component after 30 min;

[0061] (2) mixing isocyanate component and the polyol component obtained in step (1) according to the formulation amount, then introducing inert gas with a flow rate of 1000 cc / min for mechanical foaming, and obtaining the polyurethane foam after coating and curing.

[0062] Example 3

[0063] The present embodiment provides a polyurethane foam, the preparation raw material of the polyurethane foam includes polyol component 70wt% and isocyanate component 30wt% according to the percentage by weight;

[0064] The polyol component includes polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder with an average particle size of 50 nm; the molecular mass of the polyol component is 5200 kg / mol.

[0065] The mass ratio of the polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder is 72:1:10:3:14.

[0066] The chain extender includes butanediol and / or dipropylene glycol; the surfactant includes polyorganosiloxane; the catalyst includes metal nickel catalyst.

[0067] The NCO% content of the isocyanate component is 18-33.5%; the isocyanate component includes MDI prepolymer and / or PMDI.

[0068] The preparation method of the polyurethane foam includes the following steps:

[0069] (1) mixing polyether polyol, chain extender, surfactant, catalyst and additive according to the formula, and obtaining polyol component after 15-30 min;

[0070] (2) mixing isocyanate component and polyol component obtained in step (1) according to the formula, then performing mechanical foaming by introducing inert gas at a flow rate of 100-1000 cc / min, and obtaining the polyurethane foam after coating and curing.

[0071] Example 4

[0072] This example provides a polyurethane foam, which is identical to Example 1 except that the average particle size of the nano-carbon powder is changed to 20 nm.

[0073] The preparation method of the polyurethane foam is identical to Example 1.

[0074] Example 5

[0075] This example provides a polyurethane foam, which is identical to Example 1 except that the average particle size of the nano-carbon powder is changed to 220 nm.

[0076] The preparation method of the polyurethane foam is identical to Example 1.

[0077] Example 6

[0078] This example provides a polyurethane foam, which is identical to Example 1 except that the mass ratio of the polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder is changed to 60:5:5:5:25.

[0079] The preparation method of the polyurethane foam is identical to Example 1.

[0080] Example 7

[0081] This example provides a polyurethane foam, which is identical to Example 1 except that the mass ratio of the polyether polyol, chain extender, surfactant, catalyst and nano-carbon powder is changed to 50:5:5:5:35.

[0082] The preparation method of the polyurethane foam is identical to Example 1.

[0083] Example 8

[0084] This example provides a polyurethane foam, which is identical to Example 1.

[0085] The preparation method of the polyurethane foam is identical to Example 1 except that:

[0086] This example changes the mechanical foaming described in step (2) to chemical foaming.

[0087] Comparative Example 1

[0088] This comparative example provides a polyurethane foam, which is only different from Example 1 in that this comparative example changes the content of the polyol component to 60% and the content of the isocyanate to 40%.

[0089] The preparation method of the polyurethane foam is the same as that of Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a polyurethane foam, which is only different from Example 1 in that this comparative example changes the content of the polyol component to 90% and the content of the isocyanate to 10%.

[0092] The preparation method of the polyurethane foam is the same as that of Example 1.

[0093] Comparative Example 3

[0094] This comparative example provides a polyurethane foam, which is only different from Example 1 in that this comparative example omits the nano-carbon powder and changes the nano-carbon powder to the same mass of polyether polyol.

[0095] The preparation method of the polyurethane foam is the same as that of Example 1.

[0096] Performance Test:

[0097] The polyurethane foams provided in Examples 1-8 and Comparative Examples 1-3 are subjected to performance tests, and the test items include density, compression strength at 25% compression ratio, and cohesive strength, and the results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] From Table 1, it can be seen that the polyurethane foams provided by Examples 1-3 have lower compressive strength and higher cohesive strength in the density range, and the mechanical properties and light leakage properties meet the requirements; the polyurethane foam of Example 4 shrinks due to the increase in closed cell rate caused by the too small particle size of the nano-carbon powder; the polyurethane foam of Example 5 has larger cells due to the too large particle size of the nano-carbon powder, and occasionally has light leakage points; the polyurethane foam of Example 6 has a higher compressive strength of more than 10 kPa due to the lower content of polyether polyol, which has a risk of causing screen cracking; the polyurethane foam of Example 7 has a very high compressive strength due to the lower content of polyether polyol and the higher content of isocyanate, which has a higher probability of causing screen cracking; the polyurethane foam of Example 8 is foamed by chemical foaming, has larger cells, has more light leakage points, and the process is more difficult to control. The polyurethane foam of Comparative Example 1 has a very high compressive strength due to the lower content of polyol component and the higher content of isocyanate, which is easy to cause screen cracking; the polyurethane foam of Comparative Example 2 has a lower compressive strength due to the higher content of polyol component and the lower content of isocyanate, which has a weaker cushioning effect; the polyurethane foam of Comparative Example 3 does not use nano-carbon powder, although the compressive strength and cohesive strength are suitable, but due to the larger cells, the light leakage property is poor.

[0102] In summary, the polyurethane foam provided by the present application has a composition containing nano-carbon powder, which provides finer nucleation points for finer cells, and the black filler also improves the light leakage property; in addition, it also has a better density range, compressive strength and cohesive strength.

[0103] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above-described specific embodiments are only specific embodiments of the present application and are not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A polyurethane foam characterized by, The raw materials for preparing the polyurethane foam include a polyol component 70-85 wt% and an isocyanate component 15-30 wt% by weight percentage; The polyol component includes a polyether polyol, a chain extender, a surfactant, a catalyst and an additive; the mass ratio of the polyether polyol, the chain extender, the surfactant, the catalyst and the additive is (70-85):(1-6):(2-10):(0.5-3):(5-30); the chain extender includes butanediol and / or dipropylene glycol; the NCO% content of the isocyanate component is 18-33.5%; The additive includes nano carbon powder; the average particle size of the additive is 50-200 nm; The compression strength of the polyurethane foam under a 25% compression ratio is 3-10 kPa; the cohesive strength of the polyurethane foam is ≥6 N / inch; The polyurethane foam is prepared by mechanical foaming.

2. The polyurethane foam according to claim 1, characterized in that, The polyether polyol includes any one or a combination of at least two of polytetrahydrofuran polyether polyol, polypropylene oxide polyether polyol or polyethylene oxide polyether polyol.

3. The polyurethane foam according to claim 1, characterized in that, The surfactant includes polyorganosiloxane.

4. The polyurethane foam according to claim 1, characterized in that, The catalyst includes a metal nickel catalyst.

5. The polyurethane foam according to claim 1, wherein, The isocyanate component includes MDI prepolymer and / or PMDI.

6. The polyurethane foam according to claim 1, wherein, The density of the polyurethane foam is 180-300 g / L.

7. A process for the preparation of the polyurethane foam according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: (1) mixing the polyether polyol, the chain extender, the surfactant, the catalyst and the additive according to the formula amount to obtain a polyol component; (2) mixing the isocyanate component and the polyol component obtained in step (1) according to the formula amount, then introducing inert gas for mechanical foaming, coating, curing to obtain the polyurethane foam.

8. The preparation method according to claim 7, characterized in that, The mixing time in step (1) is 15-30 min.

9. The preparation method according to claim 7, characterized in that, The mechanical foaming time in step (2) is 0.5-1 min.

10. The preparation method according to claim 7, characterized in that, The inert gas in step (2) includes any one or a combination of at least two of nitrogen, helium, argon or neon.

11. The preparation method according to claim 7, characterized in that, The flow rate of the inert gas in step (2) is 100-1000 cc / min.

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