Halogen-free flame-retardant foam and preparation method thereof

Abstract

The application provides a halogen-free flame-retardant foam and a preparation method thereof, and relates to the technical field of flame-retardant foam.The preparation method of the halogen-free flame-retardant foam comprises the following steps: uniformly mixing polyether polyol, a catalyst, a chain extender, a cell regulator, a halogen-free flame retardant and a filler to obtain a premix, mixing the premix with modified MDI to obtain a mixture; coating the mixture on a release film to obtain a film material, and performing heating foaming treatment and curing treatment on the film material to obtain the halogen-free flame-retardant foam; the modified MDI is polyethylene glycol polyol modified diphenyl methane diisocyanate, and the content of NCO in the modified MDI is 18%-24%.The halogen-free flame-retardant foam prepared by the method has the slow rebound characteristic, good structural uniformity and excellent flame-retardant performance.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant foam technology, and in particular to a halogen-free flame-retardant foam and its preparation method. Background Technology

[0002] Polyurethane foam is a material obtained by reacting isocyanates and polyols, and it has a wide range of applications in daily life and industry. Because polyurethane is an organic synthetic material, its molecules contain a large amount of carbon and hydrogen elements, making polyurethane foam a flammable material. Currently, most flame retardants on the market are halophosphate compounds, which produce toxic gases after combustion, posing a significant threat to the environment and human health, and are prohibited by domestic and international environmental standards.

[0003] With the rapid development of new energy vehicles and their increasing sales, the demand for polyurethane foam, as an auxiliary component of power batteries in new energy vehicles, is also expanding. Currently, most polyurethane foam products used in this field are supplied by foreign companies and have relatively superior performance. Although a few domestic manufacturers have the capability to develop such products, their flame-retardant polyurethane foams often fail to meet the UL94 V-0 rating; other companies are mostly agents for products from foreign companies such as Rogers and Inoue. Therefore, there is an urgent need to develop new flame-retardant polyurethane foam materials. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a halogen-free flame-retardant foam and its preparation method.

[0005] The present invention proposes a method for preparing halogen-free flame-retardant foam, comprising the following steps: mixing polyether polyol, catalyst, chain extender, foam leveling agent, halogen-free flame retardant, and filler evenly to obtain a premix; mixing the premix with modified MDI to obtain a mixture; coating the mixture onto a release film to obtain a film material; subjecting the film material to heating foaming treatment and curing treatment to obtain halogen-free flame-retardant foam; wherein the modified MDI is polyethylene glycol polyol modified diphenylmethane diisocyanate (MDI), and the NCO content in the modified MDI is 18%-24%.

[0006] Preferably, the polyether polyol is selected from one or more of polypropylene glycol, polypropylene triol, and polyethylene glycol.

[0007] Preferably, the catalyst is selected from one or more of tin-based catalysts and antimony-based catalysts.

[0008] More preferably, the tin catalyst is selected from one or more of dibutyltin dilaurate, stannous octoate, and stannous isooctanoate; the antimony catalyst is selected from one or more of antimony trioxide and antimony glycol.

[0009] Preferably, the chain extender is selected from one or more of 1,4-butanediol, ethylene glycol, and diethyltoluenediamine.

[0010] Preferably, the foam leveling agent is selected from one or more of polyether-modified silicone oil and silicone-boron composite silicone oil.

[0011] Preferably, the halogen-free flame retardant is selected from one or more of a mixture of phosphate esters and dimethyl methylphosphonate.

[0012] Preferably, the filler is selected from one or more of expanded graphite and aluminum hydroxide.

[0013] More preferably, the expanded graphite has a particle size of 60-100 mesh, and the aluminum hydroxide has a particle size of 1000-2000 mesh.

[0014] Preferably, the mass ratio of the polyether polyol, catalyst, chain extender, foam stabilizer, halogen-free flame retardant, and filler is 100:0.01-2:5-20:5-10:10-30:50-60.

[0015] Preferably, the mass ratio of the premix to the modified MDI is 3-4:2-3.

[0016] More preferably, the mass ratio of the premix to the modified MDI is 4:2-3.

[0017] Preferably, the release film is a transparent single-sided silicone-coated polyester film, the release force of the release film is 5-8 g / inch, and the thickness of the release film is 40-60 μm.

[0018] Preferably, the release film has a tensile strength ≥150MPa, an elongation at break ≥100%, and a heat shrinkage rate ≤1.5%.

[0019] Preferably, the coating method is blade coating.

[0020] Preferably, the heating and foaming process includes passing the membrane material through a gradient temperature zone at a speed of 10-15 m / min.

[0021] More preferably, the gradient temperature zone is divided into 5 segments, with temperatures of 120-130℃, 130-140℃, 140-150℃, 140-150℃, and 130-140℃ respectively.

[0022] Preferably, the heating and foaming treatment time is 2-4 minutes.

[0023] Preferably, the aging process is carried out at a temperature of 30-45°C for 12-36 hours.

[0024] A halogen-free flame-retardant foam is prepared by the above-described method.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention uses polyether polyol and modified MDI as the main raw materials, and mixes chain extender, catalyst, foam stabilizer, aluminum hydroxide powder and expanded graphite to make foam. A one-step foaming process was used to successfully prepare polyurethane foam material with excellent flame retardant effect, which can meet the UL94-V0 standard. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail through specific embodiments.

[0028] In the following embodiments, the specific information regarding the raw materials used is as follows:

[0029] Release film: Release film with a residual rate of ≥90% produced by Anhui Fuyin New Materials, 50μm single-sided silicone-coated release PET material, with a release force of 6g / inch.

[0030] Expanded graphite: Manufacturer: Hebei Aoteng Trading Co., Ltd., Grade: ADT802.

[0031] Polyether polyol: Manufacturer: Yinuowei, Brand: C220, Molecular weight 2000.

[0032] Polyether polyol mixture: Manufacturer: Zhangjiagang Shoubo Electronics, Grade: A720.

[0033] Polyether modified silicone oil: Manufacturer: Zhangjiagang Shoubo Electronics, Grade: G70.

[0034] Silicon-boron composite silicone oil: Manufacturer: Zhangjiagang Shoubo Electronics, Grade: G25.

[0035] Modified MDI: Manufacturer: Zhangjiagang Shoubo Electronics; Grade: M1966; Parameters include: Viscosity: 900 ± 150 CPS (25℃), Specific Gravity: 1.3 g / cm³ 3 (25℃).

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] Example 1

[0038] A method for preparing halogen-free flame-retardant foam includes the following steps: mixing 100 parts of polyether polyol, 10 parts of chain extender ethylene glycol, 7 parts of foam leveling agent (a mixture of polyether-modified silicone oil and silicone-boron composite silicone oil at a mass ratio of 1:3), 0.04 parts of catalyst dibutyltin dilaurate, 18 parts of halogen-free flame retardant (Wansheng WSFR-F68 phosphate ester mixture), 35 parts of aluminum hydroxide (particle size of 1200 mesh), and 23 parts of expanded graphite (particle size of 80 mesh) at 650 rpm to obtain a premix; mixing the premix with modified MDI (Zhangjiagang Shoubo MDI)... (1966) The mixture was prepared by mixing materials at a mass ratio of 2:1. The mixture was then coated onto a release film at a release film thickness of 6 g / inch to obtain a film material. The film material was then conveyed into an oven with a set temperature gradient: 130-140-150-150-140℃, with a total length of 20m and a constant speed of 10m / min. The baking time was 120 seconds. After exiting the oven, the film was wound up to obtain a finished product. The roll was then cured at 40℃ for 24 hours to ensure a stable shape after foam formation, resulting in halogen-free flame-retardant foam with a thickness of 3mm.

[0039] Example 2

[0040] A method for preparing halogen-free flame-retardant foam includes the following steps: mixing 100 parts of polyether polyol (Yinuowei, brand C220), 10 parts of chain extender ethylene glycol, 7 parts of foam leveling agent (mixed from polyether-modified silicone oil and silicone-boron composite silicone oil at a mass ratio of 1:3), 0.04 parts of catalyst dibutyltin dilaurate, 20 parts of halogen-free flame retardant (Wansheng WSFR-F68 phosphate ester mixture), 30 parts of aluminum hydroxide (particle size of 1200 mesh), and 23 parts of expanded graphite (particle size of 80 mesh) at 650 rpm to obtain a premix; mixing the premix with modified MDI ( Zhangjiagang Shoubo M1966) was mixed at a mass ratio of 2:1 to obtain a mixture; the mixture was coated on the surface of a release film of 6g / inch to obtain a film material; the film material was then conveyed into an oven with a set temperature gradient: 130-140-150-150-140℃, total length 20m, constant speed 10m / min, baking time 120 seconds; after exiting the oven, it was rolled up to obtain a finished rolled product; the roll was cured at 40℃ for 24h to ensure the stable shape after foam formation, resulting in halogen-free flame-retardant foam with a thickness of 3mm.

[0041] Example 3

[0042] A method for preparing halogen-free flame-retardant foam includes the following steps: mixing 100 parts of a polyether polyol mixture (Zhangjiagang Shoubo Electronics, brand A720), 5 parts of a chain extender ethylene glycol, 7 parts of a foam leveling agent (a mixture of polyether-modified silicone oil and silicon-boron composite silicone oil at a mass ratio of 5:2), 0.05 parts of a catalyst dibutyltin dilaurate, 18 parts of a halogen-free flame retardant (Wansheng WSFR-F68 phosphate ester mixture), 35 parts of aluminum hydroxide (particle size of 1200 mesh), and 23 parts of expanded graphite (particle size of 80 mesh) at 650 rpm to obtain a premix; and mixing the premix with modified MDI. (Zhangjiagang Shoubo Electronics M2382) Mixed at a mass ratio of 1:0.68 to obtain a mixture; the mixture is coated on a release film surface of 6g / inch to obtain a film material; the film material is conveyed into an oven with a set temperature gradient: 130-140-150-150-140℃, total length 20m, constant speed 10m / min, baking time 120 seconds; after exiting the oven, it is wound up to obtain a finished product; the roll is cured at 40℃ for 24h to ensure the stable shape after foam formation, resulting in halogen-free flame-retardant foam with a thickness of 3mm.

[0043] Example 4

[0044] A method for preparing halogen-free flame-retardant foam includes the following steps: mixing 100 parts of a polyether polyol mixture (Zhangjiagang Shoubo Electronics, brand A720), 5 parts of a chain extender ethylene glycol, 7 parts of a foam leveling agent (a mixture of polyether-modified silicone oil and silicon-boron composite silicone oil at a mass ratio of 5:2), 0.05 parts of a catalyst dibutyltin dilaurate, 10 parts of a halogen-free flame retardant (Wansheng WSFR-F68 phosphate ester mixture), 30 parts of aluminum hydroxide (particle size of 1200 mesh), and 25 parts of expanded graphite (particle size of 80 mesh) at 650 rpm to obtain a premix; and mixing the premix with modified MDI. (Zhangjiagang Shoubo Electronics M2382) Mixed at a mass ratio of 1:0.68 to obtain a mixture; the mixture is coated on a release film surface of 6g / inch to obtain a film material; the film material is conveyed into an oven with a set temperature gradient: 130-140-150-150-140℃, total length 20m, constant speed 10m / min, baking time 120 seconds; after exiting the oven, it is wound up to obtain a finished product; the roll is cured at 40℃ for 24h to ensure the stable shape after foam formation, resulting in halogen-free flame-retardant foam with a thickness of 3mm.

[0045] The halogen-free flame-retardant foam prepared above was stripped of its release film, and its apparent density was tested according to GB / T 6343-2009, its 50% permanent compression loss was tested according to GB / T 6669-2008, its 25% compression rebound strength was tested according to GB / T 20467-2006, and its flame retardancy rating was tested according to UL94 standard. The test results are shown in Table 1.

[0046] Table 1

[0047]

[0048] As can be seen from the data in Table 1, the halogen-free flame-retardant foam prepared by this invention exhibits slow rebound characteristics, good structural uniformity, and excellent flame-retardant properties. This provides important reference value for its industrial application in electronic components, new energy batteries, and 3C products.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing halogen-free flame-retardant foam, characterized in that, The process includes the following steps: mixing polyether polyol, catalyst, chain extender, foam leveling agent, halogen-free flame retardant, and filler evenly to obtain a premix; mixing the premix with modified MDI to obtain a mixture; coating the mixture onto a release film to obtain a film material; subjecting the film material to heat foaming treatment and curing treatment to obtain halogen-free flame retardant foam; wherein the modified MDI is polyethylene glycol polyol modified diphenylmethane diisocyanate, and the NCO content in the modified MDI is 18%-24%.

2. The preparation method according to claim 1, characterized in that, The polyether polyol is selected from one or more of polypropylene glycol, polypropylene triol, and polyethylene glycol.

3. The preparation method according to claim 1, characterized in that, The catalyst is selected from one or more of tin-based catalysts and antimony-based catalysts; the chain extender is selected from one or more of 1,4-butanediol, ethylene glycol, and diethyltoluenediamine.

4. The preparation method according to claim 1, characterized in that, The foam stabilizer is selected from one or more of polyether-modified silicone oil and silicone-boron composite silicone oil.

5. The preparation method according to claim 1, characterized in that, The halogen-free flame retardant is selected from one or more of phosphate ester mixtures and dimethyl methylphosphonate; the filler is selected from one or more of expanded graphite and aluminum hydroxide.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the polyether polyol, catalyst, chain extender, foam stabilizer, halogen-free flame retardant, and filler is 100:0.01-2:5-20:5-10:10-30:50-60.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the premix to the modified MDI is 3-4:2-3.

8. The preparation method according to claim 1, characterized in that, The heating and foaming process includes passing the membrane material through a gradient temperature zone at a speed of 10-15 m / min; the gradient temperature zone is divided into 5 segments, with temperatures of 120-130℃, 130-140℃, 140-150℃, 140-150℃, and 130-140℃ respectively; the heating and foaming process takes 2-4 minutes.

9. The preparation method according to claim 1, characterized in that, The aging process is carried out at a temperature of 30-45℃ for 12-36 hours.

10. A halogen-free flame-retardant foam, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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