阅读说明：本技术 一种耐冲击泡棉、制备方法以及应用 (Impact-resistant foam, preparation method and application ) 是由 李沛 魏琼 于 2021-07-20 设计创作，主要内容包括：本发明公开一种耐冲击泡棉、制备方法以及应用,属于减震泡棉领域,其由丙烯酸系乳液物理搅拌机械发泡而成,泡棉内气泡为构成泡棉的丙烯酸系树脂组合物中直接形成的孔隙,气泡壁内面为丙烯酸系树脂组合物,泡棉气泡内壁不具有除形成泡棉的丙烯酸系树脂外的壳结构。其采用丙烯酸系乳液物理搅拌机械发泡而成,丙烯酸系乳液平均粒径为0.07～0.3μm,粘度为1000～9000mPas,丙烯酸系乳液由丙烯酸系单体在包括水、乳化剂、引发剂在内的物质共同作用下聚合而成。本发明泡棉即便在厚度较薄的情况下也具有较高的耐冲击性能,能解决现有泡棉存在厚度薄的情况下耐冲击性能不足的问题。(The invention discloses impact-resistant foam, a preparation method and application, belongs to the field of damping foam, and is formed by physically stirring and mechanically foaming acrylic emulsion. The acrylic emulsion is prepared by physically stirring and mechanically foaming acrylic emulsion, the average particle size of the acrylic emulsion is 0.07-0.3 mu m, the viscosity of the acrylic emulsion is 1000-9000 mPas, and the acrylic emulsion is prepared by polymerizing acrylic monomers under the combined action of substances including water, an emulsifier and an initiator. The foam of the invention has high impact resistance even under the condition of thin thickness, and can solve the problem that the existing foam has insufficient impact resistance under the condition of thin thickness.)

1. An impact-resistant foam characterized in that it is produced by physically stirring and mechanically foaming an acrylic emulsion, the bubbles in the foam are voids directly formed in an acrylic resin composition constituting the foam, the inner surface of the cell wall is the acrylic resin composition, and the inner wall of the foam bubbles does not have a shell structure other than the acrylic resin forming the foam.

2. An impact resistant foam as recited in claim 1,it is characterized in that the thickness of the foam is 0.05 mm-0.3 mm, and the density is 0.3g/cm³～0.8g/cm³。

3. The impact-resistant foam according to claim 2, wherein the impact absorption is 60% or more, and a 1mm thick glass sheet laminated on the foam can withstand 20g iron balls falling from a height of 10cm and impacting more than 50 times and still remain intact.

4. The preparation method of the impact-resistant foam is characterized in that the impact-resistant foam is prepared by physically stirring and mechanically foaming acrylic emulsion, wherein the average particle size of the acrylic emulsion is 0.07-0.3 mu m, the viscosity of the acrylic emulsion is 1000-9000 mPas, and the acrylic emulsion is prepared by polymerizing acrylic monomers under the combined action of substances including water, an emulsifier and an initiator.

5. A process for preparing an impact resistant foam according to claim 4 wherein the acrylic monomer is selected from one or more of the following:

methacrylate, acrylate, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-propyl methacrylate, n-propyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, sec-butyl methacrylate, sec-butyl acrylate, n-octyl methacrylate, n-octyl acrylate, isooctyl methacrylate, isooctyl acrylate, n-pentyl methacrylate, n-pentyl acrylate, n-hexyl methacrylate, n-hexyl acrylate, lauryl methacrylate, lauryl acrylate, n-heptyl methacrylate, n-heptyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, ethyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-nonyl acrylate, n-ethylhexyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-decyl methacrylate, N-decyl acrylate, N-alkyl methacrylate, N-alkyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, styrene, methyl methacrylate, ethyl methacrylate, isobornyl methacrylate, itaconic acid, fumaric acid, maleic acid half ester, maleic anhydride, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, methacrylamide, acrylamide, N-methylmethacrylamide, N-dimethylacrylamide, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-methylacrylamide, N-methylacrylamide, N-methylacrylamide, and a, N, N-diethylmethacrylamide, N-diethylacrylamide, N-propylmethacrylamide, N-propylacrylamide, acrylamide-based monomers, aminoethyl methacrylate, aminoethyl acrylate, t-butylaminoethyl (meth) acrylate, t-butylaminoethyl acrylate, glycidyl methacrylate, and acetoacetoxyethyl methacrylate.

6. The method for preparing an impact resistant foam according to claim 5, wherein the emulsifier is selected from one or more of the following:

sodium lauryl sulfate, sodium stearate salt, alkyl sulfate, sulfosuccinate, alkylphenol polyoxyethylene ethers, alkyl alcohol polyoxyethylene ethers, allyl polyether sulfate, allyl sulfosuccinate, calcium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, potassium oleate, sodium sulfosuccinate, glyceryl stearate, glyceryl oleate, polyoxyethylene lauryl ether, polyoxyethylene laurate, modified sodium lauryl sulfate, polyoxyethylene oleate, MX-188, N40, T-20, and T-60,

the initiator is selected from one or more of the following: potassium persulfate, ammonium persulfate, and sodium persulfate.

7. The method for preparing impact-resistant foam according to claim 6, wherein the acrylic emulsion is polymerized from an emulsion composition of acrylic monomers, water, an emulsifier and an initiator, wherein the mass of the water is 0.7-1.5 times of the total weight of the acrylic monomers, the amount of the emulsifier is 0.5-5% of the total weight of the acrylic monomers, the amount of the initiator is 0.2-3% of the total weight of the acrylic monomers, and the total weight of the acrylic monomers is 30-70% of the total weight of the emulsion composition.

8. The method for preparing impact-resistant foam according to claim 4, wherein the acrylic emulsion is polymerized by the combined action of the following substances:

an acrylic monomer,

Water,

An emulsifier,

An initiator and

one or more of thickening agent, surfactant, antistatic agent, stabilizer, nucleating agent, crosslinking assistant, pigment and flame retardant.

9. A method for preparing an impact-resistant foam as claimed in any of claims 4 to 8, characterized in that it comprises the following steps:

(1) acrylic acid series monomer, water, emulsifier, initiator and other needed additives are emulsified and polymerized in an emulsifying device in an emulsion polymerization mode to obtain acrylic acid emulsion,

(2) placing the acrylic emulsion into a stirring container, adjusting the stirring speed and the stirring time according to the density of foam cotton required to be finally obtained, mixing air, nitrogen, carbon dioxide and other inert gases into the acrylic emulsion, wherein the stirring speed is 800-2500 rpm, the stirring time is 5-50 min,

(3) coating the stirred acrylic emulsion on a base film in a coating mode to obtain an emulsion wet film, adjusting the coating thickness according to the final foam thickness,

(4) and (3) feeding the coated emulsion wet film into a drying tunnel, and finishing the polymerization crosslinking process of the emulsion in the drying tunnel to obtain the acrylic resin foaming film material.

10. The application of the impact-resistant foam is characterized in that the foam is used as a buffer material or an adhesive tape base material under a screen or at a back plate of an intelligent machine.

Technical Field

The invention belongs to the field of shock absorption foam, and particularly relates to impact-resistant foam, a preparation method and application.

Background

With the development of the technology, the larger the screen size of the intelligent machine is, the more the rear shell is made of glass ceramic materials, the thinner the thickness of the intelligent machine is, the thinner the buffer material in the corresponding intelligent machine is, and the thinner the buffer material is, the thinner the thickness of the buffer material is, the thinner the buffer material is. In a display device used in an electronic device, a portion between a glass ceramic material on a device surface and the inside of the device is required to have high impact resistance.

At present, polyolefin foam or polyurethane foam is commonly used as a buffer damping material in a smart machine, however, as the design of the smart machine is advanced, the thickness of the relevant damping material is reduced, and for the existing material, if the thickness is reduced a lot, the glass ceramic material on the surface of the device is not sufficiently impact-resistant to protect the device from being damaged.

Therefore, there is a need to develop a foam material that is sufficiently resistant to impact absorption even at a relatively thin thickness to meet the development requirements of smart machines.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide an impact-resistant foam, a preparation method and application, wherein the foam is formed by physically stirring and mechanically foaming an acrylic emulsion through designing components and processes, has high impact resistance even under the condition of thin thickness, and aims to solve the problem that the impact resistance is insufficient under the condition of thin thickness of the conventional foam.

In order to achieve the above object, the present invention provides an impact-resistant foam which is obtained by physically stirring and mechanically foaming an acrylic emulsion, wherein cells in the foam are voids directly formed in an acrylic resin composition constituting the foam, an inner surface of a cell wall is the acrylic resin composition, and an inner wall of the cells in the foam does not have a shell structure other than the acrylic resin forming the foam.

Furthermore, the thickness of the foam is 0.05 mm-0.3 mm, and the density is 0.3g/cm³～0.8g/cm³。

Furthermore, the impact absorption is more than or equal to 60 percent, and the glass sheet with the thickness of 1mm laminated above the foam can bear the falling impact of 20g of iron balls for more than 50 times from the height of 10cm and still keep intact.

According to the second aspect of the invention, the preparation method of the impact-resistant foam is also provided, and the impact-resistant foam is prepared by physically stirring and mechanically foaming an acrylic emulsion, wherein the acrylic emulsion has an average particle size of 0.07-0.3 mu m and a viscosity of 1000-9000 mPas, and is prepared by polymerizing acrylic monomers under the combined action of substances including water, an emulsifier and an initiator.

Further, the acrylic monomer is selected from one or more of the following:

methacrylate, acrylate, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-propyl methacrylate, n-propyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, sec-butyl methacrylate, sec-butyl acrylate, n-octyl methacrylate, n-octyl acrylate, isooctyl methacrylate, isooctyl acrylate, n-pentyl methacrylate, n-pentyl acrylate, n-hexyl methacrylate, n-hexyl acrylate, lauryl methacrylate, lauryl acrylate, n-heptyl methacrylate, n-heptyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, ethyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-nonyl acrylate, n-ethylhexyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-decyl methacrylate, N-decyl acrylate, N-alkyl methacrylate, N-alkyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, styrene, methyl methacrylate, ethyl methacrylate, isobornyl methacrylate, itaconic acid, fumaric acid, maleic acid half ester, maleic anhydride, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, methacrylamide, acrylamide, N-methylmethacrylamide, N-dimethylacrylamide, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-methylacrylamide, N-methylacrylamide, N-methylacrylamide, and a, N, N-diethylmethacrylamide, N-diethylacrylamide, N-propylmethacrylamide, N-propylacrylamide, acrylamide-based monomers, aminoethyl methacrylate, aminoethyl acrylate, t-butylaminoethyl (meth) acrylate, t-butylaminoethyl acrylate, glycidyl methacrylate, and acetoacetoxyethyl methacrylate.

Further, the emulsifier is selected from one or more of the following:

sodium lauryl sulfate, sodium stearate salt, alkyl sulfate, sulfosuccinate, alkylphenol ethoxylates, alkyl alcohol ethoxylates, allyl polyether sulfate, allyl sulfosuccinate, calcium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, potassium oleate, sodium sulfosuccinate, glyceryl stearate, glyceryl oleate, polyoxyethylene lauryl ether, polyoxyethylene laurate, modified sodium lauryl sulfate, polyoxyethylene oleate, MX-188, N40, T-20, and T-60, wherein the initiator is selected from one or more of the following: potassium persulfate, ammonium persulfate, and sodium persulfate.

Further, the acrylic emulsion is formed by polymerizing an emulsion composition of an acrylic monomer, water, an emulsifier and an initiator, wherein the mass of the water is 0.7-1.5 times of the total weight of the acrylic monomer, the dosage of the emulsifier is 0.5-5% of the total weight of the acrylic monomer, the dosage of the initiator is 0.2-3% of the total weight of the acrylic monomer, and the total weight of the acrylic monomer is 30-70% of the total weight of the emulsion composition.

Further, the acrylic emulsion is formed by the polymerization of the following materials in a combined action mode:

an acrylic monomer,

Water,

An emulsifier,

An initiator and

one or more of thickening agent, surfactant, antistatic agent, stabilizer, nucleating agent, crosslinking assistant, pigment and flame retardant.

Further, the method comprises the following steps:

(1) acrylic monomers, water, an emulsifier, an initiator and other required additives are subjected to emulsion polymerization in emulsion equipment in an emulsion polymerization mode to obtain the acrylic emulsion.

(2) Putting the acrylic emulsion into a stirring container, adjusting the stirring speed and the stirring time according to the foam density finally required, and mixing air, nitrogen, carbon dioxide and other inert gases into the acrylic emulsion, wherein the stirring speed is 800-2500 rpm, the stirring time is 5-50 min, the stirring speed or the stirring time is increased, the total volume of the gas introduced into the acrylic resin is increased, the corresponding foam density is also reduced, when the stirring time is increased to be more than 50min, the gas introduced into the acrylic resin is saturated, when the stirring speed is increased to be more than 2500rpm, the acrylic resin emulsion has the possibility of demulsification, or the resin is subjected to local polymerization and solidification due to friction heat generated by stirring, so that the stability of the foam performance is influenced, and the stirring speed is 1200-2200 rpm, and the stirring time is 10-30 min are preferably selected.

(3) Coating the stirred acrylic emulsion on a base film in a coating mode to obtain an emulsion wet film, and adjusting the coating thickness according to the final foam thickness.

(4) And (3) feeding the coated emulsion wet film into a drying tunnel, and finishing the polymerization crosslinking process of the emulsion in the drying tunnel to obtain the acrylic resin foaming film material.

According to the third aspect of the invention, the application of the impact-resistant foam is also provided, and the impact-resistant foam is used as a buffer material or an adhesive tape substrate under a screen or on a back plate part of a smart machine.

Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

in the present invention, the acrylic resin is used as a main material of the foam, since the acrylic resin polymer itself has a certain impact resistance, and the foam material having an excellent impact resistance can be obtained by combining the foam structure. Specifically, with the increasing social requirements for environmental protection, mechanical foaming is used, waste gas waste possibly generated by foaming with a chemical foaming agent is avoided, mechanical foaming is used, bubbles in foam are directly formed in a resin composition forming the foam, the inner surface of a bubble wall is the resin composition instead of the bubbles with a shell structure of chemical foaming agent residues, and the inner wall of the bubble of the foam does not have a shell structure except for foam resin, so that the inner wall of the bubble is not easily damaged or even broken when being impacted, and the impact resistance of the foam can be improved. In addition, the emulsion liquid raw material is adopted for coating production, and compared with a stretching process in the production of the traditional polyolefin foam, a thinner foam product can be obtained, and the method is more suitable for the design trend and the requirement of thinning the mobile phone.

Drawings

FIG. 1 is a schematic flow chart of a method for preparing impact-resistant foam in an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The foam is prepared by physically stirring and mechanically foaming acrylic emulsion, has the thickness of 0.05-0.3 mm and the density of 0.3-0.8 g/cm³The impact absorption is more than or equal to 60 percent, and a glass sheet with the thickness of 1mm and placed above the foam can resist the falling impact of 20g of iron balls for more than 50 times from the height of 10 cm; characterized in that the acrylic emulsion has an average particle diameter of 0.07 to 0.3 μm and a viscosity of 1000 to 9000 mPas. The above-mentioned CThe average particle size of the acrylic emulsion is 0.07 to 0.3 μm, preferably 0.1 to 0.2 μm. The particle size of the acrylic emulsion resin is required to be smaller than the thickness of the foam, preferably smaller than 0.05mm, and further, if the average particle size of the emulsion is smaller than 0.07. mu.m, the viscosity of the emulsion becomes too high, and if the average particle size is larger than 0.3. mu.m, the water resistance of the resin increases, which is disadvantageous for the polymerization of the emulsion, and the particle size of the resin emulsion is 0.07 to 0.3. mu.m, preferably 0.1 to 0.2. mu.m, for the stability of the mixed gas bubbles in the emulsion.

The viscosity of the acrylic emulsion is 1000 to 9000mPas, preferably 1500 to 5000 mPas. If the viscosity of the emulsion is too low, bubbles mixed in by mechanical stirring easily float in the emulsion, so that the bubbles in the obtained foam product are not uniformly distributed and are not beneficial to the impact resistance of the foam; the emulsion has high viscosity, and is easy to generate shearing heat in the process of mixing bubbles by mechanical stirring, so that the emulsion is locally polymerized, and the obtained foam product has a plurality of small lumps with unqualified appearance, and the composition ratio in the formula design is influenced, so that the required foam product can not be produced.

The acrylic emulsion is prepared by polymerizing acrylic monomers under the action of water, an emulsifier and an initiator. Wherein the mass of the water is 0.7-1.5 times of the total weight of the acrylic monomer; the dosage of the emulsifier is 0.5-5% of the total weight of the acrylic monomers, and the dosage of the initiator is 0.2-3% of the total weight of the acrylic monomers; the total weight of the acrylic monomers is within a range of 30-70% of the total weight of the emulsion composition. The design can make the emulsion formed by emulsion polymerization more stable, is not easy to generate phase separation, and can obtain the emulsion with the viscosity in the required range, so that the introduced bubbles can stably exist in the emulsion.

As a further improvement of the present invention, the acrylic monomer is selected from one or more of the following: methacrylate, acrylate, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-propyl methacrylate, n-propyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, sec-butyl methacrylate, sec-butyl acrylate, n-octyl methacrylate, n-octyl acrylate, isooctyl methacrylate, isooctyl acrylate, n-pentyl methacrylate, n-pentyl acrylate, n-hexyl methacrylate, n-hexyl acrylate, lauryl methacrylate, lauryl acrylate, n-heptyl methacrylate, n-heptyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, n-nonyl methacrylate, n-nonyl acrylate, ethyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-nonyl acrylate, n-ethylhexyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-hexyl acrylate, n-decyl methacrylate, N-decyl acrylate, N-alkyl methacrylate, N-alkyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, styrene, methyl methacrylate, ethyl methacrylate, isobornyl methacrylate, itaconic acid, fumaric acid, maleic acid half ester, maleic anhydride, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, methacrylamide, acrylamide, N-methylmethacrylamide, N-dimethylacrylamide, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-methylacrylamide, N-methylacrylamide, N-methylacrylamide, and a, N, N-diethylmethacrylamide, N-diethylacrylamide, N-propylmethacrylamide, N-propylacrylamide, acrylamide-based monomers, aminoethyl methacrylate, aminoethyl acrylate, t-butylaminoethyl (meth) acrylate, t-butylaminoethyl acrylate, glycidyl methacrylate, and acetoacetoxyethyl methacrylate.

The emulsifier is one or more of sodium dodecyl sulfate, sodium stearate salt, alkyl sulfate, sulfosuccinate, alkylphenol polyoxyethylene ether, alkyl alcohol polyoxyethylene ether, allyl polyether sulfate, allyl sulfosuccinate, calcium dodecylbenzene sulfonate, sodium dodecylbenzene sulfonate, potassium oleate, sodium succinate sulfonate, glyceryl stearate, glyceryl oleate, polyoxyethylene lauryl ether, polyoxyethylene laurate, modified sodium lauryl sulfate, polyoxyethylene oleate, MX-188, N40, T-20 and T-60. The initiator is one or more of potassium persulfate, ammonium persulfate and sodium persulfate.

The acrylic emulsion may further contain other additives such as a thickener, a surfactant, an antistatic agent, a stabilizer, a nucleating agent, a crosslinking assistant, a pigment, a flame retardant, and the like, as long as the object of the present invention is not impaired.

In addition, the acrylic monomer, the emulsifier and the initiator can be combined and matched with each other only if they do not conflict with each other in terms of components.

Fig. 1 is a schematic flow chart of a method for preparing impact-resistant foam in an embodiment of the present invention, and it can be seen that the method for preparing acrylic foam is as follows:

(1) emulsion polymerization: carrying out emulsion polymerization on acrylic monomers, water, an emulsifier, an initiator and other additives in emulsion polymerization equipment to obtain acrylic emulsion;

(2) mechanical foaming: placing the acrylic emulsion into a stirring container, adjusting the stirring speed and the stirring time according to the finally required foam density, and mixing air or inert gases such as nitrogen or carbon dioxide into the acrylic emulsion;

(3) coating: coating the stirred acrylic emulsion on a base film by using PET (polyethylene terephthalate) or a release film or other base materials as the base film in a coating mode to obtain an emulsion wet film, and adjusting the coating thickness in the step;

(4) polymerization and crosslinking: sending the coated emulsion wet film into a drying tunnel, and finishing the polymerization crosslinking process of the emulsion in the drying tunnel to obtain an acrylic resin foaming film material;

(5) winding: and (4) rolling the acrylic resin foaming film material to finally obtain the required acrylic acid foam.

The following examples are given in more detail

Example 1

(1) Emulsion polymerization: carrying out emulsion polymerization on a methacrylic acid monomer, an acrylamide monomer, water, an emulsifier sodium dodecyl sulfate and an initiator potassium persulfate in an emulsifying machine according to mass fraction to obtain an acrylic emulsion. The methacrylic acid monomer and the acrylamide monomer constitute acrylic acid monomers, in this example, the mass of water is 1.0 time of the total weight of the acrylic acid monomers, the amount of the emulsifier is 2.5% of the total weight of the acrylic acid monomers, and the amount of the initiator is 1.5% of the total weight of the acrylic acid monomers.

(2) Mechanical foaming: putting the obtained acrylic emulsion into a stirring container, stirring at the rotating speed of 1000rpm for 10min, and mixing with emulsion gas which is air;

(3) coating: coating the stirred acrylic emulsion on a base film by taking a release PET film as the base film in a comma scraper coating mode to obtain an emulsion wet film, and adjusting the thickness of the emulsion wet film to be 0.25 mm;

(4) polymerization and crosslinking: feeding the coated emulsion wet film into a drying tunnel, setting the temperature in the drying tunnel to be 100 ℃, setting the drying tunnel to be 20m long, setting the equipment running speed to be 2m/min, finishing the polymerization crosslinking process of the emulsion in the drying tunnel to obtain an acrylic resin foaming film material, wherein the foam thickness is 0.15 mm;

(5) winding: and (4) rolling the acrylic resin foaming film material to finally obtain the required acrylic acid foam.

The above test was conducted by sampling to evaluate the impact resistance.

Example 2

The test was conducted in the same manner as in example 1 except that the stirring speed was increased to 2000rpm as in example 1, and the impact resistance was evaluated by sampling.

Example 3

The difference from example 2 was that the stirring time was increased to 20min, and the impact resistance was evaluated by sampling the sample in the same manner as in example 2.

Example 4

The difference from the example 1 is that the formula proportion is changed into: methacrylic acid monomer, acrylamide monomer, water, emulsifier sodium dodecyl sulfate, and initiator potassium persulfate. The acrylic monomer is composed of a methacrylic monomer and an acrylamide monomer, wherein the mass of water is 1.5 times of the total weight of the acrylic monomer, the using amount of the emulsifier is 5% of the total weight of the acrylic monomer, and the using amount of the initiator is 0.2% of the total weight of the acrylic monomer.

The above test was conducted by sampling to evaluate the impact resistance.

Example 5

The difference from the example 1 is that the formula proportion is changed into methacrylic acid monomer, styrene, acrylamide monomer, water, emulsifier sodium dodecyl sulfate and initiator potassium persulfate in the emulsion polymerization process. Wherein, the methacrylic acid monomer, the styrene and the acrylamide monomer form an acrylic acid monomer. In this example, the mass of water is 0.7 times of the total weight of the acrylic monomers, the amount of the emulsifier is 0.5% of the total weight of the acrylic monomers, and the amount of the initiator is 3% of the total weight of the acrylic monomers.

The above test was conducted by sampling to evaluate the impact resistance.

Example 6

The difference from the embodiment 1 is that the formula proportion is changed into methacrylic acid monomer, acrylamide, N-ethyl acrylamide, water, emulsifier lauryl alcohol polyoxyethylene ether and initiator ammonium persulfate in the emulsion polymerization process. Wherein, the methacrylic acid monomer, the styrene and the acrylamide monomer form an acrylic acid monomer. In this example, the mass of water is 1.3 times of the total weight of the acrylic monomers, the amount of the emulsifier is 0.6% of the total weight of the acrylic monomers, and the amount of the initiator is 2.8% of the total weight of the acrylic monomers.

And (2) putting the acrylic emulsion into a stirring container, adjusting the stirring speed and the stirring time according to the foam density required to be finally obtained, and mixing air, nitrogen, carbon dioxide and other inert gases into the acrylic emulsion, wherein the stirring speed is 1800rpm, and the stirring time is 25 min.

The above test was conducted by sampling to evaluate the impact resistance.

Example 7

The difference from the example 1 is that the formula proportion is changed into methacrylic acid monomer, aminoethyl methacrylate, acrylamide monomer, water, emulsifier sodium dodecyl sulfate and initiator potassium persulfate in the emulsion polymerization process. Wherein, the methacrylic acid monomer, the styrene and the acrylamide monomer form an acrylic acid monomer. In this example, the mass of water is 1.2 times of the total weight of the acrylic monomers, the amount of the emulsifier is 3.5% of the total weight of the acrylic monomers, and the amount of the initiator is 1.6% of the total weight of the acrylic monomers.

And (2) putting the acrylic emulsion into a stirring container, adjusting the stirring speed and the stirring time according to the foam density required to be finally obtained, and mixing air, nitrogen, carbon dioxide and other inert gases into the acrylic emulsion, wherein the stirring speed is 2100rpm, and the stirring time is 41 min.

The above test was conducted by sampling to evaluate the impact resistance.

Comparative example 1:

commercial polyethylene foam with the same thickness and density as those of the foam product obtained in example 3 was selected and tested to evaluate the impact resistance.

Comparative example 2:

commercial polyurethane foam with the same thickness and density as those of the foam product obtained in example 3 was selected and tested to evaluate impact resistance.

In the following examples, the test methods employed for foamed sheets are as follows:

(1) the thickness of the foam is as follows: the thickness was measured by a method described in ASTM D3574 standard, using a thickness gauge for soft foam having a base area of not less than 650mm2, measuring the thickness by a 9-point method (the center point of the sample, the center points of four sides of the sample, and the four corner points of the sample) on a 10cm by 10cm foam sheet sample, and calculating the average value.

(2) Foam density: a 10cm by 10cm standard sample of the foamed sheet was taken, and the thickness was measured according to the method described in ASTM D3574 standard, and then the mass was weighed to calculate the density.

(3) Impact absorption test of foam: in a standard laboratory environment, 5cm by 10cm samples of foam were prepared and placed on the bottom stress sensing device platform. The maximum stress before and after placing the foam was read by using 20g pellets which were freely dropped from a height of 20cm, and the impact absorption was (maximum stress value before placing the foam-maximum stress value after placing the foam)/maximum stress value before placing the foam was 100%.

(4) Impact resistance test of foam: in a standard laboratory environment, a 5cm by 10cm sample of foam was prepared and placed on a flat platform, and a 1mm by 5cm by 10cm glass slide was placed over the foam sample. The dropping test was repeated by using 20g of iron balls to impact the glass sheet in a free fall from a height of 20cm, and the number of times the iron balls hit the glass when the glass sheet was broken was recorded, and the larger the number of times, the better the impact resistance of the foam.

(5) Testing the particle size of the emulsion: particle size was measured using a BettERSIZE2600 laser particle size distribution instrument.

(6) Emulsion viscosity test: the viscosity was measured using a rotational viscometer using a # 3 spindle set at 30rpm for the measurement in viscosity units mPas.

In the invention, the impact-resistant foam can be used as a buffer material or an adhesive tape base material under a screen or at a back plate of an intelligent machine, and has enough impact-resistant absorption capacity even under a thinner thickness.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.