Siloxane modified thermal foaming microsphere, polyacrylate foam and preparation method and application thereof

Abstract

The present invention provides a siloxane-modified thermal foaming microsphere, polyacrylate foam and a preparation method and application thereof. The siloxane-modified thermal foaming microsphere is synthesized from thermal expansion microspheres, a silane coupling agent, a catalyst, an initiator and a hydroxyl-terminated silicone oil as raw materials. The siloxane-modified thermal expansion microsphere of the present invention can induce silver streaks and shear bands, greatly improving the energy absorption rate of the polyacrylate foam, because the siloxane-modified thermal expansion microsphere improves the compatibility of the microsphere with the foam matrix.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a siloxane-modified thermal foaming microsphere, polyacrylate foam, and a preparation method and application thereof. Background Art

[0002] With the development of economy and society, various electronic products have entered people's production and life, greatly promoting the development of various fields. As the display screen of high-end electronic products, OLED screen has the advantages of rich colors, light weight and thinness, but OLED is prone to cracking and product failure when impacted by external force. Polyacrylate foam is widely used in the field of electronic product buffering as the protective layer of OLED screen.

[0003] Existing polyacrylate foam increases energy absorption by forming pores through foaming. When subjected to external impact, the pores have a certain anti-shear effect and can play a role in shock absorption and buffering. However, this single shock absorption method is difficult to meet the demand of OLED screens for ultra-thin shock-absorbing and buffering foam. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a silicone modified thermal foaming microsphere, polyacrylate foam and a preparation method and application thereof, so as to solve the problem that the protection and shock absorption performance of polyacrylate foam in the prior art cannot meet the demand of OLED screen for ultra-thin shock-absorbing buffer foam.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A siloxane-modified thermal foaming microsphere is synthesized from thermal expansion microspheres, a silane coupling agent, a catalyst, an initiator and terminal hydroxyl silicone oil as raw materials.

[0007] Preferably, the siloxane-modified heat-expandable microspheres have a structure as shown in Formula I:

[0008]

[0009] Preferably, the silicone-modified thermal foaming microspheres are synthesized from the following raw materials in parts by weight:

[0010] 10-15 parts by weight of heat-expandable microspheres, 1-3 parts by weight of silane coupling agent, 5-10 parts by weight of hydroxyl-terminated silicone oil, 0.1-0.3 parts by weight of catalyst, and 0.2-0.4 parts by weight of initiator.

[0011] Preferably, the silane coupling agent is one or more of 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane;

[0012] Optionally, the catalyst is one or more of O-benzotriazole-tetramethyluronium hexafluorophosphate, N,N-diisopropylethylamine;

[0013] Optionally, the initiator is one or more of dibutyltin dilaurate or dibutyltin didodecylsulfide.

[0014] The present invention also provides a method for preparing the silicone-modified thermally foamed microspheres, comprising the following steps:

[0015] (1) taking heat-expandable microspheres, a silane coupling agent and a catalyst, and reacting them to obtain an intermediate product;

[0016] (2) Adding an initiator and terminal hydroxyl silicone oil to the intermediate product obtained in (1) to react to obtain siloxane-modified heat-expandable microspheres.

[0017] Preferably, in step (1), the reaction temperature is 10-40°C and the reaction time is 3-4h;

[0018] Optionally, in step (2), the reaction temperature is 50-60° C. and the reaction time is 2-6 h.

[0019] Preferably, step (1) specifically comprises the following steps: taking heat-expandable microspheres, a silane coupling agent and a catalyst, adding them into ethanol in sequence under the protection of nitrogen, mixing them evenly, stirring and reacting to obtain an intermediate product.

[0020] Preferably, step (2) specifically comprises the following steps: taking the intermediate product of step (1), an initiator, and terminal hydroxyl silicone oil, adding them to isopropanol in sequence, mixing them evenly, stirring and reacting, and obtaining siloxane-modified thermally expandable microspheres.

[0021] Preferably, step (2) further comprises the step of post-treating the obtained siloxane-modified heat-expandable microspheres:

[0022] The obtained siloxane-modified heat-expandable microspheres are filtered from the mixed solution, washed with petroleum ether and ethanol, and then dried with anhydrous magnesium sulfate to remove the volatile solvent to obtain dry siloxane-modified heat-expandable microspheres.

[0023] The invention also provides a polyacrylate foam containing the silicone-modified thermal foaming microspheres.

[0024] Preferably, the polyacrylate foam further comprises polyacrylate emulsion; the weight ratio of the polyacrylate emulsion to the silicone-modified thermal foaming microspheres is 1:(0.1-0.4).

[0025] The present invention also provides a method for preparing the polyacrylate foam, comprising the following steps:

[0026] The siloxane-modified heat-expandable microspheres are added into the polyacrylate emulsion to react and obtain the polyacrylate foam.

[0027] Preferably, the reaction temperature is 55-60°C and the reaction time is 1-2h.

[0028] Preferably, the preparation method of the polyacrylate foam comprises the following steps:

[0029] The siloxane-modified heat-expandable microspheres are added into the polyacrylate emulsion, mixed evenly, reacted, and the coating is dried to obtain the polyacrylate foam.

[0030] The present invention also provides an application of the polyacrylate foam or the foam obtained by the preparation method of the polyacrylate foam in a buffering and shock absorbing material.

[0031] The above solution of the present invention includes at least the following beneficial effects:

[0032] (1) The siloxane-modified heat-expandable microspheres of the present invention are synthesized from heat-expandable microspheres, silane coupling agents, catalysts, initiators, and terminal hydroxyl silicone oils as raw materials. The siloxane-modified heat-expandable microspheres of the present invention utilize the carboxyl groups on the heat-expandable microspheres to react with the amino groups of the silane coupling agents to form intermediate products, and then under the action of the catalyst, the other end of the silane coupling agent is deethanolized, reacted with the terminal hydroxyl silicone oil, and reacted on the surface of the heat-expandable microspheres to generate long chains of polysiloxane. Since the main component of the heat-expandable microspheres is polyacrylate, they have good compatibility with the foam matrix. When the siloxane-modified heat-expandable microspheres of the present invention are added to the polyacrylate emulsion to make foam, the compatibility of the microspheres with the foam matrix is ​​reduced, and silver streaks can be generated when subjected to external forces, which greatly increases the energy absorption rate of the polyacrylate foam.

[0033] The polysiloxane chain is located on the surface of the heat-expandable microspheres, and the obtained microspheres can still maintain a relatively stable shape and achieve high energy absorption. At the same time, polysiloxane also has excellent hydrophobicity and electrical insulation. Its hydrophobic properties can effectively reduce the water absorption rate of polyacrylate foam after adding siloxane-modified heat-expandable microspheres to foam, greatly increasing the practicality of polyacrylate foam, thereby obtaining polyacrylate foam with high energy absorption rate and low water absorption rate. The energy absorption rate of the obtained polyacrylate foam can meet the current needs of the OLED industry.

[0034] (2) The polyacrylate foam of the present invention uses silicone-modified heat-expandable microspheres to improve the compatibility of the microspheres with the foam matrix, induce silver streaks and shear bands, and greatly improve the energy absorption rate of the polyacrylate foam.

[0035] (3) The preparation method of the siloxane-modified heat-expandable microspheres of the present invention comprises the following steps: taking heat-expandable microspheres, a silane coupling agent and a catalyst, reacting to obtain an intermediate product; adding an initiator and a terminal hydroxyl silicone oil to the intermediate product, and reacting to obtain the siloxane-modified heat-expandable microspheres. The preparation method of the siloxane-modified heat-expandable microspheres starts from the surface modification of the heat-expandable microspheres, and after two steps of modification, the silane coupling agent and the terminal hydroxyl silicone oil are uniformly grafted on the surface of the microspheres. When applied to polyacrylate foam, the siloxane-modified heat-expandable microspheres can be mixed with a polyacrylate emulsion to obtain a polyacrylate foam, which reduces the compatibility of the microspheres with the foam matrix. When subjected to external force, silver streaks can be generated on the surface of the heat-expandable microspheres and the foam matrix, which greatly increases the energy absorption rate of the polyacrylate foam. At the same time, the siloxane-modified thermally expandable microspheres can maintain a relatively stable shape and effectively reduce the water absorption rate of the polyacrylate foam, greatly increasing the practicality of the polyacrylate foam. The energy absorption rate of the obtained polyacrylate foam can better meet the needs of the OLED industry. DETAILED DESCRIPTION

[0036] If the specific conditions are not specified in the embodiments of the present invention, the conventional conditions or the conditions recommended by the manufacturer are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially. Only some of the reagents used in the embodiments of the present invention are provided below. Raw materials of different manufacturers and models do not affect the implementation of the technical solution of the present invention and the realization of the technical effects.

[0037]

[0038]

[0039] Example 1

[0040] The siloxane-modified heat-expandable microspheres of this embodiment are synthesized from the following raw materials in parts by weight:

[0041] 10 parts by weight of heat-expandable microspheres, 2 parts by weight of silane coupling agent, 10 parts by weight of hydroxy-terminated silicone oil, 0.2 parts by weight of catalyst, and 0.3 parts by weight of initiator.

[0042] The silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane in a weight ratio of 1:1; the initiator is dibutyltin dilaurate; and the catalyst is a mixture of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine in a weight ratio of 1:1.

[0043] The method for preparing the siloxane-modified heat-expandable microspheres described in this embodiment comprises the following steps:

[0044] (1) Take heat-expandable microspheres, a silane coupling agent and a catalyst, and react to obtain an intermediate product; the reaction formula is as follows:

[0045]

[0046] Wherein, the spherical structure in the above reaction formula is a heat-expandable microsphere, and the initial heat-expandable microsphere is a microsphere with a carboxyl group on the surface;

[0047] (2) adding an initiator and hydroxyl-terminated silicone oil to the intermediate product obtained in (1) to react to obtain siloxane-modified thermally expandable microspheres; the reaction formula is as follows:

[0048]

[0049] The preparation method of the siloxane-modified heat-expandable microspheres described in this embodiment specifically comprises the following steps:

[0050] (1) taking heat-expandable microspheres, a silane coupling agent and a catalyst, adding them to ethanol in sequence under the protection of nitrogen, mixing them evenly, and stirring and reacting them at 25° C. for 4 h to obtain an intermediate product;

[0051] (2) The intermediate product of step (1), an initiator, and terminal hydroxyl silicone oil are added to isopropanol in sequence, mixed evenly, and stirred for reaction at 50° C. for 4 h to obtain siloxane-modified thermally expandable microspheres.

[0052] Since the siloxane-modified heat-expandable microspheres are present in the mixed solution after the reaction, the method may further include the following steps: post-treating the obtained siloxane-modified heat-expandable microspheres:

[0053] The obtained siloxane-modified heat-expandable microspheres are filtered from the mixed solution, washed with petroleum ether and ethanol, and then dried with anhydrous magnesium sulfate to remove the volatile solvent to obtain dry siloxane-modified heat-expandable microspheres.

[0054] For achieving the purpose of the present invention, the solvents used in steps (1) and (2) are not unique. As an alternative implementation method of this embodiment, the isopropanol solvent can also be replaced by one or more of methanol, n-propanol, and butanol.

[0055] The polyacrylate foam of this embodiment contains the silicone-modified thermal foaming microspheres and also includes a polyacrylate emulsion;

[0056] The weight ratio of the polyacrylate emulsion to the silicone-modified thermal foaming microspheres is 1:0.2.

[0057] The preparation method of the polyacrylate foam of this embodiment comprises the following steps:

[0058] The siloxane-modified heat-expandable microspheres were added into the polyacrylate emulsion, mixed evenly, reacted at a temperature of 55° C. for 1 hour, and then the coating was dried to obtain the polyacrylate foam.

[0059] Example 2

[0060] The siloxane-modified heat-expandable microspheres of this embodiment are synthesized from the following raw materials in parts by weight:

[0061] 15 parts by weight of heat-expandable microspheres, 1 part by weight of silane coupling agent, 5 parts by weight of hydroxy-terminated silicone oil, 0.1 parts by weight of catalyst, and 0.4 parts by weight of initiator.

[0062] Wherein, the silane coupling agent is 3-aminopropyltriethoxysilane; the initiator is didodecylsulfide dibutyltin; and the catalyst is O-benzotriazole-tetramethyluronium hexafluorophosphate.

[0063] The preparation method of the siloxane-modified heat-expandable microspheres described in this embodiment specifically comprises the following steps:

[0064] (1) taking heat-expandable microspheres, a silane coupling agent and a catalyst, adding them to ethanol in sequence under the protection of nitrogen, mixing them evenly, and stirring and reacting them at 40° C. for 3 h to obtain an intermediate product;

[0065] (2) The intermediate product of step (1), an initiator, and terminal hydroxyl silicone oil are added to isopropanol in sequence, mixed evenly, and stirred for reaction at 55° C. for 2 h to obtain siloxane-modified thermally expandable microspheres.

[0066] Since the siloxane-modified heat-expandable microspheres are present in the mixed solution after the reaction, the method may further include the following steps: post-treating the obtained siloxane-modified heat-expandable microspheres:

[0067] The obtained siloxane-modified heat-expandable microspheres are filtered from the mixed solution, washed with petroleum ether and ethanol, and then dried with anhydrous magnesium sulfate to remove the volatile solvent to obtain dry siloxane-modified heat-expandable microspheres.

[0068] For achieving the purpose of the present invention, the solvents used in steps (1) and (2) are not unique. As an alternative implementation method of this embodiment, the isopropanol solvent can also be replaced by one or more of methanol, n-propanol, and butanol.

[0069] The polyacrylate foam of this embodiment contains the silicone-modified thermal foaming microspheres and also includes a polyacrylate emulsion;

[0070] The weight ratio of the polyacrylate emulsion to the silicone-modified thermal foaming microspheres is 1:0.1.

[0071] The preparation method of the polyacrylate foam of this embodiment comprises the following steps:

[0072] The siloxane-modified heat-expandable microspheres were added into the polyacrylate emulsion, mixed evenly, reacted at a temperature of 60° C. for 2 hours, and the coating was dried to obtain the polyacrylate foam.

[0073] Example 3

[0074] The siloxane-modified heat-expandable microspheres of this embodiment are synthesized from the following raw materials in parts by weight:

[0075] 12 parts by weight of heat-expandable microspheres, 3 parts by weight of silane coupling agent, 7 parts by weight of hydroxy-terminated silicone oil, 0.3 parts by weight of catalyst, and 0.2 parts by weight of initiator.

[0076] Wherein, the silane coupling agent is 3-aminopropyltrimethoxysilane; the initiator is dibutyltin dilaurate; and the catalyst is N,N-diisopropylethylamine.

[0077] The preparation method of the siloxane-modified heat-expandable microspheres described in this embodiment specifically comprises the following steps:

[0078] (1) taking heat-expandable microspheres, a silane coupling agent and a catalyst, adding them to ethanol in sequence under the protection of nitrogen, mixing them evenly, and stirring and reacting them at 10° C. for 4 h to obtain an intermediate product;

[0079] (2) The intermediate product of step (1), an initiator, and terminal hydroxyl silicone oil are added to isopropanol in sequence, mixed evenly, and stirred at 60° C. for 6 h to obtain siloxane-modified heat-expandable microspheres.

[0080] Since the siloxane-modified heat-expandable microspheres are present in the mixed solution after the reaction, the method may further include the following steps: post-treating the obtained siloxane-modified heat-expandable microspheres:

[0081] The obtained siloxane-modified heat-expandable microspheres are filtered from the mixed solution, washed with petroleum ether and ethanol, and then dried with anhydrous magnesium sulfate to remove the volatile solvent to obtain dry siloxane-modified heat-expandable microspheres.

[0082] For achieving the purpose of the present invention, the solvents used in steps (1) and (2) are not unique. As an alternative implementation method of this embodiment, the isopropanol solvent can also be replaced by one or more of methanol, n-propanol, and butanol.

[0083] The polyacrylate foam of this embodiment contains the silicone-modified thermal foaming microspheres and also includes a polyacrylate emulsion;

[0084] The weight ratio of the polyacrylate emulsion to the silicone-modified thermal foaming microspheres is 1:0.4.

[0085] The preparation method of the polyacrylate foam of this embodiment comprises the following steps:

[0086] The siloxane-modified heat-expandable microspheres were added into the polyacrylate emulsion, mixed evenly, reacted at a temperature of 58° C. for 1 hour, and then the coating was dried to obtain the polyacrylate foam.

[0087] Example 4

[0088] The siloxane-modified heat-expandable microspheres of this embodiment have the same raw materials and the same preparation method as those of Embodiment 1, with the only difference being that in step (2), the reaction time is 2 hours.

[0089] The polyacrylate foam of this embodiment has the same raw materials and the same preparation method as that of Embodiment 1.

[0090] Example 5

[0091] The siloxane-modified heat-expandable microspheres of this embodiment have the same raw materials and the same preparation method as those of Example 1, with the only difference being that in step (2), the reaction time is 6 hours.

[0092] The polyacrylate foam of this embodiment has the same raw materials and the same preparation method as that of Embodiment 1.

[0093] Comparative Example 1

[0094] This comparative example has the same raw materials and the same preparation method as Example 1, and the only difference is that in this comparative example, the terminal hydroxyl silicone oil is not used, and only the heat-expandable microspheres are modified with a silane coupling agent.

[0095] In this comparative example, the heat-expandable microspheres were modified with a silane coupling agent only, and polyacrylate foam was prepared according to the same raw materials and the same preparation method as in Example 1.

[0096] Comparative Example 2

[0097] This comparative example has the same raw materials and preparation method as Example 1, with the only difference being that in this comparative example, the terminal hydroxyl silicone oil and the silane coupling agent are not used for modification, and only the raw material heat-expandable microspheres are used.

[0098] In this comparative example, the heat-expandable microspheres are used to prepare polyacrylate foam using the same raw materials and the same preparation method as in Example 1.

[0099] Effect comparison ratio

[0100] In order to verify the technical effect of the polyacrylate foam described in the present invention, the following experiments were conducted:

[0101] Take the polyacrylate foam prepared in Examples 1-5 and Comparative Examples 1-2, and test its cushioning performance after standing for 24 hours: first cut the foam to be tested into a size of 100mm*100mm*0.1mm and stick it to the sensor of the falling ball impact tester, use a 4.3g steel ball to drop it at a height of 10cm, and the energy value obtained by the test is G1; then tear off the foam and directly drop the test energy value is G0; (G0-G1) / G0 is used to obtain the impact energy absorption rate.

[0102] After experimentation, the results are as follows:

[0103] Group Point impact energy absorption rate (%) Example 1 72.7％ Example 2 62.5％ Example 3 69.3％ Example 4 68.5％ Example 5 74.6％ Comparative Example 1 55.5％ Comparative Example 2 52.8％

[0104] It can be seen from the above comparative examples 1-7 that the point impact energy absorption of the polyacrylate foam made of the heat-expandable microspheres modified by siloxane is greatly improved. It can be seen from the point impact energy absorption rate of Examples 1, 4, and 5 that the cushioning performance of the polyacrylate foam of the siloxane-modified heat-expandable microspheres increases with the increase of the end hydroxyl silicone oil content, which shows that the heat-expandable microspheres modified by the end hydroxyl silicone oil of the present invention can improve the energy absorption rate of the foam product when added to the polyacrylate foam. It can be seen from Examples 1, 2, and 3 that with the increase of the amount of heat-expandable microspheres added after siloxane modification, the cushioning performance of the polyacrylate foam first increases and then decreases, which shows that when the siloxane-modified heat-expandable microspheres and the foam matrix are in a suitable ratio, the two can form an effective bonding interface, produce silver streaks when subjected to external impact, and increase the energy absorption rate of the foam, and the best effect is when the ratio of polyacrylate emulsion to heat-expandable microspheres is 1:0.2. The present invention grafts terminal hydroxyl silicone oil onto the surface of heat-expandable microspheres, and then mixes and foams the microspheres with polyacrylate emulsion to obtain polyacrylate foam with excellent energy absorption, which meets the demand of high-end electronic products OLED screens for ultra-thin shock-absorbing and buffering foams and has broad application prospects.

[0105] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A siloxane-modified thermal foaming microsphere, characterized in that: The product is synthesized from 10-15 parts by weight of heat-expandable microspheres, 1-3 parts by weight of a silane coupling agent, 0.1-0.3 parts by weight of a catalyst, 0.2-0.4 parts by weight of an initiator, and 5-10 parts by weight of terminal hydroxyl silicone oil as raw materials; The silane coupling agent is one or more of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

2. The siloxane-modified thermally foamed microsphere according to claim 1, characterized in that: The catalyst is one or more of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine.

3. The siloxane-modified thermally foamed microsphere according to claim 1, characterized in that: The initiator is one or more of dibutyltin dilaurate or didodecylsulfide dibutyltin.

4. A method for preparing the siloxane-modified thermally foamed microspheres according to any one of claims 1 to 3, characterized in that: The steps include: (1) taking heat-expandable microspheres, a silane coupling agent and a catalyst, and reacting them to obtain an intermediate product; (2) Adding an initiator and terminal hydroxyl silicone oil to the intermediate product obtained in (1) to react to obtain siloxane-modified heat-expandable microspheres.

5. The method for preparing siloxane-modified thermally foamed microspheres according to claim 4, characterized in that: In step (1), the reaction temperature is 10-40°C and the reaction time is 3-4h.

6. The method for preparing siloxane-modified thermally foamed microspheres according to claim 4, characterized in that: In step (2), the reaction temperature is 50-60°C and the reaction time is 2-6h.

7. A polyacrylate foam, characterized in that: Contains the silicone-modified thermally foamed microspheres according to any one of claims 1 to 3.

8. The polyacrylate foam according to claim 7, characterized in that: It also includes polyacrylate emulsion; the weight ratio of the polyacrylate emulsion to the silicone modified thermal foaming microsphere is 1:(0.1-0.4).

9. A method for preparing the polyacrylate foam according to any one of claims 7 to 8, characterized in that: The steps include: The siloxane-modified heat-expandable microspheres are added into the polyacrylate emulsion to react and obtain the polyacrylate foam.

10. The method for preparing polyacrylate foam according to claim 9, characterized in that: The reaction temperature is 55-60°C and the reaction time is 1-2h.

11. Use of the polyacrylate foam described in any one of claims 7 to 8 or the foam obtained by the preparation method of the polyacrylate foam described in any one of claims 9 to 10 in cushioning and shock absorbing materials.

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