A foaming agent microcapsule composite material and preparation method thereof

Abstract

The invention discloses a foaming agent microcapsule composite material and a preparation method thereof. The microcapsule composite material has a core-shell structure, wherein the core is N,N'-dinitrosopentamethylenetetramine and the shell is formed by polymerization of styrene, isooctyl acrylate and dimethyl maleate. The preparation method comprises the following steps: (1) dispersing an oil phase consisting of N,N'-dinitrosopentamethylenetetramine, an organic solvent, styrene, isooctyl acrylate, dimethyl maleate and an initiator in an aqueous phase consisting of water and an emulsifier to form a stable O / W system; (2) heating the O / W system to perform a polymerization reaction, and after the reaction is completed, taking a solid material; and by loading the N,N'-dinitrosopentamethylenetetramine foaming agent into a uniform and dense polystyrene resin-based polymer shell material, the storage stability, use and transportation safety of the N,N'-dinitrosopentamethylenetetramine foaming agent are effectively improved.

Description

Technical Field

[0001] The invention relates to a foaming agent and a preparation method thereof, in particular to a foaming agent microcapsule composite material and a preparation method thereof. Background Art

[0002] Polymer foam material refers to a microporous material based on polymer (plastic, rubber, elastomer or natural polymer material) with countless bubbles inside. It can also be regarded as a composite material with gas as filler.

[0003] There are many varieties of polymer foam materials. For plastics, most thermoplastics and thermosetting plastics can be processed into foam plastics. Typical foam materials include thermoplastic and thermosetting foam plastics such as polystyrene foam, polyurethane foam, polyolefin foam, polyvinyl chloride foam, phenolic foam, epoxy resin foam, nitrile rubber foam, thermoplastic elastomer foam, foaming starch, foaming plant fiber and other natural polymer foam materials. They are widely used in household daily necessities, transportation, insulation materials, packaging materials, electrical appliances, sports facilities, electronic products, chemicals and textiles. High-performance foam plastics play an important role in cutting-edge fields such as military and aerospace.

[0004] Most foaming materials are prepared by gas foaming within a specific viscosity range of the polymerization system. A foaming agent is a type of additive that is added to the polymer matrix and provides gas by heating decomposition or direct injection, so that the polymer can form a cellular structure under processing conditions. Therefore, a foaming agent is an important processing aid that is indispensable for foaming materials. Depending on the state of the substance, there are three types of foaming agents: solid, liquid and gas; according to the different ways of generating gas during the foaming process, they are generally divided into physical foaming agents and chemical foaming agents.

[0005] N,N'-Dinitrosopentamethylenetetramine is one of the main blowing agents currently used for foaming materials. However, the blowing agent is extremely sensitive to acidic substances such as inorganic acids and organic acids. It can decompose violently or even catch fire upon contact at room temperature. At the same time, the blowing agent itself is flammable. In combustion tests, it often ignites along with decomposition and has a tendency to continue burning, resulting in poor storage stability, use and transportation safety, which brings many safety hazards to the large-scale production and use of the blowing agent in foam plastics. Summary of the invention

[0006] Purpose of the invention: The first purpose of the present invention is to provide a foaming agent microcapsule composite material that improves the storage stability of N,N'-dinitrosopentamethylenetetramine; another purpose of the present invention is to provide a method for preparing the foaming agent microcapsule composite material.

[0007] Technical solution: The foaming agent microcapsule composite material of the present invention has a core-shell structure, wherein the core is N,N'-dinitrosopentamethylenetetramine and the shell is formed by polymerization of styrene, isooctyl acrylate and dimethyl maleate.

[0008] Preferably, the mass ratio of the inner core to the outer shell is 4-5:5.5-9.5.

[0009] Preferably, the ratio of styrene, isooctyl acrylate and dimethyl maleate in the shell is 4-6:1-2:0.5-1.5. Under this ratio, the formed polymer shell material is uniform and dense and has a certain flexibility, which is conducive to the effective release of the core.

[0010] The method for preparing the foaming agent microcapsule composite material of the present invention comprises the following steps:

[0011] (1) dispersing an oil phase consisting of N,N'-dinitrosopentamethylenetetramine, an organic solvent, styrene, isooctyl acrylate, dimethyl maleate and an initiator in a water phase consisting of water and an emulsifier to form a stable O / W system;

[0012] (2) The O / W system is heated to carry out polymerization reaction. After the reaction is completed, a solid material is obtained, which is the N,N'-dinitrosopentamethylenetetramine foaming agent microcapsule composite material.

[0013] Styrene, isooctyl acrylate and dimethyl maleate undergo polymerization reaction under the action of an initiator when the temperature rises, forming a dense polystyrene resin-based polymer shell material, which wraps up N,N'-dinitrosopentamethylenetetramine to achieve microencapsulation.

[0014] Preferably, the initiator is azobisisobutyronitrile or benzoyl peroxide, the polymerization temperature is 80-85° C., and the reaction time is 5-6 hours.

[0015] The emulsifier is used to emulsify and disperse N,N'-dinitrosopentamethylenetetramine. Preferably, the emulsifier is fatty alcohol polyoxyethylene ether and disodium salt of alkyl sulfosuccinate monoester.

[0016] The organic solvent is used to dissolve N,N'-dinitrosopentamethylenetetramine, styrene, isooctyl acrylate, dimethyl maleate and the initiator. Preferably, the organic solvent is ethyl acetoacetate.

[0017] Invention mechanism: Microcapsules refer to the use of natural or synthetic polymer coating materials to encapsulate solids, liquids or gases with a certain degree of dispersion to form tiny particles with a distinct "core-shell" structure. N,N'-dinitrosopentamethylenetetramine foaming agent is loaded into a uniform and dense polystyrene resin-based polymer shell material to achieve microencapsulation. After the N,N'-dinitrosopentamethylenetetramine foaming agent is microencapsulated, it can be isolated from the external environment, effectively protecting its original physical and chemical properties and stability from the influence and destruction of the external environment.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) by encapsulating the N,N'-dinitrosopentamethylenetetramine foaming agent into a uniform and dense polystyrene resin-based polymer shell material, the storage stability, use and transportation safety of the N,N'-dinitrosopentamethylenetetramine foaming agent are effectively improved; (2) the foaming agent microcapsule encapsulation rate is high (≥96%) and the storage stability is good. At the same time, its production cost is controlled within a relatively low range and can be widely used in actual production; (3) the preparation method is simple, environmentally friendly and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an optical microscope characterization image of the foaming agent microcapsule composite material prepared in Example 1 of the present invention;

[0020] Figure 2 This is an optical microscope characterization picture of the foaming agent microcapsule composite material prepared in Example 1 of the present invention after being stored at room temperature for 6 months. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with embodiments.

[0022] Example 1

[0023] The foaming agent microcapsule composite material of the present invention comprises the following steps:

[0024] (1) By weight, 4 parts of N,N'-dinitrosopentamethylenetetramine, 4 parts of styrene, 1 part of isooctyl acrylate, 0.5 parts of dimethyl maleate, 0.1 parts of initiator azobisisobutyronitrile and 6 parts of organic solvent ethyl acetoacetate are used to form an oil phase; 82.9 parts of deionized water, 1 part of fatty alcohol polyoxyethylene ether and 0.5 parts of alkyl sulfosuccinic acid monoester disodium salt are used to form a water phase; the oil phase is dispersed in the water phase, and emulsified for 5 minutes by a high-speed emulsifier (25000 rpm) to form a stable O / W system;

[0025] (2) The temperature was raised to 85° C. to allow the O / W system to undergo a polymerization reaction for 5 hours. The product was centrifuged for 1 minute in a high-speed centrifuge (2000 rpm) to obtain a solid material, which was the N,N′-dinitrosopentamethylenetetramine foaming agent microcapsule composite material.

[0026] from Figure 1 It can be seen that the prepared foaming agent microcapsules are spherical in shape, have an obvious "core-shell" structure and have good dispersion properties.

[0027] Example 2

[0028] (1) By weight, 4.5 parts of N,N'-dinitrosopentamethylenetetramine, 5 parts of styrene, 2 parts of isooctyl acrylate, 0.5 parts of dimethyl maleate, 0.2 parts of initiator azobisisobutyronitrile and 8 parts of organic solvent ethyl acetoacetate are used to form an oil phase; 78.3 parts of deionized water, 1 part of fatty alcohol polyoxyethylene ether and 0.5 parts of alkyl sulfosuccinic acid monoester disodium salt are used to form a water phase; the oil phase is dispersed in the water phase, and emulsified for 5 minutes by a high-speed emulsifier (25000 rpm) to form a stable O / W system;

[0029] (2) The temperature was raised to 85° C. to allow the O / W system to undergo a polymerization reaction for 5 hours. The product was centrifuged for 1 minute in a high-speed centrifuge (2000 rpm) to obtain a solid material, which was the N,N′-dinitrosopentamethylenetetramine foaming agent microcapsule composite material.

[0030] Example 3

[0031] (1) By weight, 5 parts of N,N'-dinitrosopentamethylenetetramine, 6 parts of styrene, 2 parts of isooctyl acrylate, 1.5 parts of dimethyl maleate, 0.2 parts of initiator azobisisobutyronitrile and 10 parts of organic solvent ethyl acetoacetate are used to form an oil phase; 71.8 parts of deionized water, 2 parts of fatty alcohol polyoxyethylene ether and 1.5 parts of alkyl sulfosuccinic acid monoester disodium salt are used to form a water phase; the oil phase is dispersed in the water phase, and emulsified for 5 minutes by a high-speed emulsifier (25000 rpm) to form a stable O / W system;

[0032] (2) The temperature was raised to 85° C. to allow the O / W system to undergo polymerization reaction for 6 hours. The product was centrifuged for 1 minute in a high-speed centrifuge (2000 rpm) to obtain a solid material, which was the N,N′-dinitrosopentamethylenetetramine foaming agent microcapsule composite material.

[0033] Performance Testing

[0034] (1) Test on the encapsulation efficiency of foaming agent microcapsules

[0035] The encapsulation rate of the foaming agent microcapsule of the present invention is determined by centrifugal separation combined with quantitative analysis by GC-MS instrument. The product after 6 hours of polymerization reaction of the O / W system is centrifuged for 1 minute by a high-speed centrifuge (2000rpm), and the solid material is taken out. The remaining liquid component is qualitatively and quantitatively analyzed for the content of N, N'-dinitrosopentamethylenetetramine by GC-MS instrument. Finally, the content of N, N'-dinitrosopentamethylenetetramine in the remaining liquid component, represented as (Wr), and the initial addition amount of N, N'-dinitrosopentamethylenetetramine, represented as Wm, are converted by the following formula to obtain the encapsulation rate of the foaming agent microcapsule, represented as (Em).

[0036]

[0037] The encapsulation rates of Examples 1 to 3 were 96.4%, 96.9%, and 98.2%, respectively.

[0038] (2) Safety performance test of foaming agent

[0039] Whether the foaming agent microcapsules have good storage stability is a key factor in evaluating whether the microcapsules can be used in industrialization. The present invention investigates the storage stability of microcapsule samples by optical microscopy characterization. The morphology and dispersibility of the microcapsule samples after storage at room temperature for 6 months are shown in Figure 2. Figure 2 shown.

[0040] Will Figure 2 and Figure 1 By comparison, it can be seen that the microcapsule sample still has good dispersibility after being stored at room temperature for 6 months, and there is no obvious damage or morphological change, indicating that the microcapsules prepared by the present invention have good storage stability.

Claims

1. A foaming agent microcapsule composite material, characterized in that: The invention has a core-shell structure, wherein the core is N,N'-dinitrosopentamethylenetetramine and the shell is formed by polymerization of styrene, isooctyl acrylate and dimethyl maleate; the mass ratio of styrene, isooctyl acrylate and dimethyl maleate in the shell is 4-6:1-2:0.5-1.

5.

2. The foaming agent microcapsule composite material according to claim 1, characterized in that: The mass ratio of the inner core to the outer shell is 4-5:5.5-9.

5.

3. A method for preparing the foaming agent microcapsule composite material according to claim 1 or 2, characterized in that: The following steps are involved: (1) dispersing an oil phase consisting of N,N'-dinitrosopentamethylenetetramine, an organic solvent, styrene, isooctyl acrylate, dimethyl maleate and an initiator in a water phase consisting of water and an emulsifier to form a stable O / W system; (2) The temperature of the O / W system is raised to carry out a polymerization reaction. After the reaction is completed, a solid material is obtained, which is the N,N'-dinitrosopentamethylenetetramine foaming agent microcapsule composite material.

4. The method for preparing the foaming agent microcapsule composite material according to claim 3, characterized in that: The initiator is azobisisobutyronitrile or benzoyl peroxide, the polymerization temperature is 80-85° C., and the reaction time is 5-6 hours.

5. The method for preparing the foaming agent microcapsule composite material according to claim 3, characterized in that: The emulsifiers are fatty alcohol polyoxyethylene ether and disodium salt of alkyl sulfosuccinate monoester.

6. The method for preparing the foaming agent microcapsule composite material according to claim 3, characterized in that: The organic solvent is ethyl acetoacetate.

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