Nitrosamine-free balloon and preparation process thereof

Abstract

The invention relates to a nitrosamine-free balloon and a preparation method thereof, and belongs to the technical field of balloon products. In order to solve the problem that nitrosamine is easily generated by using a vulcanization accelerator in the traditional latex balloon, the balloon disclosed by the invention adopts a double-layer composite structure, the inner layer is a natural latex / waterborne polyurethane composite film containing a coupling agent and an acrylic acid hydroxyl compound, and the outer layer is a waterborne polyurethane protective layer film; according to the technology, active groups decomposed by a silane coupling agent are used for promoting cross-linking of sulfur and rubber, and chemical bond cross-linking is formed through surface hydroxyl groups, latex protein and polyurethane groups; the balloon product prepared by utilizing a cross-linking mechanism of reaction of a hydroxyl acrylic acid compound with carboxyl in latex and carbamate of polyurethane and matching with an impregnation process is free of nitrosamine. According to the technology, amine-containing vulcanization accelerators such as thiazoles and thiurams are completely abandoned, and nitrosamine generation is completely eradicated from the source.

Description

Technical Field

[0001] The present invention relates to the technical field of balloon preparation, in particular to a nitrosamine-free balloon and its preparation process. Background Art

[0002] Rubber vulcanization accelerators are substances that can promote the vulcanization process and mainly play a role in improving the physical and mechanical properties of rubber. However, the accelerators commonly used in the current rubber industry will decompose to produce secondary amines during the vulcanization process, and the secondary amines will further react to form nitrosamines. Nitrosamines enter the body through inhalation, digestion, skin absorption, etc., inducing cancer and causing malignant tumors and chronic tumors in various organs of humans and animals.

[0003] In order to prevent the harm of nitrosamines to the human body, Europe has formulated relevant regulations and standards for the toxic and harmful substances that may be produced in rubber products. The European Union stipulates that the total content of N-nitrosamines in rubber shall not exceed 0.01 mg per kilogram.

[0004] To solve the problem of nitrosamine production, researchers have invented a natural latex peroxide vulcanization system and a radiation vulcanization system. Neither of these two vulcanization systems uses conventional accelerators and will not form nitrosamines. However, when using the peroxide vulcanization system and radiation vulcanization technology to vulcanize natural latex, the cross-linking bonds formed between rubber molecular chains are carbon-carbon single bonds. Although no nitrosamines are produced, the cross-linking density is low and the mechanical properties of the products are poor. So far, neither of these two technologies can be widely applied.

[0005] CN103951698 B discloses a vulcanization accelerator for rubber - thiophosphate, which is safe and non-toxic. The thiophosphate accelerator does not contain nitrogen elements, does not produce nitrosamines, and at the same time has a good vulcanization promoting effect. However, during the use process, it has an uncontrollable thickening and gelling phenomenon on natural latex emulsion, seriously affecting the operation of the production line.

[0006] The problem of nitrosamine production in latex balloon products is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of the above deficiencies, the balloon of this application adopts a double-layer composite structure. The inner layer is a natural latex / waterborne polyurethane composite film containing a coupling agent and a hydroxy acrylic compound, and the outer layer is a waterborne polyurethane protective layer. The active groups decomposed by the silane coupling agent promote the cross-linking of sulfur and rubber, and the surface hydroxyl groups form chemical bonds with latex protein and polyurethane groups. By using the reaction cross-linking mechanism of hydroxy acrylic compounds with carboxyl groups in latex and urethane groups in polyurethane, the balloon products obtained by combining the dipping process do not contain nitrosamines. This technology completely abandons amine-containing vulcanization accelerators such as thiazoles and thiurams, eliminating the generation of nitrosamines from the source.

[0008] An environmentally friendly double-layer composite structure balloon without nitrosamine, characterized in that: the inner layer is a natural latex / waterborne polyurethane composite film containing a coupling agent and an acrylic hydroxy compound, and the outer layer is a waterborne polyurethane film layer; its preparation method includes: Step 1: Prepare pre-vulcanized natural rubber latex: composed of 90-100% natural rubber latex, 0.1-2% sulfur, 0.1-2% zinc oxide, 0.1-1% antioxidant, 0.1-1% potassium hydroxide, and 0.1-0.3% surfactant; Step 2: Prepare the composite inner layer emulsion: 10-100% pre-vulcanized natural rubber latex, 0.1-10% silane coupling agent, 1-20% acrylic hydroxy compound, 10-100% waterborne polyurethane emulsion; Step 3: Prepare the outer layer emulsion: 90-100% waterborne polyurethane emulsion, 1-10% crosslinking agent, 0.1-2% wetting agent, 0.1-2% defoaming agent; Step 4: Prepare by dipping process: mold cleaning → drying → dipping coagulant → drying → dipping the emulsion in step b → drying → dipping the emulsion in step c → drying → curling → drying → demolding.

[0009] Further, the pre-vulcanized natural rubber latex is composed of 90-100% natural rubber latex, 0.1-2% sulfur, 0.1-2% zinc oxide, 0.1-1% antioxidant, 0.1-1% potassium hydroxide, and 0.1-0.3% surfactant. After stirring evenly and pre-vulcanizing, the pre-vulcanization temperature is 45-65°C, and the chloroform value reaches three ends and four beginnings.

[0010] Further, the silane coupling agent is any one or several of γ-aminopropyltriethoxysilane (coupling agent KH-560), γ-glycidoxypropyltrimethoxysilane (coupling agent 570), γ-methacryloxypropyltrimethoxysilane (KH-590), γ-mercaptopropyltrimethoxysilane (silane coupling agent KH-590), γ-mercaptopropylethoxybis(propylalkyl-hexaethoxysiloxane) (Si 747), bis-[γ-(triethoxysilyl)propyl]-disulfide (Si 75), and bis(γ-triethoxysilylpropyl)tetrasulfide (silane coupling agent Si-69), etc. The addition method is after hydrolysis or after emulsification.

[0011] Further, the mass ratio of the silane coupling agent to the acrylic hydroxy compound in the composite inner layer emulsion is 1:1-1:5.

[0012] Further, the coagulating liquid is a calcium nitrate type coagulating liquid or a calcium chloride type coagulant. The calcium nitrate type coagulant is an aqueous solution containing 5-30% calcium nitrate, 0.1-0.5% wetting agent, 5-10% mold release agent, and 0.1-1% defoaming agent; the calcium chloride type coagulant is an aqueous solution containing 5-30% calcium nitrate, 0.1-0.5% wetting agent, 5-10% mold release agent, and 0.1-1% defoaming agent.

[0013] Further, the aqueous polyurethane emulsion contains 1-10% cross-linking agent, 0.1-2% wetting agent, and 0.1-2% defoaming agent, and is an outer layer dipping emulsion.

[0014] Further, dip the dried balloon mold into the natural latex / aqueous polyurethane composite film latex containing a coupling agent and a hydroxy acrylic compound, take it out after staying for 10-60 seconds, and dry the balloon mold at a temperature of 55-75°C for 1-5 minutes.

[0015] Further, dip the baked balloon mold into the aqueous polyurethane emulsion, take it out after staying for 10-60 seconds, and heat the balloon mold at 60-90°C for 1-3 minutes.

[0016] Further, perform mechanical curling on the baked balloon mold, and the curling is subjected to hot water leaching for 3 minutes at a water temperature of 50-80°C. Dry the balloon mold containing the composite latex after leaching at 90-120°C for 10-60 minutes.

[0017] Further, perform gas stripping or water stripping on the dried balloon mold containing the composite latex to obtain a composite balloon.

[0018] The beneficial effects of the present invention are as follows.

[0019] The present invention does not use conventional rubber vulcanization accelerators, does not generate nitrosamines, and is beneficial to personnel and the environment; a balloon product is obtained by combining a double dipping process, with low cost, and solves the problem of industrial production. Specific embodiments

[0020] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in combination with the preferred embodiments of the specification. However, the protection scope of the present invention is not limited to the following specific embodiments. Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0021] Example 1 I. Configuration of raw materials (taking 100 kg as an example, all are commercially available products unless otherwise specified) Step 1: Prepare a natural latex / aqueous polyurethane mixed emulsion containing a coupling agent and a hydroxy acrylic compound In proportion, 71.7% natural rubber latex, 5% hydroxyethyl acrylate, 1% silane coupling agent Si-69, 1% sulfur, 0.5% zinc oxide, 0.5% antioxidant 616, 0.2% potassium hydroxide, 0.1% surfactant, 20% aqueous polyurethane emulsion; after mixing the above raw materials evenly, filter and pre-vulcanize. The vulcanization temperature is 50°C, and the chloroform value is three ends and four beginnings. After meeting the numerical requirements, reserve for use; Step 2: Prepare an aqueous polyurethane mixed emulsion In proportion, 96.5% aqueous polyurethane emulsion with a solid content of 30%, 2% polycarbodiimide, 1% wetting agent polyether-modified silicone, 0.5% defoaming agent; after mixing the above raw materials evenly, filter and reserve for use.

[0022] Step 3: Prepare a coagulant aqueous solution In proportion, 15% calcium nitrate, 0.2% defoaming agent, 0.2% wetting agent, 20% aqueous calcium stearate emulsion, 64.6% water; after mixing the above raw materials evenly, filter and reserve for use.

[0023] II. Production process Clean the balloon mold with an acid-base cleaning agent; transfer it to an oven and dry it at 70°C for 30 seconds, then immerse the balloon mold in the coagulant aqueous solution pool composed of 3 for 10 seconds; transfer it to the oven and bake at 70°C for 30 seconds. After the surface of the coagulant is dry, take it out; immerse it in the mixed emulsion pool composed of 1 natural latex / aqueous polyurethane mixed emulsion containing a coupling agent and a hydroxy acrylic compound for 10 seconds and take it out; transfer it to the oven and bake at 60°C for 3 minutes and take it out, then immerse it in the 2 aqueous polyurethane mixed emulsion pool, stay for 10 seconds and take it out; transfer it to the oven and dry it at 65°C for 7 minutes and then crimp. After crimping, immerse it in the leaching pool composed of pure water at 80°C for 3 minutes and take it out, transfer it to the oven and bake at 100°C for 50 minutes. After the composite film is completely dry, demold to obtain a nitrite-free balloon product.

[0024] Example 2 I. Preparation of raw materials (taking 100 kg as an example, all are commercially available products unless otherwise specified) Step 1: Prepare a natural latex / aqueous polyurethane mixed emulsion containing a coupling agent and a hydroxy acrylic compound According to the proportion, pre-vulcanized natural rubber latex 64.7%, hydroxypropyl acrylate 1.5%, silane coupling agent Si-75 1.5%, sulfur 1%, zinc oxide 0.5%, antioxidant 2264 0.5%, potassium hydroxide 0.2%, surfactant 0.1%, waterborne polyurethane emulsion 30%; After mixing the above raw materials evenly, filter and then pre-vulcanize at a vulcanization temperature of 45°C, with the chloroform value being three at the end and four at the beginning. After meeting the numerical requirements, set aside for use; Step 2: Waterborne polyurethane mixed emulsion According to the proportion, waterborne polyurethane with a solid content of 20% 98.5%, aziridine 1%, polyether-modified silicone wetting agent 0.5%; After mixing the above raw materials evenly, filter and then set aside for use.

[0025] Step 3: Aqueous coagulant solution According to the proportion, 15% calcium chloride, 0.2 defoamer, 0.2% wetting agent, 10% calcium stearate, 74.6%. After mixing the above raw materials evenly, filter and then set aside for use.

[0026] II. Production process Clean the balloon mold alternately with acidic and alkaline cleaning agents, then take it out and transfer it to an oven. After drying at 70°C for 30 seconds, immerse the balloon mold in the aqueous coagulant solution pool composed of 3 for 10 seconds and then take it out; Transfer it to the oven and bake at 70°C for 30 seconds. After the surface of the coagulant is dry, take it out; Immerse it in the natural latex / waterborne polyurethane mixed emulsion pool of coupling agent and acrylic hydroxy compound for 10 seconds and then take it out; Transfer it to the oven and bake at 65°C for 3 minutes and then take it out. Immerse it in the waterborne polyurethane mixed emulsion pool composed of 2 and stay for 10 seconds and then take it out; Transfer it to the oven, dry at 80°C for 4 minutes and then crimp the edge. After crimping, immerse it in the leaching pool composed of 80°C pure water for 3 minutes and then take it out. Transfer it to the oven and bake at 110°C for 45 minutes. After the composite film is completely dry, demold to obtain nitrite-free balloon products.

[0027] Example 3. I. Preparation of raw materials (taking 100 kg as an example, all are commercially available products unless otherwise specified) Step 1: Prepare a natural latex / waterborne polyurethane mixed emulsion containing a coupling agent and an acrylic hydroxy compound According to the proportion: pre-vulcanized natural rubber latex 67.7%, hydroxyethyl acrylate 8%, silane crosslinking agent 590 2%, sulfur 1%, zinc oxide 0.5%, antioxidant 264 0.5%, potassium hydroxide 0.2%, surfactant 0.1%, waterborne polyurethane emulsion 20%; After mixing the above raw materials evenly, filter and then pre-vulcanize at a vulcanization temperature of 55°C, with the chloroform value being three at the end and four at the beginning. After meeting the numerical requirements, set aside for use; Step 2: Waterborne polyurethane mixed emulsion By proportion: 20% solid content of waterborne polyurethane 98.5%, polyisocyanate 1%, polyether-modified silicone wetting agent 0.5%; Mix the above raw materials evenly, filter, and reserve for later use. Step 3: Prepare the coagulant aqueous solution By proportion: 20% calcium nitrate, 0.2% wetting agent, 10% diatomaceous earth, 69.8% water; Mix the above raw materials evenly, filter, and reserve for later use. II. Production process Clean the balloon mold with a cleaning agent and take it out; Transfer it to an oven, dry it at 70°C for 30 seconds, then immerse the balloon mold in the coagulant aqueous solution pool composed of 3 for 10 seconds; Transfer it to the oven and bake at 70°C for 30 seconds. After the surface of the coagulant is dry, take it out; Immerse it in the mixed emulsion pool composed of the mixed emulsion of natural latex / waterborne polyurethane of 1 coupling agent and acrylic hydroxy compound for 10 seconds and take it out; Transfer it to the oven and bake at 60°C for 3 minutes and take it out, immerse it in the mixed emulsion pool composed of 2 waterborne polyurethane, stay for 10 seconds and then take it out; Transfer it to the oven and dry it at 75°C for 5 minutes and then crimp. After crimping, immerse it in the leaching pool containing 80°C pure water for 3 minutes and take it out, transfer it to the oven and bake at 100°C for 50 minutes. After the composite film is completely dry, demold to obtain the nitrite-free balloon product.

[0028] Comparative example 1 Clean the balloon mold with a cleaning agent and take it out; Transfer it to an oven, dry it at 70°C for 30 seconds, then immerse the balloon mold in the aqueous solution composed of 15% calcium chloride, 0.2% defoaming agent, 0.2% wetting agent and 20% diatomaceous earth for 10 seconds; Transfer it to the oven and bake at 70°C for 30 seconds. After the surface of the coagulant is dry, take it out; Immerse it in the mixed latex pool composed of 97.2% pre-vulcanized natural rubber latex, 0.5% accelerator ZDC, 1% sulfur, 0.5% zinc oxide, 0.5% antioxidant, 0.2% potassium hydroxide, 0.1% surfactant for 10 seconds and take it out; Transfer it to the oven and dry it at 75°C for 6 minutes and then crimp. After crimping, immerse it in the leaching pool containing 80°C pure water for 3 minutes and take it out, transfer it to the oven and bake at 110°C for 45 minutes. After the composite film is completely dry, demold to obtain the natural latex balloon product.

[0029] Comparative example 2 Take out the balloon mold after cleaning it with a cleaning agent; transfer it to an oven, dry it at 70°C for 30 seconds, then immerse the balloon mold in an aqueous solution composed of 15% calcium nitrate, 0.2% defoamer, 0.2% wetting agent, and 20% diatomaceous earth for 10 seconds; transfer it to the oven and bake at 70°C for 30 seconds, take it out after the surface of the coagulant is dry; immerse it in a mixed latex pool composed of 95.7% pre-vulcanized natural rubber latex, 1% accelerator ZDC, 1% sulfur, 1% zinc oxide, 1% antioxidant, 0.2% potassium hydroxide, and 0.1% surfactant for 10 seconds and then take it out; transfer it to the oven and dry it at 75°C for 6 minutes and then crimp it. After crimping, immerse it in a leaching pool containing pure water at 65°C for 3 minutes and then take it out. Transfer it to the oven and bake at 105°C for 45 minutes. After the composite film is completely dry, demold it to obtain a natural latex balloon product.

[0030] Refer to the national standard GB / T528-2009 to measure the physical and mechanical properties of the finished balloons in Examples 1 to 4 and Comparative Examples 1-2 before and after aging, and refer to the EU EN71-12 for the determination method of nitrosamine content. The results are shown in Table 1: 。

[0031] Judging from the results in Table 1, no nitrosamine was detected in the balloons produced by the present invention. The nitrosamine content in the comparative examples is much higher than the EU standard. The comprehensive performance of the balloons of the present invention is superior to that of natural rubber balloons.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A double-layer composite structure balloon without nitrosamine, characterized in that: The inner layer is a natural latex / aqueous polyurethane composite film containing a coupling agent and an acrylic hydroxy compound, and the outer layer is an aqueous polyurethane film layer; its preparation method includes: a. Prepare pre-vulcanized natural rubber latex: It is composed of 90 - 100% natural rubber latex, 0.1 - 2% sulfur, 0.1 - 2% zinc oxide, 0.1 - 1% antioxidant, 0.1 - 1% potassium hydroxide, and 0.1 - 0.3% surfactant; b. Prepare the composite inner layer emulsion: 10 - 100% pre-vulcanized natural rubber latex, 0.1 - 10% silane coupling agent, 1 - 20% acrylic hydroxy compound, 10 - 100% aqueous polyurethane emulsion; c. Prepare the outer layer emulsion: 90 - 100% aqueous polyurethane emulsion, 1 - 10% crosslinking agent, 0.1 - 2% wetting agent, 0.1 - 2% defoaming agent; d. Preparation by dipping process: Mold cleaning → drying → dipping in coagulant → drying → dipping in the emulsion of step b → drying → dipping in the emulsion of step c → drying → curling → drying → demolding.

2. The composition according to claim 1, wherein the silane coupling agent is any one or several of γ-aminopropyltriethoxysilane (coupling agent KH-560), γ-glycidoxypropyltrimethoxysilane (coupling agent 570), γ-methacryloxypropyltrimethoxysilane (KH-590), γ-mercaptopropyltrimethoxysilane (silane coupling agent KH-590), γ-mercaptopropylethoxybis(propylalkyl-hexaethoxysiloxane) (Si 747), bis-[γ-(triethoxysilyl)propyl]-disulfide (Si 75), and bis(γ-triethoxysilylpropyl)tetrasulfide (silane coupling agent Si-69), etc. The addition method is after hydrolysis or after emulsification.

3. The acrylic hydroxy compound in the composition according to claim 1 is hydroxyethyl acrylate and hydroxybutyl acrylate.

4. In the composite inner layer emulsion of the composition according to claim 1, the mass ratio of the silane coupling agent to the acrylic hydroxy compound is 1:1 - 1:5.