Preparation method of styrene-butadiene rubber latex adhesive for metal surface printing

Abstract

The present invention provides a preparation method of a styrene-butadiene rubber latex adhesive for metal surface printing. After the reaction kettle is evacuated, water, part of emulsifier A, emulsifier B and initiator A are added, the temperature is raised, and part of styrene is added for free radical emulsion polymerization reaction; then the remaining emulsifier A, emulsifier B, initiator A, styrene, and part of butadiene are added dropwise for reaction; then initiator B, ester functional monomer, crosslinking monomer, and the remaining butadiene are added dropwise to continue the reaction; after the reaction is completed, the temperature is lowered to room temperature, the pH value of the emulsion is adjusted with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing is obtained; emulsifier A is an anionic emulsifier, emulsifier B is a reactive emulsifier, initiator A is a persulfate initiator, and initiator B is an oil-soluble initiator. The present invention adopts a three-step stepwise polymerization method to synthesize a latex structure with a three-layer coating structure, which has good metal affinity and high-temperature yellowing resistance performance.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a preparation method of a styrene-butadiene rubber latex adhesive for metal surface printing. Background Art

[0002] The metal surface printing process, different from the traditional spray painting process, mainly uses the method of rubber cloth transfer to transfer the required target pattern to the surface of metal profiles (generally stainless steel plates or iron plates), and then dries the printed pattern through a high-temperature drying device. The above metal surface printing process, compared with the traditional spray painting process, has the advantages of fast printing speed, a wide variety of pattern types, bright colors, high printing clarity, no volatile toxic and harmful substances such as thinner, and is safe, environmentally friendly and pollution-free. At present, most of the metal surface printing processes on the market adopt the form of offset printing - first spray a layer of adhesive on the metal surface for bonding the printed pattern, and then transfer the printed pattern to the surface of the adhesive. Therefore, the performance of the adhesive plays a crucial role in the metal surface printing process.

[0003] At present, most of the adhesives for metal surface printing on the market adopt acrylate adhesives. Although this type of adhesive has excellent adhesion, its high-temperature resistance ability is poor, and it is easy to turn yellow during the high-temperature drying process, deepening the color of the coating, seriously affecting the display effect of light-colored printed patterns. At the same time, the affinity of this type of adhesive with the metal coating is slightly poor, and over time, the printed pattern on the metal surface is likely to fall off. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a styrene-butadiene rubber latex adhesive for metal surface printing, which has good metal affinity and can adhere to the surface of metal profiles for a long time, thereby solving the above technical problems existing in the prior art.

[0005] The present invention is implemented by adopting the following technical solutions:

[0006] A preparation method of a styrene-butadiene rubber latex adhesive for metal surface printing, comprising the following steps:

[0007] S1. After the reaction kettle is evacuated, add water, part of emulsifier A, emulsifier B and initiator A, heat up to 60 - 85°C, dropwise add part of styrene monomer, and carry out free radical emulsion polymerization reaction for 2 - 5 hours. Then heat up to 70 - 90°C and keep warm for 0.5 - 2 hours;

[0008] S2. After the heat preservation is completed, simultaneously dropwise add the remaining emulsifier A, emulsifier B, initiator A, styrene, and part of butadiene, control the reaction temperature at 65 - 85°C, continuously react for 3 - 8 hours, and keep warm for 1 - 4 hours;

[0009] S3. After the heat preservation is completed, initiator B, ester functional monomer, crosslinking monomer, and the remaining butadiene are simultaneously added dropwise, and the reaction temperature is controlled at 55 - 80 °C, and the reaction continues for 2 - 6 hours, followed by heat preservation for 2 - 5 hours;

[0010] S4. After the reaction is completed, the temperature is lowered to room temperature (about 25 °C), and the pH value of the emulsion is adjusted to 5 - 9 with an alkaline substance. After filtration, the styrene - butadiene rubber latex adhesive for metal surface printing is obtained;

[0011] The emulsifier A is an anionic emulsifier, the emulsifier B is a reactive emulsifier, the initiator A is a persulfate initiator, and the initiator B is an oil - soluble initiator.

[0012] Preferably, the emulsifier A is selected from at least one of sodium alkyl sulfate, sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium alkyl diphenyl ether disulfonate, ammonium alkyl phenol ether sulfate, and sodium alkyl phenol ether sulfosuccinate. The alkyl group is preferably a C8 - C 18 alkyl group, more preferably a C8 - C 16 alkyl group, and most preferably a C8 - C 14 sodium alkyl sulfate, C8 - C 14 sodium alkyl sulfonate, C8 - C 14 sodium alkyl benzene sulfonate, C8 - C 14 sodium alkyl diphenyl ether disulfonate, C8 - C 14 ammonium alkyl phenol ether sulfate, C8 - C 14 at least one of sodium alkyl phenol ether sulfosuccinate. As a further preferred option, the alkyl group of the emulsifier A selected in the present invention is a dodecyl group.

[0013] Preferably, the emulsifier B is selected from at least one of sodium p - styrene sulfonate, sodium 2 - acrylamide - 2,2 - dimethyl ethanesulfonate, sodium allyl succinic acid alkyl ester sulfonate, sodium acrylamido isopropyl sulfonate, and sodium 2 - ethyl sulfonate of alkyl acrylate. The alkyl group in the sodium 2 - ethyl sulfonate of alkyl acrylate is preferably a C 10 -C 18 alkyl group, and most preferably a C 12 -C 18 sodium 2 - ethyl sulfonate of alkyl acrylate. As a further preferred option, the emulsifier B selected in the present invention is sodium 2 - ethyl sulfonate of hexadecyl acrylate.

[0014] Preferably, the initiator A is selected from at least one of sodium persulfate, ammonium persulfate, and potassium persulfate.

[0015] Preferably, the initiator B is selected from tert - butyl hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, azobisisobutyronitrile, and azobisisoheptonitrile. As a further preferred option, the initiator B more preferably selected in the present invention is cumene hydroperoxide.

[0016] Preferably, the ester functional monomer is selected from at least one of n-propyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-pentyl acrylate, dimethyl vinyl phosphate, and dimethyl vinyl phosphonate. As a further preferred embodiment, the ester functional monomer of the present invention is more preferably dimethyl vinyl phosphonate.

[0017] Preferably, the crosslinking monomer is selected from at least one of 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-ethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate.

[0018] Preferably, the basic substance is selected from at least one of alkali metal hydroxides.

[0019] As a preferred technical solution, the amounts of each component are as follows by weight parts: 0.8 - 2.1 parts of emulsifier A, 0.5 - 1.7 parts of emulsifier B, 0.5 - 5 parts of initiator A, 0.05 - 1 part of initiator B, 10 - 20 parts of styrene, 15 - 30 parts of butadiene, 15 - 25 parts of ester functional monomer, 2 - 5 parts of crosslinking monomer, 3 - 8 parts of basic substance, and an appropriate amount of deionized water.

[0020] Preferably, in step S1, the addition amount of emulsifier A is 50% - 100% of its total amount, the addition amount of emulsifier B is 0% - 70% of its total amount, the addition amount of initiator A is 20% - 100% of its total amount, and the addition amount of styrene is 35% - 95% of its total amount; in step S2, the addition amount of butadiene is 30% - 70% of its total amount.

[0021] Wherein water is used to disperse each component, and those skilled in the art can easily adjust the amount of water according to the actual use needs of the product. Preferably 70 - 100 parts.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] A three-step stepwise polymerization method is adopted to synthesize a latex structure with a three-layer coating structure. Among them, the polystyrene homopolymer with relatively high hardness is located in the innermost layer of the latex structure, so that when the latex particles are coated on the metal surface, it provides better support for printing and prevents large deformation of the coating during printing; the butadiene-styrene copolymer is wrapped outside the polystyrene core to form an intermediate connection layer. This layer of copolymer has good toughness, enabling the adhesive coating to withstand a certain amount of pressure during the printing process and preventing the coating from cracking due to excessive printing pressure. At the same time, this layer contains both styrene and butadiene structures, which can play a role in connecting the core and the outermost layer; the copolymer of butadiene, ester functional monomers and crosslinking monomers is coated on the outermost layer of the latex particles, providing adhesion to the metal surface. Since ester monomers, especially phosphate esters, will undergo chemical reactions with the metal surface layer, through this reaction, phosphate groups can form a strong chemical layer with the metal surface, playing a role in enhancing the adhesion of the adhesive on the metal surface.

[0024] At the same time, the polystyrene homopolymer core has a relatively high glass transition temperature. During printing, it can absorb a large amount of heat without significant deformation. In addition, the benzene ring structure that is prone to yellowing is coated in the innermost layer of the latex particles, which largely solves the problem of yellowing of the adhesive at high temperatures. Specific implementation mode

[0025] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples and do not limit the scope of the present invention. Those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other implementation schemes, deformation schemes, improvement schemes, equivalent schemes, and other technical schemes that do not depart from the spirit and scope of the present invention.

[0026] In the present invention, if the instruments or raw materials are not specified for the manufacturer, they are all conventional commercial instruments or raw materials. Among them, emulsifier A is sodium dodecyl sulfate, emulsifier B is sodium 2-ethylhexyl acrylate sulfonate, initiator A is sodium persulfate, initiator B is cumene hydroperoxide, ester functional monomer is dimethyl vinyl phosphate, crosslinking monomer is 1,3-butanediol dimethacrylate, and the basic substance is sodium hydroxide.

[0027] If the detection indexes involved in the embodiments of the present invention are not mentioned, they are all detected by conventional detection methods in the art.

[0028] Example 1

[0029] Step 1: After evacuating the reactor, add 70 g of deionized water, 1.5 g of emulsifier A, 0.9 g of emulsifier B, and 3 g of initiator A. Start the reaction stirring and raise the reaction temperature in the reactor to 85 °C. Dropwise add 13 g of styrene monomer and start the free radical emulsion polymerization reaction. The reaction time is 2.5 hours. Raise the reaction temperature to 90 °C and keep it at this temperature for 0.5 hour.

[0030] Step 2: After the insulation in "Step 1" ends, simultaneously dropwise add 0.3 g of emulsifier A, 0.5 g of emulsifier B, 2 g of initiator A, 5 g of styrene, and 20 g of butadiene. Control the reaction temperature at 65 °C and continue the reaction for 7 hours. Keep it at this temperature for 2.5 hours.

[0031] Step 3: After the insulation in "Step 2" ends, simultaneously dropwise add 0.5 g of initiator B, 18 g of ester functional monomer, 2.1 g of crosslinking monomer, and 12 g of butadiene. Control the reaction temperature at 80 °C and continue the reaction for 2 hours. Keep it at this temperature for 2.5 hours.

[0032] Step 4: After the reaction ends, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 7 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0033] Example 2

[0034] Step 1: After evacuating the reactor, add 100 g of deionized water, 2.1 g of emulsifier A, 0 g of emulsifier B, and 3 g of initiator A. Start the reaction stirring and raise the reaction temperature in the reactor to 65 °C. Dropwise add 15 g of styrene monomer and start the free radical emulsion polymerization reaction. The reaction time is 2 hours. Raise the reaction temperature to 75 °C and keep it at this temperature for 2 hours.

[0035] Step 2: After the insulation in "Step 1" ends, simultaneously dropwise add 0 g of emulsifier A, 1.5 g of emulsifier B, 1.5 g of initiator A, 5 g of styrene, and 7 g of butadiene. Control the reaction temperature at 80 °C and continue the reaction for 5 hours. Keep it at this temperature for 2 hours.

[0036] Step 3: After the insulation in "Step 2" ends, simultaneously dropwise add 1 g of initiator B, 19 g of ester functional monomer, 3 g of crosslinking monomer, and 13 g of butadiene. Control the reaction temperature at 80 °C and continue the reaction for 2.5 hours. Keep it at this temperature for 2 hours.

[0037] Step 4: After the reaction ends, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 6.5 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0038] Example 3

[0039] Step 1: After evacuating the reactor, add 95 g of deionized water, 1.6 g of emulsifier A, 1 g of emulsifier B, and 5 g of initiator A. Start the reaction stirring and raise the reaction temperature in the reactor to 60 °C. Dropwise add 17 g of styrene monomer and start the free radical emulsion polymerization reaction. The reaction time is 5 hours. Raise the reaction temperature to 90 °C and keep it warm for 0.5 hour.

[0040] Step 2: After the insulation in "Step 1" ends, simultaneously dropwise add 0.5 g of emulsifier A, 0.7 g of emulsifier B, 0 g of initiator A, 2 g of styrene, and 17 g of butadiene. Control the reaction temperature at 75 °C and continue the reaction for 6 hours. Keep it warm for 3 hours.

[0041] Step 3: After the insulation in "Step 2" ends, simultaneously dropwise add 1 g of initiator B, 15 g of ester functional monomer, 4 g of crosslinking monomer, and 10 g of butadiene. Control the reaction temperature at 80 °C and continue the reaction for 2 hours. Keep it warm for 4 hours.

[0042] Step 4: After the reaction ends, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 8.6 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0043] Example 4

[0044] Step 1: After evacuating the reactor, add 100 g of deionized water, 1.2 g of emulsifier A, 0.9 g of emulsifier B, and 0.9 g of initiator A. Start the reaction stirring and raise the reaction temperature in the reactor to 80 °C. Dropwise add 10 g of styrene monomer and start the free radical emulsion polymerization reaction. The reaction time is 4 hours. Raise the reaction temperature to 90 °C and keep it warm for 0.7 hour.

[0045] Step 2: After the insulation in "Step 1" ends, simultaneously dropwise add 0.8 g of emulsifier A, 0.5 g of emulsifier B, 3 g of initiator A, 5 g of styrene, and 16 g of butadiene. Control the reaction temperature at 76 °C and continue the reaction for 7 hours. Keep it warm for 1 hour.

[0046] Step 3: After the insulation in "Step 2" ends, simultaneously dropwise add 0.6 g of initiator B, 24 g of ester functional monomer, 4 g of crosslinking monomer, and 13 g of butadiene. Control the reaction temperature at 75 °C and continue the reaction for 3.6 hours. Keep it warm for 2.8 hours.

[0047] Step 4: After the reaction ends, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 8.4 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0048] Comparative Example 1

[0049] After the reaction kettle is evacuated, add 70 g of deionized water, 1.8 g of emulsifier A, 1.4 g of emulsifier B, 5 g of initiator A, and 0.5 g of initiator B. Start the reaction stirring and raise the reaction temperature in the kettle to 85 °C. Dropwise add 18 g of styrene monomer, 32 g of butadiene, 18 g of ester functional monomer, and 2.1 g of crosslinking monomer. Then start the free radical emulsion polymerization reaction for 10 hours and keep the temperature for 4 hours. After the reaction is completed, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 7 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0050] Comparative Example 2

[0051] Step 1: After the reaction kettle is evacuated, add 70 g of deionized water, 1.8 g of emulsifier A, 1.4 g of emulsifier B, and 5 g of initiator A. Start the reaction stirring and raise the reaction temperature in the kettle to 85 °C. Dropwise add 13 g of styrene monomer and start the free radical emulsion polymerization reaction for 2.5 hours. Then raise the reaction temperature to 90 °C and keep the temperature for 0.5 hour.

[0052] Step 2: After the insulation in "Step 1" ends, simultaneously dropwise add 0.5 g of initiator B, 18 g of ester functional monomer, 2.1 g of crosslinking monomer, and 32 g of butadiene, and control the reaction temperature at 80 °C and continue the reaction for 2 hours and keep the temperature for 2.5 hours.

[0053] Step 3: After the reaction is completed, cool down to room temperature (about 25 °C), adjust the pH value of the emulsion to 7 with an alkaline substance, and after filtration, the styrene-butadiene rubber latex adhesive for metal surface printing can be obtained.

[0054] The performance measurement results of the styrene-butadiene rubber latex adhesives for metal surface printing prepared in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0055] Table 1 Product Performance Indexes

[0056]

[0057] Among them, the determination of the bonding strength: It is determined by the determination method in the national standard GB 1742-79. The determination of the water resistance: It is determined by the determination method in the national standard GB / T1733-1993. The determination of the tensile strength of the rubber film: It is determined by the determination method in the national standard GB / T 13022-1991.

[0058] It can be seen from the above application results that: the styrene-butadiene rubber latex adhesive for metal surface printing prepared by the method of the present invention can significantly improve the bonding strength with the metal surface compared with Comparative Examples 1 and 2, and has excellent water resistance, indicating that the three-layer structure polymer composite synthesized by the three-step distribution polymerization method adopted by the present invention has more excellent application performance.

[0059] Those skilled in the art should understand that the above embodiments are only examples and do not limit the present invention. The object of the present invention has been completely and effectively achieved. The function and structural principle of the present invention have been shown and explained in the embodiments. Without departing from the above principle, any deformation or modification of the embodiments of the present invention is possible.

Claims

1. A preparation method of a styrene-butadiene rubber latex adhesive for metal surface printing, characterized in that It includes the following steps: S1. After evacuating the reactor, add water, a part of emulsifier A, emulsifier B and initiator A, heat up to 60 - 85 °C, dropwise add a part of styrene monomer, and carry out free radical emulsion polymerization reaction for 2 - 5 hours. Subsequently, heat up to 70 - 90 °C and keep warm for 0.5 - 2 hours; S2. After the heat preservation ends, simultaneously dropwise add the remaining emulsifier A, emulsifier B, initiator A, styrene, and a part of butadiene, control the reaction temperature at 65 - 85 °C, continuously react for 3 - 8 hours, and keep warm for 1 - 4 hours; S3. After the heat preservation ends, simultaneously dropwise add initiator B, ester functional monomer, crosslinking monomer, and the remaining butadiene, control the reaction temperature at 55 - 80 °C, continuously react for 2 - 6 hours, and keep warm for 2 - 5 hours; the ester functional monomer is dimethyl - vinyl phosphate; S4. After the reaction ends, cool down to room temperature, adjust the pH value of the emulsion to 5 - 9 with an alkaline substance, and after filtration, the styrene - butadiene rubber latex adhesive for metal surface printing is obtained; The emulsifier A is an anionic emulsifier, the emulsifier B is a reactive emulsifier, the initiator A is a persulfate - type initiator, and the initiator B is an oil - soluble initiator; The dosage of each component is as follows by weight parts: emulsifier A 0.8 - 2.1 parts, emulsifier B 0.5 - 1.7 parts, initiator A 0.5 - 5 parts, initiator B 0.05 - 1 part, styrene 10 - 20 parts, butadiene 15 - 30 parts, ester functional monomer 15 - 25 parts, crosslinking monomer 2 - 5 parts, alkaline substance 3 - 8 parts, and appropriate amount of deionized water; In step S1, the addition amount of emulsifier A is 50% - 100% of its total dosage, the addition amount of emulsifier B is 0% - 70% of its total dosage, the addition amount of initiator A is 20% - 100% of its total dosage, and the addition amount of styrene is 35% - 95% of its total dosage; in step S2, the addition amount of butadiene is 30% - 70% of its total dosage.

2. The method according to claim 1, characterized in that, The emulsifier A is selected from at least one of sodium alkyl sulfate, sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium alkyl diphenyl ether disulfonate, ammonium alkyl phenol ether sulfate, and sodium alkyl phenol ether sulfosuccinate; 3. The method according to claim 2, wherein The alkyl group in the emulsifier A is C8-C 18 alkyl group.

4. The method according to claim 1, wherein The emulsifier B is selected from at least one of sodium p - styrene sulfonate, 2 - acrylamide - 2,2 - dimethyl ethyl sulfonate, sodium allyl succinate alkyl ester sulfonate, sodium acrylamidopropyl sulfonate, and sodium 2 - ethyl sulfonate alkyl acrylate; 5. The method according to claim 4, wherein The alkyl group in the sodium 2-ethylsulfonate acrylate is an alkyl group of C 10 -C 18 .

6. The method according to claim 1, wherein The initiator A is selected from at least one of sodium persulfate, ammonium persulfate, and potassium persulfate; the initiator B is selected from tert - butyl hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, azobisisobutyronitrile, and azobisisoheptonitrile.

7. The method according to claim 1, characterized in that The crosslinking monomer is selected from at least one of 1,3 - butanediol dimethacrylate, 1,4 - butanediol dimethacrylate, 1,6 - hexanediol dimethacrylate, and neopentyl glycol dimethacrylate.

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