Why research environmentally friendly low-temperature water-based acrylate copolymer adhesives

The adhesive film made of polyacrylate latex has a good time, phase aging, shooting oil, and when acid and alkaline performance, and it has good sticky performance for fiber, leather, paper, etc. Therefore, latex is widely used in coatings, fabrics, and tanneries. In the fabric application, it is mainly used as a printing and dyeing adhesive, fabric coating agent, wake-up agent, anti-pilling agent, non-woven products with adhesives, etc.

The development of water-based acrylic copolymer latex has gone through three stages: non-crosslinking, crosslinking, and white crosslinking, but these crosslinking conditions are relatively freezing, requiring higher temperatures (around 160°C) and lower pH values, which wastes resources and increases the damage to the processed substrate and also releases formaldehyde substances that are harmful to humans during the application process.

water-based adhesive

To implement low-temperature cross-linking of water-based acrylate copolymer latex, some people use an additional catalyst: the use of a mixture of magnesium chloride hexahydrate and citric acid (1:1), such as Azcat A as a catalyst for two-component low-temperature curing adhesives, but the main shortcomings are the use of catalyst, more trouble, and the configuration of the product is not stable, the residual slurry can not be reused. Another way is to adopt radiation-initiated crosslinking technology, but this requires additional special equipment and is costly. There is also a reaction with epichlorohydrin to introduce a reactive epoxy group to replace the formaldehyde-releasing substance N hydroxymethyl acrylamide, but this technology brings the problem of adding AOX pollution to the environment.

The technical problem to be solved is to overcome the above shortcomings and design a special structure of macromolecules and its preparation method so that the main body of the latex formed has a certain degree of pre-crosslinked network structure rather than linear macromolecules.

Therefore, it is necessary to design an environmentally friendly method for the preparation of low-temperature waterborne acrylate copolymer latexes by adding cross-linked components containing two and more diethers to the poly monomers to participate in the copolymerization and introducing a certain degree of cross-linking in the macromolecules during the polymerization process.

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How to prepare an aqueous acrylic adhesive with high adhesion value and low residual value

A pre-emulsion containing 28 parts BA, 22 parts EHA, 1.5 parts AA, 1.0 part HEA, 0.5 parts AM, 0.6 parts Mon0 pol NP1018, 0.2 parts SE-10N, and 20 parts deionized water was prepared in a glass or stainless steel reactor.

To the polymerization reactor equipped with a reflux condenser, thermometer, and stirrer, 10% of the prepared pre-emulsion, 5 parts of deionized water, and 5 parts of polyester resin AQ1045 (Eastman Chemical Co.) were added, followed by thorough stirring of the resulting mixture at 75°C. To this mixture, the remaining 90% of the above pre-emulsion was slowly added over a period of 5 hours.

Pressure Sensitive Adhesives Manufacturer

The remaining 90% of the above pre-emulsion and an initiator solution containing 15.85 parts of deionized water, 03 parts of ammonium persulfate, and 0.05 parts of sodium phosphate was slowly added to this mixture over 5 hours for the polymerization reaction. After all the reactants were added, the temperature was raised to 80°C and the reaction mixture was reacted for another 1 hour.

After cooling, the pH of the mixture was adjusted to 5.5-6.0 using an 8% solution of zinc ammonium bicarbonate (Billion AB) prepared with ammonia, zinc oxide, and ammonium bicarbonate, and then the viscosity of the mixture was adjusted to 3500 cps using a tackifier to produce an aqueous acrylic adhesive.

The aqueous acrylic adhesive is applied to one side of a PET film as described above, and the volatiles is removed from the adhesive in a drying chamber to produce an adhesive layer. The tape was prepared by attaching a glass wool mesh to the adhesive layer and reapplying the aqueous adhesive to the glass wool mesh attached to the adhesive layer to form another adhesive layer, resulting in an adhesive strength value of 790 g/26 mm and a residual value of 3.0%.

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The necessity of research and development of improved water-based acrylic adhesive

Currently, water-based acrylic adhesives are the most widely used alternative to oil-based adhesive products. The reasons for this are as follows.

They generally adhere very well to a wide range of materials and have excellent weathering and low-temperature resistance properties. In addition, they are emulsion-based adhesives with cross-linking capability, thus offering compatibility with other polymer emulsions, good adjustability, and workability due to their wide viscosity range, and can have a high solids content. To solve these problems, the content of solids can be increased and special beads of raw materials can be used to improve the production speed and adhesion. However, these practices are economically ineffective due to the increased cost of raw materials and the excessive residues after the high-temperature production process can cause other problems in the reassembly process.

pressure sensitive adhesive

Even though conventional emulsion-based adhesives contain the same polymeric components as solvent-based adhesives, they are slightly inferior in terms of adhesive performance (e.g., adhesion, cohesion, shear, and heat resistance). One of the reasons for this is the different mechanisms of mucous film formation. In the case of drop-in adhesives, the continuous film is formed when the organic solvent evaporates from the homogeneous solution. In the case of emulsions, the film is formed when the water dries out of the discontinuous system of emulsion particles. In addition, emulsion-type adhesives contain low molecular weight substances, such as surface activators or defoamers and viscosity modifiers (usually tackifiers), which are detrimental to their adhesive properties.

Although it depends on the method and process used to form the film, these phenomena can cause emulsion adhesives to have reduced moisture and water resistance, adhesion and other adhesive properties compared to solvent-based adhesives, for which polyethylene (PE) films have been widely used as substrates for tapes.

Medium adhesion PE protective film for aluminum profile1

However, because of its low melting point, its use in the manufacturing process of Braun tubes at temperatures above 200°C is very limited, it is not possible to dry quickly, the preparation process is time-consuming, and its adhesive state may be easily changed again by melting the adhesive.

The availability of improved aqueous acrylic adhesives not only solves these problems but also allows the use of high-quality blast tapes for fixing braunschweiger tubes.

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The need to develop water-based adhesives to replace oil-soluble adhesives

Braun tubes are made of glass and maintain a vacuum inside, so they are easily damaged by external forces applied to them. Therefore, the Braun tube cannot be fixed directly into a box or shell. Instead, an explosion-proof tape made of the whole plant adheres to the outer perimeter of the Braus tube, and then the explosion-proof tape is fixed to the box or shell.

If the explosion-proof tape is secured to the Braun tube by means of cushioning tape, it is possible to prevent damage to the Braun tube in the event of an internal explosion caused by external force or accident and to minimize the area of debris scattering. The demand for Braun tubes has been increasing due to the rapidly developing information technology market which demands better display media. In particular, the size and quality of Braun tubes used in traditional TV sets are increasing, and expensive color Braun tubes with high resolution and flat panel displays have been developed for the next generation of computer monitors, super large screen color TV sets, and high definition TV (daily DTV).

transparent PE films with printing

Before the Brawstube is marketed as a final product, it goes through many assembly steps and rigorous testing procedures. In the final test after completion of assembly, defective parts that do not provide satisfactory performance due to defects or errors in the assembly process are eliminated.

In this case, the final product was so defective that it had to be disassembled so that the problem could be fixed and then reassembled for the market. During the disassembly process, the tape attached to the Braun tube for explosion protection must be removed. However, because the adhesive layer is formed during heat treatment at temperatures above 200℃ for 30 to 40 minutes in the Braun tube assembly process, the tape is usually firmly attached to the Braun tube, making its removal quite difficult. Up to now, the removal of the adhesive layer during the disassembly process has been carried out either by organic solvent lysis or by physical force. However, these methods take a long time and may cause other problems, such as environmental pollution and damage to the periphery of the Brauer tube. These problems are particularly acute for tape prepared with an oil-soluble adhesive. The explosion-proof tape used to secure Braun tubes consists of an adhesive and a tape base material.

Widely used as adhesives, oil-soluble acrylic adhesives have the advantages of low price, excellent adhesion, and a simple production process. However, the use of oil-soluble propionic acid adhesives is regulated in developed countries due to the risk of fire or toxic volatile vapors and environmental pollution in their production and reproduction processes.

Therefore, it is necessary to develop water-based adhesives to replace oil-soluble adhesives and make them have better performance and reasonable prices compared with oil-soluble adhesives.

 

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Preparation of hybrid adhesive solution with macromolecular monomers sealed by methacrylate

Hybrid polymer solutions were prepared using methacrylate-capped macromonomers, which contain essentially no strong acids or metal catalysts. The average molecular weight of the macromonomer was determined by the GP°C method using polystyrene as a standard substance, and the result was M6600, Mw=7200 Dalton.

The initial addition mixture was prepared to contain 5973 g of 2-ethylhexyl acrylate (225EHA), 22.72 g of ethylene-butene macromonomer, 17.05 g of methyl acrylate MA) 5.67 g of acrylic acid-2-hydroxyethyl ester (2-HEA) in 55.0 g of ethyl acetate (EtOAc), 64.19 g of hexane (standard mixed isomeric grade) and 028 g of even aminodiisobutylene (ABN), was added to a 3-liter, 4-necked round-bottom flask equipped with a stainless steel stirrer, thermometer, condenser, water bath, and low-speed addition funnel.

acrylate

The initial addition mixture was heated to reflux while stirring. After ten minutes of reflux, simultaneously but over 2 h 30 and 3 h, respectively, a monomer mixture containing 229.0 g of 2EHA, 128.59 g of ethylene-butene macromonomer, 65.45 g of MA, 21.84 g of 2-HEA, 27.5 g of hexane and a monomer mixture containing 236.5 g of EtOAc, 55.0 g of hexane, 138 g of AIBN. At the end of the addition, the flask contents were kept under reflux for 2 hours. Next, the residual macromonomer was removed by adding a short half-life initiator within 1 hour, and then the solution was held at reflux for 1 hour. Finally, a diluent consisting of 1833 g of toluene was slowly added to the reaction mass while the contents were cooled to room temperature. The polymer solution maintained its fluid viscosity throughout the reaction and did not tend to attach to the reactor stirrer.

The polymer solution contained 42.7% solids and had a Brook6eld viscosity of 2500 mPas. Coagulation
The average molecular weight determined by gel permeation chromatography was Mw=560,000, M=34,000.

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Rubber resin compositions are often used to bond polyolefin and other low energy substrates

A typical acrylic pressure-sensitive adhesive is an alkyl ester monomer, a functional monomer such as acrylic acid.

Copolymers can be cross-linked with, for example, aluminum chelators. These adhesives are generally deficient for low-energy surfaces.

Lack of adhesion, but these adhesives can be improved by adding rosin esters to the low-energy surface it works. But at the same time lead to the loss of heat resistance and aging resistance. Even if it hurts well with good aging resistance, the viscosifying acrylic dispersion is also sufficient for some uses, such as most paper labels, and has actually become the dominant paper label technology. But these enhanced propenes.

Acid binders do not have sufficient resistance to degradation required for most cartographic and industrial tape applications, where acrylic solutions are commonly used.

PE-protective-film-for-mirror-usage

Rubber resin compositions are often used to bond polyolefin and other low-energy substrates.

The compound is a natural rubber or styrene block copolymer with rosin esters. These compositions have advantages

It has good adhesion and bond strength but is subject to oxidation and degradation caused by ultraviolet irradiation

The use will fade and age and lose viscosity. A fully hydrogenated composition of rubber and resin, except to be added into.

In addition, basically does not have the required cohesiveness.

The United States patent once disclosed a rubber acrylic pressure-sensitive adhesive mix only good.

Good UV and aging resistance and adhesion to non-polar surfaces. In spite of the ability with these advances, improvements are still needed to prepare polymer compositions that are pressure-sensitive adhesives, such as industrial tape, transfer film, and exterior graphics, where adhesivities and chemical resistance are sufficient to work with low-energy difficult-to-bond surfaces. The invention is the solution to this need.

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Industry Share: Preparation of a parent modified acrylate copolymer adhesive 4

Preparation of a parent-modified acrylate copolymer adhesive

Preparation of amphiphilic oligomers 12g octadecyl alcohol, 7g maleic anhydride, and 65g xylene were mixed evenly and poured into a round-bottom flask; The monoester of octadecyl maleate was obtained at 120℃ for 4h. 10g octadecyl maleate, 7.5g polyethylene glycol 600, 1.6g p-toluene sulfonic acid, and 150g toluene was poured into a round-bottomed flask, mixed evenly, and reacted at 90℃ for 16h to obtain amphiphilic oligomers.

  • (1) Take 10g methacrylate, 15g ethyl acrylate, 40g toluene, 40g ethyl acetate, and 5g acetone and mix evenly; Then, 5g dimethylacryloxy (trimethyl) hexamethyldiurethane, 1g ammonium persulfate and 1g potassium persulfate were added in the stirring state, and the reaction was stirred at 60℃ for 6h.
  • (2) Adding 15g of the amphiphilic oligomer, 2g methylene diacrylamide, 1.2g sodium p-toluene thiosulfate, 0.1g methyl persulfate, stirring reaction at 60℃ for 6h;
  • (3) Add 0.3g sodium hydrogen phosphate, 0.3g tartaric acid, 1.4g phosphate PM1500, 2 calcium carbonate whiskers, and 5g silicon dioxide successively, stirring until evenly dispersed;
  • (4) In stirring state, vacuum, parental oligomer block modified acrylate copolymer adhesive.
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Emulsion modification agent of adhesive

Solution A is first prepared by mixing 44g deionized water with 0.25g polyoxyethylene nonyl ether sulfate (0NH4. Polyoxethyene Nonyl ether sulfate, China Japan Synthesis Company).

In addition, 76.7g deionized water, 2.9g polyoxyethylene nonyl pheny1 ether, 12.9g polyoxyethylene nonyl pheny1 ammonium sulfate, 157.3g were obtained 2-ethylhexyl acrylate monomer, 102.6g dioctyl maleate monomer, 85.5g ethyl collate.

The olefin monomer and 1.0g acetyl oxyethylene methacrylate ethyl monomer were prepared into a 5B solution by uniform stirring.

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In addition, 87.5g of deionized water, 1.8g of sodium bicarbonate, and 0.9g of potassium persulfate were prepared into a C solution by uniform stirring.

In addition, 20.5g of deionized water and 0.9g of potassium persulfate were prepared into a D solution by uniform stirring. Solutions A, B, C, and D can be prepared separately.

10 Pour solution A and solution D (half of the total amount) into the emulsion polymerization equipment, which includes: an agitator, temperature meter, heater, reflux condensing tube, and five-neck flask. When it was heated to 70℃, B solution (1/10 of its total) was mixed with 1/2D solution and fed within 20-30 minutes. Then the temperature was raised to 80℃, and the remaining B solution (9/10) and C solution were fed for 240 minutes respectively.

The temperature rises to 85℃ and is maintained for 90 minutes before cooling to room temperature. The solid 15 composition of the emulsion modifier was 59.5%, the pH value was 5.2, and the viscosity was 23000 cps.

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Industry Share: Preparation of a parent modified acrylate copolymer adhesive 3

Preparation of a parent-modified acrylate copolymer adhesive 3

Preparation of amphiphilic oligomers. Mix 8g octadecyl alcohol, 6g maleic anhydride, and 55g toluene evenly and pour them into a round-bottom flask; The monoester of octadecyl maleate was obtained at 60℃ for 48h. 7g octadecyl maleate monoester, 5g polyethylene glycol 800, 0.8 g p-toluene sulfonic acid, and 150g toluene were poured into a round-bottomed flask, mixed evenly, and reacted at 120℃ for 4h to obtain amphiphilic oligomers.

  • (1) Take 12g methyl methacrylate, 16g acrylic acid, 70g xylene, 20g ethyl acetate, and 5g acetone and mix evenly; Then, 12g dimethylacryloxy (trimethyl) hexamethyldiurethane, 3g ammonium persulfate and 2g potassium persulfide were added in the stirring state, stirring at 60℃ for 6h;
  • (2) Add 5g amphiphilic oligomer, 1.5g methylene acrylamide, 1g sodium p-toluene thione-sulfonate, and 1g ammonium persulfate, stirring reaction at 70℃ for 5h;
  • (3) Add 0.5g sodium metaphosphate, 0.1g citric acid, 1.6g phosphate PM2000, and 10 calcium carbonate whisker successively, stirring until evenly dispersed;
  • (4) In stirring state, vacuum, parental oligomer block modified acrylate copolymer adhesive.
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Emulsion type modification agent can be added emulsion acrylic pressure sensitive adhesive

The use of emulsion acrylic pressure-sensitive adhesive, for low surface energy substrates such as polyolefin surface adhesion, is poor. Therefore, tackifiers often need to be added to improve their sticking performance. Viscosifying resin was usually mixed with rosin resin as an emulsion acrylic pressure-sensitive adhesive. Rosin resin source is an acidic natural resin extracted from pine, pine easy to be affected by different origins, climate change and variety differences, and other conditions, resulting in the quality of the extracted rosin resin instability: and emulsion acrylic pressure sensitive adhesive and rosin resin compatibility problems, rosin resin added to excess, easy to cause a decline in adhesive properties.

pressure sensitive adhesive

Emulsion modifier is used as a viscosifying resin of emulsion acrylic pressure sensitive adhesive, and the composition of emulsion modifier includes (a) diester of a dicarboxylic acid with 6-12 carbon atoms (part per hundred) with 15-35 weight parts (phr): (6)2~16 carbon vinyl esters. l5~35phr:(c)4~8 carbon alky1 acrylates) 35~65phr: In terms of total (a)+(b)+(c) acrylates, (d) acetoacetate monomer 0.1~2.0phr: relative to.

(a)+ (b)+  (c) in terms of the total, nonionic surfactants (e) 0.1 ~ 2.0 PHR, compared with (a) + (b) + (c) in terms of the total, anionic surfactants (f) 0.4 ~ 3.0 PHR. The average particle size of the emulsion modifier is 0.1~0.4μm, the glass transfer temperature (Tg) is -30~-50℃, and the solid composition ranges from 50 to 70 % by weight.

Emulsion modification agent added emulsion acrylic pressure sensitive adhesive mixed, The adhesion force of steel peel adhesion, PE peel adhesion, loop tack, and holding power of the steel plate can be improved by adding The dosage relative to emulsion acrylic pressure sensitive adhesive is 5~30phr.

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