A halogen-free antistatic composition for pressure sensitive adhesive

Abstract

The application provides a halogen-free antistatic composition for pressure-sensitive adhesive, and belongs to the technical field of high polymer materials.The composition is prepared by compounding a fluorine-free ionic liquid, an alkoxyl-containing cyclic compound, a functional additive and a solvent, and is halogen-free and environmentally friendly.The product has excellent compatibility with pressure-sensitive adhesive such as acrylic, organic silicon and PU, can significantly reduce the surface resistance, and has stable and long-lasting antistatic property, good low-temperature performance, small influence of seasons, and resistance to moisture and heat without separation, and has no obvious influence on the peeling force and light transmittance, solves the problems of easy agglomeration, large migration and poor moisture resistance of traditional antistatic agents, and is suitable for high-end pressure-sensitive adhesive protective films in the electronic industry.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a halogen-free antistatic composition for pressure-sensitive adhesives. Background Technology

[0002] With the rapid development of the electronics industry, the demand for anti-static functions is becoming increasingly common. Electronic products utilize a large amount of pressure-sensitive adhesive protective film during manufacturing. Protective films without anti-static properties will attract small particulate contaminants from the air onto the film surface during use, causing contamination. In severe cases, electrostatic breakdown may even occur, damaging electronic products and compromising yield.

[0003] The EU has further tightened restrictions on halogen content in electrical and electronic equipment. Halogen-free status has become a key indicator for products to enter the EU market.

[0004] Patent document CN202510362919.3 describes the use of graphene, polypyrrole, and carbon nanotubes as a mixed halogen-free component to achieve antistatic properties, exhibiting excellent performance in thermoplastic TPU materials. However, in pressure-sensitive adhesive systems, the addition of low-polarity solvents causes graphene, polypyrrole, and carbon nanotubes to easily agglomerate secondary, reducing the antistatic function and affecting product quality.

[0005] Patent document CN202511924875.5 describes the preparation of a halogen-free imidazolium salt ionic liquid using the reaction of 1-ethyl-3-methylimidazolium bromide and sodium diethyl phosphate as an antistatic agent in acrylic adhesives; patent document TW114105986 describes the use of tetraalkylbis(oxalato)borate quaternary ammonium salt as a halogen-free antistatic agent in ink coatings. Both are successful examples of the application of halogen-free antistatic agents. However, the current market for pressure-sensitive adhesives has increasingly higher requirements for antistatic agents, with low migration, low resistance, and minimal seasonal influence becoming increasingly common requirements. Low molecular weight imidazolium salts migrate quickly and have poor resistance to damp heat; while tetraalkylbis(oxalato)borate quaternary ammonium salt performs well in ink systems, pressure-sensitive adhesive coatings are generally thicker, increasing the ion conduction distance and leading to poorer antistatic performance. Furthermore, single ionic conductors or their simple combinations exhibit low ion mobility at low temperatures, resulting in product performance being significantly affected by seasonality, particularly in winter. Summary of the Invention

[0006] The purpose of this invention is to provide a halogen-free antistatic composition for pressure-sensitive adhesives to solve the above-mentioned technical problems.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a halogen-free antistatic composition for pressure-sensitive adhesives, comprising the following components: a fluorine-free ionic liquid, an alkoxy-containing cyclic compound, functional additives, and a solvent; The mass ratio of the fluorine-free ionic liquid, the alkoxy-containing cyclic compound, and the functional additive is 40~50:10~20:10~20; The amount of solvent added is such that all components are mixed evenly.

[0008] Furthermore, the fluorine-free ionic liquid is an ionic compound, and the cations of the ionic compound include: alkylimidazolium cation, alkylpyridine cation, alkylpyrrolidine cation, alkylpiperidine cation or tetraalkyl quaternary ammonium cation; the anions include: sulfate anion, phosphate anion, acetate anion, borate anion, bis(2-ethylhexyl)phosphate anion and bis(oxalate-boronate) anion or more.

[0009] Furthermore, the fluorine-free ionic liquid can also be prepared by reacting a functional ionic liquid with a fluorine-free metal salt. The molar ratio of the functional ionic liquid to the fluorine-free metal salt is 1:1 to 1.2.

[0010] Furthermore, the functional ionic liquid is an ionic compound, whose cations include: alkylimidazolium cation, alkylpyridine cation, alkylpyrrolidine cation, alkylpiperidine cation, tetraalkylquaternary ammonium cation, and whose anions include: one or more of phosphate ester anions, carbonate anions, borate anions, acetate anions, chloride anions, bromide anions, and iodide anions.

[0011] The fluorine-free metal salt includes metal salts of potassium, sodium, lithium, silver or copper that can provide coordinating cations; the anions of the fluorine-free metal salt include one or more of carbonate, hydroxide, sulfate, phosphate, borate, acetate and bis(2-ethylhexyl)phosphate or bis(oxalate-borate).

[0012] Furthermore, the fluorine-free ionic liquid is an ionic liquid in which the cations and anions of alkyl groups have 3 to 4 carbon atoms and do not contain N, S, or P elements.

[0013] Furthermore, the functional additives include one or more of citrate esters, adipate esters, and terephthalate esters.

[0014] Furthermore, the solvent includes one or more of ethyl acetate, butanone, acetone, toluene, butyl acetate, and solvent oil.

[0015] The beneficial effects of this invention are: The halogen-free antistatic composition for pressure-sensitive adhesives provided by this invention combines excellent antistatic properties, environmental friendliness, and system compatibility. The composition uses a fluorine-free ionic liquid as the core antistatic component, combined with alkoxy-containing cyclic compounds and functional additives, to rapidly reduce the surface resistance of pressure-sensitive adhesives, achieving a stable and long-lasting antistatic effect. This effectively avoids electrostatic adsorption pollution and electrostatic breakdown problems, improving the yield rate of electronic product processing. The product is completely halogen-free, meeting the EU's environmental access requirements for electrical and electronic equipment, and has a wider range of applications. This composition exhibits good compatibility with various pressure-sensitive adhesive systems such as acrylic, silicone, and PU, without agglomeration or precipitation. Its ion mobility is stable at low temperatures, minimally affected by seasonal changes, and exhibits excellent resistance to damp heat, resulting in a complete and smooth adhesive layer after boiling. Simultaneously, it has minimal impact on the peel force of the substrate and does not damage light transmittance, making it widely applicable to high-end pressure-sensitive adhesive protective films in the electronics industry. Its overall performance is significantly superior to traditional antistatic agents. Attached Figure Description

[0016] Figure 1 The images show the third-party inspection and testing reports of the products obtained in Example 3 and Comparative Example 1, respectively. Detailed Implementation

[0017] This invention provides a halogen-free antistatic composition for pressure-sensitive adhesives, comprising the following components: a fluorine-free ionic liquid, an alkoxy-containing cyclic compound, functional additives, and a solvent; The mass ratio of the fluorine-free ionic liquid, the alkoxy-containing cyclic compound, and the functional additive is 40~50:10~20:10~20; The amount of solvent added is such that all components are mixed evenly.

[0018] In this invention, the preferred mass ratio of the fluorine-free ionic liquid, the alkoxy-containing cyclic compound, and the functional additive is 42~48:12~18:12~18.

[0019] In this invention, the fluorine-free ionic liquid is an ionic compound. The cations of the ionic compound include alkyl imidazole cations, alkyl pyridine cations, alkyl pyrrolidine cations, alkyl piperidine cations, tetraalkyl quaternary ammonium cations, etc.; the anions include: sulfate ester anions, phosphate ester anions, acetate anions, borate anions, bis(2-ethylhexyl) phosphate anions or bis(oxalate-borate) anions, preferably fluorine-free ionic liquids in which the cations and anions do not contain N, S, or P elements and have 3 to 4 alkyl C atoms.

[0020] In this invention, the fluorine-free ionic liquid can also be prepared by reacting a functional ionic liquid with a fluorine-free metal salt. The molar ratio of the functional ionic liquid to the fluorine-free metal salt is 1:1 to 1.2, preferably 1:1.1 to 1.2.

[0021] In this invention, the functional ionic liquid is an ionic compound, whose cations include: alkylimidazolium cation, alkylpyridine cation, alkylpyrrolidine cation, alkylpiperidine cation, tetraalkylquaternary ammonium cation, and whose anions include: phosphate ester anion, carbonate anion, borate anion, acetate ion, chloride anion, bromide anion, and iodide anion, one or more of these.

[0022] The fluorine-free metal salt includes metal salts of potassium, sodium, lithium, silver or copper that can provide coordinating cations; the anions of the fluorine-free metal salt include one or more of carbonate, hydroxide, sulfate, phosphate, borate, acetate, bis(2-ethylhexyl)phosphate and bis(oxalate-borate).

[0023] In this invention, the fluorine-free ionic liquid is further preferably an ionic liquid comprising 3 to 4 alkyl C atoms as cations and anions that do not contain N, S, or P elements.

[0024] In this invention, an ionic liquid with 3-4 alkyl C atoms as cations and anions that do not contain N, S, or P elements has the characteristics of good hydrophobicity, good compatibility with pressure-sensitive adhesive systems, good resistance to damp heat, low migration and precipitation rate, and minimal impact.

[0025] In this invention, the alkoxy-containing cyclic compound has a hydrophilic and hydrophobic dual structure, which can enhance ion conductivity as a skeleton. Cyclodextrin, columnar aromatic hydrocarbons, crown ethers, cucurbituril, polyrotaxane, etc. can all improve ion conductivity.

[0026] In this invention, the alkoxy-containing cyclic compound is preferably one or more of solvent-based columnar aromatics, polyrotaxanes or sulfonates, and more preferably columnar[5] aromatics and / or 1,4-butanesulfonates.

[0027] In this invention, the functional additives include one or more of citrate esters, adipate esters, and terephthalate esters, preferably citrate esters and adipate esters. These additives can synergistically work with alkoxy-containing cyclic compounds to further enhance ionic conductivity, ensure low-temperature performance, and thus improve the antistatic effect of the composition.

[0028] In this invention, the solvent includes one or more of ethyl acetate, butanone, acetone, toluene, butyl acetate, and solvent oil, preferably one or more of ethyl acetate, butanone, acetone, and toluene.

[0029] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1

[0031] 1-Butyl-3-methylpyrrolidine bis(oxalate)borate was prepared by reacting N-butyl-N-methylpyrrolidine bromide with lithium bis(oxalate)borate at a molar ratio of 1:1.2. The product was washed with deionized water to remove bromine and unreacted impurities, and then thoroughly dried to remove moisture. The pure product yield was approximately 93%.

[0032] Take 50 parts of N-butyl-N-methylpyrrolidone bis(oxalato)borate, 15 parts of 1,4-butyric acid lactone, and 10 parts of adipate, and stir with ethyl acetate as solvent until the product is completely mixed to obtain halogen-free antistatic composition A.

[0033] Take 1.5g of antistatic composition A and 100g of acrylic adhesive, and apply them to the antistatic base film at a dry adhesive thickness of 10μm to obtain an acrylic pressure-sensitive adhesive protective film.

[0034] Surface resistance is tested using an electrostatic tester.

[0035] Example 2

[0036] Halogen-free antistatic composition B was prepared by using 50 parts of commercially available N-butyl-N-methylpyrrolidone bis(oxalato)borate, 15 parts of 1,4-butyric acid lactone, and 10 parts of adipate, with ethyl acetate as the solvent and stirring until the product was completely and evenly mixed.

[0037] Take 1.5g of antistatic composition B and 100g of acrylic adhesive, and apply them to the antistatic base film at a dry adhesive thickness of 10μm to obtain an acrylic pressure-sensitive adhesive protective film.

[0038] Surface resistance was tested using an electrostatic tester.

[0039] Example 3

[0040] Take 1.5g of antistatic composition A and 100g of finished silicone adhesive, and apply them to the antistatic original film with a dry adhesive thickness of 10μm to obtain a silicone pressure-sensitive adhesive protective film.

[0041] After testing the surface resistance with an electrostatic tester and recording the data, cut a piece of pressure-sensitive adhesive protective film and place it in a constant temperature chamber at 1℃ for 24 hours. Then, take it out and test the surface resistance again with an electrostatic tester.

[0042] The silicone pressure-sensitive adhesive protective film was recut and boiled in boiling water for 2 hours. The moisture was then wiped away with a lint-free cloth, and the adhesive surface's resistance to damp heat was tested. Peel strength and light transmittance were tested by a third-party testing company.

[0043] Example 4

[0044] Take 1.5g of antistatic composition A and 100g of finished PU adhesive, and apply them to the antistatic base film at a dry adhesive thickness of 10μm to obtain a PU pressure-sensitive adhesive protective film.

[0045] Comparative Example 1

[0046] The silicone pressure-sensitive adhesive from Example 3, without the addition of an antistatic agent, was directly coated onto the antistatic base film at a dry adhesive thickness of 10 μm to obtain a silicone pressure-sensitive adhesive protective film.

[0047] Surface resistance was tested using an electrostatic tester.

[0048] Cut a piece of silicone pressure-sensitive adhesive protective film and boil it in boiling water for 2 hours. Wipe off the moisture with a lint-free cloth and test the adhesive surface's resistance to damp heat. The peel strength was tested by a third-party testing company.

[0049] Comparative Example 2

[0050] Take 100g of the silicone pressure-sensitive adhesive from Example 3, add 1.5g of commercially available 1-ethyl-3-methylimidazolium phosphate salt, and apply it directly onto the antistatic original film with a dry adhesive thickness of 10μm to obtain a silicone pressure-sensitive adhesive protective film.

[0051] After testing the surface resistance with an electrostatic tester and recording the data, cut a piece of pressure-sensitive adhesive protective film and place it in a constant temperature chamber at 1℃ for 24 hours. Then, take it out and test the surface resistance again with an electrostatic tester.

[0052] Cut a new piece of silicone pressure-sensitive adhesive protective film, boil it in boiling water for 2 hours, wipe off the moisture with a lint-free cloth, and test the adhesive surface's resistance to damp heat.

[0053] Performance and Data

[0054] The surface resistance of the adhesive surface was tested using a Smick ST-4 digital resistance meter. Table 1 shows the surface resistance values ​​and damp heat resistance of the samples obtained in Examples 1-4 and Comparative Examples 1-2.

[0055] Table 1. Characterization of surface resistivity and damp heat resistance of samples obtained in Examples 1-4 and Comparative Examples 1-2.

[0056] / : Untested

[0057] ×: Adhesive layer peeling off, adhesive surface rough.

[0058] ○: The adhesive layer is intact, but the adhesive surface is rough and has a grainy texture.

[0059] ◎: The adhesive layer is intact, and the adhesive surface is smooth and without any abnormalities.

[0060] As can be seen from the above embodiments, the present invention provides a halogen-free antistatic composition for pressure-sensitive adhesives. The results in the table show that the antistatic composition of the present invention achieves excellent antistatic properties in acrylic pressure-sensitive adhesives, PU pressure-sensitive adhesives, and silicone pressure-sensitive adhesives. Comparative tests using a relatively demanding silicone pressure-sensitive adhesive system demonstrate that the antistatic composition of the present invention exhibits low migration, no impact on the system's resistance to damp heat, minimal impact on the peel strength of the pressure-sensitive adhesive, light transmittance exceeding 90%, and good low-temperature performance.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A halogen-free antistatic composition for pressure-sensitive adhesives, characterized in that, It includes the following components: fluorine-free ionic liquid, alkoxy-containing cyclic compound, functional additives, and solvent; The mass ratio of the fluorine-free ionic liquid, the alkoxy-containing cyclic compound, and the functional additive is 40~50:10~20:10~20; The amount of solvent added is such that all components are mixed evenly.

2. The halogen-free antistatic composition for pressure-sensitive adhesives according to claim 1, characterized in that, The fluorine-free ionic liquid is an ionic compound. The cations of the ionic compound include: alkylimidazolium cation, alkylpyridine cation, alkylpyrrolidine cation, alkylpiperidine cation, or tetraalkyl quaternary ammonium cation; the anions include: sulfate anion, phosphate anion, acetate anion, borate anion, bis(2-ethylhexyl)phosphate anion, and bis(oxalate-boronate) anion, or more of these.

3. The halogen-free antistatic composition for pressure-sensitive adhesives according to claim 1, characterized in that, The fluorine-free ionic liquid can also be prepared by reacting a functional ionic liquid with a fluorine-free metal salt; The molar ratio of the functional ionic liquid to the fluorine-free metal salt is 1:1 to 1.

2.

4. The halogen-free antistatic composition for pressure-sensitive adhesives according to claim 3, characterized in that, The functional ionic liquid is an ionic compound, whose cations include: alkylimidazolium cation, alkylpyridine cation, alkylpyrrolidine cation, alkylpiperidine cation, tetraalkylquaternary ammonium cation, and anions include: one or more of phosphate ester anions, carbonate anions, borate anions, acetate anions, chloride anions, bromide anions, and iodide anions. The fluorine-free metal salt includes metal salts of potassium, sodium, lithium, silver or copper that can provide coordinating cations; the anions of the fluorine-free metal salt include one or more of carbonate, hydroxide, sulfate, phosphate, borate, acetate, bis(2-ethylhexyl)phosphate and bis(oxalate-borate).

5. A halogen-free antistatic composition for pressure-sensitive adhesives according to claim 2 or 3, characterized in that, The fluorine-free ionic liquid is an ionic liquid with 3-4 alkyl C atoms, containing cations and anions that do not contain N, S, or P elements.

6. A halogen-free antistatic composition for pressure-sensitive adhesives according to claim 1 or 2, characterized in that, The functional additives include one or more of citrate esters, adipate esters, and terephthalate esters.

7. The halogen-free antistatic composition for pressure-sensitive adhesives according to claim 1, characterized in that, The solvent includes one or more of ethyl acetate, butanone, acetone, toluene, butyl acetate, and solvent oil.

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