Low-temperature-resistant pressure-sensitive adhesive applied to road traffic signs and preparation method of low-temperature-resistant pressure-sensitive adhesive

Abstract

The invention discloses a low-temperature-resistant pressure-sensitive adhesive applied to road traffic signs and a preparation method of the low-temperature-resistant pressure-sensitive adhesive. The problem of insufficient bonding force in a low-temperature construction environment and a low-temperature working environment in the prior art is solved. The low-temperature-resistant pressure-sensitive adhesive applied to the road traffic sign consists of a soft monomer, a hard monomer, a functional monomer A, a functional monomer B, a solvent, an initiator and a curing agent. By reasonably selecting the monomers, reducing the glass transition temperature of the system and introducing the functional monomer A with low-temperature adaptability and the functional monomer B with strong polarity, the high-temperature cohesion strength is ensured, the adhesion of the pressure-sensitive adhesive in a low-temperature environment is improved, and the pressure-sensitive adhesive is suitable for various environments from room temperature to low temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive adhesives, and in particular to a low-temperature resistant pressure-sensitive adhesive used for road traffic signs and a preparation method thereof. Background Art

[0002] Pressure-sensitive adhesives (PSA) are viscoelastic materials that possess both the viscous properties of a liquid and the elastic properties of a solid. These adhesives are highly sensitive to pressure, allowing them to adhere to adhered surfaces under minimal pressure. The bonding principle is that external pressure causes the adhesive to flow viscously, achieving close contact with the surface and generating intermolecular forces, thereby achieving adhesion.

[0003] At low temperatures, road traffic signs are prone to separation between the adhesive layer and the substrate, resulting in apparent quality defects in the reflective sheeting, seriously affecting driving safety and shortening the reflective sheeting's service life. Furthermore, low-temperature construction environments can prevent the adhesive layer from fully wetting the substrate surface. Therefore, there is an urgent need to develop a low-temperature-resistant pressure-sensitive adhesive for road traffic signs and its preparation method.

[0004] Existing pressure-sensitive adhesives have low initial peel strength at low temperatures, making them difficult to bond to surfaces. Furthermore, added tackifying resins and functional additives often precipitate at low temperatures, leading to potential compatibility issues. This invention, by rationally adjusting the monomer ratio and introducing functional monomers, lowers the system's glass transition temperature and increases low-temperature wettability while ensuring strong bonding to the interface, thus resolving this difficult-to-bond problem. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention aims to provide a low-temperature-resistant pressure-sensitive adhesive for road traffic signs and a method for preparing the same. The following provides a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The invention relates to a low-temperature resistant acrylic pressure-sensitive adhesive, which comprises the following raw materials in percentage by weight: 20-40% of a soft monomer, 3-10% of a hard monomer, 5-11% of a functional monomer A, 0.1-5% of a functional monomer B, 0.05-0.5% of an initiator, 40-60% of a solvent, and 0.05-0.5% of a curing agent.

[0008] As an embodiment of the present invention, the mass ratio of the total amount of monomers and initiators to the solvent is 100:100-170, preferably 100:100-150. The mass ratio of the soft monomer to the total amount of monomers and initiators is 66%-72%.

[0009] As an embodiment of the present invention, the soft monomer is a long-chain alkane acrylate, and the alkane chain thereof has 4 to 16 carbon atoms.

[0010] In one embodiment of the present invention, the soft monomer is one or more of isooctyl acrylate, butyl acrylate, octadecyl methacrylate, and lauryl methacrylate. The soft monomer accounts for 20-40% by weight of the pressure-sensitive adhesive; alternatively, the soft monomer may comprise 20%, 22%, 24%, 26%, 28%, 29%, 30%, 31%, 32%, 33%, 35%, 36%, 38%, or 40%.

[0011] In one embodiment of the present invention, the hard monomer is one or more of methyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl acrylate, vinyl acetate, and styrene. The hard monomer accounts for 3-10% by weight of the pressure-sensitive adhesive, and may be 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, or 10%.

[0012] As one embodiment of the present invention, the functional monomer A is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and carbitol acrylate. The mass proportion of functional monomer A in the pressure-sensitive adhesive is 5-11%; it can be 5%, 5.5%, 6.5%, 7%, 8%, 9%, 10%, 10.5%, or 11%. Under the system of the present invention, functional monomer A can promote the bonding effect of the pressure-sensitive adhesive in a low-temperature environment, improve the bonding strength, and act as a cross-linking point. When its usage equivalent is less than 5%, the interaction force between the pressure-sensitive adhesive and the adhesive is low, and the bonding effect deteriorates. When its usage equivalent is higher than 10%, the intramolecular hydrogen bonds increase, cross-linking is aggravated, the wetting effect of the pressure-sensitive adhesive deteriorates, and the bonding effect also deteriorates.

[0013] In one embodiment of the present invention, the functional monomer B is one or more of acrylonitrile, acrylamide, methacrylonitrile, and methacrylamide. The weight percentage of functional monomer B in the pressure-sensitive adhesive is 0.1-5%, and may be 0.1%, 0.5%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 2%, 3%, 4%, or 5%. It is preferably 1-5%, and more preferably 1-2%. As a highly polar monomer, functional monomer B enhances the system's cohesion while ensuring low-temperature adhesion. The absence of functional monomer B results in reduced peel strength.

[0014] In one embodiment of the present invention, the solvent is one or more of acetone, ethyl acetate, n-heptane, dimethyl carbonate, butyl acetate, toluene, xylene, and methyl ethyl ketone. The mass proportion of the solvent in the pressure-sensitive adhesive is 40-60%, and may be 40%, 45%, 50%, 52%, 53%, 53.5%, 54%, 55%, 56%, 56.5%, 58%, or 60%.

[0015] In one embodiment of the present invention, the curing agent is one or more of an isocyanate curing agent, an epoxy curing agent, an aziridine curing agent, and a metal salt curing agent. The cured mass percentage of the pressure-sensitive adhesive is 0.05-0.5%, and may be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0016] In one embodiment of the present invention, the initiator is selected from azobisisobutyronitrile, benzoyl peroxide, dilauroyl peroxide, and azobisisovaleronitrile. The weight percentage of the initiator in the pressure-sensitive adhesive is 0.05-0.5%, and may be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, or 0.5%.

[0017] The present invention also relates to a method for preparing a low-temperature resistant pressure-sensitive adhesive for road traffic signs, comprising the following steps:

[0018] S1, mixing part of the soft monomer, the hard monomer, the functional monomer A, the functional monomer B, and a part of the initiator to obtain a mixed monomer;

[0019] S2, adding a portion of the solvent to the reaction vessel, heating to a temperature of 70-85 ° C, allowing the solvent to reflux stably, and then adding the mixed monomers dropwise to the reaction vessel at the solvent reflux temperature for 1-2 hours. After the addition of the mixed monomers is completed, the reaction is kept at the solvent reflux temperature for 1-4 hours;

[0020] S3, mixing the remaining initiator and the remaining monomer, dissolving them with a portion of the solvent, and adding them to the reaction vessel, and then keeping the mixture at the reflux temperature of the solvent for 2-4 hours;

[0021] S4. After the reaction is completed, the temperature is lowered to below 50° C., the remaining solvent and curing agent are added and stirred evenly to obtain a low-temperature resistant acrylic pressure-sensitive adhesive for road traffic markings.

[0022] As one embodiment of the present invention, the amount of the initiator in S1 accounts for 30-50% of the total mass of the initiator, and can be 30%, 32%, 34%, 36%, 38%, 38.5%, 40%, 42%, 44%, 46%, 48%, or 50%.

[0023] As an embodiment of the present invention, the proportion of the solvent usage in S1 to the total mass of the solvent is 40-70%; it can be 40%, 50%, 60%, 61%, 65%, 65.5%, 66%, 68%, 69%, or 70%.

[0024] In one embodiment of the present invention, the solvent content in S2 is 28%-35% of the total solvent mass; alternatively, the content may be 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 32%, 33%, 34%, or 35%. In some embodiments, the solvent comprises ethyl acetate, with the ethyl acetate content accounting for 55%-97% by mass. The solvents in both S2 and S3 are ethyl acetate; in S1, the ethyl acetate content is 29%-62.5% of the total ethyl acetate content; and in S2, the ethyl acetate content is 31%-59% of the total ethyl acetate content.

[0025] As an embodiment of the present invention, the ratio of the monomer amount in S1 to the total mass of the monomers is 50-60%; it can be 50%, 52%, 54%, 56%, 58%, or 60%.

[0026] As an embodiment of the present invention, it also includes S5, taking the S4 sample and coating it on a release film, placing the coated release film in an oven for baking, and after baking, curing it for a period of time to obtain a finished acrylic pressure-sensitive adhesive.

[0027] As an embodiment of the present invention, in S5, the baking temperature is Bake for 3-5 minutes.

[0028] As an embodiment of the present invention, in S5, the aging temperature is The ripening time is 1-3 days.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The acrylic pressure-sensitive adhesive of the present invention has good low-temperature adhesion, a low glass transition temperature, and a high cohesive strength, so that it can quickly wet the surface of the adherend at a low temperature of 0°C and Maintain good bonding performance. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several adjustments and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0032] Example 1

[0033] Step 1, put 72g of isooctyl acrylate, 36g of butyl acrylate, 12g of methyl acrylate, 12g of vinyl acetate, 12g of acrylic acid, 12g of hydroxyethyl acrylate, 4.8g of acrylonitrile, and 0.5g of azobisisobutylcyanide into a 250mL beaker and stir and mix uniformly to obtain a mixed monomer;

[0034] Step 2: 100 g of ethyl acetate, 50 g of acetone, 20 g of dimethyl carbonate, and 50 g of methyl ethyl ketone were added to a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser. The mixture was heated in a constant temperature water bath until the solvent was stably refluxed (temperature 73°C). The mixed monomers were evenly added dropwise to the reaction flask using a constant pressure dropping funnel at the solvent reflux temperature. The addition took 2 hours. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour.

[0035] Step 3: Add subsequent monomers: dissolve 48 g of isooctyl acrylate, 24 g of butyl acrylate, 8 g of methyl acrylate, 8 g of vinyl acetate, 8 g of acrylic acid, 8 g of hydroxyethyl acrylate, 3.2 g of acrylonitrile, and 0.8 g of azobisisobutylcyanide in 100 g of ethyl acetate, mix well, add to a four-necked flask, and keep the mixture at the reflux temperature of the solvent for 4 hours;

[0036] Step 4: After the reaction is completed, the temperature is lowered to below 50° C., 20 g of ethyl acetate and 0.5 g of aluminum acetylacetonate, a metal salt curing agent, are added and stirred thoroughly.

[0037] Example 2

[0038] Step 1, 72 g of isooctyl acrylate, 36 g of lauryl methacrylate, 12 g of methyl acrylate, 12 g of acrylic acid, 12 g of hydroxyethyl acrylate, 12 g of hydroxypropyl acrylate, 4.8 g of acrylamide, and 0.5 g of benzoyl peroxide were added into a 250 mL beaker and stirred to obtain a mixed monomer;

[0039] Step 2, 50 g of ethyl acetate, 20 g of dimethyl carbonate, 20 g of butyl acetate, and 100 g of toluene were added to a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, and heated in a constant temperature water bath until the solvent was stably refluxed (temperature 85 ° C). The mixed monomers were evenly added dropwise to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition took 2 hours. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour;

[0040] Step 3: Add subsequent monomers: dissolve 48 g of isooctyl acrylate, 24 g of lauryl methacrylate, 8 g of methyl acrylate, 8 g of acrylic acid, 8 g of hydroxyethyl acrylate, 8 g of hydroxypropyl acrylate, 3.2 g of acrylamide, and 0.8 g of benzoyl peroxide in 100 g of ethyl acetate, mix well, add to a four-necked flask, and keep the mixture at the reflux temperature of the solvent for 4 hours;

[0041] Step 4: After the reaction is completed, the temperature is lowered to below 50°C, and 20 g of ethyl acetate and 0.5 g of isocyanate curing agent are added and stirred thoroughly.

[0042] Example 3

[0043] Step 1, 36 g of butyl acrylate, 72 g of lauryl methacrylate, 12 g of methyl acrylate, 4.8 g of styrene, 7.2 g of acrylic acid, 12 g of hydroxypropyl acrylate, 4.8 g of acrylonitrile, and 0.5 g of dilauroyl peroxide were added into a 250 mL beaker and stirred to mix uniformly to obtain a mixed monomer;

[0044] Step 2: Add 200 g of ethyl acetate and 10 g of acetone to a 1 L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, and heat in a constant temperature water bath until the solvent is stably refluxed (temperature 75°C). Add the mixed monomers evenly dropwise to the reaction flask using a constant pressure dropping funnel at the solvent reflux temperature. The addition takes 2 hours. After the addition is complete, keep the reaction at the solvent reflux temperature for 1 hour.

[0045] Step 3: Add subsequent monomers: 24 g of butyl acrylate, 48 g of lauryl methacrylate, 8 g of methyl acrylate, 3.2 g of styrene, 4.8 g of acrylic acid, 8 g of hydroxypropyl acrylate, 3.2 g of acrylonitrile, and 0.8 g of dilauroyl peroxide were dissolved in 100 g of ethyl acetate, mixed well, and added to a four-necked flask. The mixture was kept warm at the reflux temperature of the solvent for 4 hours.

[0046] Step 4: After the reaction is completed, the temperature is lowered to below 50°C, and 20 g of ethyl acetate and 0.5 g of aziridine are added and stirred thoroughly.

[0047] Example 4

[0048] Step 1, 72g of isooctyl acrylate, 36g of butyl acrylate, 12g of methyl acrylate, 12g of vinyl acetate, 12g of acrylic acid, 12g of hydroxyethyl acrylate, 4.8g of acrylonitrile, and 0.5g of azobisisovaleronitrile were added into a 250mL beaker and stirred to mix uniformly to obtain a mixed monomer;

[0049] Step 2: 100 g of ethyl acetate, 100 g of acetone, and 30 g of methyl ethyl ketone were added to a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser. The mixture was heated in a constant temperature water bath until the solvent was stably refluxed (temperature 70°C). The mixed monomers were evenly added dropwise to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition took 2 hours. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour.

[0050] Step 3: Add subsequent monomers: dissolve 48 g of isooctyl acrylate, 24 g of butyl acrylate, 8 g of methyl acrylate, 8 g of vinyl acetate, 8 g of acrylic acid, 8 g of hydroxyethyl acrylate, 3.2 g of acrylonitrile, and 0.8 g of azobisisopentyl cyanide in 100 g of ethyl acetate, mix well, add to a four-necked flask, and keep the mixture at the reflux temperature for 4 hours;

[0051] Step 4: After the reaction is completed, the temperature is lowered to below 50°C, 20 g of ethyl acetate and 0.5 g of epoxy curing agent are added, and the mixture is thoroughly stirred.

[0052] Comparative Example 1

[0053] Step 1, add 72g of isooctyl acrylate, 36g of lauryl methacrylate, 12g of methyl acrylate, 12g of acrylic acid, 12g of hydroxyethyl acrylate, 12g of hydroxypropyl acrylate, and 0.5g of benzoyl peroxide into a 250mL beaker and stir to mix uniformly to obtain a mixed monomer;

[0054] Step 2, 50 g of ethyl acetate, 20 g of dimethyl carbonate, 20 g of butyl acetate, and 100 g of toluene were added to a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, and heated in a constant temperature water bath until the solvent was stably refluxed (temperature 85 ° C). The mixed monomers were evenly added dropwise to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition took 2 hours. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour;

[0055] Step 3: Add subsequent monomers: dissolve 48 g of isooctyl acrylate, 24 g of lauryl methacrylate, 8 g of methyl acrylate, 8 g of acrylic acid, 8 g of hydroxyethyl acrylate, 8 g of hydroxypropyl acrylate, and 0.8 g of benzoyl peroxide in 100 g of ethyl acetate, mix well, add to a four-necked flask, and keep the mixture at the reflux temperature of the solvent for 4 hours;

[0056] Step 4: After the reaction is completed, the temperature is lowered to below 50°C, and 20 g of ethyl acetate and 0.5 g of isocyanate curing agent are added and stirred thoroughly.

[0057] Comparative Example 2

[0058] Prepare polyacrylate according to Example 1 of CN109762097B, take out 40g, add 0.1g epoxy curing agent and 26g ethyl acetate, stir thoroughly,

[0059] The low-temperature-resistant acrylic pressure-sensitive adhesives for road traffic signs prepared in Examples 1-4 and Comparative Example 1 were evenly coated onto a 50 μm PET release film using a doctor blade. The adhesives were baked at 120°C for 3 minutes and then transferred to a road traffic sign substrate to obtain road traffic sign samples. The samples were then aged at 50°C for 3 days before performance testing. Table 1 shows the performance parameters of the low-temperature-resistant acrylic pressure-sensitive adhesives for road traffic signs prepared in Examples 1-4 and Comparative Example 1.

[0060] The viscosity test is conducted at 25°C with a sample solid content of 40% by a rotational viscometer; the 180° peel strength test is conducted according to the national standard. The initial adhesion is measured according to the national standard GB-T4852-2002 (rolling ball method), and the sample is tested after being placed at the test temperature for 60 minutes.

[0061] Table 1. Performance parameters of low-temperature resistant acrylic pressure-sensitive adhesive for road traffic markings

[0062]

[0063]

[0064] The test results in Table 1 show that the low-temperature-resistant acrylic pressure-sensitive adhesive for road traffic marking prepared by the present invention has a high initial tack at 0°C, meeting the construction requirements for quick application at low temperatures. It also exhibits good adhesion at -20°C, ensuring good low-temperature bonding. In Control Example 1, functional monomer B was removed. Although the initial tack at low temperatures was good, the low-temperature peel strength decreased significantly, demonstrating that functional monomer B contributes to low-temperature peel strength. The pressure-sensitive adhesive in Control Example 2, while exhibiting good room-temperature bonding, exhibits low initial tack at 0°C, poor wettability at -20°C, and low peel strength, failing to meet low-temperature bonding requirements. This may be due to the high degree of crosslinking and the abundance of intramolecular hydrogen bonds.

[0065] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0066] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking, characterized in that: The invention comprises the following raw materials in weight percentage: soft monomer: 20-40%, hard monomer: 3-10%, functional monomer A: 5-11%, functional monomer B: 0.1-5%, initiator: 0.05-0.5%, solvent: 40-60%, and curing agent: 0.05-0.5%.

2. The low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 1, characterized in that: The soft monomer is one or more of isooctyl acrylate, butyl acrylate, lauryl methacrylate, and octadecyl methacrylate.

3. The low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 1, characterized in that: The hard monomer is one or more of methyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl acrylate, styrene, and vinyl acetate.

4. The low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 1, characterized in that: The functional monomer A is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and carbitol acrylate.

5. The low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 1, characterized in that: The functional monomer B is one or more of acrylonitrile, acrylamide, methacrylonitrile and methacrylamide.

6. The low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 1, characterized in that: The curing agent is one or more of an isocyanate curing agent, an epoxy curing agent, an aziridine, and a metal salt curing agent.

7. A method for preparing the low-temperature resistant acrylic pressure-sensitive adhesive for road traffic markings as claimed in claim 1, characterized in that: The method comprises the following steps: S1, mixing part of the soft monomer, the hard monomer, the functional monomer A, the functional monomer B, and a part of the initiator to obtain a mixed monomer; S2, adding a portion of the solvent to the reaction vessel, heating to a temperature of 70-85 ° C, allowing the solvent to reflux stably, and then adding the mixed monomers dropwise to the reaction vessel at the solvent reflux temperature for 1-2 hours. After the addition of the mixed monomers is completed, the reaction is kept at the solvent reflux temperature for 1-4 hours; S3, mixing the remaining initiator and the remaining monomer, dissolving them with a portion of the solvent, and adding them to the reaction vessel, and then keeping the mixture at the reflux temperature of the solvent for 2-4 hours; S4. After the reaction is completed, the temperature is lowered to below 50° C., the remaining solvent and curing agent are added and stirred evenly to obtain a low-temperature resistant acrylic pressure-sensitive adhesive for road traffic markings.

8. The method for preparing the low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 7, characterized in that: The amount of the initiator in S1 accounts for 30-50% of the total mass of the initiator.

9. The method for preparing the low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 7, characterized in that: The proportion of the solvent usage in S1 to the total mass of the solvent is 40-70%; the proportion of the solvent usage in S2 to the total mass of the solvent is 28%-35%.

10. The method for preparing the low-temperature resistant acrylic pressure-sensitive adhesive for road traffic marking according to claim 7, characterized in that: The monomer amount in S1 accounts for 50-60% of the total monomer mass.

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