A novel hot-melt pressure-sensitive adhesive for black plaster matrix and its preparation method

Abstract

This invention discloses a novel hot-melt pressure-sensitive adhesive for black plaster matrix and its preparation method. The hot-melt pressure-sensitive adhesive comprises 15-40 parts of synthetic rubber, 10-30 parts of naphthenic oil, 0.1-5 parts of antioxidant, 30-50 parts of hydrogenated petroleum resin, 5-20 parts of rosin resin, 0.1-10 parts of pigments and fillers, and 5-20 parts of grafted epoxidized natural rubber ENR-HMEA. The invention introduces epoxy groups into epoxidized natural rubber ENR-25 with a grafting rate of 25%, and utilizes the excellent adhesion of epoxy groups to increase the adhesion effect of the formulated adhesive to different skin types. While improving adhesion, it also enhances the skin-feedback properties of the hot melt pressure-sensitive adhesive, ensuring the seal around the adhesive and preventing the invasion of external bacteria. Simultaneously, it utilizes the remaining double-bonded active groups in ENR-25 to graft hydroxyethyl methacrylate (HMEA) into the adhesive, thereby introducing an appropriate amount of hydrophilic hydroxyl end groups to increase the adhesive's sweat resistance. Furthermore, the introduced HMEA contains acrylates, which offer excellent skin-feedback and anti-allergic properties.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, and in particular to a novel hot melt pressure-sensitive adhesive for black plaster matrix and its preparation method. Background Technology

[0002] Traditional black plasters first appeared during the Wei, Jin, and Northern and Southern Dynasties. Production techniques were gradually perfected during the Tang and Song Dynasties, and they have played an indispensable role ever since. However, due to the complex manufacturing process and lack of standardized procedures, quality control is difficult, resulting in inconsistent quality and hindering large-scale standardized production.

[0003] In recent years, synthetic rubber SBS and SIS pressure-sensitive adhesive systems have been introduced to replace traditional black plasters and have entered the market. They can solve the problems of mass production and quality control of traditional black plasters. However, because the human body sweats easily, and sweat contains oil and water, the adhesive effect of these plasters is poor and they are easy to fall off when sweating. At the same time, they are easy to fall off if they are not firmly attached to joints, such as elbows, knees and ankles.

[0004] Therefore, it is necessary to seek a new, stable, and mass-producible base for black plasters that can solve these drawbacks of traditional black plasters. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, one of the objectives of this invention is to provide a novel hot melt pressure-sensitive adhesive for black plaster matrix. This invention introduces synthetic rubber SIS, petroleum resin, and rosin resin, taking into account the advantages of good adhesion of traditional hot melt pressure-sensitive adhesives. This invention preferably uses SIS 1126 and SIS 1220 in a mass ratio of 3:1. The content of diblocks, i.e., flexible segments, in SIS will affect the ring initial tack of the hot melt adhesive. Therefore, different diblock contents will change the performance of the prepared hot melt adhesive. This invention preferably uses SIS 1126 and SIS 1220 in a mass ratio of 3:1, which results in the best cohesive strength and wettability of the hot melt adhesive.

[0006] Furthermore, this invention introduces epoxy groups into 25% grafted epoxidized natural rubber ENR-25. Utilizing the excellent adhesion of these epoxy groups, the adhesive formulation is enhanced to improve its fit to different skin types. While increasing tack, it also improves the adhesion between the hot-melt pressure-sensitive adhesive and the skin, ensuring a tight seal around the adhesive and preventing bacterial invasion. Simultaneously, the remaining double-bonded active groups in ENR-25 are used to graft hydroxyethyl methacrylate (HMEA), introducing an appropriate amount of hydrophilic hydroxyl end groups to increase the adhesive's sweat resistance. Furthermore, the introduced HMEA contains acrylates, which offer excellent skin conformability and anti-allergenic properties.

[0007] More importantly, this invention introduces grafted ENR-HMEA combined with synthetic rubber, with the preferred ratio of ENR-HMEA to synthetic rubber being 9:4. This can enhance the viscosity of the hot melt adhesive to a certain extent without affecting its peel strength. Therefore, the resulting hot melt pressure-sensitive adhesive exhibits significantly improved tack and peel performance.

[0008] The second objective of this invention is to provide a method for preparing a novel hot-melt pressure-sensitive adhesive for black plaster matrix. The process of this invention is mature and stable, and solves the problem that traditional black plaster adhesives cannot be mass-produced.

[0009] One of the objectives of this invention is achieved through the following solution:

[0010] A novel hot-melt pressure-sensitive adhesive for black plaster matrix is ​​prepared from the following components in parts by weight:

[0011] 15-40 parts synthetic rubber

[0012] 10-30 parts naphthenic oil

[0013] Antioxidant 0.1-5 parts

[0014] 30-50 parts of hydrogenated petroleum resin

[0015] 5-20 parts of rosin resin

[0016] Pigments and fillers: 0.1-10 parts

[0017] 5-20 parts of grafted epoxidized natural rubber ENR-HMEA.

[0018] To further explain, the novel black plaster matrix hot melt pressure-sensitive adhesive is prepared from the following components in parts by weight:

[0019] 15-35 parts synthetic rubber

[0020] 20-30 parts naphthenic oil

[0021] Antioxidant 0.1-1 part

[0022] 30-40 parts of hydrogenated petroleum resin

[0023] 5-10 parts of rosin resin

[0024] Pigments and fillers: 0.1-2 parts

[0025] 10-20 parts of grafted epoxidized natural rubber ENR-HMEA.

[0026] To further explain, the novel black plaster matrix hot melt pressure-sensitive adhesive is prepared from the following components in parts by weight:

[0027] 18.1 parts of synthetic rubber

[0028] 23 parts naphthenic oil

[0029] Antioxidant 0.6 parts

[0030] 39.5 parts hydrogenated petroleum resin

[0031] 5-10 parts of rosin resin

[0032] Pigment and filler 0.8 parts

[0033] 12 parts of grafted epoxidized natural rubber ENR-HMEA.

[0034] To further explain, the method for synthesizing the grafted epoxidized natural rubber ENR-HMEA includes the following steps:

[0035] S1: Heat the torque rheometer to 120°C, and cut the epoxidized natural rubber into small pieces and add them to the torque rheometer;

[0036] S2: Weigh out the monomers hydroxyethyl methacrylate and dicumyl peroxide and add them separately to the rheometer of S1. Mix them together for 13-16 minutes and then discharge and cool.

[0037] S3: The mixture from S2 was refluxed with acetone in a Soxhlet extractor for 24 hours to remove the monomer hydroxyethyl methacrylate and the self-polymerized products of dicumyl peroxide and hydroxyethyl methacrylate. The product was then dried in a drying oven at 60-65℃ to constant weight to obtain the grafted product ENR-HMEA, with a grafting rate of 6%.

[0038] To further clarify, the epoxidized natural rubber mentioned is ENR-25, an epoxidized natural rubber with an epoxy value of 25, produced by Shandong Klein Co., Ltd.

[0039] To further clarify, the mass ratio of the epoxidized natural rubber, the monomer hydroxyethyl methacrylate, and dicumyl peroxide is 100:5:0.75.

[0040] To further clarify, the ratio of the grafted epoxidized natural rubber ENR-HMEA to the synthetic rubber is (9-9.5):4 by mass.

[0041] Further explanation: the synthetic rubber is one of SIS and SBS. The SIS is selected from one or a mixture of two or more of SIS 1106, SIS 1126, and SIS 1220 from Yueyang Baling Petrochemical Company. The SIS 1106 has a styrene content of 16% and a diblock content of 17%. The SIS 1126 has a styrene content of 16% and a diblock content of 50%. The SIS 1220 has a styrene content of 25% and a diblock content of 25%.

[0042] To further explain, the synthetic rubber is a blend of SIS 1126 and SIS 1220 in a mass ratio of 3:1.

[0043] Further explanation: the naphthenic oil is naphthenic oil of type 47135 produced by Xinjiang Karamay Company; the hydrogenated petroleum resin is C5 hydrogenated petroleum resin of type 5100 produced by ExxonMobil; the rosin resin is rosin resin of type KE95F produced by Kemalin Company; the antioxidant is one of antioxidants of type 1010 and antioxidant 168 produced by BASF Company; and the pigments and fillers are carbon black of type DL-8101 produced by Delan Chemical Company.

[0044] The second objective of this invention is achieved by the following technical solution:

[0045] A method for preparing a novel hot-melt pressure-sensitive adhesive base for black plaster includes the following steps:

[0046] S1: First, raise the kneader oil temperature to 175-180℃, pour an appropriate amount of naphthenic oil into the kneader, and add antioxidants at the same time. After the temperature inside the kneader reaches 130℃, add synthetic rubber and start stirring.

[0047] S2: After the synthetic rubber in S1 is kneaded until there are no obvious particles, add the grafted natural rubber ENR-HMEA according to the formula, knead for 20 minutes, then add the pigments and fillers according to the formula and stir evenly.

[0048] S3: Finally, add petroleum resin, rosin resin and the remaining naphthenic oil, vacuum to remove bubbles, discharge the material and cool to room temperature to obtain the black plaster hot melt adhesive matrix.

[0049] To further clarify, the amount of naphthenic oil in S1 is 60% of the total amount of synthetic rubber.

[0050] To further explain, the vacuuming pressure in S3 is 0.08-0.1 MPa, and the vacuuming time for removing air bubbles is 25-30 minutes.

[0051] Compared with the prior art, the beneficial effects of the present invention are at least in the following aspects:

[0052] (1) This invention introduces synthetic rubber SIS, petroleum resin and rosin resin, which take into account the advantages of good adhesion of traditional hot melt pressure sensitive adhesive. This invention preferably uses SIS 1126 and SIS 1220 in a mass ratio of 3:1. The high diblock content of SIS 1126 significantly improves the initial tack and peel strength of the formulation. SIS 1220 provides the advantages of low viscosity and high cohesive strength, adjusts the application viscosity of the formulation, and significantly improves the holding power. Combined with petroleum resin and rosin resin, the overall initial tack, peel strength and holding power of the formulation are good.

[0053] (2) Furthermore, the present invention introduces epoxy groups into epoxidized natural rubber ENR-25 with a grafting rate of 25%, and utilizes the excellent adhesion of epoxy groups to increase the adhesion effect of the formulated adhesive to different skin types; at the same time, it utilizes the remaining double bond active groups in ENR-25 to graft hydroxyethyl methacrylate (HMEA) to introduce an appropriate amount of hydrophilic hydroxyl end groups, thereby increasing the sweat resistance of the adhesive; on the other hand, the introduced HMEA contains acrylate, which has excellent skin conformability and anti-allergy properties;

[0054] More importantly, this invention introduces grafted ENR-HMEA and synthetic rubber in combination, with the preferred ratio of ENR-HMEA to synthetic rubber being 9:4. This can enhance the viscosity of the hot melt adhesive to a certain extent without affecting its peel strength. Therefore, the resulting hot melt pressure-sensitive adhesive has significantly improved tack and peel performance.

[0055] (3) In the synthesis of ENR-HMEA of the present invention, epoxidized natural rubber ENR-25 with a grafting rate of 25% is used. At the same time, the mass ratio of the epoxidized natural rubber, monomer hydroxyethyl methacrylate, and dicumyl peroxide is 100:5:0.75, so that the grafting rate of the grafted product ENR-HMEA is 6%. This results in good stability of the prepared epoxy groups, taking into account the advantages of natural rubber's good skin adhesion, the adhesion advantage of epoxy groups, and the skin conformity and appropriate hydrophilicity of hydroxyethyl methacrylate, which greatly improves the water and sweat resistance of the film.

[0056] (4) The process of the present invention is mature and stable, which solves the problem that traditional black plaster glue cannot be mass-produced. Detailed Implementation

[0057] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0058] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0059] This invention provides a novel hot-melt pressure-sensitive adhesive for black plaster base, prepared from the following components in parts by weight:

[0060] 15-40 parts synthetic rubber

[0061] 10-30 parts naphthenic oil

[0062] Antioxidant 0.1-5 parts

[0063] 30-50 parts of hydrogenated petroleum resin

[0064] 5-20 parts of rosin resin

[0065] Pigments and fillers: 0.1-10 parts

[0066] 5-20 parts of grafted epoxidized natural rubber ENR-HMEA.

[0067] To further explain, the novel black plaster matrix hot melt pressure-sensitive adhesive is prepared from the following components in parts by weight:

[0068] 15-35 parts synthetic rubber

[0069] 20-30 parts naphthenic oil

[0070] Antioxidant 0.1-1 part

[0071] 30-40 parts of hydrogenated petroleum resin

[0072] 5-10 parts of rosin resin

[0073] Pigments and fillers: 0.1-2 parts

[0074] 10-20 parts of grafted epoxidized natural rubber ENR-HMEA.

[0075] To further explain, the novel black plaster matrix hot melt pressure-sensitive adhesive is prepared from the following components in parts by weight:

[0076] 18.1 parts of synthetic rubber

[0077] 23 parts naphthenic oil

[0078] Antioxidant 0.6 parts

[0079] 39.5 parts hydrogenated petroleum resin

[0080] 5-10 parts of rosin resin

[0081] Pigment and filler 0.8 parts

[0082] 12 parts of grafted epoxidized natural rubber ENR-HMEA.

[0083] To further explain, the method for synthesizing the grafted epoxidized natural rubber ENR-HMEA includes the following steps:

[0084] S1: Heat the torque rheometer to 120°C, and cut the epoxidized natural rubber into small pieces and add them to the torque rheometer;

[0085] S2: Weigh out the monomers hydroxyethyl methacrylate and dicumyl peroxide and add them separately to the rheometer of S1. Mix them together for 13-16 minutes and then discharge and cool.

[0086] S3: The mixture from S2 was refluxed with acetone in a Soxhlet extractor for 24 hours to remove the monomer hydroxyethyl methacrylate and the self-polymerized products of dicumyl peroxide and hydroxyethyl methacrylate. The product was then dried in a drying oven at 60-65℃ to constant weight to obtain the grafted product ENR-HMEA, with a grafting rate of 6%.

[0087] To further clarify, the epoxidized natural rubber mentioned is ENR-25, an epoxidized natural rubber with an epoxy value of 25, produced by Shandong Klein Co., Ltd.

[0088] To further clarify, the mass ratio of the epoxidized natural rubber, the monomer hydroxyethyl methacrylate, and dicumyl peroxide is 100:5:0.75.

[0089] To further clarify, the ratio of the grafted epoxidized natural rubber ENR-HMEA to the synthetic rubber is (9-9.5):4 by mass.

[0090] To further clarify, the ratio of the grafted epoxidized natural rubber ENR-HMEA to the synthetic rubber is 9:4 by mass.

[0091] Further explanation: the synthetic rubber is one of SIS and SBS. The SIS is selected from one or a mixture of two or more of SIS 1106, SIS 1126, and SIS 1220 from Yueyang Baling Petrochemical Company. The SIS 1106 has a styrene content of 16% and a diblock content of 17%. The SIS 1126 has a styrene content of 16% and a diblock content of 50%. The SIS 1220 has a styrene content of 25% and a diblock content of 25%.

[0092] To further explain, the synthetic rubber is SIS 1126 or a blend of SIS 1126 and SIS 1220 in a mass ratio of 3:1.

[0093] Further explanation: the naphthenic oil is naphthenic oil of type 47135 produced by Xinjiang Karamay Company; the hydrogenated petroleum resin is C5 hydrogenated petroleum resin of type 5100 produced by ExxonMobil; the rosin resin is rosin resin of type KE95F produced by Kemalin Company; the antioxidant is one of antioxidants of type 1010 and antioxidant 168 produced by BASF Company; and the pigments and fillers are carbon black of type DL-8101 produced by Delan Chemical Company.

[0094] The formulation principle of this invention is as follows:

[0095] The synthetic rubber used in the formulation of this invention can be styrene-isoprene-styrene (SIS) or styrene-butadiene-styrene (SBS). The SIS used in this invention has a styrene content of 15-25% and a diblock content of 15-50%. SIS is softer than SBS. The content of the diblock, i.e., flexible segment, of SIS will affect the ring initial tack of the hot melt adhesive. Different diblock contents will change the properties of the prepared hot melt adhesive. Through a large number of experiments, this invention has found that the optimal blend of SIS1126 and SIS1220 at a mass ratio of 3:1 results in the best cohesiveness and wettability of the hot melt adhesive.

[0096] One of the key components in the formulation of this invention, grafted epoxidized natural rubber ENR-HMEA, is synthesized by introducing epoxy groups into epoxidized natural rubber ENR-25 with a grafting rate of 25%. Utilizing the excellent adhesion of these epoxy groups, the adhesive formulation is improved for different skin types. Simultaneously, hydroxyethyl methacrylate (HMEA) is grafted into the remaining double-bonded active groups in ENR-25, thereby introducing an appropriate amount of hydrophilic hydroxyl end groups and increasing the adhesive's sweat resistance. Furthermore, the introduced HMEA contains acrylates, which provide excellent skin adherence and anti-allergic properties.

[0097] In this invention, the grafted epoxidized natural rubber ENR-HMEA and synthetic rubber are preferably mixed in a 9:4 ratio. This ratio can enhance the viscosity of the hot melt adhesive to a certain extent without affecting its peel strength. Therefore, the resulting hot melt pressure-sensitive adhesive exhibits significantly improved tack and peel performance. The amount of ENR-HMEA added should not be too much, as ENR-HMEA itself has a relatively high viscosity. Adding too much will significantly affect the viscosity of the formulation, making the prepared hot melt adhesive too hard and reducing initial tack and peel strength. Conversely, the amount added should not be too little, as insufficient addition will affect the water and sweat resistance of the prepared hot melt adhesive, making it prone to detachment from human skin due to sweating.

[0098] In the synthesis of ENR-HMEA in this invention, epoxidized natural rubber ENR-25 with a grafting rate of 25% is used. The mass ratio of the epoxidized natural rubber, hydroxyethyl methacrylate monomer, and dicumyl peroxide is 100:5:0.75. The grafting rate of the grafted product ENR-HMEA is 6%, resulting in a product with good stability of epoxy groups. This combines the advantages of natural rubber, the adhesion strength of epoxy groups, the hydrophilicity and skin-adhesiveness of hydroxyethyl methacrylate, and appropriate hydrophilicity, significantly improving the water and sweat resistance of the film. The synthesis process is carried out at 130°C in a catalyst-free neutral environment, which is beneficial for improving the stability of the epoxy groups.

[0099] The naphthenic oil in the formulation of this invention is a type of petroleum-based rubber oil. This naphthenic oil is primarily composed of cycloalkanes, exhibiting good affinity and low or no pollution. Preferably, it is naphthenic oil of type 47135, sourced from Karamay, Xinjiang. In this formulation, it acts as a softening agent. Furthermore, the preferred dosage of the naphthenic oil is between 20-30 parts. When combined with the selected synthetic rubber, it helps maintain suitable peel strength and initial tack, meeting the performance requirements for decorative bonding. Simultaneously, it can improve the stability of the epoxy groups in the epoxidized natural rubber during the preparation process, avoiding ring-opening issues.

[0100] The pigments and fillers of this invention are organic pigments such as carbon black, which do not contain heavy metals, and different colored plaster bases can be formulated according to customer needs.

[0101] The formulation of this invention uses preferred hydrogenated DCPD petroleum resin and C5 hydrogenated petroleum resin, which have good compatibility with the SIS selected in this invention and high peel strength.

[0102] This invention also provides a method for preparing a novel hot-melt pressure-sensitive adhesive for black plaster matrix, comprising the following steps:

[0103] S1: First, raise the kneader oil temperature to 175-180℃, pour an appropriate amount of naphthenic oil into the kneader, and add antioxidants at the same time. After the temperature inside the kneader reaches 130℃, add synthetic rubber and start stirring.

[0104] S2: After the synthetic rubber in S1 is kneaded until there are no obvious particles, add the grafted natural rubber ENR-HMEA according to the formula, knead for 20 minutes, then add the pigments and fillers according to the formula and stir evenly.

[0105] S3: Finally, add petroleum resin, rosin resin and the remaining naphthenic oil, vacuum to remove bubbles, discharge the material and cool to room temperature to obtain the black plaster hot melt adhesive matrix.

[0106] To further clarify, the amount of naphthenic oil in S1 is 60% of the total amount of synthetic rubber.

[0107] To further explain, the vacuuming pressure in S3 is 0.08-0.1 MPa, and the vacuuming time for removing air bubbles is 25-30 minutes.

[0108] The preparation process of this invention should be noted as follows:

[0109] This application requires controlling the ratio of naphthenic oil to synthetic rubber in the initial input. The amount of naphthenic oil should be 60% of the rubber polymer for optimal swelling and melting effect. This is because the applicant has found through extensive experiments that when the initial rubber oil ratio is too high, the shear force during the melting process of the rubber polymer is lower, making it more difficult to melt. The rubber polymer used in this invention has a strong oil absorption capacity. When the rubber oil ratio is too low, it is not conducive to the swelling and melting of the rubber polymer. At the same time, excessive shear force can easily damage the production equipment. As the main component in the preparation of the hot melt adhesive of this application, poor swelling and melting effect of the rubber polymer will result in a large number of independent particles in the hot melt adhesive. More importantly, these particles will not melt when the hot melt adhesive is heated to a liquid state, thus significantly affecting the properties of the hot melt adhesive. Furthermore, these particles gradually accumulate and can easily clog the glue spraying equipment during the hot melt adhesive product spraying process, resulting in uneven glue spraying and greatly affecting the quality of the hot melt adhesive product.

[0110] The following are specific embodiments of the present invention. Unless otherwise specified, the raw materials, equipment and other materials used in the following embodiments can be obtained by purchasing.

[0111] Examples 1-4 and Comparative Examples 1-9

[0112] Weigh the raw materials according to the proportions in Table 1, and prepare the hot melt adhesive according to the preparation method in Table 1 to obtain hot melt adhesives for different embodiments. See Table 1 for details:

[0113] Table 1. Raw material ratios for Examples 1-4 and Comparative Examples 1-9

[0114]

[0115]

[0116]

[0117] The SIS 1106 has a styrene content of 16% and a diblock content of 17%; the SIS 1126 has a styrene content of 16% and a diblock content of 50%; the SIS 1220 has a styrene content of 25% and a diblock content of 25%; the SIS 1209 has a styrene content of 29% and a diblock content of <1%; the SIS 4016 has a styrene content of 18% and a diblock content of 75%; and the SBS is selected from Yueyang Baling Petrochemical's SBS 791, which has a styrene content of 30% and a diblock content of <1%.

[0118] The synthesis method of ENR(25)-HMEA is as follows:

[0119] The torque rheometer was heated to 120°C, and 100 parts of epoxidized natural rubber ENR-25 (commercially available epoxidized natural rubber with a 25% epoxidation grafting rate) were cut into small pieces and added to the torque rheometer. 5 parts of monomer hydroxyethyl methacrylate (HMEA) and 0.75 parts of initiator dicumyl peroxide (DCP) were weighed and added to the rheometer respectively. The mixture was then kneaded together for 15 minutes and then discharged and cooled.

[0120] The effluent mixture was refluxed with acetone in a Soxhlet extractor for 24 hours to remove monomers, initiators and HMEA self-polymers from the product. It was then dried in a 60°C drying oven to constant weight to obtain the grafted product ENR-HMEA. The grafting rate of this step was 6%.

[0121] The synthesis method of ENR(25)-HMEA (ENR:HMEA = 100:15) is the same as the above synthesis method, except that the ratio of epoxidized natural rubber ENR-25, hydroxyethyl methacrylate (HMEA), and dicumyl peroxide (DCP) is 100:15:0.75.

[0122] The synthesis method of ENR(25)-HMEA (ENR:HMEA = 100:1) is the same as the above synthesis method, except that the ratio of epoxidized natural rubber ENR-25, hydroxyethyl methacrylate (HMEA), and dicumyl peroxide (DCP) is 100:1:0.75.

[0123] The natural rubber ENR-25 grafted with only epoxy groups is an epoxidized natural rubber with an epoxy value of 25% produced by Shandong Klein Company.

[0124] The physical mixing method for ENR-25 and HMEA is as follows: simply mix 100 parts of epoxidized natural rubber ENR-25 with 5 parts of HMEA.

[0125] The synthesis methods of ENR(10)-HMEA and ENR(50)-HMEA can be the same as those of ENR(25)-HMEA. Furthermore, ENR(10) is an epoxidized natural rubber with an epoxy value of 10% produced by Shandong Klein Co., Ltd.; ENR(50) is an epoxidized natural rubber with an epoxy value of 50% produced by Shandong Klein Co., Ltd.

[0126] The preparation method of the above hot melt adhesive is as follows:

[0127] S1: First, raise the kneader oil temperature to 175℃, pour an appropriate amount of naphthenic oil into the kneader, and add antioxidants at the same time. After the temperature inside the kneader reaches 130℃, add synthetic rubber and start stirring; the amount of naphthenic oil added is 60% of the total amount of synthetic rubber.

[0128] S2: After the synthetic rubber in S1 is kneaded until there are no obvious particles, add the grafted natural rubber ENR-HMEA according to the formula, knead for 20 minutes, then add the pigments and fillers according to the formula and stir evenly.

[0129] S3: Finally, add petroleum resin, rosin resin and the remaining naphthenic oil, vacuum to remove bubbles, discharge the material and cool to room temperature to obtain the black plaster hot melt adhesive matrix.

[0130] The difference between the preparation processes of Examples 2-4 and Comparative Examples 1-2 and Example 1 lies in the different natural rubbers added in S2.

[0131] Effect evaluation and performance testing

[0132] The properties of the hot melt adhesives in each embodiment and comparative example were tested using the following methods:

[0133] The black plaster hot melt adhesive obtained according to the examples and comparative examples was evenly applied to a PET substrate using a transfer coating method, with an adhesive thickness of 30±2 g / m. 2 The ring initial tack and peel strength properties of the samples were tested under indoor temperature conditions of 23±2℃ and relative humidity of 45±10%. The peel strength of the hot melt adhesive was tested according to the specific provisions of national standard GB / T 2792-2014, and the ring initial tack was tested according to the specific provisions of national standard GB / T 31125—2014.

[0134] Simultaneously, the direct coating method was used, with a coating thickness of 110±5 g / m². 2 On a white cotton fabric substrate, observe the seepage on the back of the white cotton fabric. At the same time, cut a size of 6×4cm (length×width) and attach it to the elbow joint and the back where sweat is easy to get, and observe its adhesion effect.

[0135] The test items and results are shown in Table 2:

[0136] Table 2 shows the hot melt adhesive performance test data for each embodiment and comparative example.

[0137]

[0138]

[0139] As can be seen from Table 2 above, the optimal embodiment of the present invention is Example 1, which combines the advantages of natural rubber's good adhesion to the skin, the adhesion advantage of epoxy groups, and the skin-fitting properties and appropriate hydrophilicity of hydroxyethyl methacrylate, thereby improving the water and sweat resistance of the film. It is not easy to fall off after heavy sweating or when taking a bath with the plaster on.

[0140] Example 2 uses ENR-10 with a low epoxy value. Due to the small number of epoxy groups, the probability of collision with HMEA molecules is low, and the grafting rate of HMEA is less than 2%. Therefore, HMEA's hydrophilic properties are not good enough, and its skin adhesion is poor after sweating.

[0141] Example 3 uses commercially available ENR50 with an epoxy value of 50. There are too many epoxy groups. Compared with other components in the formulation, the stability of epoxy groups is relatively poor. During long-term storage and transportation, there will be slow internal self-polymerization and intermolecular reactions. Over time, the adhesive will slowly harden and yellow, and the adhesion will gradually decrease, thus reducing the storage period of the adhesive.

[0142] Example 4: A simple physical mixture of ENR and HMEA resulted in very low overall adhesion because the colloid itself lacked sufficient cohesive strength due to the absence of functional macromolecules.

[0143] In Comparative Example 1, unmodified natural rubber was added. Since natural rubber has a better fit to human skin than synthetic rubber and has a certain degree of sweat resistance, the initial peel strength was almost not increased after adding natural rubber, but the fit to human skin was significantly improved.

[0144] Comparative Example 2 added epoxy-modified natural rubber ENR-25. With the addition of epoxy groups, the adhesion of the film to the test substrate was significantly improved, and the adhesion force was significantly increased. However, the sweat resistance was still poor, and it was easy to fall off when exposed to human skin sweat.

[0145] In Comparative Example 3, the synthetic rubber was not a blend of SIS 1126 and SIS 1220, but only SIS 1126 was used. The SIS 1126 had a styrene content of 16% and a diblock content of 50%. The initial tack was slightly increased, the cohesive strength was reduced, and the peel and holding power were reduced.

[0146] The synthetic rubber used in Comparative Example 4 was SIS 1220, which had a diblock content of 25% and thus a lower initial tack.

[0147] In the synthesis of ENR(25)-HMEA in Comparative Example 5, the ratio of epoxidized natural rubber ENR-25, hydroxyethyl methacrylate (HMEA), and dicumyl peroxide (DCP) was 100:15:0.75. The introduction of too many hydrophilic hydroxyl end groups resulted in excessive hydrophilicity, which easily led to a decrease in the water solubility and adhesion of some adhesives after soaking in water, resulting in detachment.

[0148] In the synthesis of ENR(25)-HMEA in Comparative Example 6, the ratio of epoxidized natural rubber ENR-25, hydroxyethyl methacrylate (HMEA), and dicumyl peroxide (DCP) was 100:1:0.75. The introduction of too few hydrophilic hydroxyl end groups resulted in the rubber being oleophilic and hydrophobic, with poor sweat resistance and reduced skin conformability.

[0149] The synthetic rubber used in Comparative Example 7 is SBS 791. Since SBS is harder than SIS, it significantly reduces the peel strength and initial tack of the hot melt adhesive.

[0150] In Comparative Example 8, the amount of synthetic rubber was more than 30 parts and no ENR(25)-HMEA was added. It had almost no water and sweat resistance and would fall off quickly when exposed to sweat during exercise.

[0151] In Comparative Example 9, the amount of ENR(25)-HMEA added was twice that of Example 1. Excessive ENR(25)-HMEA had a significant impact on the viscosity of the hot melt adhesive, making the adhesive harder and reducing initial tack and peel strength.

[0152] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A hot-melt pressure-sensitive adhesive for black plaster base, characterized in that, It is prepared from the following components in parts by weight: 18.1 parts of synthetic rubber 23 parts naphthenic oil Antioxidant 0.6 parts 39.5 parts hydrogenated petroleum resin 6 parts rosin resin Pigment and filler 0.8 parts 12 parts of grafted epoxidized natural rubber ENR-HMEA; The synthetic rubber is one of SIS and SBS. The SIS is selected from one or a mixture of two or more of SIS 1106, SIS 1126, and SIS 1220 from Yueyang Baling Petrochemical Company. The styrene content of the SIS is 15-25%, and the diblock content is 15-60%. The naphthenic oil is naphthenic oil of type 47135 produced by Xinjiang Karamay Company. The hydrogenated petroleum resin is C5 hydrogenated petroleum resin of type 5100 from ExxonMobil Company. The rosin resin is rosin resin of type KE95F from Kemalin Company. The antioxidant is one of antioxidants of type 1010 and antioxidant 168 produced by BASF Company. The pigment and filler is carbon black of type DL-8101 from Delan Chemical Company. The method for synthesizing the grafted epoxidized natural rubber ENR-HMEA includes the following steps: S1: Heat the torque rheometer to 120°C, and cut the epoxidized natural rubber into small pieces and add them to the torque rheometer; S2: Weigh out the monomers hydroxyethyl methacrylate and dicumyl peroxide and add them separately to the rheometer of S1. Mix them together for 13-16 minutes and then discharge and cool. S3: The mixture from S2 was refluxed with acetone in a Soxhlet extractor for 24 hours to remove the monomers hydroxyethyl methacrylate and the self-polymerized products of dicumyl peroxide and hydroxyethyl methacrylate. The product was then dried in a drying oven at 60-65℃ to constant weight to obtain the grafted product ENR-HMEA, with a grafting rate of 6%.

2. The hot-melt pressure-sensitive adhesive for black plaster matrix as described in claim 1, characterized in that, The epoxidized natural rubber is ENR-25, an epoxidized natural rubber with an epoxy value of 25, produced by Shandong Klein Co., Ltd.

3. The hot-melt pressure-sensitive adhesive for black plaster matrix as described in claim 2, characterized in that, The mass ratio of the epoxidized natural rubber, the monomer hydroxyethyl methacrylate, and dicumyl peroxide is 100:5:0.

75.

4. The hot-melt pressure-sensitive adhesive for black plaster matrix as described in claim 1, characterized in that, The ratio of the grafted epoxidized natural rubber ENR-HMEA to the synthetic rubber is (9-9.5):4 by mass.

5. A method for preparing a hot-melt pressure-sensitive adhesive for a black plaster matrix as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: First, raise the kneader oil temperature to 175-180℃, pour an appropriate amount of naphthenic oil into the kneader, and add antioxidants at the same time. After the temperature inside the kneader reaches 130℃, add synthetic rubber and start stirring. S2: After the synthetic rubber in S1 is kneaded until there are no obvious particles, add the grafted natural rubber ENR-HMEA according to the formula, knead for 20 minutes, then add the pigments and fillers according to the formula and stir evenly. S3: Finally, add petroleum resin, rosin resin and the remaining naphthenic oil, vacuum to remove bubbles, discharge the material and cool to room temperature to obtain the black plaster hot melt adhesive matrix.

6. The method for preparing the hot-melt pressure-sensitive adhesive for the black plaster matrix as described in claim 5, characterized in that, The amount of naphthenic oil in S1 is 60% of the total amount of synthetic rubber.

7. The method for preparing the hot-melt pressure-sensitive adhesive for the black plaster matrix as described in claim 5, characterized in that, The vacuuming pressure in S3 is 0.08-0.1 MPa, and the vacuuming time for removing air bubbles is 25-30 minutes.

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