A low-temperature hot melt adhesive and preparation method thereof

Abstract

The present invention discloses a low-temperature hot melt adhesive and a preparation method thereof, and relates to the technical field of polyolefin system hot melt adhesive. A low-temperature hot melt adhesive comprises 45-65 parts of base resin, 28-44 parts of tackifying resin, 3-6 parts of SIS rubber, 3-6 parts of wax, 1.6-2.5 parts of polyisobutylene, 5-8 parts of maleic anhydride grafted POP, 3-4 parts of reinforcing fillers and 0.5-1 parts of antioxidant, wherein the base resin comprises APAO resin, the tackifying resin comprises a petroleum liquid resin and at least one of C5 hydrogenated petroleum resin or C5 / C9 copolymerized petroleum resin, and the SIS rubber is a SIS rubber containing 25%-35% of diblock SI. By using APAO resin as the base resin of the hot melt adhesive, in combination with tackifying resin, SIS rubber and reinforcing filler, the obtained polyolefin hot melt adhesive has a lower softening point, can be melted and used normally without being heated to above 150°C, is conducive to reducing the risk of being scalded during use, and greatly improves the safety of the polyolefin hot melt adhesive.

Description

Technical Field

[0001] The invention relates to the technical field of polyolefin hot melt adhesives, and in particular to a low-temperature hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive is a polymer material that is fluid when heated and quickly solidifies to form a bond after cooling. It is favored for its advantages such as easy operation, fast curing speed and no solvent volatilization. It is currently widely used in packaging, furniture, shoemaking, electronics, construction and other fields.

[0003] Commonly used hot melt adhesives are mainly EVA hot melt adhesive and polyolefin hot melt adhesive. EVA hot melt adhesive is a hot melt adhesive based on ethylene-vinyl acetate copolymer (EVA), while polyolefin hot melt adhesive is a hot melt adhesive based on polyolefin polymers (such as polyethylene and polypropylene).

[0004] Since the softening point of EVA is generally in the range of 80-100℃, and the softening point of polyolefin is generally in the range of 110-180℃, the produced EVA hot melt adhesive can be melted and used normally at a lower operating temperature, while the polyolefin hot melt adhesive needs to be heated to an operating temperature of 150℃ or higher to be used normally. Therefore, most of the low-temperature hot melt adhesive sticks used in daily life on the market are EVA hot melt adhesives, and polyolefin hot melt adhesives are widely used in industrial applications. Because the structure of polyolefin does not contain polar groups such as vinyl acetate, the odor of polyolefin hot melt adhesive is not only smaller than that of EVA hot melt adhesive, but also has higher environmental protection performance, and can also be used for bonding of a variety of non-polar and polar materials, with a wider bonding range. Therefore, more and more polyolefin hot melt adhesives are currently appearing in hot melt adhesive sticks used in daily life.

[0005] However, due to the high operating temperature of polyolefin hot melt adhesive, operators still face the potential safety hazard of being easily burned when using polyolefin hot melt adhesive sticks in daily life. If low-softening-point polyolefin resin is directly used to prepare low-temperature hot melt adhesive, and the technical problem of reducing the safety hazard of polyolefin hot melt adhesive is solved, a series of other technical problems will arise, such as the hot melt adhesive is too soft and the adhesive stick is difficult to shape. Therefore, it is of great significance to develop a polyolefin hot melt adhesive that is easy to shape, has a low operating temperature, and is suitable for daily use. Summary of the invention

[0006] In order to lower the operating temperature of polyolefin hot melt adhesive, the polyolefin hot melt adhesive can be melted and used normally without being heated to above 150°C, thereby reducing the risk of burns from high temperature during use and improving the safety of the hot melt adhesive. The present application provides a low-temperature hot melt adhesive and a preparation method thereof.

[0007] In the first aspect, the low-temperature hot melt adhesive provided in the present application adopts the following technical solution:

[0008] A low-temperature hot melt adhesive comprises the following raw materials in parts by weight:

[0009] Base resin: 45-65 parts;

[0010] Tackifying resin: 28-44 parts;

[0011] SIS rubber: 3-6 parts;

[0012] Wax material: 3-6 parts;

[0013] Polyisobutylene 1.6-2.5 parts;

[0014] Maleic anhydride grafted POP: 5-8 parts;

[0015] Reinforcing filler: 3-4 parts;

[0016] 0.5-1 part of antioxidant;

[0017] The base resin includes a low softening point APAO resin, the tackifying resin includes a compound of a petroleum liquid resin and at least one of a C5 hydrogenated petroleum resin or a C5 / C9 copolymerized petroleum resin, and the SIS rubber is a SIS rubber containing 25%-35% of a two-block SI.

[0018] By adopting the above technical scheme, using APAO resin with a low softening point as the base resin of the hot melt adhesive, combined with a tackifying resin containing petroleum liquid resin, a SIS rubber containing two-block SI and a harder reinforcing filler, the prepared polyolefin hot melt adhesive is not only easy to form, but also has a low softening point. The hot melt adhesive can be melted and used normally without being heated to an operating temperature above 150°C, which is beneficial to reducing the risk of burns to operators during use and greatly improving the safety of the hot melt adhesive.

[0019] Optionally, the base resin also includes a metallocene ethylene-octene copolymer, and the mixing weight ratio of the APAO resin to the metallocene ethylene-octene copolymer is 1:(0.6-1).

[0020] By adopting the above technical solution, adding a certain proportion of metallocene ethylene-octene copolymer to the base resin is not only conducive to improving the bonding strength of the polyolefin hot melt adhesive, but also can further reduce the softening point of the polyolefin hot melt adhesive. Secondly, within this mixing weight ratio range, as the content of the metallocene ethylene-octene copolymer increases, the bonding strength of the polyolefin hot melt adhesive can be further improved.

[0021] Optionally, the softening point of the APAO resin is in the range of 115-126° C., and the metallocene ethylene-octene copolymer is one of the brands POP GA1900 or POP GA1950.

[0022] By adopting the above technical scheme, the metallocene ethylene-octene copolymer is selected from one of the brands POP GA1900 and POP GA1950. Both metallocene ethylene-octene copolymers have low glass transition temperatures, but the melt viscosity range of the two is wide, among which the melt viscosity of POP GA1900 is 8.2 Pa·s (177°C), and the melt viscosity of POP GA1950 is 17 Pa·s (177°C), so that they can be matched according to APAO resins with different softening points, which is beneficial to lowering the softening point of the hot melt adhesive while maintaining the hot melt adhesive with good bonding properties.

[0023] Optionally, the tackifying resin is a mixture of the petroleum liquid resin, the C5 hydrogenated petroleum resin and the C5 / C9 copolymerized petroleum resin, and the mixing weight ratio of the petroleum liquid resin, the C5 hydrogenated petroleum resin and the C5 / C9 copolymerized petroleum resin is 1:(2-5):(4.5-5).

[0024] By adopting the above technical solution, when the tackifying resin is mixed and compounded with petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in a weight ratio of 1: (2-5): (4.5-5), it is beneficial to improve the bonding strength of the hot melt adhesive while maintaining the low softening point of the polyolefin hot melt adhesive. Moreover, within this range, as the proportion of petroleum liquid resin decreases, the bonding strength of the hot melt adhesive can be further improved, while the softening point of the hot melt adhesive is not greatly improved, which is within an acceptable range.

[0025] Optionally, the relative molecular mass of the two-block SI in the SIS rubber is 50,000-60,000, and the block ratio of the two-block SI is (11-20): (80-89).

[0026] By adopting the above technical solution, when the SIS rubber contains 25%-35% of diblock SI, and the relative molecular mass of the diblock SI is 50000-60000, and the block ratio is in the range of (11-20): (80-89), the hot melt adhesive not only has a lower softening point but also has good bonding strength.

[0027] Optionally, the wax material is a mixture of paraffin wax and Fischer-Tropsch wax, and the mixing weight ratio of the paraffin wax to the Fischer-Tropsch wax is 1:(0.2-0.5).

[0028] By adopting the above technical scheme, paraffin wax and Fischer-Tropsch wax are mixed and compounded in a weight ratio of 1: (0.2-0.5), which is not only beneficial to improving the melt fluidity of the hot melt adhesive and improving the processing performance of the hot melt adhesive so that it can be easier to form, but also beneficial to lowering the softening point of the hot melt adhesive while allowing the hot melt adhesive to maintain good bonding properties.

[0029] Optionally, the relative molecular weight of the polyisobutylene is 35,000-50,000.

[0030] By adopting the above technical solution, when the relative molecular weight of polyisobutylene is 35000-50000, the polyisobutylene becomes semi-solid, has good processing performance and low glass transition temperature, which is beneficial to improving the melt fluidity of the hot melt adhesive.

[0031] Optionally, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and the mixing weight ratio of the antioxidant 1010 to the antioxidant 168 is 1:(2.33-4).

[0032] By adopting the above technical solution, a certain synergistic effect can be produced between the antioxidant 1010 and the antioxidant 168, which is beneficial to improving the antioxidant property of the hot melt adhesive and preventing the hot melt adhesive from turning yellow or reducing its viscosity due to oxidation after being placed for a long time.

[0033] In the second aspect, the present application provides a method for preparing a low-temperature hot melt adhesive using the following technical solution:

[0034] A method for preparing a low-temperature hot melt adhesive comprises the following steps:

[0035] S1, firstly, 10% of the base resin is fully mixed with the wax material, polyisobutylene, maleic anhydride grafted POP and antioxidant at a mixing temperature of 160-180° C., and then the remaining base resin, SIS rubber and reinforcing filler are added, and the mixture is fully stirred to obtain a first mixture;

[0036] S2, lowering the mixing temperature to 140-150°C, then adding a tackifying resin, and continuing stirring for 20-30 minutes to obtain a second mixture;

[0037] S3, subjecting the second mixture to vacuum exhaust treatment, and then extruding the second mixture, and quickly pulling it into a circulating cooling water tank with a cooling solution temperature of 5° C. for cooling, and then cutting and drying, thereby obtaining a low-temperature hot melt adhesive.

[0038] By adopting the above technical solution, the temperature is lowered when mixing the tackifying resin, which is beneficial to reduce the impact of high-temperature melt mixing on the tackifying resin, prevent the tackifying resin from yellowing, and improve the appearance performance of the hot melt adhesive; and the hot melt adhesive is quickly cooled after extrusion, which can not only quickly shape the hot melt adhesive, but also prevent the hot melt adhesive from crystallizing, thereby reducing the impact on the transparency and other properties of the product. Secondly, the preparation method of low-temperature hot melt adhesive is simple, which is conducive to subsequent mass production.

[0039] Optionally, the cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0040] By adopting the above technical solution, a certain amount of anti-sticking liquid is added to the cooling solution, so that the surface of the hot melt adhesive can be anti-sticked while it is cooling and shaping, further simplifying the process flow. It is not only beneficial to prevent the knife from sticking when cutting the hot melt adhesive, but also beneficial to the subsequent transportation and storage of the hot melt adhesive.

[0041] In summary, the technical solution of this application has at least one of the following beneficial effects:

[0042] 1. By using low softening point APAO resin as the base resin of hot melt adhesive, combined with tackifying resin containing petroleum liquid resin, SIS rubber containing two-block SI and harder reinforcing filler, it is beneficial to prepare a polyolefin hot melt adhesive stick that is easy to shape and has a low softening point, thereby reducing the risk of operators being scalded during use and greatly improving the safety of hot melt adhesive.

[0043] 2. By adding a certain amount of metallocene ethylene-octene copolymer into the base resin, it is not only beneficial to improve the bonding strength of the polyolefin hot melt adhesive, but also beneficial to further reduce the softening point of the polyolefin hot melt adhesive.

[0044] 3. By adding a tackifying resin mixed with petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in a weight ratio of 1: (2-5): (4.5-5), it is beneficial to improve the bonding strength of the polyolefin hot melt adhesive while maintaining a low softening point of the polyolefin hot melt adhesive. DETAILED DESCRIPTION

[0045] The present application is further described in detail below with reference to examples and comparative examples. Example

[0046] [Example 1]

[0047] A low-temperature hot melt adhesive, comprising the following raw materials:

[0048] 60kg base resin, 30kg tackifying resin, 5kg SIS rubber, 6kg wax, 2kg polyisobutylene, 7kg maleic anhydride grafted POP, 3.5kg activated calcium carbonate and 0.8kg antioxidant.

[0049] In this embodiment, the base resin is APAO resin, specifically Evonik APAO 703, which has a softening point of 126° C. and an open time of 15 seconds.

[0050] The tackifying resin is a mixture of petroleum liquid resin and C5 hydrogenated petroleum resin in a weight ratio of 1:5, that is, the addition amount of petroleum liquid resin is 5kg, and the addition amount of C5 hydrogenated petroleum resin is 25kg. Among them, the petroleum liquid resin is NOVARES LA300, and the C5 hydrogenated petroleum resin is H5-1001. The softening point of this grade of C5 hydrogenated petroleum resin is 100℃, and the acid value is ≤0.1mgKOH / g.

[0051] SIS rubber contains 30% diblock SI, the molecular weight of the diblock SI is 60,000, and the block ratio of SI is 15:85.

[0052] The wax material is a mixture of paraffin wax and Fischer-Tropsch wax in a weight ratio of 1:0.5, that is, the added amount of paraffin wax is 4 kg and the added amount of Fischer-Tropsch wax is 2 kg.

[0053] The polyisobutylene used is HRD-500 produced by Hongruida, and the molecular weight of the polyisobutylene of this grade is 50000. The maleic anhydride grafted POP is specifically selected as AFFINITY GA 1000R.

[0054] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:3, that is, the added amount of antioxidant 1010 is 0.2 kg, and the added amount of antioxidant 168 is 0.6 kg.

[0055] A method for preparing a low-temperature hot melt adhesive comprises the following steps:

[0056] S1. First, 10% of the base resin is mixed with wax, polyisobutylene, maleic anhydride grafted POP and antioxidant at a mixing temperature of 145° C. for 10 minutes, and then the remaining base resin, SIS rubber and reinforcing filler are added and stirred for 20 minutes to obtain a first mixture;

[0057] S2, lowering the mixing temperature to 135° C., then adding a tackifying resin, and continuing stirring for 30 minutes to obtain a second mixture;

[0058] S3. Maintaining a vacuum environment with a vacuum degree of -0.1 MPa to perform vacuum exhaust treatment on the second mixture, then extruding the second mixture through an extruder, and quickly pulling it into a circulating cooling water tank with a cooling solution temperature of 5°C for cooling, and then cutting it into a hot melt adhesive stick with a length of 20 cm, and drying the adhesive stick to obtain a low-temperature hot melt adhesive.

[0059] The cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0060] [Example 2]

[0061] A low-temperature hot melt adhesive, comprising the following raw materials:

[0062] 45kg base resin, 44kg tackifying resin, 6kg SIS rubber, 3kg wax, 2.5kg polyisobutylene, 5kg maleic anhydride grafted POP, 3kg activated calcium carbonate and 0.5kg antioxidant.

[0063] In this embodiment, the base resin is APAO resin, specifically Evonik APAO 704, which has a softening point of 115° C. and an open time of 80 seconds.

[0064] The tackifying resin is a mixture of petroleum liquid resin and C5 / C9 copolymerized petroleum resin in a weight ratio of 1:4.5, that is, the addition amount of petroleum liquid resin is 8kg, and the addition amount of C5 / C9 copolymerized petroleum resin is 36kg. Among them, the petroleum liquid resin is NOVARES LA300, and the C5 / C9 copolymerized petroleum resin is HH2-1103. The softening point of this grade of C5 / C9 copolymerized petroleum resin is 110℃, and the acid value is ≤0.5mgKOH / g.

[0065] SIS rubber contains 25% diblock SI, the molecular weight of the diblock SI is 50,000, and the block ratio of SI is 15:85.

[0066] The wax material is a mixture of paraffin wax and Fischer-Tropsch wax in a weight ratio of 1:0.5, that is, the added amount of paraffin wax is 2 kg and the added amount of Fischer-Tropsch wax is 1 kg.

[0067] The polyisobutylene used is HRD-350 produced by Hongruida, and the molecular weight of the polyisobutylene of this grade is 35000. The maleic anhydride grafted POP is specifically selected as AFFINITY GA 1000R.

[0068] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:2.33, that is, the added amount of antioxidant 1010 is 0.15 kg, and the added amount of antioxidant 168 is 0.35 kg.

[0069] A method for preparing a low-temperature hot melt adhesive comprises the following steps:

[0070] S1, firstly mix 10% of the base resin with wax, polyisobutylene, maleic anhydride grafted POP and antioxidant at a mixing temperature of 140° C. for 10 minutes, then add the remaining base resin, SIS rubber and reinforcing filler, and stir thoroughly for 20 minutes to obtain a first mixture;

[0071] S2, lowering the mixing temperature to 130° C., then adding a tackifying resin, and continuing stirring for 30 minutes to obtain a second mixture;

[0072] S3. Maintaining a vacuum environment with a vacuum degree of -0.1 MPa to perform vacuum exhaust treatment on the second mixture, then extruding the second mixture through an extruder, and quickly pulling it into a circulating cooling water tank with a cooling solution temperature of 5°C for cooling, and then cutting it into a hot melt adhesive stick with a length of 20 cm, and drying the adhesive stick to obtain a low-temperature hot melt adhesive.

[0073] The cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0074] [Example 3]

[0075] A low-temperature hot melt adhesive, comprising the following raw materials:

[0076] 65kg base resin, 28kg tackifying resin, 3kg SIS rubber, 4.8kg wax, 1.6kg polyisobutylene, 8kg maleic anhydride grafted POP, 4kg activated calcium carbonate and 1kg antioxidant.

[0077] In this embodiment, the base resin is APAO resin and metallocene ethylene-octene copolymer mixed in a weight ratio of 1:0.8, that is, the addition amount of APAO resin is 33.3 kg, and the addition amount of metallocene ethylene-octene copolymer is 26.7 kg. Among them, the APAO resin is Evonik APAO 703, the softening point of this grade of APAO resin is 126°C, and the open time is 15s; the metallocene ethylene-octene copolymer is POP GA1950, and the Brookfield viscosity of this grade is 17 Pa·s (177°C).

[0078] The tackifying resin is a mixture of petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in a weight ratio of 1:2:5, that is, the added amount of petroleum liquid resin is 3.5kg, the added amount of C5 hydrogenated petroleum resin is 7kg, and the added amount of C5 / C9 copolymerized petroleum resin is 17.5kg.

[0079] SIS rubber contains 35% diblock SI, the molecular weight of the diblock SI is 60,000, and the block ratio of SI is 11:89.

[0080] The wax material is a mixture of paraffin wax and Fischer-Tropsch wax in a weight ratio of 1:0.2, that is, the added amount of paraffin wax is 4 kg and the added amount of Fischer-Tropsch wax is 0.8 kg.

[0081] The polyisobutylene used is HRD-450 produced by Hongruida, and the molecular weight of the polyisobutylene of this grade is 45000. The maleic anhydride grafted POP is specifically selected as AFFINITY GA 1000R.

[0082] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:4, that is, the added amount of antioxidant 1010 is 0.2 kg, and the added amount of antioxidant 168 is 0.8 kg.

[0083] A method for preparing a low-temperature hot melt adhesive comprises the following steps:

[0084] S1, firstly mix 10% of the base resin with wax, polyisobutylene, maleic anhydride grafted POP and antioxidant at a mixing temperature of 150° C. for 10 minutes, then add the remaining base resin, SIS rubber and reinforcing filler, and stir thoroughly for 20 minutes to obtain a first mixture;

[0085] S2, lowering the mixing temperature to 140° C., then adding a tackifying resin, and continuing stirring for 30 minutes to obtain a second mixture;

[0086] S3. Maintaining a vacuum environment with a vacuum degree of -0.1 MPa to perform vacuum exhaust treatment on the second mixture, then extruding the second mixture through an extruder, and quickly pulling it into a circulating cooling water tank with a cooling solution temperature of 5°C for cooling, and then cutting it into a hot melt adhesive stick with a length of 20 cm, and drying the adhesive stick to obtain a low-temperature hot melt adhesive.

[0087] The cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0088] [Example 4]

[0089] A low-temperature hot melt adhesive, which differs from [Example 1] in that the base resin is different.

[0090] In this embodiment, the base resin is replaced by APAO resin of the same grade and metallocene ethylene-octene copolymer in equal amounts, which are mixed and compounded in a weight ratio of 1:0.6, that is, the addition amount of APAO resin is 37.5 kg, and the addition amount of metallocene ethylene-octene copolymer is 22.5 kg. Among them, the metallocene ethylene-octene copolymer uses POP GA1900, and the Brookfield viscosity of this grade is 8.2 Pa·s (177°C).

[0091] [Example 5]

[0092] A low-temperature hot melt adhesive, which differs from [Example 1] in that the base resin is different.

[0093] In this embodiment, the base resin is replaced by APAO resin of the same grade and metallocene ethylene-octene copolymer in equal amounts, mixed and compounded in a weight ratio of 1:1, that is, the addition amount of APAO resin is 30 kg, and the addition amount of metallocene ethylene-octene copolymer is 30 kg. Among them, the metallocene ethylene-octene copolymer uses POP GA1900, and the Brookfield viscosity of this grade is 8.2 Pa·s (177°C).

[0094] [Example 6]

[0095] A low-temperature hot melt adhesive, which differs from [Example 5] in that the tackifying resin is different.

[0096] In this embodiment, the tackifying resin is replaced by petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in equal amounts and mixed in a weight ratio of 1:2:5. That is, the amount of petroleum liquid resin added is 3.75 kg, the amount of C5 hydrogenated petroleum resin added is 7.5 kg, and the amount of C5 / C9 copolymerized petroleum resin added is 18.75 kg.

[0097] [Example 7]

[0098] A low-temperature hot melt adhesive, which differs from [Example 5] in that the tackifying resin is different.

[0099] In this embodiment, the tackifying resin is replaced by petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in equal amounts and mixed in a weight ratio of 1:5:4.5. That is, the amount of petroleum liquid resin added is 2.86 kg, the amount of C5 hydrogenated petroleum resin added is 14.29 kg, and the amount of C5 / C9 copolymerized petroleum resin added is 12.86 kg.

[0100] [Example 8]

[0101] A low-temperature hot melt adhesive, which differs from [Example 7] in that the SIS rubber is different.

[0102] In this embodiment, the SIS rubber contains 35% of diblock SI, the molecular weight of the diblock SI is 60,000, and the block ratio of SI is 15:85.

[0103] [Example 9]

[0104] A low-temperature hot melt adhesive, which differs from [Example 8] in that the SIS rubber is different.

[0105] In this embodiment, the SIS rubber contains 35% of diblock SI, the molecular weight of the diblock SI is 60,000, and the block ratio of SI is 11:89. Comparative Example

[0106] [Comparative Example 1]

[0107] A hot melt adhesive is purchased from a common polyolefin hot melt adhesive stick on the market, and the specific brand is 7150N.

[0108] [Comparative Example 2]

[0109] A hot melt adhesive, which differs from [Example 1] in that an equal amount of tackifying resin is replaced by C5 hydrogenated petroleum resin.

[0110] [Comparative Example 3]

[0111] A hot melt adhesive, which differs from [Example 1] in that no reinforcing filler is added.

[0112] Performance test data

[0113] 1. Softening point test (melting temperature): Refer to "GB / T 15332-1994 Hot Melt Adhesive Softening Point Ring and Ball Method" for testing, and record the lowest temperature (℃) when the softening state is reached. Among them, silicone oil is used as the heating medium.

[0114] 2. Bonding strength test: Refer to GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material) for testing, and record the tensile shear strength (MPa) and bonding interface failure type of each embodiment and comparative example. The bonding medium is a standard copper plate.

[0115] Table 1 Partial performance test data of hot melt adhesive

[0116]

[0117] Combining Example 1 with Comparative Examples 1-3 and the data in Table 1, it can be seen that the use of low softening point APAO as the base resin, combined with petroleum liquid resin, SIS rubber containing a certain amount of two-block SI and reinforcing filler, compared with the hot melt adhesive of the traditional polyolefin system, has a lower softening point and can be smoothly formed into a hot melt adhesive stick. In terms of use, it can be used normally without heating to above 150°C. However, due to the reduction in the softening point of the base resin, the bonding strength of the hot melt adhesive stick is greatly reduced. However, although the petroleum liquid resin in the tackifying resin can reduce the softening point of the colloid as a whole, it will also further reduce the melt viscosity of the colloid. When combined with SIS rubber with good cohesion and adhesion properties, it can compensate for the melt strength and viscosity of the low softening point APAO resin to a certain extent. However, after adding petroleum liquid resin and SIS rubber at the same time, the overall hardness of the hot melt adhesive will decrease, and it will be difficult to form. Therefore, it is still necessary to match reinforcing fillers and wax materials to improve the molding effect of the hot melt adhesive, so as to facilitate the preparation of an olefin hot melt adhesive with a low softening point and easy to form.

[0118] Combining Example 1 with Comparative Examples 4-5 and the data in Table 1, it can be seen that by adding a certain proportion of metallocene ethylene-octene copolymer to the base resin, not only can the bonding strength of the polyolefin hot melt adhesive itself be effectively improved, but also the softening point of the hot melt adhesive can be further reduced, and as the proportion of metallocene ethylene-octene copolymer increases, the bonding strength of the hot melt adhesive is further improved. This may be because compared with APAO resin, metallocene ethylene-octene copolymer can play a role of physical crosslinking through the crystallization of polyethylene segments, and at the same time, it has high static shear viscosity and good melt strength, which is conducive to improving the overall bonding performance and cohesive strength of the hot melt adhesive. At the same time, since the side chains of the metallocene ethylene-octene copolymer's own structure destroy the orderly arrangement of the polyethylene segments and reduce its crystallinity, it has a lower softening point, and can further reduce the softening point of the polyolefin hot melt adhesive after blending in a certain proportion.

[0119] Combining Example 4 with Comparative Examples 6-7 and the data in Table 1, it can be seen that when the tackifying resin is a mixture of petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in a certain proportion, the bonding strength of the hot melt adhesive can be effectively improved. At the same time, as the proportion of petroleum liquid resin decreases and the proportion of C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin increases, the bonding strength of the hot melt adhesive can be further improved, but the softening point will increase slightly.

[0120] Combining Example 7 and Example 8 and the data in Table 1, it can be seen that as the content of the two-block SI in the SIS rubber increases from 30% to 35%, the bonding strength of the hot melt adhesive is further improved. This may be because in the hot melt adhesive formulas of Example 7 and Example 8, the base resin is APAO resin and metallocene ethylene-octene copolymer, the tackifying resin is a petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin mixed in a certain proportion, and the cohesive strength in the entire hot melt adhesive system is relatively high. At this time, the bonding strength is mainly based on the interfacial adhesion strength, and the two-block SI has good adhesion performance and poor cohesive strength due to the network loss of the molecular structure and the small molecular weight. Therefore, in the hot melt adhesive system of Example 7 and Example 8, as the content of the two-block SI in the SIS rubber is higher, the bonding strength of the obtained hot melt adhesive will increase.

[0121] Combining Example 8 and Example 9 with the data in Table 1, it can be seen that when the content of the two-block SI in the SIS rubber is 35%, as the S / I block ratio in the two-block SI decreases (i.e., the proportion of I increases), the bonding strength of the hot melt adhesive can be further improved, and the softening point can be further reduced. This may be because when the content of the two-block SI remains unchanged, as the S / I block ratio decreases, the proportion of the isoprene block increases relatively, and the isoprene block plays the role of a soft segment in the SIS rubber and has a lower glass transition temperature, so when its proportion increases, the SIS rubber can have good elasticity, viscosity and a lower softening point.

[0122] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A low temperature hot melt adhesive, characterized in that: It includes the following raw materials in parts by weight: Base resin: 45-65 parts; Tackifying resin: 28-44 parts; SIS rubber: 3-6 parts; Wax material: 3-6 parts; Polyisobutylene 1.6-2.5 parts; Maleic anhydride grafted POP: 5-8 parts; Reinforcing filler: 3-4 parts; Antioxidant: 0.5-1 part; The base resin is a mixture of APAO resin and metallocene ethylene-octene copolymer in a weight ratio of 1:(0.6-1), and the softening point of the APAO resin is in the range of 115-126°C; the tackifying resin is a mixture of petroleum liquid resin, C5 hydrogenated petroleum resin and C5 / C9 copolymerized petroleum resin in a weight ratio of 1:(2-5):(4.5-5); the SIS rubber is a SIS rubber containing 25%-35% of two-block SI, and the relative molecular mass of the two-block SI is 50000-60000, and the block ratio of the two-block SI is (11-20):(80-89).

2. A low-temperature hot melt adhesive according to claim 1, characterized in that: The metallocene ethylene-octene copolymer is one of the brands POP GA1900 and POP GA1950.

3. The low-temperature hot melt adhesive according to claim 1, characterized in that: The wax material is a mixture of paraffin wax and Fischer-Tropsch wax, and the mixing weight ratio of the paraffin wax to the Fischer-Tropsch wax is 1:(0.2-0.5).

4. The low-temperature hot melt adhesive according to claim 1, characterized in that: The relative molecular weight of the polyisobutylene is 35000-50000.

5. The low-temperature hot melt adhesive according to claim 1, characterized in that: The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and the mixing weight ratio of the antioxidant 1010 to the antioxidant 168 is 1:(2.33-4).

6. A method for preparing a low-temperature hot melt adhesive, characterized in that: The method for preparing a low-temperature hot melt adhesive according to any one of claims 1 to 5 comprises the following steps: S1. First, 10% of the base resin is fully mixed with the wax material, polyisobutylene, maleic anhydride grafted POP and antioxidant at a mixing temperature of 140-150° C., and then the remaining base resin, SIS rubber and reinforcing filler are added, and the mixture is fully stirred to obtain a first mixture; S2, lowering the mixing temperature to 135-145°C, then adding a tackifying resin, and continuing stirring for 20-30 minutes to obtain a second mixture; S3, vacuum exhaust treatment is performed on the second mixture, and then the second mixture is extruded and quickly pulled into a circulating cooling water tank with a cooling solution temperature of 5° C. for cooling, and then cut into a fixed length to form a hot melt adhesive stick and dry the adhesive stick to obtain a low-temperature hot melt adhesive.

7. The method for preparing a low-temperature hot melt adhesive according to claim 6, characterized in that: The cooling solution includes 10% anti-adhesive solution and 90% deionized water.

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