PA hot melt adhesive material applied to low-pressure injection molding and preparation method thereof

Abstract

The application provides a PA hot melt adhesive material applied to low-pressure injection molding, which is prepared from the following components: 70-90 parts of low-temperature modified PA resin, 20-30 parts of DOPP viscosity additive, 1-3 parts of nano boron nitride powder, 0.2-1.5 parts of antioxidant and 0.01-0.05 parts of dendritic high-molecular polyamide amine; the low-temperature modified PA resin is obtained by the reaction of dimerized fatty acid, trimerized fatty acid and hexanediamine; a small amount of dendritic high-molecular polyamide amine and nano boron nitride is added to the PA hot melt adhesive material; the PA hot melt adhesive material prepared by the application has a narrow melting point range, excellent low-temperature flexibility, high bonding strength, good elongation and relatively short open time, and can be widely applied to packaging fields such as chips, automobile electronics, 4G / 5G communication and the like.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive materials, and more specifically to a PA hot melt adhesive material for low-pressure injection molding and its preparation method. Background Technology

[0002] Hot melt adhesives are thermoplastic polymers applied to a substrate at a temperature above their softening point, reaching cohesive strength upon cooling. In the molten state, hot melt adhesives must have sufficiently low viscosity to cure and allow wetting of the substrate surface. Polyamides, ethylene-vinyl acetate copolymers, polyesters, polyurethanes, and styrene block copolymers are some common types, widely used in footwear, electronics, textiles, and packaging systems. Polyamide (PA) resin is a hot melt adhesive material produced by the condensation polymerization of dimer fatty acids and amine compounds. It features rapid hot melt curing, strong initial tack, solvent resistance, water resistance, high temperature resistance, and low density, and is widely used in low-pressure injection molding of core electronic and electrical components in industries such as automotive electronics, smart homes, and 4G / 5G communications, as well as in the wood furniture industry. The melting point, low-temperature flexibility, bond strength, and elongation are unavoidable performance factors for hot melt adhesives, and therefore, much research focuses on improving these properties.

[0003] Chinese Patent CN 108048026 A discloses a polyamide hot melt adhesive for injection molding of low surface energy substrates and its preparation method. The raw material composition of the polyamide hot melt adhesive is: 35%-45% aliphatic dimer acid, 5%-20% aliphatic dicarboxylic acid, 40%-55% aliphatic diamine, 5%-40% polyether polyamine, 0.1%-2% antioxidant, 0.01%-0.1% acid catalyst, 0.5%-2% maleic anhydride, and 1.5%-15% EVA resin. This polyamide hot melt adhesive for injection molding of low surface energy substrates exhibits good adhesion to low surface energy injection molding substrates, while also possessing high thermal stability, a high melting point, and good chemical resistance to many compounds, including many common solvents, plasticizers, and oils.

[0004] Chinese Patent CN 113667447 A discloses a polyamide hot melt adhesive, its preparation method, and its application. The raw materials for preparation include the following components: a diacid, a diamine, a catalyst, and thermally conductive seed crystals. The diacid includes a dimer acid and a combination of other diacids. Based on the total mass of the raw materials for preparing the polyamide hot melt adhesive being 100%, the mass percentage of the thermally conductive seed crystals is 1%-2.1%. This polyamide hot melt adhesive exhibits a fast crystallization rate and, in addition to its low viscosity, good wettability, oil resistance, and insulation properties, also possesses the advantage of a fast solidification rate, which can improve the product molding rate and further enhance the production efficiency of the injection molding process.

[0005] Chinese Patent CN 104356998 A discloses a polyamide hot melt adhesive for electronic packaging, prepared by mixing the following components in parts by weight: 45-90 parts of unsaturated fatty acid dimer; 5-20 parts of aliphatic diacid; 15-35 parts of diamine; 0.01-0.05 parts of catalyst; 1-5 parts of polyolefin; 1-5 parts of epoxy resin; 1-5 parts of molecular weight end-capping agent; 0.5-2 parts of antioxidant; and 0.01-0.1 parts of rheology control agent. The polyamide hot melt adhesive provided by this invention exhibits improved low-temperature flexibility and high-temperature creep resistance, excellent low-temperature performance, and is not easily decomposed by heat; it has a high softening point and good fluidity at the high softening point, resulting in uniform application; it has high bonding strength, good adhesion to metals and plastics, and strong adhesion to polar PVC materials; it has moderate hardness and excellent overall performance.

[0006] With the development and rise of my country's chip, automotive electronics, and 4G / 5G communication industries, the demand and requirements for hot melt adhesive materials are also increasing. Summary of the Invention

[0007] Based on the needs and shortcomings of existing technologies, the purpose of this invention is to provide a PA hot melt adhesive material for low-pressure injection molding and its preparation method. The PA hot melt adhesive material prepared by this invention has a narrow melting point range, excellent low-temperature flexibility, high bond strength, good elongation, and a relatively short open time. It can be widely used in packaging fields such as chips, automotive electronics, and 4G / 5G communications.

[0008] To solve the above-mentioned technical problems, this application achieves the following technical solution:

[0009] A PA hot melt adhesive material for low-pressure injection molding is prepared from the following components in parts by weight:

[0010] 70-90 parts of low-temperature modified PA resin

[0011] 20-30 parts of DOPP adhesive additive

[0012] 1-3 parts of nano boron nitride powder

[0013] Antioxidant 0.2-1.5 parts,

[0014] 0.01-0.05 parts of dendritic polyamide amine;

[0015] The preparation steps of the low-temperature modified PA resin are as follows: (1) 100-120 parts of dimer fatty acid, 10-15 parts of trimer fatty acid and 2-5 parts of phosphoric acid are added to the reactor and stirred evenly; (2) when nitrogen gas is introduced and the temperature is heated to 120-140°C, 30-40 parts of piperazine and 90-100 parts of hexamethylenediamine mixture are slowly added; (3) after the addition is completed, the mixture is stirred for 2-4 hours. After the reaction is completed and cooled, the low-temperature modified PA resin is obtained.

[0016] Furthermore, the structural formula of the dimer fatty acid is: The structural formula of the trimeric fatty acid is:

[0017] Where n is between 5 and 8.

[0018] Furthermore, the PA hot melt adhesive material is prepared from the following components in parts by weight:

[0019] 75-85 parts of low-temperature modified PA resin

[0020] 23-27 parts of DOPP adhesive additive

[0021] 1.5-2.5 parts of nano boron nitride powder

[0022] Antioxidant 0.5-1.0 parts,

[0023] 0.03-0.04 parts of dendritic polyamide amine.

[0024] Further, it is one of tris(2,4-di-tert-butylphenyl) phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0025] Furthermore, the molecular weight of the dendritic polymer polyamide amine is 20,000-30,000.

[0026] This application synthesizes PA resin by reacting dimer and trimer fatty acids to obtain low-temperature modified PA resin. The diffusion of molecular chains on the crystal surface reduces the crystallization rate of polyamide and prevents the orderly stacking of molecular chains, thus reducing the degree of crystallinity.

[0027] This application adds a small amount of dendritic polymer polyamide amine to PA hot melt adhesive materials. Dendritic polymers are generally composed of three parts: a dendritic macromolecular core, branched units, and surface groups. They possess a unique three-dimensional molecular configuration and numerous active end groups, exhibiting a highly branched structure with many intramolecular cavities. Simultaneously, utilizing the thermal conductivity of nano-boron nitride, the two are thoroughly and uniformly mixed, filling the cavities with nano-boron nitride. On one hand, this significantly reduces the shrinkage rate of the hot melt adhesive material and improves the compatibility and adhesion strength between boron nitride and the PA matrix. On the other hand, the dendritic structure dispersed within the PA matrix also contributes to improving the relevant mechanical properties of the hot melt adhesive material, particularly increasing tensile strength.

[0028] Furthermore, the PA hot melt adhesive material has a melting point of 192–203°C, low temperature resistance below -40°C, and an open time of less than 15 seconds.

[0029] A method for preparing PA hot melt adhesive material for low-pressure injection molding includes the following steps:

[0030] (1) Weigh out the components in the specified proportions for later use;

[0031] (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1;

[0032] (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

[0033] Furthermore, the set temperature of the twin-screw extruder is as follows: Section 1: 130-140℃, Section 2: 135-145℃, Section 3: 140-160℃, Section 4: 140-160℃, Section 5: 145-155℃, Section 6: 135-145℃, Section 7: 130-150℃, Section 8: 135-155℃, Section 9: 140-150℃, and Die Head: 135-165℃.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) This application optimizes the preparation of low-temperature modified PA resin and the composition of PA hot melt adhesive material to obtain PA hot melt adhesive material with narrow melting point range, excellent low-temperature flexibility, high bonding strength, good elongation, low shrinkage and relatively short open time, which can meet the application of electronic packaging industry and is a low-pressure injection molding hot melt adhesive material.

[0036] (2) This application significantly improves the performance of PA hot melt adhesive materials through the interaction of dendritic polymer polyamide amine and nano boron nitride. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] The dimeric fatty acids and trimeric fatty acids were purchased from Shandong Honghe Chemical Co., Ltd., and the structural formulas of the dimeric fatty acids and trimeric fatty acids are as follows:

[0039] The dendritic polymer polyamide amine was purchased from Weihai Chenyuan Molecular New Materials Co., Ltd., and its brand name is CYD-150A.

[0040] The DOPP adhesive additive was purchased from Shenyang Juwei Technology Co., Ltd.

[0041] Example 1

[0042] The specific steps for preparing low-temperature modified PA resin are as follows: (1) 110 parts of dimer fatty acid, 13 parts of trimer fatty acid and 3 parts of phosphoric acid are added to the reactor and stirred evenly; (2) when nitrogen gas is introduced and heated to 135°C, 36 parts of piperazine and 95 parts of hexamethylenediamine mixture are slowly added; (3) after the addition is completed, the mixture is stirred for 3 hours. After the reaction is completed and cooled, the low-temperature modified PA resin is obtained.

[0043] Unless otherwise specified, the low-temperature modified PA resin in the following examples is the low-temperature modified PA resin prepared in Example 1.

[0044] Example 2

[0045] A PA hot melt adhesive material for low-pressure injection molding is prepared from the following components in parts by weight:

[0046] 70 parts of low-temperature modified PA resin

[0047] 20 parts of DOPP adhesive additive

[0048] 1 part of nano boron nitride powder

[0049] 0.4 parts of tris(2,4-di-tert-butylphenyl) phosphite

[0050] 0.02 parts of dendritic polyamide amine;

[0051] The preparation method of the low-pressure injection molded PA hot melt adhesive material includes the following steps:

[0052] (1) Weigh out the components in the specified proportions for later use;

[0053] (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1;

[0054] (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

[0055] The set temperatures of the twin-screw extruder are as follows: Section 1: 130℃, Section 2: 135℃, Section 3: 140℃, Section 4: 140℃, Section 5: 145℃, Section 6: 135℃, Section 7: 130℃, Section 8: 135℃, Section 9: 140℃, and Die Head: 135℃.

[0056] Example 3

[0057] A PA hot melt adhesive material for low-pressure injection molding is prepared from the following components in parts by weight:

[0058] 90 parts of low-temperature modified PA resin

[0059] 30 parts of DOPP adhesive additive

[0060] 3 parts of nano boron nitride powder

[0061] 1.5 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]

[0062] 0.05 parts of dendritic polymer polyamide amine;

[0063] The preparation method of the low-pressure injection molded PA hot melt adhesive material includes the following steps:

[0064] (1) Weigh out the components in the specified proportions for later use;

[0065] (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1;

[0066] (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

[0067] The set temperatures of the twin-screw extruder are as follows: Section 1: 140℃, Section 2: 145℃, Section 3: 160℃, Section 4: 150℃, Section 5: 155℃, Section 6: 145℃, Section 7: 140℃, Section 8: 155℃, Section 9: 150℃, and Die Head: 165℃.

[0068] Example 4

[0069] A PA hot melt adhesive material for low-pressure injection molding is prepared from the following components in parts by weight:

[0070] 84 parts of low-temperature modified PA resin

[0071] 25 parts of DOPP adhesive additive

[0072] Two parts of nano boron nitride powder

[0073] One part of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]

[0074] 0.04 parts of dendritic polyamide amine;

[0075] The preparation method of the low-pressure injection molded PA hot melt adhesive material includes the following steps:

[0076] (1) Weigh out the components in the specified proportions for later use;

[0077] (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1;

[0078] (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

[0079] The set temperatures of the twin-screw extruder are as follows: Section 1: 135℃, Section 2: 140℃, Section 3: 150℃, Section 4: 150℃, Section 5: 145℃, Section 6: 140℃, Section 7: 150℃, Section 8: 150℃, Section 9: 140℃, and Die Head: 160℃.

[0080] Example 5

[0081] A PA hot melt adhesive material for low-pressure injection molding is prepared from the following components in parts by weight:

[0082] 76 parts of low-temperature modified PA resin

[0083] 24 parts of DOPP adhesive additive

[0084] 1.8 parts of nano boron nitride powder

[0085] One part of the tris(2,4-di-tert-butylphenyl) phosphite,

[0086] 0.03 parts of dendritic polyamide amine;

[0087] The preparation method of the low-pressure injection molded PA hot melt adhesive material includes the following steps:

[0088] (1) Weigh out the components in the specified proportions for later use;

[0089] (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1;

[0090] (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

[0091] The set temperatures of the twin-screw extruder are as follows: Section 1: 130℃, Section 2: 135℃, Section 3: 140℃, Section 4: 160℃, Section 5: 155℃, Section 6: 135℃, Section 7: 140℃, Section 8: 155℃, Section 9: 145℃, and Die Head: 140℃.

[0092] Comparative Example 1

[0093] Comparative Example 1 is basically the same as Example 5, except that the PA resin used is PA66 produced by DuPont.

[0094] Comparative Example 2

[0095] Comparative Example 2 is basically the same as Example 5, except that no dendritic polymer polyamide amine was added.

[0096] The hot melt adhesive materials prepared in Examples 2-5 were subjected to performance tests, specifically including softening point, viscosity, low-temperature resistance, tensile strength, shear strength, and bond strength. The softening point was measured according to standard GB / T 4507-1984; viscosity was measured using a rotational viscometer according to standard GB / T 2794-1995 at a heating temperature of 220℃; low-temperature resistance was tested according to standard ASTM-D746-2004; tensile strength was measured according to standard GB / T528-1998; shear strength was measured according to GB 7124-1986, where the PA hot melt adhesive material was coated onto a clean copper foil surface; and bond strength was tested according to ASTM-D1876-72. Specific test data are recorded in Table 1.

[0097] Table 1

[0098]

[0099]

[0100] According to the test data above, the softening point of the PA hot melt adhesive material prepared by this invention is as high as 190℃ or even reaches 203℃. The low-temperature resistance and shear strength data also indicate excellent low-temperature resistance and bond strength. Furthermore, the open time of the PA hot melt adhesive material is less than 15 seconds, demonstrating good workability.

[0101] Compared to Comparative Example 1, which did not use low-temperature modified PA resin, the softening point and low-temperature resistance of the prepared PA hot melt adhesive material were significantly reduced, and the open time was also prolonged. This indicates that the low-temperature modified PA resin prepared in this application can effectively increase the melting point and improve the low-temperature resistance of the hot melt adhesive material. The open time of a hot melt adhesive is the time from application to when the hot melt adhesive has adhesion to the substrate, and it is one of the important parameters of hot melt adhesive materials. The open time of a hot melt adhesive is generally affected by its own crystallization rate and is also related to the glass transition temperature (Tg) of the hot melt adhesive material.

[0102] In contrast, Comparative Example 2, which did not contain dendritic polyamide amine, produced PA hot melt adhesive materials with softening point, viscosity, and low-temperature resistance that were basically the same as those in this application. However, its tensile strength, shear strength, and elongation at break decreased, although the decrease was not significant. However, its open time was much higher than that in this application. This shows that the addition of dendritic polyamide amine has a significant impact on the performance of PA hot melt adhesive materials.

[0103] While specific embodiments of the present invention have been described in detail, this is not intended to limit the scope of protection of this patent. Various modifications or adjustments that can be made by those skilled in the art without inventive effort within the scope defined by the claims are still protected by this patent.

Claims

1. A PA hot melt adhesive material applied to low pressure injection molding, characterized by, It is prepared from the following components in parts by weight: 70-90 parts of low-temperature modified PA resin, 20-30 parts of DOPP adhesive additive 1-3 parts of nano boron nitride powder Antioxidant 0.2-1.5 parts, 0.01-0.05 parts of dendritic polyamide amine; The preparation steps of the low-temperature modified PA resin are as follows: (1) 100-120 parts of dimer fatty acid, 10-15 parts of trimer fatty acid and 2-5 parts of phosphoric acid are added to the reactor and stirred evenly; (2) when nitrogen gas is introduced and the temperature is heated to 120-140°C, 30-40 parts of piperazine and 90-100 parts of hexamethylenediamine mixture are slowly added; (3) after the addition is completed, the mixture is stirred for 2-4 hours. After the reaction is completed and cooled, the low-temperature modified PA resin is obtained.

2. The PA hot melt adhesive material for low-pressure injection molding according to claim 1, characterized in that, The dimeric fatty acid has a structural formula of: The trimeric fatty acid has a structural formula of: ; wherein n is 5-8.

3. The PA hot melt adhesive material applied to low-pressure injection molding according to claim 1, characterized in that, The PA hot melt adhesive material is prepared from the following components in parts by weight: 75-85 parts of low-temperature modified PA resin 23-27 parts of DOPP adhesive additive 1.5-2.5 parts of nano boron nitride powder Antioxidant 0.5-1.0 parts, 0.03-0.04 parts of dendritic polyamide amine.

4. The PA hot melt adhesive material applied to low-pressure injection molding according to claim 1, characterized in that, The antioxidant is one of tris(2,4-di-tert-butylphenyl) phosphite or pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

5. The PA hot melt adhesive material applied to low-pressure injection molding according to claim 1, characterized in that, The PA hot melt adhesive material has a melting point of 192-203℃, low temperature resistance below -40℃, and an open time of less than 15s.

6. A process for the preparation of a PA hot-melt adhesive material for low-pressure injection moulding according to any one of claims 1 to 5, characterised in that, Includes the following steps: (1) Weigh out the components in the specified proportions for later use; (2) Pour the DOPP adhesive additive, nano boron nitride powder, antioxidant, and dendritic polyamide amine into the mixing equipment according to the weight parts and mix evenly to material group 1; (3) The low-temperature modified PA resin is fed from the main feeder of the twin-screw extruder and the material group 1 is fed from the side feeder of the twin-screw extruder. The materials are melted, mixed and extruded in the twin-screw extruder to obtain the PA hot melt adhesive material for low-pressure injection molding.

7. The method for preparing a PA hot melt adhesive material for low-pressure injection molding according to claim 6, characterized in that, The set temperatures of the twin-screw extruder are as follows: Section 1: 130-140℃, Section 2: 135-145℃, Section 3: 140-160℃, Section 4: 140-160℃, Section 5: 145-155℃, Section 6: 135-145℃, Section 7: 130-150℃, Section 8: 135-155℃, Section 9: 140-150℃, and Die Head: 135-165℃.

Images