Viscosity-reducing glue and preparation method thereof

Abstract

The viscosity-reducing adhesive is prepared from the following components in parts by weight: 80 to 100 parts of polyacrylate adhesive, 0.25 to 0.7 part of curing agent, 5 to 10 parts of monomer, 0.8 to 1.0 part of retarder, 2.5 to 5 parts of photoinitiator I, 0.05 to 0.2 part of photoinitiator II and 80 to 100 parts of diluent, the polyacrylate adhesive contains active groups, and the preparation method comprises the following steps: step S1, preparing a curing agent; the preparation method has the advantages that the curing agent contains isocyanate and alkenyl, the density of the alkenyl is relatively large, on one hand, network crosslinking of the polyacrylate adhesive is increased during thermocuring, and on the other hand, the stripping strength of acrylate is rapidly and greatly reduced due to crosslinking of the alkenyl with relatively large density during ultraviolet irradiation; the problem of adhesive residue is improved, energy consumption is reduced, and production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a viscosity-reducing adhesive and a preparation method thereof. Background Art

[0002] In the production process of electronic products, UV adhesive is often used to fix and protect electronic components, such as circuit boards and chips. With the improvement of semiconductor manufacturing level, UV adhesive is more and more widely used in process protection. In order to make the wafer dicing, thinning and packaging process go smoothly, the supporting UV adhesive is also required to be upgraded accordingly.

[0003] At present, VOCs emission control is becoming more and more stringent. Since the main adhesive polyacrylate of the viscosity-reducing adhesive has a large molecular weight, a large amount of solvent is used in the production process to dissolve the curing agent and monomer of the viscosity-reducing adhesive, which reduces the peeling force of the viscosity-reducing adhesive before curing. In addition, the solvent has good fluidity and is easy to volatilize, which not only increases the cost and the danger of the transportation process, but also is not easy to recycle.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In view of the deficiencies in the prior art, the invention discloses a viscosity-reducing adhesive and a preparation method thereof.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A viscosity-reducing adhesive comprises components counted in parts by weight: 80-100 parts of polyacrylate adhesive, 0.25-0.7 parts of curing agent, 5-10 parts of monomer, 0.8-1.0 parts of retarder, 2.5-5 parts of photoinitiator I, 0.05-0.2 parts of photoinitiator II, and 80-100 parts of diluent; the polyacrylate adhesive contains active groups.

[0008] Furthermore, the active groups of the polyacrylate include one or more combinations of carboxyl, hydroxyl and epoxy groups.

[0009] Furthermore, the curing agent is a curing agent containing isocyanate and olefin groups on the molecular chain, which is generated by the reaction of isocyanate, hydroxyethyl methacrylate and pentaerythritol triacrylate.

[0010] Furthermore, the isocyanate includes at least one of toluene diisocyanate, isophordine diisocyanate, hexamethylene diisocyanate, hydrogenated phenylmethane diisocyanate, aliphatic polyisocyanate, and aromatic polyisocyanate based on toluene diisocyanate.

[0011] Furthermore, the monomer is a hydroxyl-containing monomer.

[0012] Furthermore, the monomer containing a hydroxyl group includes at least one of ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and standard epoxy acrylate.

[0013] Furthermore, the photoinitiator I is at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, TMO\1-hydroxycyclohexyl phenyl ketone, and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0014] Furthermore, the photoinitiator II is at least one of a long-chain amine and trimethylolpropane tris(3-mercaptopropionate).

[0015] Furthermore, the retarder includes at least one of acetic acid, phosphoric acid, and acyl chloride; and the diluent includes at least one of ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, and toluene.

[0016] A method for preparing a UV viscosity-reducing adhesive comprises the following steps:

[0017] Step S1, preparing a curing agent:

[0018] The isocyanate, polymerization inhibitor and catalyst are mixed and stirred, wherein the polymerization inhibitor is p-hydroxyanisole and the catalyst is dibutyltin dilaurate. The mixture is slowly heated to 30° C. in a dry container, and pentaerythritol triacrylate is added dropwise to react, and the temperature is kept below 65° C. After the addition is completed, the mixture is kept warm for 2 hours to react until the isocyanate content reaches 6.5-11.0%, and the mixture is set aside.

[0019] Step S2, preparing the viscosity-reducing adhesive:

[0020] Prepare polyacrylate glue, curing agent, monomer, retarder, photoinitiator I, photoinitiator II and diluent in proportion, first add polyacrylate glue into a container, add ethyl acetate to dilute, then add monomer, retarder, photoinitiator I, photoinitiator II and diluent, stir, finally add curing agent, stir, after the reaction is completed, filter the reaction product, and discharge the reaction product to obtain a viscosity-reducing glue.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. Through the cross-linking of curing agent and acrylate, the hydroxyl group on polyacrylate reacts with the isocyanate group in the curing agent to form a dense network cross-linking structure. At the same time, the multi-functional olefin group on the curing agent is connected to the olefin group of the polyacrylate main chain for free radical polymerization to form a network cross-linking structure. The thickness uniformity of the adhesive layer is better and the adhesion of the adhesive layer is more uniform.

[0023] 2. Adding a retarder increases the open time of the glue before coating, improves the leveling of the viscosity-reducing glue, and cooperates with a suitable initiator to reduce oxygen inhibition during the reaction and increase the radiation cross-linking density. After low-energy UVLED irradiation, the peel strength is greatly reduced, which greatly reduces the difficulty of peeling the glue layer after UV irradiation.

[0024] 3. Use a retarder of the appropriate system to improve the stability of the adhesive before thermal curing and extend the open time of the adhesive so that the staff has enough time to carry out construction and coating. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described below.

[0026] Embodiment 1:

[0027] A viscosity-reducing adhesive, specifically a UV viscosity-reducing adhesive, comprises the following components by weight: 100 parts of acrylate adhesive, 0.3 parts of a curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0028] The preparation method of UV viscosity reducing adhesive comprises the following steps:

[0029] Step S1, preparing a curing agent:

[0030] Prepare the raw materials: 100 parts of isophordine diisocyanate, 194 parts of pentaerythritol triacrylate, 0.08 parts of dibutyltin dilaurate, and 0.15 parts of p-hydroxyanisole.

[0031] Add isophordione diisocyanate and p-hydroxyanisole into a stirred, dry container, slowly heat up to 30°C, drop pentaerythritol triacrylate, control the dropping speed to keep the temperature below 65°C. After the addition is complete, keep warm for 2 hours, and test NCO to reach the theoretical value of 6.5%. Put it into a dry nitrogen-filled container, seal it, avoid light, and set aside.

[0032] Step S2, preparing the viscosity-reducing adhesive:

[0033] Prepare the raw materials: 100 parts of acrylate glue, 0.3 parts of curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0034] Add polyacrylate glue into the container, add ethyl acetate to dilute, then add dipentaerythritol hexaacrylate, phosphoric acid, TMO\1-hydroxycyclohexyl phenyl ketone, trimethylolpropane tris(3-mercaptopropionic acid) ester. Stir for 0.5h, and finally add curing agent. Stir for 0.5h, filter, and discharge to obtain viscosity-reducing glue.

[0035] Embodiment 2:

[0036] The curing agent and its preparation process are the same as those in Example 1.

[0037] Step S2, preparing the viscosity-reducing adhesive:

[0038] Prepare the raw materials: 100 parts of acrylate glue, 0.5 parts of curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0039] Add polyacrylate glue into the container, add ethyl acetate to dilute, then add dipentaerythritol hexaacrylate, phosphoric acid, TMO\1-hydroxycyclohexyl phenyl ketone, trimethylolpropane tris(3-mercaptopropionic acid) ester. Stir for 0.5h, and finally add curing agent. Stir for 0.5h, filter, and discharge to obtain viscosity-reducing glue.

[0040] Embodiment 3:

[0041] The curing agent and its preparation process are the same as those in Example 1.

[0042] Step S2, preparing the viscosity-reducing adhesive:

[0043] Prepare the raw materials: 100 parts of acrylate glue, 0.7 parts of curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0044] Add polyacrylate glue into the container, add ethyl acetate to dilute, then add dipentaerythritol hexaacrylate, phosphoric acid, TMO\1-hydroxycyclohexyl phenyl ketone, trimethylolpropane tris(3-mercaptopropionic acid) ester. Stir for 0.5h, and finally add curing agent. Stir for 0.5h, filter, and discharge to obtain viscosity-reducing glue.

[0045] Embodiment 4:

[0046] A viscosity-reducing adhesive comprises the following components by weight: 100 parts of acrylate adhesive, 0.5 parts of curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0047] Step S1, preparing a curing agent:

[0048] Prepare the raw materials: 100 parts of toluene diisocyanate, 247 parts of pentaerythritol triacrylate, 0.1 parts of dibutyltin dilaurate, and 0.17 parts of p-hydroxyanisole.

[0049] Add toluene diisocyanate and p-hydroxyanisole into a stirred, dry container, slowly raise the temperature to 30°C, drop pentaerythritol triacrylate, and control the dropping speed to keep the temperature below 65°C. After the addition is completed, keep warm for 2 hours, and test NCO to reach the theoretical value of 6.8%. Put it into a dry nitrogen-filled container, seal it, protect it from light, and set it aside.

[0050] Step S2, preparing the viscosity-reducing adhesive:

[0051] Prepare the raw materials: 100 parts of acrylate glue, 0.5 parts of curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0052] Add polyacrylate glue into the container, add ethyl acetate to dilute, then add curing agent, dipentaerythritol hexaacrylate, phosphoric acid, TMO\1-hydroxycyclohexyl phenyl ketone, trimethylolpropane tris(3-mercaptopropionic acid) ester. Stir for 0.5h, and finally add curing agent. Stir for 0.5h, filter, and discharge.

[0053] Embodiment 5:

[0054] The difference from Example 1 is that:

[0055] The isocyanate used in the curing agent is toluene diisocyanate.

[0056] Embodiment 6:

[0057] The difference from Example 1 is that:

[0058] The isocyanate used in the curing agent is hexamethylene diisocyanate.

[0059] Embodiment 7:

[0060] The difference from Example 1 is that:

[0061] The isocyanate used in the curing agent is hydrogenated phenylmethane diisocyanate.

[0062] Embodiment 8:

[0063] The difference from Example 1 is that:

[0064] The isocyanate used in the curing agent is an aliphatic polyisocyanate, specifically, polyisocyanate TKA-90SB.

[0065] Embodiment 9:

[0066] The difference from Example 1 is that:

[0067] The isocyanate used in the curing agent is an aliphatic polyisocyanate, specifically, polyisocyanate 22A-75PX.

[0068] Embodiment 10:

[0069] The difference from Example 1 is that:

[0070] The isocyanate used in the curing agent is an aliphatic polyisocyanate, specifically hexamethylene diisocyanate, model Covestro polyisocyanate Desmodur N3390.

[0071] Embodiment 11:

[0072] The difference from Example 1 is that:

[0073] The isocyanate used in the curing agent is an aromatic polyisocyanate based on toluene diisocyanate, specifically Covestro polyisocyanate Desmodur L75.

[0074] Embodiment 12:

[0075] The difference from Example 1 is that:

[0076] The monomer used in the viscosity reducing adhesive is ditrimethylolpropane tetraacrylate.

[0077] Embodiment 13:

[0078] The difference from Example 1 is that:

[0079] The monomers used in the viscosity reducing adhesive are standard epoxy acrylates.

[0080] Embodiment 14:

[0081] The difference from Example 1 is that:

[0082] The photoinitiator I used in the viscosity-reducing adhesive is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0083] Embodiment 15:

[0084] The difference from Example 1 is that:

[0085] The photoinitiator I used in the viscosity-reducing adhesive is phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide.

[0086] Embodiment 16:

[0087] The difference from Example 1 is that:

[0088] The photoinitiator II used in the viscosity-reducing adhesive is a long-chain amine, specifically a polyol acrylate, which includes one or more of ethylene glycol diacrylate, trimethylolpropane triacrylate, and 1,6-hexanediol diacrylate. It is prepared by copolymerization with one or more of ethylamine, diethylamine, propylamine, n-butylamine, N,N'-dimethylethylenediamine, N,N'-dimethyl-1,3-propylenediamine, piperazine, and piperidine after Michael addition, and then with maleic anhydride or maleimide.

[0089] Embodiment 17:

[0090] The difference from Example 1 is that:

[0091] The retarder used in viscosity reducing adhesive is acetic acid.

[0092] Embodiment 18:

[0093] The difference from Example 1 is that:

[0094] The retarder used in viscosity reducing rubber is acyl chloride.

[0095] Embodiment 19:

[0096] The difference from Example 1 is that:

[0097] The diluent used in the viscosity reducing adhesive is ethyl acetate.

[0098] Embodiment 20:

[0099] The difference from Example 1 is that:

[0100] The diluent used in the viscosity reducing adhesive is butyl acetate.

[0101] Embodiment 21:

[0102] The difference from Example 1 is that:

[0103] The diluent used in viscosity reducing adhesive is methyl ethyl ketone.

[0104] Embodiment 22:

[0105] The difference from Example 1 is that:

[0106] The diluent used in the viscosity reducing adhesive is toluene.

[0107] Embodiment 23:

[0108] The difference from Example 1 is that:

[0109] The diluent used in viscosity reducing adhesive is acetone.

[0110] Comparative Example 1:

[0111] The difference from Example 2 is that: an olefin-containing curing agent is used instead of the olefin-containing curing agent in Example 2.

[0112] Viscosity-reducing adhesive raw materials: 100 parts of acrylate adhesive, 0.5 parts of Covestro L75 (aromatic polyisocyanate based on toluene diisocyanate), 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0113] Preparation process: Add polyacrylate glue into the container, add ethyl acetate to dilute, then add dipentaerythritol hexaacrylate, phosphoric acid, TMO\1-hydroxycyclohexyl phenyl ketone, trimethylolpropane tris(3-mercaptopropionic acid) ester. Stir for 0.5h, and finally add the homemade curing agent. Stir for 0.5h, filter, and discharge.

[0114] Comparative Example 2:

[0115] The difference from Example 2 is that the retarder is removed.

[0116] Raw materials for viscosity-reducing adhesive: 100 parts of acrylate adhesive, 0.5 parts of homemade curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0117] Comparative Example 3:

[0118] The difference from Example 2 is that dipentaerythritol hexaacrylate is replaced by tripropylene glycol diacrylate.

[0119] Viscosity-reducing adhesive raw materials: 100 parts of acrylate adhesive, 0.5 parts of curing agent, 5 parts of tripropylene glycol diacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.1 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester, and 100 parts of ethyl acetate.

[0120] Comparative Example 4:

[0121] The difference from Example 2 is that 0.1 part of trimethylolpropane tris(3-mercaptopropionate) is removed.

[0122] Raw materials for viscosity-reducing adhesive: 100 parts of acrylate adhesive, 0.5 parts of homemade curing agent, 5 parts of dipentaerythritol hexaacrylate, 0.8 parts of phosphoric acid, 3 parts of TMO\1-hydroxycyclohexyl phenyl ketone, 0.8 parts of phosphoric acid, and 100 parts of ethyl acetate.

[0123] Comparative experiment:

[0124] The specific test items are as follows:

[0125]

[0126] Test result analysis:

[0127] In Example 1, due to the small amount of curing agent added, the polyacrylate crosslinking is small during thermal curing, which makes the adhesive layer wettable and leads to high initial adhesion. After irradiation, the double bond crosslinking is insufficient, resulting in a small amount of residual adhesive.

[0128] Compared with Example 1, the amount of self-made curing agent used in Example 2 and Example 3 increases successively, and the heat curing crosslinking before irradiation and the double bond crosslinking after irradiation are increased. Therefore, the peel strength on the steel plate and the silicon wafer is lower than that in Example 1, and there is no residual glue.

[0129] The difference between Example 4 and Example 2 is that the isocyanate of the curing agent in Example 2 is replaced by toluene diisocyanate instead of isophordine diisocyanate. Since toluene diisocyanate contains a benzene ring structure, it has a strong rigidity. Therefore, when the dosage is the same, its peel strength is lower than that of Example 2.

[0130] Comparative Example 1 is to replace the self-made alkenyl-containing curing agent of Example 2 with a commercially available common curing agent without alkenyl groups. The curing agent used does not contain alkenyl groups. After thermal curing, there are no radiation-curable alkenyl groups on the polyacrylate macromolecule chain. The polyacrylate macromolecule and the crosslinked product of the alkenyl groups in dipentaerythritol hexaacrylate are entangled together by physical action. As a result, it is difficult to peel off after irradiation and there is residual glue.

[0131] It can be seen from Comparative Example 2 that when there is no retarder, the gel time of the glue is short. The function of the retarder is to increase the stability of the prepared glue before thermal curing and to extend the open time of the glue to facilitate coating construction.

[0132] From Comparative Example 3, it can be seen that when dipentaerythritol hexaacrylate is replaced with tripropylene glycol diacrylate, the density of the olefin group is reduced. Therefore, the crosslinking density is reduced after irradiation, which is manifested in that it is not easy to peel off.

[0133] It can be seen from Comparative Example 4 that it does not contain trimethylolpropane tris(3-mercaptopropionate) and cannot resist oxygen inhibition, so that the peel strength after irradiation is not well reduced and there is a small amount of residual adhesive.

[0134] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A viscosity-reducing adhesive, characterized in that: The composition includes the following components, which are counted by weight: 80-100 parts of polyacrylate glue, 0.25-0.7 parts of curing agent, 5-10 parts of monomer, 0.8-1.0 parts of retarder, 2.5-5 parts of photoinitiator I, 0.05-0.2 parts of photoinitiator II, and 80-100 parts of diluent; The polyacrylate glue contains reactive groups.

2. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The active groups of the polyacrylate include one or more combinations of carboxyl groups, hydroxyl groups and epoxy groups.

3. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The curing agent is a curing agent generated by the reaction of isocyanate, hydroxyethyl methacrylate and pentaerythritol triacrylate, and contains isocyanate and olefin groups on the molecular chain.

4. The UV viscosity-reducing adhesive according to claim 3, characterized in that: The isocyanate includes at least one of toluene diisocyanate, isophordine diisocyanate, hexamethylene diisocyanate, hydrogenated phenylmethane diisocyanate, aliphatic polyisocyanate, and aromatic polyisocyanate based on toluene diisocyanate.

5. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The monomer is a hydroxyl-containing monomer.

6. The UV viscosity-reducing adhesive according to claim 5, characterized in that: The monomer containing a hydroxyl group includes at least one of ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and standard epoxy acrylate.

7. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The photoinitiator I is at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, TMO\1-hydroxycyclohexyl phenyl ketone, and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

8. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The photoinitiator II is at least one of a long-chain amine and trimethylolpropane tris(3-mercaptopropionate).

9. The UV viscosity-reducing adhesive according to claim 1, characterized in that: The retarder includes at least one of acetic acid, phosphoric acid and acyl chloride; the diluent includes at least one of ethyl acetate, butyl acetate, acetone, methyl ethyl ketone and toluene.

10. A method for preparing the UV viscosity-reducing adhesive as claimed in any one of claims 1 to 9, further characterized in that it comprises the following steps: Step S1, preparing a curing agent: The isocyanate, polymerization inhibitor and catalyst are mixed and stirred, wherein the polymerization inhibitor is p-hydroxyanisole and the catalyst is dibutyltin dilaurate. The mixture is slowly heated to 30° C. in a dry container, and pentaerythritol triacrylate is added dropwise to react, and the temperature is kept below 65° C. After the addition is completed, the mixture is kept warm for 2 hours to react until the isocyanate content reaches 6.5-11.0%, and the mixture is set aside. Step S2, preparing the viscosity-reducing adhesive: Prepare polyacrylate glue, curing agent, monomer, retarder, photoinitiator I, photoinitiator II and diluent in proportion, first add polyacrylate glue into a container, add ethyl acetate to dilute, then add monomer, retarder, photoinitiator I, photoinitiator II and diluent, stir, finally add curing agent, stir, after the reaction is completed, filter the reaction product, and discharge the reaction product to obtain a viscosity-reducing glue.

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