Polymer prepolymer and preparation method thereof as well as washing type UV (ultraviolet) drop glue and preparation method thereof

Abstract

The invention relates to the field of photocuring materials, in particular to a polymer prepolymer and a preparation method thereof as well as washing type UV (ultraviolet) drop glue and a preparation method thereof. The polymer prepolymer provided by the invention is synthesized through a special polymerization process, and the molecular structure of the polymer prepolymer contains specific hydrophilic groups and cross-linkable groups, so that the solubility of drop glue in water can be ensured, and a stable three-dimensional network structure can be formed in a curing process; the UV crystal drop glue prepared by using the prepolymer can effectively solve the problems that the existing UV crystal drop glue is complicated in operation, poor in curing effect and difficult to clean.

Description

Technical Field

[0001] This invention relates to the field of photocurable materials, and particularly to a polymer prepolymer and its preparation method, as well as a water-washable UV epoxy resin and its preparation method. Background Technology

[0002] UV crystal epoxy resin is a transparent resin material that can be cured by ultraviolet light (such as nail lamps or special UV epoxy resin curing lamps). After curing, it presents a crystal-like transparent texture. UV crystal epoxy resin usually has the following characteristics: (1) Fast curing: No need to wait for a long time. Under the irradiation of ultraviolet light, it can usually harden completely within tens of seconds to minutes; (2) High transparency: After curing, it is clear and transparent, which can preserve the original appearance of the covered item to the greatest extent, and has a high gloss; (3) Strong adhesion: It can adhere tightly to the surface of various materials such as paper, wood, metal, and plastic, and is not easy to fall off.

[0003] The core purpose of UV crystal epoxy resin is to decorate, protect, or shape items, with common applications concentrated in handicrafts and industrial fields. For example, in handicrafts, this is the most common use; applying the resin to the surface of small items such as phone cases, keychains, and hair clips creates a three-dimensional, sparkling effect. It can also be used to embed dried flowers, sequins, photos, etc., to create pendants, ornaments, etc. Another application is surface protection, where it forms a hard protective film on the surface of items to prevent scratches, wear, or moisture damage, such as protecting journal stickers, hand-drawn artwork, and business cards.

[0004] UV crystal epoxy resin is essentially a UV-curable polyurethane acrylate resin, composed of a base resin, photoinitiator, diluent, and other additives. Currently, most UV crystal epoxy resins on the market are oil-based, immiscible with water, and suffer from cumbersome application, poor curing results, and difficulty in cleaning. Summary of the Invention

[0005] In view of this, the present invention provides a polymer prepolymer and its preparation method, as well as a water-washable UV epoxy resin and its preparation method. The polymer prepolymer provided by the present invention can effectively solve the problems of cumbersome operation, poor curing effect, and difficulty in cleaning of existing UV crystal epoxy resins.

[0006] This invention provides a method for preparing a polymer prepolymer, comprising:

[0007] S1. Preparation of unsaturated polyester resin A:

[0008] (S101) Mixing:

[0009] Maleic anhydride, phthalic anhydride, ethylene glycol, 1,2-propanediol, catalyst and polymerization inhibitor are mixed, and a protective gas is introduced into the system for gas replacement.

[0010] (S102) Segmented heating and polycondensation:

[0011] ① Low-temperature esterification stage:

[0012] Heat the system to 75-85℃ to completely dissolve the solid raw materials, then continue to heat to 118-122℃ and hold for 1-1.5 hours to remove the precipitated water.

[0013] ②Mesotemperature polycondensation stage:

[0014] Continue heating the system to 150~165℃ and hold for 2~3 hours. During this period, take samples to test the acid value. When the acid value drops to 80~100mg KOH / g, proceed to the next stage.

[0015] ③ High-temperature refining stage:

[0016] The system was heated to 175-185℃ and held at that temperature. During this period, samples were taken to test the acid value and hydroxyl value. Heating was stopped when the acid value dropped to 30-50 mg KOH / g and the hydroxyl value reached 50-80 mg KOH / g, and unsaturated polyester resin A was obtained.

[0017] S2. Preparation of polymer prepolymer B:

[0018] (S201) Mixing:

[0019] The unsaturated polyester resin A obtained in step S1, the initiator and the chain transfer agent are mixed, and a protective gas is introduced into the system for gas replacement.

[0020] (S202) Heating polymerization:

[0021] Heat the system to 80-90℃ and keep it at that temperature for 3-5 hours. During this period, take samples to detect the molecular weight of the polymer. Stop heating when the molecular weight reaches 5000-15000 Da.

[0022] (S203) Post-processing:

[0023] When the system cools down to 30~50℃, add the polymerization inhibitor to obtain polymer prepolymer B.

[0024] Preferably, in step S1, the amounts of each raw material used, by mass, are as follows:

[0025] Maleic anhydride: 30-40 parts;

[0026] Phthalic anhydride: 20-25 parts;

[0027] Ethylene glycol: 25-30 parts;

[0028] 1,2-Propanediol: 10-15 parts;

[0029] Catalyst: 0.1~0.3 parts;

[0030] Polymerization inhibitor: 0.05~0.1 parts;

[0031] The catalyst is p-toluenesulfonic acid;

[0032] The polymerization inhibitor is hydroquinone.

[0033] Preferably, step (S101) specifically includes:

[0034] ① Raw material pretreatment:

[0035] Maleic anhydride and phthalic anhydride were placed in a vacuum drying oven for vacuum drying and dehydration pretreatment; ethylene glycol and 1,2-propanediol were pretreated by filtration.

[0036] ② Mixing:

[0037] Pretreated maleic anhydride, pretreated phthalic anhydride, pretreated ethylene glycol, and pretreated 1,2-propanediol were added to the flask, followed by the addition of a catalyst and a polymerization inhibitor. A protective gas was then introduced into the flask for gas replacement.

[0038] Preferably, the unsaturated polyester resin A obtained in step S1 has the following specifications: acid value of 30~50mg KOH / g, hydroxyl value of 50~80mg KOH / g, double bond content of 0.015~0.025mol / g, and viscosity at 25℃ of 500~1500mPa.s.

[0039] Preferably, in step S2, the amount of each material used is as follows:

[0040] Unsaturated polyester resin A: 100 parts;

[0041] Initiator: 0.1~1 part;

[0042] Chain transfer agent: 0.1~2.5 parts;

[0043] Polymerization inhibitor: 0.01~1 part;

[0044] The initiator is an azo initiator;

[0045] The chain transfer agent is dodecyl mercaptan;

[0046] The polymerization inhibitor is hydroquinone.

[0047] The present invention also provides a polymer prepolymer, which is prepared by the preparation method described in the above technical solution.

[0048] This invention also provides a water-washable UV epoxy resin, the raw materials for which, by weight, are:

[0049] Resin: 30-60 parts;

[0050] Photoinitiator: 1-5 parts;

[0051] Reactive diluent: 10-30 parts;

[0052] Additives: 0.1~2 parts;

[0053] Special additives: 5-15 parts;

[0054] in:

[0055] The resin is the polymer prepolymer described in the above technical solution;

[0056] The special additive is a water-soluble polymer containing carboxyl and sulfonic acid groups.

[0057] Preferably, the reactive diluent is hydroxyethyl acrylate;

[0058] The photoinitiator is a benzophenone derivative;

[0059] The additives are dispersants, defoamers, and plasticizers;

[0060] The special additive is sodium salt of maleic acid-acrylic acid copolymer.

[0061] The present invention also provides a method for preparing the water-washable UV epoxy resin described in the above technical solution, comprising: mixing resin, photoinitiator, reactive diluent, additives and special additives to obtain water-washable UV epoxy resin.

[0062] Preferably, it includes the following steps:

[0063] K1. Mix the resin, reactive diluent and additives to obtain solution 1;

[0064] K2. Mix the liquid 1 with the photoinitiator to obtain liquid 2;

[0065] K3. Mix the liquid material 2 with special additives to obtain a water-washable UV epoxy resin.

[0066] The polymer prepolymer provided by this invention is a novel polymer prepolymer. This prepolymer is synthesized through a special polymerization process. Its molecular structure contains specific hydrophilic groups and crosslinkable groups, which can ensure the solubility of the epoxy resin in water and form a stable three-dimensional network structure during the curing process. The UV crystal epoxy resin prepared using this prepolymer can effectively solve the problems of cumbersome operation, poor curing effect and difficulty in cleaning of existing UV crystal epoxy resins. Detailed Implementation

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0068] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0069] The term “and / or” as used herein includes any and all combinations of one or more of the related listed items.

[0070] In this document, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0071] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it means that the units for the left and right endpoints are the same. For example, 80~90℃ means that the units for the left endpoint "80" and the right endpoint "90" are both in degrees Celsius.

[0072] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0073] In a first aspect, the present invention provides a method for preparing a polymer prepolymer, comprising:

[0074] S1. Preparation of unsaturated polyester resin A:

[0075] (S101) Mixing:

[0076] Maleic anhydride, phthalic anhydride, ethylene glycol, 1,2-propanediol, catalyst and polymerization inhibitor are mixed, and a protective gas is introduced into the system for gas replacement.

[0077] (S102) Segmented heating and polycondensation:

[0078] ① Low-temperature esterification stage:

[0079] Heat the system to 75-85℃ to completely dissolve the solid raw materials, then continue to heat to 118-122℃ and hold for 1-1.5 hours to remove the precipitated water.

[0080] ②Mesotemperature polycondensation stage:

[0081] Continue heating the system to 150~165℃ and hold for 2~3 hours. During this period, take samples to test the acid value. When the acid value drops to 80~100mg KOH / g, proceed to the next stage.

[0082] ③ High-temperature refining stage:

[0083] The system was heated to 175-185℃ and held at that temperature. During this period, samples were taken to test the acid value and hydroxyl value. Heating was stopped when the acid value dropped to 30-50 mg KOH / g and the hydroxyl value reached 50-80 mg KOH / g, and unsaturated polyester resin A was obtained.

[0084] S2. Preparation of polymer prepolymer B:

[0085] (S201) Mixing:

[0086] The unsaturated polyester resin A obtained in step S1, the initiator and the chain transfer agent are mixed, and a protective gas is introduced into the system for gas replacement.

[0087] (S202) Heating polymerization:

[0088] Heat the system to 80-90℃ and keep it at that temperature for 3-5 hours. During this period, take samples to detect the molecular weight of the polymer. Stop heating when the molecular weight reaches 5000-15000 Da.

[0089] (S203) Post-processing:

[0090] When the system cools down to 30~50℃, add the polymerization inhibitor to obtain polymer prepolymer B.

[0091] Regarding step S1 :

[0092] According to the present invention, step S1 is to prepare unsaturated polyester resin A, including: (S101)~(S102).

[0093] [Regarding step (S101)]:

[0094] (S101) Mixing: Mix maleic anhydride, phthalic anhydride, ethylene glycol, 1,2-propanediol, catalyst and polymerization inhibitor, and introduce protective gas into the system for gas replacement.

[0095] In this invention, in step S1, the amounts of each raw material used, by weight, are as follows:

[0096] Maleic anhydride: 30-40 parts;

[0097] Phthalic anhydride: 20-25 parts;

[0098] Ethylene glycol: 25-30 parts;

[0099] 1,2-Propanediol: 10-15 parts;

[0100] Catalyst: 0.1~0.3 parts;

[0101] Polymerization inhibitor: 0.05~0.1 parts.

[0102] The purity of the maleic anhydride is preferably ≥99%. The maleic anhydride is preferably maleic anhydride with a melting point of 52-54℃, specifically 52℃, 53℃, or 54℃. The amount of maleic anhydride used is 30-40 parts, specifically 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 parts.

[0103] The purity of the phthalic anhydride is preferably ≥99%. The phthalic anhydride is preferably a phthalic anhydride with a melting point of 131℃. The amount of phthalic anhydride used is 20-25 parts, specifically 20, 21, 22, 23, 24, or 25 parts.

[0104] The purity of the ethylene glycol is preferably ≥99.5%. The boiling point of the ethylene glycol is 197.3℃. The amount of ethylene glycol used is 25~30 parts, specifically 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, or 30 parts.

[0105] The purity of the 1,2-propanediol is preferably ≥99%. The boiling point of the 1,2-propanediol is 188.2℃. The amount of the 1,2-propanediol used is 10~15 parts, specifically 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, or 15 parts.

[0106] The catalyst is preferably p-toluenesulfonic acid. The purity of the catalyst is preferably ≥98%. The amount of the catalyst used is 0.1~0.3 parts, specifically 0.1 parts, 0.2 parts, or 0.3 parts.

[0107] The polymerization inhibitor is preferably hydroquinone. The purity of the polymerization inhibitor is preferably ≥99%. The amount of the polymerization inhibitor is 0.05~0.1 parts, specifically 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, or 0.1 parts.

[0108] In this invention, preferably, step (S101) specifically includes:

[0109] ① Raw material pretreatment:

[0110] Maleic anhydride and phthalic anhydride were placed in a vacuum drying oven for vacuum drying and dehydration pretreatment; ethylene glycol and 1,2-propanediol were pretreated by filtration.

[0111] ② Mixing:

[0112] Pretreated maleic anhydride, pretreated phthalic anhydride, pretreated ethylene glycol, and pretreated 1,2-propanediol were added to the flask, followed by the addition of a catalyst and a polymerization inhibitor. A protective gas was then introduced into the flask for gas replacement.

[0113] Regarding step ①: The preferred temperature for vacuum drying and dehydration is 40~80℃, more preferably 60℃. The preferred time for vacuum drying is 1~4h, more preferably 2h. The preferred vacuum degree for vacuum drying is -0.06~-0.095MPa, more preferably -0.08MPa. Maleic anhydride and phthalic anhydride can be pretreated separately or together in a vacuum drying oven. When pretreated separately, the pretreatment conditions for both are independently selected from the above-mentioned parameters; that is, the pretreatment conditions for both can be the same or different. In this invention, filtration is preferably performed through a 0.20~0.25μm filter membrane, more preferably 0.22μm. The filter membrane is preferably an organic filter membrane.

[0114] Regarding step ②: The flask is preferably a four-necked flask; more preferably, it is a four-necked flask equipped with a stirrer, thermometer, reflux condenser (connected to a water separator at the top), and protective gas inlet tube. In this invention, the type of protective gas is not particularly limited; any conventional protective gas in the art is acceptable, such as nitrogen or argon, with nitrogen being preferred. In this invention, the purity of the protective gas is preferably ≥99.99%. The flow rate of the protective gas is preferably 30~80 mL / min, more preferably 50 mL / min. The introduction time of the protective gas is preferably 5~30 min, more preferably 15 min.

[0115] [Regarding step (S102)]:

[0116] In this invention, step (S102) involves segmented heating polycondensation, including: ① low-temperature esterification stage → ② medium-temperature polycondensation stage → ③ high-temperature refining stage.

[0117] ① Low-temperature esterification stage: Heat the system to 75~85℃ to completely dissolve the solid raw materials, then continue to heat to 118~122℃ and keep it at that temperature for 1~1.5h to remove the precipitated water.

[0118] The heating rate is preferably 3-6°C / min, more preferably 5°C / min. The system is first heated to 75-85°C, more preferably 80°C. Upon reaching this temperature, stirring is performed at a rate preferably 150-250 r / min, more preferably 200 r / min. Heating continues until the solid raw material is completely dissolved. The rate of this continued heating is preferably 3-6°C / min, more preferably 5°C / min. The target temperature for this continued heating is 118-122°C, more preferably 120°C. After reaching the target temperature, the temperature is maintained. The maintenance time is preferably 1-1.5 h, more preferably 1 h. During the maintenance reaction, the precipitated water is discharged, specifically the water precipitated in the water separator. The precipitated water is 20% of the theoretical water production.

[0119] ②Medium-temperature polycondensation stage: Continue to heat the system to 150~165℃ and keep it at that temperature for 2~3 hours. During this period, take samples to test the acid value. When the acid value drops to 80~100mg KOH / g, proceed to the next stage.

[0120] The rate of further heating is preferably 3-6 °C / min, more preferably 3 °C / min. The target temperature for further heating is 150-165 °C, more preferably 160 °C. After reaching the above temperature, the stirring rate is preferably increased to 280-330 r / min, more preferably 300 r / min. Furthermore, the reaction is maintained at this temperature for 2-3 hours, during which the acid value is sampled and tested. When the acid value drops to 80-100 mg KOH / g, the next stage begins. The sampling frequency can be once every 30 minutes.

[0121] ③ High-temperature refining stage: The system is heated to 175~185℃ and kept at that temperature. During this period, samples are taken to test the acid value and hydroxyl value. When the acid value drops to 30~50mg KOH / g and the hydroxyl value reaches 50~80mg KOH / g, heating is stopped to obtain unsaturated polyester resin A.

[0122] The rate of continued heating is preferably 1~3℃ / min, more preferably 2℃ / min. The target temperature for continued heating is 175~185℃, more preferably 180℃. After reaching the above temperature, the system is held at this temperature while being stirred; the stirring rate is preferably 280~330 r / min, more preferably 300 r / min. During the holding period, if the system viscosity is too high, a solvent is added; the solvent is preferably xylene; the purity of the solvent is preferably ≥99%; if the system viscosity is suitable, the solvent does not need to be added. Based on a maleic anhydride dosage of 30~40 parts, the solvent dosage is preferably 5~10 parts, specifically 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts. During the holding period, samples are taken to test the acid value and hydroxyl value. Heating is stopped when the acid value drops to 30~50 mg KOH / g and the hydroxyl value reaches 50~80 mg KOH / g.

[0123] After heating is stopped, post-processing is preferably performed. The post-processing includes cooling and filtration. Preferably, the cooling is natural cooling; more preferably, the temperature is reduced to 90-105°C, and more preferably to 100°C. After cooling, a diluent can be added according to the required resin viscosity. If no viscosity reduction is needed, no diluent is added; if viscosity reduction is required, it is added. The diluent is preferably styrene. The amount of diluent added is preferably 20%-30% of the resin mass, specifically 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%. The resin is the product obtained from the system reaction, i.e., the material after cooling. Filtration is preferably performed using a 1-2 μm filter membrane, more preferably a 1 μm filter membrane. After filtration, the obtained product is placed in brown sealed bottles and stored at room temperature (preferably 25°C) away from light for later use.

[0124] In this invention, the sum of the amounts of all materials (except the diluent) used in step S1 is preferably 100 parts by mass.

[0125] In this invention, the unsaturated polyester resin A obtained in step S1 has the following specifications: acid value of 30~50mg KOH / g, hydroxyl value of 50~80mg KOH / g, double bond content of 0.015~0.025mol / g, and viscosity at 25℃ of 500~1500mPa.s.

[0126] In step S1 of this invention, unsaturated dicarboxylic acid (maleic anhydride), saturated dicarboxylic acid (phthalic anhydride), main hydroxyl source diol (ethylene glycol), and auxiliary regulating diol (1,2-propanediol) are used as main raw materials to carry out segmented heating polycondensation to obtain unsaturated polyester resin A containing hydroxyl (-OH) and double bond (C=C).

[0127] Regarding step S2 :

[0128] According to the present invention, step S2 is to prepare polymer prepolymer B, including: (S201)~(S203).

[0129] [Regarding step (S201)]:

[0130] (S201) Mixing: Mix the unsaturated polyester resin A obtained in step S1, the initiator and the chain transfer agent, and introduce a protective gas into the system for gas replacement.

[0131] In this invention, the initiator is preferably an azo initiator, more preferably azobisisobutyronitrile (AIBN). The purity of the initiator is preferably ≥98%.

[0132] In this invention, the chain transfer agent is preferably dodecyl mercaptan. The purity of the chain transfer agent is preferably ≥95%.

[0133] In this invention, preferably, step (S201) specifically includes:

[0134] ① Raw material pretreatment:

[0135] The unsaturated polyester resin A, initiator and chain transfer agent obtained in step S1 are placed in a dry container and allowed to stand for pretreatment.

[0136] ② Mixing:

[0137] Pretreated unsaturated polyester resin A, pretreated initiator, and pretreated chain transfer agent are added to the flask, and a protective gas is introduced into the flask for gas replacement.

[0138] Regarding step ①: The preferred temperature for the settling period is 20~30℃, more preferably 25℃. The preferred settling time is 20~40min, more preferably 30min. After the above settling pretreatment, the material is fully degassed, and pretreated unsaturated polyester resin A, pretreated initiator, and pretreated chain transfer agent are obtained respectively.

[0139] Regarding step ②: The flask is preferably a three-necked flask. After adding the materials, stirring is performed; the stirring rate is preferably 280~330 r / min, more preferably 300 r / min; stirring continues until the raw materials are completely dissolved. Then, a protective gas is introduced into the system. In this invention, the type of protective gas is not particularly limited, and any conventional protective gas in the art is acceptable, such as nitrogen or argon, etc., with nitrogen being preferred in this invention. In this invention, the purity of the protective gas is preferably ≥99.99%. The flow rate of the protective gas is preferably 80~120 mL / min, more preferably 100 mL / min. The introduction time of the protective gas is preferably 20~40 min, more preferably 30 min.

[0140] [Regarding step (S202)]:

[0141] (S202) Heating polymerization: Heat the system to 80~90℃ and keep it at that temperature for 3~5 hours; take samples during the reaction to detect the molecular weight of the polymer, and stop heating when the molecular weight reaches 5000~15000 Da.

[0142] In this invention, the heating rate is preferably 3-6°C / min, more preferably 5°C / min. The target temperature is 80-90°C, specifically 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C. After reaching the target temperature, a heat preservation reaction is carried out for 3-5 hours, specifically 3 hours, 4 hours, or 5 hours. During the heat preservation reaction, samples are taken to detect the polymer molecular weight, and heating is stopped when the molecular weight reaches 5000-15000 Da. The sampling frequency is preferably once per hour. The molecular weight is preferably detected by gel permeation chromatography (GPC).

[0143] [Regarding step (S203)]:

[0144] (S203) Post-treatment: When the system is cooled to 30~50℃, add the polymerization inhibitor to obtain polymer prepolymer B.

[0145] In this invention, after step (S202), the system is cooled. To avoid system inhomogeneity, the cooling rate is preferably 5~20℃ / min, more preferably 10℃ / min. The cooling temperature is reduced to 30~50℃, more preferably 40℃. After cooling to the above temperature, a polymerization inhibitor is added to inhibit the polymerization reaction. The polymerization inhibitor is preferably hydroquinone; the purity of the polymerization inhibitor is preferably ≥99%. After adding the polymerization inhibitor, the mixture is stirred continuously for a period of time; the stirring rate is preferably 150~250 r / min, more preferably 200 r / min; the stirring time is preferably 5~20 min, more preferably 10 min. After the above treatment, polymer prepolymer B, i.e., a novel polymer prepolymer, is obtained. The obtained product is sealed and stored in a brown bottle at room temperature (preferably 25℃) away from light for later use. The storage period is ≤3 months to prevent functional group deactivation.

[0146] In this invention, the amounts of each material used in step S2, by mass, are as follows:

[0147] Unsaturated polyester resin A: 100 parts;

[0148] Initiator: 0.1~1 part; preferably 0.5 part;

[0149] Chain transfer agent: 0.1~2.5 parts; preferably 2 parts;

[0150] Polymerization inhibitor: 0.01~1 part; preferably 0.1 part.

[0151] In this article, "A" and "B" in unsaturated polyester resin A and polymer prepolymer B have no special meaning or limitation; they are only used to label the products obtained in different steps.

[0152] The polymer prepolymer B obtained by this invention contains specific hydrophilic groups and crosslinkable groups, which can ensure the solubility of the droplets in water and form a stable three-dimensional network structure during the curing process.

[0153] Secondly, the present invention also provides a polymer prepolymer prepared by the preparation method described in the above technical solution.

[0154] Thirdly, the present invention also provides a water-washable UV epoxy resin, the raw materials for which, by weight, are:

[0155] Resin: 30-60 parts;

[0156] Photoinitiator: 1-5 parts;

[0157] Reactive diluent: 10-30 parts;

[0158] Additives: 0.1~2 parts;

[0159] Special additives: 5-15 parts;

[0160] in:

[0161] The resin is the polymer prepolymer described in the above technical solution;

[0162] The special additive is a water-soluble polymer containing carboxyl and sulfonic acid groups.

[0163] In this invention, the resin is the polymer prepolymer (i.e., polymer prepolymer B) described in the above technical solution, which will not be repeated here. The hydrophilic group in the above polymer prepolymer is a hydroxyl group, and the crosslinkable group is a double bond. During the curing process, it can form a stable three-dimensional network structure and ensure the swelling and decomposition properties of the droplet in water. In this invention, the amount of the resin is 30-60 parts, specifically 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, or 60 parts.

[0164] In this invention, the photoinitiator is preferably a benzophenone derivative, more preferably at least one of photoinitiator BP, photoinitiator MBP, photoinitiator MK, and photoinitiator DEABP. The above photoinitiators respond to visible light at a wavelength of 400-450 nm, and under illumination at this wavelength, they can generate free radicals, initiating a crosslinking reaction between the novel polymer prepolymer and the reactive diluent. In this invention, the amount of the photoinitiator is 1-5 parts, specifically 1 part, 2 parts, 3 parts, 4 parts, or 5 parts.

[0165] In this invention, the reactive diluent is preferably hydroxyethyl acrylate. The purity of the hydroxyethyl acrylate is ≥98%; the viscosity of the hydroxyethyl acrylate at 25°C is 5~15 mPa·s. Using the above-mentioned reactive diluent can reduce the viscosity of the dispensing system and participate in the copolymerization reaction. In this invention, the amount of the reactive diluent is 10~30 parts, specifically 10 parts, 15 parts, 20 parts, 25 parts, or 30 parts.

[0166] In this invention, the additives are preferably dispersants, defoamers, and plasticizers. The dispersant is preferably a fatty acid ester dispersant, more preferably at least one selected from stearic acid, palmitic acid, lauric acid, oleic acid, and linolenic acid. The defoamer is preferably an organosilicon defoamer, more preferably at least one selected from dimethyl silicone oil, diethyl silicone oil, and methylphenyl silicone oil. The plasticizer is preferably dibutyl phthalate. In this invention, the preferred mass ratio of the dispersant, defoamer, and plasticizer is (0.05~0.5):(0.03~0.3):(0.02~1.2). In this invention, the total amount of the additives is 0.1~2 parts, specifically 0.1 parts, 0.5 parts, 1 part, 1.5 parts, or 2 parts.

[0167] In this invention, the special additive is a water-soluble polymer containing carboxyl and sulfonic acid groups, preferably sodium salt of maleic acid-acrylic acid copolymer, which can be derived from Changzhou Kylin Chemical (KylinCP-5). The water solubility of the above-mentioned special additive is ≥30g / 100mL (25℃), and it can form a hydrophilic microstructure after the dispensing is cured, allowing the cured colloid to completely swell and decompose after soaking in water at 25℃ for 2-5 hours. In this invention, the amount of the special additive is 5-15 parts, specifically 5 parts, 10 parts, or 15 parts. Fourthly, this invention also provides a method for preparing the water-washable UV dispensing described in the above technical solution, comprising: mixing resin, photoinitiator, reactive diluent, additives, and special additive to obtain the water-washable UV dispensing.

[0168] In this invention, preferably, the preparation method includes the following steps:

[0169] K1. Mix the resin, reactive diluent and additives to obtain solution 1;

[0170] K2. Mix the liquid 1 with the photoinitiator to obtain liquid 2;

[0171] K3. Mix the liquid material 2 with special additives to obtain a water-washable UV epoxy resin.

[0172] Regarding step K1: The preferred mixing temperature is 40~60℃, specifically 40℃, 45℃, 50℃, 55℃, or 60℃. Setting the temperature at these levels and controlling the temperature fluctuation within ±2℃ during mixing ensures stable viscosity of each component during mixing and prevents premature cross-linking of the prepolymer due to localized overheating. The mixing is preferably stirring; the preferred stirring rate is 1000~1500 r / min, specifically 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, or 1500 r / min. The preferred stirring time is 1~2 hours, specifically 1 hour, 1.5 hours, or 2 hours.

[0173] Regarding step K2: The preferred method of adding the material is to add a photoinitiator to the liquid 1. The addition rate is preferably 0.5 to 1 part / 10 min to prevent local aggregation of the photoinitiator from affecting the uniformity of dispersion. The preferred mixing temperature is 40 to 60°C, specifically 40°C, 45°C, 50°C, 55°C, or 60°C. The mixing is preferably stirring; the preferred stirring rate is 1000 to 1500 r / min, specifically 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, or 1500 r / min. The preferred stirring time is 30 to 60 min, specifically 30 min, 40 min, 50 min, or 60 min.

[0174] Regarding step K3: The preferred mixing temperature is 40~60℃, specifically 40℃, 45℃, 50℃, 55℃, or 60℃. The mixing is preferably stirring; the preferred stirring speed is 800~1200 r / min, specifically 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, or 1200 r / min. Controlling the stirring speed at this level avoids introducing excessive air bubbles through high-speed stirring while ensuring the special additives are fully integrated into the system. The preferred stirring time is 45~90 min, specifically 45 min, 50 min, 60 min, 70 min, 80 min, or 90 min. After the above treatment, a water-washable UV epoxy resin is obtained. The finished product is transferred to a light-proof, sealed container and stored at room temperature (preferably 25℃) to prevent premature curing.

[0175] The water-washable UV epoxy resin provided by this invention has the following advantages:

[0176] (1) Easy to operate: The water-washable UV epoxy resin of this invention is a single component, which does not require the complicated A and B glue mixing operation of traditional epoxy resin epoxy resin, greatly saving time and labor costs and improving production efficiency.

[0177] (2) Excellent curing effect: It can be rapidly cured under low-energy visible light irradiation, forming a colloid with high transparency, a light transmittance of over 95%, and a uniform internal structure without cracks or fogging. The colloid has excellent physical properties such as hardness, flexibility, and abrasion resistance, which can meet the needs of different fields. For example, in the production of handicrafts, it can clearly display the details and colors of the handicrafts; in the field of electronic packaging, it can provide good protection for electronic components.

[0178] (3) Easy to clean: When it is necessary to clean the epoxy resin, simply soak the item containing the resin in water. Within a certain period of time (generally 1-24 hours depending on the thickness of the resin and the ambient temperature), the resin will gradually swell and decompose, and can be completely removed by a simple water wash. It will not leave any residue on the surface of the cleaned item, nor will it cause any damage to the item. At the same time, ordinary water is used in the cleaning process, which will not cause environmental pollution and meets environmental protection requirements.

[0179] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0180] Example 1

[0181] 1. Preparation of polymer prepolymer

[0182] S1. Preparation of unsaturated polyester resin A:

[0183] Raw materials: 35 parts maleic anhydride (99% purity, melting point 53℃), 22 parts phthalic anhydride (99% purity, melting point 131℃), 28 parts ethylene glycol (99.5% purity, boiling point 197.3℃), 12 parts 1,2-propanediol (99% purity, boiling point 188.2℃), 0.2 parts p-toluenesulfonic acid catalyst (98% purity), 0.08 parts hydroquinone inhibitor (99% purity), and 8 parts xylene solvent (99% purity, boiling point 138.4℃).

[0184] Preparation process:

[0185] (S101) Mixing:

[0186] ① Raw material pretreatment:

[0187] Maleic anhydride and phthalic anhydride were placed in a vacuum drying oven and dried at 60℃ and -0.08MPa for 2 hours; ethylene glycol and 1,2-propanediol were filtered through a 0.22μm organic phase filter membrane.

[0188] ② Mixing:

[0189] Add pretreated maleic anhydride, pretreated phthalic anhydride, pretreated ethylene glycol, and pretreated 1,2-propanediol to a four-necked flask (1000 mL capacity) equipped with a stirrer, thermometer, reflux condenser (connected to a water separator at the top), and protective gas inlet tube. Then add the catalyst p-toluenesulfonic acid and the polymerization inhibitor hydroquinone. Purge the flask with 99.99% pure nitrogen gas (flow rate 50 mL / min) for 15 min.

[0190] (S102) Segmented heating and polycondensation:

[0191] ① Low-temperature esterification stage:

[0192] The temperature is increased to 80℃ at 5℃ / min, and stirred at 200r / min until the solid raw material is completely dissolved. Then the temperature is increased to 120℃ at 5℃ / min and kept at 1h. The water separated from the water separator (accounting for 20% of the theoretical water production) is discharged.

[0193] ②Mesotemperature polycondensation stage:

[0194] The temperature was increased to 160℃ at 3℃ / min, and the reaction was stirred at 300r / min. During the reaction, the acid value was measured. After 2.5h, the acid value dropped to 90mgKOH / g, and the reaction proceeded to the next stage.

[0195] ③ High-temperature refining stage:

[0196] The temperature was increased to 180℃ at a rate of 2℃ / min, and the reaction was stirred at 300 rpm. During the reaction, samples were taken to test the acid value and hydroxyl value. Xylene was added midway due to the high viscosity of the system. After 1.2 hours of stirring, the acid value was 40 mg KOH / g and the hydroxyl value was 70 mg KOH / g. Heating was then stopped. The mixture was allowed to cool naturally to 100℃, and 28 g of styrene (25% of the resin mass) was added. The mixture was stirred at 200 rpm for 30 minutes. Then, it was filtered through a 1 μm filter membrane to obtain unsaturated polyester resin A, which was stored in a brown bottle at 25℃ protected from light.

[0197] The characteristics of the obtained unsaturated polyester resin A are as follows: acid value 40 mg KOH / g, hydroxyl value 70 mg KOH / g, double bond content 0.02 mol / g, viscosity at 25℃ 1000 mPa.s, and no self-polymerization after 6 months of storage.

[0198] S2. Preparation of polymer prepolymer B:

[0199] Raw materials: 100 parts of unsaturated polymer A, 0.5 parts of initiator AIBN (98% purity), 2 parts of chain transfer agent dodecyl mercaptan (95% purity), and 0.1 parts of polymerization inhibitor hydroquinone (99% purity).

[0200] Preparation process:

[0201] (S201) Mixing:

[0202] ① Raw material pretreatment:

[0203] Place unsaturated polyester resin A, initiator and chain transfer agent in a dry container and let stand at 25°C for 30 minutes.

[0204] ② Mixing:

[0205] Add the pretreated unsaturated polyester resin A, initiator AIBN and chain transfer agent dodecanethiol to a 500mL three-necked flask, and stir at 300r / min for 15min until completely dissolved; then, introduce high-purity nitrogen gas (100mL / min) with a purity of 99.99% for 30min.

[0206] (S202) Heating polymerization:

[0207] Oil bath heating (fluctuation ±1℃) was used to raise the temperature to 85℃ at a rate of 5℃ / min. The reaction was maintained at this temperature, and samples were taken during the reaction to detect the molecular weight of the polymer. GPC analysis showed that the molecular weight was 12000 Da after 4 hours of holding the reaction. Heating was then stopped.

[0208] (S203) Post-processing:

[0209] Cool the mixture to 40°C at 10°C / min, add hydroquinone as a polymerization inhibitor, and stir at 200 r / min for 10 min to obtain polymer prepolymer B. Store in a brown bottle at 25°C in the dark.

[0210] The characteristics of the obtained polymer prepolymer B are: molecular weight 12000 Da, viscosity at 25℃ 800 mPa.s, and no functional group failure after 3 months of storage.

[0211] 2. Preparation of water-washable UV epoxy resin

[0212] (2.1) Raw materials:

[0213] Polymer prepolymer B: 45 parts; Photoinitiator (BP): 3 parts; Reactive diluent (hydroxyethyl acrylate, purity 98%, viscosity 10 mPa.s at 25℃): 20 parts; Additives (dispersant lauric acid 0.3 parts, defoamer dimethyl silicone oil 0.2 parts, plasticizer dibutyl phthalate 0.5 parts): 1 part; Special additive (sodium maleic acid-acrylic acid copolymer, water solubility 35 g / 100 mL at 25℃): 10 parts.

[0214] (2.2) Preparation:

[0215] K1. Add polymer prepolymer B, reactive diluent and additives to the reactor, stir at 45℃ (fluctuation ±2℃) and 1200r / min for 1.5h to obtain liquid 1;

[0216] K2, the reactor is stirred at 1200 r / min, and then the photoinitiator is added at a feeding rate of 0.6 parts / 10 min. Stirring is continued for 45 min to obtain liquid 2;

[0217] K3. Add special additives, adjust the stirring speed to 1000 r / min, and stir for 60 min to obtain a water-washable UV epoxy resin. Cool to 25℃ and transfer to a light-proof, airtight container for storage.

[0218] Example 2

[0219] 1. Preparation of polymer prepolymer

[0220] S1. Preparation of unsaturated polyester resin A:

[0221] Raw materials: 30 parts maleic anhydride (99% purity, melting point 53℃), 20 parts phthalic anhydride (99% purity, melting point 131℃), 25 parts ethylene glycol (99.5% purity, boiling point 197.3℃), 15 parts 1,2-propanediol (99% purity, boiling point 188.2℃), 0.1 parts p-toluenesulfonic acid catalyst (98% purity), 0.05 parts hydroquinone inhibitor (99% purity), and 5 parts xylene solvent (99% purity, boiling point 138.4℃).

[0222] Preparation process:

[0223] (S101) Mixing: Same as in Example 1.

[0224] (S102) Segmented heating and polycondensation:

[0225] ① Low-temperature esterification stage:

[0226] The temperature is increased to 80℃ at 5℃ / min, and stirred at 200r / min until the solid raw material is completely dissolved. Then the temperature is increased to 120℃ at 5℃ / min and kept at 1h. The water separated from the water separator (accounting for 20% of the theoretical water production) is discharged.

[0227] ②Mesotemperature polycondensation stage:

[0228] The temperature was increased to 160℃ at 3℃ / min, and the reaction was stirred at 300r / min. During the reaction, the acid value was measured. After 2 hours of reaction, the acid value dropped to 85mgKOH / g, and the reaction proceeded to the next stage.

[0229] ③ High-temperature refining stage:

[0230] The temperature was increased to 180℃ at a rate of 2℃ / min, and the reaction was stirred at 300 rpm. During the reaction, samples were taken to test the acid value and hydroxyl value. Xylene was added at one point due to the high viscosity of the system. After stirring for 1 hour, the acid value was 35 mg KOH / g and the hydroxyl value was 65 mg KOH / g. Heating was then stopped. The mixture was allowed to cool naturally to 100℃ and filtered through a 1 μm filter membrane to obtain unsaturated polyester resin A. The resin was stored in a brown bottle at 25℃ protected from light.

[0231] The characteristics of the obtained unsaturated polyester resin A are: acid value 35 mg KOH / g, hydroxyl value 65 mg KOH / g, double bond content 0.018 mol / g, and viscosity at 25℃ 1400 mPa.s.

[0232] S2. Preparation of polymer prepolymer B:

[0233] Raw materials: 100 parts of unsaturated polymer A, 0.5 parts of initiator AIBN (98% purity), 2 parts of chain transfer agent dodecyl mercaptan (95% purity), and 0.1 parts of polymerization inhibitor hydroquinone (99% purity).

[0234] Preparation process:

[0235] (S201) Mixing: Same as in Example 1.

[0236] (S202) Heating polymerization:

[0237] Oil bath heating (fluctuation ±1℃) was used to raise the temperature to 80℃ at a rate of 5℃ / min. The reaction was maintained at this temperature, and samples were taken during the reaction to detect the molecular weight of the polymer. GPC analysis showed that the molecular weight was 10000 Da after 5 hours of holding the reaction. Heating was then stopped.

[0238] (S203) Post-processing: Same as in Example 1.

[0239] The characteristics of the obtained polymer prepolymer B are: molecular weight 10000 Da, viscosity at 25℃ 700 mPa·s.

[0240] 2. Preparation of water-washable UV epoxy resin

[0241] (2.1) Raw materials:

[0242] Polymer prepolymer B: 35 parts; Photoinitiator (BP): 2 parts; Reactive diluent (hydroxyethyl acrylate, purity 98%, viscosity 10 mPa.s at 25℃): 15 parts; Additives (dispersant lauric acid 0.2 parts, defoamer dimethyl silicone oil 0.1 parts, plasticizer dibutyl phthalate 0.2 parts): 0.5 parts; Special additive (sodium maleic acid-acrylic acid copolymer, water solubility 35 g / 100 mL at 25℃): 8 parts.

[0243] (2.2) Preparation:

[0244] K1. Add polymer prepolymer B, reactive diluent and additives to the reactor, stir at 40℃ (fluctuation ±2℃) and 1000r / min for 1h to obtain liquid 1;

[0245] K2, the reactor is stirred at 1000 r / min, and then the photoinitiator is added at a feeding rate of 0.5 parts / 10 min. Stirring is continued for 30 min to obtain liquid 2;

[0246] K3. Add special additives, adjust the stirring speed to 800 rpm, and stir for 45 minutes to obtain a water-washable UV epoxy resin. Cool to 25°C and transfer to a light-proof, airtight container for storage.

[0247] Example 3

[0248] 1. Preparation of polymer prepolymer

[0249] S1. Preparation of unsaturated polyester resin A:

[0250] Raw materials: 40 parts maleic anhydride (99% purity, melting point 53℃), 25 parts phthalic anhydride (99% purity, melting point 131℃), 30 parts ethylene glycol (99.5% purity, boiling point 197.3℃), 10 parts 1,2-propanediol (99% purity, boiling point 188.2℃), 0.3 parts p-toluenesulfonic acid catalyst (98% purity), 0.1 parts hydroquinone inhibitor (99% purity), and 10 parts xylene solvent (99% purity, boiling point 138.4℃).

[0251] Preparation process:

[0252] (S101) Mixing: Same as in Example 1.

[0253] (S102) Segmented heating and polycondensation:

[0254] ① Low-temperature esterification stage: Same as in Example 1;

[0255] ②Mesotemperature polycondensation stage:

[0256] The temperature was increased to 160℃ at 3℃ / min, and the reaction was stirred at 300r / min. During the reaction, the acid value was measured. After 3 hours of reaction, the acid value dropped to 100mgKOH / g, and the reaction proceeded to the next stage.

[0257] ③ High-temperature refining stage:

[0258] The temperature was increased to 180℃ at a rate of 2℃ / min, and the reaction was stirred at 300 rpm. During the reaction, samples were taken to test the acid value and hydroxyl value. Xylene was added at one point due to the high viscosity of the system. After stirring for 1.5 hours, the acid value was 50 mg KOH / g and the hydroxyl value was 80 mg KOH / g. Heating was then stopped. The mixture was allowed to cool naturally to 100℃ and filtered through a 1 μm filter membrane to obtain unsaturated polyester resin A. It was stored in a brown bottle at 25℃ protected from light.

[0259] The characteristics of the obtained unsaturated polyester resin A are: acid value 50 mg KOH / g, hydroxyl value 80 mg KOH / g, double bond content 0.025 mol / g, and viscosity at 25℃ 1500 mPa.s.

[0260] S2. Preparation of polymer prepolymer B:

[0261] Raw materials: 100 parts of unsaturated polymer A, 0.5 parts of initiator AIBN (98% purity), 2 parts of chain transfer agent dodecyl mercaptan (95% purity), and 0.1 parts of polymerization inhibitor hydroquinone (99% purity).

[0262] Preparation process:

[0263] (S201) Mixing: Same as in Example 1.

[0264] (S202) Heating polymerization:

[0265] Oil bath heating (fluctuation ±1℃) was used to raise the temperature to 90℃ at a rate of 5℃ / min. The reaction was maintained at this temperature, and samples were taken during the reaction to detect the molecular weight of the polymer. GPC analysis showed that the molecular weight was 15000 Da after 3 hours of holding the reaction. Heating was then stopped.

[0266] (S203) Post-processing: Same as in Example 1.

[0267] The characteristics of the obtained polymer prepolymer B are: molecular weight 15000 Da, viscosity at 25℃ 900 mPa·s.

[0268] 2. Preparation of water-washable UV epoxy resin

[0269] (2.1) Raw materials:

[0270] Polymer prepolymer B: 60 parts; Photoinitiator (BP): 5 parts; Reactive diluent (hydroxyethyl acrylate, purity 98%, viscosity 10 mPa.s at 25℃): 30 parts; Additives (dispersant lauric acid 0.5 parts, defoamer dimethyl silicone oil 0.3 parts, plasticizer dibutyl phthalate 1.2 parts): 2 parts; Special additive (sodium maleic acid-acrylic acid copolymer, water solubility 35 g / 100 mL at 25℃): 15 parts.

[0271] (2.2) Preparation:

[0272] K1. Add polymer prepolymer B, reactive diluent and additives to the reactor, stir at 60℃ (fluctuation ±2℃) and 1500r / min for 2h to obtain liquid 1;

[0273] K2, the reactor is stirred at 1500 r / min, and then the photoinitiator is added at a feeding rate of 1 part / 10 min. Stirring is continued for 60 min to obtain liquid 2;

[0274] K3. Add special additives, adjust the stirring speed to 1200 r / min, and stir for 90 min to obtain a water-washable UV epoxy resin. Cool to 25℃ and transfer to a light-proof, airtight container for storage.

[0275] Comparative Example

[0276] Traditional epoxy resin epoxy resin, model ZDS-1608A3ab, is sourced from Zhengdasheng Chemical.

[0277] Comparative Example 2

[0278] The procedure was carried out according to Example 2, except that maleic anhydride in step S1 was replaced with another unsaturated dicarboxylic acid - itaconic acid, and phthalic anhydride was replaced with another saturated dicarboxylic acid - adipic acid.

[0279] Comparative Example 3

[0280] The procedure was carried out according to Example 2, except that the ethylene glycol in step S1 was replaced with 1,2-propanediol (i.e., all diols were single 1,2-propanediol).

[0281] Comparative Example 4

[0282] The procedure was carried out according to Example 2, except that 1,2-propanediol in step S1 was replaced with ethylene glycol (i.e., all diols were made of a single type of ethylene glycol).

[0283] Comparative Example 5

[0284] The process was carried out according to Example 2, except that in step S1, the high-temperature refining stage was stopped when the acid value reached 20 mg KOH / g and the hydroxyl value reached 40 mg KOH / g; the characteristics of the resulting unsaturated polyester resin A were: acid value 20 mg KOH / g and hydroxyl value 40 mg KOH / g.

[0285] Comparative Example 6

[0286] The process was carried out according to Example 2, except that in step S1, the high-temperature refining stage was stopped when the acid value reached 60 mg KOH / g and the hydroxyl value reached 90 mg KOH / g; the characteristics of the resulting unsaturated polyester resin A were: acid value 60 mg KOH / g and hydroxyl value 90 mg KOH / g.

[0287] Product Testing :

[0288] (1) Washability test:

[0289] The epoxy resins of each embodiment and comparative example were coated onto glass substrates and cured according to their respective curing conditions (e.g., the embodiments of the present invention and other comparative examples were irradiated with 500 lux visible light for 2 minutes, and the conventional adhesive of Comparative Example 1 was cured according to the instructions). Ten sets of parallel samples were prepared (three replicates per set). The average value was taken as the measurement result.

[0290] Water washing test:

[0291] Room temperature water group: Immerse the sample completely in 25℃ distilled water and record the time when the colloid begins to swell and the time when it completely detaches from the substrate (as long as there is no visible residue).

[0292] Warm water acceleration group: tested the removal efficiency under 40℃ warm water conditions (simulating possible heating and cleaning scenarios in actual use).

[0293] Residue detection: After washing with water, observe the substrate surface with an optical microscope (50-100x magnification) to confirm that there is no colloidal residue; for precision substrates such as electronic components, the surface conductivity can be tested with a resistance meter to check whether it is affected (to rule out residual corrosion).

[0294] The test results are shown in Table 1.

[0295] Table 1: Test Results of Washability

[0296]

[0297] (2) Curing effect test:

[0298] Rapid curing: Using a UV-Vis spectrophotometer or irradiometer to control the light source intensity (400 lux visible light), record the time it takes for the dispensing to cure completely (no stickiness when lightly touched with a glass rod).

[0299] Transmittance test: The cured colloid was made into a 1mm thick sheet and the transmittance was tested using a UV-Vis spectrophotometer (550nm wavelength).

[0300] Visual inspection: Check the surface of the cured colloid for bubbles and cracks with the naked eye.

[0301] The test results are shown in Table 2.

[0302] Table 2: Curing effect

[0303]

[0304] (3) Physical performance testing:

[0305] Hardness test: The hardness of the colloid is tested using a Shore hardness tester (Type D, for hard plastics).

[0306] Flexibility test: The cured colloid coated on a flexible substrate (PET film) is repeatedly bent (180° bend, 100 cycles) and observed for cracking.

[0307] Abrasion resistance test: The Taber abrasion tester (load 500g, grinding wheel CS-10) was used to test and record the weight loss rate of the colloid after 1000 friction cycles (the lower the weight loss, the better the abrasion resistance).

[0308] The test results are shown in Table 3.

[0309] Table 3: Physical Performance Test Results

[0310]

[0311] As can be seen from the above performance tests, the water-washable UV epoxy resin obtained in Examples 1-3 of this invention has high light transmittance, toughness, and is washable, perfectly solving the problems of cumbersome operation, poor curing effect, and difficulty in cleaning of existing UV crystal epoxy resins.

[0312] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a polymer prepolymer, characterized in that, include: S1. Preparation of unsaturated polyester resin A: (S101) Mixing: Maleic anhydride, phthalic anhydride, ethylene glycol, 1,2-propanediol, catalyst and polymerization inhibitor are mixed, and a protective gas is introduced into the system for gas replacement. (S102) Segmented heating and polycondensation: ① Low-temperature esterification stage: Heat the system to 75-85℃ to completely dissolve the solid raw materials, then continue to heat to 118-122℃ and hold for 1-1.5 hours to remove the precipitated water. ②Mesotemperature polycondensation stage: Continue heating the system to 150~165℃ and hold for 2~3 hours. During this period, take samples to test the acid value. When the acid value drops to 80~100mgKOH / g, proceed to the next stage. ③ High-temperature refining stage: The system was heated to 175-185℃ and held at that temperature. During this period, samples were taken to test the acid value and hydroxyl value. Heating was stopped when the acid value dropped to 30-50 mg KOH / g and the hydroxyl value reached 50-80 mg KOH / g, and unsaturated polyester resin A was obtained. S2. Preparation of polymer prepolymer B: (S201) Mixing: The unsaturated polyester resin A obtained in step S1, the initiator and the chain transfer agent are mixed, and a protective gas is introduced into the system for gas replacement. (S202) Heating polymerization: Heat the system to 80-90℃ and keep it at that temperature for 3-5 hours. During this period, take samples to detect the molecular weight of the polymer. Stop heating when the molecular weight reaches 5000-15000 Da. (S203) Post-processing: When the system cools down to 30~50℃, add the polymerization inhibitor to obtain polymer prepolymer B.

2. The preparation method according to claim 1, characterized in that, In step S1, the amounts of each raw material used, by mass, are as follows: Maleic anhydride: 30-40 parts; Phthalic anhydride: 20-25 parts; Ethylene glycol: 25-30 parts; 1,2-Propanediol: 10-15 parts; Catalyst: 0.1~0.3 parts; Polymerization inhibitor: 0.05~0.1 parts; The catalyst is p-toluenesulfonic acid; The polymerization inhibitor is hydroquinone.

3. The preparation method according to claim 1, characterized in that, Step (S101) specifically includes: ① Raw material pretreatment: Maleic anhydride and phthalic anhydride were placed in a vacuum drying oven for vacuum drying and dehydration pretreatment; ethylene glycol and 1,2-propanediol were pretreated by filtration. ② Mixing: Pretreated maleic anhydride, pretreated phthalic anhydride, pretreated ethylene glycol, and pretreated 1,2-propanediol were added to the flask, followed by the addition of a catalyst and a polymerization inhibitor. A protective gas was then introduced into the flask for gas replacement.

4. The preparation method according to claim 1, characterized in that, The specifications of the unsaturated polyester resin A obtained in step S1 are as follows: acid value of 30~50mg KOH / g, hydroxyl value of 50~80mg KOH / g, double bond content of 0.015~0.025mol / g, and viscosity at 25℃ of 500~1500mPa.s.

5. The preparation method according to claim 1, characterized in that, In step S2, the amount of each material used is as follows: Unsaturated polyester resin A: 100 parts; Initiator: 0.1~1 part; Chain transfer agent: 0.1~2.5 parts; Polymerization inhibitor: 0.01~1 part; The initiator is an azo initiator; The chain transfer agent is dodecyl mercaptan; The polymerization inhibitor is hydroquinone.

6. A polymer prepolymer, characterized in that, It is prepared by any one of claims 1 to 5.

7. A water-washable UV epoxy resin, characterized in that, The raw materials for its preparation, by mass, include: Resin: 30-60 parts; Photoinitiator: 1-5 parts; Reactive diluent: 10-30 parts; Additives: 0.1~2 parts; Special additives: 5-15 parts; in: The resin is the polymer prepolymer as described in claim 6; The special additive is a water-soluble polymer containing carboxyl and sulfonic acid groups.

8. The water-washable UV epoxy resin according to claim 7, characterized in that, The active diluent is hydroxyethyl acrylate; The photoinitiator is a benzophenone derivative; The additives are dispersants, defoamers, and plasticizers; The special additive is sodium salt of maleic acid-acrylic acid copolymer.

9. A method for preparing a water-washable UV epoxy resin according to any one of claims 7-8, characterized in that, include: The resin, photoinitiator, reactive diluent, additives and special additives are mixed to obtain a water-washable UV epoxy resin.

10. The preparation method according to claim 9, characterized in that, Includes the following steps: K1. Mix the resin, reactive diluent and additives to obtain solution 1; K2. Mix the liquid 1 with the photoinitiator to obtain liquid 2; K3. Mix the liquid material 2 with special additives to obtain a water-washable UV epoxy resin.

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