A pure cationic system photosensitive resin composition and preparation method thereof

Abstract

The present invention relates to a pure cationic system photosensitive resin composition and a preparation method thereof. The pure cationic system photosensitive resin composition is mainly prepared from the following components in parts by weight: 2 to 5 parts of a cationic photoinitiator, 0.5 to 1.5 parts of a photosensitizer, 20 to 50 parts of an epoxy resin, 10 to 40 parts of a carbonyl compound, and 10 to 40 parts of an olefin compound. In the photosensitive resin, the carbonyl compound and the non-conjugated olefin compound that are not suitable for general SLA photocuring conditions are converted into oxetane compounds suitable for this field through the Paternó-Büchi reaction principle, which greatly expands the range of raw material selection in the SLA photocuring field.

Description

Technical Field

[0001] The present invention belongs to the technical field of photosensitive resin materials for 3D printing, and specifically relates to a pure cationic system photosensitive resin composition and a preparation method thereof. Background Art

[0002] As an emerging additive manufacturing method, SLA light-curing process is a common 3D printing technology with the advantages of high molding accuracy, high degree of automation, and good surface quality. It is widely used.

[0003] At present, the mainstream SLA photocurable materials adopt a dual catalytic system, that is, an epoxy cationic ring-opening polymerization system and an acrylic free radical polymerization system (such as CN109651766A, CN104387755A) are adopted at the same time. The reason for this is that the advantages of fast free radical polymerization and high initial strength are utilized to make up for the slow initial reaction of the epoxy system. However, free radical photoinitiated polymerization also has problems such as oxygen inhibition and large dimensional shrinkage, which limits the application scope of photosensitive resins with dual catalytic systems in the field of SLA photocurable materials.

[0004] At the same time, currently suitable free radical photoinitiator materials are limited to a few conjugated olefin materials such as acrylic acid and vinyl ether, while for most non-conjugated olefin materials, it is difficult to achieve direct free radical photoinitiated polymerization reaction, unless very special means are used, such as using photosensitive acid-generating substances to activate pre-catalysts, generating free radical catalysts under UV, catalyzing ethylene monomers for coordination polymerization (Jordan M. Kaiser, Justin M. Burroughs, and Brian K. Long, JACS 2022, 144, 46, 21206-21212), or some special ternary photoinitiator systems (CN114409872A). Therefore, the source of raw materials for free radical photoinitiator materials is also greatly limited, which further affects the use of photosensitive resins of dual catalytic systems in the field of SLA materials.

[0005] Therefore, it is necessary to develop a pure cationic system of SLA photocurable materials to make up for the shortcomings of the existing dual-catalytic system and broaden the selection range of olefin materials.

[0006] At present, there is a document (CN105384913A) that has developed a pure cationic system photocurable resin. This method uses the strong alkalinity of oxetane monomers to accelerate the cationic reaction and introduces siloxane groups into the epoxy resin to promote the photocuring reaction. However, this method requires the additional synthesis of a more complex structure of siloxane-containing alicyclic epoxy resins, and the implementation process is relatively complicated.

[0007] Therefore, the prior art needs to be improved. Summary of the invention

[0008] The present invention provides a pure cationic system photosensitive resin composition and a preparation method thereof, aiming to solve the technical problem of limited olefin raw materials.

[0009] The present invention is achieved through the following technical solutions:

[0010] Solution 1)

[0011] A pure cationic photosensitive resin composition is mainly prepared from the following components in parts by weight:

[0012] Cationic photoinitiator 2-5 parts

[0013] Photosensitizer 0.5~1.5 parts

[0014] Epoxy resin 20-50 parts

[0015] 10-40 parts of carbonyl compound

[0016] 10 to 40 parts of olefin compound.

[0017] Furthermore, the cationic photoinitiator is one or more of diphenyliodonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, and 4,4'-dimethyldiphenyliodonium hexafluorophosphate in any proportion.

[0018] Furthermore, the photosensitizer is thioxanthone, camphorquinone, bis-2,6-difluoro-3-pyrrolephenyl titanocene (photoinitiator 784), phenyl dichloroacetamide, etc., preferably thioxanthone.

[0019] Furthermore, the epoxy resin is an alicyclic epoxy resin or a non-alicyclic epoxy resin.

[0020] Specifically, the alicyclic epoxy resin is one or more of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, (3,4,3',4'-diepoxy)bicyclohexane, dicyclopentadiene diepoxide, tetrahydroindene diepoxide, and vinylcyclohexene dioxide in any proportion;

[0021] The non-alicyclic epoxy resin is one or more of BPA type epoxy resin, o-cresol type epoxy resin or phenolic type epoxy resin in any proportion.

[0022] Furthermore, the carbonyl compound is one of the compounds of formula 1 or the compounds of formula 2 or a mixture of the two in any proportion.

[0023]

[0024] Wherein, R1, R2, and R3 are organic groups containing 1 to 10 carbon atoms, and R1, R2, and R3 may be the same or different.

[0025] Furthermore, R1, R2, and R3 are alkyl, cycloalkyl, carbonyl, aldehyde, ether bond, cyclic ether, ester or vinyl.

[0026] Specifically, the carbonyl compound is 2-aldehyde cyclohexanone, dicyclohexyl ketone, dicyclopentyl ketone, methyl hexyl ketone, citral or dicyclopropyl ketone.

[0027] Furthermore, the olefin compound is a compound containing two or more unsaturated double bonds.

[0028] Furthermore, the olefin compound is a conjugated olefin compound or a non-conjugated olefin compound.

[0029] Specifically, the olefin compound is hexadiene, cyclohexadiene, allyl diglycol carbonate, 1,4-butanediol divinyl ether, diethylene glycol divinyl ether, cyclopentadiene, dicyclopentadiene, terpinene, norbornadiene, myrcene, acrylic acid, methacrylic acid or a vinyl ether compound.

[0030] Option 2)

[0031] A method for preparing a pure cationic system photosensitive resin composition comprises the following steps:

[0032] (1) mixing the cationic photoinitiator, thioxanthone, epoxy resin, carbonyl compound and olefin compound in proportion and stirring evenly to obtain a mixture;

[0033] (2) The mixed material is irradiated with 450-470 nm light for pretreatment for 1-2 hours to obtain the pure cationic system photosensitive resin composition.

[0034] The present invention has at least the following beneficial effects:

[0035] (1) In photosensitive resins, carbonyl compounds and non-conjugated olefin compounds that are not suitable for general SLA photocuring conditions are converted into oxetane compounds suitable for this field through the Paternó-Büchi reaction principle, which greatly expands the range of raw material selection in the field of SLA photocuring;

[0036] (2) Through the resin light pretreatment method, a large number of oxetane groups are preformed, which greatly promotes the cationic UV curing reaction of epoxy resin and solves the problem of slow epoxy group-initiated polymerization and poor initial performance in the SLA light curing process;

[0037] (3) Free radical polymerization reaction is avoided during the photocuring process, fundamentally solving the problems of material size shrinkage and oxygen inhibition caused by it. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are further described below in conjunction with examples. It should be noted that the embodiments and examples cited are only used to demonstrate the beneficial effects of the present invention, and are not intended to limit the scope of application of the present invention. The raw materials used in the following examples are all commercially available products.

[0039] This embodiment provides a pure cationic photosensitive resin composition, which is prepared from the following components in parts by mass:

[0040] Cationic photoinitiator 2-5 parts

[0041] Photosensitizer 0.5~1.5 parts

[0042] Epoxy resin 20-50 parts

[0043] 10-40 parts of carbonyl compound

[0044] 10 to 40 parts of olefin compound.

[0045] In one embodiment, the cationic photoinitiator is one or more of diphenyliodonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, and 4,4'-dimethyldiphenyliodonium hexafluorophosphate in any proportion.

[0046] It should be noted that the present invention does not limit the type of cationic photoinitiator.

[0047] In one embodiment, the photosensitizer is thioxanthone, camphorquinone, bis-2,6-difluoro-3-pyrrolephenyl titanocene (photoinitiator 784), phenyl dichloroacetamide, etc., preferably thioxanthone.

[0048] In the present invention, carbonyl compounds and olefin compounds undergo Paternó–Büchi reaction (PB reaction) under the catalysis of photosensitizers (including thioxanthone) and visible light in the range of 420 to 470 nm, and a large number of intermediates with oxetane structures are generated in advance, which participate in cationic ring-opening polymerization under subsequent UV light curing conditions to form a cross-linked structure. It should be noted that in this process, the PB reaction may compete with side reactions such as rearrangement reactions, resulting in decreased efficiency. After experiments, it was found that this problem was solved when certain types of photosensitizers (such as thioxanthone) were used.

[0049] In a preferred embodiment, the epoxy resin is an alicyclic epoxy resin, including 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, (3,4,3',4'-diepoxy)dicyclohexane, dicyclopentadiene diepoxide, tetrahydroindene diepoxide, vinylcyclohexene dioxide, one or more of any proportion. The reason why the present invention prefers alicyclic epoxy resins is that the epoxy group reaction activity of alicyclic epoxy resins is relatively high.

[0050] In an optional embodiment, the present invention may also use other non-alicyclic epoxy resins with higher activity, such as BPA-type epoxy resins, o-cresol-type epoxy resins, phenolic-type epoxy resins, etc. Those skilled in the art may select appropriate epoxy resin types within a wider range according to specific needs.

[0051] In one embodiment, the carbonyl compound is one of the compounds of Formula 1 or Formula 2, or a mixture of the two in any proportion.

[0052]

[0053] Wherein, R1, R2, and R3 are organic groups containing 1 to 10 carbon atoms.

[0054] It should be noted that R1, R2, and R3 may be the same or different.

[0055] In a specific embodiment, R1, R2, and R3 include but are not limited to alkyl, cycloalkyl, carbonyl, aldehyde, ether bond, cyclic ether, ester or vinyl.

[0056] In an optional embodiment, the present invention may also use a variety of carbonyl compounds mixed in any proportion, or use substances containing single / multiple carbonyl groups, which will not affect the implementation effect of the present invention.

[0057] In a preferred embodiment, the carbonyl compound of the present invention is 2-aldehyde cyclohexanone, dicyclohexyl ketone, dicyclopentyl ketone, methyl hexyl ketone, citral or dicyclopropyl ketone.

[0058] In one embodiment, the olefin compound of the present invention is a compound containing two or more unsaturated double bonds.

[0059] In one embodiment, the olefin compound includes but is not limited to butadiene, pentadiene, hexadiene, cyclohexadiene, allyl diglycol carbonate, 1,4-butanediol divinyl ether, diethylene glycol divinyl ether, cyclopentadiene, dicyclopentadiene, terpinene, norbornadiene or myrcene.

[0060] In a specific embodiment, the olefin compound is allyl diglycol carbonate, dicyclopentadiene, and myrcene.

[0061] In one embodiment, the present invention can use conjugated olefins such as acrylic acid, methacrylic acid, vinyl ether and other monomers containing unsaturated double bonds, and can also use other non-conjugated olefin monomers. The present invention does not specifically limit the type of olefin monomers. No matter what type of olefin monomer is used, it does not affect the advantageous effects of the present invention. When acrylic acid / methacrylic acid monomers are used, a free radical initiator can also be added simultaneously to initiate a free radical photocuring reaction. The present invention does not specifically limit the use or non-use of free radical photoinitiators.

[0062] Of course, the present invention can also use some monoolefins with good properties.

[0063] As an optional solution, when necessary, the present invention may also add other functional components, including but not limited to: functional polymers, oligomers, organic / inorganic fillers, pigments, leveling agents, etc., and those skilled in the art can adjust according to actual needs without affecting the beneficial effects of the present invention.

[0064] The preparation method of the pure cationic system photosensitive resin composition is:

[0065] (1) mixing the cationic photoinitiator, photosensitizer, alicyclic epoxy resin, carbonyl compound and olefin compound in proportion and stirring evenly to obtain a mixture;

[0066] (2) The mixture is irradiated with 450-470 nm light for 1-2 hours to obtain the pure cationic photosensitive resin composition. The irradiation can also be carried out under stirring.

[0067] Specifically, during the pretreatment process of step (1), the carbonyl compound and the olefin compound undergo a Paternó–Büchi reaction (PB reaction) under the catalysis of the photosensitizer and after light radiation, to generate a large amount of intermediates with an oxetane structure. In this process, the cationic initiator is not excited, so the resin will not be cured, and the formed oxetane intermediate can be stably present for a long time after the end of step (2), so the photosensitive resin composition of the present invention has good long-term storage stability.

[0068] Example 1

[0069] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0070] Cationic photoinitiator 2 parts

[0071] 1.5 parts of photosensitizer

[0072] Epoxy resin 40.5 parts

[0073] 28 parts of carbonyl compounds

[0074] 28 parts of olefin compound.

[0075] The preparation method comprises mixing and stirring 100 g of a cationic photoinitiator (diphenyliodonium hexafluorophosphate), 75 g of a photosensitizer (thioxanthone), 2025 g of an epoxy resin (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate), 1400 g of a carbonyl compound (2-aldehyde cyclohexanone), and 1400 g of an olefin compound (dicyclopentadiene) to obtain 5 kg of a premix, and then stirring the premix under a blue light lamp of 450 to 460 nm for 1 hour to obtain a target photosensitive resin composition.

[0076] Example 2

[0077] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0078] Cationic photoinitiator 5 parts

[0079] 1.5 parts of photosensitizer

[0080] Epoxy resin 20 parts

[0081] 33.5 parts of carbonyl compounds

[0082] 40 parts of olefin compound.

[0083] The preparation method comprises the following steps: fully mixing and stirring 50 g of a cationic photoinitiator (diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate), 15 g of a photosensitizer (bis-2,6-difluoro-3-pyrrolophenyl titanocene), 200 g of an epoxy resin (dicyclopentadiene diepoxide), 335 g of a carbonyl compound (dicyclohexyl ketone), and 400 g of an olefin compound (allyl diglycol carbonate) to obtain 1 kg of a premix, and then stirring the premix under a blue light lamp of 465 to 470 nm for 2 hours to obtain a target photosensitive resin composition.

[0084] Example 3

[0085] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0086] Cationic photoinitiator 5 parts

[0087] Photosensitizer 0.5 parts

[0088] Epoxy resin 20 parts

[0089] 34.5 parts of carbonyl compounds

[0090] 40 parts of olefin compound.

[0091] The preparation method comprises the following steps: fully mixing and stirring 500 g of a cationic photoinitiator (4,4'-dimethyldiphenyliodonium hexafluorophosphate), 50 g of a photosensitizer (camphorquinone), 2000 g of an epoxy resin ((3,4,3',4'-diepoxy)bicyclohexane), 3450 g of a carbonyl compound (2-aldehyde cyclohexanone), and 4000 g of an olefin compound (myrcene) to obtain 10 kg of a premix, and then stirring the premix under a blue light lamp of 465 to 470 nm for 1.5 hours to obtain a target photosensitive resin composition.

[0092] Example 4

[0093] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0094] Cationic photoinitiator 4.5 parts

[0095] 1.5 parts of photosensitizer

[0096] Epoxy resin 50 parts

[0097] 10 parts of carbonyl compound

[0098] 34 parts of olefin compound.

[0099] The preparation method comprises the following steps: fully mixing and stirring 90 g of a cationic photoinitiator (diphenyliodonium hexafluorophosphate), 30 g of a photosensitizer (thioxanthone), 1000 g of an epoxy resin (vinyl cyclohexene dioxide), 200 g of a carbonyl compound (dicyclopentyl ketone), and 680 g of an olefin compound (norbornadiene) to obtain 2 kg of a premix; and then stirring the premix under a blue light lamp of 465 to 470 nm for 1 hour to obtain a target photosensitive resin composition.

[0100] Example 5

[0101] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0102] Cationic photoinitiator 5 parts

[0103] 1.5 parts of photosensitizer

[0104] Epoxy resin 50 parts

[0105] 33.5 parts of carbonyl compounds

[0106] 10 parts of olefin compound.

[0107] The preparation method comprises the following steps: fully mixing and stirring 250 g of a cationic photoinitiator (triphenylsulfonium hexafluorophosphate), 75 g of a photosensitizer (phenyl dichloroacetamide), 2500 g of an epoxy resin (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate), 1675 g of a carbonyl compound (citral), and 500 g of an olefin compound (ethoxylated trimethylol triacrylate) to obtain 5 kg of a premix; and then stirring the premix under a blue light of 450 to 460 nm for 2 hours to obtain a target photosensitive resin composition.

[0108] Example 6

[0109] The pure cationic photosensitive resin composition of this embodiment is prepared from the following components in parts by weight:

[0110] Cationic photoinitiator 2.5 parts

[0111] Photosensitizer 1.2 parts

[0112] Epoxy resin 20 parts

[0113] 40 parts of carbonyl compounds

[0114] 36.3 parts of olefin compounds.

[0115] The preparation method comprises the following steps: 125 g of a cationic photoinitiator (diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate), 60 g of a photosensitizer (thioxanthone), 1000 g of an epoxy resin (tetrahydroindene diepoxide), 2000 g of a carbonyl compound (dicyclopropyl ketone), and 1815 g of an olefin compound (diethylene glycol divinyl ether) are fully mixed and stirred to obtain 5 kg of a premix; and then the premix is ​​stirred for 2 hours under a blue light of 450 to 460 nm to obtain a target photosensitive resin composition.

[0116] Comparative Example 1

[0117] 200 g of diphenyliodonium hexafluorophosphate, 100 g of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2250 g of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 1000 g of 3-methyl-3-hydroxymethyloxetane, and 1450 g of ethoxylated trimethylol triacrylate were fully mixed and stirred to obtain a photocurable photosensitive resin composition.

[0118] Comparative Example 2

[0119] 250 g of cationic photoinitiator (triphenylsulfonium hexafluorophosphate), 150 g of free radical photoinitiator (isopropylthioxanthone), epoxy resin composition (1250 g of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate and 1750 g of E51 epoxy resin), 750 g of 3,3'-(oxybismethylene)bis(3-ethyl)oxetane, and 850 g of tripropylene glycol diacrylate were fully mixed and stirred to obtain a photocurable photosensitive resin composition.

[0120] Comparative Example 3

[0121] 200 g of a cationic photoinitiator (4,4′-dimethyldiphenyliodonium hexafluorophosphate), 150 g of a free radical photoinitiator (isopropylthioxanthone), 1250 g of an alicyclic epoxy resin (bis(3,4-epoxycyclohexylmethyl)adipate), and an acrylic composition (750 g of ethoxylated bisphenol A diacrylate and 450 g of pentaerythritol triacrylate) were fully mixed and stirred to obtain a photocurable photosensitive resin composition.

[0122] Among them, the conventional preparation method was adopted in Comparative Examples 1 and 2, i.e., a composite system of acrylic free radical photoinitiator and epoxy resin cationic photoinitiator, and oxetane monomer was directly added to promote cationic photocuring reaction. However, no oxetane was added in Comparative Example 3.

[0123] The resin compositions prepared in the above embodiments and comparative examples were respectively poured into an SLA light-curing printer, and 3D printing was performed using a 300-350nm ultraviolet light source. The obtained samples were cleaned and dried, placed in an ultraviolet curing box for curing for 20 minutes, and then heat-treated in an oven at 60°C for 1 hour to obtain test samples.

[0124] The samples were tested for heat deformation performance (HDT) comparison according to the test method of GB / T 1634, and for bending performance according to GB / T 9431-2008. At the same time, the size of the samples was accurately tested for accuracy comparison.

[0125] The test results are as follows:

[0126]

[0127]

[0128] From the test comparison data, it can be seen that: 1. The thermal deformation temperature of the materials printed by the photosensitive resin compositions obtained in Examples 1 to 6 all exceeded 100°C, while Comparative Examples 1 to 2 were photocurable resins prepared using traditional preparation processes, and the thermal deformation temperature of the printed materials was relatively low, which shows that the method of the present invention can achieve full reaction of the pure cationic system in a free radical-free photocurable system, and at the same time has good heat resistance; 2. By comparing Examples 1 to 6 with Comparative Example 3, it is found that in the traditional method, if no oxetane monomer is added to promote cationic ring opening, the performance of the obtained material is poor, while by using the method of the present invention, no oxetane is added, and a higher performance cured material can be obtained; 3. By comparing Examples 1 to 6 with Comparative Examples 1 to 3, it is found that by using the method of the present invention, the dimensional accuracy of the obtained material is high, while the comparative example using the traditional dual catalytic system has poor dimensional accuracy due to the reaction shrinkage characteristics of acrylic acid.

[0129] The present invention is not limited to the above embodiments, and all improvements made based on the principles of the present invention are within the protection scope of the present invention.

Claims

1. A pure cationic system photosensitive resin composition, characterized in that: It is mainly prepared from the following components by weight: Cationic photoinitiator 2-5 parts Photosensitizer 0.5~1.5 parts Epoxy resin 20-50 parts 10-40 parts of carbonyl compound 10 to 40 parts of olefin compound.

2. A pure cationic photosensitive resin composition according to claim 1, characterized in that: The cationic photoinitiator is one or more of diphenyliodonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, and 4,4'-dimethyldiphenyliodonium hexafluorophosphate in any proportion.

3. The pure cationic system photosensitive resin composition according to claim 1, characterized in that: The photosensitizer is one or more of thioxanthone, camphorquinone, bis-2,6-difluoro-3-pyrrolephenyl titanocene (photoinitiator 784), and phenyl dichloroacetamide in any proportion.

4. A pure cationic system photosensitive resin composition according to claim 1, characterized in that: The epoxy resin is an alicyclic epoxy resin or a non-alicyclic epoxy resin.

5. A pure cationic photosensitive resin composition according to claim 4, characterized in that: The alicyclic epoxy resin is one or more of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, (3,4,3',4'-diepoxy)bicyclohexane, dicyclopentadiene diepoxide, tetrahydroindene diepoxide, and vinylcyclohexene dioxide in any proportion; The non-alicyclic epoxy resin is one or more of BPA type epoxy resin, o-cresol type epoxy resin or phenolic type epoxy resin in any proportion.

6. A pure cationic photosensitive resin composition according to claim 1, characterized in that: The carbonyl compound is one of the compounds of formula 1 or formula 2, or a mixture of the two in any proportion. Wherein, R1, R2, and R3 are organic groups containing 1 to 10 carbon atoms.

7. A pure cationic photosensitive resin composition according to claim 6, characterized in that: The R1, R2 and R3 are alkyl, cycloalkyl, carbonyl, aldehyde, ether bond, cyclic ether, ester or vinyl.

8. A pure cationic photosensitive resin composition according to claim 7, characterized in that: The carbonyl compound is 2-aldehyde cyclohexanone, dicyclohexyl ketone, dicyclopentyl ketone, methyl hexyl ketone, citral or dicyclopropyl ketone.

9. A pure cationic photosensitive resin composition according to claim 1, characterized in that: The olefin compound is a non-conjugated olefin compound or a conjugated olefin compound; the olefin compound is hexadiene, cyclohexadiene, allyl diglycol carbonate, cyclopentadiene, dicyclopentadiene, terpinene, norbornadiene, myrcene, acrylic acid, methacrylic acid or a vinyl ether compound.

10. The method for preparing a pure cationic photosensitive resin composition according to any one of claims 1 to 9, characterized in that: The steps include: (1) mixing the cationic photoinitiator, photosensitizer, epoxy resin, carbonyl compound and olefin compound and stirring them uniformly to obtain a mixture; (2) The mixed material is irradiated with 450-470 nm light for pretreatment for 1-2 hours to obtain the pure cationic system photosensitive resin composition.

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