PO composite transfer printing film for out-of-mold transfer printing and preparation method of PO composite transfer printing film

Abstract

The invention provides a PO composite transfer printing film for out-of-mold transfer printing and a preparation method of the PO composite transfer printing film, and relates to the technical field of transfer printing films. A PO composite transfer printing film for out-of-mold transfer printing comprises a carrier layer, a buffer layer, a PO functional layer, a transition layer and a release layer. The PO functional layer is prepared from the following raw materials in parts by mass: 75 to 85 parts of cycloolefin copolymer, 5 to 10 parts of inorganic filler, 3 to 8 parts of silane coupling agent, 1 to 3 parts of antioxidant and 3 to 5 parts of light stabilizer. The PO composite transfer printing film for out-of-mold transfer printing prepared by the invention has excellent alcohol resistance, light transmittance and hardness and relatively low thermal shrinkage rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transfer film, in particular to a PO composite transfer film for off-mold transfer printing and a preparation method thereof. BACKGROUND

[0002] Prior art 1: CN202010583214.X discloses a PMMA functional layer transfer film, which has problems such as poor chemical resistance (alcohol resistance < 50 times) and low surface hardness (< 2H). Prior art 2: US20210340321A1 uses a PC functional layer, although the hardness is improved, but the light transmittance is only 85-88%, which affects the pattern color rendering effect. The problem of the prior art is that the traditional functional layer material has insufficient chemical resistance and cannot pass the mobile phone reliability test. The low surface hardness and poor size stability at high temperature affect the transfer printing precision. SUMMARY

[0003] Based on the technical problems existing in the background technology, the present application provides a PO composite transfer film for off-mold transfer printing and a preparation method thereof.

[0004] The PO composite transfer film for off-mold transfer printing provided by the present application comprises a carrier layer, a buffer layer, a PO functional layer, a transition layer and a release layer.

[0005] Preferably, the thickness of the carrier layer is 100-250 μm, the thickness of the buffer layer is 10-50 μm, the thickness of the PO functional layer is 5-15 μm, the thickness of the transition layer is 80-150 μm, and the thickness of the release layer is 10-30 μm.

[0006] Preferably, the carrier layer is selected from one or more of polyethylene terephthalate film, polyvinyl chloride film and polypropylene film.

[0007] Preferably, the raw material of the buffer layer is selected from one or more of polyurethane and linear low density polyethylene.

[0008] Preferably, the raw material of the release layer is silicone modified acrylic resin.

[0009] Preferably, the raw material of the transition layer comprises polyolefin and SEBS thermoplastic elastomer.

[0010] More preferably, the transition layer comprises polyolefin and SEBS thermoplastic elastomer in a mass ratio of (6-7) : (2-3), which are uniformly mixed at 200-250℃.

[0011] More preferably, the polyolefin is selected from one or more of polyethylene and polypropylene.

[0012] Preferably, the PO functional layer comprises the following raw materials by mass fraction: 75-85 parts of a cyclic olefin copolymer, 5-10 parts of an inorganic filler, 3-8 parts of a silane coupling agent, 1-3 parts of an antioxidant, and 3-5 parts of a light stabilizer.

[0013] More preferably, the melt flow rate (260℃, 2.16kg) of the cyclic olefin copolymer is 40-50g / 10min.

[0014] More preferably, the light transmittance of the cyclic olefin copolymer is 90%-98%.

[0015] More preferably, the inorganic filler is selected from one or more of alumina and silica.

[0016] More preferably, the particle size of the inorganic filler is 10-100nm.

[0017] More preferably, the silane coupling agent is selected from one or more of KH-570 and KH-550.

[0018] More preferably, the antioxidant is selected from one or more of antioxidant 1010 and antioxidant 1076.

[0019] More preferably, the light stabilizer is selected from one or more of light stabilizer 944 and light stabilizer 770.

[0020] Preferably, the PO functional layer is obtained by uniformly mixing the cyclic olefin copolymer, the inorganic filler, the silane coupling agent, the antioxidant, and the light stabilizer at 30-50℃ and 700-1500rpm.

[0021] The present application also provides a preparation method of a PO composite transfer film for off-machine transfer printing, comprising the following steps:

[0022] S1, coating the raw materials of the buffer layer on the surface of the carrier layer, and heating to obtain a film structure A;

[0023] S2, uniformly mixing the raw materials of the transition layer and the PO functional layer respectively, co-extruding, and performing electron beam crosslinking to obtain a film structure B;

[0024] S3, after laminating the buffer layer side of the film structure A with the PO functional layer side of the film structure B, bidirectional synchronous stretching, coating the raw materials of the release layer on the transition layer side of the film structure B, and performing UV curing.

[0025] Preferably, in S1 and S3, the coating is precise micro-gravure coating.

[0026] Preferably, in S1, the heating treatment comprises treating at 70-80℃ for 5-10min, then treating at 120-150℃ for 10-20min, and finally treating at 80-90℃ for 5-10min.

[0027] Preferably, in S2, the extrusion temperature is 240-260℃.

[0028] Preferably, in S2, the electron beam crosslinking comprises irradiating at a radiation dose rate of 10-20kGy / min for 1-2min.

[0029] Preferably, in S3, the bidirectional synchronous stretching comprises longitudinal stretching and transverse stretching; the stretching ratio of the longitudinal stretching is 2.5-3.5; and the stretching ratio of the transverse stretching is 3-4.

[0030] Preferably, in S3, the UV curing comprises curing at an energy of 800-1000mJ / cm 2 , a wavelength of 365nm, and for 5-15s.

[0031] The present application has the following beneficial effects:

[0032] The present application provides a PO composite transfer film for off-mold transfer, which is suitable for off-mold transfer composite film for manufacturing of consumer electronic product shell, and particularly suitable for high-precision texture transfer of back cover of smart phone. The PO composite transfer film for off-mold transfer provided by the present application helps to improve chemical resistance (alcohol wiping resistance ≥ 250 times), improve light transmittance (≥ 93%) and color reproduction, enhance surface hardness (≥ 4H), and improve high-temperature dimensional stability (thermal shrinkage rate ≤ 0.2% @ 150℃). BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The structure diagram of the PO composite transfer film for off-mold transfer provided by the present application is shown in the figure.

[0034] 1 - carrier layer, 2 - buffer layer, 3 - PO functional layer, 4 - transition layer, 5 - release layer. DETAILED DESCRIPTION

[0035] The technical solutions of the present application are described in detail through specific embodiments.

[0036] The materials, reagents, etc. used in the following examples and comparative examples can be obtained from commercial channels unless otherwise specified.

[0037] Example 1

[0038] A PO composite transfer film for off-mold transfer comprises a 200μm carrier layer, a 25μm buffer layer, a 10μm PO functional layer, a 110μm transition layer, and a 20μm release layer.

[0039] The carrier layer is a polyethylene terephthalate film; the raw material of the buffer layer is polyurethane;

[0040] The PO functional layer comprises the following raw materials by mass fraction: 80 parts of a cyclic olefin copolymer (TOPAS 5013L-10), 8 parts of an inorganic filler, 5 parts of a silane coupling agent KH-570, 2 parts of an antioxidant 1010, and 5 parts of a light stabilizer 944; the inorganic filler is nano-Al2O3 with a particle size of 50 nm.

[0041] The PO functional layer is obtained by uniformly mixing the cyclic olefin copolymer, the inorganic filler, the silane coupling agent KH-570, the antioxidant 1010, and the light stabilizer 944 at 40℃ and 1000 rpm.

[0042] The raw material of the release layer is a silicone-modified acrylic resin (Shin-Etsu KS-847H).

[0043] The raw material of the transition layer comprises a polyolefin and a SEBS thermoplastic elastomer.

[0044] The transition layer is obtained by uniformly mixing the polyolefin and the SEBS thermoplastic elastomer at a mass ratio of 7:3 at 240℃; the mass ratio of polyethylene to polypropylene in the polyolefin is 1:1.

[0045] A preparation method of a PO composite transfer film for off-machine transfer printing, comprising the following steps:

[0046] S1, precisely microgravure coat the raw material of the buffer layer on the surface of the carrier layer, first treat at 80℃ for 10 min, then treat at 150℃ for 15 min, and finally treat at 90℃ for 8 min to obtain a film structure A;

[0047] S2, uniformly mix the raw materials of the transition layer and the PO functional layer respectively, co-extrude at an extrusion temperature of 250℃, and perform electron beam crosslinking by irradiating at a radiation dose rate of 20 kGy / min for 1 min to obtain a film structure B;

[0048] S3, after laminating the buffer layer side of the film structure A with the PO functional layer side of the film structure B, perform bidirectional synchronous stretching (longitudinal stretching by 3.2 and transverse stretching by 3.5), coat the raw material of the release layer on the transition layer side of the film structure B, and perform UV curing by using a UV lamp with an energy of 800 mJ / cm 2 , a wavelength of 365 nm, and curing for 10 s.

[0049] Example 2

[0050] Example 2 differs from Example 1 only in the PO functional layer, and the rest is the same as Example 1; the specific differences are as follows:

[0051] The PO functional layer comprises the following raw materials by mass fraction: 81 parts of a cyclic olefin copolymer (TOPAS 5013L-10), 10 parts of an inorganic filler, 5 parts of a silane coupling agent KH-570, 2 parts of an antioxidant 1010, and 5 parts of a light stabilizer 944; the inorganic filler is composed of nano-Al2O3 with a particle size of 50 nm and nano-SiO2 with a particle size of 30 nm at a mass ratio of 3:1.

[0052] Example 3

[0053] Example 3 is different from Example 1 only in that the PO composite transfer film structure for off-machine transfer and the preparation method are different, and the rest is the same as Example 1; specifically as follows:

[0054] A PO composite transfer film for off-machine transfer, comprising a 230 μm carrier layer, a 35 μm buffer layer, a 10 μm PO functional layer, an 80 μm transition layer, and a 20 μm release layer.

[0055] A preparation method of a PO composite transfer film for off-machine transfer, comprising the following steps:

[0056] S1, precisely microgravure coating the raw materials of the buffer layer on the surface of the carrier layer, first treating at 85°C for 8 min, then treating at 150°C for 15 min, and finally treating at 90°C for 8 min to obtain film structure A;

[0057] S2, uniformly mixing the raw materials of the transition layer and the PO functional layer respectively, co-extruding at an extrusion temperature of 250°C, and performing electron beam crosslinking at a radiation dose rate of 10 kGy / min for 2 min to obtain film structure B;

[0058] S3, after laminating the buffer layer side of film structure A with the PO functional layer side of film structure B, bidirectional synchronous stretching (3.2 times in the longitudinal direction and 3.5 times in the transverse direction), coating the raw materials of the release layer on the transition layer side of film structure B, and performing UV curing at an energy of 800 mJ / cm 2 , a wavelength of 365 nm, and a curing time of 10 s.

[0059] Comparative Example 1

[0060] Comparative Example 1 is a commercially available off-machine transfer film.

[0061] The PO composite transfer film for off-machine transfer is tested for alcohol resistance, light transmittance, pencil hardness, and thermal shrinkage (150°C). The test results are shown in Table 1.

[0062] Table 1

[0063] Group Alcohol resistance (times) Transmittance Pencil hardness Heat shrinkage / 150°C Example 1 250 times no change 93.8％ 4H 0.2％ Example 2 250 times no change 93.2％ 4H 0.2％ Example 3 250 times no change 93.5％ 4H 0.2％ Comparative Example 1 85 times no change 87％ 2H 0.7％

[0064] As can be seen from the data in Table 1, the PO composite transfer film prepared by the present application has excellent alcohol resistance, light transmittance, hardness and low heat shrinkage.

[0065] In summary, the PO composite transfer film for off-mold transfer provided by the present application helps to improve chemical resistance (alcohol resistance ≥ 250 times), improve light transmittance (≥ 93%) and color reproduction, enhance surface hardness (≥ 4H), and improve high-temperature dimensional stability (heat shrinkage ≤ 0.2% @ 150°C).

[0066] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution and the inventive concept of the present application, equivalent replacement or change, should be covered within the protection scope of the present application.

Claims

1. A PO composite transfer film for off-mold transfer, characterized in that: It includes a carrier layer, a buffer layer, a PO functional layer, a transition layer, and a release layer; the PO functional layer includes the following raw materials in parts by weight: 75-85 parts of cycloolefin copolymer, 5-10 parts of inorganic filler, 3-8 parts of silane coupling agent, 1-3 parts of antioxidant, and 3-5 parts of light stabilizer.

2. The PO composite transfer film for off-mold transfer according to claim 1, characterized in that: The melt flow rate (260° C., 2.16 kg) of the cycloolefin copolymer is 40-50 g / 10 min; and the light transmittance of the cycloolefin copolymer is 90%-98%.

3. The PO composite transfer film for off-mold transfer according to claim 1, characterized in that: The inorganic filler is selected from one or more of alumina and silica; the particle size of the inorganic filler is 10-100 nm; the silane coupling agent is selected from one or more of KH-570 and KH-550; the antioxidant is selected from one or more of antioxidant 1010 and antioxidant 1076; the light stabilizer is selected from one or more of light stabilizer 944 and light stabilizer 770.

4. The PO composite transfer film for off-mold transfer according to claim 1, characterized in that: The carrier layer is selected from one or more of polyethylene terephthalate film, polyvinyl chloride film, and polypropylene film; the raw material of the buffer layer is selected from one or more of polyurethane and linear low-density polyethylene; the raw material of the release layer is silicone-modified acrylic resin.

5. The PO composite transfer film for off-mold transfer according to claim 1, characterized in that: The raw materials of the transition layer include polyolefin and SEBS thermoplastic elastomer; the polyolefin is selected from one or more of polyethylene and polypropylene.

6. A method for preparing the PO composite transfer film for off-mold transfer according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Coating the raw material of the buffer layer on the surface of the carrier layer and heating it to obtain a membrane structure A; S2, respectively, mixing the raw materials of the transition layer and the PO functional layer, co-extruding, and electron beam cross-linking to obtain a membrane structure B; S3. After laminating the buffer layer of membrane structure A and the PO functional layer of membrane structure B, they are bidirectionally stretched synchronously, and the raw material of the release layer is coated on the transition layer of membrane structure B, and UV curing is performed to obtain.

7. The preparation method according to claim 6, characterized in that In the above-mentioned S1, the heating treatment includes treating at 70-80°C for 5-10 minutes, treating at 120-150°C for 10-20 minutes, and finally treating at 80-90°C for 5-10 minutes.

8. The preparation method according to claim 6, characterized in that In the above-mentioned S2, the extrusion temperature is 240-260° C.; and the electron beam cross-linking comprises irradiation at a radiation dose rate of 10-20 kGy / min for 1-2 minutes.

9. The preparation method according to claim 6, characterized in that In the above S3, the bidirectional synchronous stretching includes longitudinal stretching and transverse stretching; the stretching ratio of the longitudinal stretching is 2.5-3.5; the stretching ratio of the transverse stretching is 3-4; the UV curing includes an energy of 800-1000mJ / cm 2 , wavelength is 365nm, curing is 5-15s.

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