JP-2026074646-A - Cured film, lens, and inspection method

Abstract

[Problem] The objective is to provide a cured film, a lens, and a method for inspecting a cured film that ensures adhesion to a substrate. [Solution] An active energy curable film that covers at least a portion of the surface of a substrate, wherein the cured film has a ratio A/B of 0.2 or more and less than 0.55 between the peak area (A) due to C=C stretching vibration originating from vinyl groups and the peak area (B) due to C=O stretching vibration originating from ester groups, as detected by FT-IR analysis ATR method, and the peak areas (A) and (B) are determined by the peak area in the wavelength band from the short wavelength side to the long wavelength side of the full width at half maximum of each peak (P1, P2), and the peel strength between the substrate and the cured film by surface-interface cutting method is 0.0005 N or more. [Selection Diagram] Figure 3

Inventors

• 岡本 羽純
• 堀場 幸治

Assignees

• スタンレー電気株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (6)

1. An active energy curable film that covers at least a portion of the surface of a substrate, The cured film has a ratio A/B of 0.2 or more and less than 0.55 between the peak area (A) due to C=C stretching vibration originating from vinyl groups and the peak area (B) due to C=O stretching vibration originating from ester groups, as detected by FT-IR analysis ATR method. The aforementioned peak area (A) and peak area (B) are determined by the area of the peak in the wavelength band from the short-wavelength side to the long-wavelength side of the full width at half maximum of each peak. A cured film having a peel strength of 0.0005 N or more when measured by surface-interface cutting between the substrate and the cured film.
2. The value of A/B is less than 0.41, The cured film according to claim 1, wherein the peel strength of the substrate and the cured film by surface-interface cutting is 0.001 N or more.
3. The cured film according to claim 1, wherein the thickness of the cured film is 5 μm or more and 20 μm or less.
4. The cured film according to claim 1, wherein the substrate is a polycarbonate resin or a polymethyl methacrylate resin.
5. A lens for a vehicle lamp having the cured film described in claim 3.
6. A method for inspecting an active energy curing type cured film that has been thinly cured on at least a portion of the surface of a substrate, The peak area (A) due to C=C stretching vibrations originating from vinyl groups and the peak area (B) due to C=O stretching vibrations originating from ester groups, which are detected by measuring the cured film using the FT-IR analysis ATR method, are determined by the area of the peaks in the wavelength band from the short-wavelength side to the long-wavelength side of the full width at half maximum of each peak. A method for inspecting a cured film, wherein the adhesion between the surface interface of the substrate and the cured film is determined from the ratio A/B of the peak area (A) and the peak area (B).

Description

This invention relates to a cured film, a lens, and an inspection method. Synthetic resins such as polycarbonate resin (PC) and polymethyl methacrylate resin (PMMA) are used in many fields, including lenses (translucent covers) for lights in automobiles and motorcycles, eyeglass lenses, optical sensor covers, and various liquid crystal panels, due to their excellent transparency, moldability, and mechanical properties. However, on the surface of molded products made of synthetic resins, when the surface temperature falls below the dew point, moisture in the atmosphere condenses into fine water droplets, causing fogging. This reduces light transmittance, leading to problems such as poor visibility and sensor malfunctions. Furthermore, scratches or dirt adhering to the surface of molded products made of synthetic resins can also reduce light transmittance, leading to poor visibility and sensor malfunctions. To prevent these problems, a composition is applied to the surface of molded products (substrates) made of synthetic resins and allowed to cure, forming a cured film that ensures transparency (anti-fogging performance, scratch resistance, etc.). For example, Patent Document 1 discloses a hard coat film in which a bonding underlayer mainly composed of a photopolymerization initiator is provided on the surface of a cellulose ester film substrate, and a hard coat layer forming composition layer made of an active energy ray curable resin composition containing 10 to 95% by weight of a compound having two or more (meth)acryloyl groups is provided on the surface of the bonding underlayer, and the cellulose ester film substrate and the hard coat layer are integrally bonded by the curing reaction of the resin by the photopolymerization initiator. The hard coat film is characterized in that, when the resin reaction rate at the surface of the hard coat layer is (A) and the resin reaction rate at the interface between the cellulose ester film substrate and the hard coat layer bonded thereto by the curing reaction of the photopolymerization initiator is (B), the surface resin reaction rate (A) is 60% or more, and the relationship between the surface resin reaction rate (A) and the interface resin reaction rate (B) satisfies the condition: Surface resin reaction rate (A) - Interface resin reaction rate (B) < 30%. Japanese Patent Publication No. 2009-241256 This is a conceptual diagram showing a molded article having a cured film according to the present invention.This figure shows the manufacturing process for a molded article having a cured film according to the present invention.This is an FT-IR chart obtained when the cured film of the present invention was measured using the FT-IR analysis ATR method (Total Reflectance Fourier Transform Infrared Spectroscopy).This graph shows the correlation between the ratio A/B of the peak area due to C=C stretching vibrations originating from vinyl groups (A) and the peak area due to C=O stretching vibrations originating from ester groups (B), which are detected by measuring the cured film of the present invention using FT-IR analysis ATR method (Total Reflectance Fourier Transform Infrared Spectroscopy), and the peel strength of the substrate and the cured film by surface-interface cutting.This table summarizes the comparison results between examples and comparative examples of the cured film of the present invention. Embodiments of the present invention will now be described. The cured film 10 of the present invention is a cured film obtained by thin-film curing an active energy-curable composition containing an acrylate, a hydrophilic monomer, and an initiator onto at least a portion of the surface of a substrate 20. In other words, the cured film 10 covers at least a portion of the surface of the substrate 20. The thickness of the cured film 10 is 1 μm to 20 μm. Acrylate is a highly reactive, hydrophobic, radical-reactive material. By including acrylate in an active energy ray-curable composition, the curing speed of the composition can be accelerated. Furthermore, the highly reactive acrylate cures first, followed later by the hydrophilic monomers with hydrophilic groups. Therefore, the acrylate, which is compatible with hydrophobic substrates, adheres closely to the substrate 20, while the hydrophilic monomers, which cure later, are more easily positioned on the outermost surface. Thus, a thin film of hydrophilic monomer can be applied to the surface of the cured film 10, improving its anti-fogging properties. Because acrylate is hydrophobic, when applied to a hydrophobic substrate 20, it can improve the adhesion between the active energy ray-curable composition and the substrate. Therefore, peeling of the cured film 10 from the substrate 20 can be suppressed. Furthermore, due to the high adhesion between the cured film 10 and the substrate 20, crack formation in low-temperature environments can also be suppressed. Thus, a highly durable cured film 10 can be formed on the