의미와 목적
5.1 모든 가속 테스트와 마찬가지로, the increase in weathering rate compared to in-service exposure depends on the material. 그러므로, there is no acceleration factor that can be used to correlate two different types of outdoor weathering exposure. When comparing coatings with different compositions, the weatherability rankings of the coatings provided by these two programs may not be consistent. The two processes should not be used interchangeably.

5.2 The procedures described in this practice are designed to provide a higher degradation rate of coatings than those provided by fixed Angle, open, outdoor exposure racks. For many products, fixed-angle exposure will yield a higher degradation rate than the normal end use of the material.

5.2.1 For materials with higher temperature end-use conditions, using procedure A (black box) instead of open rack direct exposure is a more realistic test. For many coatings, this process provides degradation rates higher than 5° that would be provided by an open exposure facing the equator, as the black box produces higher sample temperatures and longer sample humidity times during daylight exposure. The temperature of the black box sample is comparable to that on the hood, roof and deck cover of a car parked in the sun. ASTM STP 781 gives the relative rates of gloss loss and color change resulting from exposure to procedure A in certain automotive coatings. four

5.2.2 The weathering accelerated degradation described in procedure C is generated by reflecting sunlight from ten mirrors onto the air-cooled sample area. Approximately 1400 MJ/m2 in the central Arizona climate received UV radiation exposure (295 to 385nm) during a typical year when the samples were exposed to these devices. In comparison, approximately 333 MJ/m2 central Arizona latitude exposure and 280 MJ/m2 Southern Florida latitude exposure to UV radiation during the same time period. 하지만, the test described in Procedure C only reflects the beam radiation onto the test sample. The reflected direct beam of sunlight contains a lower percentage of shortwave UV radiation than global daylight, because shortwave UV is more easily scattered by the atmosphere, and because mirrors are generally less efficient at shorter UV wavelengths. The level of UV radiation exposure should not be used to calculate the acceleration coefficient because the acceleration depends on the material.

5.3 Due to differences in ultraviolet (자외선) radiation, 젖은 시간, 온도, 오염물질, 그리고 다른 요인, the weather resistance of coatings for outdoor use can vary considerably depending on the geographical location of exposure. 그러므로, it cannot be assumed that the results of a single exposure at a single location will help determine the relative weatherability of different locations. Exposure is recommended at multiple locations with different climates that represent a wide range of expected use conditions to determine weather resistance and/or service life.

ASTM D 4141-2022 코팅을 위한 다크박스 및 집중된 햇빛 노출

5.4 매년 기후변화로 인해, 단일 노출 테스트의 결과는 재료 열화의 절대 속도를 예측하는 데 사용할 수 없습니다..

메모 3: Repeated exposures of three or more years, starting at different times of the year, are typically required to obtain “평균” test results for a given location.

5.4.1 The degradation curves of many coatings are not linear functions of exposure time or radiation exposure. When short exposures are used as an indicator of weather resistance, the results obtained may not be representative of those obtained for long exposures.

메모 4: Guidance G141 provides information to address variability in exposure testing for non-metallic materials. 지침 G169는 노출 테스트 결과에 통계를 적용하는 방법에 대한 정보를 제공합니다..

5.5 It is recommended that at least one control material be used in any exposure assessment. The control material is used to compare the performance of the test material relative to the control when the materials are not ranked against each other. The reference material used shall have a similar composition and structure to the test material and shall have known weather resistance. Two control materials are recommended, one with relatively good weather resistance and one with poor weather resistance.

ASTM D 4141-2022 코팅을 위한 다크박스 및 집중된 햇빛 노출

범위
1.1 The practice covers two accelerated outdoor exposure procedures for assessing the external weather resistance of coatings applied to substrates.

1.2 The two processes are as follows:

1.2.1 Procedure A — Black box Exposure.

1.2.2 Program C — Fresnel reflector rack exposure.

메모 1: Procedure B describes the heating black box subprocedure, which is no longer in common use and has been removed from the 2014 revision of this standard.

1.3 This standard does not cover all procedures that can be used by users to accelerate the outdoor exposure of coatings. Other procedures are used to provide specific effects; 하지만, the two processes described here are widely used.

1.4 SI 단위나 잉크파운드 단위로 표현된 값은 표준값으로 별도로 취급되어야 합니다.. 각 시스템에 지정된 값이 반드시 동일할 필요는 없습니다.; 그러므로, 표준 준수를 보장하기 위해, 각 시스템은 서로 독립적으로 사용해야 하며 두 시스템의 값을 결합해서는 안 됩니다..

ASTM D 4141-2022 코팅을 위한 다크박스 및 집중된 햇빛 노출

1.5 이 표준은 모든 안전 문제를 다루기 위한 것이 아닙니다., 만약에 어떠한, 그 사용과 관련된. 적절한 안전을 확립하는 것은 이 표준 사용자의 책임입니다., 건강 및 환경 관행을 확인하고 사용 전 규제 제한의 적용 여부를 결정합니다..

1.6 본 국제 표준은 국제 표준 개발 원칙에 관한 결정에서 확립된 국제적으로 인정받는 표준화 원칙에 따라 개발되었습니다., 세계무역기구(WTO) 무역기술장벽위원회가 발행한 지침 및 권고사항.