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印刷包装色相不一致怎么办?

保持色相一致性是包装印刷的基本要求。为此,包装印刷企业采用了不同的管控方法。然而,随着检测技术的不断革新,“人眼感官比对+色差值判定+光谱反射率判定”的综合判定模式已经成为大家的共识,即要求印样与标准样“面色”一致,且“同色同谱”。

To keep the color consistency is the basic requirement of packaging printing. Therefore, packaging and printing enterprises adopt different control methods. However, with the continuous innovation of detection technology, the comprehensive judgment mode of "human visual sensory comparison + color difference value judgment + spectral reflectance judgment" has become a consensus, that is, it is required that the printing sample and the standard sample "face color" are the same, and "same color and spectrum".

什么是“同色同谱”?

What is homochromatic spectrum?

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光谱反射率曲线是指被物体反射的光通量与入射到物体的光通量之比,即光反射比与波长之间的关系曲线,是材料自身的一种固有特性,可称之为材料的“指纹”,其曲线的光谱数据可视为该材料的“DNA”。

The spectral reflectance curve refers to the ratio of the luminous flux reflected by the object to the luminous flux incident on the object, that is, the relation curve between the optical reflectance ratio and the wavelength. It is an inherent characteristic of the material itself, which can be called the "fingerprint" of the material. The spectral data of the curve can be regarded as the "DNA" of the material.

如果两个颜色具有相同的三刺激值,且具有完全相同的光谱反射率曲线,则称这两个颜色为同色同谱色,同色同谱色在不同的照明光源、不同的视场条件下,色相保持一致;若两个颜色具有相同的三刺激值,但具有不同的光谱反射率,则称这两个颜色为同色异谱色,同色异谱色在特定的不同的照明光源、不同的视场条件下可能会呈现不同的色相。

If two colors have the same tristimulus value and the same spectral reflectance curve, they are called homochromatic and homospectral colors, and the color phase of homochromatic and homospectral colors is consistent under different lighting sources and different field of view; if two colors have the same tristimulus value but different spectral reflectance, they are called homochromatic and heterospectral colors The same color and different spectrum may present different hues under different lighting sources and different field of view.

在实际生产中,绝对的同色同谱色是不存在的。要求印样的光谱反射率曲线与标准样相吻合,且色差值ΔE*ab控制在标准规定范围内即可。

In actual production, there is no absolute homochromatic color. It is required that the spectral reflectance curve of the printed sample is consistent with the standard sample, and the color difference value Δ e * AB is controlled within the specified range of the standard.

印刷色相管控存在的普遍问题

Common problems in printing color control

1.标准样存在色差

1. Color difference in standard sample

客户签样与样张比对过程影响因素较多,另外所签发标准样存在色差。

There are many influencing factors in the process of comparison between customer's signature sample and sample sheet, in addition, there is color difference in the standard sample issued.

2.检测设备存在台间差

2. There is difference between test equipment

客户与印刷企业所使用的色相检测设备,如美国爱色丽(X-Rite)Ci7x00/Ci6x/SP6x、德国德塔(DataColor)DCx00以及日本美能达(MINOLTA)CM-2x00/CM-3x00等品牌、型号较多,还有少部分印刷企业使用国产检测设备,存在不同程度的台间差问题,且标准建立与测色方式有所不同。

There are many brands and models of color detection equipment used by customers and printing enterprises, such as X-Rite ci7x00 / ci6x / sp6x in the United States, Datacolor dcx00 in Germany, and Minolta cm-2x00 / cm-3x00 in Japan. A few printing enterprises use domestic detection equipment, which has different degree of platform difference, and the standard establishment and color measurement method are different.

3.印刷过程色相变化因素较多

3. There are many factors of color change in the printing process

批量生产前调色过程、印刷过程油墨黏度变化、纸张(特殊纸张)色差、油墨批次间色差、印版印次差异(网穴深浅)等因素均会造成印刷过程的色相变化,甚至色差值超标。

Before batch production, the color matching process, the change of ink viscosity, the color difference between paper and paper, the difference between printing batch and printing plate, and the difference between printing plate and printing plate will cause the hue change of printing process exceed the standard of color difference.

4.常规抽样检测存在局限性

4. Limitations of routine sampling inspection

印刷过程抽样检测数量有限,只代表检验个体,无法真实反映批次产品印刷色相。另外,抽检过程质量信息反馈不及时,往往在抽检不合格时已产生部分不合格品,只能通过挑选进行清理,“死后验尸”。

In the printing process, the number of sampling inspection is limited, which only represents the inspection individual and can not truly reflect the printing color of batch products. In addition, the feedback of quality information in the sampling process is not timely, and some unqualified products have been produced when the sampling inspection is unqualified, which can only be cleaned through selection, "postmortem examination after death".

5.无光谱反射率控制标准

5. No spectral reflectance control standard

传统检测设备根据印刷企业设定的色相标准,可对色差值ΔE*ab进行判定,并在检测软件中可显示、导出光谱反射率曲线与数据,但无判定标准与依据。

According to the color standard set by the printing enterprise, the traditional testing equipment can judge the color difference value Δ e * AB, and display and derive the spectral reflectance curve and data in the testing software, but there is no judgment standard and basis.

印刷色相“同色同谱”管控措施

Control measures of printing color phase "same color and same spectrum"

1.建流程

1. Construction process

根据印刷企业目标客户质控要求,以及企业软硬件配置等客观实际,建立适合于企业自身的色相管控流程,对原材料入库、产前准备、印刷生产过程、成品检验等全过程进行有效监控,管控要点见表1。

According to the quality control requirements of the target customers of the printing enterprise, as well as the objective reality of the software and hardware configuration of the enterprise, establish a color control process suitable for the enterprise itself, and effectively monitor the whole process of raw material warehousing, pre production preparation, printing production process, finished product inspection, etc. see Table 1 for the key points of control.

2.建标准

2. Construction standard

不论是新产品打样还是跟样生产,标准样应挑选色相一致的印样,与客户确定统一的测色位置,统一初始色相标准。与客户共同确认标准样后,应建立该产品纸张、油墨等关键原材料入库检验标准、生产过程工艺技术标准及出厂检验标准。

No matter for new product proofing or production with samples, standard samples shall be printed with the same color, and the unified color measuring position and initial color standard shall be determined with customers. After confirming the standard sample with the customer, the warehousing inspection standard, production process technology standard and delivery inspection standard for the key raw materials such as paper and ink of the product shall be established.

针对色相同色同谱管控要求,在原材料入库检验标准中明确对印刷专色油墨、纸张色相及光谱反射率要求,严把道关;生产过程按照工艺技术标准要求,根据各专色油墨配方组成,明确调色墨添加型号、比例和限量值,明确印刷油墨黏度标准要求,避免因色料光谱成分差异或色差值偏大而造成同色异谱。特殊地,企业内控质量指标应适当严于客户标准,以保证交验质量。

According to the requirements of the same color and spectrum management and control, the requirements for the special color printing ink, paper color and spectral reflectance shall be specified in the warehousing inspection standard of raw materials, and the first pass shall be strictly controlled; the production process shall be in accordance with the requirements of the technological standards, the formula composition of the special color printing ink, the added model, proportion and limit value of the color mixing ink, and the requirements for the viscosity standard of the printing ink shall be specified, so as to avoid the problems caused by the color materials The difference of spectral composition or the value of chromatic difference is too large, which results in homochromatic difference. In particular, the internal control quality index of the enterprise should be properly stricter than the customer standard to ensure the quality of delivery and inspection.

3.购设备

3. Purchase of equipment

为准确检测印刷产品色差值与光谱反射率数据,满足生产过程便携使用、定时抽检以及批量产品色相实时监控等多重管控需求,企业应根据自身实际,合理配置印刷在线、离线色相检测设备。

In order to accurately detect the color difference value and spectral reflectance data of printing products, meet the multiple control needs of portable use in the production process, regular spot check and real-time monitoring of the color phase of batch products, enterprises should reasonably configure the printing online and offline color phase detection equipment according to their own reality.

根据管控需求,我公司购置了爱色丽Ci7800台式分光测色仪、爱色丽Ci64便携式分光测色仪、征图单张多光谱颜色测量系统、征图印刷在线多光谱颜色测量系统等多台套检测设备。

According to the management and control requirements, our company has purchased a number of sets of testing equipment, such as Ashley ci7800 desktop spectrophotometer, Ashley ci64 portable spectrophotometer, single sheet multi spectral color measurement system, online multi spectral color measurement system for map printing, etc.

特殊地,单张多光谱颜色测量系统可以输出产品全幅面任意区域的光谱反射率数据,并进行光谱的对比与判定;印刷在线多光谱颜色测量系统可对印刷产品色相进行实时检测并反馈数据,色相差异达到预警值即发出声光报警警示,确保目标印刷色相与标准样同谱。

In particular, the single multispectral color measurement system can output the spectral reflectance data of any area of the whole breadth of the product, and carry out spectral comparison and judgment; the printing online multispectral color measurement system can carry out real-time detection of the color phase of the printed product and feed back the data. When the color difference reaches the early warning value, it will send out an audible and visual alarm warning to ensure that the target printing color phase and the standard sample are the same spectrum.

4.细节控制

4. Detail control

(1)油墨黏度控制。油墨作为色相管控的关键环节,印刷过程应遵循“少量、多次、计量”的原则添加油墨及溶剂,保证油墨中的色含量与色浓度。另外,应严格规定黏度测量频次,做到定时测量(如20分钟一次),若印刷设备已加装黏度自动控制系统,应对其检测准确性进行复核、校正,确保黏度测量的准确性与稳定性。

(1) Ink viscosity control. As the key link of color control, ink and solvent should be added in the printing process in accordance with the principle of "small amount, multiple times and measurement" to ensure the color content and color concentration in the ink. In addition, the frequency of viscosity measurement shall be strictly specified to achieve timing measurement (such as once every 20 minutes). If the printing equipment has been equipped with automatic viscosity control system, its detection accuracy shall be rechecked and corrected to ensure the accuracy and stability of viscosity measurement.

(2)根据印版印次数据,建立动态色相标准。凹印遵循“浅墨深印,深墨浅印”原理,要还原相同的色相效果,不同深度的凹版网穴应配套不同的油墨色相。实际生产过程中,应针对不同凹版网穴深度状态(凹版正常磨损过程)形成油墨色相数据或样品,在批量生产前,通过对照动态色相标准数据或印样,对油墨进行预调,减少印刷生产前的调色次数及调色过程造成的不合格品,提高生产效率。

(2) According to the data of plate printing times, the dynamic color standard is established. Gravure printing follows the principle of "light ink deep printing, deep ink shallow printing". In order to restore the same color effect, different depth of gravure mesh should be matched with different ink color. In the actual production process, ink color data or samples should be formed according to different intaglio mesh depth states (normal intaglio wear process). Before batch production, the ink should be pre adjusted by comparing the dynamic color standard data or printing samples, so as to reduce the number of color matching before printing and the unqualified products caused by color matching process and improve the production efficiency.

(3)特殊纸张印刷色序的确定。特殊纸张印刷生产前应根据原纸亮度值或色相深浅对纸张进行分选,确认印刷色序。一般地,按照“先暗后亮,先深后浅”的原则进行印刷,印刷油墨则先浅后深,方便印刷过程油墨调色,减少调色量与次数。

(3) Determination of color sequence of special paper printing. Before special paper printing production, paper shall be sorted according to brightness value or color shade of base paper to confirm printing color sequence. Generally, printing is carried out according to the principle of "first dark and then bright, first deep and then light", and printing ink is first light and then deep, which is convenient for ink color matching in the printing process and reduces the amount and times of color matching.

(4)检测设备管理与数据分析。色差作为印刷过程关键质量指标,色相检测设备应定期(每年/半年)进行周期检定、校正;日常使用过程中,应建立自检校正要求,每8小时或12小时进行自校(标准板校正),通过测量标准样等形式确保检测设备保持在正常使用状态。

(4) Test equipment management and data analysis. As the key quality index of printing process, the color difference detection equipment shall be periodically verified and corrected (every year / half a year); during daily use, self inspection and correction requirements shall be established, self calibration (standard plate correction) shall be carried out every 8 hours or 12 hours, and the detection equipment shall be kept in normal use by measuring standard samples and other forms.

另外,印刷企业应根据各项质量指标及检测设备特性,制定专项比对计划,定期对自身各系列牌号检测设备、客户检测设备进行比对试验,以客户建立的检测标准和实际检测数据为依据,确定各台检测设备之间的台间差,并对企业自身检测设备进行有效地修正处理,落实到色差值中的ΔL*、Δa*、Δb*及不同波段光谱反射率数据,真实地反映检测数据,有效指导生产。

In addition, the printing enterprise shall make a special comparison plan according to various quality indexes and characteristics of testing equipment, regularly carry out comparison tests on its own series of brand testing equipment and customer testing equipment, determine the difference between each testing equipment based on the testing standards established by the customer and the actual testing data, and effectively modify and process the testing equipment of the enterprise itself The spectral reflectance data of Δ L *, Δ a *, Δ b * and different wavebands in the chromatic aberration value can truly reflect the detection data and effectively guide the production.

综上所述,本文由山东印刷包装友情奉献,印刷色相管控是印刷企业质量控制的关键指标,如何结合企业实际形成一套系统的管控措施至关重要。随着行业技术持续创新发展,先进的管控技术、检测设备、检测方法层出不穷,让我们拭目以待,。

To sum up, this paper is dedicated by Shandong printing packaging, printing color control is the key index of printing enterprise quality control, how to form a set of systematic control measures based on the actual situation of the enterprise is very important. With the continuous innovation and development of industry technology, advanced management and control technology, testing equipment, testing methods emerge in endlessly, let's wait and see,.


 
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