Sovg'a qutisini chop etishda kartonning namlik o'zgarishining ta'siri

Sovg'a qutisini chop etishda kartonning namlik o'zgarishining ta'siri

Hozirgi vaqtda oq karton qog'oz va oq karton barcha turdagi qadoqlashlarda keng qo'llanilgan va mijozlar mahsulot sifatiga yuqori va yuqori talablarga ega. Qadoqlash va poligrafiya sanoati oldida turgan yangi muammolar.

Qog'ozning namligi va muvozanat namligi

The moisture content of paper has a great influence on printing. If the moisture content is too low, the paper will become brittle, and static electricity is easily generated during printing; if the content is too high, it will be difficult for the ink to dry. The change of moisture also has a great influence on various properties of paper. With the change of moisture, its quantitative, tensile strength, flexibility, and folding endurance will change, and the size of the paper will also expand and contract, and even curl and warp. Edges, wrinkling, ruffles, etc. All kinds of paper have an optimum moisture content value. Under this value, the various properties of the paper are in a good state. The optimum moisture content of cast-coated paper and cast-coated white board is 7 percent ± 2 percent . White cardboard It is 4 percent -7 percent , and the single-sided coated white cardboard is 8 percent ±2 percent . This is the moisture content of the paper when it leaves the factory.

Bosmaxonada saqlash vaqtida qog‘oz gigroskopik material sifatida havodan namlikni havoning nisbiy namligi va haroratiga bog‘liq bo‘lgan tezlikda o‘zlashtira oladi; shuningdek, namlikni havoga o'tkazishi va qog'ozning namligi va atrof-muhit harorati va namligiga bog'liq bo'lgan tezlikda namlikni yo'qotishi mumkin. Namlikni yutish darajasi va suvni yo'qotish tezligi bir xil bo'lsa, qog'oz va havo muvozanatda bo'ladi va qog'ozdagi suv miqdori o'zgarishsiz qoladi. Bunda qog'ozning namligi muvozanat namligi deyiladi.

Nisbiy namlik deb ataladigan-ma'lum bir haroratdagi havo namligining havo shu haroratda to'yinganida ushlab turishi mumkin bo'lgan namlik miqdoriga nisbati tushuniladi. Xuddi shu qog'oz har xil nisbiy namlik ostida turli namlik balansiga ega.

Bundan tashqari, muvozanat namligidagi o'zgarishlar quyidagi xususiyatlarga ega:

① Affected by the nature of the paper. Under the same relative humidity, the more hydrophilic the paper, the higher the equilibrium moisture; otherwise, the lower. The paper without excipients has a higher equilibrium moisture, while the paper with fillers, sizing and coating has a lower equilibrium moisture. For the same variety, the balance moisture of thick products is higher than that of thin products, because the ratio of base paper rich in water absorption is high in thick products.

② Affected by temperature. Under the same relative humidity, when the temperature changes by about 15 degree , the maximum change in the equilibrium moisture of the paper is about 0.5 percent . However, overprinting during printing requires the control of the moisture content of the paper within ±0.1 percent , otherwise the accuracy of overprinting will be affected. Therefore, the color printing workshop should control the temperature change within ±3 degree while controlling the relative humidity.

③ It is affected by the itinerary to achieve equilibrium - moisture absorption or dehumidification. Under a certain relative humidity, the moisture content of paper when it reaches equilibrium by low moisture absorption is lower than that when it reaches equilibrium by high moisture dehumidification under the same relative humidity. This is the moisture absorption hysteresis effect of paper. In order to make the moisture content of the paper consistent with the original, it is necessary to take an "overkill" approach. That is to say, the paper that reaches equilibrium under a certain relative humidity must be placed in an environment with a lower relative humidity than the original relative humidity if it is to be dehumidified to achieve the original equilibrium moisture after absorbing moisture in a high-humidity environment, and vice versa. In addition, the speed of moisture absorption and dehumidification is also different, and the dehumidification speed is much slower. But regardless of moisture absorption or dehumidification, the starting speed is relatively fast, and the closer it is to equilibrium, the slower it is. This process is also related to paper quality and air mobility. Under standard humidity and temperature, a single cigarette paper can reach 5.8 percent equilibrium moisture after 35min treatment; various printing papers need 2-4h to reach 5 percent -8 percent equilibrium moisture; packaging cardboard takes longer . The hysteresis between the relative humidity change and the paper moisture content change will bring about a hysteresis effect between the paper deformation and the relative humidity change.

④ It is affected by the orientation of the paper. The so-called directionality means that the equilibrium moisture of the paper is inconsistent in the longitudinal and transverse directions, and the transverse expansion rate is much larger than the longitudinal expansion rate. Therefore, the transverse expansion and contraction of the paper is larger than that in the longitudinal direction. Tests show that the expansion and contraction of a single fiber in the transverse direction is equivalent to about 20 times that in the longitudinal direction. However, the arrangement directions of the fibers inside the paper are various, but the number of fibers arranged in the longitudinal direction is usually more. Therefore, the difference between the vertical and horizontal stretch ratios of the paper is not as large as the vertical and horizontal stretch of a single fiber. Taking the relative humidity from 50 percent to 60 percent as an example, the ratio of vertical and horizontal expansion and contraction is about 3:7, or about 2.3 times. This ratio varies according to the degree of orientation of the fibers, and the stronger the orientation, the larger the ratio. One of the key problems to reduce the horizontal stretch ratio and avoid the occurrence of inaccurate overprinting is to make paper with scattered and irregular fiber arrangement direction.

⑤ Affected by the two-sidedness of paper. A perfectly flat sheet of paper absorbs or dehumidifies in the air when its environment changes. If it is moisture absorption, the elongation of the reverse side is greater than that of the front side, and the paper will curl to the front side; if it is dehumidified, the shortening of the reverse side is greater than that of the front side, and the paper will curl to the reverse side. No matter which direction it is curled, it always takes the longitudinal direction of the paper as the axis, which is caused by the different degrees of orientation of the front and back sides of the paper. Cardboard, in particular, shows even more in this regard.

Karton namligining o'zgarishining bosib chiqarish sifatiga ta'siri

Chop etish qobiliyati qog'ozning namligida namoyon bo'ladi va odatda ishlab chiqarish muhitining nisbiy namligiga imkon qadar mos bo'lishi talab qilinadi. 200 g/m2 dan yuqori bo'lgan barcha turdagi kartonlar qog'oz ishlab chiqarish jarayonida ko'p qatlamli kompozit qog'oz ishlab chiqarish hisoblanadi va ularning ishlab chiqarish jarayoni talablariga muvofiq, ko'plab ishlab chiqaruvchilar qog'ozni qog'ozdan o'ralganidan keyin qog'ozni o'z vaqtida kesib, muhrlaydi, qadoqlaydi va qadoqlaydi. qog'oz mashinasi. Istalgan vaqtda aniq jo'natiladi. Ko'p qatlamli kompozit jarayon talablari tufayli kartonning namligi odatda oddiy qog'ozga nisbatan taxminan 5 foizga yuqori. Qog'ozning yuqori suv miqdori bosma uchun foydali bo'lsa-da, agar u to'g'ri saqlanmasa va foydalanilmasa, matbaa ishlab chiqarishiga juda ko'p muammolarni keltirib chiqaradi. Paket shikastlangan bo'lsa, paketdagi qog'ozning mahalliy namligi o'zgaradi, bu qog'ozning to'lqinli, qattiq qirralarning va bir tomoni baland va bir tomoni past bo'lishiga olib keladi; bosib chiqarish paytida qog'ozni oziqlantirish qiyin va siyoh va suv muvozanatini nazorat qilish qiyin. Noto'g'ri ko'p rang{5}}bosib chiqarish va boshqa sifat kamchiliklari, masalan, orqa burchakning tebranishi; ayniqsa, keyingi jarayonda qolipni kesish texnologiyasi-bo‘lgan mahsulotlar uchun qog‘ozning kengayishi va qisqarishi ham tartibsiz qolip yasash va noto‘g‘ri kesish-o‘lchamlari kabi muammolarni keltirib chiqaradi.

Shuning uchun, 200 g / m2 dan yuqori rangli quti o'rash qog'ozi uchun maxsus ishlab chiqarish amaliyotida quyidagi ikkita nuqta bajarilishi kerak:

1. Qog'ozni ilmiy va oqilona saqlang va saqlang. Kartonning o'ziga xosligini hisobga olgan holda, qog'ozni quritish yoki namlikni yutish va qog'ozning yaroqliligini o'zgartirishga yo'l qo'ymaslik uchun qog'ozni tashish va saqlash paytida mahsulotning qadoqlanishining yaxlitligiga katta e'tibor berilishi kerak, chunki mahsulot noto'g'ri bo'lganligi sababli qadoqlash shikastlanmasligi kerak. transport va ekspluatatsiya. Saqlashda ham shamollatish, ham yorug'lik va shamolga e'tibor berish kerak. Harorat 15-25 daraja, nisbiy namlik esa 40 foiz -65 foiz bo'lishi kerak. Qog'ozni yig'ish qog'oz ishlab chiqarish sanasi, mahsulot toifasi va ishlab chiqarish manzili bo'yicha tasniflanishi kerak va qog'oz keyingi jarayon uchun nisbatan barqaror qog'oz namligini ta'minlash uchun ishlab chiqarilgan sanaga muvofiq ketma-ketlikda berilishi kerak. iloji boricha.

2. Qog'oz namligining o'zgarishini samarali nazorat qilish. Agar kesishdan oldin uni to'g'ri saqlash va foydalanishni oqilona tashkil qilish juda zarur bo'lsa, kesishdan keyin harorat va namlikning o'zgarishi natijasida qog'oz hajmining o'zgarishini oldini olish uchun qanday choralar ko'rish kerak? Avvalo, ishlab chiqarish buyrug'i ilmiy va oqilona bo'lishi kerak va qog'oz erishishga intiladi Chop etish va kesish bilan, chop etishdan bir soat oldin qog'ozni tayyorlash yaxshidir. Katta hajmdagi narsalarni bir vaqtning o'zida ochish va kesish mumkin emas. Ular chop etish tezligi va jarayoniga qarab partiyalarga kesilishi kerak va kesilgan qog'oz havo bilan to'g'ridan-to'g'ri aloqa qilish vaqtini minimallashtirish uchun, ayniqsa, ko'p- rangli mahsulotlar bitta yoki ikkita{2}}rangli mashinada chop etiladi, bu usul yanada muhimroq. Namlikning o'zgarishi natijasida qog'ozning kengayishi va qisqarishi natijasida yuzaga keladigan ko'p rangli ortiqcha bosib chiqarish hodisasini oldini olish uchun chop etilgandan keyin nafaqat oq qog'ozga, balki har bir rangga ham xuddi shunday ishlov berish kerak. bosma mahsulotlar sifati.

Kalendrlashdan keyin karton namligining oʻzgarishining matritsa-kesish aniqligiga taʼsiri

Mahsulotning go'zalligini oshirish va rangli qutining sirtini yaxshilash uchun karton qadoqlashning 70% -80 foizini silliqlash va kalendarlash kerak. Yaltiroqlash deganda, bosma mahsulotning bosma mahsulot yuzasiga lak qatlami orqali laklangan yog 'roligi orqali bir tekis qoplanishi, so'ngra erituvchining qizdirilishi va quritilishi orqali yorqin qatlam hosil qilish uchun uchuvchanligi tushuniladi. Kalendrlash - bosma mahsulotlarni sirlash asosida qayta ishlash. 100-130 daraja yuqori harorat va taxminan 138kg / sm2 bosim bosilgan material yuzasida hosil bo'lgan yorqin qatlamni yanada ixcham va yorqinroq qiladi.

Due to this special process, the water content of the paper itself is seriously dehumidified in a short period of time, and the paper will inevitably shrink. The shrinkage amount is related to the structure of the paper and the size of the initial humidity. Although its shrinkage has nothing to do with printing overprint, it directly affects the precision of die-cutting. For example, the input size of a product manuscript is X, and the width is Y. If you print 5 pieces horizontally and 3 pieces vertically on a pair of K paper, you will get a product with a pattern size of 3Y5X after printing. After calendering After the paper pattern size shrinks, shrinking △X in the horizontal direction and △Y in the vertical direction, the die-cutting and shrinking products with the same size as the original will definitely have inaccurate die-cutting accuracy, and even embossing, Bleeding, the phenomenon that the pattern is not centered on the left and right. The customer is dissatisfied, and the product will be partially or completely scrapped, causing undue losses to the enterprise.

Xo'sh, qanday qilib aniq ishlab chiqarishda bunday xatolardan qochish yoki kamaytirish mumkin? Nisbatan oddiy usul - kalendarlashdan so'ng turli xil qog'ozlar va har xil qisqarish miqdori bo'yicha qoliplar (kesuvchi taxtalar)- yasashdir, lekin bu ko'pincha ishlab chiqarish jarayonini jiddiy kechiktiradi va kesish-qoliplangan o'lcham asl o'lchamidan kichikroq bo'lishi kerak. Shu maqsadda biz ushbu birlikda tez-tez ishlatiladigan turli qog'ozlarning namlik xususiyatlarini va kalendarlashdan keyin gorizontal va vertikal qisqarishni bosqichma-bosqich o'rganishimiz kerak va yakuniy qisqarishni amalga oshirish uchun chop etish paytida ushbu qisqarishni qo'lyozmaning kirish hajmiga qo'shishimiz kerak. Butun grafik o'lcham standart talablarga javob beradi, shuning uchun mahsulot sifati va aylanishini ta'minlash uchun -kesuvchi plastinka oldindan tayyorlanishi mumkin.

Sirlangan va kalendarlangandan keyin karton namligining o'zgarishining mahsulotning buklanish chidamliligiga ta'siri.

Folding resistance refers to the crease properties of the paper when the paper is folded without cracks on the surface of the folded belt, peeling of the fine seam coating, etc. It is usually used to indicate the toughness and surface strength of cardboard and cardboard under folding conditions. . From the paper itself, the folding endurance depends on the length, strength, flexibility and bonding force of fibers. A large part of my country's papermaking raw materials are non-wood raw materials, among which reed, wheat straw, straw, bagasse and other grass raw materials are used more. The paper produced from raw materials such as hemp, hemp, and wood has good toughness, while most grass raw materials have poor toughness after paper formation due to small fiber length and high content of hybrid cells.

Biz hozir ishlatadigan qog'oz. Qog'oz tegirmonlari odatda qog'ozning qattiqligini samarali yaxshilash uchun o't tolalarini yog'och tolalari bilan birlashtiradi. Biroq, yog'och xamirining turli nisbatlari, plomba moddalarining xususiyatlari va ishlab chiqarish jarayonlari tufayli turli qog'ozlarning qattiqligi bir-biridan farq qiladi va kalendarlash yuqori harorat va yuqori{1}}bosimli namlikni yo'qotish jarayonidir. qog'oz. Ildiz tolasi namlanish tufayli mo'rt bo'lib qoladi, tolaning siljish va stressni tarqatish qobiliyati sezilarli darajada kamayadi va katlama qarshiligi zaiflashadi, bu esa kartonni kesish jarayonida paxmoq, qobiq, yoriqlar va hokazolarni hosil qiladi; yelimlash, buklash. Buzilgan va chirigan kabi kamchiliklar va hatto mahsulotlarning butun partiyasini parchalanishiga olib keladi. Shuning uchun, maxsus ishlab chiqarish tartiblarida va mijozlar qog'ozni tanlaganda, qog'ozning ishlashiga va qog'ozning katlama chidamliligiga kalendarlashning ta'siriga alohida e'tibor berilishi kerak.

Umuman olganda, 250-380g oq-orqali oq doska va oq karton yaxshi buklanishga chidamliligiga ega va kalendarlash jarayonini hisobga olish mumkin; kulrang doskali qog'oz kalendrlash uchun mos emas. Bundan tashqari, qog'oz tolalarining o'ziga xos xususiyatlaridan kelib chiqqan holda, uzunlamasına yo'nalishda katlama chidamliligi ko'ndalang yo'nalishdagiga qaraganda yaxshiroq. Kartonning gorizontal va vertikal joylashishi va format hajmini hisoblashda bu omil to'liq hisobga olinishi kerak.

Barcha kalendrlangan mahsulotlar uchun kesishdan- oldin kalendrlangan qog'oz gorizontal va vertikal yo'nalishlarda buklanishga chidamliligi uchun sinovdan o'tkazilishi kerak. Suv, agar tsikl juda kech bo'lsa, namlikni tabiiy ravishda sozlash uchun namlikni yuqori bo'lgan joyga qo'yish mumkin, shunda qog'oz o'rtacha gigroskopik bo'lgandan keyin tolaning mustahkamligi va moslashuvchanligi kuchayadi va katlama qarshiligi yaxshilanadi, bu chiqindilar va yo'qotishlarni kamaytirishi mumkin.

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