I. Effects on thin film materials and matters needing attention:
1. Improper storage and storage of film and ink after entering winter will bring some influence on the printing and compounding of film.For example, when printing, there will be some problems such as uneven coloring of the light screen plate and poor firmness of the field pictures and texts.In the case of composite, the glue is not even, the composite strength is poor, and the cooking bag made at high temperature is easy to break.The temperature of the raw material storage warehouse should be kept at around 20 ℃.
2. The fast drying solvent of the shallow mesh dries faster, causing blocking plate, and ink granulation causes knife line;The dry solvent of deep network is more slow, which leads to the anti - adhesion roller and anti - adhesion.
3 after printing, the printing film, such as the best indoor in curing were not immediately composite insulation, generally between 30 ℃ and 40 ℃ temperature.Maintain a certain temperature, improve the fluidity and dispersion of the glue, improve the volatile solvent.
4. Before the composite coating, such as PE, PP and aluminum plating, the curing room should also be kept at a constant temperature to improve the film's own temperature and increase the affinity between the two membranes.
II. Influence on ink and solvent and matters needing attention:
1. The temperature is relatively low in winter, and ink thickening is often caused by too low temperature.Ink too thick, viscosity is also large, but it is best not to use thinner or ink oil to adjust its viscosity.So as not to weaken the basic performance of the ink, affect the printing quality.
2. Due to the temperature reduction in the workshop and the warehouse, ink and adhesive have a poor fluidity. As a result, the number of bubbles in printing composites will lead to the low temperature of products with white flower points, and the color of tone and composite colors will become worse.
3. Especially when the humidity drops below 40%, a large amount of static electricity will be generated in the workshop. The static electricity will cause the dry version and the static electricity will reject the white around the font, thus making it shallow or empty.Irregular piebald spots, white spots in shallow mesh;Hard winding and poor opening,
4. Under different temperatures, the latent heat of vaporization of solvent is different. The lower the temperature, the harder the liquid will be vaporized.During the printing process, proper control of machine speed, increase drying temperature, promote the volatile solvent, reduce the amount of residue in the film.
5, the solvent used must reach the national standard, if not reach the requirement of national standard, the other solvent in solvent or water paint, such as ethyl ester water cut will affect the dissolving ability of glue, dispersion is bad, when water molecules through the oven bake steam to run not to come out, adsorption on the printed film, after compound produced bubbles, light threshold of approximate phenomenon.Therefore, the use of solvents in winter must require suppliers to achieve national standard class I products.
III. Influence on compound process and matters needing attention:
1. Adjustment of glue preparation:
When preparing glue in winter, it is best to keep the adhesive and curing agent together in a high room temperature or curing room for a period of time, and then use the mixture.In preparation, the adhesive and curing agent are first added to appropriate amount of ethyl ester, and then the curing agent is added to the adhesive after being lightly stirred for half an hour. After stirring evenly, the curing agent is put into the adhesive groove for use, which will further improve the fluidity of the glue.
2. Effects on initial adhesion at the time of recombination:
In winter, when the temperature is low, the initial viscosity of the adhesive decreases. When the PE composite film is peeled, it is often removed from the interface between the adhesive layer and PE film. Moreover, the adhesion force is very small, and the adhesive has not yet completely wet the surface of PE film.Preheat PE film when rolling.Pay attention to the raw material storage environment temperature should not be too low.
3. Influence on fluidity of adhesive:
Pay attention to the influence of temperature on viscosity. The viscosity of adhesive increases with the decrease of ambient temperature.In winter, the viscosity of adhesive increases due to the low temperature and the same working concentration, which will directly lead to the poor leveling property of adhesive.
4. Control the amount of adhesive coating, the Angle of scraper and the combining ability of network roller to control the amount of adhesive coating and the evenness of coating.And in time to clean the network roller, to prevent the network roller blocking phenomenon.Bake, temperature 5 ℃ to 10 ℃ higher than the summer.
5. In winter, when the temperature is low, the hardness and hardness of the cots will change, resulting in hard and brittle phenomenon. In winter, the pressure of the cots should increase.As the temperature decreases, the hardness of the cots will increase by 2~5 shaoshi degree. The pressure of the roller should be increased appropriately when printing compound. If the hardness of the original cots exceeds 80 degrees, relatively soft cots should be replaced so as not to affect the product effect.
1. Influence on curing process of composite film:
The effect of low temperature in winter on the curing degree of the composite film is shown as follows.When the situation is not too serious, the composite membrane of the core will appear delamination after boiling and cooking.Therefore, in winter production, soft packaging enterprises should pay attention to the different curing effects of different parts of the same film roll.Extend the ripening time properly and control the temperature of the cooling roller.
2. Packaging bags are easy to be damaged:
Winter low temperature environment structure of BOPP/CPP composite bags in material and process parameters are almost the same, after the bag sealing brittle, and the sealing strength to drop, mainly because the stretch film of polypropylene film cold resistance is poorer, when the environment temperature is 10 ℃ have certain brittleness.