In the binding process, at present commonly used adhesive, EVA adhesives PVA glue adhesion agent and PUR glue adhesion agent.Among them, about PUR adhesives originated in the 1980 s, because has the advantages of good book reading out flat, once pushed wide praise market, has been increasingly applied to the plastic loaded magazines, brochures, etc.
As a new type of material, PUR adhesives in use process need to pay attention to the following matters.
1. The thickness of the coating
The PUR adhesives coating thickness thin than traditional EVA adhesives, recommendation is 0.4 mm, and should be coated uniformly.
2. The belt length is set
If the connection operation and the book is thick, adhere to in order to prevent deformation of the spine and avoid adhesives on the cutting knife, need to configure the conveyor belt, long enough to ensure that the adhesive curing time.When the choose and buy equipment, it must be taken into account.Usually in PUR glue, from the coating to the three sides and cutting knife time must be controlled in 3.5 minutes.
3. The operating temperature
Due to above 140 ℃, PUR adhesives can release toxic gases and isocyanate, stimulate the mucous membrane of the eye, nose and throat, causing symptoms such as headache, so need to control the working temperature below 140 ℃, also need to install local exhaust system in heating position, to accelerate the diffusion of gases.
4. The adhesive storage conditions
Should be stored in the PUR adhesives in confined Spaces without light, and it is prohibited to contact steam, water and alcohol solvent, lest produce irreversible crosslinking curing reaction.Under the condition of the original packing PUR adhesives can store 1 year not metamorphism, open after use can be stored in a closed space within 3 months or so, but I still suggest that run out as soon as possible.
5. Print placement
Using PUR glue after books, in a short period of time to should take put down gently, because at that time has not fully curing PUR adhesives.
6. Adhesive replacement
When changing the PUR adhesives, need to comply with certain operational specification: replace former PUR adhesives, must first make PUR glue device heating plate and barrel from PUR adhesives;Out, into the air pressure should be from small to large, in order to avoid accidents, under any circumstances do not allow the use of high pressure gas directly to take off the barrel, and the burst pressure should avoid to use without dry compressed air, it is best to use dry nitrogen;From after, before more than clear PUR adhesives glue, must through the PUR glue on the pressure plate device special institutions, closing the passage between the pressure plate and the pump body, prevent curing PUR adhesives;In cleaning up hot plate when the remaining PUR adhesives, cannot use any hard tool, in order to avoid the scratch, teflon coating;Hot plate after cleaned up, press the pressure plate shall be immediately into the new barrels of PUR adhesives, avoid let pressure plate, exposed to air for a long time, now the pressure of the cylinder size should be from small to large, may not directly use the high pressure gas, prevent accidents;After changing the PUR adhesives, must stay behind the PUR glue heating device for at least 20 minutes to start the pump and motor, such as immediately start the pump and motor can damage the gear pump, lower the service life of PUR binding equipment. (Gold Printing Group) |
