Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
2003-05-16
2004-08-17
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyester
C428S041800, C428S532000, C428S213000, C428S215000, C427S339000, C427S384000
Reexamination Certificate
active
06777100
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface protective film for adhesive resin and process for producing the same, more particularly a surface protective film which can be easily peeled off from an adhesive resin film surface to which it is applied, free of a plasticizer or the like, which may have an adverse effect on adhesion of the adhesive resin itself, and having no adverse effect on thickness uniformity or surface flatness of the adhesive resin, and process for producing the same.
2. Description of the Prior Art
There are many types of adhesive resin, from low to high viscosity type. Considering adhesive agents, which are one of the representative applications of adhesive resin, the low-viscosity type is directly spread from a can, bottle, tube or the like onto an adhesion interface whereas the high-viscosity type is used as a hot melt after being heated, or as the so-called adhesive tape, where it is used while being supported by a base film.
Layered (sometimes referred to as sheet-shape) adhesive agents have been increasingly used with development of technology. A layered (sheet-shape) adhesive agent of hot melt type may be used as a product after being merely sprayed with a blocking inhibitor (inorganic powder of silica gel, zeolite, calcium carbide or the like) or laminated with a releasing paper put between the sheets, because the sheets are relatively not sticky to each other at room temperature. However, a layer (or sheet) of an adhesive agent viscous at room temperature is sticky to each other or another object around before it is applied to an intended object, and may not be saleable. As such, it is necessarily coated with a releasable surface protective film temporarily before being sold.
Therefore, when a layered (sheet-shape) adhesive agent of the above type is applied to an object, a releasable (temporarily adhesive) surface protective film is peeled off from the agent-containing laminate brought close to the object, and the exposed agent is quickly transferred to and bonded to the object. The resulting laminate is then pressed and/or heated, as required, to fast bond the adhesive to the object.
Layered (sheet-shape) adhesive agents are widely used in various industrial areas, e.g., electronic, medical, printing, machinery, optical device, ornament, jewelry, information device and clothing industries.
The adhesive resin layer with the surface kept exposed will be contaminated with dust, moisture or the like in air, which will degrade the object to which it is bonded. Therefore, it should be coated with a surface protective layer to be protected against such contaminants.
The surface protective films proposed so far include those of fluorine, polyethylene, polypropylene, polyimide, polyester, polyether, polyether sulfone, epoxy and phenol resin.
However, the surface protective films of these resins involve various problems, as described below.
For example, a fluorine-based film, although good in releasability, involves a problem of reduced adhesive strength of the adhesive resin layer to the object from which it is peeled off.
Each of a polyethylene and polypropylene resin sheet (synonymous with “film,” “layer” or the like), although low in cost, has a melting point lower than crosslinking temperature of the adhesive resin to cause a problem of deformed surface protective film itself with the result that the adhesive resin layer of constant thickness may be no longer formed.
A polyimide resin sheet, although very high in heat resistance and dimensional stability, involves problems of high cost and slightly low releasability from the adhesive resin layer.
A polyester resin sheet, represented by polyethyleneterephthalate (PET) sheet, although favorable in that it is free of fisheye or uneven thickness, involves a problem of poor releasability.
A polyether resin sheet involves problems of insufficient surface flatness, high cost and very poor releasability from the adhesive resin layer.
A polyether sulfone (sometimes referred to as PES) resin sheet has been used as a surface protective film most widely, because of its good releasability from the adhesive resin layer, but involves problems of high cost and possibly causing fisheye and uneven thickness to increase defective product yield.
An epoxy resin sheet is not used, because of its very poor releasability from the adhesive resin layer. A phenol resin sheet is also not used, because of its very poor flexibility.
The common releasing film (separator) is difficult to use as the surface protective film, because it is surface-treated with silicone for releasability, which causes problems similar to those associated with a fluorine-based film.
An adhesive resin layer, when heated at relatively high temperature for extended periods following the conventional procedure to improve its adhesive strength with an object, can deteriorate performance of the object to which it is to be bonded, because of high temperature to which the object is exposed. Therefore, an adhesive resin layer tends to be incorporated with an adhesion promoter. However, use of an adhesion promoter may cause problems of deteriorated releasability of the conventional surface protective film from the adhesive resin layer to obstruct the releasing works, and uneven thickness of the adhesive resin layer left by the surface protective film. These problems may cause difficulty in producing the product of high reliability.
Layered (sheet-shape) adhesive agents of various adhesive resins are widely used in various industrial areas, e.g., electronic device, medical, printing, machinery, optical device, ornament, jewelry, information device and clothing industries. Quality of the layered (sheet-shape) adhesive agent required by each area varies depending on the resin material and industrial area in which it is used. The common requirements in these areas are that the agent should not cause quality degradation resulting from transfer of plasticizer, oligomer, low-molecular-weight compound, solvent or the like from the surface protective layer, and that flatness of the adhesive agent surface and uniform thickness of the agent layer should not be prevented.
SUMMARY OF THE INVENTION
In consideration of the problems involved in the conventional techniques, it is an object of the present invention to provide a surface protective film for adhesive resin which can be easily peeled off from the resin surface to which it is applied, is free of a plasticizer or the like which may have an adverse effect on adhesion of the adhesive resin itself, and has no adverse effect on thickness uniformity or surface flatness of the adhesive resin.
The inventors of the present invention have found, after having made on a trial basis a variety of types of plastic films and plastic film laminates, and extensively conducted a number of tests to investigate releasability of the plastic films from an adhesive resin layer, and their effects on adhesion of the adhesive resin layer to the object to which it is applied and on thickness uniformity of the adhesive resin layer and its surface flatness, that a surface protective film comprising a base film coated, at least on one side, with a cellulose-based resin layer having a specific SP value (Solubility Parameter; determined by the Fedors method) gives good results, achieving the present invention.
The first aspect of the present invention provides a surface protective film for adhesive resin, comprising a base film (A) coated, at least on one side, with a cellulose-based resin layer (B) having an SP value of 21.0 to 29.0(MPa)
1/2
, determined by the Fedors method.
The second aspect of the present invention provides the surface protective film of the first aspect, wherein the cellulose-based resin layer (B) is of cellulose acetate having an acetylation degree of 47 to 63.
The third aspect of the present invention provides the surface protective film of the first aspect, wherein the base film (A) is a polyethyleneterephthalate film, and the base film (A) and cellulose-based resin layer (B
Omura Masaya
Sumita Katsuhiko
Armstrong Kratz Quintos Hanson & Brooks, LLP
Chen Vivian
Daicel Chemical Industries Ltd.
LandOfFree
Surface protective film for adhesive resin and process for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surface protective film for adhesive resin and process for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface protective film for adhesive resin and process for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3346052