Process for producing an invisible and writable biaxially...

Details Process for producing an invisible and writable biaxially... Process for producing an invisible and writable biaxially...

1999-09-13

2001-12-25

Yao, Sam Chuan (Department: 1733)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C156S244170, C156S272600, C264S173150, C264S290200, C264SDIG007, C264S291000

Reexamination Certificate

active

06332940

ABSTRACT:

BACKGROUND
Nowadays, biaxially oriented polypropylene (hereinafter as BOPP ) transparent films used as substrate were treated by coating onto its surface to cause the transparent substrate matte, which can be finished by backing adhesive finish to obtain invisible and writable tape. This is the only producing method for the existing invisible and writable tape which is different from the conventional producing method of 3M (Minnesota Mining Manufacturing Company); As a whole, the cost of said conventional producing method is too high, due to an additional coating process and cost of raw material in coating agent and equipment needed, and some loss will occur during the coating process. So the application is limited and cannot be widely used in various usage. Hence the invisible and writable tape made from the raw film by this conventional method will cause abnormality due to the adhesive layer migrating into invisible and writable layer or cause to be unable for adhesion and writing because the invisible and writable layer and adhesive layer may delaminate after a certain period.
SUMMARY OF THE INVENTION
In view of the above description, the present invention is intended to obviate the problems mentioned in last paragraph and to provide a process for producing a three layers invisible and writable biaxially oriented polypropylene (BOPP) film of a thickness between 20 to 60 &mgr;m of the form of invisible and writable layer(
11
)/intermediate resin layer (
12
)/backing adhesive resin layer(
13
)(refer to FIG.
1
). The PP composition of PP resin and inorganic ingredients used for invisible and writable layer (
11
) is extruded by a twin screw secondary extruder with side feeding hopper. While the resin composition used for intermediate resin layer (
12
) and backing adhesive resin layer (
13
) are separately extruded by a twin screw primary extruder with side feeding hopper and a twin screw secondary extruder with side feeding hopper. The above-mentioned extrudates are co-flowed by a same T-die to co-extrude and form a three-layers coating sheet, and through cooling, biaxial orientation, corona treatment, and winding to form a three layers co-extrusion BOPP raw processing film of thickness 20-60 &mgr;m, which can be processed after matte finishing in the form of invisible and writable BOPP film.
The invisible and writable BOPP raw processing film obtained according to this invention are different whatever in processing quality and cost with that of conventional prior art, due to the specific process and composition used, and this make more incentives in the market, and can be widely used in the invisible and writable adhesive tape application. The merits can be shown as follows:
1. The invisible and writable layer can be obtained in BOPP process while no after coating treatment needed, it can reduce the production cost for market competence by saving the fee in equipment installation, ingredients, man-hour to handle material loss. These are not disclosed in the conventional prior art.
2. The inorganic powder used in the invisible and writable layer obtained by using three layers co-extrusion and biaxial orientation is good in its fixation, the bonding strength between this layer and intermediate layer also better than the bonding strength of coated layer made by conventional prior art and substrate. So the backing adhesive layer may not transfuse into the invisible and writable layer to cause delamination abnormality for a period after coating backing adhesive layer or the invisible and writable layer may not be separated by backing adhesive layer to become useless for writing and adhesion.
3. There is no need of drying zone in the coating process, it favors the heat shrinkage caused by the size reduction and the change of flatness in the film.
4. The invisible and writable layer can be obtained by a twin screw extruder with side feeding hopper, the inorganic powder can be fed into the side feeding hopper in the powder state without pre-forming it into master batch, this can largely reduce the production cost, Further the master batch of inorganic powder blended with resin can also be used in the single screw extruder only if by effectively raising the L/D(length/diameter) of the screw to reach uniform blending effect.


REFERENCES:
patent: 4716068, 19871200
patent: 5073452, 19911200
patent: 5552011, 19960900
patent: 6083443, 20000700
patent: 6086987, 20000700
patent: 6136439, 20001000

Affiliated with

Also associated with

Rating

Process for producing an invisible and writable biaxially... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing an invisible and writable biaxially..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing an invisible and writable biaxially... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2576387