Sealed letter

The invention relates to an envelope having a transparent layer, allowing printed information on the letter paper in the envelope to appear through the envelope. The inner surface of the transparent layer is laminated with a transparent, thermal adhering synthetic resin film to bind the transparent layer to a second layer along their periphery.

BACKGROUND OF THE INVENTION 
This invention relates to a sealed letter which is used chiefly for mailing 
a letter paper such as a bill, a notice or the like suitably printed by a 
printer without failing. 
As for a sealed letter of this kind, there has been hitherto known a type 
in which an address and any other necessary descriptive matters such as a 
sum of money or other correspondence items are printed out on 
predetermined portions of letter paper by a printer of a computer, and the 
resultant correspondence letter paper is folded and the peripheral 
portions of the folded one are adhered together to form a sealed letter. 
To adhere the peripheral portions of the folded letter paper together, the 
letter paper, in general, is so prepared, prior to being folded, that 
ruled lines or other necessary matters are printed by an offset duplicator 
at predetermined portions on the blank of paper and thereafter the 
resultant letter paper is coated at predetermined peripheral portions with 
a heat sensitive or pressure sensitive adhesive agent. The letter paper 
thus prepared as above is applied with the foregoing printing of the 
address and so on by the printer of the computer and thereafter is folded 
and the peripheral portions of the folded one are adhered together by 
applying the heat or pressure to the coating, resulting in a sealed 
letter. 
This conventional type of sealed letter involves various inconveniences as 
described below: 
Recently, among various types of printers, use of a thermal type one has 
been on the increase and a large quantity thereof are used, but if this 
thermal printer is used for the letter paper coated with the adhesive 
agent as mentioned above, the adhesive agent is heated to melt at the time 
of printing the necessary items on the letter paper to cause trouble to 
the printer such as blocking to printing. Further, it is necessary for the 
letter paper to provide for a margin to paste up for applying the adhesive 
agent thereto, so that the overlap width is not effective for a 
corresponding part of the letter paper. Furthermore, since the sealed 
letter is formed by folding and adhering the letter paper, the number of 
folding thereof is limited, and accordingly the sealed letter folded in 
four, for instance, is difficult to obtain. 
In addition, the letter paper is printed with feed holes for a printer on 
both side edges thereof, so that it is impossible to form the same into 
one having a series of separable sections as required for a letter paper 
having a series of separable printed forms, for statement of payment for 
instance. 
The object of this invention is to provide a sealed letter which is a 
combination of such letter paper without coating any adhesive agent 
thereon that is suitable for printing out necessary descriptive matters 
thereon even by a thermal printer without causing any trouble thereto and 
separate sealable covering sheets for enclosing the foregoing printed 
letter paper therein, so that the printed letter paper is foldable any 
desired number of times and also any additional sheet such as a printed 
matter or the like can be enclosed therein, and accordingly a large number 
of the sealed letters can be made in succession in conjunction with a 
computer. 
According to this invention, there is provided a sealed letter 
characterized in that letter paper on which an address and other 
descriptive matters are printed is covered, at its front surface, with a 
front sheet made of transparent paper laminated, at least at its rear 
surface, with a transparent and thermal adhering synthetic resin film, and 
is covered at its rear surface with a rear sheet made of any desired paper 
material, and the front sheet and the rear sheet are adhered together by 
heat at their peripheral portions to form an enclosed sealed portion. 
Next, the process for making the sealed letter of this invention and the 
effect thereof will be explained as follows: 
Any necessary matters of correspondence such as an address and a sum of 
money, for instance, or others are printed out on predetermined portions 
of a letter paper by a printer connected to a computer, and the resultant 
correspondence letter paper is so folded a desired number of times to form 
a folded paper of a predetermined size so that the address printed thereon 
may appear on the front or top surface of the folded paper. 
The folded letter paper is covered, at its front surface bearing the 
address printed thereon, with a front sheet made of transparent paper 
which is laminated, at its rear surface, with a transparent and thermal 
adhering synthetic resin film, and the folded letter paper is covered, at 
its rear surface, with a rear sheet made of any desired paper material, 
which may be the same material as the front sheet or ordinary paper such 
as kraft paper or the like, for instance, and the front sheet and the rear 
sheet are adhered together by heat at their peripheral portions to form an 
enclosed sealed envelope, so that a sealed letter is produced. 
With the sealed letter, the address of the letter paper can be read through 
the transparent front sheet, and the front sheet and the rear sheet are 
chiefly composed of paper material, so that the sealed letter never does 
lose its proper rigidity, and consequently can maintain its predetermined 
shape of the sealed letter, until broken manually by an addressee. 
Additionally, since the letter paper is not coated with a thermal adhering 
agent, a thermal printer can be free from any trouble hitherto caused by 
the adhesive agent, and the manner of folding the letter paper is a matter 
of discretion except the condition that the address has to appear on the 
front side, so that even a large-sized letter paper can be formed into a 
folded small-sized one such as a fourfold one or eightfold one, and thus a 
lot of information can be communicated by a sealed letter.

DETAILED DESCRIPTION OF THE INVENTION 
Embodying examples of this invention will now be explained with reference 
to the accompanying drawings: 
Referring to FIGS. 1-5 showing one embodying example thereof, numeral 1 
denotes a letter paper for a bill, for instance, formed by printing out 
necessary descriptive matters such as an address 2, amounts of money 3, 
and others filled in the predetermined blank portions thereof by a thermal 
printer arranged to be operated in conjunction with a computer, and the 
printed letter paper 1 in an unfolded condition shown in FIG. 3 is so 
folded in three that the address 2 may appear on its front side and the 
amounts of money 3 may be on its rear side, as shown in FIG. 4. 
This folded letter paper 1 is inserted, as shown in FIG. 5, between a pair 
of long front and rear sheets 4a, 4b drawn out from respective rolls (not 
illustrated) for being covered therewith at its front and rear surfaces, 
and is heated by a pair of heating rolls 5, 5. 
In this case, the front sheet 4a is made of transparent paper 9 such as 
glassine paper which is laminated, at its rear surface, with a transparent 
and thermal adhering synthetic resin film 10 such as of hot melt type 
resin, thermoplastic resin, etc., and the rear sheet 4b is made of 
transparent paper 11 which is laminated, at its front surface, with a 
transparent and thermal adhering synthetic resin film 12. 
Thus, by the foregoing heating operation, the synthetic resin films 10, 12 
at such peripheral portions of the front and rear sheets 4a, 4b that 
surround the folded letter paper 1 are adhered together by heat to form an 
enclosed sealed portion 6, and thus there can be produced a sealed letter 
8 as shown in FIG. 1. 
FIG. 6 and FIG. 8 show another embodying example. 
If, as shown in FIG. 8, the printed letter paper 1 is interposed between 
the front sheet 4a and the rear sheet 4b which are formed by folding a 
single long sheet in two, there is produced the sealed letter 8 of such a 
type that out of the peripheral four sides thereof one side is lacking in 
the sealed portion 6 as clearly shown in FIG. 6 and that the front sheet 
4a and the rear sheet 4b are made of the same materials 9 and 10. 
In any of the above embodying examples, a printed matter or the like can be 
enclosed together with the printed letter paper 1 in the enclosed sealed 
sheets 4a, 4b. 
The transparent paper 9 constituting the front sheet 4a is preferably made 
of glassine paper, so that characters or the like can be written thereon 
in water-color ink. 
The front sheet 4a may be modified so that the front surface of the 
transparent paper 9 thereof is also laminated with a transparent synthetic 
resin film 13, as shown in FIG. 9, so that a waterproof property thereof 
is improved and also the rigidity thereof is increased. Further, in this 
case, if the front synthetic resin film 13 is thicker than the rear 
synthetic resin film 10, breaking the sealed letter is facilitated. 
Numeral 14 is a stamp mark affixed onto the front surface of the letter 
paper 1. 
Instead thereof, the front sheet 4a itself may be previously affixed, by 
printing, with a stamp mark 14 or the like, as shown in FIG. 10. 
In another embodying example shown in FIG. 11, the rear sheet 4b is made of 
opaque ordinary paper 11a such as kraft paper, roll paper or the like, and 
in a further another embodying example shown in FIG. 12, the rear sheet 4b 
is formed of a lamination of an opaque paper 11a and a thermal adhering 
synthetic resin film 12a applied to a front surface of the paper 11a. 
In the latter case, the paper 11a may be applied also on its rear surface 
with a synthetic resin film 12b, as shown by a chain line in the same 
Figure. 
If the rear sheet 4b is opaque as shown in these examples, even when the 
printed letter paper 1 is folded so that the last section thereof 
including the correspondence contents may appear on its rear surface, as 
shown in FIG. 13, the rear surface thereof is covered with the rear sheet 
4b and cannot be seen from outside and therefore the last section of the 
printed letter paper can be utilized effectively for correspondence 
description. 
Referring to the drawings, numeral 15 denotes a folding line, and the 
folding line may be provided with perforations so that the letter paper 
may be formed of plural separable sections. 
Thus, according to this invention, letter paper on which an address and any 
other necessary matters are printed by a printer of a computer is covered, 
at its front surface, with front sheet made of transparent paper applied 
with a transparent and thermal adhering synthetic resin film, and is 
covered, at its rear surface,with a rear sheet made of any paper material, 
and the front sheet and the rear sheet are adhered together by heat at 
their peripheral portions so as to form a sealed letter, so that any 
coating of an adhesive agent on the letter paper can be eliminated, and 
consequently there can be removed such a trouble as disorder of a thermal 
printer caused by the adhesive agent. Additionally, the manner of folding 
the letter paper can be carried out in any manner provided that the 
printed address thereof should appear on the front surface. 
Additionally, for the front sheet and the rear sheet are made chiefly of 
paper material, the sealed letter can be easily broken for opening the 
same, and for the front sheet has the synthetic resin film, it can prevent 
the sealed letter from getting wet with rain or the like.