BY ADHESIVE

Field

The present disclosure relates to a process for producing an adhesive for joining two or more parts and a process capable of joining, in an efficient manner, two or more parts with complicated and/or irregular shapes. Background

Joining parts using adhesive is a highly explored technical field. In the automotive industry, for example, it is common to use adhesives to join glass parts to the chassis of an automobile, meeting an esthetic and structural manufacturing need. One of the known methods for bonding parts comprises an adhesive process with polyurethane. The polyurethane, also known as PU, is a polymer that consists of a chain of organic units joined by urethane links, also known as carbamate.

Polyurethane adhesives are widely used to join parts with complicated and/or irregular shapes and with large thickness gaps, due to their simple application process and their capacity to fill the empty spaces originating from the differences in shape of the parts and the gaps present in a structure.

The rheology of the adhesive allows a perfect copy of the shape using the very structure as pre-mold. Therefore, one of the known applications of this kind of adhesive is the joining of glass in the automotive industry, where the adhesive is applied in the structure of the car copying the perimeter of the window where the glass will be fixed.

Besides the molding facility on the structure itself, the polyurethane adhesive also fills the gap between the chassis of the car and the glass window, such that after curing, the window is completely fixed to the chassis and the cured adhesive fills any gap between it and the window.

Although polyurethane adhesives have proven to be an efficient way of fixing parts in the automobile industry, there are drawbacks associated to their use, principally concerning their application and cure time. For example, the process of applying a polyurethane adhesive is not easy and requires special care to avoid sullying the parts to be joined with consequent low productivity. Moreover, the process causes material waste, since no prior mold is made with the exact quantity of adhesive needed for fixing. Lastly, the curing of polyurethane adhesive is a lengthy process, which may take hours, and must be performed carefully, preventing work with joined parts; additionally, it is necessary to prevent the adhesive from curing on the application device, by way of a device cleaning procedure to remove residual adhesive. Said procedure adversely impacts the efficiency of this process.

Another type of adhesive used in joining parts is acrylic foam tape, also known by the abbreviation AFT. AFT is a double-coated tape that combines acrylic adhesives with viscoelastic foam nuclei.

In the automotive industry, AFT tapes are used in a variety of applications where the contours of the surfaces to be joined do not perfectly match. In these applications, the viscoelastic foam of the AFT tapes is desirable to offset the imperfections in matching. The process of joining by AFT generally involves the following steps: the tape is unraveled from a tape bobbin, then the unraveled tape is pressed on the surface of one of the parts to be joined; after adhesion with the first part, the coating of the other face of the tape is withdrawn, and the other part to be joined is pressed against the other face of the tape.

Among the drawbacks of joining by AFT are: the thickness of the filling of the gap between parts, which is generally limited by the reduced thickness of the tape; the formation of wrinkles and irregularities on the surface of the tape when it is used for joining parts with complicated and irregular shapes - once formed, the wrinkles on the surface hamper the adhesion of parts by the reduction of the contact area; the presence of at least one junction on the adhesive surface, at the point where application of the tap begins and concludes, having the potential to cause faults in the sealing between the two parts. Besides these drawbacks, the process of joining by AFT may cause great waste of material, since certain part shapes may require cutting and removal of a central area of the tap before its application. There exists a need for a process of joining parts by adhesive that eliminates the drawbacks found in known processes, carrying out the fixing in a simple and clean manner without wasting material. There also exists a need for a process of manufacturing, in a simple, economic and efficient manner, an adhesive that may be used to join parts with complicated and/or irregular shapes and with gaps and/or thick spaces between them.

Summary

The present disclosure provides a process of manufacturing an adhesive for joining two or more parts, the adhesive enabling more efficient and faster joining of the parts. The present disclosure also provides a manufacturing process using an adhesive for joining two or more parts where the adhesive fills gaps between the parts. The present disclosure further provides a process for manufacturing an adhesive for joining two or more parts, where the adhesive develops its adhesion properties rapidly without the need for a long curing time. The present disclosure also provides a process of joining parts having complicated and/or irregular shapes and/or contact gap that is performed in a clean manner, without contamination by dirt or impurities. The present disclosure provides a process of joining parts having complicated and/or irregular shapes and contact gap that presents low material wastage. The present disclosure also provides a process of joining parts with complicated and/or irregular shapes and contact gap that presents a continuous adhesive surface.

The present disclosure achieves the above objectives by way of a process for manufacturing an adhesive for joining two or more parts that comprises:

producing a pre-mold that defines desired dimensions and shape for an adhesive,

filling the pre-mold with a transparent acrylic adhesive;

polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber; and

removing the pre-mold.

In some embodiments of the present disclosure, the pre-mold is made of silicon rubber and the transparent acrylic adhesive comprises a photopolymerizable transparent acrylic syrup. In some embodiments, the ultraviolet ray chamber undergoes an elimination of oxygen prior to polymerization. In an exemplary embodiment, elimination of the oxygen present in the chamber is conducted by filling the chamber with nitrogen gas. The present disclosure also includes a process for joining two or more parts by an adhesive that comprises:

producing a pre-mold that defines desired dimensions and shape for an adhesive,

filling the pre-mold with a transparent acrylic adhesive;

polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber;

removing the pre-mold;

adhering the transparent acrylic adhesive to a first of the parts to be joined; and

adhering the second part to be joined to the transparent acrylic adhesive.

In some embodiments of the present disclosure, the adhesion of the transparent acrylic adhesive to a first of the parts to be joined occurs after the step of polymerizing the transparent acrylic adhesive, filled in the pre-mold on the first part to be adhered. In some embodiments, the adhesion of the transparent acrylic adhesive to a first of the parts to be joined occurs after its polymerization on an intermediary surface and the removal of the mold. In some embodiments of the present disclosure, the pre-mold is made of silicon rubber and the transparent acrylic adhesive comprises a photopolymerizable transparent acrylic syrup. In some embodiments, the ultraviolet ray chamber undergoes an elimination of oxygen prior to polymerization. For example, elimination of the oxygen present in the chamber can be accomplished by filling the chamber with nitrogen gas. Brief Description of the Drawings

Figure 1 - Figure 1 illustrates an exemplary embodiment of a pre-mold used in the processes of the present disclosure.

Figure 2 - Figure 2 illustrates an exemplary embodiment of a pre-mold used in the processes of the present disclosure.

Detailed Description

The present disclosure solves the drawbacks of the prior art by way of a process of manufacturing an adhesive for joining two or more parts that comprises the following steps:

a) producing a pre-mold that defines desired dimensions and shape for an adhesive, b) filling the pre-mold with a transparent acrylic adhesive;

c) polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber; and d) removing the pre-mold.

The present disclosure also comprises a process of joining two or more parts by an adhesive that comprises the following steps:

a) producing a pre-mold that defines desired dimensions and shape for an adhesive, b) filling the pre-mold with a transparent acrylic adhesive;

c) polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber;

d) removing the pre-mold;

e) adhering the transparent acrylic adhesive to a first of the parts to be joined; and f) adhering the transparent acrylic adhesive to a second part to be joined.

The adhesion of the transparent acrylic adhesive to a first of the parts to be joined can be done at different times in the process. For example, in some embodiments, the pre-mold, after its manufacturing (step a), is positioned on the first of the parts to be joined (step e). After positioning the pre-mold, there occurs the filling thereof, the polymerization of the transparent acrylic adhesive and the removal of the pre-mold (steps b, c and d). After removal of the pre-mold, the second part to be joined is adhered to the transparent acrylic adhesive (step f).

In some embodiments, steps a) to d) occur consecutively, and after removal of the pre-mold, the cured (or polymerized) transparent acrylic adhesive is adhered to the first of the parts to be joined (step e), and then the second part to be joined is adhered to the transparent acrylic adhesive (step f).

The pre-mold is shaped so as to define a volume and a dimension of the transparent acrylic adhesive which will be used in the process. Figure 1 shows a first pre-mold exemplary embodiment where the pre- mold 1 is a silicon rubber pre-mold with a rectangular filling free part (central part) of approximately 100 mm in length, by 10 mm in width and 7 mm in height. Figure 2 shows a first pre-mold exemplary embodiment where the pre-mold 1 is a silicon rubber pre-mold and has a triangular shape to match the triangular shape of the edges of a glass window 2 of an automobile. Although in the preferred embodiment of the present disclosure, the pre-mold is made of silicon rubber, any material could be used, provided that it allowed the correct removal of the pre-mold after curing, preventing the adhesion of the transparent acrylic adhesive to the pre-mold surfaces.

In the some embodiments of the present disclosure, the transparent acrylic adhesive, which will be dispensed on the pre-mold, is a photopolymerizable transparent acrylic syrup. Curing the transparent acrylic adhesive involves the passage of the pre-mold through an ultraviolet ray chamber so that the acrylic adhesive is polymerized. The acrylic adhesive is preferably transparent to allow UV rays to reach all the monomers so that complete polymerization is achieved.

In some embodiments of the present disclosure, the UV chamber is preferably sized to be 120mm in height, 1000mm in width and 780mm in length and is composed of 14 UV lamps of 30W. So that complete polymerization of the transparent acrylic adhesive is achieved, it is desirable to eliminate the oxygen inside the chamber. Hence, in some embodiments, the chamber is filled with nitrogen gas, preferably with nitrogen gas having a purity of 99.999%.

The curing time in the chamber varies according to the dimensions of the pre-mold. For the transparent acrylic adhesive for the exemplary pre-mold shown in Figure 2, the curing time is approximately 10 min. After the step of curing (or polymerization), the transparent acrylic adhesive is very near to solid state, and the cured adhesive "copies" the shape of the filling part of the pre-mold. As the adhesive is previously designed and shaped exactly for the desired joining process to be carried out, material waste and trash are eliminated. Additionally, the process of manufacturing the adhesive described herein allows a large width adhesive to be obtained, which manages to fill the gaps of over 10mm between the parts.

Exemplary embodiments and combinations of embodiments include at least the following: 1. Process for manufacturing an adhesive for joining two or more parts comprising the following steps: a) producing a pre-mold that defines desired dimensions and shape for an adhesive,

b) filling the pre-mold with a transparent acrylic adhesive; c) polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber; and d) removing the pre-mold.

2. Process for manufacturing an adhesive, according to claim 1, wherein the pre-mold is made of silicon rubber.

3. Process for manufacturing an adhesive, according to any of the previous claims, wherein the transparent acrylic adhesive comprises a photopolymerizable transparent acrylic syrup. 4. Process for manufacturing an adhesive, according to any of the preceding claims, further comprising, prior to step c) polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber, an additional step for eliminating oxygen present in the chamber.

5. Process for manufacturing an adhesive, according to claim 4, wherein the additional step for eliminating oxygen present in the chamber comprises filling the chamber with nitrogen gas.

6. Process for joining two or more parts by an adhesive comprising the following steps:

a) producing a pre-mold that defines desired dimensions and shape for an adhesive,

b) filling the pre-mold with a transparent acrylic adhesive;

c) polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber;

d) removal of the pre-mold;

e) adhering the transparent acrylic adhesive to a first of the parts to be joined; and

f) adhering the second part to be joined to the transparent acrylic adhesive. 7. Process for joining two or more parts, according to claim 6, wherein step e) of adhering the transparent acrylic adhesive to a first of the parts to be joined further comprises positioning the pre-mold on the first of the parts to be joined before carrying out steps b) to d).

8. Process for joining two or more parts, according to claim 6, wherein step e) of adhering the transparent acrylic adhesive to a first of the parts to be joined and step f) of adhering the second part to be joined to the transparent acrylic adhesive occur consecutively after carrying out steps b) to d).

9. Process for joining two or more parts, according to any of claims 6 to 8, wherein the pre-mold is made of silicon rubber.

10. Process for joining two or more parts, according to any of claims 6 to 9, wherein the transparent acrylic adhesive comprises a photopolymerizable transparent acrylic syrup. 11. Process for joining two or more parts, according to any of claims 6 to 10, further comprising, prior to the step of polymerizing the transparent acrylic adhesive in an ultraviolet ray chamber, an additional step of eliminating oxygen present in the chamber.

12. Process for joining two or more parts, according to claim 11, wherein the additional step of eliminating the oxygen present in the chamber further comprises filling the chamber with nitrogen gas.

The description provided above refers only to possible embodiments for processes of the present disclosure. The scope of the subject matter of the disclosure is further defined in the following claims.