Vehicle body part and method of forming a vehicle body part

Abstract

A vehicle body part including a support, an uncured sealer and an uncured primer, the uncured sealer being interposed between the support and the uncured primer, the uncured sealer and the uncured primer each including a compatible solvent, each compatible solvent having a log P.sub.ow value and an absolute value of a difference between the log P.sub.ow value of the compatible solvent of the uncured primer and the compatible solvent of the uncured sealer being equal to or smaller than 3.0. A method of forming a finished vehicle body part.

Claims

1. A vehicle body part comprising a support, an uncured sealer, and an uncured primer, wherein the vehicle body part is a door or a hood, the uncured sealer is interposed between the support and the uncured primer, the uncured sealer and the uncured primer each comprise a compatible solvent, each compatible solvent has a log P.sub.ow value, and an absolute value of a difference between the log P.sub.ow value of the compatible solvent of the uncured primer and the compatible solvent of the uncured sealer being equal to or smaller than 3.0; where the uncured sealer comprises 15-50 wt % of plasticizer, and the door or the hood has an opening, a strip of the uncured sealer being applied at the opening of the door or the hood to prevent water from entering into a finished vehicle that includes the door or the hood.

2. The vehicle body part according to claim 1, wherein the absolute value of the difference between the log P.sub.ow value of the compatible solvent of the uncured primer and the compatible solvent of the uncured sealer being equal to or smaller than 2.5.

3. The vehicle body part according to claim 2, wherein the absolute value of the difference between the log P.sub.ow value of the compatible solvent of the uncured primer and the compatible solvent of the uncured sealer being equal to or smaller than 2.0.

4. A method of forming a finished vehicle body part having a support comprising the steps of: applying an uncured sealer on the support; and applying an uncured primer on the uncured sealer, so as to form the vehicle body part according to claim 1.

5. The method according to claim 4, wherein after applying the uncured primer, a curing step is performed.

6. The method according to claim 4, wherein a cured electrodeposition coating has been applied on the support before applying the uncured sealer.

7. The method according to claim 4, comprising a step of applying a base coat.

8. The method according to 7, comprising a step of applying a clear coat on the base coat.

9. The method according to claim 7, wherein after applying the base coat, a curing step is performed.

10. The method according to claim 8, wherein after applying the clear coat, a curing step is performed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an exemplary vehicle body part with a sealer;

(2) FIG. 2 shows a cross-section of the exemplary vehicle body part with the sealer and a primer uncured taken along II-II of FIG. 1;

(3) FIG. 3 shows a cross-section of the exemplary finished vehicle body part taken along II-II of FIG. 1;

(4) FIG. 4 shows a block diagram illustrating an exemplary method according to embodiments of the present disclosure;

(5) FIGS. 5A and 5B show a vehicle body part after curing of the sealer and the primer; and

(6) FIG. 6 shows a test method for determining the compatibility of the solvent of the sealer with the primer.

DESCRIPTION OF THE EMBODIMENTS

(7) Reference will now be made in detail to exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

(8) FIG. 1 shows a representation of an exemplary vehicle body part according to embodiments of the present disclosure, in this example a door 10. The door 10 comprises an uncured sealer 12 applied to prevent water to enter the finished vehicle. As can be seen on FIG. 1, the uncured sealer 12 is applied close to the inner periphery of the door 10.

(9) FIG. 2 shows a cross-section of the exemplary vehicle body part 10 of FIG. 1 comprising a support 14 of the vehicle body part 10. The support 10 is typically made of metal, such as steel or aluminum. The support 14 is covered with a cured electrodeposition layer 16′ on which the uncured sealer 12 has been applied. The vehicle body part 10 also comprises an uncured primer 18 applied on the uncured sealer 12. Thus, the uncured sealer 12 is interposed between the support 14, through the cured electrodeposition layer 16′, and the uncured primer 18. Some of the uncured primer 18 is directly applied on the cured electrodeposition layer 16′, no uncured sealer being interposed between the support 14, through the cured electrodeposition layer 16′, and the uncured primer 18.

(10) FIG. 3 shows a cross-section of an exemplary finished vehicle body part 24 comprising the support 14, the cured electrodeposition layer 16′, the cured sealer 12′, the cured primer 18′, a cured base coat 20′ applied on the cured primer 18′ and a cured clear coat 22′ applied on the cured base coat 20′.

(11) An exemplary method of forming the finished vehicle body part 24 is as follows. At step 30, an electrodeposition layer is deposited on the support 14 and then cured to form the electrodeposition layer 16′. At step 32, the uncured sealer 12 is applied on the support 14 coated with the cured electrodeposition layer 16′. At step 34, the uncured primer 18 is applied on the support 14 coated with the cured electrodeposition layer 16′ and the uncured sealer 12. Thus, the uncured primer 18 is applied on both the uncured sealer 12 and the cured electrodeposition layer 16′. At step 36, a first curing step is performed, for example at temperature above 100° C., preferably at 140° C. for more than 10 min. (minutes) so as to cure the uncured sealer 12 and the uncured primer 18, forming a cured sealer 12′ and a cured primer 18′. Then, at step 38, an uncured base coat is applied and cured at step 40 so as to form a cured base coat 20′. At step 42, an uncured clear coat is applied over the cured base coat 20′ and cured at step 44 so as to form a cured clear coat 22′ and obtain the finished vehicle body part 24.

(12) It is to be understood that the curing steps 36, 40 and 44 may or not may be performed.

(13) As can be seen on FIG. 4, there is no curing step performed between steps 32 and 34.

(14) Typically, the uncured sealer 12 comprises a plasticizer, preferably 15-50 wt %, more preferably 25-35 wt %. It also comprises a compatible solvent 26, for example at around 4 wt %, as well as a filler, preferably 20-50 wt %, more preferably 30 to 40 wt %, such as calcium carbonate (CaCO.sub.3).

(15) Typically, the uncured primer 18 comprises mainly a resin, such as a polyester resin, a polyacrylic resin or a melamine resin. It also comprises a compatible solvent, additives such as surface control agent and/or rheology control agent, and pigments such as titanium oxide (TiO.sub.2) or carbon black. Examples of solvent are, but are not limited to, toluene, xylene, methanol, butanol, naphtha solvent, and mixture thereof.

(16) Thus, samples are made by applying a layer of plasticizer mixed with the compatible solvent of the plasticizer on a metallic plate coated with a cured electrodeposition layer 16′. Then, the primer is applied on the uncured plasticizer, let to rest at least 3 min., preferably at least 7 min., and then cured at 140° C. for 18 min.

(17) FIG. 5A is a test sample where the log P.sub.ow/primer value of the compatible solvent of the primer is equal to 3.0 and the log P.sub.ow/sealer value of the compatible solvent of the sealer is equal to 7.5. As can be seen, crawling of the primer on the sealer occurs.

(18) In the test sample of FIG. 5A, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is equal to 4.5. Thus, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is greater than 3.0.

(19) FIG. 5B is a test sample where the log P.sub.ow/primer value of the compatible solvent of the primer is equal to 3.0 and the log P.sub.ow/sealer value of the compatible solvent of the sealer is equal to 5.0. As can be seen on FIG. 5B, no crawling of the primer on the sealer occurs.

(20) In the test sample of FIG. 5B, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is equal to 2.0. Thus, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is smaller than 3.0, even smaller than 2.5 and equal to 2.0.

(21) Another experiment is shown on FIG. 6. The metallic part 14 coated with the cured electrodeposition layer 16′ is coated with the uncured primer 18. Then, the compatible solvent 26 of the uncured sealer 12 is dropped on the uncured primer 18. The compatible solvent 26 spreads over the uncured primer 18.

(22) When, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is smaller than or equal to 3.0, the compatible solvent 26 dissolves in the uncured primer 18.

(23) When, the absolute value of a difference between the log P.sub.ow value of the compatible solvent of the primer and the compatible solvent of the sealer is greater than 3.0, the compatible solvent 26 does not dissolves in the uncured primer 18.

(24) Throughout the description, including the claims, the term “comprising a” should be understood as being synonymous with “comprising at least one” unless otherwise stated. In addition, any range set forth in the description, including the claims should be understood as including its end value(s) unless otherwise stated. Specific values for described elements should be understood to be within accepted manufacturing or industry tolerances known to one of skill in the art, and any use of the terms “substantially” and/or “approximately” and/or “generally” should be understood to mean falling within such accepted tolerances.

(25) Where any standards of national, international, or other standards body are referenced (e.g., ISO, etc.), such references are intended to refer to the standard as defined by the national or international standards body as of the priority date of the present specification. Any subsequent substantive changes to such standards are not intended to modify the scope and/or definitions of the present disclosure and/or claims.

(26) Although the present disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It is understood that the present disclosure is not only meant for a door 10. It may encompass any vehicle body part, such as a frame, a hood, etc.

(27) It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.