Component for a motor vehicle and method for the production thereof

Abstract

The invention relates to a component (1) for a vehicle (20). The component (1) comprises a main body (10) made of a polyester resin, and comprises a coating (30). The coating (30) is arranged on the side of the main body (10) facing the interior (21) of the vehicle (20). According to the invention, the coating (30) has an epoxy resin. The coating acts as a barrier layer for emissions of volatile compounds from the polyester resin.

Description

[0001] Description

[0002] Component for a motor vehicle and methods for its manufacture

[0003] The invention relates to an emission-reduced polyester component for a vehicle, a vehicle with such a component, and a method for manufacturing the component.

[0004] Some commercially available plastics used as structural components in motor vehicles tend to release volatile compounds that can enter vehicle interiors. For example, high roofs for delivery vans or motorhomes are often made of polyester, which can release small amounts of styrene or other benzene derivatives. This effect can be intensified by elevated temperatures, such as those caused by exposure to sunlight.

[0005] Systems or mechanisms for limiting unwanted volatile compounds are known. Limiting and controlling styrene emissions is particularly important when using styrene-containing polyester resins. To reduce the emission of volatile compounds from polyester components, the use of certain barrier coatings is known, which are intended to prevent the diffusion of unwanted compounds into the vehicle interior. For example, emission-reducing, styrene-free acrylate barrier coatings are known to be applied as a coating to the side of polyester high roofs facing the vehicle interior. The use of acrylate barrier coatings can achieve a good barrier effect against styrene and formaldehyde. However, this high barrier effect often competes with significant intrinsic emissions of unwanted compounds, such as benzene derivatives like toluene and xylene.Furthermore, due to the intended emission suppression, the barrier coatings extend the duration of emissions into the interior at low exposure levels.

[0006] Furthermore, it is known to manufacture structural components from emission-free plastics. However, these are often associated with high costs and / or high manufacturing effort.

[0007] Furthermore, epoxy resins are generally known for repairing, bonding, coating, and as potting compounds for a wide variety of substrates and materials, providing corrosion protection and mechanical abrasion resistance. The substrate materials include mineral building materials and metals.

[0008] The invention is based on the objective of proposing a plastic component for a vehicle that reduces or completely prevents the emission of volatile compounds. The component should, in particular, be simple and cost-effective in design.

[0009] The problems are solved wholly or at least partially by a component and a method for manufacturing the same, having the features of the independent claims. Further preferred embodiments of the invention result from the remaining features mentioned in the dependent claims.

[0010] The component according to the invention for a vehicle comprises a base body made of a polyester resin and a coating which is arranged on a side of the base body facing an interior of the vehicle and partially or completely coats this side. The coating is characterized in that it contains an epoxy resin or consists essentially entirely of one.

[0011] The aforementioned epoxy resin coating has the surprising advantage of forming a diffusion-tight layer that inhibits the diffusion of unwanted volatile compounds and creates a highly effective barrier. In this way, the penetration of unwanted compounds, including benzene, benzene derivatives such as styrene, formaldehyde, and per- and polyfluoroalkyl substances (PFAS), from the polyester resin of the base material into the vehicle's interior can be significantly reduced or completely prevented. Furthermore, epoxy resins are characterized by virtually no inherent emissions of unwanted volatile compounds. This coating allows the use of cost-effective polyester resins (such as unsaturated polyester resins) as the base material for the component without having to accept their emissions.

[0012] In the context of this application, epoxy resin is understood to be a plastic that is the reaction product of a macromolecular epoxide-containing polyether and an amine-containing hardener. The epoxide-containing polyether, as the resin component, and the hardener, as the second component, are used and processed as a two-component composition, which cures after application to the substrate through the reaction of the epoxide groups with the amine groups of the hardener.

[0013] In a preferred embodiment of the invention, the epoxy resin is a bisphenol monomer-based epoxy resin. That is, the polyether of the epoxy resin comprises one or more bisphenols. The use of bisphenol monomers ensures a stable and resistant coating, which is also characterized by a high barrier effect against volatile compounds. Any bisphenols can be used within the scope of the invention, including bisphenol A (CAS name: 2,2-bis(4-hydroxyphenyl)propane), bisphenol AF (2,2-bis(4-hydroxyphenyl)hexafluoropropane), bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol B (2,2-bis(4-hydroxyphenyl)butane), bisphenol BP (bis(4-hydroxyphenyl)diphenylmethane), bisphenol C (2,2-bis(3-methyl-4-hydroxyphenyl)propane), bisphenol O2 (1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene), bisphenol E (1,1-bis(4-hydroxyphenyl)ethane), bisphenol F (bis(4-hydroxyphenyl)methane), and bisphenol FL (9,9-bis(4-hydroxyphenyl)fluorene).Bisphenol G (2,2-bis(4-hydroxy-3-isopropylphenyl)propane), Bisphenol M (1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene), Bisphenol P (1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene), Bisphenol PH (2,2-{5,5'-bis[1,1'-(biphenyl)-2-ol]}propane]), Bisphenol S (bis(4-hydroxyphenyl)sulfone), Bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane), Bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), and mixtures thereof. Epoxy resins based on Bisphenol A or Bisphenol F, or a mixture thereof, are particularly preferred due to their high corrosion resistance, temperature resistance, and durability. Furthermore, bisphenol A and bisphenol F are cost-effective monomers that keep production costs low. In particular, bisphenol F, alone or in combination with other bisphenols, has proven especially advantageous with regard to the peel resistance of the coating to the substrate.

[0014] The polyether of the resin component, in particular the bisphenol-based polyether, has epoxide groups (ethylene oxide groups), which are preferably arranged terminally, and preferably two terminal epoxide groups. Generally, such an epoxylated polyether is obtained by reacting the terminal hydroxyl groups of the polyether with a glycidyl compound. The glycidyl compound can be selected, in particular, from epichlorohydrin, 4,4'-methylenediphenyl diglycidyl ether, 1,6-bis(2,3-epoxypropoxy)hexane (= 1,6-hexanediol diglycidyl ether), and others, as well as mixtures thereof. The glycidyl compound most preferably comprises at least epichlorohydrin, which can be used alone or in combination with others. The hardener component of the (uncured) epoxy resin comprises amine compounds with two or more primary or secondary amino groups, which react with the epoxide groups of the resin component during curing.Suitable amine compounds include, for example, diethylenetriamine, 1,3-diaminobenzene, 4,4'-methylenebis(cyclohexylamine), 3-aminomethyl-3,4,4-trimethylcyclohexylamine, 2,4,6-tri-(dimethylaminomethyl)phenol, and others. Particularly preferred within the scope of the invention are hardeners with three or more amino groups, i.e., triamines or polyamines, since these lead to crosslinking of the resin component. These can be used alone or in combination with other amine compounds.

[0015] In a preferred embodiment of the invention, the epoxy resin is cross-linked, with a high degree of cross-linking being particularly preferred. Cross-linking provides a particularly good barrier effect against unwanted volatile compounds, and this effect increases with increasing degree of cross-linking. Cross-linking can be achieved by the hardener, in particular by a hardener comprising triamines or polyamines, wherein the degree of cross-linking can be adjusted by the proportion of the hardener in the epoxy composition and the molecular ratio of the triamines or polyamines to the epoxy groups of the resin component.

[0016] In a further preferred embodiment of the invention, the coating is diffusion-tight against undesirable volatile compounds, including benzene, benzene derivatives (especially styrene), formaldehyde, and PFAS compounds, at temperatures up to 100 °C. Diffusion-tightness refers to the property of preventing the passage of these compounds, particularly gaseous ones, or at least allowing only very small amounts. This is particularly advantageous, for example, during extended periods of parking in sunny locations where high temperatures can occur. Coatings that lack temperature resistance can exhibit increasing diffusion rates of volatile compounds at high temperatures or even suffer thermal damage and alterations, further reducing their barrier effect.The temperature resistance up to 100 °C ensures that no undesirable changes or damage occur at higher temperatures, such as those that arise during longer periods of parking in the sun, and that the diffusion of volatile compounds through the coating into the interior of the vehicle is reliably inhibited.

[0017] In a further preferred embodiment of the invention, the coating has a layer thickness of at least 50 pm, in particular at least 100 pm, and most preferably 150 pm. A greater layer thickness increases the protection against emissions from the substrate and extends the service life of the coating.

[0018] Furthermore, it is preferred that the polyester resin of the base body is an unsaturated polyester resin. Unsaturated polyester resins have double bonds in their linear or branched polymer chain. The double bonds are characterized by high chemical reactivity, which allows cross-linking with the coating to occur.

[0019] This allows the coating to be bonded to the base body in a particularly stable manner.

[0020] In a further preferred embodiment of the invention, the polyester resin of the base body comprises or consists of a glass fiber-reinforced polyester resin composite. The glass fiber reinforcement results in increased strength. This also has a positive effect on the durability, strength, and toughness of the base body.

[0021] In a further preferred embodiment of the invention, the component according to the invention is the roof of a vehicle. The vehicle roof forms the upper boundary of the vehicle's interior and has a comparatively large surface area as well as increased exposure to solar radiation. Since the vehicle roof is continuously exposed to the sun's UV rays, increased heating occurs, even on its side facing the vehicle's interior. By coating the vehicle roof with the epoxy resin coating according to the invention, the emission of volatile compounds from the polyester resin can be at least reduced or completely prevented. The aforementioned advantages are particularly relevant for high roofs, such as those used on delivery vehicles or camper vans. On the one hand, the occupants spend comparatively long periods of time in these vehicles, which is why particularly low emissions are desirable.Furthermore, high roofs are often made of polyester.

[0022] In a further preferred embodiment of the invention, the coating exhibits no self-emissions at temperatures up to 100 °C. Self-emission is understood to be the process by which the coating material, upon sufficient energy input (for example, in the form of heat), undergoes chemical reactions involving partial decomposition and releases new, low-molecular-weight compounds, which are primarily released into the environment in gaseous form. Self-emission also includes the release into the environment of low-molecular-weight compounds present as additives in the coating material, such as solvents or other additives. Prolonged parking in strong sunlight can lead to high temperatures, which promote self-emissions in the vehicle's interior. The coating ensures reduced self-emission levels in the vehicle interior even at high temperatures up to 100 °C.

[0023] In a further preferred embodiment of the invention, the coating material forms a chemical bond with the polyester resin of the base body. A chemical bond is understood to mean the presence of, in particular, covalent bonds between the macromolecules of the coating material and the base body. The chemical bond between the epoxy resin and the polyester resin results in a strong adhesion of the coating to the base body, thereby achieving high durability with low wear.

[0024] In a further preferred embodiment of the invention, the coating and / or the chemical compound is provided to have a pull-off strength of at least 2.0 MPa, in particular at least 2.5 MPa, and most preferably at least 3.0 MPa. This ensures the stability and durability of the coating. Cracks and damage to the coating can also impair the desired protective function against unwanted compounds. The high pull-off strength ensures that no damage can occur to the coating. The pull-off strength is measured using a method according to ASTM D4541 with a flat, circular test specimen with a diameter of 50 mm.

[0025] Another aspect of the invention relates to a method for manufacturing a component according to the invention, comprising the following process steps:

[0026] a) Providing a base body made of a polyester resin;

[0027] b) Providing an uncured composition for the formation of an epoxy resin;

[0028] c) manual or automated application of the composition to the side of the base body facing the interior of the vehicle;

[0029] d) Curing of the applied composition to form a coating on the side of the base body facing the vehicle's interior. In a preferred embodiment of the process, the uncured composition used to form the epoxy resin is solvent-free, and the application of the composition is also solvent-free. Eliminating solvents during the manufacturing process allows for an environmentally friendly, cost-effective method with minimized health risks. Furthermore, the risk of emissions from the coating itself due to solvent contamination is minimized.

[0030] In a further preferred embodiment of the method, the composition is applied by spraying, in particular using a spray head. This allows for the simplest, fastest and most uniform application possible in a controllable layer thickness.

[0031] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0032] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show:

[0033] Figure 1 shows a schematic representation of a component according to an embodiment of the invention in a sectional view;

[0034] Figure 2 shows a high roof according to an embodiment of the invention;

[0035] Figure 3 shows a vehicle with a high roof according to an embodiment of the invention;

[0036] Figure 4 shows a schematic representation of the manufacturing process according to one embodiment of the invention.

[0037] Figure 1 shows a schematic representation of component 1 according to the invention in a cross-sectional view.

[0038] The component for a vehicle, designated as 1, comprises a base body 10 and a coating 30, which faces the interior 21 of the vehicle 20. The base body 10 comprises a polyester resin. Preferably, the base body 10 comprises a glass fiber reinforced polyester resin composite, which includes an unsaturated polyester resin (UP resin).

[0039] The coating 30 comprises a preferably highly cross-linked epoxy resin. The coating 30 forms a diffusion barrier that makes it difficult for undesirable compounds, such as benzene, benzene derivatives, especially styrene, formaldehyde, or PFAS compounds, to enter the interior of the vehicle. The coating 30 is particularly advantageous due to its high temperature resistance of up to 100 °C and its diffusion tightness, which is maintained at least up to this temperature. This ensures that the coating 30 will not be damaged, emit compounds, or lose its diffusion-blocking properties, for example, during prolonged parking in areas exposed to strong sunlight.

[0040] The epoxy or polyurethane resin used for coating 30 is produced on the basis of bisphenol monomers, for example bisphenol F and / or bisphenol A, particularly preferably bisphenol F. Bisphenols form high-strength coatings characterized by temperature resistance, durability, corrosion resistance, and cost-effective production.

[0041] A chemical bond 40, preferably in the form of covalent bonds, exists between the base body 10 and the coating 30. This results in a pull-off force of at least 2.0 MPa, particularly at least 2.5 MPa, and most preferably at least 3.0 MPa. This also has a beneficial effect on the durability of the coating 30. Particularly high pull-off forces were achieved using epoxy resins based on bisphenol F.

[0042] Figure 2 shows component 1 as a high roof 22 according to an embodiment of the invention, and Figure 3 shows a vehicle 20 with such a high roof 22. High roofs 22 are exposed to significant solar radiation and experience high heat loads over time. Coatings applied to the interior side of high roofs 22 must exhibit high temperature resistance to prevent the emission of undesirable compounds due to heat generation. The epoxy resin coating 30, particularly one based on bisphenols, is specifically adapted to this requirement and is especially suitable as a coating 30 for a high roof 22. The interior 21 of the vehicle 20 with the high roof 22 according to the invention is protected from undesirable emissions of volatile compounds by the epoxy resin coating 30 according to the invention.

[0043] Figure 4 schematically shows the manufacturing process of component 1 according to the invention.

[0044] In process step a), the base body 10 is provided from a polyester resin. This can be done using conventional methods such as injection molding or the like.

[0045] In process step b), a preferably solvent-free, uncured composition is provided for the formation of an epoxy resin. The composition comprises the reaction components (starting materials) for the formation of the respective plastic. In the case of an epoxy resin, the composition comprises a macromolecular polyether, preferably bisphenol-based, with terminal epoxy groups and an amine-containing hardener that also acts as a crosslinker. The absence of solvents during the manufacturing process enables environmentally friendly and cost-effective production, as no additional process steps are required for solvent removal. Furthermore, this avoids the emissions that can occur due to residual solvents in the coating.

[0046] In the next process step c), the composition is applied manually or automatically to component 1 on the side of the base body 10 facing the interior 21 of the vehicle 20, for example by spraying using a spray head.

[0047] In the last process step d), the applied composition is cured, forming the coating 30 on the side of the base body 10 facing the interior 21 of the vehicle. Curing is carried out, for example, by heat input or by suitable electromagnetic radiation, in particular UV radiation.

[0048] Examples

[0049] To investigate the emission behavior of components according to the invention, two polyester sheets each with a bisphenol-A coating of 150 pm and two polyester sheets with a bisphenol-F coating of 150 pm were manufactured and tested under controlled conditions. The polyester sheets were new parts to simulate the conditions of a new vehicle roof. Two identical uncoated polyester sheets were tested as a reference. The testing of the six test specimens was carried out over a period of 4 hours in a steel chamber at a constant temperature of 65 °C and an air exchange rate of 2.5 m³ / h. 3The chamber was heated for a period of time of 1 hour and a relative humidity of 5%. Following this holding time, the concentrations of styrene, benzene, xylene, and formaldehyde in the chamber were determined, with the measurement method having a maximum measurement tolerance of ±16%. The measurements were carried out by the independent Fraunhofer Wilhelm-Klauditz-Institute in Braunschweig.

[0050] The results are summarized below in Table 1 and compared to the applicant's internal limits according to VW50175.

[0051] Table 1: Emission behavior

[0052]

[0053] 'Limit values ​​according to VW50175

[0054] The results show that the bisphenol-A coating leads to a significant reduction in formaldehyde emissions compared to the uncoated control sample, while styrene emissions remain essentially unchanged. The bisphenol-F coating reduces both styrene and formaldehyde emissions significantly below the limit values. Benzene and xylene emissions are below the respective limit values ​​for all samples.

[0055] component

[0056] basic body

[0057] vehicle

[0058] interior

[0059] High roof

[0060] coating

[0061] chemical compound

Claims

Patent claims 1. Component (1) for a vehicle (20), comprising a base body (10) made of a polyester resin and a coating (30) which is arranged on a side of the base body (10) facing an interior (21) of the vehicle (20) and partially or completely coats this side, characterized by that the coating (30) contains or consists of an epoxy resin.

2. Component (1) according to claim 1, characterized in that the epoxy resin is an epoxy resin based on bisphenol monomers, in particular based on bisphenol A and / or bisphenol F.

3. Component (1) according to claim 1 or 2, characterized in that the epoxy resin is cross-linked.

4. Component (1) according to one of the preceding claims, characterized in that the coating (30) is diffusion-tight against benzene, styrene, formaldehyde and PFAS compounds.

5. Component (1) according to one of the preceding claims, characterized in that the coating (30) has a layer thickness of at least 50 pm, in particular at least 100 pm, particularly preferably 150 pm.

6. Component (1) according to one of the preceding claims, characterized in that the polyester resin of the base body is an unsaturated polyester resin.

7. Component (1) according to one of the preceding claims, characterized in that the polyester resin of the base body (10) comprises or consists of a glass fiber reinforced polyester resin composite.

8. Component (1) according to one of the preceding claims, characterized in that the coating (30) has no intrinsic emissions at temperatures up to 100 °C.

9. Component (1) according to one of the preceding claims, characterized in that a covalent connection (40) exists between the epoxy resin or polyurethane resin of the coating (30) and the polyester resin of the base body (10).

10. Component (1) according to one of the preceding claims, characterized in that the coating (30) and / or chemical compound (40) has a pull-off force of at least 2.0 MPa, in particular at least 2.5 MPa, particularly preferably at least 3.0 MPa.

11. Component (1) according to one of the preceding claims, characterized in that the component (1) is a roof (22) for vehicles (20), in particular a high-roof delivery vehicle or camping vehicle.

12. Vehicle (20) comprising a component (1) according to one of the preceding claims.

13. Method for manufacturing a component (1) according to any one of claims 1 to 11, comprising the process steps: a) Providing a base body (10) made of a polyester resin; b) Providing an uncured composition for the formation of an epoxy resin or a polyurethane resin; c) Applying the composition to the side of the base body (10) facing the interior (21) of the vehicle (20); d) Curing of the applied composition to form a coating (30) on the side of the base body (10) facing the interior (21) of the vehicle (20).

14. Method for producing a component (1) according to claim 13, characterized in that the uncured composition and the application of the composition are solvent-free.

15. Method for manufacturing a component (1) according to claim 13 or 14, characterized in that the composition is applied by spraying.

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