Molding method

Abstract

Molding method suitable for making a first component (1 ), comprising at least: a first deposition step of a first mixture (4) on a second surface (30) inside a mold (3) for molding, said first mixture (4) comprising at least a detaching agent (5) suitable for promoting the detachment of said first component (1 ) from said mold (3); a second deposition step wherein a second mixture (7) is deposited at least on predetermined second zones (31 ) of said second surface (30); said second mixture (7) comprising a photoinitiator (9); a filling step wherein said mold (3) is filled with a material (6); a molding step wherein said material (6) in said mold (3) is transformed into said first component (1 ), and said first mixture (4) is present on a first surface (10) of said first component (1 ); an extraction step wherein said first component (1 ) is extracted from said mold (3); and an irradiation step, subsequent to said extraction step, wherein at least some first zones (11 ) of said first surface (10), said first zones (11 ) being facing said second zones (31 ) when said first component (1 ) is contained in said mold (3), are irradiated with electromagnetic radiation capable of activating said photoinitiator (9) and said first mixture (4) undergoes a chemical transformation.

Description

[0001] DESCRI PTION

[0002] MOLDING METHOD

[0003] The present invention relates to a molding method of the type specified in the preamble of the first claim.

[0004] The object of the present invention is a molding method which is mainly, but not exclusively, applied in the field of production and processing of polymeric materials. Currently, detaching agents are known in the production processes of components made of polymeric materials. In particular, these agents are employed in the production of components by molding. In these processes, detaching agents are used to facilitate the separation of the manufactured component from the internal surface of the mold, thus avoiding surface alterations, detachments, and breakages of the component. Consequently, detaching agents are interposed between the surface of the component and the internal surface of the mold.

[0005] Detaching agents are typically chosen based on the type of material to be separated from the mold. Specifically, in the processing and production of polyurethane molded components, two main categories of detaching agents can be distinguished: wax-based detaching agents and polybutadiene-based detaching agents.

[0006] Wax-based detaching agents consist of a material dissolved in a liquid solvent, applied by spraying onto the surface of the mold, followed by the evaporation of the solvent, so that the waxy material solidifies to form a waxy film coating the surface. Wax-based detaching agents can be either water-soluble or dispersed.

[0007] A drawback of wax-based detaching agents dispersed in water is the necessity of working at a mold temperature close to the melting point of the wax, to allow the formation of the waxy film. Consequently, the molding process will be limited in its ability to optimize temperatures. Moreover, wax-based detaching agents tend to deposit a residual layer on the mold, which, after a series of molding cycles, results in a thickening of the film adhered to the surface of the mold, requiring an additional operation to remove the accumulated layer.

[0008] The category of gum-based detaching agents, such as polybutadiene, operates with purely liquid components at use temperatures. In this case, water acts as the medium for spraying the detaching agent onto the surface. The film created in this case is liquid, which facilitates the extraction of the part from the mold.

[0009] Polybutadiene-based detaching agents also lead to the formation of a residual layer on the internal surface of the mold, but over much longer periods compared to waxbased detaching agents.

[0010] Additionally, this class of detaching agents performs an anti-noise function. This function ensures that in the areas of the molded components close to zones in contact with metal or plastic parts, the noise due to the friction between the material of the molded component and the rigid surface of the part attached to the component itself is reduced.

[0011] The known technique described involves some significant drawbacks.

[0012] In particular, this class of detaching agents, in addition to their anti-noise properties, also possesses lubricating properties. This characteristic results in difficulty in performing bonding operations of further parts onto the molded components.

[0013] In this context, the technical task underlying the present invention is to devise a molding method capable of substantially overcoming at least some of the aforementioned drawbacks.

[0014] As part of this technical task, an important objective of the invention is to provide a molding method that allows for the bonding of components even in the presence of a detaching agent on the surface.

[0015] Another important aim of the invention is to create a molding method that enables the production of components coated on the surface with a detaching agent having an anti-noise effect.

[0016] The technical task and the specified aims are achieved by a molding method as claimed in the attached claim 1 .

[0017] Preferred technical solutions are highlighted in the dependent claims.

[0018] The characteristics and advantages of the invention are further clarified by the detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, wherein:

[0019] Fig. 1 shows a diagram of the molding method according to the invention;

[0020] Fig. 2 illustrates a section of a part of a component made by the molding method according to the invention; and

[0021] Fig. 3 illustrates a phase of the molding method according to the invention.

[0022] In this document, measurements, values, shapes, and geometric references (such as perpendicularity and parallelism), when associated with words like " approximately " or other similar terms such as " virtually" or "substantially," are to be understood as subject to measurement errors or inaccuracies due to production and / or manufacturing errors and, most importantly, subject to a slight deviation from the value, measurement, shape, or geometric reference to which they are associated. For example, such terms, when associated with a value, preferably indicate a deviation of no more than 10% from the value itself.

[0023] Moreover, when terms such as "first," "second," "upper," "lower," "primary," and "secondary" are used, they do not necessarily identify an order, priority of relation, or relative position but can simply be used to distinguish different components more clearly one from the other.

[0024] Unless otherwise specified, as results from the following description, terms such as "processing", "computing", "determination", "computation", or similar are considered to refer to the action and / or processes of a computer or similar electronic computation device that manipulates and / or transforms data represented as physical quantities, such as electronic magnitudes of records of a computing system and / or memories into other data similarly represented as physical quantities within computer systems, records, or other storage, transmission, or information display devices.

[0025] The measurements and data reported in this text are to be considered, unless otherwise indicated, as being performed in the International Standard Atmosphere (ICAO) (ISO 2533:1975).

[0026] With reference to the figures, the first component made by the molding method according to the invention is generally denoted by number 1. For instance, the first component 1 can be a car seat or a component with mechanical characteristics capable of absorbing impacts. More generally, the first component 1 can be a component obtained from a material processable by a molding technique.

[0027] The method comprises at least a first deposition step. In this step, a first mixture 4 is deposited. The first mixture 4 comprises at least a detaching agent 5. The latter is a substance capable of reducing adhesion between two surfaces of two components in contact, in such a way as to cause their mutual detachment. Concurrently with the function of facilitating the reduction of adhesion between surfaces, the detaching agent 5 may also confer a lubricating effect on the surfaces to which it is applied. In particular, on the surface portions of components where further components are required to be bonded, the lubricating effect becomes an obstacle to the bonding process.

[0028] The detaching agent 5 may also advantageously have an anti-noise effect. Indeed, at the areas of the first surface 10 in contact with rigid elements such as metal parts or rigid plastic parts, it reduces or eliminates the noise caused by friction between surfaces.

[0029] In particular, the first mixture 4 may comprise water 8 in addition to the detaching agent 5. The presence of water 8 in the first mixture 4, for example, as a solvent, is advantageous when starting with a concentrated detaching agent 5, diluting it to the desired concentration.

[0030] Therefore, the first mixture 4 can be prepared upstream of the molding method. It can be obtained by mixing water 8 and the detaching agent 5. Alternatively, pure detaching agent 5 may be used. Additionally, the first mixture 4 may contain other substances or additives. These can be added to optimize the chemical-physical properties to facilitate the molding method.

[0031] In the first deposition step, the first mixture 4 is deposited on a second surface 30. This is the internal surface of a mold 3. The mold 3 is a tool that allows to produce components by transforming materials or substances, either physically, chemically, or both, to implement the component 1 . In particular, it can be a mold designed for the molding of first components 1 made of polymeric material. Therefore, in the first deposition step, the detaching agent 5 is suited to facilitate the detachment of the first component 1 from the mold 3.

[0032] In particular, the detaching agent 5 preferably comprises polybutadiene. Polybutadiene has the advantage of ensuring an effective detachment effect with polymeric materials, particularly with polymer dispersions. It is also effective for use with polymer foams. Polybutadiene can also be used as a mixture contained in water.

[0033] Polybutadiene is also advantageous in processes where the first components 1 are made, such as padded parts or seats for vehicle interiors. Moreover, the detaching agents 5 belonging to this class remain in a liquid state, enhancing the detaching effect and facilitating mixing with water.

[0034] Another advantage of polybutadiene-based detaching agents 5 is the lesser amount of residue left adhered to the second surface 30 after extraction compared to other types of detaching agents, such as wax-based detaching agents.

[0035] Therefore, the use of the detaching agent 5 has the advantage of reducing the frequency with which the removal of the residue adhered to the second surface 30 during mold 3 maintenance must be performed.

[0036] In the first deposition step, the first mixture 4 is preferably deposited on the second surface 30 by spraying. Spraying can be carried out by atomizing the first mixture 4 through a nozzle. This technique allows for the uniform and consistent deposition of the first mixture 4 on the first surface 10. This prevents situations where the detaching agent 5 acts unevenly on the first component 1 , causing localized and partial damage to the first component 1 .

[0037] The method advantageously comprises a second deposition step. In this step, a second mixture 7 is deposited on at least predetermined second zones 31 of the second surface 30. The second deposition step can be simultaneous with, subsequent to, or prior to the first deposition step.

[0038] The second zones 31 are portions of the second surface 30. In subsequent phases of the method, the second zones 31 are positioned at corresponding parts of the first component 1. Alternatively, the second mixture 7 is deposited over the entire second surface 30.

[0039] The second mixture 7 is a mixture comprising a photoinitiator 9. The photoinitiator is a substance that reacts when exposed to electromagnetic radiation of suitable wavelengths to activate it. Once activated, the photoinitiator 9 can trigger chemical reactions. These reactions allow for the modification of the properties of the components involved in said chemical reactions.

[0040] In particular, the photoinitiator 9 preferably comprises at least one of the following: mono-acylphosphine oxides, bis-acylphosphine oxides, tris-acylphosphine oxides, multifunctional mono-acylphosphine oxides, or bis-acylphosphine oxides. These classes of photoinitiators are advantageous because they are easily mixable with the detaching agent 5 and allow the use of UV radiation for activation and surface treatment.

[0041] Specifically, the photoinitiator 9 preferably comprises bis-acylphosphine oxides dispersed in water. This class of photoinitiators 9 has the advantage of being usable for polymerizing substances. Furthermore, this class of photoinitiators can also be activated by visible light.

[0042] Alternatively, the photoinitiator 9 preferably comprises at least one selected from camphorquinone, thioxanthone, derivatives of said thioxanthone, benzophenone, derivatives of said benzophenone, acetophenone, derivatives of said acetophenone, dialkoxyacetophenones, a-hydroxyketones, a-amino ketones, 4- aryl-1 ,3-dioxolanes, benzoin alkyl ethers and benzyl ketals, ketosulfones, 3- ketocoumarins, phenylglyoxylates, derivatives of said phenylglyoxylates, dimeric phenylglyoxylates, peresters, halomethyltriazines, mixtures including hexaaryl bisimidazole, and a co-initiator, ferrocene or titanocene compounds, O-acyl oxime ester photoinitiators. These classes of photoinitiators 9 also have the advantage of high miscibility with the detaching agent 5 and aqueous dispersions. Furthermore, this type of photoinitiator 9 can also be activated by UV radiation.

[0043] In the second deposition step, the second mixture 7 can be deposited on the second surface 30 by spraying. In this way, the deposition of the second mixture 7 becomes more homogeneous and uniform.

[0044] Specifically, the second deposition step preferably comprises a first sub-step of deposition, wherein the second mixture 7 is deposited on the second surface 30. Therefore, in this first sub-step, the second mixture 7 can be deposited on the entire second surface 30.

[0045] Subsequently, the second deposition step preferably comprises a second sub-step of deposition, wherein the second mixture 7, having a higher concentration of photoinitiator 9, is deposited on the second zones 31 .

[0046] In this way, a differentiation of the final properties of the first component 1 is achieved at the end of the method. These properties are obtained between the portions of the second surface 30 wherein the second mixture 7 with a lower concentration of photoinitiator 9 is deposited and the second zones 31 wherein the second mixture 7 is deposited with a higher concentration of photoinitiator 9.

[0047] In the method, the step following the first deposition step is the filling step. Furthermore, the filling step is preferably subsequent to the second deposition step. In the filling step, the mold 3 is filled with a material 6. The material 6 is the substance that is transformed during the molding process, such that the first component 1 is obtained. The material 6 preferably comprises a polymeric material. The molding method is, in fact, suitable for the transformation of polymeric materials.

[0048] In particular, the material 6 preferably comprises polyurethane. It is a material particularly suited for the production of components capable of absorbing impacts or for padding. Specifically, it is advantageous when the first component 1 is a padded element, such as a car interior seat, or a component that performs both a supporting and ergonomic function. Moreover, as previously mentioned, the use of polybutadiene as a detaching agent 5 ensures that the detachment and lubricating effects are effective on the first component 1 , especially on polymeric materials such as polyurethane.

[0049] Subsequently, the method may comprise a closing step. In this step, the mold 3 is closed, and the material 6, which was previously inserted into the mold 3, is confined therein.

[0050] The method includes a molding step. In this step, the material 6 in the mold 3 is transformed into the first component 1 .

[0051] The molding process causes the transformation of the material 6 into the first component 1 as a result of a chemical transformation.

[0052] Moreover, the first mixture 4 is present on a first surface 10. This surface corresponds to the surface of the first component 1 . Therefore, the first surface 10 is the surface in contact with the second surface 30 when the first component 1 is formed inside the mold 3.

[0053] Consequently, at the end of this step, the first mixture 4 is present on the first surface 10 and can facilitate the detachment of the first component 1 from the mold 3.

[0054] Additionally, the second mixture 7 is also present on the first surface 10. Specifically, the second mixture 7 may be present with a higher concentration of photoinitiator 9 in certain portions of the first surface 10, in such a way as to differentiate the local properties of the first surface 10.

[0055] After the molding step, a mold opening step may follow. The mold 3, containing the first component 1 , is opened.

[0056] Next follows an extraction step, wherein the first component 1 is removed from the mold 3.

[0057] In this step, the detaching agent 5 serves the function of enabling the detachment of the first component 1 from the mold 3, thus advantageously preventing parts of the first surface 10 from adhering to the second surface 30, which could result in alterations or breakages of the first component 1 .

[0058] The method advantageously comprises an irradiation step, following the extraction step, wherein at least first zones 11 of the first surface 10 are irradiated with electromagnetic radiation. This radiation is of a type that activates the photoinitiator 9, thereby causing the first mixture 4 to undergo a chemical transformation.

[0059] The first zones 11 are facing the second zones 31 when the first component 1 is contained in the mold 3.

[0060] The presence of the photoinitiator 9 is therefore advantageous, as it allows for the treatment of the first surface 10 by exposure to electromagnetic radiation of a wavelength suitable to trigger a chemical transformation. In this way, the properties of the first surface 10 are modified, since the activation of the photoinitiator 9, as previously mentioned, causes a chemical reaction. Specifically, the first mixture 4 on the first surface 10 undergoes a chemical transformation. This transformation will take place on the first surface 10, and particularly in the first zones 11 , where the second mixture 7 with a higher concentration of photoinitiator 9 may be present.

[0061] The chemical transformation can result in a change in the surface properties in the first zones 11 and, more generally, in the portions of the first surface 10 whereon the second mixture 7 has been deposited. For example, the first zones 11 , after irradiation, may lose the lubricating properties due to the presence of the detaching agent 5, thereby facilitating the subsequent bonding of additional components. The first zones 11 , after irradiation, transform into treated zones 12. These treated zones enable the bonding of additional components. The treated zones 12 coincide with the first zones 11 and may also coincide with the portions of the first surface 10 that were subjected to the addition of the second mixture 7 and treated by irradiation.

[0062] The irradiation step can be carried out on a conveyor belt, where at least one lamp is present for irradiation, capable of emitting radiation with wavelengths suitable for activating the photoinitiator 9.

[0063] In this way, in-line irradiation of the first component 1 can take place after its release from the mold 30.

[0064] The molding method can comprise additional steps.

[0065] The method preferably includes a partial covering step, which precedes the irradiation step. In the partial covering step, the first component 1 is reversibly covered with masks. In this way, only the first zones 11 are left exposed to the external environment. The masks can be screens with openings oriented at the first zones 11 to be irradiated. Additionally, the masks can be shaped so that the first zones 11 to be irradiated have the desired shape. The masks may be made of a material capable of absorbing the electromagnetic radiation used to trigger the chemical transformation of the first mixture 4.

[0066] Therefore, during the irradiation step, the masks and the first zones 11 are preferably irradiated.

[0067] In this way, the alteration of the surface properties affects only the first zones 11 and not the rest of the first surface 10. Even in the embodiments of the method wherein the second mixture 7 is deposited on the entire first surface 10, the masks allow for the selective irradiation of only the first zones 11 . The method preferably includes a removal step, which follows the irradiation step. In this step, the masks are removed.

[0068] In this way, the lubricating properties of the polybutadiene on the first surface 10 are preserved, and they are lost in the treated zones 12. This differentiation in the surface properties of the first component 1 ensures that the treated zones 12, as previously mentioned, can be used for further processes.

[0069] Thus, the component 1 produced through the molding method is obtained.

[0070] The method can include an additional bonding step, following the irradiation step. In this step, the first component 1 is bonded to at least a second component 2. Each second component 2 can be bonded at least at one of the treated zones 12. For example, the second component 2 can be assembled onto the first component 1 by bonding.

[0071] The method according to the invention achieves significant advantages.

[0072] Indeed, this method allows for the use of polybutadiene-based detaching agents, which are advantageous because they ensure the presence of a liquid lubricating phase on the surface of the extracted piece, while leaving few residues on the internal surface of the mold.

[0073] Furthermore, the method ensures that, through the addition of the photoinitiator, the extracted piece can be assembled with additional components by bonding. Therefore, the method advantageously allows for the use of this class of detaching agents in such a way that both their anti-noise properties are maintained and bonding with other components is possible, selectively in the zones where bonding is intended.

[0074] At the same time, the method allows for improved control over the zones where it is preferable to maintain lubricating properties and those where lubrication is undesirable.

[0075] The method, therefore, allows for retaining the advantages of using polybutadiene- based detaching agents and gaining greater control over the final surface properties of the piece. Therefore, the method according to the invention has the advantage of allowing the assembly of any additional components onto the extracted piece, even in the presence of a detaching agent on the surface.

[0076] The invention is susceptible to variations within the scope of the inventive concept defined by the claims. Within this scope, all details can be replaced with equivalent elements, and materials, shapes, and sizes can be any.

Claims

C LAI M S1. A molding method suitable for making a first component (1 ) and comprising at least:- a first step of deposition of a first mixture (4) on a second surface (30) inside a mold (3) for molding, said first mixture (4) comprising at least a detaching agent (5) suitable for promoting the detachment of said first component (1 ) from said mold (3);- a filling step wherein said mold (3) is filled with a material (6);- a molding step wherein said material (6) in said mold (3) is transformed into said first component (1 ) and said first mixture (4) is present on a first surface (10) of said first component (1 );- an extraction step wherein said first component (1 ) is extracted from said mold (3); and characterized in that it further comprises:- a second deposition step wherein a second mixture (7) is deposited on at least predetermined second zones (31 ) of said second surface (30);- said second mixture (7) comprising a photoinitiator (9);- an irradiation step, subsequent to said extraction step, wherein at least some first zones (11 ) of said first surface (10), said first zones (11 ) being facing said second zones (31 ) when said first component (1 ) is contained in said mold (3), are irradiated with electromagnetic radiation capable of activating said photoinitiator (9) and said first mixture (4) undergoes a chemical transformation.

2. The method according to claim 1 , wherein said detaching agent (5) comprises polybutadiene.

3. The method according to any one of the preceding claims, wherein said material (6) comprises a polymeric material.

4. The method according to the preceding claim, wherein said material (6) comprises polyurethane.

5. The method according to any one of the preceding claims, wherein in said first deposition step said first mixture (4) is deposited on said second surface (30) by spraying.

6. The method according to any one of the preceding claims, wherein said second deposition step comprises:- a first deposition sub-step wherein said second mixture (7) is deposited on said second surface (30);- a second deposition sub-step wherein said second mixture (7) having a higher concentration of said photoinitiator (9) is deposited on said second zones (31 ).

7. The method according to any one of the preceding claims, wherein said photoinitiator (9) comprises at least one of mono-acylphosphine oxides, bisacylphosphine oxides, tris-acylphosphine oxides, multifunctional mono- acylphosphine oxides or bis-acylphosphine oxides.

8. The method according to any one of claims 1 -6, wherein said photoinitiator (9) comprises at least one of a choice of camphorquinone, thioxanthone, derivatives of said thioxanthone, benzophenone, derivatives of said benzophenone, acetophenone, derivatives of said acetophenone, dialkoxyacetophenones, a- hydroxyketones, a -aminoketones, 4-aryl-1 , 3-dioxolanes, benzoin alkyl ethers and benzyl ketals, ketosulfones, 3-ketocoumarins, phenylglyoxylates, derivatives of said phenylglyoxylates, dimeric phenylglyoxylates, peresters, halomethyltriazines,mixtures including hexaaryl bisimidazole and a co-initiator, ferrocene or titanocene compounds, photoinitiators of O-acyl oxime esters.

9. The method according to any of the preceding claims, further comprising:- a partial covering step, preceding said irradiation step, wherein said first component (1 ) is reversibly covered by masks so as to leave only said first zones (11 ) exposed to an external environment;- in said irradiation phase wherein said masks and said first zones (11) are irradiated; and- a removal phase, subsequent to said irradiation phase, wherein said masks are removed.

10. A component (1 ) made by a molding method according to any of the preceding claims.

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