NL1007001C2 - Sheet-shaped prepreg. - Google Patents

Description

- 1 - PN 9091 SHEET PREPREG 5

The invention relates to a sheet-shaped prepreg consisting of one or more layers of a sheet-shaped support, which support is impregnated with an as yet uncured resin.

Sheet-like prepregs consisting of multiple stacked films of alpha cellulose impregnated with the reaction product of formaldehyde and melamine are known, for example, from US-A-3730828. According to this patent, paper 15 is first impregnated with a resin of melamine-formaldehyde. A prepreg is then made by stacking a few layers of this impregnated paper on top of each other.

For example, under a pressure of 6 MPa and at a temperature of about 150 ° C, the resin 20 is cured in a press. The conversion of the reaction between formaldehyde and melamine in the sheet-shaped product thus obtained is complete (completely cured). The sheet-like articles described in this patent have been found to have good post-forming properties. By post-forming it is meant here that the sheet-shaped article can be bent at an elevated temperature which lies between 160 and 180 ° C. It is hereby possible to bend the sheet-shaped article along one axis without the sheet-shaped article breaking / tearing.

A drawback is that starting from a prepreg according to US-A-3730828 it is not possible to obtain sheet-shaped products which can be bent along two (or more) intersecting axes into complex shapes without breaking / tearing. With complex shapes you can think for example of a saddle-shaped pattern, a tub, a sickle pattern or a pimple.

1007001 - 2 -

The object of this invention is a prepreg with which more complex shapes can be obtained.

This object is achieved in that the support is a sheet-like porous polymer and the elongation at break of the prepreg and of the individual impregnated support is greater than 10%.

It has been found that, based on the prepreg according to the invention, sheet-shaped products can be made in the most diverse shapes, without cracks being formed in the sheet-shaped product during deformation.

Sheet shaped articles with molds in which the prepregs are locally stretched from 10% to more than 400% during molding are now possible. A further advantage is that the further curing of the resin and the deformation can be carried out in one step. This is in contrast to the method described in the aforementioned US-A-3730828 where, based on the prepreg, two steps are required to arrive at a formed end product. An additional advantage is that the prepreg can be processed with a variety of techniques, so that the most optimal technique can always be used for each end product.

Starting from the prepreg according to the invention it is furthermore possible to make sheet-shaped products which, for instance along one axis, are bent to an acute angle. This is not possible on the basis of the known prepregs based on a paper carrier.

JP-A-7002119 discloses a prepreg consisting of a carrier of a polyamide non-woven material and a carrier of kraft paper, which carriers are impregnated with a melamine-formaldehyde resin. An impregnated polyamide non-woven carrier generally has an elongation at break of more than 10%. However, impregnated kraft paper has an elongation at break of less than 10%, making the elongation at break of the 1007001-3 prepreg as a whole less than 10%.

A sheet-shaped porous polymeric carrier is understood to mean any polymer which contains a high degree of porosity. The porosity of the polymeric carrier 5 is essential to obtain the advantageous properties of the prepreg as described above.

Due to the high porosity, the sheet-shaped polymeric carrier can, as it were, be mixed almost homogeneously with the resin. Preferably, the porosity is obtained in the form of microscopically interconnected cavities and preferably slightly larger cavities and holes are present. Larger holes lead to loss of resin during further processing of the prepreg to its final shape. Preferably, the porosity is sufficiently large that at least 30% by volume of the final molded article consists of resin. The porosity is the ratio of the density of the porous polymeric support to that of the corresponding bulk polymer (no voids).

The porous polymeric support may be, for example, a nonwoven sheet polymer, a sheet open polymer foam or a microporous membrane. Preferably, the fibers of the nonwoven are less than 0.1 mm. Non-woven fabrics with very small diameter fibers are also called open films. Due to the small wire diameter, this class of non-wovens has few larger meshes and many microscopically small interconnecting cavities. The fibers of these nonwovens are generally parallel to the plane of the sheet-like porous polymer. Polymer foams naturally have reasonably definable and uniform sizes of the interconnected voids.

The cavities preferably have a diameter of less than 1 mm. Occasionally larger cavities may be present in the foam if more than 80% by volume of the 1007001-4 cavities have these smaller diameters.

The porous polymeric support can in principle be any porous polymeric support that meets the requirement that the impregnated support has an elongation at break of more than 10%. Examples of porous polymers are porous polyethylene, porous polypropylene, porous polyestyrene, porous ethylene propylene copolymers, porous EPDM, porous polyamides, for example, porous nylon 6,6, porous nylon-6, porous ethyl cellulose, porous diacetate, SAN porous SMA porous polyesters, for example, porous polyethylene terephthalate (PET), porous polybutene terephthalate (PBT), porous polyethers. The above polymers can be used as a non-woven, open film or as an open polymer foam as a porous polymeric support.

Examples of an open film polyethylene are the polyethylene types known under the name Solupor® (Solupor® is a brand name of DSM N.V.). Nonwovens based on different polymers are suitable for use as a support. An example of a non-woven polyethylene is Tyvek * (Tyvek * is a brand name of DuPont de Nemours). Lutasil® (Lutasil * is a brand name of Freudenberg) is an example of a non-woven polypropylene. Example of a non-woven polyester 25 is Viledon® H1206. An example of a non-woven polyamide is Viledon® FS2118 (Viledon® is a brand name of Freudenberg). An example of an open polymer foam is Calligan * open cell foam standard 1.17 polyether (Calligan® is a brand name of Calligan 30 Europe B.V.).

The polymer may have both polar and non-polar properties. By using suitable wetting agents, the desired degree of impregnation of the polymer sheet by the resin can be obtained. As a rule, all wetting agents known to the person skilled in the art can be used. Examples of wetting agents are PAT® 523W, PAT® 959 (PAT® is 1007001 - 5 - a brand name of Wilrtz), Nonidet® P40 (Nonidet® P40 is a brand name of Sigma Chemie) and Aminol® N (Aminol® is a brand name of Chem-Y).

The resin can in principle be any thermosetting resin known. Examples are aminoplast formaldehyde resin, phenol-formaldehyde resin (PF resin), epoxy resin or unsaturated polyester resin.

An aminoplast formaldehyde resin is preferably used as the resin. As an aminoplast, for example, urea, melamine or benzoguanamine can be used. Preferably melamine is used because of superior mechanical properties. The resin can be manufactured in a method known to the person skilled in the art by reaction of aminoplast and formaldehyde in water. For example, the ratio of formaldehyde: melamine is normally between 1: 1 and 6: 1, preferably between 1.2: 1 and 2: 1. Optionally, the aminoplast can be partly replaced by, for example, phenol, but this can have negative effects on the color. Modifiers can also be added, such as sorbitol, ε-caprolactam, ethylene glycol, trioxitol, toluenesulfonamide, and benzo and acetoguanamine.

Practically useful mechanical properties are achieved if 10-70 wt.% Porous polymer and 90-30 wt.% Resin are used. The resin can contain the known fillers such as lime, clay, glass, carbon, silica or metal particles. However, it has been found that the best results are achieved in the absence of fillers or at least with fewer fillers than has hitherto been customary. The weight ratio of fillers and resin is preferably between 0: 1 and 0.5: 1. These ratios relate to the cured final sheet-shaped article.

The prepreg consists of one or more stacked sheets of the impregnated porous polymeric support.

1007001 - 6 -

The number of sheet carriers is generally 10 or less, and preferably 5 or less. The prepreg can vary in thickness from 100 μνη to about 3 cm. The extent to which the resin has cured in the prepreg can be determined for melamine-formaldehyde (MF) and PF resins by determining the residual volatility. This residual volatility is the mass loss of the prepreg at 160 ° C for 7 minutes. The residual volatility of the prepreg is usually between 2-20%. The elongation at break of the prepreg as used in the description is defined as the elongation at break at a residual volatility of about 5%

The prepreg is made under the conditions already known for making paper carrier prepregs, as described, for example, in the aforementioned US-A-3730828 or JP-A-7002119. The resin is preferably dissolved in water and is "water liquid", preferably the resin has a viscosity of 1-1000 Pa.s. The viscosity can be influenced by varying the amount of solvent. The solvent will vary depending on the resin selected. For example, as yet uncured aminoplast formaldehyde is dissolved in water. Preferably, solvents are used in which the polymeric carrier does not dissolve or swell. The temperature during impregnation can be between 15-60 ° C and is often room temperature for practical reasons. Higher temperatures are less practical because the resin partially hardens during impregnation. The pressure during impregnation is not critical and, for practical reasons, is usually atmospheric.

The thus impregnated carriers are dried until residual volatility is achieved as described above for the prepreg. Drying preferably takes place at a temperature of 100-160 ° C. Higher temperatures are less practical because the drying times then become too short, resulting in a 1 007001 - 7 - less manageable process. In practice, the temperature will partly be determined by the type of oven. The carrier is preferably stacked after drying.

The elongation at break of the individual impregnated support (residual volatility = about 5%) and of the prepreg obtained is greater than 10% and preferably greater than 50%. The prepreg may optionally also include layers of a non-porous polymer in addition to the porous polymer supports provided that these polymers also have an elongation to break greater than or equal to that of the prepreg.

The prepreg can be processed into a finished finished product by first deforming the prepreg and then curing the formed intermediate at an elevated temperature or by combining the deformation and curing in one step.

The deformation, optionally in combination with the curing, can be carried out by means of bending, shaping, stamping, pneumatic or mechanical stretching.

The temperature during deformation will depend on the yield stress of the prepreg. The yield stress is the stress at which the material starts to flow. This yield stress is determined by the resin composition, resin content, polymer type and water content. In principle, this temperature can be between room temperature and 200 ° C. At temperatures higher than 100 ° C, the resin will already (partly) harden during the deformation, so that the deformation and curing of the resin will take place simultaneously.

The shaped product thus obtained can be used as a final product or as a protective layer around an object with a core material of, for example, wood, metal, glass or plastic, for example polyethylene, polypropylene, ABS, polyamide and MF, PF and epoxy resins.

Examples of end products of the 1007001 - 8 - shaped product are trays, dishes, crockery, doors, kitchen tops, furniture, wall panels. Examples of end products where the shaped product is used as a protective layer for a wooden core are counter tops with, for example, an acute angle, (kitchen) cupboards or frames. Examples of objects in which the shaped product serves as a protective layer for a plastic core are bumpers, petrol tanks, garden furniture, counter tops or car body parts.

The protective layer can be glued to the core material. Another possibility is that the molded article is applied to the core while the resin is not yet fully cured. The resin then serves as an adhesive when it is subsequently cured.

The invention will be described by the following non-limiting examples.

20

Example 1 Preparation of resin

In a reactor, 100 parts of melamine, 24 parts of water and 135 parts of formaldehyde (30% formaldehyde in water which had been adjusted to pH 9.3 with 50% NaOH) were added. The F / M ratio of the resin was 1.7 (F / M ratio is the formaldehyde-melamine mol ratio). The condensation reaction was carried out at 95 ° C until the water dilutability of the resin at 20 ° C was 1.5 g resin per g water. The water dilutability is the amount (g) of water that can be added to a resin solution (g) at 20 ° C before the solution becomes cloudy. The resin was reactivated (catalyzed) with a 50% (weight) p-toluenesulfonic acid solution to pH 8.1.

1007001 - 9 -

Preparation deformation product 4 sheets of 10 by 10 cm Solupor® (type 16PO3; DSM) were impregnated at room temperature with the above resin solution to which 1% (m / m) of Nonidet® 5 P40 (Sigma Chemie) was added as wetting agent. After a few minutes, the resin impregnated sheets were removed from the resin arrangement and the excess resin was removed using a "wringer". The sheets were dried in a ventilation oven at 100 ° C for 4 minutes.

Preorea characterization

Resin Content: The resin content of the prepreg was determined by weighing the prepreg and the polymeric support and was 440%. The resin content is defined as: (g (prepreg) -g (polym) / g (polym) g (prepreg) and g (polym) are the weights of the prepreg and of the polymeric carrier Solupor, respectively.

Residual volatility content: The residual volatility content was determined by measuring the weight loss after further drying and curing the prepreg for 7 minutes in an oven at 160 ° C and was 3.5%. The residual volatility content is defined as (g (before) -g (na)) / g (before) 30 g (before) and g (after) are the prepreg weights before and after treatment at 160 ° C, respectively.

Characterization of the laminate: 35 Resin content: The resin content of the laminate was determined by weighing the laminate and the starting polymers and was 406%. The resin content is 1007001 - 10 - defined as: (g (laminate) -g (polym)) / g (polym) g (laminate) and g (polym) are the weights of the laminate and of the polymeric support, respectively.

Elongation at break: The elongation at break is measured on test pieces (size 4.0 * 50.0 * 0.07 mm) using a Standard Zwick pull bench at 140 ° C according to ISO 37 type 3 and amounted to more than 400%, the maximum value to be measured with this device. The tensile strength was 5.4 MPa. The deformation speed was 100 mm / min.

- 2D pressing: 4 sheets of the prepreg of 10 * 10 cm are pressed into a laminate according to the following high pressure laminate pressing cycle: The sheets are put in the press (of the type Fontijnen SRA 100) at 60 ° C and the press is brought to a pressure of 80 bar and the press is further heated in about 15 minutes to 130 ° C, this temperature is maintained for 30 minutes and then it is cooled in about 15 minutes to 60 ° C after which the pressure is released.

- 3D pressing: 25 Single sheets of Solupor prepreg on a high density polyethylene core material were pressed at 140 ° C in an S-shaped mold for 20 minutes. The closing force was 9 MPa. Then it was cooled to 40 ° C for 10 minutes. The results are further listed in Tables 1 and 2.

Example 2

The same procedure as in example 1 has been repeated, but instead of Solupor, Tyvek® L1058D 35 (DuPont) has been used. Table 1 shows the resin content, residual volatility content, prepreg press conditions and the resin content of the laminate 1 007 001-11. Table 2 shows the elongation at break and the tensile strength of the prepreg at the stated test temperature.

5 Example 3

The same procedure as in example 1 has been repeated, but Lutrasil® 3450 (Freudenberg) has been used instead of Solupor. See Tables 1 and 2 for further conditions and results.

10

Example 4

The same procedure as in example 1 has been repeated, but instead of Solupor, cellulose diacetate (CD) non-woven has been used. See Tables 1 and 2 for further conditions and results.

Example 5

The same procedure as in Example 1 was repeated using instead of Solupor® Viledon® FS2118. See Tables 1 and 2 for further conditions and results.

Example 6

The same procedure as in Example 1 was repeated using instead of Solupor® Viledon® H1206. See Tables 1 and 2 for further conditions and results.

Comparative experiment A

The same method as in example 1 was used, but instead of Solupor a decor paper (80 gr / m2) was used. See Tables 1 and 2 for further conditions and results.

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Claims (13)

1. Sheet-shaped prepreg consisting of one or more layers of a sheet-shaped support, which support is impregnated with an as yet uncured resin, characterized in that the support is a sheet-shaped porous polymer and that the elongation at break of the prepreg and the individual impregnated sheet carrier is greater than 10%. Sheet-shaped prepreg according to claim 1, characterized in that the elongation at break of the separate impregnated sheet-shaped support and of the prepreg is greater than 50%. Sheet-like prepreg according to any one of claims 1-2, characterized in that the density of the porous polymeric support is less than 70% of the density of the corresponding bulk polymer. 4. Sheet-shaped prepreg according to any one of claims 1-3, characterized in that the porous polymeric support is a sheet-shaped non-woven, open-film or open-foam polymeric support. Sheet-shaped prepreg according to claim 4, characterized in that the porous polymeric support is a non-woven or open film support. Sheet-shaped prepreg according to any one of claims 1 to 5, characterized in that the resin is an aminoplast formaldehyde resin, a phenol formaldehyde resin, an epoxy resin, or an unsaturated polyester resin. Sheet-shaped prepreg according to claim 6, characterized in that the resin is an aminoplast formaldehyde resin. Sheet-shaped prepreg according to claim 7, characterized in that the aminoplast is urea, melamine or benzoguanamine. Sheet-shaped prepreg according to any one of claims 7-8, characterized in that the residual volatility is between 2 and 20%. 1007001 -Ιδιο. Sheet-like prepreg according to any one of claims 1-9, characterized in that the weight ratio of fillers and resin is between 0: 1 and 0.5: 1. A method for making a prepreg according to any one of claims 5 to 7-9, wherein the polymeric carrier is impregnated with water-liquid resin, optionally in the presence of a wetting agent, after which the carriers thus impregnated are dried (precured), the water being evaporated so that the prepreg has a residual volatility of 2-20%, after which the prepreg may be stacked. 12. A method for processing a prepreg according to any one of claims 1-10 into a molded article in which the prepreg is deformed at a temperature between room temperature and 200 ° C, wherein the resin, either in a subsequent step or during the deformation, hardens. 13. Method according to claim 12, characterized in that locally the prepreg is stretched at least 50% during the molding. 14. Use of the shaped product obtained by the method according to any one of claims 12-13 as a protective layer of a wooden, plastic, glass, metal object. 1 007001 COOPERATION TREATY (PCD REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE ION IDENTIFICATION OF NATIONAL APPLICATION Characteristic of applicant o! Van da gemacntigee 9091NL Dutch application no. request for an examination of miemaoonai type Ooor the Insanoe for Intemaeonaai Onderzoek (ISA) assigned to the request for an examination of international type no. SN 30038 NL I. CLASSIFICATION OF THE SUBJECT (in case of secassmg of hideout classifications, specify all ossificaoesym languages) According to International Classification (IPC) Int Cl.6: C 08 J 5/24 II AREAS OF TECHNIQUE EXAMINED _____Unsupported minimum documentation_____ Classification system__Classification symbols __; __ J Int Cl.6 C 08 J Documentation other than minimum documentation enter as far as such documents m the geoieoen examined are I omen! i ΙΙΙ.Γ '"NO EXAMINATION FOR CERTAIN CONCLUSIONS {oomerxmgen co complementolad) J IV .'_ LACK OF UNIT OF INVENTION (ccmerttmgen op supplementircsotad) • rom PCTïlSA / 20 1! a i CS 15¾ ΙΓ