JPH0740340A - Production of sheet molding material, laminate of sheet molding material, and molded article - Google Patents

Abstract

PURPOSE: To provide a method for producing a sheet-shaped molding material which is easy of handling an SMC layer, prevents the final product from showing a wound, and has optimum mechanical strength. CONSTITUTION: A fiber material in the form of a mat or a fleece is impregnated with an aminoplastoresin mixture. The fiber material has tensile strength at room temperature of 0.1-20 MPa. When a sheet-shaped molding material(SMC) is produced by drying the impregnated material to have viscosity of 25-15. 10<3> Pa.s (measured at 120 deg.C), the impregnated material of at least two layers is then piled up and heated under pressure until the resin is cured in a B-stage in a quantity to allow the resin to be still able to flow at a treatment temperature of 110-170 deg.C.

Description

Detailed Description of the Invention

[0001]

The invention relates to (1) impregnating a fibrous material in the form of a mat or fleece with an aminoplast resin mixture, wherein the fibrous material is in the form of a fleece or mat at room temperature from 0.1 MPa to 20 MPa. Has a tensile strength of
And (2) impregnating the material with the aminoplast resin mixture at 25 Pa. s-15.10 ³ Pa. It relates to a method for producing a sheet-like molding material (SMC) by drying until it has a viscosity of s (measured at 120 ° C.).

[0002]

Such a method is described in EP-A-304133. In the case of this European Patent Application Publication No. 304133, 35P
a. The material of the SMC layer made of a resin having a viscosity of s is
It is molded at a temperature of 260 ° C. and a pressure of 8.10 to ¹ N / m ² . This results in a product with reasonable properties, but this method suffers from the drawback that the SMC layer is difficult to handle, the final product shows surface scratches and does not have optimum mechanical strength. Indicated.

Aminoplast resins have properties that make them attractive for use in structural purposes. This aminoplast resin has significantly more flame retardant properties than unsaturated polyesters and is significantly more colorable than phenol formaldehyde resins.

[0004]

The object of the invention is that it can be treated in the same way as unsaturated polyester sheet molding compositions (UP-SMC), but with better handling properties and better mechanical quality. A sheet-shaped molding material based on the resulting aminoplast resin (SM
It is to provide a method for producing C). UP-SM
C is a surface shaped article that is almost dry at room temperature, has a significantly higher viscosity, and is liquid at increased temperature and pressure. This liquid state is important. This is because m, usually such an amount of SMC, is placed in a mold that covers only approximately 70% of the surface area of the mold.

[0005]

This problem is solved by (3) stacking at least two layers of the impregnated material thereafter, such that the resin is mixed with B in an amount such that the resin can still flow at a processing temperature of 110-170 ° C. It is solved by heating under pressure until the stage is cured.

Preferably, the processing temperature is 130 to 160 ° C.
Is.

Preferably, the layer is between 10 and 180 seconds
It is cured by heating to a temperature of 60 ° C to 100 ° C. More preferably, it is 20 to 30 seconds. Higher temperatures can result in undesirable curing. This is because the glass transition temperature of cured aminoplasts such as melamine-formaldehyde resins is about 11
This is because it is 0 ° C.

Preferably, a pressure of 5 to 50 bar is used, more preferably 15 to 45 bar and most preferably 5 bar.
Bars are used. Maintaining pressure during the entire cure process is unnecessary. Because the first reason for pressurization is to compress the stack of SMCs.

An additional advantage of the pressing process is that the material is easy to handle and the material has a smaller volume, which results in lower shipping costs.

It is an advantage to preheat the SMC in a preheating step (4) before processing the material. This can be done, for example, in a microwave oven or a high frequency (HF) oven. The water present in this step evaporates and the resin
It can also be slightly cured. It should be noted that SMC will not cure once the resin no longer flows at the processing temperature. If the material is processed immediately after the curing step (3), the preheating step (5) can be omitted.

The sheet-like molding material obtained after the curing step (3) can be easily processed into a product in the compression molding step (5). The pressure used for curing is usually 10-
Between 200 bar, preferably between 20 and 120 bar.

International publication number WO-A-82 / 03198
At room temperature is 10 to 500,000 Pa. The use of unsaturated polyurethane resins or unsaturated polyester resins having viscosities in the range of s is described. The method disclosed in International Publication No. WO-A-82 / 031998 is
It is directed to a combination of the resin with chopped fiber strands and an additional support material such as a thermoplastic film. International publication number WO-A-82 / 03
The surface shaped article described in 198 is suitable for vacuum forming to obtain the final product. It is stated that the use of a fibrous material in the form of a mat reduces the processability of the surface-shaped article.

The method described in EP-A-51060 is used to produce boards that are more or less foamed, with water present which partially serves as a foaming agent.

If the viscosity of the resin mixture and the tenacity of the fleece or mat of the fibrous material are chosen as a function of temperature, they are particularly suitable for processing in the same way as for UP-SMC. A certain aminoplast SMC
Is obtained.

The lower limit of the tensile strength of the fibrous material is determined by the strength required to withstand the forces generated when impregnating the fibrous material and during the post-treatment process, eg drying, rolling, winding, etc. . This required strength depends to some extent on the width and the thickness of the material, but in each case it can easily be determined and, in the case of the normally known machines, approximately. Greater than 0.1 MPa. Advantageously, fibrous materials are used which have a stronger strength, ie higher than MPa (measured at room temperature).

The viscosity of the fibrous material should be such that it pulls the fibrous material during molding. This is essential. This is because, as mentioned above, the mold only fills 30-80% of the surface area and during molding the material has to fill the whole mold. If the fibers do not flow along the residue of the material, a product with uneven mechanical properties is obtained. In the case of special protrusions, the ridges and rims are subjected to a relatively high force during the use of the product, and it is therefore important to include the fiber material in these ridges and rims as well. Therefore, the required viscosity of the resin mixture depends on the tensile strength of the fibrous material in SMC. This tensile strength depends on the strength of the bond between the filaments caused by the coating (or sizing) and can be influenced by the solvent and temperature present in the resin mixture. In relation to the minimum strength of the fiber material, the viscosity of the resin mixture is 120 Pa. must be greater than s (Brookfield viscosity). Aminoplast resins usually have a significantly lower viscosity under compression molding conditions,
Therefore, it does not meet the above requirements. A simple and inexpensive way is to use fillers in the resin.

The SMC obtained by the process according to the invention preferably comprises 5 to 85% by weight of fiber-reinforced material and 15 of a resin mixture.
~ 95% by weight, more advantageously fiber-reinforced material 15 ~
60% by weight and 40-85% by weight of resin mixture, particularly preferably 20-30% by weight of fiber-reinforced material and resin mixture 7
From 0 to 80% by weight.

The resin mixture preferably comprises 20 to 100% by weight of aminoplast resin, 0 to 80% by weight of fillers and additives such as 0 to 25% by weight of pigments. Even more advantageously, the resin mixture comprises aminoplast resins 30-8.
0 wt%, filler 10-70 wt% and additive 10-
With 20% by weight. Most advantageously, the resin mixture comprises 20-60% by weight filler. Particularly useful are mixtures which result in molding compounds having at least 30% by weight of filler.

The upper limit of the viscosity of the resin mixture depends on the processability and is about 15,000 Pa.s. s. Preferably 50 Pa. s-5000 Pa.s. viscosity of s (120 ° C
A resin mixture with) is used.

The upper limit of the viscosity of the resin mixture is about 20.
Determine the upper limit of the strength of the fiber material which is MPa. Preferably, a fibrous material having a strength of less than 10 MPa is used.

Aminoplast resins are used as resins. Urea, melamine or benzoguanamine can be used, for example, as aminoplasts. Melamine is preferably used because of its outstanding mechanical properties. This resin can be obtained by reacting aminoplast and formaldehyde in water by methods known to those skilled in the art. For example, the ratio of formaldehyde to melamine is usually 1.3 to 2.5, preferably 1.
5 to 2.0. If necessary, aminoplasts can be partially replaced, for example by phenol, but this can have an adverse effect on color. It is also possible to add plasticizers such as sorbitol, caprolactam, ethylene glycol, trioxitol, toluenesulfonamide and benzoguanamine and acetoguanamine.

Preferably, glass fibers are used as the fiber material, but other fibers are also suitable, for example rock fiber, carbon fiber, cotton, polyamide or cellulose. The fibrous material is usually used in the form of fleece or mat or 6-60 mm
It is used in the form of a mat with long filaments.

Chalk, clay, carbon, silica, aluminum trihydrate or metal particles can be used, for example, as a filler. Usually, the particles have a size of 2 μm to 1
It has a length of mm. Further, SMC is a catalyst, a release agent,
Coloring agents and other conventional additives can be included. Conventional catalysts such as p-toluenesulfonic acid and boric acid can be used as catalysts.

The amount of resin mixture used per 1 m ^{2 of} fiber mat or fleece can be easily adjusted, for example by removing the resin mixture with a roll. It can also be used more or less in fibrous materials to tailor the viscosity of the aqueous resin mixture.

To obtain dry SMC, most of the water is
It must be removed after the impregnation step. A residual moisture content of less than 5% seems to give good results. Too much free water can cause porosity in the final product. Water is the preheating step (4) before treating SMC,
Alternatively, it can be easily removed by passing the SMC through a furnace during other steps of the manufacturing process, such as during the drying step (2). Since no product is produced between the two films as in the case of polyester SMC, water can be fully evaporated over the entire surface.

The SMC obtained after impregnation usually has a thickness between 0.2 mm and 5 mm. Thinner products are economically unattractive, and thicker products have problems during drying and / or sticking together when rolled up. After the product has dried, this product is stacked and
A sheet-shaped molding material having a thickness of 1 mm to several centimeters is formed. The additional advantage of the SMC's pressurized stack is that it heats up more quickly and uniformly,
This avoids local hardening and results in better flow in the mould.

The product obtained has remarkably good mechanical properties and the fibrous material is dispersed throughout the product. Typical mechanical strengths for 30% by volume of glass fiber reinforced material with long fibers of 5 mm to 50 mm are as follows: bending strength of 100-200 MPa, 7-15.
GPa Modulus (ASTM-D790) and 5-70
Impact resistance of kJ / m ~ ² (ISO 179).

The SMC is outstandingly suitable for use in the production of large molded parts, for example with ribs and protrusions, such as chair seats, casings, mounting parts, body parts of motor vehicles. The excellent flame-retardant nature of the material, thermal stability, high heat deflection temperature, scratch resistance and good colorability are significant advantages for such applications.

The present invention will be described with reference to the following examples, but the present invention is not limited thereto.

[0030]

【Example】

Example I Resin Preparation In a reactor, 5 parts caprolactam, 24 parts water and 135 parts formalin (30% formalin in water having a pH of 9.4) were added to 100 parts melamine. The condensation reaction was carried out at 95 ° C. (formaldehyde / melamine ratio was 1.7) until the dilutability of the resin at 20 ° C. resulted in 1.2 kg resin / kg water. Example II Preparation of aminoplast SMC 110 parts CaCO ₃ (75% solids in water) and 0.45 parts paratoluenesulfonic acid (50% solids) were added to 100 parts resin of Example I (55% solids) in a vane mixer. ) Was added. The mixture was stirred until a homogenous mixture was obtained. The viscosity is 0.1 Pa.s. s (Brookfield viscosity at 20 ° C.).

The resin mixture is VITS type (LIA model)
Was poured into the bath of the impregnator. A glass fleece with a tensile strength of 1.1 MPa at 20 ° C. was passed through the bath with the resin mixture. The impregnated fleece was rolled into two rolls (0.
The excess resin mixture was removed by passing between 2 mm intervals). Then, the impregnated fleece 16
The resin mixture, which has been passed through the oven at a temperature of 0 ° C. for 120 seconds and then dried, has a viscosity of 35 Pa. It had a viscosity of s (Brookfield viscosity).

Example III Preparation of Aminoplast SMC 110 parts of aluminum trihydrate (100% solids) and 0.2 parts of paratoluenesulfonic acid in a vane mixer.
5 parts (50% solids) to 100 parts of the resin of Example I (55 solids)
%).

The mixture was stored until a homogeneous mixture was obtained. The viscosity was 0.5 Pa.s. s (Brookfield viscosity at 20 ° C.).

Resin mixture is VITS type (LIA model)
Was poured into the bath of the impregnator. A glass mat having a weight per unit area of 250 g / m ² was passed through the bath containing the resin mixture. By passing the impregnated mat between two rolls (1.3 mm spacing),
Excess resin mixture was removed. The impregnated mat is then passed through the oven for 120 seconds at a temperature of 140 ° C and 120
It was passed through the furnace at 120C for 120 seconds.

Test plate (size 20 × 25 × 0.14 cm)
Was manufactured and the mechanical properties of this test plate were measured. AST
The bending strength according to MD-790 was 160 MPa. The elastic modulus (ASTM-D790) was 12 GPa and the impact resistance (ISO 171) was 40 kJ / m ² .

COMPARATIVE TEST A Treatment of the final product without the curing step 3 20 layers of the SMC of Example II with a thickness of 0.3 mm are placed on the other top side and in a compression mold (Burghle design LA 63). 160
It was compressed at a pressure of temperature and 8.10 ~ ² N / m ² of ° C.. Glass fibers appeared to be present on all protrusions, ridges and rims.

Similarly, a test plate (size 25 × 25 ×
0.4 cm) was manufactured and the mechanical properties of this test plate were measured. Bending strength according to ASTM-D-790 is 100M
Pa and elastic modulus (ASTM-D790) is 10 GP
and has impact resistance (ISO179) of 15 kJ / m ²
Met. The Heat Deflection Temperature (HDT) was above 300 ° C. and the UL-94 flammability rating was V-0, although the limited oxygen index reached 40.

Example IV Precuring of Layer Stack to Stage B IVa A 6 layer stack of SMC obtained according to Example II was preheated in an oven at 80 ° C. for 3 minutes. The SMC stack was introduced into a Collin Roller. The distance between the rollers was 2.5 mm.

IVb A 4-layer stack of SMCs obtained according to Example III was heated at a temperature of 80 ° C. to a Fontijne Flatplate molder (TP 40).
0) and compressed under a pressure of 35 bar for 3 minutes.

In both cases the result is a rigid plate at room temperature, but is capable of flowing at higher temperatures and pressures.

With the Colin roller, the Fontijne Flatplate type molding machine (TP 4
00) with comparable results. The product obtained with the Corin roller had a low air entrapment.
One roller had the additional advantage that it could be used in a continuous industrial process.

Blisters in the final product are less frequent because a small amount of air is trapped. Further, the sheet-like material is almost free from dirt.

The plate is the SM used to obtain this plate
It had a lower water content than that of C. Also, the amount of air trapped in the plate was reduced.

Instead of heating in a furnace and compacting in a Colin roller or flat plate molder as described in the examples, it is also possible to use, for example, a double belt molder. More industrial production is advantageous.

Example V Flow Test of Layer B Stage Stacks Six sheets of 40 × 10 cm (Schuellercombimat, Microlith® 021/031/92) of impregnated glass mats were prepared from Examples IIIa-i. ).

The compressed plates were cut into 10 × 10 cm samples and introduced into a Renault flow molding tool to test the flow behavior of the plates and compare them with the uncompressed plates. The Renault flow molding mold exerted a pressure of 70 bar for 3 minutes at a temperature of 150 ° C.

The results show that the pre-cured material has even better flow behavior than the uncured material. In the final product, there are no striped markings when the material is introduced into the mould.

Example VI Preparation of final product from a pre-cured stack of layers VI The plate obtained according to Example IVa was manufactured by Panasonic (Panasoni).
c) microwave generator 1760, output 1600W,
Precured in 150 seconds.

From the preheated plate, 730 g was introduced into a mold for a fry tray having a temperature of 150 ° C. and pressed with a clamping force of 2800 kN for 2 minutes. After 30 seconds of the degassing step, the plate was left. This example was repeated 4 times. It has been found possible to manufacture the final product in a reproducible manner.

The impact resistance of the final product was remarkably good. No bending occurred and the dimensional stability was remarkably good. The Barcol hardness was between 60 and 65.

In the case of a washing test in a washing machine, the finished plate can be washed very well and gives a dry feel after removal. This is an important advantage compared to, for example, polyester products. For example, if it is desired to use such products as trays in the food sector, then such trays must be washable. Polyester trays give a tacky feel after washing due to their water absorption.

The chemical resistance was tested with different cleaning materials and different types of foodstuffs and was found to be remarkably good as follows: no surface damage could be found.

Example VII Microwave Preheating Step The preheating step of Example VI was carried out using the Gigatherm (Switzerland) method.
m) Microwave generator from GM Mammut. In this machine, 4 kg of material were heated at 3000 W for 2 minutes to 100 ° C.

Example VIII Preheating Step Using High Frequency The preheating step of Example VI was carried out by
rfurth) high frequency generator. This same device can be used for the compression of the material. Using the generated 10kW HF, material 10kg
Was heated to 90 ° C. for 2 minutes.

Example IX Completion of a surface with a decorative top layer In the case of the method described in Example VI, the mold was opened after pressing and impregnated with melamine formaldehyde according to Example 1,
Paper sheet material (decorative paper) catalyzed to a pH of 8.0
Was placed on top of the pressurized stack of layers and pressed for a few seconds. As a result, a finished product having a good surface appearance was obtained. The adhesion between SMC and the paper laminate was remarkably good.

Example X Manufacture of the finished product MF-SMC with short glass fibers (3-6 mm),
AlOH ₃ as a filler and TiO ₂ as a pigment were used to give a weight of 7.5 k according to the method described in Examples IV and VI.
Pressurized in the form of a kitchen sink of g. Degasification was not used.

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[Procedure amendment]

[Submission date] October 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 9

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

The object of the invention is that it can be treated in the same way as unsaturated polyester sheet molding compositions (UP-SMC), but with better handling properties and better mechanical quality. A sheet-shaped molding material based on the resulting aminoplast resin (SM
It is to provide a method for producing C). Aminoplast-SMC is a surface shaped article that is almost dry at room temperature, has a significantly higher viscosity, and is liquid at increased temperature and pressure. This liquid state is important. That's usually because this amount of SMC
Because it is placed in a mold that covers only approximately 70% of the surface area of the mold.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Aminoplast resins are used as resins. Urea-formaldehyde or melamine-formaldehyde can be used, for example, as aminoplasts. Melamine is preferably used because of its outstanding mechanical properties. This resin can be obtained by reacting aminoplast and formaldehyde in water by methods known to those skilled in the art. For example, the ratio of formaldehyde and melamine is usually 1.3-
2.5, preferably 1.5 to 2.0. If necessary, aminoplasts can be partially replaced, for example by phenol, but this can have an adverse effect on color. It is also possible to add plasticizers such as sorbitol, caprolactam, ethylene glycol, trioxitol, toluenesulfonamide and benzoguanamine and acetoguanamine.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Example IV Precuring of Layer Stack to Stage B IVa A 6 layer stack of SMCs obtained according to Example III was preheated in an oven at 80 ° C. for 3 minutes. The SMC stack was introduced into a Collin Roller. The distance between the rollers was 2.5 mm.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

Example V Flow test of a B-stage stack of layers V. 6 sheets of 40 × 10 cm (Schueller combi mat,
Microlith (registered trademark) 021/031/9
2) was compressed in the choliner roller described in Example IVa).

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

Example X Manufacture of Finished Goods 25-50 mm, as commonly used in SMC molding processes
Fiber with a length of 3 to 6 mm, M with AlOH ₃ as filler and TiO ₂ as pigment
The F-SMC was pressed in the form of a kitchen sink weighing 7.5 kg by the method described in Examples IV and VI. Degasification was not used.

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Claims (11)

[Claims] 1. A fibrous material in the form of a mat or fleece is impregnated with an aminoplast resin mixture, the fibrous material having a tensile strength of 0.1 MPa to 20 MPa at room temperature, and (2). The impregnated material was treated with the aminoplast resin mixture at 25 Pa. s-15.10 ³ Pa. s (12
A method of producing a sheet-like molding material (SMC) by drying until it has a viscosity of (measured at 0 ° C.), (3) after which at least two layers of impregnated material are stacked and the resin is still 110- A process for producing a sheet-shaped molding material, characterized in that the resin is heated under pressure until the resin is cured in stage B in an amount such that it can flow at a processing temperature of 170 ° C. 2. The layer at a temperature of 60 to 100 ° C. for 10 seconds to 1
The method of claim 1, wherein the heating is for 80 seconds. 3. The method according to claim 1, wherein the layer is heated under a pressure of 5 bar to 50 bar. 4. The sheet-shaped molding material is a resin mixture 30-9.
The method according to any one of claims 1 to 3, which comprises 5% by weight and 5 to 70% by weight of fibrous material. 5. The resin mixture after drying has a viscosity of 50 Pa.s. s ~
5000 Pa. Method according to any one of claims 1 to 4, having a viscosity of s. 6. The method according to claim 1, wherein the fibrous material has a strength (at 20 ° C.) of 1 MPa to 10 MPa. 7. The resin mixture comprises 10 to 70% by weight of filler,
30-80% by weight of aminoplast resin and 10 additives
7. A method according to any one of claims 1 to 6 containing from -20% by weight. 8. Use of glass fibers as the fiber material,
Method according to any one of claims 1 to 7. 9. The method according to claim 1, wherein melamine is used as the aminoplast. 10. A mixture of at least two layers of aminoplast resin mixture and a fibrous material, wherein the resin mixture is 25 Pa. s to 15.1
0 ³ Pa. and has a viscosity of s, and the fibrous material is in the form of a fleece or mat at 20 ° C.
A stack of sheet-form molding materials having a strength of 1 to 3, characterized in that the stack is such that the resin is still able to flow at temperatures of 110 to 170 ° C. Stacks of. 11. A molded article obtained using the method according to any one of claims 1 to 9 or a product obtainable by this method.