JPS62109615A - Manufacturing process for unsaturated polyester resin molded product utilizing melamine resin as surfacing - Google Patents

Abstract

PURPOSE:To manufacture a molded product having marble-like pattern and hardness by monolithically molding the resin composition comprising unsaturated polyester resin blended with polymethyl methacrylate of specific molecular weight, aluminum hydroxide and ethylene unsaturated monomer utilizing melamine resin as surfacing. CONSTITUTION:Resin composition comprising ethylene unsaturated monomer consisting of '(a) unsaturated polyester resin normally used, (b) polymethyl methacrylate carrying 50,000-500,000 weight-average molecular weight, (c) aluminum hydroxide carrying such crystallographic structures as gibbsite, boemite or bayerite and (d) styrene, vinyltoluene and the like', each blended at specific ratio, and the melamine resin impregnated solution having melamine resin coverage 50-70wt% are loaded in the mold and pressing molded to manufacture a molded product having marble-like pattern and hardness.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an unsaturated polyester resin that has excellent workability and processability during molding, and has excellent mechanical strength, thermal shock resistance, transparency, etc. of molded products. By heat-pressing and integrally molding the composition and melamine resin-impregnated paper with various colors and patterns, it has an astronomical stone-like transparency and a variety of colors and patterns, as well as high surface hardness, mechanical strength, and heat resistance. The present invention relates to a method for manufacturing a molded article having impact resistance.

[Conventional technology]

Demand for plastic trays, plates, and other tableware, top materials for tables, kitchen counters, and interior/exterior wall materials, for which demand has been increasing in recent years, is filled with unsaturated polyester resins, mainly inorganic fillers such as calcium carbonate. Molding materials such as SMC (sheet molding compound) and BMC (parc molding compound), which are blended with wood and glass fiber, are used.

These molding materials have extremely excellent mechanical strength, but on the other hand, wet molding materials containing a high content of ethylenically unsaturated monomers, which are mainly styrene and are liquid at room temperature, Since the content of saturated monomers is approximately 6 to 20 parts), it is not only difficult to handle during molding, but also the molding material may be damaged due to volatilization of monomers and progress of reactions during work and storage. It has the drawback that it causes changes in flow and hardening characteristics, and that the so-called moldability is unstable. In addition, the resulting molded products have the disadvantage of lacking in variety of patterns and transparency.゛These SMC
+BMC and other wet molding materials are unstable in handling and molding processability during molding, so-called dry molding materials (e.g. By controlling the content of the ethylenically unsaturated monomer in the molding material to less than 5% by weight, the performance can be greatly improved. However, molded products obtained from commercially available dry unsaturated polyester resin molding materials have low surface hardness and are easily damaged. It has the disadvantage that it is not sufficiently satisfactory in terms of clear transparency and diversity of colors and patterns, and is not used for the above-mentioned purposes.

[Problem that the invention seeks to solve]

As a result of intensive studies in view of the above-mentioned circumstances, the inventors of the present invention have decided to use an unsaturated polyester resin as the resin, add a specific thermoplastic polymer and an inorganic filler to this resin, and add a small amount of ethylene as necessary. Compositions containing sexually unsaturated monomers have excellent handling properties and molding stability.
This composition and melamine resin-impregnated paper having various colors and patterns are simultaneously heated and pressed using a molding die to give a molded article with excellent transparency, thermal shock resistance, and mechanical strength.
The present inventors have discovered that by integrally molding, in addition to the characteristics of the polyester resin composition described above, molded products having high surface hardness and a variety of colors and patterns can be obtained, and the present invention has been completed.

[Failure to solve the problem]

That is, the present invention provides (3) (a) an unsaturated polyester resin, (b) a polymethyl methacrylate having a weight average molecular weight of 50,000 to 500,000, (c) aluminum hydroxide, and (d) an ethylenically unsaturated monomer. and a weight ratio of the (a) component to the (b) component is 70:30 to 90:10, and the total amount of the (a) component and (b) component is ) an unsaturated polyester resin composition in which the weight ratio of components is from 10:90 to 35:65, and the proportion of component (d) in the composition is at most 5 weight range; (B) melamine resin adhesion; Melamine resin-impregnated paper with a weight of 50 to 70% is placed in a preheated mold (
B) is placed so that the surface is in contact with the mold surface, and then (A
) f: unsaturated, (PIJ ester resin molded product manufacturing method) using a melamine resin as a surface material obtained by loading and pressure molding.

[Effect]

In the present invention, the unsaturated polyester resin as the component (A) used in the production of the unsaturated 151J polyester resin composition is an unsaturated dibasic acid or an unsaturated dibasic acid and a saturated dibasic acid. It is an ordinary unsaturated polyester resin obtained by reacting a dibasic acid component and a glycol component.

Examples of the unsaturated dibasic acids used above include maleic anhydride, fumaric acid, ntraconic acid, itaconic acid, and -logonated fumaric acid. In addition, saturated dibasic acids include phthalic anhydride, isophthalic acid, terephthalic acid,
Examples include tetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, het acid, and nologonated phthalic anhydride.

On the other hand, examples of the glycol component used above include ethylene glycol, soropylene glycol, 1,3-butanediol, neopentyl glycol, hydrogenated bisphenol A, glycerin, and trimethylene glycol. Two or more of each of the unsaturated dibasic acids, saturated dibasic acids, and glycol components may be used in combination. The method for synthesizing unsaturated polyester is not particularly limited, and it is produced by a conventionally known method.

In addition, the polymethyl methacrylate of component (b) is a polymer of methyl methacrylate, and has a weight average molecular weight of 50.00.
0 to 500.000, preferably ioo, oo.

~300,000.

The method for synthesizing polymethyl methacrylate is not particularly limited, and it can be produced by a conventional synthesis method.

The weight average molecular weight of polymethyl methacrylate is 50.00
If it is less than 0, the molded product obtained from the composition blended with this has the drawback of low bending strength and surface hardness. On the other hand, the weight average molecular weight of polymethyl methacrylate is 500,
If it exceeds 000, the effect will be similar to that of increasing the amount of filler, and sufficient impact resistance and thermal shock resistance will not be obtained.

The blending amount of polymethyl methacrylate is 70:30 in weight ratio of unsaturated polyester resin and polymethyl methacrylate.
~90:10, preferably 75:25 to 85:15.

If the blending ratio of polymethyl methacrylate is less than 10 by weight, the thermal shock resistance will not be sufficient and cracks will occur due to repeated local heating and cooling of the molded product. 30 in weight ratio
If the temperature is exceeded, the heat resistance of the resulting molded product will decrease, and the molded product may become uneven due to high-temperature heating, or the molded product may become curved or curved.
There is a drawback that warping occurs.

In the present invention, polymethyl methacrylate was specifically selected because it meets the purpose of the present invention in terms of the balance of various performances such as mechanical strength, surface hardness, thermal shock resistance, weather resistance, and transparency of the molded product. However, even if other thermoplastic polymers are added to the unsaturated polyester resin, the same effect as polymethyl methacrylate in terms of the balance of the above-mentioned performance is not observed.

The aluminum hydroxide of component (c) of the present invention has a gibbsite crystal structure, a boehmite crystal structure, and a guiarite crystal structure, all of which are industrially produced as raw materials for aluminum. ing. When implementing the present invention, it is desirable to use K having a gibbsite crystal structure in consideration of the thermal decomposition temperature of aluminum hydroxide. Its thermal decomposition temperature is 16
The temperature is 0°C or higher. Moreover, those having an average particle diameter of 100 microns or less are preferable, and those of 0.5 to 70 microns are particularly optimal.

The amount of aluminum hydroxide blended is within the range of 10:90 to 35:65 in weight ratio of the total amount of unsaturated polyester resin and polymethyl methacrylate to aluminum hydroxide.

If the blending ratio of aluminum hydroxide exceeds 90% by weight, there will be an excess of filler, and the kneading properties of the composition will decrease, and the fluidity of the resulting composition will also drop significantly, making it difficult to form it satisfactorily. become unable. On the other hand, if the weight ratio of aluminum hydroxide is less than 65, the mechanical strength and surface hardness of the molded product will decrease rapidly, and the shrinkage rate during curing will increase, causing the molded product to warp. This may cause some inconvenience.

In addition to aluminum hydroxide, fillers include inorganic fillers such as calcium carbonate, silica, clay, asbestos, barium sulfate, and mica, and organic fillers such as starch flour and wood flour. If other fillers are used alone or in combination, they have the disadvantage of reducing the transparency of the molded product, and in order to obtain the desired transparency, it is necessary to use aluminum hydroxide as the filler. .

In the present invention, an ethylenically unsaturated monomer may be added as component (d) if necessary. Ethylenically unsaturated monomers include styrene, vinyltoluene, divinylbenzene, methyl methacrylate, diallylphthalate,
Suitable examples include those that are liquid at room temperature, such as triallyl cyanurate.

Two or more of these ethylenically unsaturated monomers may be used in combination.

The ethylenically unsaturated monomer is used within the range permitted as a dry molding material, ie its proportion in the composition is at most 5% by weight. If the proportion of the ethylenically unsaturated monomer in the composition exceeds 5% by weight, the pulverization properties in the pulverization process during the production of the composition may deteriorate, or the composition may form sheets or flakes during storage. The composition is blocking (
The problem is that the workability during molding is significantly reduced due to solidification.

In the unsaturated & IJ ester resin composition used in the present invention, a polymerization initiator, a mold release agent, a stabilizer, a coloring agent, an inorganic fiber reinforcing agent, an organic fiber reinforcing agent, etc. are used as necessary.

The unsaturated polyester resin composition used in the present invention is easily produced by mixing or kneading the ingredients using a general-purpose kneader, extruder, roll mill, or the like. The resulting block, sheet, or flake composition can be easily molded into any shape by compression molding.

The melamine resin-impregnated paper of component (B) used together with the unsaturated polyester resin composition in the present invention is obtained by impregnating an overlay paper with a desired color and pattern with a melamine resin and drying it. The amount of coating needs to be adjusted within the range of 50 to 70% by weight.

If the amount of melamine resin applied is less than 50% fi: 1, the surface of the molded product will have poor gloss and a molded product with a good appearance will not be obtained.
-1 If the coating amount exceeds 70 needles, the fluidity during molding will be good, but the melamine resin-impregnated paper will be damaged during processing, resulting in the difficulty of obtaining a molded product with a good appearance.

By loading the unsaturated polyester resin composition and melamine resin-impregnated paper into a mold and integrally molding them, melamine-impregnated paper can be obtained in addition to the excellent mechanical strength, thermal shock resistance, and transparency of the unsaturated polyester cured product. Molded products with high surface hardness and beautiful colors and patterns of the cured product can be easily obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

In addition, each physical property value in Examples and Comparative Examples was measured according to the following method.

(1) Bending strength: According to JISK6911.

(■) Charpy impact strength: According to JISK6911.

(IID Surface hardness (pencil hardness): JISK54
According to 00.

(Foundation) Thermal shock resistance: Place a small iron heated to 200℃ on a test piece (200x200x3%) kept at 20℃, remove it after 5 minutes, observe the appearance with the naked eye, and rank it as follows. .

○ Good △ Unevenness × Cracks (■ Transparent) Nippon Denshoku Kogyo ■ Color measurement color difference meter (
A test piece (thickness 10
% flat plate) and judge by the presence or absence of transmitted light.

Examples 1 to 8 and Comparative Examples 1 to 10 [Manufacture of unsaturated polyester resin composition] Unsaturated polyester resin, polymethyl methacrylate, aluminum hydroxide, calcium carbonate, styrene monomer, glass fiber (1/4 inch), Dicumyl peroxide, stearic acid and hydroquinone are weighed and blended in the proportions shown in Table 1. 10 volumes of each formulation! After mixing in a pressure kneader for about 5 minutes at 100 to 110°C, the mixture is passed through a roll mill with a diameter of 10 inches to form a sheet. After cooling, the mixture is crushed in a crusher having a 10% screen to obtain a flaky composition. In Comparative Example 5, kneader kneading properties were poor and a uniform composition could not be obtained. Comparative Example 8 had poor pulverizability and could not be pulverized, but the compositions of the other Examples and Comparative Examples all had good kneader kneading and pulverizing properties.

[Manufacture of melamine resin impregnated paper]

Using a melamine resin-impregnated paper manufacturing machine (which can perform impregnation, drying, and cutting in succession), overlay paper printed with a desired color or pattern is impregnated with melamine resin varnish and dried at a temperature of 90 to 100°C to produce the results shown in Table 1. A melamine resin-impregnated paper having a resin adhesion resistance shown in is obtained. The obtained product is cut into specified dimensions (500 x 500'A) using a cutter, then packaged in polyethylene bags (50 pieces each), placed in a cardboard box, sealed with Surion Tezo, and stored.

[Manufacture of unsaturated polyester resin molded products using melamine resin as surface material]

The melamine resin-impregnated paper produced above was placed in a preheated molding mold so that its surface was in contact with the inside of the mold, and then the unsaturated polyester resin composition was loaded and heated and pressurized to obtain a paper with dimensions of 400 x 200%. , a flat plate with a thickness of 10% was molded. Various test pieces were cut out from the rice plate and used as samples. The molding conditions were as follows.

Molding machine: Toho Press Seisakusho Model TD-5100) Compression molding machine Mold temperature: 155±3℃ Molding pressure 100 kg/Cm2 Curing time: 5 minutes Using each test piece obtained, bending strength, Chassis impact strength, surface hardness, thermal shock resistance and transparency were measured.

The results are shown in Table 1.

In Comparative Example 9, uneven gloss occurred on the surface of the molded product, and a molded product with a good appearance could not be obtained. Furthermore, in Comparative Example 10, the melamine-impregnated paper was damaged by the pressure applied during molding, and similarly a molded product with a good appearance could not be obtained.

The components used in the Examples and Comparative Examples are as follows.

(1) Unsaturated polyester resin Unsaturated polyester resin obtained from 1.1 mol of propylene glycol, 0.7 mol of fumaric acid, and 0.3 mol of isophthalic acid, manufactured by Showa Kobunshi ■ (2) f! Methyl remethacrylate A weight average molecular weight approximately 200. OOO
1 Manufactured by Mitsubishi Rayon ■ (3) Methyl methacrylate B Weight average molecular weight approximately 30,000, manufactured by Mitsubishi Rayon ■ (4
) Polymethyl methacrylate C ゛Weight average molecular weight approx. Calcium average particle size 2.2 microns, manufactured by Bihoku Funka Kogyo ■ (8) Glass fiber manufactured by Nitto Boseki ■ (9) Zinc stearate manufactured by Nippon Oil & Fats ■ (11 Dicumil Tsuk - Oxide manufactured by Nippon Oil & Fats ■ → Hydroquinone manufactured by Kawaguchi Chemical ■ 0 Melamine resin-impregnated paper made by Showa Kobunshi■ From Table 1, the molded products of Examples 1 to 8 have a good balance of bending strength, Charpy impact strength, surface hardness, thermal shock resistance, transparency, and molded product appearance. It can be seen that the molded products are superior to the molded products of Comparative Examples 1 to 10.

〔Effect of the invention〕

The method of the present invention has excellent workability and processability during molding, and the molded products obtained have an astronomical stone-like transparency and a variety of color patterns, as well as high surface hardness, mechanical strength, and impact resistance. Owned.

Claims (1)

[Scope of Claims] (A) (a) Unsaturated polyester resin (b) Weight average molecular weight of 50,000 to 500,000
A composition comprising polymethyl methacrylate (c) aluminum hydroxide, and (d) an ethylenically unsaturated monomer, the weight ratio of components (a) and (b) being 70:30 to 90. and the weight ratio of the total amount of component (a) and component (b) to component (c) is 10:90 to 35:65, and the proportion of component (d) in the composition is An unsaturated polyester resin composition having an amount of at most 5% by weight, and (B) a melamine resin-impregnated paper having a melamine resin adhesion amount of 50 to 70% by weight are placed in a preheated mold.
A method for producing an unsaturated polyester resin molded article using a melamine resin as a surface material, which is obtained by placing (A) so that the surface thereof is in contact with a mold surface, and then loading and pressure molding (A).