JPH05138676A - Manufacture of unsaturated polyester resin molded item - Google Patents

Abstract

PURPOSE:To provide a method wherein an unsaturated polyester resin molded item with excellent transparent feeling, deep feeling and surface smoothness, with very little cracks and with large mechanical strength can be efficiently obtd. CONSTITUTION:In a method for producing a molded item 1 having a bottom face part 1a and a rising face part 1b by molding a resin compsn. contg. an unsatd. polyester resin as a base under heating and pressing, molding under heating and pressing is performed in such a way that the temp. of a part of a mold which is brought into contact with the surface of the rising face part 15 is made 5-30 deg.C lower than the temp. of a part of the mold which is brought into contact with the surface of the bottom face part 1a and at the same time, the temp. of a part of the mold which is brought into contact with the rear face of the rising face part 1b is made 5-30 deg.C lower than the temp. of a part of the mold which is brought into contact with the rear face of the bottom face part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an unsaturated polyester resin molded product by a heat and pressure molding method, and more particularly to a molded product having a bottom surface part and a rising surface part continuous with the bottom surface part, which has a smooth surface. , A method of producing a molded article having excellent transparency and a feeling of depth and high mechanical strength.

[0002]

2. Description of the Related Art A product obtained by a heat and pressure molding method using a molding material based on an unsaturated polyester resin is excellent in surface smoothness, transparency and depth, and has sufficient mechanical strength. Have. Therefore, the molded products as described above have been widely used in sanitary products such as bathtubs and washstands. However, when an unsaturated polyester resin is used as a base material and a molding material composed of an inorganic filler, an aggregate, a curing agent, an internal mold release agent and a pigment is used to obtain a molded article by a heating / pressurizing molding method,
In particular, there is a problem that cracking occurs due to curing shrinkage or curing heat generation when molding is performed in a high temperature region. In particular, when a three-dimensional molded product having a bottom surface portion and a rising surface portion connected to the bottom surface portion is to be obtained, cracks due to the curing shrinkage or curing heat generation frequently occur in the rising surface portion where the molding material is difficult to spread sufficiently. There is also a problem that not only the cracks described above occur but also unevenness occurs on the surface outside the rising surface portion.

In order to prevent the above-mentioned cracks due to curing shrinkage or curing heat generation, a method of adding, for example, a heat-expandable polymer as a low-shrinking agent to a molding material is known (see, for example, Japanese Patent Application Laid-Open No. 2000-242242). 63-212515). However, when the low-shrinking agent as described above is added to the molding material, the transparency of the molded product tends to be impaired due to the difference in the refractive index with other components or due to diffuse reflection of light. In addition, there are problems that the physical properties of the molded product deteriorate and the cost increases. Therefore, as a method for producing an unsaturated polyester resin molded article excellent in transparency or depth as described above, the above heat and pressure molding method is not widely adopted industrially, and the productivity is low. At present, the up method is used.

[0004]

Therefore, an object of the present invention is to eliminate the drawbacks of the conventional method for producing an unsaturated polyester resin molded article based on the heating and pressurizing method, and to add a low shrinkage agent. It is an object of the present invention to provide a method for efficiently producing an unsaturated polyester resin molded article excellent in transparency or depth of feeling, without any need.

[0005]

According to the present invention, a resin composition containing an unsaturated polyester resin, an inorganic filler and a curing agent is heat-pressed to form a bottom surface portion and a rising surface portion continuous with the bottom surface portion. In the method for obtaining a molded article having the method, the temperature of the mold part in contact with the surface of the rising surface part is lower than the temperature of the mold part in contact with the surface of the bottom part by 5 to 30 ° C., and the back surface of the rising surface part is contacted. It is characterized in that the temperature of the molding die portion to be heated is lower than the temperature of the molding die portion contacting the back surface of the bottom surface portion by 5 to 30 ° C. to carry out the heating and pressure molding. Hereinafter, the details of the manufacturing method of the present invention will be described.

Unsaturated Polyester Resin The unsaturated polyester resin used in the present invention contains an unsaturated polyester and a polymerizable monomer. Such an unsaturated polyester resin is generally an unsaturated polyester 5 obtained by reacting an acid component which is an α, β-unsaturated dibasic acid and / or its acid anhydride with a polyhydric alcohol component.
It is obtained by dissolving 0 to 80 parts by weight in 50 to 20 parts by weight of the polymerizable monomer. If the amount of unsaturated polyester is less than 50 parts by weight, it is difficult to obtain a molded product having sufficient strength, while if it exceeds 80 parts by weight, moldability and workability tend to be deteriorated.

Examples of the α, β-unsaturated dibasic acid include maleic acid, fumaric acid, itaconic acid, ditraconic acid, chloromaleic acid, and the like. Good. As polyhydric alcohol,
For example, ethylene glycol, diethylene glycol,
Propylene glycol, dipropylene glycol, 1,
3-butanediol, neopentyl glycol, 1,6
-Hexanediol, triethylene glycol, hydrogenated bisphenol A, isopentyl glycol, glycerin, trimethylolpropane, dicyclopentadiene and the like can be mentioned, and two or more kinds of these polyhydric alcohols may be used in combination.

If necessary, a saturated dibasic acid and / or its acid anhydride may be used as the acid component.
As the saturated dibasic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, succinic acid, azelaic acid,
Examples thereof include adipic acid, tetrahydrophthalic acid, hexahydrophthalic acid, chlorendic acid, tetrachlorophthalic acid, tetrabromophthalic acid and the like. The unsaturated polyester resin is obtained by dissolving the above unsaturated polyester in a polymerizable monomer, and as the polymerizable monomer, styrene, vinyltoluene, divinylbenzene, α
-Methylstyrene, chlorostyrene, dichlorostyrene, vinyl acetate, diallyl phthalate, diallyl isophthalate, vinyl monomers that can be crosslinked with unsaturated polyesters such as diallyl terephthalate, or vinyl oligomers, but usually styrene It is preferably used.

Inorganic Filler In the resin composition used in the method of the present invention, an inorganic filler is blended with the unsaturated polyester resin. Examples of the inorganic filler include calcium carbonate, magnesium carbonate, barium sulfate, talc, clay, mica, silica, alumina, glass powder, aluminum hydroxide, magnesium hydroxide, cold water stone, silica sand and the like. In particular, it is preferable to use glass powder, aluminum hydroxide or the like in order to enhance the transparency when cured. The blending ratio of the inorganic filler can be selected in a wide range, and generally, it may be determined in consideration of economical efficiency, workability, strength of the product, etc. It is preferable to set it as a ratio.

Hardener As a hardener, t-butyl peroxybenzoate,
Benzoyl peroxide, methyl ethyl ketone peroxide, t-butylperoxy-isopropyl carbonate, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-di-t-butylperoxycyclohexane, etc. Examples thereof include organic peroxides that act on the saturated polyester, and it is preferable to use it in the range of 0.5 to 3 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin (unsaturated polyester and polymerizable monomer). it can.

Other Additive Components The resin composition used in the present invention contains the above-mentioned unsaturated polyester resin, inorganic filler and curing agent, but when an actual molded product is obtained, the above-mentioned unsaturated composition is used. Thermosetting resin other than unsaturated polyester, low shrinkage agent, internal mold release agent, thickener, reinforcing material, etc. are required in the resin composition obtained by kneading polyester resin, inorganic filler and curing agent. Mixed accordingly.

Examples of the low-shrinking agent include thermoplastic resins such as polyethylene, polystyrene and saturated polyester, and polybutadiene rubber. When used, a small amount is used so as not to impair the transparency of the molded product. preferable.
Examples of the internal release agent include higher fatty acids such as stearic acid and zinc stearate, esters of the fatty acids, and alkyl phosphates, and the amount is 0.5 to 100 parts by weight of the unsaturated polyester resin. It can be used in a ratio of 5 parts by weight.

The thickener is chemically bonded to a hydroxyl group, a carboxyl group, an ester group, or the like of the unsaturated polyester to form a linear or partially cross-linked bond to increase the molecular weight, thereby increasing the unsaturated polyester resin. Thickeners, for example, diisocyanates such as toluylene diisocyanate; metal alkoxides such as aluminum isopropoxide and titanium tetrabutoxide; oxidation of divalent metals such as magnesium oxide, calcium oxide and beryllium oxide. Substances: Divalent metal hydroxides such as calcium hydroxide are used. Generally, magnesium oxide and calcium oxide are used.
The amount used is usually 0.5 to 10 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin.

Examples of the reinforcing material include glass fibers, organic fibers such as polyester, phenol and vinylon, and carbon fibers. Generally, glass fibers are used. The amount used can be appropriately determined within a wide range in consideration of desired strength, viscosity and the like. In addition, a pigment or the like can be added in an appropriate amount as needed to impart color. Any pigment may be used as long as it does not significantly impair the curing of the unsaturated polyester resin.

[0015] molding the molding material, the resin composition was adjusted, be prepared thickened by cold or heat wrapped in a polyethylene laminate cellophane in order to prevent volatilization of the volatile components of the resin composition, a relatively hard It is clay-like and can be stored for a long period of time as a lump or plate in a cool and dark place. In preparing the molding material, the viscosity may be adjusted by leaving it at room temperature for, for example, about 24 to 72 hours. When heating, the temperature at which the life of the molding material is not impaired, for example, 35 to 60 ° C. It can be easily carried out by aging at a temperature within the range.

At the time of molding, the above resin composition prepared to have a relatively hard viscosity is charged into a molding die and heated and pressurized to polymerize and cure to obtain a molded product. Each step of the heating / pressurizing method itself is easily performed according to the procedure of the heating / pressurizing method known in the related art. For example,
Immediately after the preparation or previously prepared and stored in a cool and dark place, the molding material is charged into a desired mold, and the mold is clamped.
2 for the temperature range of 170 ° C and the projected area of the molded product
After heat and pressure molding in the pressure range of 0 to 200 kg / cm ² , by releasing the molded product from the molding die,
A desired molded product can be obtained.

A feature of the present invention is that the temperature of the mold contacting the surface of the rising surface portion (the surface required to have a good appearance as a product) in the above heating and pressurizing is the temperature of the mold portion contacting the surface of the bottom surface portion. 5 to 30 ° C., preferably 10 to 20 ° C. lower than the temperature, and the temperature of the mold part contacting the back surface of the rising surface part is 5 than the temperature of the mold part contacting the back surface of the bottom surface part. The heating and pressure molding is performed by lowering the temperature by -30 ° C, preferably by 10-20 ° C. In this way, by lowering the temperature of the mold part in contact with the rising surface portion, it is possible to delay the curing of the rising surface portion, whereby the curing shrinkage is absorbed by the fluid portion during curing, It is possible to prevent the occurrence of cracks due to curing shrinkage or curing heat generation at the corner portion between the bottom surface portion and the rising surface portion.

More preferably, not only a temperature difference is provided between the temperature of the mold part in contact with the rising surface part and the temperature of the mold part in contact with the bottom surface part, but also in each of the rising surface part and the bottom part. By making the temperature of the mold part contacting the front side of the product higher by about 5 ° C to 15 ° C than the temperature of the mold part contacting the back side, the curing shrinkage on the surface side of the molded product is reduced. It is possible to more surely prevent the occurrence of cracks and irregularities on the surface of the molded product by absorbing it in the fluid part during curing.

Further, in the manufacturing method of the present invention, as the molding process progresses, the upper mold of the mold is brought closer to the lower mold, and therefore, the molding material is molded under the condition that the molding material is always pressurized. It is difficult for resin to leak from. Further, the resin composition containing the pigment exists in a high viscosity state in the molding die, and when viewed as the molding material as a whole, the unsaturated polyester resin and the inorganic filler and other components flow and cure uniformly without separation. .. Therefore, an unsaturated polyester resin molded article which can be molded at high temperature and high speed, is excellent in transparency or depth, is clear, has excellent surface smoothness, and has high mechanical strength can be obtained.

[0020]

In the manufacturing method of the present invention, the unsaturated polyester resin molded product can be obtained by the heat and pressure molding method, so that the unsaturated polyester resin molded product can be efficiently manufactured. Further, the temperature of the molding die portion in contact with the surface of the rising surface portion is lower than the temperature of the molding die portion in contact with the surface of the bottom surface portion by 5 to 30 ° C., and the temperature of the molding die portion in contact with the back surface of the rising surface portion is Since the above-mentioned heat and pressure molding is performed in a state of being lower than the temperature of the mold part which is in contact with the back surface of the bottom surface portion by 5 to 30 ° C., curing of the rising surface portion is delayed as compared with the bottom surface portion, and thereby curing shrinkage occurs. However, since it is absorbed by the fluid portion during curing, the generation of cracks due to curing shrinkage or curing heat generation at the corners between the rising surface portion and the bottom surface portion is reliably prevented.

[0021]

EXAMPLES The production method of the present invention will be described below with reference to examples. Example 1 A resin composition was prepared by blending the following composition using an unsaturated polyester resin as a matrix resin. Unsaturated polyester resin (manufactured by Nippon Yupica Co., trade name; 7661) 100 parts by weight Glass powder (average particle size of about 5 μm) 300 parts by weight t-butyl peroxybenzoate 1 part by weight Internal mold release agent (St-Zn) ) 3 parts by weight Thickener (MgO) (Kyowa Chemical Co., Ltd., trade name: Kyowamag 150) 2 parts by weight Pigment (red organic pigment) Diameter 13 μm, length 6 mm) 20 parts by weight

A molding material made of the above resin composition was prepared, and the obtained molding material was wrapped in polyethylene laminated cellophane and aged at a temperature of 40 ° C. for 48 hours. And
The molded product shown in FIG. 1 was molded. The molded product 1 shown in FIG.
The bottom surface portion 1a is a square having a size of 300 mm × 300 mm, and the rising surface portion 1b is continuous with the bottom surface portion and has a height of about 150 mm. The wall thickness of the molded product 1 is about 6 mm. As the molding die, one having an upper die and a lower die, and arranged so that the upper die was in contact with the front surface side of the molded article and the lower die was in contact with the back surface side of the molded article, was used. At the time of molding, the temperature of the molding die portion in contact with the rising surface portion 1b is set to the upper die; 130 ° C. and the lower die;
The temperature of the mold part contacting the bottom surface portion 1a is set to 0 ° C., the upper mold is 140 ° C., the lower mold is 130 ° C., and the molding pressure is 100.
Heat press molding was performed under the conditions of kgf / cm ² and molding time of 7 minutes. The molded product obtained as described above was beautiful, was excellent in transparency and depth, and had no cracks.

Example 2 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
A molded product was obtained in the same manner as in Example 1, except that the temperature of the mold part in contact with the bottom part was set to 30 ° C., the lower mold; 115 ° C., and the upper mold; 140 ° C., and the lower mold; 130 ° C. As a result, it was possible to obtain a molded product which was beautiful and had no cracks and which was excellent in clear transparency and depth.

Example 3 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
30 ° C., lower mold; 110 ° C., the temperature of the mold part in contact with the bottom surface was upper mold; 140 ° C., lower mold; 130 ° C., and the molding time was 10 minutes. To obtain a molded product. As a result, it was possible to obtain a molded product which was beautiful and had no cracks and which was excellent in clear transparency and depth.

Example 4 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
20 ° C., lower mold; 110 ° C., the temperature of the mold part in contact with the bottom surface was upper mold; 140 ° C., lower mold; 130 ° C., and the molding time was 13 minutes. To obtain a molded product. Although the gloss of the rising surface portion of the obtained molded product was slightly lower than that of the molded product obtained in Example 1, the molded product was excellent in transparency and depth and had no cracks.

Comparative Example 1 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
A molded product was obtained in the same manner as in Example 1 except that the temperature of the mold part in contact with the bottom surface was 40 ° C., the lower mold was 130 ° C., and the upper mold was 140 ° C. and the lower mold was 130 ° C. As a result, cracks were generated at the corners between the rising surface portion and the bottom surface portion.

Comparative Example 2 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
A molded product was obtained in the same manner as in Example 1 except that the temperature of the mold part in contact with the bottom surface was 40 ° C., the lower mold was 120 ° C., and the temperature was 300 ° C. for the upper mold. As a result, cracks were generated at the corners between the rising surface portion and the bottom surface portion.

Comparative Example 3 The same molding material as in Example 1 was used. When molding,
The temperature of the mold contacting the rising surface is controlled by the upper mold; 1
A molded product was obtained in the same manner as in Example 1 except that the temperature of the mold part in contact with the bottom part was 40 ° C., the lower mold was 130 ° C. and the upper mold was 130 ° C. and the lower mold was 120 ° C. As a result, some cracks were generated at the corners of the rising surface.

[0029]

As described above, according to the present invention, since the curing of the rising surface portion is delayed with respect to the bottom surface portion, the curing shrinkage in the bottom surface portion is caused by the fluid portion in the rising surface portion during the curing. Will be absorbed. Therefore, the occurrence of cracks due to curing shrinkage or curing heat is reduced. In addition, the upper mold approaches the lower mold in response to curing shrinkage, and the resin composition is always molded in a pressurized state, so that the resin does not easily leak from the molding mold. Furthermore, the resin composition containing, for example, a pigment is present in the mold in a highly viscous state, and when viewed as a molding material as a whole, the unsaturated polyester resin and the inorganic filler and other components flow uniformly without separation. Is cured.

Therefore, the manufacturing method of the present invention uses the heat and pressure molding method, and since high-temperature high-speed molding is possible, unsaturated polyester resin molded products can be efficiently obtained. In addition, it is possible to obtain a high-strength unsaturated polyester resin molded product which is excellent in transparency, depth and surface smoothness, is clear, and has no cracks. Therefore, the present invention can be preferably used for producing a deep-drawing molded product such as a wash basin.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a molded product molded in Example 1.

[Explanation of symbols]

 1 ... Molded product 1a ... Bottom part 1b ... Rising surface part

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area B29L 22:00 4F

Claims (1)

[Claims] 1. A method for obtaining a molded article having a bottom surface portion and a rising surface portion continuous with the bottom surface portion by heat-pressing a resin composition containing an unsaturated polyester resin, an inorganic filler and a curing agent, The temperature of the mold part contacting the surface of the rising surface part is lower than the temperature of the mold part contacting the surface of the bottom surface part by 5 to 30 ° C., and the temperature of the mold part contacting the back surface of the rising surface part. The method for producing an unsaturated polyester resin molded article is characterized in that the temperature is lowered by 5 to 30 ° C. lower than the temperature of the mold part which comes into contact with the back surface of the bottom surface part, and heat and pressure molding is carried out.