JPH0464522B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing artificial marble containing fillers, and more particularly to a method for manufacturing artificial marble having high mechanical properties and excellent appearance. [Prior Art] Conventionally, various inorganic compounds (e.g., aluminum hydroxide, silica, calcium carbonate, etc.) have been used as inorganic fillers such as methyl methacrylate (MMA) mainly for the purpose of imparting design properties, flame retardance, and rigidity.
Various so-called artificial marbles blended with resins have been developed. [Problems to be solved by the invention] In these conventional artificial marbles, the inorganic filler and the organic resin have significantly different properties, so they have poor interfacial compatibility such as compatibility and adhesiveness.
Therefore, conventionally used inorganic fillers have often been unable to sufficiently improve the mechanical properties of artificial marble, particularly with respect to bending strength and impact strength. In order to improve the above-mentioned drawbacks caused by conventional inorganic fillers, artificial marble has been proposed in which the surface of the inorganic filler is treated with, for example, a silane coupling agent, and this is blended with, for example, MMA-based resin. Sufficient improvement has not always been achieved. [Means for Solving the Problems] In order to solve the above problems, the present invention provides the following: [In the formula, R ₁ and R ₂ are each H, carbon number 1 to 15
alkyl group, COOY (where Y represents H, NH ₄ or an alkali metal atom), halogen atom, phenyl group or substituted phenyl group, R ₃ is H, carbon number 1
~15 alkyl groups, halogen atoms, phenyl groups or substituted phenyl groups, X represents H, NH ₄ or an alkali metal atom. ] or general formula [] (In the formula, R ₄ and R ₅ are each H, carbon number 1 to 15
represents an alkyl group, halogen atom, phenyl group or substituted phenyl group. ) at least 1
An organic bond formed by polymerizing a seed carboxylic acid monomer and at least one radically polymerizable vinyl monomer without a catalyst in a polymerization system in which an inorganic compound is dispersed. The present invention provides a method for producing artificial marble, which comprises obtaining a filler, and then curing a composition obtained by adding a vinyl compound to the obtained organic bond filler. The carboxylic acid monomer used to form the organic bond filler in the production method of the present invention and represented by the general formula [] or [] has a carboxylic acid group as an active site that brings about polymerization activity, and It is essential that the resulting polymer has a double bond as an active site to express strong union with the inorganic compound, and any compound having these functional groups may be used, such as acrylic acid. ,
Examples include methacrylic acid, crotonic acid, tiglic acid, cinnamic acid, maleic anhydride, and citraconic anhydride. Among these, acrylic acid, methacrylic acid, and crotonic acid are particularly preferred because they have high polymerization activity. In addition, the inorganic compounds used for forming the organic binding filler include those listed in the periodic table.
group, transition metals and their oxides, hydroxides,
chloride, sulfate, sulfite, carbonate, phosphate,
Examples include silicates, mixtures thereof, complex salts, etc. Among these, calcium sulfite, calcium sulfate, barium sulfate, silicon dioxide, quartz, calcite, feldspar, titanium oxide, antimony trioxide, talc, clay, aluminum oxide. , calcium carbonate, nickel powder, iron powder, zinc powder, copper powder, iron oxide,
Zinc oxide, aluminum hydroxide, magnesium hydroxide, glass powder, glass beads, glass fiber,
Glass fillers containing barium salts or lead salts, silica gel, zirconium oxides, tin oxides, slags, etc. are preferred because they have a particularly remarkable effect of activating vinyl monomers and strongly bonding with polymers.
These inorganic compounds should be present in amounts ranging from 20% to 20% based on the total weight of the composition.
It can be used in an amount of 95% by weight, preferably 30 to 90% by weight, and its shape and size can be selected as appropriate. Furthermore, the vinyl monomer used to form the organic bonding filler may be any ordinary vinyl monomer that can be radically polymerized, and among them, methyl methacrylate has a particularly high polymerization activity, and moreover, It is particularly preferred because the polymer and the inorganic compound have good coalescence. When two or more types of vinyl monomers are used in combination, it is particularly preferable to use methyl methacrylate as one component from the viewpoint of polymerization activity. The organic binding filler is formed by combining the carboxylic acid monomer and 1 in a polymerization system in which an inorganic compound is dispersed.
It can be obtained by polymerizing more than one type of polymerizable vinyl monomer, that is, by polymerizing in the presence of an inorganic compound as an essential condition. As an example of a preferred method for producing the organic bond filler, the vinyl monomer and the inorganic compound are suspended and dispersed in an aqueous medium under temperature conditions that do not cause a thermal polymerization reaction, and then the carboxylic acid-based filler is suspended and dispersed in an aqueous medium. Examples include a method in which a monomer is added and stirred to cause an aqueous heterogeneous polymerization reaction, and the polymerization is carried out for a predetermined period of time. The amount of carboxylic acid monomer used to obtain the organic binding filler is about 0.05 to 100% by weight, preferably 0.1 to 50% by weight, more preferably 0.5 to 30% by weight, based on the total weight of the inorganic compound and vinyl monomer. Used in amounts of % by weight. In most cases, it is preferred to increase the amount of carboxylic acid monomer as the hinyl monomer content increases. Additionally, the weight ratio of inorganic compound to vinyl monomer (one type or mixture of two or more types) can vary over a wide range, and is from about 500:1 to about 1:5, preferably from about 50:1 to about 1: In the range of 1. The amount of water as a reaction medium ranges from about 1% by weight to several hundred times, preferably from about 10% by weight to several tens of times, based on the total weight of inorganic compound and vinyl monomer. The polymerization reaction is preferably carried out at a temperature range of about 10-100°C, preferably 20-80°C, under an atmosphere of an inert gas, such as nitrogen. Reaction times can range from 30 minutes to about 15 hours. The organic bond filler produced can be dried at a temperature ranging from about 10 to 300°C, preferably from about 50 to 200°C. The interaction between the inorganic compound and the polymer in this organic binding filler can be caused by simple adsorption or
This is more than adhesion in a physical sense due to van der Waals forces and the like. This is clear from the fact that when this organic bond filler is extracted with a good solvent for vinyl polymers, such as hot benzene, very little polymer is extracted. Such a strong bonding effect between the inorganic compound and the polymer in the organic bonding filler can be obtained by separately producing a polymer that is thought to be produced during the above polymerization in the presence of the inorganic compound, and then using a solvent method to produce the polymer. This cannot be obtained at all by simply using an organic filler coated on the inorganic compound, and this means that if this organic filler is subjected to the same extraction process as described above, most of the polymer will be extracted. It is clear from this. In the production method of the present invention, the vinyl compound to be blended with the organic binding filler is preferably methyl methacrylate and a partial polymer of methyl methacrylate (hereinafter referred to as methacrylate syrup), and other monofunctional A vinyl compound or a polyfunctional vinyl compound may be used in combination. The methacrylate syrup used has a polymer content of 95 to 2% by weight, preferably 85 to 15% by weight. Examples of the monofunctional vinyl compounds include styrene; acrylonitrile; vinyl acetate; methyl acrylate; ethyl acrylate and methacrylate; butyl acrylate and methacrylate;
2-ethylhexyl acrylate and methacrylate; lauryl acrylate and methacrylate; stearyl acrylate and methacrylate; bidroxyethyl acrylate and methacrylate; methoxyethyl acrylate and methacrylate; glycidyl acrylate and methacrylate; methacryloxyethyl trimellitic acid and its acid anhydride, etc. . The polyfunctional vinyl compound has the general formula [] (In the formula, R ₆ is H or a methyl group, p is an integer of 1 to 20) Ethylene glycol diacrylate and dimethacrylate; Diethylene glycol diacrylate and dimethacrylate; Triethylene glycol diacrylate and dimethacrylate; Polyethylene Examples include glycol diacrylate and dimethacrylate. These acrylates and methacrylates can be used alone or in combination of two or more. Furthermore, liquid polybutadiene can also be added. In the production method of the present invention, at least one of silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents is blended into the composition, mainly to reduce viscosity. Preferably, the blending amount may be 0.01 to 10% by weight based on the total amount of the composition. In addition, in the production method of the present invention, colorants, polymerization inhibitors, ultraviolet absorbers,
Antioxidants can also be blended. A molded artificial marble is obtained by polymerizing and curing a composition comprising the organic bond filler and the vinyl compound by a cast polymerization method. At this time, it is possible to stabilize the uniform dispersion of the filler in the composition, which has been extremely difficult using conventional methods, and the cured molded product can therefore exhibit excellent properties. Note that by mixing the organic binder filler with a methacrylic resin and press-molding this mixture by melting and heating, a molded product with excellent properties can be obtained. The mechanical strength is slightly inferior to that of cured molded products obtained by mold polymerization. In order to obtain a desired cured molded article using the composition, a polymerization catalyst for polymerizing and curing the vinyl compound in the composition is used. Any known compound can be used as the polymerization catalyst, but in the case of polymerization and curing by heating, substances that can decompose at high temperatures and initiate polymerization, such as benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, etc. , dicumyl peroxide, acetyl peroxide, lauroyl peroxide, azobisisobutyronitrile, etc. When polymerizing and curing at room temperature, for example, peroxide and amines, peroxide and sulfinic acids, peroxide and cobalt compounds can be used. The composition can also be cured by UV irradiation using a photosensitizer such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, etc. The amount of polymerization initiator used for curing by cast polymerization can range from 0.01 to 10% by weight, based on the vinyl compound. Cast polymerization can be carried out, for example, by first carrying out a polymerization reaction at 50 to 80°C for 1 to 5 hours, and then carrying out a polymerization reaction at 100 to 140°C for 0.5 to 3 hours. The present invention will be explained in more detail below with reference to Examples. Note that all parts in the examples are parts by weight.
In addition, the mechanical strength of cured molded products can be measured using JIS
Bending strength and Izot impact strength were tested in accordance with K6911. Examples 1 and 2 and Comparative Examples 1 and 2 4,000 ml of deionized water was placed in a No. 5 four-necked flask equipped with a cooling tube, a nitrogen introduction tube, a stirring rod, and a thermocouple for internal temperature detection, and inorganic compounds were added to the flask. After adding 1200 g of aluminum hydroxide powder (Hygilite (trademark) H-210, manufactured by Showa Light Metal Co., Ltd.) and suspending and dispersing the mixture, the mixture was purged with nitrogen for 30 minutes. Next, 215 g of methyl methacrylate as a vinyl monomer was added under nitrogen flow and vigorous stirring. next,
After heating the contents of the flask to 60°C in a hot water bath and confirming the uniform dispersion of methyl methacrylate, a solution of 57 g of methacrylic acid as a carboxylic acid monomer dissolved in 100 ml of deionized water was added. was gradually added, and the polymerization reaction was carried out at 60°C for 8 hours. After the reaction was completed, the product was filtered under reduced pressure, thoroughly washed with deionized water, and then water was removed using a steam dryer at 105°C to obtain 1370 g of an organic binding filler. The polymer content of this organic binder filler was measured using a calcination method and was found to be 12%.On the other hand, when a Soxhlet extraction test was conducted for 50 hours using hot benzene as an extraction solvent, it was found that even after the extraction process, the polymer content was still 12%. The combined content was 10%. Therefore, it was found that the aluminum hydroxide powder and most of the polymer composited on the surface of this powder by the polymerization reaction were extremely strongly integrated. The organic bond filler thus obtained was mixed into methacrylate syrup (polymerization rate = 33.4%, intrinsic viscosity of the polymer = 0.033/g, viscosity at 23°C =
680 cp) and azobisisobutyronitrile in the proportions shown in Example 1 in Table 1 below, and this blend was mechanically mixed to prepare a dope for cast polymerization. Further, in order to reduce the viscosity of the dope, a dope was prepared in which 1% by weight of 3-methacryloxypropyltrimethoxysilane was blended as a silane coupling agent based on the organic binding filler (Example 2). Each of the dopes of Examples 1 and 2 was filled into a mold made of tempered glass with a polyethylene terephthalate film attached and a gasket.
It was cured at 120°C for 2 hours. The bending strength and Izot impact strength of each of the obtained cured products were measured. The results are shown in Table 1. For comparison, a dope (Comparative Example 1) in which the aluminum hydroxide powder used in the formation of this filler was used as a filler instead of the organic binding filler used in Examples 1 and 2, and A dope containing a silane coupling agent (Comparative Example 2) was prepared in the same manner as in Example 2. In Comparative Example 1, the blending amount of the filler was made to correspond to the content of aluminum hydroxide powder in the organic binding filler in Example 1. That is, 409 copies x 0.88
=360 copies. On the other hand, the amount of methacrylate syrup blended in Comparative Example 1 was an amount corresponding to the content of the polymer in the organic binding filler, that is, 409 parts.
The amount was increased by 360 copies = 49 copies compared to Example 1. In Example 2 and Comparative Example 2, each compounding amount was determined based on similar calculations. Using each dope of Comparative Examples 1 and 2, cured products were obtained in the same manner as in the above Examples, and the bending strength and Izot impact strength were measured. The results are shown in Table 1.

[Table] As is clear from Table 1, the dope composition containing the organic binder filler according to the example of the present invention is superior to the dope composition of the comparative example containing the untreated filler. , can provide an artificial marble cured product with excellent mechanical properties. Further, since the organic binding filler had extremely good wettability with respect to the liquid resin, it was easy to form a composite with the resin, and the appearance of the cured product was significantly cleaner than that of the comparative example. Examples 3 and 4 and Comparative Examples 3 and 4 Aqueous heterogeneous treatment was performed in the same manner as in Example 1, except that 1200 g of quartz powder (Crystallite (trademark) A-2 manufactured by Ryumori Co., Ltd.) was used as the inorganic compound. A polymerization reaction was carried out to obtain 1333 g of an organic bonding filler. The organic binder filler had a polymer content of 10%, and even after 50 hours of Soxhlet extraction with hot benzene, the polymer content was still 9%. Using this organic binder filler and the quartz powder, dopes of Examples 3 and 4 and Comparative Examples 3 and 4 were prepared according to the formulations shown in Table 2, and these dopes were mixed with Example 1 and Comparative Examples 3 and 4. It was cured in the same way. The mechanical strength of the obtained cured product was measured and the results are shown in Table 2.

[Table] As is clear from Table 2, each of the dopes of Comparative Examples 3 and 4 provides a cured product with physical strength values that are considerably lower than those of each of the dopes of Examples 3 and 4. . That is, the organic bond filler in this example exhibits a remarkable strength-improving effect on the cured product, and provides a cured product for artificial marble with excellent mechanical properties. Furthermore, since this organic binding filler had extremely good wettability with the liquid resin, it was easy to form a composite with the resin, and the appearance of the cured product was significantly cleaner than that of the comparative example. Example 5 and Comparative Examples 5 and 6 An aqueous heterogeneous polymerization reaction was carried out in the same manner as in Example 1, except that 1200 g of magnesium hydroxide powder (special grade reagent) was used as the inorganic compound, and 1412 g of organic binding filler was obtained. Ta. The organic binder filler had a polymer content of 15%, and even after 50 hours of Soxhlet extraction with hot benzene, the polymer content was still 13%. Using this organic binding filler and the magnesium hydroxide powder, Example 5 and Comparative Example 5 were prepared according to the formulations shown in Table 3.
and 6 were prepared, and these dopes were cured in the same manner as in Example 1. The mechanical strength of the obtained cured product was measured and the results are shown in Table 3.

[Table] As is clear from Table 3, the strength properties of the dopes of Comparative Examples 5 and 6, which used magnesium hydroxide powder as a filler, were significantly lower than that of the dope of Example 5. Give a certain cured product.
That is, the organic bond filler in this example exhibits a remarkable strength-improving effect on the cured product, and provides a cured product for artificial marble with excellent mechanical properties. Furthermore, since this organic binding filler had extremely good wettability with the liquid resin, it was easy to form a composite with the resin, and the appearance of the cured product was significantly cleaner than that of the comparative example. Comparative Example 7 50g of methyl methacrylate by bulk polymerization method
and 13 g of methacrylic acid were copolymerized using 0.6 g of azobisisobutyronitrile as a polymerization initiator. 49 g of the obtained copolymer was added to methacrylate syrup (same as described in Example 1).
Using 240 g of the copolymer-blended methacrylate syrup dissolved in 191 g, a dope was prepared and cured in the same manner as in Comparative Example 2 above. The mechanical strength of the cured product was measured and the results were as shown in Table 4.

[Table] As is clear from Table 4, the hardened portion of the dope of Comparative Example 7 had a significantly lower strength physical property value than that of Example 2. In addition, the wettability was poor, making it difficult to form a composite, and the uniform dispersion stability of the filler was poor, resulting in filler precipitation, and the appearance of the cured product was extremely poor. Reference Example 1 The organic bond filler obtained in Example 1 and pearl-like methyl methacrylate resin were mixed and pressure molded by melting and heating.
Mechanical strength was measured in the same way as in the case of . The results are shown in Table 5.

〔Effect of the invention〕

The method for producing artificial marble according to the present invention uses an organic bonding filler in which an inorganic compound and an organic polymer are strongly combined as a filler, so the interfacial affinity between the filler and the vinyl compound is extremely high. improved,
As a result, the filler is uniformly dispersed and stabilized in the composition, and workability is significantly improved. Therefore, by curing this composition, it is possible to obtain artificial marble having high mechanical properties and an excellent appearance that cannot be obtained by conventional manufacturing methods.

Claims (1)

[Claims] 1. General formula [] [In the formula, R ₁ and R ₂ are each H, carbon number 1 to 15
alkyl group, COOY (where Y represents H, NH ₄ or an alkali metal atom), halogen atom, phenyl group or substituted phenyl group, R ₃ is H, carbon number 1
~15 alkyl groups, halogen atoms, phenyl groups or substituted phenyl groups, X represents H, NH ₄ or an alkali metal atom. ] or general formula [] (In the formula, R ₄ and R ₅ are each H, carbon number 1 to 15
represents an alkyl group, halogen atom, phenyl group or substituted phenyl group. ) at least 1
An organic bond formed by polymerizing a seed carboxylic acid monomer and at least one radically polymerizable vinyl monomer without a catalyst in a polymerization system in which an inorganic compound is dispersed. 1. A method for producing artificial marble, which comprises obtaining a filler and then curing a composition obtained by adding a vinyl compound to the obtained organic bond filler. 2. The method for producing artificial marble according to claim 1, wherein at least one of silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents is blended.