JPH0655406B2 - Method of manufacturing artificial marble by extrusion - Google Patents

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 artificial marble used for building materials, vanity tops, sink tops, etc.
In particular, an artificial marble with an appearance of natural marble by dispersing aluminum hydroxide powder as a powdery inorganic filler in an acrylic resin matrix and a colorant powder for showing a pattern such as spots on the surface. To an extrusion molding method.

[0002]

2. Description of the Related Art The present inventors have previously filed Japanese Patent Application No. 63-63.
According to JP-A-228048 (JP-A-2-74317),
As a method for producing artificial marble, we have proposed a highly efficient extrusion molding method. The manufacturing method according to this prior proposal selectively uses magnesium hydroxide as the powdery inorganic filler. However, it is known that it is rather preferable to use aluminum hydroxide as the inorganic filler for artificial marble. That is, since aluminum hydroxide has a refractive index similar to that of an acrylic resin as a matrix resin, it gives the product a deep appearance having both transparency and hiding power, and is easy to cut. It is most suitable as the main material of the powder filler because it can be achieved.

[0003]

However, aluminum hydroxide powder, which is most suitable as an inorganic filler, has a low thermal decomposition temperature, and when it exceeds 180 ° C., thermal decomposition gradually progresses to water and alumina. Therefore, it is foreseeable that the decomposed water foams at the extrusion molding processing temperature (200 to 250 ° C.) of the acrylic resin, and a desired marble-like molded article cannot be obtained, which shows the advantage of extrusion molding. The fact is that it was recognized and could not be adopted at all. Moreover, even if aluminum hydroxide is used as the inorganic filler, it is difficult to bring out the peculiar speckled pattern seen in natural marble on the surface by itself, and it is more similar to natural marble. There was room for improvement in obtaining the desired appearance.

In view of the background of the prior art as described above, the present invention uses aluminum hydroxide powder as the powdery inorganic filler and has excellent appearance and quality characteristics by the continuous extrusion molding method. The purpose of the present invention is to obtain an artificial marble which enables continuous production of the artificial marble and has a speckled pattern on the surface to give a natural marble-like texture.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted various experiments and studies under the above-mentioned intended problems, and as described above, decomposition starts gradually when the temperature exceeds 180 ° C. Using an aluminum hydroxide powder that changes into alumina and alumina as an inorganic filler, and even when blending a colorant powder for producing a speckled pattern, a solidification extrusion method for performing extrusion molding under extremely high pressure, That is, the solidification extrusion method is adopted in which the molding material is conducted to the forming die with a cooling jacket immediately after extrusion by the extrusion die to complete the extrusion in a solidified state, and further, the state in which a specific sliding treatment is applied to the extrusion die and the forming die. Based on the thermal decomposition of aluminum hydroxide powder, the extruding conditions, especially the extruding temperature condition and the cooling temperature condition by the forming die are set to specific ranges. It is possible to carry out continuous extrusion molding without hindering the generation of bubbles and voids, and it is possible to obtain a molded product that is very similar to natural marble in terms of appearance transparency, depth, concealment effect, and patternability. The present invention has been completed upon finding out what can be obtained.

That is, the basis of the present invention is that an acrylic resin powder as a matrix resin, aluminum hydroxide powder as a powdery inorganic filler, and a colorant powder for pattern development are added in a small amount in a liquid form. A mixture uniformly mixed with a molding aid is used as a molding material, and immediately after the molding material is extruded into a predetermined shape from an extrusion die of an extrusion molding machine, it is passed through a forming die with a cooling jacket to form a solidified state. Extrusion molding is performed, and when performing the solidification extrusion molding, the extrusion temperature by the extruder is set to 180.
˜220 ° C. (preferably 190 to 210 ° C.), while setting and controlling the cooling temperature of the molded body by the forming die to 150 ° C. or lower (preferably 120 ° C. or lower), and a molding material for the inner surface of the extrusion die and the forming die Friction coefficient of 0.3 or less, tensile strength of 50 kgf on the entire contact surface of
/ (10 mm width) or more, the solidified extrusion molding operation is carried out in a state where the lubricant layer is formed to cover the artificial marble by extrusion molding.

For the above-mentioned lubricant layer, it is preferable to use a film or sheet obtained by using a fluororesin, especially a tetrafluoroethylene resin as a lubricant, and the resin alone or in combination with a tensile fiber core material. Is.

Next, each component, blending and extrusion molding conditions of the molding material used in the present invention will be described more specifically in detail.

(Matrix Resin) As the matrix resin, an acrylic resin is used because it is excellent in various properties such as transparency, weather resistance, hardness and heat resistance. Specific examples of the resin include thermoplastic acrylic resins having different monomer compositions and thermoplastic methacrylic resins, and in particular, a homopolymer of methyl methacrylate or methyl methacrylate is used as the total monomer content. A copolymer obtained by copolymerizing at least 1% of other vinyl ester monomer copolymerizable with other methacrylic acid ester and other methyl methacrylate in a proportion of at least 70% by weight, preferably at least 70% by weight, is preferable. These beads or ground powders are used as molding material elements. The particle size is not particularly limited, but generally 5 to 200
μm, particularly preferably about 20 to 100 μm is suitably used.

The above acrylic resin has a melt flow rate (MFR, 230 ° C., 3.8 kg) (test method / unit: A in order to carry out melt-kneading operation in an extruder without any trouble.
STMD 1238) is 0.5 g / 10 min or more,
And, those having a weight average molecular weight of less than 300,000 should be used. Melt flow rate (MFR) is less than 0.5 g / 10 min or weight average molecular weight is 3
If more than 0,000 is used, when kneading with the filler in the extruder, the melt viscosity will increase and the fluidity will decrease, resulting in a power load exceeding the capacity of the extruder, causing the operation to stop unexpectedly. Or problems such as resin leakage and screw damage occur, making smooth extrusion molding difficult. However, when the artificial marble, which is a molded product, is used for heat resistance-required applications, the lower limit of the weight average molecular weight is required to be 80,000 or more. That is, when an acrylic resin having a weight average molecular weight of less than 80,000 is used, the surface of the molded product may be lowered when a hot pot is placed on the molded product or a lit cigarette is accidentally dropped due to a decrease in heat resistance. It may be damaged.
The most preferable ranges of the melt flow rate (MFR) and the weight average molecular weight are MFR: 1.0 g / 10 min or more, and the weight average molecular weight is 120,000 to 170,000.

(Powdered inorganic filler) As the powdered inorganic filler, it is necessary to use aluminum hydroxide powder as a main material. Moreover, it is preferable to use the aluminum hydroxide powder having an average particle diameter of 10 μm or more and a specific surface area of 2 m ² / g or less, and further, it is preferable to use a material having a substantially spherical particle shape. .

When the average particle diameter is 10 μm or less, the sheet hiding property is too high and the texture of the artificial marble becomes poor.

When the specific surface area exceeds 2 m ² / g and becomes too large, the hiding property is too high due to the fine bubbles at the interface between the aluminum hydroxide and the matrix resin. Furthermore, the increase in the specific surface area facilitates the adsorption of pollutant properties, which causes a problem in the stain resistance of the artificial marble.

By using an aluminum hydroxide powder satisfying the above requirements as a filler, continuous molding by extrusion of artificial marble having a good appearance can be carried out without any trouble.
Aluminum hydroxide has a relatively low hardness of Mohs' hardness of 2.5, has a large particle size and a small specific surface area, has a refractive index close to that of the matrix resin, and has poor leak resistance to an acrylic resin. It is considered that the above are related to each other and work effectively together.

(Coloring Agent for Pattern Appearance) The coloring agent for pattern appearance is required to develop a speckled colored pattern on the surface of the artificial marble to obtain an appearance closer to that of natural marble. The following specific examples can be given as the coloring agent for pattern expression.

Concrete Example 1 It is possible to use a mixture of a thermoplastic resin or an elastomer which undergoes a crosslinking reaction with an organic peroxide, a dye and a pigment and an organic peroxide. With this composition, a spotted pattern is obtained. This is because there is almost no compatibility between the colorant and the acrylic resin as the matrix resin. In order to almost eliminate the compatibility, it is necessary to appropriately select a thermoplastic resin or elastomer that cross-links with the organic peroxide. That is, it is necessary to increase the degree of crosslinking as much as possible and eliminate the compatibility with the acrylic resin.

In order to complete the appearance of the speckled pattern, it is preferable to employ a thermoplastic resin or elastomer which is incompatible with the acrylic resin and does not decompose and melt at the molding temperature employed in the present invention. . Further, a resin having a relatively large molecular weight and fluidity equivalent to or close to that of an acrylic resin is suitable. The resin or elastomer for the colorant may be in the form of any of a homopolymer (homopolymer), a copolymer (copolymer) and a mixture thereof.
Typical of them are LDPE, LIDPE,
Examples include olefin resins such as HDPE, PP, EEA and EGMA, elastomers such as SBS, SIS, SEBS and SEPS, and EPM and EPDM elastomers.

Examples of the organic peroxide to be blended with the colorant resin or elastomer as a crosslinking agent include ketone peroxides, alkyl peroxides, hydroperoxides, dialkyl peroxides, alkylaryl peroxides. , Peroxyketals, alkylperesters, peroxycarbonates and the like, but dicumyl peroxide and tributylbenzyl peroxide are particularly preferably used. The degree of crosslinking of the resin can be adjusted by the amount of the crosslinking agent used. The preferable ratio of the organic peroxide to the colorant resin or elastomer is 0.2 to 2.5%.

As the dyes and pigments, those commercially available for plastics can be used, and the amount thereof can be appropriately increased or decreased depending on the shade of the pattern to be obtained.

In the production of the above colorant, a method is used in which an organic peroxide and a dye / pigment are added to a coloring resin, the mixture is kneaded by using a heating roll, an extruder or the like, and then pulverized to 10 to 4000 μm. However, at that time, a dispersant, a stabilizer and the like can be added if necessary.

Concrete Example 2 As another example of the colorant, it is possible to use crosslinked beads of the same kind or closely related to each other, which do not cause a flow at the processing temperature of the acrylic resin serving as the matrix. As a representative, P
There are MMA crosslinked beads and PS crosslinked beads. Styrene in the case of polystyrene resin, in the case of polymethylmethacrylate resin, a crosslinkable monomer such as divinylbenzene that crosslinks with these monomers and methylmethacrylate, etc.,
Polymer particles obtained by cross-linking polymerization with ethylene glycol dimethacrylate, triethylene glycol dimethacrylate and the like. Such crosslinked beads are colored or dyed in advance, but the method of coloring or dyeing is not particularly limited. For example, if a coloring agent such as a pigment or dye is required, it is known by a method in which it is added to a polymerization bath in the presence of a dispersant or the like to color the raw material, or a crosslinked polymerized finely divided polymer is used as a heat-resistant dye such as a disperse dye. The method of dyeing can be adopted.

Concrete Example 3 As still another pattern revealing colorant, it is a solid thermosetting resin having a softening point higher than the processing temperature of an acrylic resin which is a matrix resin, and is excellent in transparency and colorability. You can use one. Examples thereof include epoxy resin, unsaturated polyester resin, melamine resin, acrylic resin and the like. This pattern-appearing colorant can be obtained as desired particles by pulverizing and classifying a molded product which has been hardened by adding additives such as a curing agent, a curing accelerator and various stabilizers according to a conventional method.

The pattern-developing coloring agents shown in the above specific examples 1 to 3 are used as powders, and the average particle diameter is 10 to 40.
It is desirable that the fine particles have a size of 00 μm. If it is less than 10 μm, it becomes a monochromatic system, and it is difficult to obtain the effect of developing a speckled pattern. On the other hand, when it exceeds 4000 μm, impact resistance is lowered. A preferred range is 100 to 1000 μm. Also, the shape of the colorant is scale-like rather than spherical,
It is more preferable because it more closely resembles the spotted pattern of natural marble.

Concrete Example 4 As another coloring agent for showing a pattern, a fiber length of 0.1 to 1
A colored synthetic fiber powder having a diameter of 0 mm and a fiber diameter of 5 to 200 μm can also be used. Fiber length is less than 0.1 mm or fiber diameter is 5
If it is less than μm, it is difficult to obtain a molded product having a clear spot pattern, and if the fiber length exceeds 10 mm or the fiber diameter exceeds 200 μm, the impact resistance decreases. The fiber length is preferably 0.5 to 5 mm and the fiber diameter is 10 to 100 μm. As the synthetic fiber, one kind or two or more kinds of polyester fiber, polyamide fiber, aramid fiber, vinylon fiber and the like can be used. The synthetic fibers may be colored by a known method using a known dye and pigment. There is no limitation on the amount of the dye / pigment used, and it may be used within a range capable of coloring in a desired color.

(Liquid Forming Aid) The forming aid is a plasticizer or mineral oil, and it is necessary that both are liquids having compatibility with the acrylic resin. When the molding aid is liquid, wetting the acrylic resin powder during kneading,
Aluminum hydroxide powder is attached to this, which is necessary in order to facilitate obtaining a uniform mixture,
It is also useful for reducing the melt viscosity of the acrylic resin and improving the moldability.

As the plasticizer to be used, for example, DMP, DOP, DBP or the like as a phthalate ester type, and DIOA or D as a fatty acid (dibasic) ester type are used.
BS, DOS, etc., and TOTM, etc. can be listed as a trimellitic acid ester type.

The mineral oil is a hydrocarbon liquid paraffin obtained by highly refining and separating a high-quality crude oil and has a viscosity-specific gravity constant (V, G, C) of less than 0.9. It is preferably used. In this case, it is possible to obtain artificial marble in which the softening point of the acrylic resin is less likely to decrease.

(Composition) The mixing ratio of the molding material is 20 to 50 wt% of acrylic resin powder and water when the total amount of the mixture of acrylic resin powder and aluminum hydroxide powder is 100 wt%. The aluminum oxide powder should be in the range of 80 to 50 wt%. If the blending ratio of the acrylic resin powder is less than 20 wt%, and therefore the blending amount of aluminum hydroxide exceeds 80 wt%, the matrix resin is not uniformly dispersed in the aluminum hydroxide powder, and as a result, in the extruder. Melt softening does not proceed sufficiently,
Extrusion molding becomes difficult. On the other hand, if the acrylic resin powder content exceeds 50 wt% and the aluminum hydroxide powder content is relatively less than 50 wt%, the concealing property of the molded product will be poor even if the extrusion molding operation is facilitated. Sufficient and too strong transparency makes it impossible to express the weight feeling similar to natural marble, and heat resistance becomes insufficient. The most preferable blending ratio is in the range of 25 to 40 wt% in the acrylic resin powder.

The blending amount of the colorant powder for pattern appearance is 0.1 to 10 parts by weight when the total amount of the powder mixture of the above acrylic resin powder and aluminum hydroxide powder is taken as 100 parts by weight. Should be a department. The reason for setting the content within 10 parts by weight is that the cross-linked colorant has almost no compatibility with the compounding components of the acrylic resin powder and the aluminum hydroxide powder due to the crosslinking, and exceeds 10 parts by weight. This is because if the amount is used, the dispersibility such as separation and peeling is deteriorated and the physical properties are deteriorated. On the other hand, if the amount is less than 0.1 parts by weight, it becomes difficult to reveal the speckled pattern, and the significance of adding the colorant is lost. Therefore, 0.1
Within the range of from 10 to 10 parts by weight, the dispersibility is not hindered and a natural marble-like spot pattern can be revealed. A particularly preferable amount of addition is 0.3 to 3 parts by weight.

The amount of the liquid molding aid, that is, the plasticizer or the mineral oil, is 100 based on the total amount of the powder mixture of the acrylic resin powder and the aluminum hydroxide powder.
If the amount is less than 0.5 part by weight, the desired addition effect cannot be obtained sufficiently. That is, the acrylic resin cannot be sufficiently leaked, the aluminum hydroxide powder is secondarily aggregated, and the coarse particles are segregated, so that a uniform mixture cannot be obtained. In addition, the role of plasticization efficiency is not fully exerted, the extrusion fluidity is not stable during extrusion molding, and it becomes difficult to perform continuous extrusion molding in a uniform manner for a long time. The distribution of the aluminum powder becomes non-uniform, and its agglomerates serve as nuclei, resulting in a defect that the strength becomes extremely inferior to the impact from the outside. On the other hand, if the blending amount of the molding aid exceeds 5 parts by weight, the heat resistance of the molded product is significantly lowered even if a uniform mixture is obtained. Therefore, the blending amount of the molding aid should be in the range of 0.5 to 5 parts by weight, and particularly preferably in the range of 1.0 to 3 parts by weight.

The molding material used in the present invention contains, in addition to the above-mentioned essential components, a colorant other than the colorant for pattern expression in order to obtain a colored artificial marble, and a small amount of stearic acid as a lubricant. Higher fatty acids such as palmitic acid,
Naturally, addition of the alkaline earth metal salt (calcium salt, magnesium salt, etc.), montanic acid wax, amides of higher fatty acid, etc. is allowed. Also,
If necessary, the aluminum hydroxide powder may be surface-treated with a fatty acid metal salt, a silane coupling agent, a titanate coupling agent, or the like in advance. Furthermore, within a range that does not impair the effects of the present invention, a part of the aluminum hydroxide powder is replaced with another type of powdered inorganic filler to reduce the material cost and adjust the appearance of the molded product. It is acceptable to do.

(Molding Conditions) In molding, first, the pre-blended materials are premixed. In this mixing operation, for example, a Henschel mixer having a stirring blade, a ribbon blender, a V-type tumbler, etc. are used, and the acrylic resin powder, aluminum hydroxide powder, colorant powder for pattern appearance and liquid molding aid are each mixed in the above-mentioned mixing ratio. , And uniformly mix until there is no "mow powder" -like lumps. It is not appropriate to use a dry blender or the like having no stirring blade as the mixer, because the "mass powder" -like lumps do not disappear even after a long mixing operation. Further, the order of feeding the blended materials to the mixer does not matter so much.

Next, the mixture obtained by the above premixing operation is used as a molding material, and this is solidified and extruded into a predetermined cross-sectional shape by a solidification extruding apparatus. The extrusion molding equipment used here is generally used to extrude polymeric materials into round bars, plate pipes, or other shaped products. The molten polymer material is distributed to an extrusion die as needed, and is cooled while passing through a forming die attached to the tip of the extrusion die to solidify and mold it into a desired shape and size. The solidification extrusion method using such an apparatus can be suitably used for molding not only general resins but also materials having particularly high melt viscosity and poor fluidity, and materials with high filler filling. That is, since the molten material is solidified and extruded in the forming die, the pressure inside the die becomes extremely high. Therefore, it is possible to suppress the generation of voids and bubbles in the molded product, and obtain good quality. It has features.

A typical example of the solidification extrusion molding apparatus used in the present invention is shown in FIG. In the figure, (1) is the extruder body, (2) is its cylinder, (3) is the extrusion screw installed inside it, and (4)
A) (4B) (4C) (4D) are first to fourth heating devices of the cylinder (2), (5) is a material supply hopper,
(6) is a driving device, (7) is a throttle portion at the tip of the cylinder (2), (8) is an extrusion die provided subsequently to it,
(9) is a water cooling jacket (9
Forming die with a), (10) take-up device for a molded product made of rubber roll, track, etc., (11) (12)
Is a heating device for the drawing portion (7) and the extrusion die (8),
(13) is a measuring device for the resin pressure at the throttle of the cylinder tip.

By the way, in the practice of the present invention, a specific sliding treatment is applied to the inner surfaces of the extrusion die (8) and the forming die (9) in contact with the extruded material in order to prevent the molding material from sticking. Must be given. This slipping treatment is essential in order to enable continuous extrusion molding for a long time while maintaining the surface properties and texture of the artificial marble constant and good, and the static or dynamic friction coefficient is 0. Three
The following is performed by applying the lubricant layer (14) having a tensile strength of 50 kgf / (10 mm width) or more to the entire inner surfaces of the extrusion die (8) and the forming die (9) by sticking or the like. It is a thing. If the friction material layer (14) has a friction coefficient of more than 0.3, the extrusion pressure of the molding material increases, and it becomes impossible to maintain a preferable predetermined pressure described later, which makes molding practically difficult. A preferable friction coefficient is 0.15 or less.

The tensile strength is 50 kgf / (10 mm
If the width is less than (width), the sliding material layer (14) is damaged early due to the strong rubbing of the molding material during extrusion molding, the lubrication effect is lost, and the propulsive force is reduced, making continuous molding difficult. Become. Preferably, the tensile strength is 100 kgf / (10 mm
Width) or more is better.

The constituent material of the lubricant layer (14) is not particularly limited as long as it has the above-mentioned friction coefficient and tensile strength, but the fluorine-based material has a low friction coefficient. It is preferable to use a resin as the sliding material. Among them, it is particularly preferable to use tetrafluoroethylene resin (PTFE). The required tensile strength may be imparted by increasing the thickness of the resin film or sheet used as the above-mentioned lubricant, but the required strength can be obtained while using a thin resin film itself as the lubricant. In order to provide it, it is advantageous to deal with it by forming a composite material by laminating the resin film on a core layer made of a tensile fiber such as glass fiber, Kevlar fiber or metal fiber.

In the above-mentioned solidification extrusion molding apparatus, the molding material is charged from the hopper (5), is kneaded by the screw (3) while being melted and softened by being heated in the cylinder (2), and is drawn (7). And is extruded into a predetermined shape from the extrusion die (8). Then, the extrudate extruded from the extrusion die is cooled by a water cooling jacket (9a) provided therein while passing through the forming die (9), shaped into a predetermined cross-sectional shape, and a molded body (A) in a solidified state, That is, it is manufactured into artificial marble.

As mentioned above, when aluminum hydroxide exceeds 180 ° C., it gradually decomposes and changes into water and alumina, and this water content becomes foam in a usual extrusion molding method and the appearance of the product is remarkably improved. It causes the inhibition.
On the other hand, by using the solidification extrusion method, by molding under high pressure, even when using aluminum hydroxide as a filler,
It is possible to obtain a good quality artificial marble without foaming, but the solidification extrusion method does not allow molding at any temperature and can be carried out only under limited conditions.

The first condition is the extrusion temperature. That is, the extrusion temperature is 180 ° C. or higher in any of the cylinder (2) portion, the cylinder tip narrowed portion (7), and the extrusion die (8) portion of the extruder body (1).
It should be set in the range of 220 ° C, preferably in the range of 190 ° C to 210 ° C. This set temperature is 180
When the temperature is lower than 0 ° C., the acrylic resin is not melted and softened sufficiently, so that the back pressure of the extruder becomes too large and extrusion molding becomes difficult. On the other hand, when the set temperature exceeds 220 ° C., the decomposition of aluminum hydroxide is promoted, so that foaming cannot be suppressed even in the solidification extrusion method, and the value of the product is significantly reduced.

The second condition is the cooling temperature of the molded body (A) formed by the forming die (9) with a cooling jacket. That is, the temperature of the molded body (A) at the outlet of the forming die (9) is 150 ° C. or lower, preferably 120 ° C.
Sufficient cooling must be provided so that: If this cooling temperature exceeds 150 ° C., the artificial marble molded body extruded from the forming die with a cooling jacket (9) is in a softened state, causing foaming, appearance defects such as blisters, and the like on the surface thereof. The shape is also difficult.

The third condition is that the inner surface of the extrusion die (8) and the forming die (9) is entirely coated with the lubricant layer (14) having predetermined physical properties as described above. That is, the solidification extrusion molding operation is performed under the condition that the sliding treatment is applied. Under the condition that the sliding treatment is not provided, it is not possible to carry out continuous extrusion molding of artificial marble having a stable surface property for a long time.

As yet another condition, the pressure of the extruded resin in the cylinder drawing part (7) is 50 kg / cm ² to 50.
0 kg / cm ² , preferably 70 kg / cm ^{2 to} 350 kg / cm ²
Must be operated within the range of. Resin pressure is 50
If it is less than kg / cm ² , nest formation and foaming are likely to occur and the quality of the product as an artificial marble is deteriorated. Also, 500 kg
If it exceeds / cm ² , there is a mechanical limit, and there is a risk of damaging the extruder and extrusion die forming die.

[0044]

According to the present invention, in addition to selecting an acrylic resin powder having excellent transparency and heat resistance as a matrix resin, aluminum hydroxide powder is particularly selected as a powder inorganic filler. Using a mixture of a powder and a coloring agent powder for pattern appearance and a liquid molding aid as a molding material, and adopting a solidification extrusion method, setting a specific range of an extrusion temperature condition and a cooling temperature condition by a forming die, and In addition, by combining with a specific sliding treatment to the extrusion die and forming die, it is possible to perform continuous molding of high-quality artificial marble without hindrance by the extrusion molding method that was conventionally considered impossible. it can.

Therefore, it is possible to efficiently manufacture an artificial marble having an arbitrarily long length and a required cross-sectional shape, and the manufactured artificial marble has a good harmony of transparency and concealment, which gives a deep and profound feeling. It is possible to obtain a high-quality product which has an excellent and speckled pattern and which has an appearance similar to that of natural marble, and which is also uniform in terms of quality.

[0046]

Example A matrix resin, a powdered inorganic filler and a liquid molding aid shown in Table 1 below were prepared.

[0047]

[Table 1]

On the other hand, as a coloring agent for pattern appearance, the following A-
1 to 7 were prepared.

A-1 As an SBS elastomer, dicumyl peroxide was added to the styrene / butadiene / styrene block copolymer (Shell Chemical Co., Califlex TR1184) in an amount of 1.0% by weight, 12% of pigments such as carbon black, titanium oxide, and anthraquinone were mixed, heated with a roll and kneaded at 180 to 220 ° C., cooled, and then pulverized to produce colorant particles having an average of 500 to 1000 μm.

A-2 SEBS elastomer (hydrogenated SBS) containing 1.2% by weight of dicumyl peroxide with respect to styrene / ethylene / butylene / styrene / block copolymer (Shell Chemical Co., Ltd., Kraton G1650). And added under the same conditions as A-1 to produce colorant particles of 500 to 1000 um.

A-3 EPM, EPDM elastomers such as ethylene propylene rubber (Supreme 553, Sumitomo Chemical Co., Ltd.)
Dicumyl peroxide was added to 1.5% by weight to 500 to 1000 under the same conditions as A-1.
Made um colorant particles.

As A-4 PP, Mitsui Toatsu Chemical Co., Ltd. Mitsui Noblen BEB
Dicumyl peroxide was added in an amount of 1.0% by weight with respect to -G, and 500 to 10 was added under the same conditions as A-1.
00 um colorant particles were made.

A-5 PS resin (Sumitomo Chemical, Sbright 6S) 2.97 kg
Suspension polymerization of 99 parts by weight of styrene monomer and 1 part by weight of divinylbenzene gave cross-linked beads having an average particle size of 350 um, and was dyed by Sumitomo Chemical disperse dye Sumikaron Brilliant Red S-2BL in a 1% bath by a conventional method. To produce colorant particles.

A-6 Solid Epoxy Resin (Mitsui Petrochemical, R-309) 10
0 parts by weight, curing agent (C11-Z manufactured by Shikoku Chemical Co., Ltd.) 5 parts by weight,
Aluminum oxide (200 parts by weight), carbon black, titanium oxide, valve stem (5 to 8 parts by weight) and zinc stearate (lubricant) (1 to 5 parts by weight) are melt-mixed for 5 minutes on a hot roll at 100 ° C., then cooled and pulverized to 100. ~ 500 um colorant particles were made.

A-7: A mixture of blue, red and yellow polyester fibers each having a fiber length of 3 mm and a fiber diameter of 50 um mixed in a ratio of 1 / 1.5 / 2.0.

On the other hand, as a solidification extrusion molding apparatus, a full flight type molding machine (caliber: 50 mm, as shown in FIG. 1)
L / D = 32, screw compression ratio: 2.5), and the entire inner surface of the extrusion die (8) and the forming die (9) is covered with a lubricant made of various materials as shown in Table 2. The layer (14) was adapted to form a coating.

[0057]

[Table 2]

The materials shown in Table 1 above and the colorants A-1 to 7 for pattern development were introduced into a Henschel mixer at the compounding ratios shown in Tables 3 and 4 below, and mixed at room temperature for 30 minutes.

Then, the mixture was solidified and extruded by changing the extruding conditions to various values as shown in Tables 3 and 4 by the above solidifying extruder, and various plate-like moldings having a thickness of 12 mm and a width of 790 mm were formed. I got the goods.

Then, the extrusion moldability at the time of extrusion molding was evaluated, the appearance of the product and the appearance of the pattern were observed for each molded product, and the product impact strength was further investigated. The evaluation methods are as follows, and the evaluation results are
The results are shown in Tables and Table 4.

[Evaluation Method] Product Appearance ◯: A smooth and beautiful surface having no cavities due to foaming and no voids was obtained.

X: Foaming caused by formation of cavities, voids, or uneven surface.

Observation of product pattern and impact strength ◯: A natural stone-like spotted pattern is uniformly obtained on the surface and the inner surface, and the falling ball impact strength (JIS K 6718,
200 g steel ball, plate thickness 12 mm) that did not crack at a height of 180 cm. X ... A pattern in which spot-like patterns were extremely concentrated or overlapped and only a non-uniform pattern was obtained, and moreover, cracked at a height of less than 180 cm in the above falling ball impact strength.

Extrudability: Good: Extruder load was within the rated value and stable extrusion was possible for 24 hours or more.

X: The extruder was overloaded and the screw stopped during operation, and the fluctuation was extremely large, and stable extrusion for 24 hours or more could not be performed.

[0066]

[Table 3]

[0067]

[Table 4]

As shown in the evaluation of Table 3 above, in the production methods of Examples 1 to 9 according to the prescribed conditions of the present invention, the continuous solidification extrusion molding operation was continued for 24 hours or more. It was possible, and it was possible to obtain an artificial marble with high efficiency, good appearance quality, and a spotted pattern.

On the other hand, the extrusion temperature condition is too high,
Alternatively, when Comparative Examples 11 and 12 in Table 4 are too low, plate formation cannot be performed due to excessive load or fluctuation of the extruder,
Alternatively, even if the plate was produced, foaming and voids were generated, and a molded product of good quality could not be obtained. Further, in the case of Comparative Example 13 in which the temperature of the molded body at the die outlet is too high due to insufficient cooling of the molded body by the water cooling jacket of the forming die, and in Comparative Example molded using the forming die having no cooling jacket (not used). In the case of No. 14, it was not possible to suppress the occurrence of voids and blisters due to foaming, and it was also impossible to obtain a molded product of excellent quality.

Furthermore, in the case of Comparative Example 15 in which the lubricant layer was not provided on the extrusion die and the forming die,
In the case of Comparative Examples 16 and 17 in which extrusion molding cannot be performed at all from the initial point and the physical properties of the lubricant layer deviate from the specified values of the present invention, the lubricant is less than 24 hours after the start of operation. The resin film of the material layer was damaged, and thereafter molding became difficult.

Further, in the case of Comparative Example 10 in which the coloring agent for pattern development was not blended, naturally no speckled pattern was revealed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an example of a solidification extrusion molding apparatus used for an extrusion molding operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Extruder main body 2 ... Cylinder 8 ... Extrusion die 9 ... Forming die 9a ... Water cooling jacket 14 ... Attached lubricant layer

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Claims (2)

[Claims] 1. A mixture obtained by uniformly mixing an acrylic resin powder as a matrix resin, an aluminum hydroxide powder as a powdery inorganic filler, and a colorant powder for pattern expression with a small amount of a liquid molding aid. Is used as a molding material, and immediately after the molding material is extruded into a predetermined shape from an extrusion die of an extrusion molding machine, solidification extrusion molding is conducted in which a molding die with a cooling jacket is conducted to be solidified. When performing solidification extrusion molding, the extrusion temperature by the extruder is set to 180 to 220 ° C., the cooling temperature of the formed body by the forming die is set to 150 ° C. or less, and the extrusion die and the forming material on the inner surface of the forming die are used. Under the condition that the entire contact surface is covered with a lubricant layer having a friction coefficient of 0.3 or less and a tensile strength of 50 kgf / (10 mm width) or more. Artificial marble method of manufacture by extrusion, characterized in that performing the solidification extrusion molding operation. 2. The method for producing artificial marble by extrusion molding according to claim 1, wherein the lubricant layer comprises a film or sheet using a tetrafluoroethylene resin as a lubricant.