JPS6220888B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester cosmetic bottle having a deeper pearly surface luster and a flowing pattern on the surface, and a method for manufacturing the same. Polyester resin is hygienic, strong, chemical resistant,
Due to their excellent fragrance retention, transparency, and surface gloss, they are being widely used for cosmetics, pharmaceuticals, and food containers, but the quality of the appearance of cosmetic containers in particular determines their commercial value. There is a demand not only for transparent containers, but also for containers that have a unique external appearance with excellent decorative properties, such as those with pearly surface luster. In order to satisfy these demands, the present inventors studied a plastic cosmetic bottle with a turbulent cloud pattern composed of a polyester resin and a methacrylic resin of a specific composition, and filed an application earlier. The appearance of the bottle has a gentle pearly surface luster that gives the impression of an elegant ceramic surface.For example, it is made of a mixed resin composition of polycarbonate and polymethyl methacrylate, or a mixture of acrylonitrile-styrene copolymer and methacrylic resin. It does not reach the strong pearly surface gloss that molded products made of resin compositions have. However, polycarbonate-based mixed resin compositions and acrylonitrile-styrene copolymer-based mixed resin compositions have poor chemical resistance, strength, and fragrance retention, so their use as containers for cosmetics is currently limited. There has been a strong desire to develop a cosmetic bottle that is mainly made of resin and has a deeper pearly surface luster. In view of the current situation, the present inventors set out to obtain a beautiful cosmetic bottle that has a deep pearly surface luster with a stronger pearl feeling without impairing the properties of polyester resin, and also has a flowing pattern on the surface. As a result of extensive research, we have developed a preform obtained by blending polyester resin into extruded pellets consisting of polyester resin and methacrylic resin in a specific composition range so that the amount of methacrylic resin is in a specific range, and then injection molding the pellets. The present invention was accomplished by discovering that the above object could be achieved by blow molding. In other words, the gist of the present invention is that the intrinsic viscosity is
For extruded pellets consisting of a resin composition of 10 to 99% by weight of a polyester resin of 0.6 or more and 90 to 1% by weight of a methacrylic resin, the methacrylic resin in the preform is made of a polyester resin with an intrinsic viscosity of 0.6 or more. The first invention is a polyester cosmetic bottle having a pearly surface luster and a surface flow pattern obtained by blow molding a preform obtained by injection molding after blending to a composition of ~40% by weight. A methacrylic resin in a preform containing a polyester resin with an intrinsic viscosity of 0.6 or more for extruded pellets consisting of a resin composition of 10 to 99% by weight of a polyester resin with a viscosity of 0.6 or more and 90 to 1% by weight of a methacrylic resin. A cosmetic bottle made of polyester having a pearly surface luster and a surface flow pattern, characterized in that the polyester cosmetic bottle is blended to have a composition of 0.5 to 40% by weight and then injection molded to obtain a preform, and then the preform is blow molded. The second invention is a manufacturing method. In the cosmetic bottle of the present invention, the first step is to blend polyester resin and methacrylic resin in amounts within a specific range and melt-extrude them to form pellets to obtain extruded shaped pellets, and then the second step is to form a pellet. This is obtained by blending the shaped pellets with a predetermined amount of polyester resin and then injection molding to obtain a preform, and in the third step blow molding the preform. The feature of this method is that in the first step, mixed resin pellets are prepared, and then in the second step, a predetermined amount of polyester resin is blended and injection molded to create a preform by so-called two-step molding. This two-stage molding allows the preform itself to exhibit a strong, deep pearly surface luster and surface flow pattern in a stable and well-reproduced manner. Conventionally, products made by mixing polyester resin and methacrylic resin at the same time exhibited a pearly surface luster, although it was weak. However, when mixing polyester resin and methacrylic resin, it was thought that it would be difficult to develop a pearly surface luster in the two-stage molding described above, but surprisingly, contrary to expectations, a deep pearly surface luster was created. This is a unique phenomenon. Moreover, it has the excellent feature that the surface flow pattern of the molded product is clearly expressed. Next, the second feature of the present invention is that the preform obtained by the two-stage molding is blow-molded to produce a cosmetic bottle with a pearl surface luster and surface flow pattern that is even stronger and deeper. That's a good point. The polyester resin in the present invention is one in which 60 mol% or more of the repeating units that constitute it are composed of ethylene terephthalate, and the copolymerized components include isophthalic acid, adipic acid, sebacic acid, and p-β-oxyethoxybenzoic acid. , dicarboxylic acid components such as diphenyl ether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, etc. or their alkyl ester derivatives, propylene glycol, butanediol, hexamethylene glycol, neopentyl Glycols such as glycol and cyclohexanedimethanol are used. Polyester resins can be produced by any of the following methods: polycondensation via transesterification, direct esterification and polycondensation, or solid phase polymerization of the polymers obtained by these methods. The polymer thus obtained can be used, but its intrinsic viscosity [η] must be 0.6 or more, preferably in the range of 0.65 to 1.4. It is preferable to use a polyester resin with a large [η] because the pearl surface gloss and luster tend to be good. If [η] is less than 0.6, the mechanical strength of the final bottle will be significantly lowered, and the bottle will lose its luster and beauty, which is undesirable. On the other hand, if [η] exceeds, for example, 1.4, the molding processability becomes poor, which is not preferable. Note that [η] is a value determined from the solution viscosity measured at 25°C in a phenol/tetrachloroethane=50/50 (weight ratio) solution. In addition, [η] of the polyester resin in the mixed composition of polyester resin and methacrylic resin is -
This is a value obtained by pulverizing at a temperature of 30° C. or lower, extracting and removing the methacrylic resin using an acetone/ethanol mixed solvent, drying, and then using the same method as above. In the present invention, the polyester resin mixed with the methacrylic resin and used for extrusion shaping and the polyester resin used in the second stage may be the same or different. good. In particular, it is preferable to use polyester resins with different [η] values because their flow behavior will be different and a strong surface flow pattern will tend to appear. The methacrylic resin in the present invention is a homopolymer of methyl methacrylate, a copolymer of 50 mol% or more of methyl methacrylate and another vinyl monomer that can be copolymerized with it, or a mixture of these polymers. . Other vinyl monomers that can be copolymerized with methyl methacrylate include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, butyl acrylate, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, etc. It will be done. In the present invention, it is preferable to use a homopolymer of methyl methacrylate or a copolymer with methyl acrylate or ethyl acrylate because a bottle with particularly excellent pearly surface luster can be obtained. The resin composition of the extruded pellets made of polyester resin and methacrylic resin is 10 to 99% by weight of polyester resin, preferably 40 to 97% by weight, and 90 to 1% by weight of methacrylic resin, preferably 60 to 99% by weight. It is necessary that the composition be in the range of 3% by weight. The extrusion-shaped pellets may be obtained by mixing pellets of each resin within the above composition range in a blender or the like, and then shaping the pellets in an extruder. If the proportion of polyester resin in the extruded pellets is less than 10% by weight, not only will the mechanical strength of the final bottle be low, but also delamination will easily occur, making it impossible to obtain the desired bottle. This is not desirable as it often disappears. On the other hand, if the proportion of the polyester resin exceeds 99% by weight, it is not preferable because it becomes difficult to develop the pearly surface gloss of the final bottle. When preparing these extrusion-formed pellets, it is important to thoroughly dry the polyester resin and methacrylic resin. If drying is insufficient, the [η] of the polyester resin may decrease. This is not preferable because it not only impairs the mechanical strength and chemical resistance of the finally obtained bottle, but also weakens the development of pearl surface luster. Any commonly used extruder can be used, but an extruder that provides sufficient kneading will give better results. For example, an extruder with a relatively large L/D and a compression ratio of 1.6 to 3.5 is preferable. Furthermore, measures to enhance the kneading effect, such as adding dalmage to the tip of the screw, are preferably implemented. The temperature during extrusion shaping must be such that the polyester resin is sufficiently melted; for example, in the case of polyethylene terephthalate, the cylinder temperature is preferably 260°C or higher. It is often better to use a so-called forward tapered profile where the temperature gradient of the cylinder is low on the hopper side and high on the nozzle side, but if the polyester resin content is high, the cylinder temperature on the hopper side should be increased. A reverse tapered profile may also be used. In the present invention, a polyester resin with [η] of 0.6 or more is used so that the composition of the methacrylic resin in the injection molded product is 0.5 to 40% by weight with respect to the extruded pellets having the above-mentioned specific composition ratio. One of its major features is that it can be injection molded by blending the ingredients. The extruded pellets and the newly blended polyester resin can be mixed uniformly using a commonly used blender, etc. In this case, it is preferable that the shapes of the pellets be close in size. . The composition of methacrylic resin in injection molded products is 0.5 to 40% by weight as described above.
It is necessary that methacrylic resin
If it is less than 0.5% by weight, the resulting bottle will have a strong transparency and almost no pearlescent appearance will be observed. On the other hand, if the methacrylic resin exceeds 40% by weight, the pearl surface luster becomes weak, the mechanical strength becomes poor, and the chemical resistance becomes extremely poor, which is not preferable. In carrying out the present invention, any commonly used injection molding machine may be used, but the degree of pearl surface gloss and surface flow pattern tends to be affected by the screw shape and injection molding conditions. Therefore, it is preferable that the screw has a compression zone and a metering zone each having at least 3 pitches and a compression ratio of 1.5 to 4. Also important in injection molding conditions are injection speed and mold temperature.
As the injection speed increases, the surface flow pattern becomes more pronounced. However, if the injection speed is extremely high, the gloss around the gate will disappear, stains will occur, and the flow pattern on the upper surface will tend to lose its elegance, so a moderate injection speed is required. On the other hand, it is preferable that the mold temperature is set at 50°C or less. If the mold temperature exceeds 50°C, it will take a long time to cool and solidify the preform, resulting in a longer molding cycle. This is not preferable because crystallization of the preform may occur and the pearl surface luster may disappear. The wall thickness of the preform is 1 to 1 from the viewpoint of moldability.
Preferably, the thickness is within the range of 12 mm; if it is thinner than 1 mm, strength deterioration may occur due to insufficient filling or orientation; if it exceeds 12 mm, the polyester resin will crystallize, causing not only loss of pearl surface luster but also sink marks. This is not preferable because it makes it easier. Next, when carrying out the present invention, the preform obtained by the above-mentioned method is blow molded. Various methods can be used for blow molding, but the so-called in-die extension blow method and biaxial stretching method are available. It can be divided into blow method. Among these, the biaxial stretching blow method is particularly preferred because it not only improves the appearance of the final bottle but also dramatically increases its mechanical strength. Further, this biaxial stretching blowing method may be a hot parison method or a cold parison method. In the biaxial stretch blow method, the preform is held at a stretching temperature of 80 to 160°C and biaxially stretched blow molded using pressurized gas at a total stretch ratio of 1.3 to 20. Hereinafter, a manufacturing method example of the present invention using the above-mentioned biaxial stretch blow molding method will be specifically explained. The stretching temperature is defined by the outer surface temperature of the preform immediately before biaxial stretch blow molding, and it is necessary that the inner surface temperature of the preform also fall within the above temperature range. Blow molding at a temperature of less than 80° C. is not preferable because partial stretching occurs, which tends to result in uneven wall thickness, and only bottles with poor reproducibility of the curvature of the mold are obtained. Further, blow molding at a temperature exceeding 160° C. is not preferred because sufficient orientation is difficult to be achieved and the resulting bottle has extremely low mechanical strength such as drop strength. In order to maintain the preform within the above stretching temperature range, the preform in a high temperature state obtained by injection molding may be left to cool, or the preform in this high temperature state may be cooled to about room temperature and then heated using a far infrared heater or the like. A method may be used as appropriate, such as a method of heating uniformly while rotating. The above-mentioned total stretching ratio is defined as follows. That is, R ₁ is the ratio of the stretch-oriented longitudinal size of the biaxially stretch blow-molded bottle to the substantially unoriented longitudinal size of the preform corresponding to this longitudinal direction; If the ratio of the stretch-oriented lateral size of the bottle and the substantially unoriented lateral size of the preform corresponding to this lateral direction is R ₂ , then the total stretching ratio = R ₁ × R ₂ This is what is shown. The cosmetic bottle according to the present invention has chemical resistance, fragrance retention,
It has excellent mechanical strength, and the unique pearl surface luster and surface flow pattern give it a stronger and deeper appearance, making it suitable for small bottles for basic cosmetics, bottles for men's cosmetics, bottles for women's cosmetics, cream containers, cologne containers, shampoos and conditioners. It can be preferably used as bottles for various cosmetics such as cosmetic bottles. The present invention will be specifically explained below using Examples. Example 1 5.5 kg of polyethylene terephthalate pellets with [η] of 1.2, dried to a moisture content of 50 ppm, were heated at 25°C.
[η] (d/g) measured in chloroform solution
4.5Kg of polymethyl methacrylate pellets with 0.6
After drying to a moisture content of 100 ppm, the mixture was added and mixed well using a blender, L/D = 24, supply zone 11D, compression zone 6D, metalling zone.
The pellets were fed into a Toshiba Machine 40 mmφ extruder equipped with a 7D screw, a pitch 1D screw, and a compression ratio of 2.5, and extrusion molded to obtain pellets having an average size of 3φ×3 mm.
At this time, the cylinder temperature is 260℃ in the rear, 270℃ in the middle,
Front 280℃, die 280℃, screw rotation speed 60rpm
The molding was done with The measured value of [η] of polyethylene terephthalate in the obtained pellets was 1.06. After drying these pellets to a moisture content of 60 ppm, the pellets may be mixed with polyethylene terephthalate pellets having a moisture content of 70 ppm and a [η] of 1.0 in the proportions shown in Test Nos. 1 to 5 in Table 1 and Comparative Examples 1 to 2, and then mixed in a blender. After mixing L/D=17, feeding zone 8.5D, compression zone 5.3D, metaling zone
Using a Meiki Seisakusho SJ-40C injection molding machine equipped with a screw of 3.2D, pitch 0.9D, and compression ratio 3.0, the weight is 35g, the body wall thickness is 3mm, the thread outside diameter is 28mm,
A preform with an average body diameter of 25.7 mm and a length of 135 mm was molded using a single direct gate mold. The molding conditions were as follows. Cylinder temperature C ₁ 270℃, C ₂ 280℃, C ₃ 290℃, nozzle 290
℃, primary injection pressure (gauge pressure) 25Kg/cm ² , injection speed 20g/sec, molding cycle 32 seconds, mold temperature 10℃
It was hot. The obtained preform was set in a biaxial stretch blow molding machine, and the temperature of the preform was 105.
℃, then using a blow pressure of 20Kg/cm ² and a core for hanging down, it was 54mmφ and 170cm high.
A cylindrical cosmetic bottle of mm was molded. The resulting cosmetic bottle has a pearly surface luster, a surface flow pattern, and a temperature of 40°C.
Appearance changes and drop strength after being left filled with ethanol for one month were evaluated. The results are shown in Table 1. Moisture percentage used in the first stage as a comparative example
Pellets of various compositions were made by extrusion molding under the same conditions as above, except that pellets of polyethylene terephthalate (50 ppm, [η] = 1.2) and polymethyl methacrylate ([η] = 0.6) were mixed in the proportions shown in Table 2. I got it. Thereafter, this pellet was injection molded under the same conditions as above to obtain a preform, and then biaxially stretched and blown under the same conditions to obtain a preform with a diameter of 54 mm and a height of 170 mm.
A cylindrical cosmetic bottle of mm was obtained. Table 2 shows the results of the same evaluation as above. The evaluation display of pearl surface gloss, surface flow pattern, and drop strength in Tables 1 and 2 is as follows (these display methods are common to the following Examples and Comparative Examples). Pearl surface gloss ◎: Extremely strong pearl surface gloss ○: Fairly strong pearl surface gloss △: Weak pearl expression gloss ×: Pearl surface with no luster and surface flow pattern ◎: Very strong surface flow pattern ○: Fairly strong surface Flow pattern present △: Weak surface flow pattern ×: Slight surface flow pattern or no surface flow pattern Drop strength Fill a container with ethanol and leave it at 40℃ for one month, then extract the ethanol and pour in 0℃ water. filling
The number of times the container was dropped was determined by dropping it from a height of 1 m onto a concrete floor from the bottom and breaking the container.

【table】

[Table] Example 2 Pellet of ethylene (terephthalate-isophthalate) copolymer with [η] of 1.0, which was copolymerized with 3 mol % of isophthalic acid component dried to a moisture content of 50 ppm, and 10 mol % of methyl acrylate. Measured in copolymerized chloroform solution at 25°C [η]
(d/g) of 0.65 (methyl methacrylate-methyl acrylate) copolymer pellets and (methyl methacrylate-methyl acrylate) copolymer shown in Table 3 Test Nos. 1 to 4 and Comparative Example 1. The mixture was mixed so as to have a content of , and extrusion molding was performed using the extruder and molding conditions used in Example 1 to obtain pellets having dimensions of 3 mm x 3 mm. Next, the obtained pellets were dried to a moisture content of 35 ppm, and then a (methyl methacrylate-methyl acrylate) copolymer having a composition of 7.
[η] of 50 ppm moisture content is 1.05 so that it is weight%
The same polyethylene terephthalate pellets as in Example 1 were mixed, and the same cosmetic bottles as in Example 1 were molded and evaluated using the injection molding machine, mold, and biaxial stretch blow molding machine used in Example 1. The results are shown in Table 3.

[Table] Example 3 (Methyl methacrylate-methyl acrylate) copolymer/ethylene (terephthalate-isophthalate) copolymer obtained in Test No. 2 of Example 2 =
Extruded pellets having a composition of 20/80 (wt%) and pellets of polyethylene terephthalate with different [η] as shown in Table 4 Test Nos. 1 to 4 and Comparative Example 1 were mixed in equal amounts, and after thoroughly drying. A cosmetic bottle was molded using the same equipment and conditions as in Example 1. The resulting bottle was evaluated in the same manner as in Example 1. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. Polyester resin 10 having an intrinsic viscosity of 0.6 or more
For extruded pellets with a resin composition of ~99% by weight and 90-1% by weight of methacrylic resin, a polyester resin with an intrinsic viscosity of 0.6 or more is used in a preform with a composition of 0.5-40% by weight of methacrylic resin. A polyester cosmetic bottle having a pearly surface luster and a surface flow pattern obtained by blow molding a preform obtained by injection molding after blending the polyester so as to have the following properties. 2 Polyester resin 10 with an intrinsic viscosity of 0.6 or more
For extruded pellets with a resin composition of ~99% by weight and 90-1% by weight of methacrylic resin, a polyester resin with an intrinsic viscosity of 0.6 or more is used in a preform with a composition of 0.5-40% by weight of methacrylic resin. 1. A method for producing a polyester cosmetic bottle having a pearly surface luster and a surface flow pattern, which comprises blending the polyester cosmetic bottles so as to have a pearly surface luster and a surface flow pattern, the method comprising: obtaining a preform by injection molding, and then blow molding the preform.