JPH078943B2 - Polyester composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester composition. More specifically, it relates to a polyester composition containing a specific amount of calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound, and more specifically, a white polyester film used as a substrate for cards, labels, display plates, white plates and the like. The present invention relates to a polyester composition suitable for use.

[Prior Art] Polyester typified by polyethylene terephthalate has excellent physical and chemical properties and is widely used as fibers, films, and other molded articles. Among these applications, white films are used as substrates for cards, labels, display boards, white boards and the like.

Conventionally, it is well known to add a large amount of white inorganic particles to polyethylene terephthalate in order to obtain a white film. For example, an example of adding a large amount of titanium oxide and barium sulfate (Japanese Patent Publication No. 56-4901), an example of adding a large amount of barium sulfate (Japanese Patent Publication No. 60-30930), a large amount of titanium dioxide, and others There is an example of adding a small amount of the inorganic particles (JP-A-60-96654).

Further, Japanese Patent Publication No. 43-12013 discloses that a large amount of calcium carbonate is added.

However, in the above-mentioned conventional techniques, the one to which barium sulfate is added has poor dispersibility of particles, and when the obtained polyester is used to form a film, a film having sufficient whiteness and hiding power cannot be obtained. . On the other hand, those containing titanium oxide have excellent hiding power because of the high refractive index of the particles, but for example, a decrease in spectral reflectance in the low wavelength region of 450 nm or less is observed, and sufficient whiteness cannot be obtained. .

Further, for example, when a large amount of calcium carbonate as exemplified in Japanese Patent Publication No. 43-12013 is added to polyester, agglomeration of particles occurs or a yellowish polymer is obtained, which is not preferable. Even if a film having a sufficient whiteness is obtained, it is difficult to combine the hiding power.

[Problems to be Solved by the Invention] An object of the present invention is to contain a large amount of white inorganic particles in a polyester to obtain a molded article excellent in whiteness and hiding power. By using a polyester composition containing inorganic particles and a phosphorus compound, the above-mentioned conventional drawbacks are solved.

[Means for Solving the Problems] The above-mentioned object of the present invention is a polyester in which at least 80 mol% of repeating units are ethylene terephthalate, and (A) calcium carbonate having an average particle diameter of 0.05 to 5 μm It can be achieved by a polyester composition containing 40% by weight, (B) 1 to 20% by weight of inorganic particles other than calcium carbonate having an average particle size of 0.05 to 5 μ, and (C) a phosphorus compound as P atoms of 100 to 5000 ppm. .

The polyester of the present invention means at least 80 repeating units.
A polyester having a mol% of ethylene terephthalate is produced by a transesterification or esterification reaction and a polycondensation reaction of a dicarboxylic acid mainly composed of terephthalic acid or an ester-forming derivative thereof and a glycol mainly composed of ethylene glycol. Of course, the polyester may be a homopolyester or a copolyester. In the case of copolyester, examples of components to be copolymerized include diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol having an average molecular weight of 150 to 20000, p-xylene glycol, 1,4-cyclohexanedimethanol and 5-sodium sulforesorcin. Adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid,
Examples thereof include dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxy acid benzoic acid.

The calcium carbonate referred to in the present invention may be a natural product or a synthetic product, and its crystal form includes calcite, aragonite, vaterite, etc., but is not particularly limited thereto.

The calcium carbonate may be surface-treated with stearic acid, polyacrylic acid, a silane coupling agent, a titanium coupling agent, or the like, and a surfactant such as sodium dodecylbenzenesulfonate may be used in combination.

The average particle size of calcium carbonate must be 0.05 to 5 µ, preferably 0.1 to 3 µ, more preferably 0.2 to
2μ. If the average particle size is less than 0.05 μm or the average particle size exceeds 5 μm, a film formed as a film cannot be obtained, which is inferior in whiteness and hiding power.

Further, the content of calcium carbonate in the present invention is 6 to 40.
It is necessary to set it as a weight percentage, preferably 7 to 30 wt%, and more preferably 10 to 20 wt%.

When the polyester obtained when the content is less than 6% by weight is formed into a film, the desired whiteness and hiding power of the film become insufficient. On the other hand, if the content exceeds 40% by weight, the dispersibility of particles in polyester may be poor, or the film strength may be insufficient.

Inorganic particles other than calcium carbonate in the present invention are not particularly limited, but specifically titanium dioxide, zinc white, lead sulfide, lithopone, lead white, basic lead sulfate, basic lead silicate,
Lead zinc white, barium sulfate, silicon dioxide, magnesium oxide, alumina, talc, clay, calcium phosphate,
And so on. In particular, in order to enhance the hiding power of the film when formed into a film, inorganic particles having a high refractive index are preferable, and the refractive index is preferably 1.70 or more, and further
Inorganic particles of 1.80 or more are more preferable. Specifically, the use of titanium dioxide and zinc oxide is particularly preferable because high hiding power can be obtained when the film is formed.

Further, these inorganic particles may be used alone or in combination of two or more kinds.

The average particle diameter of the inorganic particles other than calcium carbonate in the present invention is required to be 0.05 to 5 μ, preferably 0.1 to
It is 3μ, and more preferably 0.2 to 2μ. If the average particle size is less than 0.05 μm or if the average particle size exceeds 5 μm, a film formed as a film cannot be obtained because the hiding power is poor.

Further, the content of inorganic particles other than calcium carbonate in the present invention needs to be 1 to 20% by weight, preferably 2
-15 wt%, more preferably 3-10 wt%.

When the polyester obtained when the content is less than 1% by weight is formed into a film, the target film has insufficient whiteness and hiding power. On the other hand, if the content exceeds 20% by weight, the dispersibility of particles in the polyester may be poor, or the whiteness of the film may be insufficient.

In the present invention, the ratio of the content of inorganic particles other than calcium carbonate to the content of calcium carbonate is not particularly limited, but in order to obtain the whiteness of the target film, hiding power, 0.05 to 2.0, more preferably 0.1 to 1.0. Is.

The phosphorus compound as used in the present invention means a compound which contains a phosphorus atom and is soluble in glycol.

Examples thereof include phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof, and specifically, phosphoric acid, phosphorous acid,
Phosphoric acid trimethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid mono or dimethyl ester, phosphorous acid trimethyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, etc. I can give you. Of these, the use of phosphoric acid, phosphorous acid and their ester-forming derivatives is particularly preferred.

Furthermore, these phosphorus compounds may be used alone or in combination of two or more kinds.

The content of the phosphorus compound in the present invention is 100 as the P atom.
~ 5000ppm, preferably 200-4000pp
m, more preferably 300 to 3000 ppm.

When the content of the phosphorus compound is less than 100 ppm as P atom, the dispersibility of calcium carbonate in the polyester and inorganic particles other than calcium carbonate becomes poor. Alternatively, the color tone of the obtained polyester composition is deteriorated, and when formed into a film, sufficient whiteness and hiding power cannot be obtained. On the other hand, if the content exceeds 5000 ppm as P atoms, diethylene glycol as a by-product of the polyester is increased and the polyester is significantly deteriorated, so that a good film cannot be obtained. .

In the present invention, the ratio of the phosphorus compound content (% by weight as P atom) to the calcium carbonate and the inorganic particles other than calcium carbonate is not particularly limited, but is preferable in order to obtain the desired whiteness and hiding power of the film. Is 0.00
It is from 0.05 to 0.05, and more preferably from 0.001 to 0.03.

As described above, the present invention aims to improve the particle dispersibility in the polyester and the color tone by allowing the polyester to contain calcium carbonate and inorganic particles other than calcium carbonate in a specific amount in combination, and containing a phosphorus compound in a specific amount. In addition, when the polyester composition is formed into a film, a white film having excellent whiteness and hiding power is obtained.

As a method of incorporating calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound of the present invention into a polyester, one or more kinds of calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound are added in the polyester manufacturing step. The method, the method of dry blending with polyester and the method of melt blending the polyester obtained by these methods within the scope of the present invention are not particularly limited, but preferably calcium carbonate, other than calcium carbonate at any stage during polyester production. Inorganic particles and phosphorus compound are added. As a specific production method, calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound may be added to the polyester reaction system at any time, and it is preferable that the esterification or transesterification reaction is carried out before polyester production during polyester production. It is during the initial stage of the condensation reaction, and more preferably between the end of the esterification or transesterification reaction and the initial stage of the polycondensation reaction.

Further, the method of adding calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound to the polyester reaction system is not particularly limited, and calcium carbonate, inorganic particles other than calcium carbonate and a phosphorus compound may be simultaneously or mixed. You may add. As a preferable addition method for obtaining particularly good dispersibility of calcium carbonate and inorganic particles other than calcium carbonate, after adding a phosphorus compound, calcium carbonate and inorganic particles other than calcium carbonate are added, and the addition interval is within 1 hour. , More preferably within 30 minutes.

The calcium carbonate to be added to the polyester reaction system, the inorganic particles other than calcium carbonate and the phosphorus compound may be added in the form of powder or liquid or as they are, but calcium carbonate in the polyester and inorganic particles other than calcium carbonate From the viewpoint of dispersibility, a method of adding it in a chiller state or a liquid state appropriately mixed with an organic solvent such as glycol is preferable. Further, these slurries and liquids may be added after heat treatment.

The polyester of the present invention is a metal compound catalyst such as lithium, sodium, calcium, magnesium, manganese, zinc, cobalt, antimony, germanium, and titanium, which is usually used during production, an antioxidant, a pigment, a fluorescent whitening agent, and a surface active agent. Agents, antistatic agents and the like can be added as required.

When a film is produced from the polyester composition containing the calcium carbonate of the present invention, inorganic particles other than calcium carbonate, and a phosphorus compound, the polyester composition is molded into a sheet by a usual method, and a conventional method is used. The film is stretched biaxially by a factor of 2.5 to 4.0 and then heat set at a temperature of 150 ° C or higher.

The preferred density of the biaxially stretched film using the polyester composition of the present invention is 1.10 to 1.38 g / cm ³ , more preferably 1.1.
It is 5 to 1.35 g / cm ³ . When the density is less than 1.10, the productivity and mechanical properties of the film are inferior, and when the density exceeds 1.38, preferable whiteness of the film cannot be obtained.

The polyester composition of the present invention is a molded article other than a film,
For example, it can be preferably used in the field of fibers and the like.

[Examples] The present invention will be described in more detail with reference to Examples. The characteristics in the examples were measured as follows.

A. Intrinsic viscosity of polymer Measured at 25 ° C using o-chlorophenol as a solvent.

B. Polymer Softening Point Polymer chips were placed in a heating bath and heated at 6 ° C. for 5 minutes, and the temperature at which the tip of the load was 5 mm into the chips was measured.

C. Particle dispersibility in polymer A polymer (20 mg) was sandwiched between two cover glasses and melt-press cooled at 280 ° C., and then judged by microscopic observation.

The criteria for judgment are as follows.

◯: Aggregated particles are hardly observed. (It is within the target range of the present invention.) Δ: A few aggregated particles are observed. (The purpose of the present invention is not reached.) X: Many aggregated particles are observed. (It does not reach the object of the present invention.) D. Polymer color tone It is calculated from Hunter values (L, a, b) of a polymer chip color machine (manufactured by Toyo Rika) based on the method of JIS L1073.

⊚: Whiteness of 70 or more (particularly preferred within the scope of the present invention) ◯: Whiteness of 55 or more and less than 70 (within scope of the present invention) Δ: Whiteness of 53 or more and less than 55 (present invention The whiteness of less than 53 (the object of the present invention is not reached.) E. Film concealment power The visible light transmission density of a film having a thickness of 250 μ was measured with a transmission density meter TD-504 manufactured by Macbeth. It was measured and the hiding power was judged.

The transmission density here is calculated by the following equation.

Transmission density [−] ×; less than 1.0 (poor hiding power) △; 1.0 to less than 1.2 (slightly poor hiding power) ○; 1.2 to less than 1.5 (good hiding power) ◎; 1.5 or more (very good hiding power) D = −log (T / 100) where D: Transmission density [−] T; Visible light transmittance [%] F. Film whiteness 450 nm and 550 nm measured with a tungsten photogen using Hitachi Autograph EPE-2 The film having a thickness of 250 μm was evaluated by the following formula from reflectances R ₄₅₀ and R ₅₅₀ .

Whiteness (%) = 4R ₄₅₀ −3R ₅₅₀ ◎; 95% or more (particularly preferred within the scope of the present invention) ○; 90% or more and less than 95% (within the scope of the present invention) Δ: 85% or more and less than 90% (does not reach the object of the present invention) ×; less than 85% (does not reach the object of the present invention) Example 1 80 parts by weight of dimethyl terephthalate, ethylene glycol
After transesterifying 60 parts by weight with 0.09 parts by weight of calcium acetate as a catalyst according to a conventional method, 10% by weight of trimethyl phosphate was used as a phosphorus compound so that the amount was 0.273% by weight with respect to the polymer (molar ratio to calcium carbonate 0.0130). Add the containing ethylene glycol solution,
After 10 minutes, 37.5 parts by weight of ethylene glycol slurry containing 40% by weight of calcium carbonate having an average particle size of 0.9μ and 25 parts by weight of ethylene glycol slurry containing 20% by weight of titanium dioxide having an average particle size of 0.5μ were added, followed by polymerization. As a catalyst, 0.03 part by weight of antimony trioxide was added.

Then, polycondensation reaction was performed according to a conventional method under reduced pressure at high temperature to obtain polyethylene terephthalate having an extreme viscosity of 0.605, a softening point of 259.7 ° C. and a P content of 450 ppm. As a result of observing the particle dispersion state of polymer calcium carbonate and titanium dioxide,
No aggregated particles were observed. The color tone of the obtained polymer was 77.2% with a very high whiteness, and the yellowness was also very small and good.

Fluorescent brightener "O" based on 100 parts by weight of the obtained polyester
B-1 "(manufactured by Eastman Co.) was blended in an amount of 0.03 parts by weight and biaxially stretched 3.2 times in the longitudinal direction and 3.2 times in the transverse direction to obtain a film having a thickness of 250 μ. It was a white film with no defects and a whiteness of 95.8% and hiding power of 1.92.

Comparative Example 1 In the same manner as in Example 1, polyethylene terephthalate was obtained in which only titanium dioxide was not added. Although the particle dispersibility of calcium carbonate in the polymer and the color tone of the polymer were excellent, when the film was produced in the same manner as in Example 1, the hiding power of the film was slightly poor.

Examples 2 to 9 and Comparative Examples 2 to 6 Polyesters and films were prepared in the same manner as in Example 1 except that the added calcium carbonate, inorganic particles other than calcium carbonate and phosphorus compounds were changed as described in Table 1. Was manufactured.

The results are shown in Table-1.

Examples 2 to 9 are within the scope of the present invention and are excellent in particle dispersibility and color tone, and the films obtained from the polyester have good whiteness and hiding power without any bubble defects.

On the other hand, Comparative Examples 2 to 6 are all outside the scope of the present invention and are inferior in any of particle dispersibility, color tone, hiding power of film, and whiteness.

Example 10 In the same manner as in Example 1, polyethylene terephthalate containing 20% by weight of calcium carbonate and a P content of 450 ppm was produced.
On the other hand, polyethylene terephthalate containing substantially no inorganic particles was dry-blended with titanium dioxide having an average particle size of 0.5 μ to produce polyethylene terephthalate having 20% by weight of titanium dioxide and a P content of 70 ppm.

Calcium carbonate-containing polyethylene terephthalate
75 parts by weight and 25 parts by weight of titanium dioxide-containing polyethylene terephthalate are melt-blended with an extruder to give 15% by weight of calcium carbonate, 5% by weight of titanium dioxide and a P content of 355 p.
A polyethylene terephthalate composition of pm was obtained.

Then, a film was manufactured in the same manner as in Example 1.
The obtained film had a density of 1.245, a whiteness of 95.5% and a hiding power of 1.85, and was a good white film.

[Results of the Invention] The present invention, as described above, has a specific amount of an average particle diameter of 0.05 to 5 µm.
It is possible to obtain a polyester composition having high aggregation and high whiteness, which does not include aggregated particles which have not been obtained in the past, by incorporating calcium carbonate having an OH, inorganic particles other than calcium carbonate and a phosphorus compound into the polyester. it can.

When film-forming the polyester composition obtained by the present invention, it is possible to prevent bubbles at the time of melt extrusion, to eliminate film tear, whiteness, and to produce a white film excellent in hiding power. , X-ray intensifying screens, cards, labels, display plates, white plates, and decorative substrates.

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Claims (3)

[Claims] 1. A polyester comprising at least 80 mol% of repeating units of ethylene terephthalate, and 6 to 40 of (A) calcium carbonate having an average particle size of 0.05 to 5 μm.
A polyester composition containing 1 to 20% by weight of (B) inorganic particles other than calcium carbonate having an average particle diameter of 0.05 to 5 μm, and (C) a phosphorus compound as P atoms of 100 to 5000 ppm. 2. The polyester composition according to claim 1, wherein the inorganic particles other than calcium carbonate are titanium dioxide and zinc white. 3. The polyester composition according to claim 1, wherein the weight ratio of the content of inorganic particles other than calcium carbonate to the content of calcium carbonate is 0.05 to 2.0.