JPH10101917A - Polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene terephthalate base saturated polyester resin composition satisfactory in both transparency and impact resistance. SOLUTION: This composition comprises 99-60wt.% polyethylene terephthalate base saturated polyester resin and 1-40wt.% two-layer structure polymer particles each of which is composed of 50-90wt.% core comprising a polymer having a glass transition temperature of -10 deg.C or below and 10-50wt.% shell comprising a radical-polymerizable monomer and having a glass transition temperature of 50 deg.C or above and satisfies the formula: |f×y1+(1-f)×y2-x|<=0.005 (wherein x is the refractive index of the saturated polyester resin, y1 is the refractive index of the core of a two-layer structure polymer particle; y2 is the refractive index of the shell; and f is the weight fraction of the core based on the entire two-layer structure polymer particle).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyester resin composition containing specific double-layered polymer particles having excellent transparency and impact resistance.

[0002]

2. Description of the Related Art Polyethylene terephthalate-based saturated polyester resins are excellent in properties such as transparency, mechanical properties, gas barrier properties and the like. For example, they are used for filling juices, soft drinks, seasonings, oils, cosmetics, detergents and other products. In recent years, it has come to be widely used as a material of a container for carrying out. In addition, applications in which transparency is used, such as materials for films and sheets, lenses, and materials for packaging, are expanding. Among them, for example, in a state where a relatively large-capacity container is filled with contents, the container tends to be easily damaged by an impact when dropped, and therefore, a high impact resistance is required for a saturated polyester resin. ing.

Hitherto, many methods for improving the impact resistance of a polyethylene terephthalate-based saturated polyester resin have been proposed. One of them is to improve the impact strength by copolymerizing a small amount of a component with polyester. . For example, in Japanese Unexamined Patent Publication (Kokai) No. 6-211973, the notched Izod impact strength is from 1.9 kgcm / cm to 4.9 kgcm / cm by copolymerization of bishydroxyethoxybenzene, bishydroxyethoxyethoxybenzene and the like.
Has been shown to improve. Also known is a method of improving impact resistance by blending a resin other than polyester, for example, a polyolefin resin.

[0004]

In the above-mentioned method by copolymerization, the improvement of impact resistance cannot be said to be sufficient, and a method of improving impact resistance by blending a resin other than polyester, For example, a blend with a polyolefin-based resin has improved impact resistance but significantly impairs transparency. For example, it is not easy to select a resin for blending that can achieve both high impact resistance and high transparency. Accordingly, an object of the present invention is to provide a polyethylene terephthalate-based saturated polyester resin composition having both transparency and impact resistance.

[0005]

As a result of repeated studies by the present inventors to achieve the above-mentioned object, it has been found that the resin composition of the double-layered polymer particles and the polyethylene terephthalate-based saturated polyester resin has a double-layered structure. A specific rubber layer is employed as the inner core of the coalesced particles, a polymer comprising a radically polymerizable monomer as the outer shell and having a glass transition temperature of 50 ° C. or higher is formed. Transparency and impact resistance by making the average refractive index of the bilayer polymer particles obtained from the refractive index of the inner core, the refractive index of the outer shell, and the weight fraction of the inner core of the layered polymer particles close to a certain value or less The inventors have found that the properties can be satisfied at the same time, and have reached the present invention.

That is, the present invention mainly comprises (1) a polyethylene terephthalate-based saturated polyester resin 99
And (2) (A) the glass transition temperature is-
A two-layer polymer comprising 50 to 90% by weight of an inner core composed of a polymer having a temperature of 10 ° C. or lower, and 10 to 50% by weight of a shell having a glass transition temperature of 50 ° C. or more and (B) a radical polymerizable monomer. The saturated polyester resin has a refractive index of x, a refractive index of the inner core of the double-layered polymer particles is y1, a refractive index of the outer shell is y2, and a refractive index of the inner core in the entire double-layered polymer particles is 1 to 40% by weight. When the weight fraction is f,
A polyester resin composition characterized by satisfying the following equation: | f × y1 + (1-f) × y2-x | ≦ 0.005 (1)

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene terephthalate-based saturated polyester resin modified by the present invention includes:
From the viewpoint that crystallinity is not substantially observed or low and transparency is good, for example, a diol in which 80 mol% or more is ethylene glycol and a diol in which 80 mol% or more are terephthalic acid or an alkyl ester thereof are used. A homopolymer, a copolymer obtained by condensation polymerization of dicarboxylic acids or a mixture of these polymers can be preferably used. As the copolymer, for example, another dicarboxylic acid such as 20 mol% or less of all carboxylic acids, for example, Examples thereof include copolymers of isophthalic acid or halogenated terephthalic acid, and copolymers of poly (alkylene glycol) in a range of 20 mol% or less of the total diol.

The two-layer polymer particles of the present invention are formed by polymerizing a polymer having a glass transition temperature of -10 ° C. or lower as an inner core, and further polymerizing a radical polymerizable monomer with respect to the polymer. It has an outer shell showing a glass transition point of 50 ° C. or higher. Here, when the glass transition temperature of the polymer of the inner core component is higher than -10 ° C, the impact resistance of the resin composition with the saturated polyester is insufficient. Further, when the glass transition temperature of the polymer of the outer shell component is lower than 50 ° C., the handleability is reduced because the two-layer polymer particles exhibit tackiness, and the resin composition with a saturated polyester is used. In some cases, the effect of improving impact resistance may be insufficient.

The monomers used in the polymerization for forming the inner core include a diene compound, an aromatic methacrylate and / or an aromatic methacrylate since the glass transition temperature is -10 ° C. or less and the above formula (1) is easily satisfied. Preferred is a mixture with an aromatic vinyl compound. As the diene compound, for example, butadiene and isoprene can be used. Further, the monomer component copolymerized with the diene compound can be selected from radically polymerizable aromatic methacrylates and aromatic vinyl compounds that can be generally used in emulsion polymerization. And an ester of methacrylic acid and an aromatic compound having an alcoholic or phenolic hydroxyl group. As the aromatic methacrylate, phenyl methacrylate is preferable, and as the aromatic vinyl compound, styrene is preferable.

[0010] The polymer forming the inner core of the bilayer polymer particles used in the present invention preferably has a crosslinked molecular chain structure in order to function as an elastic body.
Further, it is desirable that the molecular chain in the inner core and the molecular chain in the outer shell are grafted by a chemical bond. When a monomer containing a diene compound as an essential component as described above is used as a raw material of the polymer that forms the inner core, since the diene compound itself functions as a crosslinking point or a graft point, a polyfunctional polymerizable monomer is used. The body is not necessary. However, if desired, a small amount of a polyfunctional polymerizable monomer such as triethylene glycol diacrylate, 1,6-hexamethylene glycol diacrylate, or allyl methacrylate (preferably a total polymerizable monomer for forming an inner core) is used. If it is 2 mol% or less), they may be used in combination.

The outer shell of the two-layer polymer particles used in the present invention may be formed, for example, by the emulsion polymerization method in the presence of the polymer particles constituting the inner core as described above in the glass transition point of the outer shell portion formed. Is obtained by polymerizing a radically polymerizable monomer selected in such a combination that the temperature becomes 50 ° C. or higher. Examples of the radical polymerizable monomer used to form the shell include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; methacrylates having an alicyclic skeleton such as cyclohexyl methacrylate and isobornyl methacrylate; A methacrylic acid ester having an aromatic ring such as phenyl methacrylate; an aromatic vinyl compound such as styrene; acrylonitrile; and a shell component in which one or more of these radically polymerizable monomers are formed. Are used in such a combination that the glass transition temperature derived from the polymer part constituting is 50 ° C. or higher. Preferred radical polymerizable monomer systems include methyl methacrylate or styrene alone or a combination of two or more radical polymerizable monomers containing the same as a main component.

Further, the kind of these monomer components and the ratio of the inner core and the outer shell made of the same are x as the refractive index of the saturated polyester resin, y1 as the refractive index of the inner core of the double-layered polymer particles, and y1 as the outer shell. Assuming that the refractive index is y2 and the weight fraction of the inner core in the whole of the two-layer polymer particles is f, the following expression is satisfied: | f × y1 + (1-f) × y2−x | ≦ 0.005 (1) Must be a combination. If the value (absolute value) on the left side of the above equation (1) is larger than 0.005, transparency becomes insufficient. Here, the refractive index is
Saturated polyester resin, the same polymer that composes the inner core, and the same polymer that composes the outer shell are individually prepared, and then rapidly cooled and solidified after being heated to a moldable temperature without substantial thermal decomposition Can be measured by using a sample obtained by the above method.

The weight ratio between the inner core and the outer shell in the two-layer polymer particles is 50/50 to 90/10 in the inner core / outer shell.
Is within the range. If the amount of the polymer part forming the inner core is too small, the modifying effect may be insufficient, and if the amount of the polymer part forming the outer shell is too small, the handleability of the two-layer structure polymer particles is reduced. In addition, the modifying effect of the resin composition may be insufficient. The particle diameter of the bilayer polymer particles is 0.05 to 0.5 μm in average.
Is preferably within the range.

The polymerization method for producing the two-layered polymer particles in the present invention is not particularly limited. For example, the two-layered polymer particles can be easily obtained by following a usual emulsion polymerization method. it can. In the emulsion polymerization method, a chain transfer agent such as octyl mercaptan and lauryl mercaptan can be used as necessary according to a known method. After the emulsion polymerization, the separation and acquisition of the two-layer polymer particles from the polymer latex can be performed by a known method, for example, a coagulation method.

The mixing ratio of the saturated polyester resin and the double-layered polymer particles is 1 to 40% by weight of the double-layered polymer particles based on 99 to 60% by weight of the saturated polyester resin.
When the blending ratio of the two-layer polymer particles is further large, the obtained polyester resin composition is softened and the strength becomes insufficient. When the blending ratio of the two-layer polymer particles is less than 1% by weight, the resulting polyester resin composition has insufficient impact resistance.

The polyester resin composition of the present invention may contain other components, if necessary, in addition to the saturated polyester resin and the two-layer polymer particles, as long as the object of the present invention is not impaired. Other components that can be blended include light or heat stabilizers such as ultraviolet absorbers and antioxidants; modifiers such as epoxy resins and fatty acid ester waxes; mold release agents; fluidity improvers; And the like.

The polyester resin composition of the present invention can be obtained by mixing the above-mentioned saturated polyester resin, polymer particles having a two-layer structure, and other components as desired. The method for mixing these is not particularly limited as long as it is a method that can be substantially uniformly mixed as a whole, and a known method generally used for mixing resins can be applied. For example, when the melt mixing method is adopted, the saturated polyester resin and the two-layer polymer particles are melt-kneaded at 200 to 300 ° C. using a screw type extruder after appropriately adding other components as required. I just need. The double-layered polymer particles that can be used for the production of the polyester resin composition may be any particles that can be sufficiently dispersed in the form of particles when mixed with a saturated polyester resin. Alternatively, they may be in the form of pellets fused to each other at their outer shells.

In the polyethylene terephthalate resin composition of the present invention, the two-layered polymer particles may not be completely melted, but the composition as a whole has excellent melt fluidity, and can be obtained by injection molding, press molding, A desired molded article can be formed by any molding method such as blow molding, calender molding, and cast molding.

[0019]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each measured value was measured as follows. Refractive index measurement Only the inner core of the two-layer structure polymer particles, the polymer having the same monomer composition as the outer shell, and the polyethylene terephthalate resin are individually heated and softened or melted at a temperature at which molding is possible. Into a thin flat plate. This was measured using an Atago Abbe refractometer according to JIS.
The refractive index was measured according to K7105. Measurement of Glass Transition Temperature The glass transition temperature was measured by a differential scanning calorimetric analysis method using a METTLER TA3000 manufactured by METTLER, at a heating rate of 10 ° C./min according to JIS K7121. Impact resistance test of resin composition 30 mm length x 5 width at 270 ° C using a small injection molding machine
Injection molding to a size of 2.7 mm x 2.7 mm, cutouts were cut in the obtained molded product to prepare test pieces, and small Izo
The impact strength at 23 ° C. was measured using a d tester. Transparency test of resin composition The resin composition was press-molded into a flat plate having a thickness of 1 mm in the same manner as in the refractive index measurement, and the transparency was visually determined. ◎ indicates transparent, and × indicates cloudy and opaque. Further, the total light transmittance and the haze value were measured according to JIS K7105.

Example 1 In an autoclave, 250 parts by weight of distilled water, 1.0 part by weight of sodium lauroyl sarcosinate as an emulsifier, 0.334 part by weight of Rongalite (formaldehyde sodium sulfoxylate), 0.016 part of disodium ethylenediaminetetraacetate Parts by weight and ferrous sulfate heptahydrate
008 parts by weight were charged and stirred for 30 minutes while replacing with nitrogen. Next, 50 parts by weight of phenyl methacrylate and 50 parts by weight of butadiene were added, the temperature was raised to 50 ° C., and this temperature was maintained for 30 minutes. Next, at the same temperature, 0.2 part by weight of cumene hydroperoxide was added to initiate polymerization. After 4 hours, gas chromatography confirmed that all the monomers had been consumed.

Next, the obtained copolymer latex was transferred to a polymerization vessel equipped with a stirring blade, a cooling pipe and a dropping funnel under a nitrogen atmosphere, and heated to 70 ° C. Further, after adding 0.1 part by weight of potassium peroxodisulfate, 27.4 parts by weight of methyl methacrylate was added dropwise from a dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was continued at 70 ° C. for another 30 minutes, and the polymerization was terminated after confirming that the monomer was consumed. When the average particle diameter of the obtained latex was determined by a dynamic light scattering method, it was 0.09 μm. This is -2
After cooling to 0 ° C. for 24 hours for coagulation, the coagulated material was taken out and washed three times with 50 ° C. water. Further, the polymer was dried under reduced pressure at 80 ° C. for 2 days to obtain bilayer polymer particles.

Twenty parts by weight of the two-layered polymer particles obtained by the above method and 80 parts by weight of polyethylene terephthalate having an intrinsic viscosity of 1.0 were rotated at 270 ° C. using a Labo Plastmill manufactured by Toyo Seiki Co., Ltd. By melt-mixing at several hundred rpm, a polyester resin composition was obtained. Table 1 shows the evaluation results of the impact resistance and the transparency of the obtained polyester resin composition.

Examples 2 and 3 and Comparative Examples 1 to 3 In the same manner as in Example 1, two-layer polymer particles having the monomer composition shown in Table 1 were obtained. A polyester resin composition by melt mixing with polyethylene terephthalate was also obtained by the same method and composition as in Example 1. Table 1 shows the evaluation results of the impact resistance and the transparency of the obtained polyester resin composition.

[0024]

[Table 1]

The meanings of the symbols used in the tables are as follows. Bd: Butadiene PhMA: Phenyl methacrylate St: Styrene MMA: Methyl methacrylate Tg: Glass transition temperature For each monomer represented by the above abbreviation, the unit “part” in the table means “part by weight”. The unit “%” of the “core ratio” in the table means “% by weight”. The “difference in refractive index” in the table is “[(inner core ratio) / 100] × (refractive index of inner core).
+ [1− (inner core ratio) / 100] × (refractive index of outer shell) −
(Refractive index of polyethylene terephthalate). " “NB” means “not destroyed”.

In Example 1, the inner core was Bd and PhM
It is made of A and has a refractive index of 1.570, and the outer shell is made of St and has a refractive index of 1.590. The core ratio is 78.5% by weight
Therefore, the left side of Expression (1) is 0.001, which satisfies Expression (1). Furthermore, the glass transition temperatures of the inner core and the outer shell are respectively -10 ° C or less (-32 ° C) and 50 ° C.
That is (99 ° C.). And this resin composition is excellent in impact resistance and transparency. On the other hand, in Comparative Example 1, similarly, the inner core is made of Bd and PhMA, but the composition ratio is different, and the refractive index is as high as 1.584. Accordingly, the ratio of the inner core and the configuration of the outer shell are the same as those of the embodiment, but the left side of the equation (1) is 0.01, which does not satisfy the equation (1). Furthermore, the glass transition temperature of the inner core is higher than -10C (-2C). And both impact resistance and transparency are inferior.

In Example 2, the inner core is Bd and Ph
MA, refractive index of 1.565, outer shell of St and M
Since it is composed of MA and the ratio of the inner core is 64.0% by weight, the left side of the equation (1) is 0.002, which satisfies the equation (1). This resin composition is excellent in impact resistance and transparency. On the other hand, in Comparative Example 2, the inner core was the same as in Comparative Example 1, and St and MMA were used for the outer shell. Equation (1)
Is 0.001 and satisfies the expression (1), and the transparency is good. However, the glass transition temperature of the inner core is as high as that of Comparative Example 1 (−2 ° C.), and the impact resistance is inferior.

In Example 3, the inner core is Bd and St.
The refractive index is 1.563, the shell is St, the refractive index is 1.590, and the ratio of the inner core is 60.0% by weight. Therefore, the left side of the equation (1) is 0.001, and the equation (1) )
Meet. This resin composition is excellent in impact resistance and transparency. On the other hand, in Comparative Example 3, the ratio of the inner core was 80.0% by weight, and the left side of the expression (1) was 0.007, which did not satisfy the expression (1). Opaque.

[0029]

According to the present invention, a novel polyester resin composition excellent in both transparency and impact resistance can be obtained by selecting and using bilayer polymer particles satisfying specific conditions. Is provided.

[Table 1]

Claims (1)

[Claims] 1. Mainly (1) 99 to 60% by weight of a polyethylene terephthalate-based saturated polyester resin; and (2) (A) 50 to 90% by weight of an inner core made of a polymer having a glass transition temperature of -10 ° C. or lower; And (B)
It is composed of a radical polymerizable monomer and has a glass transition temperature of 50
2 to 40% by weight of a double-layered polymer particle composed of 10 to 50% by weight of an outer shell having a temperature of not less than C. The refractive index of the saturated polyester resin is x, the refractive index of the inner core of the double-layered polymer particle is y1, and the outer shell Where y2 is the refractive index and f is the weight fraction of the inner core in the entire double-layered polymer particle, | f * y1 + (1-f) * y2-x | ≤0.005 (1) is satisfied. A polyester resin composition characterized in that: