JP2001114905A - Method for manufacturing branched polylactone, its resin composition and its molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polylactone having a high melt tension and improved in moldability, its resin composition and its molded article. SOLUTION: In the method for manufacturing a branched polylactone, a polylactone is subjected to a radiation treatment so that the inclination (α) of a plotted straight line expressed by logarithm (lnλn) of nonlinear parameter λn and elongation strain ε is in the range of 0.15-4.0 in the elongation viscosity measurement at the temperature 10 deg.C higher than the melting point. The polylactone composition comprises 100 parts by mass of the resin component comprising 5-100 mass % branched polylactone and 95-0 mass % linear polylactone and/or another thermoplastic resin and 0-70 parts by mass of fillers. The molded article is obtained by molding the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polylactone composition having improved moldability, and more particularly to a polylactone composition containing a branched polylactone, which is used for foam molding, inflation molding, blow molding and vacuum molding. The present invention relates to a method for producing polylactone, which exhibits excellent moldability during thermoforming or melt kneading with another resin, and a resin composition thereof.

[0002]

2. Description of the Related Art In general, polylactones represented by polycaprolactone are not only raw materials such as urethane resins, but also polycarbonate resins, polyterephthalate resins, and the like.
In order to improve the fluidity and appearance of ABS resin and the like, melt kneading and polylactone alone have been used for various molded articles and molding materials. In recent years, the biodegradability of polylactones has attracted attention, and it has been used alone or in a mixture with other thermoplastic resins for a wide range of applications such as heat insulating materials, cushioning materials, films, bottles, and fibers. Was. However, polylactones typified by polycaprolactone have lower melt viscosities than thermoplastic resins having other high molding temperatures, and have been difficult to melt-knead with such resins. Furthermore, since these blends have a low melt tension, they cause foam breakage during foam molding, failing to obtain a sufficient expansion ratio, and are not stabilized during inflation molding, resulting in uneven thickness of the molded body. There was a problem that it easily occurred. Also, when polylactone is molded alone, in the case of conventional linear polylactone, the melt tension is low,
There were various drawbacks such as severe restrictions on molding conditions and poor production efficiency, and the use was greatly restricted. For practical use, it was essential to significantly increase the melt tension. In order to increase the melt tension of polylactone, it is considered desirable to apply a general method which is also applied to thermoplastic polyesters and polycarbonates, for example, a method using a polymer having a high degree of polymerization or a method using a polymer having a branch. However, in order to obtain a linear polylactone having a high degree of polymerization, the molar amount of the monofunctional or bifunctional initiator with respect to the lactone monomer must be set to a very small and precise molar ratio. It is necessary to minimize the amount of water that is generated. In fact, there has been no report of increasing the melt tension of polylactone by consuming such efforts, for example, Japanese Patent Publication Nos. 40-23917 and 4
Nos. 0-26557, JP-B-40-14739 and JP-A-56-49728 describe high-polymerized polylactones, but do not disclose melt tension. Regarding the possibility of using the other branched polymer, for example, trifunctional or higher functional groups such as glycerin, pentaerythritol and glycerol as disclosed in JP-B-34-5293, JP-B-41-19559 and JP-B-47-13783. Although there is a description of a branched polylactone polymerized using an initiator, this polylactone is an oligomer having a molecular weight of 10,000 or less, and was not very satisfactory in melt tension.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a branched polylactone which exhibits excellent moldability during thermoforming such as foam molding, inflation molding, blow molding and vacuum molding, and melt kneading with other resins. An object of the present invention is to provide a production method and a resin composition thereof.

[0004] In this specification, the International System of Units is used as a unit with the enforcement of the New Measurement Law. Therefore, conventionally,
“Weight” used in the meaning of mass is described as “mass”. In accordance with this, “% by weight”, “parts by weight” and the like are described as “% by weight”, “parts by weight” and the like.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that branched polylactones that have been subjected to radiation treatment under specific conditions can be used alone or as needed. By melt-kneading and using the polylactone and / or other thermoplastic resin, a melt having a high melt tension during high-temperature molding and, for example, a foam having a sufficient expansion ratio as a heat insulating material or a cushioning material in foam molding can be obtained. It is also found that a film without uneven thickness can be easily obtained with good production efficiency in inflation molding,
The present invention has been completed. A first aspect of the present invention is that, when measuring the extensional viscosity at a temperature higher by 10 ° C. than the melting point, the nonlinear parameter λn [the extensional viscosity (λ) in the nonlinear region and the extensional viscosity (λ1) in the linear region at the same extension time are used. Ratio λ
/ λl] (lnλn) and elongation strain ε [= ln (l / l
0), l0 and l are the lengths of the samples at the elongation times 0 and t, respectively.
A method for producing a branched polylactone, which comprises subjecting the polylactone resin (a) to radiation irradiation treatment so as to fall within a range of from 4.0 to 4.0. A second aspect of the present invention is that the polylactone resin (a) is a homopolymer of ε-caprolactone, methylated caprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, enantholactone, or a mixture of two or more of these. A first method for producing a branched polylactone of the present invention, which is a monomer copolymer or a mixture of these homopolymers or copolymers, is provided.
A third aspect of the present invention is the method for producing the first or second branched polylactone of the present invention, wherein the number average molecular weight (Mn) of the polylactone resin (a) is 10,000 to 1,000,000. I will provide a. A fourth aspect of the present invention is a branched polylactone produced by any one of the first to third aspects of the present invention, 5 to 100% by mass, and linear polylactone and / or another thermoplastic resin 95 to 0% by mass. A polylactone composition comprising 0 to 70 parts by mass of a filler is provided with respect to 100 parts by mass of a resin component composed of (the total of both is 100% by mass). A fifth aspect of the present invention provides a molded product obtained by molding and processing the fourth polylactone composition of the present invention.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lactone monomers usable in the present invention include various methylated caprolactones such as ε-caprolactone, 4-methylcaprolactone, 3,5,5-trimethylcaprolactone, and 3,3,5-trimethylcaprolactone. , Β-propiolactone, γ-
Butyrolactone, δ-valerolactone, enantholactone, and their alkyl and alkoxy derivatives. Further, 3-ethyl-2-keto-1,4-
Dioxanes such as dioxane and 1,4-dioxan-2-one are also applied. These lactone monomers may be used alone or as a mixture of two or more. Among these lactone monomers, ε-caprolactone, methylated caprolactone, δ-valerolactone, 3-ethyl-2-keto-1,4-dioxane and the like having the highest practical value are preferably used. The branched polylactone according to the present invention is obtained by subjecting a polylactone polymerized using the above-described monomer to a predetermined irradiation treatment. It is essential that the polylactone has a number average molecular weight of 10,000 or more, preferably 10,000 to 1,0.
00,000, more preferably 100,000 to 50
It is about 0000. When the number average molecular weight is less than 10,000, efficient crosslinking does not occur and improvement in melt tension is not expected. Conversely, when the molecular weight exceeds 1,000,000, gel is easily generated and the fluidity is rather lowered. The molecular weight was measured using gel permeation chromatography. In addition, the number average molecular weight of the branched polylactone according to the present invention is also preferably in the above range. The molecular weight distribution (definition is described later) is 2.
0 or more, preferably in the range of 2.0 to 6.0.

[0007] It is essential that the branched polylactone of the present invention be subjected to a radiation irradiation treatment so as to have the following characteristics.
The nonlinear parameter (λn) in elongational viscosity is expressed by the following formula: λ
It is obtained from n = λ / λl (see FIG. 1). Where λ
Indicates the elongational viscosity at a given temperature and at an elongation time under a given strain rate, and λl indicates the elongational viscosity in a linear region (a region where the elongational viscosity shows the same time dependency without depending on various strain rates). [References: Kiyoto Koyama, Osamu Ishizuka; Journal of the Rheological Society of Japan, 13, 93 (198
5)]. In the measurement of elongational viscosity, some resins have a so-called strain hardening property in which the elongational viscosity rapidly deviates from the linear region and rises rapidly in a high strain region depending on the type of resin. In this case, it is known that the logarithm of λn (lnλn) increases linearly with Hencky's elongation strain ε [= ln (l / l0)] (where l0 and l are the elongation times, respectively). (The length of the sample at 0 and t) [Reference: Kiyoto Koyama,
Osamu Ishizuka; Journal of the Textile Society of Japan, 37, T-258 (198
1)]. In the case of a resin having no strain hardening property, λn is 1 for an arbitrary elongation strain, and the logarithm of λn (lnλn)
Is plotted against the amount of elongation strain (ε) of Hencky, and the slope α of the straight line is 0. In the case of a resin having strain hardening property, the slope α of the linear plot does not become 0 particularly in a high strain region. In the present invention, a nonlinear parameter λn is used as a parameter representing the degree of strain hardening.
Is defined as a slope α (hereinafter, referred to as a strain hardening index) of a straight line obtained by plotting the logarithm (lnλn) of the curve with respect to the Hencky elongation strain (ε). This strain hardening index is an index indicating the fluidity and molding workability of the resin. When the strain hardening index is 0.15 to 4.0, it is found that the resin exhibits fluidity and workability that meet the purpose. Was done. That is, when the strain hardening index is 0.15 to 4.0, both the fluidity and the moldability are improved, preferably 0.35 to 3.0, more preferably 1.1 to 2.0. is there. When the strain hardening index is less than 0.15, the moldability is inferior, and as a result, the foam breaks at the time of foaming and the film becomes uneven in thickness. When the strain hardening index exceeds 4.0, the molded article is obtained. In this case, a gel is easily generated and the fluidity is poor, so that the moldability is rather deteriorated.

[0008] The branched polylactone of the present invention can be used in the form of linear polylactone and / or other thermoplastic resin.
Mixing can be performed at an arbitrary ratio of not less than mass% by using an arbitrary method. When the proportion of the branched polylactone in the total resin is 5% by mass or less, there is almost no effect of improving the moldability, which is not preferable. Usually, in order to improve moldability,
The proportion of the branched polylactone in the total polylactone is 5% by mass or more, and when mixed with another thermoplastic resin, the proportion of the branched polylactone in the total polylactone is preferably 15% by mass or more, more preferably 30% by mass. % Or more. In order to impart functionality, a filler is added in an amount of 70 to 100 parts by mass of a resin component composed of 5 to 100% by mass of branched polylactone and 95 to 0% by mass of linear polylactone and / or another thermoplastic resin. Mixing can be performed at any ratio of not more than parts by mass using any method.

Any other thermoplastic resin can be used. For example, thermoplastic polyester resin, polycarbonate resin, polystyrene resin, polyacrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin and the like are compatible with polylactone. Other preferable examples include polyamide resins, polyolefin resins such as polyethylene and polypropylene, polyphenylene oxide resins, polyether resins, and various copolymer resins. The thermoplastic polyester resin is a glycol having 2 to 6 carbon atoms as a glycol component, such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and glycol such as hexanediol and a dicarboxylic acid component such as terephthalic acid.
Polyester having a skeleton combined with a dicarboxylic acid such as isophthalic acid, phthalic acid, maleic acid, succinic acid, and adipic acid, and if necessary, other components such as lactone oxycarboxylic acid, alcohol, and trifunctional or higher polyhydric alcohol. , A carboxylic acid and a polyester having a trifunctional or higher polyvalent carboxylic acid in the skeleton. The polycarbonate resin is a polycarbonate produced by reacting a dihydric phenol such as bis-A with phosgene (phosgene method) or by reacting a dihydric phenol with a carbonate (ester exchange method). A polystyrene-based resin is a polymer polymerized from a styrene monomer and a monomer such as acrylonitrile, butadiene, (meth) acrylate, and specifically, a polystyrene resin, a HIPS resin, an AS resin, an ABS resin, and MMA-styrene. And copolymers. With respect to the polylactone composition of the present invention, epoxy resins, urethane resins, thermosetting resins such as melanin resins, starch, cellulose, and other naturally occurring biodegradable polymers and modified products thereof, glass fibers, talc Inorganic fillers such as mica, silica, titanium oxide, aluminum oxide, and metal powder, and one or more additives such as heat stabilizers, lubricants, flame retardants, pigments, and plasticizers can be arbitrarily mixed. In particular, the branched polylactone or polylactone composition 7 of the present invention
By adding 30 to 0.2% by mass of silica (silicon oxide), aluminum oxide, etc. to 0 to 99.8% by mass (the total of both is 100% by mass), the heat resistance of the surface of the molded product is obtained. It is preferably used depending on the application because of its enhanced properties.

The method of mixing a linear polylactone and / or another thermoplastic resin and / or a filler with the branched prolactone of the present invention is not particularly limited. Kneading may be performed by a kneading method using a conventionally known single-screw extruder, twin-screw extruder, roll kneader, Brabender or the like.

In the present invention, as the polylactone to be subjected to the radiation irradiation treatment, those which do not soften at room temperature are particularly preferable. From this viewpoint, polycaprolactone having a high molecular weight and a melting point of 60 ° C. or more, which is easy to obtain stable performance, is preferable. is there. In the present invention, the radiation may be irradiated at any stage before, during, or after the molding, but is preferably performed on the powdered or pelletized polylactone resin before the molding.

As a radiation source used in the radiation irradiation treatment according to the present invention, α-rays, β-rays, γ-rays, X-rays, electron beams, ultraviolet rays and the like can be used.
Γ-rays, X-rays and electron beams are more preferable.
Electron beam irradiation treatment according to the specifications of the electron beam or electron accelerator is most convenient for introducing a bridge structure of a polymer material. The irradiation dose is
As described above, the strain hardening index of a branched polylactone resin, which is a measure for introducing a bridge structure of a polymer, is determined as one measure. That is, the strain hardening index of the branched polylactone is 0.15 to 4.0, preferably 0.35 to 3.0.
Irradiation treatment may be applied to the powder or pellet-like polylactone so as to be more preferably 1.1 to 2.0. When the strain hardening index of the branched polylactone is less than 0.15 by the radiation irradiation treatment, the moldability is poor, and as a result, the foam breaks at the time of foaming and the film becomes uneven. Further, the strain hardening index is 4.
If it exceeds 0, gel tends to be generated in the molded article, and the flowability is poor, so that the moldability is rather lowered. The atmosphere during the radiation treatment is not particularly limited, but it is advantageous that the lower the oxygen concentration, the higher the bridging efficiency and the smaller the irradiation dose.

[0013]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples. Note that “%” described in Examples and Comparative Examples indicates “% by mass” unless otherwise specified. The physical properties of the resin were measured by the methods described below. (1) Elongational viscosity Measurement temperature; temperature higher by 10 ° C. than melting point (70 ° C. in case of polycaprolactone as a typical example of polylactone), strain rate: 0.005 to 0.5 sec ⁻¹ , MELTEN R
HEOMETER (manufactured by Toyo Seiki Co., Ltd.). Measurement method: After supporting both sides of a strand-shaped measurement sample with a pinch roller, the sample is rotated at a constant strain rate to apply elongation deformation to the measurement sample, and the cross-sectional area of the sample being deformed and the torque applied to the pinch roller are detected. Thus, the extensional viscosity was determined. (2) Strain hardening index (α) (see FIGS. 1 and 2) In a linear plot of the logarithm (lnλn) of the nonlinear parameter λn and the amount of elongation strain ε, the difference between lnλn at any two points is calculated as The resulting value is called the strain hardening index. Strain hardening index (α) = (lnλn2-lnλn1) / (ε
2-ε1) = (lnλn2-lnλn1) / [ln (l2 / l
0) -ln (11/10)] (3) Molecular weight, molecular weight distribution A polymer solution eluted by gel permeation chromatography (GPC) at 40 ° C. using chloroform as an eluent is a differential refractive index detector and a differential pressure viscosity detector. The molecular weight and the molecular weight distribution (the ratio between the number average molecular weight and the weight average molecular weight) were determined using a universal calibration curve and intrinsic viscosity calibrated with standard polystyrene.

[Examples 1 to 5, Comparative Examples 1 to 3] Pellets of polycaprolactone (trade name “Placcel H7”, manufactured by Daicel Chemical Industries, Ltd.) (hereinafter referred to as PCL) were placed in a vacuum-sealed bag. Under the conditions described in the present invention, gamma rays were emitted at 5, 10, 30, 50, 70, 100, and 200 k, respectively.
Gy irradiation was performed. Table 1 shows these physical property values.

[0015]

[Table 1]

According to the results shown in Table 1, the irradiated PCL and the unirradiated PCL (both may be abbreviated as PCL unless the meaning is clarified) have almost the same molecular weight. It is clear that the strain hardening index is greatly improved due to the entanglement of the irradiated PCL. However, in Comparative Example 3, although the strain hardening index showed a large value, the fluidity was extremely reduced.

Examples 6 to 14 and Comparative Examples 4 and 7 The foam moldability (expansion ratio, polyfoaming ratio) of the polylactone compositions mixed in Examples 1 to 5 and Comparative Examples 1 to 3 by changing the composition ratio of PCL.
The uniformity of the foam cells, the ejection stability during extrusion) and the appearance (surface irregularities such as rough skin) were evaluated. The results are shown in Table 2. Expansion ratio: Calculated from the ratio of the volume that increases when the obtained foam is immersed in water to the volume obtained from the mass of the foam and the resin density. Cell uniformity: ・ ・ ・: uniform throughout the foam. Δ: non-uniform in a part of the inside of the foam. X: Non-uniform throughout the foam. Discharge stability: ・ ・ ・: Pressure fluctuation and melt fracture do not occur. Δ: slight pressure fluctuation occurs, but no melt fracture occurs. X: Both pressure fluctuation and melt fracture occur. Appearance of foam: ○: Uniform rod shape, no surface roughness △: Partially non-uniform rod shape,
There is no rough surface. ×: The rod becomes non-uniform and the surface is rough. Molding machine: Ikegai's foam molding machine (50-65 tandem extruder, die diameter 2.8 mm), molding temperature; 120 ° C, foaming agent; 142b

[0018]

[Table 2]

From the results shown in Table 2, it is clear that PCL exhibiting a large value of the strain hardening index has a large expansion ratio, good appearance of the foam, and excellent moldability (Example 6).
-10). Also, when the branched PCL and the linear PCL are mixed, the PCL having a large strain hardening index is 5%.
It was found that the moldability was maintained if it was contained at a ratio of not less than mass% (Examples 11 to 14). On the other hand, PCL having a small strain hardening index is inferior in moldability due to poor expansion ratio and cell uniformity (Comparative Example 5), and when branch PCL and straight-chain PCL are mixed, the strain hardening index is low. It is clear that if the large PCL is less than 5% by mass, the moldability is also poor. (Comparative Example 7). In addition, the linear PCL did not foam, and the PCL subjected to the extreme radiation treatment could not be foamed due to poor fluidity (Comparative Example 4).
And 6).

[Examples 15 to 19, Comparative examples 8 to 10] Molding of blown film using polylactone composition obtained by mixing PCL of Example 3 and Comparative example 1 with changing the composition ratio of thermoplastic resin and filler. The properties were evaluated, and the results are shown in Table 3. Sample: C: Branched PCL (Example 3) F: Linear PCL (Comparative Example 1) I: General-purpose polystyrene; manufactured by Toyo Styrene Co., Ltd., trade name “Toyostyrol 31N” (Mw = 350,000, MFR)
= 2.5 g / 10 min) J: talc; trade name “PH talc” manufactured by Takehara Chemical Co., Ltd. (average particle size: 6 μm, no surface treatment) Bubble stability: ・ ・ ・: No flapping, stable. Δ: There is a little flapping, but the bag does not break.
X: Large flapping and breaking the bag. Thickness uniformity: The ratio of variation in circumferential film thickness was measured. Take-up speed: The speed at which the film was wound was measured. The faster the speed, the higher the production efficiency. Molding machine: Placo inflation device Die diameter 400mm, slit 0.7mm, spiral mold upward Molding temperature 200 ° C, film thickness 30μm

[0021]

[Table 3]

From the results shown in Table 3, it is clear that PCL showing a large value of the strain hardening index has good bubble stability and thickness uniformity, and also has extremely excellent production efficiency (Example 15). Also, when the branched PCL is mixed with the linear PCL and / or the thermoplastic resin and / or the filler, the PCL having a large strain hardening index is 20% by mass.
It was found that the moldability was maintained when the content was at the above ratio (Examples 16 to 19). On the other hand, when 80% by mass of a filler is added to PCL showing a large value of the strain hardening index, the bubble stability is poor and the bag is broken (Comparative Example 10). It was found that molding was not possible (Comparative Example 8).

[0023]

According to the present invention, by subjecting polylactone to radiation treatment under specific conditions, that is, exhibiting specific properties, and forming a bridge structure in the polylactone, the melt tension during high-temperature molding can be reduced. Thus, for example, a foam having a sufficient expansion ratio as a heat insulating material and a cushioning material can be obtained in foam molding, and a film without uneven thickness can be easily obtained with good production efficiency in inflation molding.

[Brief description of the drawings]

FIG. 1 shows the relationship between elongation time and elongational viscosity when determining a nonlinear parameter λn.

FIG. 2 shows a linear plot of the logarithm (lnλn) of the nonlinear parameter λn and the elongation strain ε for the sample B obtained in Example 2.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F070 AA47 AC15 AC23 AC27 AC28 AC72 AC75 AC76 AC77 AC78 AC83 AC87 AC88 AC89 AD01 AD02 HA02 HA03 HA04 HB01 4F071 AA02 AA41 AA42 AA43 AA43X AA53 AA81 AB18 AB26 AB28 AF06Y AG05 A04 A04 A BA01 BB05 BB06 BB09 BC01 BC04 BC17 4J002 AA01Y AB01Z AB04Z BB00Y BC02Y BD03Y BD10Y BG00Y CC18Z CD00Z CF03Y CF19W CF19X CG00Y CH00Y CH07Y CK02Z CL00Y DA066 DE136 DE146 DJ016 DJ04601000 DG00 FA0 006 EG05 EG07 EG08 EG09 KD11 KD12 KD13 KH03 KH08

Claims (5)

[Claims] In the measurement of extensional viscosity at a temperature higher by 10 ° C. than the melting point, a nonlinear parameter λn [the ratio of the extensional viscosity (λ) in the nonlinear region to the extensional viscosity (λ1) in the linear region at the same extension time λ / λl] and the slope (α) of the linear plot represented by the logarithm (lnλn) and the amount of elongation strain ε [= ln (l / l0), l0, l are the lengths of the sample at elongation times 0 and t, respectively] A method for producing a branched polylactone, which comprises subjecting the polylactone resin (a) to radiation irradiation so as to be in the range of 0.15 to 4.0. 2. The polylactone resin (a) is a homopolymer of ε-caprolactone, methylated caprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, enantholactone, or a copolymer of two or more of these monomers. The method for producing a branched polylactone according to claim 1, wherein the method is a polymer or a mixture of a homopolymer or a copolymer thereof. 3. The process for producing a branched polylactone according to claim 1, wherein the number average molecular weight (Mn) of the polylactone resin (a) is 10,000 to 1,000,000. 4. A branched polylactone produced by the production method according to claim 1, which is 5 to 100% by mass.
A polylactone composition comprising 0 to 70 parts by mass of a filler with respect to 100 parts by mass of a resin component composed of 95 to 0% by mass of a linear polylactone and / or another thermoplastic resin. 5. A molded product obtained by molding the polylactone composition according to claim 4.