JPH09111030A - Polyethylene terephthalate resin foam and method for producing the same - Google Patents

Abstract

(57) [PROBLEMS] To provide a polyethylene terephthalate resin foam having a low foam density, a good appearance, and a high closed cell rate, and a method for producing the same. SOLUTION: A polyethylene terephthalate resin foam obtained by extrusion-foaming a polyethylene terephthalate resin composition containing a polyethylene terephthalate resin, a polyolefin resin and an epoxy group-containing polyolefin resin, and a polyethylene terephthalate resin, a polyolefin resin. And a method for producing a polyethylene terephthalate-based resin foam, which comprises heating and melting a polyethylene terephthalate-based resin composition containing an epoxy group-containing polyolefin-based resin, impregnating a foaming agent, and then extruding and foaming in a low-pressure region.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene terephthalate resin foam and a method for producing the same. More specifically, it relates to a polyethylene terephthalate-based resin foam that can be suitably used as a packaging material, a cushioning material, a heat insulating material, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Aromatic polyesters, especially polyethylene terephthalate, have heretofore been widely used as resin raw materials for injection molded products, blow molded products, films, etc., but have poor foamability and are therefore mostly used for foams. Didn't.

In recent years, polyethylene terephthalate foams have been investigated, and in order to improve the foamability, an epoxy compound is blended as a melting property improver (Japanese Patent Laid-Open No. 53-24364), pyromellitic dianhydride. Is proposed (Japanese Patent Laid-Open No. 3-200843). However, when these melting property improvers are blended, there is a problem that coloring and foaming unevenness occur in the obtained foam.

Further, in order to improve the crystallinity of polyethylene terephthalate foam, linear low density polyethylene,
It has been proposed to add a small amount (1 to 6% by weight) of a polyolefin such as polyethylene ionomer as a crystal nucleating agent (JP-A-2-286725). However, when the above-mentioned polyolefin is added, there is a problem that a foam having uniform and fine cells cannot be obtained, and the expansion ratio thereof is improved to only about 2 times.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and it is free from wrinkles and fluff on the surface of the foam, has a low foam density, and has a high closed cell rate. An object is to provide a terephthalate resin foam and a method for producing the same.

[0006]

The present invention is a polyethylene terephthalate resin foam obtained by extrusion-foaming a polyethylene terephthalate resin composition containing a polyethylene terephthalate resin, a polyolefin resin and an epoxy group-containing polyolefin resin, And polyethylene terephthalate resin, a polyolefin resin and a polyethylene terephthalate resin composition containing an epoxy group-containing polyolefin resin are heated and melted, impregnated with a foaming agent, and then extruded and foamed in a low pressure region. The present invention relates to a method for producing a terephthalate resin foam.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the polyethylene terephthalate resin foam of the present invention is obtained by extruding and foaming a polyethylene terephthalate resin composition containing a polyethylene terephthalate resin, a polyolefin resin and an epoxy group-containing polyolefin resin. It was given to me.

Examples of the polyethylene terephthalate-based resin include not only polyethylene terephthalate but also a copolymerization component that constitutes polyethylene terephthalate, that is, ethylene glycol, and terephthalic acid or terephthalate in the copolymerization component that constitutes the polyethylene terephthalate resin. Examples thereof include dimethyl acid in a total amount of 80% by weight or more.

The amount of the copolymerization component other than the copolymerization component constituting the polyethylene terephthalate contained in the copolymerization component constituting the polyethylene terephthalate resin is 20% by weight or less, which is a representative of the copolymerization components. Examples include, for example, isophthalic acid, naphthalenedicarboxylic acid, dicarboxylic acids such as aliphatic dicarboxylic acids, and polyhydric alcohols such as propylene glycol, butanediol, and hexanediol.
They may be used alone or in combination of two or more.

Examples of the polyolefin resin include linear low-density polyethylene, high-pressure low-density polyethylene, high-density polyethylene, polypropylene, ethylene-
Examples thereof include a propylene copolymer and an ethylene-vinyl acetate copolymer.

As the epoxy group-containing polyolefin resin, considering that the resin acts as a compatibilizer and secures an effective reaction site, the epoxy group contained in the constituent components of the resin is considered. The content of the component is preferably 0.05% by weight or more, more preferably 0.3% by weight or more, and in order to suppress the deterioration of the fluidity and the surface property of the foam due to an excessive reaction excessively, The amount of the epoxy group-containing component is preferably 50% by weight or less, more preferably 30% by weight or less.

Typical examples of the epoxy group-containing component include glycidyl methacrylate, glycidyl acrylate, α-methylglycidyl acrylate, α-
Examples thereof include methyl glycidyl methacrylate, vinyl glycidyl ether, and methacryl glycidyl ether.

Typical examples of the epoxy group-containing polyolefin resin include a random copolymer and a graft copolymer of an epoxy group-containing component and polyolefin.

The epoxy group-containing polyolefin resin not only functions as a compatibilizing agent for the polyethylene terephthalate resin and the polyolefin resin and enhances the compatibility of the two, but also the polyethylene terephthalate resin and the polyolefin. It exhibits the property of cross-linking with the system resin and increasing the melt viscosity to improve the foamability.

The amount of the epoxy group-containing polyolefin resin used is 100% by weight of the total amount of the polyethylene terephthalate resin and the polyolefin resin in order to improve the foamability by sufficiently increasing the melt viscosity. 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 2 parts by weight or more is desirable, and the melt viscosity becomes too high, so that the extrusion load is not increased and the die is not clogged. Therefore, it is desirable that the amount is 30 parts by weight or less, preferably 20 parts by weight or less, and more preferably 15 parts by weight or less.

The ratio of the polyethylene terephthalate resin to the polyolefin resin (polyethylene terephthalate resin / polyolefin resin: weight ratio) is 10/90 or more in order to improve the foamability by sufficiently increasing the melt viscosity. It is preferably 20/80 or more, more preferably 95/5 or less, and particularly 90/10 or less in order to suppress the occurrence of foaming unevenness.

The polyethylene terephthalate resin,
The polyethylene terephthalate resin composition containing a polyolefin resin and an epoxy group-containing polyolefin resin may include, if necessary, a nucleating agent such as talc, baking soda, and citric acid, a stabilizer, a lubricant, an antioxidant, and a colorant. You may add such additives as long as the object of the present invention is not impaired.

In the present invention, the order and method of mixing the polyethylene terephthalate-based resin, the polyolefin-based resin, the epoxy group-containing polyolefin-based resin, and the additives optionally added are not particularly limited.

The method for producing the polyethylene terephthalate resin foam of the present invention will be described below.

According to the method for producing a polyethylene terephthalate-based resin foam of the present invention, a polyethylene terephthalate-based resin composition containing a polyethylene terephthalate-based resin, a polyolefin-based resin, an epoxy group-containing polyolefin-based resin, and an additive added if necessary. A polyethylene terephthalate-based resin foam is obtained by heating and melting the material, impregnating it with a foaming agent, and then extruding and foaming in a low-pressure region.

First, in the present invention, a kneading machine which is generally used in a molten state of a polyethylene terephthalate resin, a polyolefin resin, an epoxy group-containing polyolefin resin and, if necessary, an additive such as a nucleating agent. Knead with.

Examples of the kneader include rolls, co-kneaders, Banbury mixers, Brabenders, single-screw extruders, twin-screw extruders, and other kneaders and extruders.
Among these, an extruder is preferable from the viewpoint of productivity,
In particular, a twin-screw extruder having a large shear force for kneading the polymers is more preferable.

As a method of impregnating a polyethylene terephthalate resin composition that has been heated and melted with a foaming agent and performing extrusion foaming, for example, a polyethylene terephthalate resin composition is prepared by a kneading machine that is usually used, and then the resin composition is prepared. A method of impregnating a product with a foaming agent and then extruding it outside the kneading machine to foam, a step of kneading a polyethylene terephthalate resin composition and a step of impregnating a foaming agent and foaming can be performed at the same time Examples of the method include a method of extruding and foaming after kneading using an apparatus.

Both evaporative foaming agents and decomposable foaming agents can be used as the foaming agent.

Typical examples of the evaporative blowing agent include aliphatic hydrocarbons such as n-propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane and heptane; cyclobutane, Alicyclic hydrocarbons such as cyclopentane and cyclohexane; chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane,
Dichlorofluoromethane, dichlorodifluoromethane,
Chloromethane, dichloromethane, chloroethane, dichlorotrifluoroethane, dichlorofluoroethane, chlorodifluoroethane, dichloropentafluoroethane,
Examples thereof include halogenated hydrocarbons such as tetrafluoroethane; inorganic gases such as carbon dioxide, nitrogen and air; water and the like. These foaming agents can be used alone or in combination of two or more.

Typical examples of the decomposing type foaming agent include N, N'-dinitrosopentamethylenetetramine,
Nitroso foaming agents such as N, N'-dimethyl-N, N'-dinitrosoterephthalamide; azo foaming agents such as azodicarbonamide and barium azodicarboxylate;
p, p'-oxybisbenzenesulfonyl hydrazide,
Examples thereof include sulfohydrazide-based foaming agents such as p-toluenesulfonyl semicarbazide; trihydrazinotriazine and the like. These foaming agents can be used alone or in combination of two or more kinds.

The amount of the foaming agent used is not particularly limited and may be appropriately adjusted according to the desired expansion ratio of the foamed product obtained. Usually, the amount of the foaming agent used is about 5 to 50 parts by weight with respect to 100 parts by weight of the resin.

As a method of extruding and foaming the polyethylene terephthalate resin composition which has been heated and melted, for example, a foaming agent is preliminarily added to the resin composition by using a single-screw extruder, a tandem type extruder having two kneading regions, or the like. Examples thereof include a method of foaming by impregnating or impregnating in an extruder and extruding from a die.

The extrusion temperature may be appropriately adjusted according to the composition of the resin composition. Generally, for example, when a tandem extruder is used, the temperature of the first-stage kneading section is raised to 260 to 320 ° C., the foaming agent is injected and impregnated in the second-stage kneading section, and the extrusion temperature is set to about 240 to 270 ° C. It can be foamed by extrusion from the die into the low pressure area.

As a method of extruding and foaming using a kneading device capable of simultaneously performing the kneading step and the foaming step, specifically, for example, the raw materials are mixed at a normal temperature with a ribbon blender or the like, and the resin is mixed. A method of foaming by preparing a composition and extruding the resin composition from a die to a low pressure region using a kneading device such as a tandem type extruder having a kneading region and a foaming agent impregnated region can be mentioned.

The low pressure region is usually under atmospheric pressure,
If necessary, the atmosphere may be depressurized to be lower than atmospheric pressure.

The polyethylene terephthalate resin foam of the present invention thus obtained is lightweight, has a beautiful surface, and has a high closed cell rate, and therefore, for example, packaging materials, cushioning materials, heat insulating materials, etc. Can be suitably used as.

[0033]

EXAMPLES Next, the polyethylene terephthalate resin foam of the present invention and the method for producing the same will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 Polyethylene terephthalate (intrinsic viscosity (IV):
0.97, phenol / tetrachloroethane (volume ratio)
= Measured at 25 ° C. in a 1/1 mixed solution) 50 parts by weight,
High-pressure method low-density polyethylene (melt flow index: 0.4 g / 10 min (measured at 190 ° C.)) 50 parts by weight, ethylene-glycidyl methacrylate copolymer (Sumitomo Chemical Co., Ltd., Bond First E, glycidyl methacrylate) 8 parts by weight) and 0.5 parts by weight of talc were mixed in advance with a ribbon blender, and then the tandem type extruder with a cylinder diameter of the first stage extruder of 40 mm and a cylinder diameter of the second stage extruder of 50 mm was mixed. Supplied to the machine.

Next, the first cylinder temperature of 280 ° C.
After the resin composition was heated and melted in the single-stage extruder, 8 parts by weight of butane as a foaming agent was pressed in from a pressure inlet provided in the latter half of the first-stage extruder.

The temperature of the resin composition was 260 in the second stage extruder.
Cool it down to ℃, and use a cylindrical die (6mmφ × 25m
m) was extruded to obtain a round rod-shaped foam.

As the physical properties of the obtained foam, (a) foam density, (b) appearance and (c) closed cell ratio were examined according to the following methods. Table 1 shows the results.

(A) Foam density Measured according to JIS-K 6767.

(B) Appearance The surface of the foam was visually observed and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: No unfoamed part, wrinkles and fluff are observed. X: Unfoamed site, wrinkles or fluff are observed.

(C) Closed cell ratio According to the method described in ASTM D-2856, a multi-air pycnometer (manufactured by Beckman),
Measured using MODEL 930).

Example 2 In Example 1, linear low-density polyethylene (melt flow index: 0.3 g / 10 min (measured at 190 ° C.)) was used instead of 50 parts by weight of high-pressure low-density polyethylene.
Extrusion foaming was performed in the same manner as in Example 1 except that 50 parts by weight was used to obtain a round rod-shaped foam.

The physical properties of the obtained foam were examined in the same manner as in Example 1. Table 1 shows the results.

Example 3 In Example 1, 50 parts by weight of polypropylene (melt flow index: 0.4 g / 10 min (measured at 230 ° C.)) was used in place of 50 parts by weight of high-pressure low density polyethylene, and ethylene was used. -Round bar-shaped foaming was carried out in the same manner as in Example 1 except that 10 parts by weight of polypropylene grafted with 0.5% by weight of glycidyl methacrylate was used instead of 8 parts by weight of glycidyl methacrylate copolymer. I got a body.

The physical properties of the obtained foam were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Extrusion foaming was carried out in the same manner as in Example 1 except that the ethylene-glycidyl methacrylate copolymer was not used, but outgassing occurred and no foam was obtained. It was

Comparative Example 2 Extrusion foaming was carried out in the same manner as in Example 1 except that the amount of polyethylene terephthalate used was changed from 50 parts by weight to 100 parts by weight without using high-pressure low density polyethylene. Then, a round bar-shaped foam was obtained.

The physical properties of the obtained foam were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 In Example 3, the amount of polypropylene used was 50 parts by weight to 100 parts without using polyethylene terephthalate.
Extrusion foaming was performed in the same manner as in Example 3 except that the amount was changed to parts by weight to obtain a round rod-shaped foam.

The physical properties of the obtained foam were examined in the same manner as in Example 1. Table 1 shows the results.

[0051]

[Table 1]

From the results shown in Table 1, the foams obtained in Examples 1 to 3 have low foam density and good appearance due to the use of the epoxy group-containing polyolefin resin. Further, it is understood that it has a high closed cell rate.

[0053]

According to the present invention, a polyethylene terephthalate resin foam having a low foam density, a good appearance and a high closed cell rate is provided.

Claims (4)

[Claims] 1. A polyethylene terephthalate resin foam obtained by extruding a polyethylene terephthalate resin composition containing a polyethylene terephthalate resin, a polyolefin resin and an epoxy group-containing polyolefin resin. 2. The amount of the epoxy group-containing polyolefin resin used is 0.1 to 100 parts by weight of the total amount of the polyethylene terephthalate resin and the polyolefin resin.
The polyethylene terephthalate resin foam according to claim 1, which is 30 parts by weight. 3. A polyethylene terephthalate resin composition containing a polyethylene terephthalate resin, a polyolefin resin and an epoxy group-containing polyolefin resin is melted by heating, impregnated with a foaming agent, and then extruded and foamed in a low pressure region. A method for producing a characteristic polyethylene terephthalate resin foam. 4. The amount of the epoxy group-containing polyolefin resin used is 0.1 to 100 parts by weight of the total amount of the polyethylene terephthalate resin and the polyolefin resin.
The method for producing a polyethylene terephthalate resin foam according to claim 3, which is 30 parts by weight.