JPS5828288B2 - Polyester Hatsupoutaino Seizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing polyester foam.

Conventionally, methods for foaming polyester to obtain foam include impregnating molten polyester with soluble gas under pressure and then lowering the pressure during the curing and molding process to foam, or adding a chemical blowing agent to polyester. However, there is a method of foaming polyester by decomposing a chemical foaming agent in a molten state.

However, polyester mainly composed of polyethylene terephthalate needs to be melted at high temperatures.
There are few soluble gases or blowing agents applicable to these conditions, and it is difficult to produce foams of the polymer by conventional methods.

The present inventors have conducted extensive research into a method for producing foam from polyester with a high melting point, mainly consisting of polyethylene terephthalate. After dissolving the polyester in a solvent for the polymer to form a solution, (A) The present inventors have discovered that a foam can be obtained by mixing the polymer solution, (B) a lower fatty acid, and a mixture of (a lower alcohol in which a metal carbonate is dissolved and water), and have arrived at the present invention. .

An object of the present invention is to provide a novel method for producing a polyester foam mainly composed of polyethylene terephthalate.

Another object is to provide a polyester foam that is bulky, highly elastic, and has excellent filling properties in molds.

The present invention involves mixing three components: (4) a polyester polymer solution, a former lower fatty acid, and (C) a mixture of lower alcohol and water in which a metal carbonate is dissolved, and carbon dioxide gas is generated in the polyester polymer solution. This is a method for producing a polyester foam by generating.

That is, in the present invention, a metal carbonate chemically reacts with a lower fatty acid in a polyester polymer solution to generate carbon dioxide gas and foam the polyester in the solution.

Further, in the process of generating carbon dioxide gas, mixing of (B) and (C) lowers the solubility of polyester, causing polyester foam to precipitate.

Furthermore, since the volume of the polyester increases by 10 to 20 times during the foaming process of the polyester, the filling performance for the shape of the molded container is extremely good.

The polyester mainly composed of polyethylene terephthalate and having a melting point of 200°C or higher used as a material in the present invention is polyethylene terephthalate produced from terephthalic acid or its ester-forming derivative and ethylene glycol, or polyester mainly composed of polyethylene terephthalate component, p- Even if the main chain contains bonds other than ether bonds, such as poly-p-ethyleneoxybenzoate derived from (β-oxyethoxy)benzoic acid, the synthesis process mainly relies on the formation of ester bonds. The polymer used is a copolymerized polyester that is block or random copolymerized with a fraction of polyethylene terecrate, and furthermore, it is a copolymer that is mainly composed of polyethylene terrescrete and a synthetic polymer other than polyester. , for example, copolymers with polyalkylene glycol, polyphenylene oxide, polybenzylbenzoyl, etc.

The polyester used as the material may be of any shape, and there is no problem even if dyes, pigments, antistatic agents, fillers such as stabilizers, oils, etc. are mixed into the polymer.

Waste products from polyester moldings and waste polymers can also be used as raw materials.

The polyester concentration in the polyester solution should be selected appropriately depending on the type and amount of lower fatty acids, metal carbonates, lower fatty alcohols, etc. used, but is generally 20% by weight or less, preferably: When the amount is 15% by weight or less, a good polyester foam molded product is obtained.

When the concentration of polyester exceeds 20% by weight, the mixture with (B) lower aliphatic and (lower fatty alcohol in which q metal carbonate is dissolved) and water becomes uneven, and as shown in Figure 2. As shown schematically, only a portion of the polyester foams, and the other portions do not foam at all.

The lower fatty acids referred to in the present invention are those that react with metal carbonates to generate carbon dioxide gas.

Therefore, it is necessary to select a stronger acid than carbonic acid.

For example, formic acid, acetic acid, propionic acid, etc. can be mentioned.

The addition of lower fatty acids is 3-1% of the polyester polymer solution.
A suitable amount is 5% by weight, preferably 5-10% by weight.

When the lower fatty acid is less than 3% by weight, carbon dioxide gas generation is slow, and the polyester does not foam and is precipitated in the form of lumps or fibers.

On the other hand, when the amount of lower fatty acids added exceeds 15% by weight, precipitation occurs before the polyester is sufficiently foamed.
No foam is obtained.

The metal carbonates referred to in the present invention include alkali metal carbonate salts such as sodium carbonate and potassium carbonate; alkali metal hydrogen carbonate salts such as sodium hydrogen carbonate and potassium hydrogen carbonate;
Carbonate alkaline earth metal salts such as calcium carbonate and barium carbonate.

Further, the lower fatty alcohol that can be used in the present invention is preferably a valent or divalent lower alcohol, such as methanol, ethanol, furopanol, ethylene glycol, triethylene glycol, and the like.

The mixing ratio of the lower fatty alcohol and water is adjusted to a weight ratio of alcohol/water = 60/40 to 90/10.

When the mixing ratio of lower fatty alcohol and water is less than 60/40, the miscibility of the polyester solution and the lower fatty alcohol and water mixture decreases, making it difficult to uniformly foam the polyester.

Further, if the ratio is 90/10 or more, the solubility of the metal carbonate in the lower alcohol/water mixture decreases, and the ability to generate sufficient carbon dioxide gas for foaming polyester is lost, which is not preferable.

In the present invention, the carbon dioxide gas generation phenomenon caused by mixing a polyester solution, a lower fatty acid, a lower fatty alcohol in which a metal carbonate is dissolved, and water is a pure chemical reaction.
The mixing ratio of the polyester solution, lower fatty acid, alcohol containing metal carbonate, water mixture, carbon dioxide generation rate, etc. depend on the polyester solvent used, the type and concentration of the lower fatty acid, metal carbonate, and lower fatty alcohol. Appropriate conditions should be selected accordingly.

The method for producing polyester foam according to the invention has the advantage that foaming, precipitation and shaping can be carried out in a single step.

Further, by adjusting the carbon dioxide gas generation rate, it is possible to adjust the size of the foam holes, and bulky polyester foam molded products can be manufactured.

The polyester foam molded product obtained by the present invention has an apparent specific gravity of 0.05 to 0.1 and is extremely bulky.

In addition, since the foamed pores are continuously overlapped, it is highly elastic and has extremely good compression recovery properties.

Therefore, the polyester foam molded product of the present invention is useful as a material for cushion parts of chairs, seats, beds, etc.

Furthermore, compared to polystyrene foam and urethane foam,
Since it has excellent heat resistance and organic resistance, it can be effectively used as a heat insulating material for high temperatures or as a special packaging material.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 A polyethylene terephthalate (25°C, intrinsic viscosity in O-chlorophenol = 0.72, hereinafter referred to as PET) chip was dissolved in O-chlorophenol, and the PET concentration was 3.
, 10, 15.25 weight 70 solutions were prepared.

In a 500CC beaker in a water bath set at various temperatures,
The above PET solution 2 (l) was charged.

Next, add 2'? of 8570 formic acid to each beaker. Add and stir gently.

Further, 300 g of a mixture of methanol and water saturated with sodium hydrogen carbonate (methanol/water = 80,720 weight ratio) was added to each of the above PET solutions containing formic acid and stirred.

Carbon dioxide gas was gradually generated and PET was deposited as a foam.

After the generation of carbon dioxide gas has finished, take out the PET foam,
It was thoroughly washed with methanol and dried.

In a similar manner, a copolymerized polyester consisting of terephthalic acid, adipic acid and ethylene glycol (25°C, O-
Intrinsic viscosity in chlorophenol = 0.55, melting point 205
℃, hereinafter referred to as copolymerized PET), a foam was made.

Table 1 shows the manufacturing conditions, the apparent specific gravity of the obtained foam, the compression recovery rate, and the morphology of the foam.

The apparent specific gravity is calculated from any part of the obtained foam, 10 on each side.
A mm cube was cut out and its weight was measured.

The values in the table are the average values of n-3.

The compression recovery rate was determined from the obtained foam by 7 in each length, width, and thickness.
A rectangular parallelepiped of 0, 70, and 30 ml was cut out, and this rectangular parallelepiped was sandwiched between iron plates each having a length, width, and thickness of 1001100.2 m7H, and a weight was applied on the iron plates until the foam thickness became 10 mm.

After applying the weight for 5 minutes, the weight was removed and the rectangular parallelepiped was taken out.

Furthermore, the rectangular parallelepiped was left for 2 minutes under a load of O, the thickness of the rectangular parallelepiped was measured, and the recovery rate to the original thickness of the rectangular parallelepiped was calculated.

Form I and river in Table 1 refer to the following form observations.

Form ①: Schematically, the form is as shown in FIG. 1, and it is a foamed body in which uniform foam pores are layered in many layers.

Form (2): Schematically, the form is as shown in FIG. 2, and the size of the foamed pores is non-uniform, and some unfoamed portions are simply precipitated.

In the present invention, by appropriately selecting the polymer concentration and mixing temperature, a polyester foam having a low apparent specific gravity, that is, a high bulkiness and a good compression recovery rate can be obtained.

Example 2 An undrawn PET yarn was dissolved in 2,4-dichlorophenol to prepare a solution having a PET concentration of 10% by weight.

Next, various lower fatty acids as shown in Table 2 were added, and a mixture of methanol and water saturated with sodium bicarbonate was further added and stirred to obtain a foam.

The manufacturing conditions and properties of the obtained foam are shown in Table 2.

As is clear from Table 2, when formic acid is used as a fatty acid, it can be mixed at room temperature, but in the case of fatty acids that are relatively weak acids such as acetic acid, propionic acid, and butyric acid, mixing at high temperatures is not necessary. is preferable.

The amount of fatty acid added is about 10% by weight of the polyester solution, which gives good results for bulkiness and compression recovery.

Example 3 PET multifilament fibers (70d/14f) were dissolved in O-chlorophenol to prepare a solution with a PET concentration of 10 weight and 7°.

Next, 85% formic acid was added to 10% by weight of the solution, and the same procedure as in Example 1 was carried out using a mixture of lower fatty alcohols and water of various metal salts as shown in Table 3. I made a PET foam.

The manufacturing conditions and properties of the obtained foam are shown in Table 3.

When the mixing ratio of the alcohol/water mixture for dissolving the metal carbonate was 60/40 to 80/20, a foam of Form I having uniform foam pores was obtained regardless of the type of metal carbonate or alcohol.

Example 4 Undrawn PET lint yarn was dissolved in m-cresol to form a polymer solution with a concentration of 10% by weight.

25 g of the polymer solution was poured into a 100 CC Erlenmeyer flask and kept at 25°C in a water bath.

Next, 2.5% of 85% formic acid was added, and 40% of the mixture was further saturated with potassium hydrogen carbonate. was injected.

PET foamed as carbon dioxide gas was generated, and a foam was deposited along the glass wall.

After the foaming was completed, the glass container was broken and the foam was taken out, and a foam in the same Erlenmeyer flask shape as the glass container was obtained.

As shown in this example, the present invention has the advantage that foaming, precipitation, and molding can be performed simultaneously in the production of foam.

Example 5 Parts of the Erlenmeyer flask-shaped foam obtained in Example 4 were cut out from four locations on the upper layer, the lower layer, and the wall side and inside of the middle layer to determine the size of the foam holes. It was observed and measured using a microscope.

There was no unevenness in the size of the foam pores between each location, and the foam had excellent filling properties.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 schematically show the form of the foam obtained by the present invention. FIG. 1 shows a foamed body in which uniform foam pores overlap, and FIG. 2 shows a foamed body that partially contains unfoamed parts. *In the figure indicates an unfoamed area.

Claims (1)

[Claims] 1. Mix three components: (A) a polymer solution of polyester with a melting point of 200°C or higher, mainly consisting of polyethylene terephthalate, a former lower fatty acid, and (C) a mixture of lower fatty alcohol in which a metal carbonate is dissolved and water. A method for producing a polyester foam, characterized by: