JPH10315260A - Manufacture of synthetic resin foamed molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely and easily manufacture a synthetic resin foamed molded body having an enough mechanical strength by a method wherein a thermoplastic resin molded body, which swells through the contact with a specified mixed solution under the normal temperature and pressure, is heated up to the temperature, which is higher than its thermal deformation temperature and lower than its melting point, and pressurized and then gradually reduces the heightened pressure for expanding the molded body. SOLUTION: A thermoplastic resin molded body swells by being brought into contact with a mixed solution consisting of three components or water (a component A), an alcohol having two or less carbon atoms within its molecule (a component B) and an organic solvent having the boiling point of 50-150 deg.C under the normal temperature and pressure. Next, this thermoplastic resin molded body is heated up to the temperature, which is higher than its thermal deformation temperature and lower than its molting point, and pressurized and, after that, gradually reduces the heightened pressure for expanding the molded body. The volumetric ratio of the component A to the component B is prepared so as to realize a homogeneous mixed solution by preparing the degree of swelling of the thermoplastic resin molded body under low toxicity. Thus, the influence of toxicity during working can be reduced and a synthetic resin foamed molded body, in which an enough mechanical strength its maintained, can be easily and safely manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a synthetic resin foam molded article.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a synthetic resin foam molded article, for example, a thermoplastic resin molded article such as polycarbonate is impregnated with an organic solvent, and this is sealed in a molding die and pressurized. After heating above the melting point,
There is known a method in which the molded body is cooled to a temperature range from the glass transition temperature to the melting point, and foamed by depressurizing the inside of the molding die. Examples of such methods include:
JP-B-63-4502 (hereinafter referred to as method 1).
Can be mentioned.

However, in the production method of the above-mentioned method 1, the degree of swelling is increased because the thermoplastic resin molded article is impregnated with only an organic solvent in advance, and the synthetic resin foam molded article after heating and pressurization is excessively foamed, resulting in excessive mechanical expansion. There is a problem that strength is reduced and the material becomes brittle. In addition, when a problem of toxicity in the working environment due to the organic solvent occurs, and when the step of charging the molded body into a pressure vessel containing an organic solvent and heating is employed, there is a problem in working safety, and However, there is a problem that the cost is high because special equipment is required, and the production efficiency is low.

In an attempt to solve the problem in the above-mentioned method 1, the present inventors have previously disclosed a method of impregnating a thermoplastic resin molded article with a mixed solution of water or an alcohol and an organic solvent in Japanese Patent Application No. Hei 9 (1994) -189,197. No. -4708 (hereinafter referred to as method 2).

However, in the production method of the above method 2, it is difficult to uniformly dissolve it depending on the kind of the organic solvent to be mixed and the mixing ratio with the mixed water or alcohol having 2 or less carbon atoms.

[0006] In particular, when an organic solvent is dissolved in water or when water is dissolved in an organic solvent, their mixing ratio is limited. That is, the amount of the organic solvent that can be uniformly dissolved or the amount of water that can be uniformly dissolved in the organic solvent is limited, and it is impossible to dissolve more than a specific amount.

Under the heterogeneous mixed solution as described above, for example, the amount of the organic solvent is increased with respect to water, or the amount of water is increased with respect to the organic solvent as compared with the conventional mixed solution. It has been found that, when the molded body is brought into contact with and swelled, it is difficult to uniformly foam even if the molded body is heated and pressurized and then foamed. This is due to the fact that the mixed solution is not a homogeneous system, so that a portion that contacts the organic solvent and a portion that contacts the water are generated during swelling.

The present invention has been made in order to address the above-mentioned conventional problems. A thermoplastic resin molded article is selected, and water, an alcohol having 2 or less carbon atoms, a boiling point of 50% or less are selected.
After swelling by contacting with a mixed solution consisting of three components with an organic solvent at a temperature of up to 150 ° C., if this is heated and pressurized and foamed, the mechanical strength close to the original mechanical strength of the thermoplastic resin molded article is maintained. They have found that a uniformly foamed synthetic resin foam can be easily and safely obtained, and have been completed.

[0009]

SUMMARY OF THE INVENTION Under the above-mentioned background, the present invention has sufficient mechanical strength such as rigidity,
It is an object of the present invention to provide a method for producing a synthetic resin foam molded article which can easily obtain a uniformly foamed synthetic resin foam molded article without problems of toxicity and safety.

[0010]

According to the first object of the present invention, water (component A), alcohol having 2 or less carbon atoms (component B) and boiling point of 50 or less are added to a thermoplastic resin molded article. Contacting a mixed solution of three components with an organic solvent (component C) at a temperature of from 150 ° C. to 150 ° C. under normal temperature and normal pressure to swell the same; and one or more of the thermoplastic resin molded products swelled in the above process Laminated, the heat deformation temperature or higher,
After heating and pressurizing to a temperature equal to or lower than the melting point, a method for producing a synthetic resin foam molded article comprising a step of foaming the thermoplastic resin molded article while gradually reducing the pressure.

In a second aspect of the present invention, a thermoplastic resin molded article is prepared by adding water (component A), an alcohol having 2 or less carbon atoms (component B) and an organic solvent having a boiling point of 50 ° C. to 150 ° C. C) contacting a mixed solution comprising the three components under normal temperature and normal pressure to swell the mixture; and bonding the thermoplastic resin molded body swelled in the above step and another non-swelled molded body to an adhesive layer. Laminating with or without intermediary, heating and pressing to a temperature equal to or higher than the heat distortion temperature and equal to or lower than the melting point, and then foaming the thermoplastic resin molded body while gradually reducing the pressure. The gist is a method for manufacturing a molded body.

The thermoplastic resin molded article used in the present invention includes, for example, polyvinyl chloride, polypropylene, polystyrene, polycarbonate, polyetherimide,
The molded article is made of a thermoplastic resin selected from one or a mixture of two or more of polyamide, polymethyl methacrylate, polyether sulfone, polyether ether ketone, ABS, polyethylene terephthalate, and polybutylene terephthalate.

As the molding method of the thermoplastic resin molded article, a conventionally known molding method can be adopted, and for example, an extrusion molding method, a compression molding method, an injection molding method, etc. can be applied.
The thermoplastic resin molded article is molded into a form suitable for the intended form of the synthetic resin foam molded article, but is usually in the form of a sheet. In this case, if the thickness of the sheet is too thin, the handling operation is difficult, and if it is too thick, a uniform foaming state cannot be obtained. Therefore, preferably 0.05 to 1.0 mm
Degree.

In the present invention, the organic solvent used in the mixed solution for swelling the thermoplastic resin molded article has a boiling point in the range of 50 ° C. to 150 ° C. If the boiling point of the organic solvent is less than 50 ° C., the organic solvent does not volatilize unnecessarily and does not contribute to the swelling of the thermoplastic resin molded article.
If the temperature is 50 ° C. or higher, it will remain inside the obtained synthetic resin foam molded article, which is not preferable. From such a point, the organic solvent used in the present invention is preferably selected from one or a mixture of two or more of methyl acetate, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, trichloromethane, and tetrahydrofuran. Organic solvent.

Further, the component ratio of the mixed solution used in the present invention is such that water (component A), alcohol having 2 or less carbon atoms (component B) and organic solvent having a boiling point of 50 to 150 ° C. (component C). The volume ratio is defined as component A: component B: component C = 20-60: 15-50: 15-40. In this case, the volume ratio of the organic solvent (component C) is excessively swelled when it exceeds 40, and excessive foaming occurs in the subsequent heating and pressurizing step. Care must be taken because sufficient foaming cannot be obtained. The alcohol (component B) has a function of uniformly compatibilizing water (component A) and the organic solvent (component C), and is a mixture of water (component A) and the organic solvent (component C). It is added appropriately depending on the ratio. In this case, if the volume ratio of the alcohol (component B) is less than 15, the function as a compatibilizer is not sufficient, and if it exceeds 50, the ratio of water decreases. Alcohol toxicity will increase.

In the second aspect of the present invention, another molded article laminated on at least one of the two surfaces of the swollen thermoplastic resin molded article is the same as or compatible with the thermoplastic resin molded article. It is a non-swelled, usually plate-like molded body made of a thermoplastic resin having Also,
In the laminating mode, the thermoplastic resin molded body and the other molded body are laminated with or without an adhesive layer interposed therebetween. You can also. In this case, as the swollen thermoplastic resin molded article, the one obtained in the production process in the first invention is used.

In the laminating mode according to the second aspect of the present invention, the adhesive layer between the thermoplastic resin molded article and another molded article may be such that the two molded articles are of the same quality or compatible with each other. It is unnecessary, but if not, an adhesive layer corresponding to the two molded bodies shall be interposed.

As described above, the method for producing a synthetic resin foam molded article according to the present invention comprises an organic solvent (component C) for increasing the degree of swelling of a thermoplastic resin molded article and shortening the time required to reach swelling equilibrium. Water (component A), which slows the swelling action of the solvent (component C), is non-toxic itself and minimizes the toxicity of the mixed solution, and the organic solvent (component C) and the water (component A) By adding an alcohol having a carbon number of 2 or less (component B) acting as a solubilizer, it is possible to appropriately adjust the degree of swelling of the thermoplastic resin molded article under low toxicity and to make the mixed solution a homogeneous system. As a result, the thermoplastic resin molded article can be finally foamed uniformly.

Therefore, since the mixed solution is a homogeneous system and the volume ratio of the component A and the component B showing the optimum degree of swelling to the thermoplastic resin molded article can be freely adjusted, the uniform foaming can be achieved. A molded article can be obtained in a short swelling time.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
A description will be given based on examples and along with comparative examples.

Examples 1 to 9 First, Examples 1 to 9 were carried out using 1,1-bis (4-oxyphenyl) ethane as a resin raw material of a thermoplastic resin molded article applied to the first invention of the present invention. A polycarbonate made of bisphenol was prepared, and was formed into a sheet having a thickness of 0.1 mm by extrusion molding.

Next, a mixed solution composed of the components A, B and C at a mixing ratio (% by volume) as shown in Table 1 was placed in separate containers, and prepared as shown in Table 1 for each embodiment. In accordance with the above, 30c
Two types of sheets cut to a size of mx 30 cm were immersed and immersed under normal temperature and pressure until swelling reached equilibrium. The time required for the swelling to reach equilibrium is shown in Table 1 as the immersion time.

With respect to the uniformity of each of the above mixed solutions, the presence or absence of an interface similar to the oil-water interface was visually observed, and those having no interface were evaluated as good (良), and those having an interface were evaluated as poor (×). As a result of the evaluation, the interface was not good for any of Examples 1 to 9 and was good (○).

The sheets immersed in the mixed solution as described above had swelling rates (% by weight) as shown in Table 1. The swelling ratio is a value obtained by dividing the weight increase of the sheet when the swelling reaches equilibrium by the weight of the original sheet in 100%.

Next, seven sheets of each swollen sheet obtained as described above were prepared and stacked for each of the examples.
It is pressed for 15 to 20 seconds by hot pressing under heating and pressing conditions of 40 ° C. and pressure of 12 MPa, and then cooling while gradually releasing the gap between the upper and lower hot plates of the hot press to 10 mm at a speed of 1 to 1.5 mm / sec. Then, a laminated synthetic resin foam molded article having a thickness of 10 mm was obtained.

The synthetic resin foam molded article obtained above was subjected to a finger pressure test on the foamed state, and the state of occurrence of a dent when pressed with a finger was observed. The result of evaluation of a sample in which remained or collapsed was evaluated as poor (×) was as shown in Table 1, and all of Examples 1 to 9 were evaluated as good (○).

[0027]

[Table 1]

Comparative Examples 1 to 12 As a thermoplastic resin molded article, a sheet cut from a 0.1 mm thick sheet made of the same polycarbonate as used in Examples 1 to 9 above was used. Prepared a mixed solution having the mixing ratio shown in Table 2, using the same organic solvent as the component used in the above example,
Thereafter, the sheet was swollen in the same manner as in the example to obtain a laminated synthetic resin foam molded article for comparison.

The synthetic resin foam molded article obtained above was evaluated by performing a finger pressure test in the same manner as in the example. As shown in Table 2, Comparative Examples 2, 4, 6, 7, 9, 10 Was good (○), and Comparative Examples 1, 3, 5, 8, 11, and 12 were poor (x). However, in Comparative Examples 2, 4, 6, and 10, the swelling time was long and exceeded 120 minutes.
For swellings 7 and 9, the swelling ratio is less than 10% by weight and the thickness is 5%.
It was as thin as ~ 7 mm.

[0030]

[Table 2]

As is apparent from Tables 1 and 2, those having a swelling ratio exceeding 20% by weight, that is, all of Comparative Examples 1, 3, 5, 8, 11, and 12 were defective in the foamed state ( X). The swelling ratio is 10% by weight.
For Comparative Examples 6, 7, 9 of less than 5 to 7 mm in thickness
It became thin. From these results, it is understood that the swelling ratio of the thermoplastic resin molded article is suitably in the range of 10% by weight to 20% by weight for the synthetic resin foam molded article to be obtained. In Comparative Examples 5 and 12, the evaluation of the uniformity of the mixed solution was poor (x), and at the same time, the foaming state was also poor (x).

[0032]

As described above, according to the method for producing a synthetic resin foam molded article of the present invention, water (component A), alcohol having 2 or less carbon atoms (component B) and boiling point of 5
Contacting a mixed solution consisting of three components with an organic solvent (component C) at 0 ° C. to 150 ° C. under normal temperature and normal pressure to swell the thermoplastic resin molded article swelled in the step; Heating and pressurizing to a temperature not lower than the heat deformation temperature but not higher than the melting point, and then foaming the thermoplastic resin molded article while gradually reducing the pressure. There is an effect that a synthetic resin foam molded article having sufficient mechanical strength can be easily and safely obtained.

Further, in the method for producing a synthetic resin foam molded article according to the present invention, the swollen thermoplastic resin molded article and the other unswelled molded article may be interposed with or without an adhesive layer. Since the layers can be laminated and heated and pressed to form a synthetic resin foam molded article, there is an advantage that a synthetic resin foam molded article having a varied laminated structure can be easily obtained at low cost.

[Procedure amendment]

[Submission date] April 21, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

[0019] Thus, a mixed solution homogeneous system, since the volume ratio of component A and component B for the thermoplastic resin molded article showing the optimal swelling degree can be freely adjusted, uniform foam A molded article can be obtained in a short swelling time.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

Examples 1 to 9 First, Examples 1 to 8 were prepared using 1,1-bis (4-oxyphenyl) ethane as a resin raw material of a thermoplastic resin molded article applied to the first invention of the present invention. Polycarbonate consisting of bisphenol and , in Example 9, polyamide
Prepared polycapramide (nylon 6)
By these extrusion how both the thickness of 0.1mm
Into a sheet.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

The above-mentioned Example 1 is used as a thermoplastic resin molded article.
A sheet cut from a sheet having a thickness of 0.1 mm made of the same polycarbonate as that used in Examples 8 to 8 was applied, and as a mixed solution, the same organic solvent as used in the above Examples was used as a component and shown in Table 2. A mixed solution having a mixing ratio was prepared, and thereafter, the sheet was swollen in the same manner as in the example to obtain a laminated synthetic resin foam molded article for comparison.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazuhisa Sakayama 1-13-5 Yachiyo, Utsunomiya, Tochigi

Claims (9)

[Claims] 1. A thermoplastic resin molded article is prepared by adding water (component A), an alcohol having 2 or less carbon atoms (component B) and a boiling point of 50.degree.
Contacting a mixed solution of three components with an organic solvent (component C) at 150 ° C. at normal temperature and pressure to swell the same; and laminating one or more of the thermoplastic resin molded products swelled in the above process Heating and pressurizing to a temperature not lower than the heat deformation temperature and not higher than the melting point, and then, while gradually reducing the pressure, foaming the thermoplastic resin molded article. 2. The organic solvent is methyl acetate, ethyl acetate,
The method for producing a synthetic resin foam molded article according to claim 1, wherein the organic resin is an organic solvent selected from one or a mixture of two or more of butyl acetate, acetone, methyl ethyl ketone, trichloromethane, and tetrahydrofuran. 3. The volume ratio of each component of the mixed solution is as follows: Component A: Component B: Component C = 20 to 60:15 to 50:15
The method for producing a synthetic resin foam molded article according to claim 1, wherein the number is 40. 4. The thermoplastic resin molded article is made of polyvinyl chloride, polypropylene, polystyrene, polycarbonate, polyetherimide, polyamide, polymethyl methacrylate, polyether sulfone, polyether ether ketone, ABS, polyethylene terephthalate, or polybutylene terephthalate. Any one or two of
The method for producing a synthetic resin foam molded article according to any one of claims 1 to 3, comprising a thermoplastic resin selected from a mixture of at least one kind. 5. A thermoplastic resin molded article comprising water (component A) and an alcohol having 2 or less carbon atoms (component B) having a boiling point of 50 ° C. or less.
A step of contacting a mixed solution comprising three components with an organic solvent (component C) at 150 ° C. under normal temperature and normal pressure to swell the mixed solution; and a step of not swelling the thermoplastic resin molded body swollen in the step. Is laminated with or without an adhesive layer, and after being heated and pressurized to a temperature not lower than its thermal deformation temperature and not higher than its melting point, the thermoplastic resin molded article is foamed while gradually reducing the pressure. And a method for producing a synthetic resin foam molded article. 6. The organic solvent is methyl acetate, ethyl acetate,
The method for producing a synthetic resin foam molded article according to claim 5, which is an organic solvent selected from one or a mixture of two or more of butyl acetate, acetone, methyl ethyl ketone, trichloromethane, and tetrahydrofuran. 7. The volume ratio of each component of the mixed solution is as follows: Component A: Component B: Component C = 20-60: 15-50: 15
The method for producing a synthetic resin foam molded article according to claim 5, wherein the number is 40. 8. The thermoplastic resin molded article is made of polyvinyl chloride, polypropylene, polystyrene, polycarbonate, polyether imide, polyamide, polymethyl methacrylate, polyether sulfone, polyether ether ketone, ABS, polyethylene terephthalate, polybutylene terephthalate. Any one or two of
The method for producing a synthetic resin foam molded article according to any one of claims 5 to 7, comprising a thermoplastic resin selected from a mixture of at least one kind. 9. The method according to claim 5, wherein the swollen thermoplastic resin molded article and another molded article are alternately laminated with a plurality of layers with or without an adhesive layer. A method for producing a synthetic resin foam molded article.