JPH0543639A - Degradable foam - Google Patents

Abstract

PURPOSE:To provide a degradable foam which is excellent in cushioning and thermally insulating properties and does not pollute the natural environment since it degrades and does not accumulate in the environment by preparing the foam from a specific degradable poyacetal-contg. resin. CONSTITUTION:A degradable foam is prepd. from a degradable polyacetal-contg. resin (e.g. a polymer of the formula) which decreases its own wt. when brought into contact with water in the natural environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam made of a degradable polyacetal-containing resin. More specifically, the present invention relates to a foam comprising a degradable polyacetal-containing resin, which has excellent properties as a foam and is easily decomposed in a natural environment.

[0002]

2. Description of the Related Art In recent years, various resins have been used as foams for applications such as cushioning materials and heat insulating materials. Polyethylene, polystyrene, polyurethane, etc. have been conventionally used as the material for these foams, because of the lightness, impact resistance, and easy processability of these foams. Moreover, due to its high stability, it can withstand long-term use even when left in a natural environment.

[0003]

Foams used as cushioning materials, heat insulating materials, etc. are partially incinerated after use, but most of them are landfilled or left as they are. is there. Conventional foam materials are very stable in the natural environment, for example, when left in the soil, they remain unchanged for many years without change. This has become a major problem in recent years as awareness of environmental conservation has increased.

In such a situation, the present invention provides a cushioning material,
It is an object of the present invention to provide a foam having excellent properties as a foam that can be used in applications such as a heat insulating material and easily decomposed in a natural environment.

[0005]

As a result of intensive studies, the present inventors have found that a foam made of a degradable polyacetal-containing resin can achieve this object, and complete the present invention based on this finding. Came to.

That is, the present invention is a decomposable foam comprising a degradable polyacetal-containing resin, the self-weight of which is reduced by being exposed to a natural environment in which it can come into contact with water.

More specifically, according to the present invention, the total contact time with water is 12 by being exposed to a natural environment in which water is continuously or intermittently contacted in a temperature range of -10 ° C to 50 ° C.
The present invention relates to a degradable foam made of a degradable polyacetal-containing resin, characterized in that its own weight is reduced by 5% or more within a month.

The present invention will be described in detail below.

In the present invention, the natural environment which continuously or intermittently comes into contact with water in the temperature range of -10 ° C to 50 ° C means the atmosphere, the soil surface such as fields, forests or landfills, the soil, the ocean, It is in water such as rivers and lakes, or in sediment such as soil under water. Regarding contact with water, it goes without saying that water directly contacts the foam,
It also includes intermittent contact of water vapor in the atmosphere or soil by repeated condensation and evaporation.

The degradability in the present invention means that the weight of the resin forming the foam is 5 when the contact time with water is 12 months or less due to the exposure to the natural environment.
% Or more. To reduce the weight in this case,
Not only the weight loss due to the elution of a part of the resin into the natural environment is included, but also the weight reduction due to the chemical change due to the action of microorganisms, bacteria and the like existing in the natural environment is included. Furthermore, the weight loss due to self-disintegrating decomposition is also included.

In the present invention, the temperature range is -10 ° C to 5 ° C.
A degradable polyacetal-containing resin that reduces its own weight by 5% or more within 12 months of the total contact time with water by being exposed to a natural environment that continuously or intermittently contacts water at 0 ° C , A copolymer of polyacetal as a main component, a copolymer of the polyacetal with another comonomer, a mixture thereof, or a mixture of these with another polymer or copolymer. For example, (A) an ABA block copolymer having a structure represented by the formula (1) with polyacetal, wherein the polyacetal copolymer has a number average molecular weight of 10,000 to 50,000.
Polyacetal block copolymers between 0.

-[(A) n- (b) l- (c) m] p- (1) (In the formula, a, b and c are the same or different and -CO-R _{1-
CO -, - O-R 2} -O -, - selected from CO-R ₃ the group consisting of -O-. R ₁ , R ₂ and R ₃ are the same or different and are unsubstituted or have at least 1 to 2 carbon atoms, or at least 1
It is a linear methylene chain in which each hydrogen atom is substituted with a group selected from an alkyl group, a cycloalkyl group, an aryl group, or a halogen element. n, l, m is 0-5
000 and not 0 at the same time. p is 1 to 5000. ) (II) selected from the group consisting of a polyacetal, a polyamide represented by the formula (2) or (3), a polyester represented by the formula (4) or (5), and a hydrocarbon represented by the formula (6). A block copolymer of A-B, wherein the polyacetal block copolymer has a number average molecular weight of 10,000 to 500,000.

[0013] _{- (NH-R 1 -CO)} a- (2) - (NH-R 2 -NH-CO-R 3 -CO) b (3) ( wherein R _1, R _2, R ₃ is an alkylene Represents a group or a substituted alkylene group, provided that hydrogen of the substituted alkylene group is substituted with an ester group or an amide group, a, b >
_{1) - (CO-R 4} -O) c- (4) - (CO-R 5 -CO-O-R 6 -O) d- (5) ( wherein R _4, R _5, R ₆ is an alkylene .c represents a group or a substituted alkylene group, d> 1) - (CH 2) .40 e-R 7 (6) ( wherein R ₇ represents hydrogen, an amido group, an ester group, or an alkoxy group>e> 1 ) (III) oxymethylene units - (CH ₂ O) - a linear polymer made of repeating, at least one of the end groups hydroxyl group consists of an ester group an alkoxy group, and the polymer terminus of Having a hydroxyl group ratio of 0.2 to 2.5 mol% or less based on all terminal groups and an alkoxy group ratio of 50 mol% or less based on all terminal groups having a number average molecular weight of 10,000 to 500,000.
Polyacetal.

(IV) A main chain consisting of a segment derived from a monosaccharide or a polysaccharide having an active hydrogen-containing functional group or both and a graft chain consisting of a polyoxymethylene segment, and having a viscosity number of 0.1 to 10 dl /
g, a thermoplastic graft copolymer having a melting point of 150 to 175 ° C.

(V) Polyacetal resin and water absorption of 10
In the case of less than (g / g), 10 ⁴ (dyn
/ Cm ² ) or more, and when the water absorption amount is saturated, a polyacetal composed of at least one water-absorbing substance having a storage elastic modulus of less than 10 ⁴ (dyn / cm ² ). A composition etc. are mentioned.

The method for producing these degradable polyacetal-containing resins will be described below. The polyacetal block copolymer of the above (I) has a structure represented by the above formula (1), and has hydroxyl groups at both ends of the compound,
It can be obtained by homopolymerizing formaldehyde or trioxane or copolymerizing formaldehyde or trioxane with a cyclic ether using a compound having any of a carboxyl group, an ester group and an alkoxy group as a molecular weight modifier.

The polyacetal block copolymer (II) is a polyamide represented by the above formula (2) or (3), a polyester represented by the above formula (4) or (5), or the above formula ( A hydrocarbon represented by 6), which has a hydroxy group, a carboxyl group or an amino group at one end of the compound as a molecular weight modifier, is homopolymerized with formaldehyde or trioxane, or has the above-mentioned molecular weight. It can be obtained by copolymerizing formaldehyde or trioxane with a cyclic ether using a regulator.

The polyacetal of (III) can be obtained, for example, by homopolymerizing substantially anhydrous formaldehyde in the presence of an anionic polymerization catalyst using a mixture of an acid anhydride and water as a molecular weight modifier. In this case, it is necessary that the ratio of the acid anhydride and water with respect to the formaldehyde is within the above range of the terminal group composition.

The thermoplastic graft copolymer (IV) can be obtained by polymerizing formaldehyde using an anionic polymerization catalyst in the presence of a monosaccharide and / or a polysaccharide having an active hydrogen-containing functional group.

The polyacetal composition (V) is based on 100 parts by weight of a powder or granular polyacetal polymer,
It is obtained by mixing powdery or granular water-absorbing substances in the range of 1 to 200 parts by weight and homogenizing using a melting device.

In producing the foam made of the degradable polyacetal-containing resin in the present invention, a usual volatile organic foaming agent is used. For example, there are hydrocarbons and halogenated hydrocarbons. Specific examples of the hydrocarbons are propane, butane, pentane, pentene, hexane and the like, and specific examples of the halogenated hydrocarbons are methyl chloride and dichloromethane. , Trichloromonofluoroethane, dichlorodifluoromethane, monochlorotrifluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, monochloropentafluoroethane and the like. The mixing ratio of these volatile organic foaming agents is preferably in the range of 5 to 150 parts by weight, more preferably 10 to 100 parts by weight, per 100 parts by weight of the foam material. If this ratio is less than 5 parts by weight, it is difficult to obtain a high foam, and if it exceeds 150 parts by weight, the effect of increasing the cross-sectional area of the foam becomes small.

In the foam made of the degradable polyacetal-containing resin of the present invention, various resin additives can be added to the resin in advance, if necessary. Examples of these resin additives include plasticizers, lubricants, antioxidants, antistatic agents, light stabilizers, heat stabilizers, ultraviolet absorbers, pigments and the like.

When a volatile organic foaming agent and, if necessary, a resin additive are added to the material of the foam of the present invention, any method commonly used for preparing a uniform mixture can be used. The master-badge method and the dry blending method are particularly preferable. However, when the volatile organic foaming agent is mixed, a method of mixing in the extrusion foaming step is usually used.
The foam made of the degradable polyacetal-containing resin in the present invention can be produced by using a usual foaming technique. For example, a method is generally used in which a material to be a foam is prepared under high temperature and high pressure and then opened to a low temperature and low pressure range to form a foam. As a molding method at this time, for example,
The extrusion foaming method, the in-mold foaming method, the press foaming method, the injection foaming method and the like can be applied.

In this way, extruded foam moldings of various shapes, such as sheets, boards, rods, tubes, pipes and nets, can be manufactured.

[0025]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.

The foaming method, measurement items and degradability test method used in the examples are as follows.

(1) Foaming method: A first extruder having a foaming agent injection port in the cylinder (diameter 30 mmφ, L / D = 30) and a second extruder having a cooling oil jacket in the cylinder (diameter 40 mmφ) , L / D = 30) were connected in series to each other, and each resin of Examples 1 to 12 was fed to the first extruder heated to a maximum temperature of 200 ° C. at a feed rate of 4 kg / hr. Powder or pellets) was supplied, and a predetermined foaming agent was injected into the zone where the powder was melt-kneaded. As the foaming agent, a mixture of dichlorotetrafluoroethane and trichlorotrifluoroethane in an equimolar ratio is used,
A high-pressure pump continuously supplied 30 parts by weight to 100 parts by weight of each resin. The mixture obtained here is supplied to a second extruder through a connecting pipe, where it is gradually cooled to a foaming optimum temperature, and then extruded from a rod die having a diameter of 3 mmφ attached to the tip of the second extruder to foam. Got the body

(2) Measurement items-Expansion ratio: ・ Cross-sectional area coefficient: (3) Degradability test method: 3 layers below the surface layer in the mulch (average ripe mulch made by JT Agris Co., Ltd.) with an average temperature of 15 ℃
The foam (2 cm square cubic foam) was embedded at 0 cm, and the time until the weight of the foam decreased by 5% was determined.

Examples 1 and 2 Sufficiently dehydrated paraformaldehyde was pyrolyzed at 150 ° C and passed through a cooling trap several times to obtain a purity of 9
Formaldehyde gas of 9.9% was obtained. 3 per hour
Formaldehyde gas of 00gr, 1.00 × 10 ~ ⁴
mol / l tetrabutylammonium acetate,
It was introduced into 1,000 gr of toluene containing 4.80 × 10 ³ to ³ mol / l of the molecular weight regulator shown in Table 1. 1.0 × 10 to ⁴ mol / at the same time as the supply of formaldehyde
l Tetrabutylammonium acetate, 4.80x
Toluene containing 10 to ³ mol / l of PCL-50 was continuously fed at a rate of 1,000 gr per hour for 4 hours. Formaldehyde was also continuously fed at a rate of 300 gr per hour, during which the polymerization temperature was maintained at 60 ° C.
Toluene containing a polymer was continuously extracted in accordance with the supply amount, and the polymer was separated by filtration. The polymer was thoroughly washed with acetone and vacuum dried at 60 ° C to obtain the polymer shown in Table 2.

Foams were prepared from these polymers, and the expansion ratio and cross-sectional area coefficient were measured and the decomposability test was conducted by the methods described above. The results are shown in Table 6.

Examples 3 and 4 Into a kneader having two Σ type stirring blades, 500 gr of sufficiently purified trioxane, 10 gr of ethylene oxide and 300 gr of a molecular weight modifier shown in Table 1 were charged, and the mixture was heated to 70 ° C.
Heated to. Then, 0.25 gr of boron trifluoride dibutyl etherate was added to this kneader and heated for 35 minutes.
Immediately thereafter, 10 gr of tributylamine was added to stop the polymerization. The contents were taken out from the kneader and washed with acetone to obtain the polyacetal copolymer shown in Table 2.

Foams were produced from these polymers, and the expansion ratio and the cross-sectional area coefficient were measured and the decomposability test was conducted by the methods described above. The results are shown in Table 6.

Examples 5 and 6 300 gr of formaldehyde gas was added per hour.
It was introduced into 1000 gr of toluene containing 00 × 10 to ⁴ mol / l of tetrabutylammonium acetate and 4.80 × 10 to ³ mol / l of the molecular weight regulator shown in Table 1.

1.0 × simultaneously with the supply of formaldehyde
Toluene containing 10 to ⁴ mol / l of tetrabutylammonium acetate and 4.80 × 10 to ³ mol / l of a molecular weight modifier was continuously supplied at a rate of 1000 gr for 4 hours. Formaldehyde is 30 per hour
It was fed at a rate of 0 gr, while maintaining the polymerization temperature at 60 ° C. Toluene containing a polymer was continuously extracted in accordance with the supply amount, and the polymer was separated by filtration. The polymer was thoroughly washed with acetone and vacuum dried at 60 ° C to obtain the polymer shown in Table 2.

A foam was produced using this polymer, and the expansion ratio and cross-sectional area coefficient were measured and the decomposability test was conducted by the methods described above. The results are shown in Table 6.

Example 7 300 gr of formaldehyde gas per hour, 1.0 × 10 to ⁴ mol / l of tetrabutylammonium acetate as a polymerization catalyst, and 5.69 × 10 to ³ mol / l of acetic anhydride as a molecular weight modifier. And water 5.75 × 10 ~ ⁵ mo
It was introduced into 2 liters of toluene containing 1 / l. 1.0 × 10 ~ ⁴ mol at the same time as the supply of formaldehyde
/ L tetrabutylammonium acetate, 5.69
X10 ~ ³ mol / l acetic anhydride and 5.75x10 ~ ⁵ mo
Toluene containing 1 / l of water was fed continuously at a rate of 2 liters per hour for 4 hours. Formaldehyde gas was also continuously supplied at a rate of 300 gr per hour, during which the polymerization temperature was maintained at 60 ° C. Toluene containing the polymer was continuously withdrawn in accordance with the supply amount, and the polymer was separated by filtration. The polymer was thoroughly dried with acetone to obtain a polymer in Table 3.

A foam was produced using this polymer, and the expansion ratio and cross-sectional area coefficient were measured and the decomposability test was carried out by the methods described above. The results are shown in Table 6.

Example 8 Polyacetals shown in Table 3 were produced in the same manner as in Example 7 except that 2.4 × 10 to ⁵ mol / l of methanol was used in addition to acetic anhydride and water as molecular weight regulators. ,
A foam was produced. Table 6 shows the results of the measurement of the expansion ratio and the cross-sectional area coefficient and the decomposability test.

Examples 9 and 10 The sugars 100 shown in Table 4 were added to 10 liters of cyclohexane.
After suspending 0 g, anhydrous formaldehyde gas at 2000 g / hr and the polymerization catalyst shown in Table 4 were introduced into this suspension over 2 hours. During this period, the polymerization temperature is 50
It was maintained at ° C.

Next, the produced polymer was separated from cyclohexane, thoroughly washed with acetone and vacuum dried at 60 ° C. to obtain a polymer.

Foams were prepared using these polymers,
The expansion ratio and the cross-sectional area coefficient were measured and the decomposability test was performed by the methods described above. The results are shown in Table 6.

Examples 11 and 12 20 parts by weight of the water-absorbing polymer shown in Table 5 was added to 100 parts by weight of the end-stabilized polyacetal homopolymer having a number average molecular weight of 35,000, and the composition was prepared using a 30 mmφ extruder. The thing was prepared.

Foams were prepared using these compositions,
The expansion ratio and the cross-sectional area coefficient were measured and the decomposability test was performed by the methods described above. The results are shown in Table 6.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

[0049]

[Table 6]

[0050]

The foam made of the degradable polyacetal-containing resin in the present invention is a high foam having a foaming ratio of about 50 times and has excellent cushioning and heat insulating properties. It can be used for applications such as wood. Moreover, it also has degradability in the environment, which is not found in conventional foams. Therefore, even if it is left in the natural environment, it disappears within a short period of time, so that it does not pollute the environment due to accumulation in the environment.

Claims (1)

[Claims] 1. A decomposable foam comprising a degradable polyacetal-containing resin, the self-weight of which decreases when exposed to a natural environment in which it can come into contact with water.