Method for manufacturing foam

Abstract

To enable the production of a foam that can biodegrade back into the soil, by utilizing polybutylene succinate as the substrate and subjecting it to block foaming.SOLUTION: A method for producing a foam includes the steps for loading a crosslinkable foamable composition, in which a crosslinker and 3-15 pts.wt. of sodium bicarbonate as a foamer are added to 50-100 pts.wt. of polybutylene succinate as a substrate, into a closed vessel, followed by pressurized heating and subsequent decompression.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a foam using polybutylene succinate as the main raw material. [Background technology]

[0002] Recently, there has been a growing interest in manufacturing foams using biodegradable resins, with environmental considerations in mind. Because biodegradable resins decompose even when released into the natural environment, their use is expanding as a solution to environmental pollution caused by microplastics.

[0003] Here, polybutylene succinate can be cited as an example of a biodegradable resin used as a base material in the manufacture of foams (see, for example, Patent Document 1). Polybutylene succinate has the advantage of being biodegradable in soil. When manufacturing foams using polybutylene succinate, it is often mixed with other biodegradable resins such as polylactic acid. However, since polylactic acid does not decompose in soil, attempts have been made to manufacture foams using polybutylene succinate alone or mixed with other biodegradable resins that can be decomposed in soil as the main raw material.

[0004] However, when attempting to manufacture foams by block foaming, which involves filling a foaming composition of polybutylene succinate into a sealed container and allowing it to foam, a problem arises: the resin deteriorates, and the foam cannot maintain its shape. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-163614 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above, and aims to enable the production of a soil-degradable foam by using polybutylene succinate as a base material and by block foaming polybutylene succinate. [Means for solving the problem]

[0007] The method for producing a foam according to claim 1 includes the steps of filling a sealed container with a crosslinkable foaming composition prepared by adding a crosslinking agent and 3 to 15 parts by weight of sodium bicarbonate, which is a foaming agent, to 50 to 100 parts by weight of polybutylene succinate, which is a base material, heating it under pressure, and then releasing the pressure.

[0008] This manufacturing method allows for the production of a soil-degradable foam by block foaming, using sodium bicarbonate as the foaming agent instead of ADCA, which has been widely used as a foaming agent in the past.

[0009] As one effective embodiment of such a foam manufacturing method, the method for manufacturing a foam according to claim 1 includes a step of adding 5 to 100 parts by weight of a filler.

[0010] Another effective embodiment of such a foam manufacturing method is the foam manufacturing method according to claim 1 or 2, comprising 5 to 50 parts by weight of polybutylene adivate or PLA as a base material in addition to polybutylene succinate. [Effects of the Invention]

[0011] According to the present invention, by using polybutylene succinate as a base material and adding 3 to 15 parts by weight of sodium bicarbonate as a foaming agent, and performing block foaming, it is possible to produce a foam that can be decomposed in soil. [Brief explanation of the drawing]

[0012] [Figure 1] A graph showing the change over time in the biodegradation rate of the foam of this embodiment in soil. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below. In this embodiment, a crosslinkable foaming composition is obtained by adding sodium bicarbonate, a foaming agent, a crosslinking agent, etc., as a foaming agent to a base material, polybutylene succinate (or a mixture of polybutylene succinate and polybutylene adipate / terephthalate), and kneading the mixture. A foam is then obtained by filling the composition into a sealed container and heating it under pressure to cause foaming.

[0014] Here, the crosslinkable foaming composition comprises 50 to 100 parts by weight, preferably 80 to 100 parts by weight, of polybutylene succinate as a base material, 3 to 15 parts by weight, preferably 6 to 15 parts by weight, of sodium bicarbonate as a foaming agent, and at least a crosslinking agent.

[0015] The crosslinking agent is an organic peroxide that, in polybutylene succinate (or a mixture of polybutylene succinate and polybutylene adipate / terephthalate), has a decomposition temperature at least equal to the flow initiation temperature of polybutylene succinate, and is a radical generating agent that decomposes upon heating, generating free radicals that cause crosslinking bonds between molecules or within molecules. Specific examples include dicumyl peroxide, n-butyl 4,4-bis(t-butylperoxy)valerate, 1,1-ditteretherlybutyl peroxide, 1,1-ditteretherlybutylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-ditteretherlybutylperoxyhexane, 2,5-dimethyl-2,5-ditteretherlybutylperoxyhexine, α,α-ditteretherlybutylperoxyisopropylbenzene, tert-butyl peroxyketone, tert-butyl peroxybenzoate, and the like. However, it is necessary to select the optimal organic peroxide depending on the raw material resin.

[0016] In addition, for the purpose of improving the physical properties or reducing the price of the crosslinkable foaming composition, additives (filler) that do not significantly affect crosslinking, such as metal oxides such as zinc oxide, titanium oxide, calcium oxide, magnesium oxide, silicon oxide, etc., carbonates such as magnesium carbonate, calcium carbonate, various dyes, pigments, starch (corn starch), fluorescent substances, and other commonly used rubber and plastic additives can be added as needed. Furthermore, lubricants such as stearic acid, modifiers such as carbodiimide, etc. can also be added as needed.

[0017] The procedure for manufacturing the foam in this embodiment is basically the same as that in the manufacture of existing foams. That is, after adding a foaming agent, a crosslinking agent, etc. to the polyolefin resin as the base material and kneading, this is heated and foamed to obtain a foam. In Examples 2 and 5 of this embodiment, a step of causing the kneaded material to undergo the first-stage foaming, a primary extraction step of taking out the intermediate after the first-stage foaming, a step of causing the intermediate to undergo the second-stage foaming, and a secondary extraction step of taking out the foam after the second-stage foaming are performed.

[0018] Tables 1 and 2 show specific examples of this embodiment. Needless to say, the present invention is not limited to the following examples. Also, Table 2 shows comparative examples of this embodiment. In Tables 1 and 2, the numbers are the weight ratios of the respective components when the total amount of polybutylene succinate (or a mixture of polybutylene succinate and polybutylene adipate terephthalate) as the main raw material is 100 parts by weight.

[0019]

Table 1

[0020]

Table 2

[0021] <Example 1> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 9 parts by weight of sodium bicarbonate (baking soda, foaming agent), and 0.7 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded, and the kneaded mixture was heated under pressure at 160°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 103 kg / m³ 3 That's what happened.

[0022] <Example 2> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 9 parts by weight of sodium bicarbonate (baking soda, foaming agent), and 0.7 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded. The kneaded mixture was heated under pressure at 150°C for 50 minutes, and then further heated under pressure at 160°C for 30 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 88 kg / m³ 3 That's what happened.

[0023] <Example 3> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 9 parts by weight of sodium bicarbonate (baking soda, foaming agent), 0.7 parts by weight of dicumyl peroxide (DCP, crosslinking agent), and 30 parts by weight of corn starch (starch, filler) was kneaded, and the kneaded mixture was heated under pressure at 160°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 108 kg / m³ 3 That's what happened.

[0024] <Example 4> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 6 parts by weight of sodium bicarbonate (baking soda, foaming agent), and 0.6 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded, and the kneaded mixture was heated under pressure at 150°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 140 kg / m³ 3 That's what happened.

[0025] <Example 5> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 12 parts by weight of sodium bicarbonate (baking soda, foaming agent), and 0.6 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded. The kneaded mixture was heated under pressure at 160°C for 50 minutes, and then heated again under pressure at 160°C for 30 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 57.4 kg / m³. 3 That's what happened.

[0026] <Example 6> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 12 parts by weight of sodium bicarbonate (baking soda, foaming agent), 0.6 parts by weight of dicumyl peroxide (DCP, crosslinking agent), and 50 parts by weight of calcium carbonate (filler) was kneaded, and the kneaded mixture was heated under pressure at 160°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 110 kg / m³ 3 That's what happened.

[0027] <Example 7> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 12 parts by weight of sodium bicarbonate (baking soda, foaming agent), 0.3 parts by weight of dicumyl peroxide (DCP, crosslinking agent), and 2 parts by weight of carbodilite (modifier) ​​was kneaded, and the kneaded mixture was heated under pressure at 160°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 91 kg / m³ 3 That's what happened.

[0028] <Example 8>A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 15 parts by weight of sodium hydrogen carbonate (sodium bicarbonate, foaming agent), 1.2 parts by weight of Perhexyne 25B-40 (crosslinking agent), and 50 parts by weight of corn starch (starch, filler) was kneaded, and the kneaded product was heated under pressure at 160 °C for 50 minutes to decompose and foam the foaming agent and the crosslinking agent. The apparent density of the resulting foam was 105 kg / m 3 It became.

[0029] <Example 9>A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 12 parts by weight of sodium hydrogen carbonate (sodium bicarbonate, foaming agent), 1.5 parts by weight of Perhexa V-40 (crosslinking agent), and 0.7 parts by weight of stearic acid (lubricant) was kneaded, and the kneaded product was heated under pressure at 150 °C for 50 minutes to decompose and foam the foaming agent and the crosslinking agent. The apparent density of the resulting foam was 95 kg / m 3 It became.

[0030] <Example 10>A composition consisting of 80 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 20 parts by weight of polybutylene adipate terephthalate (PBAT, trade name: Ecoflex, manufactured by Basf Japan Ltd.), 12 parts by weight of sodium hydrogen carbonate (sodium bicarbonate, foaming agent), and 0.6 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded, and the kneaded product was heated under pressure at 150 °C for 50 minutes to decompose and foam the foaming agent and the crosslinking agent. The apparent density of the resulting foam was 96 kg / m 3 It became.

[0031] <Example 11> A composition consisting of 80 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 20 parts by weight of polybutylene adipate terephthalate (PBAT, trade name: Ecoflex, manufactured by Basf Japan Ltd.), 12 parts by weight of sodium bicarbonate (baking soda, foaming agent), 0.3 parts by weight of dicumyl peroxide (DCP, crosslinking agent), and 2 parts by weight of carbodilite (modifier) ​​was kneaded, and the kneaded mixture was heated under pressure at 150°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam. The apparent density of the resulting foam was 90 kg / m³ 3 That's what happened.

[0032] <Comparative Example> A composition consisting of 100 parts by weight of polybutylene succinate (PBS, trade name: FZ91B, manufactured by Mitsubishi Chemical Corporation), 1 part by weight of azodicarbonamide (ADCA, foaming agent), and 0.3 parts by weight of dicumyl peroxide (DCP, crosslinking agent) was kneaded, and the kneaded mixture was heated under pressure at 150°C for 50 minutes to decompose the foaming agent and crosslinking agent and produce foam, but the shape could not be maintained.

[0033] Furthermore, the results of a soil biodegradation test of the foam of this embodiment using polybutylene succinate (PBS) as the base material are shown below with reference to Figure 1, a graph showing the biodegradation rate against the number of test days. This test was conducted in accordance with JIS K 6955:2017. The foam of this embodiment degraded by 48.9-67.8% and an average of approximately 54% after 180 days from the start of the experiment. Although this does not reach the standard of 60% or more decomposition in 180 days that the Japan Bioplastics Association recognizes as a "biodegradable plastic," it is expected that the standard can be met by replacing some of the raw materials with cornstarch, etc.

[0034] As described above, the materials described in Examples 1 to 11, which used sodium bicarbonate (baking soda) as a foaming agent, were able to maintain their shape as foam even after the block foaming process.

[0035] In contrast, the material described in the comparative example failed to maintain its shape as a foam after the block foaming process.

[0036] As described above, the foam according to this embodiment decomposes by more than 54% in soil after 180 days, and the decomposition rate has not decreased even after 180 days. Further decomposition is expected, and it can contribute to solving environmental pollution caused by microplastics.

[0037] However, the present invention is not limited to the embodiments described above.

[0038] For example, the blending ratio of the base material, polybutylene succinate, can be arbitrarily set within the range of 50 to 100 parts by weight, preferably 80 to 100 parts by weight. The blending ratio of the foaming agent, sodium bicarbonate, can also be arbitrarily set within the range of 3 to 15 parts by weight, preferably 6 to 15 parts by weight.

[0039] In addition, as a base material, polybutylene adipate terephthalate, polybutylene adivate, or polylactic acid may be optionally blended in an amount of 5 to 50 parts by weight, in addition to polybutylene succinate.

[0040] Furthermore, various modifications are permitted as long as they do not impair the spirit of the present invention.

Claims

1. A method for producing a foam, comprising the steps of filling a crosslinkable foaming composition, which is obtained by adding a crosslinking agent and 3 to 15 parts by weight of sodium bicarbonate, a foaming agent, to 50 to 100 parts by weight of polybutylene succinate, a base material, into a sealed container, heating under pressure, and then releasing the pressure.

2. A method for producing a foam according to claim 1, comprising the step of adding 5 to 100 parts by weight of a filler.

3. A method for producing a foam according to claim 1 or 2, comprising, as a base material, 5 to 50 parts by weight of polybutylene adipate terephthalate, polybutylene adivate, or polylactic acid, in addition to polybutylene succinate.

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