Mold-release agent for plastics and method for manufacturing plastics for food container packages
Patent Information
- Application Number
- JP2022206339
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-12-23
- Publication Date
- 2025-12-15
Smart Images
Figure 2024090425000001 
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Abstract
Description
[Technical field]
[0001] The present invention relates to an aqueous silicone emulsion composition useful as a release agent for synthetic resin films or sheets (hereinafter referred to as films, etc.), and particularly to a release agent for plastics in the form of a silicone emulsion suitable for films for food packaging, etc. Furthermore, the present invention relates to a method for producing plastics for food container packaging using said release agent for plastics. [Background technology]
[0002] From the viewpoint of freshness and hygiene, foods are sold protected with plastic trays, sheets, films, etc. As packaging materials for various foods, thermoplastic resin films and sheets such as polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) are widely used because of their excellent formability and water resistance. Resin films, etc. are wound into rolls during the manufacturing process, and when used as packaging materials for food, the rolled films, etc. are unwound to form cups or bags. However, if a release agent is not used, the surfaces of the resin films, etc. adhere to each other, making unwrapping difficult, and there are problems such as deformation or tearing of the films, etc. when peeling them off. In addition, when molding containers, problems such as adhesion to the mold and reduced ease of removal occur, and when punching out a large number of sheets, there are problems such as adhesion between the products. Furthermore, molded products such as cases, trays, and cups made from sheets and films are stored in layers, and if a release agent is not applied to them, there is a problem of blocking.
[0003] As a means for solving these problems, the application of silicone release agents, particularly organopolysiloxane emulsions, is widely used from the viewpoints of workability and safety. From the viewpoints of releasability and slipperiness, an organopolysiloxane emulsion composition having a kinetic viscosity of 100 to 100,000 mm2 / s at 25°C is suitable as a release agent for synthetic resins used in food container packaging (for example, Patent Document 1).
[0004] When the organopolysiloxane emulsion composition is applied to plastics as a release agent, it is diluted with water to a concentration of 0.1 to 5.0 mass % of the organopolysiloxane, and applied by rotary dampening, gravure or spraying.
[0005] In coating methods involving strong agitation such as rotary dampening, the emulsion itself may be destroyed, causing gels, oil floating, etc. If the emulsion is coated on plastic in a state where gels or oil floating have occurred, uneven wetting will occur, causing problems such as adhesion between plastics and uneven appearance. In addition, if the storage stability of the emulsion is poor, oil floating will occur over time, causing uneven wetting.
[0006] In addition, when an emulsion of organopolysiloxane containing a large amount of nonionic surfactant is applied to plastic, the nonionic surfactant penetrates into the plastic, causing cracks, which can lead to problems such as cracks in the molded product. Such cracks are particularly likely to occur in plastics such as biaxially oriented polystyrene and polystyrene (PS).
[0007] Furthermore, in recent years, octamethylcyclotetrasiloxane has become a candidate for a substance of very high concern under the European REACH regulation and is therefore of concern as an environmentally hazardous substance, so there is a demand for products with reduced octamethylcyclotetrasiloxane content.
[0008] Therefore, there is a need for an organopolysiloxane emulsion type release agent which has excellent dilution stability, mechanical stability, and storage stability, has good wettability, does not cause cracks in plastics, and contains a low amount of octamethylcyclotetrasiloxane.
[0009] In Japan, the Food Sanitation Act was amended to enforce the "Positive List (PL) System for Food Utensils and Containers" on June 1, 2020, requiring that only raw materials whose safety has been confirmed be used in food utensils and containers. In addition, for coating agents used in the manufacture of plastic food utensils and containers, the Polyolefin and Other Hygienic Materials Council previously issued a confirmation certificate after confirming that the agent met the substances and restrictions listed on the positive list and passed hygiene tests. Since 2021, this has been taken over by the Food Contact Material Safety Center of the Chemical Research and Evaluation Institute. Therefore, it is recommended to use raw materials whose safety has been confirmed for container packaging applications that come into direct contact with food. For plastic release agents for food container packaging, an organopolysiloxane emulsion that is safe and can solve the above-mentioned objectives is desired.
[0010] Various methods have been investigated to solve the above problems.
[0011] Patent Document 1 proposes a silicone release agent composition that causes little whitening of the film. The composition of Patent Document 1 contains propylene glycol. In the examples, emulsion polymerization is performed using octamethylcyclotetrasiloxane as a raw material, so there is a concern that 1% or more of octamethylcyclotetrasiloxane remains. In addition, mechanical emulsification of organopolysiloxane is also performed, but polyoxyethylene lauryl ether is used alone as a nonionic emulsifier, so the average particle size does not become fine and there is a risk of poor stability. In addition, among polyoxyethylene lauryl ethers, those with polyoxyethylene chains of 1 to 6 may cause cracks in synthetic resins, especially PS and OPS, so there is a risk of cracks occurring even in the emulsion of the examples of Patent Document 1 when used as a release agent for PS or OPS.
[0012] Patent Document 2 discloses an organopolysiloxane emulsion release agent composition that has excellent wettability and good transparency. However, in the examples, sodium polyoxyethylene nonylphenyl ether sulfate is used as an anionic surfactant, which is of concern as an environmentally hazardous substance, and therefore is not recommended for use as a release agent for plastics used in food container packaging.
[0013] The dimethylpolysiloxane release agent composition described in Patent Document 3 contains 500 ppm or less of dimethylsiloxane oligomers having 20 or less silicon atoms. In the examples, a polyoxyethylene (8.5 mol addition) nonylphenyl ether emulsifier is used as the nonionic emulsifier, and a polyoxyethylene (3.5 mol addition) octylphenol sulfate sodium salt emulsifier is used as the anionic surfactant, but since this is a substance of concern as an environmental load, its use as a release agent for plastics used in food container packaging is not recommended.
[0014] Patent Document 4 relates to an emulsion with a narrow particle size distribution and excellent stability, which is obtained by blending phenoxyethanols during emulsification, but the average particle size in the examples is large, at 1 μm or more, and it is expected that the dilution stability and mechanical stability are low. In addition, phenoxyethanol is not registered on the positive list.
[0015] Patent Document 5 is an alkylaralkyl co-modified silicone emulsion release agent for aluminum die casting. Alkylaralkyl co-modified silicone has a lower release property for plastics than dimethylpolysiloxane, and is not suitable as a release agent for plastics.
[0016] Patent Document 6 discloses a silicone water-dispersed release agent composition that uses a sorbitan higher alkyl ester, which is preferably used in the vulcanization molding of acrylic rubber, in combination with other nonionic surfactants. It is said that when an anionic surfactant is added to the silicone emulsion, the emulsion has a larger negative zeta potential, and the emulsion particles are less likely to aggregate due to stronger electronic repulsion between them, improving mechanical stability. Patent Document 6 does not contain an anionic surfactant, and mechanical stability is expected to be low. In addition, the silicone oil used in the examples is a polyether-modified silicone oil, and it is expected that the release properties are insufficient.
[0017] Patent Document 7 discloses an emulsion in which organopolysiloxane is emulsified with polyoxyethylene alkyl ether having an HLB of 10 or more. As with Patent Document 6, no anionic surfactant is blended, and mechanical stability is expected to be low. In addition, there is a concern that polyoxyethylene alkyl ether having an HLB of 10 or more may cause cracks when applied to plastics.
[0018] Patent Document 8 discloses a silicone emulsion composition comprising an organopolysiloxane, a polyoxyethylene alkyl ether having an alkyl chain with 8 to 11 carbon atoms, and an anionic surfactant. However, an emulsion containing a polyoxyethylene alkyl ether having 8 to 11 carbon atoms may cause cracks when applied to plastics.
[0019] Patent Document 9 discloses a silicone emulsion composition in which organopolysiloxane is emulsified with polyoxyethylene alkyl ether and sucrose fatty acid ester. In the examples, polyoxyethylene (3) decyl ether is used as the polyoxyethylene alkyl ether, but polyoxyethylene alkyl ethers with an alkyl group having 10 or less carbon atoms may cause cracks in plastics.
[0020] Patent Document 10 discloses a silicone emulsion in which organopolysiloxane is emulsified with polyoxyethylene hexyldecyl ether or polyoxyethylene isostearyl ether. However, the average particle size in the examples is relatively large at about 400 nm, and dilution stability and mechanical stability may be poor.
[0021] Patent Document 11 discloses an emulsion in which organopolysiloxane is emulsified with an anionic surfactant and a polyhydric alcohol. In general, anionic surfactants and polyhydric alcohols have a lower function of lowering surface tension than nonionic surfactants such as polyoxyethylene alkyl ethers. The emulsion in Patent Document 11 has a high surface tension (25°C) of 45 dyne / cm or more even when diluted 50 times with water, and since it does not contain a nonionic surfactant, when applied to plastics, it has poor wettability and may cause cissing.
[0022] Patent Document 12 discloses an emulsion in which organopolysiloxane is used with polyoxyethylene alkyl ether or the like to reduce the particle size to 100 nm or less. However, since a large amount of polyoxyethylene alkyl ether is used to reduce the particle size of the emulsion to 100 nm or less, there is a risk of cracking the plastic.
[0023] In response to this, Patent Document 13 proposes an emulsion in which organopolysiloxane is used with an anionic surfactant and a polyoxyethylene sorbitan fatty acid ester to reduce the particle size from 200 nm to 350 nm. However, the anionic surfactant and the polyoxyethylene sorbitan fatty acid ester are only weakly effective in improving the stability of the organopolysiloxane emulsion, and there are concerns about the stability over time of the resulting emulsion composition, i.e., the mold release agent for plastics. [Prior art documents] [Patent documents]
[0024] [Patent Document 1] JP 2005-281409 A [Patent Document 2] Patent No. 3106079 [Patent Document 3] Special Publication No. 7-91529 [Patent Document 4] JP 2000-169705 A [Patent Document 5] Japanese Patent Application Publication No. 4-84643 [Patent Document 6] Japanese Patent Application Publication No. 8-283771 [Patent Document 7] Patent No. 3638087 [Patent Document 8] JP 2004-331784 A [Patent Document 9] JP 2004-035820 A [Patent Document 10] Patent No. 4828054 [Patent Document 11] Patent No. 3835646 [Patent Document 12] Patent No. 7142163 [Patent Document 13] Patent No. 7181915 Summary of the Invention [Problem to be solved by the invention]
[0025] The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a release agent for plastics in the form of an emulsion of organopolysiloxane which is safe, has excellent storage stability and mechanical stability in particular, causes little repellency when applied to plastics, has good wettability, is less likely to cause cracks in plastics, and has a low content of cyclic siloxane components with a low degree of polymerization, and a method for producing plastics for food container packaging using the same. [Means for solving the problem]
[0026] The present inventors have intensively studied the above-mentioned problems and arrived at the present invention. That is, the problem of the present invention is to provide a composition comprising: (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1), having a kinetic viscosity at 25°C of 100 to 100,000 mm2 / s, and containing less than 1 mass% each of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; [ka] (In the formula, R 1 may be the same or different and are either a hydroxyl group, a hydrogen atom, an unsubstituted linear alkyl group having 1 to 32 carbon atoms, or a phenyl group, and L is an integer of 60 to 1,500. (B) anionic surfactant: 0.1 to 18.0 parts by mass, (C) 0.1 to 10 parts by mass of a polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier, and (F) Water: 35~100,000 parts by mass The problem is solved by a release agent for plastics, which is characterized in that the emulsion particles have an average particle size of more than 100 nm and not more than 1000 nm as measured by a laser diffraction / scattering method.
[0027] Furthermore, in the release agent for plastics, the component (B) may be one or more anionic surfactants selected from alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl phosphates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkyl ether phosphates.
[0028] Similarly, the release agent for plastics is (D) The following general formula (2): [ka] (R 2is an alkyl group having 8 to 24 carbon atoms. a, b, and c are independently integers of 0 or more, and the sum of a+b+c is 8 to 30. Polyoxyethylene sorbitan fatty acid ester represented by the formula: 0.1 to 15.0 parts by mass; and / or (E) the following general formula (3): C m H 2m+1 (OCH2CH2) n OH (3) (m is an integer from 10 to 20, and n is an integer from 4 to 50.) Polyoxyethylene alkyl ether represented by the formula: 0.1 to 10.0 parts by mass It may further include.
[0029] In the release agent for plastics according to the present invention, the plastic is preferably a plastic for food container packaging, and particularly preferably a plastic sheet (including film) for food packaging or a molded product thereof.
[0030] The problems of the present invention are also solved by a method for producing plastics for food container packaging, which is characterized by the use of the release agent for plastics of the present invention. Effect of the Invention
[0031] The present invention makes it possible to provide a release agent for plastics which is safe enough for use in food packaging, is particularly excellent in storage stability and mechanical stability, causes little repellency when applied to plastics, has good wettability and dilution stability, is less likely to cause stress cracks in plastics, and has a low content of volatile cyclic siloxane components (such as octamethylcyclotetrasiloxane).
[0032] Furthermore, by using the release agent for plastics according to the present invention, it is possible to provide a method for producing the above-mentioned food container packaging plastics, particularly food packaging plastic sheets (including films) and molded products thereof, by demolding or molding with a mold. BEST MODE FOR CARRYING OUT THEINVENTION
[0033] The release agent for plastics according to the present invention will be described in detail below. The release agent for plastics contains the following components (A) to (C) and component (F), and may optionally contain components (D), (E) and other components within the scope of the technical effect of the present invention, and is an emulsion in which the average particle size of the emulsion particles is greater than 100 nm and not greater than 1000 nm as measured by a laser diffraction / scattering method. The emulsion is in the form of an oil-in-water organopolysiloxane emulsion in which the aqueous phase is the continuous phase.
[0034] The release agent for plastics according to the present invention, particularly when used in combination with a polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier (C) (e.g., the Pluronic (registered trademark) series from ADEKA Corporation), has the advantages of being particularly superior in storage stability and mechanical stability as well as improved wettability and crack resistance of plastics, etc., compared to known release agents for plastics.
[0035] [(A) Organopolysiloxane] (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1) and having a kinetic viscosity at 25°C of 100 to 100,000 mm2 / s: [ka]
[0036] In formula (1), R 1may be the same or different, and are any of an unsubstituted linear alkyl group having 1 to 32 carbon atoms, a phenyl group, a hydroxyl group, and a hydrogen atom. Examples of the linear unsubstituted alkyl group having 1 to 32 carbon atoms include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a n-decyl group, a n-dodecyl group, a n-tetradecyl group, a n-hexadecyl group, a n-octadecyl group, and an eicosyl group. R1 is preferably a linear unsubstituted alkyl group having 1 to 20 carbon atoms or a phenyl group, and more preferably a methyl group or a phenyl group from the viewpoint of versatility. In addition, from the viewpoint of releasability, it is preferable that 50 mol % or more of the number of R1 in one molecule is a methyl group, and more preferably 75% or more is a methyl group. In addition, L is an integer of 60 to 1,500, and preferably 150 to 1,200.
[0037] One of the features of the organopolysiloxane (A) is that it has a reduced amount of cyclic siloxane components with low polymerization degrees. Specifically, the content of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane in the component (A) is less than 1% by mass, preferably less than 0.5% by mass, and more preferably less than 0.1% by mass. Particularly preferably, the content of these cyclic siloxane components with low polymerization degrees in the component (A) is below the detection limit.
[0038] If the organopolysiloxane (A) contains a large amount of cyclic siloxane components with low polymerization degrees, particularly octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane, it may be difficult to emulsify, the average particle size may become large, or the storage stability, dilution stability, and mechanical stability may decrease, or cracks may easily occur when applied to plastics. There are also concerns about environmental issues. The amount of cyclic siloxane components with low polymerization degrees in the organopolysiloxane (A) can be reduced by stripping or using a thin-film distillation device, etc.
[0039] The kinetic viscosity of the organopolysiloxane of component (A) at 25°C is 100 to 100,000 mm2 / s. If the kinetic viscosity is lower than 100 mm2 / s, the resulting composition may not exhibit sufficient releasability. On the other hand, if the kinetic viscosity of the organopolysiloxane of component (A) is greater than 100,000 mm2 / s, when the composition is applied to a film or the like, the surface may become sticky. In addition, if the kinetic viscosity of the organopolysiloxane is greater than 100,000 mm2 / s, emulsification becomes difficult, making it difficult to obtain an emulsion with good stability. The kinetic viscosity is preferably 200 to 50,000 mm2 / s, and more preferably 300 to 15,000 mm2 / s. mm2 / s, and more preferably 500 to 5,000 mm2 / s.
[0040] The above kinematic viscosity refers to the value of the kinematic viscosity at 25°C measured by a rotational viscometer conforming to JIS K7117-1. However, when the value of the kinematic viscosity exceeds 20,000 mm2 / s, the value obtained by dividing the viscosity value at 25°C measured by the single cylinder type rotational viscometer described in the above JIS standard by the measured density at 25°C is used.
[0041] The organopolysiloxane of component (A) may be any type as long as it has a kinematic viscosity at 25° C. within the above range, and may use either a single type or a mixture of two or more types.
[0042] [(B) Anionic surfactant] Examples of the anionic surfactant of the component (B) include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, fatty acid alkylolamide sulfates, alkyl sulfonates, polyoxyethylene alkyl phenyl ether sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonates, alkanesulfonates, monoalkyl sulfosuccinates, dialkyl sulfosuccinates and other alkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, monoalkyl phosphates, dialkyl phosphates and other alkyl phosphates, polyoxyethylene alkyl ether phosphates, α-sulfofatty acid esters, N-acyltaurates, fatty acid salts, polyoxyethylene alkyl ether carboxylates, N-acyl amino acid salts, etc. Examples of salts include sodium salts, potassium salts, ammonium salts, triethanolamine salts, etc.
[0043] The amount of the anionic surfactant (B) used as an emulsifier is in the range of 0.1 to 18.0 parts by mass relative to 100 parts by mass of the organopolysiloxane (A). It is preferably in the range of 0.15 to 15.0 parts by mass, more preferably 0.2 to 12.0 parts by mass, and even more preferably 0.25 to 10.0 parts by mass. If the amount of the component (B) used is less than 0.1 parts by mass, the mechanical stability and dilution stability of the plastic release agent of the present invention may decrease. On the other hand, if the amount of the component (B) used is more than 18.0 parts by mass, the release property may decrease or the wettability to the substrate may decrease.
[0044] The anionic surfactant of the component (B) may be used alone or in combination of two or more kinds.
[0045] [(C) Polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier] The polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier, which is component (C), is one of the characteristic features of the present invention, and by using it in a specified quantitative range with the above-mentioned components (A), (B) and water (F), it forms an emulsion that is particularly excellent in storage stability and mechanical stability, and has the advantage of improving the wettability of the resulting plastic release agent and the crack resistance (= stress crack resistance) of plastics, etc. In particular, the anionic surfactant, component (B), alone has a weak emulsifying power for the organopolysiloxane, component (A), and sufficient storage stability, mechanical stability and dilution stability cannot be obtained, but by blending the polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier, component (C), in a specific quantitative range, it is possible to improve the storage stability, mechanical stability and dilution stability of the resulting plastic release agent.
[0046] The polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier of component (C) is usually a compound represented by the following general formula: HO(CH2CH2O) a (CH(CH3)CH2O) b (CH2CH2O)CH (HO(CH(CH3)CH2O) d (CH2CH2O) e (CH(CH3)CH2O) f H In general formulae (1) and (2), a, b, c, d, e and f are the average number of moles of ethylene oxide or propylene oxide added, and each independently is a number from 1 to 350. The weight average molecular weight of component (C) is preferably 1,000 to 18,000, more preferably 1,500 to 10,000. From the viewpoint of emulsion stability, the HLB is preferably 10 to 18, more preferably 12 to 18. When component (C) is a solid, it can be used in the form of an aqueous solution.
[0047] The polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier of component (C) is available as the "Pluronic (registered trademark) L" series, "Pluronic (registered trademark) P" series, "Pluronic (registered trademark) F" series, and "Pluronic (registered trademark) TR" series of ADEKA Corporation, the Newpol PE series of Sanyo Chemical Industries, and the PE series of BASF Corporation. In particular, from the viewpoint of the stability, wettability, and suppression of stress cracks in plastics and the like of the plastic release agent obtained by the present invention, Pluronic (registered trademark) F-108 of ADEKA Corporation, Newpol PE75, PE108, PE128, PE68, PE78, and the like of Sanyo Chemical Industries can be particularly preferably used. The polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier of component (C) may be used alone or in combination of two or more kinds.
[0048] The amount of the (C) component used is 0.1 to 10.0 parts by mass relative to 100 parts by mass of the (A) component organopolysiloxane. It is preferably 0.15 to 8.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, and even more preferably 0.25 to 5.0 parts by mass. If it is less than 0.1 part by mass, the effect of improving the stability of the plastic release agent of the present invention cannot be expected. On the other hand, if it is more than 10.0 parts by mass, there is a risk that the wettability to the substrate or the crack resistance may decrease.
[0049] [(D) Polyoxyethylene sorbitan fatty acid ester] The release agent for plastics according to the present invention may further contain, as an optional component (D), 0.1 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by the following general formula (2). [ka] (R 2 is an alkyl group having 8 to 24 carbon atoms. a, b, and c are independently integers of 0 or more, and the sum of a+b+c is 8 to 30.
[0050] In formula (2), if the sum of a+b+c is less than 8, the emulsifiability may be insufficient and the stability may be poor. On the other hand, if the sum of +b+c is more than 30, the viscosity may be high or the composition may become solid, which may reduce the handling and workability.
[0051] The polyoxyethylene sorbitan fatty acid ester of component (D) may be used alone or in combination of two or more. The HLB of the polyoxyethylene sorbitan fatty acid ester of component (D) can be 10 to 18, preferably 12 to 18. If the HLB of component (D) is within this range, it has good emulsifying power, and by using it in combination with the above-mentioned components (B) and (C), a release agent for plastics with further improved stability may be obtained.
[0052] The amount of polyoxyethylene sorbitan fatty acid ester (D) used is 0.1 to 15.0 parts by mass relative to 100 parts by mass of the organopolysiloxane (A). It is preferably 0.2 to 13.0 parts by mass, and more preferably 0.5 to 11.0 parts by mass. If the amount of the (D) component is less than 0.1 part by mass, the stability of the emulsion in which the organopolysiloxane (A) is emulsified may not be sufficiently improved. On the other hand, if it is more than 15.0 parts by mass, cracks may occur when the plastic release agent of the present invention is applied to plastic.
[0053] [(E) Polyoxyethylene alkyl ether] The release agent for plastics according to the present invention may further contain, as desired, (E) 0.1 to 10.0 parts by mass of a polyoxyethylene alkyl ether represented by the following general formula (3). C m H 2m+1 (OCH2CH2) n OH (3) (m is an integer from 10 to 20, and n is an integer from 4 to 50.)
[0054] In the above formula (3), m is an integer of 10 to 20, and preferably an integer of 11 to 18. Furthermore, the alkyl group may be either branched or linear, and may be selected based on the ease of emulsification of the organopolysiloxane of component (A) and the resistance to cracking when applied to plastics.
[0055] In the above formula (3), n is an integer of 4 to 50. It is preferably 4 to 30, and more preferably 4 to 25. If n is smaller than 4, cracks are likely to occur in the plastic coated with the release agent for plastics of the present invention. On the other hand, if n is larger than 50, the effect of improving stability is weakened.
[0056] The component (E) may be used alone or in combination of two or more kinds. The HLB value of the component (E) may be 8 to 18, preferably 9 to 17, and more preferably 10 to 16.
[0057] Specific examples of component (E) include polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene hexyldecyl ether, polyoxyethylene isostearyl ether, polyoxyethylene octyldodecyl ether, and the like, but are not limited to these.
[0058] The amount of polyoxyethylene alkyl ether (E) used is 0.1 to 10.0 parts by mass relative to 100 parts by mass of organopolysiloxane (A). If the amount of component (E) is less than 0.1 part by mass, the stability of the emulsion in which organopolysiloxane (A) is emulsified may not be sufficiently improved. On the other hand, if the amount is more than 10.0 parts by mass, depending on the type of polyoxyethylene alkyl ether, cracks may occur when the plastic release agent of the present invention is applied to plastic.
[0059] [(F)Water] The release agent for plastics of the present invention is an emulsion composition of organopolysiloxane and is in the form of an oil-in-water emulsion characterized in that (E) water is the dispersion medium (=continuous phase).
[0060] The amount of water used as component (F) is 35 to 100,000 parts by mass relative to 100 parts by mass of the organopolysiloxane as component (A). It is preferably 50 to 20,000 parts by mass. If the amount of water (F) is less than 35 parts by mass, stickiness, uneven coating, and cracks may occur when the plastic release agent of the present invention is applied to plastic, and the viscosity of the emulsion composition increases, which is not preferable. On the other hand, if the amount of water (F) is more than 100,000 parts by mass, the mechanical stability decreases, and oil floating may occur after dilution and stirring. In addition, if the dilution ratio is high, the amount of emulsion composition required to be used to exert its effect as a release agent increases, which is economically unfavorable.
[0061] [Other ingredients] The release agent for plastics of the present invention may contain a water-soluble polymer for the purpose of improving the dispersibility of the organopolysiloxane of component (A), etc. The water-soluble polymer compound is not particularly limited, and examples thereof include nonionic water-soluble polymer compounds, anionic water-soluble polymer compounds, cationic water-soluble polymer compounds, and amphoteric water-soluble polymer compounds.
[0062] Examples of nonionic water-soluble polymer compounds include vinyl alcohol polymers, copolymers of vinyl alcohol and vinyl acetate, acrylamide polymers, vinylpyrrolidone polymers, copolymers of vinylpyrrolidone and vinyl acetate, polyethylene glycol, isopropylacrylamide polymers, methyl vinyl ether polymers, starch, methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, guar gum, and xanthan gum.
[0063] Examples of anionic water-soluble polymer compounds include sodium acrylate polymers, copolymers of sodium acrylate and sodium maleate, copolymers of sodium acrylate and acrylamide, polymers of sodium styrenesulfonate, copolymers of sodium polyisoprene sulfonate and styrene, polymers of sodium naphthalenesulfonate, carboxymethyl starch, starch phosphate, carboxymethyl cellulose, sodium alginate, gum arabic, carrageenan, sodium chondroitin sulfate, and sodium hyaluronate.
[0064] Examples of the cationic water-soluble polymer compound include a polymer of dimethyldiallylammonium chloride, a polymer of vinylimidazoline, a polymer of methylvinylimidazolium chloride, a polymer of ethyltrimethylammonium chloride acrylate, a polymer of ethyltrimethylammonium chloride methacrylate, a polymer of acrylamidopropyltrimethylammonium chloride, a polymer of methacrylamidepropyltrimethylammonium chloride, an epichlorohydrin / dimethylamine polymer, a polymer of ethyleneimine, a quaternary product of an ethyleneimine polymer, a polymer of allylamine hydrochloride, polylysine, cationic starch, cationic cellulose, chitosan, and derivatives thereof obtained by copolymerizing a monomer having a nonionic group or an anionic group with these, and the like.
[0065] Examples of amphoteric water-soluble polymer compounds include copolymers of ethyltrimethylammonium chloride acrylate, acrylic acid, and acrylamide, copolymers of ethyltrimethylammonium chloride methacrylate, acrylic acid, and acrylamide, and Hoffman degradation products of acrylamide polymers.
[0066] The plastic release agent of the present invention may contain an antibacterial preservative or an antimicrobial agent. Examples of the antibacterial preservative include paraoxybenzoic acid alkyl esters, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, phenoxyethanol, and isothiazolinone derivatives, while examples of the antibacterial agent include benzoic acid, salicylic acid, phenol, sorbic acid, paraoxybenzoic acid alkyl esters, p-chloro-m-cresol, hexachlorophene, benzalkonium chloride, chlorhexidine chloride, trichlorocarbanilide, photosensitizers, and phenoxyethanol. In addition to the above, pH adjusters, fragrances, antioxidants, rust inhibitors, dyes, fillers, curing catalysts, organic powders, and inorganic powders may also be blended.
[0067] [Preparation of Composition] The release agent for plastics of the present invention can be obtained in the form of an oil-in-water emulsion by emulsifying (A) organopolysiloxane in (F) water using (B) anionic surfactant, (C) polyoxyethylene-polyoxypropylene copolymer type nonionic emulsifier, and, if necessary, (D) polyoxyethylene sorbitan fatty acid ester, and / or (E) polyoxyethylene alkyl ether. Note that, hereinafter, "particle size" or "particle diameter" refers to the average particle size of emulsion particles measured by a laser diffraction / scattering method.
[0068] Emulsification may be performed using a general emulsifying / dispersing machine, for example, a high-speed rotating centrifugal radial type agitator such as a homodisper, a high-speed rotating shear type agitator such as a homomixer, a high-pressure jet type emulsifying / dispersing machine such as a pressure homogenizer, a colloid mill, a combimix, an in-line continuous emulsifier, a vacuum emulsifier, a continuous mixing device, an ultrasonic emulsifier, etc.
[0069] The temperature during emulsification is preferably 0 to 80°C, more preferably 10 to 60°C. At a temperature of 10°C to 80°C, emulsification is easy, and the produced emulsion tends to be more stable. The pressure during emulsification may be normal pressure or reduced or increased pressure. When emulsifying under reduced or increased pressure, bubbles are less likely to be mixed in, and emulsification may be effective. When reducing the pressure, it is preferable that the pressure is higher than the vapor pressure of the raw material so that the raw material does not volatilize. In addition, when using a batch-type emulsification device, there is no particular designation for the emulsification time, and it may be the time required to achieve the desired particle size, but generally it is preferable that the emulsification time is 360 minutes or less.
[0070] The average particle size of the release agent for plastics of the present invention is more than 100 nm and is not more than 1000 nm. It is preferably more than 200 nm and is not more than 800 nm. If the average particle size is larger than 1000 nm, the dilution stability and mechanical stability are reduced, and oil floating may occur during dilution or stirring. In addition, there is a risk of separation of light and dark when stored for a long period of time. On the other hand, in order to produce an emulsion with an average particle size of 100 nm or less, the content of nonionic surfactants such as (C) polyoxyethylene-polyoxypropylene copolymer type nonionic emulsifier, (D) polyoxyethylene sorbitan fatty acid ester, and (E) polyoxyethylene alkyl ether, etc., generally tends to be high relative to (A) organopolysiloxane. For this reason, when the components (C), (D), and (E) are used within the quantitative range of the present invention, it is difficult to achieve an emulsion particle size of 100 nm or less, and when the components (C), (D), and (E) are blended beyond the range of the present invention, there is a risk of reduced releasability and cracks occurring when applied to plastics.
[0071] [Use of plastic release agents and manufacturing method for plastics for food packaging] The emulsion obtained by the above method is extremely useful as a release agent for plastic sheets for food packaging and molded products thereof, and as a release agent for use in molding. For example, the release agent for plastics of the present invention, which contains 0.1 to 2.0% by mass of component (A), can be applied by rotor dampening, gravure or spraying. The application amount is generally 0.01 to 1.0 g / m2, particularly 0.02 to 0.2 g / m2, on a dry basis. If it is 0.01 g / m2 or more, sufficient release properties are obtained, and if it is 1.0 g / m2 or less, it is preferable from the viewpoint of transparency and stickiness.
[0072] Plastics used for food container packaging include polyethylene, polypropylene, polymethylpentene, polybutene, ethylene-tetracyclododecene copolymer, ethylene-2-norbornene copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer, polyphenylene ether, polyacrylonitrile, polymethacrylic styrene, polymethyl methacrylate, nylon, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyacetal, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, and polyvinyl chloride.
[0073] According to the present invention, by emulsifying an organopolysiloxane in water using an anionic surfactant, a polyoxyethylene-polyoxypropylene copolymer type nonionic emulsifier, and, as necessary, a polyoxyethylene sorbitan fatty acid ester and / or a (E) polyoxyethylene alkyl ether, it is possible to provide a release agent for plastics which has excellent release properties, as well as good dilution stability, mechanical stability, storage stability and wettability, and which is less likely to cause stress cracks.
[0074] Furthermore, it is possible to provide a method for producing plastics for packaging food containers, characterized by using the release agent for plastics of the present invention. Specifically, by using the release agent for plastics of the present invention, it is possible to provide a method for producing the above-mentioned plastics for packaging food containers, particularly plastic sheets (including films) for packaging food and molded products thereof, by releasing or molding with a mold.
[0075] The method for producing the food container packaging plastic is as follows: Step (I): A step of applying the release agent for plastics of the present invention to a mold or the like by spraying or the like; Step (II): Molding plastic for food packaging; and Process (II): The process of releasing the plastic for food container packaging after molding. The coating method, coating amount and types of usable plastics are as described above. EXAMPLES
[0076] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.
[0077] The components used in the following Examples and Comparative Examples are as follows:
[0078] [Component (A) and comparative organopolysiloxane] (A1) Organopolysiloxane: Represented by the following general formula (4), having a kinetic viscosity of 9970 mm2 / s at 25°C and L1 of 580, and containing octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane each at 100 ppm or less. [ka]
[0079] [Component (B)] (B1) 40% aqueous solution of sodium alkanesulfonate (trade name: LATEMURU PS, manufactured by Kao Corporation), (B2) 65% aqueous solution of sodium dodecylbenzenesulfonate (trade name: Neopelex G-65, manufactured by Kao Corporation), (B3) 70% aqueous solution of sodium dioctyl sulfosuccinate (trade name: PEREX OT-P, manufactured by Kao Corporation), (B4) sodium lauryl sulfate (trade name: EMAL 2FG, manufactured by Kao Corporation), (B5) 70% aqueous solution of sodium polyoxyethylene alkyl ether sulfate (trade name: EMAL 270J, manufactured by Kao Corporation)
[0080] [Component (C)] (C1) Polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier (trade name Pluronic (registered trademark) F108, manufactured by Adeka Corporation)
[0081] [Component (D)] (D1) Polyoxyethylene sorbitan monooleate (trade name: Rheodor TW-O120V, manufactured by Kao Corporation), (D2) Polyoxyethylene sorbitan monolaurate (trade name: Nonion LT-221, manufactured by NOF Corporation)
[0082] [Component (E)] (E1) Polyoxyethylene lauryl ether (product name: Emulgen 108, manufactured by Kao Corporation), (E2) 80% polyoxyethylene alkyl ether aqueous solution (product name: Leocol TDN90-80, manufactured by Lion Corporation)
[0083] [Component (F)] (F) Water [Other emulsifiers] (1) Polyoxyethylene distyrenated phenyl ether (product name: Emulgen A-60, manufactured by Kao Corporation), (2) Sorbitan monolaurate (Nonion LP-20R, manufactured by NOF Corporation) [Other ingredients] Sodium benzoate, citric acid, methyl p-hydroxybenzoate, propyl p-hydroxybenzoate
[0084] [Example 1] (B1) 2 parts by mass of anionic surfactant, (C1) 1 part by mass of polyoxyethylene-polyoxypropylene copolymer type nonionic emulsifier, (E1) 3.0 parts by mass of polyoxyethylene alkyl ether, (A1) 0.1 parts by mass of methyl p-hydroxybenzoate, 0.03 parts by mass of propyl p-hydroxybenzoate, and (F) 4.0 parts by mass of water were mixed in advance, placed in a container containing (A1) 60.0 parts by mass of organopolysiloxane, and emulsified using a continuous emulsifier. The obtained emulsion was diluted with (F) 29.87 parts by mass of water, and stirred until homogenous, to prepare a plastic release agent (in the form of an emulsion composition) according to Example 1.
[0085] [Examples 2 to 3, Comparative Examples 1 to 4] Using the same procedure as in Example 1, plastic release agents according to Examples 2 to 3 and Comparative Examples 1 to 4 (all in the form of emulsion compositions) were prepared using the compositions in Table 1. In Table 1, "parts" means parts by mass.
[0086] [Table 1]
[0087] The average particle size, pH, storage stability, wettability to a film, and stress cracking to a film were evaluated for the plastic release agents of Examples 1 to 3 and Comparative Examples 1 to 4. The details of the evaluation method are explained below.
[0088] [Average particle size] Using water as a dispersion medium, the particle size of the silicone emulsion was measured with a laser diffraction particle size distribution analyzer (Malvern Panalytical's Mastersizer 3000) to obtain the median diameter (particle size equivalent to 50% of the cumulative distribution).
[0089] [Storage stability] Each plastic release agent was placed in a glass bottle with a capacity of about 30 mL and stored in an oven at 50° C., and water separation, oil separation, and creaming were evaluated. The evaluation was based on the following criteria. ○: Almost no separation occurred after 1 month at 50℃ △: Almost no separation occurs after 2 weeks at 50℃, but after 1 month at 50℃, water separation, oil separation, or creaming occurs. ×: After 2 weeks at 50°C, water separation, oil separation or creaming occurred.
[0090] [Wettability] Each plastic release agent is applied to a PET film (Lumirror(R) T60, manufactured by Toray Industries, Inc.) using a Mayer bar No. 3. The occurrence of repellency was confirmed by visual inspection. ◯: Overall wettability Δ: Partial repellency occurs ×: Overall repellency occurs immediately after coating In this specification, "◯" and "Δ" are judged as good, and "×" is judged as bad.
[0091] [Crack resistance] 10 g of the above emulsion composition is placed in a 30 cc glass bottle, and a 2.5 cm x 6 cm OPS sheet (= biaxially oriented polystyrene sheet, Sanctoria SP manufactured by Mitsubishi Chemical Corporation) is rolled and immersed in the bottle. After placing in a 50°C oven for 7 hours, the presence or absence of cracks is visually confirmed. "○" is judged as good, and "×" is judged as bad.
[0092] The evaluation results of the release agents for plastics according to Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 2 below. [Table 2]
[0093] From the above evaluation results, it was found that the release agents for plastics of the present invention (Examples 1 to 3) had excellent storage stability, relatively good wettability, and were less likely to cause stress cracks in plastics, and also had excellent crack resistance.
[0094] On the other hand, in Comparative Examples 1 to 4 lacking the component (C) of the present invention, any one of crack resistance, storage stability, and wettability was poor, and even if the component (D) or (E) was used instead of the component (C), it was not possible to achieve good performance in all of these properties equivalent to the examples of the present invention. Therefore, the plastic release agent of the present invention, which uses the components (A) to (C) and water (F) in a certain quantitative range, has clear performance advantages over known techniques, and is expected to realize sufficient technical benefits, particularly when used in the production of plastics for food container packaging.
Claims
1. (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1), having a kinematic viscosity at 25°C of 100 to 100,000 mm / s, and containing less than 1 mass% each of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane: 【Chemistry 1】 (In the formula, R １ may be the same or different and are either a hydroxy group, a hydrogen atom, an unsubstituted linear alkyl group having 1 to 32 carbon atoms, or a phenyl group, and L is an integer from 60 to 1,500. (B) Anionic surfactant: 0.1 to 18.0 parts by mass, (C) 0.1 to 10 parts by mass of a polyoxyethylene-polyoxypropylene copolymer nonionic emulsifier, and (F) Water: 35 to 100,000 parts by mass and wherein the average particle size of the emulsion particles measured by a laser diffraction / scattering method is more than 100 nm and not more than 1000 nm.
2. 2. The mold release agent for plastics according to claim 1, wherein the component (B) is one or more anionic surfactants selected from the group consisting of alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl phosphates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkyl ether phosphates.
3. Furthermore, (D) a compound represented by the following general formula (2): 【Chemistry 2】 (R ２ is an alkyl group having 8 to 24 carbon atoms; a, b, and c are independently integers of 0 or more, and the sum of a+b+c is 8 to 30.
2. The mold release agent for plastics according to claim 1, comprising 0.1 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by the formula:
4. Furthermore, (E) the following general formula (3): C ｍ H ２ｍ＋１ (OCH) ２ CH ２ ) ｎ OH (3) (m is an integer from 10 to 20, and n is an integer from 4 to 50.) 0.1 to 10.0 parts by mass of a polyoxyethylene alkyl ether represented by the formula: The release agent for plastics according to claim 1.
5. 5. The release agent for plastics according to claim 1, wherein the plastic is used for food packaging.
6. A method for producing plastics for food container packaging, using the mold release agent for plastics according to any one of claims 1 to 4.