CN105150510A - Fully-degradable polycaprolactone film and production method and application thereof - Google Patents
Fully-degradable polycaprolactone film and production method and application thereof Download PDFInfo
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Abstract
The invention relates to fully-degradable polycaprolactone (PLC) film and a production method thereof. The fully-degradable polycaprolactone film has a spontaneous gas regulating function. The production method comprises the steps that polycaprolactone master batches are dried in a vacuum drying box; the dried polycaprolactone master batches are subjected to melt extrusion in a twin-screw extruder; a cast sheet is formed on a flow-casting roller; the cast sheet is stretched in the longitudinal direction according to uniaxial extension ratio of 3-5, and the fully-degradable polycaprolactone film which is uniaxially stretched in the longitudinal direction is obtained. By means of PCL freshness protection packages, the shelf life of strawberries is effectively prolonged and reaches 20-28 days, and the fully-degradable polycaprolactone film has great significance on the aspect of the application of environment-friendly materials in food packaging.
Description
[technical field]
The invention belongs to food preservative technology field.More specifically, the present invention relates to a kind of Wholly-degradable pla-pcl film with spontaneous controlled atmosphere function, also relate to described Wholly-degradable pla-pcl film production method, also relate to the purposes of described Wholly-degradable pla-pcl film.
[background technology]
Strawberry delicious flavour, has higher nutritive value, the huge market demand.Fresh strawberry pericarp is thin, coarse surface structure, and water content, up to 90 ~ 95%, is organized tender and lovely, vulnerable and microbial infection and rots, and places that within 1 ~ 2 day, just to start variable color spoiled at normal temperatures, and can rot time serious, fresh rate declines obviously.Therefore, only make full use of modern science and technology unified with nature condition to extend the strawberry preservation phase, improve Strawberry industry economic benefit, to meet the multiple requesting of people to food security, quality and nutrition.It is fresh-keeping that the storage of current strawberry and preservation method mainly contain deepfreeze, heat treatment, irradiation, air conditioned storage and chemical preservative.
The people such as Qiu Chaokun are being entitled as " application study in strawberry preservation of lysozyme and nisin ", " Agriculture In Hubei Province ", (7), lysozyme and nisin is have studied on the impact of strawberry preservation by low temperature effect in the article of pp1631-1633 (2014), result show 0.01% lysozyme and the composite fresh-keeping liquid of 0.10%Nisin best to strawberry preservation effect, preserve first 5 days without decayed fruit.Gao Xin, Zheng Huayan be " Different Package material is on the impact of Storage of Strawberry quality and freshness date " being entitled as, " food industry science and technology ", (2) in (2015), adopt LDPE, HDPE plastic package material different from OPP to carry out the research of cold storing and fresh-keeping packaging to strawberry, result shows that plastic packaging film can obviously suppress strawberry to go bad; Have best compared with the HDPE film fresh-keeping effect of low air penetrability.Zhang Jianhao is at " fresh food preservation and freshness packing technique ", Chemical Industry Press publishes in (2009) and points out, controlled atmospheric packing (MPA) technology can extend the shelf life of fruits and vegetables greatly, generally speaking, the MAP of fruits and vegetables series products should select has better gas permeability and moisture permeable material, and notes CO
2and O
2selective through, its CO
2/ O
2tranmittance be 8 ~ 10:1 be ideal.And the controlled atmospheric packing material sold in the market is such as the thin-film materials such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), PVDC, polyamide and PET, their CO
2/ O
2tranmittance be about 3 ~ 6:1, the demand of desirable controlled atmospheric packing can not be met.The people such as Xiao Gongnian are being entitled as " controlled atmospheric packing (MAP) is on the impact of strawberry preservation ", " food industry science and technology ", (6), have studied the effect that controlled atmospheric packing technology is fresh-keeping to Storage of Strawberry in pp68-71 (2003), result shows that the condition of the best air conditioned storage of strawberry is 2.5%O
2, 16%CO
2, it can extend 4 ~ 6 days the shelf life of strawberry like this.
CN99103003.6 discloses a kind of aerated strawberry preserving bag.This aerated strawberry preserving bag comprises bag, ethene adsorbent, the fresh-keeping gas of mixing and strawberry, the composition mixing fresh-keeping gas is nitrogen, oxygen and carbon dioxide, its volume ratio is nitrogen 94-95%, oxygen 1.5-4%, carbon dioxide 2-4.5%, and mixture pressure is 1.00 × 10
5pa-3 × 10
5pa.
CN201210261821 discloses the air regulating fresh-keeping method of a kind of strawberry, the strawberry of fresh harvesting is placed in packing container through precooling, and in described packing container, pass into the mist of oxygen, carbon dioxide and nitrogen three kinds of gases, make that the concentration of packing container nitrogen is 85-95%, the concentration of oxygen is 1-8%, the concentration of carbon dioxide is 1-6%, refrigerate in the freezer of packaged strawberry being inserted 0 ~ 2 DEG C.
Use antistaling agent can extend strawberry shelf life, but food security hidden danger can be brought, and gas flush packaging can increase transportation cost, and these packaging material in a large number use can cause environmental pressure, easily cause white pollution.
Therefore, for the technological deficiency that prior art exists, the present inventor, on the basis of summing up prior art, by lot of experiments, completes the present invention finally.
[summary of the invention]
[technical problem that will solve]
The object of this invention is to provide a kind of Wholly-degradable pla-pcl film with spontaneous controlled atmosphere function.
Another object of the present invention is to provide the production method of described Wholly-degradable pla-pcl film.
Another object of the present invention is to provide the purposes of described Wholly-degradable pla-pcl film.
[technical scheme]
The present invention is achieved through the following technical solutions.
The present invention regulates and controls Wholly-degradable PCL film gas permeability by restrained stretching ratio and film thickness.By to film water steam, carbon dioxide (CO
2) and oxygen (CO
2) etc. permeability test, choose the PCL film preparation spontaneous controlled-atmosphere preservation bag that stretch ratio is 3-5, it stores in the cold fresh cabinet of temperature about 4 DEG C for packing strawberry.Measured by sensory evaluation, physical and chemical index, the fresh-keeping effect of the comprehensive assessment packaging bag such as atmosphere composition in packaging bag, and carried out comparative analysis with the fresh-keeping effect that unpacked, commercially available nylon/polyethylene (PA/PE) and PE pack strawberry.
The present invention relates to a kind of Wholly-degradable pla-pcl film with spontaneous controlled atmosphere function.
Described Wholly-degradable pla-pcl film is the Wholly-degradable pla-pcl film of single shaft longitudinal stretching, and it has following characteristic:
A, thermal property
Melt temperature T
m: 62.8-64.1 DEG C; Heat content Δ H
m: 68.0-68.4J/g; Uniaxial tension compares: 3-5.
The differential scanning calorimeter (i.e. DSC) sold with commodity DSCQ20 by TA Instrument Ltd. of the U.S. is adopted to measure thermal property.This instrument is depicted as a kind of curve over time by thermocouple collection material hot-fluid in lifting/lowering temperature process, and because material can a large amount of heat absorption when fusing point, sharp-pointed peak appears in curve herein, and namely peak temperature is this material melt temp.The DSC heating curve of the PCL film of different uniaxial tension ratio is shown in that the DSC characteristic parameter of accompanying drawing 1, PCL film is listed in table 1.
Table 1: different stretch is than the DSC characteristic parameter of PCL film
The curve of accompanying drawing 1 and the data of table 1 clearly show, the melt temperature T of the PCL film that do not stretch
mwith heat content △ H
mminimum.Along with the increase of draw ratio, melt temperature T
m64.1 DEG C are increased to, heat content △ H from 59.5 DEG C
mfrom 51.11Jg
-1be increased to 68.40Jg
-1, illustrate PCL film after orientation because strand is arranged in parallel, crystallization temperature and degree of crystallinity increase, and crystal property also improves thereupon.
B, mechanical property
The longitudinal mechanical performance of film:
Yield strength σ
s: 19.7-90.8MPa; Elongation at break Δ: 73-179%;
Young's modulus Y:274-343MPa;
The horizontal mechanical performance of film:
Yield strength σ
s: 17.5-18.7MPa; Elongation at break Δ: 270-648%;
Young's modulus Y:208-485MPa;
Adopt the mechanical property being measured PCL film by Dongguan City Xing Hui Electronics Co., Ltd. with the mechanical test machine that trade name computer Tension-pressure tester XH-8750 sells.This material is (load, speed, temperature etc.) under various operating conditions, from the mechanical characteristics that presents in stressed (static(al) or power) to the overall process destroyed, comprising yield strength, elongation at break, Young's modulus.
Different draw ratio PCL film is listed in Fig. 2 and Fig. 3 respectively at the load-deformation curve on horizontal and vertical.The result of calculation of its yield strength, elongation at break and Young's modulus is listed in table 2.
Table 2: the mechanical property of different draw ratio PCL film
The data of Fig. 2 and table 2 are clear to be known, in cross directional stretch group, compared with the PCL film that do not stretch, yield strength and the Young's modulus of stretching PCL film all obviously increase.Wherein, the yield strength of 5 times of stretching PCL films is 17.5MPa, although lower than 3 times of stretching PCL films, its elongation at break and Young's modulus are apparently higher than 3 times of stretching PCL films.These result of the tests show, uniaxial tension makes the horizontal lear energy of PCL film and rigidity strengthen all to some extent, and deformation is less likely to occur material.
The data of Fig. 3 and table 2 are clear to be known, in longitudinal stretching group, the yield strength of stretching PCL film and Young's modulus are all higher than the PCL film that do not stretch, and elongation at break but significantly reduces.The yield strength of 5 times of stretching PCL films is 90.8MPa, and Young's modulus is 343.4MPa, and all higher than 3 times of stretching PCL films, and elongation at break significantly reduces.These result of the tests show, uniaxial tension can improve equally PCL film longitudinally on lear energy and rigidity, the reason that toughness weakens is because in drawing process, draw ratio is larger, it is larger that the strand of film or segment stretch degree, the deformation quantity that can bear in extension test process is less, and then under high draw ratio, the elongation at break of film is lower, and toughness is more weak.
For same draw ratio PCL film, the drafting results in different stretch direction is known, the film yield strength of longitudinal stretching is large, and elongation at break is low, illustrates that film is strong along differently-oriented directivity lear energy.
C, air permeable performance
Adopt coulomb coulometry to measure under the test condition of thickness 50-103 micron, relative humidity 40-70% and temperature 23 DEG C, its OTR oxygen transmission rate is 345-1460cm
3m
-2d
-1; Oxygen transmission coefficient is 4.65-8.63 × 10
-13cm
3mm
-2s
-1pa
-1; Water vapour permeability is 384-840gm
-2d
-1; Steam transmission coefficient is 2.08-3.61 × 10
-10gmm
-2s
-1pa
-1;
Adopt pressure differential method to measure under relative humidity 0% with the test condition of temperature 5-23 DEG C, its carbon dioxide transmission rate is 5028-11204cm
3m
-2d
-1; OTR oxygen transmission rate is 492-1501cm
3m
-2d
-1; Carbon dioxide/oxygen tranmittance is 8.1-10.2.
The present invention uses by UKSystechIllinoisInstruments according to ASTM1434-82, Inc. the pressure differential method that company sells with trade name LyssyL100-5000 determines the oxygen permeability energy of PCL film under temperature 5-23 DEG C of temperature conditions through instrument, the results are shown in Table 3 for it.
Table 3: the oxygen permeability energy of uniaxial tension PCL film
Known that by the data of table 3 oxygen transmission coefficient (OP) value of the PCL film that do not stretch is 7.34 × 10 when RH=40%
-13cm
3mm
-2s
-1pa
-1, when RH=70%, OP value increases to 8.10 × 10
-13cm
3mm
-2s
-1pa
-1, the OP value of 3 times of stretchings and 5 times of stretching PCL films also presents identical variation tendency, and the PCL film of same stretch multiple is described, the oxygen resistance of the larger then film of humidity is more weak.
Under identical relative humidity, the OP value of PCL film along with the increase of draw ratio first reduce after sharply increase.As RH=40%, the OP value of 3 times of stretching PCL films is 4.65 × 10
-13cm
3mm
-2s
-1pa
-1, be starkly lower than 1 times of stretching and 5 times of PCL films stretched.The test of its excess-three kind humidity has this Changing Pattern equally, illustrates that the oxygen resistance of 3 times of stretching PCL films is the strongest.Its reason is under certain draw ratio, and the molecule segment degree of orientation of PCL film and degree of crystallinity are improved, and now the oxygen resistance of film is also improved; And when draw ratio is excessive, crystal region is destroyed, the combination between molecule segment is than also loose when not stretching, and film defects increases, and the path that oxygen can pass through is increased, and causes oxygen resistance to reduce.And humidity is larger in test process, the oxygen resistance of film is more weak.
The present invention uses by the U.S. according to ASTM1434-82, and MOCON company determines the moisture vapor permeability energy of PCL film with the moisture-inhibiting instrument that trade name Permatran-w3/61 sells under temperature 5-23 DEG C of temperature conditions, and the results are shown in Table 4 for it.
Table 4: the water vapor permeance energy of uniaxial tension PCL film
The result of table 4 shows, for the PCL film of same stretch multiple, its steam transmission coefficient (WVP) value increases with humidity and reduces.For the PCL film do not stretched, time relative humidity (RH)=40%, WVP value is 3.36 × 10
-10gmm
-2s
-1pa
-1, and when RH increases to 70%, WVP value is reduced to 2.41 × 10 on the contrary
-10gmm
-2s
-1pa
-1.Stretch and 5 times of stretching PCL films for 3 times, their WVP value also presents identical Changing Pattern.Illustrate that in test environment, humidity is larger thus, the moisture barrier property of PCL film is stronger, this is because PCL hydrophily is poor, along with humidity increases, the ability that PCL is combined with steam reduces, and therefore humidity is larger, WVP value is lower, thus embodies the good moisture barrier property of PCL.
Under identical humidity, the WVP value of PCL film declines afterwards along with the increase of draw ratio is first risen, as RH=40%, do not stretch and the WVP value of 3 times of stretching PCL films all higher, be respectively 3.36 × 10
-10gmm
-2s
-1pa
-1with 3.61 × 10
-10gmm
-2s
-1pa
-1, and the WVP value of 5 times of stretching PCL films is only 2.59 × 10
-10gmm
-2s
-1pa
-1, well below the WVP value of all the other two kinds of films, its excess-three kind humidity meets this Changing Pattern.It can thus be appreciated that the moisture barrier property of high draw ratio PCL film is better than low draw ratio PCL film after orientation.This phenomenon is the raising due to drawing process Middle molecule chain segment orientation degree and degree of crystallinity, and the moisture barrier property of film is improved.
According to the mode identical with above-mentioned oxygen permeability energy method of testing, under relative humidity 0% with the test condition of temperature 5-23 DEG C, determine carbon dioxide transmission rate is 5028-11204cm
3m
-2d
-1; OTR oxygen transmission rate is 492-1501cm
3m
-2d
-1; Carbon dioxide/oxygen tranmittance is 8.1-10.2
Preferably, described Wholly-degradable pla-pcl film has following characteristic:
A, thermal property
Melt temperature T
m: 62.8-64.1 DEG C; Heat content Δ H
m: 68.0-68.4J/g; Uniaxial tension compares: 3-5;
B, mechanical property
The longitudinal mechanical performance of film:
Yield strength σ
s: 30-70MPa; Elongation at break Δ: 90-150%;
Young's modulus Y:290-310MPa;
The horizontal mechanical performance of film:
Yield strength σ
s: 17.5-18.7MPa; Elongation at break Δ: 400-520%;
Young's modulus Y:290-405MPa;
C, air permeable performance
Adopt coulomb coulometry to measure in the test condition of thickness 50-103 micron, relative humidity 40-70% and temperature 23 DEG C, its OTR oxygen transmission rate is 650-1160cm
3m
-2d
-1; Oxygen transmission coefficient is 4.90-8.20 × 10
-13cm
3mm
-2s
-1pa
-1; Water vapour permeability is 480-740gm
-2d
-1; Steam transmission coefficient is 2.40-3.20 × 10
-10gmm
-2s
-1pa
-1;
Adopt pressure differential method in relative humidity 0% with under the test condition of temperature 5-23 DEG C, the transmitance of carbon dioxide is 6000-10200cm
3m
-2d
-1; OTR oxygen transmission rate is 692-1200cm
3m
-2d
-1; Carbon dioxide/oxygen tranmittance is 8.8-9.5.
The invention still further relates to the described production method with the Wholly-degradable pla-pcl film of spontaneous controlled atmosphere function.The step of the method is as follows:
Allow polycaprolactone master batch in vacuum drying chamber under temperature 35-45 DEG C with the condition of vacuum 0.1-0.5MPa dry 6-10 hour; Then, dry polycaprolactone master batch injects twin (double) screw extruder, twin-screw group temperature is adjusted to 60 DEG C ~ 150 DEG C successively, die head extrusion temperature is 150 DEG C, melt extrude under these conditions, casting roller forms slab, during by regulating the rotating speed of stationary roll and mobile roller to reach uniaxial tension than 3-5, longitudinal stretching is carried out, so obtain the Wholly-degradable pla-pcl film of single shaft longitudinal stretching under the condition of temperature 40 DEG C.
Wherein, the draw ratio of the Wholly-degradable pla-pcl film of single shaft longitudinal stretching is obtained by following formulae discovery:
In formula:
R represents draw ratio;
S
mrepresent the rotating speed of mobile roller;
S
frepresent the rotating speed of stationary roll.
The twin (double) screw extruder that the present invention uses is product sold in the market, and the general same experimental analysis Instrument Ltd. in such as Guangzhou is with trade name PPT-3/SJ2-20-250 twin (double) screw extruder product sold.The polycaprolactone master batch that the present invention uses is product sold in the market, such as, be with trade name 800c type polycaprolactone master batch product sold by Yi Sheng new material Co., Ltd of Shenzhen.The vacuum drying chamber that the present invention uses is product sold in the market.
The invention still further relates to the described Wholly-degradable pla-pcl film with spontaneous controlled atmosphere function and produce the purposes in fresh fruit vegetables packing material.
According to a kind of preferred embodiment of the present invention, described fresh fruit is strawberry.
According to a kind of preferred embodiment of the present invention, in strawberry storage period, CO in the packaging bag made from described Wholly-degradable pla-pcl film
2concentration remains in body 2 ~ 5%, O
2concentration remains on by volume 3 ~ 7%, thus keeps the desirable atmosphere composition of strawberry preservation.
According to a kind of preferred embodiment of the present invention, during the packaging bags strawberry using described Wholly-degradable pla-pcl film to make, strawberry shelf life reaches 20-28 days.
It is short to the present invention is based on the fresh strawberry shelf-life, and the object of putrefactive production status combining environmental protection works out a kind of strawberry preserving bag with spontaneous controlled-atmosphere function.By to film water steam, carbon dioxide (CO
2) and oxygen (CO
2) etc. permeability test, selected stretch ratio is the PCL film preparation spontaneous controlled-atmosphere preservation bag of 5.Measured by sensory evaluation, physical and chemical index, the fresh-keeping effect of the comprehensive assessment packaging bag such as atmosphere composition in packaging bag, and be analyzed with the fresh-keeping effect that unpacked commercially available nylon/polyethylene (PA/PE), PE pack, result shows in relative humidity 50%, under the cryogenic conditions that temperature is about 4 DEG C, unpackaged strawberry went mouldy completely at the 8th day.Oxygen content in the packaging bag made from PA/PE sharply declines.At the 8th day O
2content is almost 0, CO
2content is more than 20%, and anaerobic respiration starts, and due to film poisture-penetrability poor, in bag, dew condensation phenomenon is serious, thus causes strawberry to start to occur peculiar smell corruption at the 8th day.And PCL packaging bag of the present invention has good moisture-penetrable ventilated property and CO
2/ O
2select tranmittance 10.22, the respiration of strawberry in this bag can its atmosphere component of spontaneous adjustment, reaches 2 ~ 5%CO of relative constancy
2with 3 ~ 7%O
2, the very suitable strawberry preservation of this atmosphere, and without dew condensation phenomenon.Therefore, strawberry shelf life more than 20 days, still can have edibility 28 days time.The environmentally friendly PCL freshness protection package of Wholly-degradable of the present invention effectively extends the shelf life of strawberry, for the application of ep-type material in packaging for foodstuff, significant.
[beneficial effect]
The invention has the beneficial effects as follows: the freshness protection package that the Wholly-degradable pla-pcl film using the present invention to have spontaneous controlled atmosphere function is made has good moisture-penetrable ventilated property and CO
2/ O
2select tranmittance 10.22, the respiration of strawberry in this bag can its atmosphere component of spontaneous adjustment, reaches 2 ~ 5%CO of relative constancy
2with 3 ~ 7%O
2, the very suitable strawberry preservation of this atmosphere, and without dew condensation phenomenon.Therefore, strawberry shelf life more than 20 days, still can have edibility 28 days time.The environmentally friendly PCL freshness protection package of Wholly-degradable of the present invention effectively extends the shelf life of strawberry, for the application of ep-type material in packaging for foodstuff, significant.And in prior art, the oxygen content in the packaging bag made from PA/PE sharply declines.At the 8th day O
2content is almost 0, CO
2content is more than 20%, and anaerobic respiration starts, and due to film poisture-penetrability poor, in bag, dew condensation phenomenon is serious, thus causes strawberry to start to occur peculiar smell corruption at the 8th day.
[accompanying drawing explanation]
Fig. 1 is the DSC heating curve figure of different draw ratio PCL film;
Fig. 2 is different draw ratio PCL film lateral stress-strain curve figure;
Fig. 3 is different draw ratio PCL film longitudinal stress-strain curve figure;
Fig. 4 is the CO of PCL, PA/PE and PE film
2, O
2transmitance and tranmittance figure thereof;
Fig. 5 is the fresh-keeping effect figure of Different Package bag packaging strawberry;
Wherein:
A-PCL freshness protection package the 14th day; B-PCL freshness protection package the 22nd day; C-blank group the 10th day; D-PA/PE bag the 10th day; E-PCL group and blank organize the 10th day; F-PE group the 10th day.
Fig. 6 is the strawberry quality comparison figure of strawberry at storage period;
Wherein:
A-strawberry sense organ is with the variation diagram in storage time; The weightless variation diagram with the storage time of b-strawberry; C-strawberry hardness is with the variation diagram in storage time; D-strawberry ascorbic acid content is with the variation diagram in storage time; E-strawberry solid content is with the variation diagram in storage time.
[detailed description of the invention]
The present invention can be understood better by following embodiment.
Embodiment 1: the fresh-keeping test of PCL film of the present invention
One, test method
If five process, 3 repetitions are established in each process, average as measured value.
PCL group: by stretch ratio be 5 PCL film preparation become 20cm × 12cm packaging bag, directly the 50g fresh strawberry of harvesting is put into PCL packaging bag.
PA/PE group: load 50g fresh strawberry in 17 × 12cmPA/PE bag (PA polyamide) commercially.
PE group: load 50g fresh strawberry in 17 × 12cmPE bag (PE polyethylene) commercially.
Blank group: without any packaging.
The cold fresh cabinet of temperature about 4 DEG C all put into by the bag these being assembled with strawberry, routine observation, detection physics and chemistry and organoleptic indicator.
Two, method of testing
The gas-premeable of I, film: according to ASTM1434-82, uses pressure differential method to test under the condition of temperature 5-23 DEG C through instrument.
II, sensory evaluation scores method: form group by 12 through start-up and mark; Strawberry color and luster, structural state, fruital local flavor are marked according to ten fraction systems, remove 1 best result and 1 minimum point, remaining point of sum is obtained a mean value divided by 8.
III, weight-loss ratio measure: use electronic balance to take the starting weight of test strawberry and the weight after storing, then calculate weight-loss ratio according to the following formula:
Weight-loss ratio (%)=(after starting weight-storage weight)/starting weight × 100
IV, hardness test: use the fruit hardometer sold with trade name GY-1 fruit hardometer by Zhejiang company of Top to carry out hardness test to choosing strawberry three different parts, often group gets 8 Duplicate Samples, using its mean value as final hardness.
The anti-sepsis acid content of V, employing Conventional UV spectrophotometry test strawberry.
Three, result of the test
I, PCL, PA/PE and PE film permeability
The water vapo(u)r transmission energy of PCL, PA/PE and PE film listed by table 5.Known by table 5, the steam penetrating capacity of PCL group is 350 times of PA/PE film, 135 times of PE film.PA/PE and PE packing film is very high to the barrier of steam, and steam penetrating capacity is little.When this two based packaging material is used for strawberry packaging, inner rising moisture cannot be discharged to outer package in time and easily cause dew condensation phenomenon, impel conk, accelerate the corruption of strawberry.PCL film has suitable water vapo(u)r transmission, can avoid producing dew condensation phenomenon, is beneficial to the fresh-keeping of strawberry.
Table 5: different film water vapor permeation performance
The CO of PCL, PA/PE and PE film
2, O
2the situation that transmitance and tranmittance thereof change along with temperature is shown in accompanying drawing 4.PA/PE group is to CO
2and O
2barrier very good, although along with the raising CO of temperature
2and O
2transit dose increase to some extent, but its transit dose is still lower.PE group has good CO
2and O
2permeability, and PCL occupy between PA/PE and PE film, and CO
2and O
2transit dose all promote along with the raising of temperature.PA/PE to have respiratory fruits and vegetables pack time, package interior gas cannot be exchanged in time, can cause a large amount of CO like this
2pile up, oxygen content declines, and fruits and vegetables can carry out anaerobic respiration and produce harmful substance under the low oxygen content of pole.The gas barrier property of PE and PCL group is lower, during vegetable and fruit packaging can in time and the external world carry out gas exchanges.But under too high oxygen atmosphere, fruit/vegetable aerobic respiration can not get moderate inhibition, nutriment can consume in a large number, is also unfavorable for preserving fruit and vegetable utilizing.For vegetable and fruit packaging material, suitable CO
2/ O
2tranmittance is very important to the Reasonable Regulation And Control controlling package interior atmosphere.As can be seen from accompanying drawing 4, three groups of films when low temperature to CO
2/ O
2selective penetrated property higher than room temperature time, and PE and PA/PE is to CO
2/ O
2tranmittance is less than PCL film.Under the environment of temperature 5 DEG C, the CO of PCL film
2transit dose reaches 5029mL/m
224h is 26 times of PA/PE film, 1/2 of PE film.Oxygen transit dose reaches 429mL/m
224h is 12 times of PA/PE film, 1/4 of PE film.CO
2/ O
2selecting tranmittance up to 10.22, is more than 2 times of PA/PE and PE film.Suitable CO
2/ O
2transit dose and selection tranmittance can regulate and control atmosphere change in packaging and be conducive to preserving fruit and vegetable utilizing.PCL film has good O
2and CO
2permeability and higher CO
2/ O
2select tranmittance, be very beneficial for strawberry packaging.
II, strawberry are in the fruit state of storage period
Fig. 5 is the strawberry of packing with the Different Package bag fruit state diagram at storage period.Can be known by Fig. 5, the strawberry of packing with PCL still kept good fruit state the 14th, the 22nd day time.The strawberry of blank group is rotten at the 10th day rots, and completely loses edibility.The strawberry of packing with PA/PE and PE condensed water droplet from second day in its bag, and within the 8th day, strawberry starts to occur locally corruption with position contact that condenses.PA/PE poor air permeability, fails adjust internal atmosphere change in time and cause strawberry anuerobic respiration to aggravate, produces ethanol and go bad.The CO of PE
2/ O
2tranmittance is selected to be about 4.6, but due to CO
2and O
2permeability comparatively large and fail to play atmosphere regulating action, and its water vapo(u)r transmission is poor, and condense generations in a large number, causes careless enzyme corruption.There is not dew condensation phenomenon because PCL packaging bag of the present invention has good water vapor permeance, keep sense organ and the trophic level of strawberry well.Meanwhile, because the carbon dioxide/oxygen tranmittance of PCL bag of the present invention is 8.1-10.2, more much higher than PE, therefore PCL bag of the present invention can very well realize atmosphere regulating action, suppresses the respiration of strawberry, thus can greatly extend its shelf-life.
III, strawberry are at the quality comparison of storage period
Strawberry sees accompanying drawing 6 at the quality comparison of storage period in different packaging bags.
I, strawberry sense organ change
Accompanying drawing 6a is the variation diagram of strawberry sense organ with the storage time, can be known by accompanying drawing 6a, at storage period, each subjective appreciation score of PCL group is higher than other group, unpacked blank group sensory evaluation scores declines the rapidest, is secondly the poor PE film of PA/PE composite membrane that barrier is higher and poisture-penetrability.
PCL group can keep good sensory modalities the long period, because its poisture-penetrability is good, does not occur dew condensation phenomenon, slow down the corruption of strawberry, in addition, and the O of PCL of the present invention
2and CO
2permeability can make the high-load CO that in this packaging bag, long-time maintenance is stable
2, low content O
2environment, the respiratory rate of strawberry is slowed down, extend storage period.The sensory modalities of blank group declines rapidly, and its reason is that strawberry exposes in atmosphere, and water loss is very fast, and contacts easy microbial contamination with air, and strawberry will be wilted at short notice and be gone mouldy.The strawberry of PA/PE group due to its gas-premeable poor, section between initial, the O in bag
2be consumed rapidly because of aerobic respiration, strawberry breathes and transfers anaerobic respiration to very soon, so produce alcohol, and injury strawberry tissue; Secondly, this film poisture-penetrability is poor, produces and condenses in a large number, accelerates strawberry and rots, so sensory modalities declines.Although PE film gas-premeable is better, poisture-penetrability is poor, and strawberry occurs dew condensation phenomenon at duration of storage, and with condensation contact site, strawberry occurs that local is corrupt, therefore sensory modalities also declines.
Ii, strawberry weightlessness
Its water loss in the main cause of duration of storage strawberry weightlessness.Accompanying drawing 6b is the weightless variation diagram with the storage time of strawberry, and can be known by accompanying drawing 6b, the weight-loss ratio of PA/PE film packages groups and PE film packages groups is minimum comes from its poor water vapo(u)r transmission, and the moisture that transpiration produces not easily scatters and disappears.The strawberry weight-loss ratio of PCL film packaging is higher than PA/PE film and PE film packages groups, but lower than blank group, this illustrates that PCL film effectively can delay scattering and disappearing of moisture in strawberry.
Iii, strawberry hardness
Firmness change depends primarily on the change of moisture and the integrality of institutional framework in strawberry.Accompanying drawing 6c is the variation diagram of strawberry hardness with the storage time, can be known by accompanying drawing 6c, and blank group hardness declines the rapidest, this is because strawberry moisture can run off in a large number, also because its institutional framework can be subject to microbial destruction.For PA/PE group and PE group, their institutional framework is damaged under the effect of anaerobic respiration product alcohol, and its hardness declines obviously.For PCL group of the present invention, under strawberry is in comparatively suitable atmospheric condition, aerobic respiration and maturation are suppressed to a certain extent, so hardness underspeeds slowly.
Iv, ascorbic acid content
Ascorbic acid content in strawberry can decline gradually under oxidation.Accompanying drawing 6d is the variation diagram of strawberry ascorbic acid content with the storage time, can be known by accompanying drawing 6d, and it is more that PE group and the strawberry of blank group contact oxygen, and ascorbic acid content declines the fastest.PA/PE group, due to anuerobic respiration, organizes the loss rotting to accelerate ascorbic acid.PCL group strawberry preservation is effective, and bag internal oxygen Gas content is comparatively few in air and PE bag, and ascorbic acid declines slowly.
V, soluble solid
In the present invention, soluble solid should be all general names being dissolved in the compound of water in strawberry, comprising sugar, acid, vitamin, mineral matter etc., based on soluble sugar.In duration of storage strawberry, soluble solid content rises with storage time, and this is because selected not full ripe strawberry is ripe at duration of storage, causes Starch Conversion to be soluble sugar, causes soluble solid content to increase.Accompanying drawing 6e is the variation diagram of strawberry solid content with the storage time.Tend to be steady after the soluble solids content of blank group and PA/PE group rises rapidly, and the lasting rising of the soluble solids content duration of storage of PE and PCL group.The rate of climb is not both the CO due to respective residing environment
2and O
2ratio is different, and respiratory rate speed is different, and ripe speed is different.
According to the embodiment of the present embodiment, to stretch ratio be 3,3.5,4.2 with 4.6 PCL film carry out same strawberry preservation and test, the result obtained is close with the result of the present embodiment.
Claims (8)
1. have a Wholly-degradable pla-pcl film for spontaneous controlled atmosphere function, it is characterized in that described Wholly-degradable pla-pcl film is the Wholly-degradable pla-pcl film of single shaft longitudinal stretching, it has following characteristic:
A, thermal property
Melt temperature T
m: 62.8-64.1 DEG C; Heat content Δ H
m: 68.0-68.4J/g; Uniaxial tension compares: 3-5;
B, mechanical property
The longitudinal mechanical performance of film:
Yield strength σ
s: 19.7-90.8MPa; Elongation at break Δ: 73-179%;
Young's modulus Y:274-343MPa;
The horizontal mechanical performance of film:
Yield strength σ
s: 17.5-18.7MPa; Elongation at break Δ: 270-648%;
Young's modulus Y:208-485MPa;
C, air permeable performance
Adopt coulomb coulometry to measure under the test condition of thickness 50-103 micron, relative humidity 40-70% and temperature 23 DEG C, its OTR oxygen transmission rate is 345-1460cm
3m
-2d
-1; Oxygen transmission coefficient is 4.65-8.63 × 10
-13cm
3mm
-2s
-1pa
-1; Water vapour permeability is 384-840gm
-2d
-1; Steam transmission coefficient is 2.08-3.61 × 10
-10gmm
-2s
-1pa
-1;
Adopt pressure differential method to measure under relative humidity 0% with the test condition of temperature 5-23 DEG C, its carbon dioxide transmission rate is 5028-11204cm
3m
-2d
-1; OTR oxygen transmission rate is 492-1501cm
3m
-2d
-1; Carbon dioxide/oxygen tranmittance is 8.1-10.2.
2. Wholly-degradable pla-pcl film according to claim 1, is characterized in that described Wholly-degradable pla-pcl film has following characteristic:
A, thermal property
Melt temperature T
m: 62.8-64.1 DEG C; Heat content Δ H
m: 68.0-68.4J/g; Uniaxial tension compares: 3-5;
B, mechanical property
The longitudinal mechanical performance of film:
Yield strength σ
s: 30-70MPa; Elongation at break Δ: 90-150%;
Young's modulus Y:290-310MPa;
The horizontal mechanical performance of film:
Yield strength σ
s: 17.5-18.7MPa; Elongation at break Δ: 400-520%;
Young's modulus Y:290-405MPa;
C, air permeable performance
Adopt coulomb coulometry to measure in the test condition of thickness 50-103 micron, relative humidity 40-70% and temperature 23 DEG C, its OTR oxygen transmission rate is 650-1160cm
3m
-2d
-1; Oxygen transmission coefficient is 4.90-8.20 × 10
-13cm
3mm
-2s
-1pa
-1; Water vapour permeability is 480-740gm
-2d
-1; Steam transmission coefficient is 2.40-3.20 × 10
-10gmm
-2s
-1pa
-1;
Adopt pressure differential method in relative humidity 0% with under the test condition of temperature 5-23 DEG C, the transmitance of carbon dioxide is 6000-10200cm
3m
-2d
-1; OTR oxygen transmission rate is 692-1200cm
3m
-2d
-1; Carbon dioxide/oxygen tranmittance is 8.8-9.5.
3. the production method with the Wholly-degradable pla-pcl film of spontaneous controlled atmosphere function according to claim 1, is characterized in that the step of the method is as follows:
Allow polycaprolactone master batch in vacuum drying chamber under temperature 35-45 DEG C with the condition of vacuum 0.1-0.5MPa dry 6-10 hour; Then, dry polycaprolactone master batch injects twin (double) screw extruder, twin-screw group temperature is adjusted to 60 DEG C ~ 150 DEG C successively, die head extrusion temperature is 150 DEG C, melt extrude under these conditions, casting roller forms slab, during by regulating the rotating speed of stationary roll and mobile roller to reach uniaxial tension than 3-5, longitudinal stretching is carried out, so obtain the Wholly-degradable pla-pcl film of single shaft longitudinal stretching under the condition of temperature 40 DEG C.
4. production method according to claim 3, is characterized in that the draw ratio of the Wholly-degradable pla-pcl film of single shaft longitudinal stretching is obtained by following formulae discovery:
In formula:
R represents draw ratio;
S
mrepresent the rotating speed of mobile roller;
S
frepresent the rotating speed of stationary roll.
5. the Wholly-degradable pla-pcl film with spontaneous controlled atmosphere function according to claim 1 is producing the purposes in fresh fruit vegetables packing material.
6. purposes according to claim 5, is characterized in that described fresh fruit is strawberry.
7. purposes according to claim 6, is characterized in that in strawberry storage period, CO in the packaging bag made from Wholly-degradable pla-pcl film described in claim 1
2concentration remains in body 2 ~ 5, O
2concentration remains on by volume 3 ~ 7, thus keeps the desirable atmosphere composition of strawberry preservation.
8. purposes according to claim 7, during the packaging bags strawberry that it is characterized in that using Wholly-degradable pla-pcl film described in claim 1 to make, strawberry shelf life reaches 20-28 days.
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|---|---|---|---|
| CN201510397558.2A CN105150510B (en) | 2015-07-08 | 2015-07-08 | A kind of Wholly-degradable pla-pcl film and its production method and its purposes |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108017888A (en) * | 2017-12-02 | 2018-05-11 | 无锡福尔顺科技有限公司 | One kind sealing polycaprolactone pack case and its application |
| CN111735707A (en) * | 2020-06-29 | 2020-10-02 | 天津市捷威动力工业有限公司 | Method and device for testing packaging strength of lithium ion soft package battery |
| CN113207600A (en) * | 2021-05-19 | 2021-08-06 | 河南青源天仁生物技术有限公司 | Peanut planting method with full-biodegradable mulching film covering |
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| JPS60219080A (en) * | 1984-04-16 | 1985-11-01 | Mitsui Toatsu Chem Inc | Production of film for typing ribbon |
| JPH11320674A (en) * | 1998-03-19 | 1999-11-24 | Agency Of Ind Science & Technol | Method for stretching process of aliphatic polyester sheet |
| CN101440165A (en) * | 2007-11-19 | 2009-05-27 | 上海华酝化工科技有限公司 | Biodegradable flexible polylactic acid alloy film and preparation thereof |
| CN101649072A (en) * | 2009-09-22 | 2010-02-17 | 任伟 | Full-degradable biological material and film product thereof |
| TW201446470A (en) * | 2011-03-29 | 2014-12-16 | Kuraray Co | Manufacture method for polarizing film |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60219080A (en) * | 1984-04-16 | 1985-11-01 | Mitsui Toatsu Chem Inc | Production of film for typing ribbon |
| JPH11320674A (en) * | 1998-03-19 | 1999-11-24 | Agency Of Ind Science & Technol | Method for stretching process of aliphatic polyester sheet |
| CN101440165A (en) * | 2007-11-19 | 2009-05-27 | 上海华酝化工科技有限公司 | Biodegradable flexible polylactic acid alloy film and preparation thereof |
| CN101649072A (en) * | 2009-09-22 | 2010-02-17 | 任伟 | Full-degradable biological material and film product thereof |
| TW201446470A (en) * | 2011-03-29 | 2014-12-16 | Kuraray Co | Manufacture method for polarizing film |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108017888A (en) * | 2017-12-02 | 2018-05-11 | 无锡福尔顺科技有限公司 | One kind sealing polycaprolactone pack case and its application |
| CN111735707A (en) * | 2020-06-29 | 2020-10-02 | 天津市捷威动力工业有限公司 | Method and device for testing packaging strength of lithium ion soft package battery |
| CN113207600A (en) * | 2021-05-19 | 2021-08-06 | 河南青源天仁生物技术有限公司 | Peanut planting method with full-biodegradable mulching film covering |
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| Publication number | Publication date |
|---|---|
| CN105150510B (en) | 2018-03-16 |
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